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为高效低损回收柴油机多品位余热,本文提出了一种跨临界有机朗肯联合循环,其中高温级循环用于回收温度较高的发动机排气余热和废气再循环(EGR)余热,低温级循环回收发动机冷却水余热、增压空气余热、与高温级循环换热后的排气余热和EGR余热。本文对联合系统高温级工质选择多种高温型工质,并对系统热效率、回收功、效率及整体效率随高温级最大压力的变化规律进行模拟分析。结果表明存在一个最优的高温级最大压力P_(maxh),使得随着P_(maxh)的增大,系统热效率先上升后下降,工质均存在热效率η(th)的最大值。甲苯不论是热效率还是效率均表现出较好的性能,并且使柴油机效率提高了6.86个百分点。
In order to recover diesel engine multi-grade waste heat with high efficiency and low loss, a transcritical organic Rankine cycle is proposed in this paper. The high temperature cycle is used to recover engine exhaust heat and exhaust gas recirculation (EGR) Recycling engine cooling water recycling waste heat, pressurized air afterheat, and the high temperature cycle exhaust heat after exhaust heat and EGR waste heat. In this paper, a variety of high-temperature working fluids were selected for the high-temperature working fluid in the combined system. The thermal efficiency, recovery work, efficiency and overall efficiency of the system were simulated and analyzed with the variation of maximum pressure at high temperature level. The results show that there exists an optimal maximum pressure at high temperature level, P maxh, such that as the P maxh increases, the thermal efficiency of the system first increases and then decreases, and the maximum of the thermal efficiency η (th) exists in the working fluid. Toluene showed good performance both in terms of thermal efficiency and efficiency, and the diesel engine efficiency was improved by 6.86%.