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

• Published in: Applied thermal engineering Vol. 119; pp. 319 - 330
• Main Authors: Wang, Rui, Chen, Bin, Wang, Xin-Sheng
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 05.06.2017; Elsevier BV
• Subjects: Acetone; Atomization; Atomizing; Compressibility; Compressibility effects; Computer simulation; Cooling; Coupling; Cryogen spray cooling; Droplet evaporation; Epidermis; Evaporative cooling; Hybrid vortex method; Laser cooling; Laser damage; Laser dermatology; Laser surgery; Mathematical models; Numerical analysis; Spray cooling; Studies; Three dimensional imaging; Vortices; Vorticity; Laser dermatology; Cryogen spray cooling; Droplet evaporation; Atomization; Hybrid vortex method
• ISSN: 1359-4311; 1873-5606
• DOI: 10.1016/j.applthermaleng.2017.03.066

The hybrid vortex method conducts precise simulation on R134a flashing spray, and obtains spatial distribution of cooling capacity which provides the suggestion of the optimal spray distance to get a compromise of large central cooling capacity and uniform distribution. [Display omitted] •A three-dimensional hybrid vortex method is developed for flashing spray.•Internal flow inside nozzle, atomization, and droplet evaporation are considered.•Cooling distribution function is derived to represent spatial cooling capacity.•A radius of 2mm in R134a spray owns 74% of the total cooling capacity.•Optimal spray distance of 26mm is suggested to achieve maximal cooling efficiency. 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 26mm, which is close to the optimal spray distance of 30mm in clinical practice. Particulate count reveals that the central area with a radius of 2mm 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.