Zhang Aili, Luo Xiaodong, Chen Chao, He Liqun, Xu Lisa X
College of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dong Chuan Rd., Shanghai 200240, PR China.
Cryo Letters. 2006 Jul-Aug;27(4):243-52.
A model is presented to simulate the cooling processes during tumor cryosurgery with different kinds of flows through the cryoprobe. The heat flux between the cryoprobe wall and the tumor, the heat transfer coefficient under different inflow conditions are obtained numerically. The impact of the inlet mass flow rate, gas volume fraction on these parameters is investigated. It is found that the heat transfer coefficient decreased significantly when inflow changed from two-phase annular flow to droplet flow, and to gas flow. The inlet gas volume fraction and flow velocity only significantly affect the freezing ability of the probe when the inflow is gas or in droplet phase. Simulation of the tumor temperature profiles under different flow conditions show that the heat transfer coefficient is a crucial parameter in temperature prediction during cryosurgery. Results indicate that when the cryoprobe wall is assumed at a constant temperature conventionally, the cooling effect could be overestimated. It would be more reasonable to use the constant wall heat transfer coefficient to simulate the cooling progress under a specific flow.
提出了一个模型，用于模拟肿瘤冷冻手术过程中不同流体流经冷冻探针时的冷却过程。通过数值计算得到了冷冻探针壁与肿瘤之间的热通量以及不同流入条件下的传热系数。研究了入口质量流量、气体体积分数对这些参数的影响。结果发现，当流体从两相环状流变为液滴流再变为气流时，传热系数显著降低。仅当流入流体为气体或液滴相时，入口气体体积分数和流速才会显著影响探针的冷冻能力。不同流动条件下肿瘤温度分布的模拟结果表明，传热系数是冷冻手术温度预测中的关键参数。结果表明，传统上假设冷冻探针壁温度恒定时，冷却效果可能会被高估。在特定流动条件下，使用恒定壁面传热系数来模拟冷却过程更为合理。
