Efficacy of using slurry of metal-coated microencapsulated PCM for cooling in a micro-channel heat exchanger
Efficacy of using slurry of metal-coated microencapsulated PCM for cooling in a micro-channel heat exchanger
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DOI：
10.1016/j.applthermaleng.2017.05.001
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发表时间：
2017-07
影响因子：
6.4
通讯作者：
Nathan S. Roberts;R. Al-Shannaq;J. Kurdi;S. Al‐Muhtaseb;M. Farid
中科院分区：
文献类型：
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作者：
Nathan S. Roberts;R. Al-Shannaq;J. Kurdi;S. Al‐Muhtaseb;M. Farid
本文提出了一种利用相变材料（MPCM）在熔化过程中的潜热，使用微胶囊相变材料（MPCM）浆料强化传热的方法。水的传热系数的值是在一个很好的协议与那些估计使用传热相关文献。通过具有不同浆料浓度（5和10 wt.%）的短管MCHE测试两种类型的PCM微胶囊，非金属涂覆和金属涂覆PCM）和流体流速。计算的PCM微胶囊的熔融时间小于它们在相同流速下的停留时间;这证实了它们在MCHE中的熔融。结果表明，传热系数hf随料浆流量和料浆中MPCM浓度的增大而增大。当使用10%非金属包覆的MPCM浆料时，hf增加到纯水的约3.5倍。在相同的MPCM浓度和雷诺数下，与非金属涂覆的相比，金属涂覆的MPCM浆料显示出进一步10%的hf增加。结果表明，相变材料的热物性的提高主要是由于相变材料的熔化引起的流体热容的增加，而微胶囊的微混合作用对相变材料热物性的影响较小。MPCM浆料的使用增加了压降，然而传热增强超过了这种压降的增加。
This paper provides a method of heat transfer enhancement using microencapsulated phase change material (MPCM) slurries, utilizing the latent heat of PCM during melting. The values of heat transfer coefficient obtained for water are in a good agreement with those estimated using heat transfer correlation available in the literature. Two types of PCM microcapsules, non-metal coated and metal coated, were tested through a short tube MCHE with different slurry concentrations (5 and 10 wt.% PCM) and fluid flow rates. The calculated melting times for PCM microcapsules are less than their resident time at the same flow rate; which confirm their melting in the MCHE. The results show that heat transfer coefficient, h f increases as slurry flow rate and MPCM concentration in it increases. The h f increased by∼ 3.5 times of that of pure water when 10% non-metal coated MPCM slurry was used. The metal coated MPCM slurry showed a further 10% increase in h f compared to the non-metal coated at same MPCM concentration and Reynolds number. The results show that the major enhancement in h f is due to the increase in the fluid thermal capacity caused by PCM melting and also to less extend by micro mixing caused by the capsules. The use of MPCM slurry increases pressure drop, however the heat transfer enhancement override such increase in pressure drop.