Numerical Investigation of Vapor-Chamber Heat Spreading Using 3D Multiphysics Modeling

The continuously increasing power density of modern electronic devices poses a major challenge for thermal management, motivating the development of cooling technologies that exceed the limits of conventional heat sinks and heat pipes. Vapor chambers, which utilize highly efficient two-phase heat transfer within a sealed enclosure, have emerged as attractive solutions for high-heat-flux applications in compact systems. In this work, a three-dimensional multiphysics modeling framework is developed to investigate the thermal behavior of a small-scale copper--water vapor chamber under representative operating conditions. The model couples heat transfer in solid and fluid domains with laminar compressible vapor flow and Brinkman flow in a porous wick to capture conjugate heat transport, vapor redistribution, and wick-assisted liquid return. Phase-change effects are incorporated through energy-conserving boundary conditions at the liquid--vapor interface, avoiding explicit interface tracking while retaining the dominant latent-heat transport mechanism. Numerical simulations performed in COMSOL Multiphysics resolve temperature, velocity, and pressure fields within the vapor chamber, revealing strong in-plane heat spreading and reduced peak temperature relative to purely conductive transport. The results demonstrate an effective interfacial thermal conductivity significantly higher than that of the working fluid alone, highlighting the role of two-phase transport in enhancing thermal performance. The proposed modeling framework provides a computationally efficient and extensible tool for analyzing vapor chamber operation and guiding the design and optimization of advanced thermal management solutions for high-power electronic systems.