激光手术喷雾冷却中单个液滴蒸发特性  

Evaporation Characteristics of a Single Droplet in Laser Treatment of Port Wine Stain in Conjunction with Cryogen Spray Cooling

作　　者：周致富[1] 辛慧[1] 陈斌[1] 王国祥[1,2] 

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 [2]美国阿克伦大学机械工程系,美国阿克伦44325

出　　处：《中国激光》2008年第6期952-956,共5页Chinese Journal of Lasers

基　　金：国家自然科学基金(50676079);教育部新世纪优秀人才计划(NCET-07-0661);教育部科学技术研究重点项目(107101)联合资助课题

摘　　要：制冷剂喷雾冷却(CSC)是激光治疗鲜红斑痣(PWS)手术的重要辅助手段。为了深入了解制冷剂喷雾特性以提高冷却效率、优化喷嘴设计,利用质量传递数法推导传质方程,通过选取合适的阻力系数经验关联式建立了动量方程,考虑液滴蒸发以及与环境气体的对流换热建立了液滴能量方程,初步建立了单个制冷剂液滴平衡蒸发阶段蒸发冷却理论模型。利用建立的模型模拟悬挂水滴冷冻过程的过冷阶段,并在变物性条件下预测了制冷剂液滴温度随飞行距离的变化,结果与实验对比证明了模型的有效性。有关液滴初始参数对液滴蒸发冷却特性影响的研究结果表明,本模型可以为制冷剂喷雾冷却实际应用于激光治疗鲜红斑痣手术提供有效的分析方法。Cryogen spray cooling （CSC） is an effective cooling technique used for laser treatment of port wine stain （PWS）. The cooling process involves complex droplet evaporation, strong convective heat and mass transfer, therefore a deep understanding of spray characteristics is essential to optimize the nozzle design and improve the cooling efficiency of the spray. This paper presents a theoretical model to describe the equilibrium evaporation process of a single droplet in cryogen spray. The model considers mass transfer through mass transfer number method, the momentum transfer by selecting the suitable empirical correlation of drag coefficient, and heat transfer by taking into account the droplet evaporation and convective effect with ambient air. Through simulating the cooling stage of a hanging water droplet and the temperature variation of cryogen droplets in cryogen spray, the model is validated by the reasonable agreement with the experimental measurements. Then a parametric study of the influences of initial diameter and velocity on the droplet evaporation is carried out, which states that an effective analysis method can be provided by the proposed model to guide the CSC of laser therapy.

关 键 词：医用光学与生物技术 制冷剂喷雾冷却 数学建模 激光手术 鲜红斑痣 液滴蒸发 

分 类 号：R318.51[医药卫生—生物医学工程] R758.5[医药卫生—基础医学]