Experimental investigations of cooling methods on the performance of TEG Module in an exhaust heat recovery system of an agricultural Diesel engine

Diesel engines are fuel efficient and have better part load characteristics than their counterpart petrol engines.Approximately thirty percent of heat is rejected in the exhaust gases of diesel engine.Many research works have been carried out to recover this waste heat for the utilization of power generation and other applications.The most notable one is the turbocharger, with others being various types of heat exchangers.All these devices have worked well in recovering heat.They also have their drawbacks.The present work is about recovering waste heat using thermoelectric devices to generate power directly.But the problem was how effectively this waste heat could be recovered.In this present work an exhaust passage has been designed to extracts maximum amount of heat from the exhaust and supplies it to the thermoelectric module.The passage has two main components.The central passage which extracts heat from exhaust and supplies it to the thermoelectric generator.The heat sink ensures the continuous absorption of heat from the thermoelectric module.Two types of designs were developed.One passage uses air for cooling the heat sink.The other passage uses water for cooling the heat sink.Then testing was carried out by connecting the passage to the exhaust pipe of the single cylinder diesel engine.Testing was carried out separately for air cooling and water cooling.A comparison was made on theoretical heat transfer, actual heat transfer, module power in both air-and water-cooled setups.Efficiencies based on heat transfer and module power were also calculated.It showed around 9% of heat had been converted to electricity by the module.