DE2164224C3 - Heat engine with displacer and working piston - Google Patents

Description

The invention relates to a heat engine according to the preamble of claim 1.
In the case of heat engines operating according to the Stirling principle, a predetermined amount of gas is moved back and forth between a high-temperature zone and a low-temperature zone by means of a displacement piston. The thermal energy for heating up the amount of gas is transferred to the

) »Transfer working gas in the cylinder. The Pressure fluctuations resulting from temperature changes are converted into kinetic ones via a working piston Energy implemented. One of the practical advantages of such heat engines is that

r> solved exhaust gas problem, but with this advantage the serious disadvantage of only a low level of efficiency.

Various modifications based on the Stirling principle have already been shown at

4 »which also have a working medium between zones of consistently high and low temperature Piston is moved, but none of these developments has been implemented in practice. So is for example a heat engine known

<r> (GB-PS 2 29 235), in which a working fluid alternates from a liquid to a gaseous phase - and vice versa - by heating and cooling in corresponding zones is transferred. The working fluid is conveyed by a displacement col-

■ id ben and a pressure swing piston, the displacement piston due to a lateral play to the inner wall of the cylinder from the vaporous or liquid Working medium is alternately flowed around. An alternating raising and lowering of the liquid

Y> phase of the working medium is not provided in this known machine, since the change in the phases is caused by changes in pressure. In addition, the pressure change piston in this known machine only acts as a pressure stabilizer.

w) gate, which is designed as a pure plunger and a cannot provide effective dissipation of the converted kinetic energy.

Furthermore, there is still a device for converting mechanical energy into thermal energy or

h conversely known (DIIOS 15 51 313), with the one combined effect of a gas spring and a gas shock absorber is to be achieved. A compression piston is via its piston rod 2 with a

Engine connected and changes the volume of a compression chamber through its movement, which has a duct, a cooler, a regenerator and a freezer with an expansion cylinder in Is flow connection, the piston is connected to an auxiliary piston, which is in a with liquid filled cylinder is immersed The desired energy conversion is achieved by an adjustable throttle element reached at this cylinder space

The object of the invention is to improve the efficiency of a To improve heat engine of the specified type.

According to the invention, this object is achieved by the characterizing features of claim 1 solved

The higher efficiency of the heat engine aimed at according to the invention results from significantly increased differential pressures at lower operating temperatures, on the one hand due to & e use of the working fluid present in two phases as well as the formation of the regenerator as alternately flooded by the liquid phase heat storage is due. In this heat storage there is a temperature gradient through which the liquid lifted by the displacer accelerates evaporated or condensed when lowering. Particular advantages of the heat engine according to the invention lie in the relatively large differential pressures with small temperature differences, in the absence of one mechanical control and a feed pump and in their suitability for different, z. B. mixed. Work equipment. In addition to the low-noise operation, there is also the useful possibility of a Liquid and vapor heat storage.

In the following, exemplary embodiments of the invention are described in detail with reference to the drawing described. It shows

Fig. 1 is a schematic view of a heat engine,

2A-2F show the heat engine of FIG. 1 in different operating phases,

F i g. 3 a temperature-entropy diagram of the heat engine,

Fig. 4-7 other versions of the heat engine.

The heat engine shown in Fig. 1 contains three parallel cylinders, namely one as Heat accumulator formed cylinder 12, a displacement cylinder 14 and a working cylinder 16, whose upper ends are connected to one another by a manifold 18. The heat storage 12 is with a Bed of storage body 20, e.g. B. Metal balls filled on wire mesh.

In the displacement cylinder 14 is a mechanically driven displacement piston 22 with a piston rod 24 arranged, displaces the liquid working medium and at the same time the vapor phase of the Separates the liquid phase of the working medium. The piston rod 24 is sealed against the cylinder base. in the Working cylinder 16 is a reciprocating working piston 26 with mechanical work dispensing piston rod 28 arranged.

In the lower part of the heat reservoir 12 is a condenser 30 and an evaporator 32. In its upper part amounts of heat Q are fed in the direction of arrows in Fig. 1 to the evaporator 32 from the outside and discharged from the capacitor W, whereby the length of the Wärniespeichers 12 there is a temperature gradient in which in FIG. 1, the operating state shown is the heat accumulator 12 up to level 34 with a liquid working medium, e.g. B. water or, better, mixtures of ammonia and water 5 or trichloroethyl alcohol and water filled. Above this level 34, the working fluid is in the form of steam.

In the part of the distributor pipe 18 connected to the evaporator 32 there are regenerative evaporation bodies 36 arranged, stacked loosely or made out

ίο coiled thin metal wire or from other Materials with a large surface area and low longitudinal conductivity exist. This evaporation body 36 are z. B. held by cuffs with narrow bores that allow steam to flow through

th superheater 38 form in the distribution pipe.

Each level 34 in the heat accumulator 12 indicates an essentially constant temperature. if If the displacement piston 22 moves downwards in the cylinder 14, the liquid level 34 in the heat accumulator rises

χ 12 to the evaporator 32, wherein the liquid phase of the working medium is increased by the bed 20 in WärmesDeicherkörper 30 and then transferred to the liquid in the evaporator 20 in their gaseous phase. The balanced system pressure then corresponds to that

:> the saturation pressure assigned to the evaporation temperature. When moving the displacement piston 22 in FIG. 1 upwards, the liquid level 34 sinks in the heat accumulator 12 down to the level of the condenser 30. At the same time the moves

ii) working piston 26 in its upper pressure point position, wherein Due to the low system pressure, he only does a little compression work Working cylinder 16 and the distributor pipe 18 pushed out steam flows into the heat accumulator 12 and

r. condensed. When the liquid level is 34 in Condenser 30 is located, the low system pressure corresponds to the saturation temperature of the condenser.

The operational sequence of the heat engine is shown in FIGS. 2A to 2F and the thermodynamic process in 3 as a temperature-entropy diagram for the different positions of the pistons shown. The one shown in Fig. 2A, slightly modified in construction The type of construction is shown in FIG. 1 shown thermodynamically -. equivalent to. The combined functions of the in Fig. 1 shown displacement piston, namely the displacement of working fluid and the thermal Separation of vapor and liquid are in the embodiment according to F i g. 2 structurally simpler to the

> o Displacement piston and an additional separating piston distributed.

F i g. 2A shows the position of the displacement piston 22, the separating piston 94 and the working piston 26 on the End of the return stroke. The displacement piston 22 is in

ν-, its lower and the working piston 26 in its upper end position. The movement of the separating piston 94 is hydraulically coupled to that of the working piston 26. The liquid level is in the condenser, and the low system pressure corresponds

W) the saturation temperature of the capacitor. The relationships correspond to state A in FIG. 3

F i g. 2B shows the beginning of the working stroke, which is initiated by the movement of the displacement piston 22 winJ. the liquid level from the condenser 30 ·, To evaporator 32 rises. The system pressure in the overall machine is the saturation pressure assigned to the temperature of the evaporator 32. This State is through the point ßin F i g. 3 marked.

Because of the relationship

dl
d7

- (Satldanipf)

is also the difference between the maximum system pressure at the evaporation temperature and the minimum system pressure at condensation temperature is significantly greater than the comparable differential pressure a heat engine operated with gaseous working fluid, which is inevitably caused by the Relationship of the absolute inlet and outlet temperature is limited.

F i g. 2C identifies the working stroke of the system, during which the working piston 26 performs mechanical work. Since this working piston 26 and the separating piston 94 move together, evaporation and overheating also take place simultaneously - as in FIG. 3 indicated by the line C. The end of the working stroke is shown in FIG. 2D and corresponds to the state point D in FIG. 3.

The piston position at the beginning of the return stroke is shown in FIG. 2E and the corresponding state point E is indicated in FIG. This step is initiated by lowering the displacement piston 22 and thus the liquid level into its lower position. The system pressure drops to its lowest value. During the pressure decrease while the volume remains the same, the working fluid runs through the thermodynamic path DE

F i g. 2F shows the return stroke of the working piston 26, in which the separating piston 94 is the vapor phase of the Working medium from the separating cylinder against the low system pressure with little effort pushes out. The in F i g. 3 indicated by the line F The condensation process is in the state according to FIG. 2A ends, in which the cycle starts again begins.

The in the F i g. 4 to 6 can be roughly divided into two classes, ie machines with double-pressurized pistons and machines with displacement pistons. In the case of the in FIG. 4, the upper region of the evaporator 32 is only connected to the working cylinder 16 and the condenser 30 is connected to a second working cylinder 16a . The alternately flooded heat accumulator 12 is located between the evaporator 32 and the condenser 30. Both pistons are articulated to a common crankshaft.

In the case of the in FIG. 5, the displacement piston 22 and the working piston 26 work in a single cylinder. The evaporator 32 is connected to the cylinder 16 above the displacement piston 22 and the condenser 30 is connected to this cylinder below the displacement piston 22 and above the working piston 26 . The workload and the timing of the piston movements correspond to those of a Stirling engine in "Beta" design.

The in F i g. 6 has separate cylinders for the displacement piston 22 and the working piston 26. The evaporator 32 is only connected to the displacement cylinder. The work and the timing correspond to the "Gamma" design of a Stirling engine according to Robertson. In the case of the explanations according to FIG. 4 and 5, the displacement piston 22 must follow the working piston 26 during the stroke, so that the liquid level in the heat accumulator 12 and thus also the system pressure are maintained. 7 shows a mechanically simple practical embodiment of the heat engine with particularly good efficiency. The floodable heat accumulator has a liquid heat accumulator 72 which contains tubes with a relatively small inner diameter, small wall thickness and low thermal conductivity, and which is arranged between an evaporator 74 and a condenser 76. The specified design of the liquid heat exchanger 72 causes only low heat losses. Metal wool or the like is packed into the tube containing the liquid heat accumulator 72 in order to increase the cooling and heating of the working medium as it flows through. Brass balls 80 are arranged in the evaporator 74 to enlarge the heating surfaces, which results in faster evaporation of the working medium. The condenser 76 can also contain brass balls 82, which in a corresponding manner promote the condensation of the steam.

At the upper part of the evaporator 74, a U-shaped steam accumulator 84 is connected, which is a Material 86 of large surface area and low longitudinal conductivity, e.g. B. loosely wound thin Wire, contains. This material 86 stores some of the steam superheat from previous ones Cycles for use in a running cycle. At the end of the steam heat accumulator 84 is located a superheater 88, which may also contain brass balls to improve steam superheating. A dumbbell-shaped separating cylinder is connected to the superheater 88, which in its upper part a cylinder 89 of relatively large inner diameter with one on the upper end wall The bellows 90 is arranged in a vapor-tight manner. The interior of the bellows 90 is connected to the superheater 88 Flow connection, whereas the rest of the interior of the cylinder 89 by the bellows 90 opposite the Superheater is disconnected. The cylinder 89 is connected to a narrow, coaxial cylinder 92 in which a Piston 94 goes up and down, which forms a thermal barrier. The movement of this separating piston 94 is with that of the bellows 90 by a thermally stable liquid 95 in the cylinders 89 and 92 coupled, which has a low vapor pressure and increases the service life and operational reliability Pressure equalization for the bellows 90 causes

At the lower end of the narrow cylinder 92, a second wide cylinder 96 is connected, in which a Bellows 98 is fastened in a sealed manner. Between this bellows 98 and the piston 94 there is a second one Separating liquid 99, which fulfills a similar task as separating liquid 95. Liquids 95 and 99 are preferably of the same type and composition.

Under the bellows 98 connects a pressure equalization line 100 to the lower part of the cylinder 96 with the cylinder 102 in which a displacement membrane 104 leak-tightly secured is at this displacement membrane 104 is centrally a binary magnetic coil 106 via a rod 108 attached to the actuation of this solenoid 106 is controlled by a electronic switching device 112 controlled. The use of the bellows and the diaphragms instead of the sliding pistons avoids leakage losses, which can be of particular importance in small machines.

A hydraulic line 114 is connected to the lower end of the cylinder 98 and leads to a suitable consumer.

genes are possible, but this system is particularly special because of the tight and simple coupling advantageous.

The electronic switching device 112 can be a fixed circuit that continuously delivers current pulses to the magnetic coil 108. The magnetic coil 106 acts on the displacement membrane 104, so that the level of the liquid phase of the working medium between the condenser 76 and the evaporator 74 is moved up and down. The pressure equalization line 100 effects a pressure equalization in the system with the exception of the relatively small pressure differences that result from the low inertia forces of the flowing liquid. The pressure equalization line 100 advantageously enables movements of the liquid feeder with little energy being supplied to the magnetic coil. The magnetic coil can be provided with a mechanical lock or with a permanent magnet in order to secure the position it has assumed without any effort. A flywheel can be used to obtain a uniform cycle sequence and a gear unit can be used to convert the translational displacements of the piston into rotary motion. The electronic design, however, is cheaper and possible in particular because only small amounts of working fluid have to be displaced in the pressure-balanced system. In addition, the number of cycles of the system can be conveniently changed using the electronic control.

The operation of the in F i g. The heat engine shown in FIG. 7 corresponds to that of the simpler types according to FIGS. 1 to 6. The electronic control unit 112 provides programmed pulses to excite the magnetic coil 106, which moves the membrane 104 up and down. The membrane is preferably made of sheet metal or rubber and its diameter and its stroke in the wide cylinder 102 is large enough to accommodate the liquid level from the lower end of the narrow heat accumulator 72 to its upper end, ie from the evaporator 74 to the condenser 76 and vice versa.

Heat is supplied in the evaporator 74 and in the superheater 88 and removed from the condenser 76. The resulting change in the state of the working medium alternately causes maximum and minimum system pressure and thus bending of bellows 90 as well as a back and forth movement of heat separating piston 94, which is absorbed by bellows 98 as mechanical or hydraulic work in hydraulic line 114 .

There are also other versions of the heat accumulator possible. The working fluid can be composed of any number of substances or mixtures of substances be. For example, a mixture of 61% ammonia and 39% water gives better efficiency than water alone. Various metals or organic compounds are also suitable. In particular In some cases, work equipment can also be operated in the supercritical range to improve the efficiency will. Although the direct mechanical coupling to the working piston can be advantageous, the hydraulic coupling is more advantageous for many applications of the heat engine. The described Heat engine is suitable for a variety of different areas of application, from which z. B. the circulation of hot water through a diving suit, the underwater drive through a Screw or nozzle, the power supply of hydraulic tools under water, power plants, implantable Devices for supporting the blood circulation, remote-controlled pump systems and drives for land vehicles are called.

In addition 5 sheets of drawings

Claims (9)

Patent claims: 1. Heat engine with a mechanically moved displacement piston for alternating delivery of a working fluid in a closed system between a heated zone of high temperature and a cooled zone of low temperature, with a regenerator and a working piston for removing the mechanical work generated by expansion of the heated working fluid, characterized that the working fluid is a condensable vapor, that the regenerator is designed as a floodable heat accumulator (12, 72) which is cyclically flooded during operation by the liquid phase of the working fluid conveyed by the displacement piston (22, 104), and that at one end of the heat accumulator (12, 72) a condensation zone and at its other end an evaporation zone for the working fluid are provided. 2. Heat engine according to claim!, Characterized in that in the closed system an evaporator (32,74) and a condenser (30,76) are arranged at each end of the heat accumulator (12, 72) and that the controlled (106, 112) Movement of the displacement piston (22, 104), the liquid phase of the working fluid can be raised up to the evaporator (32, 74) and lowered to the condenser (30, 76), the system pressure when the evaporator is flooded being equal to the high pressure corresponding to the evaporation temperature and when the liquid level (34) is lowered to the condenser, it is equal to the low pressure associated with the condensation temperature. 3. Heat engine according to claim 1 or 2, characterized in that the from the outside cyclically driven displacement piston (22) in a cylinder (14) is sealed and the separates the liquid phase from the vapor phase of the working fluid. 4. Heat engine according to claim 3, characterized in that with the displacement piston (22) with a control device (112) coupled electromagnetic transducer (105) is rigidly connected. 5. Heat engine according to one of the preceding claims, characterized in that the working piston (26) is slidably guided in a working cylinder (16). 6. Heat engine according to one of the preceding claims, characterized in that the working medium consists of a mixture of different liquids. 7. Heat engine according to one of the preceding claims, characterized in that a separate separating piston (94), moved by the working fluid, with the working piston (26) hydraulically is coupled. 8. Heat engine according to one of the preceding claims, characterized in that the regenerator consists of one arranged between the evaporation zone and the condensation zone, with storage bodies (20) filled liquid heat storage (12) and from a between the Evaporation zone and a superheating / .one (38) arranged steam heat storage (36) bc- stands 9. Heat engine according to one of the preceding claims, characterized in that the displacement piston is designed as an electromagnetically actuated diaphragm piston (104) , that the working piston acted upon by the gaseous working fluid is designed as a bellows (90) and is arranged in a first liquid chamber (89) which is connected via a heat separating piston (194) containing intermediate cylinder (92) with a second liquid chamber (96) which is closed by a bellows (98) against a hydraulic line (1 14)