Stirling Engine Performance Optimization with Different Working Fluids

摘要

The design flexibility of Stirling cycle devices is evident from the wide variety of mechanical configurations that have been developed as well as the many differing applications that have been shown to be technically feasible. The choice of working fluid is one option that strongly influences engine design. Hydrogen permits the most compact engine (for a given power output and efficiency) of any gaseous working fluid investigated and has therefore been the choice in Stirling development programs directed at the automotive application where engine size is a major concern. Systems using helium or air are presently under development for applications where size is not as important a consideration. This paper describes calculated characteristics of engines optimized for four working fluids (hydrogen, helium, air and methane). A comparison is given between engines whose exterior dimensions are minimized and with lower rpm, lower pressure engine designs calculated by maximizing the dimensionless parameter known as the Beale number. Design point power and efficiency are the same in the resulting eight conceptual designs but great variation is shown in engine characteristics due both to working fluid differences and to the two different design objectives. 5 refs., 7 figs., 5 tabs. (ERA citation 12:004686)