Marangoni condensation of ammonia-water vapor mixtures on a horizontal tube

Abstract

In this paper, the Marangoni condensation of ammonia-water mixture on a horizontal smooth tube was investigated. The research presented here concerns the external condensation of down-flowing ammonia-water vapors on a 100mm long cooled horizontal copper tube of 16mm external diameter. The results showed that, with the change of the surface subcooling, the condensation heat transfer coefficients revealed nonlinear characteristics with peak values. With the increase of the ammonia vapor concentration, the condensation heat transfer coefficient decreased notably. The condensation heat transfer enhancement had been realized by addition of ammonia to water almost in all the experimental surface subcoolings. The maximum ratio of heat transfer coefficient compared to the pure steam is 1.9 at the ammonia vapor concentration of 0.38%.