AbstractThe high-pressure injection strategy for di-n-butyl ether (DBE)-diesel fuel blends reduces particulate matter emissions. Exhaust gas recirculation (EGR) technology was used to decrease NOx emissions. In this study, the combustion and emission characteristics of DBE blended fuel under the coupling of EGR and injection pressure (IP) were investigated using a turbocharged compression ignition (CI) engine. Furthermore, to understand the effect of fuel blends on particulate matter emissions, the emission levels of particulate matter were analyzed for four particle size ranges of different EGR, IP, and fuels. The results show that BD40 reduced CO emissions by 37.3% and soot emissions by 69.8% and increased NOx emissions only slightly. The use of EGR significantly reduced NOx emissions from DBE/diesel. The coupling of EGR with BD40 broke the NOx-soot emission balance. In addition, without EGR, BD40 reduced the DP<20 nm particle number concentration by 52.5% compared to D100. By increasing IP from 60 to 120 MPa, DP<20 nm particle number concentration of BD40 was reduced by 30.2%. Therefore, the use of 25% EGR and 120 MPa IP helps to decrease NOx emissions, soot emissions, and fine particulate matter emissions of BD40.