Experimental investigation of operation behavior of plate heat exchangers and their influences on organic Rankine cycle performance

As an efficient and reliable heat-to-power conversion technology, the Organic Rankine Cycle (ORC) has been recognized and accepted throughout academia and industry. Much effort has been devoted to the theoretical analysis, numerical simulation, and optimization in past decades. Experimental investigation has recently drawn considerable attention to practical applications. Most of experimental studies focused on the performance test of working fluid, expander, pump, and system. Although heat exchangers are the major contributors of exergy destruction and investment cost, few experimental studies have paid attention to heat exchangers and their effects on the performance of the ORC system. In this study, an ORC test rig with switchable evaporators and condensers is established to investigate the operation behavior of these heat exchangers and the influences of their heat transfer area on the performance of ORC system. An equivalent overall heat transfer coefficient, together with the degree of superheat, degree of subcooling, temperature difference and location at pinch point are used to evaluate operation behavior of the evaporators and condensers. A heat exchanger area utilization indicator is proposed, and applied along with the net power output and thermal efficiency to access the performance of the ORC with different heat exchanger combinations. The operation characteristics of these heat exchangers and the ORC system are experimentally investigated. Experimental results demonstrate that the operation behavior of these heat exchangers and the ORC systems are remarkably influenced by their heat transfer areas and combinations.