Basic Study on Development of Stirling Engine for Small Portable Generator. 1st Report. Engine Design, Manufacturing, and Performance.

Abstract

A small gamma-type Stirling engine was developed as a prime mover of a portable generator set. The engine target performance is 100W output power and 20% net thermal efficiency at 1000 rpm. Special bayonet-type heat exchangers whose inner tubes move inside of the outer tubes, were applied for the engine's heater and cooler. An annular regenerator was located in a displacer piston. The displacer piston had both of the heating and cooling inner tubes for the working gas which flows to and from outer tubes. The outer tubes for heating were located at the top of the expansion cylinder and the outer tubes for cooling were located in the middle of the cylinder. For a piston drive mechanism, a Scotch-yoke mechanism which was useful to realize the small-size engine without any lubricating device, was adopted. In this paper, the design methed using an adiabatic model which can treat several thermal and hydraulic losses, and a nodal model, SETMA, are introduced. The analysis results are compared with the experimental data to show the availability of the arranged design method. Also, the performance of the compact bayonet-type heat exchangers are briefly discussed.