The development of F-76 and algae-derived HRD-76 diesel fuel surrogates

The surrogate models for HRD-76 and F-76 diesel fuels to capture their combustion properties were developed in the present study. n-C16H34 (n-hexadecane), C15H32-26X (2,6,10-trimethyl dodecane) and C6H5C4H9 (n-butylbenzene) were chosen as surrogate components, and formulated by the FGBS (Function Group Based Surrogate Fuel) methodology. The HRD-76 surrogate consists of 58.0% n-C16H34 and 42.0% C15H32-26X, and the F-76 surrogate consists of 41.0% n-C16H34, 24.0% C15H32-26X and 35.0% C6H5C4H9 by mole fraction, were determined by directly matching four functional groups that obtained from the NMR (Nuclear Magnetic Resonance) spectroscopy analysis. A detailed kinetic mechanism was constructed and then reduced by a kinetic model reduction scheme. After that, the merged surrogate kinetic mechanism was verified against various experiments for each individual surrogate component. Furthermore, the HRD-76 and F-76 surrogate fuel models which contain the determined surrogate formulation and developed surrogate mechanism were validated against experiments. The agreements between the simulation results and the experiments on ignition delay times (IDTs), laminar flame speeds (S0u) and extinction strain rates (Kext) are reasonably good. Based on sensitivity analysis, key reactions of HRD-76 and F-76 surrogate fuels were compared and analyzed. This study can help understand the combustion characteristics of HRD-76 and F-76 fuels in deeply, and lay the foundation for the engine combustion simulation using the CFD.