Influence of electrochemical deposition parameters on capillary performance of a rectangular grooved wick with a porous layer

Abstract

A wick is a key component of two-phase heat transfer devices. To balance conventional conflicting requirements between permeability and capillary pressure performance, a rectangular grooved composite wick combined with a porous deposition layer was fabricated on a copper plate using a combined technology of planing, electrochemical deposition and heat treatment. The permeability of this composite wick was tested experimentally by a forced liquid flow method to investigate the effect of electrochemical deposition parameters. Deposition current density was shown to affect permeability more intensely than deposition time. To overcome the difficulty of porosity measurement, a modified capillary performance parameter K/(AiwReff) instead of conventional K/Reff was proposed to evaluate the comprehensive capillary performance of the composite wick. In addition, an infrared (IR) thermal imaging method was employed to investigate capillary rising height and velocity, using ethanol as the test liquid. The influence of deposition parameters and wick types on the values of parameter K/(AiwReff) was discussed. The results show that there is an optimal value of both deposition time and current density to maximize capillary performance of the composite wick. Comparative studies show that a composite wick features a better capillary performance with proper fabrication parameters than a plane-deposition or its preformed smooth grooved wick.