OT-88-05-3 -- Condensation Heat Transfer Enhancement by Doubly Augemented Tubes PDF

Heat transfer and pressure drop data were taken during condensation of R-113 inside nine different double-pipe condensers. R-113 was condensed inside the inner tube and the cooling water flowed in the annulus. The condensers were divided into three sets with three condensers in each set. Within each set, the inner tube of each condenser had the same outside diameter. However, in one condenser the inner tube had internal fins on the inside and a smooth surface on the outside (type a). In the second condenser, the inner tube had knurls on the outside surface and a smooth surface on the inside (type b). In the third condenser, the inner tube had the sane fins as the first condenser on the inside and the same knurls as the second condenser on the outside (type c). This tube is identified as a doubly augmented tube. The three sets of condensers differed in the outside diameter of the inner tube and the fin geometric parameters. The performance of the test condensers with inner tubes of types a, b, and c was evaluated by comparing the experimental values of the overall conductance (UA). The comparisons were made under the constraints of fixed geometry of the inner tube, the same cooling water flow rate and inlet temperature, and the the same inlet condensation pressure of R-113, for different flow rates of the condensing fluid. On the basis of the results, it was possible to identify the favorable conditions under which it is desirable to use single augmentation (inside or outside) versus double augmentation of t~e inner tube in condenser design.

Units: Dual