Experimental investigation on nucleate pool boiling heat transfer characteristics on hydrophobic metal foam covers

Abstract

Hydrophobic metal foam has a great potential for improving the boiling characteristics. In the present study, the nucleate pool boiling heat transfer characteristics of water on the hydrophobic metal foam covers were experimentally investigated. The experimental conditions cover the metal foam pore density of 5–40 PPI (pores per inch), the porosity of 85%-95%, and the heat flux of 0–2 × 106 W/m2. The experimental results show that, at heat flux smaller than 1.3 × 106 W/m2, the pool boiling heat transfer coefficient is increased maximally by 36% and the incipient boiling superheated degree is decreased by 0.4–1.4 K through hydrophobic modification on metal fibers; with the increasing heat flux, the increment of heat transfer coefficient decreases; at high heat flux, the heat transfer coefficient of hydrophobic metal foams is smaller than that of uncoated ones. The hydrophobic modification effect factor EFHy varies within 0.88–1.36. A new correlation for pool boiling on uncoated and hydrophobic metal foam covers was developed with an average deviation of 10.2%.