Experimental Study on Performance Enhancement in Gradient Wick Vapor Chambers

Abstract

The high-efficiency vapor chamber (VC) is an effective solution for the thermal management of high-heat-flux electronic devices. To further improve the VC performance, this work proposes a gradient wick VC. A systematic experimental investigation of gradient wick VCs is conducted to evaluate their thermal performance enhancement compared to conventional wickless designs. Through comprehensive testing, the gradient wick VC demonstrates superior thermal characteristics, including 33% faster stabilization rates and significant reductions in steady-state temperature (32.5% on evaporator, 7% on condenser surfaces) under identical operating conditions. The research reveals three key operational dependencies: (1) thermal resistance increases with heat source eccentricity, though this effect diminishes at higher heat fluxes; (2) resistance grows with smaller heat source areas but stabilizes above 8 W/cm²; and (3) gravity-assisted orientation achieves up to 56% lower resistance than anti-gravity operation within 2 ~ 10 W/cm² range. The chamber reaches its heat transfer limit at 400 W (120 W/cm²), beyond which performance degrades substantially. These findings provide critical design guidelines for implementing gradient wick VCs in practical thermal management systems, particularly highlighting their improved temperature response, gravity adaptability, and area-dependent performance characteristics.