Research Of Thermal Stability On Common Organic Rankine Cycle Working Fluid

With the rapid development of China economy, the consumption of coal, oil, natural gas and other fossil fuels is increasing. At the same time two effections apprered, on the one hand the energy is shortage on the other hand there is a lot of heat on the community. And compared with the high-temperature source, the low-temperature distribution was broader and storage was bigger. Organic Rankine Cycle(ORC) has a small capacity, high energy efficiency and has the potential to efficiently utilize low-grade heat recovery. Halogenzted organic working fluids are offen used, such organic working fluids offen used in refrigeration cycle before which the operating temperature is low. When the working fliud for the power cycle, due to the high operating temperature cycling, it faced the problems of thermal stability. To ensure the safe operation of the circulatory system, it is necessary to examine safe operating temperature range of operating fluids.In this paper, the Gibbs free energy and chemical balance principle were adopted, the thermal stability model of working fluids was established that used environmentally friendly organic working fluids(R600、R600a、R601、R601a、R152a、R123、R161、R125、R218、R245fa、R236fa、R143a、R134a) for the study, examined the equilibrium temperature of each working fluids of different chemical decomposition reaction by theoretical research methods, obtained temperature limit of each working fluids and studied the influence of the lubricant on the working fluid chemical equilibrium reaction, gained influence of lubricants on limit operating temperature of working fluids.The results showed that the thermal stability of different organic working fluids will be affected by the system pressure. In the studied conditions, the limit operating temperature of cycle working fluid will increase with the system pressure rises, and affected extent inconsistent in different pressure spaces. Under the conditions of certain system pressure, the limit operating temperature of cycle working fluid will increase with the reactants pyrolysis rate rises, and affected extent inconsistent in different pyrolysis spaces.In the studied conditions, the presence of the lubricating oil is conducive for R600、R600a、R601 and R601 a to maintain their stability. Lubricants presence does not affect the pyrolysis of R152a、R161、R245fa、R236fa and R143 a that lubricants presence had no effect on the thermal stability of these halogenated.