*Article* **Effect of Combustion Boundary Conditions and n-Butanol on Surrogate Diesel Fuel HCCI Combustion and Emission Based on Two-Stroke Diesel Engine**

**Shiye Wang 1, Jundong Zhang 1,\* and Li Yao 2,\***


**Abstract:** The combustion and emission characteristics of surrogate diesel fuel homogeneous charge compression ignition (HCCI) with different combustion boundary conditions and n-butanol (NB) mixing ratios are studied in this work. Engine data of a two-stroke low-speed direct-injection marine diesel engine were selected for the reactor. HCCI combustion was achieved by compressing a completely homogeneous mixture of fuel and air. The results show that NO emissions decrease slightly with the increase of initial boundary pressure at a constant equivalence ratio and initial temperature. In addition, the different initial boundary temperature has little effect on NO emission. The results also indicate that the ignition delay time of the mixed fuel rises with the increase of n-butanol mixing ratio. The emissions and reaction rate of NOx reduce significantly with the increase of n-butanol percentage in surrogate diesel fuel and n-butanol mixing combustion at a constant equivalence ratio and total mole fraction. Meanwhile, CO2 emissions also decrease significantly with the increase of n-butanol mixing ratio.

**Keywords:** homogeneous charge compression ignition; surrogate diesel fuel; ignition delay; n-butanol; NOx emission
