A numerical model for a bubble in nucleate pool boiling

dc.contributor.advisor Joseph Prusa
dc.contributor.author Patil, Rajendra
dc.contributor.department Mechanical Engineering
dc.date 2018-08-15T05:16:40.000
dc.date.accessioned 2020-07-02T06:14:57Z
dc.date.available 2020-07-02T06:14:57Z
dc.date.copyright Tue Jan 01 00:00:00 UTC 1991
dc.date.issued 1991
dc.description.abstract <p>Growth of a hemispherical bubble in nucleate pool boiling is analyzed in two stages using a numerical technique. In the first stage, growth of a hemispherical bubble in viscous medium on an isothermally heated surface is investigated neglecting the microlayer contribution. The results are compared with an analytical solution for homogeneous growth in a superheated medium, to other numerical results for heterogeneous growth in an inviscid medium, and to previous experimental work. The flow field and temperature distribution around the bubble are found to exhibit similarity for large times when an appropriate non-dimensionalization is used. The Jakob number (Ja), and subcooling number (Sb) are the only similarity parameters controlling growth in this asymptotic regime;In the second stage, growth of a hemispherical bubble is investigated including the analyses of a microlayer, the non-condensible gas inside the bubble and the temperature distribution in the heated surface. The temperature distribution in the fluid and in the solid, and the microlayer profile is found to be self similar for large time. The microlayer profile is almost triangular except at the tail point, where it is very steep. The famous "bulk convection" theory is found to be questionable. In accordance with experimental observations recorded in the literature, the growth of a bubble with a microlayer is found to be equal to that in homogeneous superheated medium for equal Jakob numbers. Pressure in the bubble is almost equal to the pressure of the environment except in the extremely short initial period. The bubble growth relation in saturated boiling isR = const Ja[superscript]3/4[over] Pr[superscript]1/4 √tfor 10 ≤ Ja ≤ 640, 0.26 ≤ Pr≤ 2.33, where Pr is the Prandtl number and the value of the constant is approximately 5. The contribution to bubble growth from the microlayer has been found to be 90% for Ja~eq 10, Pr~eq 2.5, 99% for Ja~eq 80, Pr ~eq 1, and as high as 99.8% for Ja~eq 320, Pr~eq 0.2. The flow field inside the bubble is investigated with and without the microlayer. The gas inside the bubble is proved to be at an uniform state in both the cases.</p>
dc.format.mimetype application/pdf
dc.identifier archive/lib.dr.iastate.edu/rtd/9674/
dc.identifier.articleid 10673
dc.identifier.contextkey 6360807
dc.identifier.doi https://doi.org/10.31274/rtd-180813-12480
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath rtd/9674
dc.identifier.uri https://dr.lib.iastate.edu/handle/20.500.12876/82798
dc.language.iso en
dc.source.bitstream archive/lib.dr.iastate.edu/rtd/9674/r_9212177.pdf|||Sat Jan 15 02:36:05 UTC 2022
dc.subject.disciplines Mechanical Engineering
dc.subject.keywords Mechanical engineering
dc.title A numerical model for a bubble in nucleate pool boiling
dc.type article
dc.type.genre dissertation
dspace.entity.type Publication
relation.isOrgUnitOfPublication 6d38ab0f-8cc2-4ad3-90b1-67a60c5a6f59
thesis.degree.level dissertation
thesis.degree.name Doctor of Philosophy
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