Experimental study of condensation heat transfer characteristics on metal foam wrapped tubes under sloshing conditions

Abstract

Metal foam wrapped tube has the advantages of large specific surface area, and thus it has great potential to enhance the condensation heat transfer for marine shell and tube condensers, which have the requirements of "high compactness" and "high reliability" under sloshing conditions. In the present study, the effects of the metal foam pore density and the sloshing conditions on the condensation heat transfer on metal foam wrapped tubes were experimentally investigated. The pore density of metal foam covers the widely used structure ranging from 5 PPI to 40 PPI; the sloshing conditions include six-freedom motions of surging, swaying, heaving, rolling, pitching and yawing; the sloshing displacement ranges from 0 to 120 mm; the sloshing angle ranges from 0 to 12°; and the sloshing frequency ranges from 0 to 0.33 Hz. The experiment results show that the condensation heat transfer coefficients of metal foam wrapped tubes increase firstly and then decrease with the increase of PPI, and the 10 PPI metal foam wrapped tube shows the optimal condensation performance. The rolling motion has significant effect on the condensation heat transfer of metal foam wrapped tube, while the other five sloshing motions have negligible effect on the condensation heat transfer of metal foam wrapped tube. With the increase of rolling angle from 0 to 12°, the condensation heat transfer performance of 10 PPI and 20 PPI metal foam wrapped tube gradually increases and the increase rate of the condensation heat transfer coefficient is up to 12%; while the condensation heat transfer performance of metal foam wrapped tube with 5 PPI increases as the rolling angle is larger than 10°. With the increase of rolling frequency, the condensation heat transfer performance of metal foam wrapped tube decreases, and the decrease rate of the condensation heat transfer coefficient is up to 8%.