影响血浆冷冻效果因素的数值模拟研究

Numerical Simulation Study on Effect of Freezing Temperature on Quality of Fresh Frozen Plasma

血浆袋中心点温度降至-30℃是衡量血浆冷冻过程的最终指标,冷冻过程中的降温速率和温度分布均匀性是决定血浆冷冻质量的关键因素。本文通过实验测定了血浆的热物性参数,结合数值模拟方法研究不同冷冻温度对血浆冷冻过程中降温速率和温度分布均匀性的影响。结果表明:降低冷冻温度,可缩短血浆中心达到-30℃所需的冷冻时间,但使血浆内温度均匀性变差;不同冷冻温度时,由于空气与血袋壁面换热能力相对较弱,血浆最高温度均分布在与空气接触壁面附近;通过增大血袋与冷冻箱内壁的接触面积或提高空气的流速、湍流度,可能成为增大血浆降温速率和温度均匀性的重要措施。

When the central temperature of the plasma bag reaches-30 ℃ the freezing process is finished. The cooling rate and the temperature uniformity of the plasma bag during freezing are two key factors for determining the freezing quality of plasma. In this study,the thermophysical parameters of plasma were measured experimentally. The effects of different freezing temperatures on the cooling rate and temperature uniformity of the plasma bag were investigated through numerical simulation. The results show that a lower freezing temperature can shorten the time to reach-30 ℃,but the temperature uniformity of the plasma bag becomes worse. At different freezing temperatures,the maximum temperature of plasma is at the place where there is a gap between the plasma bag and the freezing plate,due to the relatively poor heat transfer capability of air. In summary,increasing the contact area between the inner wall of the freezer and plasma bag or increasing the air flow velocity and turbulence intensity can significantly increase the cooling rate and temperature uniformity of the plasma.