Piston-Turbine-Compound Engine — A Design and Performance Analysis 650632
Exhaust heat utilization for internal combustion engines has centered around turbosupercharging in recent years, neglecting the promising field of compounding a piston engine with a gas turbine in which, unlike turbocharging, turbine power is fed back to the engine crankshaft.
The piston engine can cope with high gas pressure and temperature, whereas the gas turbine can efficiently utilize the energy at relatively low pressure and temperature and large volume flows. By compounding, this-piston engine will handle the high pressure, high temperature phase of the combustion cycle and extend the expansion ratio of the gases to atmospheric pressure by completing the low pressure, low temperature phase in the gas turbine. The marriage of the two engines will result in an outstanding power package with the highest thermal efficiency possible.
This paper discusses the Southwest Research Institute’s Piston-Turbine-Compound Engine, a two-cycle, uniflow, opposed piston supercharged, turbocompounded diesel engine, incorporating infinitely variable compression ratio. The present engine has a compactness of 28 hp/cu ft of installed volume compared to values of 5.1 for a typical diesel track engine, and 19 for a typical nonregenerated gas turbine. It has a calculated minimum fuel consumption of 0.32 lb/bhp-hr.