低温蒸汽-太阳能双热源ORC发电系统热力性能分析

Thermal Performance Analysis of a Low Temperature Steam-Solar Energy Dual Heat Source ORC(Organic Rankine Cycle) Power Generation System

为充分回收矿藏热采过程尾端低温蒸汽余热,提出一种通过利用太阳能热量补充预热器中热源显热以缩小换热温差的新型低温蒸汽-太阳能双热源ORC发电系统。根据热力学第一、第二定律,建立其热力学模型,编制计算程序并进行了热力性能分析及比较。计算结果表明:采用热源补助可有效减小换热温差,进而显著提升系统热力性能。当采用R245fa作为循环工质时,与基本的ORC系统相比,选择冷端温差较小的预热器可使双热源系统火用效率显著增加;在预热器冷端温差为30 K、两系统分别采用5种不同循环工质时,双热源ORC系统的热力性能均高于基本ORC系统,且以R236fa为工质的双热源ORC系统热力性能最佳。

To fully recover the low temperature waste heat steam in the tail end of the mineral reserve hot mining process,proposed was a novel type low temperature steam-solar energy dual heat source ORC system utilizing the heat quantity from solar energy to replenish the apparent heat of the heat source in the preheater to reduce the heat exchange temperature difference. According to the first and second law of thermodynamics,a thermodynamic model for the system in question was established,a program was prepared and an analysis and comparison of the thermal performance of the system were conducted. The calculation results show that to use a supplementary heat source can effectively reduce the heat exchange temperature difference,thus remarkably enhancing the thermal performance of the system.When R245 fa is used as the working medium in the dual heat source cycle system,compared with the basic ORC system,to choose a preheater with its temperature difference at the cold end being relatively small in the system can make its exergy efficiency remarkably increase. When the temperature difference at the cold end of the preheater is30 K and both systems adopt respectively five kinds of cyclic working medium,the thermal performance of the dual heat source systems are all higher than that of the basic ORC system and the thermal performance of the dual heat source ORC system using R236 fa as its working medium is optimum.