【摘要】 首先通过分析余热回收动力循环的不可逆损失,得到循环的理想效率。其次,通过分析发现热回收效率随蒸发压力变化存在最佳值,并且最佳热回收效率与最小熵增率是等价的。然后,通过研究两种简化的余热利用动力模型,应用有限时间热力学的相关方法,指出最大热回收效率产生的原因。再次,研究了余热变化时系统最佳工况的变化。结果发现最佳蒸发压力随余热流量、入口温度增加而显著增加,而与余热组分关系不大。最后,研究了工质对系统最佳工况的影响,发现较高临界温度的工质,最佳蒸发压力较低。更多还原

【Abstract】 Because of heat transfer,temperature of heat source for Organic Rankine Cycle(ORC) is changing along the flow direction.So heat recovery efficiency is more significant than cycle efficiency.First of all,this paper describes three types of system loss,and according to these loss,an ideal cycle of waste heat driven power cycle was presented.Then,the system analysis showed that an optimum evaporating exists for ORC system,the heat recovery efficiency has a maximum value.Thirdly,two simplified power model was investigated,using finite time thermodynamics,the reason of the maximum heat recovery efficiency was presented accordingly.Fourthly,the sensibility of waste heat source on optimum evaporating pressure was carried out.The results showed that optimum evaporating is a weak function of composition,but grows with waste heat flow rate and inlet temperature.At last,the effect of working fluid found that working fluids with high critical temperature have low optimum evaporating pressure.更多还原