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In this paper, an experimental study has been conducted to study the effects of iso-alkanes blending in diesel on combustion and emission characters based on a modified single cylinder diesel engine. Iso-octane, iso-dodecane and 2,2,4,4,6,8,8-heptamethylnonane (HMN) were chosen as test iso-alkanes. The direct injection timing was kept at 7 oCA BTDC. The injection pressure was maintained at 120 MPa. The study found that iso-alkanes had strong effects on the heat release phase under low load. The effects were weakened gradually with the increase of loads. The peak value of heat release curves and the maximum pressure rising rate gradually increased with the increase of loads. Blending iso-alkanes resulted in the increase of CO emissions and decrease of HC emissions. NOx emissions also decrease under low loads. Under high loads, blending iso-alkanes reduced the soot emissions significantly.

The ignition delay time of toluene reference fuels composed of iso-Octane, n-heptane and toluene was studied in a shock tube under the conditions of medium to high temperature ranges, different pressures (10-20 bar), and various equivalence ratios (0.5,1.0,1.5 and 2) by reflected waves.Three different ternary blends, TRF2 (42.8% iso-Octane/13.7% n-heptane/43.5% toluene), TRF3 (65% iso-Octane/10% n-heptane/25% toluene) and TRF4 (87.2% iso-Octane/6.3% n-heptane/6.5% toluene), with the same Research Octane Number of 95 (RON=95) were constructed. The experimental results showed that there was an obvious negative correlation between the ignition delay time of the toluene reference fuels and the pressure, temperature and equivalence ratio; and, a minimal discrepancy of TRF2, TRF3, and TRF4 was measured at pressures of 10 and 20 bar in a stoichiometric ratio. A detailed chemical mechanism was established to research the surrogate combustion properties.