On-line Monitoring Of Ship Exhaust Emission And Energy Efficiency

Energy saving and emission reduction has become a hot issue in the shipping industry.Requirements of the current ship regulations are only aiming at ships in the design or certification stage,and there are few researches focusing on the evaluation of ships'comprehensive performance from the operational point of view.However,there are differences in operating conditions and environmental conditions between the actual operation and the certification process,which may result in the change in ship's real energy efficiency and emissions.What's more,ships'performance during the operating stage,which directly determines the severity of its actual environmental impact,should be more worthy of attention.To investigate the performance of ships in operation,a real-time ship test is launched on an inland waterway ship with an online monitoring system.Based on the analyses of the measured data,a comprehensive method is put forward to evaluate,supervise and optimize the energy efficiency and emission performance of ships in operation.The main contents of the paper are as follows:(1)Determine the parameters to be measured for the calculation of the ship's operating performance,and complete the selection and verification of the sensors based on the estimated range of the parameters and the characteristics of the test environment of ship.Selecting an inland river cargo ship and as the test object,and the middle and lower reaches of the Yangtze River,in which the tested ship usually sails,as the test area,an one-month ship navigation test is carried out.Continuous monitoring data of the test ship's navigation environment,operating conditions,fuel consumption and NO_x emission during its normal operation are obtained.(2)According to the operating condition data collected by the on-line monitoring system,the load spectrum of the real ship diesel engine is obtained.Based on the fuzzy clustering method,five feature points and their weights characterizing the ship engine's real operation state are dug out from the engine condition data.It's observed that the actual operating conditions are all in low speed,low power range,which are much different from the bench certification test cycle E3.Through the comparison of the actual data and the bench test data of ship engine performance,NEOI,for NO_x emission operational index,EEOI and the working range of main engine are respectively selected as the evaluation index of ships' performance in energy efficiency,emission and safety.Based on the evaluation index,an evaluation system framework for the operation performance of operating ship is established.Finally,the definition of performance baseline and its emission reduction coefficient for ship operation regulations are proposed.(3)The BP neural network and the derived mathematical model are respectively used to fit the relationship between EEOI and the ship speed,and the relationship between NEOI and ship speed.According to the acquired relationship above,a multi-objective optimization model of the comprehensive operating performance was established and solved under different ship load with the multi-objective genetic algorithm.As shown in the Pareto front of the solution,there is a trade-off relationship between EEOI and NEOI;EEOI shows relatively more sensitive to changes in ship speed;under the premise of navigation safety,improved operating performance of both energy efficiency and emission can be achieved by the increase in ships's actual load.