Effect of Fuel Physicochemical Properties on Spray and Particulate Emissions

To investigate the effect of fuel physicochemical properties on spray and particulate emissions, fuel spray characteristics were tested on a constant volume chamber (CVC) test rig using a high-speed camera method to investigate the effect of different injection and ambient pressures on spray characteristics. In the engine bench tests, the effects of particulate emissions from five different diesel fuels with different physicochemical properties were analyzed under low-, medium-, and high-load steady-state conditions and 5 s transient loading conditions. The test results showed that the spray tip penetration of different CNs results from the combined effect of the fuel properties. The spray cone angle of the five fuels increased with the increase of injection and ambient pressure, and the impact of ambient pressure on the spray cone angle was more prominent. Spray tip penetration and spray projection area increase with increased injection pressure and decrease with increased ambient pressure; compared with spray tip penetration, the spray cone angle has more influence on spray projection area, especially near-field spray cone angle as the primary influence factor. Fuels with different ignition characteristics have other effects on particulates at different loads. At low loads, choosing CN = 55.3 fuel improved the number and mass of particulates; at medium and high loads, choosing CN = 51 fuel reduced the number of particulate emissions. Fuels with different volatilities have different effects on particulates at other loads. At low loads, CN = 54.9 fuel was chosen with moderate volatility and aromatic content. At medium and high loads, the volatility of the fuel had a lower weight on particulates, and the aromatic content had a higher weight. Under the transient loading condition of 5 s, using fuel with a higher CN, good volatility, and lower aromatic content can appropriately reduce the number of particulate emissions.