| With the decrease of global oil resources and environmental deterioration, energy conservation and emission reduction has become a hot topic which human concerned. In the shipping field, since2007when Marine Environment protection Committee (MEPC) launched the Energy Efficiency Design Index (EEDI) for new ships, marine diesel engine exhaust heat recovery technology has been paid more and more attention by all parties.Technological development and modern technology in a large number of applications in the ship, the ship contains a wide range of thermal devices and equipment, there are close work and hot relationships and interactions among these devices and equipment which constitute a complex ship integrated energy system. Therefore, the analysis of the total energy system is of great significance for ship energy saving and emission reduction.Based on the specific analysis of the diesel engine system structure, using energy conservation equation, continuity equation, the gas equation of state to establish a mathematical model of the diesel engine working process. Then it use set of dynamic system modeling, simulation, and analysis in one software MATLAB/Simulink to establish cooling law, the instantaneous cylinder volume law, burning exothermic law modules package modeling. Moreover, host of a76,000t bulk carrier ship for the study, and its simulation, comparison with the actual working conditions in order to verify its correctness. And then the diesel engine exhaust heat based on the cascade use calculation to obtain the calculation result of the relevant parameters.According to a steady-state operating conditions of the diesel engine of the76,000tons of bulk carriers ship and the steady-state condition diesel engine exhaust heat cascade utilization of these two conditions, respectively exergy analysis and calculate of the exergy efficiency of the two conditions including the main engine unit, power generation diesel engine unit, waste heat recovery unit, the food refrigeration cycle unit, air conditioning and refrigeration cycle unit and fresh water generation unit and the total energy system of ship. And then conducting energy-saving and emission reduction analysis based on the calculated results.For large diesel engine exhaust heat cascade utilization generate energy-saving effect. From the perspective of the waste heat reutilization it is because the power turbine and steam turbine re-use impossible energy of the diesel engine, i.e. the main engine exhaust gas; from the point of view of the combined cycle, the Bolei Raton cycle of power turbine and Rankine cycle of steam turbine in accordance with the principle of the main engine exhaust gas cascade utilization, the maximum use of the energy in the exhaust gas; from the point of view of the average temperature of the main engine, cascade utilization reduces the waste heat average exhaust temperature of the entire cycle so that it achieve a higher cycle efficiency. |
