Heat Transfer Enhancement and RTD in Pipes with Flow Inversion

Žitný, Rudolf; Luong, Thi Cam Tu; Střasák, P.; Šesták, Jaroslav

doi:10.1080/01457630490443794

Cited by 4 publications

(4 citation statements)

References 4 publications

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“…The relative increase of Nu, corresponding to the wall layer flow inverter, is reproduced from Zitny et al [15] in Figures 11 and 12, and is compared with the data measured with flow inverters A and B, respectively.…”

Section: Theoretical Prediction Of Heat Transfer Enhancement By Flow mentioning

confidence: 98%

“…The paper by Zitny et al [15] presented mathematical models of partial flow inverters, characterized by division of the inlet flow rate into three streams, with two of them being inverted and perfectly mixed, while the wall layer passes directly without mixing. Inversion efficiency is defined as the ratio of the inverted flow rate to the overall flow rate ϕ.…”

Section: Theoretical Prediction Of Heat Transfer Enhancement By Flow mentioning

confidence: 99%

“…Viscosity was measured by a Rheotest RV rotational rheometer in several cylinder/cylinder configurations, and no deviation from Newtonian behavior was registered within the range of shear rates 0.81 to 1312 1/s. Viscosity-temperature dependence was correlated by 15 (2)…”

Section: Working Liquidmentioning

confidence: 99%

“…Thus the installation of the flow inverter has only a local effect on the pressure drop, while the heat transfer is affected globally, in a significant section of a straight pipe behind the flow inverter. Local and only partial flow inversion can be achieved, for example, by using a locally curved pipe (Zitny et al [15]) or by using two parallel inclined ribs or wrappings; see Strasak [16]. However, these arrangements work only at sufficiently high Reynolds numbers (typically Re >50).…”

Section: Introductionmentioning

confidence: 99%

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Heat Transfer Enhancement in a Pipe Using a Flow Inverter

Žitný

Luong

Šesták

2009

Heat Transfer Engineering

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Flow inversion, transferring a liquid from the wall region toward the center of the pipe or from the axis toward the heat transfer surface, improves heat transfer in the laminar flow regime. While a fully developed velocity profile is quickly established, a thin thermal boundary layer is preserved for a considerable distance in the pipe behind the flow inverter for highly viscous liquids. Thus the pressure drop is increased only locally (by the inverter itself), while heat transfer enhancement is also seen in a long straight section of the pipe. Two original flow inverter designs were tested in a long pipe (3 m in length) heated by condensing steam, using starch molasses as a working medium. Experiments carried out in the range of Reynolds number 4-60 and Graetz number 150-700 resulted in an increase of 20-35% in the heat transfer coefficient, accompanied by a 30-40% increase in the pressure drop. The experimental results confirm the numerical model prediction (within an extendedReynolds number range starting from 0.1). Thus an almost 40% increase in heat transfer can be expected at the optimal Graetz number in the range 50-100, using only one flow inverter located in the middle of a sufficiently long pipe.

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Section: Theoretical Prediction Of Heat Transfer Enhancement By Flow mentioning

confidence: 98%

Section: Theoretical Prediction Of Heat Transfer Enhancement By Flow mentioning

confidence: 99%

Section: Working Liquidmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Heat Transfer Enhancement in a Pipe Using a Flow Inverter

Žitný

Luong

Šesták

2009

Heat Transfer Engineering

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Influence of Rheological Behavior of Purely Viscous Fluids on Analytical Residence Time Distribution in Straight Tubes

et al. 2008

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In an effort to better understand the homogeneity of heat treatment of foodstuffs in holding tubes, the cumulative residence time distribution function is derived for a Herschel-Bulkley fluid from fully developed laminar flow in a straight circular tube under isothermal conditions when diffusional effects are negligible. The proposed analytical solution can be reduced to solutions for Newtonian, shearthinning, dilatant, Bingham fluids by setting particular rheological parameters, and consequently, it is possible to successfully explain the dependence of residence time distribution on fluid properties for almost all of the rheological models used for time-independent purely viscous fluids.

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The influence of secondary refrigerant air chiller U-bends on fluid temperature profile and downstream heat transfer for laminar flow conditions

Clarke

Finn

2008

International Journal of Heat and Mass Transfer

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Heat Transfer Enhancement and RTD in Pipes with Flow Inversion

Cited by 4 publications

References 4 publications

Heat Transfer Enhancement in a Pipe Using a Flow Inverter

Heat Transfer Enhancement in a Pipe Using a Flow Inverter

Influence of Rheological Behavior of Purely Viscous Fluids on Analytical Residence Time Distribution in Straight Tubes

The influence of secondary refrigerant air chiller U-bends on fluid temperature profile and downstream heat transfer for laminar flow conditions

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