Study on the Physicochemical Properties and Spray and Combustion Characteristics of 1-Butanol/Diesel Fuel Blends in a Constant-Volume Combustion Chamber

1-Butanol/diesel blend is an ideal fuel for low-temperature combustion (LTC); it has the potential to reduce soot as well as nitrogen oxides (NO X ) simultaneously. To date, comprehensive study on the spray and combustion characteristics of 1-butanol blends has not yet been sufficient, despite these characteristics being significant to the exhaust gas emissions and the combustion system design for engines. In this study, 1-butanol/diesel blends consisting of diesel fuel and 10–30% 1-butanol by volume basis were developed first. Then the study on the physicochemical properties of the blends was presented. Last, the characteristics of nonevaporative spray, evaporative spray, and spray combustion under different environmental conditions were comprehensively examined with the application of the shadowgraph method and Mie-scattering imaging method in a constant-volume combustion chamber (CVCC). The results show that the spray tip penetration and spray cone angle of various fuels under both nonevaporative and evaporative conditions are slightly different. The effects of injection pressure, ambient density, and ambient temperature on the spray characteristics are generally consistent with the classical empirical models. Furthermore, the nature luminosity intensity of spray combustion of diesel is significantly higher than that of the 1-butanol blends. The KL distributions of spray flames for 1-butanol/diesel blends were obtained by the two-color pyrometry method, indicating that the 1-butanol blend is beneficial to reduce soot formation. Moreover, microexplosion may play a significant role on soot reduction instead of the effects of fuel evaporation characteristics.