Premixed Charge Preparation Strategies

Abstract

Mixing of fuel and oxidiser (air) for combustion is termed as charge preparation. Creation of premixed charge is the key feature of low temperature combustion (LTC) engines. Quality of fuel–air mixture governs the combustion process and its rate. Premixed charge is required prior to the start of combustion in LTC engines. Depending on LTC strategy, different quality of premixed charge (degree of homogeneity) is required for higher thermal efficiency and control of the combustion rate. The premixed charge can be created by injecting fuel outside the engine cylinder (external charge preparation) or inside the engine cylinder (internal charge preparation), depending on fuel properties and combustion strategy. This chapter presents the summary of premixing techniques used for charge preparation in LTC engines. Charge preparation strategies for well-mixed charge (more often external charge preparation) and partially stratified charge (internal charge preparation using direct injection) are discussed in detailed for gasoline-like fuels as well as diesel-like fuels. Dual fuel charge preparation (using high and low reactivity fuels) is typically used in RCCI combustion is also discussed in the present chapter.