弱磁场对去离子水及蔗糖溶液过冷过程的影响

为了研究溶液过冷度和过冷时间在磁场作用下的变化规律,研究了弱直流磁场作用下去离子水和蔗糖溶液的过冷现象。采用亥姆霍兹线圈产生匀强磁场,线圈连接到可以改变输出电流值的直流电源上,从而可以控制磁场强度的大小。研究去离子水以及4种不同质量分数的蔗糖溶液(ω₁=2%、ω₂=5%、ω₃=8%、ω₄=10%)在直流磁场作用下的过冷度及过冷态时间的变化,在冷却和冻结过程中记录溶液温度和时间。结果表明:对于去离子水,直流磁场会提高过冷度,过冷时间会有所延长;而对于蔗糖溶液,不同强度的直流磁场对不同质量分数的蔗糖溶液过冷过程的影响呈现多极值现象。该试验结果可以为磁场应用于控制溶液的冷冻干燥过程提供指导。

The effects of weak magnetic field on supercooling process of deionized water and sucrose solution

In order to study changing laws of supercooling degree and supercooling time of solution under different magnetic field intensity, supercooling processes of deionized water and sucrose solution under a week direct current magnetic field were investigated. The sucrose solution was chosen with four different concentrations (ω₁=2%、ω₂=5%、ω₃=8%、ω₄=10%). Experiments were performed to see how the supercooling degree and supercooling time of deionized water and sucrose solution changed at different magnetic field intensities. The magnetic field was generated by a pair of Helmholtz coils and evenly distributed. The coils were connected to a direct current electric source, which regulated the intensities of the magnetic field by varying the direct current output. Both temperature and time was recorded during cooling and freezing processes.The results showed that magnetic field could increase the supercooling degree and supercooling time of deionized water, but the influence on the supercooling process of sucrose solution with different concentration presented a multi-extreme phenomenon. Research results could provide a reference for controlling freeze drying process of solution by applying magnetic field.