Numerical Study of the Effect of Adding Water with Different Temperatures to Low-Reactivity Fuel in a Reactivity Controlled Compression Ignition (RCCI) Engine

Reducing fuel consumption and emissions, as well as increasing the power and efficiency, have always been important in IC engines researches. Due to the positive effects of adding water to the inlet fuel-air mixture through the manifold of a low-temperature engine, the effect of the temperature of water added to the low-reactivity fuel in an RCCI engine with gasoline-diesel dual-fuel has been investigated. The water temperature varies between [20-60]oC. Water is substituted for gasoline with different mass-ratios; so that the reduction of fuel will be equal to the amount of water added. For numerical simulation, the AVL-Fire was used as a couplet with the detailed chemical kinetics code. For validation, numerical results are compared with similar experimental data. The results show that by increasing the mass-ratio of the replaced water up to 10%, the in-cylinder pressure and temperature as well as the NOx increase significantly; but with an increase in mass-ratio to 15%, a decreasing trend is seen. With the increase in the mass-ratio to 20%, it will again lead to an increasing trend; however, at this mass-ratio, the in-cylinder temperature, and the NOx have not increased significantly, despite the increase in power characteristics. Then, considering the mass-ratio of 20%, the evaluation of water temperature increasing shows an improving trend; so that the maximum average in-cylinder pressure is increased and leads to a slight increase in the IMEP. Also, due to the increase in combustion quality, CO is significantly reduced, as well as the ISFC is reduced up to 2%.