SECOND LAW ANALYSIS AND CONSTRUCTAL DESIGN OF STIRLING ENGINE HEAT EXCHANGER (REGENERATOR) FOR MEDIUM TEMPERATURE DIFFERENCE (MTD)

This paper presents an analysis mto the effects that the regenerator length, regenerator matrix choice and dead-volume ratio have on medium temperature difference (MTD) Stirling engine performance. The Stirling engine has potential for use in the renewable energy industry and is suitable for use with low grade heat sources. The aim of the investigation is to give insight into the effects that the choice of regenerator properties and dead-volume ratio have on engine performance. The higher the effectiveness of the regenerator, the higher the thermal efficiency of the Stirling engine. Increasing the length of the regenerator increases the effectiveness, but results in an increased pressure drop. Decreasing the length results in a decreased pressure drop, but the heater and cooler loads increase decreasing engine performance. Therefore, there is an optimal regenerator length that gives optimal engine performance. In this paper, an engine of volume 1 000 cm(3) is analyzed at four different MTD heater inlet temperatures, namely 150 degrees C, 200 degrees C, 250 degrees C and 300 degrees C. Quasi-steady flow conditions and finite source and sink heat capacity rates are assumed and the exergy analysis approach is used to optimize the configuration. Results show that for each source temperature and mesh type there is a regenerator length and dead-volume ratio that give optimal engine work output.