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ISSN Online: 2377-424X

International Heat Transfer Conference 12
August, 18-23, 2002, Grenoble, France

The effect of micro- surface treatment on heat and mass transfer performance for falling film absorption process

Get access (open in a dialog) DOI: 10.1615/IHTC12.730
6 pages

Resumo

The objectives of this paper are to develop a new method of wettability measurement and to study the effect of micro-surface treatment on the wettability in a LiBr/H2O falling film absorber. Three absorber tubes with micro-scale roughness are tested in a falling film absorber installed in a test rig. Inlet solution temperature (30 - 50°C), concentration (55 - 62 weight % of LiBr) and mass flow rate (0.74 - 2.71 kg/min) are considered as key parameters. A new method is proposed to estimate the wettability of a tube by measuring a minimum mass flow rate to wet the tube completely. Reynolds number is ranged from 30 to 120 by controlling the inlet mass flow rate. The wettability for the structured surfaces was much higher than that for the bare tube. The wettability decreased linearly along the vertical location as low as 65 % for the bare tube and 75% for the micro-scale hatched tubes. The wettability increased with increasing the solution temperature and the solution mass flow rate. It was found that the wettability increased with increasing the liquid film Reynolds number and the roughness. The experimental correlations of the wettability for the bare and the micro-hatched tubes were developed with error bands of ±20% and ±10%, respectively. This correlation can be used in the design of absorbers with micro-scale roughness.