Boiling heat transfer characteristics of nanofluids in a flat heat pipe evaporator with micro-grooved heating surface
Boiling heat transfer characteristics of nanofluids in a flat heat pipe evaporator with micro-grooved heating surface
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DOI：
10.1016/j.ijmultiphaseflow.2007.06.009
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发表时间：
2007-12-01
影响因子：
3.8
通讯作者：
Bao, Ran
中科院分区：
文献类型：
--
作者：
Liu, Zhen-Hua;Xiong, Jian-Guo;Bao, Ran
对水-CuO纳米颗粒悬浮液（纳米流体）在不同操作压力和不同纳米颗粒质量浓度下的核沸腾传热进行了实验研究。实验装置为蒸发器传热表面带有微槽道的微型平板热管。实验结果表明，操作压力对多工质热泵蒸发器内的核态沸腾特性有很大的影响。与水相比，纳米流体的传热系数和临界热流密度随着压力的降低而显著增加。在常压下，纳米流体的传热系数和CHF分别提高了25%和50%，而在7.4kPa下，纳米流体的传热系数和CHF分别提高了100%和150%。纳米颗粒的质量浓度对纳米流体的沸腾传热和CHF也有显著的影响。在低浓度条件下，传热系数和CHF随纳米颗粒质量浓度的增加而缓慢增加。然而，当纳米颗粒质量浓度超过1.0wt%时，CHF增强接近于常数，并且传热系数劣化。存在一个最佳的质量浓度的纳米流体，这对应于最大的传热增强和这个最佳的质量浓度是1.0重量%，在所有的测试压力。实验证实，水/CuO纳米流体能显著强化MFHP蒸发器的沸腾换热特性。(C)2007爱思唯尔有限公司版权所有。
An experimental study was performed to understand the nucleate boiling heat transfer of water-CuO nanoparticles suspension (nanofluids) at different operating pressures and different nanoparticle mass concentrations. The experimental apparatus is a miniature flat heat pipe (MFHP) with micro-grooved heat transfer surface of its evaporator. The experimental results indicate that the operating pressure has great influence on the nucleate boiling characteristics in the MFHP evaporator. The heat transfer coefficient and the critical heat flux (CHF) of nanofluids increase greatly with decreasing pressure as compared with those of water. The heat transfer coefficient and the CHF of nanofluids can increase about 25% and 50%, respectively, at atmospheric pressure whereas about 100% and 150%, respectively, at the pressure of 7.4 kPa. Nanoparticle mass concentration also has significant influence on the boiling heat transfer and the CHF of nanofluids. The heat transfer coefficient and the CHF increase slowly with the increase of the nanoparticle mass concentration at low concentration conditions. However, when the nanoparticle mass concentration is over 1.0 wt%, the CHF enhancement is close to a constant number and the heat transfer coefficient deteriorates. There exists an optimum mass concentration for nanofluids which corresponds to the maximum heat transfer enhancement and this optimum mass concentration is 1.0 wt% at all test pressures. The experiment confirmed that the boiling heat transfer characteristics of the MFHP evaporator can evidently be strengthened by using water/CuO nanofluids. (C) 2007 Elsevier Ltd. All rights reserved.