Effect of Different Heat Transfer Models on a Diesel Homogeneous Charge Compression Ignition Engine

Abstract

Homogeneous charge compression ignition (HCCI) engine technology is relatively new and has not matured sufficiently to be commercialized compared with conventional engines. It can use spark and compression ignition engine configurations, capitalizing on the advantages of both: high engine efficiency with low emissions levels. However, the combustion behavior in an HCCI engine is difficult to predict because it has no spark plug or injector. The chemical kinetics mechanism influences the combustion with some heat losses to the cylinder wall. The effect of different heat loss models in a diesel HCCI engine has to be investigated further. A single-zone thermodynamics model was used in this study along with three different heat loss models: Woschni, modified Woschni, and Hohenberg correlations. It was found that the difference in heat loss models leads to a big difference in the heat flux, and the modified Woschni model has the highest heat flux among these models. The effects of the different scaling factor and characteristic velocity were also investigated. The study concluded that the modified Woschni model produced more accurate results, while the Woschni and Hohenberg models require more tuning of constants before they can be used in a diesel HCCI engine.