Lingfeng Shi

Comparison and Selection Research of CO2-Based Transcritical Rankine Cycle Using for Gasoline and Diesel Engine's Waste Heat Recovery

ABSTRACT This paper presents a theoretical study of CO2-based transcritical Rankine cycle (CTRC) for engines waste heat recovery, involving comparison and selection of four CTRC configurations for two engine types, namely a gasoline engine and a diesel engine. The results of configuration comparison show that the CTRC configuration with both a preheater and a regenerator may be more suitable for both two type engines with water-cooling system. If only recovering the waste heat of exhaust gas, the regenerated CTRC configuration may be more appropriate. The results of engine type comparison show that engine load has slighter effect on the CTRC performance for the gasoline engine compared with that for the diesel engine. Particularly, this paper jointly considers the effect of CTRC weight to evaluate the final CTRC output, which is significant for the vehicle engine. A critical weight is found for the two engines based on 100% engine load, 215 kg for the gasoline engine and 998 kg for the diesel engine, which is the upper limitation of the CTRC weight design. When considering the weight effect, the diesel engine may be the more suitable recovery target compared with the gasoline engine, owing to the more stable reaction of output performance to the CTRC weight.