Dry-out CHF correlation for R134a flow boiling in a horizontal helically-coiled tube

Chen, C.-N.; Han, J.-T.; Jen, T.-C.; Shao, L.

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Chen, C.-N., Han, J.-T., Jen, T.-C., Shao, L.. Elsevier; 2011. Dry-out CHF correlation for R134a flow boiling in a horizontal helically-coiled tube.

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Please use this identifier to cite or link to this item: http://hdl.handle.net/10210/14955

Title: Dry-out CHF correlation for R134a flow boiling in a horizontal helically-coiled tube
Creator: Chen, C.-N.
Creator: Han, J.-T.
Creator: Jen, T.-C.
Creator: Shao, L.
Subject: Critical heat flux
Subject: Helically coiled tubes
Subject: Heat transfer
Date: 2011
Publisher: Elsevier
Description: An experimental study was carried out to investigate the R134a dry-out critical heat flux (CHF) characteristics in a horizontal helically-coiled tube. The test section was heated uniformly by DC high-power source, and its geometrical parameters are the outer diameter of 10 mm, inner diameter of 8.4 mm, coil diameter of 300 mm, helical pitch of 75 mm and valid heated length of 1.89 m. The experimental parameters are the outlet pressures of 0.30–0.95 MPa, mass fluxes of 60–500 kg m 2 s 1, inlet qualities of 0.36–0.35 and heat fluxes of 7.0 103–5.0 104 Wm 2. A method based on Agilent BenchLink Data Logger Pro was developed to determine the occurrence of CHF with a total of 68 T-type thermocouples (0.2 mm) set along the tube for accurate temperature measurement. The characteristics of wall temperatures and the parametric effect on dry-out CHF showed that temperature would jump abruptly at the point of CHF, which usually started to form at the front and offside (270 and 90 ) of the outlet crosssection. The CHF values decrease nearly linearly with increasing inlet qualities, while they decrease more acutely with increasing critical qualities, especially under larger mass flux conditions. The mass flux has a positive effect on CHF enhancement, but the pressure has negative one. A new dimensionless correlation was developed to estimate dry-out CHF of R134a flow boiling in horizontal helically-coiled tubes under current experimental conditions and compared to calculated results from Bowring and Shah correlations.

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collection(s): 11067
collection(s): Journal articles
Identifier: uj:5286
Identifier: http://hdl.handle.net/10210/14955
Type: Article
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11067

Journal articles Dry-out CHF correlation for R134a flow boiling in a horizontal helically-coiled tube

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