| Summary: The first law of thermodynamics emphasizes that the amount of energy of a system cannot be destroyed but can turned into different energy while the second law gives an information of how much of energy can be converted to useful work. In the present study, availability of energy and exergy variations are analyzed for a diesel engine belongs to a vessel. Six different engine loads are obtained by changing vessel’s propellers’ blade’ pitch angle keeping stable engine speed at 550 rpm. By measuring pressure, temperature and flow rate of fluids such as water, oil, air, exhaust gases that belongs to the engine in this engine loads; it is determined that energy was consumed in which proportions on the systems such as cooling water, lubrications oil, exhaust gases that belongs to the engine with this amounts. Because of irreversibilities which forms in the engine, the amount of exergy destruction was calculated. According to the obtained results, fuel and air energy amount which passed to exhaust gases is about (19-28)%. Excluding exhaust gases about (38-58)% of fuel and air energy is used for cooling water, lubrication oil and other losses energy expelled for total heating losses. Maximum engine efficiency is supplied on 70% of engine load. It is seen that the highest exergy flow rate belongs to exhaust gases with (20-27)%, while changing based on engine loads. Excluding exhaust gases, total exergy amounts used for cooling water, lubrication oil and other losses are about (9-15)%. In the system, the highest exergy efficiency value which is calculated in engine loads with the amount of 40% and 70%, the highest exergy destruction is seen nearly 39% in the engine load 30%.
Key Words: Energy analysis, Exergy analysis, Irreversibility, Vessel diesel engine |
