Experimental Analysis of Effect of Orifice Diameter on Combustion and Emission of Biodiesel Supercharged Engine

In with the increasing number of automobile ownership and the increasingly stringent emission regulations, the development of clean energy has become an important issue in the field of energy and environment at present. In this paper, combustion and emission experiments of biodiesel supercharged engine were conducted to investigate the effects of orifice diameter (6×0.24mm, 6×0.35mm), engine speed (800r/min, 1400r/min), and engine load (25%, 50%, 75%, and 100%) on combustion and emission characteristics. In this paper, build a biodiesel boost injection system on the test bench, where the fuel is boosted by a high-pressure pump and injected directly through the injector via a high-pressure fuel pipe. The length of the high-pressure oil pipe is 91cm; The nozzle diameters are 6x0.24mm and 6x0.35mm, respectively, with an injection pressure of 24MPa. Real time monitoring of the pressure at the pump end and nozzle end of the fuel pipe. In the experiment, the rotational speeds of the high-pressure pump were 800r/min and 1400r/min. The results showed that for emission characteristics, at a certain rotational speed and load, the use of orifice diameter 6×0.35 mm resulted in larger carbon monoxide emission, hydrocarbon emission and carbon smoke emission and smaller NOx emission from the engine. In terms of combustion characteristics, the cylinder pressure, heat release rate, and pressure rise rate peaks are higher with orifice diameter 6×0.24mm than with orifice diameter 6×0.35mm.The pressure rise rates of both orifices have two peaks, with the first peak basically overlapping, and the orifice diameter mainly affects the second peak, and the second peak is higher with orifice diameter 6×0.24mm, and the difference is not obvious after the second peak. The cylinder pressure peak at 1400r/min is higher than the peak at 800r/min, and the peak phase is delayed. The pressure rise rate at both speeds showed a double peak, the second peak of the pressure rise rate at speed 800r/min was high and the first peak at speed 1400r/min was high.