有机朗肯循环复合系统中喷射器能量分析

Energy loss investigation of ejector in organic Rankine combined cycle

有机朗肯循环利用太阳能、地热能和余热驱动,是回收余热、实现能源可持续发展的一个很好途径。有机朗肯循环可与喷射制冷循环结合,可同时提供电能和冷量。喷射器内部流体的不可逆混合引起的能量损失,是该系统最大部分的能量损失。着眼喷射器内部流场分布和机理,分析工作参数和几何参数对其性能的影响,以优化喷射器设计,减小系统能量损失,提高带有喷射器的有机朗肯循环复合系统的效率和节能潜力。结果显示,提高引射压力和出口压力会导致喷射器内部更多能量损失,制约整体系统的性能;在给定工况下,可通过钝化喷嘴内壁面、喷嘴处于最佳位置使喷射器达到最大喷射系数、最优性能,和最小的能量损失。

Organic Rankine cycle （ORC） can be driven by low temperature heat sources such as solar energy, geothermal energy, and waste heat. A combined ORC and ejector refrigeration cycle are introduced which are capable of producing power while having a simultaneous capacity for cooling. Most energy losses in the whole system take place in the ejector due to unavoidable losses caused by irreversible mixing. On the flow in the ejector in order to understand the underlying reasons for these energy losses were concentrated. It is found that some operating conditions, such as high pressure of suction and discharge fluid, introduce more energy loss inside the ejector and limit performance of whole system. An optimal design of smoothed nozzle edge and nozzle position were found to achieve a maximum entrainment ratio, the best performance, and lowest energy loss.