Thermal Analysis of Light Pipes for Insulated Flat Roofs

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dc.contributor.authorŠikula, Ondřejcs
dc.contributor.authorMohelníková, Jitkacs
dc.contributor.authorPlášek, Josefcs
dc.coverage.issue85cs
dc.coverage.volume2014cs
dc.date.issued2014-10-22cs
dc.description.abstractLight pipes transmit daylight into building interiors. Their installation into thermally insulated roofs of low energy buildings can be a problem because of thermal bridges and condensation problems. This article is focused on a CFD simulation thermal analysis that include four variations of light pipes with a segment of a flat roof. Common light pipes with a hollow light guiding tube were compared to special light pipes containing an additional glass unit located inside the tube. The additional glass units increase thermal resistance and reduce condensation risks of the light guiding systems. The light pipes were compared in two different simulation models run in ANSYS Fluent software and the CalA program. Temperature profiles and air flow patterns of the cross sectional profiles of the light pipes served to determine the total heat transmittance and heat losses of the studied light pipes installed in a segment of a thermally insulated flat roof. The paper compares simplified 2D rotational-symmetrical numerical model based on the thermal diffusion equation with the complex 3D CFD numerical simulation. The results confirm that the simplified 2D numerical model is suitable for the thermal evaluation of the light pipes containing an additional glass unit, too. The additional glass unit with the triple glass improves thermal resistance up to 88% in case of light pipe with diameter 600 mm and reduces optical transmittance to 28%.en
dc.description.abstractLight pipes transmit daylight into building interiors. Their installation into thermally insulated roofs of low energy buildings can be a problem because of thermal bridges and condensation problems. This article is focused on a CFD simulation thermal analysis that include four variations of light pipes with a segment of a flat roof. Common light pipes with a hollow light guiding tube were compared to special light pipes containing an additional glass unit located inside the tube. The additional glass units increase thermal resistance and reduce condensation risks of the light guiding systems. The light pipes were compared in two different simulation models run in ANSYS Fluent software and the CalA program. Temperature profiles and air flow patterns of the cross sectional profiles of the light pipes served to determine the total heat transmittance and heat losses of the studied light pipes installed in a segment of a thermally insulated flat roof. The paper compares simplified 2D rotational-symmetrical numerical model based on the thermal diffusion equation with the complex 3D CFD numerical simulation. The results confirm that the simplified 2D numerical model is suitable for the thermal evaluation of the light pipes containing an additional glass unit, too. The additional glass unit with the triple glass improves thermal resistance up to 88% in case of light pipe with diameter 600 mm and reduces optical transmittance to 28%.cs
dc.formattextcs
dc.format.extent436-444cs
dc.format.mimetypeapplication/pdfcs
dc.identifier.citationENERGY AND BUILDINGS. 2014, vol. 2014, issue 85, p. 436-444.en
dc.identifier.doi10.1016/j.enbuild.2014.09.044cs
dc.identifier.issn0378-7788cs
dc.identifier.orcid0000-0002-7661-0732cs
dc.identifier.orcid0000-0002-5853-078Xcs
dc.identifier.orcid0000-0002-0509-1912cs
dc.identifier.other109707cs
dc.identifier.researcheridJ-4390-2012cs
dc.identifier.researcheridB-6585-2018cs
dc.identifier.researcheridF-7548-2013cs
dc.identifier.scopus55053563200cs
dc.identifier.scopus22980983700cs
dc.identifier.scopus55099842900cs
dc.identifier.urihttp://hdl.handle.net/11012/69289
dc.language.isoencs
dc.publisherElsevier B.V.cs
dc.relation.ispartofENERGY AND BUILDINGScs
dc.relation.urihttp://www.sciencedirect.com/science/article/pii/S0378778814007816#cs
dc.rightsCreative Commons Attribution-NonCommercial-NoDerivatives 3.0 Unportedcs
dc.rights.accessopenAccesscs
dc.rights.sherpahttp://www.sherpa.ac.uk/romeo/issn/0378-7788/cs
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/3.0/cs
dc.subjectHeat transferen
dc.subjectCFD simulationen
dc.subjectTubular light guideen
dc.subjectThermal bridgeen
dc.subjectWater vapor condensation.en
dc.subjectHeat transfer
dc.subjectCFD simulation
dc.subjectTubular light guide
dc.subjectThermal bridge
dc.subjectWater vapor condensation.
dc.titleThermal Analysis of Light Pipes for Insulated Flat Roofsen
dc.title.alternativeThermal Analysis of Light Pipes for Insulated Flat Roofscs
dc.type.driverarticleen
dc.type.statusPeer-revieweden
dc.type.versionpublishedVersionen
sync.item.dbidVAV-109707en
sync.item.dbtypeVAVen
sync.item.insts2025.02.03 15:45:00en
sync.item.modts2025.01.17 15:35:07en
thesis.grantorVysoké učení technické v Brně. Fakulta stavební. Ústav pozemního stavitelstvícs
thesis.grantorVysoké učení technické v Brně. Fakulta stavební. Ústav technických zařízení budovcs
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