A unified model for the prediction of bubble detachment diameters in boiling systems—II. Flow boiling

✍ Scribed by L.Z. Zeng; J.F. Klausner; D.M. Bernhard; R. Mei

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 794 KB
• Volume: 36
• Category: Article
• ISSN: 0017-9310
• DOI: 10.1016/s0017-9310(05)80112-7

✦ Synopsis

An improved model is proposed for the prediction of departure and lift-off diameters in saturated forced convection boiling. The model utilizes a force balance similar to that proposed by Klausner et al. (ht. J. Heat Mass Trunsfer 36,651-662 (1993)). One significant improvement is that the inclination angle is determined on a dynamic basis and is not required as an input. Furthermore, it is hypothesized that the surface tension force is small compared to other forces acting on a vapor bubble at the points of departure and lift-off, and thus information on the bubble contact diameter and contact angles is not required. A new data set on mean vapor bubble lift-off diameters and probability density functions (pdf's) for flow boiling of refrigerant R113 on a nichrome heating strip has been obtained using the experimental facility described by Klausner et 01. (ht. J. Heat Muss Trunsfer 36, 651-662 (1993)). The wall superheat and mean liquid velocity respectively range from 5.5 to 12.O"C and 0.35 to 1.0 m s-'. It is demonstrated that over the limited range of flow boiling conditions considered, the predicted departure and lift-off diameters agree well with measured values.