EXPERIMENTAL STUDY OF POOL BOILING HEAT TRANSFER ON METALLIC FOAM SURFACE WITH U-SHAPED AND V-SHAPED GROOVES

摘要

Pool boiling heat transfer on horizontal metal foam surface with U-shaped and V-shaped groove configurations was investigated experimentally in deionized water at atmosphere pressure. The boiling patterns were gained with a highspeed camera. The foam porosity, foam thickness and pore density were fixed as 0.95, 2 mm, and 130 pores per inch, respectively The U-shaped and V-shaped grooves were manufactured in the studied foam samples with three widths (1, 2, and 3 mm) and three groove number values (1, 2, 3) The existence of grooves can delay the critical heat flux. The boiling heat transfer mechanisms for the grooves are discussed with prevailing influenced factors including bubble escaping resistance, heat transfer surface area, or capillary force in the boiling process The foam surface with U-shaped grooves provides enhanced boiling heat transfer at higher heat flux (q > 5.0 × 10~5 W-m~(-2)). An optimal U-shaped groove number of 2 and a groove width of 3 mm were gained. The heat transfer performance difference between U-and V-shaped grooves is related to the groove number. Particularly, the V-shaped grooved foam surface provids superior performance to the U-shaped groove at the highest groove volume ratio of 36% in the whole experimental heat flux range.