Temperature, Combustion, and Emissions on a Diesel Engine Using N-Butanol/Diesel Compound Combustion Mode

By adding an injection system of n-butanol on the intake manifold, the four-cylinder direct injection (DI) diesel engine had been modified to operate in n-butanol/diesel compound combustion mode (BDCC). Effects of temperature, combustion, and emissions were experimentally investigated on this experimental engine. The temperature, combustion, and emissions characteristics were compared between the original neat diesel mode and the BDCC mode. The engine speeds were set to be 2,250, 2,800, and 3,350rpm, and the engine loads were set to be 25, 50, 75, and 100%, respectively. The experimental results demonstrated that the intake temperature, the combustion temperature, and the exhaust temperature were decreased under BDCC mode, compared with that of the original neat diesel mode. The form of heat release rate was significantly changed using the BDCC mode, and the maximum combustion pressure of BDCC mode was higher than that of diesel mode. Under the low load, the ignition delay of BDCC mode was longer than that of original neat diesel mode, which caused the heat release was much more centralized and the peak of heat release was much higher. Under the high load, BDCC mode had two peak values of the heat release rate, the first small peak was formed by the small partial self-ignition of n-butanol, and the second peak was formed by the heat release of n-butanol and diesel compound combustion. The diesel engine operating with the BDCC mode could simultaneously reduce the NOx and soot emissions but increase the total hydrocarbons (THC) and carbon monoxide (CO) emissions compared with the original neat diesel engine.