细小圆管内相变微胶囊悬浮液的换热特性

Experimental Research on Heat Transfer Characteristics of Microcapsule Suspensions in Small Circular Tubes

相变微胶囊悬浮液是集储热与强化传热功能于一体的新型工质。分别选取浓度为0.5%,0.75%,1.0%,2.0%和3.0%的相变微胶囊悬浮液,在长为650 mm、内径为2.5 mm、外径为3 mm的不锈钢圆管中进行了换热实验。结果表明:在放热过程中,壁面无量纲温度随浓度的增加而逐渐增加,局部努塞尔数随浓度的增加而逐渐减小;随着沿程的不断增大,壁面无量纲温度出现先增大后减小的趋势,局部努塞尔数呈逐渐降低的趋势。

Phase change microcapsule suspension is a new working medium which integrates heat storage and heat transfer enhancement.Phase change microcapsule suspensions with mass concentrations of 0.5%,0.75%,1%,2%and 3%were selected to conduct heat transfer experiments in stainless steel circular tubes with a length of 650 mm,inner diameter of 2.5 mm and outer diameter of 3 mm.The results show that the dimensionless temperature of the wall surface increases with the increase of mass concentration,and the local Nusselt number decreases with the increase of concentration.Along the flow direction of the suspension,the dimensionless temperature of the wall surface increases first and then decreases,and the local Nusselt number decreases gradually.