Effect of circumferentially nonuniform heating on laminar combined convection in a horizontal tube

S. V. Patankar, S. Ramadhyani, E. M. Sparrow

Research output: Contribution to journalArticle

64 Citations (Scopus)

Abstract

An analytical study has been made of how the circumferential distribution of the wall heat flux affects the forced/natural convection flow and heat transfer in a horizontal tube. Two heating conditions were investigated, one in which the tube was Uniformly heated over the top half and insulated over the bottom, and the other in which the heated and insulated portions were reversed. The results were obtained numerically for a wide range of the governing buoyancy parameter and for Prandtl numbers of 0.7 and 5. It was found that bottom heating gives rise to a vigorous buoyancy-induced secondary flow, with the result that the average Nusselt numbers are much higher than those for pure forced convection, while the local Nusselt numbers are nearly circumferentially uniform. A less vigorous secondary flow is i?iduced in the case of top heating because of temperature stratification, with average Nusselt numbers that are substantially lower than those for bottom heating and with large circumferential variations of the local Nusselt number. The friction factor is also increased by the secondary flow, but much less than the average heat transfer coefficient. It was also demonstrated that the buoyancy effects are governed solely by a modified Grashof number, without regard for the Reynolds number of the forced convection flow.

Original languageEnglish (US)
Pages (from-to)63-70
Number of pages8
JournalJournal of Heat Transfer
Volume100
Issue number1
DOIs
StatePublished - Feb 1978

Fingerprint

Nusselt number
secondary flow
forced convection
Secondary flow
convection
Buoyancy
buoyancy
tubes
Heating
heating
Forced convection
Grashof number
friction factor
Prandtl number
stratification
heat transfer coefficients
Natural convection
free convection
Heat transfer coefficients
Heat flux

Cite this

Effect of circumferentially nonuniform heating on laminar combined convection in a horizontal tube . / Patankar, S. V.; Ramadhyani, S.; Sparrow, E. M.

In: Journal of Heat Transfer, Vol. 100, No. 1, 02.1978, p. 63-70.

Research output: Contribution to journalArticle

Patankar, S. V. ; Ramadhyani, S. ; Sparrow, E. M. / Effect of circumferentially nonuniform heating on laminar combined convection in a horizontal tube . In: Journal of Heat Transfer. 1978 ; Vol. 100, No. 1. pp. 63-70.
@article{a088e0acf31e424488ca775dc4731b14,
title = "Effect of circumferentially nonuniform heating on laminar combined convection in a horizontal tube",
abstract = "An analytical study has been made of how the circumferential distribution of the wall heat flux affects the forced/natural convection flow and heat transfer in a horizontal tube. Two heating conditions were investigated, one in which the tube was Uniformly heated over the top half and insulated over the bottom, and the other in which the heated and insulated portions were reversed. The results were obtained numerically for a wide range of the governing buoyancy parameter and for Prandtl numbers of 0.7 and 5. It was found that bottom heating gives rise to a vigorous buoyancy-induced secondary flow, with the result that the average Nusselt numbers are much higher than those for pure forced convection, while the local Nusselt numbers are nearly circumferentially uniform. A less vigorous secondary flow is i?iduced in the case of top heating because of temperature stratification, with average Nusselt numbers that are substantially lower than those for bottom heating and with large circumferential variations of the local Nusselt number. The friction factor is also increased by the secondary flow, but much less than the average heat transfer coefficient. It was also demonstrated that the buoyancy effects are governed solely by a modified Grashof number, without regard for the Reynolds number of the forced convection flow.",
author = "Patankar, {S. V.} and S. Ramadhyani and Sparrow, {E. M.}",
year = "1978",
month = "2",
doi = "10.1115/1.3450505",
language = "English (US)",
volume = "100",
pages = "63--70",
journal = "Journal of Heat Transfer",
issn = "0022-1481",
publisher = "American Society of Mechanical Engineers(ASME)",
number = "1",

}

TY - JOUR

T1 - Effect of circumferentially nonuniform heating on laminar combined convection in a horizontal tube

AU - Patankar, S. V.

AU - Ramadhyani, S.

AU - Sparrow, E. M.

PY - 1978/2

Y1 - 1978/2

N2 - An analytical study has been made of how the circumferential distribution of the wall heat flux affects the forced/natural convection flow and heat transfer in a horizontal tube. Two heating conditions were investigated, one in which the tube was Uniformly heated over the top half and insulated over the bottom, and the other in which the heated and insulated portions were reversed. The results were obtained numerically for a wide range of the governing buoyancy parameter and for Prandtl numbers of 0.7 and 5. It was found that bottom heating gives rise to a vigorous buoyancy-induced secondary flow, with the result that the average Nusselt numbers are much higher than those for pure forced convection, while the local Nusselt numbers are nearly circumferentially uniform. A less vigorous secondary flow is i?iduced in the case of top heating because of temperature stratification, with average Nusselt numbers that are substantially lower than those for bottom heating and with large circumferential variations of the local Nusselt number. The friction factor is also increased by the secondary flow, but much less than the average heat transfer coefficient. It was also demonstrated that the buoyancy effects are governed solely by a modified Grashof number, without regard for the Reynolds number of the forced convection flow.

AB - An analytical study has been made of how the circumferential distribution of the wall heat flux affects the forced/natural convection flow and heat transfer in a horizontal tube. Two heating conditions were investigated, one in which the tube was Uniformly heated over the top half and insulated over the bottom, and the other in which the heated and insulated portions were reversed. The results were obtained numerically for a wide range of the governing buoyancy parameter and for Prandtl numbers of 0.7 and 5. It was found that bottom heating gives rise to a vigorous buoyancy-induced secondary flow, with the result that the average Nusselt numbers are much higher than those for pure forced convection, while the local Nusselt numbers are nearly circumferentially uniform. A less vigorous secondary flow is i?iduced in the case of top heating because of temperature stratification, with average Nusselt numbers that are substantially lower than those for bottom heating and with large circumferential variations of the local Nusselt number. The friction factor is also increased by the secondary flow, but much less than the average heat transfer coefficient. It was also demonstrated that the buoyancy effects are governed solely by a modified Grashof number, without regard for the Reynolds number of the forced convection flow.

UR - http://www.scopus.com/inward/record.url?scp=0017934627&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0017934627&partnerID=8YFLogxK

U2 - 10.1115/1.3450505

DO - 10.1115/1.3450505

M3 - Article

AN - SCOPUS:0017934627

VL - 100

SP - 63

EP - 70

JO - Journal of Heat Transfer

JF - Journal of Heat Transfer

SN - 0022-1481

IS - 1

ER -