Safe performance analysis of flammable mixture working fluid leakage in Organic Rankine Cycle

As working fluid in Organic Rankine Cycle (ORC) used for engine waste heat recovery, the unavoidable leakage of HCs/CO2 mixture in practical application is a threat for safety due to its flammability. In this work, safe performance comparison of propylene/carbon dioxide and pentane/carbon dioxide is carried out through concentration distribution analysis and explosion damage degree evaluation. In addition, influence factors of dispersion characteristic were analysed. According to the assessment results, the concentration of propylene is higher than pentane at the same position after leakage. However, the damage degree to buildings and individuals caused by explosion increase from propylene/carbon dioxide to pentane/carbon dioxide. Wind speed and hydrocarbon ratio have obvious effect on the dispersion characteristics. To improve the safe performance of hydrocarbon/carbon dioxide mixture in practical application, gas detectors in the middle of the ceiling can detect the occurrence of gas leakage in less than one second. The maximum ratio of propylene and pentane should be 0.4 when blending with carbon dioxide in view of explosion risk. (C) 2017 The Authors. Published by Elsevier Ltd.