生物制气-柴油双燃料发动机NO_x计算模型

Simulation of NO_x Emission in Biogas Diesel Dual-Fuel Engine

采用气化炉热解气化各种农林废弃的生物质,产生可燃生物制气,作为双燃料发动机的主要燃料。双燃料发动机由单缸、四冲程、水冷、直喷式柴油机改装,生物制气通入发动机进气管,在进气过程中吸入气缸。在油滴蒸发准维燃烧模型的基础上,结合单区模型和详细化学反应动力学机理,建立生物制气—柴油双燃料发动机的NOx生成模型,计算结果与试验结果吻合较好。供油提前角提前,生物制气—柴油双燃料发动机NOx排放量增加;引燃柴油量减小时,NOx排放量减小。

Biogas can be made from various kinds of agricultural and forestry residues by a gasifier, and can be used as the main fuel of a biogas diesel dual-fuel engine ignited by diesel fuel. The dual-fuel engine is modified from a single cylinder, four-stroke, water-cooled, direct injection diesel engine. The biogas is induced to the cylinder through intake pipe during the intake process. A combustion and NOx formation model for biogas diesel dual-fuel engine is established. The model combines the single-zone model and the quasi-dimensional spray combustion model based on hiroyasu＇s model and the detailed chemical kinetics of NOx formation. The NOx emission at various speeds and loads are measured. The simulated and measured NOx emissions show good agreement. The relationship between the NOx emission performance and the operating parameters, such as engine speed and fuel pilot quantity are studied by using this model. NOx emission of the biogas diesel dual-fuel engine increases with the increase of pilot fuel quantity and the advancement of fuel delivery advance angle.