通过质量分数为5%~20%的潜热型功能热流体在扁管内的对流换热特性实验,研究了相变材料微胶囊质量分数、质量流量等因素对流体换热性能的影响。实验发现,流量较小的情况下,功能流体传热性能优于水且随着质量分数的升高而增强,而当流量较大的情况下,接近入口处的功能流体的传热性能则弱于水。以改进的Nusselt数评价,入口段内,质量分数为10%和20%的潜热型功能热流体的平均换热能力比水分别提高了6.7%和16.2%。实验质量分数范围内的潜热型功能热流体均表现出牛顿流体的特性,且其黏度较符合Vand关系式。
An experimental investigation on the convective heat transfer characteristic of 5wt%-20wt% latent functionally thermal fluid flowing in a flat tube is presented in this work. The influences of the mass flow rate and the mass fraction of microencapsulated phase change material (MPCM) on the heat transfer performance are conducted. The results of the experiment show that at the region of small flow rate, the heat transfer performance of latent functionally thermal fluid is better than that of water and increases with the increase of concentration of MPCM, while not as good as that of water near the entrance where the flow rate is high. Evaluated by the modified Nusselt number, the average heat transfer rate of 10wt% and 20wt% suspensions is improved by 6.7% and 16.2% respectively compared to that of water at the entrance region. The latent functionally thermal fluids are approximately Newtonian fluids and their viscosities fit well with the Vand model.
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