Numerical simulation of cryogen spray cooling by a three-dimensional hybrid vortex method

Cryogen spray cooling (CSC) can protect the epidermis from unwanted thermal damage during laser dermatological procedures. Numerical simulation of CSC can provide significant guidance for clinical implementation, but relevant research is sparse. Thus, a 3D two-way coupling hybrid vortex method is developed to simulate CSC. The two-way coupling and compressibility effects are implemented by introducing a vorticity source term into the grid. The validity of this algorithm has been confirmed in a previous simulation of the evaporating acetone spray. Comparisons between the simulation results and the R134a spray cooling experimental results demonstrate the accuracy of the present method in analyzing the complex atomization and evaporation. The simulated cooling capacity achieves the maximum experimental value at a spray distance of 26 mm, which is close to the optimal spray distance of 30 mm in clinical practice. Particulate count reveals that the central area with a radius of 2 mm in R134a spray accounts for 74% of the total cooling capacity, which is beneficial for the precise control of the therapy area in laser surgery. (C) 2017 Elsevier Ltd. All rights reserved.