The Research On Exhaust Gas Cogeneration Technology Of Marine Medium-speed Diesel Engine

The efficiency of Medium-speed marine diesel engine fuel is limited, in order to improve energy efficiency and reduce emissions. Application the thermoelectric power generation technology, recover the exhaust duct heat, change the waste heat into electricity.In this paper, analysis and optimization medium-speed marine diesel engine exhaust pipe structure. Enhanced the heat convection between hot exhaust and the wall of pipe, improve the efficiency of waste heat utilization by changing the pipe structure model. Combined with thermocouple model, analysis the thermoelectric output characteristics of improved pipeline in different working conditions by FLUENT simulation software.First, according to the arrangement of the thermoelectric power generating device, selected the regular octagonal body conduit structure as the based exhaust duct model. Based on the theory of enhanced wall heat transfer, improve the internal structure of the pipe model and simulate the wall temperature distribution of different improvement program in rated conditions of diesel engine. The results of simulation data show the average temperature of the wall on exhaust pipes can be increased to 687.4K and the gradient is small when install the metal fins mounting annular inside the pipe which is very suitable for thermoelectric power generating device disposed. And simulate the temperature of the wall on exhaust pipe which has been improved under different conditions of distribution.Secondly, establish the thermocouple module and simulate the effects about the both end of thermocouple temperature by different cooling way on cooling end. When using water as the cooling medium, the temperature difference across the thermocouple was significantly higher than the case of using air as the cooling medium. Analysis temperature distribution at both ends of the thermocouple when using the wall temperature in different conditions as the contact temperature on hot side of the thermoelectric generator chip and cold junction forced convection of water as the cooling end.Finally, according to the temperature at both ends of the thermocouple in the different working conditions and the thermoelectric power generation output characteristic curve sheet differs, Analysis the maximum output power by thermoelectric generator of the exhaust pipe structure. Verify the thermoelectric power generation technology can be applied to medium-speed marine diesel engine exhaust gas heat recovery.