Investigation of dual fueled (Diesel-Natural Gas) diesel engine ignition delay in different loads, pilot injection timings and quantities

Ignition delay time is an important factor in internal combustion engines design, performance and emissions. In this work, ignition delay time of dual fueled (Diesel – Natural Gas) diesel engine with constant speed in 1500 rpm and 44 kW was investigated. Experimental tests done with diesel in different loads and fuel injection timings primarily and then engine converted to dual mode and experimental tests continued in various loads (10%, 25%, 50%, 75% and 100 of full load) and different pilot advance timings (20, 17, 14 crank angle degree before TDC) and different pilot fuel to gaseous fuel ratios (50%, 40%, 30%). Results shown that by increasing engine load, ignition delay decreases in both diesel and dual mode. Ignition delay time in diesel mode was lower than dual mode in all of condition of the tests. In dual mode increasing pilot injection timing decreases ignition delay time, although, in diesel mode it was non – significant. Numerical simulations done for estimating ignition delay time in different conditions of the tests. Simulations results shown that suggested model can estimate ignition delay time in dual fueled engine and have a good agreement with experimental results.