Exhaust Heat Co-Generation System Using Phase Change Cooling for Heavy Duty Vehicle

Copyright © 2007 SAE International A waste heat recovery system composed of a two phase cooling system, an exhaust heat exchanger, and mini-turbine (expander) has been proposed by Henry Works, Inc to generate auxiliary power via harvesting engine cooling and exhaust heat loss from heavy duty vehicles. The objective of this research is to evaluate the two phase cooling system through engine dynamometer testing and obtain initial test data for the development of the waste heat recovery system. Engine dynamometer experimentation for evaluating two phase cooling has been conducted using a Perkins diesel engine. During the two phase cooling phase, the coolant temperature showed less than 1 °C variation in the cooling path and the cylinder head temperature was more uniform than that of single phase cooling. As the saturated vapor pressure increases during two phase cooling, the cylinder head and coolant temperatures also increase. Thus, the maximum pressure of the saturated vapor in the two phase cooling is limited by allowable cylinder head temperature that is determined by cylinder head distortion, abnormal combustion, exhaust emissions, etc. The water coolant mixed with trifluoroethanol showed lower cylinder head temperature than pure water coolant at higher vapor pressure of the coolant. Based on the measured values in the engine dynamometer experiment, the potential power output of the proposed waste heat recovery system under the same engine operating conditions in this study ranges from 0.47 KW ~ 1.05 KW