Design and performance study of an alpha V-type stirling engine converted from diesel engine

Abstract

The design of an alpha V-type Stirling engine converted from Yamaha fourstroke diesel engine was realized with few major modifications on the engine housing, heater head, swirl burner, regenerator, oil lubrication system, auxiliary cooler and flywheel. The methodology of developing a 25 W alpha V-type Stirling engine that is simple in design, low cost and multi-fuel potential due to its easy integration with external heat sources had been successfully established and it is proven practicable. The engine can be marked as a closed regenerative cycle engine that pioneers the research of high temperature differential (HTD) alpha V-type Stirling engine operating in self-pressurized mode using air as a working gas. The engine is featured with 90o phase angle, bore and stroke of 53 mm and 44 mm respectively, total swept volume of 194 cc., total dead volume of 115 cc., volume compression ratio of 2.2, 4 mm spherical bed regenerator and Liquefied Petroleum Gas (LPG) as fuel. At heat input of 1100 J/s, the engine performance was successfully tested. For mechanical shaft power assessment, torque, output-power and thermal efficiency variations were obtained at different engine speeds, hot and cold cylinder temperatures. The engine approximately produced a maximum brake power of 7 Watt, brake thermal efficiency of 0.6% at 717 rpm speed, 811oC hot cylinder temperature and 96oC cold cylinder temperature. For electrical power assessment, the engine is capable of generating a maximum electrical output power of 1.7 Watt, system thermal efficiency of 0.15% at 657 rpm, 855oC hot cylinder temperature and 98oC cold cylinder temperature. The investigation of engine seal, oil lubricant, flywheel size and configuration, regenerator tube diameter, total dead volume and auxiliary cooler have significantly contributed to a successful performance of the engine in self-pressurized mode.