基于实船油耗与排放的拖轮航速优化

利用便携式排放测试系统对上海外高桥港近海拖轮进行了油耗与排放测试, 拟合了油耗、排放与航速的关系, 建立了巡航工况下的航速优化模型, 分析了拖轮最佳油耗和排放对应的航速。试验结果表明: 船舶CO₂的排放因子与燃油的品质和船舶工况相关, 与实船排放测试相比, 使用经验排放因子估算排放率是可行的; 当使用幂函数拟合CO、CO₂、THC、NO_x、PM、PN排放和油耗与航速关系时, 各拟合曲线的决定系数均大于0.9;仅对油耗优化, 当航速为7.21kn时, 拖轮单次巡航工况下的总油耗达到最小值, 相对最大航速12.00kn的油耗下降了33.40%;对油耗和NO_x排放进行优化, 得到的最优航速最大; 对油耗与所有排放同时优化, 得到的最优航速最小; 当航速为6.96kn时, 拖轮的总油耗、NO_x、PM和PN总排放达到最优值, 相对最大航速, 总油耗下降了33.29%, CO、CO₂、THC、NO_x、PM、PN减排率分别达到59.56%、76.37%、82.34%、92.36%、53.10%和62.25%。可见, 在最优航速时, 拖轮总油耗与总排放均显著减小。

Cruise speed optimization of tugboat based on real fuel consumption and emission

The test of fuel consumption and emission of offshore tugboat in Shanghai Waigaoqiao Port was conducted by using portable emission measurement system, the relationship between fuel consumption, emission and cruise speed was fitted, an optimization model of cruise speed was established, and the optimal fuel consumption and emission of tugboat and corresponding speed were analyzed.Test result shows that CO2 emission factor is related to fuel quality and working condition of ship, and the accurate emission result can be obtained by estimating based on empirical emission factor comparing with real-ship emission test.When power function is used to fit the relationship between the emissions of CO, CO2, THC, NOx, PM and PN, fuel consumption and cruise speed, the determination coefficient of each fitting curve is larger than0.9.Under the condition that fuel consumptionis optimized, when cruise speed is 7.21 kn, the total fuel consumption of tugboat in single cruise condition reaches the minimum and decreases by33.40% compared to the maximum cruise speed of 12.00 kn.The optimal cruise speed reachesthe maximum while both fuel consumption and NOxemission are optimized.The optimal cruise speed reaches the minimum while both fuel consumption and all emissions are optimized.When cruise speed is 6.96 kn, the total fuel consumption and emission of NOx, PM and PN reach the optimal values, compared to the maximum cruise speed, the total fuel consumption decreases by33.29%, and the emission reduction rates of CO, CO2, THC, NOx, PM, PN are 59.56%, 76.37%, 82.34%, 92.36%, 53.10%, 62.25% respectively. Obviously, the total fuel consumption and emissions of tugboat decrease significantly at optimal cruise speed.