Analysis of Low Global Warming Potential Alternatives to HFC-245fa in Micro Scale Low Temperature Organic Rankine Cycles

orc2019 Tracking Number 100

The Organic Rankine Cycle is a power cycle for the valorization of low-temperature heat sources, being similar to a conventional Rankine cycle, but using an organic working fluid instead of water. Focusing on micro-scale low-temperature applications up to 100ºC, HFC-245fa and R134a are the most common working fluids, which stands out for its suitable thermodynamic and security properties. Nevertheless, due to new legislations, finding a low global warming potential working fluid is becoming increasingly necessary. New HFOs and HCFOs have been recently presented as potential low GWP alternatives for their use in low-temperature micro-scale ORC technology. The purpose of the present study is to analyze the behavior of these low-GWP substitutes in typical configurations, basic cycle and regenerative cycle, under generation and cogeneration operating conditions. The different working fluids will be tested in a theoretical model, which has been computed taking as a reference real installation with similar features. Finally, the main conclusions about the main strategies in order to design a new installation or to face a drop-in replacement with these low GWP working fluids are commented.