Combustion Characteristics Research Of Blended Fuel By The Internal Combustion Engine Analysis System Based On Virtual Instrument

The technology of diesel engine and gasoline engine is becoming closer with the evolution of internal combustion engine theories and technologies. Blended fuel (or "flexible" fuel) will be the main form of fuel in future engines. According to the changes in the composition of the blended fuel, engine can organize different combustion mode. So the full understanding of combustion of different blended fuel is very important.In this paper, a internal combustion engine combustion analysis system, which contains two parts of hardware and software, is firstly developed. The hardware consists of cylinder pressure sensor, charge amplifier, optical encoder, filter circuit module and data acquisition card. Engine cylinder pressure signal can be detected, amplified and filleted in hardware. The software includes acquisition card drive module, cylinder pressure data processing module, display module, data storage module and other components. The calculation, analysis and display of blended fuel combustion heat release rate, the average temperature of the cylinder, the rate of pressure rise and the cumulative heat release are able to be completed in these modules. And then gasoline and diesel is blended with the volume proportion of1:2to obtain the reference oil that has the property like crude oil(fuel12). The reference oil is distilled with the boiling range of40～240℃(fuel240),40～270℃(fuel270),40～300℃(fuel300)in distillation still to get blended fuels of different distillates.Finally, the developed combustion analysis system is set on the engine test bench. And the cylinder pressure, heat release, pressure rise rate, average cylinder temperature as well as the emission of NOx and CO of diesel and the four different distillate blended fuel are all investigated by changing the injection timing and rotational speed. The results show that, the cylinder pressure peaks of the five fuels rise with the injection timing advance. The cylinder pressure peaks of the five fuel is substantially same when the injection timing at11.02℃A BTDC. The max cylinder average temperature of diesel is slightly higher than the other four blended fuels. With the injection timing advance, heat release rate curve of the five fuels have a similar shape. Comparing with the blended fuels300,270and240, the ignition timing of diesel is advanced. And ignition timing of fuel12slightly advance than that of diesel when fuel injection timing is0.02℃A BTDC,3.02℃A BTDC and7.02℃A BTDC. When the injection timing is3.02℃A BTDC and7.02℃A BTDC, the cumulative heat release of blended fuels240and300are higher than the one of diesel. When the injection timing is-1.02℃A BTDC, except the diesel, the combustion of other four blended fuels is not ideal, the worst effect of the combustion is the fuel240. When fuel injection timing and fuel injection quantity are constant, the power, torque and the max cylinder average temperature of diesel and fuel12increase along with the increase of engine speed. While the power, torque and the max cylinder average temperature of fuel300and270decrease with the increase of engine speed. CO emissions of Diesel, fuel300,12and270decline obviously with the fuel injection timing advance. CO emissions of fuel240increase first and then decline with the fuel injection timing advance. NOx emissions significantly increase with the fuel injection timing advance.