The diesel engine is a well-known source to supply energy for vehicles such as marine transportation, industrial sectors, road vehicles. However, the large quantity of diesel engine usages in current scenario tends to environmental hazards and that affects the living organisms in a universe. Nowadays, numerous researches have been performed for diminishing the emission of hazardous gases from a diesel engine. For that, the desired amount of water is blended with the engine oil to minimize the particulate matter (PM), carbon monoxide (CO), nitrogen oxides (NOx) emission, and so on. Moreover, thermal effectiveness of the diesel engine was enhanced with the help of emulsion fuel technique. Henceforth, the current investigation presents a review of water emulsified diesel (WED) fuel performance in the traditional diesel engine. Moreover, this paper is mainly focused on the assessment of emission analysis, combustion of fuel, and physical properties of water–diesel emulsion for the diesel engine. The usage of emulsified fuel has enhanced diesel engine operation.
Furthermore, the optimal blend ratio improves the fuel-efficient and reduces fuel emission. The entire research papers of all parameters are compared to validate the effectiveness and improvement of engine performance.