A new approach for exhaust energy recovery of internal combustion engine: Steam turbocharging

In this paper, a new concept of steam turbocharging was proposed to boost IC engine intake pressure. A set of Rankine steam cycle system is coupled on IC engine exhaust pipe, which uses IC engine exhaust energy to generate steam and then drive the turbine. Part of steam expansion power is used to drive air compressor, and the remainder is recovered by motor. To compare with exhaust turbocharging, the two kinds of boosting pressure methods are applied on the same IC engine, and the working processes of steam turbocharged engine and exhaust turbocharged engine were simulated. On this basis, the differences between two kinds of boosting pressure methods were analyzed, and IC engine performance enhancement potentials by using steam turbocharging system were obtained. The results show that IC engine power can be theoretically improved by 7.2% at most, and thermal efficiencies can be improved by 2 percent points or more except at 1000 r/min by using steam turbocharging. All these can prove this boosting pressure concept is a novel technology with great energy saving potentials.

► A new concept of steam turbocharging is proposed to boost IC engine intake pressure.
► In exhaust turbocharging system, nearly half of turbine output work comes from the piston work.
► The performances of steam turbocharging system can be optimized by adjusting steam pressure and flow rate.
► The power of steam turbocharging engine can be improved by 7.2% at most on the basis of exhaust turbocharging engine.
► IC engine thermal efficiencies can be improved by 2 percent points or more except at 1000 r/min.