Pool boiling on micro-fin array with wire mesh structures

Abstract

Experimental investigations of pool boiling heat transfer on micro-fin arrays covered with porous structure were conducted. Experimental data were discussed for two kinds of enhanced surfaces: micro-fin structure without covering and micro-fins with the copper wire net (mesh structure). The experiments were carried out for water and FC-72 at atmospheric pressure. Micro-fins of 0.5 and 1 mm height were uniformly spaced on base surface. The wire mesh with aperture of 0.32, 0.4 and 0.5 mm (mesh pitch 0.52, 0.54 mm and 0.82 mm respectively), sintered with the fin tips, formed a system of connected perpendicular horizontal tunnels. Tunnel width was 0.6–1.0–1.5 mm and its depth was 0.5 or 1.0 mm. The effects of tunnel/micro-fin dimensions and wire mesh parameters on heat transfer coefficient in nucleate pool boiling was examined. Rather essential enhancement of heat transfer coefficient was observed for the surfaces with micro-fins of 0.5 mm with sintered wire net, especially at low and medium heat fluxes for boiling FC-72 and at the whole range of heat fluxes for boiling water. Structures with micro-fins of 1 mm height showed the best boiling heat transfer performance for water at all used heat fluxes and at the medium and highest heat fluxes for FC-72. For FC-72 at high heat fluxes (above 30 kW/m 2 for shorter micro-fins and 50 kW/m 2 for higher micro-fins) surfaces with plain micro-fins showed the highest heat transfer coefficients.