Study on Solar Rankine Cycle Engine of Displacement-type.

Abstract

Most of the past solar-powered heat engines have been aiming at operating under very high temperature and high pressure. For example, solar Stirling engine is operated at over 700∼800 degrees Celsius and at high pressure exceeding 10MPa. However, in order to obtain such a high temperature and high pressure condition, concentrating collector with large concentration ratio is inevitable. Also sun tracking device was compulsory to achieve high thermal efficiency. This direction requires high cost of the product, and brings low thermal efficiency, which loses competitiveness in the solar market. In this article, the unique solar Rankine cycle engine using displacement-type scroll expander is proposed. The proposed solar Rankine cycle engine has the following features ; 1) The system consists of very simple components similar to the airconditioner. 2) The operational temperature is very low (100∼300°C). 3) The thermal efficiency based on solar radiation is supposed to be about 15%, which is at least twice the conventional photovoltaic (PV) system.