The effect of temperature and amount of water in co-injection of diesel-water on exergy and irreversibility rate of VGT diesel engine

Abstract

The water introduction to combustion chamber can leave two-sided effect on diesel engine performance, thus its role on combustion must be delineated. Accordingly, three levels of water amount in 14.21, 21.31, and 28.41 mg/cycle are adopted to be injected from an upper angled nozzle hole, while fixed diesel amount of 31.3 mg/cycle is injected at 3 °CA BTDC from lower angled nozzle. The water temperature is also taken into account in two levels of 27 °C and 60 °C. By high water injection (HWI) at 60 °C, the rate of pressure rise increases by 17.1% compared to the base case (no water injection) due to steam pressure in the cylinder. The results indicate that WI scheme is effective for fuel consumption, NOx, and soot reduction. In terms of exergy balance by input fuel exergy, it is concluded that the more heat loss exergy is transferring to work exergy in low and medium water injection, while the fuel burn exergy increases drastically. Altogether, the case of diesel injection with high water amount at 27 °C water temperature, i.e. “diesel-HWI-27 °C” is recommended from exergetic viewpoint since it represents the highest total exergy (838.31 J) and the lowest irreversibility (132.98 J).