An Incestigation Of The Combustion Characterstics Of Diesel Engine Running With Fischer-Tropsch Diesel And No.0Diesel

The pressure from energy and environmental has increased rapidly with the increase of motor vehicle population. Fuels from coal to liquids have significant development prospects the regions where coal resources are rich. In this investigation, combustion characteristics of three different proportions of F-T diesel blended with NO.0diesel (F10, F30and F100in volume) were studied and compared with pure NO.0diesel to understand the power performance, economical efficiency and emission characteristics based on a four cylinder diesel engine for the frist time. Results showed that the output power and output torque with blended fuels have slight reduction whereas the economic varies with different blends. The blended fuels with low component of FT diesel have little effects on the fuel consumption rate and the effective thermal efficiency. The pure FT diesel has shown advantaged economical efficiency. With the increase of the F-T diesel mixing ratio, NOx, soot and HC showed a gradual decrease trend, but CO showed worse results.The analysis of indicator diagrams found that with the increasing ratio of FT in the blends, the peak value of cylinder pressure exhibits a gradual increase with a gradual delay in the phase of peak values. However, the peak of pressure rise reduces gradually andthe corresponding phase of the peak gradually advances. The pressure rise acceleration gradually decreases and the corresponding phase of peak gradually advances, which is helpful for reducing dynamic load and extending the life and reliability of engines using F-T blends.To gain in-depth understanding of the changes found above, this research has developed a software package for the heat release rate analysis of FT blended fuels, which allows more details of combustion process of different fuel blends to be examined. It has found that with increasing the F-T ratio, the ignition delay period reduces gradually and the average reduction ratio increases with engine speed. Main combustion period gradually extendsin which the rapid combustion period gradually shorten and the shortening degree gradually increases with speeds. The normal combustion period become longerat medium and low speeds butat high speed it is shorter forF10and F30and longer for F100. The post combustion period becomes longer at low and high speed while shorter at medium speed. The mixing ratios of FT diesel produce a clear influence on combustion roughness, the peak of heat release rate showinga graduall decrease, corresponding phase of peaks gradually advanced with the increasing of mixing ratio of FT diesel. The ratio of mixing also has an influence on the burning structure, the percentage of heat release are increased with the increasing of mixing ratio at low speed, and the exothermic center of gravity advances. The exothermic center of gravity of FT blended fuel retard gradually with increasing of speed. The percentage of heat release of normal combustion period increases with the mixing ratio of FT diesel at low speed but it is higher than FO at medium speeds under low loads, and little difference has been found at medium speed withhigh load, while there is little change at high speed. The rapid/normal combustion coefficient gradually decreases as the increasing of mixing ratio of FT diesel at low speed, while the differences of fuels gradually decreased with increasing of speed. These combustion characteristics shows that to obtain optimal combustion different fuel blends have to be used under diiferent operating conditions. The results of simulation analysis using FIRE software show that temperature of the cylinder can be reduced by using F30, helping to reduce NOx emissions.The use of FT diesel mixed with diesel can be taken as a kind of clean fuels which meet more the energy distibutions in our country and henceit has great prospects for further development.