Effect of Layer Height on Heat Transfer during Boiling of Dielectric Liquid on Mesh Coatings
摘要
In immersion, two-phase cooling systems for micro- and power electronics, where the permissible heating temperature should not exceed 85°C, dielectric liquid HFE-7100 is widely used. To increase the heat-transfer coefficient (HTC) and critical heat flux (CHF) values during boiling of HFE-7100 liquid, mesh coatings are used. The results of systematic experiments on single-layer and multilayer mesh coatings made of stainless steel with boiling liquid HFE-7100 in horizontal layers are presented. The liquid layer height varied in the range from 1.5 to 25.0 mm at pressures of 100 and 50 kPa. The experiments were performed using wire meshes with a diameter of 100 and 220 µm with cell side of 230 and 401 µm, respectively. The heat-transfer coefficient values obtained on the multilayer mesh coating are higher than those on the surface without meshes by 35% at all pressures considered. At a saturation pressure of 100 kPa, the increase in the critical heat flux values qcr on mesh coatings is almost 60%, while that at a saturation pressure of 50 kPa is approximately 214% compared to qcr on surfaces without meshes. The maximum values of the critical heat flux on single-layer mesh coatings shifts towards thinner liquid layers of 8 mm in height compared to the value qcr on a 16-mm-height layer on a smooth surface.