Diesel engines reject a considerable amount of energy to the ambience through the exhaust gas. Significant reduction of engine brake-specific fuel consumption (bsfc) could be attained by recovering a significant part of exhaust gas heat. Various techniques have been proposed in the past to recover exhaust energy: mechanical, electrical turbocompounding and Rankine Bottoming Cycles. In the present it is examined the potential bsfc improvement of heavy-duty (HD) diesel engines using the aforementioned technologies. The analysis is performed on a HD Diesel engine. An engine simulation model is used to estimate exhaust gas characteristics and examine mechanical and electrical turbocompounding. For mechanical turbocompounding it is investigated the effect of power turbine pressure ratio and efficiency while for electric the effect of T/C efficiency and exhaust pressure increase. Finally, a parametric study has been conducted using a 'Rankine bottoming cycle'. The analysis includes the effect of evaporator pressure and expander efficiency.
Keywords: exhaust gases, heat recuperation, mechanical turbocompounding, electrical turbocompounding, steam Rankine cycle, heat recovery, heavy-duty diesel engines, combustion, brake-specific fuel consumption, exhaust gas heat, simulation, evaporator pressure, expander efficiency