A. Kalendar, T. Galal*, A. Al-Saftawi and M. Zedan
The Journal of Mechanical Science and Technology, vol. 25, no. 8, pp.1969-1977, 2011

Abstract : Existing MSF systems experience severe mechanical difficulties due to fouling deposited inside the bore of the condenser tubes. The idea of replacing smooth tubing with enhanced tubing is discussed for innovative design. Performance analysis between enhanced and plain tubes is investigated experimentally, using a simulated design test rig. The study is performed for corrugated and smooth resemblance aluminum-brass tubes of 1100 mm length and 23 mm bore. Pumping different coolants as steady transition/turbulent flow, fresh water and authentic brine are conducted to simulate actual environmental conditions. Three different flow velocities are examined: 0.1, 0.1645, and 0.2398 m/s. Comparing results of the brine with that of fresh water shows the effects of fouling on significantly lowering values of overall heat transfer coefficient versus time. The results confirm that the smooth tube has a greater fouling tendency than the corrugated tube. The effect of fouling is reduced as flow speed increases, and consequently, the asymptotic value of overall heat transfer coefficient U* increases. Values of U* for the enhanced tube are much higher than that of the smooth tube. The highest difference occurs at velocity 0.2398 m/s by a factor of about 1.5. Overall, by utilizing real brine, the results proved that heat performance of the employed corrugated tube is superior to the plain, over the studied time period, 140 hrs, and on the studied range of flow speeds.

Keyword : Smooth tube; Corrugated tube; Condenser tubing; MSF system; Desalination