The forest area of Japan is almost equal to that of Sweden. However, the utilization of the wood biomass in Japan has not been advancing. By the soaring oil prices from last year, the wood pellet price has become almost equivalent to the kerosene price at the standard heat quantity. As a result, if the supply system of the wood pellet becomes systematic, the wood pellet stoves and boilers would be more widely used. In this study, effective utilization of waste heat in the pellet stove is noticed. The system generating the electric power from not only conventional space heating by the stove but also the waste heat is constructed. And, the possibility of generating the electric power has been investigated experimentally. The waste heat of the stove is utilized for driving of the Stirling engine generator and the hot water supply. The possibility of electric power generation using a wood pellet stove is verified.

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Development of small-scale power system based on the biomass gasification is under going. But because of so complicated system and high cost, the commercialization is not progressing as expected. Small-scale system which has high thermal efficiency and low cost is requested. So, in this study we develop small-scale power system, in which stirling engine power system is combined with biomass direct injection burner directly. In this system, wood powder is injected into the burner, which generates the heat needed to drive the stirling engine. We aim at high thermal efficiency and low cost of the biomass power system through this developmnet. In this paper, our field tests of the stirling engine is reported. Moreover, the demonstration plant of biomass direct burning stirling engine system is intrduced and typical results of the field test of the plant are reported.

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Heat exchanger performance, engine performance characteristics and emission characteristics were investigated by equipping a 1kW-class Stiring Engine with a premixed multi-nozzle combustor and flat-plate finned heat exchanger. The finned heat exchanger showed a uniform temperature distribution on fins and a high heat transfer. Improvement of the combustor is needed because while NO concentration was reduced to blow 50ppm, CO concentration is still higher than the target value, 100ppm. Compared to electric heating, ejected heat upon combustion heating increased due to the leakage of the burned gas through the gap between the engine cylinder and the thermal insulator.

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In this study, a 3kW class new Stirling engine generator, SERENUM05, was developed. The SERENUM05 engine has a high efficiency with compact dimensions and lightweight. As one of unique specifications of the SRENUM05 engine, four-piston double-acting mechanism with a Z-type crank for high power is introduced. A generator is set in the bottom space of the engine. And annular-shaped mesh sheets are used as the regenerator matrix to improve the engine performance. From the engine test results, the maximum generated power of 2,188W and the maximum generating efficiency of 22.7% were obtained.

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Engines the bore of which is much longer than the stroke have a potential of high performance engines because flow loss can be much reduced. To examine the possibility of heat transfer enhancement we visualized the flow in such situation. The hydrogen bubble method is used for the corresponding condition as 1MPa, 600K hydrogen gas. A pair of vortexes forms on the both side of channel. It, once weakened near the bottom dead center, is strong then by the flow coming along the displacer upper surface when the fluid is sucked into the channel.

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Ross-Yorke drive mechanism is composed by the crank disk, the T-type link, the support link and becomes the structure to work a piston using each connecting rod from the side P_h of the T-link expansion piston and the P_c of the side of the compression piston. In this report, it did and it investigated a simulation analysis by this Ross-Yorke drive mechanism about the estimation method in the phase angle and the estimation method of the piston stroke. Moreover, it investigates about transformation Ross-Yorke drive mechanism that a different piston stroke is gotten, too. As a result, we were able to propose the new equation of the experiment of the piston stroke and phase angle.

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A prototype of beta configuration small Stirling engines has been built for the development of small Stirling engines used in thermal engineering experiments for educational purposes. Though the engine has been designed to be heated by an alcohol lamp when used for educational purposes, it can also be heated by a gas burner if higher power and/or higher speeds are needed. Details on the engine design and some aspects of its performance as well as the difficulties to be overcome are reported.

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The first stage experimental results of two kinds of newly manufactured Stirling engine from the last academic year, which are using pin-fin array heat exchangers as components of heater and cooler, are presented in this paper. Stirling engines manufactured this time are, 1) a large size β type Stirling engine (150mm of bore diameter and 100mm stroke length, consisting of 1.7L single cylinder's displacement volume.) In order to demonstrate better effectiveness of pin-fin arrays heat exchanger, we increased the displacement volume as 15 times as lager than that of previous Stirling engines made in this laboratory. 2) an α type stirling engine using glass syringe as piston cylinder in order to decrease friction loss significantly. Also we use Ross-yoke mechanism. From the experimental results, both two engines output are about 1/4.8〜1/9.3 of designed values. In the concluding remark, some drastic improvement of these engines is required.

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A pulse tube cryocooler without moving parts in the expander has the advantage over a stirling cryocooler on low vibration and long life. So it is widely used for space crafts and HTS devices. Recently Fuji Electric Group has developed a pulse tube cryocooler with cooling capacity of 2.5W-class at 70K, based on our technologies of the Stirling cryocoolers for the space crafts. This paper describes the main performance and an improvement effect of the developed pulse tube cryocooler about low vibration.

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Stirlig cycle machines with rotary drive mechanisms have already been proposed which consist of rotating expansion and compression spaces and which are equipped with complicated installations controlling the working gas flowing to and fro between the machine units. This paper presents a new type of rotary drive mechanism for Stirling cycle machines superior to the conventional ones. The key innovation is the use of stationary expansion and compression spaces to allow coupling a rotor and vane installed on a housing. In the advantageous construction, the working space can be separated from one another. At the first onset, we attempt to apply the mechanism for the compressor of a St type pulse tube refrigerator. The result proves that the new type of the rotary drive mechanism has a potential applied to various Striling machines.

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Stirling engines are the composition of 2 pistons in 2 cylinders or 2 pistons in 1 cylinder except for a double acting type engine. Heater, regenerator and cooler are installed between 2 pistons. In the meantime, the pulse tube engine consists of 1 piston in 1 cylinder, pulse tube, heater, regenerator, cooler and 2^<nd> cooler. Therefore, the composition resembles the Stirling engine well. However, the composition of the engine is more simplified than the composition of the Stirling engine. And, the piston and cylinder are in a room temperature environment. So, the heat measure is unnecessary for sealing mechanisms such as a piston ring. In this paper, using the energy flow on the thermodynamics, the examination which develops the pulse tube engine based on the working principle of the pulse tube refrigerator is carried out. In order to investigate the basic characteristics of the pulse tube engine, an engine of simple composition, which used atmospheric pressure air in the working gas, has been manufactured. Effects of the orifice, bypass and inertance on shaft power are examined experimentally. As the result, the excellent effect of the inertance has been confirmed. The feasibility of the pulse tube engine has been verified thermodynamically and experimentally.

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Flow rate changes around the resonance tube outlet of the thermoacoustic sound wave generator are described. Both flow rates and stream functions based on axial velocity amplitude are employed for confirming the flow rate changes here. The optimum propeller positions for wind power generation with the flow in the thermoacoustic sound wave generator have been observed previously. It is confirmed that they are almost equal to those analyzed by flow rates and stream functions based on axial velocity amplitude.

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In this paper, we report the direct observation of the energy conversion in a narrow tube having a temperature gradient. A gas parcel in the tube was driven by an oscillating piston at 1.00Hz to assure good thermal contact with the tube wall. We measured the oscillations of pressure and velocity in the tube to determine the acoustic intensity in the tube. We observed the amplification of the acoustic intensity in the region having a positive temperature gradient. We derived specific volume oscillation of the gas parcel from the measured pressure and temperature. The increase of the acoustic intensity per unit length was in good agreement with the enclosed area in the plot of pressure versus specific volume. This represents that the amplification of the acoustic intensity results from the thermodynamic cycles experienced by the gas parcel.

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Numerical simulation of heat and fluid flow has been performed to analyze the generation of the self-excited oscillation in thermoacoustic phenomena. Transient one-dimensional equations of continuity, momentum and energy were solved utilizing the TVD scheme. A simple physical model is used for the numerical simulation. In this paper, we analyze the behavior of pressure in a tube. As a result, it was found that the initial oscillation is important for generating self-excited oscillation.

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This paper presents operating characteristics on a Stirling refrigerator with an active type regenerator. When the Stirling refrigerator with the regenerator in a displacer uses light and flexible matrixes, those matrixes reciprocate in the regenerator housing. This phenomenon changes the flow loss and the residual gas volume in the regenerator matrixes. Moreover, the variation of the matrix volume influences the cooling capacity. Then, we propose the active type regenerator that actually transforms the matrix according to the reciprocation of the displacer. The active type regenerator uses an urethane matrix that the swelling and compression are done by the matrix piston.

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The refrigerator using low-pressure air or nitrogen has wonderful features. Those are lightweight, low cost and easy maintenance. On the other hand, using low-pressure gas brings about the insufficiency of heat transfer to the gas from a heat exchanger. COP is decreased as a result. This paper proposes a heat exchanger with elasticity as a method of enhancing the heat transfer without increasing dead volume. When applying the method to a cold-cap type refrigerator using atmospheric pressure air, the performance improved sharply. The estimation method of the gas temperature ratio and the measurement is reported.

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The advanced two-stage stirling cooler has been developed for the cryogenic system of next space missions, SPICA, NeXT, ASTRO-G promoted by JAXA. In order to meet the cooling requirements of these missions, improvement of cooling performance and mechanical reliability is required based on the existing two-stage stirling cooler with cooling capacity 0.2W at 20K by power input 90W, which is operated on the infrared astronomical satellite AKARI (ASTRO-F) launched in 2006/2/22. This paper describes the cooling capacity evaluation test by simulating contamination of the working gas and mechanical attrition reduction by flat-spring-supported displacer for development of the advanced two-stage stirling cooler.

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Cryogenic cooling is useful to most detectors in astronomical and atmospheric observation for improving the sensitivity and reducing the background noise. Recently cryocoolers are often adopted as cooling devices. This paper describes a single stage Stirling cryocooler. It is designed, manufactured and tested for space borne mission. The typical cooling power is 2W at 80K with 50W input. The cooler on the X-ray telescope satellite "Suzaku" was launched July 2005. It is operating over 1 year without any trouble. On the other hand, a cooler achieved 50,000 hour operation in the lifetime test on the ground. Same type coolers will be launched on the lunar explorer and the Venus orbiter of Japan

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In this study, we examined performance and characteristics of regenerator composed of mesh sheet matrix with groove. This mesh sheet was designed based on the mesh sheet, M5 reported by the previous study. The dimensions of a groove were decided by considering coefficient of friction number, f, and Nusselt number, Nu_d, and porosity number, φ. The regenerator performance is related with the index number of f/Nu_d ratio so that performance should improve if fis smaller, and Nu_d is larger. There are proposed dimensions as the candidates. The first one has almost same φ number as that of M5. The second has the most suitable index number of f/Nu_d. By this experiment we examined the first one and called it M6. As a result, M6 had a bigger pressure loss than M5. But M6 has almost same indicated power and indicated efficiency as that of M5.

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Heat transfer during compression and expansion is particularly important in closed-cycle machines such as Stirling engines and pulse-tube refrigerators. It is important to know the temperature profile near the wall by which the heat transmission is determined. The early work measured temperature profile near the wall with a thin (3.8μm diameter) hot-wire censer. But, the measured temperature was affected by the supports of hot-wire censer. Therefore, the effects of supports calculated using control volume method. The parameter of the equation is only the angular frequency divided by the thermal diffusivity, and it is possible to correlate with this value. In the results, dimensionless temperature and the average temperature amplitude of the censer were estimated.

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We made a horizontally opposed (alpha-type) Stirling engine that operated at small temperature difference. The effects of regenerator and the effects of phase angle of both pistons on engine performance are discussed.

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This paper presents study on miniature Stirling engine. We made a single piston-type Stirling engine. This engine consist of 1 piston in 1 cylinder, heater, regenerator, and cooler. The effects of temperature difference and regenerator on Stirling engine performance are discussed.

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Recently, the development of the magnetic regenerator materials greatly contributes to improve the cryocooler in the 4K temperature territory. The specific heat of 2^<nd> regenerator materials so far used for the regenerator material decreases greatly comparing to that of He in the temperature area below 10K. So, most of regenerator of 4K cooler is composed of mixture of lead and magnetic materials because some magnetic materials have same order of specific heat as that of He temperature territory below 10K. We have estimated the 4K-GM cryocooler performance with several kinds of regenerators because of the cost reduction of the 4K-GM cryocooler and the efficiency improvement. An examination by the numerical analysis was done to grasp the characteristics of regenerator material of the 4K-GM cryocooler and to attempt future performance improvement. Numerical result of Pb diameter dependnce of cooling capacity has been compared with the experimental result. Cooling capacity has nearly same maximum value at about diameter 0.45mm both in the experiment and calculation.

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A new mechanism (we called "α^+ Type") is developed for the Low Temperature Difference Stirling Engine. Now we have completed a 10kW target power prototype model. It is for use of 300℃ heat source from recovering wasted heat and from biomass direct combustion. The AP1-10/250 engine has unique construction which has a displacer composed two pistons and power piston arranged at center of lower piston of displacer. This mechanism aims for decreasing flow friction of working gas, reducing piston forces and increasing regenerator efficiency. This paper describes the concept and the experimental results obtained by performance test. The engine performs 8640W/600rpm shaft power under heat source temperature of 279℃.

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A previous double-acting Stirling engine consists of four cylinders. It has compact engine size and high performance, because overall space in the engine is used effectively. However the engine needs complex and many mechanical parts in a piston drive mechanism, such as a swash plate mechanism. Then we are interested in the configurations of a unique double-acting Stirling engine that consists of two cylinders. In this paper, we discuss about characteristics of the unique engine and show outline of the engine performance with a prototype Stirling engine.

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When a freight ship is in a harbor, a Diesel engine generator is operated to supply electric energy in the ship. Exhaust gas from the Diesel engine causes air pollution in the harbor area. We have tried to develop a heat recovery system with a Stirling engine generator. This system is expected that the harbor area is kept clean, because the exhaust gas of the Diesel engine decreases in the area. In this paper, we report structure and performance of an experimental Stirling engine for the system. The engine has target power of 500W, and it can operate using heat source of 400 deg C.

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Exhaust gas from the Diesel engine on the ship causes air pollution in the harbor area. In order to have little environmental impact, we suggested a heat recovery system with a Stirling engine generator that used the exhaust gas. However, the gas flow is lower temperature compared with other high performance Stirling engines so an assessment and plans of heat exchanger is important part of the process of design. In this paper, we have tried to develop the system as well as evaluated the heat exchanger characterization.

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For the global environment protection, it is expected that the household co-generation systems that have high conversion efficiency, namely, high reduction rate in CO_2 emissions. Low installation volume and high net working rate suitable for the Japanese residences hold the key to the success of the household co-generation systems. In order to realize such systems, it is necessary to develop small-size and high-efficiency Stirling engines. Free piston Stirling engines with integrated linear alternators have the potential to realize compact size and high efficiency due to low mechanical loss. Aiming to develop a household co-generation system that achieves the conversion efficiency of 25% and the total efficiency of 90%, a free piston Stirling engine with an integrated linear alternator is being developed.

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In order to develop a household co-generation system, we need a compact and high efficient power source. A Stirling engine, which has excellent characteristics such as high ideal efficiency and low pollution, is one of the suitable power sources for the co-generation system. In this study, we aim to develop a high efficient Stirling engine. And a ceramics heat exchanger is developed. It has high heatproof performance and high heat conduction, then the Stirling engine can have higher operating temperature. We also develop a prototype Stirling engine for investigation of the ceramics heat exchanger. In this paper, we discuss a fundamental performance of the engine.

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Because free piston Stirling engines (FPSEs) have no mechanisms such as cranks and cams, high system efficiency can be expected compared with conventional engines. The output power of the working gas is directly utilized as a linear alternator input, and then converted into the electrical power. Therefore, in the case of the FPSE, linear alternator is one of the most important devices. In general, the airgap exists in two places of the inside and outside of the magnet ring in a moving-magnet type linear alternator. Because the airgap in a magnetic circuit causes most of the reluctance, it should be reduced as much as possible. A new type linear alternator that has only one airgap has been designed and developed. In this study, the performance evaluations of the linear alternator that has one-airgap were conducted.

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A new mechanism Stirling Engine (we called "α+Type") is now under developing, which has 1kW of target power by using 300℃ of heat source for recovering wasted heat. The AP1-1/250 engine has unique construction which has a displacer composed two pistons and power piston arranged at center of lower piston of displacer. This mechanism aims for decreasing flow friction of working gas, reducing piston forces and increasing Regenerator efficiency. This paper describes the experimental results obtained by performance test of test engine applied new crank for higher buffer pressure. Now, the engine performs 805W/700rpm shaft power under 600kPa buffer pressure.

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The authors have developed the 1kW class Stirling engine generator ASEG1000-I based on the SEG1000-AS/I, II and built a kerosene fueled co-generation system for home-use in cold regions. Investigations of a machine structure including crank mechanism, an electric generator and heat exchangers have been conducted in order to improve the performance of Stirling engine generator for practical use. The ASEG1000-I shows the electric power of 960W and the engine generator efficiency of 30% (electric power/heat absorbed into the engine). Also, as a result of comparison with competition systems, the developed system is able to save energy and decrease in an energy cost.

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