Analysis of wettability effects on thermal performance of vapor chamber with a hybrid lattice Boltzmann method

Vapor chamber (VC) has been recognized as an effective passive cooling solution for thermal management. Due to complexity of phase-change processes in VC, boiling and condensation have been the focus of attention. In this paper, a hybrid lattice Boltzmann method was employed to explore the effects of surface wettability on thermal behavior/performance of VC. Taking the bubble/droplet dynamics, boiling heat transfer coefficient (BHTC), critical heat flux (CHF), thermal response and resistance as key factors, selections of proper surface wettability to address heat dissipation requirements were discussed. The results show that the influences of wettability on phase-change processes are not monotonic. For high heat fluxes, compared with neutral surface of 89.0° contact angle (CA), the CHF of the hydrophilic boiling surface (CA=23.9°) is enhanced by 92.57%. For low heat fluxes, the VC with a hydrophobic boiling surface (CA=115.5°) results in the highest BHTC by 260.34% compared with the neutral one. The heat flux should be carefully applied to the hydrophobic surface to prevent burnout. For condensation surface modification, the hydrophilic condensation surface is preferred for the faster thermal response. These findings are expected to provide a promising method for enhancing thermal performance of VC by surface modification.