Research on fuel spray characteristics of coal-made Fisch-Tropsch process diesel/methanol

Abstract

ABSTRACT Fuel spray characteristics have a big influence on the combustion process and pollutants of diesel engines. The physical characteristics of fuel such as latent heat of vaporization, density and viscosity are also changed when methanol is added to the fuel, resulting in changes in fuel transport characteristics and spray characteristics, which affect the combustion process. A high-pressure common rail spray characteristics visualization platform was built to assess the spray characteristics of diesel, Fischer-Tropsch process diesel and Fischer-Tropsch process diesel mixed with 5%, 10% and 15% methanol. The spray penetration distance, spray projection area and spray cone angle of the five fuels were measured under various injection pressures and back pressure conditions. In addition, the influence of the physical characteristics of the fuels on the spray characteristics was analyzed. The results showed that the spray penetration distance of Fischer-Tropsch diesel/methanol blends changed by about 2%, the spray cone angle elevated by 1%-5%, and the spray projected area increased by 10%-23% when the back pressure ranged from 120 to 160 MPa. When the back pressure was constant and the injection pressure was increased from 120 to 160 MPa, the spray penetration distance of Fischer-Tropsch process diesel/methanol blends increased by about 13%, the spray cone angle increased by about 4%, and the spray area increased by 9% to 33%. Our results provide a basis for the application of Fischer-Tropsch process diesel/methanol blends in diesel engines.