Study On Electrostatic Break-up Characteristics Of Al/N-Decane Nanofluid Fuel

In recent years,nanofluid fuels have received extensive attention due to their excellent heat transfer,mass transfer characteristics,and high heat of combustion.In order to make combustion performance better,it is necessary to atomize the nanofluid fuel,and electrostatic atomization is one of the optimal atomization methods for the nanofluid fuel.The addition of nanoparticles changes the physical properties of the base fluid,including thermal conductivity,heat transfer coefficient,density,viscosity,electrical conductivity,and surface tension.Under the action of an electric field,the nanoparticles also have significant effects on the charge and fragmentation of the base fluid.In the literatures reported,there is few systematic study on the combined effect of nanoparticles and electrification on the fragmentation of nanofluid fuels.Therefore,this paper selects the Al/n-decane nanofluid fuel system as the research subject,and focuses on the effects of Al nanoparticle concentration and size on the physical parameters,agglomeration and sedimentation characteristics,and the electrostatic break-up characteristics under the synergistic effect among particle concentration,particle size and electrification.The stability analysis of Al/n-decane nanofluid fuel was carried out by static observation,microscopic observation and dynamic light scattering measurement(DLS).The results show that due to the existence of Brownian motion,the nanoparticles will agglomerate to form larger particles,and the agglomerated particles accelerate the sedimentation.Besides,the effects of nanoparticle concentration,particle size and surfactant on the agglomeration and sedimentation of nanofluid fuel were analyzed and discussed.Under the action of a certain concentration of surfactant,the increase of Al nanoparticle concentration leads to a linear increase in density,a trinomial increase in viscosity,however,piecewise influence on surface tension.An increase of Al nanoparticle size causes a decrease in surface tension,an increase in the viscosity,and nearly constant in density.In the electrostatic field,the Al nanoparticle affects the electrification of the nanofluid fuel,which promotes the deformation of the Taylor cone and the break-up of the jet.As the concentration of nanoparticles increases,due to the synergistic effect of concentration and charge effect,there is a critical concentration that minimizes the effective surface tension,thereby achieving optimal break-up performance.For the Al/n-decane nanofluid fuel,the theoretical critical calculation results are agreement with the experimental results.As the concentration is below the critical value,the higher the concentration,the smaller the particle size of the break-up droplets become.For Al nanoparticles with different particle sizes,the Al/n-decane nanofluid fuel has a great influence under the combined action of the charging effect.The experimental results show that the Al nanoparticle with a median diameter of 93.4nm minimize the break-up droplets size of the electrostatic break-up of the Al/n-decane nanofluid fuel.