The idea of recovering waste heat, and using it for some useful purpose, is certainly not new. Within vehicular applications, most people are aware, perhaps unknowingly, of some form of waste heat recovery technology. The simplest of these forms is most-likely the utilization of engine waste heat for the purpose of cabin heating. In this instance, the waste heat engine coolant stream simply transfers heat to the cabin, instead of outside air, in order to provide the desired level of passenger comfort. Another common, and more complex, form of waste heat recovery is the use of a turbocharger. In this instance, some of the waste heat from the exhaust stream is used to drive a compressor, via an exhaust-driven turbine, for the purpose of increasing the aerobic potential of an internal combustion engine, which in turn increases its power output. This evolution of waste heat recovery technology from simple thermal waste heat utilization, to thermal mechanical waste heat utilization with the automotive industry is an evolutionary path not unique to this industry, and has subsequently taken place in other areas outside of on-road applications. Of
ABSTRACTFuel efficiency for tractor/trailer combinations continues to be a key area of focus for manufacturers and suppliers in the commercial vehicle industry. Improved fuel economy of vehicles in transit can be achieved through reductions in aerodynamic drag, tire rolling resistance, and driveline losses. Fuel economy can also be increased by improving the efficiency of the thermal to mechanical energy conversion of the engine. One specific approach to improving the thermal efficiency of the engine is to implement a waste heat recovery (WHR) system that captures engine exhaust heat and converts this heat into useful mechanical power through use of a power fluid turbine expander.Several heat exchangers are required for this Rankine-based WHR system to collect and reject the waste heat before and after the turbine expander. The WHR condenser, which is the heat rejection component of this system, can be an additional part of the front-end cooling module. Packaging this WHR condenser as part of the front-end cooling module can be an engineering challenge given the tight underhood environment where the current powertrain cooling components are already near system-capable thermal limits. This paper shows how Lattice Boltzmann Method based simulations using highly-detailed vehicle geometry were utilized in the development of the heat exchanger architecture used to meet peak cooling needs as well as provide sufficient cooling airflow to the WHR condenser under all operating conditions. Heat exchanger results from the simulations are shown to compare well to cooling test measurements in a fully-climatic vehicular wind tunnel.