Combined forced and free laminar convection in horizontal tubes

Morcos, S. M.

doi:10.31274/rtd-180814-2309

Cited by 8 publications

(14 citation statements)

References 9 publications

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“…[97] shows that metal tube data are closer to boundary conditions of Case 1 than glass tube data corresponding to Case 2. The tube wall parameter suggests that in order to have uniform circumference tube wall temperature (Case 1), a thicker tube wall and higher thermal conductivity of tube should be utilized.…”

Section: Introductionmentioning

confidence: 77%

“…In general, the deviation between the present analysis and experimenr tal data from Morcos and Bergles [97] may come from the three sources listed below:…”

Section: Introductionmentioning

confidence: 79%

“…The test facility utilized in this investigation was constructed in the ISU Heat Transfer Laboratory by Dr. Morcos for his straight tube studies [97]. The facility was designed to allow flexibility in testing different kinds of fluids and tubes.…”

Section: Experimental Apparatus Test Loopmentioning

confidence: 99%

“…In view of this uncertainty, the heat input was taken from the electrical power input as corrected for the heat loss through the insulation. The heat loss to the surroundings was estimated to be about 1.5 percent of the total power input [97]. …”

Section: Experimental Apparatus Test Loopmentioning

confidence: 99%

“…Itorcos and Bergles [97] found that the pressure drop for water in an empty tube was too low to permit detection of pressure drop variations due to heating. Swirl flow generated by the twisted tape insert does not increase pressure drop significantly.…”

Section: Pressure Dropmentioning

confidence: 99%

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Laminar flow heat transfer in ordinary and augmented tubes

Hong

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Section: Introductionmentioning

confidence: 77%

“…In general, the deviation between the present analysis and experimenr tal data from Morcos and Bergles [97] may come from the three sources listed below:…”

Section: Introductionmentioning

confidence: 79%

Section: Experimental Apparatus Test Loopmentioning

confidence: 99%

Section: Experimental Apparatus Test Loopmentioning

confidence: 99%

Section: Pressure Dropmentioning

confidence: 99%

See 3 more Smart Citations

Laminar flow heat transfer in ordinary and augmented tubes

Hong

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Single-phase mixed convection of developing and fully developed flow in smooth horizontal circular tubes in the laminar and transitional flow regimes

Meyer

Everts

2018

International Journal of Heat and Mass Transfer

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Highlights• Three laminar regions: Forcedand Mixed Convection Developing and Fully Developed. • Thermal entrance length correlations for forced and mixed convection laminar flow. • Local and average laminar Nusselt number correlations for mixed convection flow. • Influence of free convection on the laminar-turbulent transition. ABSTRACT Correlations to calculate the local and average heat transfer coefficients for single-phase laminar flow through horizontal circular tubes with a constant heat flux boundary condition are usually restricted to fully developed flow, high Prandtl numbers or constant fluid properties. What further complicates the heat transfer characteristics of developing flow, is the local transition from laminar to turbulent flow along the tube length, above the critical Reynolds number. The purpose of this study was to investigate the effects of free convection on the development of the local heat transfer characteristics in smooth horizontal circular tubes heated with a constant heat flux. An experimental set-up was designed, built, and results were validated against literature. Two smooth circular test sections with innerdiameters of 4 mm and 11.5 mm were used, and the maximum length-to-diameter ratios were 1 373 and 872, respectively. Heat transfer measurements were taken at Reynolds numbers between 500 and 10 000 at different heat fluxes. A total of 1 046 mass flow rate measurements and 89 459 temperature measurements were taken. Water was used as the test fluid and the Prandtl number ranged between 3 and 7. Three different regions were identified for developing laminar flow and were qualitatively and quantitatively defined. Correlations were developed to determine the thermal entrance lengths, as well as local and average Nusselt numbers for developing and fully developed laminar flow in mixed convection conditions with a constant heat flux boundary condition. In the transitional flow regime, the laminar-turbulent transition along the tube length was divided into four regions, and it was

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Developing laminar mixed convection of nanofluids in an inclined tube with uniform wall heat flux

Mansour

Galanis

Nguyen

2009

International Journal of Numerical Methods for Heat &Amp; Fluid Flow

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Purpose -The aim is to study the conjugate problem of developing laminar mixed convection flow and heat transfer of water-Al 2 O 3 nanofluid inside an inclined tube submitted to a uniform wall heat flux. Design/methodology/approach -The set of non-linear, coupled and fully elliptic governing equations has been solved using a ''finite-control-volume'' numerical method, the classical power-law scheme for computing heat and momentum fluxes staggered and non uniform grids for spatial discretization of various regions of the tube. Findings -Numerical results have shown that the presence of nanoparticles slightly intensifies the secondary flow due to buoyancy, in particular in the developing region. It also increases the average Nusselt number and decreases slightly the product ReC f with respect to those of water. For the horizontal inclination, two new correlations have been proposed to calculate these two variables in the fully developed region, for Grashof number ranging from 10 3 to 10 5 and particle volume concentrations up to 7 per cent. Practical implications -The results of this study can be employed for various practical heat transfer and thermal applications using nanofluids. Originality/value -The present study constitutes an original contribution to the knowledge of nanofluid thermal behaviour.

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Combined forced and free laminar convection in horizontal tubes

Cited by 8 publications

References 9 publications

Laminar flow heat transfer in ordinary and augmented tubes

Laminar flow heat transfer in ordinary and augmented tubes

Single-phase mixed convection of developing and fully developed flow in smooth horizontal circular tubes in the laminar and transitional flow regimes

Developing laminar mixed convection of nanofluids in an inclined tube with uniform wall heat flux

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