Performance tests on a novel vapor chamber using water, methanol or acetone as the working fluid

Experiments on vapor chamber performance with working fluid of water, methanol and acetone, respectively, were conducted using our novel vapor chambers. Water has remarkably larger latent heat and surface tension, and acetone has similar surface tension as methanol but smallest latent heat. A sintered two-layer 100+200 mesh wick was adopted, and the volumetric fluid charges were the same. The footprint of the vapor chamber was 90 mm ×100 mm. The vapor chamber was loaded at its central bottom with a dummy heater of 1.1 × 1.1, 2.1 × 2.1 or 3.1 × 3.1 cm
²
. The thermal resistances of the vapor chamber were determined according to the heat load and the temperature difference between the bottom plate and the heat sink base. As far as the maximum heat load is concerned, water presents the largest and acetone the smallest, in the same sequence of their figures of merit. However, the differences are not as distinct as in their figures of merit. As for the minimum vapor chamber resistances, water presents the smallest value and acetone the largest, as acetone presents the largest average evaporating film thickness due to its small surface tension. The differences are more pronounced than those in the evaporation resistances measured in a conventional plat-plate heat pipe. For all three working fluids, the minimum vapor chamber resistances strongly decreased with increasing heated area. For sufficiently large heated area, this can be mainly attributed to a smaller average evaporating film thickness for a larger evaporation area.