Thermal performance of composite porous vapor chambers with uniform radial grooves

This study developed a type of composite porous vapor chambers (CPVCs) with uniform radial grooves in the evaporator, providing radial multi-artery channels for the fast liquid backflow with low hydraulic resistance. The separated porous powder parts between adjacent radial grooves were in intimate contact with the condenser porous wick to strengthen the structures of vapor chambers. These CPVCs can be fabricated without solid supporting columns with low cost. A series of CPVCs were fabricated by sintering two types of copper powder with spherical and irregular shapes, and five different particle sizes of <50, 50–75, 75–100, 100–125 and 125–150 μm. Using the working fluid of ethanol, the thermal performance of these CPVCs were systematically assessed together with the comparison with a pure copper plate. The CPVCs were found to maintain good temperature uniformity. They were able to operate efficiently to high heat fluxes of 280 W/cm² without notable performance degradation, and presented the best thermal resistances smaller than 0.15 °C/W. The sample with the spherical powder size of 50–75 μm was found to be the optimum choice for the CPVCs. Moreover, enhanced thermal performance can be obtained when the heating area increased from 10 mm × 10 mm to 15 mm × 15 mm for the CPVCs.