A three-dimensional analysis of the heat and mass transfer phenomena inside a vapor chamber is essential for correctly understanding its thermal performance limitations and structural optimization. This paper presents a complete three-dimensional numerical analysis and comparative study of two different miniature vapor chambers designs with identical external geometry and dimensions but different internal structures: one having a wicked pillar array and the other one without the wicked pillars array. The distribution of the wicked pillar array in the vapor core was aligned. Detailed comparative experimental results are also reported, which were performed to verify the calculations from the numerical simulations. It was found that the numerical and experimental results agree quite well, especially at high heat flux values. It is also observed that the vapor chamber with wicked pillars had a better thermal performance than the conventional design, with a 5% decrease in terms of total thermal resistance due to the added extra channels that allow a better flow of the working fluid to the evaporator surface. An insight into how improving the thermal performance of a vapor chamber is provided through the detailed three-dimensional numerical simulations. 1. Introduction The recent developments in information technology demand large scale integration of electronic circuits, as well as better performance of microelectronic devices. However, as the heat generation rates in electronic chips are continuously becoming larger, to cool such systems effectively also has become a critical problem. Putra et al. [1] suggested that the heat flux of new microprocessor for commercial applications may exceed 100？W/cm2. For hybrid starter-alternator in the automotive industry the electronic components can generate heat fluxes in the range 40–400？W/cm2 [2]. Traditional cooling methods suggest increasing the total surface area of the heat sink or improving the forced convection with the use of fans, but these methods have a performance limit within a specified space constraint. Heat pipe technology is another commonly implemented method which has a number of industrial and electronic applications. Mochizuki et al. [3, 4] suggested the use of the vapor chamber is one of the most effective methods to cool chips. A vapor chamber, a special type of heat pipe, is a vacuum container with a wick structure lining the internal wall, which contains a working fluid, such as water. On applying heat, the water evaporates at the heated surface, and the vapor condenses back to the liquid state
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