WATER-DIESEL EMULSION: A REVIEW

Due to its impact on human health and the nature surrounding us, diesel engine emissions have been significantly reduced over the last two decades. This reduction has been enforced by the legislating organs around the world that gradually have made the manufacturers transform their engines to today's complex high‐tech products. One of the most challenging area to meet the legislations is the emissions of the diesel engine which are the products of the combustion of diesel fuel. More restrictions have been imposed by the some governments to reduce these emissions to a level such that will not cause any harmful impacts for the environment after releasing them to the atmosphere. This paper examines the effects of combusting a mixture of diesel fuel, water, and surfactant which forms emulsion on the nitrogen oxides, or NOx, carbon monoxide CO, carbon dioxide CO2, sulfur oxides SOx emissions and particulate matter (PM) from a compression ignition diesel engine. Previous research has attributed the observed reduction of these emissions to a suppression of flame temperature due to quenching effects from the water, thereby reducing thermal NOx formation and other pollutants. The focus of this review paper will be on experiments were conducted a using diesel engine with pure diesel fuel and emulsion of water-diesel. Furthermore, results from the testing diesel fuel that mixed with varied ratios of water balanced with a surfactant to stabilize the emulsion will be presented and discussed. Three different samples of water- diesel emulsion were used with 10 % water and 90 % diesel, 20 % water and 80% diesel, and 30 % water and 70 % diesel (by volume) respectively to conduct the experiments in the lab . The purpose was to see the impact of adding the water from 10 % up to 30 % (by volume) to the diesel fuel making the emulsion fuel to explain what will occur to the emissions and the performance of the engine. The data shows significant NOx emission reduction when using the emulsion water diesel fuel of 30 % water (by volume) in diesel. These results are correlated with a thermodynamic first law analysis to estimate the adiabatic flame temperature of the standard fuel and fuel-water emulsion cases. Results indicate that thermal NOx is indeed reduced by quenching and flame temperature suppression confirming reports in the literature. Recommendations are given for further studies, including improving the fuel—water emulsion and considerations for long-term testing.