Analysis on the heat-recuperable hybrid cycle for micro swing engine with a non-isometric multi-chamber structure

With low efficiency and insufficient power, the conventional micro swing engine has not been available for portable power source. Therefore a novel hybrid thermodynamic cycle with heat recuperation ability, which is suitable for the micro swing engine, is proposed to overcome the above defects, whose thermodynamic characteristics are investigated in details, indicating a great improvement for the engine performance. Firstly, the micro swing engine is modified to be a three-arm engine with a non-isometric multi-chamber structure. Driven by the hybrid cycle, the engine body and a specially designed spiral recuperator work together successfully in theory. Thus, the entire efficiency is increased by heat recovery from hot exhaust and restriction of structural heat leakage. In consideration of flow leakage effect, simulation models of the steady working process of the engine in hybrid cycle are established. Numerical results reveal that, thermal performance of the hybrid cycle has an obvious advantage over the single thermal cycle. Moreover, the hybrid cycle is composed of two single four-stroke cycles and two two-stroke cycles. The two adjacent cylinders, between whom the flow leakage happens, are with different cycles, and hence distinct thermal performances. Finally, with the application of this heat recovery process, the efficiency of the four-stroke cylinders is improved relatively by 45.31% and the total engine efficiency is increased by 14.09%. Effectiveness and practicability of the hybrid cycle with heat recuperation are demonstrated theoretically, which is of great significance for the progress in micro heat engine field.