R404A脉冲喷雾冷却类皮肤表面动态传热规律研究  

Dynamic Heat Transfer on Skin Phantom Exposed to R404A Pulsed Spray Cooling

作　　者：杨燃 朱新港 杨涛[1] 周致富[1] 陈斌[1] Yang Ran;Zhu Xingang;Yang Tao;Zhou Zhifu;Chen Bin(State Key Laboratory of Multiphase Flow in Power Engineering,Xi'an Jiaotong University,Xi'an,Shaanxi 710049,China)

机构地区：[1]西安交通大学动力工程多相流国家重点实验室,陕西西安710049

出　　处：《中国激光》2022年第5期66-74,共9页Chinese Journal of Lasers

基　　金：国家自然科学基金(52176163);陕西省科技新星项目(2020KJXX-040);国家重点研发计划政府间国际科技创新合作重点专项(2017YFE0134200)。

摘　　要：目前,辅助激光临床治疗鲜红斑痣所使用的R134a制冷剂喷雾冷却冷量不足,导致表皮黑色素含量高的患者的治疗效果较差。R404A以其更强的冷却能力具有取代R134a的潜力。本文通过实验定量研究了喷雾距离和时间对R404A喷雾冷却类皮肤表面动态传热的影响,并分析了不同工况下传热规律的相似性。结果表明:增加喷雾时间,可以延长对表皮的冷却保护时间;喷雾距离对表面温度的影响取决于时间尺度,短时间喷雾(20 ms)下,表面最低温度T_(min)随着喷雾距离的增大而升高,而长时间喷雾下(100ms),表面最低温度T_(min)在喷雾距离为30mm时达到最小值;表面的最大热流密度q_(max)和最大换热系数h_(max)随喷雾距离增大而单调递减,与喷雾时长无关。通过理论分析提出了无量纲热流密度随无量纲时间变化的关系式。本研究结果对R404A喷雾冷却未来的临床应用具有重要的指导意义。Objective Cryogen spray cooling(CSC)with several tens of milliseconds prior to laser irradiation has been widely used in laser surgeries for treating port-wine stain(PWS).CSC can protect the epidermis from nonirreversible thermal injuries due to competitive absorption by melanin in the epidermis;thus,enhancing the threshold of laser energy.However,the currently used cryogen R134a has shown little efficacy in protecting dark patients as compared with white patients because of the higher melanin content in the epidermis.Meanwhile,to improve the cooling capacity,R404A has been proposed to replace the R134a due to its lower boiling temperature,higher latent heat of vaporization,nontoxicity,and friendly with ozone depletion.In this paper,the influence of spray distance and the duration on the dynamic heat transfer of R404A spray cooling is quantitatively investigated through experiments to analyze the mechanism of heat transfer under different conditions.These results are useful in selecting optimal CSC parameters for PWS patients with dark skin,which are significant for the clinical applications of R404A spray cooling in laser dermatology.Methods This study developed an experimental system of CSC,which included the cryogen spray generation and surface transient temperature measurement parts(Fig.1).The cryogen spray generation system consists of a high-pressure nitrogen bottle,cryogen container,fast-response solenoid valve,and straight-tube nozzle.The liquid cryogen R404A was stored in the cryogen container that connected with the high-pressure nitrogen bottle to adjust its pressure.A solenoid valve was used to precisely control the opening and closing of the pulsed spray,and the nozzle was fitted tightly into the outlet of the solenoid valve.The relative space between the nozzle tip and the measurement points on the cooling surface was controlled by a three-dimensional positioner.The measurement part consists of a fast-response film thermocouple and data acquisition system.The thin-film thermocouple(TFTC)with 2μm th

关 键 词：医用光学 激光皮肤手术 脉冲喷雾冷却 动态传热 R404A 鲜红斑痣 

分 类 号：TK124[动力工程及工程热物理—工程热物理] R751.05[动力工程及工程热物理—热能工程]