Study On Evaporation And Combustion Characteristics Of Single Droplet Of Graphite-n-decane Nanofluid Fuel

As the main source of energy consumption in the world for a long time,fossil energy has always been unsustainable and low thermal efficiency.At present,various new energy sources are difficult to overcome in a short time due to technical difficulties,and it is temporarily difficult to replace fossil energy.Therefore,it is necessary to improve the thermal efficiency of fossil fuels.In recent years,the rise of nanofluid fuels has provided a new direction for improving the thermal efficiency of traditional fossil energy sources.There are few studies on the use of carbon nanoparticles as nanofluid fuel additives in academia.Therefore,this paper takes graphite-n-decane nanofluid fuel as the research object,and studies the evaporation and combustion characteristics of its single droplet.Firstly,the preparation method of nanofluid fuel was studied and its optimal suspension stability parameters were explored.A two-step method was used to prepare graphite-n-decane nanofluid fuel suspensions with different surfactants and graphite concentrations.The experiment found that when 1)the graphite concentration is below1 Wt.%,2)the surfactant is SP80 and the concentration is 0.5Vol.%,3)When the ultrasonic oscillation time is 10 mins,the suspension stability of the suspension is the best.Secondly,the influence of graphite concentration on the physical parameters of nanofluid fuel was studied.The experimental results show that with the increase of graphite concentration,1)the density of nanofluid fuel increases linearly,2)the viscosity coefficient increases with second-order fitting,and 3)the surface tension coefficient first increases and then decreases.Finally,a hanging drop test device was built to study the evaporation and combustion characteristics of a single drop of nanofluid fuel.The study found that the evaporation rate of a single drop of nanofluid fuel 1)increases with the increase of heating temperature,2)decreases with the increase of surfactant concentration,and 3)increases first with the increase of graphite concentration and then reduced.With the increase of graphite concentration,the ignition delay of a single droplet of nanofluid fuel first decreases and then increases,and the combustion rate first decreases and then increases.The average temperature of the droplet surface in the initial evaporation stage of the droplet increases and the maximum temperature decreases.From the experimental results stated above,it can be concluded that for graphite-ndecane nanofluid fuel,at low concentrations(<1Wt.%),the addition of nano-graphite does have a better effect on the evaporation and combustion characteristics of n-decane liquid.But at high concentrations(≥1Wt%.)it has a negative effect.Moreover,the low-concentration graphite-n-decane nanofluid fuel has both excellent suspension stability and good economy.This work will help to improve the understanding of nanofluid fuel stability,physical parameters,evaporation,ignition and combustion characteristics,and have reference significance for the development of new energetic nanofluid fuels.