Kuniya Watanabe

New solar Stirling engine TNT-1 with direct internal radiation heating

A unique 1 kW solar Stirling engine called TNT-1 (for Tohoku Gakuin Univ., Nihon Univ., and Tohoku Electric Power), utilizing N. Isshikis (1984) internal solar heating method and two solar concentrator dishes, is under test as a prototype for future large-scale solar engine systems. The Stirling engine has a transparent cylinder head made of quartz glass, and the solar beam concentrated by the solar dish heats up internal meshes installed on the displacer directly from the outside through the glass. As a result the engine can have a very simple heater with small dead volume and with enough heating surface, using wire mesh only, to provide high efficiency and low cost. One solar dish is a very accurate parabolic concentrator consisting of 180 small, accurate glass mirrors; the other consists of 40 simple spherical mirrors composed of plastic plates.<<ETX>>

Study on Pneumatic Wave Power Conversion System with Water Valve Rectifier

We experimentally and theoretically studied the energy conversion characteristics on a new type of wave power conversion system with water valves. The hydraulic model experiment was performed in regular waves using a nozzle as a dummy load with some parameters of submerged depth of the water valve, nozzle ratio, height of incident wave and wave period. It was proved from the experimental results that the efficiency of the water valve is equal to or higher than that of such a mechanical valve as conventional flap valves, that the influences of wave period and load change to the new system is less than to the conventional oscillating water column type wave power converter. In addition, it was confirmed that the water valve was effective as a safety system.

Kilowatt-Range Optical System for Driving the Solar Stirling Engine

The Cassegranian-type optical system for driving the solar Stirling engine consisted of a parabolic mirror with a diameter (D) of 3.2m and a hyperbolic mirror with a D of 600mm. The parabolic mirror was of the segmental-type which consisted of 180 ellipsoidal mirrors made from glass plates, and the hyperbolic mirror was made from Al plate. The Stirling engine was developed by Isshiki et al in order to convert solar heat energy into electric power. For driving this Stirling engine, the cylinder head was directly heated by the sun rays converged by this optical system, and the temperature of the cylinder increased up to 700 /spl deg/C. Finally, the engine produced an output power of about 1kW.

Kilowatt-range optical system for driving the solar Stirling engine

The optical systei for driving the solar Stirling engine with an output power in the kW range is described. This systei was of the Cassegranian-type and consisted of a parabolic iirror (diaieter 0 2. f/D 30 f: focal length) and a hyperbolic irror (0 . f/D 26). The parabolic airror was co. posed of 181 segiental iirrors . ade fro. glass plates and the hyperbolic iirror was iade fro. Al plate. The Stirling engine was developed by Isshiki et al. The input power of sun rays converged by the optical syste. ranged fro. 3. 0 to 3. 2kW and the output power of this engine was about 1kW. Fig. 1 The optical systea for the kW-range Fig. 2 A section of the Stirling engine. 1.

ENERGY LOSS OF AIR FLOW DUE TO WATER-VALVE SYSTEM

Energy loss of air flow due to water-valve which will be utilized in a wave-power-generation system is experimentally studied. Conclusions are; 1) the difference between steady and unsteady flow is not recognized; 2) flow loses its energy by two factors; one is threshold pressure head which is equivalent to submerged depth of vertical pipe and the other blowing out of air into water; and 3) the loss by later one is proportional to the 0.5 power of velocity in case of low velocity and to the 1.6 power in case of high.