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The Lambert-Beer's coefficient K was measured in a wide range of temperatures (400-1200K) and pressures (2-8.2 MPa) in this paper. Based on the measured MAP of K and principle of energy conservation in the sprays mass and transfer, a quantitative presentation of equivalence ratio and temperature in vapor phase sprays at diesel engine like conditions was put forward. The experimental range of temperatures was 800-1100K and 20-100 kg/m₃ for density. It was found that the maximum equivalence ratio of vapor phase spray remained fairly constant at about 3.0 and the maximum equivalence ratio appearance earlier as the ambient density increased, while the ambient temperature in the constant volume vessel was set at 800K. The maximum equivalence ratio of vapor phase spray increased from about 3.0 to about 3.7 as ambient temperature increased from 800 to 1100K.

The Premixed Charge Compression Ignition (PCCI) engine has the potential to reduce soot and NOx emissions while maintaining high thermal efficiency at part load conditions. However, several technical barriers must be overcome. Notably ways must be found to control ignition timing, expand its limited operation range and limit the rate of heat release. In this paper, comparing with single fuel injection, the superiority of multiple-pulse fuel injection in extending engine load, improve emissions and thermal efficiency trade-off using high exhaust gas recirculation (EGR) and boost in diesel PCCI combustion is studied by engine experiments and simulation study. It was found that EGR can delay the start of hot temperature reactions, reduce the reaction speed to avoid knock combustion in high load, is a very useful method to expand high load limit of PCCI. EGR can reduce the NOx emission to a very small value in PCCI.

The paper has presented a new reduced chemical kinetic model for the Homogeneous Charge Compression Ignition (HCCI) combustion of n-heptane in an engine, which contains 41 species and 63 reactions. The new model includes three sub-models: the first is the low-temperature reaction sub-model, which is established by determining particular aldehydes and small hydrocarbons in the model developed by Li et al. The second is the sub-model for large molecules decomposing directly into small molecules that is developed for linking the low-temperature reaction with high-temperature reaction. The third is used for high-temperature reaction, which is derived by several modifications to the model developed by Griffiths et al., eliminating several reactions, adding two oxidization reactions related to CO and CH3O.