A new type external combustion engine with 4 main cylinders, 1 auxiliary cylinder for heating and valves is proposed. The operation mechanism and the theoretical heat cycle of it resemble the Otto engine except the heat transfer process. By the function of valves, the engine basically separates the compression or expansion phase from the heat exchange phases. Therefore, the total volume of the pipes in the heat exchangers can be changed independently from the compression ratio of the engine. It makes the extension of heat transfer area easy, which leads to getting high power density and high thermal efficiency. Because precise structures are not required for the heat exchangers in this engine compared with the case of the Stirling engine, it is expected that pressure drops in it and the manufacturing cost of it become low.

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This study deals with the thermodynamic design of Stirling engines. Design parameters considered are rotating speed, porosity, phase angle, and tube or wire diameter, the free-flow area and the volume of heat exchangers. The optimum conditions are examined based on net cycle work obtained subtracting friction power loss estimated from existing correlations from indicated work calculated through nodal analysis neglecting flow loss. The optimum conditions for the free-flow area and the volume of the heater and the cooler are to maximize the net output power. That for the phase angle is to maximize cycle work. Those for other parameters are that the changing rate of output power or cycle work respect to the parameters satisfies respective condition. It is revealed that existing engines do not meet the condition very well.

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This study deals with the pressure drop along heat exchanger tube. Pressure drop between two gas reservoirs, a cylinder and a tank, was measured for frequencies 20-40Hz and different gases-air helium and argon, and at various pressure, 60-400kPa. The measured pressure waveform was discussed by separating it into the sine (corresponding to flow loss) component and the cosine (related to flow acceleration) component. The cosine component was several times as large as the sine component. The sine component is roughly correlated with the coefficient of resistance derived in steady flow. The cosine component is indicated to be proportional to the pressure difference to accelerate the fluid mass in the tube with a factor of about 3.

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A mathmatical calculation model for Stirling engines and coolers was developed and proposed. The particle method is applied to this model. This model considers that composition elements of engines, such as working fluid, pistons, wall and matrix, are a lump of small particles. Dominate equations are applied for each particle, and the movement of each particle are treated directly. The new model can evaluate the effect of complicated path shapes and flow patterns, for example, connecting between tubes and regenerator case. This issue is very useful for Stirling engine and cooler design. This paper introduces the theory and technique of the model and the caluculation results.

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For driving of multi parallel cylinders, so called barrel type as Daidoji, Aishin and Clucus Engines^<(1)(2)(3)> etc, there were many ways. But, we have found that, if Z crank is used, the driving ball's center moves up and down along the surface of small circular pillar. So, new piston driving mechanism using this fact is now under developments for less friction and simplicity.

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The characteristics of hydrogen internal combustion Stirling engine were analyzed by comparing the engine performances on steam injection and H2-O2 injection. The experiment results on the steam injection showed that the internal conversion efficiency and pressure ratio increased to comparable levels with H2-O2 injection. Simulations and estimations on the engine characteristics suggested that the performance improvement in the hydrogen internal combustion Stirling engine was caused by not only the temperature increase in the expansion space but also a large amount of condensation of steam and the evaporation at the regenerator.

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In National Aerospace Laboratory (NAL), a conceptual model of life support system was designed. This is a self-contained partially circulated life support system, called the SEPAL. The most significant feature of the SEPAL is that the system includes an energy supply subsystem. Based on the concept, energy supply subsystem using solar thermal energy as an energy source has been developed. This subsystem includes a Stirling engine generator. The prototype engines, called the NALSEM (NAL Stirling Engine Model) series, are semi-free-piston Stirling machines with a moving-magnet linear alternator. The NALSEM500 was designed to achieve thermodynamic efficiency of 30% or more with an indicated power of 500W. The design performance has been achievable to date. Based on this achievement, an improved Stirling engine generator, the NALSEM700,has been designed. This engine has an opposed-piston configuration to minimize mechanical vibration, and is expected to provide higher performance and stability than the NALSEM 500. This paper describes the significant design features and test results of the NALSEM700.

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A hermetic Stirling engine, which has a generator in a pressurized crankcase, is suitable for an application of a generator set. Because the hermetic engine does not have an external seal device between the working space and the atmosphere, and it has small mechanical loss. In this paper, the author reorganizes a 100 W class Stirling engine named "Ecoboy-SCM81" to the hermetic type. The original engine was developed at a RC127 committee of JSME in 1995,and it had a mechanical seal as the external seal device. And, the performance of the hermetic engine is measured for a comparison with that of the original engine. As the result, it is confirmed that the hermetic engine has very smaller mechanical loss and higher generator power than that of the original engine.

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One of the largest problems of a cogeneration system is the application to changing ratio of thermal and power demand. Stirling cycle is useful for a cogeneration system because it can convert a thermal energy to power and vise versa. The Stirling cycle is applied to a cogeneration system as a bottoming cycle. The performance of the proposed system is estimated with the characteristics of the topping cycle and heat transfer of heat exchangers. When a gasoline engine is chosen as a topping cycle, the maximum efficiency of power output and thermal output is 24.5% and 143%, respectively. Furthermore, the proposed system is useful because it can be applied to any kinds of topping cycles.

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Stirling engine is very attractive prime mover because of its inherent advantages such as high thermal efficiency, high applicability to use of many kinds of fuels or thermal energies, clean exhaust, low level of vibration and noise etc. But until now, the size of the engines developed are relatively small and the output maximum is 100kW at most. One major reason why few research about large-sized Stirling engine performed is, of course, there is no demand to apply the engine as a high output power plant. But it is very important to discuss about a large-sized Stirling engine for the engine development. So, we have studied mainly about the relation between the engine size and the compression ratio by using computer simulation. Results obtained as the limited area to be good relation for them and expected output.

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KUBOTA developed a Stirling heat pump system using dual input both shaft power and heat power. This system consists of an efficient gas engine and a heat-assisted Stirling heat pump constructed as two sets of three-cylinder machines, each a combination of two Stirling sub-systems; one a power producer and one a heat pump. This paper describes performance characteristics of the heat pump system and an approach to place it to practical usage. Since this Stirling heat pump is able to match with various heat balance, it is applicable for various driving sources such as a gas engine and a micro gas turbine. And the performances show that it will be an efficient engine driven freon-free heat pump system.

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The authors had developed a Stirling cooler and cooling unit (single Stirling cooling unit). In addtion, A double Stirling cooling unit installing two Stirling coolers has been developed to aim at increasing in the cooling capacity of unit. This paper presents a tandem type Stirling cooler which is built up by connecting two Stirling coolers with coupling the crank shafts directly. The cooling unit with the tandem type Stirling cooler is superior to the double Stirling cooling unit, because motor input decreases and buffer tank is not necessary. So the tandem Stirling cooler could be very useful to make refrigeration systems higher efficiency, more compact and cost down.

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This paper describes Stirling cooler which is intended to use in very high temperature area where usual air conditioner can not operate in. The Stirling engine presented here has curvature shape heat exchanger having pin fin arrays inside in them. The proposed cooler's style is "α" type Stirling cooler. The structure of Stirling cooler consists of an expansion piston, a cooler head with pin fin arrays heat exchanger, two regenerator matrix, a connecting pipe, a radiator head with pin fin array' heat exchanger inside in it, compression piston and a power supply motor. In conclusion, the study of Stirling cooler for high ambient temperature area is very important.

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This paper presents study of performance characteristics on a cylindrical cam type Stirling Refrigerator. When the 100W class Stirling Refrigerator was trial made until now and the operating performance characteristics Was investigated, mechanical loss occupied about 54%. In order to improve efficiency, it is necessary to press down mechanical loss low. Then, the cylindrical cam type Stirling Refrigerator equipped whit the oil lubricous mechanism was trial made, and performace evaluation was carried out. Consequently, net freezing capability improved and the value of COP improved because the motor input declined.

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In Stirlig cycle machines, the regenerator entrance area is usually smaller than the cross-sectional area of matrix and the pressure drop loss increases due to a nonuniform velocity distribution in the matrix. This study measured and analyzed the effect of the small distance gap between the entrance and the matrix end on the pressure drop. In addition, the velocity distribution of a working gas flow was observed by the flow visualization methods using a smoke-wire and a hydrogen bubbling. The results show that the gap extends considerably the flow to radial direction, makes the velocity distribution uniform and is effective in decreasing the pressure drop loss across the regenerator matrix.

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Performance of new matrix for Stirling engine regenerator is examined in this study. Mesh sheet is used as new matrix. The performance of mesh sheet is measured with an engine test stand and is evaluated in detail. Based on the measured pressure drop and regenerator loss date, friction coefficients and Nusselt numbers are arranged with Reynolds numbers. By using the mesh sheet, the engine output power and thermal efficiency are improved about 20%.

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It is writing to this paper about the operating characteristic of the hybrid reproduction machine carried in a stirling freezer. The matrix which mixed nylon with copper to the thermal storage material of a reproduction machine on the assumption that efficient-izing of a stirling freezer is used, and the fall of pressure loss is tried. Furthermore, pressure loss of a hybrid matrix is measured by experiment, and the possibility as a reproduction machine matrix is proved.

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Oscillatory flow heat transfer is an essential design factor for thermoacoustic refrigerator, especially in a stack of an acoustic refrigerator, regenerator in Stirling refrigerator and related heat exchangers. Aiming to have a design criterion for such oscillatory flow heat transfer system, experimental and analytical investigations were conducted using incompressible oscillating flow in tube. The mode of heat transfer was mainly classified into laminar and turbulent flow heat transfers. The boundary between laminar and turbulent flows was approximately given by Ohmi-Iguchi criterion. The space-cycle averaged heat transfer characteristics are well correlated using Nusselt number, Reynolds number, Strouhal number and Prandtl number for the respective heat transfer modes, similarly to forced convective heat transfer.

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As a point to do special mention in cryocooler development of late years, it is splendid of late years surpasses Stirling cryocooler. We developed the small size of efficiency Stirling type pulse tube cryocooler that cooling uses such as high-temperature superconductor and semiconductor sensor was turned into with a purpose. As demand specification from the device side to the cryocooler side, smaller light weight, the high efficiency, high reliability is sought for. For those demand specification, pulse tube cryocooler (WE-SP4000) made by DAIKIN needs to examine larger improvement. So we report it about the examination result because I analyzed it about a loss of WE-SP4000 model, and we did improve the efficiency more this time.

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In order to meet with the cooling power requirement around 130W at 165K, an U-shape pulse tube refrigerator was designed, fabricated and tested for the purpose of xenon gas re-condensation in a liquid xenon calorimeter. It will be used in the final calorimeter with 800L of liquid xenon inside. Because of relatively higher temperature operation, a simple-orifice configuration is applied for a phase shift. mechanism. The cooling performance was obtained under the same operating condition as the previously developed co-axial pulse tube refrigerator using 1.6kW GM compressor.

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A Pulse tube cryocooler of simple structure without moving part in the expander has the advantage over a stirling cryocooler of low vibration and long life. So its wide uses for space crafts and high-temperature superconductor devices are extended. Recently Fuji Electric has developed a pulse tube cryocooler with cooling capacity of 2.5W at 70K, based on the technology of the stirling cryocooler for the space crafts. The cryocooler consists of a compressor with two opposite pistons supported by flexure bearings and an in-line type pulse tube expander. This paper describes the structural features, typical performances and reliability of the new cryocooler.

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Cooling performance of pulse tube refrigerators was investigated in a temperature range from about 270K to 80K to apply cooling systems for a temperature range higher than the liquid nitrogen temperature. Helium and nitrogen were used as a working gas. It is found that performance of refrigerator with nitrogen is more influenced by the connecting tube between a hot end of pulse tube to a reservoir than that with helium, and pulse tube refrigerators that are deigned and optimized for helium didn't always work as refrigerators with high performance for nitrogen.

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Numerical simulation of viscous compressible flow in basic pulse tube refrigerator is conducted to make clear the working principle of refrigeration. Transient axisymmetric two-dimensional equations of continuity, momentum and energy were solved by means of TVD method. The physical model of the pulse tube with a regenerator is used for numerical simulation. Heat exchange between the pulse tube wall and the working gas in the pulse tube is assumed as a convective heat transfer. In this paper the transient behaviors of pressure and gas temperature, moving distances and temperature changes of gas elements in the pulse tube, and the effect on Surface Heat Pumping are analyzed.

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Over the past several years, much interest has been devoted to the study of thermoacoustic machines that have the simple construction and do not use the ozone depleting fluid. It is important to understand the thermoacoustics characteristics for developing thermoacoustic machines. This paper is concerned with analyzing the detailed behavior of thermoacoustic machines by using a numerical cycle simulation. Complete differential equations of continuity, momentum and energy of working gas, as well as energy of stack and heat exchanger walls are employed as the governing equations. The experimental results are also discussed to confirm its validity. In this report a typical thermoacoustic generator is adopted.

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In this work, we simultaneously measured the pressure and velocity oscillations in a U-tube of a water Stirling engine. We found that the energy conversion from heat flux to work flux is executed through the Stirling cycles and that the acoustic impedance responsible for the energy conversion is considerably higher than other thermoacoustic engines. We conclude a water Stirling engine can be a powerful device for applications such as a prime mover and a cooler having no mechanical parts.

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The pulse tube cryocooler is which doesn't need a moving parts in the expansion space and the advantage that said with improvement of reliability by low vibration is given. But it becomes difficult to predict performance of the cryocooler because there is not a piston when becomes the design method. In late years, analysis technique by Thermoacoustics theory has been developed as the tool which understood the pulse tube cryocooler at the overall. Moreover and, as a simple method, Matsubara likens gas in pulse tube to solid piston, and develops equivalent PV method calculating work in the expansion space. But, as pulse tube design tool, there are many points to be still not enough. So we select numerical calculation by 3rd Order as analysis technique to do design development of pulse tube cryocooler by this report, and report it because evaluation examined behavior of inside gas by a difference of the phase controller.

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When a steep temperature gradient is imposed on a regenerator contained in a looped tube by using two heat exchangers, acoustic waves are spontaneously generated as a result of the thermoacoustic energy conversions through the Stirling cycle. While the energy conversion in a conventional Stirling engine is performed by the carefully tuned pistons, a thermoacoustic Stirling engine does not have any mechanical parts to tune the acoustic wave responsible for the energy conversion. Thus, it is of great importance to study how the thermoacoustic engines perform energy conversions without moving parts. In this experiment, we focused on the phase angle between the pressure and velocity oscillations of gas parcels in a looped tube thermoacoustic engine. We demonstrate that the phase angle changes corresponding to the energy conversion process within the regenerator.

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