Forced convection film condensation on a horizontal tube—effect of surface temperature variation

✍ Scribed by S.B. Memory; W.C. Lee; J.W. Rose

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 458 KB
• Volume: 36
• Category: Article
• ISSN: 0017-9310
• DOI: 10.1016/s0017-9310(05)80076-6

✦ Synopsis

In free and forced convection condensation on a horizontal tube. measurements show that the surface temperature variation with angle approximately follows a cosine distribution. For forced convection condensation of steam. relatively low (with respect to isothermal-surfilce theoretical values) observed vapour-side heat-transfer coefficients have been attributed to surface temperature non-uniformity. A recent theoretical study ofthe effect of wall temperature variation in freeconvection condensation shows negligible erect on the average heat-transfer coeficient. In the present paper it is shown that. when a simple surpdcc shear stress approximation, which gives satisfactory values for the mean heat-transfer coefficient for an isothermal tube, is adopted with variable wall temperature. /I$IP~ mean surFace heat-transfer coeflicients are obtained. This seems to be in contradiction with results of conjugate (vapour-to-coolant) solutions which predict variable wall temperature and /OWW mean surface heat-transfer coefficients.

Reasons for this apparent anomaly are advanced.