Evaporation and Condensation Heat Transfer and Pressure Drop in Horizontal, 12.7-mm Microfin Tubes With Refrigerant 22

摘要: Using R-22 as the working fluid, a series of tests was performed to determine evaporation and condensation performance three 12.7-mm o.d. tubes having many small, spiral inner fins. The tubes, referred microfin had 11.7-mm maximum i.d., 60 or 70 fins with heights ranging from 0.15 0.30 mm, angles 15 25 deg. A smooth tube also tested establish basis comparison. test apparatus straight, horizontal section length 3.67 m heated cooled by water circulated in surrounding annulus. Nominal conditions were 0 5C (0.5 0.6 MPa) inlet outlet qualities 85%, respectively; condition 39 42C (1.5 1.6 85 10%, 42 C respectively. mass flux varied 75 400 kg/m{sup 2}{centermore » dot}s. average heat transfer coefficients based on nominal equivalent area, 2.2 times larger for 1.5 2.0 than those tube. pressure drop increased, but smaller factor coefficient.« less