Study on evaporation heat transfer characteristics of sessile droplets based on temperature measurement of double layer temperature sensitive paint

As a new non-contact temperature measurement method, temperature sensitive paint has the advantages of low cost and fast response. In this paper, a temperature measurement technology based on double layer temperature sensitive paint was used to study the heat transfer characteristics of sessile droplet evaporation. The temperature distributions at the contact surface between the droplet and the heating substrate and at the back of the substrate were obtained by measuring the temperature with a double-layer temperature sensitive paint. A one-dimensional unsteady inverse heat conduction model was established to obtain the heat flux distribution at the interface between the droplet and the heating substrate. The results show that the droplet vaporization process can be divided into three stages: initial heating stage, convection unit evaporation stage and film evaporation stage. In the initial heating stage, the heat flux increases rapidly. In the convection unit evaporation stage, the heat flux decreases gradually and remains basically unchanged. In the film evaporation stage, the heat flux first increases, and then decreases rapidly as the droplet almost completely evaporates. The reliability of the experimental method is verified by checking the heat quantity of droplet evaporation. The research results in this paper are helpful to broaden the experimental measurement method of heat flux during phase change heat transfer.