Parametric study of a single-channel diesel/methanol dual-fuel injector on a diesel engine fueled with directly injected methanol and pilot diesel

Abstract Diesel/methanol dual-fuel injectors can achieve dual direct injection of diesel and methanol without modifying the cylinder head structure. Owing to the complex structure and high cost of the dual-channel dual-fuel injector, a single-channel dual-fuel injector is proposed and investigated. The effects of residual methanol volume (Vrm), diesel amount, nozzle diameter, and injection pressure on combustion characteristics and engine performance are investigated. Ignition delay increases with the rise of Vrm, and the negative effect of residual methanol on the auto-ignition of diesel can be weakened by increasing diesel amounts. Furthermore, Vrm does not affect fuel economy much, but higher Vrm makes knock more likely. There is an optimal diesel amount, that is, diesel energy should account for 10% of the total fuel energy (Rd10%), and knock is prone to occur if diesel amounts are too large or too small. Lastly, a nozzle diameter of 0.36 mm paired with an injection pressure of 27.4 MPa (0.36 mm + 27.4 MPa) yields the best engine performance, one that is comparable to the dual-channel injector of 0.4 mm + 18 MPa.