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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| Format: | Article |
| Language: | English |
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MDPI AG
2021-11-01
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| Series: | Energies |
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| Online Access: | https://www.mdpi.com/1996-1073/14/22/7772 |
| _version_ | 1797510420123090944 |
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| author | Hamed H. Saber David W. Yarbrough |
| author_facet | Hamed H. Saber David W. Yarbrough |
| author_sort | Hamed H. Saber |
| collection | DOAJ |
| 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. |
| first_indexed | 2024-03-10T05:31:14Z |
| format | Article |
| id | doaj.art-239c12ed476d4f43a22e2624523ea120 |
| institution | Directory Open Access Journal |
| issn | 1996-1073 |
| language | English |
| last_indexed | 2024-03-10T05:31:14Z |
| publishDate | 2021-11-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Energies |
| spelling | doaj.art-239c12ed476d4f43a22e2624523ea1202023-11-22T23:13:11ZengMDPI AGEnergies1996-10732021-11-011422777210.3390/en14227772Advanced Modeling of Enclosed Airspaces to Determine Thermal Resistance for Building ApplicationsHamed H. Saber0David W. Yarbrough1Prince Saud bin Thuniyan Research Center, Mechanical Engineering Department, Jubail University College, Royal Commission of Jubail and Yanbu, Jubail Industrial City 35716, Saudi ArabiaR&D Services, Inc., Watertown, TN 37184, USAEnclosed 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.https://www.mdpi.com/1996-1073/14/22/7772reflective insulationsaspect ratioenclosed airspacelow-emittance materialsradiation and convection heat transferR value |
| spellingShingle | Hamed H. Saber David W. Yarbrough Advanced Modeling of Enclosed Airspaces to Determine Thermal Resistance for Building Applications Energies reflective insulations aspect ratio enclosed airspace low-emittance materials radiation and convection heat transfer R value |
| title | 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_short | 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 |
| topic | reflective insulations aspect ratio enclosed airspace low-emittance materials radiation and convection heat transfer R value |
| url | https://www.mdpi.com/1996-1073/14/22/7772 |
| work_keys_str_mv | AT hamedhsaber advancedmodelingofenclosedairspacestodeterminethermalresistanceforbuildingapplications AT davidwyarbrough advancedmodelingofenclosedairspacestodeterminethermalresistanceforbuildingapplications |