A study evaluating the ability to recover cooling water waste heat using organic Rankine cycle on marine engines

Waste heat recovery (WHR) technology is an effective way to reduce fuel consumption and CO2 emissions, and is currently used in some ships, converting up to 8% of main engine braking power into electric power. In this paper, a 4-stroke small marine diesel engine with a nominal capacity of 60kW at 2200 rpm is used for experimental research. The main parameters of waste heat from the engine include the exhaust heat and the cooling water waste heat used under operating conditions at a fixed speed at 2000 rpm at 100%, 75%, and 50% load respectively. Three system configurations were studied, including configuration (a) (recovering waste heat from cooling water to preheating the substance and recovering all waste heat from waste gas to evaporate the substance), configuration (b) (recover all waste heat from cooling water for preheating properties and recover waste heat from waste gas to further heat the substance) and configuration (c) (only waste heat recovery is performed by cooling water). The system activities are evaluated for thermal efficiency and waste heat recovery efficiency with R245fa. At the same time, the improved efficiency of ORC systems and generating capacity are presented to clarify the ability to utilize waste heat of the designed ORC system.