A parametric study of nucleate boiling on structured surfaces part I: Effect of tunnel dimensions

Liang Han Chien*, Ralph L. Webb

*Corresponding author for this work

Research output: Contribution to journalJournal Article peer-review

16 Scopus citations

Abstract

This two-part experimental work identifies the effect of geometric dimensions on the boiling performance of "tunneled" enhanced boiling surfaces. The surface is formed on an integral-fin tube having a copper foil wrapped over the fin tips. Pores of known diameter and pitch are pierced in the foil cover. The resulting surface is similar to the Hitachi Thermoexcel-E tube. Tests were performed on a 19.1 mm diameter, horizontal tube using R-11 at 26.7°C for heat fluxes between 2-to-70 kW/m2. The cylindrical glass test cell permitted viewing of the boiling process. The first part of the study defines the effect of the tunnel dimensions (fin height, fin pitch, and tunnel shape) for a limited range of pore diameters (0.12-0.28 mm) and pore pitches (0.75-3.0 mm). Data are provided for tubes having 35, 40, and 50 fins/in and fin heights between 0.5 and 1.5 mm. The data show that greater tunnel height and smaller tunnel pitch are preferred. Sharp tunnel corners having a small corner radius also provides greater enhancement. However, the pore diameter and pore pitch have the most significant effect on the boiling enhancement. The boiling performance for R-11 and R-123 are nearly equal at the same saturation temperature.

Original languageEnglish
Pages (from-to)129-136
Number of pages8
JournalAmerican Society of Mechanical Engineers, Heat Transfer Division, (Publication) HTD
Volume326
StatePublished - 1996
Externally publishedYes

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