Note: Descriptions are shown in the official language in which they were submitted.
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TITLE: BIO-RENEWABLE THERMAL ENERGY HEATING AND
COOLING SYSTEM AND METHOD
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims priority under 35 U.S.C. 119 of a provisional
application Serial No. 60/804,148 filed June 6, 2006, which application is
hereby
incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
U.S. Patent 7,040,108 ('108) described a method of recovering thermal energy
from
various environments and utilizing it in a process or storing it for later
use. The basic
configuration in the '108 patent utilized a single evaporator and water cooled
condenser
with a compressor, expansion device, receiver, circulating pump and hot
storage tank. This
patent emphasized the heating capability of the refrigeration process and
extended the use
of refrigeration technology towards the maximum utilization of the
refrigeration cycle for
its heating affects within a given application. The refrigeration cycle was
defined as a
process involving a compressor, heat exchanger (condenser), expansion device,
and
evaporator. Thermal energy was to be collected in the evaporator from air or
from liquids
or slurries and was generally to be placed into a liquid stream or storage
device where it
could also be used to heat a space or process. The'108 system operated in a
single mode,
that is, reclamation.
SUMMARY OF THE INVENTION
The present invention extends the teaching of U.S. Patent 7,040,108 to include
a
formula or methodology for application of the refrigeration process to further
enhance or
optimize the utilization and control of refrigeration for the transformation
of thermal
energy available in one environment/media to another environment/media. This
is not the
simple transfer of thermal energy from location to location but the efficient
transformation
of thermal energy from one condition to one or more conditions desirable for a
given
application. This is accomplished through the balancing of the environmental
variables
with the properties of the refrigerant and the capabilities of the compressor.
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For example, in a meat processing facility, chillers are used to maintain
workplace
temperatures that are suitable for safe processing of the meat and boilers are
used to heat
kill process water and wash water. The system of the present invention will
provide the
chilling while also providing a fixed temperature of liquid refrigerant to the
expansion
device and generating heated water for the kill process and the wash down. The
fixed
liquid refrigerant temperature helps to optimize the performance of the
compressor where
most chiller condensers are currently exposed to the variability of the
ambient air
temperature which will cause compressor performance to vary off of the optimal
condition.
The combination of compressor configuration, refrigerant, condenser
configuration,
expansion device/configuration, and evaporator configuration are driven by the
requirements of the application and the nature of the refrigerant selected.
One goal of the
system configuration is to achieve the most desirable balance of refrigerant
and lubricant.
conditions at the compressor while optimally utilizing thermal energy sources
and thermal
energy sinks available in the application.
With this teaching and methodology the use of refrigeration for heating and
cooling
is extended to new horizons whereby with new refrigerants and refrigeration
system
configurations we will have capability to displace a significant portion of
the world's
combustion based fiarnace or boiler capacity, while providing refrigeration or
cooling to the
same application. This technology may also lead to the co-location of
complimentary
energy-intensive applications to help reduce or eliminate dependence on
external fuel
sources.
One aspect of the present invention is the utilization of multiple evaporators
and
multiple condensers tied to a single compressor so as to increase the
utilization of waste
heat.
In another aspect of the present invention, refrigerant heat is split for
multiple uses.
For example, the heat can be used for generating water, liquid or steam that
is hotter than
the condensing temperature of the refrigerant. Producing steam represents use
of the hot
path to produce a phase change on the environment side of the refrigeration
process.
In another aspect of the present invention, a circulating loop with a water
tank,
pump and a condenser/heat exchanger provides control to the head pressure, so
as to
provide control and storage of higher temperature fluid, and to control the
subcooling -
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temperature for the improvement of the evaporator heat collection capacity,
and to uniquely
improve compressor efficiency. While subcooling has been used in the prior
art, such use
is provided by robbing a portion of the system refrigerant to cool the
remaining liquid
refrigerant prior to introduction into the expansion device to help improve
heat collection
capacity in the evaporator. In=comparison, the present invention uses water or
a process
stream to do this subcooling, rather than the refrigerant. This improves
performance by
collecting additional useful heat in the process stream through the subcooling
of the
refrigerant, as well as boosting the heat collection efficiency of the
evaporator. A
circulating loop provides the basis for control of subcooling conditions to
maintain higher
compressor efficiency.
Another aspect of the present invention relates to desuperheating, which is
known
in the prior art, but only for the purpose of extracting the heat available
from the superheat
in the high temperature refrigerant vapor to heat water, while the remainder
of the heat is
rejected. The present invention utilizes the full heat path towards heating a
liquid prior to
allowing rejection or switching to a heating application from a secondary
priority, which is
unique, and specifically not in conjunction with a circulating and storage
loop used for
process control. This invention utilizes the full heat path as a priority and
utilizes the
desuperheating segment to produce and/or store water or fluid at temperatures
above the
condensing temperature of the refrigerant before allowing rejection or lower
priority use.
Splitting the refrigerant hot side for various uses or controls significantly
advances energy
utilization beyond the prior art, which focused on rejection of the
refrigeration heat.
A further aspect of the present invention is the splitting of the cold side of
the
refrigeration process, in conjunction with splitting of the hot side.
Evaporators in series or
in parallel provide certain challenges, such as control of pressure in the
suction line when
two parallel evaporators operate at different temperatures and pressures.
Evaporators in
series are a challenge to supply cooling at temperatures that are suitable for
both
environments, since the outlet temperature drives the control of the
temperature of the
refrigerant in all evaporators.
With the system of the present invention operating in the reclamation and
cogeneration mode, a significant thermal emission reduction is provided, since
the thermal
energy that previously was going to be wasted is now recycled back into the
bio-renewable
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process. The formula that has been developed for controlling the environmental
balance is
premised upon the first and second laws of thermodynamics, so as to balance
the energy of
the system of the present invention from both the refrigerant and
environmental
perspectives, thereby achieving results and control of process beyond
traditional
refrigeration processes.
The system has the ability to heat potable water, cool interior space areas,
use the
hot water for heating interior space areas, recycle thermal energy by cooling
one area while
heating a second area, and save significant amounts of energy while completing
these tasks.
A three-way reclaim valve is used to switch between the water-cooled condenser
and the external condenser. This valve along with a check valve draws the
refrigerant out
of the external condenser and back into the system and keep the refrigerant
from pooling in
the external condenser. This allowed the system to provide heating, cooling
and water
heating.
The ability to control the condensing temperature at the temperature of the
water
tank via the circulation system is a unique characteristic. The use of water
for control,
while also using the heat for useful heating, is unique. The temperature of
the water in the
tank sets the head pressure of the compressor (i.e. corresponding to the
condensing
temperature of the refrigerant).
The limitation of the single condenser, is overcome with a system that used
two
condensers in series each with its own tank and circulating system. This
allows the first
condenser to absorb all of the energy it could before the second heat
exchanger begins to
absorb energy. As the first heat exchanger system reaches the maximum
condensing
temperature, the majority of the heat is being captured by the second heat
exchanger. As
the system continues to operate, the water in the first circulation loop
becomes hotter than
the condensing temperature and the refrigerant entering the second heat
exchanger is now
accepting some superheated vapor refrigerant. The temperature of the first
loop is above
the condensing temperature of the refrigerant. This allows the system to heat
water to over
200F in a batch mode operation.
For continuous mode operation, cold water is introduced at the inlet of the
circulating pump of the second circulating loop to allow the system to operate
at a
condensing temperature attributable to the mixture temperature of the hot
water in the tank
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and the cold water entering the system. This allows the system to operate at
lower head
pressures while generating higher temperatures. A reciprocating compressor
operating on
R22 can operate in continuous flow mode at temperatures as high as 130F
without
exceeding acceptable head pressures. This would be the result whether the
system had one
or two condensers. Applicants call the phenomenon tempering.
The same flow strategy is also applied to the hot water entering the first
circulating
loop. If the hot water is introduced at the suction of the circulating pump,
the first
condenser sees a mixture temperature that is lower than the tank temperature.
Thus the
system can absorb more heat at a given condition in the first condenser due to
the greater
temperature differential. The first circulating loop controls the head
pressure of the
compressor, thereby increasing compressor efficiency.
The system performs better when the first condenser circulating loop is at or
below
the maximum condensing temperature of the refrigerant in the system -- which
for the
given system was around 125F -- and the second circulating loop is still
relatively cool.
The second loop is removing additional heat and sub-cooling the liquid
refrigerant. The
second circulating loop controls refrigerant subcooling, which also improves
efficiency of
the compressor.
Subcooling provides two benefits:
1. The system gains the heat of subcooling for useful heating of the water.
2. When the refrigerant is expanded in the TX valve there are fewer flash gas
losses (i.e. there is more liquid refrigerant to boil in the mixture inside of
the
evaporator and the heat transfer into the evaporator can be increased).
A third circulating loop may be provided for controlling desuperheating.
Thus, a second use for the dual condenser mode operation is to provide
subcooling
to increase the capacity of the system. It then follows that a third condenser
can be used to
provide both the ability to heat liquid to higher temperatures and subcool the
refrigerant for
the same system, yielding improved system performance.
Use of multiple evaporators and multiple condensers in parallel circuits to
provide
any combination of heating and/or cooling and the use of multiple condensers
and
circulating loops in series within a circuit can be expanded for use of
configurations in
whatever capacity is needed. Any number of circuits can be applied or any
number of
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condensers or evaporators in series to not only satisfy the requirements of
any application
but to optimize the utilization of the refrigeration system and maximize the
cost benefit of
the system installation for a given application.
Thus, a formula has been developed which describes the nature of the system in
terms of both its physical and economic variables. Since a refrigeration
system has never
been applied in this manner, this formula is unique and describes the nature
of the system
for a wide variety of applications. The formula parameters allow the system to
be
evaluated as a viable alternative in the thermal energy infrastructure of the
world.
The thennodynamic formula inputs bio energy in the form of ambient air and
recycled energy balanced on the capacity of the refrigerant and the compressor
by first
applying the energy into the application and rejecting the remaining energy in
order to
balance on the capacity of the refrigerant and compressor to all new levels.
As used in this application, "environmental thermal energy" is defined as
thermal
energy that is available and exists naturally or has been released to an
environment by an
exothermic process.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a schematic drawing of a basic prior art heating, cooling and hot
water
configuration according to the'108 patent.
Figure 2 is a schematic drawing of another embodiment of a prior art basic
heating,
cooling and hot water configuration according to the'108 patent.
Figure 3 is a schematic drawing of an embodiment of a basic heating, cooling
and
hot water configuration according to the present invention. .
Figure 4 is a schematic view of an embodiment of the present invention showing
heating, cooling and hot water utilizing multiple heat sinks.
Figures 5A and 5B are schematic drawings showing alternative embodiments of a
heating, cooling and hot water system having a warm water heat sink according
to the
present invention.
Figure 6 is a schematic drawing of another embodiment of a heating, cooling
and
hot water system having thermal loops and thermal storage according to the
present
invention.
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Figure 7 is a schematic drawing of yet another embodiment of a heating,
cooling
and hot water system with mixed superheat cogeneration and rejection according
to the
present invention.
Figure 8 is a schematic drawing of still another embodiment of a heating,
cooling
and hot water system utilizing superheated liquid according to the present
invention.
Figures 9 and 10 are schematic drawings of further embodiments of a heating,
cooling and hot water system with subcooled liquid according to the present
invention.
Figure 11 is a schematic drawing of another embodiment of a heating, cooling
and
hot water system with superheated heated liquid and supercooling according to
the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Formula for controIIing environmental balance with the refrigeration cycle.
Applicants have developed a universal formula necessary for balancing the co-
generation of heat and cold within the refrigeration cycle with the
constraints of two (or
more) environments to be affected or controlled by the refrigeration process.
The variables must be balanced relative to the requirements of a given
application
of the system. The first consideration is the choice of a refrigerant that has
physical
properties that will allow evaporation and condensation at temperatures that
meet the
demands of the application within the compression ratio and operating
temperature
limitations of available compressors and compressor oils. There are many
materials and
mixtures of materials having refrigerant characteristics. As a broader array
of application
conditions are considered, new refrigerants will be selected or created to
harness the
efficiencies of the refrigeration cycle. Once a suitable refrigerant is
selected, the formula
can be applied along with the appropriate engineering principles to select or
design the
refrigeration system components that will properly balance the refrigeration
cycle and
withstand the rigors of the application.
The basic formula can be written in a number of formats. For a refrigeration
process using direct expansion in terms of the application environments and
electricity use:
(1) Desired change in environmental conditions at location of evaporators -
Evaporator
side piping losses and heat gain + Electricity consumed - Compressor and motor
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losses = Desired change in environmental conditions at location of condensers -
Condenser side piping and heat losses.
This relationship can also be represented in terms of the of the refrigeration
cycle
itself. For example, equation I can be written as follows:
(2) Evaporator energy collected - Evaporator side piping losses and heat gain
+
Compressor work = Condenser energy rejected - Condenser side piping and heat
losses.
These relationships share the following sub-relationships:
(3) Evaporation energy collected = Desired change in environmental conditions
at
location of evaporators.
(4) Condensation energy rejected = Desired change in environmental conditions
at
location of condensers.
(5) Compressor work = Electricity consumed - Compressor and motor losses.
The generic terms utilized in the foregoing equations will be derived in the
terms of
the specific application or refrigeration cycle and will conform to the laws
of the
conservation of mass and energy with consideration of the significant losses.
These
equations are utilized to determine the practical scale and configuration of
refrigeration
system that will maximize the utilization of both heating and cooling
resources while the
refrigeration cycle is in operation and thus maximize the overall benefit of
the installed
system.
The formulae provides the basis for designing the system to match the
environmental requirements with the refrigeration system requirements and
optimize
operating efficiency for simultaneously utilizing both the heating and cooling
sides of the
refrigeration cycle. In comparison, the goal of prior art systems was
generally to maximize
performance while satisfying either the heating or the cooling side.
Classes of refrigeration application.
There are three classes of refrigeration application based on the utilization
and
efficiency of the refrigeration process: Rejection, Reclamation, and
Cogeneration.
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A. Reiection
Historically, the majority of refrigeration applications fall into the
rejection class.
In rejection, one side of the refrigeration process is always wasted. For
example, an air
conditioner transports heat from inside of a building to the outdoors. The
desired benefit is
the cooling of the space, while the heat (including the electricity used to
run the machine)
is displaced or rejected to the environment. Similarly most refrigerators,
chillers, and
freezers will simply reject the heat they are collecting to the environment
where the
condenser is located without consideration of the utilization of the heat for
any useful
purpose. An air to air heat pump is similar in that it cools the space while
rejecting heat in
the summer, and heats the space while rejecting cold in the winter. Rejection
refrigeration
systems are the least efficient systems since they utilize energy to either
heat or cool, but
never both. Rejection systems have their place since they provide value to a
process that
pays for itself through product protection or production. In many applications
however,
rejection systems such as chillers and freezers exist along side of boilers or
furnaces which
provide space and process heating based on combustion. These applications are
candidates
for conversion to reclamation or cogeneration refrigeration.
B. Reclamation
With volatility in energy prices, and uncertainty regarding the balance
between
energy supply and energy demand, more and more refrigeration systems are
utilizing some
form of reclamation. In reclamation, some portion of the heating or cooling
that may have
historically been rejected is captured and reused for some useful purpose.
Collecting heat
from a waste stream of an application and using it to heat water, space, or
some other
process stream in the application is reclamation, as described in U.S. Patent
No. 7,040,108.
Collecting heat from the exhaust of an animal confinement to heat the
confinement or
collecting heat out of the waste water or drier vent exhaust of a laundry to
heat wash water
are specific examples. In reclamation, the refrigeration system is often
designed or
optimized for utilization of one side of the refrigeration cycle while the
other side is
utilized as much as possible, but not necessarily all of the time or to the
fullest extent
possible.
The time dependent nature of many processes and the change of seasons is
accommodated by the present invention wherein the refrigeration process is
designed with
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additional flexibility to allow it to be utilized more efficiently and to a
greater extent within
a given application, including the need for multiple evaporators and multiple
condensers to
meet the priorities and time dependent requirements of the application. A
reclamation
application may include periods of operation where priorities require
rejection and may at
times operate in cogeneration mode (discussed below). For example, Applicants'
system
installed in a home will operate in cogeneration mode when heating potable
water while
providing comfort cooling. The same system will however switch to rejection
mode when
the potable water is heated to its limits and more comfort cooling is
required. If in the
same home application, the external evaporator is positioned so that it can
take advantage
of the drier exhaust and bathroom and oven exhaust fans then the system will
operate in
reclamation mode during the heating season or while heating water during the
cooling
season when there is no call for comfort cooling. Since the system is capable
of operating
in this variety of modes, it enjoys the potential of annual performance that
exceeds that of
many conventional refrigeration based heating or cooling systems. Several
examples of
reclamation configurations are described below with respect to the drawings. A
unique
characteristic of each of these systems is that when it operates in
reclamation mode, it
utilizes 100% of the heating side of the refrigeration cycle. Most reclamation
systems only
utilize a fraction of the heating capacity. A home heating and cooling system
falls into the
reclamation category since it may at times use rejection, reclamation or
cogeneration,
which is better than pure rejection but not as good as pure cogeneration.
Cogeneration
When both the cooling and the heating side of the refrigeration cycle are
fully
utilized within a process, the application is called cogeneration. As
mentioned in the
reclaxnation section above, an example of cogeneration is when a refrigeration
system is
used to provide comfort cooling while heating potable water. This effective
utilization of
the resource can be extended in a housing or hotel application if the same
system can be
used to heat a swimming pool and/or hot tub. However, due to daily and
seasonal
variability in outdoor atmospheric conditions, housing applications are rarely
pure
cogeneration applications. Pure cogeneration applications will mostly be found
in
agricultural, commercial and industrial applications where both cooling and
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used to produce a product. In an ethanol plant for example, heat rejected from
the cooked
mash on its way to fermentation or from the fermentation process itself may be
collected
and used to heat the cook water or to heat the condensate returns for the
boiler. In the
future, advances in refrigerants and refrigeration equipment may allow
refrigeration
systems to operate at temperatures that will allow refrigeration systems to
displace the
boiler. Power plants, bio-diesel plants, chemical and petroleum refineries,
commercial
laundry/dry cleaners and a host of other energy intensive process oriented
industries
provide opportunities for cogeneration with a refrigeration system.
The configurations shown in the drawings are examples of refrigeration systems
where the formulae described above are used to maximize the reclamation and
cogeneration opportunities in an application.
The goal is to maximize utilization of a balanced refrigeration cycle in a
configuration that will minimize energy consumption and maximize efficiency
and value to
the application. The systems are able to utilize the optimal combination of
rejection,
reclamation, and cogeneration as driven by the requirements and limitations
imposed by
the application. The systems are capable of utilizing all three classes of
operation within
the same installation.
The bio-renewable reverse thermal energy nature of the system
Historically the refrigeration process has been thought of as a simple
transferring of
energy from one location to another at the expense of electricity to operate
the compressor.
The present invention endeavors not to simply transfer thermal energy, but
through controls
and system design, to transform thermal energy relative to its most desirable
condition in a
specific application given the constraints and capabilities of the
refrigerant, compressor oil
and the equipment. This is evident for example in the ethanol process
described previously
as an example of cogeneration. The fermentation process requires a fixed 95 F
while the
cooked mash is held at 180 F. Fermentation gives off heat as the bacteria
metabolize sugar
into alcohol. The mash is maintained (excess heat is collected) by the system
and
transformed into 130 F to 180 F water depending on the design of the
refrigeration
process.
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The invention is capable of transforming electricity from any source into
thermal
"bio-energy" through reuse of thermal energy that would historically have been
wasted to
the environment and through reduction of toxic emissions associated with
conventional
combustion based heating systems. For example, in a conventional ethanol
plant, the cook
water is heated using a natural gas, coal, or biomass fired boiler. The excess
heat in the
cooked mash must be removed before it can be prepared for the fermentation
process. This
historically has involved use of heat exchangers to provide heating to other
parts of the
process but also requires additional cooling either from a chiller or cooling
tower to finish
the cooling process, since the mash must be colder than most other stages of
the ethanol
production process. This is also true for maintaining the fermentation process
at 95 F.
Thus a fuel is burned to heat a process stream and the heat is then rejected
to the
environment, or a biological process creates excess heat which is rejected to
the
environment. This mode of operation is prevalent in most industries today
because
historical energy prices and energy supplies have allowed it and until now
there has not
been an economical way to utilize the low grade "waste" heat. With Applicants'
system
= however, the energy that would be wasted can be reclaimed to provide the
desired cooling
and heating affects simultaneously. Also, as technology and refrigerants
advance, it will be
possible to more precisely match the desired operating conditions on both
sides of the
refrigeration cycle.
The system displaces direct fired sources of heating and their associated
emissions.
Since the wasted energy and solid and gaseous emissions would have otherwise
been
emitted into the environment, the thermal energy reclaimed by the new,
inventive system is
bio-energy. A bio-energy system also exists when the energy that is reclaimed
is derived
from living organisms (such as in animal confinements, alcohol producing
bacteria or
incubating eggs). The system will inherently displace carbon dioxide (C02),
carbon
monoxide (CO), and nitrogen oxide (NO,,) emissions from all carbon based
combustion
processes and it will displace sulfur dioxide, mercury and ash emissions from
oil, coal,
solid waste or biomass combustion. Given the system displacement or reduction
of C02,
SO2 and other emissions, it may be possible in the future to qualify projects
for the
production of emissions credits (currently SO2, NOx, Hg, and C02) which have a
marketable value in the present U.S. cap and trade emissions reduction
strategy. The
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extent of the displacement of emissions and the ecological impact is measured
relative to
the renewable energy nature of the system within an application at a specific
location.
The renewable nature of this bio-energy can be derived by comparing the
efficiency
of the system with the efficiency of thermal power plants that generate the
electricity for
the application site. Thermal plants include fossil fuel fired plants, nuclear
plants, biomass
fired plants, solar thermal plants and geothermal plants. All of these types
of generation
emit significant amounts of waste heat into the environment, and the
combustion based
systems produce large quantities of combustion products that contribute to air
and water
pollution. The efficiency of thermal generating plants is characterized by the
heat rate
which is defined as the Btu input of fuel (or thermal energy) per kWh of
electricity output.
The system operation in reclamation or rejection mode can similarly be
characterized as the
Btu of heat output per kWh of electricity input (the reverse thermal
characteristic). If the
system performance (Btu output/kWh input) is greater than the average heat
rate (Btu
input/kWh output) of the thermal electrical generating system, then the ratio
of the two
represents the renewable contribution of the system operation.
For example, if Applicants' system operates at 12,000 Btu heat output per kWh
electricity input while the thermal generating system is producing electricity
at 9,000
Btu/kWh, then the Applicants' system is contributing (12,000/9,000 - 1)*100 =
33%
renewable thermal energy (i.e. 1 unit of energy provides 1.33 units of energy
for a desired
purpose). The average local Btu/kWh heat rate of the generating system will
vary as
different generating units with different efficiencies are used to meet load.
So the
renewable energy contribution will vary over time as the heat rate of the
generating system
varies. However it can be seen that the system provides a new, incentive to
work towards
driving the thermal generating system heat rate to lower values.
To demonstrate the impact of reducing the heat rate for thermal generating
systems,
for example, let's apply a 7000 Btu/kWh thermal generation heat rate. This is
in the range
of newer combined cycle natural gas fired power plants. The renewable energy
contribution of Applicants' system becomes (12000/7000 -1) * 100 = 71.4% (i.e.
I Btu of
energy provides 1.714 Btu of thermal energy). This implies that by shifting
natural gas and
propane use from direct combustion in residential, commercial, and industrial
applications
to use in combined cycle power generation systems while at the same time
applying
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Applicants' system technology, we can significantly reduce the amount of waste
thermal
energy and the amount of combustion products emitted into the environment. To
further
drive this point, assume for example that the renewable energy contribution
formula that is
an alternative to Applicants' system will operate at 100% efficiency (i.e.
subtract 1.0 from
the ratio). In reality, a direct combustion system would usually have a
conversion
efficiency in the range of 80% to 93% which means that an additional 7% to 20%
of the
heat energy that would have been used (and its associated emissions) would
have been lost
to the environment compared to use of the system. Another way to say this is
that one Btu
of natural gas or propane provide 0.8 to 0.93 Btu of useful heating.
Therefore, for the sake
of comparing alternatives, we subtract the efficiency of the direct combustion
system from
the efficiency of the Applicants' combination/combined cycle generating system
to
determine the renewable energy contribution adjusted for the competing
alternative (i.e. if
the alternative is a 93% efficient boiler the renewable contribution is
(12000/7000 -0.93)
* 100 = 78.4%. This implies that the system will produce 1.784 Btu of useful
heating per
Btu of useful heat that would have been provided by a 93% efficient direct
fired boiler.
Applicants' system in a reclamation or cogeneration scenario will typically
operate
in the range of 11260 Btu/kWh to 13650Btu/kWh, and new advances are expected
to
increase the upper limit. As the reverse heat rate increases, the overall bio-
renewable
impact of the system will increase proportionally. A system running at 13650
Btu/kWh
running on electricity from a gas fired combined cycle that will displace a
93% efficient
gas fired boiler will produce a renewable contribution of (13650/7000 - 0.93)
* 100 =
102% (i.e. 2.02 Btu of useful heating will be generated from a Btu of gas
fired in the
combined cycle plant and amplified by the system relative to 0.93 Btu of
useful heating if
the same Btu was directly fired in the 93% efficient boiler).
Since not all electricity generation comes from thermal sources, some
correction
should be made for the affect of non-thermal electricity sources. Non-thermal
renewable
energy sources have little if any airborne or thermal emissions and include
technologies
like wind, wave, hydro and solar photo-voltaic power. The impact of non-
thermal
renewable generation on the Applicants' system renewable contribution will be
proportional to the fraction of the total mix of generation produced from non-
thermal
sources. However, the contribution of the Applicants' reverse thermal process
and system
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relative to a non-thermal electricity source is better described based on the
coefficient of
perfonnance (COP) or Btu of heat output per Btu of electricity used by the
Applicants'
system. The units operating in reclamation and cogeneration mode are generally
capable of
operating at a COP of 3.3 or greater. This level of COP is also possible in
rejection mode,
however the temperature of the heat source such as outdoor air on a very cold
winter day
during the heating season when the system is running in rejection mode can
degrade the
COP to levels as low as 1Ø For example, assume the system is operating in
reclamation
mode at a COP between 3.3 and 4Ø A COP of 3.3 corresponds to a reverse heat
rate of
11262 Btu/kWh while a COP of 4.0 corresponds to a reverse heat rate of 13650
Btu/kWh
(i.e. 11262/3413 = 3.3 and 13652/3413 = 4.0 where 3413 is the conversion
constant
between Btu and kWh (i.e. 1 kWh of electricity will provide 3413 Btu of
thermal heating
from a resistant electric heater). At a COP of 4.0, the unit in reclamation
mode will be
generating 4 Btu of thermal energy for a process for every 1 Btu of
electricity consumed.
Thus, Applicants' system multiplies the thermal capacity of electricity
generated from non-
thermal sources by a ratio equivalent to the COP.
The total renewable contribution of Applicants' system in a generation mix
that
includes non-thermal generation is represented in the following example. Take
the 13562
Btu/kWh RASERS, the natural gas fired combined cycle power plant operating at
7000
Btu/kWh heat rate and a non-thermal renewable energy contribution of 10%
competing
with a 93% efficient direct fired boiler. The renewable energy contribution of
our system
then becomes (13562/(0.9*7000 +0.1 *3413) - 0.93) * 100 = 112.56%. As the
thermal
generation heat rate is reduced and as the non-therrnal contribution is
increased this
formula will be reduced to the COP of the system. The minimum possible heat
rate of the
thermal energy systems is 3413 Btu/kWh since that would mean that they were
operating at
a conversion efficiency of 100% (i.e. 1 kWh = 3413 Btu).
When Applicants' system operates in cogeneration mode, then the renewable
contribution arguably becomes equal to the COP, since the cooling affect would
have been
required regardless of whether the thermal heating affect was utilized or not.
In-other-
words if you produce and use the energy for the cooling affect of the system,
then the
heating affect, if it is fully used, comes for free.
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The above discussion demonstrates that the Applicants' system allows thermal
energy based electricity generation systems to produce bio-renewable thermal
energy when
the conversion efficiency (heat rate) of the electricity generation system is
combined with
the conversion efficiency (reverse heat rate) of the Applicants' system. It
was also shown
that the Applicants' system effectively multiplies the renewable contribution
of non-thermal
renewable electricity sources by the COP of the Applicants' system. Also,
Applicants'
system operated in cogeneration mode has a bio-renewable thermal energy
contribution
equal to the COP of the system.
The assumptions made regarding heat rates and efficiencies are within the
range of
nominal performance for thermal systems in operation today. The renewable
contribution
may infer that the efficiency of the combined system exceeds 100%. However,
Applicants'
system does not create energy, but rather transforms thermal energy that would
normally be
wasted or exhausted into the environment into useful thermal energy. The
refrigeration
cycle, through proper use and control of the phase change properties of a
refrigerant,
amplifies a small input of energy (electricity) into a larger quantity of
thermal energy
available for use in a variety of applications.
There will be additional ecological benefits of displacing direct fired
thermal
heating systems with the Applicants' system besides the reduction in the
emission of
thermal energy and products of combustion. One example is the reduction in use
of
makeup water for boilers and cooling towers or evaporative coolers. Another is
the
reduction in use of scale and biological water treatment chemicals for the
boiler and the
cooling towers. In consideration of all these things, the environmental and
economic
footprint of fossil fuel utilization can be significantly reduced through
implementation of
the Applicants' system. As natural gas and propane used for direct thermal
heating of
onsite industrial, commercial, agricultural, and residential applications is
displaced with
Applicants' system technology, more natural gas and propane will be available
for cleaner,
more efficient combined cycle gas fired electricity generation. Since
Applicants' system
technology generates bio-renewable thermal energy it may also be classified
according to
its bio-renewable nature to allow it to participate in the renewable energy
incentives
programs and renewable energy credit markets with at least the following
benefits:
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(1) capable of reducing the emissions of waste thermal energy and the
products of combustion resulting from fuels used for thermal heating
processes at a rate defined as the renewable energy contribution.
Renewable energy contribution is derived according to the following
formula:
Renewable Energy Contribution % = (RTHR /( REFTH * THPHR - REFNTH
* 3413) - CompEff) * 100
Where:
RTHR = the reverse thermal heat rate of the system, Btu heat output / kWh
electricity input
THPHR = the heat rate of thermal generating plants, Btu heat input / kWh
electricity output
REFTH = Fraction of generation mix provided by thermal plants
REFNTH = Fraction of generation mix provided by non-thermal generation
systems
3413 = conversion from Btu to kWh or the THPHR of a 100% efficient thermal
generating plant
CompEff = conversion efficiency of the thermal energy system that the system
competes with Btu heat output / Btu of fuel fired.
(2) Thermal energy at=efficiencies greater than 100% when the efficiencies of
the =
system reclamation are considered in combination with the efficiency of
thermal
generating plants.
(3) Capable of generating thermal energy at a maximum efficiency defined as
the
coefficient of performance of the system. This occurs when electricity is used
that
is derived from a non-thermal source, when the efficiency of a thermal
generation
source reaches 100% and when the system operates in cogeneration mode. The
Coefficient of Performance is defined as the Btu of energy output divided by
the
Btu of electricity input.
(4) Operating in cogeneration mode produces both heating and cooling at the
cost of
operating the cooling system plus the cost of operating any additional fans,
pumps
or controls required to manage the heating side of the process.
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Three commercial applications of the system
There are a vast array of applications where the Applicants' system can be
applied
to take advantage of its bio-renewable characteristic and its flexibility to
operate efficiently
within the three classes of refrigeration application. From the perspective of
commercialization, there are three broadly defined markets that will benefit
from the
system. A few specific market segments are identified for each (though the
lists are not
intended to be exhaustive).
a. Housing and commercial heating and cooling
= Single Family
= Multi-family
= Hospitality & Dormitory
= Offices
= Retail
= Warehouses/storage
= Non-process facilities (manufacturing, assembly, laboratories, etc.)
= Animal confinements
= Greenhouses and plant nurseries
b. Industrial heating and cooling
= Powder coating and baked on painting operations
= Food processing facilities (meat, dairy, baking, frozen foods, etc.)
= Foundries
c. Inline process
= Ethanol and biodiesel processes
= Power plants
= Applications with both boiler and chiller or cooling tower
= Various chemical, petroleum, drug, and agricultural byproduct refining
processes
= Hatcheries/incubator climate control systems
= Hay, grain or product drying processes
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The new and unique feature of the system technology in these markets is its
flexibility to take advantage of reclamation and cogeneration opportunities in
each
application. Use of the Applicants' system in place of combustion based
technologies has
also been shown to provide residual benefits in specific applications. For
example,
humidity can be better controlled to help reduce potential for disease and
pests or various
process elements can be significantly reduced such as the use of fresh water
for cooling an
incubator. The system will also work in concert with other energy efficient
solutions,
renewable energy systems or energy storage systems to provide an additive or
multiplicative affect. For example, a two pipe heating and cooling system in a
hotel,
hospital, or other commercial facility can be retrofit to include water source
heat pumps in
each unit and Applicants' system that will operate between the boiler and the
chiller to
significantly reduce the rejection mode operation of the chiller and the
combustion of the
boiler. The Applicants' system will use cogeneration to take excess heat in
the loop and
apply it to heating potable water or the swimming pool and hot tub. If the
loop needs
additional heat, the system will use reclamation to take waste heat from the
continuous
exhaust system, waste water or other heat sources in the facility to provide
the needed
heating. The Applicants' system possesses a unique market potential in a broad
range of
applications, some of which are described in the following sections.
Thus, Applicants' system provides flexibility to utilize rejection,
reclamation and
cogeneration in an optimal manner to maximize energy savings and emissions
reductions
for a wide array of applications. Claims for specific applications are listed
at the end of
this patent description. Applicants' system can provide residual benefits such
as reduction
in humidity or reduction in water usage in some applications that can be as
valuable as the
energy savings and emissions reduction benefits.
Specific applications and configurations that demonstrate the three classes of
refrip-eration application and the bio-renewable energy nature of the system
Multi-heat source / multi-heat sink configurations
To allow the Applicants' system to take advantage of reclamation and
cogeneration
opportunities it has been necessary to extend the definition of the system
described in U.S.
Patent 7,040,108 to allow utilization of one or more evaporators and one or
more
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condensers for= a given refrigeration cycle. In the most basic configuration
this allows the
Applicants' system to provide space heating, comfort cooling and potable water
heating in
any facility. The configuration of the evaporators and condensers can be
adjusted from
application to application. Some applications may require only one evaporator
and one
condenser. Some applications may require two or three evaporators and one or
two
condensers. The number and type of evaporators is deterrnined by the
availability and type
of excess, waste or ambient heat resource and the demand for heating or
cooling for the
application. The number and type of condensers is determined by the number and
type of
required heating and cooling demands of the application. The number of
evaporators and
condensers associated with a given unit is also driven by the economics of the
installation
and the timing of the available heat sources and the timing of the heating and
cooling
demands. When heat resources and heating and cooling demand do not occur
simultaneously, it often becomes necessary to consider thermal storage as a
method of
retaining heat or cool for later utilization. In some instances the cooling
demand
consistently exceeds the heating demand in which case storage capacity for
heat can be
reduced by utilizing a higher storage temperature. These concepts are
developed in greater
detail in the following descriptions relating to Figures 1 through 6.
Basic heatinz coolina and hot water confi--urations
Figures 1 and 2 demonstrate basic configurations of the'108 patent. Figure 2
is
similar to Figure 1, and adds the concept of using a heat exchanger and
circulating pump to
remove heat from the storage tank for a purpose such as heating a space or
heating a second
stream. Figures 1 and 2 are practical configurations for applications where
there is a need
for heating based on heat collected from a single ambient source or stream.
These
configurations were however inadequate to provide year-round heating and
cooling for a
home, for example, since the heat source changes from inside of the home
during the
comfort cooling season to the outside for the heating season. In addition, the
cooling load
in a comfort cooling application often exceeds the potable water heating
requirements so a
method of rejecting the extra heat generated by the comfort cooling process is
needed.
Figure 3 demonstrates the use of the three-way reclaim valve and the reclaim
check
valve to switch between the water cooled condenser and the air cooled
condenser. Also
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illustrated is the addition of 2 two-way solenoid valves used to supply liquid
refrigerant to
two evaporators labeled "A-Coil Evaporator" and "Evaporator". Multiple two-way
valves
or three-way valves may be used interchangeably for switching between multiple
condenser
paths or switching between multiple evaporator paths as the application
requires. Care
must be taken to provide a means to reclaim the refrigerant in a given path
that is not in
use, if that path could hold enough volume of liquid refrigerant to starve the
unit while
using other paths. This is particularly an issue for condenser paths. Without
this control,
when the ambient temperature around the condenser drops, the refrigerant will
tend to
migrate to the condenser (condense inside of the condenser) and starve the
unit of
refrigerant. Reclaim is not as important for the evaporator paths since all
evaporators are
tied directly to the suction of the compressor. The three-way reclaim valve
provides a
convenient method of reclaiming refrigerant to the suction of the compressor
from the
reclaim port on the valve. The use of normally open 2-way solenoid valves (if
used) is also
important to avoid having the valves fail closed and causing a deadhead
situation for the
compressor. The use of the 3-way valve is again superior since it will always
have one port
open and will fail open to only one port.
This configuration provides the basic components necessary to provide heating
and
comfort cooling to any facility (home, office, warehouse, factory, etc.) while
also heating
the potable water. The ability to cogenerate by heating potable water while
providing
comfort cooling provides a significant advantage. If the outdoor evaporator
can be located
where it can use reclamation from heated streams leaving the facility, then
the overall
performance of the system can be further improved during the heating season,
and while
heating water when there is no cooling demand.
There are also many applications beyond simple space conditioning and potable
water heating where the second condenser (or third or fourth, etc) and the two
evaporators
(or third or fourth, etc.) can be placed in locations to take advantage of
specific heat
sources and provide useful heating to spaces or processes. Applying multiple
evaporators
and multiple condensers in this way allows the system to be configured to take
maximum
advantage of reclamation and cogeneration opportunities in any application.
The drive to
maximize performance must be tempered relative to the economic and residual
cost/benefit
of the specific configuration in the specific application.
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Heating, cooling and hot water with multiple heat sinks
In some instances, an application presents an opportunity to provide useful
heating
of multiple locations or processes such as the heating of a space and the
heating of a large
heat sink such as a swimming pool or a process stream. 'U.S. Patent 7,040,108
disclosed
the use of one loop for the heating of a space but did not disclose the multi-
circuit
possibility. Figure 4 demonstrates the use of more than one heating circuit
tied to the hot
water tank to allow the system to provide heating to multiple demands at or
below the
controlled temperature of the hot water tank. The desired temperature of the
heat sink must
be at or below the operating temperature of the Applicants' system while
operating on a
given refrigerant to allow heat transfer into the heat sink. In a'housing or
hospitality
application, where there are swimming pools, this configuration allows the
system to
reduce, if not eliminate, rejection mode operation and maximize cogeneration
during
comfort cooling operation or a continuous process cooling operation. A second
heating
circuit is used instead of a second water cooled condenser when the heat
demand is at a
temperature significantly below the typical refrigerant condensing temperature
(hot tank
setpoint) of the system. This will allow the Applicants' system to control
refrigeration
system operation and in some instances avoid excessive frost formation on the
evaporator(s) and suction piping. Each heating loop will have a solenoid valve
to control
flow of water through the loop based on application demand and priority. A
flow control
valve may also be placed in each loop to allow the heat transfer out of the
tank to be
limited to the heat entering the tank from the water cooled condenser. Each
loop may have
its own circulating pump as shown in Figure 4 or a single pump may be used to
supply
circulation for all loops.
Heating, coolinz and hot water with warm water heat sink
A slight variation of the multiple heat sink concept advanced in Figure 4 is
demonstrated in Figure 5. In this configuration, warm water is supplied to the
cold supply
of plumbing fixtures throughout a facility except possibly for water used for
drinking, ice
making and food preparation purposes. The intent is to provide additional
heating load
during the cooling season to help avoid the need for rejection mode operation
as with an air
cooled condenser. The system would not be used during the heating season
unless it
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provides value to some process within an application. The fact that the cold
water supply
is heated will reduce the demand on the hot water since the mixing at the
point of use will
be biased more towards the cold than usual to arrive at the same level of
comfort for the
user. There are also commercial applications such as laundry operations, dairy
cow
drinking water supply and humidification systems for incubators where 70 F to
90 F water
is preferred to typical ground water temperatures. Using 70 F to 80 F water in
the toilets
and cold water piping to limit condensation and sweating can help reduce mold
formation
in walls and ceilings and reduce liability for people slipping on wet floors
in public
restrooms. Restaurants may be able to utilize the wa.rm water supply to avoid
rejection
mode operation of an air cooled condenser during the comfort cooling season.
There are two configurations presented in Figure 5, cool water supply with
mixing
valve and cool water supply with independent tank. Both options reduce energy
consumption by reducing the need for rejection mode operation during a cooling
process
and can be used in specific applications where warm water is desirable. The
Hot Control
valve is opened and Cool Control valve is closed only when the hot water tank
is satisfied
and the system is calling for cooling. As soon as the hot tank calls for
heating, the valves
will return to their de-energized positions (the Hot Control valve will close
and the Cool
Control valve will open).
The mixing valve configuration allows warm water to be generated on demand
helping to reduce concerns about bacterial growth in warm water storage tanks.
This
approach is best used when there is a continuous demand for cool water since
there must be
a demand for cold water to provide continued support of the comfort cooling
demand. The
independent tank option allows a larger supply of heated water to be stored
and available
for use and it allows the comfort cooling to be extended for a longer period
of time after
water usage or during periods of time when there is no cold water demand. An
additional
benefit of the tank relative to the mixing valve is that the water supply
temperature to the
user will not suddenly switch from cold to cool or from cool to cold when the
hot and cool
control valves actuate. If the temperature of the cool water tank reaches its
set point, the
system will either shut off the cooling process or switch to a heat rejection
mode if it is
available until water is used allowing the system to continue to generate hot
or cool water.
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If a mixing valve were added to the tank configuration the tank could be
heated to a higher
temperature while controlling cool water temperature at the faucet.
The cold water bypass valves in the independent tank option are used to allow
the
cool water tank to be used to store hot water during the heating season.
Bypass valve I is
closed and bypass valve 2 open when the system is calling for cooling. Bypass
valve 1 is
open and bypass valve 2 is closed when the system is calling for heating.
These valves
may be manually operated valves or automated to respond to the system
thermostat.
During the heating season, if the bypass valves are properly set for bypass
mode, the
thermostat on the cool tank may be set to allow it to reach hot water
temperatures. During
the comfort cooling season the thermostat on the cool tank may be set to hold
the
temperature to the warmest acceptable temperature for cool water supply.
Heatinz cooling and hot water with thermal loops and thermal storage
The Applicants' system with its flexible configuration provides a unique
capability
to support heating and cooling operations that involve thermal fluid loops and
thermal
energy storage. The thermal loop or storage system may operate to provide
either cooling
or heating on demand. Figure 6 depicts a basic thermal system with both fluid
loop and
thermal storage. The fluid and storage media may be water, a mixture of glycol
and water
or one of any number of thermal fluids available on the market. The storage
system may
also utilize phase change or phase change materials to boost the energy
density on the
storage device.
The Applicants' system refrigeration cycle configuration is the same as any of
the
multi-heat source / multi-heat sink configurations illustrated in Figures 4
and 5 except this
configuration explicitly utilizes a chiller as one of its evaporators. There
is only one
condenser shown however a specific application may call for additional
condensers. For
example, a second condenser may be used to reject heat to a cooling tower or
air cooled
condenser when a facility's heating demands are satisfied and there is still
need for comfort
cooling. If the system is used only for cooling, the Heating Heat Exchanger,
associated
piping and the Fluid Control valves may be omitted from the configuration. If
the system
is used only for heating, it will take the configuration of the system
depicted in Figure 4,
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except that now the hot water tank might involve a phase change mechanism to
increase
the storage capacity of the system.
The circulation loop between the water cooled condenser and the hot water tank
adds a heat exchanger in the loop rather than utilizing a separate circulating
loop. This
offers the-advantages of providing the highest temperature for the heat
exchange with the
thermal loop/storage system and it avoids the operation of an additional pump.
It does
imply however, that the circulating pump must be wired to operate whenever
there is a call
for heat from either the thermal system or the water storage tank. It also
forces the
configuration of the thermal system loop to have the Chiller Fluid Control and
Heating
Fluid Control valves to avoid heating the loop during cooling operations when
the system
is in operation. The alternative would be to provide an independent heat
circulating loop
between the hot water tank and the thermal system loop as illustrated in
Figure 4. This
eliminates the need for the Chiller Fluid Control and Heating Fluid Control
valves and
places the chillers and heating heat exchangers on the same loop, however it
adds the cost
of operating an additional pump. Both approaches will work and will be
selected primarily
on the basis of cost versus the effect on system energy efficiency. The number
of pumps
and the configuration of the thermal loop system will vary from application to
application.
The thermal system loop may or may not include a thermal storage device
(Heat/cool Fluid
Tank) depending on the requirements of the application. This implies that in
some
instances the tank and one of the pumps in the thermal system will not exist.
Backup
heating and cooling may come from any economically viable source tied into the
thermal
loop. In most thermal loop systems like this today, the backup heating and
cooling would
be provided by a boiler and chiller or cooling tower.
This Applicants' system configuration provides a unique opportunity to utilize
reclamation and/or cogeneration to significantly improve the efficiency of
existing thermal
loop systems in many facilities and it offers opportunity for a number of new
applications
where thermal energy (heat or cool) can be efficiently stored for later use.
Consider, for
example, the two pipe heating and cooling system example discussed above
regarding the
commercial application of the Applicants' system in a hotel. The two pipe
system is
represented by the thermal loop system either with or without the tank. The
tank will often
be used in this application since it provides a dampening affect to the loop
to help reduce
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the variability in loop temperature. The chiller is used in cogeneration mode
operation to
provide cooling to the thermal loop system while it heats the potable water
for showers and
laundry or it heats a swimming pool. The Evaporator (one or more of them),
operated in
reclamation mode to provide heating to the thermal loop system, can be located
in various
exhaust streams such as the continuous makeup air system exhaust, restaurant
kitchen
exhaust, laundry drier exhaust, or the wastewater from the showers and
laundry. The
Applicants' system is sized to match the typical base load heating and cooling
for the
facility within the constraints of the available heat sources and heat sinks.
The backup
heating and cooling systems may then be sized to makeup the difference between
extreme
operating conditions and the typical operating conditions. Another sizing
approach would
be to size the system to satisfy the demands usually experienced during the
spring and fall
and size the boiler and chiller for the remainder of the winter and summer
extremes. The
loop may be operated either in hot and cold mode to provide heating and
cooling via a
sirnple fan coil in each hotel room or the loop may be operated at a given
temperature such
as 55F to provide heating and cooling via water source heat pumps in each
hotel room or
temperature controlled space serviced by the loop. It would be possible to
also provide
backup heating and cooling from a ground connected heat pump system as opposed
to a
boiler and chiller if sufficient ground connection capacity can be
economically obtained in
an environmentally acceptable manner at the application site. With the
Applicants' system,
the scale of the ground connected system can be reduced to help hold down
overall
implementation cost.
A good example of a system where this configuration is used for heat storage
is in a
green house. The greenhouse is subject to significant solar gain on clear days
even when
the outdoor temperatures are cold. This affords the opportunity to collect the
excess heat
during the day and utilize it to heat the space during the night. Ideally, a
phase change
material will be used in the storage tank to increase the energy density of
the storage tank
and the phase change material will be selected to allow storage at the normal
condensing
temperature (hot water tank set point) of the Applicants' system. An advantage
of
removing the excess heat from the greenhouse (beyond the obvious benefits to
the plants)
is that the total amount of heat that might be collected will increase, since
the cooler
temperature in the facility will reduce losses to the outdoors and more solar
energy will be
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captured in a cooled space than in a heated space. This will be true of any
solar thermal
collection system when it is coupled with Applicants' system. When the
collector is
cooled, it will collect more heat. The collected heat may be used directly by
circulating the
heated stored fluid and if the storage system temperature falls below a useful
heating
temperature, the system can be used to extract additional heat from the
storage tank until it
reaches a temperature that will prohibit reasonably efficient operation.
Heating, Cooling, and Hot Water with Parallel Units
In some applications more than one energy reclamation unit with its various
components is required to satisfy the heating and/or coolirig requirement. In
these
applications, particularly in commercial and industrial settings, it can be
more economical
to utilize one circulation pump and/or a common hot water tank for more than
one unit.
The more easily controlled multi-unit configuration on-the water circulation
side is a
parallel configuration so that each unit will experience the same operating
conditions or
water temperatures in the water cooled condenser. Using a series configuration
will cause
downstream units to experience higher temperatures in the water cooled
condenser and as a
result higher compressor head pressure and refrigerant temperature. While this
temperature
differential could be used as a means of turning units on and off, it can be
difficult to
synchronize the controls with the hot tank thermostat. Each unit will have its
own heat
sources and will be controlled independently relative to those sources. Care
should be
taken to try to group units with reasonably similar heat sources to allow the
units to operate
at relatively similar operating conditions on the refrigerant side. For
example, one unit
may be servicing a chilled water loop at 40 F while the other unit is
reclaiming heat from a
wastewater tank at 125 F. The compression ratio of the two compressors could
be
significantly different relative to the condensing temperature which is
controlled by the
temperature of the hot water tank. The unit operating on the colder
environment may reach
a compression ratio condition that exceeds the recommendation for the
compressor before
the hot water tank thermostat is satisfied, putting that unit in danger of
failure or reduced
operating life.
A disadvantage of using common circulating pumps and common tanks for a group
of units operating in parallel is that all of the units will be out of
operation if the pump, the
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tank or a common header experience a failure. The redundancy of using a
circulating
pump for each unit or supplying a spare pump in parallel may be required in
some
applications to minimize risk or costs associated with an outage.
Summary of benefits for Multi-heat source / multi-heat sink configurations
(1) The Applicants' system can utilize one or more evaporators or one or more
condensers independently to optimize utilization of available heat sources and
heat
demands according to the timing of events within a given application process.
This
extends the use of one evaporator and one condenser as disclosed in U.S.
Patent
7,040,108.
(2) The Applicants' system can be used to provide heating, cooling, and heated
water
for any application.
(3) The Applicants' system will utilize 1 or more 3-way or 2 or more 2-way
valves and
controls to switch between evaporators and between condensers according to the
priorities of the application that are defined in the control system.
(4) The system can provide hydronic heat to one or more heat sinks via a
hydronic
heating loop.
(5) The system can provide both chilled water and heated water for a hydronic
heating
and cooling system.
(6) The system can provide tempered water in place of cold water as a way to
avoid use
of an air cooled condenser during comfort cooling season. This reduces energy
consumption by avoiding fan operation, increases heat storage capacity, and
reduces
sweating from pipes and fixture.
(7) Units can be installed in parallel to utilize common circulating pumps and
storage
tanks for increasing capacity while reducing installation cost.
(8) The system can be used with phase change materials to efficiently store
heat or cold
for later use in a process or facility.
(9) The Applicants' system can be used with solar thermal heat collection
systems or
greenhouses to maximize the thermal energy.capture because the collector is
continuously cooled which reduces losses to the surroundings and increases the
amount of thermal energy that can be collected.
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Multi-stage heat dissipation configurations
The condensing path or heat dissipation side of the refrigerant cycle, can be
split
into useful subcomponents for the purpose of transforming environments or
process
streams from one state to a desired state. For example, it is possible to
utilize one portion
of the heat dissipation path of the refrigeration cycle to heat a process
stream while another
part of the dissipation path is producing steam. The refrigerant passes
through three
physical phases (vapor, vapor/liquid mixture, and liquid) during heat
dissipation. The
refrigeration processes associated with each phase are desuperheating (vapor),
condensing
(vapor/liquid mix) and subcooling (liquid). Desuperheating and subcooling
occur over a
range of temperatures while condensing occurs at a single temperature or over
a small
range of temperatures if the refrigerant is a mixture of refrigerants. Each
process occurs at
approximately the same pressure, except as affected by pressure losses in the
piping and
system components. In general, each segment of the heat dissipation path may
be used to
accomplish specific tasks and each segment may be further split to satisfy
application
requirements. Because the refrigerant is going through a phase change and
experiencing
significant variation in density, it will be desirable to select heat
exchangers that best
accommodate the specific phase of refrigerant being processed. For example a
heat
exchanger and associated piping that handles superheated vapor will be sized
and designed
differently than a heat exchanger and piping that will process subcooled
liquid and both of
these may be different than a heat exchanger and piping that processes a
vapor/liquid
mixture. The physical state of the application space or process streams may
also pass
through or be in various phases such as if water were heated to produce steam
which will
further impact equipment and process design.
In the prior art, the water cooled condenser or external condenser of the
system was
assumed to accept or reject all of the energy associated with desuperheating
and
condensing. With multiple water cooled condensers, two or more heated
conditions can be
controlled at a desired temperature. Little attention has been given in the
prior art to the
energy of subcooling, although subcooling is a critical factor in claims
related to frost
formation on evaporators and will be an important consideration for process
efficiency for
some refrigerants. When subcooling is applied, a second or third water
cooledcondenser
(technically called a subcooler) will be required, as described in the
following sections.
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When the universal formulae and the principles of the classes of refrigeration
are applied to
an application, the best arrangement and split of the heat dissipation path
will be
determined so that the refrigeration process and the application requirements
will be
balanced.
The following sections, along with Figures 7 through 11, describe a few of the
basic
configurations and applications where the heat dissipation path of the
refrigerant can be
split to satisfy the requirements of an application. As with any embodiment of
Applicants'
system, the multi-stage heating configuration may be designed for a continuous
heating
process, batch heating, or both, depending on the application requirements.
The
configurations described below extend the multi-heat source / multi-heat sink
approach
discfosed above to include multiple heat exchangers in a given heat
dissipation path and the
ability to control operation to heat process liquids to higher temperatures.
Heating cooliniz and hot water with mixed siuperheat copueneration and
reiection
A special refrigeration configuration has been developed for applications
where the
cooling demand exceeds the heating demand but the application will benefit
from stored
thermal energy at a temperature higher than the normal condensing temperature
(hot water
tank set point temperature). The configuration is illustrated in Figure 7. The
configuration
on the refrigeration side is like other multi-heat source / multi-heat sink
configurations
except that there are two 3-way valves on the condenser side of the compressor
and those
valves are configured and controlled in a special way. The 3-way valve C3V1
supplies
compressed refrigerant to the water cooled condenser or to the external
condenser. Valve
C3V1 as shown, is not a 3-way reclaim valve however it can be, since check
valve 1 is
required. Valve C3V1 allows the system to operate in normal water heating mode
or heat
rejection mode (if the second condenser is not used for some specific heating
application).
The second 3-way valve C3V2 is positioned down stream of the water cooled
condenser
and discharges either to the receiver or to the external condenser. Valve C3V2
must be a
3-way reclaim valve since it will be used to draw refrigerant out of the
external condenser
when the water cooled condenser is being used to heat the hot water tank to
temperatures
below hot water tank set point (i.e. the refrigerant will be condensing in the
water cooled
condenser). When both valves are energized the system will continue to heat
the hot water
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tank above the normal hot water set point (normal refrigerant condensing
temperature)
when there is a call for additional cooling. The water cooled condenser will
operate in
desuperheat mode (i.e. the refrigerant remains a vapor in the water cooled
condenser and is
passed to the external condenser to complete condensation). Thus the system
provides a
mixed cogeneratiori and rejection mode operation when used for comfort cooing
and water
heating. The refrigerant leaving the water cooled condenser at temperatures
above the
condensing temperature is still a vapor and will then travel to the external
condenser to be
condensed. It is important.that the hot refrigerant lines between the water
cooled
condenser and the external condenser are insulated to help keep the
refrigerant from
condensing in the lines before it arrives at the condenser. Preferrably, the
external
condenser is physically located below the water cooled condenser so that any
refrigerant
that condenses to a liquid prior to the external condenser will be carried by
gravity to the
external condenser. As with any refrigerant cycle the receiver should be
positioned below
all condensers to allow the refrigerant to flow by gravity from the condensers
to the
receiver.
As the temperature in the hot water tank increases, the temperature of the
refrigerant vapor traveling to the external condenser will increase. As these
temperatures
increase, the amount of energy captured in the water will decrease. For many
refrigerants
the amount of heat captured in the water will range from 10% to 20% of the
amount that
would be captured while operating the hot water tank at or below the
refrigerant
condensing temperature (i.e. 10% to 20% of normal cogeneration capacity and
80% to 90%
rejection). However, the amount of thermal energy stored in the hot water tank
will be
greater than it could have been if the system were simply switched to
rejection mode when
the hot water tank reached its normal set point or the maximum condensing
temperature of
the refrigerant. Because the tank temperature is higher than the condensing
temperature of
the refrigerant, the system cannot revert to simple water heating mode until
the temperature
in the tank is reduced to the condensing temperature of the refrigerant.
This configuration is ideal for any facility with a high cooling load that can
use a
limited amount of higher temperature water. One example is a carwash that is
co-located
with a restaurant. The cooling demand in a restaurant (particularly from the
kitchen) will
coincide with meal times, while the heating demand for the car wash will
coincide with the
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car wash cycle which will usually be greatest after work hours on weekdays and
all day on
weekends. The heat rejected from the kitchen will be stored in the hot tank at
the highest
temperature permissible for the installed equipment and the water going to the
car wash
from.the hot tank will be tempered down to acceptable conditions for use in
the carwash by
use of a mixing valve. At the point where the car wash demand reduces the hot
tank
temperature to the normal set point temperature, the system will revert to
normal water
heating mode to eliminate the rejection mode operation of the external
condenser and
maximize heat capture into the water.
The above examples assume that the external condenser operates to reject heat.
It is
not necessary that this condenser be used solely for rejection. For example, a
combination
dry cleaner / laundry with a small laundry load could use this configuration
to provide
comfort cooling for the dry cleaning process while generating water at 80 F,
125 F, and
180 F. The 125 F water would be generated using only the water cooled
condenser while
the 80 F and 180 F water would be generated using both the water cooled
condenser and
the external condenser, which in this case would be another water cooled
condenser. Thus
the external condenser would be used to heat incoming cold water to 80 F,
which is a
luxury that adds value to the laundry process but is usually not affordable
when heating
water with a fuel. The heat rejection goes to a useful heating process that is
optional.
Use of this configuration must be weighed against use of larger storage at
normal
condensing temperature and the improved efficiency afforded through reduced
rejection
mode operation given the larger storage capacity. One of the following
configurations may
also provide a more effective solution for some applications.
Heating, cooling, and hot water with suRerheated liquid
In some applications it is of value to incorporate two or more water or liquid
cooled
condensers in series to achieve one or more objectives as was identified in
the dry
cleaner/laundry example described in the previous section; These condensers
may provide
desuperheating, condensing or subcooling to the refrigerant while heating the
liquid to
desired conditions or providing stable, efficient refrigeration system
operation.
A two water cooled condenser configuration shown in Figure 8 is similar to
Figure
7 except it includes the second water cooled condenser WCC2 and its own
circulating loop
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and storage tank in addition to the external condenser EC. This system is
capable of
producing two temperatures of water or liquid, mixed cogeneration/rejection
mode
operation as described in the previous section and rejection of heat via the
external
condenser. The first water cooled condenser WCC1 is used for generating water
or liquid
at temperatures greater than the normal condensing temperature of the
refrigerant. It will
operate in condensing mode until the temperature of the water in its
circulating loop
exceeds the condensing temperature of the refrigerant. At that point WCC1 will
handle
superheated refrigerant vapor and is capable of heating the water in its
circulating loop and
storage tank to a temperature that approaches the temperature of the
superheated vapor
entering WCC1. Tanks, pumps, valves, piping, insulation, etc. associated with
this loop
must all be selected to withstand the temperatures that are desired or
possible with
superheat operation. Testing with R22 in a 5-ton reciprocating compressor has
yielded
water temperatures in the neighborhood of 200 F in batch mode operation. The
refrigerant
vapor entering WCC 1 can be in the range of 220 F to 260 F. This implies that
it would be
possible to generate steam at atmospheric and low pressure conditions using
R22. This
was verified in testing, as a few times the system vapor-locked due to steam
formation in
WCC 1. A different heat exchanger and piping arrangernent would have been
needed to
separate the steam and water for a steam production process.
WCC2 is used to heat water or liquid in its circulation loop up to the maximum
condensing temperature of the refrigerant as controlled by the thermostat in
WCC2's hot
water tank. This water can be supplied either to WCC1's circulation loop or to
a hot water
supply system for the application. When using a system like this it is good to
have a use
for a hot liquid at the condensing temperature provided by WCC2 and at a
higher
temperature provided by WCC1. When WCC1 is in desuperheating mode on an R22
system, 80% to 90% of the available heat will come out through WCC2 while 10%
to 20%
will come out through WCC 1. These percentages will vary with the refrigerant
used in the
system.
Cold water is introduced into the WCC2 loop on the suction side of the
circulating
pump to take advantage of tempering. If the system is controlled to produce a
continuous
flow at a specific temperature, the cold water will mix with the heated water
entering
WCC2. This can allow the tank in the WCC2 loop to operate at 5 F to 8 F higher
than the
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normally acceptable condensing temperature of the refrigerant, since the
compressor will
see a head pressure corresponding with the mixed water temperature rather than
the
temperature of the water in the tank. The flow in WCC2's circulating loop is
controlled
using the Hot Circ Flow Control valve and the tempering water flow rate can be
controlled
by the Tempering Flow Control valve. These flow rates can be adjusted to
obtain the
desired level of temperature control. This tempering affect is of course only
available if
there is a continuous flow of water through the system. Similarly, hot water
leaving the
WCC2 tank is routed to the suction side of WCC1's circulating pump. This
allows the
desuperheating process to see a lower temperature at the water side inlet to
WCC1, which
increases the amount of heat transfer that can be obtained for a given
temperature in
WCC 1's tank. The HT Supply Flow Control valve is used to control the flow of
water to
allow the system to maintain a set point temperature leaving the tank. If
there was no Hot
Supply line (i.e. the system heats water on a once through basis) then the HT
Supply Flow
Control valve could also provide the same affect as the Tempering Flow Control
valve for
WCC2's circulation loop. The number, style and location of flow control valves
will vary
with the requirements or opportunities of an application. For example, if the
Hot Supply
and HT Supply are exposed to atmospheric pressure, then the flow control
valves will be
best located in the Hot Supply and HT Supply lines. Another example is where a
3-way
proportional control valve can be located in the circulation line between the
tank and the
tempering supply. The 3-way valve would discharge water at a rate sufficient
to allow the
temperature in the tank to be held relatively constant. The priority in any
combination of
flow control valves will be to ensure that the compressor head pressure is
controlled to
within acceptable limits while meeting the temperature requirements of the
application.
There is no need to limit the circulation flow rate in WCC1's circulation loop
although it
could help to impose a temperature differential across the water side of WCC1
to promote
better heat transfer.
Theoretical analysis shows that given the right evaporator conditions and
proper
equipment selection while using existing refrigerants, the refrigerant
condensing
temperature (WCC2) can be maintained as high as 150 F. The greatest limitation
on the
use of this configuration is the temperature of the superheated refrigerant
vapor, or more
importantly, the ternperature of the oil in the superheated vapor entering
WCC1. This
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temperature must remain below the point where the oil begins to break down and
lose its
lubricating capability. The choice of refrigerant and the efficiency of the
compressor can
have a significant impact on this temperature. With proper equipment selection
the
configuration can be used to produce saturated steam at low pressures. An
additional heat
exchanger of appropriate design would be needed to generate superheated steam.
Hydronic heating loops can be applied to either tank. The return from a
hydronic
loop originating in the WCC1 tank may return either to the same tank or to the
WCC2 tank.
The primary factor in determining which tank it will return to is the
temperature of the
return relative to the temperature of the tanks. If the return is hotter than
the temperature in
the WCC2 tank it must be returned to the WCC1 tank, the return from a hydronic
heating
loop originating from the WCC21oop must return to the WCC2 tank.
The utilization of this configuration, to produce a liquid or vapor at a
temperature
higher than the nominal refrigerant condensing temperature, will be useful in
any
application where there is a need for cleaning or sterilization of clothing,
and equipment
such as in laundry, agricultural, food processing, and medical sectors. For
example, a
hatchery has a significant cooling load to keep the eggs from over heating.
The hatchery
also needs to sterilize the equipment used to hold the eggs and the chicks
several times a
week. This configuration can be used to generate and store high temperature
water for use
in the wash while maintaining the cooling for the eggs.
Heating, coolin,z; and hot water with subcooled liquid
Figure 9 is the same as Figure 8 except it utilizes the configuration very
differently.
The objective of this utilization is to provide heated liquid at the
condensing temperature in
WCC1 and warmed water from subcooling in WCC2. The circulating loop for WCC2
is
used to maintain an average temperature in the tank for subcooling. This is
useful if the
water usage through the system is intermittent or the temperature of water
returned from
hydronic heating loops is variable. The tank helps to keep the refrigeration
system
operation more stable. If the conditions of the cool liquid entering WCC2 will
be
consistent such as might be the case with a once through heating system, the
circulating
loop and tank may not be necessary as depicted in Figure 10. In this case, the
warmed
CA 02659584 2008-12-04
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water is introduced directly into the suction side of the WCC1 circulating
loop pump.
There may be applications where warrned water or liquid can be useful.
This configuration will be important for use of refrigerants such as R410A and
R422B. The added subcooling is important for obtaining the maximum efficiency
out of
the refrigeration cycle. When the refrigerant is expanded through the TX
valve, a certain
fraction of the refrigerant is converted to a vapor and the rest remains a
liquid. The
expansion process is considered to be isenthalpic or it occurs at a constant
enthalpy.
Enthalpy is the measure of the energy content of the refrigerant in Btu/lb.
The enthalpy of
the liquid refrigerant leaving condenser WCC2 will be greater than the
enthalpy of the
liquid leaving WCC2, since some energy will have been imparted to the water.or
liquid.
This subcooling will allow the fraction of vapor in the mixture to be lower
and the fraction
of liquid in the mix to be higher after the TX valve. Since the refrigeration
effect is
produced by the boiling of the remaining liquid fraction of the liquid/vapor
mixture in the
evaporator, the mixture generated from the subcooled refrigerant will be able
to capture
more heat in the evaporator. When the evaporator captures more heat, the
refrigeration
effect is increased and the COP of the system is enhanced. The maximum
refrigeration
effect occurs when the liquid refrigerant is subcooled to the temperature
which corresponds
to saturated liquid at the suction pressure or pressure at the inlet of the
evaporator. For
some refrigerants such as R410a and R422B the system can lose in the
neighborhood of
40% to 50% of the refrigeration effect during expansion in the TX valve. By
using
subcooling, the refrigeration effect and system efficiency will be
significantly increased.
This utilization of this configuration can be applied anywhere that the system
can
be used with consideration of the issues related to using once through
subcooling as in
Figure 10 or using a tank and circulating loop as depicted in Figure 9. To
take advantage
of the subcooling, the system is best applied in situations where there will
be a consistent
flow of water or liquid to be heated or in the case of a hydronic heating
system to be
reheated.
Heating, coolinz and hot water with superheated liquid and subcoolin~
Figure 11 illustrates a system configured to provide subcooling via WCC3,
condensing via WCC2 and superheating via WCC1. The configuration basically
combines
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the concepts of the previous 2 sections to arrive at a way of generating
higher liquid
temperatures while maintaining higher efficiency through use of subcooling.
The same
concepts of superheat and subcooling apply except they are combined into the
same
system. A fourth heat exchanger would be needed prior to WCC1 in the
refrigeration path
if the system were to be used to generate superheated steam.
When multiple heat exchangers are connected in series, the designer must be
careful to size the equipment to control the pressure drop on both sides of
the heat
exchangers or water cooled condensers. The pressure drop on the refrigerant
side should
be held to a minimum to help limit compressor power requirements and maximize
capacity. The pressures and pressure drops on the water or liquid side should
be controlled
to avoid creating low pressure points where heated liquid may become prone to
boiling
where it isn't desirable. If boiling occurs, the system will be subject to
vapor locks and
cavitation in water pumps.
Summary of Multi-Stage Heat Dissipation Benefits:
(1) The ability to use two heat exchangers (referred to as a water cooled
condensers
WCC1 and WCC2) in series in the refrigerant path to provide heating 6f water
or a
liquid to temperatures higher than the normal maximum condensing temperature
of
the refrigerant at the head pressure of the system. WCC1 desuperheats the
refrigerant while WCC2 condenses the refrigerant.
(2) The ability to use two heat exchangers in series in the refrigerant heat
dissipation
path to provide subcooling of the refrigerant to improve system refrigeration
and
heating effect, overall system capacity and coefficient of performance. WCC1
desuperheats and condenses the refrigerant and WCC2 subcools the refrigerant.
(3) The ability to use three heat exchangers in series in the refrigerant heat
dissipation
path to provide both subcooling of the refrigerant and heating of water or a
liquid to
temperatures greater than the normal maximum condensing temperature of the
refrigerant. This provides improved performance as well as improved system
flexibility and increased application opportunities. WCC1 desuperheats the
refrigerant, WCC2 condenses the refrigerant, WCC3 subcools the refrigerant.
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(4) The ability to apply any refrigerant to the claims of this section with
allowance for
equipment needed to accommodate specific properties of the refrigeration that
may
not have been specifically identified in this description. For example, the
equipment used to refrigerant R410A must be capable of handling the higher
pressures required for operation using R410A.
(5) The ability to use any reasonable number of heat exchangers in series in
the
refrigerant heat dissipation path to achieve a goal 'of heating one or more
liquids to
desired conditions.
(6) The ability to use any reasonable number of the appropriate heat
exchangers in
series in the refrigerant heat dissipation path to boil water or other liquid
being
heated.
(7) The ability to use a thermostatically controlled tank and circulation pump
with each
heat exchanger in series to provide heated liquid storage and consistent or
controlled process temperatures.
(8) The ability to generate heated water in batch or on a continuous basis.
For
continuous flow the ability to apply any variety of water flow control regimes
to
provide compressor head pressure control or subcooling control while obtaining
the
desired quantities of water heated at the desired temperature. Flow controls
may
include but will not be limited to manually operated valves or any of a
variety of
automated valves operated to vary the flow so as to maintain the desired
temperature of a given circulating loop and storage system.
(9) The ability to control the temperature of liquid refrigerant leaving the
last heat
exchanger in the refrigerant heat dissipation path through use of the
thermostatically controlled tank and circulating pump at a temperature which
improves the refrigeration system performance by helping to control ice on the
evaporator and allowing the compressor to operate at a more efficient
operating
point.
(10) The ability to apply multiple sets or circuits of series heat exchangers
in parallel
from the same compressor using 3-way or 2-way valves to take advantage of
different operational opportunities in an application.
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(11) The ability to apply a condenser for use in rejecting heat in parallel to
a series of
heat ekchangers in the refrigerant heat dissipation path.
(12) The ability to heat a liquid to temperatures higher than the norrnal refi-
igerant
condensing temperature using a fraction of the available heat while rejecting
the
rest of the heat or using it in an optional heating process.
(13) The ability to define a refrigeration system that uses two or more 3-way
or 2-way
powered valves to control the refrigeration process according to thermostats
associated with various states or operating modes of an application. For
example,
the 7 controllable components of the system illustrated in Figure 8 are
tabulated
with the 6 operating modes of the system in the green table on the exhibit
drawing.
Operating modes include use of two different evaporators to collect heat to
heat
either the hot tank (WCC2) or the high temperature tank (WCC1). Also included
is
a mode for mixed cogeneration`to the high temperature tank and rejection via
the
external condenser EC and a mode for pure heat rejection operation using the
extemal condenser EC.
(14) The ability to apply multiple compressors each with multiple heat
exchangers in
series in the refrigerant heat dissipation path in a parallel configuration
with the
circulation and tank system. In-other-words the circulation pump, tank and
associated hydronic heating systems may be shared across multiple RASERS units
each with their own evaporators and heat sources.
(15) The ability to conduct refrigerant subcooling via a direct water (liquid)
source or
returns from a hydronic heating system where the mixture of water (liquid)
entering
the subcooler will be relatively consistent in volume and temperature, (Figure
10).
(16) The ability to conduct refrigerant subcooling via a circulating system
with a tank
to help stabilize the operation of the refrigeration system when the supply
and
return water are variable (Figure).
(17) The ability to heat water, glycol, oils, ethanol, or any liquid in the
liquid cooled
heat exchangers provided the heat exchangers are selected with respect to the
properties of the liquid.
(18) The ability to heat air or any gas or vapor in the heat exchangers
provided the
heat exchangers are selected with respect to the properties of the gas or
vapor.
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Multi-stage heat collection configurations
The Applicants' system may utilize any evaporator or evaporator configuration
that satisfies
the requirements of the refrigeration cycle while serving the demands of the
application.
This patent previously described the use of more than one evaporator circuit
to allow
thermal energy to be collected from different locations where only one
evaporator circuit
was used at a time. In this section we expand the definition of a circuit to
include use of
one or more evaporators in a circuit at the same time as dictated by the
requirements or
opportunities of the application. Some applications may require multiple
evaporators in
series and some may require multiple evaporators in parallel for a given mode
of operation.
In general, the evaporator circuit may be split into more than one evaporator
when the
application provides multiple heat sources that are smaller than the nominal
capacity of the
Applicants' system selected to satisfy the thermal energy demands of the
application.
The basic parallel configuration includes the use of an expansion
configuration at
each evaporator. The high pressure liquid refrigerant leaving the receiver may
pass through
a set of valves (2-way or 3-way) to select the desired evaporator circuit
based on
environmental variables. After the valves, the refrigerant is split through
use of tees or a
distribution device to supply each parallel evaporator path in the circuit. It
is important
that the splitting process be designed so as to avoid expansion of the
refrigerant until it
reaches the expansion configuration. After the split the liquid refrigerant
will pass through
the expansion configuration (TX valve, orifice, distributor, etc.) on its way
to the
evaporators. After the evaporators the superheated refrigei ant will be
recornbined into the
suction line feeding the compressor using tees or other means to collect
multiple refrigerant
streams into one. With parallel evaporators it may be necessary to utilize a
pressure control
device between the evaporators and the compressor to ensure that the pressure
leaving the
evaporators is the same. An example where parallel evaporators can be used is
in a hog
barn. Two or rnore evaporators may be placed in front of separate exhaust fans
to allow
thermal energy capture sufficient to allow the unit to operate at nominal
capacity.
The basic series configuration uses only one expansion configuration but
splits the
evaporator into two or more parts to provide the cooling effect to two or more
environments while satisfying the superheating requirements of the
refrigeration cycle.
The multiple evaporators will usually be reasonably close to each other and
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connecting the evaporators will usually be well insulated to avoid losing the
refirigeration
effect between the evaporators. The refrigerant may pass between the
evaporators through
a single pipe or it may pass through multiple pipes or a multi-port mixing
device. An
example where a series configuration is useful is where an environment may
require a
small or controlled amount of cooling relative to the total cooling capacity.
The
evaporators will be sized to support the controlled cooling activity and may
be made from
any material as dictated by the environment served by the evaporator.
The temperature of the refrigerant during evaporation (a liquidJvapor mixture)
will
be constant or for a refrigerant mixture, will vary by a small amount while
the refrigerant is
boiling within the evaporator (i.e. just like water boils at 212 F at standard
atmospheric
pressure). After all of the refrigerant is boiled, its temperature will begin
to rise as more
thermal energy is applied to the evaporator (this is called superheat). The
temperature rise
(degrees of superheat) is limited to only the amount necessary to avoid
introducing liquid
refrigerant into the compressor. It is also beneficial to limit the amount of
superheat
because the capacity of the compressor decreases as the amount of superheat
increases due
to the reduction in density of the superheated vapor as its temperature
increases. The
thermal expansion (TX) valve usually provides a means to adjust the degrees of
superheat.
The expansion and evaporator configuration must be selected to provide the
best possible
system capacity while satisfying the cooling demands of the environments
served.
The evaporators must be selected to account for differences in the
environmental
conditions. For example if two evaporators operating in series experience
different
environmental temperatures then the evaporators may or may not be the same
size
depending on how much of the evaporation process each evaporator is intended
to handle.
In contrast two evaporators operating in parallel will likely be sized
differently if they are
exposed to different temperature environments to help match the temperature
and pressure
of the refrigerant leaving each evaporator. Parallel and series evaporator
configurations are
most easily applied to multiple similar environments. Series evaporator
configurations can
be more easily applied to multiple environments with different operating
conditions or
multiple environments with similar operating conditions.
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Summary of Multi-Stage Heat Collection Claims
1. Ability to use one or more evaporators in an evaporator circuit.
2. Ability to connect multiple evaporators in series or in parallel on a
single circuit.
3. Ability to use one or more evaporators to provide multiple controlled
cooling
activities for air, water, glycol mixtures, oils, ethanol or any liquid,
vapor, or gas to
be cooled.
4. Ability to use multiple elements in the expansion configuration such as the
TX
valve, orifice, and distributor.
5. Ability to use evaporators manufactured from any material (copper,
stainless steel,
aluminum, etc.) as dictated by the environment served by the evaporator to
protect
the evaporator from failure due to corrosion, erosion, thermal fatigue, or
other
phenomenon.
6. Ability to size evaporators to match different environmental conditions
while
obtaining desired refrigeration system operation.
Summary of Exemplary Uses of the System
Laundromat - In a laundromat, the system heats fresh water for a wash cycle
while
providing comfort cooling for the workers/customers, by collecting waste heat
from the
drier exhaust vents, or collecting waste heat from the waste water.
Dry cleaner/Laundromat combination - The system heats fresh water or tempered
water
from dry cleaner cooling system while providing comfort cooling for
workers/customers,
collecting waste heat from the drier exhausts, or collecting waste heat from
the waste
water.
District heating - The system utilizes the excess thermal energy from a
laundromat, dry
cleaner, or other energy intensive business located in a commercial or
residential area to
heat water that can be piped and metered to neighboring businesses or
residents for direct
use as heated water and for use in space or process=heating.
Meat Processing (kill and products) - The meat processing process generally
requires a
significant amount of heated water for washing and sterilization. The system
has the
ability to heat water from several sources: waste heat from the singe process,
excess
ambient heat from the sterilization or cooking processes (comfort cooling),
waste heat from
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the carcass wash and facility cleanup wastewater, and heat expelled from the
refrigeration
processes required to chill the carcass prior to cutting or after processing.
The ability to
provide comfort cooling through use of a forced draft air handler with a-coil
provided the
environment does not present a high fouling potential. Finless evaporators may
be used to
recover waste heat from singe and waste water to minimize fouling and allow
ease of
cleanup. There is also the ability to collect heat expelled by the
refrigeration process using
an evaporator at the exhaust of the condenser. The system has the ability to
directly
provide refrigeration and water heating simultaneously. This is the most
economical heat
recovery mode since both activities are performed using the same kW of power
that was
going to be used for refrigeration regardless of how the water was heated.
Car Wash - The system heats wash water for a car wash and in floor heated
water loops
used for office heating and eliminates ice formation at the approaches to the
wash bays.
The heat derives from several heat sources: wastewater, excess heat in the
office or
mechanical room, excess heat from an adjoining convenience store or
restaurant, warm
humid air exhausted from the wash bays or the outdoor ambient air.
Restaurant - A restaurant benefits from both heating and cooling affects of
the system.
The kitchen is cooled year-round while water is heated for dish washing and
for use in
heating the restaurant. The restaurant can be cooled during high occupancy and
during the
cooling season while heating water for dish washing. Since the cooling load
usually
exceeds the water heating demand an air cooled condenser, warm water supply,
or district
water heating system will be needed during the summer.
Swimming pool - The system can heat swimming pool water using heat from the
ambient
air or from excess heat in the offices, shower house or mechanical room
(comfort cooling).
Campground shower house - Shower house water can be heated with the system
using
heat from the ambient air or from excess heat and humidity in the shower house
or
mechanical room (comfort cooling). Comfort cooling in the shower house may
help to
extend the life of equipment and parts that are subject to the high humidity
usually found
within the shower house.
Animal Confinement - (Animals and foul including but not limited to: hogs,
dairy cattle,
beef cattle, chickens, turkeys, etc.) The system has the ability to heat the
living space using
the waste heat that is exhausted via the ventilation system or from comfort
cooling in
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critical areas such as the breeding room or boar stud area. Heating may be in
the form of
heating the air in the room or localized heating as for baby pigs in a
farrowirig crate or
small animals for the first few days or weeks after they are weaned or
hatched. Some
animals may also benefit from the ability to heat drinking water using waste
heat from an
exhaust or heat captured from comfort cooling processes. Some stages of animal
husbandry will benefit extensively (weight gain, survival, conception rates,
reduced
stress/susceptibility to disease. ..) by providing comfort cooling during hot
humid summer
days. Excess heat from comfort cooling is generally used for heating wash
water or
drinking water or is expelled in an air cooled condenser. If animal
confinements can be
properly co-located, the system has the ability to use excess heat generated
by larger
animals to heat spaces for smaller animals. Heating spaces using Applicant's
hydronic
heating system has the ability to reduce humidity and toxic gas loadings in
the space when
compared against direct fired propane or gas heaters. The system has the
ability to use
excess heat from animal confinements (heat and humidity generated by the
animals) to heat
anaerobic digesters year-round. The system can also provide the ability to
transform the
waste thermal energy to heat the residence, shop/office or to provide some
heat input for
low temperature grain drying either in the bin or in a drying process via an
appropriate
district heating system. In some specialized animal research facilities, the
system has the
ability to heat water for the sterilization processes using waste heat from
ventilation
exhaust, waste heat in the wastewater, and excess heat in the rooms where the
sterilization
equipment resides (comfort cooling for the workers).
Dairy - The dairy farm provides a unique opportunity. The system provides
cooling for
the milk and can be used to cool the offices, and milking parlor. A cooled
parlor may
contribute to comfort for the cows and increase milk volume. The captured heat
can be
used to heat Clean In Place (CIP) water and the drinking water. Warm drinking
water may
also help increase the amount of water the cows drink which can contribute to
increased
milk production. Since dairy manure is well suited for digesters, the excess
heat from the
various value added cooling activities can also be used to support an onsite
digester.
In-Line Processes (General) - The in-line process involves the integration of
the system
into a process to utilize the simultaneous cooling and heating affects. Most
in-line
processes will use cogeneration on a continuous basis when the process is
operating. The
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introduction of the system will displace a portion if not the entire use of
separate heat
sources and cooling sources. Any manufacturing process that needs both heating
and
cooling presents an opportunity to apply the system.
Hatchery - The system also has the ability to collect heat from cooling water
used to cool
the incubators and from ventilation exhaust. The reclaimed heat can be used
for space
heating and to heat wash water and humidification spray water. The ability to
recycle the
cooling water will provide significant savings in water and wastewater
disposal costs. The
ability to integrate the system into the incubators will provide both heating
and cooling
inside the box through finned hydronic systems.
Anaerobic Digesters - Anaerobic digesters require close monitoring of
temperature to
ensure bacterial activity. The manure must be heated as it enters the digester
and the
temperature must be maintained throughout the anaerobic conversion process.
Our system
provides the ability to collect heat from the manure leaving the digester and
use it to
preheat the manure entering the digester. In addition the gas treatment
systems and energy
conversion systems often associated with digesters produce excess heat which
can be
captured and used to preheat manure and maintain the temperature of the manure
in the
digester. Waste heat from nearby animal confinements can also be captured and
used as
well as heat from the ambient air.
Bio-diesel Production - Bio-diesel production requires that the raw oil be
heated and that
the various process streams be heated and cooled at various points along the
way. Most
processes use a boiler to heat the oil and a cooling tower to help cool the
process stream.
Many processes also use a chiller at some point in the process. The chiller
can be replaced
with Applicants' stem to provide both chilling and process heating. In
addition, the heat
remaining in the bio-diesel after conversion may be extracted for process use.
Heat in the
cooling water going to the cooling tower can also be used to heat makeup or
condensate
water for the boiler or for heating a process stream. Excess heat in the
boiler/mechanical
room (includes waste heat generated by compressors) and waste heat from the
boiler
exhaust can also be captured and introduced into the process. Before the bio-
diesel
process, the oil is usually generated in an extrusion process. Extrusion
generates a good
deal of heat which might also be captured and reintroduced into the process at
an
appropriate location.
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Ethanol Production - Ethanol production has some similarities to bio-diesel
processing.
The process involves a boiler and a cooling tower and may involve a chiller.
The process
streams are heated and cooled for the various stages of the process. Some
ethanol
processes utilize a great deal of fresh water to wet and cook the mash and
makeup water for
boiler. All of this water must be heated. The present invention can heat the
water used for
the cook process and preheat the condensate and makeup water for the boiler.
Heat may be
collected from the cooling water lines either before or after the cooling
processes. In a
retrofit application, the system can help to compensate for an undersized
cooling tower.
Excess heat from the boiler/mechanical room and boiler exhaust are also
available for
heating. It may also be possible to design a condensing system to cool the
exhaust from the
distiller's grain driers. In addition to recycling the heat, the condensed
water can also be
treated and reused in the process. Seasonal applications such as space heating
or comfort
cooling may also be incorporated into the plant however the payback on a
season
application is longer than the payback from supporting the process.
Canned or frozen vegetable or prepared food processing - The canned food
process
usually requires cooking and elevated temperatures to vacuum seal containers.
The excess
and waste heat from the process can be recycled into heated process and wash
water using
the system. The frozen food process usually requires chilling and may involve
cooking or
blanching. The excess or waste heat from these processes can be used to heat
process or
wash water. With our system the chilling process can perform both chilling and
water
heating. Excess heat can also be used to heat other parts of the facility or
for a district
heating system.
Painting processes - Powder coat and baked paint processes utilize ovens to
cure the paint
and produce a great deal of excess and waste heat. The system can utilize this
excess
thermal energy to heat wash water, heat other parts of the manufacturing
facility or heat
water for a district heating system.
Extrusion and molding processes - Extrusion processes generate a great deal of
excess
heat which can be utilized to heat other parts of the facility or to heat
process and wash
water. Some molding processes such as foam pallet forming utilize a great deal
of heated
water/steam and generate a large sensible and latent heat load in the
facility. This system
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can cool the facility and the cooling water while generating preheated water
going into the
boiler.
Boilers and Mechanical Rooms - Boiler and mechanical rooms provide opportunity
to
collect excess or waste heat and heat water. Air and refrigeration compressors
generate
appreciable amounts of heat and boilers have ambient radiation and convection
losses as
well as exhaust. Other types of equipment also generate heat. Our system will
benefit
compressors by cooling the air and the environment around the compressor.
Cooler air will
increase the density of the air and improve the capacity of the compressor and
cooler
operating conditions will reduce wear on the equipment and lubricating oils
resulting from
excessive heat. For boilers, the excess or waste heat can be reclaimed by the
system to
preheat makeup or condensate return water or to preheat combustion air. The
scale of such
systems can range from a few thousand Btu/hr to large utility scale power
plants.
Extracting heat from a boiler exhaust will require special evaporator
configurations and use
of materials such as stainless steel that will be suitable for the potentially
corrosive boiler
exhaust.
Greenhouse - A greenhouse provides a significant source of heat during the
day. Even on
sunny cold winter days the temperature in the greenhouse can climb and produce
warmer
temperatures than desired. During summer months the temperatures in a
greenhouse
become oppressive. This heat source can be utilized in a number of settings.
In an actual
fiinctional greenhouse the excess heat generated during the day can be
captured by the
system and stored in heated water and then distributed into the facility at
night. During the
summer when excess heat prohibits plant culture the excess heat might be used
to heat
water for nearby processes. The greenhouse can also be used in commercial
office
buildings, aparhnents, hotels, concrete plants, hospitals or any building
requiring heat that
doesn't have a waste heat source. The greenhouse can be used to collect
ventilation
exhaust and solar heat gain (not necessarily used for growing plants). The
heat captured
from the greenhouse by the system can be used to heat water for showers,
laundry,
swimming pools, concrete mix on cold days, etc. By cooling the space the
amount of
thermal energy that can be captured will increase. The moisture in a building
exhaust that
is captured in the greenhouse can be collected and reused for non-potable uses
or treated
for potable use.
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High Rise Buildings, Apartmerits and Hotels - The system can tie into large
heating
cooling and water heating systems for large high rise buildings. Using a
hydronic loop and
localized water heat pump/fan units heating and cooling can be accomplished in
different
parts of the building simultaneously by collecting excess solar gain from the
sunny side of
the building and transferring it to the shaded side of the building. Our
system is used to
chill the loop during the summer and the excess heat is used to heat potable
water for
showers/baths, laundry, swimming pools, etc., and can also be used to recoup
heat from
continuous ventilation exhaust and wastewater to makeup heat into the hydronic
heating
loop and to heat other spaces such as the parking garage, makeup air, etc.
during the
heating season.
Grain and Hay Drying - Heat from warm moist air exhausted from the drying
process
can be reclaimed by the system to preheat incoming dry air and improve the
drying process
efficiency.
Hydrocarbon to oil systems - Recently a number of systems are being developed
for
converting wet hydrocarbon materials to crude oil through a process involving
high
pressure and temperature (hydrothermal depolymerization). The system can be
integrated
into the process to preheat the hydrocarbon-water slurry based on heat
collected from the
discharged oil and heat losses from the process.
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