Note: Descriptions are shown in the official language in which they were submitted.
CA 02621084 2008-02-14
Hot water and heating system operating on the basis of
renewable energy carriers
Description
The invention relates to a hot water and heating system,
which operates on the basis of renewable energy carriers.
For economic and political reasons, the importance of
renewable energies is becoming ever greater. Obtaining
energy from the sun, air or geothermal heat is known in
various embodiments. This also applies to combinations of
the systems with one another.
In the field of housing construction, but also in the case
of offices or commercial buildings, it is particularly
important to produce hot water for heating circuits and/or
for heating fresh water.
The continuous provision of energy poses a substantial
problem in this context. In summer, solar energy is
available virtually limitlessly; but in summer the minimum
requirement also exists for hot water for heating purposes
and/or for heating fresh water.
In transitional periods such as autumn, and in winter, this
requirement increases. When the sky is overcast and
outside temperatures are relatively low, scarcely any
energy contributions of note can be provided via solar
collectors, for example.
It is intended with the invention to provide a hot water
and heating system that permits an all-year-round supply to
residential, office and commercial buildings independently
of the weather as far as possible.
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To achieve this object, the invention starts out from the
following considerations:
The system can be subdivided into various system circuits.
A so-called brine circuit takes care, for example, of the
heating of a carrier medium such as glycol by a solar
collector. If sufficient primary energy (sun) is
available, the brine can be heated to temperatures of 60 ,
100 or more degrees Celsius and transferred directly to
water via a heat exchanger.
Alternatively, the brine circuit can be routed via the
evaporator part of a heat pump, where the brine can be
cooled down for example by 5 -10 C. A refrigerant, which
circulates in the heat pump, is used furthermore to heat
water, which can be stored in an insulated vessel.
The brine circuit, refrigerant circuit and water circuit
are thus linked according to the invention.
The system comprises so-called primary energy heat
exchangers (PHEs). These include said solar collectors,
air heat exchangers or geothermal heat probes in any number
and combination. Using these PHEs, primary energy such as
solar energy is transferred to a heat carrier medium,
termed brine below (for example glycol).
Furthermore, the system comprises a heat pump, which
consists at least of an evaporator part, a compressor, a
condenser part and an expansion device, wherein the heat
pump has a refrigerant, such as C0Z or ammonia, flowing
through it.
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The evaporator part of the heat pump can be formed by a
heat exchanger. This is described as a secondary energy
heat exchanger (SHE), because in the SHE the heat is
transferred from the brine already heated in the PHE to the
refrigerant or vice-versa.
An SHE can also be a heat exchanger that facilitates a heat
transfer from the brine to water.
The condenser part of the heat pump forms a tertiary energy
heat exchanger (THE) in this terminology, as in a third
stage heat is transferred from the refrigerant to water.
The system also includes a so-called buffer tank, which is
used for layered storage of water for at least one closed
water circuit. Since hot water is lighter than cold water,
a temperature gradient from top to bottom results in the
buffer tank. Due to intermediate floors, so-called layer
or layers plates, different sections (temperature zones)
can be delimited from one another, wherein fluidic
connections between the sections are permitted.
The system is connectable to at least one high-temperature
heating circuit (in particular for radiators). To this
end, water with an input temperature of 50 -90 C, for
example, can be taken from the buffer tank. A heating
circuit for low temperatures can likewise be connected, for
example for floor heating systems, which operate at input
flow temperatures of 20 -60 C, for example.
The hot water of the buffer tank can likewise be used for
heating fresh water, for example via an interconnected heat
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exchanger. The buffer tank has corresponding supply and
removal lines for the circulation water for this purpose.
The water supplied to the buffer tank can be routed into
the appropriate temperature zone according to its
temperature.
At least one section (one temperature zone) of the buffer
tank can have a supplementary heating system, in order if
necessary to be able to heat water in the buffer tank
independently of the PfiEs. The supplementary heating can
be realized for example by way of a conventional heating
system using fossil fuels. An electric supplementary
heating system is likewise possible.
All types of heat exchangers, especially plate heat
exchangers, are suitable as SHEs or THEs.
The individual system components, in particular inside the
functional system circuits (brine circuit, refrigerant
circuit, water circuit), can be connected via suitable
multiway valves, which can also be mixing valves,
individually or in groups, if applicable also all at the
same time.
Accordingly the invention relates in its most general
embodiment to a hot water and heating system, which
operates on the basis of renewable energy carriers and
comprises the following features:
- at least one primary energy heat exchanger from the
group:
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CA 02621084 2008-02-14
solar heat exchanger, air heat exchanger, geothermal
heat exchanger,
- each primary energy heat exchanger has at least one
supply line used to transport a cooled brine and at
5 least one return line used to transport the heated
brine,
- the return lines of the primary energy heat exchangers
are directly or indirectly connectable fluidically to
following heat exchangers:
- an evaporator of a heat pump, which evaporator is formed
as a secondary energy heat exchanger, for transferring
heat from the brine to a refrigerant,
- a condenser of the heat pump, which condenser is formed
as a tertiary energy heat exchanger, for transferring
heat from the refrigerant to water,
- an autarkic secondary energy heat exchanger for
transferring heat from the brine to water, wherein
- the water flowing through at least one secondary or
tertiary energy heat exchanger is transportable from a
buffer tank into the respective heat exchanger and from
there directly or indirectly back into the buffer tank,
- from the buffer tank water-conducting lines run to
- at least one heating circuit and/or to
- at least one heat exchanger for transfer to a fresh
water circuit.
The term "autarkic secondary energy heat exchanger"
describes a heat exchanger that is not part of the heat
pump and thus not part of the refrigerant circuit.
The design of all heat exchangers is optional as far as
possible according to the invention. Thus the heat
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exchangers can operate in co-current flow or in counter
current flow. The heat exchangers can be tube heat
exchangers, plate heat exchangers, spiral heat exchangers
and/or rotary heat exchangers, for example.
The buffer tank is used to store the heated water, but also
to return cooled water, for example from the heating
circuit. Different temperature zones are formed in the
buffer tank. The inflow of cold water will accordingly
take place at the bottom and the extraction of hot water
for radiators at the top in the buffer tank vessel.
To be able to adjust/control more easily the switching
states and process variants described below, an embodiment
of the invention provides for all return lines of the
primary energy heat exchangers to be routed via a multiway
valve. It is then possible to set via this valve, for
example, whether the brine flow coming from the air heat
exchanger is routed exclusively to the evaporator of the
heat pump or whether this brine flow is conducted via the
solar collector beforehand, for example.
In the latter case, the return line of a primary energy
heat exchanger is connected fluidically to a supply line of
another primary heat exchanger.
This connection can take place in said multiway valve.
For charging the system in particular, for example for
filling the brine circuit with glycol, the invention
provides for all primary energy heat exchangers and
secondary heat exchangers located in the system and through
which the brine can flow, including supply and return
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lines, to be connected simultaneously fluidically, for
example via said multiway valve.
Similarly, all secondary energy heat exchangers and
tertiary energy heat exchangers located in the system and
through which the refrigerant can flow, including related
supply and return lines, can be connected together
fluidically.
Even the water circuit, thus all secondary energy heat
exchangers and tertiary energy heat exchangers located in
the system and through which water can flow, including
related supply and return lines, can be connected
fluidically in this way. This can be achieved via a
further, common mixing valve, for example.
From this mixing valve a plurality of water-conducting
lines can go off to the buffer tank and discharge into
different sections of the buffer tank.
The buffer tank is part of a closed water circuit, from
which at least one water line can run to at least one high-
temperature heating circuit (for example to heat radiators)
and/or from a section lying below this at least one water
line can run to at least one low-temperature heating
circuit (for example to a floor heating system).
Since the temperature of the return water from the high-
temperature heating circuit is greater than the return
temperature of the water used to heat a floor heating
system, the latter is returned to the buffer tank at a
point which lies below the area into which the return line
from the high-temperature heating circuit discharges.
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However, for indirect heating of the water in the buffer
tank it is also possible to deviate from this system in
that the return line of the high-temperature heating
circuit, with an assumed temperature of 35 C, is conducted
into a cold-water area of the buffer tank at an assumed
20 C, in order to heat the water there.
Further features of the invention are the subject of the
features of the subordinate claims as well as the other
application documents.
The invention is explained in greater detail below with
reference to various embodiments.
Here the figures show, in an extremely schematized
representation -
Fig. 1: a flow chart of a hot water and heating system
according to the invention
Figs. 2a)-f): various system states
The reference sign 10 characterizes a group of solar
collectors, and the reference sign 12 a group of air heat
exchangers. Glycol flows through both as a heat carrier
medium, wherein supply and removal lines 10a, lOb for the
solar collectors 10 and 12a, 12b for the air heat
exchangers 12 are connected to a multiway valve 14.
From the multiway valve 14 a line 16a runs to a plate heat
exchanger 18; the corresponding return line is identified
as 16b. Furthermore, a line 20a runs from the multiway
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valve 14 to a plate heat exchanger 22. The corresponding
return line 20b discharges into the valve 14.
Also connected to the multiway valve 14 are a pressure and
a suction side 24a, 24b of a pump, in order to be able to
pump the glycol flow through the lines 10a, lOb, 12a, 12b,
16a, 16b, 20a, 20b, which together form the glycol circuit
(= brine circuit).
The plate heat exchanger 22 is part of a heat pump, the
related compressor of which is designated 26, the two-stage
condenser of which is designated 28 and the expansion valve
of which is designated 30. The flow paths inside the heat
pump are indicated by arrows.
The first stage 28a of the condenser 28 is formed by a
plate heat exchanger, like the second stage 28b. Both have
water flowing through them in a counter current flow, the
water being pumped (pump 36) from a buffer tank 34 via a
line 32. Inside the condenser part 28a, partial flows of
the heated water can be led away, which is symbolized by
the reference signs 32a, 32b, wherein these lines discharge
into a mixing valve 38. In the mixing valve 38, the water
flows entering via the lines 32a, 32b at differing
temperature are fed directly or following mixing via outlet
lines 40a, 40b, 40c, depending on temperature, into
different zones of the buffer tank 34.
The volume of the buffer tank 34 is divided by intermediate
floors 42, 44 into zones, which are connected fluidically
(at the edge). Accordingly the water with the highest
temperature, for example 60 -90 , is at the top, in chamber
46, below this (between 42 and 44) is a storage chamber for
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water of medium temperature of 30 -60 for example (chamber
48) and finally below the intermediate floor 44 is a cold
water chamber 50.
5 From the chamber 46 a hot water line 52a runs to a spiral
heat exchanger 54 working in counter current flow. The
return line into the chamber 50 of the plate storage device
34 bears the figure 52b. The fresh water flows carried
through in the heat exchanger 54 are identified by 56a,
10 56b.
From the upper part of the chamber 48 a line 58a runs to a
first heating circuit 60, to which radiators (not shown)
are connected. The return line has the reference sign 58b.
A second heating circuit 62 for a low-temperature floor
heating system is coupled to a supply line 64a and a return
line 64b. The supply line runs from the middle part of the
chamber 48 in the buffer tank 34, the return line 46b
discharges into the lower section of chamber 48.
Figure 2a shows a possible set-up of the system according
to figure 1 in winter, when outside temperatures are low
and there is no sunshine.
The flow path of the heat carrier medium (glycol) is
indicated by arrows. At the inlets and outlets of the
related system components, temperatures are indicated by
way of example for the glycol. In this mode of operation,
the solar collectors 10 remain unused, as does the autarkic
heat exchanger 18. The glycol flow is routed with the aid
of the pump 24 exclusively between air heat exchanger 12
and evaporator 22.
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On the other side of the evaporator 22 the refrigerant
evaporates; vapour is then routed through the compressor 26
and heated in the process. It then passes into the
condenser 28, is cooled there still at high pressure and
finally condensed before being routed through the expansion
valve 30. In parallel, water is heated in the condenser 28
(the plate heat exchangers 28a, 28b) in counter current
flow and routed via the lines 32a and/or 32b and 40a, b, c
respectively into the buffer tank 34.
Figure 2b shows a possible system setting in winter when
there is solar radiation. The terminology for figure 2a
applies. The solar collector 10 takes the place of the air
heat exchanger 12, which now remains unused.
In winter it can happen that the air heat exchanger 12 ices
up. For this eventuality the system offers the option of
the reverse operating mode. Water is conducted from the
buffer tank 34 via the heat exchanger 18 in order to heat
the brine (glycol), which is then routed through the air
heat exchanger 12 and thaws this out. The multiway valve
14 is used once more to set the desired flow path (figure
2c).
Figure 2d shows the system management in summer at high
temperatures and with direct solar radiation. The heat
pump, which requires external energy, now remains unused,
as does the air heat exchanger 12. The solar collectors 10
are connected directly to the autarkic heat exchanger 18,
so that a direct heat transfer takes place from the brine
(glycol) to the water. The connection of the collectors to
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the heat exchanger 18 is again controlled/adjusted via the
multiway valve 14.
Figure 2e shows an alternative mode of operation in winter.
Here the brine flow taken from the air heat exchanger 12 is
conducted via the valve 14 into the solar collector 10,
before the brine, by analogy with figure 2b, is routed via
the valve 14 and then the evaporator 22 of the heat pump.
This circuit can be used similarly in summer to avoid
overheating of the solar collector 10 if no further energy
supply to the water storage device is required, for
example. In this operating mode, the brine flow is cooled
by means of the air heat exchanger 12.
The brine flow can also be circulated past the evaporator
22 directly from the solar collector 10 to the air heat
exchanger 12 and back to this end. To do this, a separate
pump is activated.
In figure 2f the entire glycol circuit is shown, wherein
all supply and removal lines are connected to one another
with the aid of the multiway valve 14. This connection
state is used for example to fill the glycol circuit_
The features described in the application can be used
singly or in different combinations, even excluding
individual features, for the invention.
