Preliminary investigation of a converted four-stroke diesel to alpha v-shaped stirling engine

Abstract

This study presents a preliminary investigation on a converted four-stroke diesel to an air charged V-shaped Alpha Stirling engine. The engine was manufactured with a total swept volume of 194 cc., volume compression ratio of 1.84, 90° phase angle and air as a working gas. The engine was designed to fulfill the requirements of hot end temperature up to 1000°C, cold end temperature of 20 to 30°C, charge pressure of minimum 1 bar or above and engine speed up to 1200 rpm. Design considerations of developing a simple and low cost Alpha-typed Stirling engine using major components of both commercial diesel engine and industrial mass production were discussed. Major modifications were done on the engine heater head design in order to cater for both natural gases and biomass fueled heating process as the external heat source. The net power output was estimated about 25 W at minimum charge pressure of 1 bar using Beale formula. The preliminary results show that the friction torque increases with the increase of engine speed. The minimum friction torque of 0.80 Nm was obtained at minimum speed of 300 rpm and the maximum friction torque obtained was approximately 1.30 Nm at the speed of 1200 rpm. The gas pressure inside the working cylinder also increases with the increase of engine speed and the maximum mean pressure obtained with the effect of engine speed and hot temperature was approximately 1.41 bar.