EP4290057A1 - Device and method for the conversion of quasi-isothermal state changes in thermal power or working machine processes - Google Patents

Abstract

The invention relates to a device (1, 20, 25) for implementing quasi-isothermal changes in state in heat engine or work machine processes, comprising a cylinder (2) which provides a working space (3) and a piston (4) which can be displaced in the working space (3). Limiting a gas volume that can be changed in the working space (3), the cylinder (2) having at least one access opening (5, 6, 21) for introducing and/or discharging working gas into or out of the working space (3), at least one heat transfer medium injection opening (7 ) for injecting a heat transfer medium (9) into the work space (3) and at least one heat transfer medium outlet opening (8) for discharging the heat transfer medium (9) from the work space (3), the at least one heat transfer medium outlet opening (8) and the access opening (6, 21) there are separate openings for discharging the working gas.

The invention further relates to a corresponding method for implementing quasi-isothermal changes of state in thermal power processes or work machine processes.

Description

The present invention relates to a device and a method for implementing quasi-isothermal changes in state, i.e. H. of quasi-isothermal compression or expansion, in thermal power or machine processes.

Isothermal compression is the theoretically most economical way to compress gases for all types of compressors. However, such isothermal compression is far from being achieved in practice, since for such a change of state to occur, as much heat must be quickly dissipated during compression as the compression work is supplied. To save energy and avoid high compressed air temperatures, we have so far worked with several compressor stages and intermediate cooling between the compressor stages at high pressure ratios or limited ourselves to passive air cooling using cooling fins in small devices. In all previously known embodiments and cooling variants, the technical work required is 15% to 30% higher than it would be with isothermal compression.

Analogous to compression processes, the same applies with the opposite sign for isothermal expansion. Examples of this are the theoretically best circular process, the Carnot process, and the well-known Stirling process, both of which contain two isotherms as ideal comparison processes, but which have so far been very inadequately implemented in reality. In order to realize isothermal expansion, heat must be supplied during expansion, analogous to the compressor, and during the expansion process, as much heat as the gas releases technical work.

So far, it has only been very inadequate to extract heat from the gas quickly and efficiently (compression) or to add heat (expansion), since thermal resistance has to be overcome in order to transfer heat. The heat transfer through cylinder walls and in particular the heat transfer from gases to walls or the limited thermal conductivity of the gases themselves make it impossible to achieve rapid and sufficiently high heat discharge or heat input.

Against this background, the present invention is based on the object of providing a device and a method for implementing quasi-isothermal state changes in cycle processes such as thermal power or work machine processes. The aim is to improve heat transfer to a working gas to be compressed or expanded in such a way that the working gas is kept essentially at its initial temperature level during the cycle, that is to say to compress the gas (quasi-)isothermally or to expand it (quasi-)isothermally . The isothermal compression or expansion should be carried out in an energy-efficient manner and a high level of efficiency should be achieved. In addition, the device should have a compact structure and the method should be as simple as possible to implement.

This object is achieved by a device with the features of claim 1 and by a method with the features of claim 10. Further, particularly advantageous embodiments of the invention are disclosed in the respective subclaims.

It should be noted that the features listed individually in the claims can be combined with one another in any technically sensible manner and show further refinements of the invention. The description additionally characterizes and specifies the invention, particularly in connection with the figures.

It should also be noted that a conjunction "and/or" used hereinafter between two features and linking them together is always to be interpreted in such a way that in a first embodiment of the subject matter according to the invention only the first feature can be present, in a second embodiment only the second feature can be present and in a third embodiment both the first and the second feature can be present.

As used herein, the term "approximately" indicates a range of tolerances that would be considered common to those skilled in the art. In particular, the term “approximately” refers to a tolerance range of the related size from to maximum +/-20%, preferably up to a maximum of +/-10%.

A device according to the invention for implementing quasi-isothermal state changes in thermal power processes or work machine processes, generally in a thermodynamic cycle, has a cylinder which provides a working space, furthermore a piston which can be displaced in the working space (also referred to herein as a working piston) to limit a working space variable gas volume, at least one heat transfer medium injection opening for injecting a heat transfer medium into the work space and at least one heat transfer medium outlet opening for discharging the heat transfer medium from the work space. The cylinder also has at least one access opening for introducing and/or discharging working gas into or out of the working space. It is possible to simply provide an access opening through which the working gas can both be introduced into the working space and removed from it again. Separate access openings, at least one of which only serves as an inflow opening for the working gas into the working space and at least one other access opening only serves as an outflow opening for the working gas from the working space, are also conceivable.

According to the invention, the at least one heat transfer medium outlet opening and at least the access opening for discharging the working gas from the working space are separate openings.

A device that implements a heat power process can also be called a heat engine. A heat engine is a machine that converts heat into mechanical energy (work). It exploits the tendency of heat to flow from areas with higher to those with lower temperatures.

A device that implements a cogeneration process can be called a work machine, a heat pump or a chiller. Such a device transports thermal energy from a lower temperature level to a higher one using mechanical energy.

Heat engines use "clockwise" cycle processes in which the closed curve is traversed in the sense "up to the right, down to the left" in the T-s diagram or p-v diagram, for example. Heat pumps use “counter-clockwise” cycle processes. The ideal comparison processes are used to assess the efficiency of circular processes. The theoretical basis of these processes is the thermal equation of state of ideal gases with the three gas state variables pressure, temperature, volume and the universal gas constant.

When we talk about circular processes in general, both right-hand and left-hand circular processes are meant equally, unless expressly stated otherwise.

The device according to the invention achieves a significantly improved implementation of quasi-isothermal changes of state in general and in particular when used in cycle processes with isothermal changes of state, in compressors/compressors, in expanders and when loading and unloading compressed air storage or storage based on the same functional principle, but different types of gas. Since the compression and expansion have so far been i. d. R. R. quasi-adiabatic or polytropic, possibly with intermediate cooling, the efficiency of the cycle processes can be significantly increased by approaching the isotherm. With compressors, the mechanical work to be supplied is reduced and with expanders, e.g. B. Unloading pressure accumulators, the work delivered is increased.

The heat transfer medium absorbs heat from the gas during compression of the working gas and releases heat to it during expansion of the working gas.

For the purposes of the invention, preferred heat transfer media are in particular liquids that have a high heat capacity, are not or only slightly corrosive, have poor solubility in gases and/or that the gas dissolves poorly in the liquid heat transfer medium, the viscosity of which for injection is in According to the invention is suitable, and which are thermally stable up to a temperature of about 220 ° C. The heat carriers are water, oils, especially low-viscosity oils, and ionic liquids desired properties are particularly preferred. Furthermore, liquids can advantageously be chosen which have a vapor pressure that is small compared to the minimum pressure in the working space (ie compression or expansion space). Such heat transfer media also have a large difference in density to the working gas, which naturally ensures easy separation from the working gas due to the effect of gravity, so that the heat transfer medium is collected specifically at a predetermined point in the working space or cylinder (e.g. in a heat transfer sump). can be, especially near or at the heat carrier outlet opening (e.g. on the floor).

It is to be understood that in order to achieve the described effect according to the invention, the heat transfer medium is injected into the working space via the at least one heat transfer medium injection opening essentially simultaneously during a compression or expansion stroke of the piston. The amount and drop size of the heat transfer medium can be suitably predetermined or controlled during operation. The pressure conditions in the work area and the material properties of the heat transfer medium are selected so that the heat transfer medium does not evaporate in the work area, as explained.

In particular, the heat transfer medium is distributed in one or more spray jets, that is, for example, essentially in the form of individual, specifically directed spray cones or shower-shaped in the manner of a shower, in which the heat transfer medium is directed downwards onto the piston through a large number of small openings is injected into the working space as a full jet and sprayed through the working space, essentially in the entire gas volume and, due to the high heat capacity of the drops compared to the smaller heat capacity of the working gas and due to the large transfer surface of the droplets, keeps the gas temperature of the working gas at or close to that Temperature level of the heat transfer medium. It should be understood that the term temperature level includes a certain temperature difference between the working gas and the heat transfer medium, since such a difference - possibly only a very small one - is always physically/technically present.

The heat transfer medium injection opening can be designed in the shape of a nozzle in order to direct the heat transfer medium into the work space in the form of a suitable spray cone to inject. Advantageously, such a nozzle-like opening can be in a cylinder wall, e.g. B. in a cylinder head, be recessed in order to minimize a dead space in the cylinder (for example in the area of the cylinder head).

After compression or expansion, the working gas is pushed out of the working space via the at least one access opening (e.g. Stirling engine). After the heat transfer medium has transferred heat to the working gas, heat is supplied or removed from the heat transfer medium via a heat exchanger. This heat transfer takes place outside the cylinder.

A particular advantage of injecting the liquid heat transfer medium is the efficient transfer of heat from the drops to the working gas to be compressed/expanded. This means that the working gas can be kept cold (compressor) or vice versa heated (expansion, e.g. Stirling engine) in a very short time (e.g. around 0.2 s or faster) by injecting a cold heat transfer medium. When combining the device according to the invention with a Stirling engine, practical, in particular significantly higher, speeds can now be achieved.

According to the invention, the heat transfer medium outlet opening for the heat transfer medium is clearly separated from at least the access opening for discharging the working gas. Likewise, the heat transfer medium outlet opening can be provided separately from both the access opening for dispensing and from the access opening for introducing the working gas, wherein the access opening can only be a single opening for introducing and discharging the working gas or several dedicated access openings can be provided.

According to the invention, the heat transfer outlet opening is provided separately from at least the access opening for discharging the working gas from the working space. The separation of the working gas from the heat transfer medium preferably takes place essentially in the cylinder/working space. Since, according to the invention, the working gas and the heat transfer medium do not exit the cylinder from the same opening, an otherwise usual heat transfer transfer outside the cylinder can be dispensed with or this be dimensioned much smaller in order to separate the residual liquid, provided that an external heat transfer medium separation is still to be provided, which overall enables a simplified, compact structure and reduces the manufacturing costs.

Furthermore, the heat transfer outlet opening can also be located at a predetermined minimum distance from the access opening for discharging and, if necessary, introducing the working gas into the working space, that is, not in (immediate) proximity/adjacent to the access opening. The possible spacing of the respective outlet openings also ensures that the heat transfer medium is separated from the working gas as completely as possible.

According to an advantageous embodiment of the invention, the at least one heat transfer medium outlet opening is arranged below the at least one heat transfer medium injection opening in relation to an operational position of the cylinder in the direction of gravity (i.e. in the direction of gravitational acceleration or gravity). The injected heat transfer medium, i.e. H. the liquid drops, collects in the area of the heat transfer medium outlet opening due to the force of gravity, so that the heat transfer medium can be sucked or pumped out of the working space in a controlled/targeted manner, is cooled or heated outside the working space and is then made available for renewed injection. This ensures an efficient heat transfer circuit. In addition, the heat carrier injection opening arranged above the heat carrier outlet opening enables targeted injection of the heat carrier into the entire working space in order to efficiently release heat to the working gas within the entire gas volume, that is to ensure that the working gas remains as constant as possible at its initial temperature level.

A further advantageous embodiment of the invention provides that the at least one heat transfer medium injection opening is arranged in an upper end section of the working space in relation to an operational position of the cylinder in the direction of gravity (ie in the direction of gravitational acceleration or gravity). The cylinder can have a cylinder head that delimits this end section of the working space. The upper end portion of the working space can accordingly be arranged close to or adjacent to a cylinder head be. The heat transfer medium injection opening can be arranged in the cylinder head. In other words, the heat transfer medium is injected into the working space from above, hits the piston and/or a cylinder wall and is then directed towards the heat transfer medium outlet opening due to gravity. This arrangement of the heat transfer medium injection opening makes it possible to minimize a dead space in the cylinder by arranging the heat transfer medium injection opening in any case above the top dead center of the piston in the cylinder, so that a continuous, efficient heat transfer from the heat transfer medium to the working gas is ensured for optimal isothermal compression or expansion.

According to a yet further preferred embodiment of the subject matter of the invention, a head surface of the piston is inclined with respect to a piston longitudinal axis, conical or curved, preferably curved in a bowl shape. The head surface of the piston is the piston surface that limits the gas volume in the working space on the piston side. A curved surface can, for example, be understood as a flattened “hemispherical shape”.

For a given outside diameter of the piston head surface and a given radius of curvature of the piston head surface in the middle of the piston, the bowl shape has a particularly strongly curved edge, the radius of curvature of which can only be approximately 10% of the outside diameter.

The oblique, conical or curved piston shape, on the one hand, effectively prevents unwanted accumulation of the heat transfer medium on the top of the piston or piston head surface and, on the other hand, promotes deflection in the direction of the heat transfer medium outlet opening or a liquid sump optionally provided upstream of the heat transfer medium outlet opening. The sloping shape of the head surface also enables optimal injection lengths of the heat transfer medium even near the top dead center of the piston, in order to ensure effective heat transfer from the heat transfer medium to the working gas even in this piston position. For this purpose, the heat transfer medium can be injected essentially parallel to the inclined piston head surface into the working space.

It goes without saying that the cylinder or a cylinder head is adapted to the respective piston shape (i.e. oblique, conical, curved and the like) in order to keep the dead volume as small as possible.

According to a yet further advantageous embodiment of the invention, the piston is designed as a plunger piston cylinder (also referred to as a plunger). Plunger piston cylinders, plungers, displacer pistons or plunger cylinders do not have an actual piston, but the piston rod itself serves as a piston. The plunger slides in a seal and sliding guide that are fixed to the cylinder. Although plungers have to be guided axially, they have a better mechanical efficiency. With the plunger piston cylinder, discontinuous piston control can also be achieved using a hydraulic drive.

As an alternative to the hydraulic drive of a plunger piston cylinder, another piston can have a mechanical drive with a connecting rod and crank mechanism.

The seal, which is fixed to the cylinder (instead of a piston seal that moves along the cylinder wall with the piston in a conventional piston), has, among other things: the advantage that the device is sealed to the outside in every plunger position, and further that there is a fluid-conducting connection between the heat transfer medium injection opening and the heat transfer medium outlet opening at all times. In this way, continuous, efficient heat transfer between the heat transfer medium and the working gas can be ensured in order to achieve optimal isothermal compression or expansion. In addition, the simultaneous and continuous injection and removal of the heat transfer medium enables the amount of heat transfer medium in the cylinder or working space to be precisely adjusted, so that dead spaces can be reduced compared to conventional piston machines. Furthermore, harmful pressure peaks in the working space when the heat transfer medium/working gas mixture is pushed out can be reliably avoided by the permanent fluid-conducting connection between the heat transfer medium injection opening and the heat transfer medium outlet opening.

In addition, the surface temperature of the cylinder inner wall can be reduced as a result of improved heat transfer or heat exchange on the inner wall of the cylinder through constant contact with the inflowing heat transfer medium. In addition, the absence of a piston seal means that no frictional heat is generated on the inner cylinder wall. Accordingly, the use of the plunger leads to lower requirements and a lower thermal and mechanical load on the cylinder inner wall, since the plunger is not in frictional contact with it.

Furthermore, an optimal distance (i.e. annular gap) between the plunger and the inner cylinder wall can be freely selected in order to increase the efficiency of the device or to adapt the geometry of the annular gap to the viscosity of the heat transfer medium. For example, the plunger and the inner cylinder wall do not necessarily have to be aligned concentrically. The plunger shape can also make it possible to freely design a sump space for collecting the heat transfer medium upstream of the heat transfer medium outlet opening in terms of volume and geometry. For example, the sump space can have a larger diameter or a different geometry than the rest of the cylinder wall. In this way, for example, the dead space can be positively influenced in the sense of minimization via the sump height or the fill level of the heat transfer medium in the sump space.

The use of the plunger also makes it possible to use ordinary check valves in the access openings for introducing and removing the working gas.

According to another advantageous development of the subject matter of the invention, an annular gap is provided upstream of the heat transfer medium outlet opening between the piston and an inner cylinder wall of the cylinder for collecting the heat transfer medium before it is discharged from the cylinder. As explained herein, a natural, gravity-assisted separation of the injected heat transfer medium from the working gas already takes place within the working space. In the present embodiment, the sprayed liquid drops flow downward in the annular gap, for example by flowing laminarly along walls of the annular gap, and collect into one in front of the heat carrier outlet opening Liquid sump that can be pumped/suctioned out of the work area in a controlled manner. The annular gap is preferably dimensioned so small that, on the one hand, the heat transfer medium can flow through in sufficient quantity and reach the heat transfer medium outlet opening, but on the other hand, the dead volume formed by the annular gap remains as small as possible. Particularly preferably, such an annular gap can have a ring diameter (ie radial diameter) of about 0.1 mm to about 2 mm, more preferably between 0.15 mm and 1.5 mm and further preferably between about 0.2 mm and 1.5 mm . Smaller ring diameters can be selected from the specified ranges when using thinner heat transfer fluids and larger ring diameters within the specified ranges when using thicker heat transfer fluids. The height of the annular gap can be dimensioned such that a reservoir of the liquid sump can be formed, which can temporarily hold at least part of the heat transfer medium injected per unit of time. The total volume of the annular gap is preferably always limited to a minimum. The annular gap enables both a compact structure of the device and a continuous, non-interrupting exchange of heat medium into and out of the working space.

According to a further embodiment, a demister is advantageously arranged in the annular gap in order to additionally separate even the smallest amounts of the heat transfer medium from the working gas, which may still have remained in the working gas after the gravity-assisted separation of the majority of the heat transfer medium. The demister can be used to create a trickling section in the annular gap. It can be advantageous to reduce the lowering speed of the heat transfer medium by trickling it in the annular gap, since due to the pressure fluctuations that occur in the working space, gas absorption - even if only small - in the heat transfer medium cannot be completely ruled out. To separate drops of heat transfer medium from the gas outlet openings of the cylinder, an insert in the form of a cover, a metal grid or similar can be attached within the cylinder/cylinder head.

The demister can be designed, for example, using a porous material or as a wire mesh filter, if necessary in combination with one or more external or woven metal grids.

In addition to the annular gap, according to a further embodiment, a sump space for collecting the incoming heat transfer medium can be provided at the lower end of the annular gap in relation to an operational position of the cylinder in the direction of gravity (i.e. in the direction of gravitational acceleration or gravity). The sump space can differ from the annular gap in that it has a larger radial width (i.e. radial diameter). The sump space provides a free space or sump in which the introduced heat transfer medium can collect and deposit, among other things. to separate gas bubbles. Furthermore, the filling level of the sump can always be controlled in such a way that working gas cannot flow out of the cylinder via the at least one heat transfer medium outlet opening at any time. For this purpose, the heat transfer medium outlet opening can be arranged and connected, for example, at the lower edge of the sump space, that is, the heat transfer medium can be discharged from the sump space directly via the heat transfer medium outlet opening.

To further optimize the controlled exchange of heat transfer medium into and out of the work space, a further embodiment of the subject matter of the invention provides a double-acting pump piston, which is set up to simultaneously inject the heat transfer medium into the work space via the at least one heat transfer medium injection opening and out of the work space via the at least one heat transfer medium outlet opening to be applied or sucked out. In other words, when the heat transfer medium is injected, the same amount is simultaneously discharged or sucked out of the working space, whereby the gas volume of the working gas in the cylinder/working space is kept constant in relation to the heat transfer exchange. This prevents undesirable compression of the working gas when injecting the heat transfer medium and undesirable expansion of the working gas when dispensing/extracting the heat transfer medium and, as a result, increases the energy efficiency when implementing the cycle. The liquid volume of the heat transfer medium in the cylinder remains constant because the same amount of liquid is sucked out at the same time as it is injected.

Accordingly, a collecting container and a high-pressure container for the heat transfer medium can be omitted. Only one piping or connecting lines for the The passage of the heat transfer medium and the double-acting pump piston must be filled, which significantly reduces the total amount of heat transfer medium required in the device.

The work required for injecting the heat carrier can be reduced to an optimal value, and the heat carrier can be efficiently brought to an injection pressure at which a thermal resistance from the heat carrier to the working gas is reduced during the injection process. The heat transfer medium is not unnecessarily relaxed, e.g. B. compressed to ambient pressure and later again to a high injection pressure, but only the differential pressure between the heat carrier outlet and the injection pressure is applied, which represents the most energy-efficient injection of the heat carrier.

The simultaneous heat transfer exchange in the cylinder ensures a constant heat transfer level, for example in a heat transfer sump and/or in an annular gap.

In addition to the double-acting pump piston, two check valves can be connected to these for the direction-dependent passage of the heat transfer medium, so that when the heat transfer medium is injected into the work space and the heat transfer medium is simultaneously discharged/sucked out of the work space, no heat transfer medium can unintentionally flow back into the cylinder via the heat transfer medium outlet opening. This function can be reliably ensured with the help of the two check valves. In addition, the check valve arrangement allows the piston to work without load outside of the active injection time.

Furthermore, with the help of the double-acting pump piston for the simultaneous transport of the heat transfer medium into and out of the working space, a non-linear (e.g. non-sinusoidal) injection/suction quantity of the heat transfer medium can be easily specified over a complete cycle of the implemented cycle, which is what the Energy efficiency of the cycle process is further increased. For this purpose, the pump piston can be controlled with a non-linear or non-sinusoidal piston displacement. For example, at the beginning of a compression stroke of the working piston less heat transfer medium is injected into the working space than towards the end before the piston reaches its top dead center (correspondingly reversed during expansion).

The double-acting pump piston can in particular be controlled in such a way that there is a constant pressure difference between the working pressure in the cylinder or working space and the injection pressure of the heat transfer medium throughout the entire working cycle. This ensures that the heat transfer medium sprays evenly in the work area and minimizes the amount of spraying required. In contrast, this pressure difference varies greatly in conventional injection systems with a constant pressure template of the heat transfer medium, which causes uneven and unfavorable spray formation.

As an alternative to the double-acting pump piston, the heat transfer medium can be transported using one or more conventional pump(s).

Furthermore, the piston (i.e. working piston) can be designed to be hollow inside the piston.

If the working gas continues to contain too high a proportion of liquid heat transfer medium for the intended application after a completed cycle of the implemented cycle, a further component can also be added, e.g. B. in the form of a separator, separator or similar, which separates excess liquid heat transfer medium from the working gas. The separated heat transfer medium can - if desired - be fed back into the heat transfer circuit or alternatively leave the circuit.

According to a further aspect of the invention, in a method for implementing quasi-isothermal state changes in thermal power processes or work machine processes, in which a working space is provided within a cylinder and a variable gas volume in the working space is limited by a piston that can be displaced in the working space (also referred to herein as a working piston). a working gas is introduced or discharged into and/or out of the working space via at least one access opening in the cylinder. A heat transfer medium is introduced into the workspace via at least one Heat transfer medium injection opening is injected and the heat transfer medium is discharged via at least one heat transfer medium outlet opening from the working space at a different location than the working gas, that is to say separately from the working gas.

It should be noted that with regard to process-related definitions of terms as well as the effects and advantages of features according to the process, full reference can be made to the explanations of corresponding definitions, effects and advantages of the device according to the invention and vice versa. In this respect, a repetition of explanations of similar features, their effects and advantages with regard to the device according to the invention disclosed herein and the method according to the invention disclosed herein can largely be dispensed with in favor of a more compact description.

Dispensing the heat transfer medium via the at least one heat transfer medium outlet opening separately from the working gas has the advantage of a natural separation of the heat transfer medium from the working gas that already takes place within the working space, e.g. B. as a result of a density difference between the heat transfer medium and the working gas as well as the effect of gravity. An otherwise usual heat transfer medium separation outside the cylinder can be dispensed with by discharging the two media separately, which significantly simplifies the implementation of the method according to the invention and successfully reduces implementation costs.

An advantageous embodiment of the method according to the invention provides that the heat transfer medium is injected into the work space in an upper end section of the work space in relation to an operational position of the cylinder in the direction of gravity (i.e. in the direction of gravitational acceleration or gravity) and is applied below the at least one heat injection opening, which further improves a natural, gravity-assisted separation of the heat transfer medium from the working gas within the working space between the heat transfer medium injection opening and the heat transfer medium outlet opening.

According to a further embodiment of the subject matter of the invention, the injected heat transfer medium is distributed over a correspondingly designed head surface of the Piston directed towards the heat carrier outlet opening. For this purpose, the piston head surface can, for example, be designed to be inclined with respect to a piston longitudinal axis or to be conical or curved. Particularly preferably, a curved piston head surface can be designed in the shape of a bowl.

According to another advantageous development of the method, the heat transfer medium is collected upstream of the heat transfer medium outlet opening in an annular gap between the piston and an inner cylinder wall of the cylinder before being discharged from the working space. After flying through the gas volume in the working space, the heat transfer medium flows downward in the annular gap and can collect in a liquid sump in front of the heat transfer outlet opening.

According to a still further embodiment of the invention, an annular diameter (i.e. radial diameter) of the annular gap is in a range from 0.1 mm to 2 mm, more preferably between 0.15 mm and 1.5 mm and even more preferably between 0.2 mm and 1 .5 mm selected. Smaller ring diameters can be selected from the specified ranges when using thinner heat transfer fluids and larger ring diameters within the specified ranges when using thicker heat transfer fluids. In this way, the heat transfer medium can, for example, flow laminarly along the walls of the annular gap in order to achieve a gravity-assisted, efficient separation of the heat transfer medium from the working gas within the cylinder. The height of the annular gap is preferably chosen so that, on the one hand, a sufficient reservoir of the liquid sump can be formed, which can temporarily hold at least part of the heat transfer medium injected per unit of time, and on the other hand, the total volume of the annular gap is reduced to a minimum.

Alternatively or additionally, a lowering speed of the heat transfer medium can be reduced by trickling in the annular gap. For example, a demister can be used in the annular gap for this purpose. Further working gas can separate from the heat transfer medium along the trickling section.

Alternatively or additionally, heat transfer drops can be attached to a panel, a Metal grid or similar inside the cylinder, e.g. B. are deposited at the gas outlet openings of the cylinder and/or in the annular gap.

Degassing of the heat transfer medium in the annular gap, e.g. B. with the help of the demister, additionally prevents the heat transfer medium from moving with the ascending and descending piston in the annular gap and not coming to rest, which, among other things, Reliable application (e.g. suction) of the heat transfer medium is made more difficult.

According to another embodiment, it is also advantageous for the heat transfer medium to be collected in a sump space at the lower end of the annular gap in relation to an operational position of the cylinder in the direction of gravity before being discharged. In the free sump space in which the incoming heat transfer medium can collect and come to rest, you can effectively, among other things, further gas bubbles are separated. Furthermore, the fill level of the heat transfer sump can be controlled in such a way that working gas cannot flow out of the cylinder through the heat transfer outlet opening at any time. In other words, the fill level of the heat transfer sump can always cover the heat transfer outlet opening and in this way reliably close it to the working gas.

Further according to a preferred embodiment of the subject matter of the invention, the heat transfer medium is simultaneously injected into the work space via the at least one heat transfer medium injection opening and is discharged or sucked out of the work space via the at least one heat transfer medium outlet opening using a double-acting pump piston. In other words, when the heat transfer medium is injected, the heat transfer medium is simultaneously released or sucked out of the working space in the same quantity, whereby the gas volume of the working gas in the cylinder/working space is kept constant in relation to the heat transfer medium exchange.

According to a yet further advantageous embodiment, the injection and/or suction of a quantity of the heat transfer medium occurs nonlinearly (e.g. non-sinusoidally) during the isothermal change of state, ie within a cycle, in the thermal power process or work machine process. During isothermal expansion and isothermal compression, it stops From a thermodynamic point of view, the work required for compression increases with increasing pressure in the working space. This means that on the way from the bottom to the top dead center of the working piston, increasingly more compression work has to be used for the same path and therefore more heat has to be cooled away. During a cycle of the cycle, the heat transfer medium is not injected at a constant pressure or with a constant volume flow, but at the beginning with a lower pressure and towards the end with a higher pressure or at the beginning less and at the end more heat transfer medium is injected into the working space. When it comes to expansion, it's the other way around. Here, most of the heat is supplied to the working gas at the beginning and less heat towards the end and thus a smaller amount of heat transfer medium towards the end or the heat transfer medium with a lower injection pressure. In this way, the amount of work required for injecting the heat transfer medium can be kept small and the efficiency of the implemented cycle process can be increased.

Furthermore, the working piston can be controlled discontinuously with a hydraulic drive if it is possible to be designed as a diving piston cylinder (i.e. plunger).

Fig. 1

eine Längsschnittansicht eines Ausführungsbeispiels einer Vorrichtung gemäß der Erfindung,

Fig. 2

eine Längsschnittansicht eines weiteren Ausführungsbeispiels einer Vorrichtung gemäß der Erfindung,

Fig. 3

eine Längsschnittansicht eines noch weiteren Ausführungsbeispiels einer Vorrichtung gemäß der Erfindung,

Fig. 4

ein Fließschema eines Ausführungsbeispiels eines Verfahrens gemäß der Erfindung unter Verwendung der Vorrichtung aus Fig. 1,

Fig. 5

ein Fließschema eines weiteren Ausführungsbeispiels eines Verfahrens gemäß der Erfindung unter Verwendung der Vorrichtung aus Fig. 2 und

Fig. 6

einen beispielhaften Druckverlauf eines Arbeitsgases im Verhältnis zu einem Druckverlauf eines Wärmeträgers einer beispielhaften Vorrichtung gemäß der Erfindung dar.

Further features and advantages of the invention result from the following description of a non-restrictive exemplary embodiment of the invention, which is explained in more detail below with reference to the drawing. This drawing shows schematically:

Fig. 1

a longitudinal sectional view of an embodiment of a device according to the invention,

Fig. 2

a longitudinal sectional view of a further embodiment of a device according to the invention,

Fig. 3

a longitudinal sectional view of yet another embodiment of a device according to the invention,

Fig. 4

a flow diagram of an exemplary embodiment of a method according to the invention using the device Fig. 1 ,

Fig. 5

a flow diagram of a further exemplary embodiment of a method according to the invention using the device Fig. 2 and

Fig. 6

an exemplary pressure curve of a working gas in relation to a pressure curve of a heat transfer medium of an exemplary device according to the invention.

In the different figures, parts that are equivalent in terms of their function are always provided with the same reference numbers, so that they are usually only described once.

Fig. 1 schematically represents a longitudinal sectional view of an exemplary embodiment of a device 1 for implementing quasi-isothermal state changes in thermal power processes or work machine processes according to the invention. The device 1 has a cylinder 2, which provides a working space 3, and a cylinder 2 which can be displaced, in particular longitudinally displaceable, in the working space 3 ( ie along its longitudinal axis 19), piston 4 to limit a gas volume that can be changed in the working space 3. The piston 4 (also referred to herein as the working piston) can be hollow. The gas volume present in the working space 3 can be expanded or compressed by the piston 4.

As in Fig. 1 As can further be seen, the cylinder 2 of the present device 1 has two access openings 5 and 6, one of which, 5, is used to introduce working gas into the working space 3 and the other, 6, is used to discharge the working gas from the working space 3. In Fig. 1 the access opening 5 is additionally and without necessarily limited to this formed with a suction valve and the access opening 6 with a pressure valve, as z. B. can be provided in a compressor. The valves in the access openings 5 and 6 can advantageously be designed as ordinary check valves, as in Fig. 1 is indicated. Furthermore, the in Fig. 1 shown device 1 at least one heat transfer medium injection opening 7 (two shown here) for injecting a heat transfer medium 9 into the Working space 3 and at least one heat transfer medium outlet opening 8 for discharging the heat transfer medium 9 from the working space 3. It is in Fig. 1 It can be clearly seen that the heat transfer outlet opening 8 and at least the access opening 6 for discharging the working gas from the working space 3 are separate openings.

In particular is in Fig. 1 It can be clearly seen that in the exemplary device 1 the at least one heat transfer medium outlet opening 8 is arranged below the at least one heat transfer medium injection opening 7 in relation to an operational position of the cylinder 2 in the direction of gravity G (ie in the direction of gravitational acceleration or gravity).

Next shows Fig. 1 that the at least one heat transfer medium injection opening 7 is arranged in an upper end section of the working space 3 in relation to the operational position of the cylinder 2 in the direction of gravity G. In the present case, the heat transfer medium injection opening 7 is arranged in a cylinder head 10 of the cylinder 2, wherein the cylinder head 10 can be flat, bowl-shaped or bevelled sharply towards its outer edges. The heat transfer medium injection openings 7 are located in the present example as in Fig. 1 can be seen in an upper end section of the cylinder 2.

The shape of the cylinder head 10 is adapted to a piston head surface 11. The head surface 11 of the piston 4 limits the gas volume in the working space 3 on the piston side. In the example shown here, the head surface 11 of the piston 4 is curved, preferably bowl-shaped. In Fig. 1 the head surface 11 is essentially shown as a flattened hemispherical shape, which can have the dimensions (ie outside diameters and radii) of a dish shape already mentioned in the general part of the description, but without necessarily being limited to this.

The exemplary device 1 in Fig. 1 also provides an annular gap 12 upstream of the heat transfer medium outlet opening 8 between the piston 4 and an inner cylinder wall of the cylinder 2 for collecting the heat transfer medium 9 before it is discharged from the working space 3.

At the lower end, ie based on the operational position of the cylinder 2 in the direction of gravity G, of the annular gap 12 points in Fig. 1 Device 1 shown additionally has a sump space 13 for collecting the incoming heat transfer medium 9. The sump space 13 is located in a lower end section of the cylinder 2 in relation to the direction of gravity G, which is diametrically opposite the upper end section.

In Fig. 1 It can be seen that the liquid heat transfer medium 9 is injected/jetted into the working space 3 from above, whereby, depending on the dimensions of the cylinder 2 or the working space 3, a single spray cone or several (as shown here) can be used. The heat transfer medium 9 is injected through the cylinder head 10 and directed by the piston 4, in particular its head surface 11, in such a way that the liquid heat transfer medium 9, after flying through the gas volume present in the working space 3, flows downward in the annular gap 12 and is located at the bottom in the sump space 13 accumulates. After the working gas has been compressed or expanded, it can be pushed out via the access opening 6.

The heat transfer medium 9 has the task of absorbing heat from the working gas during compression and releasing heat to the working gas during expansion. The injected/jetted heat transfer medium 9 hits the piston 4 or the cylinder wall and can flow from there via the annular gap 12 into the sump 13. The annular gap 12 is only chosen so large that, on the one hand, enough liquid heat transfer medium 9 gets into the sump 13 and, on the other hand, the dead volume remains small. The sump 13 can provide a free space in which the introduced heat transfer medium 9 can deposit and collect, among other things. to separate gas bubbles. In the lower region of the cylinder 2 there are one or more heat transfer outlet openings 8. The filling level of the sump 13 is preferably selected so that it is ensured at all times that no working gas can flow from the cylinder 2 or the working space 3 into the outlet opening 8 .

The liquid heat transfer medium 9 is preferably selected with a high heat capacity, non-corrosive or at least slightly corrosive, with poor solubility in gases, ie the working gas dissolves poorly in the heat transfer medium, and with a viscosity suitable for injection. In addition, the heat transfer medium 9 is preferably thermally stable up to approximately 220 ° C. Suitable heat transfer media include water, oils and ionic liquids with the desired properties.

For injecting the heat transfer medium 9, the at least one heat transfer medium injection opening 7 is preferably designed in the shape of a nozzle. The number of injection nozzles, type of injection nozzle, arrangement and orientation must be selected so that the thermal resistance from the liquid heat transfer medium to the working gas in the working space 3 is minimized during the injection process and at the same time the effort for the injection is small. The nozzles are preferably recessed in the cylinder head 10 so that the dead space is minimized.

How Fig. 1 As can be clearly seen, the harmful space (ie dead space) formed by the annular gap 12 of the device 1, which includes the annular space not filled with the heat transfer medium 9, is very small due to the relatively small size of the annular gap 12.

In contrast to previously known devices, which only implement very slow individual strokes of, for example, only 4 s for a piston stroke from top to bottom dead center, in the device 1 according to the invention, heat is transferred from the injected heat transfer medium 9 to the working gas to be compressed/expanded so efficiently that this Gas can be cooled (compressor) or conversely heated (expansion) in a very short time (e.g. about 0.2 s or faster) by injecting cold heat transfer medium 9.

It was recognized that the higher the differential pressure (injection pressure minus chamber pressure in the working space), the better this is achieved (ie the thermal resistance between the liquid heat transfer medium and the working gas decreases). The device according to the invention, e.g. B. the in Fig. 1 Device 1 shown can be operated in an optimal operating state depending on the energy required for injecting the heat transfer medium and the desired cooling or heating effect on the working gas as well as the achievable shortening of the compression phase or expansion phase and thus the achievement of practical speeds.

The piston 4 can be used as a plunger cylinder (plunger/displacer) with z. B. a hydraulic drive 14 or a mechanical drive 15 with connecting rod and crank mechanism (cf. Fig. 4 and 5 ).

Fig. 1 It can further be seen that a suitable seal 16 and a sliding guide 17 can be provided at the bottom of the piston 4, which can be provided and mounted in a seal package 18 as a common assembly. In the exemplary embodiment shown, the seal 16 and the sliding guide 17 are fixedly attached to the cylinder 2 in a lower section. In the present case, the piston 4 is designed as a plunger which slides in the fixed seal 16 and sliding guide 17, ie the seal package 18. This has the advantage, among other things, that the device 1 is sealed to the outside in every plunger position, and further that there is a fluid-conducting connection between the heat transfer medium injection opening 7 and the heat transfer medium outlet opening 8 at all times. In this way, continuous, efficient heat transfer between the heat transfer medium 9 and the working gas can be ensured in order to achieve optimal isothermal compression or expansion.

Fig. 2 represents a longitudinal sectional view of a further exemplary embodiment of a device 20 for implementing quasi-isothermal state changes in thermal power processes or work machine processes according to the invention.

The main difference between device 20 and device 1 is: Fig. 1 is that only a single access opening 21 is provided for introducing and discharging working gas into or out of the working space 3, such as when using the device 20 as part of a Stirling engine. After the working gas has been compressed or expanded in the working space 3, it can be pushed out via the opening 21.

Furthermore, the device 20 differs from the device 1 Fig. 1 in that the heat transfer medium 9 is injected in a shower-like full jet into the working space 3 from above essentially in the direction of the piston head surface 11. For this purpose, the cylinder head 10 has a large number of small openings for the heat transfer medium.

Furthermore, the device 20 differs from the device 1 Fig. 1 a demister 22 which is arranged in the annular gap 12. The intended pressure fluctuations in the working space 3 can lead to a changing gas absorption of the liquid heat transfer medium 9, albeit small. It can therefore be advantageous to reduce the lowering speed of the heat transfer medium 9 by trickling in the annular gap 12 and to bring about degassing by means of the demister 22 in the working space 3. At the same time, this can prevent the heat transfer medium from being moved with the ascending and descending piston 4 over the annular gap 12, from coming to rest and from suctioning/expelling and, if necessary, reinjecting the heat transfer medium 9 from being made more difficult.

It should be noted that the provision of a demister 22 does not necessarily apply to the exemplary embodiment in Fig. 2 shown device 20 is limited, but optionally also with a device of the type of device 1 Fig. 1 can be combined. Conversely, a further exemplary device according to the invention (not shown) may be of the type of device 20 Fig. 2 , ie with only one access opening 21, can also be designed without a demister 22. In a corresponding manner, the specific type of heat transfer medium injection, e.g. B. in the form of individual spray cones as in Fig. 1 shown or effervescent as in Fig. 2 shown, can be combined in any way with one of the exemplary embodiments disclosed herein.

Furthermore, if the working gas still contains too high a proportion of liquid heat transfer medium after compression/expansion has been completed, excess liquid can be separated from the working gas using a separate separator, separator or similar. Such a separator can in particular be arranged outside the cylinder 2. The heat transfer medium separated in this way can, if desired, be fed back into the heat transfer circuit or, alternatively, leave the circuit. To separate large drops, an insert in the form of a cover/metal grid or similar can optionally be used at the heat medium outlet opening 8 within the cylinder 2.

Fig. 3 shows a longitudinal sectional view of yet another embodiment of a device 25 for implementing quasi-isothermal state changes in thermal power processes or work machine processes according to the invention. In this exemplary embodiment, the piston 4 of the device 25 or the head surface 11 of the piston 4 is designed to be inclined with respect to its longitudinal axis 19 of the piston. The cylinder head 10 is designed according to the piston shape. The spray cone of the heat transfer medium 9 to be injected is aligned approximately parallel to the piston head surface 11, so that a spray length of the spray cone of the injected heat transfer medium 9 is also possible at the in Fig. 3 The piston position shown near the top dead center is still sufficiently large to optimally achieve the effect described here (e.g. heat transfer to the working gas).

Fig. 4 presents a flow diagram of an exemplary embodiment of a method for implementing quasi-isothermal state changes in thermal power processes or work machine processes according to the invention using the device 1 as an example Fig. 1 The device 1 is in Fig. 4 operated as a compressor, for example. The air or the working gas enters the cylinder 2 via the intake valve/inlet opening 5 and, after compression, is pushed out via the pressure valve/outlet opening 6. In this example, the liquid heat transfer medium 9 is conveyed using a hydraulic pump 26, a pressure accumulator 28 and an unpressurized tank 27. The pressurization of the heat carrier injection nozzles 7 and the draining of a sump from the heat carrier outlet opening 8 is controlled with valves 29 and 30. The pump 26 conveys the heat transfer medium from the unpressurized tank 27 into the pressure accumulator 28. The pump 26 is preferably pressure-controlled. A heat exchanger 34 supplies or removes heat from the heat transfer medium, depending on the application. In this exemplary embodiment, remaining heat transfer drops and the compressed working gas are additionally separated from one another in a separator 31 arranged outside the cylinder 2. The separated heat transfer medium can flow back into the unpressurized tank 27 via a valve 32. The compressed dried working gas emerges from the separator 31 (33). In the present example, the piston 4 is driven by means of a crank drive 15, that is to say by means of a connecting rod and crank drive, and a sealing package 18.

Fig. 5 presents a flow diagram of a further exemplary embodiment of a method for implementing quasi-isothermal state changes in thermal power processes or work machine processes according to the invention using the device 20 Fig. 2 In the application shown, the cylinder 2 exemplifies a cylinder of a Stirling engine, not shown. On cylinder 2 there is only one access opening 21 for the working gas to a regenerator. In the present exemplary embodiment, a double-acting pump piston 38 conveys the heat transfer medium from the heat transfer medium outlet opening 8 to at least one heat transfer medium injection opening 7. The double-acting pump piston 36 is set up to simultaneously inject the heat transfer medium 9 into the working space 3 via the at least one heat transfer transfer opening 7 as well as via the at least one To discharge or suck out the heat transfer medium outlet opening 8 from the work space 3.

A piston control 39 of the pump piston 38 can z. B. hydraulically, electromechanically or via a crank mechanism and is synchronized with the movement of the working piston 4 in the cylinder 2, so that it injects/jets in heat carrier 9 during expansion or compression, depending on the application. The stroke volume, start of a stroke and duration must be selected accordingly. Three check valves 35, 36, 37 ensure that the heat transfer medium 9 flows back into the cylinder 2, e.g. B. in the heat transfer sump within the cylinder 2, prevented and the gas volume is not changed by the injection of the heat transfer medium 9 into the working space 3.

In the present example, the working piston 4 is hydraulically driven by a plunger cylinder (14). Lifting duration and lifting speed can be controlled via a hydraulic connection 40. The hydraulic drive 14 enables discontinuous piston control of the working piston 4. A heat exchanger 34 supplies or removes heat from the heat transfer medium, depending on the application.

The hydraulic connection 40 can be used, a hydraulic coupling between the working piston 4 and the double-acting pump piston 38 to produce, but without necessarily being limited to a hydraulic coupling. A mechanical coupling between the working piston 4 and the pump piston 38 is also conceivable. In any case, through a direct coupling between the working piston 4 and the pump piston 38, functionality of the injection system can be achieved independently of absolute pressures and pressure conditions. In conventional injection systems, depending on the operating parameters, the injection duration, timing and injection pressures have to be programmed in a complex manner. In addition, the valves with corresponding switching times can only be used for certain operating ranges. With the invention, a significantly wider operating range can be covered by a simple driver device with a hydraulic/mechanical clutch without complex programming and parameterization of the valves and switching times. A direct hydraulic/mechanical coupling also eliminates the need for additional auxiliary energy such as power supplies and conversion efficiencies for pumps and actuators (in valves).

In both flow diagrams shown Fig. 4 and 5 the working gas is introduced or discharged into and/or out of the working space 3 via the at least one access opening 5, 6 or 21 in the cylinder 2, the heat transfer medium 9 being injected into the working space 3 via the at least one heat transfer medium injection opening 7 and the heat transfer medium 9 is discharged from the working space 3 at a different location than the working gas via the at least one heat transfer medium outlet opening 8.

The injection and/or suction of a quantity of the heat transfer medium 9 during a cycle of the quasi-isothermal change of state in the thermal power process or work machine process can advantageously take place in a nonlinear manner. For this purpose, for example, the piston control 39 can move the pump piston 38 in a corresponding non-linear manner.

It should be noted that the provision of the double-acting pump piston 38 and/or the hydraulic drive 14 does not necessarily apply to the exemplary embodiment according to Fig. 5 is limited, but also with an exemplary embodiment according to Fig. 4 can be combined, that is, the double-acting pump piston 38 can, for example, with one Embodiment can be combined with a mechanical drive 15 of the working piston 4. Conversely, the hydraulic pump 26 can of course be used in accordance with Fig. 4 also with the hydraulic drive 14 of the working piston 4 according to one embodiment Fig. 5 be combined.

Fig. 6 represents an exemplary pressure curve of a working gas in relation to a pressure curve of a heat transfer medium of an exemplary device according to the invention. The device can, for example, be similar to the device 1 Fig. 1 or device 20 Fig. 2 be trained. In any case, the device has a double-acting pump piston similar to that in Fig. 5 pump piston 38 shown.

In Fig. 6 the pressure curve of the working gas in the cylinder is shown as a solid line 41 as an example of compression. The pressure curve of the heat transfer medium to be injected into the cylinder is shown with a dashed line 42. For comparison, the pressure curve of a heat transfer medium pressure with a conventional heat transfer medium reservoir with constant pressure and valve control is shown with a dash-dotted line 43 (not part of the invention). It is in Fig. 6 It can be clearly seen that the pressure profile 41 of the working gas increases non-linearly over time t during the exemplary compression. By means of a non-linear control of the double-acting pump piston 38 (cf. Fig. 5 ) it is possible to keep the pressure difference Δp of the heat transfer medium to be injected into the workspace constant over the entire cycle, which leads to a uniform spray formation of the heat transfer medium in the workspace over the entire work cycle and also minimizes the injection effort.

In contrast, the pressure difference between the pressure 43 of the heat transfer medium to be injected and the pressure 41 of the working gas in the cylinder changes significantly during the working cycle in a conventional injection system with a storage tank and valve control, which causes uneven spray formation of the heat transfer medium.

The device according to the invention disclosed herein and the method according to the invention for implementing quasi-isothermal state changes in thermal power processes or work machine processes with quasi-isothermal Compression or expansion are not limited to the specific embodiments disclosed herein, but also include further embodiments with the same effect, which result from technically sensible further combinations of the features of both the device and the method described herein. In particular, the features and feature combinations mentioned above in the general description and the description of the figures and/or shown in the figures alone can be used not only in the combinations explicitly stated herein, but also in other combinations or on their own, without the scope of the present invention to leave.

The device disclosed herein for implementing quasi-isothermal state changes in thermal power processes or work machine processes with quasi-isothermal compression or expansion is particularly advantageous for converting available energy from renewable energy sources, e.g. B. solar thermal energy, used in electrical energy, but without necessarily being limited exclusively to such applications. The converted electrical energy can be provided by the device according to the invention for direct use, for example in households or industrial plants and the like.

Reference symbol list

1

contraption

2

cylinder

3

working space

4

Pistons

5

First access opening

6

Second access opening

7

Heat carrier injection opening

8th

Heat carrier outlet opening

9

heat carrier

10

cylinder head

11

Piston head area

12

Annular gap

13

Swamp room

14

Hydraulic drive

15

Mechanical drive

16

poetry

17

Sliding guide

18

Seal package

19

Piston longitudinal axis

20

contraption

21

Access opening

22

Demister

25

contraption

26

hydraulic pump

27

Unpressurized tank

28

Pressure accumulator

29

Valve

30

Valve

31

separator

32

Valve

33

exit

34

Heat exchanger

35

check valve

36

check valve

37

check valve

38

Double-acting pump piston

39

Piston control

40

Hydraulic connection

41

Working gas pressure curve

42

Pressure curve of a heat transfer medium according to the invention

43

Pressure curve of a heat transfer medium in a conventional storage tank

G

Direction of gravity

p

Pressure

Δp

Constant pressure difference

t

Time

Claims (17)

Device (1, 20, 25) for implementing quasi-isothermal changes of state in thermal power or work machine processes, comprising a cylinder (2) which provides a working space (3), a piston (4) which can be displaced in the working space (3) to limit a gas volume that can be changed in the working space (3), the cylinder (2) having at least one access opening (5, 6, 21) for introducing and/or discharging working gas into or out of the working space (3), at least one heat transfer medium injection opening (7). Injecting a heat transfer medium (9) into the working space (3) and having at least one heat transfer medium outlet opening (8) for discharging the heat transfer medium (9) from the working space (3), the at least one heat transfer medium outlet opening (8) and the access opening (6, 21) There are separate openings for discharging the working gas. Device according to the preceding claim,
characterized in that
the at least one heat carrier outlet opening (8) is arranged below the at least one heat carrier injection opening (7) in relation to an operational position of the cylinder (2) in the direction of gravity (G). Device according to one of the preceding claims,
characterized in that
the at least one heat carrier injection opening (7) is arranged in an upper end section of the working space (3) in relation to an operational position of the cylinder (2) in the direction of gravity (G). Device according to one of the preceding claims,
characterized in that
a head surface (11) of the piston (4) is inclined with respect to a piston longitudinal axis (19), conical or curved, preferably bowl-shaped. Device according to one of the preceding claims,
characterized in that
the piston (4) is designed as a plunger. Device according to one of the preceding claims,
characterized in that
an annular gap (12) is provided upstream of the heat transfer medium outlet opening (8) between the piston (4) and an inner cylinder wall of the cylinder (2) for collecting the heat transfer medium (9) before discharge. Device according to the preceding claim,
characterized in that
a demister (22) is arranged in the annular gap (12). Device according to one of the two preceding claims,
characterized in that
a sump space (13) for collecting the incoming heat transfer medium (9) is provided at the lower end of the annular gap (12) in relation to an operational position of the cylinder (2) in the direction of gravity (G). Device according to one of the preceding claims,
marked by
a double-acting pump piston (38), which is set up to simultaneously inject the heat transfer medium (9) into the working space (3) via the at least one heat transfer medium injection opening (7) and to discharge it out of the working space (3) via the at least one heat transfer medium outlet opening (8). . Method for implementing quasi-isothermal changes of state in thermal power or work machine processes, in which a working space (3) is provided within a cylinder (2) and a variable gas volume in the working space (3) is created by a piston (4) which can be displaced in the working space (3). is limited, wherein a working gas is introduced or discharged into and/or from the working space (3) via at least one access opening (5, 6, 21) in the cylinder (2), wherein a heat transfer medium (9) is injected into the working space (3) via at least one heat transfer medium injection opening (7) and the heat transfer medium (9) is discharged from the working space (3) via at least one heat transfer medium outlet opening (8) at a location other than the working gas. Method according to claim 10,
characterized in that
the heat transfer medium (9) is injected into the working space (3) in an upper end section of the working space (3) in relation to an operational position of the cylinder (2) in the direction of gravity (G) and is applied below the at least one heat injection opening (7). Method according to one of claims 10 to 11,
characterized in that
the injected heat transfer medium (9) is directed towards the heat transfer medium outlet opening (8) via a correspondingly designed head surface (11) of the piston (4). Method according to one of claims 10 to 12,
characterized in that
the heat transfer medium (9) is collected upstream of the heat transfer medium outlet opening (8) in an annular gap (12) between the piston (4) and an inner cylinder wall of the cylinder (2) before being discharged from the working space (3). Method according to the preceding claim,
characterized in that
a ring diameter of the annular gap (12) is selected in a range from 0.1 mm to 2 mm, more preferably between 0.15 mm and 1.5 mm and even more preferably between 0.2 mm and 1.5 mm. Method according to one of the two preceding claims,
characterized in that
the heat transfer medium (9) is collected before being discharged in a sump space (13) based on an operational position of the cylinder (2) in the direction of gravity (G) at the lower end of the annular gap (12). Method according to one of claims 10 to 15,
characterized in that
the heat transfer medium (9) is simultaneously injected into the working space (3) via the at least one heat transfer medium injection opening (7) using a double-acting pump piston (38) and is sucked out of the working space (3) via the at least one heat transfer medium outlet opening (8). Method according to one of claims 10 to 16,
characterized in that
the injection and/or suction of a quantity of the heat transfer medium (9) occurs nonlinearly during the quasi-isothermal change of state.

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