相变材料微胶囊悬浮液在矩形小通道内层流流动传热的实验

Experimental study of laminar flow heat transfer with microencapsulated phase change material suspensions in rectangular mini-channels

本文进行了对比性的实验，以研究相变材料微胶囊（MEPCM）-水悬浮液在水力直径为2．71mm的矩形小通道内的层流流动传热性能。实验中用的MEPCM颗粒的平均粒径为4．97μm，与蒸馏水混合制备成质量浓度范围为0～20％的MEPCM-水悬浮液。对比性的实验是指，在相同的悬浮液质量流量和热力条件下，使用不同浓度的MEPCM悬浮液进行传热实验。实验发现，MEPCM悬浮液的冷却性能严重依赖于悬浮液的质量流量和悬浮液的质量浓度。质量浓度为5％的悬浮液在在整个质量流量范围内总是表现出比水好的冷却性能，它对应的是更低的壁面温度以及更好的传热系数。而对于更高质量浓度的悬浮液，在低质量流量的情况下，它们具有很好的冷却性能；而在高质量流量的情况下，它们表现出的冷却性能比水更差，它们对应更高的壁面温度以及更低的Nusselt数。

A series of comparative experiments was conducted to investigate the laminar flow heat transfer characteristics with microencapsulated phase change material （MEPCM） suspensions in water flowing through rectangular mini channels with a hydraulic diameter of 2.71 mm. MEPCM particles with an average size of 4.97μm were used to form suspensions with mass concentrations ranging from 0% to 20%. The comparative experiments were done under the same mass flow rates and the same thermal conditions using water and water-based MEPCM suspensions. The cooling characteristics of MEPCM suspension strongly depend on the mass flow rate and the MEPCM mass concentration. The 5 % suspension always shows better cooling performance than water with lower wall temperatures and enhanced heat transfer coefficient within the whole range of mass flow rates. At higher mass concentrations, however, the cooling performance is more effective only at low mass flow rates. At relatively higher mass flow rates, it shows less effective cooling performance than water at higher wall temperatures and lower Nusselt numbers.