Experimental study on the capillary performance of aluminum micro-grooved wicks with reentrant cavity array

Abstract

In order to enhance the capillary performance for two-phase heat transfer apparatus, the aluminum micro-grooved wick with reentrant cavity array (MGRA) was developed by using orthogonal Ploughing-Extrusion (P-E) method. Different MGRAs with variation in the P-E pitch and depth were designed to study the effect of the fabrication parameters on the capillary performance and obtain the optimal wick structures. The IR-thermal imaging method and forced liquid flow approach were used in the capillary rise and permeability tests, respectively. It was found that the reentrant cavities became more visible and bigger with a larger pitch or smaller depth. The results manifested that the capillary rise height decreased with the increasing longitudinal P-E pitch and depth. Besides, the permeability increased with increase of pitch but decreased with increases of depth. The capillary parameter K·ΔPcap was taken as a comprehensive index to evaluate the wicks. The sample with the largest pitch and smallest depth in the tests obtained the maximal value of K·ΔPcap due to the good balance between the permeability and capillary pressure. Therefore, this sample may be the optimum structural design in this study for the application as enhanced wick for two-phase heat transfer apparatus.