Thermal CFD Analysis of Tubular Light Guides
Tubular light guides are applicable for daylighting of windowless areas in buildings. Despite their many positive indoor climate aspects they can also present some problems with heat losses and condensation. A computer CFD model focused on the evaluation of temperature distribution and air flow insi...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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MDPI AG
2013-12-01
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| Series: | Energies |
| Subjects: | |
| Online Access: | http://www.mdpi.com/1996-1073/6/12/6304 |
| _version_ | 1798005202811355136 |
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| author | Ondřej Šikula Jitka Mohelníková Josef Plášek |
| author_facet | Ondřej Šikula Jitka Mohelníková Josef Plášek |
| author_sort | Ondřej Šikula |
| collection | DOAJ |
| description | Tubular light guides are applicable for daylighting of windowless areas in buildings. Despite their many positive indoor climate aspects they can also present some problems with heat losses and condensation. A computer CFD model focused on the evaluation of temperature distribution and air flow inside tubular light guides of different dimensions was studied. The physical model of the tested light guides of lengths more than 0.60 m proves shows that Rayleigh numbers are adequate for a turbulent air flow. The turbulent model was applied despite the small heat flux differences between the turbulent and laminar model. The CFD simulations resulted into conclusions that the growing ratio of length/diameter increases the heat transmission loss/linear transmittance as much as by 50 percent. Tubular light guides of smaller diameters have lower heat transmission losses compared to the wider ones of the same lengths with the same outdoor temperature being taken into account. The simulation results confirmed the thermal bridge effect of the tubular light guide tube inside the insulated flat roof details. The thermal transmittance of the studied light guides in the whole roof area was substituted with the point thermal bridges. This substitution gives possibility for simple thermal evaluation of the tubular light pipes in roof constructions. |
| first_indexed | 2024-04-11T12:35:22Z |
| format | Article |
| id | doaj.art-45cc1092aac5478099681ed303460cd5 |
| institution | Directory Open Access Journal |
| issn | 1996-1073 |
| language | English |
| last_indexed | 2024-04-11T12:35:22Z |
| publishDate | 2013-12-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Energies |
| spelling | doaj.art-45cc1092aac5478099681ed303460cd52022-12-22T04:23:38ZengMDPI AGEnergies1996-10732013-12-016126304632110.3390/en6126304en6126304Thermal CFD Analysis of Tubular Light GuidesOndřej Šikula0Jitka Mohelníková1Josef Plášek2Faculty of Civil Engineering, Brno University of Technology, Veveří 331/95, Brno 602 00, Czech RepublicFaculty of Civil Engineering, Brno University of Technology, Veveří 331/95, Brno 602 00, Czech RepublicFaculty of Civil Engineering, Brno University of Technology, Veveří 331/95, Brno 602 00, Czech RepublicTubular light guides are applicable for daylighting of windowless areas in buildings. Despite their many positive indoor climate aspects they can also present some problems with heat losses and condensation. A computer CFD model focused on the evaluation of temperature distribution and air flow inside tubular light guides of different dimensions was studied. The physical model of the tested light guides of lengths more than 0.60 m proves shows that Rayleigh numbers are adequate for a turbulent air flow. The turbulent model was applied despite the small heat flux differences between the turbulent and laminar model. The CFD simulations resulted into conclusions that the growing ratio of length/diameter increases the heat transmission loss/linear transmittance as much as by 50 percent. Tubular light guides of smaller diameters have lower heat transmission losses compared to the wider ones of the same lengths with the same outdoor temperature being taken into account. The simulation results confirmed the thermal bridge effect of the tubular light guide tube inside the insulated flat roof details. The thermal transmittance of the studied light guides in the whole roof area was substituted with the point thermal bridges. This substitution gives possibility for simple thermal evaluation of the tubular light pipes in roof constructions.http://www.mdpi.com/1996-1073/6/12/6304computer simulationANSYS FluentCFD modeltubular light guidesthermal bridgestemperature distributionair flowthermal radiationdiscrete transfer radiation model |
| spellingShingle | Ondřej Šikula Jitka Mohelníková Josef Plášek Thermal CFD Analysis of Tubular Light Guides Energies computer simulation ANSYS Fluent CFD model tubular light guides thermal bridges temperature distribution air flow thermal radiation discrete transfer radiation model |
| title | Thermal CFD Analysis of Tubular Light Guides |
| title_full | Thermal CFD Analysis of Tubular Light Guides |
| title_fullStr | Thermal CFD Analysis of Tubular Light Guides |
| title_full_unstemmed | Thermal CFD Analysis of Tubular Light Guides |
| title_short | Thermal CFD Analysis of Tubular Light Guides |
| title_sort | thermal cfd analysis of tubular light guides |
| topic | computer simulation ANSYS Fluent CFD model tubular light guides thermal bridges temperature distribution air flow thermal radiation discrete transfer radiation model |
| url | http://www.mdpi.com/1996-1073/6/12/6304 |
| work_keys_str_mv | AT ondrejsikula thermalcfdanalysisoftubularlightguides AT jitkamohelnikova thermalcfdanalysisoftubularlightguides AT josefplasek thermalcfdanalysisoftubularlightguides |