Heat Transfer and Flow Characteristics of a Non-Uniformly Heated Tube Under Low Pressure and Low Mass Flux Condition

Umekawa, Hisashi; Hirayama, Mio; Kitajima, Tetsuo; Ozawa, Mamoru; Mishima, Kaichiro; Saitō, Yasushi

doi:10.1615/multscientechn.v18.i4.40

Cited by 3 publications

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“…However, the simple estimation value by using Eq. (1) agreed with the calculation value by the finite element method within 7% [5]. In the case of the eccentric tube of e = 1.5 mm, the ratio of the maximum heat flux and minimum heat flux was q max / q min = 7.…”

Section: Methodssupporting

confidence: 80%

“…The typical experimental results of the time-averaged local heat transfer coefficient are plotted against the pseudo-thermodynamic equilibrium quality x eq,local [5] in Figs. 5 and 6.…”

Section: Heat Transfer Characteristicsmentioning

confidence: 99%

“…12, CHF characteristics under an inclined upward flow condition are estimated by using the quality at the CHF point x CHF and modified Froude number condition by the difference in the dryout quality between the top and bottom of the tube under the CHF condition, but in this paper, for simplification, x = 1, i.e., complete dryout was used instead of the quality at the tube bottom, as shown in Eq. (5).…”

Section: Critical Heat Fluxmentioning

confidence: 99%

“…As a result, the maximum local CHF of an eccentric tube was found to be higher than the CHF of a normal tube, and the rate of CHF was increased with an increase in the non-uniformity. This CHF characteristic was explained by Butterworth's [4] redistribution of the liquid film model [5,6]. Moreover, to evaluate the influence factor of the liquid film redistribution, the investigation of a long tube (1800 mm) was also reported [7].…”

Section: Introductionmentioning

confidence: 99%

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CHF in a circumferentially non‐uniformly heated tube under low‐pressure and low‐mass‐flux condition (inclined upward flow)

Ami

Umekawa

Ozawa

et al. 2011

Heat Trans. Asian Res.

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Most investigations on forced convective boiling have been conducted by using uniformly heated round tubes under a vertical upward flow condition, although the actual system has a non‐uniformly heated condition with several tube orientations. The non‐uniformity of the heat flux and tube inclination causes the liquid film distribution, which in turn affects the critical heat flux. In this investigation, the flow and heat‐transfer characteristics were experimentally investigated under non‐uniformly heated conditions along the circumferential direction with a 45° tube inclination. In the experiment, CHF was measured by using two different heated lengths, i.e., 900 and 1800 mm. The experimental results showed a unique tendency of CHF caused by the interrelationship of the non‐uniform heat flux distribution, the tube inclination, and liquid film redistribution. © 2011 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/htj.20333

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Section: Methodssupporting

confidence: 80%

“…The typical experimental results of the time-averaged local heat transfer coefficient are plotted against the pseudo-thermodynamic equilibrium quality x eq,local [5] in Figs. 5 and 6.…”

Section: Heat Transfer Characteristicsmentioning

confidence: 99%

Section: Critical Heat Fluxmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

CHF in a circumferentially non‐uniformly heated tube under low‐pressure and low‐mass‐flux condition (inclined upward flow)

Ami

Umekawa

Ozawa

et al. 2011

Heat Trans. Asian Res.

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CHF in a Circumferentially Non-Uniformly Heated Tube under Low Pressure and Low Mass Flux Condition (Influence of the Magnitude of Heat Flux)

Ami

Umekawa

Ozawa³

et al. 2011

Trans.JSME, Ser.B

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Critical Heat Flux (CHF) in a non-uniformly heated tube is a very important designing factor of actual boiling two-phase flow equipments. In this series of studies, the CHF in a non-uniformly heated tube was discussed by using the re-distribution of a liquid film caused by the wave interaction. In the present investigation, in order to estimate the influence of the entrainment of droplet under the high heat flux condition on the re-distribution of liquid film, the CHF experiment was conducted. The experimental apparatus was a similar to the forced convective boiling system described in the previous paper, i.e. the eccentric tube with 20 mm I.D., 24 mm O.D., but heated length was just only 450 mm to keep the high heat flux condition. The experimental result expressed the influence of the magnitude of the heat flux as the increasing in the entrainment. The CHF was occurred at the high quality condition, i.e. liquid film dryout and at the low quality condition, i.e. departure from nucleate boiling (DNB), respectively. This obtained CHF was evaluated by using the film flow model, and the empirical correlation of the spreading coefficient of liquid film re-distribution was proposed.

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健行¹,

尚嗣²,

守³

et al. 2008

JAPANESE JOURNAL OF MULTIPHASE FLOW

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Heat Transfer and Flow Characteristics of a Non-Uniformly Heated Tube Under Low Pressure and Low Mass Flux Condition

Cited by 3 publications

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CHF in a circumferentially non‐uniformly heated tube under low‐pressure and low‐mass‐flux condition (inclined upward flow)

CHF in a circumferentially non‐uniformly heated tube under low‐pressure and low‐mass‐flux condition (inclined upward flow)

CHF in a Circumferentially Non-Uniformly Heated Tube under Low Pressure and Low Mass Flux Condition (Influence of the Magnitude of Heat Flux)

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