Characterization of high-performance nanostructured wick for heat pipes

To investigate the best performance wick forms to support the design and fabrication of high-performance heat pipes. This paper investigates the comprehensive performance of wicks by nanosurface technology and experi-mental methods to predict heat pipe performance rapidly. In this paper, two kinds of nanostructured wick were prepared by the oxidation-reduction method. They are stainless steel fiber mat-type nanostructured and nickel foam-type nanostructured wicks. The effect of surface nanostructure on the wick performance was investigated by comparing the surface characteristics, capillary properties, permeability, and evaporation properties. In this study, the competitive relationship between the characteristic parameters of the wick is measured by the capillary performance factor M: K/reff, which is used as a measure of the comprehensive performance of the wick, and its maximum value is pursued industrially. The result shows that the nanostructured wick presented excellent super hydrophilic properties. A liquid-lift visualization experimental method for measuring the capil-lary performance factor M was proposed, and it was verified to be correct by the separation effect of the capillary pumping experiment under a vacuum environment. With the increasing oxidized degree, the densification of nanoparticles on the wick surface increased the capillary performance factor M from 8.68 mu m to 13.81 mu m, with a maximum enhancement of 59.1%. The effective capillary radius decreased from 47.0 mu m to 40.1 mu m, with a maximum reduction of 14.9%. The permeability increased from 433 mu m2 to 583 mu m2, with a maximum enhancement of 34.7%. The increase in porosity made the effective capillary radius dominate the competition for permeability, and the capillary performance factor decreased by 17.1%. The thermal resistance of the wick decreased with the enhancement of the capillary performance factor, which fell from 20.3 cm2 center dot K/W to 12.6 cm2 center dot K/W. The current study provides a reference for the future design and preparation of high-performance heat pipe wicks.