Combustion, performance, and emissions of safflower biodiesel with dimethyl ether addition in a power generator diesel engine

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ABSTRACT In this study, the effect of dimethyl ether (DME) addition to diesel (ultralow sulfur diesel fuel) and biodiesel fuels on the combustion, performance, and emissions of a diesel-powered generator was investigated. For this purpose, fuel samples of the ternary blend that volumetrically composed of 10% safflower biodiesel–10% dimethyl ether–80% ultralow sulfur diesel fuel (B10DME10), the ternary blend that volumetrically composed of 25% safflower biodiesel–25% dimethyl ether–50% ultralow sulfur diesel fuel (B25DME25), the binary blend that volumetrically composed of 25% safflower biodiesel–75% ultralow sulfur diesel fuel (B10DME10) B25, and pure safflower oil biodiesel (B100) and standard ultralow sulfur diesel (D2) were prepared. The test engine was loaded by power drawing from the generator by the usage of equivalent powered electrical heating resistances. Generally, using DME with biodiesel improved the combustion properties of biodiesel blends that can be attributed to the lower viscosity of DME. The maximum cylinder pressure was obtained for B10DME10 in general and sometimes for B25DME25. When test fuels are compared, DME blends showed higher and earlier peaks of heat release compared to diesel and biodiesel blend fuels especially. It was found that combustion is more efficient from mass fuel consumption (MFC) and brake specific fuel consumption (BSFC) values in the use of DME than biodiesel. BSEC values of using DME in the blends considerably decreased that it is the proof of improved combustion and energy efficiency. The highest average efficiency values were obtained for B25DME25 as 28.3% although it has a lower calorific value than D2 due to the considerably improved combustion properties of DME, while the average efficiency values were 23.1%, 23.3%, and 20.7% for D2, B25, and B100 fuels, respectively. Highest carbon monoxide (CO) emissions were obtained in the use of pure biodiesel, while the lowest CO emissions were obtained in the use of DME. The addition of DME is seen to increase the nitrogen oxides (NOx) and CO emissions.