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The present work highlights the effect of wall heat transfer models on numerical predictions of combustion phenomenon in compression ignition diesel engine. A comparison of engine's performance is made using O'Rourke and Amsden, Han and Reitz and Angelberger heat transfer models. A detailed chemistry model employed comprises of 61 species and 235 reactions for n-heptane/diesel combustion. RANS RNG k-ε turbulence model (Reynolds-averaged Navier-Stokes: RANS; re-normalisation group: RNG; turbulent kinetic energy-rate of dissipation of turbulence energy: k-ε turbulence model) is used here to model mass, momentum and energy transport equations for engine computational fluid dynamics simulations. The study performed is on turbocharged 130PS 5.675L diesel engine and presented against experimental findings. Effect of different wall treatment models on accuracy and inherent computational time requirement for predicting engine P-θ (cylinder pressure vs. crank angle) curve, indicated mean effective pressure and AHRR (apparent heat release rate) is discussed in this paper. This comparative study facilitates in choosing optimum heat transfer model for in-cylinder combustion study vis-à-vis the trade-offs between solution accuracy (which drives product quality) versus computational time (which drives time to market).

The study focuses on the selection of detailed chemistry model for numerical combustion of compression ignition diesel engine. Three different established chemical reaction mechanisms of different chemistry resolution are considered to predict the macro performance characteristics. The numerical computation is performed on turbocharged 5.67L 130PS commercial vehicle diesel engine. The three chemical reactions mechanisms are used for engine performance prediction analysis viz. PSM Mechanism (having 121 species and 593 reactions), ERC Mech reaction mechanism model (having 61 species with 235 reactions) and Chalmers’ reaction mechanism model (having 42 species with 168 reactions) for analyses. The surrogate diesel fuel n-heptane is used in the combustion analysis. By making use of the three-chemistry model, conclusive results indicate significant differences in the computational runtime without much loss in the accuracy of the performance characteristics (expressed as the indicated mean effective pressure (IMEP)).