Heat transfer has been investigated on the end surface of cylinder enhanced by an annular jet from a channel installed in the displacer. The heat flux was estimated from heat generation in the foil heaters of which each temperature was controlled with CTA circuit individually. Conventionally, the heat exchanger capillary tube and so on are provided in order to increase the heat transfer in the compression and expansion process. However, by the introduction of the capillary tube the flow resistance is increased and the work is reduced. The purpose of this paper is to investigate experimentally the possibility of heat transfer enhancement by causing the proper flow to the high and low temperature space. In the Cylinder a displacer with the annular channel is placed. Annular jet is driven by reciprocating displacer. As a result, the heat transfer is enhanced when the displacer descents or stops near the bottom dead center. High heat transfer is restricted to stagnation region.

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As a power source for local electric supply in developing countries, Stirling engine has received keen interest due to its high thermal efficiency as well as its fuel diversity. In this study, a tubular flame burner has been developed for heating the head of a Stirling engine due to its advantage in shape. To enhance the thermal efficiency of electric power generation, a larger diameter burner with burned gas recirculation has been developed. Results show that stable combustion can be obtained for wider ranges in equivalence ratio and in heat input as compared with those of the previous burner. With a decrease of equivalence ratio, the head temperature, electric power generation and thermal efficiency are increased for a constant heat input, and a maximum thermal efficiency of 11.2 % has been attained.

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This study examined the basic combustion characteristics of a wood pellet gasified combustor using excess enthalpy method. The excess enthalpy was to make the heat recirculate through the fire grate from the downstream high temperature region to upstream low temperature region by inserting a high conductivity porous fire grate into the one-dimensional flame zone. Heating with excess enthalpy was simulated by heating inlet air with a heater in this experiment. As the result, the enthalpy of the exhaust gas in the case of inlet air heating was higher than the case without the heating even subtracting the enthalpy requiring to heat inlet air.

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Aiming at reduction of the energy consumed in domestic use and business use, research of an energy system corresponding to ZEB/ZEH (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 for a heat source and supplies power generation and warm water. This paper describes a design and control of a solar tracking type collector which is made by a Fresnel lens. Solar energy of 500〜550W is concentrated on a heater, so that the Sirling engine generator for performing characteristic examination as a basic system has a power generation output of 200W.

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The aim of this research is to create a Zero Energy House system using insolation. One method to run the system is by using the parabolic trough solar collector. This paper shows the specification and design of the equipment. This technology is made of a parabolic mirror for the collector. A copper pipe installed in the focus collects solar heat and water is used as heat transfer fluid. The trough type collector is available for Rankine cycle power generation systems, and also for a Stirling cycle engine operated by a low-grade heat source.

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In this study, the thermoacoustic prime mover using a quartz glass driven by sunlight was developed. The sunlight collected by the parabolic reflector was focused on the stack directly. Considering the balance between sunlight to heat conversion and flow resistance, various stacks that are different from materials and channel shapes were evaluated with temperature difference. The maximum temperature difference is achieved with the honeycomb ceramics stack.

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To reveal which is more suitable, smooth channel or metal gauze for the regenerator material, experimental study was conducted. To compare structures with the different dependencies of length scale and flow velocity both on flow resistance and heat transfer, we first looked for the condition where pressure drop along the regenerator is the same using a single smooth channel and metal gauze with three mesh size. We found that pressure drop for smooth channel is the same as that for #30 metal gauze at reciprocal frequency f=6.3Hz and #16 gauze at f=31.5Hz. We measured, indicated work and shaft work. Since there is a possibility that indicated work contains larger error due to the determination of phase, the shaft work for source temperature of 600℃ was used to draw the conclusion. The conclusion is that smooth channel is better structure of regenerator than metal gauze.

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A new method to measure heat transfer between the working gas and the regenerator matrix has been proposed in the previous work. Since the change in internal energy of working gas is calculated from its pressure and volume, heat added to the working gas can be estimated from the 1st law of thermodynamics with measured pressure history. Measurements were carried out for various combinations of changing the stroke, phase difference and frequency of the pistons. The results have been correlated in a dimensionless with three independent variables.

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We focus on the high-porosity characteristics of sintered metal fiber matrix for Stirling engine regenerator. In order to measure its basic characteristics as regenerator, we measured heat transfer characteristics and pressure drop in comparison with stacked wire-mesh matrix. From the measurement results, sintered metal fiber matrix shows lower flow resistance and either equaling or surpassing heat transfer performance than stacked wire-mesh matrix.

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A Stirling engine can be used in a waste heat recovery system of a marine Diesel engine. A heat exchanger of the Stirling engine is then designed taking into account exhaust gas characteristics and pressure loss in the mounted exhaust gas line. On the other hand, a gas engine emits exhaust gases without SO_x and soot, thus the design concept of the heat exchanger applied to the gas engine differs from that for the Diesel engine. In this paper, the authors present an initial discussion on the design and development of a waste heat recovery Stirling engine using exhaust gas from the marine gas engine as the heat source.

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From viewpoints of energy saving and environmental problem, we have developed marine waste hear recovery systems used Stirling engine generators. It is important to develop an engine speed control system for safety and effective operation for the systems, because it is difficult to control the temperature and the flow rate of the heat source for the waste heat recovery Stirling engine. In order to develop a high-performance engine speed control system, we have developed the Stirling engine simulator, which is constructed from an induction motor, an inverter and a programmable logic controller (PLC) installed an original program. In this paper, we show that the Stirling engine simulator can simulate characteristics of a Stirling engine with suitable parameters in the PLC. Also, the test results of the Stirling engine simulator are compared with that of a 500 W class Stirling engine. Then we discuss the effective value of the Stirling engine simulator when we develop the engine speed control system.

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KAIHO Engine is a new external combustion engine having following features; (1) Can use solid disposal biomass as the fuel directly, and all combustion gas generated can be used for heating the working gas(N_2), (2)Is consisted of pressure difference generator(PDG), power piston(PP), heater, regenerator, cooler, separated each other, connected by pipes. (3) The size of the heater, regenerator, cooler are not restricted. The operating principle of this engine is that PDG generates output and pressure difference between the heater and the cooler simultaneously. The pressure difference generated drives the power piston. The experiment was performed to prove the validity of the principle and to grasp the output performance of the engine. The former was proved, but the output was remained at 2kW, not able to reach the goal of 20kW. The reason the output remained short was found to be the shortage of the performances of the valve system as was reported at the last meeting. A new valve system was proposed and tested for the good results. A utility model of the valve system is under construction. Also, a new feature for the engine was proposed.

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For enhancement of heat recovery at the heater part of Stirling engine, we made a prototype Stirling engine of 7.5kw output, with four kinds of heat recovery enhancement method. Large size heat exchanger with large bore and stroke opposed piston, circulating flow system with lead valves and manifold, multi-stage heater, and working medium including condensable fluid. Through a simple modeling of 2-stage, circulating flow Stirling Engine with 10% partial pressure of H20 vapor, the heat recovery ratio on the heater part increases approx. 2.4 times, compare with single stage normal Stirling Engine.

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Dead volumes are necessarily involved in the working space of a Stirling engine, such as in its heater, regenerator, or cooler, etc. These volumes can cause substantial decreases in the indicated work produced by the working gases, resulting in low output of the engine. On the other hand, the volume variations of the working space, yielded by any piston driving mechanisms being used nowadays for the Stirling engines, are always different from the ideal ones, the "ideal volume variations" (or iVV for short), protecting it from obtaining the maximum indicated work available thermodynamically. The indicated work decreased by the dead volumes and the non-ideal volume variations was investigated analytically and shown in the p-v diagram with emphases being putted on the effects of dead volumes.

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A 2-cylinder opposite-positioned alpha-type Stirling engine for testing the heat exchangers, including the heater, cooler and regenerator, is being under construction. It is composed of two alpha-type Stirling engines with the two expansion cylinders and the two compression cylinders being respectively opposite-positioned on the same horizontal plane by using a master-and-slaves connecting rod set, resembling a radial engine with four cylinders. Such a configuration as well as the three external heat exchangers makes it convenient to replace and/or test any one or any combination of these heat exchangers on one hand, and on the other hand, avoiding the interference of various measuring instruments possibly used in the future.

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Concept of Lumped Mass Circular Traveling Wave Stirling System which was derived from thermoacoustic system and consists of lumped masses, springs (instead of resonance tube) and α-type Stirling System was introduced previously. And at the same time numerical simulation results have been reported. To prove practicability an experimental refrigerator system by that concept was composed and running test was started. In this report present state of the test and what have been known from that are shown.

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This paper presents a prototype electric-power control system for generation of electricity by free-piston type 1kW Stirling engine. Converter unit developed in our Laboratory can realize to start the Stirling engine softly with no stress and to keep it stable in normal state including battery and dynamic load in collaboration machine mechanism of the Stirling engine with control of output voltage and current of generator. The converters consist of an AC-DC boost converter for generation control of the Stirling engine, a DC-DC buck converter for charging or discharging batteries and an inverter for commercial power-supply. The proposed system can process and handle in the best condition in any states of the Stirling engine, dynamic load, batteries and external power supply.

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West proposed a looped Stirling engine with a liquid-column which the shape of is U. After this proposal, Martini worked the engine with 4 U-tubes, Li worked it with 3U-tubes. However, it's not clear that they undergo Stirling cycle and how the number of U-tubes affects the design. In this paper, we show that the engine of this type undergoes Stirling cycle, and the effect of the number of the U-tubes. By calculating the acoustic impedance in the middle of the gas-column theoretically, the possibility is showed that the engine undergoes Stirling cycle. And the number of the U-tubes can be changed by adjusting the length of gas-column or liquid-column to approach an acoustic impedance.

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A water Stirling engine has attracted attention because it can work without any moving parts and can use variety of heat sources. This device was composed of a tube containing a regenerator; the regenerator consisted of many narrow flow channels. We built a multistage water Stirling engine and measured the oscillation temperature and the pressure amplitude. The oscillation temperature is measured to be 47℃ at 28W . The pressure amplitude is measured to be 9.1kPa at 249W.

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The steam engine that is essentially same to the Pop-pop boat engine has been experimentally investigated. In this study, we measured P-V diagram and input power to the heater of some rotation speeds, and confirmed that output power was 4.0W and thermal efficiency was 1.3% under the conditions that rotation speed was 180rpm and the temperatures of heating and cooling sections were 200 and 70℃.

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This paper presents the application of The Particle Swarm Optimization (PSO) for the design of a thermoacoustic device. As a thermoacoustic device, a traveling wave thermoacoustic refrigerator with a branched tube is employed and the three parameters, regenerator's radius, position, and length, were optimized. The obtained results are compared with the results obtained without PSO method.

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A thermoacoustic electric generator is a device for converting heat into electric power via acoustic power. In this study, we have focused on the method to convert acoustic power into electric power and demonstrated the use of a bi-directional impulse turbine. We manufactured the impulse turbine and connected it to a motor. The turbine is located inside a stainless pipe equipping a speaker. Acoustic power from the speaker, rotational speed of the turbine and electric power from the motor were measured. As a result, the conversion efficiency from acoustic power into electric power was found to be 20%.

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In this paper, a pulse tube engine with a linear generator and a displacer with driving rod for using high temperature heat source to generate electricity power is discussed by numerical simulation. It is shown that there is an optimum displacer mass and rod diameter to get optimum efficiency at the condition of the linear motor on resonant condition which can be got by adjust the distance between the cylinder head and the piston head of the linear generator.

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We have constructed and tested a shell and tube heat exchanger with a dual speaker thermoacoustic device. We have tested a shell and tube heat exchanger by changing the phase between two speakers at both ends of the device. Five thermocouples are positioned within the regenerator and inlet and outlet water temperature were measured with two other thermocouples. Two pressure sensors are positioned each side of the device along the regenerator. We have measured the regenerator temperature and pressure at both sides of the regenerator with changing the mass flow rate of coolant water. The temperature distribution of regenerator and the acoustic power were gained from measured values.

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Pulse tube refrigerator does not have moving parts in the expander and thus have higher reliability. So, it has already been used practically as a cryocooler. The phase shifter in the cryocooler generally uses the inertance tube. In this study, we propose the new phase shifter, "elastic body", replaced with the inertance tube. The effect of the new shifter on the refrigerator performance, is examined analytically and experimentally using experimental model pulse tube refrigerator.

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For the purpose of cooling high-temperature superconductor (HTS) devices, such as superconducting motor, a high efficiency Stirling-type cryocooler has been developed by Sumitomo Heavy Industries, Ltd (SHI). The design concepts of cryocooler are high efficiency, compact size, light weight, and high reliability. We have developed a cryocooler with a design target of producing an efficiency COP of 0.07 at 70K and preliminary experiments were conducted. As the experimental results show, the cooling performance achieved a cooling capacity of 150 W at 70K, with a compressor input power 2.15kW, corresponding COP of 0.07 and a no heat load temperature of 36K an operating frequency of 47Hz,cooling water temperature of 30℃. The experimental results are reported in this paper.

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According to Ceperley's calculation, higher efficiency is possible with higher impedance, e.g., if z = 10ρm^c, η_2 reaches 79%. In order to achieve z = 10ρm^c, he explained the cross-sectional area of the enlarged tube would have to be 10 times larger than that of the input tube. On the other hand, losses caused by sudden expansions in regenerator was found. It can be reduced somewhat by installing a tapered tube between the two sections of straight tube. In this report, we changed the cross sectional area of the regenerator using tapered tube so it is larger than input tube, and measured its thermal efficiency and acoustic power gain at regenerator positions of a traveling wave heat engine.

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