Experimental and simulation study on capillary flow of microchannel nanoporous membrane composite wick

Abstract

In this study, we employed both experimental and simulated methods to investigate the capillary flow phenomenon in composite wicks that integrate the silicon-based microchannels with AAO nanoporous membranes. The experiment utilized deionized water and anhydrous ethanol to analyze the capillary performance of both the microchannel wick and the microchannel nanoporous membrane composite wick. The findings demonstrated that the micro-nano composite wick exhibited a higher capillary rise height and a faster capillary rise rate compared to the microchannel wick. The optimal capillary rise heights for deionized water and anhydrous ethanol were associated with microchannel widths of 10 μm and 20 μm, respectively. Additionally, the parameter K/R_eff was used to evaluate the capillary performance of both the microchannel wick and the micro-nano composite wick. The optimal capillary performance parameters for deionized water and anhydrous ethanol are 6.80 × 10⁻⁸ m and 5.54 × 10⁻⁷ m, respectively. Subsequently, the capillary flow characteristics of the micro-nano composite wick were further investigated using the lattice Boltzmann method. The results indicate that when the working fluid passes through the nanopores, it becomes immersed within their interiors, thereby continuously propelling the working fluid forward. Concurrently, the radius of curvature at the liquid front decreases, further enhancing capillary performance.