WO2007107593A2

WO2007107593A2 - Heat pump device

Info

Publication number: WO2007107593A2
Application number: PCT/EP2007/052710
Authority: WO
Inventors: Michael Löffler
Original assignee: Loeffler Michael
Priority date: 2006-03-21
Filing date: 2007-03-21
Publication date: 2007-09-27
Also published as: WO2007107593A3; EP2016346A2; DE102006012852A1; WO2007107593B1

Abstract

The invention relates to a heat pump device comprising a cyclone unit (30) and a piston engine (10) with a cylinder compartment (15). A liquid working medium is injected into the cyclone unit (30) while a gas working medium is compressed in the piston engine or while a gas working medium is expanded in the piston engine.

Description

heat pump device

The present invention relates to a heat pump device.

Currently available heat pumps (WPn) with a compressor work with a phase change, the working fluid absorbs heat during evaporation and gives off heat during condensation. Depending on the operating point, heat is absorbed by the environment and released at a high temperature level (heat pump as a heat engine, for example, for space heating and / or domestic water heating) or heat to the environment and recorded at a low temperature level (heat pumps as a chiller).

After the heat absorption in the evaporator in both cases mentioned an increase in pressure of the working medium in a mostly electrically operated pump is required. Heat pumps work in most cases after the cold vapor process. The number of work of heat pumps for domestic water heating and space heating are about 2-3. Depending on the temperature level of the hot side and the cold side and in the area of domestic water heating and room heating, the theoretical values for the working numbers are about 6.

It is therefore an object of the present invention to provide a heat pump device with improved numbers of jobs.

This object is achieved by a heat pump device according to claim 1.

Thus, a heat pump device with a cyclone unit and a piston machine with a cylinder space is provided. Here, a liquid working fluid is injected into the cyclone unit, while vaporous working fluid is compressed by the piston engine or relaxed during vaporous working fluid in the piston engine.

According to one aspect of the present invention, the injected liquid working medium moves in a circular manner in the cyclone unit. The liquid working medium is thus kept in the cyclone unit, while vaporous working medium from the cylinder chamber can penetrate into the cyclone unit or escape from the cyclone unit into the cylinder chamber.

The invention relates to the idea that maximum theoretically achievable operating numbers for heating or cooling of a medium are not achieved with the cold vapor process, but with a substantially triangular in the T-s diagram cycle.

Further embodiments of the invention are the subject of the dependent claims.

Advantages and embodiments of the invention are explained below with reference to the drawing. 1 shows a representation of a Ts diagram,

2 shows a schematic representation of different heat pump types,

Fig. 3 shows a schematic structure of a heat pump according to a first embodiment

4 shows a schematic representation of a construction of a cyclone unit of a heat pump according to a first exemplary embodiment,

Fig. 5 shows a sectional view through a cyclone according to a second embodiment, and

6 shows an illustration of a T-s diagram according to a third exemplary embodiment.

Fig. 1 shows a Ts diagram of a triangular heat pump cycle. Here, the ideal process flows for a heat pump for the delivery of useful heat with the ideal cold vapor process (line 1-2-3-4-5-6-1) and the triangular process (dashed, 1 -2-6-1) are shown. In order to clarify the principles of operation and to compare the processes in principle, the presentation of the ideal processes is sufficient here. Clearly visible is the exergy loss in the processes. Exergy is the proportion of the total energy of a system which can perform work when brought into thermodynamic equilibrium with its environment. In the cold vapor process, this exergy loss corresponds approximately to the area between the curves of the heat sink, dotted, 6-2, sensible heat, and the corresponding curve of the cold vapor process 2-3-4-5-6. On the other hand, the exergy loss in the triangular process corresponds to the area between the curves of the heat sink 6-2 and the curve of the triangular process 2-6. With ideal behavior of the countercurrent heat exchanger, which transfers the energy between the working medium and the heat carrier of the heat sink during the triangular process, and with the same thermal capacity flow of the two media, the exergy loss disappears altogether. - A -

In order to provide a triangular cycle, the cycle to be achieved is located in or directly at the wet steam zone of the working medium. The triangular process consists of a horizontal sub-process (the catheter 1: isothermal evaporation or condensation), a vertical sub-process (the catheter 2), (ideally a reversible adiabatic, ie isentropic evaporation or condensation) and a heat exchange process with the medium to be cooled or heated , the hypotenuse in the triangle. The latter sub-process, which appears as a hypotenuse, is in a first approximation a straight line. Considered more thermodynamically, the hypotenuse is an exponential function in assuming constant heat capacities and densities of the working medium as well as the medium which absorbs the heat. It turns out that the heat exchange process is usually carried out between two liquid media. Since very good countercurrent heat exchangers are available for liquid media, this sub-process can be expected to have an extremely low exergy loss.

The area of the cycle in the T-s diagram is a measure of the mechanical power that must flow into the heat pump. Since the area of the triangle is about half the area of the cold vapor process, the triangular process achieves twice the number of working hours compared to the cold vapor process.

Fig. 2 shows a schematic representation of four different types of heat pumps. 1) The first heat engine 1 with

T _Um g, 2) the second chiller 2 with T _Nutz <T _Um g, 3) heat from cold 3 with T _Nutz > T _Um g and 4) cold from heat 4 with T _Nutz <T _Um g Q _nutz refers to the Net power, Q _from the power delivered and ö _z "the power supplied to the machine. The machines 3 and 4 are heat mirrors and come with appropriate dimensioning and design of the temperatures without the supply of mechanical energy. Q are heat outputs that are introduced into the machine or removed from the machine depending on the direction of the arrow. W _meCh is the mechanical power supplied. T _Nutz are the temperature levels of useful power taken from the machine or into the machine be delivered. Depending on the type of machine, this temperature is higher or lower than the level of the ambient temperature T _To g ■ T _ab and T _to are temperature levels at which power must be dissipated from the machine or fed to the machine.

As an example of a heat mirror of the type 4) cold heat is a system in which the heat supplied from a solar collector comes (T _to = 60 ° C) and the level of ambient temperature at 30 ° C. With the machine type: Temperature mirror cold from heat, the machine can deliver cooling capacity at a temperature level of around 5 ° C. The amount of cooling capacity is about as large as the heat supplied to the machine from the collector. The dissipated to the environment heat output consists of the sum of the amount of cooling capacity and the collector heat output, that is about twice as large as the collector heat output.

Fig. 3 shows a schematic representation of a structure of a heat pump as a heater with cyclone, inlet valve V, piston, piston rod and crankshaft with motor. Exhaust valves are not shown. The heat pump device has a piston engine 10, an evaporator 20, a cyclone unit 30, an expansion valve 40, at least two non-return valves 50, a reservoir 60, a collecting container 70, an outlet valve 80 and a heat exchanger 90, via which heat can be delivered , During the compression of the vaporous working medium by means of the piston engine 10, a working medium in a liquid phase is introduced into the cyclone unit 30. The compressed vapor condenses into the liquid working medium in the cyclone unit 30. Thus, a liquid phase is injected during the compression process. The cyclone unit 30 serves to receive the liquid phase and to prevent liquid phase from being injected into the cylinder space. The liquid phase is injected on a circular path in the cyclone and thus remains in the cyclone. In contrast, the vaporous phase in the cylinder space is compressed and condenses with increasing pressure into the liquid phase, thereby heating the liquid phase. The volume of the cyclone unit 30 not occupied by the liquid phase interacts with the cylinder volume 15 of the piston engine. Thus, the cylinder volume extends into the cyclone unit 30, as it were. In other words, the volume of the cyclone unit and the volume of the cylinder space 15 form an intersection.

At the given temperatures, the heat pump achieves a theoretical working value of approx. 11. The useful thermal power P _nu t _z is preferably taken off via a countercurrent heat exchanger. In the evaporator, for example, water is at a temperature of 20 ° C at a pressure of 23mbar. In the reservoir water is at 20 ° C and a pressure of 1 bar. In the collecting container is water with, for example, 80 ° C at 0.5 bar pressure. P _ab is heat supplied from the environment in this case. The figures 10% and 90% mean that the mass flows of the working medium at this branch, for example, in the ratio 10 to 90 split. The piston machine shown in Fig. 3 has a first piston position, ie a top dead center OT, which is defined by the fact that the volume contained in the cylinder is minimal. The piston engine has a second piston position (bottom dead center UT), which is defined by the fact that the volume contained in the cylinder is maximum.

Fig. 4 shows a schematic structure of the pre-chamber with a cyclone unit according to a first embodiment. Here, by way of example, the construction of an antechamber for a heat pump according to the invention with indicated tangential injection of the heat transfer medium or the working medium through the inlet valve at for example 1 bar and 20 ° C and an outlet through the outlet valve at 0.5bar and 80 ° C shown. In the cyclone 30, the liquid heat transfer medium moves on circular paths. In the case of condensation, the gaseous heat transfer medium or the working medium can flow from the cylinder 10 into the cyclone 30 and, in the case of evaporation, from the cyclone 30 into the cylinder 10. Calculations and experiments have shown that the rotational speed of the liquid working medium, despite the friction of the liquid on the cyclone wall remains at a level sufficient for phase separation. Likewise, the heat exchange of the liquid working medium with the cycle ion wall with a suitable dimensioning of the machine and coating of the chamber walls not to a significant impairment of the process.

Fig. 5 shows a section through a cyclone with a twist according to a second embodiment. Not shown baffles in the cyclone and a tangential injection of the working medium provide a twist. This swirl promotes a mixing of the liquid working medium, which distributes the heat transferred by the phase change on the liquid surface evenly to the liquid phase.

Fig. 6 shows a T-s diagram of the novel process in direct injection after the suction of the steam (1) and in delayed injection (2) according to a third embodiment. The figure shows the ideal course of the injection process immediately after steam extraction (1). This process can e.g. be used for domestic water heating. In addition, the delayed injection process (2) is shown. The latter process can be used for space heating: steam at ambient temperature, e.g. 10 ° C, is first by adiabatic compression to z. B. 28 ° C compressed. Then 25 ° C warm liquid working medium is injected. Upon further compression, the condensation and heating of the working medium to z. B. 40 ° C a. The non-specific entropy S (Ws / K) was chosen as x-axis.

The operation of the heat pump will be described in detail below.

Process type condensation: In the bottom dead center (UT, see FIG. 3) of the piston or with a delay to UT, the liquid working medium is injected into the cyclone 30. In the cylinder 10 is the previously sucked steam. While the piston is being moved from BDC to top dead center (TDC), the engine is putting the lifting work into the heat pump. In this case, the previously aspirated vapor is compressed and condensed into the previously injected liquid phase. In the OT, the heated liquid working medium is expelled. is the heat transfer medium ejected, the exhaust valve 50 is closed. During the return of the piston from the TDC to the UT, the vapor generated in the evaporator 20 is sucked into the working space 15 of the cylinder. For this purpose, one or more inlet valves are opened. This completes the cycle. The illustrated system is very simple in the basic design. It only takes one injection valve and two check valves to fill and empty the cylinder.

Process type evaporation: In the OT, liquid heat transfer medium is injected into the cylinder chamber. When the piston travels from the TDC to the TDC, the heat transfer medium is vaporized and the liquid heat transfer medium is cooled. In UT, the liquid heat transfer medium is removed from the cylinder chamber. On the way of the piston from BDC to TDC, the steam is expelled and condensed in a condenser. In the OT, the steam outlet valves are closed. The process starts from the beginning.

A machine that picks up heat from a higher temperature level than the ambient level and picks up heat from a lower temperature level than the surrounding level, or a machine that gives off heat to a higher temperature level than the surrounding level and gives off heat to a lower temperature level than the surrounding level also referred to here as a heat pump. The latter two types of heat pumps are referred to as heat mirrors, when in an ideal course of the process, the temperature differences between the cold and the hot levels to the ambient level are equal in first approximation and the amounts of heat converted are the same.

As an example of a displacement machine, a reciprocating engine can be selected. In principle, however, the use of any type of displacement machine for the realization of the triangular processes according to the invention is possible. In the piston machine described below, the piston position top dead center, also called OT, defined by the fact that the volume contained in the cylinder is minimal in this piston position. Accordingly, the lower dead point, also called UT, defined by the fact that the volume contained in the cylinder is maximum in this piston position.

Two types of triangular processes in heat pumps are described below. In the first type, working fluid condenses in the working space (here: cylinder space) of the compression machine, in the second type working fluid evaporates in the working space (here: cylinder space) of the expansion machine.

The first type of triangular cycle is characterized in that first a working medium is evaporated to the temperature level of the environment while supplying heat in the evaporator (for example, evaporator 20) (heat consumption). The steam is sucked into the cylinder during the expansion, in this case during the piston movement from top dead center OT to bottom dead center UT. In bottom dead center UT or between bottom dead center UT and top dead center OT liquid and cold working medium is introduced into the cylinder chamber. As the piston moves from bottom dead center UT to top dead center TDC, the trapped vapor condenses into and heats the injected liquid and cold phases. At top dead center OT, the liquid phase is removed from the cylinder space. The heated liquid phase can then deliver the heat supplied to them as useful heat.

The second type of triangular cycle is distinguished by the fact that liquid working medium is introduced into the piston engine in the region of top dead center OT. If now the piston moves from top dead center OT to bottom dead center UT, part of the working medium evaporates and the working fluid cools down. If the piston is at bottom dead center UT, the cooled liquid phase is removed from the cylinder chamber and used for cooling purposes.

The prerequisite for the controlled phase change in both cycle types is that surfaces comprising the cylinder space have a higher temperature than the liquid phase; For these reasons, said surfaces may need to be heated and / or coated. The piston machine is an example of a discontinuous displacement machine. However, the triangular process can also be implemented in other displacement machines. Essential for the process is essentially an isentropic compression or expansion. An example of a displacement machine is a screw machine or a scroll compressor. The fact that currently available screw machines have too low a compression or expansion ratio, is noted marginally. The two above-mentioned processes are realized in displacement machines as follows:

The first type of cycle is characterized by a compression of a fluid which exists in two phases. Consequently, steam is first generated in an evaporator and sucked by the compression machine. Before entering the steam in the compression machine or after a pre-compression of the steam in the compression machine, liquid phase is introduced into the steam. In the compression machine, the mixture is further compressed. The vapor condenses into the liquid phase. If the steam is completely condensed, then there is only liquid phase at the outlet of the machine. In this ideal case and with isentropic conditions, the complete triangular process can be realized. As with the piston engine, the hot liquid medium releases its heat as useful heat after it leaves the machine.

The second type of cycle is in the general case of the expansion machine as follows: liquid working medium is introduced into the expansion machine. The expansion forces steam production. The required evaporation capacity is taken from the liquid phase, whereby it cools and can be used after leaving the machine for cooling purposes.

Heat-insulating coatings on the surfaces of the working area favor isentropic process control.

Since the cylinder is designed to be heated, convective heat is given off to the liquid and the gaseous working medium. This heat transfer is accompanied by exer- loss of energy and thus harmful to the process. Since cylinder wall and working medium sometimes have significantly different temperatures, the heat transfer must be reduced by measures. Calculations and experiments show in this context:

The heat transfer from the cylinder wall to the gaseous working medium is slight due to the low gas velocities and the low density of the gas.

The heat transfer from the cyclone wall to the liquid working medium is achieved by coating the corresponding cyclone wall with a heat-insulating material, e.g. Teflon, ceramic or enamel and / or by special types of injection of the working fluid to be kept harmless level.

For injection of the liquid working medium two possibilities are provided:

The liquid working medium is injected onto a circular path in an antechamber of the cylinder. Below we also call this circular path cyclone. The liquid working medium remains in the prechamber, while the gaseous working medium can move through an overflow opening between the prechamber and the cylinder space, depending on the prevailing pressure conditions between the rooms.

The liquid working medium is atomized during the injection process into the smallest possible droplets. The droplets are distributed in the cylinder space. Only droplets that come in the immediate vicinity of the heated surfaces can absorb heat on these surfaces. Since the heat absorption is associated with the evaporation of the droplets, the proportion of steam in the area of the heated surfaces increases and the vapor on the surfaces overheats. The superheated vapor inhibits further drops of liquid from moving toward the heated surfaces, reducing heat transfer. Important in the condensation in the liquid working medium is a good distribution of the heat of condensation within the liquid phase.

In the case of injection into the cyclone, the frictional flow of the liquid working medium leads to its mixed state. In addition, the cyclone for mixing the working fluid having a special design that allows turbulence of the working fluid. Heat released by the condensation on the surface of the liquid phase is thus dispersed quickly enough throughout the liquid phase due to the mixing. The cyclone has the advantage that removal of the liquid working medium from the cylinder can be carried out easily: if an outlet valve is opened on the cyclone bottom, the centrifugal forces help to remove the liquid working medium from the antechamber.

In the case of injection as a spray mist, the distribution of the heat of condensation poses no problem: the liquid droplets can be chosen to be very small, so that the distribution of the heat within the droplets is very fast due to heat conduction. The distribution of heat within the cloud of fog necessarily results from partial pressure differences: the condensation is always greatest at the coldest point and thus leads to a temperature compensation in the cloud.

Thus, the present invention relates to the structure and function of a heat pump with a phase change of the working medium in the cylinder space of a piston engine, wherein the heat transfer medium is liquid and vaporizable and is injected in liquid form into the cylinder chamber. Thus, a heat pump is provided in which liquid working medium is injected.

According to one aspect of the present invention, the liquid working fluid is injected into a portion of the cylinder space of the engine, namely the pre-chamber. The working medium moves in circular paths, the liquid heat transfer medium due to the high density and Because of the centrifugal forces caused thereby predominantly in the antechamber is kept, while vaporous working medium escape into the entire cylinder chamber and can penetrate from the cylinder chamber into the prechamber.

Thus, the heat pump has a working space consisting of cylinder space and pre-chamber, wherein the cylinder space and the pre-chamber are connected in such a way that an overflow of steam is possible. An evaporable working medium is introduced in liquid form into the pre-chamber, wherein the working medium is introduced onto a circle-like path. The circular path of the liquid phase causes centrifugal forces which greatly radially accelerate the liquid phase due to the high density. The radial acceleration and the structural design of the cyclone cause that the liquid phase can not escape from the antechamber. The volume of the cyclone device (dead space) should be as small as possible in the structure. In other words, the volume between the piston at top dead center and the volume of the cyclone unit not required by the liquid phase should be as small as possible.

According to a further aspect of the invention, the working medium in the cyclone in addition to the circular movement receives a twist, whereby the mixing of the working medium is improved. The cyclone is designed substantially circular in cross-section, so that the working medium can be provided with a swirl. The swirl serves to promote an intimate mixing of the working medium and to prevent the formation of a harmful for the process efficiency temperature gradient in the working medium.

According to a further aspect of the invention, the walls of the cyclone, which come into contact with the liquid phase, coated with a poor thermal conductivity material. To reduce the convective heat transfer from the liquid working fluid to the cyclone wall, the cyclone wall is provided with a poorly heat-conductive coating. This coating can be, for example, Teflon, ceramic or enamel. According to a further aspect of the invention, the working medium is injected in liquid form into the cylinder chamber of the machine, wherein the liquid phase is atomized by means of an injection nozzle. Thus, a heat pump is provided in which the liquid working medium is atomized as finely as possible during the injection process by means of an injection nozzle.

According to a further aspect of the invention, the surface of the piston facing the vapor-filled space of the cylinder is coated with a material having poor thermal conductivity. To reduce the convective heat transfer from the working fluid to the piston, the relevant surface of the piston is provided with a poorly heat-conductive coating. This coating can be, for example, Teflon, ceramic or enamel.

According to a further aspect of the present invention, the structural parts coming into contact with the resulting steam, such as the cyclone wall, cylinder wall or piston, are designed to be heated. When the gas is compressed, the gaseous phase accessible components of the engine must be at a temperature greater than the condensation temperature at the instantaneous vapor pressure. If the surfaces of the components were colder, part of the gaseous phase would condense abruptly on these surfaces. The condensed phase would no longer be available for condensation in the working medium, and the machine's performance and workload would be reduced.

According to one aspect of the present invention, the exhaust valves are closed in the region of top dead center, followed by the admission of steam to bottom dead center, whereupon the inlet valves are closed and liquid working fluid is injected directly or with a delay, followed by compression and condensation of the vapor in the liquid phase, whereupon the exhaust valve is opened at top dead center and thus the ejection of the heated liquid phase takes place. Then the cycle starts again. This aspect of the present invention relates to the process management in the process type condensation. With the machine one can of a Two-stroke talk. In the TDC, the inlet valves for the steam are opened. Steam is drawn from the evaporator until UT is reached. In UT, the inlet valves are closed and liquid working fluid is injected directly or with a delay. If the steam and the liquid working fluid are at the same temperature, they can be injected immediately after closing the intake valves. If the liquid phase to be injected is warmer than the vapor phase, it is not injected until the steam in the cylinder has been compressed until the pressure of the steam corresponds to the vapor pressure of the liquid phase. During the movement of the piston from BDC to OT, the steam is compressed and it causes condensation of the vapor in the liquid phase. In the TDC, the liquid phase is removed. Thereafter, the inlet valves are opened again, whereby the circuit is closed. During the process, the vaporous working medium in the cylinder is compressed, whereby it condenses at the coldest point, namely in the injected liquid phase, thereby heating the liquid phase. It is expressly understood that the injected liquid working fluid may also have a temperature lower than the ambient temperature. In this case, a sudden reduction of the vapor pressure occurs during the injection. The injection variant cold water is used, for example, for the heat pump type heat from cold. With a suitable temperature selection of the cold liquid working medium operation of the heat pump without mechanically supplied drive energy is possible.

According to another aspect of the present invention, the exhaust valves are closed in the region of top dead center, whereupon liquid working medium is injected, whereupon the expansion begins and the evaporation from the liquid phase and thereby the cooling of the liquid phase takes place, whereupon at bottom dead center liquid phase is removed and the outlet valves are opened for the gaseous phase, followed by reaching the top dead center of the ejection of the gaseous phase. The cycle then begins again. This aspect of the present invention relates to the process control in the evaporation process. In the region of top dead center (TDC) of the piston, the exhaust valve (s) is closed. and then injected the working medium. On the way of the piston from the TDC to the bottom dead center (UT) evaporates a part of the working medium. The onset of evaporation leads to a cooling of the liquid working medium. In the area of UT, the liquid phase of the working medium is removed from the cylinder space. On the way of the piston from UT to TDC, the resulting gaseous phase is expelled through an outlet valve and condensed in a condenser. It should be expressly pointed out that the expulsion of the vapor into the condenser can also take place when the condenser pressure is higher than the vapor pressure in the cylinder in the UT. In this case, the piston must first compress the steam in the cylinder until the condenser pressure is reached. Only then will the exhaust valve be opened. This litigation concerns z. B. the heat pump cold from heat. With a suitable temperature selection of the hot water operation of the heat pump without mechanically supplied drive energy is possible.

According to another aspect of the present invention, the injected heat transfer medium is water.

Claims

claims

A heat pump device comprising a cyclone unit (30) and a piston engine (10) having a cylinder space (15), wherein a liquid working fluid is injected into the cyclone unit (30) while vaporous working fluid is compressed by the piston engine or expanded in the piston engine.

2. Heat pump apparatus according to claim 1, wherein the injected liquid working fluid moves on circular-like paths in the cyclone unit (30) and thus in the cyclone unit (30) is held, while vaporous working medium from the cylinder chamber in the cyclone unit (30) can penetrate or from the cyclone unit (30) can escape into the cylinder chamber.

3. A heat pump apparatus according to claim 1 or 2, wherein the liquid working fluid receives a twist when it is injected into the cyclone unit or moves in the cyclone unit (30).

4. Heat pump device according to one of claims 1 to 3, wherein the cyclone unit has walls which are at least partially coated with a poor thermal conductivity material.

5. Heat pump device according to one of claims 1 to 4, wherein the surface of the piston at least partially with a poor heat-conducting

Material is coated.

6. Heat pump device according to one of claims 1 to 5, wherein the cyclone unit, the cylinder walls and / or the piston is at least partially heated.

7. A heat pump apparatus according to any one of claims 1 to 6, wherein exhaust valves are closed when the piston in the region of the upper Totpunktes is located, with a steam inlet is up to the bottom dead center of the piston, intake valves are closed and liquid working fluid is injected into the cyclone unit (30), wherein a compression and condensation of the vapor takes place in the liquid phase, wherein the outlet valve is opened is when the piston is at top dead center, wherein the heated liquid phase is ejected.

8. A heat pump device according to any one of claims 1 to 6, wherein exhaust valves are closed in the region of top dead center, wherein liquid working medium is injected, wherein the expansion takes place and the evaporation takes place from the liquid phase, wherein a cooling of the liquid phase takes place, wherein the liquid phase is taken at the bottom dead center and the outlet valves are opened for the gaseous phase, so that an ejection of the gaseous phase takes place to reach the top dead center.

9. Heat pump device according to one of the preceding claims, wherein the working medium is water.

10. Heat pump device, comprising a piston machine (10) with a cylinder chamber (15), wherein a liquid working medium is injected into the cylinder space, while vaporous working medium is compressed by the piston engine or relaxed in the piston engine.