Experimental and numerical study on the effect of single-hydroxybenzene/n-heptane blends on engine combustion and particulate emissions

Abstract

Understanding the influence of the primary components of diesel on engine combustion and emissions is essential to the construction of a model diesel fuel. In this study, straight-chain alkanes in diesel are represented by n-heptane, and aromatic hydrocarbons are represented by toluene, n-butylbenzene, and 1,2,4-trimethylbenzene. The effect of single-hydroxybenzene/n-heptane blended fuel on engine performance and particle emission characteristics is studied experimentally and by simulation to identify an optimal composition for a model diesel fuel. The test fuels were pure diesel (D100) and single-hydroxybenzene/n-heptane blends (toluene, n-butylbenzene and 1,2,4-trimethylbenzene each of which was added to n-heptane at a volume ratio of 20% (T20, BBZ20, TMB20) or 30% (T30, BBZ30, TMB30)). The results show that as the EGR rate increases, the total particle number concentration (TPNC), particle size distribution concentration (PSDC), total particle mass concentration (TPMC), and particle geometric mean diameter (PGMD) increase. The peak heat release rate (HRR) and peak in-cylinder pressure (IP) of single-hydroxybenzene/n-heptane are higher than those of D100; however, the values of PSDC, TPNC, TPMC, and PGMD are lower than those of D100. Among the tested fuels, the effects of n-butylbenzene/n-heptane blend on engine performance and particle emission characteristics are closest to D100. The spatial distribution of temperature field, equivalent ratio, OH-groups and NO of BBZ20 are close to that of D100. The n-butylbenzene/n-heptane fuel is suitable for modeling diesel, particularly when the addition ratio of n-butylbenzene is 20%, the combustion and emission characteristics are the closest to those of D100.