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Journal ArticleDOI

Heat transfer from flames between vertical parallel walls

01 Jan 1995-Fire Safety Journal (Elsevier)-Vol. 24, Iss: 1, pp 53-73
TL;DR: In this paper, the authors measured the distribution of total heat flux on a wall exposed to a line burner for a number of configurations in which the distance to a parallel wall has been varied.
About: This article is published in Fire Safety Journal.The article was published on 1995-01-01. It has received 28 citations till now. The article focuses on the topics: Heat flux & Heat transfer.
Citations
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Journal ArticleDOI
01 Jan 2009
TL;DR: In this paper, a new length scale, l(3), representing the length after which the flames turn from horizontal to vertical was developed, and the significance of this length scale has been verified by the experimental results for flame heights and heat fluxes and by observations.
Abstract: Flames emerging from an opening of a fully developed burning room are the main path of a fire spreading from floor to floor and to an adjacent building. Even though the issue of fire spread to an adjacent building has been incorporated in fire safety engineering design guidelines, performance-based design provides an alternative and accurate method to optimize the distance between the building facade with a burning enclosure and an adjacent building. This situation Was Simulated by performing a series of small scale experiments having a facade wall with flames and an opposite parallel wall representing an adjacent building in order to investigate the physics of the flame behaviour and measure the heat fluxes between two walls. The outcome of this research provides unique information for engineering design for separation distances between adjacent buildings. A new length scales, l(3), representing the length after which the flames turn from horizontal to vertical was developed in this research. The significance of this length scale has been verified by the experimental results for flame heights and heat fluxes and by observations. Similarity correlations for flame heights between the two parallel walls were developed in this research. Similarity correlations for radiative heat fluxes on facade walls were developed by dividing the data into two groups. One is for the distance between two walls being larger than length scale, the other is for the distance being less or equal to length scale l(3). Measurements of the heat fluxes on the opposite wall allow also the determination of the total radiant output. (c) 2009 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

62 citations

Journal ArticleDOI
TL;DR: In this article, two sets of data are presented, one based on experiments with 6 mm thick PMMA slabs (heights 25-250 mm, width 50-150 mm) as the fire source, measuring (Q) over dot (/) and X-f simultaneously.
Abstract: Previous work has demonstrated that flame height is one of the two most important parameters determining the rate of vertical flame spread on a wall. Flame spread models rely on empirical flame height correlations of the form X-f = K(Q) over dot(/n), but there have been no carefully controlled experiments designed to establish the validity of such correlations and there are no data for values of (Q) over dot(/) less than c.25 kW/m. Two new sets of data are presented here, one based on experiments with 6 mm thick PMMA slabs (heights 25-250 mm, width 50-150 mm) as the fire source, measuring (Q) over dot (/) and X-f simultaneously. This set relates to the early stages of a wall fire when (Q) over dot(/) less than 30 kW/m. The other set of data was obtained with a vertical gas-fired panel which consisted of an array of 14 independent burners arranged to allow the aspect ratio of the burning surface to be varied. The data confirm that the flame height correlates with (Q) over dot(/), but reveal (inter alia) that there are two regions, for values of (Q) over dot(/) greater than and less than c. 20 kW/m. An existing upward flame spread model was modified to allow these two correlations to be incorporated to predict the development of a small fire on a vertical surface for these two regions, which would provide more realistic modelling information.

59 citations

Journal ArticleDOI
TL;DR: In this paper, a preliminary approach towards commodity classication is presented that models the early stage of large-scale warehouse res by decoupling the problem into separate processes of heat and mass transfer.

30 citations

Journal ArticleDOI
TL;DR: It is found that the outputs from these tests were correlated, which could be used to gain more information of facade performance than simply pass or fail; and that the different layers of a facade can have a significant effect, particularly the addition of a cavity.

27 citations

DOI
01 Dec 2018
TL;DR: In this article, the authors discuss the drivers for flammability in facades, the interaction of facade materials, and current gaps in knowledge, and put forward an integral framework of design that uses multi-objective optimization to ensure that flammable is minimized while considering other objectives, such as maximizing thermal performance or minimizing weight.
Abstract: The facade is an important, complex, and costly part of a building, performing multiple objectives of value to the occupants, like protecting from wind, rain, sunlight, heat, cold, and sound. But the frequency of facade fires in large buildings is alarming, and has multiplied by seven times worldwide over the last three decades, to a current rate of 4.8 fires per year. High-performing polymer based materials allow for a significant improvement across several objectives of a facade (e.g., thermal insulation, weight, and construction time) thereby increasing the quality of a building. However, all polymers are flammable to some degree. If this safety problem is to be tackled effectively, then it is essential to understand how different materials, and the facade as a whole, perform in the event of a fire. This paper discusses the drivers for flammability in facades, the interaction of facade materials, and current gaps in knowledge. In doing so, it aims to provide an introduction to the field of facade fires, and to show that because of the drive for thermal efficiency and sustainability, facade systems have become more complex over time, and they have also become more flammable. We discuss the importance of quantifying the flammability of different facade systems, but highlight that it is currently impossible to do so, which hinders research progress. We finish by putting forward an integral framework of design that uses multi-objective optimization to ensure that flammability is minimized while considering other objectives, such as maximizing thermal performance or minimizing weight.

27 citations

References
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Book
31 Dec 1990
TL;DR: Babrauskas and Grayson as mentioned in this paper, Heat Release in Fires, Interscience Communications Ltd, London (1992; reprinted 2009). xii, 623 pages, illustrated, hardbound.
Abstract: V. Babrauskas and S. J. Grayson, eds., Heat Release in Fires, Interscience Communications Ltd, London (1992; reprinted 2009). xii, 623 pages, illustrated, hardbound. ISBN: 978-0-9556548-4-8. The original book publisher was Elsevier Applied Science. The current reprint is from Interscience Communications Ltd.: ordering information. List price: £95 plus p+p (UK £4.50, Europe £8.00, Rest of world £14.50). Few booksellers carry this book (especially charging no more than the list price!), thus it is recommended that it be ordered directly from the publishers.

390 citations

Journal ArticleDOI
TL;DR: In this article, a linear integral equation of the Volterra type is derived for the spread rate of turbulent flames along thermally thick vertical sheets for both noncharring and charring fuels.
Abstract: Mechanisms and rates of upward spread of turbulent flames along thermally thick vertical sheets are considered for both noncharring and charring fuels. By addressing the time dependence of the rate of mass loss of the burning face of a charring fuel, a linear integral equation of the Volterra type is derived for the spread rate. Measurements of spread rates, of flame heights and of surface temperature histories are reported for polymethylmethacrylate and for Douglas-fir particle board for flames initiated and supported by a line-source gas burner, with various -rates of heat release, located at the base of the fuel face. Sustained spread occurs for the synthetic polymer and not for the wood. Comparisons of measurements with theory aid in estimating characteristic parameters for the fuels.

158 citations

Journal ArticleDOI
TL;DR: In this article, heat transfer and flame height results are presented for wall samples burned at varying levels of external irradiance, and an approximate theoretical analysis is included to serve as a guide to identifying the important variables and their relationship for correlation purposes.
Abstract: New concepts are addressed for predicting the flame spread on materials from laboratory measurements. It focuses on heat transfer which precipitates and precedes upward flame spread on a vertical surface. Six materials have been featured in this study as well as in past related studies. Their flame spread properties are presented. In this particular study heat transfer and flame height results are presented for wall samples burned at varying levels of external irradiance. Also complementary results are presented for methane line burner wall fires. An approximate theoretical analysis is included to serve as a guide to identifying the important variables and their relationship for correlation purposes. Experimental results yield flame height proportional to energy release rate to the 2/3 power, and wall heat flux distributions are roughly correlated in terms of distance divided by flame height. These correlations appear to at least hold for the scale of these experiments: flame heights of 0.3 to 1....

135 citations

Journal ArticleDOI
TL;DR: In this article, measurements of temperature distribution and visible flame height were made on the fire plumes from square burners in a semi-infinite space, against a wall and in a corner of walls, and the maximum temperature on each height was formulated with the concept of virtual heat source.
Abstract: Measurements of temperature distribution and visible flame height were made on the fire plumes from square burners in a semi-infinite space, against a wall and in a corner of walls, Flame height is formulated as a function of Q * = Q/poC p T og3/4 D 3/4;52 and the maximum temperature on each height was formulated with the concept of virtual heat source. According to the comparison of the results on the fires against a wall and, n a corner of walls with those in a semi-infinite space, the existence of walls near a fire source is thought to suppress the growth of eddy scale in the plume. The characteristics of natural fuels as sources of turbulent diffusion flame are also discussed.

103 citations

Journal ArticleDOI
TL;DR: A survey of the characteristics and predictions of the different theoretical models of the spread of flames over the surface of a solid combustible in opposed or concurrent oxidizing flows is presented in this paper.
Abstract: A survey of the characteristics and predictions of the different theoretical models of the spread of flames over the surface of a solid combustible in opposed or concurrent oxidizing flows shows that, at present, there is a good understanding of what are the controlling mechanisms of the flame spread process andl of what is the necessary formulation to develop a rigorous analysis of the phenomenon. It also shows, however, that the problem is very complicated and difficult to solve mathematically particularly if an analytical solution is sought, and that this complexity is what has prevented so far the development of an analysis capable of describing accurately the flame spread process under realistic conditions where material properties, finite rate kinetics, turbulence and radiation effects can determine the characteristics of the process. Although some of the analyses presently available are capable of predicting quantitatively or at least qualitatively rates of flame spread under certain limit...

89 citations