Waste Heat Recovery System on Marine Diesel Engines for Saving Fuel and Protecting Environment

Modern marine diesel engines, most especially the 2-stroke, large-bore, low-speed models, have already developed their thermal efficiency to a very high level and would seem to have little potential for further improvement. However, this does leave us with approximately 50% of the input energy not being fully utilized on board and consequently is wasted. This paper proposes a more efficient waste energy recovery system, this mainly from the main engine exhaust gases. Using a compact module consisting of a steam turbine and an exhaust gas power turbine, it was found that the total thermal efficiency improvement to a propulsive plant was more than 10%.