中低温地热发电有机朗肯循环工质的选择

为了筛选出适合于中低温地热发电有机朗肯循环的较优有机工质,采用热动循环的分析方法及PR状态方程计算以10种干流体有机工质为循环工质的中低温地热发电有机朗肯循环的效率及其余主要热力性能.结果表明,总体来看,随着循环工质临界温度的升高,蒸发压力、凝结压力、输出功率及效率呈下降趋势,而循环热效率及地热流经换热后的排放（或回灌）温度呈上升趋势.以R227ea（七氟丙烷）作工质的有机朗肯循环系统输出功率及效率最高,蒸发压力及凝结压力均处于较合适的范围,R227ea是中低温地热发电有机朗肯循环较理想的工质.

Selection of Working Fluid for Organic Rankine Cycle Used in Mid and Low-Temperature Geothermal Power Plant

To select the ideal organic working fluid for organic Rankine cycles used in mid and low-temperature geothermal power plant,the exergetic analysis method and PR equation of state are utilized to calculate the exergy efficiency and other main thermal performances of the mid and low-temperature geothermal heat powered organic Rankine cycles using 10 kinds of dry fluids as working fluids.The results show that： As the critical temperature of working fluid increases,the evaporation pressure,condensing pressure,output power and exergy efficiency show a decreasing trend,but the cycle thermal efficiency and the final discharge（or rejection） temperature of the geothermal fluid show an increasing trend as a whole.Moreover,the organic Rankine cycle charged with R227ea（heptafluoropropane） gets the highest power output and exergy efficiency,and the evaporation and condensation pressures are in the appropriate range.Therefore,R227ea is the suitable working fluid for organic Rankine cycles used in mid and low-temperature geothermal power plant.