Oregon State University
Nucleate boiling of various fluids in a thermosiphon reboiler.
Degree: MS, Chemical Engineering, 1986, Oregon State University
A study of nucleate boiling of water, four alcohols and
three ethanol-water mixtures was conducted in a vertical
thermosiphon reboiler. The test section consisted of a 1/2-
inch diameter electrically heated stainless-steel rod
jacketed by a 15-inch long pyrex glass tube. Two different
inside diameters of the glass tube corresponding
respectively to annuli of equivalent diameters 0.225 and
0.750 inch were used.
The purpose of the study was to investigate whether or
not there was an effect of the annulus gap on heat transfer
to the boiling liquids. Heat fluxes ranged from 17,000 to
91,000 Btu/hr.ft². Velocities were measured in an attempt
to simulate the natural-circulation data by means of a
micro-pump and a rotameter. The velocities so determined
varied from 0.093 to 1.171 ft/sec. Calculations have shown
wall superheats (wall-minus-saturation temperature) from
17.4 to 58.6°F, vapor qualities from 0.9 to 7.6% and heat transfer coefficients from 518 to 2473 Btu/hr.ft². °F.
An equation expressing the relationship between the
heat flux and the wall superheat raised to a power n was
developed for each fluid-diameter combination following a
statistical analysis of the data. It was observed that for
each fluid, the value of the exponent n was less for the
smaller diameter of the annulus and approached a value of
three for the larger diameter. This was attributed to a
much lower contribution of the convective heat transfer
component compared to the nucleate boiling heat transfer
component for the larger tube.
It was also observed that for the pure organic liquids,
no significant effect of the diameter was observed whereas
for water an increase in the annular width noticeably
decreased the heat transfer coefficient at a given degree of
saturation. For ethanol-water mixtures, it was observed
particularly at high heat flow rates, that the diameter
effect tended to disappear as the weight fraction of ethanol
in the solution was increased. However, although consistent
within itself, this result probably needs further
To check the validity of the experimental data,
comparisons were made with two commonly used equations in
boiling heat transfer: Chen's correlation and Rohsenow's
correlation. It was found that Chen's correlation usually
predicted higher heat transfer rates than the experimental
values. On the other hand, Rohsenow's correlation mostly predicted lower heat fluxes at De = 0.225 inch and mostly
higher heat fluxes at De = 0.750 inch than the experimental
data. Mean deviations for Rohsenow's equation were always
lower than those from Chen's equation for both diameter
Advisors/Committee Members: Knudsen, James G. (advisor), Schafer, D. (committee member).
Subjects/Keywords: Nucleate boiling
to Zotero / EndNote / Reference
APA (6th Edition):
Oufer, L. (1986). Nucleate boiling of various fluids in a thermosiphon reboiler. (Masters Thesis). Oregon State University. Retrieved from http://hdl.handle.net/1957/39806
Chicago Manual of Style (16th Edition):
Oufer, Lounes. “Nucleate boiling of various fluids in a thermosiphon reboiler.” 1986. Masters Thesis, Oregon State University. Accessed April 06, 2020.
MLA Handbook (7th Edition):
Oufer, Lounes. “Nucleate boiling of various fluids in a thermosiphon reboiler.” 1986. Web. 06 Apr 2020.
Oufer L. Nucleate boiling of various fluids in a thermosiphon reboiler. [Internet] [Masters thesis]. Oregon State University; 1986. [cited 2020 Apr 06].
Available from: http://hdl.handle.net/1957/39806.
Council of Science Editors:
Oufer L. Nucleate boiling of various fluids in a thermosiphon reboiler. [Masters Thesis]. Oregon State University; 1986. Available from: http://hdl.handle.net/1957/39806