A review of the thermal performance of vapor chambers and heat sinks: Critical heat flux, thermal resistances, and surface temperatures

Critical heat flux (CHF), heat transfer surface temperature, and thermal resistance are arguably the three most important design and performance parameters for any two-phase cooling system. The present study focuses on a review of published articles on the thermal performance enhancements of a vapor chamber, which is one of the most-studied two-phase liquid-vapor-based cooling system for high heat-flux-dissipating systems in the last few decades. Included are both experimental and numerical findings of different geometrical and thermophysical parameters that govern and control different heat transfer phenomena in vapor chambers. Like other two-phase cooling systems, a typical vapor chamber consists of an evaporator, a condenser, a wicking structure, and an adiabatic casing. However, the overall thermal performance of a vapor chamber is mainly dependent on the heat transfer and/or capillary characteristics of the wicking structure, i.e., the evaporation and liquid supply wicks, thus, vapor chambers in this study have been classified based on the type of wick. They include sintered metal powder, axial grooves or channels, and screen/wire mesh-type evaporation wicks. Other less popular evaporation wick designs are also discussed. Moreover, some researchers have carried out comparative studies between vapor chambers of different evaporation wick, and this study has highlighted their respective pros and cons. It is important to mention that this review paper is not designed as an exhaustive study of vapor chambers but to serve as an update on the existing progress on the heat transfer performance enhancement of the technology. Finally, recommendations are provided for future research direction in terms of manufacturing and characterizing vapor chambers for concentrated heat flux dissipation applications.