CA2915305A1 - Method for operating a heat pump arrangement, and heat pump arrangement - Google Patents
Method for operating a heat pump arrangement, and heat pump arrangement Download PDFInfo
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- CA2915305A1 CA2915305A1 CA2915305A CA2915305A CA2915305A1 CA 2915305 A1 CA2915305 A1 CA 2915305A1 CA 2915305 A CA2915305 A CA 2915305A CA 2915305 A CA2915305 A CA 2915305A CA 2915305 A1 CA2915305 A1 CA 2915305A1
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- fluid
- heat
- heat pump
- temperature
- heating capacity
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B7/00—Compression machines, plants or systems, with cascade operation, i.e. with two or more circuits, the heat from the condenser of one circuit being absorbed by the evaporator of the next circuit
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B30/00—Heat pumps
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B30/00—Heat pumps
- F25B30/02—Heat pumps of the compression type
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
- F25B9/002—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
- Y02B30/52—Heat recovery pumps, i.e. heat pump based systems or units able to transfer the thermal energy from one area of the premises or part of the facilities to a different one, improving the overall efficiency
Abstract
The invention relates to a method for operating a heat pump arrangement (1), wherein a first fluid (26) flows through a first heat pump (2), a second fluid (27) flows through a second heat pump (3), and heat is transferred from the first fluid (26) to the second fluid (27) by means of a heat exchanger (19). A useful heat is drawn from the second fluid (27) at a fluid temperature (21) of at least 120 °C, and the useful heat of the second fluid (27) is dispensed at a volumetric heating power of the first fluid (26) and the second fluid (27) of at least 500 kJ/m3. The invention further relates to such a heat pump arrangement (1).
Description
Description Method for operating a heat pump arrangement, and heat pump arrangement The invention relates to a method for operating a heat pump arrangement according to the preamble of patent claim 1. The invention also relates to a heat pump arrangement according to the preamble of patent claim 8.
Such heat pump arrangements are used for example for industrial heat provision. A heat pump is a machine which, by using technical work, absorbs thermal energy in the form of heat at a lower temperature from a heat source and, together with the drive energy of a compression machine, releases it as waste heat at a higher temperature to a heat sink. For temporary storage or to transfer heat, a fluid is used, which is conveyed within the heat pump in a cycle process by means of the compression machine. This cycle process is also known as a thermodynamic vapor compression cycle.
In the absence of suitable fluids and suitable compression machines for high temperature heat pumps (HTHP), the useful heat from heat pumps which are currently commercially obtainable is limited to temperatures of up to at most 100 C.
The object of the present invention is accordingly to provide a method and a heat pump arrangement by means of which useful heat at particularly high temperatures may be provided.
This object is achieved by a method having the features of patent claim 1 and by a heat pump arrangement having the features of patent claim 8. Advantageous configurations with convenient further developments of the invention are indicated . in the dependent patent claims.
To provide a method of the above-stated type, by means of which useful heat at particularly high temperatures may be provided, provision is made according to the invention for useful heat to be extracted from the second fluid at a fluid temperature of at least 120 C, wherein the useful heat of the second fluid is released at a volumetric heating capacity of the first fluid and of the second fluid of at least 500 kJ/m3. The volumetric heating capacity (VHC) is crucial for the theoretically achievable coefficient of performance (COP) of heat pumps. In other words, the higher the VHC, the more efficiently the heat pump thus operates. Thus, the higher is the volumetric heating capacity above the stated 500 kJ/m3, the higher also is the coefficient of performance (COP) of the respective heat pump.
By means of the second heat pump, particularly high fluid temperatures may be achieved. As a consequence, useful heat at a particularly high temperature may be extracted from the second fluid as a function of the heat transferred by the first fluid.
It has proven advantageous for the useful heat to be extracted from the second fluid at a fluid temperature of at least 150 C
and particularly preferably of at least 160 C. By means of the second heat pump, particularly high fluid temperatures may be achieved. Consequently, useful heat at a particularly high temperature may be extracted from the second fluid, whereby for example useful heat may be provided all the more effectively for industrial use.
In an advantageous configuration of the invention, at least one fluoroketone flows through the first heat pump as the first . fluid. Fluoroketones are particularly safe to use in industry, since there is no need to take special protective measures in the event of an incident. Since the use of fluoroketones is not governed by environmental requirements, use thereof is particularly future-proof. Moreover, they have a particularly low global warming potential and are non-flammable and non-toxic. For this reason, fluoroketones are particularly suitable for use as fluids in heat pump arrangements, in particular if industrial process heat, in particular useful heat at a temperature of greater than 120 C, is provided using these heat pump arrangements.
In a further advantageous configuration of the invention, water or at least one fluoroketone is used as the second fluid. Since they are both environmentally friendly and unobjectionable from the point of view of safety, both water and fluoroketones are suitable in particular as fluids in applications in which high fluid temperatures occur, given that they are neither flammable nor toxic.
It is particularly advantageous for different fluids to be used as the first and second fluids. The coefficient of performance (COP) of the respective heat pump depends on the respective temperature rise. The temperature rise of a heat pump is understood to mean the temperature difference which may be achieved between a respective condenser of the heat pump and a respective evaporator of the heat pump. In accordance with the achievable temperature rise of the first heat pump, waste heat at a particularly high temperature may thus be provided and = transferred by means of the heat exchanger to the second fluid of the second heat pump. The maximum temperature of the second fluid which can be reached using the second heat pump thus depends directly on the quantity of heat transferred by the first fluid. Particularly high coefficients of performance may be achieved using particularly large temperature rises of the respective heat pump, wherein it will be explained below with reference to an example why it is advantageous for fluids of different composition to be used in each case for the first and second fluids. If fluid temperatures of at most 140 C are to be achieved for example using the first heat pump, the use of fluoroketone NOVEC 524 is particularly recommended.
Fluoroketone NOVEC 524 has a particularly high volumetric heating capacity (VHC) in the range from 100 C to 140 C. Since, however, NOVEC 524 is suitable only up to the stated maximum fluid temperature of 140 C, in order for example to achieve a temperature rise from 140 C to 200 C using the second heat pump, it is recommended that water be used as the second fluid, water also being suitable for greater fluid temperatures than 140 C.
It is particularly advantageous for the heat release from the first to the second fluid to proceed largely isothermally.
Through isothermal heat release, the temperature of the released quantity of heat is kept particularly constant, whereby temperature fluctuations are particularly largely ruled out and thus also a largely constant temperature rise may be achieved using the second heat pump. To achieve isothermal heat release using the heat exchanger, the first fluid has to be operated sub-critically, i.e. the first fluid can only be used below its critical temperature. In other words, the first fluid thus has to be operated at a temperature at which both the . liquid and the gaseous physical states may be present.
In a further advantageous configuration of the invention, the useful heat is released at a volumetric heating capacity of at least 1000 kJ/m3, preferably of at least 1200 kJ/m3 and particularly preferably of at least 1500 kJ/m3 of the second fluid. Although the theoretically achievable coefficient of performance (COP) depends on the design of a compression apparatus by means of which the respective fluid of the respective heat pump is compressed, the fluid in the heat pump arrangement should be operated at a point at which a volumetric heating capacity of at least 1000 kJ/m3 is present. The higher the volumetric heating capacity above the stated 1000 kJ/m3, the higher too is the coefficient of performance (COP) of the respective heat pump. If at least 1000 kJ/m3 are needed for the volumetric heating capacity of the respective fluid, water at a temperature of below 150 C cannot for example sensibly be used as the fluid. If a volumetric heating capacity of at least 1500 kJ/m3 is present for a respective fluid, the coefficient of performance (COP) of the respective heat pump is particularly great.
In the heat pump arrangement according to the invention with at least one first heat pump through which a first fluid flows, and a second heat pump through which a second fluid flows, heat may be transferred from the first fluid to the second fluid using a heat exchanger.
In this case, useful heat may be transferred using the second fluid at a fluid temperature of at least 120 C, wherein the , first fluid and the second fluid have a volumetric heating capacity of at least 500 kJ/m3. The higher the volumetric heating capacity, the greater too is the achievable coefficient of performance (COP) of the respective heat pump. Useful heat at a particularly high temperature may in this case be extracted from the second fluid as a function of the heat transferred by the first fluid. To provide a heat pump arrangement, which is also known as a heat pump cascade, in which the second heat pump may provide useful heat at a particularly high temperature, a maximally high volumetric heating capacity of the first fluid of the first heat pump is favorable, wherein it is favorable if the quantity of heat transferred from the first to the second fluid is transferred at a particularly high temperature.
The advantages described above in relation to the method according to the invention apply in the same way to the heat pump arrangement according to the invention and vice versa.
In one advantageous configuration of the heat pump arrangement, at least one temperature rise resulting from a relatively high pressure ratio of the first fluid and/or the second fluid may be increased by means of at least two-stage compression. If particularly large temperature rises are to be achieved with a fluid in a heat pump, two- or multistage compression is recommended. In this case, intermediate cooling may be fitted between the compression apparatuses effecting the respective compression stage. This is sensible in particular where water is used as the fluid. The heat of the intermediate cooling may be fed in a particularly energy-efficient manner to an evaporation apparatus of the respective heat pump. To bring , about very high temperature rises, cascades of more than two heat pump circuits are moreover also possible.
It has been demonstrated that, in a further advantageous configuration of the heat pump arrangement, the second fluid is largely isothermally compressible using a liquid ring compressor. Compression of the fluid may proceed largely isothermally using a liquid ring compressor. The liquid ring of the liquid ring compressor is then in direct contact with the fluid to be compressed, whereby heat of compression may be transferred particularly effectively from the fluid to the ring liquid from which the liquid ring is formed. In other words, the heat transfer resistance is thus particularly low, since the fluid and the ring liquid are not divided from one another by a wall.
Further advantages, features and details of the invention are revealed by the claims, the following description of preferred embodiments and with reference to the figures, in which:
FIG. 1 is a schematic representation of a heat pump cascade according to the prior art, which corresponds to a heat pump arrangement with in the present case two heat pump circuits;
FIG. 2 is a schematic diagram of the respective curves of the volumetric heating capacities of various fluids of the heat pump arrangement plotted against temperature; and FIG. 3 is a schematic representation of a heat pump cascade which corresponds to a heat pump arrangement with two heat pump circuits, wherein one of the heat pump circuits is operated with a fluoroketone as fluid.
FIG. 1 is a schematic representation of a heat pump arrangement which comprises two heat pump circuits and is known in accordance with the prior art as a cascade heat pump 1. The cascade heat pump 1 comprises a first heat pump 2 through which a first fluid flows and a second heat pump 3 through which a second fluid flows. The first and second fluids are coupled together for heat transfer by means of a heat exchanger 19. In this case, the heat exchanger 19 comprises a condenser 6 of the first heat pump 2 and an evaporator 8 of the second heat pump 3. The first fluid of the first heat pump 2 is evaporated by means of an evaporator 4, wherein the evaporator 4 is supplied with thermal energy by means of a heat source 12. The first fluid heated by means of the evaporator 4 is delivered in the direction of an arrow 14 by the first heat pump 2 by means of a compressor 5 of said first heat pump 2. Then the heated and compressed first fluid in the condenser 6 releases heat to the evaporator 8, wherein the second fluid of the second heat pump 3 is evaporated by means of the evaporator 8. Subsequent to this release of heat, the first fluid is expanded by means of an expansion valve 7 of the first heat pump 2 and thereupon once again absorbs heat through the evaporator 4. The circuit of the first heat pump 2 is thus closed. The second fluid of the second heat pump 3 heated by means of the heat exchanger 19, i.e. by release of heat by means of the condenser 6 of the first heat pump 2 to the evaporator 8 of the second heat pump 3, is compressed by means of a compressor 9 of the second heat pimp 3 and in a condenser 10 of the second heat pump 3 releases ,heat to a heat sink 13. Then the second fluid flows in the direction of an arrow 15 through an expansion valve 11 of the second heat pump 3 and is expanded there. Then the second fluid again absorbs heat by means of the heat exchanger 19 and the circuit of the second heat pump 3 is thus closed.
FIG. 2 is a schematic diagram of different curves of volumetric heating capacities, wherein the y axis of the diagram plots a volumetric heating capacity 20 and the x axis plots a fluid temperature 21, which corresponds to the condensing temperature of the fluid. This diagram shows that a heating capacity curve 16, which corresponds to the heating capacity curve of a fluoroketone known as NOVEC 524, in each case has higher values for the same fluid temperatures 21 than a heating capacity curve 17, which corresponds to the heating capacity curve of a fluoroketone known as NOVEC 649. As is clear from the diagram, neither the heating capacity curve 16 nor the heating capacity curve 17 extends over the entire length of the x axis, on which the fluid temperature 21 is plotted. Thus, the heating capacity curve 16 of the fluoroketone NOVEC 524 is limited by reaching a critical point 28 at 148 C and the heating capacity curve 17 of the fluoroketone NOVEC 649 is limited by reaching a critical point 29 at for instance 169 C. Although, as is clear from the diagram, a heating capacity curve 18 which corresponds to the heating capacity curve of water has the lowest volumetric heating capacity 20 in each case for the same fluid temperatures 21 compared with the two fluoroketones, water may be used over a particularly wide range of fluid temperatures = 21, without the critical point thereof being reached. As is additionally clear from FIG. 2, although the heating capacity .curve 18 of water at fluid temperatures below the critical point 28 and the critical point 29 is respectively below the heating capacity curve 16 and the heating capacity curve 17, the heating capacity curve 18 of water rises at high fluid temperatures 21 to greater values than can be achieved with the heating capacity curve 16 and the heating capacity curve 17 as a consequence of the respective critical points 28 and 29 respectively being reached. It is moreover clear that a quantity of heat with a working temperature of at least 160 C
may be released by means of the cascade heat pump 1 to the heat sink 13 if the fluoroketone NOVEC 649 is used as the first fluid of the first heat pump 2. Since, on the basis of the quantity of heat transferred by means of the heat exchanger 19 from this first fluid to the second fluid at a temperature of up to 160 C, the second fluid of the second heat pump 3 is heated further, a temperature of the useful heat even higher than 160 C may be reached by means of the second heat pump 3.
Only subcritically operated fluids are options for the fluid for the first heat pump 2 of the cascade heat pump 1, since heat release from the first fluid to the second fluid should proceed isothermally by means of the heat exchanger 19. To allow isothermal heat release, the first fluid of the first heat pump 2 is operated at a fluid temperature 21 which lies below the critical temperature of the respective critical point 28 or 29. The higher the volumetric heating capacity 20 of a fluid of one of the heat pumps 2, 3, the more efficiently the respective heat pump 2, 3 operates. Thus the theoretically achievable coefficient of performance thereof also increases with a respective higher volumetric heating capacity 20.
As is clear when FIG. 2 and FIG. 3 are looked at together, it is particularly advantageous for a fluoroketone 26 such as for example NOVEC 524 to be used as the first fluid of the first heat pump 2. It should be noted in this respect that the fluid temperature 21 to which the fluoroketone 26 is heated remains below the fundamental critical temperature of the critical point 28, in order to allow isothermal heat release by means of the heat exchanger 19 to the second fluid of the second heat pump 3. Water 27 is used, for example, as the second fluid of the second heat pump 3.
The cascade heat pump 1 illustrated in a schematic representation in FIG. 3 substantially comprises the components already described in FIG. 1, for which reason only the differences will be examined below.
Instead of the condenser 6 and the evaporator 8, the heat exchanger 19 according to FIG. 3 comprises a high temperature condenser 22 of the first heat pump 2 and a high temperature evaporator 23 of the second heat pump 3. Moreover, as is visible in FIG. 3, a liquid ring compressor 24 is used to deliver the water 27 rather than the compressor 9. By means of the liquid ring compressor 24, the water 27, which has been previously evaporated as the result of an input of heat by means of the high temperature evaporator, is now compressed and supplied to a high temperature condenser 25.
Due to the particularly high volumetric heating capacity of the fluoroketone 26 of over 3000 kJ/m3 and thus markedly over 1500 kJ/m3, a quantity of heat is transferred at a fluid temperature 21 of 140 C of the fluoroketone 26, which does not exceed the . critical temperature of the critical point 28, by means of the high temperature condenser 22 of the first heat pump 2 to the high temperature evaporator 23 of the second heat pump 3. Thus, a quantity of heat at a particularly high temperature may be released to the water 27 by means of the high temperature evaporator 23, wherein as a consequence a quantity of useful heat at a particularly high temperature may be released to the heat sink 13 by means of the high temperature condenser 25. If the water 27 which is conveyed as a fluid in the second heat pump 3 is heated to a temperature of for example 200 C by the quantity of heat at 140 C transferred by means of the heat exchanger 19 from the fluoroketone 26 to the water 27, this corresponds to a rise in temperature of 60 C of the water 27.
At 200 C the volumetric calorific value 20 of water 27 amounts to over 4000 kJ/m3, i.e. a markedly higher value than 1500 kJ/m3.
Such heat pump arrangements are used for example for industrial heat provision. A heat pump is a machine which, by using technical work, absorbs thermal energy in the form of heat at a lower temperature from a heat source and, together with the drive energy of a compression machine, releases it as waste heat at a higher temperature to a heat sink. For temporary storage or to transfer heat, a fluid is used, which is conveyed within the heat pump in a cycle process by means of the compression machine. This cycle process is also known as a thermodynamic vapor compression cycle.
In the absence of suitable fluids and suitable compression machines for high temperature heat pumps (HTHP), the useful heat from heat pumps which are currently commercially obtainable is limited to temperatures of up to at most 100 C.
The object of the present invention is accordingly to provide a method and a heat pump arrangement by means of which useful heat at particularly high temperatures may be provided.
This object is achieved by a method having the features of patent claim 1 and by a heat pump arrangement having the features of patent claim 8. Advantageous configurations with convenient further developments of the invention are indicated . in the dependent patent claims.
To provide a method of the above-stated type, by means of which useful heat at particularly high temperatures may be provided, provision is made according to the invention for useful heat to be extracted from the second fluid at a fluid temperature of at least 120 C, wherein the useful heat of the second fluid is released at a volumetric heating capacity of the first fluid and of the second fluid of at least 500 kJ/m3. The volumetric heating capacity (VHC) is crucial for the theoretically achievable coefficient of performance (COP) of heat pumps. In other words, the higher the VHC, the more efficiently the heat pump thus operates. Thus, the higher is the volumetric heating capacity above the stated 500 kJ/m3, the higher also is the coefficient of performance (COP) of the respective heat pump.
By means of the second heat pump, particularly high fluid temperatures may be achieved. As a consequence, useful heat at a particularly high temperature may be extracted from the second fluid as a function of the heat transferred by the first fluid.
It has proven advantageous for the useful heat to be extracted from the second fluid at a fluid temperature of at least 150 C
and particularly preferably of at least 160 C. By means of the second heat pump, particularly high fluid temperatures may be achieved. Consequently, useful heat at a particularly high temperature may be extracted from the second fluid, whereby for example useful heat may be provided all the more effectively for industrial use.
In an advantageous configuration of the invention, at least one fluoroketone flows through the first heat pump as the first . fluid. Fluoroketones are particularly safe to use in industry, since there is no need to take special protective measures in the event of an incident. Since the use of fluoroketones is not governed by environmental requirements, use thereof is particularly future-proof. Moreover, they have a particularly low global warming potential and are non-flammable and non-toxic. For this reason, fluoroketones are particularly suitable for use as fluids in heat pump arrangements, in particular if industrial process heat, in particular useful heat at a temperature of greater than 120 C, is provided using these heat pump arrangements.
In a further advantageous configuration of the invention, water or at least one fluoroketone is used as the second fluid. Since they are both environmentally friendly and unobjectionable from the point of view of safety, both water and fluoroketones are suitable in particular as fluids in applications in which high fluid temperatures occur, given that they are neither flammable nor toxic.
It is particularly advantageous for different fluids to be used as the first and second fluids. The coefficient of performance (COP) of the respective heat pump depends on the respective temperature rise. The temperature rise of a heat pump is understood to mean the temperature difference which may be achieved between a respective condenser of the heat pump and a respective evaporator of the heat pump. In accordance with the achievable temperature rise of the first heat pump, waste heat at a particularly high temperature may thus be provided and = transferred by means of the heat exchanger to the second fluid of the second heat pump. The maximum temperature of the second fluid which can be reached using the second heat pump thus depends directly on the quantity of heat transferred by the first fluid. Particularly high coefficients of performance may be achieved using particularly large temperature rises of the respective heat pump, wherein it will be explained below with reference to an example why it is advantageous for fluids of different composition to be used in each case for the first and second fluids. If fluid temperatures of at most 140 C are to be achieved for example using the first heat pump, the use of fluoroketone NOVEC 524 is particularly recommended.
Fluoroketone NOVEC 524 has a particularly high volumetric heating capacity (VHC) in the range from 100 C to 140 C. Since, however, NOVEC 524 is suitable only up to the stated maximum fluid temperature of 140 C, in order for example to achieve a temperature rise from 140 C to 200 C using the second heat pump, it is recommended that water be used as the second fluid, water also being suitable for greater fluid temperatures than 140 C.
It is particularly advantageous for the heat release from the first to the second fluid to proceed largely isothermally.
Through isothermal heat release, the temperature of the released quantity of heat is kept particularly constant, whereby temperature fluctuations are particularly largely ruled out and thus also a largely constant temperature rise may be achieved using the second heat pump. To achieve isothermal heat release using the heat exchanger, the first fluid has to be operated sub-critically, i.e. the first fluid can only be used below its critical temperature. In other words, the first fluid thus has to be operated at a temperature at which both the . liquid and the gaseous physical states may be present.
In a further advantageous configuration of the invention, the useful heat is released at a volumetric heating capacity of at least 1000 kJ/m3, preferably of at least 1200 kJ/m3 and particularly preferably of at least 1500 kJ/m3 of the second fluid. Although the theoretically achievable coefficient of performance (COP) depends on the design of a compression apparatus by means of which the respective fluid of the respective heat pump is compressed, the fluid in the heat pump arrangement should be operated at a point at which a volumetric heating capacity of at least 1000 kJ/m3 is present. The higher the volumetric heating capacity above the stated 1000 kJ/m3, the higher too is the coefficient of performance (COP) of the respective heat pump. If at least 1000 kJ/m3 are needed for the volumetric heating capacity of the respective fluid, water at a temperature of below 150 C cannot for example sensibly be used as the fluid. If a volumetric heating capacity of at least 1500 kJ/m3 is present for a respective fluid, the coefficient of performance (COP) of the respective heat pump is particularly great.
In the heat pump arrangement according to the invention with at least one first heat pump through which a first fluid flows, and a second heat pump through which a second fluid flows, heat may be transferred from the first fluid to the second fluid using a heat exchanger.
In this case, useful heat may be transferred using the second fluid at a fluid temperature of at least 120 C, wherein the , first fluid and the second fluid have a volumetric heating capacity of at least 500 kJ/m3. The higher the volumetric heating capacity, the greater too is the achievable coefficient of performance (COP) of the respective heat pump. Useful heat at a particularly high temperature may in this case be extracted from the second fluid as a function of the heat transferred by the first fluid. To provide a heat pump arrangement, which is also known as a heat pump cascade, in which the second heat pump may provide useful heat at a particularly high temperature, a maximally high volumetric heating capacity of the first fluid of the first heat pump is favorable, wherein it is favorable if the quantity of heat transferred from the first to the second fluid is transferred at a particularly high temperature.
The advantages described above in relation to the method according to the invention apply in the same way to the heat pump arrangement according to the invention and vice versa.
In one advantageous configuration of the heat pump arrangement, at least one temperature rise resulting from a relatively high pressure ratio of the first fluid and/or the second fluid may be increased by means of at least two-stage compression. If particularly large temperature rises are to be achieved with a fluid in a heat pump, two- or multistage compression is recommended. In this case, intermediate cooling may be fitted between the compression apparatuses effecting the respective compression stage. This is sensible in particular where water is used as the fluid. The heat of the intermediate cooling may be fed in a particularly energy-efficient manner to an evaporation apparatus of the respective heat pump. To bring , about very high temperature rises, cascades of more than two heat pump circuits are moreover also possible.
It has been demonstrated that, in a further advantageous configuration of the heat pump arrangement, the second fluid is largely isothermally compressible using a liquid ring compressor. Compression of the fluid may proceed largely isothermally using a liquid ring compressor. The liquid ring of the liquid ring compressor is then in direct contact with the fluid to be compressed, whereby heat of compression may be transferred particularly effectively from the fluid to the ring liquid from which the liquid ring is formed. In other words, the heat transfer resistance is thus particularly low, since the fluid and the ring liquid are not divided from one another by a wall.
Further advantages, features and details of the invention are revealed by the claims, the following description of preferred embodiments and with reference to the figures, in which:
FIG. 1 is a schematic representation of a heat pump cascade according to the prior art, which corresponds to a heat pump arrangement with in the present case two heat pump circuits;
FIG. 2 is a schematic diagram of the respective curves of the volumetric heating capacities of various fluids of the heat pump arrangement plotted against temperature; and FIG. 3 is a schematic representation of a heat pump cascade which corresponds to a heat pump arrangement with two heat pump circuits, wherein one of the heat pump circuits is operated with a fluoroketone as fluid.
FIG. 1 is a schematic representation of a heat pump arrangement which comprises two heat pump circuits and is known in accordance with the prior art as a cascade heat pump 1. The cascade heat pump 1 comprises a first heat pump 2 through which a first fluid flows and a second heat pump 3 through which a second fluid flows. The first and second fluids are coupled together for heat transfer by means of a heat exchanger 19. In this case, the heat exchanger 19 comprises a condenser 6 of the first heat pump 2 and an evaporator 8 of the second heat pump 3. The first fluid of the first heat pump 2 is evaporated by means of an evaporator 4, wherein the evaporator 4 is supplied with thermal energy by means of a heat source 12. The first fluid heated by means of the evaporator 4 is delivered in the direction of an arrow 14 by the first heat pump 2 by means of a compressor 5 of said first heat pump 2. Then the heated and compressed first fluid in the condenser 6 releases heat to the evaporator 8, wherein the second fluid of the second heat pump 3 is evaporated by means of the evaporator 8. Subsequent to this release of heat, the first fluid is expanded by means of an expansion valve 7 of the first heat pump 2 and thereupon once again absorbs heat through the evaporator 4. The circuit of the first heat pump 2 is thus closed. The second fluid of the second heat pump 3 heated by means of the heat exchanger 19, i.e. by release of heat by means of the condenser 6 of the first heat pump 2 to the evaporator 8 of the second heat pump 3, is compressed by means of a compressor 9 of the second heat pimp 3 and in a condenser 10 of the second heat pump 3 releases ,heat to a heat sink 13. Then the second fluid flows in the direction of an arrow 15 through an expansion valve 11 of the second heat pump 3 and is expanded there. Then the second fluid again absorbs heat by means of the heat exchanger 19 and the circuit of the second heat pump 3 is thus closed.
FIG. 2 is a schematic diagram of different curves of volumetric heating capacities, wherein the y axis of the diagram plots a volumetric heating capacity 20 and the x axis plots a fluid temperature 21, which corresponds to the condensing temperature of the fluid. This diagram shows that a heating capacity curve 16, which corresponds to the heating capacity curve of a fluoroketone known as NOVEC 524, in each case has higher values for the same fluid temperatures 21 than a heating capacity curve 17, which corresponds to the heating capacity curve of a fluoroketone known as NOVEC 649. As is clear from the diagram, neither the heating capacity curve 16 nor the heating capacity curve 17 extends over the entire length of the x axis, on which the fluid temperature 21 is plotted. Thus, the heating capacity curve 16 of the fluoroketone NOVEC 524 is limited by reaching a critical point 28 at 148 C and the heating capacity curve 17 of the fluoroketone NOVEC 649 is limited by reaching a critical point 29 at for instance 169 C. Although, as is clear from the diagram, a heating capacity curve 18 which corresponds to the heating capacity curve of water has the lowest volumetric heating capacity 20 in each case for the same fluid temperatures 21 compared with the two fluoroketones, water may be used over a particularly wide range of fluid temperatures = 21, without the critical point thereof being reached. As is additionally clear from FIG. 2, although the heating capacity .curve 18 of water at fluid temperatures below the critical point 28 and the critical point 29 is respectively below the heating capacity curve 16 and the heating capacity curve 17, the heating capacity curve 18 of water rises at high fluid temperatures 21 to greater values than can be achieved with the heating capacity curve 16 and the heating capacity curve 17 as a consequence of the respective critical points 28 and 29 respectively being reached. It is moreover clear that a quantity of heat with a working temperature of at least 160 C
may be released by means of the cascade heat pump 1 to the heat sink 13 if the fluoroketone NOVEC 649 is used as the first fluid of the first heat pump 2. Since, on the basis of the quantity of heat transferred by means of the heat exchanger 19 from this first fluid to the second fluid at a temperature of up to 160 C, the second fluid of the second heat pump 3 is heated further, a temperature of the useful heat even higher than 160 C may be reached by means of the second heat pump 3.
Only subcritically operated fluids are options for the fluid for the first heat pump 2 of the cascade heat pump 1, since heat release from the first fluid to the second fluid should proceed isothermally by means of the heat exchanger 19. To allow isothermal heat release, the first fluid of the first heat pump 2 is operated at a fluid temperature 21 which lies below the critical temperature of the respective critical point 28 or 29. The higher the volumetric heating capacity 20 of a fluid of one of the heat pumps 2, 3, the more efficiently the respective heat pump 2, 3 operates. Thus the theoretically achievable coefficient of performance thereof also increases with a respective higher volumetric heating capacity 20.
As is clear when FIG. 2 and FIG. 3 are looked at together, it is particularly advantageous for a fluoroketone 26 such as for example NOVEC 524 to be used as the first fluid of the first heat pump 2. It should be noted in this respect that the fluid temperature 21 to which the fluoroketone 26 is heated remains below the fundamental critical temperature of the critical point 28, in order to allow isothermal heat release by means of the heat exchanger 19 to the second fluid of the second heat pump 3. Water 27 is used, for example, as the second fluid of the second heat pump 3.
The cascade heat pump 1 illustrated in a schematic representation in FIG. 3 substantially comprises the components already described in FIG. 1, for which reason only the differences will be examined below.
Instead of the condenser 6 and the evaporator 8, the heat exchanger 19 according to FIG. 3 comprises a high temperature condenser 22 of the first heat pump 2 and a high temperature evaporator 23 of the second heat pump 3. Moreover, as is visible in FIG. 3, a liquid ring compressor 24 is used to deliver the water 27 rather than the compressor 9. By means of the liquid ring compressor 24, the water 27, which has been previously evaporated as the result of an input of heat by means of the high temperature evaporator, is now compressed and supplied to a high temperature condenser 25.
Due to the particularly high volumetric heating capacity of the fluoroketone 26 of over 3000 kJ/m3 and thus markedly over 1500 kJ/m3, a quantity of heat is transferred at a fluid temperature 21 of 140 C of the fluoroketone 26, which does not exceed the . critical temperature of the critical point 28, by means of the high temperature condenser 22 of the first heat pump 2 to the high temperature evaporator 23 of the second heat pump 3. Thus, a quantity of heat at a particularly high temperature may be released to the water 27 by means of the high temperature evaporator 23, wherein as a consequence a quantity of useful heat at a particularly high temperature may be released to the heat sink 13 by means of the high temperature condenser 25. If the water 27 which is conveyed as a fluid in the second heat pump 3 is heated to a temperature of for example 200 C by the quantity of heat at 140 C transferred by means of the heat exchanger 19 from the fluoroketone 26 to the water 27, this corresponds to a rise in temperature of 60 C of the water 27.
At 200 C the volumetric calorific value 20 of water 27 amounts to over 4000 kJ/m3, i.e. a markedly higher value than 1500 kJ/m3.
Claims (10)
1. A method for operating a heat pump arrangement (1), in which a first fluid (26) flows through a first heat pump (2) and a second fluid (27) flows through a second heat pump (3), and in which heat is transferred from the first fluid (26) to the second fluid (27) using a heat exchanger (19), characterized in that useful heat is extracted from the second fluid (27) at a fluid temperature (21) of at least 120°C, wherein the useful heat of the second fluid (27) is released at a volumetric heating capacity (20) of the first fluid (26) and of the second fluid (27) of at least 500 kJ/m3.
2. The method as claimed in claim 1, characterized in that the useful heat is preferably extracted from the second fluid (27) at a fluid temperature (21) of at least 150°C
and particularly preferably of at least 160°C.
and particularly preferably of at least 160°C.
3. The method as claimed in claim 1 or claim 2, characterized in that at least one fluoroketone flows through the first heat pump (2) as the first fluid (26).
4. The method as claimed in one of the preceding claims, characterized in that water or at least one fluoroketone is used as the second fluid (27).
5. The method as claimed in one of the preceding claims, characterized in that different fluids are used as the first fluid (26) and the second fluid (27).
6. The method as claimed in one of the preceding claims, characterized in that heat release from the first fluid (26) to the second fluid (27) proceeds largely isothermally.
7. The method as claimed in one of the preceding claims, characterized in that the useful heat of the second fluid (27) is released at a volumetric heating capacity (20) of the first fluid (26) and the second fluid (27) of at least 1000 kJ/m3, preferably of at least 1200 kJ/m3 and particularly preferably of at least 1500 kJ/m3.
8. A heat pump arrangement (1) having at least one first heat pump (2) through which a first fluid (26) flows, and a second heat pump (3) through which a second fluid (27) flows, in which heat may be transferred from the first fluid (26) to the second fluid (27) using a heat exchanger (19), useful heat may be transferred using the second fluid (27) at a fluid temperature (21) of at least 120°C, wherein the first fluid (26) and the second fluid (27) have a volumetric heating capacity (20) of at least 500 kJ/m3.
9. The heat pump arrangement as claimed in claim 8, characterized in that at least one temperature rise of the first fluid (26) and/or second fluid (27) may be increased by means of at least two-stage compression.
10. The heat pump arrangement as claimed in one of claims 8 or 9, characterized in that the second fluid (27) is largely isothermally compressible using a liquid ring compressor (24).
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE102013211087.1 | 2013-06-14 | ||
| DE102013211087.1A DE102013211087A1 (en) | 2013-06-14 | 2013-06-14 | Method for operating a heat pump assembly and heat pump assembly |
| PCT/EP2014/061528 WO2014198593A1 (en) | 2013-06-14 | 2014-06-04 | Method for operating a heat pump arrangement, and heat pump arrangement |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2915305A1 true CA2915305A1 (en) | 2014-12-18 |
| CA2915305C CA2915305C (en) | 2018-04-10 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2915305A Active CA2915305C (en) | 2013-06-14 | 2014-06-04 | Method for operating a heat pump arrangement, and heat pump arrangement |
Country Status (8)
| Country | Link |
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| US (1) | US20160138837A1 (en) |
| EP (1) | EP2989395A1 (en) |
| JP (1) | JP6526639B2 (en) |
| KR (2) | KR20160018795A (en) |
| CN (1) | CN105264306A (en) |
| CA (1) | CA2915305C (en) |
| DE (1) | DE102013211087A1 (en) |
| WO (1) | WO2014198593A1 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102013214891A1 (en) * | 2013-07-30 | 2015-02-05 | Siemens Aktiengesellschaft | Thermal engineering interconnection of a geothermal energy source with a district heating network |
| EP3158130B1 (en) * | 2014-07-29 | 2018-03-28 | Siemens Aktiengesellschaft | Method and apparatus for drying stock and industrial plant |
| DE112015004688T5 (en) * | 2014-10-18 | 2018-01-18 | Aerosol Dynamics Inc. | Persistent supersaturations for condensation growth of particles |
| KR102096201B1 (en) | 2016-02-26 | 2020-04-01 | 시노켐 란티안 컴퍼니 리미티드 | Composition comprising a fluorine-containing ketone |
| DE102016204158A1 (en) * | 2016-03-14 | 2017-09-14 | Efficient Energy Gmbh | Heat pump system with two stages, method for operating a heat pump system and method for producing a heat pump system |
| DE102017011134B4 (en) | 2017-12-01 | 2022-09-08 | Emz-Hanauer Gmbh & Co. Kgaa | Household refrigeration appliance and method for controlling a light source arrangement arranged in this appliance |
| EP4063762A1 (en) | 2021-03-26 | 2022-09-28 | Mitsubishi Electric R&D Centre Europe B.V. | Cascaded heat pump system with low gwp refrigerant |
| AU2022291952A1 (en) * | 2021-06-16 | 2024-01-04 | Atmoszero, Inc. | Air source heat pump system and method of use for industrial steam generation |
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| SE394741B (en) * | 1974-04-18 | 1977-07-04 | Projectus Ind Produkter Ab | VERMEPUMPSYSTEM |
| FR2374539A1 (en) * | 1976-12-15 | 1978-07-13 | Air Ind | WATER VAPOR COMPRESSION PROCESS, AND THERMAL CIRCUITS FOR ITS IMPLEMENTATION |
| US4149389A (en) * | 1978-03-06 | 1979-04-17 | The Trane Company | Heat pump system selectively operable in a cascade mode and method of operation |
| DE3433366A1 (en) * | 1984-09-08 | 1986-03-20 | Peter 2351 Hasenkrug Koch | Process for the supply and discharge of heat energy, and also heat pump device |
| JPS61138059A (en) * | 1984-12-10 | 1986-06-25 | 三井造船株式会社 | Heat pump for high temperature |
| JPS62190360A (en) * | 1986-02-17 | 1987-08-20 | 株式会社東芝 | Cascade coupled heat pump device |
| US4907410A (en) * | 1987-12-14 | 1990-03-13 | Chang Yan P | Thermal energy from environmental fluids |
| US5241829A (en) * | 1989-11-02 | 1993-09-07 | Osaka Prefecture Government | Method of operating heat pump |
| US7100380B2 (en) * | 2004-02-03 | 2006-09-05 | United Technologies Corporation | Organic rankine cycle fluid |
| KR20070053265A (en) * | 2004-09-17 | 2007-05-23 | 바스프 악티엔게젤샤프트 | Method for operating a liquid ring compressor |
| EP1764487A1 (en) * | 2005-09-19 | 2007-03-21 | Solvay Fluor GmbH | Working fluid for a OCR-process |
| JP5612250B2 (en) * | 2008-03-07 | 2014-10-22 | 出光興産株式会社 | Lubricating oil composition for refrigerator |
| PL2247562T3 (en) * | 2008-03-07 | 2018-03-30 | Arkema, Inc. | Use of r-1233 in liquid chillers |
| US20130091843A1 (en) * | 2008-12-05 | 2013-04-18 | Honeywell International Inc. | Fluoro olefin compounds useful as organic rankine cycle working fluids |
| US8871112B2 (en) * | 2008-11-19 | 2014-10-28 | E I Du Pont De Nemours And Company | Compositions comprising 2,3,3,3-tetrafluoropropene and hydrocarbons and uses thereof |
| FR2941039B1 (en) * | 2009-01-14 | 2013-02-08 | Arkema France | HEAT TRANSFER METHOD |
| IT1396440B1 (en) * | 2009-10-14 | 2012-11-23 | Innovation Factory Scarl | THERMODYNAMIC IRREVERSIBLE CYCLE HEATING DEVICE FOR HEATING SYSTEMS WITH HIGH DELIVERY TEMPERATURE. |
| JP2013510286A (en) * | 2009-11-03 | 2013-03-21 | イー・アイ・デュポン・ドウ・ヌムール・アンド・カンパニー | Cascade refrigeration system using fluoroolefin refrigerant |
| DE202009016576U1 (en) * | 2009-12-08 | 2011-01-13 | Gebhardt, Peter | Apparatus for heat recovery comprising two heat pumps |
| US8846754B2 (en) * | 2009-12-16 | 2014-09-30 | Honeywell International Inc. | Azeotrope-like compositions of cis-1,1,1,4,4,4-hexafluoro-2-butene |
| DE102010001929B4 (en) * | 2010-02-15 | 2014-06-18 | Konvekta Ag | Refrigeration system for cooling an enclosed space |
| US8535559B2 (en) * | 2010-03-26 | 2013-09-17 | 3M Innovative Properties Company | Nitrogen-containing fluoroketones for high temperature heat transfer |
| JP2012172866A (en) * | 2011-02-18 | 2012-09-10 | Showa Denko Kk | Ebullient cooling apparatus |
| DE102011086476A1 (en) * | 2011-09-30 | 2013-04-04 | Siemens Aktiengesellschaft | High temperature heat pump and method of using a working medium in a high temperature heat pump |
| US10385247B2 (en) * | 2014-09-23 | 2019-08-20 | The Chemours Company Fc, Llc | Use of (2E)-1,1,1,4,5,5,5-heptafluoro-4-(trifluoromethyl)pent-2-ene in high temperature heat pumps |
-
2013
- 2013-06-14 DE DE102013211087.1A patent/DE102013211087A1/en not_active Withdrawn
-
2014
- 2014-06-04 JP JP2016518920A patent/JP6526639B2/en active Active
- 2014-06-04 CN CN201480032455.XA patent/CN105264306A/en active Pending
- 2014-06-04 KR KR1020167000674A patent/KR20160018795A/en active Application Filing
- 2014-06-04 EP EP14728920.1A patent/EP2989395A1/en not_active Withdrawn
- 2014-06-04 CA CA2915305A patent/CA2915305C/en active Active
- 2014-06-04 US US14/897,914 patent/US20160138837A1/en not_active Abandoned
- 2014-06-04 KR KR1020187000078A patent/KR20180005281A/en not_active Application Discontinuation
- 2014-06-04 WO PCT/EP2014/061528 patent/WO2014198593A1/en active Application Filing
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|---|---|
| CN105264306A (en) | 2016-01-20 |
| JP6526639B2 (en) | 2019-06-05 |
| DE102013211087A1 (en) | 2015-01-15 |
| EP2989395A1 (en) | 2016-03-02 |
| US20160138837A1 (en) | 2016-05-19 |
| KR20160018795A (en) | 2016-02-17 |
| CA2915305C (en) | 2018-04-10 |
| KR20180005281A (en) | 2018-01-15 |
| JP2016526650A (en) | 2016-09-05 |
| WO2014198593A1 (en) | 2014-12-18 |
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