51. Energetic and Exergetic Performance Evaluations of an Experimental Beta Type Stirling Machine

This chapter focuses on a beta type Stirling receptive machine operating under an atmospheric pressure between two heat sources at constant temperatures. Two receiving modes are studied experimentally (refrigerator mode and heat pump mode). Parameters such as hot end temperature (about 110 °C maximum hot temperature output for the heat pump mode), cold end temperature (about −32 °C minimum cold temperature output for refrigerating mode) and coefficient of performance (COP) are studied under different engine speeds. In order to assess the receptive Stirling machine, we carry out energy and exergy performance assessment studies. Energetic and exergetic coefficients of performance and exergy destructions in the heat pump system and the refrigerating machine are quantified at different engine speeds. The results show that optimal operating mode for refrigerating machine is obtained at about 155 rpm. But, around this speed the heat pump mode deliver the worst COP. The influence of heat sources insulation on the exergy destruction and coefficient of performance of the system is investigated. Furthermore, the usefulness of good heat insulation is emphasized. In fact, it improves the energetic COP of the heat pump from 2.8 to 3.5 as the exergetic COP from 43 to 75.2 % at the same rotational speed.