Parametric Study on the Performance of Gas Springs in FPSE With Pneumatic Supporting System

Abstract

The introduction of a pneumatic supporting system composed of gas springs and hydrostatic bearings in the free-piston Stirling generator (FPSG) can effectively increase the power density of the nuclear space power plant. In this paper, a 1 kW FPSG with pneumatic supporting system was developed, and the working characteristics of dual gas springs were obtained under an external driving condition. A quasi-one-dimensional numerical model is established, the relative error between piston strokes is within 5%, and the maximum phase uncertainty is 5.36° between experimental and numerical results. The generator outputs 1011.3 W with a total thermo-electric efficiency of 14.85% under the rated condition, and the hysteresis loss of gas springs is 535.6 W, which accounts for 7.85% of the total power input, and the global stiffness reaches 96.43 N/mm. A multitude of influencing factors (including operational, constitutive, and sealing parameters) on the performance of gas springs are evaluated. An expression for the correction coefficient of stiffness with respect to five influencing parameters is established through data regression, as well as an empirical formula for the hysteresis loss as a percentage of the total input power. The correlations indicate that the order of weights affecting the performance of gas springs is as follows: compression ratio, configuration factor, gap thickness, gap length, and wall temperature.