INTEGRATED RANKINE BOTTOMING CYCLE FOR DIESEL TRUCK ENGINES

This study assessed the feasibility of incorporating a Rankine bottoming cycle into a diesel truck engine. An organic Rankine bottoming cycle (ORBC) previously demonstrated by the US Department of Energy in a heavy-duty, long-haul truck reduced the truck's fuel consumption by about 12%. However, that system was considered too complex and costly to be commercialized. The integrated Rankine bottoming cycle (IRBC) described here is expected to be simpler and less costly than the ORBC. In the IRBC, one cylinder of a six-cylinder diesel truck engine will be used for power recovery, instead of the turbine and reduction gears of the ORBC; engine coolant will serve as the working fluid; and the engine radiator will also serve as the condenser. Toluene and steam were considered as working fluids in this assessment, and we concluded that steam (at 1000 psi, partially vaporized to about 33% saturation in the cylinder head, and superheated in an evaporator) would be the more practical of the two. Both heat exchangers are smaller than those of the ORBC system, but may pose a challenge in an under-the-hood installation. Overall, the concept appears feasible. 13 refs., 9 figs., 7 tabs.