微结构表面的大过热度蒸发传热特性分析

Characteristic Analysis of Superheated Evaporation Heat Transfer on Micro-structured Surface

玻璃化冷冻方法是细胞超低温保存的有效冷冻方法之一。降温速率的提高有利于细胞内外溶液玻璃化程度的增加,同时可以降低低温保护剂的浓度,减少低温保护剂对细胞的毒性伤害和渗透性损伤。本文针对发生在冷冻载体微结构表面的大过热度蒸发过程的传热特性进行研究。采用集总热容法,计算了传热过程的热流密度、总传热热阻和液氮蒸发传热系数等重要传热参数,考察了它们随过热度变化的规律。在本文研究的过热度变化范围内,随着过热度的增加,微结构表面的液氮蒸发传热系数呈线性减小趋势;总传热阻呈指数增加趋势;热流密度呈抛物线变化趋势。上述研究成果有利于进一步理解微结构表面的大过热度蒸发传热机理。

Vitrification is one of effective methods for cell cryopreservation.An ultra-fast cooling rate is beneficial to improve the vitrification level of the extra and intracellular solution and decrease the concentration of cryoprotectant.The relatively low concentration cryoprotectant can decrease the damaging toxic and/or osmotic effects on cell survival.This study tried to analyze the heat transfer characteristics of the superheated evaporation on the micro-structured surface on the frozen carrier.The key parameters in the heat transfer process,such as heat flux,overall heat resistance,and evaporation heat transfer coefficient,was calculated by the lumped heat capacity method.And,the effect of the degree of the superheat on the key parameters was analyzed.When the superheat increases in the range of this study,the evaporation heat transfer coefficient decreases,the overall heat resistance increases exponentially,and the heat flux first increases and then decreases.The current investigation can result in a better understanding of the mechanism on superheated evaporation heat transfer on micro-structured surface.