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ISSN Online: 2377-424X

ISBN Print: 1-56032-797-9

International Heat Transfer Conference 11
August, 23-28, 1998, Kyongju, Korea

EXPERIMENTAL EVALUATION OF THE HEAT TRANSFER CHARACTERISTICS OF A FLUTED TUBE USED FOR DESALINATION

Get access (open in a dialog) DOI: 10.1615/IHTC11.120
pages 69-74

Résumé

A small scale single effect desalination unit was constructed at UCLA for testing heat transfer surfaces for a proposed desalination plant. The apparatus used in this study was designed to duplicate possible thermodynamic and hydrodynamic plant conditions of a full scale multi-stage/vertical tube evaporator desalination system in order to evaluate the heat transfer performance of fluted aluminum tubes. In the first phase of this investigation deionized water was used as a substitute forseawater. During these initial tests, several trends in the overall heat transfer coefficient, U (W/m2·K), were observed for the variation of the system parameters. U was found to be an increasing function of the system temperature and a decreasing function of both the internal flow rate and the driving temperature difference. An empirical equation to determine the overall heat transfer coefficient as a function of these parameters was developed. In the second phase of this study, the overall heat transfer coefficient for the evaporation of salt water was determined. However, no significant differences from the deionized water experiments were observed. The final series of experiments were to be performed with seawater. However, a 40% reduction in the overall heat transfer coefficient was immediately observed for the seawater measurements. Subsequent measurements with deionized water were also found to be approximately 40% below the earlier values. Close inspection of the tube later revealed that a thick layer of silt from the seawater had deposited along the inner surface, thus increasing the resistance to heat transfer.