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Methods to avoid the dynamic Leidenfrost effect are of great importance for high heat flux spray cooling which needs an efficient contact of liquid and superheated surface. In this paper, a novel method of increasing dynamic Leidenfrost temperature is proposed through addition of high-alcohol surfactant (HAS). Effects of 1-Octanol and 2-ethyl-hexanol surfactants on dynamic Leidenfrost temperature and spreading dynamic of droplets impacting on superheated surface were investigated for the first time using high-speed photography. Empirical correlations of dynamic Leidenfrost temperature and maximum spreading factor were obtained based on our experimental data. A possible explanation for the dynamic Leidenfrost temperature increase caused by HAS was proposed based on bubble bursting and bubble coalescence. The results show that dynamic Leidenfrost temperature is significantly increased by addition of HAS because of surface tension reduction. The empirical correlations of dynamic Leidenfrost temperature and maximum spreading factor show good agreement with maximum error of 5% and 10% respectively. These empirical correlations could provide reference value for the future research. [ABSTRACT FROM AUTHOR]

• Analytical solution of non-boiling heat transfer during droplet impact is obtained. • The analytical solutions are applicable to low velocity and low wall temperature. • Wall thermal effusivity can decide heat flux alone, but not the temperature drop. • Droplet property shows great and similar effect on heat flux and temperature drop. • Thermal effusivity is a decisive parameter and high thermal effusivity is preferred. Droplet impact process exhibits excellent heat and mass transfer characteristics. Analytical solution with simple explicit form and certain accuracy can clearly reflect the correlation of physical parameters, however the analytical study on droplet impact heat transfer is quite insufficient and limited to flow field analysis. In this paper, the analytical solutions of heat flux and temperature variation of droplet impact on heated wall in non-boiling regime were obtained based on boundary layer asymptotic matching method. Parameter analysis of thermophysical properties was conducted to explore the decisive properties of droplet and wall materials. The results showed that the analytical solutions are appropriate to predict non-boiling heat transfer at low impact velocity and low initial wall temperature. Parameter analysis showed that thermal effusivity is the decisive property rather than the thermal diffusivity. Wall thermal effusivity could independently determine heat flux, but should determine temperature variation together with wall thermal conductivity. Droplet thermal effusivity and Prandtl number were the decisive properties, however the effect of Prandtl number in reality can be ignored. Wall materials and droplet liquids with higher thermal effusivity showed higher heat transfer capacity. The importance of thermal effusivity was demonstrated and high thermal effusivity was preferred in future thermal management. [ABSTRACT FROM AUTHOR]