Numerical simulation study on the spatiotemporal evolution characteristics of heat transfer in the static flash evaporation

Due to the intense and short duration of static flash evaporation process, the internal flow field and the spatial distribution of heat transfer intensity are difficult to measure, which limits further enhancement. This paper conducts a numerical simulation study on the static flash evaporation, using the VOF model, defining the flash phase change model and nucleation model. First, the formation and evolution process of the bubble layer during static flash process was obtained: it was found that the temperature distribution within the waterfilm is jointly influenced by velocity vortices and nucleation. Second, the local heat transfer coefficient has a maximum value within the waterfilm. Third, during the flashing process, it has been observed that the spatial distribution of local heat transfer coefficients does not align with the distribution of local superheats. Additionally, it has been noted that the temporal occurrence of peak heat flux does not coincide with the moments when the maximum local heat transfer coefficients are reached, demonstrating the potential for further enhancement in the heat transfer. The findings of this study contribute to a deeper understanding of the heat transfer dynamics in the static flash process and offer insights for the development of strategies to enhance the efficiency of static flash heat transfer.