Aresearch Of Intake Air Humidification Effects On Marine Diesel Engine Performance And Emission Characteristics

Since the deterioration of environment, emission regulations on marine dieselengines have become more and more stringent. With the IMO TierⅢ come into force,the marine diesel engine manufacturers will face new challenges.The combination ofdifferent NOx reduction technologies may will be the main methods to comply withthe IMO TierⅢ NOx limit.As one of the internal NOx reduction methods, intake airhumidification can reduce NOx effectively and be combined with other NOxreduction technologies effectively. However, there is few research on combination ofMiller Cycle and intake air humidification and the study in regard to the influence ofintake air humidifacation on marine engine’s performance and emission charactericsis not enough in domain.To know more about intake air humidification, this paperinvestigated the changes of engine performance and emission characteristics afterusing intake air humidification.Aim at a high speed marine diesel engine designed by Shanghai Marine DieselEngine Research Institute, design intake air humidification system and carry outintake air humidication experiment, the intake air humidification system can humidifythe intake air effectively.On the condition of present experiment components,theintake air humid ratio can reach to20g/kg more or less,the corresponding NOxreduction can be20%with little deterition on brake specific fuel consumption.Model the experiment engine and calibrate it via the experiment results.We getdetail formula relation between intake air humidity and NOx reduction amount bysimulation and know that engine speed and load have little effect on the formularelation between them.Set intake air temperature75℃,relative humid ratio70%,theintake air humid ratio of experiment engine can be58.7g/kg and44.7g/kg on75%,100%load,the corresponding NOx reduction can be66.6%and54.7%based on simulationresult.The effect weight of charge air humidity, injection timing and Miller strength onNOx emission,brake specific fuel consumption,etc. was investigated via design ofexperiments,as well as the interaction between them.In addition,regulate the intakevalve lift and timing to investigate the effect of intake air humidification on engineperformance and emission characterics under different miller strength.The resultsindicate that there is little interaction between Miller cycle and intake airhumidification. When intake air humidification is used by experiment engine on condition that the intake air temperature is higher than70℃，the intake air cam withlittle Miller strength is the best(intake air valve close at585。CA)。...