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Low temperature heating in exhaust ventilated rooms: An approach using Computational Fluid Dynamics
KTH, School of Technology and Health (STH), Fluid and Climate Technology.
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: urn:nbn:se:kth:diva-4694ISBN: 978-91-7178-948-8 (print)OAI: oai:DiVA.org:kth-4694DiVA: diva2:13477
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
List of papers
1. Flow patterns and thermal comfort in a room with panel, floor and wall heating
Open this publication in new window or tab >>Flow patterns and thermal comfort in a room with panel, floor and wall heating
2008 (English)In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, 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.

Keyword
thermal comfort, energy consumption, exhaust ventilation, CFD simulations
National Category
Building Technologies
Identifiers
urn:nbn:se:kth:diva-8213 (URN)10.1016/j.enbuild.2007.04.011 (DOI)000252789000014 ()2-s2.0-37349005232 (Scopus ID)
Note
QC 20101118 Uppdaterad från accepted till published (20101118).Available from: 2008-04-09 Created: 2008-04-09 Last updated: 2017-12-14Bibliographically approved
2. Design considerations with ventilation-radiators: Comparisons to traditional two-panel radiators
Open this publication in new window or tab >>Design considerations with ventilation-radiators: Comparisons to traditional two-panel radiators
2009 (English)In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 41, no 1, 92-100 p.Article in journal (Refereed) Published
Abstract [en]

Performance of heat emitters in a room is affected by their interaction with the ventilation system. A radiator gives more heat output with increased air flow along its heat transferring surface, and with increased thermal difference to surrounding air. Radiator heat output and comfort temperatures in a small one-person office were Studied using different positions for the ventilation air inlet. In two of the four test cases the air inlet was placed between radiator panels to form ventilation-radiator systems. Investigations were made by CFD (Computational Fluid Dynamics) simulations, and included visualisation of thermal comfort conditions, as well as radiator heat output comparisons. The room model was exhaust-ventilated, with an air exchange rate equal to what is recommended for Swedish offices (71 s(-1) per person) and cold infiltration air (-5 degrees C) typical of a winter day in Stockholm. Results showed that under these conditions ventilation-radiators were able to create a more stable thermal climate than the traditional radiator ventilation arrangements. In addition, when using ventilation-radiators the desired thermal climate could be achieved with a radiator surface temperature as Much as 7.8 degrees C lower. It was concluded that in exhaust-ventilated office rooms, ventilation-radiators can provide energy and environmental savings.

Keyword
Ventilation-radiator, Exhaust ventilation, CFD simulation, Thermal, comfort, Energy consumption, Low temperature heating
National Category
Building Technologies
Identifiers
urn:nbn:se:kth:diva-18031 (URN)10.1016/j.enbuild.2008.07.014 (DOI)000261483800011 ()2-s2.0-55649110025 (Scopus ID)
Note

QC 20100525

Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2017-12-12Bibliographically approved
3. Comfort temperatures and operative temperatures in an office with different heating methods
Open this publication in new window or tab >>Comfort temperatures and operative temperatures in an office with different heating methods
2006 (English)In: Proceedings of the Healthy Buildings Conference: Vol. 2: Indoor Climate, 2006, Vol. 2, 47-52 p.Conference paper, Published paper (Other academic)
Keyword
Computational Fluid Dynamics, Low temperature heating, Comfort temperature, Operative temperature, Radiation asymmetry
National Category
Building Technologies
Identifiers
urn:nbn:se:kth:diva-8215 (URN)2-s2.0-84871575806 (Scopus ID)
Note
QC 20101118Available from: 2008-04-09 Created: 2008-04-09 Last updated: 2011-03-29Bibliographically approved
4. Energy savings and thermal comfort with ventilation radiators: a dynamic heating and ventilation system
Open this publication in new window or tab >>Energy savings and thermal comfort with ventilation radiators: a dynamic heating and ventilation system
2007 (English)In: Proceedings of Clima 2007 WellBeing Indoors, 2007Conference paper, Published paper (Other academic)
Abstract [en]

Studies indicate that a high ventilation rate with fresh air supply directly from outdoors gives better thermal comfort conditions, less SBS (Sick Building Syndrome) symptoms and increased work productivity. The drawbacks with a high ventilation rate in natural or exhaust ventilated buildings are normally increased energy use for heating and cold air draught. Such problems may be minimized with ventilation radiators, radiators where cold ventilation air is brought directly from outdoors through a wall channel into the radiator where it is heated before entering the room.

This paper discusses advantages with ventilation radiators in comparison to those of traditional heating systems. Focus has been on energy aspects and thermal comfort. The main conclusions are that ventilation radiators may give a stable and uniform thermal indoor climate. The high thermal gradient between cold ventilation air and the radiator surface inside the ventilation channel also makes the ventilation radiator more efficient than other systems. A method to vary indoor climate on a daily basis according to where people stay is proposed for additional energy savings with ventilation radiators. The deductions were based on results from CFD simulations in a well validated office model.

Keyword
Ventilation radiator, CFD, thermal comfort, energy consumption
National Category
Building Technologies
Identifiers
urn:nbn:se:kth:diva-8216 (URN)
Conference
Clima 2007, 10-14 June, Helsinki, Finland
Note
QC 20101118Available from: 2008-04-09 Created: 2008-04-09 Last updated: 2011-03-29Bibliographically approved

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