Impact of Port High-Pressure Injection Timing and Direct Injection Timing on Combustion and Emission of Ethylene Glycol/Diesel Dual-Fuel Engine

In this work, a comparative study on the effects of ethylene glycol high-pressure injection timing (TEG) and diesel pre-main injection timing interval (TIN) on the combustion and emission characteristics of a diesel–ethylene glycol dual-fuel engine was conducted experimentally. Three TEG namely 0, 240, 480 degree crank angle (ºCA), and four TIN namely 8, 10, 12, 14 ºCA were conducted. All experiments were conducted at an engine speed of 1600 rpm with a brake mean effective pressure (BMEP) of 0.7 MPa. The experimental results show that under the same TIN conditions, the variations of the pressure and heat release rate (HRR) of three TEG with the crank angle are basically the same. The ignition delay period under different TEG increases almost linearly with the increase of TIN, and the combustion durations lengthen with the increase of TIN. The brake thermal efficiency (BTE) decreases with the increase of TIN. When TIN is 8 and 12 ºCA, the cyclic coefficient of variation in peak cylinder pressure ( \(COV_{{P_{max} }}\) ) is relatively larger. The oxides of nitrogen (NOx) emission of the same TEG decreases with the increase of TIN, and the NOx emission is the lowest when TIN is 12 ºCA. The peak number concentration of ultrafine particles increases with the increase of Tin, and the corresponding particle diameter decreases. The weighted mean diameter of ultrafine particles gradually decreases with the increase of TIN. In summary, when the TEG is 0 ºCA and TIN is 12 ºCA, the dual-fuel engine has great combustion and emission performance.