Performance Study And Optimization Of Organic Ranking Cycle Using Medium And Low Temperature Heat

As a method to recycle the waste heat, Organic Ranking Cycle(ORC) can improve the energy efficiency and optimizing energy consumption structure which has advantages of simple structure, high efficiency, low investment and environment friendly. This paper investigates the performance of the ORC for recovery middle-low temperature heat through multi-objective functions. The work presents the thermal economic optimization on the ORC system and the construction of experimental platform. The contents of this research are as follows:Based on the basic laws of thermodynamics and thermal economy, the calculation model is built. The performance of the ORC system using several organic working fluids was evaluated through multi-objective functions and the influence of dry fluid and wet fluid on the ORC performance was to study comparatively.The impact of operation parameters on the ORC performance is carried out and five working fluids are calculated. The operation parameters include evaporating temperature, degree of superheat, condensing temperature, pinch temperature difference and heat resource temperature.The results show the overall ORC performance using the R245 fa is better than of others. Besides, there is a most suitable heat resource temperature for every working fluid.The thermal economic optimization of eight working fluids is carried out by genetic algorithm. The results indicate the levelized energy cost of R245 fa is lowest, 0.114$/k Wh. This paper researches two groups of zeotropic mixtures of R245fa-R600 a and R245fa-isopentane. The results show the zeotropic mixtures have better thermodynamic performance than the corresponding single working fluid. The mixtures show good thermal economic performance when the ratio of R245 fa is 0.7. However, the performance of other ratio mixtures is worse.To further improve the overall performance, the inner regenerator is added to the basic ORC. The results show that the thermal efficiency of the regenerative cycle is increased by 22.12% and the leveling energy cost is decreased by 32.9% when the fluid is R245 fa.Ten organic working fluids are selected to research the thermodynamic and thermal economic performance of the supercritical organic Rankine cycle. The trend of supercritical cycle is different from it of subcritical cycle and the overall performance is better than it of subcritical cycle in different degree.The experimental platform for recovery middle-low temperature heat is completed. Based on the total design scheme, the types of equipment in experimental platform are selected. The evaporating pressure is 2.5MPa, the theoretical generated power is 3k W for low heat resource and the theoretical generated power is 10 k W for medium heat resource. This platform can be used for the experimental study of various working fluids.