BK1-3 Boiling on the Outside of Horizontal Finned Tubes

C. C. Shih and J. W. Palen

Finned tubes have been shown to be very effective for boiling service under the right conditions. HTRI kettle reboiler studies included data for boiling of various liquids on low-finned tubes. Previously, the HTRI prediction of heat transfer was based upon an empirical correction to the plain tube method. Recent studies in the literature have permitted a reexamination of the data leading to improved heat transfer prediction methods.

This report discusses the background and theory of boiling on fins, documents the improved prediction methods, and presents new information about optimum fin design for boiling service. A finite difference method to calculate the fin efficiency for boiling service is given in the Appendix. This method was further corrected empirically to account for surface effects and for lower efficiency at low pressure due to vapor binding of the fin valleys. The new methods were incorporated in the HTRI RKH-1 Computer Program in Mod. 5.0.