Role of water micro-explosion on fuel droplet size distribution, engine performance, and emissions in a water-diesel emulsified engine: A comprehensive numerical investigation

Abstract

The global warming crisis and strict regulations have pushed the automotive industry into technological change, but it will take time, so finding quick solutions can be very helpful. Using water in diesel emulsion is one of the low-cost and fast solutions to reduce pollution and improve the performance of diesel engines. In this study, the effects of adding water to diesel fuel and the phenomena that occur when water enters the combustion chamber are investigated. For this purpose, a simulation of a four-cylinder diesel engine has been used with different content of water in diesel (0% or pure diesel, 5%, 10%, 15%, and 20%). The simulations are performed in Converge CFD using dynamic mesh and adaptive mesh refinement. The results showed that the use of water in diesel leads to an improvement of about 10% in engine indicated power and a simultaneous reduction in soot and NOx by 10 and 30%, respectively. The simulation results showed that water droplet micro-explosions accelerated the fuel droplet breakup process and reduced the combustion duration by 10%–30%.

Hydrocarbon Degradation by Contact with Anoxic Water Microdroplets

“…In this regard, it is well-known that adding water to diesel oil to form a fuel emulsion is advantageous in providing diesel engines more power and less pollution from unburnt hydrocarbons and NO x . , A number of reasons have been advanced to explain this fact: , the reduction of the maximum temperature of the combustion chamber that can reduce NO x formation owing to the large latent heat for water evaporation, the accelerated oxidation of soot by reaction with water, and microexplosions of evaporating water droplets that can increase fuel-air mixing and reduce soot formation. We hypothesize that the ability of water microdroplets to transform long-chain hydrocarbons to short-chain hydrocarbons and to produce H 2 might be another important contributing factor.…”

Effects of Surfactant Characteristics on Fuel Properties of Emulsions of Alternative Engine Fuel through the Phase Inversion Method

“…The secondary atomization of the injected fuel droplets would occur when the emulsion is burned. The water droplets of a dispersed phase are heated, evaporated, and expanded outwards due to the water's relatively lower boiling point in comparison with that of an enveloping oil layer to facilitate the phenomenon of micro-explosion [3]. The total contacting surface and mixing extent between atomized liquid fuel droplets and surrounding air becomes much more increased and intense, leading to a significant enhancement of the reaction rate and, thus, a higher degree of burning efficiency.…”