Effect of Nanoparticle Concentration on Physical and Heat-Transfer Properties and Evaporation Characteristics of Graphite/n-Decane Nanofluid Fuels

n-Decane-based nanofluid fuels could be one of the most promising alternative fuels as aviation kerosene for aerospace application. However, the physical and heat-transfer properties of n-decane-based nanofuels have been rarely studied, and the influence of the concentration of nanoparticles on the evaporation characteristics of n-decane-based fuels has been sparsely investigated. This paper investigated physical and heat-transfer properties and evaporation characteristics of graphite/n-decane nanofluid fuels and emphasized the concentration effect of adding graphite nanoplatelets (GNPs) on these characteristics. It was found that there are a linear increase of density and thermal conductivity, a binomial increase of viscosity, and a binomial influence on surface tension as GNP concentration increases, while the boiling point almost remains constant, and the latent heat of vaporization largely decays. There exists a critical GNP concentration of 1.75 wt % for the evaporation performance. At 0 similar to 1.75 wt %, the increase of GNP concentration benefits the evaporation. At 1.75 similar to 4.0 wt %, the enhancement of GNP concentration deteriorates the evaporation performance. A detailed discussion of this evaporation behavior was made, which could be attributed to multiple factors, for example, the aggregation of nanoplatelets, the changes of physical and heat-transfer properties owing to the nanoparticle concentration effect, the surfactant concentration, and the ambient temperature. The concentration of surfactants has a binomial effect, and the ambient temperature has a linear effect on the evaporation rate. This study would promote in depth understanding of physical and heat-transfer properties and evaporation characteristics of nanofluid fuels and develop the application in turbine engines and ramjet engines.