Performance prediction and parametric optimization of γ-type free piston Stirling engine

Abstract

The free piston Stirling engine is a complex system with multiple parameters strongly coupled. In this study, linear dynamic model and root locus technique are combined to investigate a ?-type free piston Stirling engine. Firstly, brief expressions are derived to predict the operating frequency, f, phase angle, ?, amplitude ratio, ?, and output power of ?-type free piston Stirling engine using linear dynam?ic model. The dynamic parameters are analyzed in detail to reveal their influence on the output performance of the system. Meanwhile, the starting conditions are obtained by root locus technique. Combining the results of the aforementioned two methods, a set of optimized design parameters is identified. The optimum values of f, ?, ?, and output power are 74.82 Hz, 65.38?, 1.92 W, and 108 W, respectively. Further more, a 60 W ?-type free piston Stirling engine prototype is developed and tested to validate the current model. Compared with the predicted results, the relative errors are less than 4.0% for f, less than 5.0% for ?, less than 2.0% for ?, and less than 10.0% for output power. This research provides a reliable approach for the further design of ?-type free piston stirling engine.