Nonlinear thermal optimization of external light concrete multi-holed brick walls by the finite element method

Díaz, J.; Nieto, P.J. Garcı́a; Sierra, J.L. Suárez; Biempica, C. Betegón

doi:10.1016/j.ijheatmasstransfer.2007.07.029

Cited by 66 publications

(24 citation statements)

References 4 publications

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“…Exhaustive bibliographic reviews of the coupled heat transfers by convection, conduction, and/or radiation in hollow structures were made in previous works (Ait-Taleb et al 2008;Abdelbaki et al 2001;Abdelbaki and Zrikem 1999). Other studies of this problem were presented recently by del Coz Díaz et al (2008aDíaz et al ( , 2008b which treated the nonlinear heat transfer in light concrete hollow brick walls using the finite element method. Because of the nonlinearity of heat convection and radiation, the transfer function methods usually used to predict conductive heat transfer through building walls and based on analytical or semi-analytical algorithms (Stephonson and Mitalas 1971;Ceylan and Myers 1980;Seem 1987) cannot be applied to the hollow concrete bricks.…”

Section: List Of Symbolsmentioning

confidence: 99%

Transfer function coefficients for time varying coupled heat transfers in vertically heated hollow concrete bricks

2008

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This paper describes a two step numerical procedure to determinate empirical transfer function coefficients (TFCs) for vertically heated hollow concrete bricks. For such systems TFCs cannot be generated using the analytical techniques available in the literature such as the z-transfer function method or the space state representation method because of the nonlinear local character of the heat transfer by natural convection and radiation in the air cells of the hollow concrete bricks. The first step of the procedure consists in predicting coupled heat transfer by conduction, convection, and radiation in realistic time varying conditions using a detailed numerical simulation. In the second step, the results of the simulation (the time-varying heat fluxes at the hollow brick surfaces) are used to obtain empirical transfer function coefficients using an identification technique. Transfer function coefficients are generated for three different types of hollow concrete bricks mostly used in practice. It is shown that the empirical transfer function coefficients permit fast and accurate prediction of heat transfer for thermal excitations that differ markedly from those used to generate these coefficients without solving the complex system of equations governing the coupled heat transfer mechanisms.

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Section: List Of Symbolsmentioning

confidence: 99%

Transfer function coefficients for time varying coupled heat transfers in vertically heated hollow concrete bricks

2008

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“…These studies have individually characterized the influence of the type of internal void in large format bricks (7)(8)(9)(10)(11)(12)(13) and the type of tongue and groove system (14,15) as regards clay-air and clay-mortar cross-sections (see Fig. 7), along with the influence of the horizontal joint on the cross-section of the layer of bonding mortar itself (16).…”

Section: Introductionmentioning

confidence: 99%

“…The research reported here studies the possibility of improving the equivalent thermal transmittance of building façades by using bricks available on the market with thicknesses of 0.290 m, 0.240 m and 0.190 m, and optimized internal geometry with rhomboidal internal voids (7,8,9,11,12,13) on different types of façade. The focus is on single-leaf façades, ventilated façades, façades with an outside thermal insulation system, and façades with a thermo-acoustic insulation system with cladding made of large format bricks 0.070 m thick.…”

Section: Introductionmentioning

confidence: 99%

Influence of the type of lightweight clay brick on the equivalent thermal transmittance of different types of façades on buildings

Morales¹,

Muñoz²,

Juárez³

et al. 2016

Mater. construcc.

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This paper compares the equivalent thermal transmittances of different façades built using commercial clay bricks with three different thicknesses and façades made using the same method but with ceramic bricks with optimized rhomboidal interior geometry.Equivalent thermal transmittances of 0.300 W/m 2 ·K were recorded for the rhomboidal brick with a thickness of 0.290 m and a façade with thermo-acoustic insulation and a large format brick on the interior, but the final thickness of the façade was 0.445 m. RESUMEN: Influencia del tipo de bloque de arcilla aligerada en la transmitancia térmica equivalente de diferentes tipos de fachadas en edificios.En el presente trabajo se comparan las transmitancias térmicas equivalentes de diferentes fachadas ejecutadas con bloques comerciales de tres espesores 0,290 m, 0,240 m y 0,190 m, con el mismo montaje pero con un bloque cerámico optimizado con geometría interior romboidal.Se ha obtenido una transmitancia térmica equivalente de 0,300 W/m 2 ·K para el ladrillo con geometría romboidal de 0,290 m de espesor y pared con aislamiento termoacústico y gran formato en el interior, con un espesor total de fachada de 0,445 m.Para fachadas ventiladas con el ladrillo romboidal propuesto con espesores de 0,290 y 0,240 m, se obtiene una mejora de un 8%-9%, con valores de 0,312 W/m 2 ·K y 0,339 W/m 2 ·K, respectivamente. Podemos concluir que, dada la pequeña diferencia en términos térmicos, la mejor opción es el uso de ladrillos de 0,240 m de espesor, siempre y cuando el espesor total de fachada no exceda los 0,300 m.

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“…The thermal insulation provided by these products is a result of the geometry of the brick and of the small pores present in the clay. Some studies evaluate the possibility of increasing the thermal resistance of the block through a change in the configuration of the enclosures [4][5][6][7][8][9] or by filling the enclosures with insulation material, such as perlite, mineral wood, polystyrene and other substances with low thermal conductivity [10].…”

Section: Introductionmentioning

confidence: 99%

Thermal Performance of Hollow Clay Brick with Low Emissivity Treatment in Surface Enclosures

Fioretti

Principi

2014

Coatings

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External walls made with hollow clay brick or block are widely used for their thermal, acoustic and structural properties. However, the performance of the bricks frequently does not conform with the minimum legal requirements or the values required for high efficiency buildings, and for this reason, they need to be integrated with layers of thermal insulation. In this paper, the thermal behavior of hollow clay block with low emissivity treatment on the internal cavity surfaces has been investigated. The purpose of this application is to obtain a reduction in the thermal conductivity of the block by lowering the radiative heat exchange in the enclosures. The aims of this paper are to indicate a methodology for evaluating the thermal performance of the brick and to provide information about the benefits that should be obtained. Theoretical evaluations are carried out on several bricks (12 geometries simulated with two different thermal conductivities of the clay), using a finite elements model. The heat exchange procedure is implemented in accordance with the standard, so as to obtain standardized values of the thermal characteristics of the block. Several values of emissivity are hypothesized, related to different kinds of coating. Finally, the values of the thermal transmittance of walls built with the evaluated blocks have been calculated and compared. The results show how coating the internal surface of the cavity provides a reduction in the thermal conductivity of the block, of between 26% and 45%, for a surface emissivity of 0.1. OPEN ACCESSCoatings 2014, 4 716

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Nonlinear thermal optimization of external light concrete multi-holed brick walls by the finite element method

Cited by 66 publications

References 4 publications

Transfer function coefficients for time varying coupled heat transfers in vertically heated hollow concrete bricks

Transfer function coefficients for time varying coupled heat transfers in vertically heated hollow concrete bricks

Influence of the type of lightweight clay brick on the equivalent thermal transmittance of different types of façades on buildings

Thermal Performance of Hollow Clay Brick with Low Emissivity Treatment in Surface Enclosures

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