Note: Descriptions are shown in the official language in which they were submitted.
HYBRID DRY AIR COOLING SYSTEM
Background
[0001] This disclosure relates generally to large-scale Heating, Ventilation,
and Air Conditioning
(HVAC) systems, which in some embodiments, may be employed to provide cooling
for
computer-system data centers and other large structures which may contain or
produce an
excess of heat.
[0002] Large-scale data centers typically house a variety of computer systems
in a common
facility. Data centers may also house associated components such as
telecommunication and
data storage systems and backup units such as power supplies, data
communication
connections, etc. The various computer, data storage, telecommunication, power
and other
systems at a data center may generate significant amounts of heat. Moreover,
the various
systems of a data center are typically arranged with minimal spacing to reduce
land and
building costs. Locating a large number of such heat-generating systems and
components in one
location and in close proximity to each another can create heat dissipation
issues. Mechanical,
compressor-based, HVAC cooling systems are often used to ensure that the
computer systems
operate within safe operating temperatures.
[0003] Mechanical, compressor-based HVAC cooling systems may use large amounts
of
electrical power, diesel, natural gas, or the like, to power compressors as
part of a refrigeration
cycle.
[0004] HVAC systems also often consume immense amounts of water. For example,
many
large-scale HVAC cooling systems, like those used at data centers, employ
cooling towers that
use water-based evaporative cooling, also referred to as a water-side
economizer, to pre-cool
water, propylene glycol, or a heat transfer fluid before the heat transfer
fluid may be further
cooled by a mechanical compressor-based refrigerator or chiller. Water-based
evaporative
cooling is attractive, because water has a relatively high energy density
(energy/unit volume)
compared to a large number of elements and compounds and because water also
has a large
enthalpy of vaporization (energy required to change from liquid phase to
gaseous phase).
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[0005] However, a data center using an HVAC cooling mechanism with water-based
evaporative cooling towers may consume large volumes of water on a daily,
monthly, or annual
basis. Water is becoming less available and more expensive. Use of water is
now also
understood to impose significant burdens on the environment.
[0006] When ambient external air temperatures fall below the temperature of
air in a building,
air-side economizers are sometimes used to reduce energy consumed by
mechanical HVAC
systems. In a simple form, an open window can be understood as an air-side
economizer, as it
may let cool ambient air into the warm air of the building. However, air
handling systems in
many contemporary buildings, such as computer system data-centers, hospitals,
and the like,
often filter air to remove dust, smoke, pollution, corrosive compounds,
allergens, and
biologically active material or organisms. In such a context, simply "opening
a window" is not
desirable. More complex air-side economizers incorporate air filters or may
use a heat
exchanger to exchange heat between air in the building and ambient external
air.
When the temperature of heat transfer fluid exiting a process cooling system
is below ambient
air temperatures, legacy air-side economizers are not used, because the
ambient air would be
warming the heat transfer fluid, instead of cooling it.
[0007] Mechanical HVAC cooling system are commonly designed to operate with a
minimum
"head pressure" in a condenser, such that condenser coils avoid a "low load"
condition. Low
load conditions can result in laminar flow in a condenser, underfeeding of
thermostatic
expansion valves, and oil logging (when oil logs in an evaporator), all of
which negatively impact
efficiency and/or the operating life of the machinery,
[0008] Embodiments will be readily understood by the following detailed
description in
conjunction with the accompanying drawings. To facilitate this description,
like reference
numerals designate like structural elements. Embodiments are illustrated by
way of example,
and not by way of limitation, in the figures of the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Figure 1 is a block diagram illustrating an example of an embodiment of
a hybrid dry air
cooling system.
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[0010] Figure 2 is a schematic diagram illustrating a first example of an
embodiment of a hybrid
dry air cooling system.
[0011] Figure 3A is a first portion of a flow chart illustrating an example of
an embodiment of a
process performed by a control system of a hybrid dry air cooling system.
[0012] Figure 3B is a second portion of a flow chart illustrating an example
of an embodiment
of a process performed by a control system of a hybrid dry air cooling system.
[0013] Figure 4 is a schematic diagram illustrating a second example of an
embodiment of a
hybrid dry air cooling system.
[0014] Figure 5 is a schematic diagram illustrating a third example of an
embodiment of a
hybrid dry air cooling system.
[0015] Figure 6 is a functional block diagram illustrating an example of a
computer device
incorporated with teachings of the present disclosure, according to some
embodiments.
DETAILED DESCRIPTION
[0016] For the purposes of promoting an understanding of the principles of the
invention,
reference will now be made to the examples, sometimes referred to as
embodiments,
illustrated and/or described herein. These are intended merely as examples. It
will
nevertheless be understood that no limitation of the scope of the invention is
thereby
intended. Alterations and further modifications in the described processes,
systems or devices,
any further applications of the principles of the invention as described
herein, are
contemplated as would normally occur to one skilled in the art to which the
invention relates,
now and/or in the future in light of this document.
[0017] In overview, a hybrid dry air cooling system is disclosed herein,
connected to a cooled
space, such as a building. The hybrid dry air cooling system comprises a dry
ambient air cooling
system, a control system, a mechanical refrigeration system, and an air
handling unit, coupled
to a cooled space.
[0018] In overview, the dry ambient air cooling system comprises a closed-loop
of heat transfer
fluid, a heat transfer fluid/external-air heat exchanger (which exchanges heat
energy between
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heat transfer fluid and external air; this is also referred to as a heat
rejection coil) coupled to
the closed-loop of heat transfer fluid, one or more fans or blowers, and a
partially enclosed air
space, enclosing the heat transfer fluid/external-air heat exchanger. The
partially enclosed air
space is open to ambient outside air, and coupled to the blowers, such that
the blowers can
pull or push ambient outside air across the heat transfer fluid/external-air
heat exchanger.
[0019] The dry ambient air cooling system is used by the control system, not
to directly cool air
in the cooled space, but to cool heat transfer fluid of the refrigeration
system. When ambient
outside air is cool enough, the control system uses the dry ambient air
cooling system to cool
heat transfer fluid of the mechanical refrigeration system in the heat
transfer fluid/external-air
heat exchanger.
[0020] The hybrid dry air cooling system also comprises the mechanical
refrigeration system.
The mechanical refrigeration system may comprise, for example, a mechanical
compressor, a
closed-loop of pipe, conduit, or the like containing a phase-transition
refrigerant, an external
air/phase-transition refrigerant heat exchanger (to exchange heat energy
between external air
and phase-transition refrigerant; this component is also referred to herein as
a condenser coil),
thermal expansion valve, and a heat transfer fluid/phase-transition
refrigerant heat exchanger
(to exchange heat energy between heat transfer fluid and phase-transition
refrigerant).
Examples of phase-transition refrigerants include ammonia, methyl chloride,
propane,
chlorofluorocarbon, dichlorodifluoronnethane, chloromethane, and the like.
Compressed phase-
transition refrigerant is allowed to expand or otherwise transition from a
liquid phase to a gas
phase in heat transfer fluid/phase-transition refrigerant heat exchanger,
drawing heat energy
out of heat transfer fluid and transferring heat energy of the heat transfer
fluid to the phase-
transition refrigerant. The warm or hot gas phase form of the phase-transition
refrigerant is
then compressed by compressor in external air/phase-transition refrigerant
heat exchanger
into a liquid or compressed form, releasing heat energy to external ambient
air, and returning
as a liquid to thermal expansion valve and heat transfer fluid/phase-
transition fluid heat
exchanger. In an embodiment disclosed herein, external air/phase-transition
refrigerant heat
exchanger of the mechanical refrigeration system is downstream of the heat
transfer
fluid/external-air heat exchanger (or heat rejection coil) of dry ambient air
cooling system.
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[0021] The hybrid dry air cooling system also comprises a heat transfer
fluid/internal-air heat
exchanger, to exchange heat energy between the heat transfer fluid and return
air of an air
handling unit. This may also be referred to herein as a "process air heat
exchanger" or "cooling
manifold" and may be described as being part of an "air handling unit". The
hybrid dry air
cooling system also comprise the air handling unit. The air handling unit
obtains warm air from
inside the cooled volume, also referred to herein as "return air", and passes
the return air
across the heat transfer fluid/internal-air heat exchanger, such that heat
energy passes from
the return air to the heat transfer fluid/internal-air heat exchanger and to
the heat transfer
fluid. The heat transfer fluid, now warmed by the return air, is cooled by a
control system, using
the dry ambient cooling system and/or the refrigeration system, as discussed
further herein.
The cooled return air, now referred to as "supply air", is then returned to
the cooled volume by
the air handling unit.
[0022] The air handling unit may also comprise air filters, dehumidifiers, and
the like, to
maintain a desired air purity and humidity level inside the cooled volume.
Effort may be
expended to limit direct mixing between external ambient air and interior air
of the cooled
space.
[0023] The hybrid dry air cooling system also comprises the control system.
The control system
monitors the external ambient air, generally measuring temperature and/or
humidity, which
may also be described as a measurement of enthalpy of the external ambient
air. When
external ambient air is cool and dry enough (or when the enthalpy of the
external ambient air is
low enough), the control system preferentially uses the dry ambient cooling
system to cool the
heat transfer fluid in the closed-loop of heat transfer fluid. If the dry
ambient cooling system is
not able to cool the heat transfer fluid enough to meet supply air
requirements, the control
system may engage the compressor-based refrigeration system to mechanically
cool or chill the
heat transfer fluid.
[0024] The control system of the hybrid dry air cooling system may seek to
maintain a relatively
high temperature of heat transfer fluid exiting heat transfer fluid/internal-
air heat exchanger,
such as at an upper limit of an allowed range. The control system may perform
this by i)
adjusting use of the dry ambient cooling system relative to use of the
mechanical refrigeration
CA 2973023 2017-07-12
system, preferentially increasing use of the dry ambient cooling system when
excess cooling
capacity remains in the dry ambient cooling system and/or by ii) reducing a
volume of heat
=
transfer fluid flowing to the heat transfer fluid/internal-air heat exchanger.
It is not known or
suggested to maintain a relatively high temperature of heat transfer fluid
exiting heat transfer
fluid/internal-air heat exchanger and/or it is not known or suggested to use
of these two factors
(preferential use of a dry ambient cooling system and reduction in mass flow
rate of heat
transfer fluid into heat transfer fluid/internal-air heat exchanger) to
maintain a relatively high
temperature of heat transfer fluid exiting heat transfer fluid/internal-air
heat exchanger, such as
at the top end of an allowed temperature range.
[0025] Reduction in the volume of heat transfer fluid flowing to the heat
transfer fluid/internal-
air heat exchanger may be performed by reducing the overall flow rate within
the closed loop
of heat transfer fluid. However, in order to maintain a minimum required
system pressure, such
as a minimum pressure required to operate control valves and/or heat
exchangers, the volume
of heat transfer fluid flowing to the heat transfer fluid/internal-air heat
exchanger may be
reduced, with a resulting bypass fluid being mixed with heat transfer fluid
outside of the heat
transfer fluid/internal-air heat exchanger, and with this portion of heat
transfer fluid (outside of
the heat transfer fluid/internal-air heat exchanger), being held at or above
the minimum
required system flow rate.
[0026] By maintaining a relatively high temperature of heat transfer fluid
exiting heat transfer
fluid/internal-air heat exchanger, the hybrid dry air cooling system may
continue to use the dry
ambient cooling system to address at least part of the cooling load when the
temperature of
ambient air is less than the temperature of heat transfer fluid exiting heat
transfer
fluid/internal-air heat exchanger.
[0027] In contrast, legacy cooling systems typically maintain a constant mass
flow rate of heat
transfer fluid into and out of the heat transfer fluid/internal-air heat
exchanger or process
cooling system. In, for example, low load conditions or during times of
ambient air temperature
swings, legacy cooling systems with a constant mass flow rate may produce heat
transfer fluid
exiting the heat transfer fluid/internal-air heat exchanger below the
temperature of ambient
air. In such cases, a dry ambient cooling system or a "free energy" system
cannot be used and
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mechanical cooling or water chilling must be used to address all of the
cooling load, even if the
ambient air is cooler than the upper end of an allowed temperature range for
heat transfer
fluid exiting the heat transfer fluid/internal-air heat exchanger (because the
temperature of
ambient air is below the temperature of heat transfer fluid exiting the heat
transfer
fluid/internal-air heat exchanger). Producing heat transfer fluid exiting the
heat transfer
fluid/internal-air heat exchanger below the temperature of ambient air thereby
results in
unnecessary use of relatively expensive mechanical cooling or water chillers.
By varying the
flow rate of heat transfer fluid into the heat transfer fluid/internal-air
heat exchanger to keep
the heat transfer fluid which exits the heat transfer fluid/internal-air heat
exchanger at the top
end of an allowed temperature range, the disclosed hybrid dry air cooling
system can continue
to use the relatively economical dry ambient cooling system to address at
least part of the
cooling load.
[0028] Fig. 1 is a block diagram of an implementation of a hybrid dry air
cooling system 100
that may provide hybrid air- and mechanical-cooling within a building or other
space, which
may be referred to as cooled volume 105. In embodiments, cooled volume 105 may
include a
building or data center room. The building or data center room may contain a
variety of
computer systems, or may be or include another type of commercial or
industrial space, or may
be or include a residence or a temporary space or structure, such as a tent.
[0029] Hybrid dry air cooling system 100 may include air handling unit 110,
also referred to
herein as a process cooling system, which may be in fluid-communication with
cooled volume
105 such that warm return air from within cooled volume 105 may be drawn
through air
handling unit 110, passed across a cooling manifold or heat transfer
fluid/internal-air heat
exchanger of air handling unit 110 (as described below in greater detail), and
returned to
cooled volume 105 as supply air at a lower temperature relative to the warm
return air. Cooling
system 100 may further include dry ambient cooling system 115, refrigeration
system 120, a
cooling mixer 125 coupled between dry ambient cooling system 115 and
refrigeration system
120, a mass flow rate controller 126 controlling a volume of heat transfer
fluid flowing to
cooling manifold or heat transfer fluid/internal-air heat exchanger of air
handling unit 110, and
a control system 130 coupled to i) cooling mixer 125 to control reciprocally
proportional cooling
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provided by dry ambient cooling system 115 and refrigeration system 120 and
coupled to ii)
mass flow rate controller 126 to maintain a relatively high temperature of
heat transfer fluid
exiting heat transfer fluid/internal-air heat exchanger, such as at the top
end of an allowed
temperature range. In Fig. 1, mass flow rate controller 126 is illustrated as
between
refrigeration system 120 and air handling unit 110 (along the input path to
air handling unit
110) and separate from mixer 125. In embodiments, mass flow rate controller
126 may be a
component, such as a valve, of mixer 125 and may be located along the output
path from air
handling unit 110. Mass flow rate controller 126 may also be or include a
variable pump that
circulates heat transfer fluid 135. Embodiments of components found in air
handling unit 110,
dry ambient cooling system 115, and refrigeration system 120 are illustrated
and discussed in
Figures 2, 4, and 5.
[0030] Hybrid cooling system 100 may utilize a closed-loop containing heat
transfer fluid 135.
Heat transfer fluid 135 may be or comprise, for example, water, propylene
glycol, or the like. In
embodiments, heat transfer fluid 135 may be a solution comprising water and
propylene glycol
(e.g., 10-30%). It will be appreciated, however, that many other heat transfer
fluids may be
used. Heat transfer fluid 135 may circulate in the closed-loop, such as by
operation of pumps or
passively, between air handling unit 110, dry ambient cooling system 115, and
refrigeration
system 120. Closed-loop heat transfer fluid 135 may pass through heat transfer
fluid/internal-
air heat exchanger of air handling unit 110. Warm return air from cooled
volume 105 may be
passed across the heat transfer fluid/internal-air heat exchanger of air
handling unit 110, to
reduce the temperature of the warm return air and to produce lower-temperature
supply air to
be supplied to cooled volume 105. The heat transfer fluid/internal-air heat
exchanger of air
handling unit 110 transfers heat from the warm return air of cooled volume 105
to heat
transfer fluid 135.
[0031] Heat from warm return air of cooled volume 105, after transfer to heat
transfer fluid
135, may be transferred externally, such as outside to external ambient air,
via dry ambient
cooling system 115 and/or refrigeration system 120. Dry ambient cooling system
115 may be
characterized in that it employs dry ambient air, rather than evaporation of
water or a
mechanical refrigeration system, to cool heat transfer fluid 135.
Refrigeration system 120 may
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be characterized in that it employs variable capacity mechanical cooling to
provide cooling of
heat transfer fluid 135.
[0032] In embodiments, dry ambient cooling system 115 may selectively provide
dry cooling
and/or precooling of heat transfer fluid 135 of hybrid cooling system 100
according to
operation of control system 130 and the ambient air temperature and/or
humidity, without
application of water for evaporative cooling. Although embodiments may
selectively further
employ wet evaporative cooling under some severe ambient conditions, such wet
evaporative
cooling would supplement the dry ambient cooling of dry ambient cooling system
115.
[0033] In embodiments, hybrid cooling system 100 may further control a mass
flow rate of heat
transfer fluid 135 to heat transfer fluid/internal-air heat exchanger of air
handling unit 110,
according to operation of control system 130, to maintain a temperature of the
heat transfer
fluid 135 flowing out of cooling manifold and heat transfer fluid/internal-air
heat exchanger of
air handling unit 110 close to or at an upper limit.
[0034] As an example illustrating operation of one implementation, hybrid
cooling system 100
may be operated to receive return air at air handling unit 110 from cooled
volume 105, wherein
the return air has a temperature of about 100 F. Hybrid cooling system 100
may provide to
cooled volume 105 via air handling unit 110 supply air having a temperature of
about 79.8 F. In
this example, heat transfer fluid 135 may enter air handling unit 110 at a
cooling temperature
of about 75.1 F and may return from air handling unit 110 at a heated
temperature of about
88.1 F. The heated temperature of about 88.1 F may be an upper limit of an
allowed range for
heat transfer fluid 135 exiting air handling unit 110. In operation, control
system 130 may
selectively employ dry ambient cooling system 115 and/or refrigeration system
120 to return
heat transfer fluid 135 to the cooling temperature of about 75.1 F to be
recirculated through
air handling unit 110.
[0035] In operation, control system 130 may selectively increase or decrease a
mass flow rate
of heat transfer fluid 135 flowing into and out of air handling unit 110 and
heat transfer
fluid/internal-air heat exchanger of air handling unit 110 to maintain the
relatively high
temperature of heat transfer fluid 135 exiting heat transfer fluid/internal-
air heat exchanger of
air handling unit 110, for example, at the upper limit of the allowed range.
Maintaining the heat
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transfer fluid 135 exiting heat transfer fluid/internal-air heat exchanger of
air handling unit 110
at the upper limit allows hybrid dry air cooling system 100 to continue to use
dry ambient
cooling system 115. For example, in a low-load condition, a constant mass flow
rate of heat
transfer fluid 135 through air handling unit 110 might result in a temperature
of heat transfer
fluid 135 exiting air handling unit 110 of 84 degrees. In this example, if
ambient external air has
a temperature of 85 degrees (warmer than the temperature of heat transfer
fluid 135 exiting
air handling unit 110), cooling from a mechanical chiller or a water chiller
would be required
without any cooling provided by dry ambient cooling system 115, resulting in
unnecessary
consumption of energy and/or water.
[0036] Typically, dry ambient cooling system 115 may operate with lower power
requirements
than refrigeration system 120, so that control system 130 may preferentially
employ dry
ambient cooling system 115 over refrigeration system 120, to the extent that
the temperature
of ambient (e.g., outside) air used to provide cooling of the dry ambient
cooling system 115 can
provide sufficient cooling. However, as the temperature and/or humidity of the
external,
outside, ambient air increases, control system 130 may further employ cooling
by refrigeration
system 120 to cool heat transfer fluid 135, for example, to cool heat transfer
fluid 135 to, e.g.,
75.1 F. Under, for example, low or intermediate load conditions or at times
during a day of
temperature swings (such as at morning or evening), control system 130 may
decrease a
volume of heat transfer fluid flowing into and out of air handling unit 110
and heat transfer
fluid/internal-air heat exchanger of air handling unit 110 to maintain the
temperature of heat
transfer fluid flowing out of air handling unit 110 at the allowed upper limit
of a range. Low or
intermediate load conditions may occur, for example, when there is reduced
heat production
within cooled volume 105.
[0037] Fig. 2 is a schematic diagram of a first implementation of components
of hybrid dry air
cooling system 200. It will be appreciated that the implementation of Fig. 2
is illustrative and
that many other implementations and configurations may be employed. For
example, Fig. 4
illustrates a second implementation of components of a hybrid dry air cooling
system 400 and
Fig. 5 illustrates a third implementation of components of a hybrid dry air
cooling system 500.
Hybrid dry air cooling system 200 may be characterized relative to hybrid dry
air cooling system
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400 and hybrid dry air cooling system 500 in that hybrid dry air cooling
system 200 may not
vary a flow rate of heat transfer fluid into air handling unit 110 (and a heat
transfer
fluid/internal-air heat exchanger thereof), whereas hybrid dry air cooling
system 400 and hybrid
dry air cooling system 500 may vary the flow rate of heat transfer fluid into
air handling unit
110 (and a heat transfer fluid/internal-air heat exchanger thereof).
[0038] As illustrated in Fig. 2, air handling unit 110 may include one or more
blowers or fans
205 that may draw warm return air 210 from within cooled volume 105 (Fig. 1)
across or
through a cooling manifold or heat transfer fluid/internal-air heat exchanger
215. Heat transfer
fluid/internal-air heat exchanger 215 may be coupled to a closed loop of heat
transfer fluid 235
and to the return air 210. Heat transfer fluid 235 is an example of heat
transfer fluid 135 of Fig.
1. Heat transfer fluid/internal-air heat exchanger 215 may thereby cool the
return air 210 using
heat transfer fluid 235, producing cooled supply air 220. Supply air 220 may
then be returned to
cooled volume 105 by fans 205, at a temperature lower than return air 210.
[0039] Pump 225 may operate to circulate heat transfer fluid 235 through its
closed loop
toward dry ambient cooling system 115 and refrigeration system 120.
[0040] Control system 231 is an example of control system 130 in Fig. 1.
Control system 231 in
Fig. 2 is illustrated as connecting to output and input components via
electrical, data,
pneumatic, or physical lines (illustrated with broken lines), Control system
231 may be coupled
to and control operation of mixing valve 236. With reference to Fig. 1, mixing
valve 236 may
operate as mixer 125. For example, mixing valve 236 may be selectively
operated by control
system 231 so that a heat transfer fluid portion 235A of heat transfer fluid
235 may pass
through dry ambient cooling system 115 and/or a heat transfer fluid portion
235B of heat
transfer fluid 235 may pass through a bypass 230 that bypasses ambient cooling
system 115, as
described herein in greater detail. Control system 231 may include one or more
temperature
sensors 138A, 138B, 138C, 138D for example, that may provide temperature
readings from
which control system 231 may control proportional and/or relative operation or
use of dry
ambient cooling system 115 and refrigeration system 120.
[0041] Dry ambient cooling system 115 may include one or more blowers or fans
240 that may
draw ambient (e.g., outside) external air 245 across or through a heat
transfer fluid/external-air
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heat exchanger 250 (e.g., a heat rejection coil or cooling manifold). Heat
transfer fluid/external-
air heat exchanger 250 may be coupled to the closed loop of heat transfer
fluid 235 to receive
heat transfer fluid portion 235A and so may provide cooling of heat transfer
fluid 235 that is
carrying heat from warmed return air 210 from cooled volume 105 (Fig. 1).
After passing across
heat transfer fluid/external-air heat exchanger 250, the ambient external air
245 may be vented
out or returned as return ambient air 255. Temperature sensor 138A may sense
or measure the
temperature of ambient (e.g., outside) external air 245, and temperature
sensor 1386 may
sense or measure the temperature of heat transfer fluid 235 passing out of air
handling unit
110.
[0042] In some embodiments and/or under some conditions, control system 231
may operate
mixing valve 236 to direct some or all of heat transfer fluid 235 as heat
transfer fluid portion
235A passing through dry ambient cooling system 115 or may operate mixing
valve 236 to
direct some or all of heat transfer fluid 235 as heat transfer fluid portion
2356 passing through
bypass 230. The mass flow rate of heat transfer fluid 235 may remain constant
and may be of
the combined flow rates heat transfer fluid portions 235A and 2356. For
example, control
system 231 may operate mixing valve 236 to direct all of heat transfer fluid
235 as heat transfer
fluid portion 235B passing through bypass 230 if the temperature or enthalpy
of ambient (e.g.,
outside) external air 245 measured by temperature sensor 138A is greater than
the
temperature of heat transfer fluid 235 measured by temperature sensor 1386.
[0043] In other embodiments and/or under other conditions, control system 231
may operate
mixing valve 236 to modulate or trim the proportions of heat transfer fluid
portion 235A and
heat transfer fluid portion 235B, as the volumetric flow rate of heat transfer
fluid 235 remains
constant, when the temperature of cooling ambient (e.g., outside) external air
245 measured
by temperature sensor 138A is low enough that ambient cooling system 115 has
more cooling
capacity than is needed to adequately cool heat transfer fluid 235. In these
circumstances, for
example, flow rate or proportion of heat transfer fluid portion 235A entering
ambient cooling
system 115 may be increased and the flow rate or proportion of heat transfer
fluid portion
235B entering bypass 230 may be decreased as the temperature of ambient (e.g.,
outside)
external air 245 measured by temperature sensor 138A decreases to provide
adequate cooling
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of the coincident process heat load that heat transfer fluid/internal-air heat
exchanger 215
absorbs from cooled volume 105. The heat transfer fluid 235 mass flow rate
shall be sufficient
to cool the coincident process heat load in cooled volume 105.
[0044] In embodiments, dry ambient cooling system 115 may further include an
optional
external air/phase-transition refrigerant heat exchanger 260 (also referred to
as a "condenser
coil 260"), which may operate when the heat absorbed by the heat transfer
fluid 235 in heat
transfer fluid/internal-air heat exchanger 215 is not rejected in its entirety
by the flow of
external air 245 over heat transfer fluid/external-air heat exchanger 250.
Control system 231
may control the mass flow rate of external air 245 with fan(s) 240, which may
vary the mass
flow rate of external air 245 entering i) heat transfer fluid/external-air
heat exchanger 250 and
ii) external air/phase-transition refrigerant heat exchanger or condenser coil
260.
[0045] When the heat transfer fluid portion 235A leaving the heat transfer
fluid/external-air
heat exchanger 250 is of insufficiently low temperature to absorb the process
heat load in
cooled volume 105 transferred by heat transfer fluid/internal-air heat
exchanger 215, further
required temperature reduction of the circulating heat transfer fluid 235 may
be accomplished
by refrigeration system 120. Condenser coil 260 may include a "ref hot gas"
connection or
connections 265 and liquid connection or connections 270 through which phrase-
transition
refrigerant 261 of refrigeration system 120 may pass. Couplings between
refrigeration system
120 and external air/phase-transition refrigerant heat exchanger or condenser
coil 260 are
indicated by coupling reference numerals "1" and "2" in Figure 2. The heat of
compression
generated in the refrigeration system 120, may be rejected to the process air
stream 245 at
external air/phase-transition refrigerant heat exchanger or condenser coil
260.
[0046] As a result, external air/phase-transition refrigerant heat exchanger
or condenser coil
260 may provide variable capacity additional cooling of heat transfer fluid
235 as may be
necessary to maintain the proper temperature of heat transfer fluid 235
entering the heat
transfer fluid/internal-air heat exchanger 215 to absorb the process heat
generated in the
cooled volume 105.
[0047] Mixing valve 236 may mix heat transfer fluid portion 235A from dry
ambient cooling
system 115 and heat transfer fluid portion 235B from bypass 230 to provide a
combined or
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mixed flow of heat transfer fluid 235 to refrigeration system 120.
Refrigeration system 120 may
include compressor 275 coupled with a thermal expansion valve 280 and heat
transfer
fluid/phase-transition refrigerant heat exchanger 285 to provide cooling of
heat transfer fluid
235 that depends on the temperature of the outside or ambient air less than
does the
operation of dry ambient cooling system 115.
[0048] In embodiments, control system 231 may further include temperature
sensor 138C to
sense the temperature of heat transfer fluid 235 entering air handling unit
110.
[0049] Control system 231 may also include dew point sensor 139 to sense a dew
point
temperature in cooled volume 105 and/or at heat transfer fluid/internal-air
heat exchanger 215
and control the heat transfer fluid 235 temperature such that the heat
transfer fluid 235
entering the heat transfer fluid/internal-air heat exchanger 215 is above the
dew point
temperature sensed in the cooled volume 105. This may assure that there is no
condensation of
water accumulating in the air handling unit 110 or in cooled volume 105 as the
heat transfer
fluid/internal-air heat exchanger 215 absorbs heat from cooled volume 105, or
in the piping and
devices transporting the heat transfer fluid 235 between the air handling unit
110 and the dry
ambient cooling system 115.
[0050] The control system 231 may calculate the coincident process heat
absorbing load in the
cooled volume 105 based on heat transfer fluid 235 mass flow rate, as may be
measured by
flow rate sensor 290, and entering and leaving temperatures from heat transfer
fluid/internal-
air heat exchanger 215. The control system 231 may reset the entering and
leaving heat
transfer fluid 235 temperatures to provide optimum energy efficient operation
for the heat
rejection apparatus 115 and 120 while maintaining the capacity required to
reject the
coincident heat generated in the cooled volume 105.
[0051] Control system 231 may control the mass flow rate of the air from fans
240 to adjust
heat rejection from of heat transfer fluid portion 235A in heat transfer
fluid/external-air heat
exchanger 250 when the temperature of the leaving heat transfer fluid portion
235A is
sufficient to absorb all of the heat load in heat transfer fluid/internal-air
heat exchanger 215.
When temperature of the heat transfer fluid portion 235A leaving the heat
rejection apparatus
250 reaches the dew point temperature in the cooled volume 105, and when the
coincident
14
CA 2973023 2017-07-12
=
heat load in the cooled volume 105 is rejected in entirety, control system 231
may use valve
236 to mix heat transfer fluid 235B mass flow rate with heat transfer fluid
portion 235A mass
flow rate to maintain the required heat transfer fluid temperature entering
the heat transfer
fluid/internal-air heat exchanger 215 to absorb the coincident heat load in
cooled volume 105
and to assure that heat transfer fluid 235 entering air handling unit 110 is
above the coincident
dew point temperature of the cooled volume 105 as well as the devices and
piping through
which the heat transfer fluid 235 is transported.
[0052] Figures 3A and 3B are flow charts illustrating an example of an
embodiment of a control
system module 300 of a control system of a hybrid dry air cooling system, as
may implement
control system 130 of Fig. 1, control system 231 of Fig. 2, control system 431
of Fig. 4, and
control system 531 of Fig. 5. The control system module 300 may be implemented
in computer
hardware and software, by instructions programmed in electronic circuits, in
firmware, and the
like. Control system module 300 may control output, such as actuators,
including valves,
pumps, electric motors, and the like. Control system module 300 may receive
information from
input components such as thermometers, humidity or moisture sensors,
barometric and liquid
pressure sensors, pumps, flow rate sensors, cameras, and the like, as may be
illustrated in Fig.
2, Fig. 4, and/or Fig. 5. By way of example, an example of control system
module 300 is
illustrated in control system computer 600 in Fig. 6.
[0053] At block 305 of sheet 3 of 5, Fig. 3A, control system module 300 may
measure a
temperature, volume, or volumetric flow rate of heat transfer fluid, such as
heat transfer fluid
entering an internal air cooler, such as heat transfer fluid/internal-air heat
exchanger 215/415.
Control system module 300 may perform this measurement with data from, for
example,
temperature sensor 138C/438C/538C.
[0054] At block 310, control system module 300 may measure a temperature
and/or volume or
flow rate of heat transfer fluid, such as heat transfer fluid existing an
internal air cooler, such as
heat transfer fluid/internal-air heat exchanger 215/415/515. Control system
module 300 may
perform this measurement with data from, for example, temperature sensor
138B/438B/538B
and flow rate sensor 290/490/590 or another flow rate sensor provided for this
purpose (with
respect to Fig. 2, flow rate at flow rate sensor 290 may be assumed to be the
flow rate of heat
CA 2973023 2017-07-12
transfer fluid into heat transfer fluid/internal-air heat exchanger 215; with
respect to Fig. 4 and
Fig. 5, flow rate at flow rate sensor 491/591 may be the flow rate of heat
transfer fluid into heat
transfer fluid/internal-air heat exchanger 415/515).
[0055] At block 311, control system module 300 may measure a temperature,
volume, and/or
humidity of return air from a cooled volume. Control system module 300 may
perform this
measurement with data from, for example, temperature sensor 138D/438D/538D. At
block
311, control system module 300 may also measure a temperature and/or humidity
of ambient
external air, such as with data from temperature sensor 138A/438A/538A.
[0056] At block 315, control system module 300 may determine a heat absorption
load in the
internal air cooler. This may be determined as a change (or delta) in
temperature relative to a
volume of the heat transfer fluid and/or relative to a volume of air to and
from the cooled
volume.
[0057] In opening loop block 320 to closing loop block 365, control system
module 300 may
iterate over conditions when a positive heat absorption load occurs in the
internal air cooler,
such as when cooling is required of return air. These loop blocks may also be
performed for a
determination of heat absorption load that is presumed to apply for a period
of time.
[0058] At block 321, which may be optional (such as with a control system
which does not
modulate overall flow rate of heat transfer fluid), control system module 300
may modulate the
flow rate of heat transfer fluid, above a minimum flow rate required for
proper system
operation. For example, when reduced cooling capacity is required, control
system module 300
may control pump 425/525 to reduce flow rate; when increased cooling capacity
is required,
control system module 300 may control pump 425/525 to increase flow rate.
[0059] At block 325, control system module 300 may determine an enthalpy of
ambient
external air and a cooling capacity of a dry ambient cooling system, such as
dry ambient cooling
system 115 in Fig. 1.
[0060] At decision block 330, control system module 300 may determine whether
there is
remaining, unutilized, cooling capacity in the dry ambient cooling system.
[0061] At block 335, when control system module 300 determines there is not
remaining
cooling capacity in the dry ambient cooling system or equivalent, control
system module 300
16
CA 2973023 2017-07-12
may increase a flow rate of heat transfer fluid to a mechanical cooling system
and/or control
system module 300 may increase a power to the mechanical cooling system, such
as
refrigeration system 120 in Fig. 1. Control system module 300 may also
decrease a flow rate of
heat transfer fluid into the dry ambient cooling system.
[0062] At block 340, when control system module 300 determines there is
remaining cooling
capacity in the dry ambient cooling system or equivalent, control system
module 300 may
reduce a flow rate of heat transfer fluid to the mechanical cooling system.
Control system
module 300 may also increase a flow rate of heat transfer fluid into the dry
ambient cooling
system.
[0063] At decision block 341, control system module 300 may determine whether
ambient
external air is cooler or has lower enthalpy than an upper limit of an allowed
range for the heat
transfer fluid existing the heat transfer fluid/internal air heat exchanger.
[0064] At block 342, the determination at decision block 341 was negative or
equivalent
(ambient external air is not cooler than upper limit), control system module
300 may, at block
344, increase or maintain a flow rate of heat transfer fluid into heat
transfer fluid/internal air
heat exchanger.
[0065] At block 343, the determination at decision block 341 was affirmative
or equivalent
(ambient external air is cooler than upper limit), control system module 300
may, at block 344,
decrease a flow rate of heat transfer fluid into heat transfer fluid/internal
air heat exchanger.
[0066] In this way, if ambient external air is cooler than the upper limit,
then by trimming or
decreasing the flow rate of heat transfer fluid into heat transfer
fluid/internal air heat
exchanger, control system module 300 may thereby increase the temperature of
heat transfer
fluid exiting the heat transfer fluid/internal air heat exchanger, thereby
making it possible for
the dry ambient cooling system to provide some cooling.
[0067] As noted elsewhere, modulating the flow rate of heat transfer fluid
into heat transfer
fluid/internal air heat exchanger may be performed by modulating the flow rate
of heat
transfer fluid in the entire closed loop of heat transfer fluid, thereby
increasing or decreasing
the flow rate in the entire system. Alternatively and/or in addition,
modulating the flow rate
into heat transfer fluid/internal air heat exchanger may be performed by
modulating the flow
17
CA 2973023 2017-07-12
rate into heat transfer fluid/internal air heat exchanger, which may result in
a bypass of heat
transfer fluid external to heat transfer fluid/internal air heat exchanger.
Under such
circumstances, control system module 300 may modulate the flow rate of heat
transfer fluid
external to heat transfer fluid/internal air heat exchanger, for example, to
decrease the flow
rate. The flow rate external to heat transfer fluid/internal air heat
exchanger may be kept at or
above a minimum threshold required for proper system operation.
[0068] Turning to sheet 4 of 5 and Fig. 3B (which continues control system
module 300 from
Fig. 3A), at block 345, control system module 300 may modulate external air
fans, which may
serve both the dry ambient cooling system and external air/phase-transition
refrigerant heat
exchanger or condenser coil 260/460/560, such as to increase or decrease the
fans and the
volume of ambient external air drawn over heat transfer fluid/external air
heat exchanger and
the condenser coil. For example, when cooling capacity remains in the dry
ambient cooling
system and when this cooling capacity is needed or when power is increased to
the mechanical
cooling system, the fans may be increased.
[0069] At block 350, control system module 300 may determine a dew point
temperature in
the cooled volume, such as according to data received at block 311 or
equivalent.
[0070] At decision block 355, control system module 300 may determine whether
the
temperature of heat transfer fluid returning back to heat transfer
fluid/internal air heat
exchanger is above or below the dew point temperature of block 350.
[0071] If the determination at decision block 355 was that the temperature of
heat transfer
fluid returning back to heat transfer fluid/internal air heat exchanger is
below the dew point
temperature, at block 360 control system module 300 may reduce cooling of heat
transfer fluid
(such as via mechanical cooling system and/or dry ambient cooling system)
and/or may reduce
a flow rate of heat transfer fluid into heat transfer fluid/internal air heat
exchanger. This may
be performed within an allowed range.
[0072] Closing loop block 365 may follow decision block 355 or block 360.
Closing loop block
365 may return to opening loop block 320 while a positive load condition
obtains or closing
loop block 365 may return to block 305.
18
CA 2973023 2017-07-12
[0073] At block 370, control system module 300 may return to block 305, if a
done, exit, or
other conclusion condition does not occur.
[0074] At block 399, control system module 300 may conclude and/or may return
to a process
which may have called it.
[0075] Fig. 4 is a schematic diagram of a second implementation of components
of a hybrid dry
air cooling system 400. Hybrid dry air cooling system 400 comprises many of
the components
of hybrid dry air cooling system 200, generally given the same or a similar
name, potentially
with a different reference number.
[0076] As illustrated in Fig. 4, air handling unit 110 may include one or more
blowers or fans
405 that may draw warm return air 410 from within cooled volume 105 (of Fig.
1) across or
through a cooling manifold or heat transfer fluid/internal-air heat exchanger
415. Heat transfer
fluid/internal-air heat exchanger 415 may be coupled to the closed loop of
heat transfer fluid
435 and to the return air 410. Heat transfer fluid/internal-air heat exchanger
415 may thereby
cool the return air 410 using heat transfer fluid 435, producing cooled supply
air 420. Supply air
420 may then be returned to cooled volume 105 by fans 405, at a temperature
lower than
return air 410.
[0077] Pump 425 may be operated by control system 431 to circulate heat
transfer fluid 435
through its closed loop toward dry ambient cooling system 115 and
refrigeration system 120.
Pump 425 may be operated at a variable flow rate to increase or decrease
cooling capacity of
the hybrid dry air cooling system. The variable flow rate may be kept above a
minimum flow
rate required for proper system operation (such as for operation of control
valves, heat
exchangers, and the like).
[0078] Control system 431 in Fig. 4 is illustrated as connecting to output and
input components
via electrical, data, pneumatic, or physical lines (illustrated with broken
lines). Control system
431 is an example of control system 130 in Fig. 1. Control system 431 may be
coupled to and
control operation of valves 437A-437D. With reference to Fig. 1, mixing valves
437A-437D may
operate as mixer 125. For example, mixing valves 437A-437D may be selectively
operated by
control system 431 so that a heat transfer fluid portion 435A of heat transfer
fluid 435 may pass
through dry ambient cooling system 115 and/or a heat transfer fluid portion
435B of heat
19
CA 2973023 2017-07-12
transfer fluid 435 may pass through a bypass 430 that bypasses ambient cooling
system 115, as
described herein in greater detail. Mixing valve 437B and/or pump 425 may be
operated by
control system 431 to operate as mass flow rate controller 126, to control the
flow rate of heat
transfer fluid into air handling unit 110, heat transfer fluid/internal air
heat exchanger 415, and
heat transfer fluid/phase-transition refrigerant heat exchanger 485 as
described further herein.
[0079] Control system 431 may include one or more temperature sensors 438A,
438B, 438C,
438D for example, that may provide temperature readings from which control
system 431 may
control proportional and/or relative operation or use of dry ambient cooling
system 115 and
refrigeration system 120 and activation of valve 437B and/or pump 425.
[0080] Dry ambient cooling system 115 may include one or more blowers or fans
440 that may
draw ambient (e.g., outside) external air 445 across or through a heat
transfer fluid/external-air
heat exchanger 450 (e.g., a heat rejection coil or cooling manifold). Heat
transfer fluid/external-
air heat exchanger 450 may be coupled to the closed loop of heat transfer
fluid 435 to receive
heat transfer fluid portion 435A and so may provide cooling of heat transfer
fluid 435 that is
carrying heat from warmed return air 410 from cooled volume 105 (of Fig. 1).
After passing
across heat transfer fluid/external-air heat exchanger 450, the ambient
external air 445 may be
vented out or returned as return ambient air 455. Temperature sensor 438A may
sense or
measure the temperature of ambient (e.g., outside) external air 445, and
temperature sensor
438B may sense or measure the temperature of heat transfer fluid 435 passing
out of air
handling unit 110.
[0081] In some embodiments and/or under some conditions, control system 431
may operate
pump 425 to modulate the hybrid system cooling capacity by controlling flow
rate of heat
transfer fluid 435. For example, when reduced cooling capacity is required,
control system 431
may reduce a flow rate of heat transfer fluid 435; when increased cooling
capacity is required
control system 431 may increase a flow rate of heat transfer fluid 435.
[0082] In some embodiments and/or under some conditions, control system 431
may operate
mixing valves 437A-437D to direct some or all of heat transfer fluid 435 as
heat transfer fluid
portion 435A passing through dry ambient cooling system 115 or may operate
mixing valves
437A-437D to direct some or all of heat transfer fluid 435 as heat transfer
fluid portion 435B
CA 2973023 2017-07-12
passing through bypass 430. For example, control system 431 may operate mixing
valves 437A-
437D to direct all of heat transfer fluid 435 as heat transfer fluid portion
435B passing through
bypass 430 if the temperature or enthalpy of ambient (e.g., outside) external
air 445 measured
by temperature sensor 438A is greater than the temperature of heat transfer
fluid 435
measured by temperature sensor 438B.
[0083] Control system 431 may vary the mass flow rate of heat transfer fluid
435 into air
handling unit 110, such as by valve 437B and/or pump 425. Control system 431
may do this to
increase or decrease the temperature of heat transfer fluid 435 exiting heat
transfer
fluid/internal air heat exchanger 415. In such case, valve 437B and/or pump
425 may be part of
mass flow rate controller 126. As noted, pump 425 and/or mass flow rate
controller 126 may
also be modulated to vary the cooling capacity of the hybrid cooling system.
[0084] In other embodiments and/or under other conditions, control system 431
may operate
mixing valves 437A-437D to modulate or trim the proportions of heat transfer
fluid portion
435A and heat transfer fluid portion 435B, when the temperature of cooling
ambient (e.g.,
outside) external air 445 measured by temperature sensor 438A is low enough
that ambient
cooling system 115 has more cooling capacity than is needed to adequately cool
heat transfer
fluid 435. In these circumstances, for example, flow rate or proportion of
heat transfer fluid
portion 435A entering ambient cooling system 115 may be increased and the flow
rate or
proportion of heat transfer fluid portion 435B entering bypass 430 may be
decreased as the
temperature of ambient (e.g., outside) external air 445 measured by
temperature sensor 438A
decreases to provide adequate cooling of the coincident process heat load that
heat transfer
fluid/internal-air heat exchanger 415 absorbs from cooled volume 105. The heat
transfer fluid
435 mass flow rate shall be sufficient to cool the coincident process heat
load in the cooled
volume 105.The heat transfer fluid 435 mass flow rate may also be kept above a
minimum
required system pressure, for example, for control valve operation.
[0085] In embodiments, dry ambient cooling system 115 may further include an
optional
external air/phase-transition refrigerant heat exchanger 460 (also referred to
as a "condenser
coil 460"), which may operate when the heat absorbed by the heat transfer
fluid 435 in heat
transfer fluid/internal-air heat exchanger 415 is not rejected in its entirety
by the flow of
21
CA 2973023 2017-07-12
external air 445 over heat transfer fluid/external-air heat exchanger 450.
Control system 431
may control the mass flow rate of external air 445 with fan(s) 440, which may
vary the mass
flow rate of external air 445 entering i) heat transfer fluid/external-air
heat exchanger 450 and
ii) external air/phase-transition refrigerant heat exchanger or condenser coil
460.
[0086] When the heat transfer fluid portion 435A leaving the heat transfer
fluid/external-air
heat exchanger 450 is of insufficiently low temperature to absorb the process
heat load in the
cooled volume 105 transferred by heat transfer fluid/internal-air heat
exchanger 415, further
required temperature reduction of the circulating heat transfer fluid 435 may
be accomplished
by control system 431 through use of refrigeration system 120, such as by
sending (additional)
power to refrigeration system 120. Condenser coil 460 may include a "ref hot
gas" connection
or connections 465 and liquid connection or connections 470 through which
phrase-transition
refrigerant 461 of refrigeration system 120 may pass. Couplings between
refrigeration system
120 and external air/phase-transition refrigerant heat exchanger or condenser
coil 460 are
indicated by coupling reference numerals "1" and "2" in Figure 4. The heat of
compression
generated in the refrigeration system 120, may be rejected to the process air
stream 445 at
external air/phase-transition refrigerant heat exchanger or condenser coil
460.
[0087] As a result, external air/phase-transition refrigerant heat exchanger
or condenser coil
460 may provide variable capacity, additional, cooling of heat transfer fluid
435 as may be
necessary to maintain the proper temperature of heat transfer fluid 435
entering the heat
transfer fluid/internal-air heat exchanger 415 to absorb the process heat
generated in the
cooled volume 105.
[0088] Mixing valves 437A-437D may mix heat transfer fluid portion 435A from
dry ambient
cooling system 115 and heat transfer fluid portion 4358 from bypass 430 to
provide a combined
or mixed flow of heat transfer fluid 435 to refrigeration system 120.
Refrigeration system 120
may include compressor 475 coupled with a thermal expansion valve 480 and heat
transfer
fluid/phase-transition refrigerant heat exchanger 485 to provide cooling of
heat transfer fluid
435 that depends on the temperature of the outside or ambient air less than
does the
operation of dry ambient cooling system 115. In embodiments, all of the pumped
volume of
heat transfer fluid 435 may pass through heat transfer fluid/phase-transition
refrigerant heat
22
CA 2973023 2017-07-12
exchanger 485, with more or less additional cooling capacity being provided by
refrigeration
system 120 and thermal expansion valve 480.
[0089] In embodiments, control system 431 may further include temperature
sensor 438C to
sense the temperature of heat transfer fluid 435 entering air handling unit
110, and may
include a flow rate sensor 490 to sense a fluid flow rate of heat transfer
fluid 435.
[0090] Control system 431 may also include dew point sensor 439 to sense a dew
point
temperature in the cooled volume 105 and/or at heat transfer fluid/internal-
air heat exchanger
415 and control the heat transfer fluid 435 temperature such that the heat
transfer fluid 435
entering the heat transfer fluid/internal-air heat exchanger 415 is above the
dew point
temperature sensed in the cooled volume 105. This may assure that there is no
condensation of
water accumulating in the air handling unit 110 or in the cooled volume 105 as
the heat transfer
fluid/internal-air heat exchanger 415 absorbs heat from the cooled volume 105,
or in the piping
and devices transporting the heat transfer fluid 435 between the air handling
unit 110 and the
dry ambient cooling system 115.
[0091] The control system 431 may calculate the coincident process heat
absorbing load in the
cooled volume 105 based on heat transfer fluid 435 mass flow rate, as may be
measured by
flow rate sensor 290, and entering and leaving temperatures from heat transfer
fluid/internal-
air heat exchanger 415. The control system 431 may reset the entering and
leaving heat
transfer fluid 435 temperatures to provide optimum energy efficient operation
for the heat
rejection apparatus 115 and 120 while maintaining the capacity required to
reject the
coincident heat generated in cooled volume 105.
[0092] Control system 431 may control the mass flow rate of the air from fans
440 to adjust
heat rejection from of heat transfer fluid portion 435A in heat transfer
fluid/external-air heat
exchanger 450 when the temperature of the leaving heat transfer fluid portion
435A is
sufficient to absorb all of the heat load in heat transfer fluid/internal-air
heat exchanger 415.
When temperature of the heat transfer fluid portion 435A leaving the heat
rejection apparatus
450 reaches the dew point temperature in the cooled volume 105, and when the
coincident
heat load in the cooled volume 105 is rejected in entirety, control system 431
may use valves
437A-437D to mix heat transfer fluid 4358 mass flow with heat transfer fluid
portion 435A mass
23
CA 2973023 2017-07-12
flow rate to maintain the required heat transfer fluid temperature entering
the heat transfer
fluid/internal-air heat exchanger 415 to absorb the coincident heat load in
cooled volume 105
and to assure that heat transfer fluid 435 entering air handling unit 110 is
above the coincident
dew point temperature of the cooled volume 105 as well as the devices and
piping through
which the heat transfer fluid 435 is transported.
[0093] Control system 431 may further control valves 437A-437D and in
particular, valve 437B,
to adjust a flow rate of heat transfer fluid 435 through air handling
apparatus 110 and heat
transfer fluid/internal-air heat exchanger 415. As discussed herein,
maintaining a constant flow
rate may result in a temperature of heat transfer fluid 435 exiting heat
transfer fluid/internal-air
heat exchanger 415 that is below an upper limit of an allowed range for the
heat transfer fluid
existing the heat transfer fluid/internal air heat exchanger. When ambient
external air
temperature is below this upper limit, control system 431 may use dry ambient
cooling system
115 to provide free energy cooling with reduced use of mechanical
refrigeration system 120.
[0094] Fig. 5 is a schematic diagram of a second implementation of components
of a hybrid dry
air cooling system 500. Hybrid dry air cooling system 500 comprises many of
the components
of hybrid dry air cooling system 200, generally given the same or a similar
name, potentially
with a different reference number.
[0095] As illustrated in Fig. 5, air handling unit 110 may include one or more
blowers or fans
505 that may draw warm return air 510 from within cooled volume 105 (of Fig.
1) across or
through a cooling manifold or heat transfer fluid/internal-air heat exchanger
515. Heat transfer
fluid/internal-air heat exchanger 515 may be coupled to the closed loop of
heat transfer fluid
535 and to the return air 510. Heat transfer fluid/internal-air heat exchanger
515 may thereby
cool the return air 510 using heat transfer fluid 535, producing cooled supply
air 520. Supply air
520 may then be returned to cooled volume 105 by fans 505, at a temperature
lower than
return air 510.
[0096] Pump 525 may be operated by control system 531 to circulate heat
transfer fluid 535
through its closed loop toward dry ambient cooling system 115 and
refrigeration system 120.
Pump 525 may be operated at a variable flow rate to increase or decrease
cooling capacity of
the hybrid dry air cooling system. The variable flow rate may be kept above a
minimum flow
24
CA 2973023 2017-07-12
rate required for proper system operation (such as for operation of control
valves, heat
exchangers, and the like).
[0097] Control system 531 in Fig. 5 is illustrated as connecting to output and
input components
via electrical, data, pneumatic, or physical lines (illustrated with broken
lines). Control system
531 is an example of control system 130 in Fig. 1. Control system 531 may be
coupled to and
control operation of valves 536. With reference to Fig. 1, valves 536 may
operate as mixer 125.
For example, all of heat transfer fluid 535 circulating in the closed loop of
heat transfer fluid
535, heat transfer fluid portion 535A, may pass through dry ambient cooling
system 115 and
heat transfer fluid/external-air heat exchanger 550; valves 536 may be
selectively operated by
control system 531 such that a heat transfer fluid portion 535B of heat
transfer fluid 535 cooled
by refrigeration system 120 is mixed with heat transfer fluid portion 535A.
Valve 536 and/or
pump 525 may be operated by control system 531 to operate as mass flow rate
controller 126,
to control the flow rate of heat transfer fluid into air handling unit 110,
heat transfer
fluid/internal air heat exchanger 515, and heat transfer fluid/phase-
transition refrigerant heat
exchanger 585 as described further herein.
[0098] Control system 531 may include one or more temperature sensors 538A,
538B, 538C,
538D for example, that may provide temperature readings from which control
system 531 may
control proportional and/or relative operation or use of dry ambient cooling
system 115 and
refrigeration system 120 and activation of valve 536 and/or pump 525.
[0099] Dry ambient cooling system 115 may include one or more blowers or fans
540 that may
draw ambient (e.g., outside) external air 545 across or through a heat
transfer fluid/external-air
heat exchanger 550 (e.g., a heat rejection coil or cooling manifold). Heat
transfer fluid/external-
air heat exchanger 550 may be coupled to the closed loop of heat transfer
fluid 535 to receive
heat transfer fluid portion 535A and so may provide cooling of heat transfer
fluid 535 that is
carrying heat from warmed return air 510 from cooled volume 105 (of Fig. 1).
After passing
across heat transfer fluid/external-air heat exchanger 550, the ambient
external air 545 may be
vented out or returned as return ambient air 555. Temperature sensor 538A may
sense or
measure the temperature of ambient (e.g., outside) external air 545, and
temperature sensor
CA 2973023 2017-07-12
538B may sense or measure the temperature of heat transfer fluid 535 passing
out of air
handling unit 110.
[00100] In some embodiments and/or under some conditions, control system
531 may
operate pump 525 to modulate the hybrid system cooling capacity by controlling
flow rate of
heat transfer fluid 535. For example, when reduced cooling capacity is
required, control system
531 may reduce a flow rate of heat transfer fluid 535; when increased cooling
capacity is
required control system 531 may increase a flow rate of heat transfer fluid
535.
[00101] In some embodiments and/or under some conditions, control system
531 may
operate valves 536 to direct some or all of heat transfer fluid 535 as heat
transfer fluid portion
535A passing through dry ambient cooling system 115 or may operate valves 536
to direct
some or all of heat transfer fluid portion 535B to mix with heat transfer
fluid portion 535A
passing through bypass 530, to provide mechanical cooling to heat transfer
fluid 535.
[00102] Control system 531 may vary the mass flow rate of heat transfer
fluid 535 into
air handling unit 110, such as by valves 536 and/or pump 525. Control system
531 may do this
to increase or decrease the temperature of heat transfer fluid 535 exiting
heat transfer
fluid/internal air heat exchanger 515. In such case, valves 536 and/or pump
525 may be part of
mass flow rate controller 126. As noted, pump 525 and/or mass flow rate
controller 126 may
also be modulated to vary the cooling capacity of the hybrid cooling system.
[00103] In other embodiments and/or under other conditions, control system
531 may
operate mixing valves 536 to modulate or trim the proportions of heat transfer
fluid portion
535A and heat transfer fluid portion 535B, when the temperature of cooling
ambient (e.g.,
outside) external air 545 measured by temperature sensor 538A is low enough
that ambient
cooling system 115 has more cooling capacity than is needed to adequately cool
heat transfer
fluid 535. In these circumstances, for example, flow rate or proportion of
heat transfer fluid
portion 535A entering ambient cooling system 115 may be increased and the flow
rate or
proportion of heat transfer fluid portion 535B entering bypass 530 may be
decreased as the
temperature of ambient (e.g., outside) external air 545 measured by
temperature sensor 538A
decreases to provide adequate cooling of the coincident process heat load that
heat transfer
fluid/internal-air heat exchanger 515 absorbs from cooled volume 105. The heat
transfer fluid
26
CA 2973023 2017-07-12
535 mass flow rate shall be sufficient to cool the coincident process heat
load in the cooled
volume 105.The heat transfer fluid 535 mass flow rate may also be kept above a
minimum
required system pressure, for example, for control valve operation.
[00104] In embodiments, dry ambient cooling system 115 may further include
an
optional external air/phase-transition refrigerant heat exchanger 560 (also
referred to as a
"condenser coil 560"), which may operate when the heat absorbed by the heat
transfer fluid
535 in heat transfer fluid/internal-air heat exchanger 515 is not rejected in
its entirety by the
flow of external air 545 over heat transfer fluid/external-air heat exchanger
550. Control
system 531 may control the mass flow rate of external air 545 with fan(s) 540,
which may vary
the mass flow rate of external air 545 entering i) heat transfer
fluid/external-air heat exchanger
550 and ii) external air/phase-transition refrigerant heat exchanger or
condenser coil 560.
[00105] When the heat transfer fluid portion 535A leaving the heat transfer
fluid/external-air heat exchanger 550 is of insufficiently low temperature to
absorb the process
heat load in the cooled volume 105 transferred by heat transfer fluid/internal-
air heat
exchanger 515, further required temperature reduction of the circulating heat
transfer fluid
535 may be accomplished by control system 531 through use of refrigeration
system 120, such
as by sending (additional) power to refrigeration system 120 and, as
discussed, by using mixing
valves 536 to mix heat transfer fluid portion 535B into heat transfer fluid
portion 535A.
Condenser coil 560 may include a "ref hot gas" connection or connections 565
and liquid
connection or connections 570 through which phrase-transition refrigerant 561
of refrigeration
system 120 may pass. Couplings between refrigeration system 120 and external
air/phase-
transition refrigerant heat exchanger or condenser coil 560 are indicated by
coupling reference
numerals "1" and "2" in Figure 5. The heat of compression generated in the
refrigeration
system 120, may be rejected to the process air stream 545 at external
air/phase-transition
refrigerant heat exchanger or condenser coil 560.
[00106] As a result, external air/phase-transition refrigerant heat
exchanger or
condenser coil 560 may provide variable capacity, additional, cooling of heat
transfer fluid 535
as may be necessary to maintain the proper temperature of heat transfer fluid
535 entering the
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heat transfer fluid/internal-air heat exchanger 515 to absorb the process heat
generated in the
cooled volume 105.
[00107] Mixing valves 536 may mix heat transfer fluid portion 535A from dry
ambient
cooling system 115 and heat transfer fluid portion 535B from bypass 530 to
provide a combined
or mixed flow of heat transfer fluid 535 which passes through refrigeration
system 120 and heat
transfer fluid/phase-transition refrigerant heat exchanger 585. Refrigeration
system 120 may
include compressor 575 coupled with a thermal expansion valve 580 and heat
transfer
fluid/phase-transition refrigerant heat exchanger 585 to provide cooling of
heat transfer fluid
535 that depends on the temperature of the outside or ambient air less than
does the
operation of dry ambient cooling system 115. In embodiments, all of the pumped
volume of
heat transfer fluid 535 may pass through heat transfer fluid/phase-transition
refrigerant heat
exchanger 585, with more or less additional cooling capacity being provided by
refrigeration
system 120 and thermal expansion valve 580.
[00108] In embodiments, control system 531 may further include temperature
sensor
538C to sense the temperature of heat transfer fluid 535 entering air handling
unit 110, may
include a flow rate sensor 590 to sense a fluid flow rate of heat transfer
fluid 535 external to air
handling unit 110, and may include a flow rate sensor 591 to sense a fluid
flow rate of heat
transfer fluid 535 into to air handling unit 110.
[00109] Control system 531 may also include dew point sensor 539 to sense a
dew point
temperature in the cooled volume 105 and/or at heat transfer fluid/internal-
air heat exchanger
515 and control the heat transfer fluid 535 temperature such that the heat
transfer fluid 535
entering the heat transfer fluid/internal-air heat exchanger 515 is above the
dew point
temperature sensed in the cooled volume 105. This may assure that there is no
condensation of
water accumulating in the air handling unit 110 or in the cooled volume 105 as
the heat transfer
fluid/internal-air heat exchanger 515 absorbs heat from the cooled volume 105,
or in the piping
and devices transporting the heat transfer fluid 535 between the air handling
unit 110 and the
dry ambient cooling system 115.
[00110] The control system 531 may calculate the coincident process heat
absorbing load
in the cooled volume 105 based on heat transfer fluid 535 mass flow rate, as
may be measured
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by flow rate sensor 290, and entering and leaving temperatures from heat
transfer
fluid/internal-air heat exchanger 515. The control system 531 may reset the
entering and
leaving heat transfer fluid 535 temperatures to provide optimum energy
efficient operation for
the heat rejection apparatus 115 and 120 while maintaining the capacity
required to reject the
coincident heat generated in cooled volume 105.
[00111] Control system 531 may control the mass flow rate of the air from
fans 540 to
adjust heat rejection from of heat transfer fluid portion 535A in heat
transfer fluid/external-air
heat exchanger 550 when the temperature of the leaving heat transfer fluid
portion 535A is
sufficient to absorb all of the heat load in heat transfer fluid/internal-air
heat exchanger 515.
When temperature of the heat transfer fluid portion 535A leaving the heat
rejection apparatus
550 reaches the dew point temperature in the cooled volume 105, and when the
coincident
heat load in the cooled volume 105 is rejected in entirety, control system 531
may reduce
power to mechanical refrigeration system 120 and/or control system 531 may use
valves 536 to
reduce mixing of heat transfer fluid 535B with heat transfer fluid portion
535A to maintain the
required heat transfer fluid temperature entering the heat transfer
fluid/internal-air heat
exchanger 515 to absorb the coincident heat load in cooled volume 105 and to
assure that heat
transfer fluid 535 entering air handling unit 110 is above the coincident dew
point temperature
of the cooled volume 105 as well as the devices and piping through which the
heat transfer
fluid 535 is transported.
[00112] Control system 531 may further control valves 536 to adjust a flow
rate of heat
transfer fluid 535 through air handling apparatus 110 and heat transfer
fluid/internal-air heat
exchanger 515. As discussed herein, maintaining a constant flow rate may
result in a
temperature of heat transfer fluid 535 exiting heat transfer fluid/internal-
air heat exchanger
515 that is below an upper limit of an allowed range for the heat transfer
fluid existing the heat
transfer fluid/internal air heat exchanger. When ambient external air
temperature is below this
upper limit, control system 531 may use dry ambient cooling system 115 to
provide free energy
cooling with reduced use of mechanical refrigeration system 120.
[00113] Figure 6 is a functional block diagram illustrating an example of
computer device
600 incorporated with the teachings of the present disclosure, according to
some
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embodiments. Computer device may be used, for example, to implement control
system
module 300. Computer device 600 may include chipset 655, comprising processor
603,
input/output (I/O) port(s) and peripheral device interfaces, such as output
interface 640 and
input interface 645, and network interface 630, and computer device memory
650, all
interconnected via bus 620. Network Interface 630 may be utilized to couple
processor 603 to a
network interface card (NIC) to form connections with a network, with computer
device
datastore 601, or to form device-to-device connections with other computers.
[00114] Chipset 655 may include communication components and/or paths,
e.g., buses
620, that couple processor 603 to peripheral devices, such as, for example,
output interface 640
and input interface 645, which may be connected via I/O ports. For example,
chipset 655 may
include a peripheral controller hub (PCH) (not shown). In another example,
chipset 655 may
include a sensors hub. Input interface 645 and output interface 640 may couple
processor 603
to input and/or output devices that include, for example, user and machine
interface device(s)
including actuators, motors, a display, a touch-screen display, printer,
keypad, keyboard, etc.,
sensor(s) including temperature sensors, flow rate sensors, actuator sensors,
inertial
measurement unit, camera , global positioning system (GPS), etc., storage
device(s) including
hard disk drives, solid-state drives, removable storage media, etc. I/O ports
for input interface
645 and output interface 640 may be configured to transmit and/or receive
commands and/or
data according to one or more communications protocols. For example, one or
more of the I/O
ports may comply and/or be compatible with a universal serial bus (USB)
protocol, peripheral
component interconnect (PCI) protocol (e.g., PCI express (PCIe)), or the like.
[00115] Processor 603 may include one or more execution core(s), which may
be central
processing units ("CPUs") and/or graphics processing units ("GPUs") one or
more registers, and
one or more cache memor(ies). Processor 603 may include a memory management
unit (MMU)
to manage memory accesses between processor 603 and computer device memory
650. In
some embodiments, processor 603 may be configured as one or more socket(s);
each socket
may include one or more core(s), a plurality of registers and one or more
cache memor(ies).
Each core may be configured to execute one or more process(es) 665 and/or one
or more
thread(s). A plurality of registers may include a plurality of general purpose
registers, a status
CA 2973023 2017-07-12
register and an instruction pointer. Cache(s) may include one or more cache
memories, which
may be used to cache control system module 300 of the present disclosure.
[00116] Computer device memory 650 may generally comprise a random access
memory
("RAM"), a read only memory ("ROM"), and a permanent mass storage device, such
as a disk
drive or SDRAM (synchronous dynamic random-access memory). Computer device
memory 650
may store program code for software modules or routines, such as, for example,
control system
module 300 (illustrated and discussed further in relation to Figure 3).
[00117] Computer device memory 650 may also store operating system 680.
These
software components may be loaded from a non-transient computer readable
storage medium
695 into computer device memory 650 using a drive mechanism associated with a
non-
transient computer readable storage medium 695, such as a floppy disc, tape,
DVD/CD-ROM
drive, memory card, or other like storage medium. In some embodiments,
software
components may also or instead be loaded via a mechanism other than a drive
mechanism and
computer readable storage medium 695 (e.g., via network interface 630).
[00118] Computer device memory 650 is also illustrated as comprising kernel
685, kernel
space 695, user space 690, user protected address space 660, and computer
device datastore
601.
[00119] Computer device memory 650 may store one or more process 665 (i.e.,
executing software application(s)). Process 665 may be stored in user space
690. Process 665
include one or more other process 665a... 665n. One or more process 665 may
execute
generally in parallel, i.e., as a plurality of processes and/or a plurality of
threads. Process
665vcorresponds to one example of an executing software application.
[00120] Computer device memory 650 is further illustrated as storing
operating system
680 and/or kernel 685. The operating system 680 and/or kernel 685 may be
stored in kernel
space 695. In some embodiments, operating system 680 may include kernel 685.
Process 665
may be unable to directly access kernel space 695. In other words, operating
system 680 and/or
kernel 685 may attempt to protect kernel space 695 and prevent access by
process 665a...
665n.
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[00121] Kernel 685 may be configured to provide an interface between user
processes
and circuitry associated with computer device 600. In other words, kernel 685
may be
configured to manage access to processor 603, chipset 655, I/O ports and
peripheral devices by
process 665. Kernel 685 may include one or more drivers configured to manage
and/or
communicate with elements of computer device 600 (i.e., processor 603, chipset
655, I/O ports
and peripheral devices).
[00122] Computer device datastore 601 may comprise multiple datastores, in
and/or
remote with respect to computer device 600. Datastore 601 may be distributed.
The
components of computer device datastore 601 may include data groups used by
modules
and/or routines, e.g, data and data groups used by control system module 300.
The data
groups used by modules or routines may be represented by a cell in a column or
a value
separated from other values in a defined structure in a digital document or
file. Though referred
to herein as individual records or entries, the records may comprise more than
one database
entry. The database entries may be, represent, or encode numbers, numerical
operators, binary
values, logical values, text, string operators, references to other database
entries, joins,
conditional logic, tests, and similar.
[00123] As used herein, the term "module" (or "logic") may refer to, be
part of, or
include an Application Specific Integrated Circuit (ASIC), a System on a Chip
(SoC), an electronic
circuit, a programmed programmable circuit (such as, Field Programmable Gate
Array (FPGA)), a
processor (shared, dedicated, or group) and/or memory (shared, dedicated, or
group) or in
another computer hardware component or device that execute one or more
software or
firmware programs having executable machine instructions (generated from an
assembler
and/or a compiler) or a combination, a combinational logic circuit, and/or
other suitable
components with logic that provide the described functionality. Modules may be
distinct and
independent components integrated by sharing or passing data, or the modules
may be
subcomponents of a single module, or be split among several modules. The
components may
be processes running on, or implemented on, a single compute node or
distributed among a
plurality of compute nodes running in parallel, concurrently, sequentially or
a combination, as
described more fully in conjunction with the flow diagrams in the figures.
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[00124] While
the invention has been illustrated and described in detail in the drawings
and foregoing description, the same is to be considered as illustrative and
not restrictive in
character, it being understood that only the preferred embodiment has been
shown and
described and that all changes, equivalents, and modifications that come
within the spirit of the
inventions defined by following claims are desired to be protected. All
publications, patents,
and patent applications cited in this specification are herein incorporated by
reference as if
each individual publication, patent, or patent application were specifically
and individually
indicated to be incorporated by reference and set forth in its entirety
herein.
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