双燃料发动机燃烧放热规律分析及燃烧特性研究

从热力学和内燃机燃烧的基本理论入手 ,推导了计算分析双燃料发动机缸内工质成分和热力学参数的计算关系式以及求解双燃料发动机燃烧放热规律的微分方程式 ,基于面向对象技术开发了双燃料发动机燃烧放热规律计算软件。研究结果表明 :用传统柴油机分析方法计算双燃料发动机的放热率峰值偏小 ,所计算的缸内工质平均温度偏高 ,新模型计算的结果与实际情况更为吻合。该分析软件可以适用于多种燃料发动机 ,是内燃机燃烧放热规律的通用计算软件。双燃料发动机燃烧特性研究表明 :双燃料发动机初始放热率比纯柴油大 ,若着火始点在上止点后 ,双燃料缸内最大爆发压力比纯柴油低 ,否则比纯柴油高 ;控制双燃料发动机着火始点是控制缸内最大爆发压力和 NOx 排放的关键 ,双燃料发动机着火始点应在上止点后 ,可以使发动机爆发压力和 NOx 排放比纯柴油低。

An Investigation on the Heat Release Rate and the Combustion Characteristics of Dual-Fuel Engines

In this paper,a new zero combustion model of dual fuel engines has been developed based on the fundamental combustion theory of internal combustion engine.It includes the expressions calculating the mass and the thermo physics parameters in cylinder.Also the differential equations calculating the heat release rate of the combustion have been deduced.The results show that the maximum heat release rate calculated by the conventional diesel model is lower than that calculated by the new model,but the temperature in cylinder is higher.It indicates that the new model agrees well with the experimental results.Additionally,this model is a universal engine combustion analysis one,and it can analyze the combustion process of the engine burning different fuels.The research results of the combustion characteristics of dual fuel engines show that the heat release rate at the combustion beginning of dual fuel engines is larger than that of the original diesel engines,and the pressure rise rate of dual fuel engines is larger than that of diesel engines.However,the maximum pressure in cylinder of dual fuel engines is lower than that of the original diesel engines if the combustion initiation takes place after TDC,the maximum pressure of dual fuel engines is lower than that of the original diesel engines if the combustion initiation takes place before TDC.So,in order to control the maximum pressure and the NO x emissions of dual fuel engines,it is very important to control the combustion beginning time.