Study on Low Temperature Combustion for Light-Duty Diesel Engines

摘要

This paper presents a study on the feasibility of obtaining low temperature mixing-controlled combustion (mixing-controlled LTC) in a small HSDI engine with the objective of avoiding simultaneous NO_x and soot formation. This mixing-controlled LTC strategy is based on reducing the equivalence ratio at the liftoff cross section and also the local combustion temperatures, but maintaining the conventional dicsel spray structure. A parametric study has been carried out to evaluate the effects of in-cylinder gas density, temperature, and oxygen concentration on the characteristics of the mixing-controlled LTC characteristics. Low NO_x and low soot mixing-controlled diesel combustion has been attained by combining low in-cyiinder gas temperatures together with high air densities and low oxygen concentrations. However, the mixing-controlled LTC concept also presents an important drawback related to the engine efficiency deterioration.