Aiming at reduction of the energy consumed in domestic and business use, research of an energy system corresponding to ZEB/ZEH (Net Zero Energy Building/House) is advanced. The authors are developing a hybrid heat source Stirling engine CHP (combined heat and power) system, which uses solar and woody biomass. This paper describes a basic solar Stirling engine power generation system only with solar energy. The system has a solar tracking type collector which is made by a Fresnel lens. The authors tried to improve performance of the system by design of a heat receiving part which is made by a copper plate and twelve bars, because a heater of the Stirling engine is not enough heated by sunlight. In addition, thermal conductivity analysis of the designed heat receiving part and the heater is conducted. As a result, temperature distribution is obtained.

We are designing and manufacturing a new α⁺-type engine that is considered about higher buffer pressure. Note that the α⁺-type mechanism is suitable for low-temperature-difference Stirling engines and the α⁺-type engine has a displacer consisting of two pistons that are connected via rods. Therefore, it is possible to use a regenerator with a sufficiently large area within a small range of temperature difference and to suppress the load applied to the crankshaft. We also develop a new design method suitable for low temperature difference engine. The α⁺-type engine is most effectively applied to power generation using a combustion heat from a wood biomass because the engine can be driven by indirect heating using 300 deg C thermal oil. We report the design of prototype new 10 kW class engine that reduces volume of 1/2.

When The space development becomes indispensable in thinking about the human future. The purpose of the space development is development of the human being society and research of the origin of the human. In NASA (National Aeronautics and Space Administration), JAXA (Japan Aerospace eXploration Agency) and domestic and foreign private enterprises, the space development of the 21st century to aim at the moon and a planet of the deep space becomes popular. In such a space development, a space rocket having strong driving force and a stable high-power electrical generator are important.

An outline about nuclear reactor promotion rocket and RTG (Radioisotope Thermoelectric Generator) are introduced here. In addition, Kilopower and ASRG (Advanced Stirling Radioisotope Generator) are considered as a development example of the electrical generators corresponding to the space utilization of the Stirling engine.

Stirling engines are able to utilize various heat sources, such as solar energy, exhaust gas, geothermal energy, and so on. However, the temperature level of renewable energy will be lower than conventional fossil fuel heat sources. Therefore, the conventional heat exchanger and regenerator may be not optimumed for using renewable energy heat sources. In this study, characteristics of a 1-kW Stirling engine (α-type) for the renewable energy were measured. The operating conditions of temperature and pressure were lower than those using fossil fuel energy sources. Also, two kinds of wire screens and new type matrix material for regenerator were tested to select the suitable matrix material for the operating conditions

This paper shows a new regenerator which is called active-type regenerator for practical use. Then also fundamental operating characteristic of a Stirling cycle machine using an Active-type regenerator are presented. Then technical points for these practical uses are arranged. We designed and developed an active type regenerator which is using polyurethane foam matrix and copper matrix as a heat storage material. Then, the availability of that was evaluated by an experiment. The authors have designed and developed an Active-type regenerator for small size Stirling cycle machine. This paper presents some thermodynamic characteristics shown by PV analysis and experiments on a Stirling cycle machine with an active-type regenerator made of copper matrixes and nylon or urethane matrixes. These results demonstrate that the active-type regenerator is one of the promising candidates as a high efficiency regenerator for the Stirling cycle machine.

The author made clear in the previous report that the minimization of entropy generation can be used to optimize Stirling engine parameters. In this report the effects of compression ratio, temperature ratio of heat source and sink and specific heat ratio of working gas on entropy generation are examined. In addition to these parameters engine speed and heater/cooler capacity are changed to obtain entropy generation due to heat transfer, mixing of gas with different temperatures and flow resistance. Entropy generation was evaluated in values of that per net work at the maximum power against engine speed. It has a minimum when heater/cooler capacity and compression ratio are changed. The compression ratio where entropy generation per net work takes the minimum increases with temperature ratio with different slope.The range of compression ratio where entropy generation per net work is not so large as the minimum is wide when the temperature ratio is large and specific heat ratio is small.

It is transformation of translational oscillation to rotation motion by a crank and a flywheel that is deeply involved in the operation of heat engines. Thermoacoustic engines, however, have only employed a linear alternator to extract power from the engine. In this study, we designed and built a thermoacoustic engine consisting of a looped tube and a flywheel. Successful operation of the engine is reported based on measurements of displacement oscillation of the piston and pressure oscillation of the gas pressure

The critical temperature ratio of self-excited oscillation heat driven cooler that consists of prime mover unit with wet regenerator, cooler unit with dry regenerator and liquid piston was calculated. The critical temperature ratio of prime mover was calculated for the target temperature of the cooler unit. Furthermore, the calculation results were compared under the condition that the regenerators were dry or wet at prime mover unit. Under the condition which the target temperature ratio of cooler unit was set to 0.92, the critical temperature ratio of dry regenerator was 1.55. On the other hand, the critical temperature ratio of wet regenerator was 1.14.

A thermoacoustic engine model with heat exchangers is introduced to show how a product of heat transfer coefficient h and heat transfer area of heat exchanger A determines the output power of the engine. Effective hA values are determined from experiments and calculation in a thermoacoustic engine prototype. The experimental and calculation results are compared with the favorable hA values estimated in the model.

The objective of this study is to verify how much the fluid mixture in the narrow tube such as He-Ar mixture is able to be separated using the acoustic vibration (the sound wave) in each tube diameter or sound frequency. To verify the separation of the He-Ar mixture, it was enclosed in the 4.8 mm narrow and 4.1 m long tube, and the 80.3 Hz and about 1.5 kPa sound wave was propagated in the tube. Helium quantity at the entrance of the narrow tube decreased and Helium quantity at the exit increased logarithmically. Hammering test was used to measure mixture ratio and the error was about 2.4%.

Temperature distribution of thermoacoustic engine core was evaluated by heat transfer analysis using finite difference method coupled with pressure / velocity amplitude calculation based on linear thermoacoustic theory. For the calculation, two channel widths and three displacement amplitude were set up. From the temperature distribution, it is confirmed that temperature difference of both edges of regenerator decreases according to the increase of displacement amplitude. On the other hand, heat flux density at plate surface increased and its variation region extended with increasing displacement amplitude. As a result, variation region of local Nusselt number of heat exchanger was kept within displacement amplitude. However, there was also dependence of Nusselt number on non-dimensional values related to boundary layer thickness.

Since 1987 Sumitomo Heavy Industries, Ltd. (SHI) has been developing Stirling cryocooler (STC) and Joule Thomson cryocoolers for onboard satellites which have a limited power capacity and space. Thus, the cryocooler for this purpose is required to have a low power consumption (high efficiency), a compact size and a light weight. Also, high reliability is required since the cryocooler must continuously operate in space for more than 10 years without trouble. A single stage STC has been developed by SHI that have been installed for the observation sensors and heat shield cooling such as the Earth Observation Satellite “Sikisai”, the Scientific Satellite “Suzaku”, “Kaguya”, “Akatsuki”, “Hitomi” [1], has a weight of 4.1 to 4.5 Kg and a cooling capacity of 2.2 W at 77 K with a maximum electrical input power of 50 W. However, when it is necessary to increase the cooling capacity due to the increase in the heat generation amount of the device, this cryocooler cannot be dealt with adequately. In this report, by improving the motor efficiency of the compressor, the maximum electrical input power was doubled (about 100 W) without greatly changing the size of the compressor, and the cooling performance was increased thus the efficiency was improved. In addition, a pulse tube expander was manufactured with the aim of reducing vibrations to the object to be cooled, connected to a high-efficiency compressor, and the cooling performance was measured.