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Flow patterns and thermal comfort in a room with panel, floor and wall heating
KTH, School of Technology and Health (STH), Fluid and Climate Technology.
KTH, School of Technology and Health (STH), Fluid and Climate Technology.ORCID iD: 0000-0003-1882-3833
2008 (English)In: Energy and Buildings, ISSN 0378-7788, Vol. 40, no 4, 524-536 p.Article in journal (Refereed) Published
Abstract [en]

Thermal comfort aspects in a room vary with different space heating methods. The main focus in this study was how different heating systems and their position affect the indoor climate in an exhaust-ventilated office under Swedish winter conditions. The heat emitters used were a high and a medium-high temperature radiator, a floor heating system and large wall heating surfaces at low temperature. Computational fluid dynamics (CFD) simulations were used to investigate possible cold draught problems, differences in vertical temperature gradients, air speed levels and energy consumption. Two office rooms with different ventilation systems and heating needs were evaluated. Both systems had high air exchange rates and cold infiltration air.

The general conclusions from this study were that low temperature heating systems may improve indoor climate, giving lower air speeds and lower temperature differences in the room than a conventional high temperature radiator system. The disadvantage with low temperature systems is a weakness in counteracting cold down-flow from ventilation supply units. For that reason the location of heat emitters and the design of ventilation systems proved to be of particular importance. Measurements performed in a test chamber were used to validate the results from the CFD simulations.

Place, publisher, year, edition, pages
2008. Vol. 40, no 4, 524-536 p.
Keyword [en]
thermal comfort, energy consumption, exhaust ventilation, CFD simulations
National Category
Building Technologies
Identifiers
URN: urn:nbn:se:kth:diva-8213DOI: 10.1016/j.enbuild.2007.04.011ISI: 000252789000014Scopus ID: 2-s2.0-37349005232OAI: oai:DiVA.org:kth-8213DiVA: diva2:13473
Note
QC 20101118 Uppdaterad från accepted till published (20101118).Available from: 2008-04-09 Created: 2008-04-09 Last updated: 2011-03-29Bibliographically approved
In thesis
1. Low temperature heating in exhaust ventilated rooms: An approach using Computational Fluid Dynamics
Open this publication in new window or tab >>Low temperature heating in exhaust ventilated rooms: An approach using Computational Fluid Dynamics
2008 (English)Licentiate thesis, comprehensive summary (Other scientific)
Place, publisher, year, edition, pages
Stockholm: KTH, 2008. 27 p.
Series
Trita-STH : report, ISSN 1653-3836 ; 2008:4
National Category
Building Technologies
Identifiers
urn:nbn:se:kth:diva-4694 (URN)978-91-7178-948-8 (ISBN)
Presentation
2008-04-28, Sal 5093, Riksäpplet 2, Campus Haninge, 10:00
Opponent
Supervisors
Note
QC 20101118Available from: 2008-04-09 Created: 2008-04-09 Last updated: 2010-11-18Bibliographically approved
2. Potential of Ventilation Radiators: Performance evaluation by numerical, analytical and experimental means
Open this publication in new window or tab >>Potential of Ventilation Radiators: Performance evaluation by numerical, analytical and experimental means
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Energy consumption for heating and ventilation of buildings is still in 2011considered far too high, but there are many ways to save energy and construct lowenergy buildings that have not been fully utilised. This doctoral thesis has focused onone of these - low temperature heating systems. Particular attention has been given tothe ventilation radiator adapted for exhaust-ventilated buildings because of itspotential as a low energy consuming, easily-operated, environmentally-friendlysystem that might also ensure occupant health and well-being.

Investigations were based on Computational Fluid Dynamics (CFD) simulations andanalytical calculations, with laboratory experiments used for validation.

Main conclusions:

  • Low and very low temperature heating systems, such as floor heating, in general createan indoor climate with low air speeds and low temperature differences in the room, whichis beneficial for thermal comfort. A typical disadvantage, however, was found to beweakness in counteracting cold down-flow from ventilation air supply units in exhaustventilatedbuildings.
  • with ventilation radiators, unlike most other low temperature systems, it was found thatthe risk of cold draught could be reduced while still maintaining a high ventilation rateeven in cold northern European winters.
  • ventilation radiators were found to be more thermally efficient than traditional radiators.
  • design of ventilation radiators could be further modified for improved thermal efficiency.
  • at an outdoor temperature of -15 °C the most efficient models were able to give doublethe heat output of traditional radiators. Also, by substituting the most efficient ventilationradiators for traditional radiators operating at 55 °C supply water temperature, it wasfound that supply water temperature could be reduced to 35 °C while heat outputremained the same and comfort criteria were met.
  • lowering the supply water temperature by 20 °C (as described above) could givecombined energy savings for heating and ventilation of 14-30 % in a system utilising aheat pump.
  • supply water temperatures as low as 35 °C could increase potential for utilising lowtemperature heat sources such as sun-, ground-, water- or waste-heat. This would beparticularly relevant to new-built “green” energy-efficient buildings, but severaladvantages may apply to retrofit applications as well.
  • Successful application of ventilation radiators requires understanding of relevant buildingfactors, and the appropriate number, positioning and size of radiators for best effect.Evaluation studies must be made at the level of the building as a whole, not just for theheating-ventilation system.

This work demonstrated that increased use of well-designed ventilation radiatorarrangements can help to meet regulations issued in 2008 by the Swedish Departmentof Housing (Boverket BBR 16) and goals set in the Energy Performance of BuildingsDirective (EPBD) in the same year.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2011. 63 p.
Keyword
Ventilation radiator, thermal comfort, exhaust ventilation, CFD, energy saving, convection fin, low temperature heating
National Category
Building Technologies
Identifiers
urn:nbn:se:kth:diva-31813 (URN)978-91-7415-940-0 (ISBN)
Public defence
2011-04-18, F3 (Flodis), Lindstedtsvägen 26,, 114 28 Stockholm, 16:12 (English)
Opponent
Supervisors
Projects
STEM Projektnummer:30326-1 Energieffektiva lågtemperatursystem i byggnader
Note
QC 20110328Available from: 2011-03-29 Created: 2011-03-25 Last updated: 2011-04-05Bibliographically approved

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