相变微胶囊悬浮液强制对流换热实验研究

An experimental investigation of forced convection heat transfer with novel microencapsulated phase change material slurries

提出了一种可以同时作为储能介质与传热流体的新型相变微胶囊悬浮液(MPCS),设计和搭建试验台,分别在层流和湍流条件下在等热流密度的光滑圆管中对MPCS进行了强制对流换热实验,研究了悬浮液浓度、流量、泵送功率和加热速率对其流动及传热特性的影响。结果表明:对于质量分数为5%的MPCS,当微胶囊中相变材料分别处于固体、固体-液体和液体状态时,对应的努塞尔数平均增大了23.9%、20.5%和9.1%;与纯水相比,MPCS作为在热力系统应用的传热流体可以实现强化传热,但是需要在传热实验中控制好相变过程才能使MPCS的传热性能优于水。

This paper proposes novel microencapsulated phase change material slurries(MPCS)as both the energy storage media and heat transfer fluids,and the effects of slurry concentration,flow rate,pumping power and heating rate on the flow and heat transfer characteristics of MPCS have been investigated as well.The forced convection heat transfer characteristics of MPCS in a smooth circular tube with constant heat flux were investigated under laminar and turbulent conditions using a bespoke test rig.The results showed that the average enhancement percentages of the Nusselt number were 23.9%,20.5%and 9.1%for MPCS of 5%mass ratio,and the enhancement of the Nusselt number was achieved when phase change material in the microcapsules were in solid,solid/liquid and liquid states,respectively.Compared with pure water,as a heat transfer fluid used in the thermal system,MPCS can achieve heat transfer enhancement.However,the phase change process must be carefully controlled in the heat transfer test section in order to take advantages of MPCS over pure water.