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Optimisation of a small solar organic Rankine cycle based on the exergetic analysis

Research paper by Alexandru Dobrovicescu, Lavinia Grosu, Diogo Queiros-;Condé

Indexed on: 22 Jan '17Published on: 27 Dec '16Published in: International Journal of Exergy



Abstract

A mathematical model is written for a solar organic Rankine cycle (ORC) taking into account the Pinch temperature differences in the system heat exchangers. The (exergetic factor)-;(variation in enthalpy) diagram of the hot and cold composite curves of the heater-;evaporator and the superheater of the ORC gives information about the strategy to be followed in order to improve the structure of the system. The introduction of an internal recuperative heat exchanger to preheat the ORC fluid and the splitting of the solar fluid to balance the heat capacities in the heater and the superheater are also considered. An exergetic analysis reveals the magnitude of the exergy destruction in the key pieces of the system. A comparative simulation of the way, the ORC operates with different organic fluids points out that R245fa gives the highest exergetic efficiency.