Research of an energy system corresponding to ZEH (Zero Energy House) is advanced so as to aim at reduction of the energy consumed in domestic use. 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 development of a 200W Stirling engine generator driven by solar energy using a solar collector made by a Fresnel lens. It has an α (2-piston) type structure operated by a Scotch yoke mechanism and now is made experimentally.

抄録全体を表示

For enhancement of heat recovery at the heater part of Stirling engine, we made a prototype Stirling engine of 3.7kw maximum output, with large size heat exchanger, large bore and stroke opposed piston, and semi-circulating flow system by lead valves and manifold at the heater side. Then, the semi-circulating flow effect is measured by the prototype and wooden biomass combustion. Although the manifold and lead valves are small, simple, low dead volume and low cost, temperature efficiency of heater part enhanced 5/3 times compared with the ordinary reciprocating flow Stirling engine.

抄録全体を表示

A thermoacoustic electric generator is a device for power conversion from heat into electricity. The device typically consists of a thermoacoustic engine and a linear alternator. Linear alternator has a high efficiency, whereas it has an inherent disadvantage in upscaling. Therefore, De Blok et al. proposed using bi-directional turbines. Referring to studies on wave power conversion, we designed and manufactured an impulse turbine and connected it to a generator. We measured acoustic field induced by a speaker, rotational speed of turbine, and generated electric power. As a result, the conversion efficiency from acoustic power into shaft power was estimated to be 12%.

抄録全体を表示

Using audio speaker with thermoacoustic engine, we can get electricity from heat. This type of thermoacoustic devices are called thermoacoustic electric generator. In this paper, the character of an audio speaker is studied and the calculation model for the numerical calculation is made. The calculation of the multi-stage looped tube thermoacoustic electric generator using the audio speaker is performed and the performance is estimated.

抄録全体を表示

We have developed a thermoacoustic electric generator consisting of a looped tube thermoacoustic engine and a voice coil type generator in place of an acoustic resonator. On the basis of measurements of the acoustic impedances of the looped tube engine and the generator, we modified the electric generator to make their acoustic impedances to become the same as each other. The thermoacoustic electric generator thus constructed oscillates at the frequency much lower than that expected from the engine size.

抄録全体を表示

A thermoacoustic refrigerator is the apparatus in which an acoustic wave contributes to the heat pumping. A conventional thermoacoustic refrigerator consists of a resonance tube, a stack, and two heat exchangers. To improve the limitation of performance of this refrigerator, a multistage thermoacoustic refrigerator is proposed and numerically analyzed in this work. It was found that there is a possibility that the proposed thermoacoustic refrigerator can realize the lower temperature and higher efficiency composed with the conventional one

抄録全体を表示

In recent years, many efforts have been made to improve the efficiency of an electric vehicle. To improve the efficiency of an electric bus, Sumitomo Electric Industries, Ltd. has been developing a superconducting motor system. This project is intended to demonstrate that the efficiency of an electric bus can be improved by a superconducting motor system. In order to be competitive with a conventional motor, a highly efficient cryocooler is required. Thus, Sumitomo Heavy Industries, Ltd. developed a high-efficiency Stirling cryocooler for the purpose of cooling an HTS superconducting motor system. A prototype unit was developed and performance tests were conducted. The conceptual design of the system and the detailed experiment results will be reported in this paper.

抄録全体を表示

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" and "liquid piston", different from the inertance tube. The effect of the new shifter on the refrigerator performance is examined analytically and experimentally using experimental model pulse tube refrigerator.

抄録全体を表示

The oscillating heat pipe (OHP) has attracted attention due to its high efficient transportation. We aim to enhance heat transport performance of this attracting device by adding vibration. Our experimental apparatus is made of OHP and Vibrator. OHP is mainly made of glass tube for visualization and it has 5 turns. We measured effective thermal conductivity of OHP in case adding vibration or not. As a result, we could enhance OHP's heat transport performance by adding vibration and the effective thermal conductivity was 1.03kW/m-K at the maximum (in case adding stronger vibration).

抄録全体を表示

Recently, a new, compact Gifford-McMahon (GM) cryocooler for cooling superconducting single photon detectors (SSPD) has been developed at Sumitomo Heavy Industries, Ltd. (SHI). The objective is to reduce the total height of the expander by 33% relative to the existing RDK-101 GM expander and to reduce the total volume of the compressor unit by 50% relative to the existing CNA-11 compressor. In addition, considering the targeted cooling application, we set the design temperature targets of the first and the second stages to 1 W and 20 mW of heat load at 60 K and 2.3 K, respectively. Although optimization of the internal components is one way to miniaturize the volume of the compressor unit, major design changes are required because the volume of the adsorber and the oil separator is almost the same as the volume of the compressor capsule. Thus, one approach is to develop a non-lubricated compressor, such as a valved linear compressor. An experimental unit of a valved linear compressor was designed and built, and preliminary experiments were conducted. Under no-load condition, a low temperature of 2.17 K has been achieved. With 1 W and 16 mW heat load, the temperature is 49 K at the first stage and 2.3 K at the second stage, with an input power of about 0.9 KW. The detailed experimental results will be discussed in this paper.

抄録全体を表示

According to Ceperley's calculation, if acoustic impedance z at the position of the regenerator is equal to p_mc (p_m: mean density in tube, c: adiabatic sound speed), the efficiency is limited to 10% of Carnot efficiency due to viscous losses in the regenerator. Higher efficiency is possible with higher impedance, e.g., if z = 10p_mc, reaches 79% of Carnot efficiency. In this study, we changed z at regenerator and measured thermal efficiency at regenerator positions. From the results, maximum thermal efficiency achieved 61.7 % of Carnot efficiency when z =10p_mc.

抄録全体を表示

The onset temperature of the thermoacoustic engine is required to bring down in respect of utilizing waste heat. Tsuda reported that the onset temperature is 343K when water vapor exist in the thermoacoustic engine. However it does not investigate the influence that adding water vapor gives in the temperature distribution in the stack of the thermoacoustic engine. In this study, we measured the temperature distribution in the stack of the thermoacoustic engine having wet stack after drive was starting and stable. The result of this experiment indicates that the temperature distribution in the wet stack becomes the curve of the convex.

抄録全体を表示

The optimization of heat transfer area in the regenerator is performed using the concept of enthalpy flow, which is commonly used in thermo-acoustic devices. When the hydraulic diameter is large i.e. heat transfer is low in the regenerator, enthalpy flow from the heat source to the heat sink is not negligible and it requires more heat exchange in the heater and the cooler. This enthalpy flow approaches zero but flow loss increases, as hydraulic diameter becomes small. We propose the optimum condition to be the enthalpy flow at the end of the regenerator 40% of indicated work. Cooperating with the maximization of output power and highest thermal efficiency, the optimization of not only hydraulic diameter but also cross sectional area of the regenerator was performed.

抄録全体を表示

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.

抄録全体を表示

Because the Stirling engine has a low load following capability, it is difficult to use as a power, such as a car. In order to use the Stirling engine as the power of the car, it is necessary to not load control of the time lag in the continuously variable transmission. Continuously variable transmission to devise in this study occur without the time lag required minimum of low gear effect, depending on the load applied to the tire. Therefore, the engine takes only a certain following load, it can be extracted efficiently power. Although the Stirling engine requires a large flywheel in order to maintain the rotation, it is possible to reduce the flywheel to the limit by not loading the control of the time lag, it is possible to reduce the size and weight of the vehicle.

抄録全体を表示

From viewpoints of energy saving and environmental problem, we have developed marine waste hear recovery systems used Stirling engine generators. The engine system keeps safety operation with an engine speed control system by an inverter. On the other hand, when the system has unexpected condition, such as interception of electric load or a trip of the inverter, the engine needs to stop speedy and safety, because the over speed of the engine may bring destruction of the engine mechanism or electrical fires. In this paper, we discuss shutdown methods for a Stirling engine generator, and show test results of a 500 W class Stirling engine generator to investigate effects of shutdown method with connecting pipe between the working space and the buffer space.

抄録全体を表示

The Performance of model co-generation system for greenhouse was estimated and evaluated assuming a strawberry farmer of Nasu district in Japan. The application evaluation of a model co-generation for greenhouse with CO_2 fertilization was performed using our previous experimental data. As a result, it was found that it is possible to supply heat, electricity and CO_2 required for a greenhouse without the concentration of harmful gases exceeding guidelines for man by ventilating with the flowrate of 692m^3/h. Finally, we estimated the costs of the cogeneration system for 1 month. But it was high because the wood pellets were more expensive that the heavy fuel oil.

抄録全体を表示

Aiming at reduction of the energy consumed in domestic use, research of an energy system corresponding to ZEH (Zero Energy 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 basic characteristics of a solar tracking type collector made by a Fresnel lens. The test results of a basic solar collector with a rectangular concentrating area were presented, and here new test results of an improved solar collector with a circular concentrating area are reported. The latter are improved in an absorbed heat efficiency.

抄録全体を表示

The purpose of this study was to understand the basic combustion characteristics of a wood pellet gasified combustor using secondary air swirl flow. The secondary air swirl flow can increase enthalpy and temperature in secondary combustion chamber because it enhances the mixing of air and combustible gas and it improves the combustion state. Two types of air injection holes (slit, circle) were examined. As a result of this experiment, it was revealed that the enthalpy and temperature were higher than that of previous experiment because its combustion state was improved by secondary air swirl flow.

抄録全体を表示

As a power source for local electric supply in developing countries, Stirling engine has received keen interest due to its high thermal efficiency and fuel diversity. In this study, characteristics of a metal knit burner, which gives a non-swirl-type tubular flame, have been investigated and compared with those of a swirl-type tubular flame burner. Results show that in a case of heating a simple cylindrical head, the metal knit burner has superior performance due to its radiative heat transfer from the heated metal knit surface and increased convective heat transfer rate though a thinner thermal boundary layer caused by normal attack of the burned gas on the surface. However, in a case of heating a cylindrical head with fins of the present Stirling engine, the swirl-type tubular flame burner has a higher maximum thermal efficiency of 10% against 7% of the metal knit burner for the electric power generation.

抄録全体を表示