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对以水为热载体,方形槽内水平圆管外石蜡的相变蓄热过程进行了数值模拟。通过合理的分析与假设,建立数学模型及其定解条件,并利用实验数据进行验证。引入无量纲管壁温度Ste数和无量纲相变材料初温G数,分析了Ste和G数对相变材料熔化、凝固过程的影响,给出了不同Ste数的熔化过程固液相图,结果表明:Ste数对熔化和凝固过程有显著影响,与S=0.098时的熔化时间相比,Ste=0.1875时熔化时间将会缩短将近1/2,而Ste=0.277时比Ste=0.1875时熔化时间缩短了1/3。与Ste=0.0804时的熔化时间相比,Ste=0.170时凝固时间缩短1/2,而Ste=0.259时比Ste=0.170时凝固时间缩短了1/3。G数对相变过程的影响比较小,凝固时甚至可以忽略不计。
The phase change heat storage process of paraffin outside the horizontal tube in a square tank was numerically simulated with water as heat carrier. Through reasonable analysis and hypothesis, the mathematical model and the conditions of its solution are established and validated by experimental data. The Stee number of the tube wall temperature and the initial temperature G number of the dimensionless phase change material are introduced. The influence of Ste and G number on the melting and solidification process of the phase change material is analyzed. The solid-liquid phase diagram of the melting process with different Ste numbers is given. The results show that Ste number has a significant effect on the melting and solidification process. Compared with the melting time at S = 0.098, the melting time will be shortened by nearly 1/2 at Ste = 0.1875, and will be lower at Ste = 0.277 than at Ste = 0.1875 Shorten the time by 1/3. Compared with the melting time at Ste = 0.0804, the solidification time is shortened by 1/2 when Ste = 0.170, and the solidification time is shortened by 1/3 when Ste = 0.259. The effect of G number on the phase transition is relatively small and can even be neglected when solidifying.