In this study, a small-scale test rig of organic Rankine cycle (ORC) system driven by low-grade heat has been developed and investigated experimentally. The test rig consisted of a number of essential components including a scroll expander and squirrel cage motor, plate-type recuperator, finned-tube air cooled condenser, liquid receiver, liquid pump, two thermal oil heated evaporators and other ancillaries. Considering its zeroozone depletion potential and appropriate thermophysical properties, R245fa was selected as a working fluid in the ORC system. Correspondingly, R245fa flow was heated and evaporated through either a plate-type evaporator or a shell and tube one by hot thermal oil flow which itself was circulated and heated by exhausted flue gases from an 80 kWe microturbine CHP unit. In this paper, the experimental investigations were mainly carried out on the ORC system with different evaporators and with or without recuperator integrated. Subsequently, the effects of various types of evaporators and with or without recuperator on the system performance are evaluated, compared and analysed. The test results and analysis are essential to understand the system operation at different design structures and components which can significantly contribute towards optimal component selections and system performance controls.
Keywords R245fa Organic Rankine Cycle; Experiment; Scroll expander; Evaporator