WO2014209247A1

WO2014209247A1 - A method and system for a thermodynamic power cycle

Info

Publication number: WO2014209247A1
Application number: PCT/TR2014/000229
Authority: WO
Inventors: Mehmet Terziakin
Original assignee: Mehmet Terziakin
Priority date: 2013-06-25
Filing date: 2014-06-23
Publication date: 2014-12-31
Also published as: TR201618096T1

Abstract

A method and a system are presented for achieving the continuous heating of the working gas in the isochoric manner and the continuous cooling of the gas in the isobaric manner in a heat engine. This heat engine performs three thermodynamic processes at the same time as follows gas heating, cooling and expanding processes. The gas heating method is provided with: temporarily storing of the gas within a gas transfer chamber (8 or 9), continuously heating a portion of the gas within a heating chamber (6), replacing of the gasses between the heating and the transfer chambers. The cooling system comprises of two gas transfer chambers, one middle heat exchanger, a cooling heat exchanger.

Description

DESCRIPTION

A METHOD AND SYSTEM FOR A THERMODYNAMIC POWER CYCLE

TECHNICAL FIELD

This invention relates to a method and system of a thermodynamic power cycle employing gas as the working fluid for converting heat into power.

BACKGROUND ART

Reversible power cycles such as Carnot and Stirling cycles are the most efficient power generation methods from heat in theory. Theories of these cycles are known for almost two centuries. For example Stirling cycle was invented in 1816. Efficiency of the idealized Stirling and Carnot cycles are equal and this efficiency is a function of the temperatures of the heat source and the cold sink. Where the Work=W, Ql= Heat Inlet, Tl Temperature of the Heat Source and T2 Temperature of the cold sink the efficiency of the idealized Stirling or Carnot Cycle is:

E = W / Q1 = 1 - T2/T1

The idealized Stirling cycle comprises of 4 thermodynamic process steps. These steps:

1- Isothermal compression of the gas.

2- Isochoric heating of the gas.

3- Isothermal expansion of the gas.

4- Isochoric cooling of the gas and returning to the conditions at the beginning.

Until the date many cylinder and piston arrangements, heat exchanger combinations etc. were investigated in order to obtain a realistic implementation approach to the idealized cycle. A number of different Stirling engines were designed namely such as alpha, beta and gamma types for 200 years. In recent years, Stirling engines are drawing attention as a measure to recover exhaust heat from an internal combustion engine mounted in a vehicle, such as a passenger car, a bus, a truck, etc., or exhaust heat from a factory. The Stirling engine can be expected to achieve high heat efficiency. Furthermore, since the Stirling engine is an external combustion engine in which working fluid is heated from outside, the Stirling engine also has an advantage of being able to utilize practically any heat source available, that is, being able to utilize varieties of low-temperature-difference alternative energy forms, such as solar heat, terrestrial heat, exhaust heat, etc., and of contributing to energy conservation. However implementations of the real Stirling engines are unsuccessful and there is a gap between experimental results of the real Stirling engines and the calculated values of the idealized Stirling cycle. The most important problem here is inefficiencies of the heating and cooling processes of the working gas which are far away from the idealized cycle.

In real Stirling engines heating and cooling periods of the working gas are completely dependent on timing of movements of the pistons. For example for a Stirling engine running at 3000 rev/min rotational speed, all of four thermodynamic process steps should be completed within a few miliseconds! As the heating and cooling processes are realized while the gas passing from one cylinder to the other one it is obvious that heating or cooling the working gas from outside requires a sufficient of time and some certain conditions for the efficient heat transfer such as sufficient heat transfer interface area. In small engines such as miniature ones the mass of the working gas is al so very little and so that the gas can be heated and cooled somehow while passing between the compression and expansion cylinders. But real power plants are expected to generate much higher power rates and such systems should contain much more gas as the working fluid so that heating and cooling processes of the Stirling engines require much longer time intervals. Increasing power in Stirling engines decreases speed and increases volume, weight and cost of the engine. Because of this reason Stirling engines are mostly produced as miniature size engines.

An article of Institute of Reciprocating Engines of University of Karlsruhe outlines the problems as follows: " The ideal Stirling cycle requires discontinuous movements of the piston and displ acer. In reality, however, a perfect realization of this process is not possible. In most cases, a number of deviations must be accepted which reduce both efficiency and power density. The most apparent differences result from the use of continuous instead of (impractical) discontinuous volume changes (e.g. by use of a crank shaft drive) and the heat transfer using external heaters and coolers instead of the working space surfaces. The latter modification is necessary because of the lack of surface area and time for heat transfer in reciprocating piston engines. On the whole, this leads to rather adiabatic than isothermal processes inside the engine cylinders. " In total, these deviations actually lead to a process which is significantly different from the ideal process.

Above paragraph outlines main problems by regarding of the exiting Stirling engine at the date. Indeed it is not needed discontinues movement of the pistons or the shaft in order to provide sufficient time for heating and cooling of the working gas. In reality it is needed to provide enough time and suitable heat transfer conditions for efficiently heating and cooling the working gas. On the other hand it is not realistic to expect isothermal compression and expansion processes in real engines.

Lenoir cycle is another power cycle having high efficiency potential in theory but had not successful implementations up to date. It was patented in 1860 by J. J. E. Lenoir. At first it was implemented as an internal combustion engine type before Otto engine. It was thought that Lenoir cycle is applied as early internal combustion engines produced with commercial purposes. Lenoir cycle is more simple than the Stirling cycle due to there is not a gas compression process. The absence of any compression process in the design leads to lower thermal efficiency than the more well known Otto cycle and Diesel cycle. Lenoir cycle could not compete with the Otto and Diesel cycles emerged in the following years. Since Otto and Diesel cycles have air compression process before the combustion step they offer higher efficiencies than that of the Lenoir cycle in internal combustion engines. It is known that first implementations of the Lenoir cycle were done in late of the 19. century. Commercial production of this engine type was leaved in early of the 20. century. Lenoir cycle comprises of three steps following each other in each cycle. The cycle comprises of the steps as follows:

1) Isochoric heating of the gas within a constant volume in order to increase the absolute pressure in proportionally to the absolute temperature.

2) Isentropic expansion of the gas until the pressure before the heating step.

3) Constant pressure heat rejection until the temperature at the beginning. Indeed Lenoir cycle is a external combustion engine in reality and involves same problems as that involved in the Stirling engine. The problem is how to heat the gas efficiently for a sufficient time within a closed volume while the gas circulating in the system continuously. According to currently known Stirling and Lenoir engines gas heating period can only be increased by decreasing engine speed or discontinuing running of the engine during heating process. But these are not realistic solutions and low engine speeds result in big, heavy and expensive engines achieving only slow speed and low power rates. Slowing engine speed is not an economically acceptable solution.

Similarly efficient cooling of the gas after expansion step has a critical importance for decreasing gas pressure and/or its specific volume in this step for obtaining high engine efficiencies. According to the currently known the Stirling and Lenoir engines the gas is cooled in the recuperator while the gas is passing from expansion cylinder. In the currently known Lenoir engine both of heating and cooling processes can be achieved in the very inefficient ways.

Nowadays efficiency of the energy conversion from heat into power has a vital importance. This is the key factor for a number of critical issues such as decreasing C02 emissions, stopping global warming, efficient consumption of the petrol and natural gas resources, economic energy generation from concentrated solar power. At the present time power can be generated from heat with much lower efficiencies than that of the theoretical efficiency limits. An engine type capable to generate power with efficiencies near theoretical limits will be a critical advancement for overcoming all these problems.

SUMMARY OF THE INVENTION:

This invention presents solutions for problems of the Lenoir engine. According to the invention first portion of the working gas is being heating and a second portion of the working gas is being expanded and a third portion of the working gas is being cooled at the same time. There is not gas compression process in this engine. As it is known compression and expansion processes are performed by employing a number of moving components. During compression and expansion processes substantial friction and heat losses are involved decreasing overall efficiency. This engine has less moving components and involves less frictional losses due to lack of the compression process.

This engine has also a significant thermodynamic advantage due to absence of the compression process. As it is known temperature rises during compression of gasses. In order to heat the gas after compression step temperature of the heat source should be much higher than that of the gas at the end of the compression. For example let's assume a gas is compressed from PI to P2 and its temperature increases from 300 K to 500 K. For heating this gas after the compression step a heat source is needed at a temperature much higher than 500 K. For example let's sa that we have gas at the 300 K and 30 bar conditions. If this gas is heated from 300 K to 500 K in the isochoric manner its pressure increases from 30 bar to 50 bar. In an engine without compression, expansion ratio of the gas and thus cycle efficiency will be lower than that of the engine having compression step. But in this engine residual heat of the gas after expansion step is completely utilizable for preheating the gas during isochoric heating. By this way the gas will be heated in the heating loop by using residual heat of the expanded gas thus net heat requirement from outside will be much lower and overall system efficiency will be increased substantially. Consequently this invention describes an engine having a simple structure and high efficiency as it will be explained in the following sections.

As this engine is an external combustion engine that can be run with any imaginable heat source providing sufficient heat inlet to the system at a suitable temperature. This engine can utilize varieties of available fuel types. Higher power conversion efficiency is expected in this engine due to realistic and applicable thermodynamic process steps. This engine will be much more compact, efficient, high speed and lightweight power generation system in comparison to existing engines.

DETAILED DESCRIPTION OF THE INVENTION:

In order to explain the invention with the reference to the accompanying drawings three figures are presented, in which:

FIG. 1 is the pressure-volume diagram of the idealized cycle; FIG. 2 shows a schematic embodiment of this engine and gas flows during the cooling process.

FIG. 3 shows the same schematic embodiment of this engine and gas flows during the expansion and gas heating processes.

FIG. 1 shows a pressure - volume diagram of an idealized cycle. In the diagram the line between 1-2 indicates isochoric heating of the gas as the first step of the cycle, 2-3 is the isentropic expansion of the gas as the second step of the cycle, 3-1 is the isobaric cooling of the gas. Details of this idealized cycle as follows:

1- 2 Isochoric Heating:

In the first step of the power cycle the gas is filled into a heating chamber and heated therein. So that the gas is heated in this constant volume in the isochoric manner. In this step, the volume remains constant as Voll = Vol2. Temperature increases from Tl to T2. At the end of this process the pressure is increased proportionally to the increase in absolute temperature. T2 / Tl = P2 / PI is the expression of the pressure increase. In this step, the gas is heated by- Q in - heat input provided from outside. This document will describe how to heat the gas within a closed and constant volume for a sufficient time in the following sections.

2 - 3 Isentropic Expansion: In this step the gas is expanded in the isentropic manner theoretically. During expansion isentropy of the gas remains constant as S3=S4. Other values are calculated according to the gas and conditions at the beginning of the step 2. The pressure reduces from P2 to P3 and the specific volume increases from Vol2 to Vol3. The work (W out) is extracted during expansion. As this cycle does not include a compression step this W out is equal to the W net of the cycle . In practice, due to inevitable friction and heat losses isentropic expansion cannot obtained in reality but the process can be regarded as polytrophic in most cases.

3 - 1 Isobaric Cooling: The gas is cooled isobarically from T3 temperature to Tl. During cooling step the pressure remains constant as P3 = PI. At the end of the step 3 the gas reaches the conditions of the beginning of step 1. The heat Q out is rejected from the gas. According to the present invention this rejected heat is used for the preheating of the gas in the step 1. A counter flow heat exchanger is employed to transfer of this rejected heat from this step into the heated gas in the isochoric cooling of step 1. In the present engine embodiment all of the three steps of the cycle are performed at the same time.

FIG. 2 shows how to perform all these thermodynamic processes at the same time according to the present invention. In this engine a portion of the working gas is heated in the isochoric manner continuously. This heating process is conducted in a heating chamber 6 containing pressurized gas and hot heat exchange surfaces. Unlike the Stirling engine in this engine the heating period of the working gas is not restricted by the timing of the piston movement or the shaft rotation. The amount of the gas in the heating chamber 6 is much more than that of the expanded gas amount in one thermodynamic cycle or one shaft rotation. At the same time another portion of the working gas is cooled in the cooling chamber in the isobaric manner. The gas stays in the cooling chamber 7 for a period much longer than that of one cycle or one shaft rotation. The amount of the gas in the cooling chamber 7 is much more than the gas amount expanded in one power cycle or one shaft rotation. Therefore both of the heating and cooling processes are achieved without timing restriction of the piston movement. In the meantime a third portion of the gas is expanded and power is generated.

In FIG. 2 and FIG. 3 two different operation steps of the same engine embodiment are shown schematically. FIG. 2 shows upward movement 10 of the expansion piston 5 and discharge 11 of expanded gas from the cylinder 4 and gas flows along the cooling loop 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25. FIG. 3 shows gas expansion 58 and power generation step of the same engine embodiment. Therefore FIG. 2 and FIG. 3 are schematic illustrations showing two different steps of the operation following each other in the same engine embodiment.

FIG. 2 is an illustration which is including basic elements of an engine embodiment according to the invention. This basic embodiment includes a heating chamber 6, a gas cooling chamber 7, two gas transfer chambers 8, 9 a gas expansion unit 4, 5 and three heat exchangers 15, 46, 51. In FIG. 2 a reciprocating piston 5 cylinder 4 assembly is shown as the gas expansion unit. But expansion of the gas can be achieved instead of the reciprocating piston cylinder assembly by employing another gas expansion means such as rotary piston arrangement. But reciprocating piston cylinder assemblies are widely used and also shown here.

FIG. 2 and FIG. 3 introduce a new concept "gas transfer chambers" 8, 9. There are two identical gas transfer chambers 8, 9 in these figures but numbers of these chambers can be more or less according to preferred embodiment. It should be noted that each of gas transfer chambers 8, 9 has four gas ports 29, 30, 31, 32 however same numerals are used for indicating ports having same function in each of these chambers 8, 9 for simplifying description and drawings. However 29A, 30A, 31 A, 32A indicate gas ports in the gas transfer chamber 8 and 29B, 30B, 3 IB, 32B indicate gas ports in the gas transfer chamber 9.

Each of these gas transfer chambers 8, 9 has four gas ports 29, 30, 31, 32 and four gas communications 25, 26, 27, 28 with the certain components of the system. It is to be noted herein these gas communications 25, 26, 27, 28 reach all of these gas transfer chambers 8,9 however gas valves in the ports 29, 30, 31, 32 are used to select which gas transfer chamber will be employed for which function according to the running order. Features and operation of these chambers and gas passages are described in greater detail herein below. Each of these gas transfer chambers 8, 9 has a first gas inlet port 25 and a first gas path 23, 24 for receiving the cooled gas coming from the cooling chamber 7. Each of these gas transfer chambers 8, 9 has a second gas port 30 and a second gas path 26 for carrying the gas from the gas transfer chamber 8, 9 to the expansion unit 4, 5. Each gas transfer chamber 8, 9 has a third a gas port 31 and a third gas path 27 for carrying the gas 43 from the transfer chamber to the cold gas inlet 36, 37 of the heating chamber 6. Each gas transfer chamber 8, 9 has a fourth port 32 and a fourth gas path 28 for receiving heated gas coming from the outlet 41 of the heating chamber 6. Each of these gas ports 29, 30, 31, 32 has a separate gas flow control means such as a shut off valve. These gas control means are used to allow the gas to flow along these gas conduits 25, 26, 27, 28 or not.

A gas circulation pump 35 or another gas actuating means forces the gas to flow from the gas transfer chamber 9 to inlet 36, 37 of the gas heating chamber 6. Three heat exchangers 15, 46, 51 are employed in the preferred embodiment shown in the figures. The first heat exchanger 46 is the hot heat exchanger which is employed for heating a portion of the working gas 39, 46 in the continuous manner. The second heat exchanger 51 is the cold heat exchanger which is used to cool another portion of the working gas in the continuous manner. The third heat exchanger 15 is the internal or middle heat exchanger and employed for heat recovery from the working gas 38, 39 after the expansion process. Waste heat from the gas 38, 39 undergoing the cooling process is recovered and used for pre-heating the gas undergoing the isochoric heating process via this middle heat exchanger 15.

As seen in FIG. 2 the expansion piston 5 moves in the upward direction 10 in the cylinder 4 and sweeps 1 1 the gas out of the cylinder. Before this step expansion process of the working gas was accomplished during downward movement of the piston 5 just before the upward movement seen in the figure, but expanded gas is still in the cylinder 4 and there is a residual heat in the gas. At the end of the expansion stroke the piston 5 transitions into an ascending stroke 10 and the working gas 11 is moved into the middle heat exchanger 13, 14, 15, 16 via cooling circuit 12 as seen in FIG. 2. There is an outlet valve above the cylinder 4 allowing the gas 11 to flow toward the cooling circuit 12 while the piston 5 moving upwardly 10 but this outlet valve is not shown to avoiding the figure getting too complicated. This outlet valve opens the gas connection 11, 12 between gas outlet of the cylinder 4 and inlet 13 of the middle heat exchanger 14, 15, 16 during the upward movement of the piston 5 and closes this gas passage 11, 12 during the downward movement of the same piston 5. A one way or check valve can be employed as this outlet valve so that the gas only allowed to flow in the direction 11, 12 from the cylinder 4 to the 14, 15, 16 middle heat exchanger.

The gas flows 11 from the cylinder and enters into the middle heat exchanger 13, 14, 15, 16. This heat exchanger 15 is shown inside the heating chamber 6 in the figures. But this heat exchanger 14, 15, 16 can be made as a separate component out of the heating chamber 6. The main principle is here to recover heat from the isobaric cooling process of the gas and to utilize this heat for pre-heating the gas undergoing the isochoric heating according to this invention. The gas 11 flows through the passage 12, 13 and enters into the inlet port 14 of the middle heat exchanger 15 and gradually passes toward the outlet port 16 of the middle heat exchanger. Along this flow 14, 15, 16 the gas rejects its residual heat outside via walls of the heat exchanger 15. Temperature of the gas inside the tube 15 gradually decreases until the end 16 of the middle heat exchanger. At the outer side of this heat exchanger 15 walls the gas 38, 39 is heated by the recovered heat of the cooled gas inside the tube 15. In the FIG.2 middle heat exchanger 15 is illustrated in the heating chamber 6 so that this recovered heat is utilized to pre-heat the gas 38, 39 inside this heating chamber 6.

The gas 38 undergoing the heating process in its lowest temperature in the inlet 37 of the heating chamber 6 and takes heat from the walls of heat exchangers 15 along its flow indicated by arrows 38, 39. Flow directions of the heated and cooled gasses are preferably opposite to each other. The cooled gas rejects its heat along its flow 14, 15, 16 and its temperature gradually decreases. The heated gas takes this heat along its flow path 38, 39 and its temperature gradually increases. Therefore residual heat in the gas in the cooling process is recovered and used to pre-heat the gas in the isochoric heating process. This arrangement works as a counter flow heat exchanger and serves to keep temperature difference high between the heated and cooled gases for the efficient heat recovery. The middle heat exchanger 14, 15, 16 is drawn as a helically coiled tube in the figures. But any other heat exchanger type can be implemented for this purpose. For example heat exchangers with finned tubes or plate type heat exchangers can be used for heat transfer between heated and cooled gasses. Or another heat exchange means can be used such as employing a heat transfer loop using another heat transfer medium such as a gas or liquid between cooled and heated gasses. The preferred embodiment is to use a counter flow heat exchanging means between heating and cooling gasses for accomplishing heat transfer as high as possible. Therefore net heat requirement of the system for heating the gas in isochoric manner will be decreased and overall system efficiency will be increased. For example we may assume that the temperature of the gas 23 is 700 K at the end of the expansion process this gas enters into 25 the internal heat exchanger 26 at 700 K and exits from outlet 27 at 330 K. We may assume that there is 30 K temperature difference between the gasses heated and cooled at the two sides of the heat exchanger walls. In this case the gas in the heating process can be preheated from 330 K to 670 K by pre-heating by recovering residual heat from the gas undergoing cooling process. This pre-heating will be accomplished without using a net heat energy intake from outside. After heat recovery step the cooled gas exits from outlet 16 of the middle heat exchanger and enters 17, 18, 19 into the cold heat exchanger 7 in order to be cooled therein as much as possible. A cooling fluid 53, 54 is circulated in the cold heat exchanger 7 for receiving heat from the working gas 20, 21. In these figures a helically coiled tube 50, 51, 52 is disposed in the cooling chamber as the cold heat exchanger but another heat exchanger type can be employed as cold heat exchanger in this embodiment such as shell and tube type heat exchanger etc. A cooling fluid, a liquid or gas is passed 50, 51, 52 along the heat exchanger for taking heat from the working gas. A proper cooling fluid such as sea water, fresh water or air can be used. The cooling fluid 53 enters inlet 50 of the cold heat exchanger and flows along the heat transfer walls 51 and exits 54 from outlet 52. This cold heat exchanger is preferably made as a counter flow heat exchanger. Cooled gas 20, 21 and cooling fluid 53, 54 flow opposite directions in order to keep temperature difference between two sides of the heat transfer walls 51 as high as possible. The gas exiting 22, 23 from the cooling chamber 7 is filled 23, 24, 25 into 55 one of the gas transfer chambers 8 according to a certain operation order. Functions of these gas transfer chambers will be described in details in the following sections.

Because of the isobaric manner of the cooling process, the pressure of the gas theoretically remains constant along the cooling loop 12, 13, 17, 23. But temperature gradually decreases at the gas along the cooling loop from inlet 12 to outlet 24. Temperature decrease along the cooling loop leads to increase in density of the gas during its cooling flow 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 along the cooling loop. This engine embodiment is designed so that the mass of the incoming gas 1 1 into the cooling loop 20 is equal to mass of the gas 24 leaving 55 the cooling loop in one piston 5 stroke 11. Therefore the specific volume of the incoming gas 23 to the cooling loop will be much more than the volume of the leaving gas from the cooling 11 circuit in one piston stroke 10. In other words density of the working gas gradually increases during its flow along the cooling loop 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 while its pressure remaining constant. For example we may assume that 2 It = 0,002 m3 gas 23 is discharged 1 1 at 600 K and 10 bar in each ascending stroke 10 of the expansion piston 5. This gas 11 enters into the cooling loop 12 in each discharge stroke 10, 1 1 of the expansion piston 5. At the same time same amount - mass- of the gas leaves outlet 24 of the cooling loop and enters 55 into one of the gas transfer chambers. In the cycle shown in FIG.2 the cooled gas is filled into the gas transfer chamber 8. The gas port 29A is in the open state and the incoming gas enters into the gas transfer chamber 8. If we assume temperature of the gas is still 10 bar but the temperature is 300 K at the outlet of the cooling loop it means that density of the gas increases two times along the cooling loop. Thereby 2 It gas enters into the cooling loop and 1 It gas flows out at the end of the cooling loop in each ascending stroke of the expansion piston.

While the gas 11 is being swept into the cooling loop 12 by the ascending stroke of the piston 5 much higher amount of the gas already exists along the cooling circuit 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 so that cooling process continues without any interruption. While the piston is sweeping gas 11 through 12 the cooling loop, newly incoming gas pushes existing gas ahead in the cooling path. Cooling loop contains much more gas than that of the discharged in one piston stroke. For example cooling loop may contain 100 time more gas than that of discharged 11 gas in one piston 10 stroke in order to provide sufficient cooling time for the gas along the cooling loop. In this case the incoming gas stays in the cooling loop for a cooling period as much as 100 piston stroke to be cooled efficiently. While the piston 5 is pushing the gas 11 into inlet 12 of the cooling loop, same amount of the gas 24 exits from outlet of the cold heat exchanger 7 and enters 55 into one of the gas transfer chambers 8. Temperature of the incoming gas 55 into the gas transfer chamber is near the temperature of the cooling fluid 53 due to sufficiently long cooling period. This cooling loop is a subsystem employed for isobaric cooling of the working gas and it can also be used in a Stirling engine. In this case the cooling loop is located between expansion and compression units.

This embodiment allows to employ much larger heat transfer surfaces, much longer cooling periods and thus much effective gas cooling processes than that of Stirling engines. This embodiment enables isobaric cooling of the gas between the inlet and outlet ports of the cooling loop. In practice a little pressure drop will occur inevitably due to flow resistances.

A critical inventive concept presented in this invention is the gas transfer chambers 8, 9 and their specific functions. These chambers play a series of key roles for heating and cooling the working gas in the continuous manner. Each of these transfer chambers plays a different function in each following cycle. In other words gas transfer chambers 8, 9 alter their functions in each following cycle according to a certain operation order. Gas connections 25, 26, 27, 28 and flow control members such as valves are controlled by a central control unit CPU in order to enable these transfer chambers 8, 9 to undertake one of these functions according to the running order. In each cycle each transfer chamber performs one of these functions. At the end of each cycle each chamber becomes ready for conducting the following function according to the running order. These will be described in detail in the following paragraphs.

At the end of the cooling loop the cooled gas 33 is filled 55 into one of the gas transfer chambers 8, 9. In the cycle shown in FIG. 2 gas transfer chamber 8 is employed for storing 55 the cooled gas. In the following step of the same cycle which is shown in FIG. 3 the gas in this transfer chamber 8 will be transferred into 36 the heating chamber 6 and the gas 41 in the heating chamber 6 will be passed to the same transfer chamber. In other words the gas in the transfer chamber 9 will be replaced with the heated gas 41 in the heating chamber 6. In FIG. 2 this gas replacement process is achieved between the gas transfer chamber 9 and the heating chamber 6. This gas transfer chamber 9 was filled with the cooled gas in the previously completed cycle. Each of these gas transfer chambers is employed for one of these functions as follows: 1) Storing of the cooled gas. 2) Replacement of the gases with the heating chamber containing heated and pressurized gas. 3) Feeding the expansion unit with this heated and pressurized gas.

In FIG. 2 there is a gas heating chamber 6 and two gas transfer chambers 8, 9. The gas heating chamber is a pressured vessel containing heated and pressured gas undergoing continuous heating process. There are two gas communications 27, 28 between the gas transfer chambers 8, 9 and the heating chamber 6. The first gas communication 27 is employed for carry the gas 43 from gas transfer chamber (9 in cycle shown in the FIG. 2) to the inlet port 37 of the heating chamber 6. The first gas communication 27 is able to receive gas from each of these gas transfer chambers 8, 9 and to carry 27, 35, 36 this gas to the inlet port 37 of the heating chamber (6). Gas flow paths between the first gas communication 27 and gas transfer chambers 8, 9 can be opened and closed by a series of valves 31. A flow forcing means 35 such as a circulation pump is disposed along this gas path 27, 36 for forcing the gas to flow from the transfer chamber 8, 9 to the inlet port 37 of the gas heating chamber 6. There is a second gas communication 28 between the gas transfer chambers 8, 9 and the heating chamber 6. The second gas communication 28 is employed to carry the heated gas from outlet port 41 of the heating chamber 6 into 44 the gas transfer chambers (9 in the cycle shown in FIG. 2). Gas ports 32 between the second gas communication 28 and gas transfer chambers 8, 9 can be opened and closed by the valves in the ports 32. A central control unit actuates these valves 32 for opening and closing ports 31, 32 between gas transfer chambers 8, 9 and these two gas communications 27, 28 according to the running order. Therefore these gas transfer chambers 8, 9 are employed for one of these functions as follows 1) storing the cooled gas 2) replacement of the gasses with the heating chamber 3) feeding the expansion unit with the heated and pressured gas. As described above cooled gas is filled into one of the gas transfer chambers in each cycle. In the cycle as shown in FIG. 2 the gas transfer chamber 8 is undertaking the function of storing the cooled gas. In the cycle shown in FIG. 2 gas transfer chamber 9 is employed for the gas replacement with the heating chamber. Gas ports 3 IB and 32B of the transfer chamber 9 are in the open state and gas ports 31 A and 32 A of the transfer chamber 8 are in the closed state.

Gas valves in the ports 31, 32 are controlled so that these transfer chambers 8, 9 are enable to conduct these functions according to this running order.. At the end of the step shown in FIG. 2 the gas transfer chamber 8 will be filled with the cold gas and the gas transfer chamber 9 will be filled with the hot and pressurized gas coming from the heating chamber.

FIG. 2 shows the gas transfer chamber 9 undertaking gas replacement process with the heating chamber 6. This gas transfer chamber 9 was filled with the cooled gas in the previously completed cycle. In FIG. 2 same cold gas storing process is shown for the gas transfer chamber 8 for the current cycle. After the cooled gas is charged into the gas transfer chamber inlet port conducting gas from cooling loop was closed and cold gas is kept inside the chamber. At that point the gas in the transfer chamber 9 was at a substantially lower temperature and pressure than that of the gas in the heating chamber 6.

The main principle here is to transfer the gas from transfer chamber 9 into the cold gas inlet 37 of the heating chamber 6 to be heated therein and to take heated gas from outlet 41 of the heating chamber instead and filling it into the transfer chamber 9. Therefore working gas can be heated along a sufficiently long heating period while other thermodynamic processes are performed at the same time unlike the Stirling engine. Before the gas replacement process, while gas conduits 27 and 28 between the gas transfer chamber and heating chamber are closed the gas in the transfer chamber 9 is at a substantially lower pressure and temperature than that of the gas in the heating chamber 6. The heating chamber 6 contains pressurized gas undergoing the isochoric heating process in the continuous manner. The volume of the heating chamber 6 is much larger than that of gas transfer chambers. For example we can say heating chamber contains gas at 900 K temperature and 30 bar pressure while the gas transfer chamber is containing gas at 300 K temperature and 10 bar pressure. It is to be noted here the system will be designed so that densities or specific volumes of the gases in the heating chamber 6 and the gas transfer chamber 9 are substantially closer to the each other before the gas replacement. Subsequently two gas communications 27, 28 between the heating chamber 6 and transfer chamber 9 are opened at the same time. Two valves in the two gas ports 31, 32 of the two gas conduits 27, 28 between the heating chamber 6 and gas transfer chambers 9 are opened together. These valves are shown inside the gas ports 31, 32 of the gas transfer chambers in the drawings but another gas flow control means can be employed.

After these gas conduits 27, 28 are opened pressure difference between the heating chamber 6 and the transfer chambers 9 is eliminated and pressures become equalized in two chambers 6, 9. Since the volume of the heating chamber 6 is much more than that of the transfer chamber 9, the pressure in the heating chamber 6 slightly decreases and the pressure in the transfer chamber 9 substantially increases so that both of the chambers 6, 9 reach a common pressure level. During this pressure equalization a certain amount of the gas passes from the heating chamber 6 to the transfer chamber 9.

After pressure levels of these chambers are equalized, replacement of the gasses between the heating chamber and the gas transfer chamber can be achieved without needing a gas compression process.

The cold gas from the transfer chamber 9 is forced to flow 27 to the inlet port 37 of the heating chamber 6 by a circulation pump 35 (or another flow forcing means). Newly incoming gas 38 into inlet port of the heating chamber gradually sweeps the existing gas in the chamber 6 ahead 38, 39, 40. As described above the heating chamber 6 contains much more gas than the amount of incoming gas 43 in one cycle. The gas in the heating chamber stays therein for a much longer period than that of one cycle and heated continuously. When the gas 43 of the transfer chamber passes 36 through inlet 37 of the heating chamber, the heated gas 40 at the outlet 41 of the heating chamber passes 44 through the transfer chamber 9 due to the pfessure difference provided by the circulation pump 35 or another flow forcing means. Thereby the cold gas in the transfer chamber 43 is replaced 44 by the hot gas in the heating chamber. Before the gas connections 27, 28 are opened between the transfer chamber 9 and the heating chamber 6 the gas in the heating chamber 6 was at the much higher pressure and temperature than that of the gas in the transfer chamber 9. But specific volume ( or density) of the gas in the heating chamber 4 and the specific volume of the gas in the transfer chamber(s) are equal or closer to equal in most cases before opening of these connections 27, 28, 31, 32. After replacement of the gasses transfer chamber 9 is filled with the gas 40 of the heating chamber having much higher temperature and pressure. In each cycle new cold gas 36 is added into the heating chamber 6 and heated gas 40 is taken out. Meantime the gas in the heated chamber is heated in the continuous manner. Heating of the gas increases internal pressure of the heating chamber 6. There is a heat inlet from the hot heating surfaces 15, 46 to the gas. On the other hand incoming cold gas to the heating chamber and outgoing hot gas from therein means a heat rejection from the heating chamber. This circumstance leads to decrease internal pressure of the heating chamber. In implementation of this embodiment the heating chamber 6 and heat exchangers 15, 46 should be so designed the incoming heat from outside ( via heat exchangers 15, 46 ) should be equal to outgoing energy due to incoming cold gas and outgoing hot gas during running of the system.

It should be noted that a gas separation means between hot and cold gasses in the transfer chamber 9 is provided preferably. By this way outgoing 43 and incoming gasses 44 from/ to the gas transfer chamber 9 are kept separated within the same volume by a displacer or piston in the chamber 9 and 8. In this case the a displacer separates the gas transfer chamber into two volumes. This displacer can be made as a piston moving axially in the cylinder. This displacer is moved axially within the cylinder for realizing this gas replacement process between the heating chamber and gas transfer chamber. In this embodiment gas passages 27 and 28 are located in two opposite sides of the cylinder by contrast of the FIG. 2 and FIG. 3. The displacer (not shown) is moved axially within the cylinder so that the cool gas in front of the displacer is swept 27 through inlet 36, 37 of the gas heating chamber and the heated gas passes from outlet port 40,41 of the heating chamber to the back side of the displacer. This gas separation means between outgoing 43 and incoming 44 gasses is not shown in the gas transfer chamber 9 but described. Separation of the outgoing/cold and incoming/hot gasses within the transfer chamber is critical for the system efficiency. In this embodiment a gas circulation pump 35 is not needed for gas replacement between the heating and gas transfer chambers. Each gas transfer chamber includes a displacer inside it equipped with an axial movement mechanism.

After the gas replacement between the transfer chamber 9 and the heating chamber 6 is completed and gas conduits 27, 28, 31, 32 are closed together while the transfer chamber is containing hot and pressurized gas. In the following cycle this heated and pressurized gas will be utilized in the expansion and energy generation process.

In this embodiment two heat exchangers 15, 46 are employed for heating the gas. The first one 15 is the middle heat exchanger which used for preheating the gas 38, 39 with the recovered heat obtained from the cooling circuit 14, 15, 16. The second heat exchanger 45, 46, 47 is employed to heat the gas as much as possible depending on heat source type and temperature. As it is known principles of the thermodynamics increasing temperature of the heat source increases overall system efficiency. For example a combustion process can be employed for heating the gas up to highest possible temperature. In this case a suitable fuel type such as coal or fuel oil or natural gas and combustion air can be introduced 48 into the heat exchanger 45 and combustion can be performed inside the hot heat exchanger 46. Therefore heat of the combustion passes through the heat exchanger walls 46 and utilized for heating the working gas 38, 39, 40 in the heating chamber 6. Heat exchange capacity 46 can be increased by using finned surfaces or finned tubes for increasing heat exchange area with the working gas. As another option a hot fluid coming from a heat source can be circulated 48, 49 from the hot heat exchanger 45, 46, 47. In this case the hot fluid enters 48 into inlet port 45 flows along the heat exchanger 45, 46, 47 rejects its heat through the heat exchanger walls 46 and exits 49 from the outlet port 47. For example a hot fluid coming from a nuclear reactor or solar energy system or geothermal heat source or another heat source can be circulated along the heat exchanger 45, 46, 47 for heating the working gas 38, 39, 40. In this case currently known fluid circulation equipments such circulation pumps, vanes, flow measurement and control members or the like are employed for hot fluid circulation and control system for providing heat income of the hot heat exchanger 46. Preferably flow directions of the heating fluid 45, 46, 47, 48, 49 and the gas being heated 38, 39, 40 are opposite to each other in order to keep temperature difference between two fluids as high as possible. Thereby two fluids ( heating fluid and heated gas) flows opposite directions and the heat exchanger 45, 46, 47 works as a counter flow heat exchanger.

It should be noted that only one gas transfer chamber 9 is shown during gas replacement with the heating chamber 6. According to the invention one or more gas transfer chambers can be employed for gas replacement with the heating chamber at the same time. If two gas transfer chamber are employed for gas replacement with the heating chamber at the same time gas replacement period increases two times. If one gas transfer chamber is employed for conducting gas replacement with the heating chamber gas replacement process must be completed within one thermodynamic cycle. The reason is that gas replacement process should be completed in each cycle and at least one gas transfer chamber should be ready for providing hot and pressurized gas for expansion process at the beginning of the new cycle. The gas heating subsystem comprises of the gas transfer chamber(s), the pressurized heating chamber and gas connections between them,

In each power cycle at least one gas transfer chamber undertakes the function of storing cooled gas coming from end of the cooling loop. In each power cycle at least one gas transfer chamber undertakes the function of replacement of the gases with the heating chamber. In each power cycle at least one gas transfer chamber undertakes the function of the feeding gas expansion process by delivering heated and pressured gas toward the expansion unit. In FIG. 2 and FIG. 3 there are two identical gas transfer chambers. The gas transfer chamber 8 is employed for the storing of the cooled gas along the first half the cycle while the piston 5 is ascending from lower dead point to the upper dead point. In the second half of the cycle as shown in FIG. 3 same gas transfer chamber 8 is employed for gas replacement with the heating chamber 6 while the piston is moving downward. Thereby same transfer chamber undertakes two functions within one cycle. This transfer chamber is filled with the heated and pressurized gas and becomes ready for delivering gas through the expansion unit at the end of the cycle. In the first half of the cycle shown in FIG. 2 the gas transfer chamber 9 undertakes gas replacement process with the heating chamber 6. In the second half of the cycle shown in FIG. 3 same gas transfer chamber 9 delivers heated and pressurized gas through the expansion unit. Thereby the transfer chamber 9 undertakes two functions within one engine cycle.

There are many different embodiments and running orders are possible according to this invention. For example a rotary piston can be implemented for gas expansion process instead of the reciprocating piston cylinder assembly shown in the figures.

This gas heating subsystem can also be applied in a engine including gas compression process. For example this gas heating subsystem can be applied in a Stirling engine and it will be a substantial advancement over the current Stirling engines.

As it can be understood from the drawings and the description this system enable to continue both cooling and heating processes without any interruption while gas expansion and energy generation processes are continuing.

Although the embodiment shown in these figures does not includes a gas compression process this gas heating and cooling embodiments are applicable in a thermodynamic power cycle containing a gas compression step. For example a Stirling type engine can be so arranged that the gas transfer chambers and gas heating chamber can be employed therein and continuous gas heating process can be achieved. Similarly the cooling loop shown in the figures can be applied in a Stirling engine.

FIG. 3 shows next operation step of the schematic engine embodiment shown in FIG. 2. In this step expansion piston moves downwardly and the gas is expanded for power generation. In the previous step the gas transfer chamber 9 was filled with the hot and pressurized gas coming from the heating chamber 4. In this step shown in FIG. 3 a gas conduit 26 between the gas transfer chamber 9 and the expansion cylinder is in the open state. The hot and pressurized gas in the transfer chamber 6 is allowed to flow 26, 58, 59 into the expansion cylinder. Pressure of the gas 58 pushes the piston downwardly. The reciprocating movement of the piston is converted into a rotational movement by a piston rod and crankshaft mechanism. This crankshaft mechanism is not shown but described since it is a widely known mechanism.

When the piston reaches the lower dead point the gas passage 26 is closed. The piston is pivoted to a piston rod and the piston rod is pivoted to a crankshaft so that piston and crankshaft mechanism is obtained in order to convert reciprocating movement into a rotational movement of the crankshaft. The crankshaft and piston rod and other details of the mechanism are not shown in the figures and described herein. Thereby the gas pressure 58 actuates the piston 5 downwardly along its travel from the highest dead point to the lowest dead point. When the piston start the ascending stroke the gas remaining in the cylinder is discharged through the cooling loop as illustrated in FIG. 2. At this point the gas in the transfer chamber 9 will be discharged and the gas passage 26 and port 30 will be closed.

Meanwhile the gas replacement process is accomplished between the gas transfer chamber 8 and the heating chamber 6. As described above paragraphs and shown in the FIG. 2 the gas transfer chamber 8 was filled with the cooled gas coming from the outlet port of the cooling loop 22, 23, 24, 25. In the step shown in FIG. 3 this cooled gas 43 is transferred 36 into inlet of the heating chamber to be heated therein. Instead of this gas 43 heated gas from the outlet port 41 of the heating chamber is passed to the gas transfer chamber 8.

This is the solution for the main problem the Stirling engine outlined in an article of Institute of Reciprocating Engines of University of Karlsruhe which is mentioned in the prior art section of this document.

" The ideal Stirling cycle requires discontinuous movements of the piston and displacer. In reality, however, a perfect realization of this process is not possible."

Indeed in order to provide sufficiently long heating period discontinuous movement is not needed. In the present invention all processes of the power cycle are accomplished in the continuous manner without sacrificing engine speed.

Since details of the gas transfer process between the gas heating chamber 6 and the gas transfer chamber 8, 9 were described in the preceding paragraphs same details will not be repeated herein. Before the gas replacement the transfer chamber 8 contains cooled gas at a certain temperature and pressure. After the gas replacement with the heating chamber is completed the gas transfer chamber contains gas at the much higher pressure and temperature.

Each gas transfer chamber sequentially undertakes the functions of;

1) Storing the cooled gas coming from end of the cooling loop

2) Replacing this cooled gas with the heated and pressurized gas in the heating chamber.

3) Delivering this heated and pressurized gas through the expansion unit.

In each cycle at least one gas transfer chamber is employed for one of these three functions. Each gas transfer chamber completes one of these functions and becomes ready for undertaking the following function. For example the gas transfer chamber 8 undertakes the function of storing the cooled gas. When the gas transfer chamber is filled with the cooled gas it becomes ready to undertake the following function of gas replacement process with the heating chamber. In FIG. 3 same gas transfer chamber 8 is shown while accomplishing gas replacement process with the heating chamber 6. In FIG. 2 the gas transfer chamber is shown while it is undertaking the gas replacement process with the heating chamber. After this gas replacement process is completed same gas transfer chamber becomes ready for the following function of delivering this heated and pressurized gas into the expansion unit. In FIG. 3 this gas transfer chamber 9 is illustrated while it is delivering pressurized gas into the expansion unit. Each power cycle of this engine embodiment comprises of two steps as illustrated in FIG. 2 and FIG. 3. After the step is completed as shown in FIG. 3 the gas transfer chamber 8 will undertake the function of delivering pressurized gas into the expansion piston via gas connection 26. At this time the gas transfer chamber 9 will be employed for the storing cooled gas coming from end of the cooling loop via gas connection 23, 24. Same numerals indicate the members undertaking same function in both gas transfer chamber. For example gas ports 29 exist in both gas transfer chambers and indicate the gas intake ports coming from end of the cooling loop 22, 23, 24, 25. The valves in the ports 29, 30, 31, 32 or another gas flow control means are employed which gas transfer chamber will be employed for which function. In the embodiment shown in FIG. 2 and FIG. 3 there are two gas transfer chambers (8,9). Another alternative engine embodiment (not shown but described here) includes three gas transfer chambers for achieving three functions in one cycle. In this embodiment the first gas transfer chamber can be employed for storing of the cooled gas coming from end of the cooling loop. The second transfer chamber can be employed for gas replacement with the heating chamber. The third one can be used for delivering heated and pressurized gas to the expansion unit. At the end of this cycle the first one will be filled with the cold gas and becomes ready for gas replacement with the heating chamber in the next cycle. The second one completed the gas replacement process with the heating chamber and will be filled with the heated and pressurized gas. This gas transfer chamber will be employed for delivering gas to the expansion unit in the next cycle. The third gas transfer chamber will be discharged and will become ready for storing cooled gas in the next cycle. Therefore gas transfer chambers changes their functions in this sequence and the engine continues to run in this order.

A central control unit (CCU) manages operation of the system. A series of sensors measure characteristics of the power cycle. Temperature, pressure, and flow rates of the working gas will be measured by these sensors located in suitable positions of the system. The central control unit measures output values of the sensors and determinates thermodynamic power cycle characteristics. Required power characteristics such as demanded power, torque, speed etc are submitted to the CCU. A number of other operation characteristics are measured from the environment such as cooling fluid temperature and flow rate or air temperature etc. The CCU evaluates these measurements and requirements and determines output characteristics such as valve timings, heating characteristics such as heat inlet of the system, temperature of the heat source and circulation pump characteristics etc.

In the exemplary embodiment shown in FIG. 2 and FIG. 3 three thermodynamic process are realized as follows; isobaric cooling, isochoric heating and gas expansion steps. But the main concepts of the present invention regarding with the heating and cooling processes are also applicable in a thermodynamic power cycle including the steps of; 1) compressing of the working gas 2) heating of the gas, 3) expansion of the gas, 4) cooling of the gas. In this case a gas compression process is applied between the cooling and heating steps. This embodiment will be an implementation of the Stirling cycle including gas transfer chambers. Such an embodiment will be a substantial advancement above the current Stirling Engine since essential problems such as insufficient heating and cooling problems will be solved.

In order to constitute a highly efficient, compact and high speed engine gas connections of the system should be rapidly opened and closed within milliseconds. Such a fast and accurate flow control can be best accomplished by employing cam actuated valves as used in current reciprocating engines.

All figures show an exemplary embodiment of the invention schematically. The invention is not restricted to the particular of the above embodiment, but may be carried out with various modifications and the like without departing from the gist of the invention.

Claims

Claims:

1. A method of power cycle comprising of heating, expanding and cooling steps of the working gas, the method of power cycle characterized in that:

employing at least one gas transfer chamber(s) (8,9), at least one gas heating chamber(s) (6), at least one gas cooling chamber(s) (7) and at least one gas expansion unit(s);

providing at least two gas connections (27,28) between each of the gas transfer chamber(s) (8,9) and the heating chamber(s) (6), at least one gas connection(s) (23, 24, 25) from the cooling chamber to the gas transfer chamber(s) and at least one gas connection(s) (26) from the gas transfer chamber(s) to the gas expansion unit(s) (4); heating and pressurizing the gas (38, 39 ,40) in the gas heating chamber (6) by transferring heat from hot heat exchange surfaces (15,46) to the gas;

opening (29) the gas connection (23, 24, 25) between the cooling chamber (7) and the gas transfer chamber, taking (23, 24, 25) a certain amount of the cooled gas from the cooling chamber (7) and filling (55) it into one of the gas transfer chamber(s) (8 or 9) and closing this gas port (29) so that a certain amount of the cooled gas is kept within the gas transfer chamber;

opening two gas connections (27,28) together between the gas transfer chamber(s) (8 or 9) and the heating chamber (6) and transferring the gas (43) from the transfer chamber (8 or 9) into the heating chamber (6) to be heated therein and transferring the heated gas (41) from the heating chamber (6) to the transfer chamber (8 or 9) so that the cooled gas in the transfer chamber is replaced with the heated and pressurized gas coming from the heating chamber and closing the gas connections (27,28) and keeping the heated and pressurized gas within the transfer chamber; opening the gas connection (26) from the transfer chamber to the gas expansion unit (4), allowing the gas to flow through the expansion unit and expanding the gas ( 8) therein for generating power therein; and

discharging (11 ) expanded gas from the expansion unit (4) through the cooling chamber to be cooled therein.

2. The method for generating power according to claim 1 characterized in that:

providing a gas heating chamber (6) having an internal volume much larger than that of the gas transfer chambers (8,9).

3. The method for generating power according to claim 1 characterized in that:

employing one of the gas transfer chambers for storing the cooled gas coming from the cooling chamber;

employing same gas transfer chamber for transferring cooled gas into (36) the gas heating chamber and taking heated and pressurized gas (41) from the heating chamber in the following cycle;

employing same gas transfer chamber for delivering pressurized gas to the gas expansion unit (4) in the following cycle.

4. The method for generating power according to claim 1 characterized in that: in each power cycle

one of the gas transfer chambers is employed for storing the gas coming from the cooling chamber;

one of the gas transfer chambers is employed for transferring the cooled gas (36) into the gas heating chamber (6) and taking heated and pressurized gas (41) from the heating chamber (6) to the same gas transfer chamber;

one of the gas transfer chambers is employed for delivering pressurized gas to the gas expansion unit (4) for power generation.

5. The method for generating power according to claim I characterized in that:

forcing means the gas in the transfer chamber (8 or 9) to flow into inlet (36) of the has heating chamber and the gas (41) in the outlet port of the heating chamber to flow into the same gas transfer chamber by employing a circulation pump (35)

6. The method for generating power according to claim 1 characterized in that:

employing an internal heat exchanger (14,15,16) for pre-heating the working gas flowing in the heating loop by using recovered heat from the gas flowing in the cooling loop.

7. The method for generating power according to claim 1 characterized in that:

separating internal volume of the each of the gas transfer chambers into two volumes in which the first volume contains gas to be to be passed through inlet port (36) the gas heating chamber and second volume contains heated gas coming from outlet port (41) of gas heating chamber.

8. The method for generating power according to claim 1 and claim 7 characterized in that:

employing a displacer inside each of the gas transfer chambers (8, 9) having a cylindrical internal volume for separating internal volume of the transfer chamber into two volumes in which the first volume containing gas to be flowed into the has heating chamber and second volume containing gas coming from the gas heating chamber;

moving the displacer axially within cylindrical gas transfer chamber and forcing the gas in front of the displacer to flow into inlet port of the heating chamber (36) and forcing the gas in the outlet port (41) of the heating chamber to flow into back side of the displacer.

9. A gas cooling system for a heat engine converting heat energy into power characterized in that;

at least one gas expansion unit (4, 5) expanding gas for power generation;

at least one middle heat exchanger (14, 15, 16) for recovering heat from the expanded gas;

a gas path allowing the gas to flow only in direction (11 , 12, 13) from the gas expansion unit (4,5) to the middle heat exchanger (14, 15, 16);

at least one gas cooling chamber (7) cooling heat exchanger (51) provided with a cooling fluid inlet (53) and outlet (54) and a gas path (17, 18, 19) carrying the gas only in direction from the middle heat exchanger (16) to the cooling heat exchanger; at least one gas transfer chamber (8, 9) for temporarily storing the cooled gas coming from the outlet port of the cooling chamber via a gas path (23, 24, 25).

10. The gas cooling system according to claim 9 characterized in that;

the gas cooling chamber (7) with internal volume larger than the internal volume of the gas transfer chamber(s) (8, 9).

11. The gas cooling system according to claim 9 characterized in that;

the middle heat exchanger (15) recovering heat from expanded gas and transferring this heat into the gas (38, 39) in the heating loop.

12. The gas cooling system according to claim 9 characterized in that;

a plurality of the identical gas transfer chambers (8, 9) so that each of the gas transfer chambers has ability to receive cooled gas from outlet (22) of the cooling Chamber (7) separately.

13. The gas cooling system according to claim 9 and claim 12 characterized in that;

each of the gas transfer chambers has an inlet port (29A, 29B) and an inlet valve for opening and closing gas path (24, 25) coming from the cooling chamber.

14. The gas cooling system according to claim 9 characterized in that;

the gas cooling system is an isobaric cooling system.