MULTISCALE MATHEMATICAL MODEL OF HEAT AND MASS TRANSFER IN A THIN VAPOR CHAMBER

A mathematical model of a thin vapor chamber is proposed. The model describes the processes of two-phase heat and mass transfer in this chamber on two spatial scales: the microscopic scale of a single cell of the capillary structure of the wick and the macroscopic scale of vapor chamber as a whole. Using the micromodel, the relationships used in a macromodel are obtained that link the local capillary pressure, wick permeability, and the evaporation fl ux density with the values of temperature, pressure, and degree of fi lling the wick with the working fl uid. Such a multiscale approach was used for numerical study and optimization of the vapor chamber with a wick consisting of micropillars forming a regular hexagonal structure. A fundamental limitation on the width of the vapor core of the chamber is established, which is associated with an increase in the pressure of vapor during its fl ow in a narrow gap. The dependence of the thermal performance of the vapor chamber on the initial degree of fi lling the wick with the working fl uid has been studied, and the importance of the precision fi lling of the chamber is shown. The proposed model can be extended by developing and introducing micromodels of new types of wicks, including those with a heterogeneous structure
A mathematical model of a thin vapor chamber is proposed. The model describes the processes of two-phase heat and mass transfer in this chamber on two spatial scales: the microscopic scale of a single cell of the capillary structure of the wick and the macroscopic scale of vapor chamber as a whole. Using the micromodel, the relationships used in a macromodel are obtained that link the local capillary pressure, wick permeability, and the evaporation fl ux density with the values of temperature, pressure, and degree of fi lling the wick with the working fl uid. Such a multiscale approach was used for numerical study and optimization of the vapor chamber with a wick consisting of micropillars forming a regular hexagonal structure. A fundamental limitation on the width of the vapor core of the chamber is established, which is associated with an increase in the pressure of vapor during its fl ow in a narrow gap. The dependence of the thermal performance of the vapor chamber on the initial degree of fi lling the wick with the working fl uid has been studied, and the importance of the precision fi lling of the chamber is shown. The proposed model can be extended by developing and introducing micromodels of new types of wicks, including those with a heterogeneous structure
Author:  I. A. Koznacheev, A. I. Malinovskii, M. Yu. Lyakh, O. S. Rabinovich, D. A. Ivanov
Keywords:  vapor chamber, cooling, microelectronic devices, simulation, two-phase heat and mass transfer, capillary structures, optimization
Page:  1852