T. Galal*, A. Kalendar, A. Al-Saftawi, M. Zedan
The Journal of Mechanical Science and Technology, vol. 24, no. 11, pp.2347-2355, 2010

Abstract : The present research examines the amount of condensed fresh water off the outer-side surface of heat exchangers in an MSF system. The quantitative modeling of condensed water on the outer surface of comparable tubes, enhanced and plain, in a simulated MSF technique is investigated. An adapted simulation design on a test-rig facility, accounting for the condenser tubing in actual industrial desalination plate-form, is used with corrugated and smooth aluminum-brass material tubes 1100mm long and 23mm bore. A singlephase flow of authentic brine water that typifies real fouling is utilized to simulate the actual environmental life of a multi-stage flashing desalination system, with coolant flow velocity 0.1 m/s in the two delineated types of condenser tubing. It is demonstrated that the condensate water amount from the specified enhanced tube is about 1.22 times the condensate water amount from the smooth tube, adaptive for 140 running hours under deliberated constrains. The topic covers a comparative analysis of thermal performance. Comparing results with fresh water confirm the effect of fouling on significantly lowering the value of the overall heat transfer coefficient versus time. Fouling resistance Rf is reported with the critical coolant flow speed of 0.1 m/s. Comparison between the fouling resistance for both smooth and corrugated tubes versus time is performed. The fouling thermal resistance of the corrugated tube is 0.56 of the fouling thermal resistance of the smooth tube after140 running hours of the experiment are concluded. Overall, in the case of real brine, results prove that heat performance for the corrugated tube is superior to the plain tube over the studied time period (140 hrs) for the chosen range of flow speeds.

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