角膜在冷冻过程中的传热分析

在角膜的保存方法中,无论是深低温冻贮法,还是真空冷冻干燥法,都须对角膜进行速率降温·对于一个给定的冷却条件,角膜中不同位置处的温度和降温速率是不同的,它们是角膜的几何形状和热物性参数有关的函数,这将引起角膜内皮细胞的损伤·为了保证角膜内皮细胞的成活率,最小化低温伤害,需要知道在冷却过程中,环境冷却条件如何影响角膜内的局部冷却速率和温度分布·采用有限元法模拟角膜在速率降温过程中,环境冷却条件对角膜内传热的作用·通过建立数学模型,求解出在降温仪内距液氮面9cm和1.5cm处达到最优降温速率·

Thermal Analysis in the Cooling Processes of Cornea

In the methods of low temperature freeze and vacuum freeze drying,the cooling rate of cornea must be controlled. For a given cooling condition, the real temperature and cooling rate in the different parts of cornea are varied. They're the function of geometric form and material properties. The corneal endothelium would be injured by the cooling rate. In order to guarantee survival ratio of the corneal endothelium and minimize the low temperature damages, during the cooling process,the effect of the cooling conditions on the partial cooling rate and temperature distribution of cornea must be known. The effect of the surrounding cooling conditions on the heat transfer in the cornea,in the rate cooling process of the cornea,was simulated using the finite element method. The mathematical model was established .The positions of best cooling rate were found. They are 9cm and 1.5cm to the liquid nitrogen surface.