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Technical Brief

Improvement of Correlative Approaches for Mixed Convective Flow Through a Horizontal Vent

[+] Author and Article Information
Kevin Varrall, Samuel Vaux

Laboratoire de Recherche Commun ETiC,
Institut de Radioprotection et de Sûreté
Nucléaire (PSN-RES/SA2I),
Centre de Cadarache,
St Paul Lez Durance 13115, France

Hugues Pretrel

Laboratoire de Recherche Commun ETiC,
Institut de Radioprotection et de Sûreté
Nucléaire (PSN-RES/SA2I),
Centre de Cadarache,
St Paul Lez Durance 13115, France
e-mail: hugues.pretrel@irsn.fr

Olivier Vauquelin

Laboratoire IUSTI,
Aix Marseille Université,
UMR 7343, 5 Rue Enrico Fermi,
Marseille Cedex 13453, France

1Corresponding author.

Contributed by the Heat Transfer Division of ASME for publication in the JOURNAL OF HEAT TRANSFER. Manuscript received February 16, 2018; final manuscript received December 3, 2018; published online January 25, 2019. Assoc. Editor: Antonio Barletta.

J. Heat Transfer 141(3), 034501 (Jan 25, 2019) (5 pages) Paper No: HT-18-1094; doi: 10.1115/1.4042330 History: Received February 16, 2018; Revised December 03, 2018

This study deals with the mixed convection flow through a shallow horizontal vent linking two compartments (one over the other). Depending on the temperature difference of gas as well as the ventilation flow rate between the two compartments, the flow through the vent can be bi- or uni-directional. A literature survey highlights that three correlations are used in safety engineering to calculate these upward and downward mixed convection flow rates. Unfortunately, for the same conditions, these correlations give very different results and, to date, there is no common agreement in the scientific community to identify quantitatively the most accurate model. This study proposes a new assessment of these correlations based on new experimental data obtained from the laboratory facility as well from the industrial apparatus. In addition, an improvement of the best model is proposed which better reproduced the experimental results.

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References

Cooper, L. Y. , 1989, “ Calculation of the Flow Through a Horizontal Ceiling/Floor Vent,” National Institute of Standards and Technology, Gaithersburg, MD, Standard No. NISTIR 89-4052.
Epstein, M. , 1988, “ Buoyancy Driven Exchange Flow Through Small Openings in Horizontal Partitions,” ASME J. Heat Transfer, 110(4a), pp. 885–893. [CrossRef]
Tan, Q. , and Jaluria, Y. , 1992, “ Flow Through Horizontal Vents as Related to Compartment Fire Environments,” National Institute of Standards and Technology, Gaithersburg, MD, Standard No. NIST-GCR-92-607.
Li, Z. , 2007, “ Characteristics of Buoyancy Driven Natural Ventilation Through Horizontal Openings,” Ph.D. thesis, Aalborg University, Aalborg, Denmark. http://vbn.aau.dk/en/publications/characteristics-of-buoyancy-driven-natural-ventilation-through-horizontal-openings(a2920120-4bdf-11dc-a457-000ea68e967b).html
Varrall, K. , Pretrel, H. , Vaux, S. , and Vauquelin, O. , 2016, “ Stereoscopic Particle Image Velocimetry Investigation of the Bidirectional Natural Convection Flow Through a Horizontal Vent,” Fire Technol., 52(6), pp. 2027–2041. [CrossRef]
Mercer, A. , and Thompson, H. , 1975, “ An Experimental Investigation of Some Further Aspects of the Buoyancy-Driven Exchange Flow Between Carbon Dioxide and Air Following a Depressurization Accident in a Magnox Reactor, Part I: The Exchange Flow in Inclined Ducts—Part II: The Purging Flow Requirements in Inclined Ducts,” J. British Nucl. Energy Soc., 14(4), pp. 327–340. https://inis.iaea.org/search/search.aspx?orig_q=RN:7233965
Epstein, M. , and Kenton, M. A. , 1989, “ Combined Natural Convection and Forced Flow Through Small Openings in a Horizontal Partition, With Special Reference to Flows in Multicompartment Enclosures,” ASME J. Heat Transfer, 111(4), pp. 980–987. [CrossRef]
Cooper, L. Y. , 1994, “ Combined Buoyancy- and Pressure-Driven Flow Through a Horizontal Vent,” National Institute of Standards and Technology, Gaithersburg, MD, Standard No. NISTIR 5384.
Heskestad, G. , and Spalding, R. D. , 1991, “ Inflow of Air Required at Wall and Ceiling Apertures to Prevent Escape of Fire Smoke,” Third International Symposium on Fire Safety Science, Scotland, UK, July 8–12, pp. 919–928.
Emmons, H. W. , and Tanaka, T. , 2002, “ Buoyant Flows Through Horizontal Vents,” SFPE Handbook of Fire Protection Engineering, P. J. DiNenno , ed., 4th ed., National Fire Protection Association Press, Quincy, MA, pp. 2.44–2.45.
Tan, Q. , and Jaluria, Y. , 2001, “ Mass Flow Through a Horizontal Vent in an Enclosure Due to Pressure and Density Differences,” Int. J. Heat Mass Transfer, 44(8), pp. 1543–1553. [CrossRef]
Le Quesne, M. A. , 2010, “ Saltwater Modelling of Fire Gas Flow Through a Horizontal Ceiling Opening,” Ph.D. thesis, University of Canterbury, Canterbury, New Zealand. https://ir.canterbury.ac.nz/handle/10092/4304
Chow, W. K. , and Li, J. , 2011, “ On the Bidirectional Flow Across an Atrium Ceiling Vent,” Building Environ., 46(12), pp. 2598–2602. [CrossRef]
Pretrel, H. , Sayada, R. , Varrall, K. , Audouin, L. , and Vauquelin, O. , 2017, “ Experimental Study Based on Large-Scale Smoke Propagation Fire Tests Through a Horizontal Opening Connecting Two Mechanically Ventilated Compartments,” Fire Saf. J., 90, pp. 28–43. [CrossRef]
Varrall, K. , Pretrel, H. , Vaux, S. , and Vauquelin, O. , 2017, “ Stereoscopic Particle Image Velocimetry Investigations of the Mixed Convection Exchange Flow Through a Horizontal Vent,” Exp. Fluids, 58, p. 151.

Figures

Grahic Jump Location
Fig. 1

Schematic representation of the different flow regimes through the horizontal vent as a function of the mechanical ventilation flow rate qf acting in the lower compartment: (a) uni-directional downward, (b) bi-directional, and (c) uni-directional upward

Grahic Jump Location
Fig. 2

Evolution of the flow rate at the vent as a function of the pressure difference between the two compartments where the three correlations are computed with the same initial fixed conditions (D =1 m, ρ = 0.6 kg/m3, and ρ0 = 1.2 kg/m3). The circles are for relation (1.1), the “plus” are for relation (1.2), the squares are for relation (1.3), and the asterisks are for relation (1.4). (a) wide range of ΔPf and (b) zoom on low values of ΔPf.

Grahic Jump Location
Fig. 3

Evolution of the dimensionless flow rate through the vent as a function of the dimensionless ventilation flow rate for the experimental database. (a) presents the downward flow and (b) presents the upward flow. The square symbols are for Pretrel et al.[14], all the other symbols are for Varrall et al. [15] where the circles correspond to D =0.127 m, the cross to D =0.152 m, and the asterisks to D =0.191 m.

Grahic Jump Location
Fig. 4

Comparison between the experimental data and the results obtained with the existing correlations for the experimental corresponding conditions. (a) Presents the downward flow and (b) presents the upward flow. The cross symbols are for the experimental data Varrall et al. [15] and Pretrel et al. [14], the circles are for relation (1.1), the “plus” are for relation (1.2), the squares are for relation (1.3) and the asterisks are for relation (1.4).

Grahic Jump Location
Fig. 5

Evolution of AUC as a function of α. Top: (3.1) with (a) Π approach and (b) Λ approach. Bottom: (3.2) with (c) Π approach and (d) Λ approach.

Grahic Jump Location
Fig. 6

Cumulative distribution functions of x for the different correlations. The circles are for relation (1.1), the “plus“ are for relation (1.2), the squares are for relation (1.3) and the asterisks are for relation (1.4). The continuous line is for relation (3.1) with α = 0.37 and Π approach. The dashed line refers to a hypothetical 100% relative error estimator.

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