NL8007070A - Reciprocating external-combustion engine - has liquid water injected directly into cylinder with reciprocating piston - Google Patents

Abstract

The reciprocating external combustion engine has energy transferred to a working gas from a heated liquid transfer medium. It has a cylinder with a reciprocal piston defining a working space. A heat exchanger heats the heat transfer medium externally of the cylinder under a pressure sufficient to maintain it liquid. The heat exchanger has an inlet to receive the medium and an outlet to deliver heated medium. An induction feed passes gas into the working end space. An injector is connected to the heat exchanger outlet to inject heated liquid medium into the gas before expansion of the gas in the working end space. An outlet from the cylinder exhausts heat transfer medium and working gas from the working end space near the end of the expansion stroke of the piston.

Description

- ί 2 * -

Lx 577½ 'Reciprocating engine with external combustion.

The invention relates to an reciprocating external combustion engine, ie an engine with one or more cylinders and associated pistons, the reciprocating movement of which is a power source, and the heat for driving it outside the cylinder is generated. In particular, the invention provides a new mode of action.

Many attempts have already been made to provide an engine which has both a great useful heat effect in converting supplied heat energy into useful work and an acceptable ratio of power to weight and power and content of the engine. The internal combustion engine has a good power-to-weight ratio, but a relatively little useful heat effect. The diesel engine has the best useful heat effect (up to about ^ 0%>) · Thermodynamically more effective machines that run on the Carnot, Stirling and Ericsson cycles have already been built, but these are in the generally not technically successful, mainly because of the difficulties in providing a small and efficient heat exchanger which allows the working gas to be heated quickly and efficiently by means of an external heat source.

The steam engine is a known form of external combustion machine, but the power-to-weight ratio is generally small, due to the fact that a separate steam boiler and condenser are required. The steam engine usually uses dried steam or other dry vapor as the work tool. The invention does not, however, relate to such a machine, but to an external combustion engine using a gas such as air as the work equipment.

The invention provides a reciprocating external combustion engine in which energy is transferred to a working gas from a heated liquid heat transfer means, the engine comprising: - a cylinder with a piston slidable therein, which together define a working space; 35 - a heat exchanger for heating the heat transfer 8007070

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- 2 - agent outside the cylinder, under pressure such that this agent is kept in the liquid state; - import means for introducing gas into the working space; - an injection part for injecting the heated liquid medium into the gas before or after introduction of the gas into the working space; and - an outlet in the cylinder, which can be controlled such that the heat transfer means can be discharged from the working space near the end of an expansion stroke of the piston.

This cylinder may be a single, double-acting cylinder with a piston which defines a compression space on one side thereof (usually the connecting rod side) and the working space on the other side, as with a two-stroke engine. However, this does not exclude the use of equivalent mechanical embodiments, such as for instance two cylinders coupled to a common shaft, in which the piston of one cylinder determines the compression space, and that of the other the working space. The engine may further be configured to operate in a four-stroke cycle, where one stroke is an input stroke. The compression ratio is preferably at least 2. ; 1.

This engine can also comprise a pair of mutually acting pistons placed in a common cylinder, the front surfaces of these pistons with the cylinder wall determining the working space.

25 Means are available for the introduction of gas into every work space. In the simplest form, a filling pump with an inlet port opening into the working space can be used to expel the exhaust gas and replace it with a fresh gas filling, which usually takes place in the vicinity of the bottom dead center. A press pump can also be used to supply compressed gas to the work area. With a two-stroke engine, the press pump can be formed by the compression space of the cylinder. However, a separate rotary or reciprocating press pump can also be used, for example a vane or turbine pump.

35 With a four-stroke engine, the intake stroke serves to introduce the gas.

If necessary, different inlet and outlet valves of the conventional type can be fitted, which valves can be in the form of non-return valves or can be operated by means of a cam driven by the 8007070 i-3 engine. Pit does not exclude the absence of valves, for example, as the piston can be used to open and close inlet and outlet ports, as is common with a two-stroke engine.

Furthermore, an injection nozzle is provided for injecting preheated liquid heat transfer agent into the gas. The purpose of the injected liquid medium is to effectively effect the heat transfer from the heat exchanger to the gas. Therefore, much smaller heat exchange areas are required to heat a certain amount of liquid compared to the area needed to heat the same gas mass. The object of the invention is therefore to heat the agent in the liquid state, and to heat the gas by contact with the hot liquid agent.

The heat transfer agent can evaporate or not under the operating conditions of the engine, after it has been injected into the working gas. A non-evaporating liquid will generally be introduced into the working space in the form of droplets with a large surface area. An evaporating liquid can at least partially evaporate to a vapor, whereby an extremely good heat transfer is obtained between the hot vapor originating from this transfer agent and the working gas.

The liquid heat transfer agent can be injected into the gas before or after its introduction into the working space.

When the heat transfer agent does not evaporate, it is preferably sprayed into the gas in the form of droplets. When an evaporating agent is used, it can evaporate completely or incompletely after injection. Although the liquid agent can be injected into the unpressurized working gas, it is known that a greater useful heat effect is obtained by injecting this liquid agent into the compressed gas.

In order to avoid confusion, the following expressions used will be clarified. The working gas into which the liquid agent has been injected will generally be referred to as a wet gas 55. Gas, into which the liquid medium has not yet been injected, is then called dry gas. The injected heat transfer agent can be present in the gas as a liquid or as a vapor.

The heating of the liquid heat transfer agent and the injection thereof into the working gas can take place in various ways 8007070 i *. -K -. Generally, the heat exchanger includes a burner for heating the liquid medium.

In the first place, the liquid in a compact heat exchanger, for example a coil from a narrow bore tube, can be heated to a high pressure and a high temperature (i.e. to a large internal energy). Since a narrow tube can withstand high pressures, it is usually possible to heat the liquid to the critical point. For particular applications where the heat transfer rate must be high, it may be preferable to heat the agent to a temperature and pressure above the critical point. The hot pressurized liquid agent is then introduced into a mixing chamber in the injected gas. A non-evaporating liquid agent is preferably injected by means of an atomizer. The internal energy of the agent is rapidly transferred from the hot liquid droplets to the gas, its pressure increasing. The heated and pressurized wet gas is then fed to the cylinder working space where it can expand (usually polytropic, i.e. not adiabatic), and then drive the piston.

In a second very favorable embodiment, however, the mixing chamber is omitted, while the high pressure hot liquid medium heated in the heat exchanger is injected directly into the working space of the cylinder. A fill of flushing gas is then compressed to a pressure sufficient to introduce it quickly into the working space as soon as the piston is near the bottom dead center. The dry purge gas is then compressed adiabatically, heating as the piston moves to the top dead center. Near the top dead center, the heated pressurized liquid medium is injected into the working space, further increasing the pressure of the compressed gas, and then expanding it. piston is driven back to the bottom dead center.

Heat transfer between the hot heat transfer agent and the working gas takes place very quickly. As the piston approaches the bottom dead center, the gas expands (usually polytropically), cooling it so that the liquid or vapor releases internal energy.

Preferably, the liquid is an evaporating liquid, for example water, which evaporates very quickly to vapor at least in part immediately upon injection into the working space. The heat transfer between the hot water vapor and the working gas takes place very quickly.

Therefore, in this second embodiment, the injected liquid agent is used exclusively as a heat transfer agent, which allows the compressed gas to convert internal energy into mechanical work. When an evaporating agent is used, the heat transfer is particularly effective, provided that most of the vapor leaves the cylinder in the liquid form, so that the latent evaporation space is not lost.

The engine according to the invention must be distinguished from a steam engine, since the agent remains in the liquid form and will not evaporate before it is introduced into the gas. This is in sharp contrast to a steam engine, in which, even when a rapid evaporation boiler is used, the water is always fed into the cylinder in the form of steam. Since it is necessary to use superheated steam in a conventional steam engine to remove water droplets, it is not possible to rapidly evaporate liquid water directly into its cylinder, since this would give rise to water droplets in this cylinder. In the motor according to the invention, on the other hand, the presence of water droplets in the working space can be permitted. In some cases it may even be desirable to design the piston and / or cylinder such that liquid medium remains in the working space after it has been drained. The piston or cylinder can be provided with suitable recesses for this purpose.

It is necessary to keep the heated injection means in the liquid state. Although this can be achieved by using suitable probes which ensure that the temperature at a given pressure never exceeds the boiling temperature, it has been found that when a nozzle of certain dimensions is connected to the heat exchanger in which the liquid medium is is heated, and a flow of the liquid medium is maintained through the heat exchanger, the application of heat to this medium does not lead to its boiling. Complex temperature and pressure probes can be avoided by a suitable choice of the dimensions of this nozzle. The nozzle is of course part of the injection part, through which the liquid medium is injected into the gas. It then becomes possible to control the operating speed of the engine by simply controlling the amount of heat supplied by the burner, for example by changing the fuel supply to the burner (at a given injection speed thereof).

Usually, the heat transfer agent is recovered from the exhaust gas after this gas has been removed from the working space. The recovered agent, which may still be warm, can be returned to the heat exchanger so that its internal energy is not lost. In this way, this agent acts only as a heat transfer agent, and is hardly consumed.

Water is a preferred heat transfer agent not only because it can evaporate, but also because it has a heat conductivity that is high compared to that of other liquids, such as heat transfer oils, for example. Furthermore, as will be further explained, means can be used to recover water formed by combustion in the burner. It then becomes possible to avoid any addition of water, since the water obtained by combustion in the burner can be used for this. It is of course possible to use other liquids, such as, for example, mercury, whose thermal conductivity is ten times greater than that of water or sodium. Mercury, however, has other obvious drawbacks, such as its price and toxicity. When water is used, an oil in the form of a dispersion, emulsion or solution may be added thereto to assist in lubrication of the engine.

The operating speed of the engine can further be controlled by controlling the injection speed of the liquid medium, for example, using a variable displacement pump.

In a preferred embodiment of the invention, the working gas is a gas which can participate in the combustion taking place in the burner. In this way, the internal energy of the gas discharged from the cylinder can be recovered. This gas can be a combustion supporting gas, such as oxygen, air or other oxygen-containing gas, or nitrogen oxide. The gas itself can also be a flammable gas, for which any known flammable gas can be chosen, such as gaseous hydrocarbons, carbon monoxide or hydrogen. In that case all or part of the exhaust gas can be fed to the burner.

8007070 - 7 ** * fc

The liquid burned in the burner can be any known fuel, such as gasoline, fuel oil, liquid or gaseous hydrocarbons, alcohols, wood, coal or coke.

It is generally preferred to use different heat recovery agents. For example, the entire engine can be insulated and provided with heat exchangers to collect scattered heat and transfer the compressed gas, for example, or preheat the fuel for the burner. It is further preferable to recover the heat remaining in the combustion gases, which can be done by passing the combustion gases through a spray chamber into which a flow of liquid (generally the same liquid as that into the engine is injected) by the combustion gas is sprayed. When an evaporating liquid medium is injected. When sprayed, it is preferable to spray the evaporating liquid through the combustion gases in order to heat this liquid close to the boiling point before being fed to the heat exchanger. Furthermore, when water is used as the transfer agent to be injected, the use of a water spray chamber or condenser is advantageous since water from the burner can then be condensed from the combustion gases, so that it is not necessary to supply make-up water to the engine.

The design of the engine according to the invention is considerably simplified in several respects compared to known engines, for example those with internal combustion.

The temperatures occurring in the working space are relatively low, so that sealing of the pistons is simplified.

It is noted that power in the engine according to the invention can be generated at lower temperatures than, for example, in an internal combustion engine. Furthermore, an internal combustion engine has a lower useful heat effect, since means must be used to cool the cylinders and prevent the engine from seizing up.

Since the temperatures occurring in the engine are relatively low, for example less than 350 ° C, it is usually not necessary to manufacture the cylinder from metal. Plastics such as poly-tetrafluoroethylene (PTEE), silicone resin-impregnated glass fibers, and others Plastics used in the art are particularly advantageous because of their low price and ease of use. Other heat insulation material 8007070

I

- δ - eels such as wood or ceramic can also be used.

In a preferred embodiment of the invention, the hot liquid medium is injected into one end of the working space, the inlet and outlet being near the other end of the piston stroke. The use of plastics with low thermal conductivity allows one end of the cylinder to be hot, while the inlet and outlet areas are relatively cold.

Power is taken from the engine by a piston rod connected to the reciprocating piston. The free end of the piston rod can be coupled directly to a rotary flywheel with a crank pin, while a separate crankshaft can also be used to convert the reciprocating motion into a rotary motion.

While the invention has been described with respect to a single cylinder engine, it will be appreciated that two or more cylinder engines are generally preferred in practice. In a two-stroke engine, it will generally be beneficial to communicate the cylinder compression space of a cylinder with the working space of another cylinder in order to introduce the compressed gas formed into the operating cycle of a given cylinder at the most appropriate time. .

The invention further relates to a method for operating an reciprocating external combustion engine, and to an assembly of components for converting an engine (eg internal combustion such as a diesel engine) into an engine according to the invention to transform.

The invention will be explained in more detail below with reference to a drawing; 1 shows a schematic representation of a first embodiment of an external combustion engine according to the invention; Fig. 2 is a simplified representation of this first embodiment to clarify the operating principle; fig. 3 shows a schematic cross-section of a cylinder of this engine; Fig. k is a schematic cross section of a heat exchanger of this engine; Fig. 5 shows a schematic cross-section of a spraying chamber for cooling the combustion gas of the burner; 8007070 - 9 - Fig. 6 is a schematic representation of a four-cylinder engine according to the invention; Fig. 7 diagrams of the relationship between the pressure and the content, respectively. the temperature and entropy for the first embodiment; FIG. 8 is a comparative diagram for a prior art internal combustion two-stroke engine; 9 and 10 schematic representations of a second and third embodiment of the engine according to the invention; and Fig. 11 is a schematic view, partly in section, of this third embodiment.

As can be seen from Fig. 1, the external combustion engine according to the invention mainly comprises a cylinder 5 with a piston 6, which has a compression space C and a working space. P, determine a heating coil H for heating liquid water under pressure by means of a burner B, if necessary a preheater PH for preheating fuel for the burner by means of the combustion gases, a sprayer S for cooling exhaust gases of the burner, a pump X for adding water under pressure to the heating coil, and a trap T for recovering liquid water from the wet exhaust gas from the working space.

The external combustion engine operates in the following manner. Air A with the ambient temperature and pressure is introduced into the compression space C of the cylinder 5 upon displacement of the piston 6 to the right (as seen in Fig. 1), thereby opening an inlet check valve k. The outlet in the compression space C is closed by means of a non-return valve 2. As soon as the piston 6 has reached the right-hand end position (top dead center, TDC), the inlet valve k is closed. As the piston moves further to the left, the air is compressed.

Compression is continued to obtain a sufficient air pressure in the space C, which is suitable for expelling the exhaust gas from the working space P, when the compressed air 35 passes through the inlet valve 2 in the working space P just before the bottom dead center (ODP). is allowed. When the piston approaches ODP, the outlet valve 3 is opened to drain wet exhaust air, and shortly afterwards the check valve 2 is opened to flush the working space P with compressed and slightly heated air and with 8007070 ί - 10 - dry air with almost the ambient pressure

Shortly after ODP, valves 2 and 2 are closed, after which, as the piston then moves back to TDC, the dry air is compressed adiabatically and iso-tropically · 5 Near the top dead center, hot water is pressurized through a valve and an associated injection nozzle 51 injected, causing the pressure inside the cylinder to increase very quickly (along the line bc in fig. 7) · The piston then moves back to the bottom dead center, decreasing the gas pressure and cooling the gas. The expansion of the gas in the cylinder is represented by the line cd in fig. Near the bottom dead center, the gas is expelled from the cylinder by air flowing in, the expelled air flowing to the trap T, which is provided with a baffle 10. In the trap T, liquid water is recovered, which is returned to the heater H, where it is heated and pressurized. The exhaust air and water vapor also pass from the trap T through a dryer D to the burner, where its internal energy is recovered. Condensate formed in the dryer is returned to the trap through a conduit 7. Water possibly condensed in the preheater PH is fed through a conduit 9 to the pump X.

Depending on the compression ratio and the operating speed at the time considered, the temperature of the injected water may be higher than or equal to the temperature of the compressed air in the working space.

FIG. 2 emphasizes the fact that the water itself acts essentially as a heat transfer agent which is recycled after use. The only water lost from the system is the water that is fed from the spray chamber S in the cooled combustion gases. The cycle will now be described in more detail. .

50 Heated water at ambient pressure and a temperature below 100 ° C is fed from trap T (and optionally from the spray chamber and preheater) to the press pump X, from which it is fed under high pressure to the heater H. The water is heated in the heater H to a temperature of about 300 ° C under 55 and a pressure of about 8.6 MPa. The water is usually heated to a temperature below the critical temperature and pressure (22 MPa resp.

57 ° C), but the pressure should always be such that at any temperature the water remains in the liquid state.

Ambient air is introduced into the compression space C 8007070 * - 11 - through the inlet valve 4, and is supplied to the working space P during the period from 45 ° before to 45 ° after ODP. As a result, the consumed air is flushed from the working space P and replaced by cold air. When the piston moves back to TDC, the air is compressed to about 1.2 MPa, with (for a compression ratio of 6 µl) the temperature in the top dead center o rising to about 330 ° C. The compression ratio in the cylinder is usually 2: 1..10; 1.

In BDP, warm water is injected into the working space P under a pressure of about 8.6 MPa 10 and a temperature of about 300 ° 0 by means of the injection nozzle 51, whereby part of the water immediately evaporates in a burst manner into vapor, whereby the remaining liquid water is distributed very finely, and the pressure in the space P increases rapidly. The water injection takes place during about 20..25 ° p of the entire stroke. The pressure achieved depends on the amount and temperature of the injected liquid water, and on the amount of it evaporating.

The rapid increase in pressure causes the piston 6 to return to ODP. At about 45 before ODP, the exhaust valve 3 and the inlet valve 2 are opened again in order to discharge wet exhaust gas from the space P. The temperature of the wet exhaust gas is made low to ensure that most of the water vapor in the space P condenses back into the liquid form, so that its latent heat of evaporation is recovered. The exhaust air and the water droplets are flushed out of the cylinder by the incoming flow of fill air, and passed to trap T, where the liquid water is separated from the consumed air before this air is fed to the burner. The warm recovered liquid water is returned to the heat exchanger.

Although the invention has been described with reference to a piston press pump in the same or a different cylinder as in which the working space is present, it will be clear that any other type of press pump can be used, for instance a rotary or reciprocating - and weather-moving pressure pump.

The exemplary embodiment considered enables a particularly simple cylinder design, as shown in Fig. 3. The relatively low operating temperatures make it possible to use technical plastic materials for the manufacture of the cylinder, which often have special advantages in terms of thermal conductivity.

The cylinder of FIG. 3 comprises a cylinder body 52 having a row of circumferentially distributed ports 55 »which form the inlet and outlet for the working space P of the cylinder. A cylinder head with a water injection nozzle 51 is attached to one end of the body 52, while an end plate 55 with an inlet 56 and an outlet 57 with associated check valves is mounted on the other end of the cylinder. A piston 58 and a piston rod 59 are placed in this cylinder.

It is noted that the piston has a formed upper surface, so that the filling air supplied to the working space P will flow through this space P in a path indicated by a broken line, so that the air loaded with water is effectively discharged from the space P is rinsed. For the greatest possible effect, it is important that the consumed air is effectively removed from the space P, so that this space can be filled with cool, dense filling air.

It will be understood that the end of the cylinder near the injection nozzle 51 is at a relatively high temperature, while the end of the cylinder near the inlet and outlet ports 53 is at a relatively low temperature. The use of plastics with a low thermal conductivity makes it possible to maintain this favorable temperature difference. After all, if the heat could flow to the exhaust ports 53, the temperature of the consumed gas would rise, which would lead to a reduction in the useful heat effect.

The external combustion engine of the present invention exhibits a good power-to-weight ratio compared to an internal combustion engine. Although the ratio between power and displacement may be less good, the overall ratio between engine power and displacement is comparable. However, since it is possible to optimize the combustion conditions in the burner, it becomes possible to achieve a nearly complete combustion of the fuel to carbon dioxide and water, thereby avoiding retention of carbon monoxide and unburned fuel residues in the exhaust gases exhausted. Furthermore, since combustion takes place at substantially ambient pressure, there will be virtually no formation of nitrogen oxides during combustion. This engine therefore proposes an improvement over the internal combustion engines 8007070-13, not only in terms of useful heat effect, but also in pollution of the environment.

Furthermore, this engine is capable of using a wide variety of fuels, such as gasoline, fuel oil, gaseous or liquefied hydrocarbons (including methane, butane and propane), alcohol, and even solid fuels such as coal. The burner properties can be adjusted in such a way that a substantially complete and pollution-free combustion occurs. Furthermore, such an engine can run more quietly than a conventional internal combustion engine.

Fig. 4 shows the embodiment of the heat exchanger, which consists of the heating coil H and the burner B. This heat exchanger comprises an inner tube 60 and a coaxial outer tube 61, which define a double way for the combustion gas of the burner. An insulation 6½ 15 is fitted around the outside of the heat exchanger. A fuel inlet nozzle is for supplying fuel F into an air stream A, which is admitted through an air supply opening. Water W flows through the heating coil H, which consists of an inner coil 62 and an outer coil 63, the current sense of which is indicated by 20 arrows, such that the water flows out of the inner coil 62 at a point close to the point with the highest burner temperature. The pressurized hot water is then discharged through line 50 to be injected into working space P.

When a multi-cylinder engine is used, separate cam-controlled injection nozzles can be provided for each cylinder. A distributor can also be used, which can always carry the hot water under pressure to the cylinder into which it must be injected. These spray nozzles can deliver a fixed water flow at a different temperature. However, it is also possible to use injection nozzles which deliver a changeable water flow at a fixed temperature, especially when a faster change in the speed of rotation of the engine is desired.

Fig. 5 shows a spraying device for cooling and washing the combustion gases of the burner B, in order to recover part of the heat and of the water generated during the combustion. This appliance comprises a spraying chamber 17, not a funnel 18, onto which water is sprayed from a spraying head hl through a stream of hot combustion gases. These combustion gases are supplied through an inlet 19, and will pass around the chamber 8007070-14 before flowing through an outlet 20 as cooled combustion gas. The combustion gas then flows through the sprayed water, and finally through a water curtain, which falls down along the inner edge of the trigger opening 18. Preferably, the combustion gases are cooled to below 100 ° C in order to recover the latent heat of vaporization of the water from the burner. Water at a temperature of about 100 ° C flows out through the drain 21 before being passed by the pump X to the heat exchanger.

Cold supply water W is introduced into the chamber through the intermediary of a valve 40, which maintains a fixed water level in the bottom portion of the spray chamber. A circulating pump E with an associated pipe 22 serves to pass the water through the nozzle in order to heat it up to the boiling temperature. However, if it is desired in practice to cool the combustion gases below 100 ° C, it may be necessary to discharge water through the outlet 21 at a considerably low temperature, for example 50 ° C.

Fig. 6 shows a four-cylinder external combustion engine according to the invention. This engine consists of a flat assembly of four cylinders 40, 41, 42 and 43. Each cylinder comprises a piston 20 with an associated piston rod, which piston rods are engaged with a common crankshaft 44. It is noted that each pair of adjacent cylinders exhibits 180 ° phase difference. This arrangement is substantially similar to that of a single cylinder engine of Figure 1, so that some parts are omitted. Each cylinder has an associated heat exchanger-burner-assembly HX. Each pair of counter-acting cylinders 40, 41, respectively.

42, 43 has a common exhaust line that leads to the burners, so that fluctuations in the air pressure in the burners are damped.

FIG. 7 shows the idealized thermodynamic operation of the engine of FIG. 1, while FIG. 8 shows the operation of a conventional two-stroke engine for comparison.

Fig. 7 (i) shows the PV diagram in case hardly any injected water suddenly evaporates to vapor, so that most of it remains as droplets in the liquid state. This will occur when the evaporation rate is small compared to the piston stroke time.

Fig. 7 (ü) shows the theoretical PV and TS diagrams in case all the injected water evaporates to the gaseous state 8007070-15. This can occur in a slow-running engine.

In Fig. 7 (i) the air in the working space P is compressed adiabatically during the compression stroke (ie the gas constant is approximately 1.39), which is represented by the line ab. The compression is also iso-tropical, so that the air is heated.

At a solid content, liquid water is injected, and a small amount of water vapor is generated at the same temperature as the compressed air, so that the pressure along the line bc increases. When only the air in the working space is considered, there is no change in T, provided the injected water is at the same temperature. When the piston descends, the wet air expands along the line cd, but due to the presence of warm liquid water droplets, the expansion will not be adiabatic but polytropic (with the gas constant being 1.33 ·· 1 »35), so that the curve CD is flattened in the PV diagram. The expansion further leads to a decrease of T and an increase of S. The gas is then discharged from the working space, so that the pressure of the gas in this space decreases along da.

This replacement of warm exhaust air with colder fill-20 air reduces both T and S.

Fig. 7 (ii) shows the state when all the water suddenly turns into vapor. In this case, the pressure increase along bc is much greater, but the pressure drop along cd also occurs faster, since the absence of water droplets causes the air to expand substantially adiabatically. The work performed (i.e. the area of the figure abcd) is the same in both cases (i) and (ii).

Without entering a limitation by theoretical considerations, the pV and TS diagrams show the theoretical equilibrium when all the injected water is evaporated, ie with a slow running engine, when less than the amount required to saturate the air water is injected. For the sake of clarity, it is assumed that the temperature of the injected water is slightly lower than that of the compressed air in the cylinder.

As in the foregoing, the air is compressed adiabatically (gas constant about 1.39) along the line ab with fixed entropy. The pressure p at point a is, for example, 0.1 MPa, while the

& O

temperature T there is 3 ° 0 K (27 C). With a compression

Si attitude of 6 ï 1, the air pressure p ^ and the temperature in the point b is approximately 1.2 MPa, respectively. 603 K (330 ° C).

8007070 - 16 -

Liquid water of 573 K (300 ° C) and 8.6 MPa is then injected into the compressed air and completely evaporated. This causes an increase in pressure along bc (where p c = 2.5 MPa) and a decrease in temperature by injecting the slightly colder water (T = 5δ6 K). When the water has the same temperature as the compressed air, the line bc in the T & d chart is horizontal. The reduction in entropy of the air in the cylinder along bc results from the added partial pressure of the water vapor.

10 When the piston moves back to TDC, the wet gas expands (gas constant about 1.3 * 0 along cd to a pressure p ^ of about Q * 2 MPa and a theoretical temperature T ^ of about 319 K (b6 ° C) In practice, because of the non-theoretical behavior, the temperature will be somewhat higher, for instance 80..90 ° C.

The gas is then flushed out of the working space along the line da as above, thereby reducing the temperature, pressure and entropy of the gas in the working space.

In the TS diagram, p ..p indicates Fixed pressures. The total area of the two closed figures in the TS diagram 20 represents the amount of heat supplied to the air. In the illustrated case, this is negative, since the air is cooled by injection of the water. When the water is at the same temperature as the compressed air in point b, the surfaces of the two closed figures in the TS diagram will be equal to each other, ie no heat is supplied.

Fig. 8 shows the corresponding curves for a known two-stroke engine for comparison. These correspond to the case (ii) of fig. 7 · The line ae represents the opening of the exhaust valve before the end of the stroke in a conventional two-stroke engine.

Fig. 50 9 shows a second embodiment of the invention substantially similar to that of FIG. 1, except that the water is fed to a mixing chamber M, into which it is injected into the compressed air to reduce the pressure and pressure. increase its temperature. The hot compressed air and water vapor are then fed into the working space P of the cylinder, as in the previous case.

The trap T serves to recover liquid water droplets from the exhaust gas of the space P. This trap T is carried out in a manner known from the steam engine technology for removing 8007070 3 * 17 liquid water from a gas. However, this trap can also be implemented as a cyclone dryer. The water collected in this trap is returned to the spray chamber S.

The operation of this engine is as follows. Pre-heated water 5 from the spray chamber S is fed by means of a high-pressure porap (for example a piston pump) to a heating coil H, which consists of narrow-bore pipes. The water is heated to a high temperature and pressure by means of • burner B, for example 300 ° C resp. 8.6 MPa. The pressurized hot water then passes through a conduit 50 to an injection valve 51 in the mixing chamber M. This mixing chamber contains compressed and slightly heated air which is supplied from the compression space C and through the outlet valve 1 to it. When the outlet valve 1 and the inlet valve 2 are closed, pressurized hot water is injected into the chamber M 15 by means of the injection nozzle 51, whereby the temperature and the pressure of the air therein will increase. As soon as the piston 6 has reached the top dead center, the air containing hot water vapor is introduced from the mixing chamber M through the inlet valve 2 into the space P, the outlet valve 3 being closed. The admitted hot compressed air expands in the cylinder 20, driving the piston 6 to the bottom dead center, thereby cooling the air. As soon as the piston reaches the bottom dead center, the valve 2 is closed, while shortly afterwards the valve 3 is opened in order to let spent air, which is still warm and under some pressure, flow to the burner B.

Fig. 10 and 11 show a practical embodiment of the motor according to the invention, which in principle corresponds to the embodiment of Fig. 1, but no spray chamber is used. This engine has four V-shaped cylinders at 90 °. Water is passed from a storage vessel 100 by a high-pressure pump 101 through a tube 102 to a two-stage counterflow heat exchanger IO3, which is constructed in the manner of Fig. 1. A release valve 10 ^ is disposed between line 102 and a trap 100. Exhaust air is led to heat exchanger 103 through a conduit 105 from trap 100. The air flow is controlled by a valve 107. Fuel (for example, propane gas) is fed from a pressure vessel 106 through the pre-heater 126 into the air stream through the fuel valve 108. Combustion gases exit the heat exchanger through a flue 109.

Each piston 110 runs in a corresponding double-acting 8007070 - 18 - cylinder 111, and is connected to a crosshead 112 through a piston rod 113. The crosshead is coupled to a crankshaft 114 by means of an additional connecting rod 115 · Each cylinder has a cylinder head 116, which is provided with an injection nozzle 117, which is operated by means of a camshaft 118 and a rocker arm 119.

The piston rod side cylinder space acts as a pressure pump, introducing air through an inlet valve 129, and passing it to the inlet 127 of the other cylinder end by means of a pipe 128. Each cylinder further has an outlet port 120, which a common exhaust line 127 opens, which carries the air and liquid exhaust water to the trap 100. A flywheel 124 is placed on the crankshaft.

For example, this engine has a compression ratio of 6: 1, a piston with a diameter of 100 mm, and a stroke of 15 100 mm, each cylinder capable of delivering about 7 »5 kW of power at a water injection temperature of around 300 ° C and an injection pressure of 8.6 MPa. The inclination of the cylinders contributes to the draining of the liquid water by gravity. At JQQ ° C, approximately 5 g of water should be injected with each injection.

20 The entire motor is contained within an insulating enclosure.

Hot liquid water exits the heat exchanger through a conduit 122 and is fed to the injection nozzles 117. A pressure control valve 123 is included in line 122.

The depicted external combustion engine can achieve a very great useful heat effect. Theoretically, cold air A and cold water W (if any) are fed into the engine, while cold combustion gas is vented. Therefore, virtually all heat released by the burner will be converted into work. In practice, useful heat effects of about 50..60% can be expected.

8007070

Claims (29)

An external combustion reciprocating engine operating by a working gas, comprising a cylinder with a piston slidable therein, which together define a working space, a heat exchanger for heating a heat transfer means 5 outside the cylinder, and input means for introducing working gas into the working space, the cylinder being provided with an outlet, which can be controlled to discharge the transfer means from the working space near the end of an expansion stroke of the piston, characterized in that the energy is the working gas 10 is transferred from a heated liquid heat transfer medium, the heat exchanger (H) being configured to heat the transfer medium under such pressure that it remains in the liquid state, and the engine further injecting portion (51, 117) which can inject heated liquid transfer agent into the gas before or after the gas enters the working space (P) has been entered. 2. Engine as claimed in claim 1, characterized in that the injection part is arranged on the cylinder in order to inject the heated liquid transfer agent directly into the working gas in the working space. The engine according to claim 2, characterized in that the injector part is controlled to inject the heated liquid transfer agent near the end of a piston compression stroke. ** Engine according to any one of claims 1..3, characterized in that the exhaust comprises a port (120) in the cylinder wall which is released by the piston as soon as the piston approaches the end of the expansion stroke, the injection part being located at the end of the cylinder opposite the outlet. Engine according to claim 1, characterized by a mixing chamber (M) with a working gas inlet, the injection part being arranged in this chamber in order to inject the heated liquid transfer agent into the gas before the wet gas is introduced into the working space. implemented. 6. Motor according to any one of claims 1..5> characterized in that the gas is compressed before the heated liquid transfer agent is injected into the gas. 8007070 - 20 - Engine according to claim 6, characterized in that the gas is compressed by means of a rotating press pump. Engine according to claim 6, characterized in that the cylinder is a double-acting cylinder, the working space (P) being located on one side of the piston, while a compression space (C) is located on the other side of this piston located, which compression space has an inlet (127) for the working gas and an outlet (120). Engine according to claim 6, characterized in that the engine operates in a four-stroke cycle, which comprises an input stroke and a working gas compression stroke. Mot'-T according to any one of claims 1 to 9, characterized in that the injection part is an atomizer which is the transfer agent. can spray in order to improve the heat transfer to the gas. Motor according to any one of claims 1 to 10, characterized in that the heat exchanger (H) has one or more tubes for receiving the heat transfer agent, as well as a burner (B) for heating this agent in the tube or tubes, one and the other such that this agent is kept in the liquid state. 12. Engine as claimed in claim 11, characterized in that the working gas is flammable or can support combustion, the outlet of the cylinder being connected to the burner to supply the exhaust gas to the burner. Engine according to claim 12, characterized by a drop (T) connected to the outlet of the cylinder to recover liquid heat transfer agent from the wet exhaust gas. 14. Motor according to any one of claims 11..13, characterized in that the heat exchanger comprises a tube in the form of an inner coil (62) and an outer coil (63) coaxial therewith, the burner being so within the inner coil is arranged that the hot combustion gas from the burner must flow within the inner coil and then between the inner and outer coil. Motor according to any one of claims 1..14, characterized in that the compression ratio is at least 2 ': 1. Engine according to any one of claims 1 ..15., Characterized in that the piston and / or cylinder consists at least partly of a heat insulation material such as plastic, fiber-reinforced synthetic resin, wood or ceramic. 8007070 f -. » - 21 - Engine according to any one of claims 1..16, characterized by return means for returning the discharged heat transfer means to the heat exchanger. Motor according to claims 17 and 11, characterized in that the return means comprise a spray chamber (S), which comprises an inlet for the heat transfer agent and an inlet for the combustion gases, which are connected to the heat exchanger, which chamber a sprayer for spraying liquid transfer agent through the combustion gas of the burner, in order to preheat this medium 10, which chamber is further provided with an outlet which can carry the heat transfer agent to the heat exchanger, and with an exhaust for combustion gas . 19. Engine according to any one of claims 1..18, characterized in that the injection part is a cam-operated exhaust valve. Motor according to any one of claims 1..19, characterized by speed control means for controlling the speed of rotation of the motor by controlling the contents of the injected transfer gear. Motor according to claim 20, characterized in that the speed control comprises a variable displacement pump. Motor according to any one of claims 1..19, characterized by speed control means for controlling the speed of rotation of the motor by controlling the temperature of the injected transfer means. Motor according to any one of claims 1..22, characterized in that the cylinder and / or the piston are designed such that part of the liquid transfer agent remains in the working space after the transfer agent has been discharged. 30 2 * f. Engine according to claim 23, characterized in that the cylinder and / or the piston are provided with a recess for holding the liquid transfer agent. 25. A method of operating a reciprocating external combustion engine with a cylinder and a piston defining a working space, comprising introducing a working gas into the working space, causing the gas to expand in a expansion stroke of the piston to drive the piston, and discharge of gas from the working space near the end of this expansion stroke, characterized in that energy is transferred to the working gas 8007070 - 22 - from a heated liquid heat transfer agent, and further that this heated transfer agent is generated outside the cylinder under a pressure such that this agent remains liquid while injecting the heated liquid transfer agent into the working medium before or after introduction, in order to increase the internal energy of the increase gas. 26. Process according to claim 25, characterized in that the transfer agent is water, oil, natrim or a mixture thereof. Method according to claim 25 or 26, characterized in that the working gas is compressed before the heated liquid transfer agent is injected into the gas. 28. A method according to any one of claims 25.2? » characterized in that the heated liquid transfer agent is injected into the working gas in the working space. A method according to any one of claims 25 · 27, characterized in that the heated liquid transfer agent is injected into the working gas in a mixing chamber before the gas is introduced into the working space. 50. A method according to any one of claims 25, characterized in that it is carried out under such conditions of temperature and pressure that at least part of the injected transfer agent evaporates upon injection. A method according to any one of claims 25 · 30, comprising the. characterized in that the temperature and pressure of the wet exhaust gas 25 are such that at least substantially all of the transfer agent is discharged in the liquid form. 32. A method according to any one of claims 25-31, characterized in that the working gas is a flammable gas or a combustion-supporting gas. A method according to claim 32, characterized in that the heat exchanger comprises a burner, and that the exhaust gas is fed to the burner for burning therein. Method according to any one of claims 25 - 33, characterized in that the heated liquid transfer agent has a temperature and a pressure above or below the critical point, but higher than the boiling point at the ambient pressure. A method according to any one of claims 25.3, characterized in that the transfer agent is water and reclaimed waste water is returned to the engine, heat being supplied to the 8007070 -23 agent by means of a fuel -air burner, while losses in the circulated water are supplemented by condensation from the combustion gas of the burner. 36. Assembly of components for converting an internal combustion engine 5 into an external combustion engine according to claim 1, characterized by a heat exchanger and a fuel-air burner for heating pressurized water through an insulated cylinder with piston, which cylinder is provided with an inlet for gas and an outlet for wet exhaust gas, by a pressure pump for supplying gas into the cylinder, by a pressure pump for injecting liquid water under pressure into the cylinder, by a metering means for controlling the amount of injected water, and through a container for storing recycled water · 8007070