Advanced Modeling of Enclosed Airspaces to Determine Thermal Resistance for Building Applications

Enclosed airspaces to reduce heat flow have been recognized for well over 100 years. Airspaces with one or more reflective surfaces define reflective insulation (RI) assemblies, a product type used in walls, roofs, windows with multiple panes, curtain walls and skylights. The thermal resistance (R v...

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Autores principales:	Hamed H. Saber, David W. Yarbrough
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	reflective insulations aspect ratio enclosed airspace low-emittance materials radiation and convection heat transfer R value Technology T
Acceso en línea:	https://doaj.org/article/239c12ed476d4f43a22e2624523ea120
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spelling	oai:doaj.org-article:239c12ed476d4f43a22e2624523ea1202021-11-25T17:28:38ZAdvanced Modeling of Enclosed Airspaces to Determine Thermal Resistance for Building Applications10.3390/en142277721996-1073https://doaj.org/article/239c12ed476d4f43a22e2624523ea1202021-11-01T00:00:00Zhttps://www.mdpi.com/1996-1073/14/22/7772https://doaj.org/toc/1996-1073Enclosed airspaces to reduce heat flow have been recognized for well over 100 years. Airspaces with one or more reflective surfaces define reflective insulation (RI) assemblies, a product type used in walls, roofs, windows with multiple panes, curtain walls and skylights. The thermal resistance (R value) of airspaces depends on the emittance of all surfaces, airspace dimensions and orientation, heat flow direction and surfaces temperatures. The modeling of RI now includes CFD coupled with radiation to quantify the total heat transfer. This study compares a validated model for airspace R values with existing methods such as ISO 6946 and hot-box results that provide the R values in the ASHRAE Handbook of Fundamentals. The existing methods do not include an airspace aspect ratio. This study showed that the aspect ratio can impact the R value by a factor of two. The impact of aspect ratio was calculated for double airspaces variation such as that for single airspaces. The present calculations are two-dimensional and also consider all the bounding airspace surfaces, while previous methods are one-dimensional and do not include surface temperature variations or detailed radiative transport.Hamed H. SaberDavid W. YarbroughMDPI AGarticlereflective insulationsaspect ratioenclosed airspacelow-emittance materialsradiation and convection heat transferR valueTechnologyTENEnergies, Vol 14, Iss 7772, p 7772 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	reflective insulations aspect ratio enclosed airspace low-emittance materials radiation and convection heat transfer R value Technology T
spellingShingle	reflective insulations aspect ratio enclosed airspace low-emittance materials radiation and convection heat transfer R value Technology T Hamed H. Saber David W. Yarbrough Advanced Modeling of Enclosed Airspaces to Determine Thermal Resistance for Building Applications
description	Enclosed airspaces to reduce heat flow have been recognized for well over 100 years. Airspaces with one or more reflective surfaces define reflective insulation (RI) assemblies, a product type used in walls, roofs, windows with multiple panes, curtain walls and skylights. The thermal resistance (R value) of airspaces depends on the emittance of all surfaces, airspace dimensions and orientation, heat flow direction and surfaces temperatures. The modeling of RI now includes CFD coupled with radiation to quantify the total heat transfer. This study compares a validated model for airspace R values with existing methods such as ISO 6946 and hot-box results that provide the R values in the ASHRAE Handbook of Fundamentals. The existing methods do not include an airspace aspect ratio. This study showed that the aspect ratio can impact the R value by a factor of two. The impact of aspect ratio was calculated for double airspaces variation such as that for single airspaces. The present calculations are two-dimensional and also consider all the bounding airspace surfaces, while previous methods are one-dimensional and do not include surface temperature variations or detailed radiative transport.
format	article
author	Hamed H. Saber David W. Yarbrough
author_facet	Hamed H. Saber David W. Yarbrough
author_sort	Hamed H. Saber
title	Advanced Modeling of Enclosed Airspaces to Determine Thermal Resistance for Building Applications
title_short	Advanced Modeling of Enclosed Airspaces to Determine Thermal Resistance for Building Applications
title_full	Advanced Modeling of Enclosed Airspaces to Determine Thermal Resistance for Building Applications
title_fullStr	Advanced Modeling of Enclosed Airspaces to Determine Thermal Resistance for Building Applications
title_full_unstemmed	Advanced Modeling of Enclosed Airspaces to Determine Thermal Resistance for Building Applications
title_sort	advanced modeling of enclosed airspaces to determine thermal resistance for building applications
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/239c12ed476d4f43a22e2624523ea120
work_keys_str_mv	AT hamedhsaber advancedmodelingofenclosedairspacestodeterminethermalresistanceforbuildingapplications AT davidwyarbrough advancedmodelingofenclosedairspacestodeterminethermalresistanceforbuildingapplications
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Advanced Modeling of Enclosed Airspaces to Determine Thermal Resistance for Building Applications

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