THERMAL BALANCE ANALYSIS OF THE MAN B&W 6S50ME-C MARINE DIESEL ENGINE

This study investigates the thermal balance of a MAN B&W 6S50ME-C two-stroke marine engine operating as the main propulsion system of a 40,000 DWT Oil/Chemical Tanker. Within the current maritime context, where fuel efficiency and emission reduction have become major priorities, a clear understanding of how thermal energy is distributed inside large marine engines is essential for performance optimization and energy recovery solutions. The objective of the paper is to determine how the energy released during fuel combustion is converted into useful mechanical work and how it is dissipated through various loss mechanisms. The analysis is based on a detailed thermal balance calculation using real operational data, such as effective engine power, specific fuel consumption, cooling fluid flow rates, lubrication oil parameters, and exhaust gas temperatures. The applied methodology consists of thermal balance calculations based on established thermodynamic relations, expressed in absolute, relative and percentage terms. The results indicate that approximately 40.98% of total thermal energy supplied by the fuel is transformed into effective mechanical output. A significant part of the remaining energy is lost through exhaust gases, accounting for about 29.37%, while cooling systems represent approximately 22.32% of total losses. Additional minor losses, including radiation and mechanical friction represent around 7.04%.The analysis confirms that exhaust gas losses constitute the dominant source of recoverable thermal energy. Consequently, the study highlights the importance of exhaust heat recovery systems as an effective means to improve overall engine efficiency, reduce fuel consumption, and support more sustainable marine propulsion operations.