U.S. patent application number 15/122237 was filed with the patent office on 2016-12-22 for heat pump with a storage tank.
This patent application is currently assigned to Siemens Aktiengesellschaft. The applicant listed for this patent is SIEMENS AKTIENGESELLSCHAFT. Invention is credited to Vladimir Danov, Florian Reissner.
Application Number | 20160370044 15/122237 |
Document ID | / |
Family ID | 52450063 |
Filed Date | 2016-12-22 |
United States Patent
Application |
20160370044 |
Kind Code |
A1 |
Danov; Vladimir ; et
al. |
December 22, 2016 |
Heat Pump With A Storage Tank
Abstract
A device includes a storage tank and a heat pump including at
least one condenser, an expansion valve, an evaporator, and a
compressor. The heat pump includes a working circuit for a
circulating working fluid. The storage tank is arranged between the
condenser and the evaporator with respect to the working circuit,
and the storage tank includes a piston and/or a membrane for
controlling a fluid level of the working fluid in the
condenser.
Inventors: |
Danov; Vladimir; (Erlangen,
DE) ; Reissner; Florian; (Nuernberg, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SIEMENS AKTIENGESELLSCHAFT |
Munchen |
|
DE |
|
|
Assignee: |
Siemens Aktiengesellschaft
Muenchen
DE
|
Family ID: |
52450063 |
Appl. No.: |
15/122237 |
Filed: |
January 21, 2015 |
PCT Filed: |
January 21, 2015 |
PCT NO: |
PCT/EP2015/051138 |
371 Date: |
August 29, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F25B 49/02 20130101;
F25B 2400/0411 20130101; F25B 2400/16 20130101; F25B 45/00
20130101; F25B 41/04 20130101 |
International
Class: |
F25B 45/00 20060101
F25B045/00; F25B 49/02 20060101 F25B049/02; F25B 41/04 20060101
F25B041/04 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 27, 2014 |
DE |
10 2014 203 578.3 |
Claims
1. A device, comprising: a storage tank; and a heat pump
comprising: a condenser, an expansion valve, an evaporator, a
compressor, a working circuit having a circulating working fluid,
wherein the storage tank is arranged, with respect to the working
circuit, between the condenser and the evaporator, and wherein the
storage tank comprises at least one of a piston or a diaphragm that
regulates a fluid level of the working fluid in the condenser.
2. The device of claim 1, wherein the storage tank comprises a
piston and is fluidically coupled to the heat pump via an outlet
value and an inlet valve, wherein the outlet valve, with respect to
the working circuit, is arranged between the condenser and the
expansion valve, and the inlet valve is arranged between the
expansion valve and the evaporator.
3. The device of claim 2, wherein the storage tank comprises a
hydraulic cylinder.
4. The device of claim 2, wherein at least one of the outlet valve
or the inlet valve comprises a further expansion valve and a
non-return valve.
5. The device of claim 1, wherein the storage tank is a collecting
tank comprising a diaphragm, and wherein the collecting tank is
arranged, with respect to the working circuit, between the
condenser and the expansion valve.
6. The device of claim 5, wherein the collecting tank is coupled to
an air compressor, wherein the air compressor feeds compressed air
into a partial volume of the collecting tank, the partial volume
being delimited by the diaphragm.
7. The device of claim 6, wherein the partial volume of the
collecting tank is coupled to a compressed-air outlet valve.
8. The device of claim 5, wherein the collecting tank includes a
displacement unit configured to mechanically displace the
diaphragm.
9. A method for operating a heat pump with a working fluid
circulating within a working circuit, the method comprising:
condensing the working fluid using a condenser, expanding the
working fluid using an expansion valve, evaporating the working
fluid using an evaporator, and compressing the working fluid using
a compressor, guiding the working fluid between the condenser and
the evaporator to a storage tank, and regulating a fluid level of
the working fluid in the condenser using at least one of a piston
or a diaphragm of the storage tank.
10. The method of claim 9, comprising: regulating the fluid level
using the piston, and guiding the working fluid to the storage tank
using an outlet valve.
11. The method of claim 10, comprising guiding the working fluid
from the storage tank back to the heat pump by closing the outlet
valve and opening an inlet valve coupled between the expansion
valve and the evaporate.
12. The method of claim 9, wherein: the storage tank a collecting
tank including a diaphragm that regulates the fluid level, and the
working fluid is guided, with respect to the working circuit,
between the condenser and the expansion valve to the collecting
tank.
13. The method of claim 12, wherein at least a partial volume of
the collecting tank is enlarged or reduced by a mechanical
displacement of the diaphragm.
14. The method of claim 9, comprising regulating the fluid level of
the working fluid if the fluid level of the working fluid in the
condenser exceeds or falls below a threshold value.
15. The method of claim 9, comprising regulating the fluid level of
the working fluid if the temperature of the working fluid exceeds
or falls below a threshold value.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a U.S. National Stage Application of
International Application No. PCT/EP2015/051138 filed Jan. 21,
2015, which designates the United States of America, and claims
priority to DE Application No. 10 2014 203 578.3 filed Feb. 27,
2014, the contents of which are hereby incorporated by reference in
their entirety.
TECHNICAL FIELD
[0002] The invention relates to a device and a method for
regulating a fluid level of a working fluid of a heat pump.
BACKGROUND
[0003] Fluids are typically used as working means (working fluids)
in refrigerating machines, in particular in heat pumps. The working
fluid hereby circulates within a working circuit of the heat pump.
When the heat pump is started up, the working fluid is typically
fed into the working circuit of the heat pump and hence fills the
heat pump.
[0004] In heat pumps known from the prior art, the working circuit
of the working fluid is closed during the operation of the heat
pump. In other words, the working fluid of the heat pump circulates
within a closed working circuit. As a result, it is not possible to
exert any influence on the working circuit of the working fluid, in
particular on temperature changes of the working fluid. Any leaked
working fluid is replaced only during maintenance work on the heat
pump which generally takes place once a year. However, the heat
pump is not operational during maintenance work.
[0005] Heat pumps generally discharge the heat received from a heat
source to a heat sink. Fluctuations in the temperature of the heat
sink, and in the temperature of the heat source, can hereby occur.
Known heat pumps are able to react only inadequately to temperature
fluctuations of the heat sink and/or the heat source. In
particular, the efficiency (coefficient of performance, COP) of the
heat pump is reduced by such temperature fluctuations, depending on
the use.
SUMMARY
[0006] One embodiment provides a device comprising a storage tank
and a heat pump, said heat pump having at least a condenser, an
expansion valve, an evaporator, and a compressor, wherein the heat
pump comprises a working circuit for a circulating working fluid,
wherein the storage tank is arranged, with respect to the working
circuit, between the condenser and the evaporator, and the storage
tank comprises a piston and/or a diaphragm for regulating a fluid
level of the working fluid in the condenser.
[0007] In one embodiment, the storage tank comprises a piston and
is fluidically coupled to the heat pump via an outlet and inlet
valve, wherein the outlet valve, with respect to the working
circuit, is arranged between the condenser and the expansion valve,
and the inlet valve is arranged between the expansion valve and the
evaporator.
[0008] In one embodiment, the storage tank is designed as a
hydraulic cylinder.
[0009] In one embodiment, the outlet and/or inlet valve comprises a
further expansion valve and a non-return valve.
[0010] In one embodiment, the storage tank is designed as a
collecting tank, and comprises a diaphragm, wherein the collecting
tank is arranged, with respect to the working circuit, between the
condenser and the expansion valve.
[0011] In one embodiment, the collecting tank is coupled to an air
compressor, wherein the air compressor is designed to feed
compressed air into a partial volume, delimited by the diaphragm,
of the collecting tank.
[0012] In one embodiment, the partial volume, delimited by the
diaphragm, of the collecting tank is coupled to a compressed-air
outlet valve.
[0013] In one embodiment, the collecting tank has a displacement
unit which is designed to mechanically displace the diaphragm.
[0014] Another embodiment provides a method for operating a heat
pump with a working fluid circulating within a working circuit, in
which the working fluid is condensed by means of a condenser, is
expanded by means of an expansion valve, is evaporated by means of
an evaporator, and compressed by means of a compressor, in which
the working fluid, with respect to the working circuit, is guided
between the condenser and the evaporator to a storage tank, wherein
a fluid level of the working fluid in the condenser is regulated by
means of a piston and/or a diaphragm of the storage tank.
[0015] In one embodiment, the fluid level is regulated by means of
the piston and in which the working fluid is guided to the storage
tank, with respect to the working circuit 42, between the condenser
and the expansion valve by means of an outlet valve.
[0016] In one embodiment, the working fluid is guided, with respect
to the working circuit, between the expansion valve and the
evaporator by means of an inlet valve from the storage tank back to
the heat pump, wherein the outlet valve is closed.
[0017] In one embodiment, the storage tank is designed as a
collecting tank, in which the fluid level is regulated by means of
the diaphragm, and in which the working fluid is guided, with
respect to the working circuit, between the condenser and the
expansion valve to the collecting tank.
[0018] In one embodiment, a first and/or second partial volume,
delimited by the diaphragm, of the collecting tank is enlarged or
reduced by a mechanical displacement of the diaphragm.
[0019] In one embodiment, the fluid level of the working fluid is
regulated if the fluid level of the working fluid in the condenser
exceeds or falls below a threshold value.
[0020] In one embodiment, the fluid level of the working fluid is
regulated if the temperature of the working fluid exceeds or falls
below a threshold value.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Example aspects and embodiments of the invention are
described in detail below with reference to the drawings, in
which:
[0022] FIG. 1 shows a heat pump with a storage tank which is
designed as a hydraulic cylinder; and
[0023] FIG. 2 shows a heat pump with a collecting tank which
comprises a diaphragm for regulating the fluid level.
DETAILED DESCRIPTION
[0024] Embodiments of the present invention may enable adaptation
of a heat pump to temperature fluctuations of a heat sink.
[0025] Some embodiments provide a device comprising a storage tank
and a heat pump, said heat pump having at least a condenser, an
expansion valve, an evaporator and a compressor, wherein the heat
pump comprises a working circuit for a circulating working fluid,
wherein the storage tank is arranged, with respect to the working
circuit, between the condenser and the evaporator, and the storage
tank comprises a piston and/or a diaphragm for regulating a fluid
level of the working fluid in the condenser.
[0026] By virtue of the disclosed arrangement of a storage tank,
which comprises a piston and/or a diaphragm, in the working circuit
of the heat pump, the fluid level of the working fluid in the
condenser of the heat pump can advantageously be regulated. The
fluid level of the working fluid in the condenser of the heat pump
is hereby regulated by the piston, for example by a translational
movement of the piston, and/or by a displacement and/or deformation
of the diaphragm in the storage tank. Regulation of the fluid level
during the operation of the heat pump is enabled in particular by
the disclosed device.
[0027] A height or a level of the fluid column (liquid column) of
the working fluid in the condenser can hereby be used as a measure
of the fluid level. Condensed working fluid typically collects
during the operation of the heat pump at the bottom of the
condenser, wherein the condensed working fluid in the condenser is
supercooled by thermal contact with a heat sink. The fluid level is
hereby provided by the height of the liquid column of the working
fluid collected in the condenser.
[0028] When the fluid level is high, there is more condensed
working fluid at the bottom of the condenser so that overall more
working fluid is in thermal contact with the heat sink and
consequently the working fluid is supercooled to a greater extent.
The supercooling of the working fluid can thus be regulated by
raising or lowering the fluid level. According to the disclosed
device, it is possible to react to temperature fluctuations of the
heat sink by regulating the supercooling of the working fluid in
the condenser. In other words, the supercooling of the working
fluid in the condenser can be adapted to the temperature
fluctuations of the heat sink, the adaptation being effected in
such a way that the heat pump always works in the most efficient
way possible.
[0029] According to the prior art, known heat pumps in contrast
comprise unregulatable supercooling of the working fluid because
the fluid level in the condenser is more or less constant.
Adaptation to the temperature fluctuations of the heat sink
consequently does not take place according to the prior art.
[0030] By regulating the fluid level it is possible to react
directly to fluctuations of the heat sink and/or a heat source by
regulating the supercooling of the working fluid. Increased
supercooling of the working fluid can hereby be advantageous
because the enthalpy difference in the condenser is amplified by
the increased supercooling of the working fluid. The COP and
consequently the efficiency of the heat pump are advantageously
raised as a result.
[0031] A further potential advantage is that large temperature
fluctuations of the heat source and/or the heat sink can be
regulated by means of a small change in the fluid quantity of the
working fluid. As a result, there is no need for an oversized fluid
filling quantity of the working fluid within the working circuit of
the heat pump.
[0032] Moreover, in the case of operation using recuperators,
superheating of a suction gas can advantageously be regulated by
supercooling the working fluid.
[0033] Overall, the fluid level of the working fluid in the
condenser of the heat pump is regulated by means of a piston and/or
a diaphragm, as a result of which the supercooling of the working
fluid is regulated and consequently the efficiency of the heat pump
is improved in the event of temperature fluctuations of the heat
sink.
[0034] In the disclosed method for operating a heat pump, a working
fluid circulating within a working circuit of the heat pump is
condensed by means of a condenser, is expanded by means of an
expansion valve, is evaporated by means of an evaporator, and
compressed by means of a compressor, wherein the working fluid is
guided, with respect to the working circuit, between the condenser
and the evaporator to a storage tank, wherein a fluid level of the
working fluid in the condenser is regulated by means of a piston
and/or a diaphragm of the storage tank.
[0035] In particular, the fluid level of the working fluid in the
heat pump can be regulated by means of a translational movement of
the piston and/or a displacement and/or a deformation of the
diaphragm. Equivalent and similar advantages result for the already
discussed device.
[0036] According to one embodiment, the storage tank which
comprises a piston is fluidically coupled to the heat pump via an
outlet and inlet valve, wherein the outlet valve is arranged, with
respect to the working circuit, between the condenser and the
expansion valve, and the inlet valve is arranged between the
expansion valve and the evaporator.
[0037] Working fluid is thus advantageously guided to the storage
tank downstream from the condenser and upstream from the expansion
valve. This is therefore advantageous as the working fluid is at
high pressure downstream from the compressor and upstream from the
expansion valve. It is consequently possible to remove large
quantities of working fluid for a short period of time from the
working circuit and guide them to the storage tank.
[0038] The working fluid of the heat pump is temporarily stored in
the storage tank in the liquid aggregate state. The working fluid
is hereby preferably fed into the storage tank with the outlet
valve open and the inlet valve closed. The fluid level is regulated
by enlarging and/or reducing the storage volume (volume available
for the working fluid in the storage tank) by means of a
displacement of the piston in a straight line. As a result of
enlarging the storage volume, it is consequently possible for more
working fluid to be held in the storage tank, so that the fluid
level in the condenser is reduced, and reduced supercooling of the
working fluid occurs.
[0039] If the storage volume of the storage tank is now reduced by
means of a displacement of the piston in a straight line, working
fluid is guided from the storage tank, via the inlet valve, back
into the working circuit of the heat pump so that the fluid level
in the condenser is increased and consequently increased
supercooling of the working fluid occurs. When the working fluid
from the storage tank is fed back into the working circuit of the
heat pump, it is expedient to close the outlet valve and open the
inlet valve. During return into the working circuit of the heat
pump, the working fluid can advantageously be caused to evaporate
directly by displacement of the piston.
[0040] A storage tank which is designed as a hydraulic cylinder is
hereby particularly preferred.
[0041] The storage tank can advantageously be formed technically in
a simple fashion by a hydraulic cylinder, preferably by a
double-action hydraulic cylinder. A pressure within the hydraulic
cylinder of no more than 20 MPa is hereby preferred.
[0042] It can moreover be provided to lubricate an upper side of
the piston with a compressor oil so that leaks at the piston of the
hydraulic cylinder are not critical. As a result of the
advantageous use of a hydraulic cylinder, when the evaporation and
condensation temperature of the working fluid is the same,
supercooling in the region of 5 K to 15 K can be achieved by means
of a variation in the fluid level of the working fluid within the
condenser.
[0043] In order to regulate the working fluid in the outlet or
inlet valve, it can be provided that the said valves each comprise
a further expansion valve and a non-return valve.
[0044] As a result, pressure differences between the working
circuit of the heat pump and the storage tank can advantageously be
compensated for.
[0045] In one embodiment, the storage tank is designed as a
collecting tank, wherein the collecting tank comprises a diaphragm
and the collecting tank is arranged, with respect to the working
circuit, between the condenser and the expansion valve.
[0046] In particular, the collecting tank is consequently
integrated directly in the working circuit of the heat pump. Hereby
the working fluid of the heat pump collects in the collecting tank,
wherein the amount of fluid of the working fluid collected in the
collecting tank can be altered by means of the diaphragm. In other
words, a first partial volume of the collecting tank, delimited by
a deformation of the diaphragm, is enlarged or reduced, as a result
of which a second partial volume (collection volume), which is
available for the working fluid within the collecting tank, is
reduced or enlarged.
[0047] If the supercooling of the working fluid in the condenser is
increased, the first partial volume within the collecting tank is
enlarged and consequently the second partial volume is reduced. If
the supercooling is reduced, the first partial volume in the
collecting tank is reduced by the diaphragm so that more liquid
working fluid collects in the second partial volume of the
collecting tank. By regulating the second partial volume
(collection volume) which is available for the working fluid in the
collecting tank by means of the diaphragm, the fluid level of the
working fluid in the condenser is thus changed.
[0048] It is hereby particularly preferred to couple the collecting
tank to an air compressor, wherein the air compressor is designed
to feed compressed air into a partial volume, delimited by the
diaphragm, of the collecting tank.
[0049] The deformation of the diaphragm and the consequent changing
of the first or second partial volume of the collecting tank is
advantageously regulated by means of feeding compressed air into
the first partial volume delimited by the diaphragm. The first
partial volume of the collecting tank is hereby enlarged when
compressed air is fed in so that the second partial volume which is
available for the working fluid within the collecting tank is
reduced. Overall, the fluid level of the working fluid in the
condenser can advantageously be regulated thereby.
[0050] The first partial volume is advantageously reduced by a
compressed-air outlet valve which is coupled to the collecting
tank.
[0051] If compressed air is removed from the first partial volume
of the collecting tank via the compressed-air outlet valve coupled
to the collecting tank, the first partial volume is reduced. By
reducing the first partial volume, the second partial volume which
is available for the working fluid in the collecting tank is
enlarged. In other words, more working fluid thus collects in the
collecting tank so that the supercooling of the working fluid in
the condenser of the heat pump is reduced. By varying or regulating
the feeding-in and release of compressed air, the supercooling of
the working fluid is thus regulated.
[0052] According to one embodiment, the collecting tank comprises a
displacement unit which is designed to mechanically displace the
diaphragm.
[0053] The first partial volume is advantageously enlarged or
reduced by displacing the diaphragm by means of the displacement
unit. As a result, the fluid level of the working fluid in the
condenser of the heat pump can in turn be regulated because the
second volume (collection volume) is correspondingly reduced or
enlarged. The air compressor and the outlet valve can
advantageously be omitted in this embodiment.
[0054] According to one embodiment, the fluid level can be
regulated by means of the piston and/or the diaphragm of the
working fluid if the fluid level of the working fluid in the
condenser falls below or exceeds a threshold value.
[0055] Because the fluid level of the working fluid in the
condenser is positively correlated with the supercooling of the
working fluid, the supercooling of the working fluid is
advantageously regulated via regulating the fluid level. If the
fluid level exceeds a specified level which corresponds, for
example, to the threshold value for the fluid level, the working
fluid may be supercooled too much. The fluid level of the working
fluid must thus be lowered as part of the regulation. In the
opposite case of the fluid level falling below the threshold level,
the fluid level of the working fluid in the condenser can be raised
by regulation so that the desired increased supercooling of the
working fluid is set.
[0056] According to a further embodiment, the fluid level of the
working fluid is regulated if the temperature of the working fluid
exceeds or falls below a threshold value.
[0057] It is, for example, possible to detect the temperature of
the working fluid and consequently the supercooling of the working
fluid directly by measuring the temperature in the condenser. The
temperature of the working fluid in the condenser is hereby
typically indirectly proportional to the fluid level of the working
fluid in the condenser. When the fluid level is high, there is a
high degree of supercooling and hence a low temperature of the
working fluid, whilst when the fluid level is low, the temperature
is higher and hence the supercooling of the working fluid is lower.
The temperature of the working fluid is consequently advantageously
measured inside the condenser of the heat pump. Other points at
which the temperature and/or the fluid level is measured in the
working circuit of the working fluid can be provided.
[0058] FIG. 1 shows a device 1 which comprises a heat pump 4 and a
storage tank 2, wherein the heat pump 4 has a condenser 6, an
expansion valve 8, an evaporator 10, and a compressor 12. The heat
pump 4 is hereby coupled to the storage tank 2 fluidically by means
of a working fluid 24 of the heat pump 4 via an outlet valve 18 and
via an inlet valve 20. The working fluid 24 circulates in the heat
pump 4 in a working circuit 42.
[0059] In the exemplary embodiment of the device 1 shown in FIG. 1,
the storage tank 2 is designed as a hydraulic cylinder 2 and
comprises a piston 14. A storage volume 30 of the hydraulic
cylinder 2 is hereby regulated by means of a straight-line movement
of the piston 14, wherein the straight-line movement is illustrated
in FIG. 1 by the directional arrows 32, 33. In other words, a first
partial volume 30 which is available to the working fluid 24 in the
hydraulic cylinder 2 is enlarged (directional arrow 33) or reduced
(directional arrow 32) by means of the straight-line movement of
the piston 14.
[0060] When the outlet valve 18 is opened and the inlet valve 20 is
closed, the working fluid 24 condensed in the condenser 6 is fed
into the hydraulic cylinder 2 downstream from the condenser 6 and
upstream from the expansion valve 8 with respect to the working
circuit 42 or with respect to a direction of the working circuit
42. The working fluid 24 is hereby advantageously fed into the
hydraulic cylinder 2 upstream from the expansion valve 8 so that
the working fluid 24 is fed into the hydraulic cylinder 2 at high
pressure, for example within the range of 10 MPa to 20 MPa. As a
result of the elevated pressure, large amounts of working fluid 24
can be removed from the working circuit 42 of the heat pump 4 and
fed into the hydraulic cylinder 2 in just a short period of time.
In other words, the mass flow of the working fluid 24 in the outlet
valve 18 is increased as a result of the elevated pressure. Further
expansion valves 21 and non-return valves 22 are provided for the
outlet and inlet valves 18, 20 for regulation purposes.
[0061] The outlet valve 18 is closed and the inlet valve 20 opened
in order to return the working fluid 24 into the working circuit 42
of the heat pump 4. The working fluid 24 is hereby forced out of
the hydraulic cylinder 2 by a straight-line movement--indicated by
the directional arrow 32. The working fluid 24 is returned, with
respect to the working circuit 42, preferably downstream from the
expansion valve 8 at a low pressure level. As a result, the working
fluid 24 can advantageously be caused to evaporate directly.
[0062] If more working fluid 24 is now collected in the hydraulic
cylinder 2 owing to an enlargement in the storage volume 30 by
means of a movement of the piston 14--indicated by the directional
arrow 33--the fluid level of the working fluid 24 in the condenser
6 falls. The lower the fluid level of the working fluid 24 in the
condenser 6, the lower the degree of supercooling. The working
fluid 24 thus leaves the condenser 6 more or less at a point on the
boiling point curve and is thus in thermodynamic equilibrium with
its vapor phase. In other words, the working fluid 24 is not
supercooled, or only slightly.
[0063] Overall, the device 1 shown enables the fluid level of the
working fluid 24 in the condenser 6 of the heat pump 4 to be
regulated such that the supercooling of the working fluid 24 in the
condenser 6 can be regulated. FIG. 2 shows a device 1 which
comprises a heat pump 4 and a collecting tank 3, wherein the heat
pump 4 has a condenser 6, an expansion valve 8, an evaporator 10
and a compressor 12. In the exemplary embodiment of the device 1
shown in FIG. 2, the collecting tank 3 comprises a diaphragm 16
which divides the total volume of the collecting tank 3 into a
first and a second partial volume 30, 31.
[0064] A working fluid 24 circulating in a working circuit 42 of
the heat pump 4 is collected in the second partial volume 31
(collection volume) of the collecting tank 3. The collecting tank 3
is arranged downstream from the condenser 6 and upstream from the
expansion valve 8, with respect to the working circuit 42, and
integrated directly into the working circuit 42 of the heat pump
4.
[0065] The first partial volume 30, which is delimited by the
diaphragm 16, is enlarged by feeding in compressed air by means of
an air compressor 26. Enlarging or reducing the partial volume 30
translates into a reduction or enlargement of the second partial
volume 31. Hereby, the first partial volume 30 is reduced or the
second partial volume 31 is enlarged by removing compressed air by
means of a compressed-air outlet valve 28. If the first partial
volume 30 is enlarged by feeding in compressed air by means of the
air compressor 26, less working fluid 24 is collected in the
collecting tank 3. Consequently more working fluid 24 collects in
the condenser 6 of the heat pump 4. As a result, the working fluid
24 in the condenser 6 is supercooled to a greater degree because
the fluid level in the condenser 6 is raised.
[0066] When the first partial volume 30 is reduced by removing
compressed air by means of the compressed-air outlet valve 28, the
second partial volume 31 is enlarged so that more working fluid 24
collects in the collecting tank 3. As a result, the fluid level of
the working fluid 24 in the working circuit 42 of the heat pump 4
is reduced so that working fluid 24 is extracted from the condenser
6 and the supercooling of the working fluid 24 in the condenser 6
is reduced.
[0067] According to the prior art, known working fluids, for
example R134a and/or R245fa, can be used as working fluids 24.
Working fluids can preferably also be those which comprise at least
one of the substances
1,1,1,2,2,4,5,5,5-nonafluoro-4-(trifluoromethyl)-3-pentanone (trade
name Novec.TM. 649), perfluoromethyl butanone,
1-chloro-3,3,3-trifluoro-1-propene,
cis-1,1,1,4,4,4-hexafluoro-2-butene, and/or cyclopentane. The use
of R134a, R400C, and/or R410a can also be provided.
[0068] Although the invention has been illustrated and described in
detail by the preferred exemplary embodiments, the invention is not
limited by the disclosed example and other variations can be
derived by a person skilled in the art without going beyond the
protective scope of the invention.
* * * * *