Experimental Study Of Low Grade Heat Energy Power Generation System Performance Based On Zeotropic Mixtures

Organic Rankine Cycle(ORC) power generation system becomes one of the best options for utilization of low grade heat, which is environmental friendly and has simple structure and high efficiency. However, the current study focused on pure organic working fluid, few studies about zeotropic mixtures. In order to explore the cycle performance for zeotropic mixtures applied to low grade heat power generation system, this article is mainly about calculation and experimental study for zeotropic mixtures power generation system:(1)Firstly, zeotropic mixtures components were screened and combined.By calculating the system performance of the basic and regenerative cycle under various heat conditions, Found that when the heat of condensation process with large temperature glide get full recovery, the performance of zeotropic mixtures power generation cycle is better than the components.(2)A power generation experimental system was built with different component mass ratio zeotropic mixtures R601a/R600 a,namely 1.0:0.0(R601a)、0.8:0.2(M1)、0.6:0.4(M2)和 0.4:0.6(M3).The preparation methods of R601a/R600 a and power generation experiments operational processes were determined.(3) Heat source temperature changes affect the power system performance directly. There is a heat temperature transition point, the rangeability of system performance with heat temperature is different before and after the point. The heat resource temperatures transition point of zeotropic mixtures lower than pure working fluid and which has better adaptability to heat source temperature changes. The cycle performance of zeotropic mixtures is better than pure substance under resource temperatures transition point. Zeotropic mixtures cycle performance is not a simple superposition of components. There is an optimal working fluid flow for maximum power with heat temperature increasing. The working steam superheat degree can be used to determine the matching relationship between the heat temperature and working fluid flow.(4) Adequate condensation conditions make good cycle performance. Zeotropic mixtures cycle performance is worse with large temperature glide. Due to the condensation phase transition is relatively stable, zeotropic mixtures power system running more stable than pure substance. Zeotropic mixtures cycle performance slightly weaker than pure refrigerants under basic cycle.(5) There is an optimal value of load resistor makes optimal power system performance under different heat resource temperature and working fluid flow which also make scroll expander work in the optimum condition, and the higher heat source temperatures correspond to greater optimum load. The scroll expander should match the appropriate generator and load to make the system get optimum performance.(6) The experiments verified low grade heat power generation system with zeotropic mixtures R601a/R600 a is feasible.M1 has the best performance in the three zeotropic mixtures. When the heat temperature does not exceed 140 ℃, the maximum net power generation is 0.753 kW, the maximum unit generating power is 23.12kJ/kg, the maximum thermal efficiency is 4.58%, the highest power generation efficiency is 3.51%.