WO2013045361A1

WO2013045361A1 - High-temperature heat pump and method of using a working medium in a high-temperature heat pump

Info

Publication number: WO2013045361A1
Application number: PCT/EP2012/068645
Authority: WO
Inventors: Bernd Gromoll; Jochen SCHÄFER
Original assignee: Siemens Aktiengesellschaft
Priority date: 2011-09-30
Filing date: 2012-09-21
Publication date: 2013-04-04
Also published as: JP2014528053A; US20140245763A1; CA2850396A1; CN103827599A; DE102011086476A1; EP2742298A1; RU2014117522A

Abstract

The present invention relates to a high-temperature heat pump having a fluid circuit (1) for absorbing thermal energy through the fluid from at least a first reservoir (2) while performing technical work and for outputting thermal energy through the fluid to at least a second reservoir (3) for heating the at least one second reservoir (3). The present invention also relates to a method of using a working medium in a high-temperature heat pump of this kind, wherein the working medium is hydrofluoroether or fluoroketone.

Description

description

High temperature heat pump and method of using a working medium in a high temperature heat pump

The present invention relates to a high-temperature ^¬ turwärmepumpe with a fluid circuit for receiving thermal energy by the fluid from at least one ers ^¬ th reservoir under application of technical work and for the delivery of thermal energy by the fluid at at least a second reservoir for heating the at least one second reservoir. Furthermore, the present invention relates to a method of using a working medium in such a high-temperature heat pump.

A heat pump is a machine which, by applying technical work, absorbs thermal energy from a reservoir at a lower temperature and, together with the drive energy, transfers it as useful heat to a system with a higher temperature to be heated. The lower temperature reservoir may e.g. Be air from the environment or liquid and rock of the soil when using geothermal energy. However, among other things, waste heat sources in industrial processes can also be used.

Heat pumps can be used to heat buildings or extract heat for industrial processes. High-temperature heat pumps ^¬ lead to a useful heat to be heated system which be found ^¬ at a high temperature level. Under high temperature level or higher temperature, for example, temperatures above 70 ° C to understand. The temperatures that can be achieved with the help of heat pumps for heating depend essentially on the working medium used in the heat pump. The working medium is usually a fluid which is liquefied when compressed under pressure and gives off thermal energy. When expanded to a gas, the fluid cools and can absorb thermal energy from the first reservoir. In the cycle so can amount of heat be transmitted continuously or in pulses from a cooler reservoir by the application of mechanical energy to a warmer reservoir. The temperature reached by a heat pump during heating depends not only on the working fluid used but also on the pressure in the condenser, which is also referred to as condenser or condenser. In the condenser, the working fluid is liquefied by absorbing heat from the first, cooler reservoir. For high-temperature heat pumps, for example, carbon dioxide is used as the working medium. The boiling point of carbon dioxide at 1 bar is, for example at -57 ° C and the Verflüs ^¬ sigungstemperatur located at 26 bar, for example at -26 ° C. For environmental compatibility reasons, eg regarding "Global Warming Potential" and "Ozone Depletion Potential", carbon dioxide is an ideal working medium, but the critical temperature of carbon dioxide is only 31 ° C. Above the ^¬ ser temperature carbon dioxide can no longer be liquefied even by expending the highest pressures.

From this follow special features for the process control beyond the critical temperature. Thus, the heat release after compression does not take place at a certain temperature, as with condensing agents, but over a wide temperature range. Thereby, the usability of the heat e.g. difficult to generate steam. The use of carbon dioxide as a working substance in a heat pump is also due to the material properties associated with very high pressures and thus expensive in terms of apparatus.

Hydrocarbons such as butane or pentane are more suitable for providing heat at a high temperature level because of their physical properties. Butane has, for example, a boiling point at 1 bar of -12 ° C. and a liquefaction temperature at 26 bar of 114 ° C. However, their use is problematic because of their good flammability for safety ^¬ technical reasons. Object of the present invention is therefore to provide a high-temperature heat pump and a method for using a working medium in a high-temperature heat pump, which are suitable to provide heat at high temperatures such as higher 70 ° C, are environmentally friendly and simple, inexpensive and without high risk, for example by clotting ^¬ flammability can be operated.

The specified object is with respect to the high temperature heat pump with the features of claim 1 and with respect to the method for using a working medium in a high ^¬ temperature ^heat pump with the features of claim 7 ge ^¬ triggers.

Advantageous embodiments of the high temperature heat pump and method of the invention for the Ver ^¬ use of a working medium in a high temperature heat pump will be apparent from the respectively assigned dependent subclaims. The features of the independent and independent claims may be combined with the untereinan ^¬ with each other and features of the subclaims as well as features of the subclaims.

The high-temperature heat pump according to the invention comprises a fluid circuit for receiving thermal energy from a fluid from at least one first reservoir using technical work and for delivering thermal energy through the fluid to at least a second reservoir for heating the at least one second reservoir. According to the invention, the fluid circuit is filled with a hydrofluoroether or with fluoroketone as fluid or working medium. It is also possible to use mixtures of hydrofluoroether and fluoroketone.

Hydrofluoroether or fluoroketone are not flammable and therefore safe to use eg in processes with high temperature. Hydrofluoroethers or fluoroketones are environmentally friendly, as they do not contribute to global warming or to increase the Ozone hole is done by these classes. The known hydrofluoroethers or fluoroketones have higher critical temperatures than eg carbon dioxide. As a result, a large part of the amount of heat absorbed after compression at a temperature, especially the condensation temperature, can be released again. This facilitates, for example, the use of heat in the case of a process steam supply. With a working medium hydrofluoroether or fluoroketon high-temperature heat pump to achieve very high temperatures at lower pressures than, for example, in comparison with carbon dioxide as working ^¬ medium, trans-critical operation. Transcritical in this context means that compared to subcritical process control, in which the working fluid is liquefied at a constant temperature, in transcritical process control, the heat release occurs in the supercritical region, ie when the temperature changes.

The high-temperature heat pump according to the invention may comprise at least one evaporator, at least one compressor, at least one condenser and / or at least one throttle as part of the fluid circuit. The individual components are known in the art, e.g. from the

DE 10 2007 010 646 A1. Furthermore, also expansion valve ver ^¬ turns can be used for the compressor as a synonym and compressor, for condenser and condenser or condensers, and for the reactor, depending on the particular function of the component. The fluid flowing in the fluid circuit fluid is compressed in the Kom ^¬ pressor cooled in the condenser, giving off heat to the second reservoir from flows depending on the opening of the throttle with a given speed and pressure reduction through the throttle into the evaporator where it is expanded and heat quantity deprives the first reservoir.

As a compressor, a multi-stage compressor can be used, in particular a two-stage compressor. Through a multi-stage compression increases the coefficient of performance of the high-temperature heat exchanger. An economizer may be part of the fluid circuit. An Econo miser is an additional intermediate heat exchanger in the fluid circuit. It transfers part of the heat which is present after the heat release to the second reservoir in the liquid working medium to the gaseously superheated working medium in front of the compressor. As a result, for example, a strong overheating of the Ar beitsmediums be achieved as a suction gas, whereby a Ver ^¬ seal in the wet steam region of the working medium ^{sicherge ¬} can be made. The economizer leads to an increase in the efficiency or the effectiveness of the high temperature ^¬ heat exchanger.

The fluid circuit may be closed or completed. Especially with regard to avoiding losses of working fluid, a closed fluid circuit can be selected.

The hydrofluoroether may be a hydrofluoroether having the chemical formula C _x F _y -O-C _m H _n , where x is 3, y is 7, 1 and n is 3, or x is 4, Y is 9, m is 1 and n is 3, or x is 4, Y is 9, m is 2 and n is 5, or x is 6, Y is 13,] is 1 and n is 3. The hydrofluoroether may also be a hydrofluoroether having the chemical formula 1

C ₃ F ₇ CF (OC ₂ H ₅₎ CF (CF ₃₎ 2 to be. Furthermore, the hydrofluoroether may be a hydrofluoroether having the chemical formula

CH3CHO (CF2CFHCF3) 2. It is also possible to use as fluid a fluoroketone having the chemical formula CF ₃ CF ₂ C (O) CF (CF ₃ ) ₂ . It is also possible to use other hydrofluoroethers or fluoroketones having good thermal properties as working medium in the high-temperature heat exchanger according to the invention, as well as mixtures of different hydrofluoroethers or fluoroketones.

The inventive method for using a working ^¬ medium in a high-temperature heat pump, in particular in a high-temperature heat pump described above, comprises that the working fluid when flowing in a fluid circuit thermal energy from at least a first reservoir un ^¬ ter expenditure of technical work and receives thermal energy to a second reservoir for heating emits at least the at least one second reservoir. In this case, hydrofluoroether or fluoroketone is used as the working medium.

The thermal energy can be delivered to the at least one second reservoir after the compression of the working medium at or in the region of the condensation temperature of the working medium. The thermal energy can be used for process steam ^¬ ready position.

The at least one second reservoir, to which the thermi ^¬ specific energy is emitted, a temperature of greater than 70 ° C may have. The high temperature heat pump can be operated transcritical be to Errei ^¬ chen high temperatures at low pressure. The compression of the working medium can be done more stages, in particular two stages.

The gaseous working medium can be greatly overheated, since each with the compression in front of a wet steam area of the high-temperature heat exchanger is completely completed. The overheating can be carried out by an economizer, in particular with a heat transfer of heat at the end of a high-pressure heat exchanger or the condenser to the ^{output of} the working medium on the evaporator.

The advantages associated with the method of using a working fluid in a high temperature heat pump are analogous to the advantages previously described with respect to the high temperature turwärmepumpe.

Preferred embodiments of the invention with advantageous developments according to the features of the dependent claims are explained in more detail with reference to the figures, but without being limited thereto. It is shown in the figures:

1 is a schematic representation of an inventive ^¬ Shen high-temperature heat pump, and

Fig. 2 is a schematic representation of a high-temperature heat pump according to Fig. 1 with additional multi-stage compression and economizer. In Fig. 1 is a schematic representation of an exporting ^¬ approximately example of a high-temperature heat ^¬ pump according to the invention is shown. The high temperature heat pump comprises a fluid circuit 1, in which a hydrofluoroether or fluoro ketone flows as a working medium. The hydrofluoroether or the fluoroketone is a fluid which may be liquid or gaseous. The hydrofluoroethers include substances having the chemical formula C _x F _y -O-C _m H _n , where x is 3, y is 7, m is 1 and n is 3, or x is 4, y is 9, m is equal to 1 and n is 3, or x is 4, y is 9, m is 2 and n is 5, or x is 6, y is 13, m is 1 and n is 3, or substances with the chemical formula C ₃ F ₇ CF (OC ₂ H ₅ ) CF (CF ₃ ) ₂ ,

CH ₃ CHO (CF2CFHCF ₃ ) 2, or as fluoroketone is a substance with the chemical formula CF3CF2C (0) CF (CF3) 2 in question. Other hydrofluoroethers or fluoroketones with suitable physical properties can be used to provide heat at a high temperature level.

A first reservoir 2 is in thermal contact with an evaporator 4. A second reservoir 3 is in thermal contact with a condenser 6 for the working medium. The first reservoir 2 has a temperature ΤΊ on which is able to dress ^¬ ner than the temperature T2 of the second reservoir 3. In a high-temperature heat exchanger, the temperature T2 GroE SSER may be 70 ° C.

In the evaporator 4 takes on an expansion of the working medium, the working fluid heat, which the first reservoir. 2 is withdrawn. A gaseous working medium is sucked from the evaporator 4 by a compressor 5 and compressed. As a result, the pressure of the working medium increases from a value pi to a value p ₂ . The working medium with the increased pressure p ₂ from the compressor 5 flows into a condenser 6, where it is liquefied with the release of heat to the second reservoir 3. Characterized by the first heat quantity Re ^¬ servoir 2 having a lower temperature ΤΊ is pumped to the second reservoir 3 with the higher temperature T _2, with the expenditure of work by the compressor 5, and transported. The first reservoir 2 serves as a heat source and heat is supplied to the second reservoir 3 via the condenser 6 as a heater.

The working medium from the condenser 6 can flow back into the evaporator 4 at high pressure p ₂ via a throttle valve 7 at a pressure pi. Thus, the fluid circuit 1 is closed. When using fluid-tight devices 4, 5, 6, 7 and compounds such as pipes and seals, the fluid circuit for the working fluid can be completed, so that no working fluid is released to the environment or is lost. The compressor 5 in the form of a compressor increases the pressure of the working medium from pi to p ₂ and via the throttle 7 in the form of an expansion valve, the pressure of p _{2 is} reduced to pi. Thus, the fluid circuit can be classified into a low-pressure cold side pi, ie, a low-pressure side, and a high-pressure hot side p ₂ , that is, a high-pressure side. The low-pressure side comprises the Ver ^¬ evaporator 4 and the high pressure side comprising the capacitor. 6

As shown in FIG. 2, with the aid of an economizer 8, the efficiency of the high-temperature heat exchanger, ie the ratio of pumped heat quantity to work done for pumping, eg in the form of mechanical work of the compressor 5, can be improved. The economizer 8 may be designed as a heat exchanger, which receives heat quantity from the liquid working medium at the outlet of the condenser 6 and to the gaseous working medium at the outlet of the evaporator 4 emits. As a result, an overheating of the gaseous working medium can be achieved, whereby a compression in the wet steam region of the condenser 6 can be ensured.

An increase in the coefficient of performance, the ratio of recovered useful heat to the drive energy used, the Hochtem ^¬ peraturwärmetauschers is possible by using a multi-stage instead of a single-stage compression of the working medium.

The use of hydrofluoroether or fluoroketone as a working medium or fluid in the inventive high temperature heat exchanger and process a safe, environmentally friendly and effective pumping of heat from the first re ^¬ servoir 2 with low temperature ΤΊ is possible in the second reservoir 3 with a high temperature T ₂ ,

Hydrofluoroethers and fluoroketones are non-flammable and therefore safe to use, eg in processes with high temperature and during compression. Hydrofluoroethers and fluoroketone are environmentally friendly, as no contribution to global warming or to increase the ozone hole by this class he ^¬ follows. The known hydrofluoroethers and fluoroketones have higher critical temperatures than, for example, carbon dioxide, as a result of which a large part of the heat absorbed can be released again after compression. With hydrofluoroether and / or fluoroketone, high-temperature heat pumps can be operated transcritically to achieve very high temperatures, as a result of which only moderate pressures are necessary, for example less than when using carbon dioxide. Thus, using hydrofluoroether and / or fluoroketone have fiction, modern ^¬ high temperature heat exchanger, and methods to a number of advantages over the prior art where, typical working media butane, pentane or carbon dioxide. The embodiments described above can be combined with each other and with embodiments of the prior art.

Claims

claims

A high-temperature heat pump with a fluid circuit (1) for receiving thermal energy from a fluid from at least one first reservoir (2) by using technical work and for delivering thermal energy through the fluid to at least a second reservoir (3) for heating the at least one second reservoir (3), characterized in that the fluid circuit (1) is filled with the fluid hydrofluoroether or fluoroketone as the working medium.

2. High-temperature heat pump according to one of the preceding claims, characterized in that at least one evaporator (4), at least one compressor (5), at least one condenser (6) and / or at least one throttle (7) is part of the fluid circuit (1). are.

3. High-temperature heat pump according to one of the preceding arrival claims, characterized in that a multi-stage Ver ^{¬ poet} (5), in particular a two-stage compressor (5) is part of the fluid circuit (1).

4. High-temperature heat pump according to one of the preceding arrival claims, characterized in that an economiser (8) is part of the fluid circuit (1).

5. High temperature heat pump according to one of the preceding claims, characterized in that the fluid circuit (1) is closed or completed.

6. High temperature heat pump according to one of the preceding claims, characterized in that the hydrofluoroether is a hydrofluoroether having the chemical formula C _x F _y -0-C _m H _n , where x is equal to 3, y is equal to 7, m is equal to 1 and n is equal to 3, or x equals 4, y equals 9, m equals 1, and n equals 3, or x equals 4, y equals 9, m equals 2, and n equals 5, or x equals 6, y equals 13, m is equal to 1 and n is equal to 3, or that the hydrofluoroether is a hydrofluoroether with the chemical formula C ₃ F ₇ CF (OC ₂ H ₅ ) CF (CF ₃ ) 2, or that the hydrofluoroether is a hydrofluoroether with the chemical formula CH 3 CHO (CF 2 CFFCF 3) 2 or the fluoroketone is a Fluorke ^¬ ton with the chemical formula CF ₃ CF ₂ C (0) CF (CF _3). ₂

7. A method for using a working medium in a high-temperature ^{heat pump} , in particular according to one of the preceding ^¬ claims, wherein the working fluid when flowing in a fluid circuit (1) receives thermal energy from at least a first reservoir (2) by using technical work and thermal energy write at least a second reservoir (3) for heating the at least one second reservoir (3), characterized in that is used as the Ar ^¬ beitsmedium hydrofluoroether or fluoroketone.

8. The method according to claim 7, characterized in that the thermal energy to the at least one second Reser ^¬ voir (3) is discharged after the compression of the working medium, at or in the region of the condensation temperature of the working medium, and / or that the thermal energy for a process steam supply is used.

9. The method according to any one of claims 7 or 8, characterized in that the thermal energy to the at least one second reservoir (3), which has a temperature of greater than 70 ° C, is discharged.

10. The method according to any one of claims 7 to 9, characterized in that the high temperature heat pump is operated to achieve high temperatures at low pressure transcritical.

11. The method according to any one of claims 7 to 10, characterized in that a compression of the working medium more ^¬ stage, in particular two stages takes place.

12. The method according to any one of claims 7 to 11, characterized in that the gaseous working fluid is strongly over ^¬ heated, so that each of the compression in front of a wet ^¬ steaming the high-temperature heat exchanger is completely completed.

13. The method according to claim 12, characterized in that the overheating by an economizer (8), in particular with a heat transfer of heat at the end of a high-pressure heat transfer to the output of the working medium at the evaporator (4).