| Petroleum is one of the main fuels of modern industry,causing extensive environmental pollution and damage to the ecological environment,posing a serious threat to the global climate and human health.In recent years,a representative clean energy is nanofluid fuel.This type of fuel has the advantages of high energy density,wide natural storage,easy storage and convenient transportation,and low environmental pollution.It has attracted attention in the scientific community,but its evaporation mechanism is not yet clear.The basic fuel in this thesis is butanol diesel fuel.Stable nano-fluid fuel is made by adding nano-particle aluminum with different concentrations and particle sizes to study the influence of different temperature,metal nano-particle size,and fuel concentration on droplet evaporation characteristics.In the single droplet hanging drop experiment,the initial diameter of the droplet is0.88mm?1.17 mm,and the ambient temperature is 623K?923K.The experimental data is recorded through the data acquisition system connected to the high-speed camera,and the evaporation characteristics of the single droplet are analyzed.Characteristics,etc.,and further establish an evaporation model based on the experimental results.First,introduce the experimental device and use Matlab and PS software to innovate the droplet image batch processing program to calculate the diameter of the droplets under different conditions,and analyze the error of the ratio of butanol to diesel and the uncertainty of the square of the droplet diameter.The results show that the ratio error and the square uncertainty error of the droplet diameter of the calculation method are 1.21% and1.43%,respectively,which are within a reasonable range and will not affect the experimental results of this thesis.Then,a hanging drop type single droplet evaporation device is used to study the evaporation law of nanofluid fuel,obtain the droplet evaporation characteristics at low and high temperature environment,and reveal the micro-explosion mechanism.The stability of the experimental device was verified through multiple tests,and the influence of surfactants on the evaporation of droplets was ruled out.Analyze the single droplet evaporation curve at low temperature(623K)and high temperature(923K),and the duration and proportion of different evaporation stages to obtain the evaporation characteristics of nanofluid fuel in each stage.The research results show that at low temperatures,the droplets go through two evaporation stages: transient heating stage and equilibrium evaporation stage.In a high-temperature environment,the droplet goes through three evaporation stages: transient heating stage,wave evaporation stage and equilibrium evaporation stage.At low temperatures,nanoparticles inhibit the evaporation of droplets.The protective shell-like enclosure formed by the nanoparticles will inhibit the evaporation rate of the droplets.In a high temperature environment,the droplets will expand,deform,bubbles and micro-explosions,which are mainly caused by the rapid evaporation of volatile components in the droplets.Finally,the evaporation model of nanofluid droplets is established.Based on the classic D2 evaporation theory,n-pentadecane was used to replace butanol diesel oil,a single-component fuel evaporation model was established and the evaporation rate was calculated,and its feasibility was verified by a single droplet evaporation experiment.According to the comparison between the test value and the simulation value,it can be seen that the agreement between the two is good,and the error is within a reasonable range. |
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