Study On Exergy Analysis Of Ship Integrated Energy System And Ship's Management And Energy Saving

With the development of science and technology, variety of modern technologies are applied on ships, increasingly modern ships look like metropolis sailing on the sea, they contain a large number of thermodynamic equipments and electromechanical devices, there are close relationships and interactions among these devices and equipments which constitute a complex ship integrated energy system, and this system consumes plenty of energy. So the ship energy saving has always been concerned by world shipbuilding and shipping industries, it relates to the conservation of fuel, environmental protection and economic issues such as ship operation.For the purpose of improving energy utilization of ship integrated energy system, reducing energy consumption and pollution, and finding out factors that affect the efficiency and the methods for energy saving, in this paper a thermodynamic system in engine room of a 75300 tons bulk carrier is chosen as the research object, variety of research data are obtained by investigation, the ship integrated energy system is analyzed by using exergy analysis method, and it's energy saving potential is studied as well. The paper has probed into several following respects mainly:First of all, the ship integrated energy system model is established according to a real ship powered by a diesel engine, the model is reasonable simplified, and an exergy analysis mathematical model of the ship integrated energy system is established by thermodynamic theory of exergy analysis, including the heat balance and exergy balance analysis model of the main engine unit, the waste heat recovery unit, the storage room and air-conditioning refrigeration units, the diesel generator engine unit and the fresh water generator unit.Secondly, the formulas of working medium energy and heat exergy are deduced, the fuel exergy formulas of main engine and diesel generator engine are obtained. The enthalpy, entropy, exergy of the air and flue gas are calculated, the formulas of the refrigerant, water and water vapor exergy are also obtained. According to the exergy analysis mathematical model of the ship integrated energy system and the thermodynamic properties calculation formulas of working medium, exergy analysis software of the ship integrated energy system is developed by using Visual Basic.Finally, the thermodynamic calculation and exergy analysis for a 75300 tons bulk carrier integrated energy system are implemented by using the exergy analysis software, the exergy losses, the exergy loss coefficients, the exergy loss rates and the exergy efficiencies of the ship integrated energy system, various units and various equipments are obtained, meanwhile the thermal efficiencies and the refrigeration coefficients of related units are obtained. The exergy flow diagram is drawn according to the results, the exergy losses, the exergy loss coefficients, the exergy loss rates and the exergy efficiencies of various units and equipments are compared, the exergy efficiencies and the thermal efficiencies of related units are compared as well. The energy saving potential of the ship integrated energy system is analyzed, and the multi-criteria energy saving evaluation criteria of the system is discussed, the multi-criteria evaluation system formula of the ship integrated energy system is established.