Quasi Isothermal Heat Engine for Concentrating Solar Power Systems

Abstract

Recently we developed new type of solar concentrators, which have parabolic dish surface approximated with flat facet mirrors. To create the solar power plant on the base of these concentrators it is necessary to develop efficient heat engine for the temperature difference that can be obtained with new concentrators. For this purpose we propose to create quasi isothermal heat engine based on the Ericsson cycle and designed as rolling piston engine. We present in this paper two types of such engines: one-valve heat engine and valve-less heat engine. The theoretical analysis shows that for high temperature 600 K and low temperature 300 K the thermal efficiency can be obtained 0.46-0.49 for one-valve heat engine and 0.36-0.46 for valve-less heat engines for compression rate 1.2-1.05. To obtain acceptable power-two-weight ratio of the engine it is necessary to maintain the mean pressure of the cycle equal to 100-200 bar as it is made in some Stirling engines.