Abstract
Waste heat recovery is an alternative to improve the energy efficiency and decrease the fuel cost in industrial processes. Nanofluids have been considered an alternative to common fluids in heat exchangers in order to increase their heat transfer rate. This experimental study was conducted using graphene oxide (GO) nanofluids in a thermosyphon-based heat exchanger coupled to a diesel electrogene group forming a cogeneration system. The heat exchanger had 47 copper thermosyphons, which were evaluated with water and with a GO nanofluid at a 30% filling ratio. The heat supplied to the evaporator was produced by the exhaust gases of a diesel engine coupled to an electric generator, and the external air flow was used in the condenser. Before the experiments in the heat exchanger, one thermosyphon with the same filling ratio was evaluated using water and the GO nanofluid to compare its thermal performance at lab scale. The results at lab scale showed a decrease in thermal resistance by up to 67% using the GO nanofluid compared to water. However, when the thermosyphon-based heat exchanger was evaluated at real scale with water and the GO nanofluid, its performance was not improved despite the fact that some individual thermosyphons showed lower condenser-evaporator temperature differences.
Published Version
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