Comparing the Operation of a High Speed Direction Injection Engine Using MVCO Injector and Conventional Fuel Injector

摘要

The operation of a small bore high speed direct injection (HSDI) engine with a MVCO injector is simulated by the KIVA 3V code, developed by Los Alamos National Laboratory. The MVCO injector extends the range of injection timings over conventional injectors and it extra flexibility in designing injection schemes. Combustion from very early injection is observed with MVCO injections but not with conventional injection. This improves the fuel economy of the engine in terms of lower ISFC. Even better efficiency can be achieved by using biodiesel, which may be due to extra oxygen in the fuel improving the combustion process. Biodiesel sees a longer ignition delay for the initial injection. It also exhibits a faster burning rate and shorter combustion duration. Biodiesel also lowered both NO_x and soot emissions. This is consistent with the general observation for soot emissions. The cylinder is under lower temperature upon main injection with biodiesel due to the longer ignition delay for the initial injection. This may explain the lower NOx emissions by biodiesel.