WO2014198593A1

WO2014198593A1 - Method for operating a heat pump arrangement, and heat pump arrangement

Info

Publication number: WO2014198593A1
Application number: PCT/EP2014/061528
Authority: WO
Inventors: Bernd Gromoll; Florian REISSNER; Jochen SCHÄFER
Original assignee: Siemens Aktiengesellschaft
Priority date: 2013-06-14
Filing date: 2014-06-04
Publication date: 2014-12-18
Also published as: CA2915305A1; DE102013211087A1; CA2915305C; US20160138837A1; EP2989395A1; KR20180005281A; KR20160018795A; JP2016526650A; JP6526639B2; CN105264306A

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 assembly and heat pump assembly

The invention relates to a method for operating a heat pump arrangement according to the preamble of claim 1. The invention also relates to a heat pump arrangement according to the preamble of claim 8.

Such heat pump arrangements are used for example for industrial heat supply. A heat pump is a machine that uses technical labor to absorb thermal energy in the form of heat from a lower temperature source of heat and, together with the drive energy of a compressor, dissipates it as waste heat to a heat sink with a higher temperature. For temporary storage or for the transfer of heat thereby serves a fluid which is guided within the heat pump by means of the compressor in a cyclic process. This cyclic process is also called thermodynamic vapor compression cycle.

Due to the lack of suitable fluids and suitable compressors for high-temperature heat pumps (HTWP), the useful heat of currently commercially available heat pumps is limited to temperatures of up to 100 ° C.

Object of the present invention is, therefore, reindeer a procedural and to provide a heat pump arrangement by means of which useful heat can be particularly high temperatures bereitge ^¬ represents.

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 Substituted ^¬ staltungen with expedient further developments of the invention are specified in the dependent claims. In order to provide a method of the type mentioned, by means of which useful heat can be provided with particularly high temperatures be ^¬ riding, it is according to the invention provided that the second fluid at a fluid temperature of at least 120 ° C, a useful heat is extracted from the useful heat of the second fluid at a volumetric heating capacity of the first fluid and the second fluid of at least 500 kJ / m ^{3 is} discharged. The volumetric heating capacity (VHC) is decisive for the theoretically achievable coefficient of performance

(COP) of heat pumps. In other words, the heat pump works more efficiently the higher the VHC is. Thus, the higher the volumetric heating capacity is above the said 500 kJ / m ³ , the higher the coefficient of performance (COP) of the respective heat pump. By means of the second heat pump, particularly high fluid temperatures can be achieved. Infolgedes ^¬ sen can be withdrawn from the second fluid in response to the transferred from the first fluid heat, a useful heat with a particularly high temperature.

It has proven to be advantageous if the useful heat at a fluid temperature of at least 150 ° C. and more preferably of at least 160 ° C. is withdrawn from the second fluid. By means of the second heat pump, particularly high fluid temperatures can be achieved. As a result, a useful heat can be withdrawn from the second fluid with a particularly high temperature, which can be provided more effectively, for example, useful heat for industrial use. In an advantageous embodiment of the invention, the first heat pump of at least one fluoroketone as the ers ^¬ th fluid flows through. Fluoroketones are particularly harmless ^¬ industrially applicable, since it can be dispensed with special protective measures in case of danger. Since they can be used free world pads of environmental, Fluoroketones are be ^¬ Sonder's future-proof applications. In addition, they have a particularly low global warming potential, are non-flammable and non-toxic. For this reason, fluoroketones are especially suitable for use as fluids in heat pump arrangements, in particular if by means of these Wärmepumpenanord ^¬ voltages industrial process heat, especially useful heat with a temperature greater than 120 ° C, is provided.

In a further advantageous embodiment of the invention is used as the second fluid water or at least one fluorocheck tone. Since they are both environmentally friendly and safety-harmless, both water and fluoroketones are particularly suitable as fluids in applications in which high fluid temperatures occur. Because they are neither flammable nor poisonous.

It is particularly advantageous if fluids different from one another are used as the first and the second fluid. The coefficient of performance (COP) of the respective heat pump depends on the respective temperature lift. At a tempera ^¬ turhub a heat pump is defined as the temperature difference which can be achieved between a respective capacitor of the heat pump and a respective evaporator of the heat pump. In accordance with the achievable temperature lift of the first heat pump, waste heat of a particularly high temperature can thus be provided and transferred by means of the heat exchanger to the second fluid of the second heat pump. An achievable by means of the second heat pump maximum tempera ture ^¬ of the second fluid thus depends directly on the transferred from the first fluid amount of heat. Particularly high performance can be realized by means of a particularly large temperature lifts of each heat pump weiligen pay ^¬, being illustrated by an example below, which is why it is advantageous to use for the first and the second fluid respectively ^¬ fluids under varying compositions. If, for example, fluid temperatures of a maximum of 140 ° C. are to be achieved by means of the first heat pump, the use of the fluoroketone NOVEC 524 is recommended. The fluorocarbon NOVEC 524 has a particularly high volumetric heat output in the range from 100 ° C. to 140 ° C. (US Pat. VHC). However, since NOVEC 524 ge only up to a maximum fluid temperature of said 140 ° C is suitable, it is recommended to realize by means of the second heat ^¬ pump, for example, a temperature of 140 ° C to 200 ° C, as a second fluid, for example, water ^{enforce ¬} , which is also suitable for fluid temperatures greater than 140 ° C.

It is particularly advantageous is when the heat output from ers ^¬ th on the second fluid is largely isothermal. By an isothermal heat release, the temperature of the heat released amount is kept very constant, whereby tempera ^¬ turschwankungen particularly largely excluded and thus a largely constant temperature increase by means of the second heat pump can be achieved. In order to realize an isothermal Wärmeab ^¬ transfer means of the heat exchanger, the first fluid must be operated subcritical, that is to say that the first fluid can only be used below its critical temperature. In other words, the first fluid must therefore be operated at a temperature at which both the liquid and the gaseous state of aggregation can be present.

In a further advantageous embodiment of the invention, the useful heat at a volumetric heat output of at least 1000 kJ / m ³ , preferably of at least 1200 kJ / m ³ and more preferably of at least 1500 kJ / m ^{3 of} the second

Delivered fluids. Although the COP which is theoretically achievable depends essentially on the type of compressor used to compress the respective fluid of the respective heat pump, the fluid in the heat pump assembly should be operated at a point where the volumetric heating capacity is at least 1000 kJ / m ³ is present. The higher the volumetric heat output above the said 1000 kJ / m ³ , the higher the coefficient of performance (COP) of the respective heat pump. For example, if at least 1,000 kJ m are required for volumetric heating capacity of the fluid jeweili ^¬ gen / ^3, is water having a temperature below 150 ° C are not useful as the fluid used. Lies for a particular fluid a volumetric heating capacity of at least 1500 kJ / m before, so the coefficient of performance (COP) of the respective heat pump is particularly large. 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 can be transferred from the first fluid to the second fluid by means of a heat exchanger.

It is by means of the second fluid at a Fluidtempera- ture of at least 120 ° C, a useful heat transferable, wherein the first fluid and the second fluid having a volumetric heating ^¬ power of at least 500 kJ / m ^3. The higher the volumetric heating capacity, the greater the achievable COP of the respective heat pump. The second fluid can be withdrawn depending on the heat transferred from the first fluid, a useful heat with a particularly high temperature. To fen to sheep, a heat pump arrangement which is also referred to as a heat pump cascade, wherein the second heat pump can provide a useful heat in egg ^¬ ner particularly high temperature, a very high volumetric heat output of the first fluid of the first heat pump is low, which is low is when the heat transferred from the first to the second fluid amount of heat is transmitted at a particularly high temperature.

The advantages described above in connection with the method according to the invention apply equally to the heat pump arrangement according to the invention and vice versa.

In an advantageous embodiment of the heat pump arrangement, at least one temperature stroke can be increased by means of an at least two-stage compression as a result of a higher pressure ratio of the first fluid and / or of the second fluid. If particularly large temperature lifts are to be achieved with a fluid in a heat pump, so emp ^¬ it is appropriate to a two- or multi-stage compression vorzu- see. In this case, an intermediate ^cooling can be installed between the compression devices effecting the respective stage of the compression. This is especially useful for water as a fluid. The heat of the intermediate cooling can be supplied in a particularly energy-efficient manner to an evaporation device of the respective heat pump. In order to realize very high temperature strokes, cascades of more than two heat pump cycles are still possible. As a further advantageous embodiment of the Wärmepumpenanord ^¬ voltage it has been shown, when the second fluid is ver ^¬ sealable by means of a liquid ring compressor ^¬ substantially isothermally. The compression, so the compression of the

Fluids can be largely isothermal by means of a liquid ring compressor. The liquid ring of the liquid ring compressor is in direct contact with the fluid to be compressed, whereby compression heat from the fluid to the ring liquid, from which the liquid ring is formed, can be transferred in a particularly effective manner. In other words, therefore, the heat transfer ^{resistance is} particularly low, since the fluid and the ring liquid are not separated from each other by a wall.

Further advantages, features and details of the invention will become apparent from the claims, the following description of preferred embodiments and with reference to the figures. Showing:

1 shows a schematic diagram of a heat pump cascade according to the prior art, which corresponds to a heat ^¬ pump arrangement with present two heat pump circuits.

2 shows a schematic diagram of a respective course of a volumetric heating power of different fluids of the heat pump arrangement over the temperature; and 3 is a schematic diagram of a Wärmepumpenkaska ^¬ de, which corresponds to a heat pump assembly with two heat pump circuits, one of the heat pump circuits is operated with a fluorine ketone as a fluid.

FIG. 1 shows, in a schematic diagram, a heat pump arrangement which comprises two heat pump circuits and is known as a cascade heat pump 1 according to the state of the art. The cascade heat pump 1 comprises a first heat ^¬ me pump 2, which is flowed through by a first fluid and a second heat pump 3, which is flowed through by a second fluid. By means of a heat exchanger 19, the first and the second fluid are heat-coupled ge ^¬ coupled. The heat exchanger 19 in this case comprises a Kondensa ^¬ gate 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 an evaporator 4 in which the evaporator 4 is supplied by a heat source 12 with thermal energy , The first fluid heated by the evaporator 4 according to the arrow direction of an arrow 14 by means of a compressor 5 of the first heat pump 2 through the first heat pump 2 ^¬ promoted. Subsequently, the heated and compressed first fluid in the condenser 6 gives off heat to the evaporator 8, the second fluid of the second heat pump 3 being evaporated by means of the evaporator 8. Following this heat dissipation, the first fluid is expanded by means of an expansion Sven ^¬ TILs 7 of the first heat pump 2 and then takes heat in turn through the evaporator 4 at. Thus, the

Closed circuit of the first heat pump 2. The second fluid of the second heat pump 3 heated by means of the heat exchanger 19, that is to say by heat emission by means of the condenser 6 of the first heat pump 2 to the evaporator 8 of the second heat pump 3, is heated by means of a compressor 9 of the second

Heat pump 3 compresses and releases heat in a condenser 10 of the second heat pump 3 to a heat sink 13. At the ^¬ circuit because the second fluid flows in accordance with arrow direction of an arrow 15 through an expansion valve 11 of the second heat pump 3 and is expanded there. Following this, the second fluid again absorbs heat by means of the heat exchanger 19 and the cycle of the second heat pump 3 is thus closed.

FIG. 2 shows schematically in a diagram different curves of volumetric heating powers, wherein a volumetric heating power 20 is plotted on the ordinate axis of the diagram and a fluid temperature 21 which corresponds to the condensation temperature of the fluid is plotted on the abscissa axis. In this diagram, it can be seen that a heating power curve 16, which corresponds to the heating power curve of a fluor ^¬ ketone called NOVEC 52 for each same fluid temperatures 21 has higher values, as a Heizleis ^¬ ment curve 17, which corresponds to the heating power curve of a Flu ^¬ orketons called NOVEC 649. As shown in the diagram, it is recognizable ^¬ extends neither the heating power curve 16 nor the heating power curve 17 over the entire length of the axis of abscissa, on which the fluid temperature is aufgetra ^¬ gen 21st Thus, the heating power curve 16 of the fluoroketone NOVEC 524 is limited by reaching a critical point 28 at 148 ° C. and the heat output curve 17 of the fluoroketone NOVEC 649 by reaching a critical point 29 at approximately 169 ° C. A heating power curve 18, which corresponds to the heat ^¬ performance ^curve of water, although, as shown in the diagram, for each same fluid temperatures 21 compared to the two fluoroketones the lowest volumetric heat output 20, but water is over a particularly wide range of fluid temperature 21st can be used without its critical point being reached. As shown in FIG. 2 further be appreciated, although the heating power curve 18 of water is fluid temperatures below the kriti ^¬ rule point 28 and the critical point 29 below the heating power curve 16 and the

Heizleistungsverlaufs 17 However, the heating power curve 18 of water at high fluid temperatures 21 increases to greater values than the heating power curve 16 and the Heat output curve 17 can be achieved as a result of the respective achievement of the respective critical points 28 and 29. It is also seen that an amount of heat can be delivered at a useful temperature of wenigs- least 160 ° C to the heat sink 13 by means of the cascade heat ^¬ pump 1 when the fluoroketone NOVEC is used 649 as the first fluid of the first heat ^¬ pump. 2 Since, starting from the transmitted by means of the heat exchanger 19 of this first fluid to the second fluid amount of heat at a temperature of up to 160 ° C, the second fluid of the second heat pump 3 further he ^¬ is heated, are for the temperature of the available heat even more than 160 ° C realized by means of the second heat pump 3.

As a fluid for the first heat pump 2 of the cascade heat pump 1 are only subcritically operated fluids in question, as the

Heat transfer from the first fluid to the second fluid by means of the heat exchanger 19 is to take place isothermally. In order to enable an isothermal heat release, the first fluid of the first heat pump 2 is operated at a fluid temperature 21 which is below the critical temperature of the respective critical point 28, 29. The higher the volumetric heat output 20 of a fluid of one of the heat pumps 2, 3, the more effi ^¬ cient the respective heat pump 2, 3 operates. Thus, their theoretically achievable coefficient of performance increases with a respective higher volumetric heat output 20.

As in synopsis of FIG. 2 and FIG. 3 is recognizable, it is particularly advantageous to use as the first fluid of the first heat ^¬ pump 2, a fluorinated ketone 26 such as NOVEC 524. It should be noted that the fluid temperature ^¬ structure 21 to which the fluoroketone is heated 26 remains below the underlying critical temperature of the critical point 28 to an isothermal heat dissipation by means of the heat exchanger 19 to the second fluid of the second heat pump pe 3 to allow. As a second fluid of the second heat pump 3, water 27 is used by way of example. The in FIG. FIG. 3 shows a cascade heat pump 1 shown in a schematic diagram, which essentially has the structure shown in FIG. 1 components already described, which is why in the following only the differences should be discussed.

Instead of the condenser 6 and the evaporator 8, the heat exchanger 19 comprises according to FIG. 3, a high-temperature condenser 22 of the first heat pump 2 and a high-temperature evaporator 23 of the second heat pump 3. Further, as shown in FIG. 3 recognizable for conveying the water 27 instead of the compressor 9, a liquid ring compressor 24 is used. By means of the liquid ring compressor 24, the water 27, which was previously evaporated as a result of heat input by means of the high-temperature evaporator, now compressed and fed to a high-temperature condenser 25.

Due to the particularly high volumetric heating capacity of the fluoroketone 26 of about 3000 kJ / m ³ and thus considerably more than 1500 kJ / m ^3, a quantity of heat at a fluid temperature of 21 of 140 ° C of the fluoroketone 26 that the critical temperature ^¬ structure of the critical point 28 does not exceed, 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 transmitted. Thus, by means of the high-temperature evaporator 23, a heat quantity with a particularly high temperature to the ^water 27 are discharged, as a result, a Nutzwärmemenge with particularly high temperature by means of the high ^¬ temperature ^capacitor 25 delivered to the heat sink 13 ^¬ who can. Is the water 27, which is guided as a fluid in the second heat pump 3, from the means of the

Heat exchanger 19 heated by the fluorinated ketone 26 on the water 27 ^¬ amount of heat at 140 ° C to a temperature of ^¬ example 200 ° C, this corresponds to a Tempera ^¬ turhub of 60 ° C of water 27. At 200 ° C is the volumetric heating value metric 20 of water 27 over 4000 kJ / m ^3, ie ei ^¬ nem significantly greater value than 1500 kJ / m ^3.

Claims

claims

1. A method for operating a heat pump assembly (1), wherein a first heat pump (2) by a first fluid (26) and a second heat pump (3) by a second fluid (27) are flowed through, and wherein heat by means of a

Heat exchanger (19) of the first fluid (26) is transmitted to the two ^¬ te fluid (27),

characterized in that

the second fluid (27) at a fluid temperature (21) has a useful heat is extracted from at least 120 ° C, wherein the useful ^¬ heat of the second fluid (27) at a volumetric heat output (20) of the first fluid (26) and the second fluid (27) of at least 500 kJ / m ^{3 is} delivered.

2. The method according to claim 1,

characterized in that

the useful heat is preferably withdrawn from the second fluid (27) at a fluid temperature (21) of at least 150 ° C and particularly preferably of at least 160 ° C.

3. The method according to claim 1 or 2,

characterized in that

the first heat pump (2) is flowed through by at least one fluorine ketone as the first fluid (26).

4. The method according to any one of the preceding claims,

characterized in that

as the second fluid (27), water or at least one fluoro ketone is used.

5. The method according to any one of the preceding claims,

characterized in that

as the first fluid (26) and the second fluid (27) of different fluids are used.

6. The method according to any one of the preceding claims, characterized in that

the heat transfer from the first fluid (26) to the second fluid (27) is largely isothermal.

7. The method according to any one of the preceding claims, characterized in that

the useful heat of the second fluid (27) at a volumetric heat output (20) of the first fluid (26) and the second fluid (27) of at least 1000 kJ / m ^3, preferably from we ^¬ nigstens 1200 kJ / m ³ and more preferably of at least 1500 kJ / m ^{3 is} delivered.

8. Heat pump arrangement (1) with 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 by means of a heat exchanger (19) from the first fluid (26) to the second fluid (27) is transferable,

characterized in that

a useful heat can be transferred by means of the second fluid (27) at a fluid temperature (21) of at least 120 ° C., the first fluid (26) and the second fluid (27) having a volumetric heating capacity (20) of at least 500 kJ / m ³ .

9. Heat pump arrangement according to claim 8,

characterized in that

by means of at least two-stage compression at least one temperature stroke of the first fluid (26) and / or the second fluid (27) is steigerbar.

10. Heat pump arrangement according to one of claims 8 or 9, characterized in that

by means of a liquid ring compressor (24), the second fluid (27) is substantially isothermally compressible.