A novel vapor chamber and its performance

The performance of a novel vapor chamber is tested in this study. In this vapor chamber, parallel grooves are made on the inner surface of the top plate, with inter-groove openings, to replace the conventional porous wick. To the inner surface of the bottom plate is sintered a layer of porous wick as the evaporator. The peaks of the groove walls directly contact with the wick so that the grooves function as vapor path, condenser and structural supporters simultaneously. The corrugated groove walls provide not only an enlarged condensation area, but also a direct shortcut for a portion of the liquid condensed on the groove surface to be absorbed back to the wick. Thus, smaller liquid-flow resistance and hence high anti-dryout capability are achieved. The test module includes a copper plate-fin heat sink in combination with a top fan. In this study, the evaporator wick was made of sintered multi-layer copper screens and the footprint of the vapor chamber was 10 cm x 8.9 cm. With a 2.1 cm x 2.1 cm or a 1.1 cm x 1.1 cm heating area, the vapor chamber resistances were measured for heat load increasing from 80 W to beyond 300 W. Good performances with low vapor chamber resistance and large heat load limit were obtained under different orientations. In addition, the individual evaporation resistances and condensation resistances were measured for representative conditions. The evaporation resistance was the dominating part of the vapor chamber resistance. Both the evaporation resistance and the condensation resistance decreased with increasing heat load, except that the evaporation resistance increased after the occurrence of partial dryout. (C) 2010 Elsevier Ltd. All rights reserved.