POOL BOILING HEAT TRANSFER FROM MICRO-FINS WITH WIRE MESH STRUCTURES IN SATURATED FC-72

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 mesh. The experiments were carried out for Fluorinert 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 dimension and wire mesh parameters on heat transfer coefficient in nucleate pool boiling was examined. At the medium and highest heat fluxes structures with micro-fins of 1 mm height showed the best boiling heat transfer performance. At high heat fluxes (above 30 kW/m(2) for shorter micro-fins and 50 kW/m(2) for higher micro-fins) surfaces with micro-fins without the porous structure in form of the wire mesh showed the highest heat transfer coefficients.