THERMAL-ANALYSIS OF THE HEAT-EXCHANGERS AND REGENERATOR IN STIRLING CYCLE MACHINES

A closed-form expression for the effectiveness of the heat exchangers and regenerator of a Stirling cycle machine is given. This result may be used in a simple way to evaluate their effect on the machine perfor mance. The proposed method allows the actual cycle gas temperatures in the heater and cooler to be obtained readily, once the geometry of th e heater, cooler, and regenerator is known and some quantities charact erizing the engine dynamics (strokes, frequency, and phase angle of th e moving elements) and its heat-exchange processes (inlet temperatures of the heating and cooling fluids and their volumetric flow rates) ar e measured. Thus, an immediate indication about the effectiveness of t he heat exchangers and regenerator as well as about the machine therma l efficiency may be obtained. The availability of a closed-form expres sion for the heater, regenerator, and cooler effectiveness is useful e specially for those engines, like the free-piston Stirling engines, wh ose design requires the application of analytically based optimization criteria. The obtained relations have been applied to the well-known Space Power Research Engine.