不同粒径石蜡微胶囊悬浮液的传热性能研究

Investigation on heat transfer property of aqueous suspension ofparaffin microcapsules with different sizes

石蜡微胶囊悬浮液(MEPCMS)是石蜡微胶囊与传热流体混合形成的一种新型功能材料,依靠胶囊固-液相变吸收大量潜热的特性而具有强化传热能力,在电子电器、航空航天、新能源等领域的应用前景广阔。本文尝试从胶囊粒径入手,寻找促进MEPCMS安全高效传热的可靠途径。研究以正十八烷(C18)作芯材、三聚氰胺甲醛树脂(MF)作壁材,采用原位聚合法合成了粒径均匀的石蜡微胶囊;采用分散剂手段将胶囊添加进去离子水,获得了分散稳定的MEPCMS。在此基础上,围绕不同粒径MEPCMS的管内传热性能展开研究。结果表明,减小粒径是提升MEPCMS传热性能的有效途径。MEPCMS的粒径从20.0μm减小至2.6μm,其流动传热的平均努塞尔数(Nu)增加约20.3%,传热通道的温升降低约33.0%。

Aqueous suspension of phase change material(PCM)microcapsules is a new kind of function material that has a bright application prospect in many fields such as the heat dissipation of electronic and electrical equipments,and the utilization of new clean energies.It shows an improved heat transfer performance since the PCM microcapsules can absorb lots of latent heat during solid-liquid phase transition in comparison with the base fluid.In this study,a new method of particle size control was introduced for optimizing the overall performance of microcapsule suspension in heat transfer and energy consumption.The PCM microcapsules composed of octadecane and melamine formaldehyde resin was synthesized by in-situ polymerization,and showed a uniform size distribution.These microcapsules were dispersed in the deionized water by adding a surfactant,and the resultant microcapsule suspension had a good stability.Investigation on the heat transfer of the aqueous suspension of PCM microcapsules in a circular tube was conducted,focusing on the effect of microcapsule size.It was found that as the size of microcapsules decreased from 20.0μm to 2.6μm,a 20.3%increase in Nussell number of microcapsule suspension and a 33.0%reduction in temperature rise of circular tube could be achieved.This finding confirmed that reducing the size of PCM microcapsules is a feasible and efficient way to improve the comprehensive heat transfer performance of microcapsule suspensions.