A review on "Experimental investigation of a low-temperature organic Rankine cycle (ORC) engine under variable heat input operating at both subcritical and supercritical conditions"

Abstract

The research paper cited, involves detailed experimental investigation of an organic Rankine cycle (ORC), which is designed to operate at supercritical conditions. The tests are conducted at the laboratory and the heat source is a controllable electric heater, which can keep the hot water temperature constant, by switching on/off its electrical resistances. The expansion machine is a modified scroll compressor with major conversions, in order to be able to operate with safety at high pressure (or even supercritical at some conditions). The ORC engine is equipped with a dedicated heat exchanger of helical coil design, suitable for such applications. The speeds of the expander and ORC pump are regulated with frequency inverters, in order to control the cycle top pressure and heat input. The performance of all components is evaluated, while special attention is given on the supercritical heat exchanger and the scroll expander. Supercritical pressure could be reached only for very high pump speed and low expander speed. The maximum efficiency reached is almost 6% for subcritical operation, while for supercritical operation was around 4.4%.