A Study Of Influence On Diesel Engine Performances Burning Coal Based Fischer—Tropsch Alcohol Mixed Fuel

With the increase in vehicle populations, enengy shortage and environmental pollution have become two major problems of facing the development of internal combustion engine, so looking for alternative fuels to alleviate the energy crisis, reduce pollutant emission has become a top priority of the moment. And extensive coal combustion is thought to be the main reason for the pollution haze, vigorously develop clean coal utilization, clean coal using and internal combustion engine alternative fuel development in combination, to promote the transformation of coal enterprises, to alleviate the energy crisis and pollution from the source to the terminal control has important sustainable development meaning.Combined with the advantages of large province of Shanxi coal advantage in energy and coal chemical industry development, Fischer-Tropsch diesel of coal to liquefaction fuel was used in diesel engine, F-T diesel fuel can reducethe NOX emission because of its higher cetane, but this may be increasing the proportion of diffusion combustion,thus appeared the trend of the soot emission increasing. Alcohol fuel is a kind of widely ued oxygen fuel, so chose F-T diesel blending alcohols fuels to achieve the NOX and soot emissions decreased synchronously.Due to F-T diesel fuel and alcohol fuels are not miscible. In order to solve the stability problem of the mixed fuel, Firstly, F-T diesel fuel and alcohol fuel solubility is studied example for F- T diesel and methanol, electing to the best effect of Decyl Alcohol as the solvent with the help of the mixed fuel, preparation of 10% volume ratio of coal based alcohol fuel mixture remember M10?E10 and N10, testing or calculating the physicochemical properties of mixed fuel are as follows: with the respect to 0# diesel, cetane number, c(H) / c(C) and oxygen content of mixed fuel increased, sulfur content, dynamic viscosity, volume of the low calorific value and density decreased. These physical and chemical characteristics have a direct impact on engine performance.Then, the the effects of physicochemical properties of mixed fuels on combustion, dynamic economy, conventional and unconventional emission and vibration characteristics were studied by engine bench test. The high cetane property of mixed fuels maked lag ignition and premixed combustion period between 0# diesel and F-T diesel, and diffusion combustion is the opposite. Peak of cylinder pressure and combustion heat release rate diesel was reduced, cylinder pressure peak phase was delayed and the combustion heat release rate peak was advanced and the combustion heat release center CA50, means the crankshaft angle corresponding to 50% of the total heat release, was postponed relative to 0# diesel. the lower volume calorific value of alcohol caused dynamic performance reduced by about 10%, quality calorific value of mixed fuel decisied the fuel consumption rate has increased, the effective thermal efficiency decreased,compared to the 0# diesel. The higher cetane and oxygen of mixed fuels maked soot and NOx reduced synchronously to solve the trade-off relationship between NOx and soot emissions. Higher heat of vaporization value of alcohol fuel caused the HC emissions increased, with higher c(H) / c(C) and oxygenated characteristic makes CO emissions decreased significantly, mixed fuel alcohol emission mainly comes from the mixture of unburned ethanol, thanks to the mixed fuel on the basis of F-T diesel fuel, formaldehyde emissions have greatly reduced.The vibration amplitude of 0# diesel was minimum, mixed fuels increased. Among the head vibration signal of the diesel engine, vibration acceleration amplitude maximum caused by the combustion inspired, the minimum caused by the intake valve opens along with gas shock, the valve is opened the gas shutoff valve closed is less than the valve seating, The dimension parameters value of 0# diesel was the biggest, F-T diesel was the smallest, and the mixed fuel fell in between, and the corresponding dimensionless parameters were on the contrary, under the same load.Integrated on three kinds of mixed fuel preparation and experiment analysis, the mixed fuel can reduce diesel engine soot and NOx emissions synchronously, the M10 had more obvious effectiveness, meanwhile it showed the characteristics of combustion softer, improving the vibration characteristics of diesel engine.