Theoretical Analysis of Multi-Zone and Transported Probability Density Function Approaches Applied to Low Temperature Combustion Process

Electrification of transport, together with the decarbonizationof energy production are suggested by theEuropean Union for the future quality of air. However,in the medium period, propulsion systems will continue todominate urban mobility, making mandatory the retrofittingof thermal engines by applying combustion modes able toreduce NOx and PM emissions while maintaining engineperformances. Low Temperature Combustion (LTC) is anattractive process to meet this target. This mode relies onpremixed mixture and fuel lean in-cylinder charge whateverthe fuel type: from conventional through alternative fuels witha minimum carbon footprint. This combustion mode has beensubject of numerous modelling approaches in the engineresearch community. This study provides a theoreticalcomparative analysis between multi-zone (MZ) andTransported probability density function (TPDF) modelsapplied to LTC combustion process. The generic thermokineticbalances for both approaches have been analyzed interm of similarities. Only onion-skin for MZ models havebeen considered in this study. The governing assumptionslinked to sub-models for each approach to describe mixingprocess for TPDF and interzonal heat and mass transport forMZ are discussed. This step identifies the calibrated modelparameters for each approach and their effects on the accuracyin predicting LTC mode simulations. This work shows thatthe transported probability density function model has fewerparameters to calibrate compared to multi-zone model.Transported probability density function seems easier to usefor LTC process.