Heat transfer and pressure drop during evaporation and condensation of R22 in horizontal micro-fin tubes
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The heat transfer and pressure drop performance of three tubes with many small innerfins, called micro-fin tubes, having 9.5 mm outside diameter and 8.9 mm maximum inside diameter were obtained using R22 as the working fluid. The test apparatus had a straight, horizontal test section with a length of 3.67 m and was heated or cooled by water circulated in a surrounding annulus. Nominal evaporation conditions were 0 to 5°C (0.5 to 0.6 MPa) with inlet and outlet qualities of 10% and 90%, respectively. Condensation conditions were 39 to 42°C (1.5 to 1.6 MPa) with inlet and outlet qualities of 90% and 10%, respectively. Mass flux was varied from 150 to 500 kg m-2 s-1. The micro-fin tubes were generally found to have an enhancement of heat transfer ranging from 50 to 100% when compared to an equivalent smooth tube. The maximum increase in pressure drop was only 40%. © 1989.
author list (cited authors)
Schlager, L. M., Pate, M. B., & Bergles, A. E.