Performance modelling and greenhouse impact assessment of a micro-ORC energy system working with HFCs, low GWP fluids and mixtures

Abstract

The worrying effects of climate change have led, in the last decades, to the improvement of innovative solutions for low greenhouse emission energy conversion, among which, is the use of micro-ORC (Organic Rankine Cycle) systems for distributed generation, in the framework of combined heat and power applications and renewables exploitation. However, micro-ORCs environmental impact, due to high GWP (global working potential) working fluid leak rate, is an issue still to overcome. Neverthless the interest in using new low GWP refrigerants and their blends is increasing, new fluids have not yet been properly tested into ORC. Numerical studies reveal that low GWP fluids do not always guarantee the same performance of typically used fluids, leading to indirect emissions related to the use of fossil fuels to compensate the lower power production. This study proposes to investigate performance and impact of an innovative micro-ORC test bench when working with HFCs (HydroFluoroCarbons), low GWP fluids and mixtures, with the main aim of comprehensively evaluating its impact due to both direct and indirect greenhouse gas emissions produced in a typical annual operation.