Numerical simulation of cryogen spray cooling during the laser treatment of port wine stain

A quantitative analysis of the cryogen spray cooling process was performed here by numerical method. The codes were used to simulate the dynamic variation and spatial distribution of the surface temperature. The potential cold injury and the effect of the spray distance were analyzed. Through the simulation results, it's clear that our results were in accordance with the experimental results in references; the non-uniform spatial temperature distribution which may attribute to the nonuniform spray could be eliminated by prolonging the spray duration (such as longer than 80 ms); the potential cold injury which may caused by the low temperature cryogen was limited in the epidermal layer, and its influence on human health was tiny; the effect of the spray distance on the heat transfer process was not obvious, so the placement of the nozzle could be flexible in clinical practice.