KR20160018795A - Method for operating a heat pump arrangement, and heat pump arrangement - Google Patents

Abstract

The present invention relates to a method for operating a heat pump arrangement 1 wherein a first fluid 26 flows through a first heat pump 2 and a second fluid 27 Flows through the second heat pump 3 and heat is transferred from the first fluid 26 to the second fluid 27 by the heat exchanger 19. Useful heat is extracted from the second fluid 27 at a fluid temperature 21 of at least 120 DEG C and the useful heat of the second fluid 27 is at least 500 kJ / 26). ≪ / RTI > The invention also relates to such a heat pump arrangement (1).

Description

METHOD FOR OPERATING A HEAT PUMP ARRANGEMENT, AND HEAT PUMP ARRANGEMENT,

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

Such heat pump arrangements are used, for example, to provide industrial heat. The heat pump utilizes the technical work to absorb the thermal energy from the heat source in the form of lower temperature heat and with the drive energy of the compression machine to convert the heat energy to a higher temperature It is a machine that emits heat to the heat sink as waste heat. For temporary storage or to deliver heat, fluids are used, such fluids being delivered in a heat pump, through a cycle process by a compression machine. This recycling 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), useful heat from currently commercially available heat pumps is limited to temperatures of at most 100 ° C only.

It is therefore an object of the present invention to provide a heat pump arrangement and method that can provide useful heat, especially at high temperatures.

This object is achieved by a method having the features of claim 1 and by a heat pump arrangement having the features of claim 8. Advantageous configurations with the additional advantageous further embodiments of the invention are given in the patent dependent claims.

According to the present invention there is provided useful heat extracted from a second fluid at a fluid temperature of at least 120 ° C, in order to provide a method of the above-described type which can provide useful heat, especially at high temperatures, The useful heat of the two fluids is discharged at a volumetric heating capacity of the second fluid and the first fluid of at least 500 kJ / m 3. Volumetric heating capacity (VHC) is very important for the theoretically achievable coefficient of performance (COP) of heat pumps. That is, the higher the VHC, the more efficient the heat pump operates. Therefore, the higher the volumetric heating capacity than the above-mentioned 500 kJ / m < 3 >, the higher the coefficient of performance (COP) of each heat pump is also higher. By means of the second heat pump, particularly high fluid temperatures can be achieved. As a result, useful heat, especially at high temperatures, can be extracted from the second fluid, depending on the heat carried by the first fluid.

It has proved advantageous to extract useful heat from the second fluid at a fluid temperature of at least 150 캜, and particularly preferably at least 160 캜. By means of the second heat pump, particularly high fluid temperatures can be achieved. As a result, useful heat can be extracted from the second fluid, especially at high temperatures, thereby providing useful heat, for example, even more effectively for industrial use.

In an advantageous configuration of the present invention, at least one fluoroketone flows as a first fluid through the first heat pump. Fluoroketones are particularly safe for use in industry because there is no need to take special protective measures at the time of an accident. Since the use of fluoroketones is not governed by environmental requirements, the use of fluoroketones is particularly future-proof. In addition, fluoroketones have a particularly low global warming potential, are non-flammable and non-toxic. For this reason, fluoroketones can be used as fluids in heat pump arrangements, especially when useful heat is provided using industrial heat of the process, especially above 120 < 0 & Are particularly suitable for the following.

In a further advantageous embodiment of the invention, water or at least one fluoroketone is used as the second fluid. Because both water and fluoro ketones are environmentally friendly and unsubstantial from a safety point of view, both water and fluoro ketones are used in applications where high fluid temperatures occur, taking into account that they are neither flammable nor toxic Especially as fluids in applications.

It is particularly advantageous that different fluids are used as the first fluid and the second fluid. The coefficient of performance (COP) of each heat pump depends on each temperature rise. The temperature rise of the heat pump is understood to mean the temperature difference that can be achieved between the respective condenser of the heat pump and the respective evaporator of the heat pump. Due to the achievable temperature rise of the first heat pump, therefore, waste heat of particularly high temperature can be provided and can be transferred by the heat exchanger to the second fluid of the second heat pump. Thus, the maximum temperature of the second fluid that can be reached using the second heat pump is directly dependent on the amount of heat delivered by the first fluid. Using particularly large temperature rises of each heat pump, particularly high performance factors can be achieved, and it is advantageous here that the use of different composition fluids in each case for the first fluid and the second fluid is advantageous, As will be described below. For example, the use of the fluoroketone NOVEC 524 is particularly recommended when fluid temperatures of only 140 ° C are achieved using a first heat pump. The fluoroketone NOVEC 524 has a particularly high volumetric heating capacity (VHC) in the range of 100 < 0 > C to 140 < 0 > C. However, since NOVEC 524 only fits up to the stated maximum fluid temperature of 140 ° C, for example, to achieve a temperature rise from 140 ° C to 200 ° C using a second heat pump, Is recommended because water is also suitable for fluid temperatures above < RTI ID = 0.0 > 140 C. < / RTI >

It is particularly advantageous that the heat release from the first fluid to the second fluid proceed substantially isothermally. Through isothermal heat release, the temperature of the heat of the emitted quantity is kept particularly constant, whereby temperature variations are particularly excluded in general, and therefore also a substantially constant temperature rise can be achieved using a second heat pump have. In order to achieve isothermal heat release using a heat exchanger, the first fluid must be operated sub-critically, i.e., the first fluid can only be used below the critical temperature of the first fluid . That is, therefore, the first fluid must be operated at a temperature at which both the liquid physical state and the gaseous physical state can exist.

In a further advantageous arrangement of the invention, the useful heat is discharged with a volumetric heating capacity of at least 1000 kJ / m 3, preferably at least 1200 kJ / m 3 and particularly preferably at least 1500 kJ / m 3 of the second fluid. Theoretically achievable coefficient of performance (COP) depends on the design of the compression device for compressing each fluid of each heat pump, but the fluid in the heat pump arrangement is at a point where there is a volumetric heating capacity of at least 1000 kJ / . As the volume heating capacity is higher than the above-mentioned 1000 kJ / m 3, the coefficient of performance (COP) of each heat pump is also larger. If at least 1000 kJ / m < 3 > is required for the volume heating capacity of each fluid, for example, at a temperature below 150 DEG C water can not be sensibly used as a fluid. The performance coefficient (COP) of each heat pump is particularly large when there is a volumetric heating capacity of at least 1500 kJ / m < 3 > for each fluid.

Wherein at least one first heat pump-first fluid flows through the first heat pump-and a second heat pump-a second fluid flows through the second heat pump- In the pump arrangement, heat can be transferred from the first fluid to the second fluid using a heat exchanger.

In this case, useful heat can be delivered using a 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 / m 3. The higher the capacity heating capacity, the higher the coefficient of performance (COP) achievable for each heat pump. In this case, useful heat, especially at high temperatures, may be extracted from the second fluid, depending on the heat carried by the first fluid. The heat pump arrangement, in which the second heat pump can provide useful heat, especially at high temperatures, is also known as a heat pump cascade. The heat pump arrangement, also known as a heat pump cascade, The maximum high volume heating capacity of the fluid is advantageous, where the amount of heat transferred from the first fluid to the second fluid is advantageously delivered at a particularly high temperature.

The advantages described above in connection with 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 arrangement of the heat pump arrangement, the at least one temperature rise resulting from the relatively high pressure ratio of the first fluid and / or the second fluid can be increased by at least two-stage compression. Two- or multi-stage compression is recommended, especially when large temperature increases are achieved using fluids from heat pumps. In this case, intermediate cooling may be fitted between compression devices effecting each compression step. This is particularly useful when water is used as a fluid. The heat of intermediate cooling can be supplied to the evaporator of each heat pump, in particular in an energy-efficient manner. In addition, cascades of more than two heat pump circuits are also possible to achieve very high temperature rises.

In a further advantageous configuration of the heat pump arrangement, it has been demonstrated that using a liquid ring compressor, the second fluid is substantially isothermally compressible. The compression of the fluid can proceed substantially isothermally using a liquid ring compressor. Then, the liquid ring of the liquid ring compressor is in direct contact with the fluid to be compressed, whereby the heat of compression can be transmitted particularly effectively to the liquid ring formed from the ring liquid-ring liquid from the fluid. That is, the fluid and ring liquid are not separated from each other by the wall, and therefore the heat transfer resistance is particularly low.

Additional advantages, features, and details of the present invention will become apparent from the claims, by way of the following description of the preferred embodiments, and by reference to the drawings.
1 is a schematic view of a heat pump cascade according to the prior art, in which case the heat pump cascade corresponds to a heat pump arrangement with two heat pump circuits;
2 is a schematic view of the respective curves of the volume heating capacities of the various fluids of the heat pump arrangement drawn against temperature; And
Figure 3 is a schematic diagram of a heat pump cascade corresponding to a heat pump arrangement with two heat pump circuits-one of the heat pump circuits operating with fluoro ketone as fluid.

1 is a schematic diagram of a heat pump arrangement, known in the prior art, known as a cascade heat pump 1, comprising two heat pump circuits. The cascade heat pump (1) is characterized in that the first heat pump (2) - the first fluid flows through the first heat pump and the second heat pump (3) - the second fluid flows through the second heat pump . The first and second fluids are coupled to each other for heat transfer by the heat exchanger (19). In this case, the heat exchanger 19 includes the condenser 6 of the first heat pump 2 and the evaporator 8 of the second heat pump 3. The first fluid of the first heat pump 2 is evaporated by the evaporator 4, where heat energy is supplied to the evaporator 4 by the heat source 12. The first fluid heated by the evaporator 4 is transferred by the first heat pump 2 in the direction of the arrow 14 by the compressor 5 of the first heat pump 2. The heated and compressed first fluid of the condenser 6 then releases heat to the evaporator 8 where the second fluid of the second heat pump 3 is evaporated by the evaporator 8. Following the release of this heat, the first fluid is expanded by the expansion valve 7 of the first heat pump 2 and then again absorbs the heat through the evaporator 4. Therefore, the circuit of the first heat pump 2 is closed. A second heat pump 14 which is heated by the heat exchanger 19, that is to say by the discharge of heat to the evaporator 8 of the second heat pump 3 by the condenser 6 of the first heat pump 2, The second fluid of the second heat pump 3 is compressed by the compressor 9 of the second heat pump 3 and discharges the heat to the heat sink 13 in the condenser 10 of the second heat pump 3. The second fluid then flows through the expansion valve 11 of the second heat pump 3 in the direction of the arrow 15 and expands at the expansion valve. Thereafter, the second fluid again absorbs heat by the heat exchanger 19, and thus the circuit of the second heat pump 3 is closed.

2 is a schematic diagram of different curves of volumetric heating capacities, where the y axis of the figure represents the volumetric heating capacity 20 and the x axis represents the fluid temperature 21 corresponding to the condensation temperature of the fluid. This figure shows that the heating capacity curve 16 corresponding to the heating capacity curve of the fluoroketone known as NOVEC 524 is equal to the heating capacity curve 17 corresponding to the heating capacity curve of the fluoroketone known as NOVEC 649, And higher values in each case for temperatures 21. As is apparent from the figure, both the heating capacity curve 16 and the heating capacity curve 17 do not extend 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 of 148 占 폚, and the heating capacity curve 17 of the fluoroketone NOVEC 649 has a critical point of, for example, 169 占 폚 (29). However, as is apparent from the figures, the heating capacity curve 18, corresponding to the heating capacity curve of water, has the lowest volume heating in each case for the same fluid temperatures 21 as compared to the two fluoro ketones Water may be used over a particularly wide range of fluid temperatures 21, with the capacity 20 and without reaching the critical point of water. 2, the heating capacity curve 18 of the water at fluid temperatures below the critical point 28 and the critical point 29 is shown below the heating capacity curve 16 and the heating capacity curve 17, respectively, But at high fluid temperatures 21 the heating capacity curve 18 of the water is directed to the heating capacity curve 16 and the heating capacity curve 17 as a result of reaching each of the critical points 28 and 29, Lt; RTI ID = 0.0 > values, < / RTI > In addition, when the fluoroketone NOVEC 649 is used as the first fluid of the first heat pump 2, a large amount of heat with an operating temperature of at least 160 캜 is introduced into the heat sink 13 by the cascade heat pump 1, Lt; / RTI > Because the second fluid of the second heat pump 3 is additionally heated based on the amount of heat transferred by the heat exchanger 19 from this first fluid to the second fluid at a temperature of up to 160 ° C, A useful heat temperature higher than < RTI ID = 0.0 > 1 C < / RTI > can be reached by the second heat pump 3.

For the fluid for the first heat pump 2 of the cascade heat pump 1, the heat release from the first fluid to the second fluid must be conducted only by the heat exchanger 19, Are only options. The first fluid of the first heat pump 2 is operated at a fluid temperature 21 that is less than the critical temperature of each critical point 28 or 29 to permit isothermal heat release. The higher the volumetric heating capacity 20 of the fluid in one of the heat pumps 2, 3, the more efficiently each heat pump 2, 3 operates. Thus, with each higher volumetric heating capacity 20, the coefficient of performance of the isothermally achievable heat pump also increases.

2 and 3, it is particularly advantageous, for example, that the fluoroketone 26, such as NOVEC 524, is used as the first fluid of the first heat pump 2. In this regard, in order to permit isothermal heat release of the second heat pump 3 to the second fluid by the heat exchanger 19, the fluid temperature 21 - fluoro ketone 26 is supplied to the fluid temperature 21 ) Remains below the fundamental critical temperature of the critical point 28. The critical point temperature of the critical point 28, For example, as the second fluid of the second heat pump 3, water 27 is used.

The cascade heat pump 1 illustrated in the schematic of FIG. 3 includes substantially the components already described in FIG. 1, and for that reason only the differences will be described below.

The heat exchanger 19 according to Fig. 3 is provided with a high-temperature condenser 22 of the first heat pump 2 and a high-temperature evaporator 23 of the second heat pump 3, instead of the condenser 6 and the evaporator 8, . 3, a liquid ring compressor 24 is used instead of the compressor 9 to deliver the water 27. In this case, The liquid ring compressor 24 is now compressed and supplied to the hot condenser 25 as previously evaporated water 27 as a result of the input of heat by the high temperature evaporator.

Does not exceed the critical temperature of the critical point 28 due to the particularly high volumetric heating capacity exceeding 3000 kJ / m3 of the fluoroketone 26 and thus significantly exceeding 1500 kJ / m3. A large amount of heat is transferred to the high temperature evaporator 23 of the second heat pump 3 by the high temperature condenser 22 of the first heat pump 2 at the fluid temperature 21 of 140 ° C of the second heat pump 3. Thus, a large amount of heat, especially at high temperatures, can be released to the water 27 by the high temperature evaporator 23, whereupon a large amount of useful heat, in particular at high temperatures, is removed by the hot condenser 25 , And can be discharged to the heat sink (13). The water 27 carried as a fluid in the second heat pump 3 is heated by the amount of heat of 140 占 폚 transferred from the fluoro ketone 26 to the water 27 by the heat exchanger 19, , It is heated to a temperature of 200 DEG C, which corresponds to an increase in the temperature of 60 DEG C of the water 27. [ At 200 占 폚, the calorific value 20 of water 27 exceeds the value significantly higher than 4000 kJ / m3, that is, 1500 kJ / m3.

Claims (10)

1. A method for operating a heat pump arrangement (1)
In the heat pump arrangement, a first fluid 26 flows through the first heat pump 2, a second fluid 27 flows through the second heat pump 3, and the heat exchanger 19 Heat is transferred from the first fluid 26 to the second fluid 27,
Useful heat is extracted 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 such that the heat of the second fluid 27 of at least 500 kJ / And is discharged into the volumetric heating capacity (20) of the first fluid (26).
A method for operating a heat pump arrangement.
The method according to claim 1,
Characterized in that said useful heat is extracted from said second fluid (27) at a fluid temperature (21), preferably at least 150 ° C and very particularly preferably at least 160 ° C.
A method for operating a heat pump arrangement.
3. The method according to claim 1 or 2,
Characterized in that at least one fluoroketone flows through said first heat pump (2) as said first fluid (26).
A method for operating a heat pump arrangement.
4. The method according to any one of claims 1 to 3,
Characterized in that water or at least one fluoroketone is used as said second fluid (27)
A method for operating a heat pump arrangement.
5. The method according to any one of claims 1 to 4,
Characterized in that different fluids are used as the first fluid (26) and the second fluid (27)
A method for operating a heat pump arrangement.
6. The method according to any one of claims 1 to 5,
Characterized in that heat dissipation from the first fluid (26) to the second fluid (27) proceeds substantially isothermally.
A method for operating a heat pump arrangement.
7. The method according to any one of claims 1 to 6,
The useful heat of the second fluid 27 is the heat of the second fluid 27 and the first fluid 26 of at least 1000 kJ / m 3, preferably at least 1200 kJ / m 3 and particularly preferably at least 1500 kJ / Is discharged to a volume heating capacity (20)
A method for operating a heat pump arrangement.
As a heat pump arrangement (1)
At least one first heat pump (2) - a first fluid (26) flows through the first heat pump (2) and a second heat pump (3) - a second fluid (27) Heat pump 3 and heat can 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 and the first fluid 26 and the second fluid 27 may be delivered at a rate of at least 500 kJ / Characterized in that it has a volumetric heating capacity (20)
Heat pump arrangement.
9. The method of claim 8,
Characterized in that the temperature rise of at least one of the first fluid (26) and / or the second fluid (27) can be increased by at least two-
Heat pump arrangement.
10. The method according to claim 8 or 9,
Characterized in that said second fluid (27) is substantially isothermally compressible using a liquid ring compressor (24).
Heat pump arrangement.

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