An experimental study of an anti-gravity vapor chamber with a tree-shaped evaporator

A new anti-gravity vapor chamber is proposed in this study in which a tree-shaped groove is configured on the evaporator's surface, and the formed cavity is embedded with hybrid mesh wick. The thermal performances of the anti-gravity vapor chamber with a tree-shaped evaporator surface are experimentally studied and compared with those elicited from a corresponding chamber with a smooth evaporator surface. The effects of the filling rate, cavity height, and wick structure on the heat transfer performance of the anti-gravity vapor chamber are examined and analyzed. The results indicate that the thermal performance of the anti-gravity vapor chamber is greatly improved by the combination of tree-shaped grooves and hybrid mesh wick. The introduction of mesh wick eliminates the wall temperature fluctuation of the evaporator in the vapor chamber. The tree-shaped groove induces vapor distributed flow and enhances the thermal performance of the anti-gravity vapor chamber. The thermal resistance of the vapor chamber decreases first and then increases with increases of the liquid filling rate. The optimum liquid filling rate is 60%. The thermal resistance of the anti-gravity vapor chamber decreases as the cavity height decreases. The vapor chamber with an 80/200 mesh hybrid wick facilitates the reversed motion of condensate backflow and vapor flow, thereby leading to better heat transfer performance as compared to the 80 and 200 mesh wicks.