hig.sePublications
Change search
Link to record
Permanent link

Direct link
BETA
Linden, Elisabet
Publications (10 of 22) Show all publications
Kabanshi, A., Sattari, A., Linden, E., Wigö, H. & Sandberg, M. (2017). Experimental study on contaminant entrainment in air distribution systems with free jets. In: Healthy Buildings Europe 2017: . Paper presented at HB2017-Europe, Healthy Buildings Europe 2017, 2-5 July 2017, Lublin, Poland. ISIAQ, Article ID 0040.
Open this publication in new window or tab >>Experimental study on contaminant entrainment in air distribution systems with free jets
Show others...
2017 (English)In: Healthy Buildings Europe 2017, ISIAQ , 2017, article id 0040Conference paper, Published paper (Refereed)
Abstract [en]

This is a preliminary study to an ongoing experimental and theoretical study of ambient entrainment of room air into axisymmetric free jets. The study herein aims to understanding characteristic behaviour of free jets, especially in low mixing ventilation technologies in order to get the best of such applications. In this paper, we explore the interaction of a free jet and its ambient, the effect on jet development, characteristics and behaviour at different Reynold numbers. Measurements were done with Particle Image Velocimetry (PIV) under isothermal conditions. As shown, at lower Reynolds numbers the jet is mostly laminar but is unstable consequently shortening the penetration distance into the ambient. As the Reynolds numbers increase the instability reduces and the penetration distance increases, but entrainment increases as vortices are generated closer to the nozzle exit. The current study suggests that’s further investigation is needed to define limits within which low and high mixing can be achieved with free jets, as this will have practical implications on optimization and implementation of free jets.

Place, publisher, year, edition, pages
ISIAQ, 2017
Keywords
Ambient entrainment, Jet development, PIV, Reynolds numbers
National Category
Energy Systems
Identifiers
urn:nbn:se:hig:diva-24672 (URN)2-s2.0-85053896607 (Scopus ID)978-83-7947-232-1 (ISBN)
Conference
HB2017-Europe, Healthy Buildings Europe 2017, 2-5 July 2017, Lublin, Poland
Note

Digital conference proceedings distributed to participants on USB.

Available from: 2017-07-04 Created: 2017-07-04 Last updated: 2018-10-15Bibliographically approved
Mattsson, M. & Linden, E. (2016). Test av luftrenare i Visby domkyrka.
Open this publication in new window or tab >>Test av luftrenare i Visby domkyrka
2016 (Swedish)Report (Other academic)
Abstract [sv]

Efter den senaste renoveringen av Visby domkyrka, som bl a innefattade rengöring av innerväggar (våren 2014), noterades en oväntat snabb försmutsning av rengjorda väggytor, orsakad av avsättning av partiklar i inneluften. Med syfte att minska försmutsningstakten installerades två fristående luftrenare av elektrostatisk modell i kyrkan i oktober 2015. Föreliggande studie har haft som främsta syfta att utvärdera dessa luftrenares effektivitet i att rena inneluften på luftburna partiklar, framför allt från levande ljus. Utvärderingen har gjorts genom att mäta hur partikelhalten i kyrksalen förändrades vid olika driftfall på luftrenarna. Två olika flödesinställningar på luftrenarna provades: maxflöde resp. lågflöde, där maxflödet provades med både horisontellt och vertikalt riktat utblås av den renade luften. Anledningen till att även ett lägre luftreningsflöde provades var att luftrenarna bullrade så mycket vid maxflöde att detta driftförhållande endast torde bli aktuellt utanför besökstid. Studien har även inkluderat luftomsättningsmätning med spårgasteknik, luft- och yttemperaturmätningar, samt kallrasmätning vid vägg. Även ett vädringstest via portöppning har ingått. 

Resultaten tyder på att luftrenarna har en klart renande effekt avseende luftburna partiklar i kyrksalen. Den minskning i antalet partiklar som luftrenarna åstadkom (partikelrenings-effektiviteten) varierade emellertid med partikelstorleken. I lågflödesfallet erhölls en reduktion av de minsta partiklarna (ultrafina, 0,02-0,3 µm) med ca 31 %, medan den för större partiklar (0,3-10 µm) var av storleksordningen 65‑75 %. I maxflödesfallet blev motsvarande siffror ca 58 % för de minsta partiklarna och 80‑90 % för de större. I välbesökta kyrkor där levande ljus ofta tänds – som i Visby domkyrka – utgör emissionerna från ljusen förmodligen den största partikelkällan. För dessa tycks de minsta partiklarna dominera avseende partikelyta (som kan tänkas täcka/försmutsa invändiga ytor), varför den sammantagna partikelreningseffektiviteten avseende försmutsning hamnar närmare den för de minsta partiklarna. Det är dock troligt att partikelreningseffektivitet blir något högre sommartid, då de riktigt stora besökarskarorna kommer i fallet Visby domkyrka.

Riktningen på utblåset på luftrenarna hade ingen nämnvärd inverkan på partikelrenings-effektiviteten. Dock indikerade mätningarna av kallras (nedfallande luft) längs yttervägg i kyrkan att detta blir något större vid uppåtriktat utblås på luftrenarna, vilket riskerar att öka partikelavsättningstakten vid ytan. Detta fenomen behöver dock studeras närmare. Testet med vädring genom portöppning indikerade att ett avsevärt luftutbyte erhölls med denna metod, och att tillfällig vädring därför kan vara en lämplig åtgärd (även som komplement till luftrenare) vid tillfällen med många besökare och/eller mycket ljusbränning. Både partikel- och spårgasmätningarna påvisade god luftomblandning i kyrksalen, vilket är positivt för spridningen av den renade luften, och detta bidrar till att placeringen av luftrenarna är mindre kritisk. Sommartid kan dock luftomblandningen bli sämre; detta kan behöva undersökas närmare. Förutom minskad försmutsning kan luftrenarna förväntas bidra till en hälsosammare innemiljö ett minskat städbehov i kyrkan.

Publisher
p. 30
Keywords
Luftrenare, Kyrkor, Försmutsning, Luftomsättning, Temperaturfördelning
National Category
Civil Engineering
Identifiers
urn:nbn:se:hig:diva-21343 (URN)
Projects
Church project
Note

Forskningsstudie gjord på uppdrag av Visby domkyrkoförsamling, Samfälligheten Gotlands kyrkor, Gustaf Vasa församling och Visby stift.

Available from: 2016-03-22 Created: 2016-03-22 Last updated: 2018-12-03Bibliographically approved
Arghand, T., Karimipanah, T., Awbi, H., Cehlin, M., Larsson, U. & Linden, E. (2015). An experimental investigation of the flow and comfort parameters for under-floor, confluent jets and mixing ventilation systems in an open-plan office. Building and Environment, 92, 48-60
Open this publication in new window or tab >>An experimental investigation of the flow and comfort parameters for under-floor, confluent jets and mixing ventilation systems in an open-plan office
Show others...
2015 (English)In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 92, p. 48-60Article in journal (Refereed) Published
Abstract [en]

There is a new trend to convert the workplaces from individual office rooms to open offices for motivating money saving and better communication. With such a shift the ability of existing ventilation systems in meeting the new requirements is a challenging question for researchers. The available options could have an impact on workers' health in terms of providing acceptable levels of thermalcomfort and indoor air quality. Thus, this experimental investigation focuses on the performances of three different air distribution systems in an open-plan office space. The investigated systems were: mixing ventilation with ceiling-mounted inlets, confluent jets ventilation and underfloor air distribution with straight and curved vanes. Although this represents a small part of our more extensiveexperimental investigation, the results show that all the purposed stratified ventilation systems (CJV and UFAD) were more or less behaving as mixing systems with some tendency for displacement effects. Nevertheless, it is known that the mixing systems have a stable flow pattern but has the disadvantage of mixing contaminated air with the fresh supplied air which may produce lower performance and in worst cases occupants' illness. For the open-plan office we studied here, it will be shown that the new systems are capable of performing better than the conventional mixing systems. As expected, the higher air exchange efficiency in combination with lower local mean age of air for corner-mounted CJV and floor-mounted UFAD grills systems indicates that these systems are suitable for open-plan offices and are to be favored over conventional mixing systems.

Keywords
Open office, Mixing ventilation (MV), Underfloor air distribution (UFAD), Confluent jets ventilation (CJV)
National Category
Building Technologies
Identifiers
urn:nbn:se:hig:diva-19327 (URN)10.1016/j.buildenv.2015.04.019 (DOI)000358807800006 ()2-s2.0-84929492281 (Scopus ID)
Funder
VINNOVA
Available from: 2015-05-16 Created: 2015-05-16 Last updated: 2019-05-22Bibliographically approved
Sandberg, M., Mattsson, M., Wigö, H., Hayati, A., Claesson, L., Linden, E. & Khan, M. (2015). Viewpoints on wind and air infiltration phenomena at buildings illustrated by field and model studies. Building and Environment, 92, 504-517
Open this publication in new window or tab >>Viewpoints on wind and air infiltration phenomena at buildings illustrated by field and model studies
Show others...
2015 (English)In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 92, p. 504-517Article in journal (Refereed) Published
Abstract [en]

Ventilation and infiltration caused by wind are difficult to predict because they are non-local phenomena: driving factors depend on the surrounding terrain and neighbouring buildings and on the building orientation with respect to the wind direction. Wind-driven flow through an opening is complex because wind can flow through the opening or around the building, in contrast to buoyancy driven flow. We explored wind and air infiltration phenomena in terms of pressure distributions on and around buildings, stagnation points, flow along façades, drag forces, and air flow through openings. Field trials were conducted at a 19th-century church, and wind tunnel tests were conducted using a 1:200 scale model of the church and other models with openings.

 

The locations of stagnation points on the church model were determined using particle image velocimetry measurements. Multiple stagnation points occurred. The forces exerted on the church model by winds in various directions were measured using a load cell. The projected areas affected by winds in various directions were calculated using a CAD model of the church. The area-averaged pressure difference across the church was assessed. A fairly large region of influence on the ground, caused by blockage of the wind, was revealed by testing the scale model in the wind tunnel and recording the static pressure on the ground at many points. The findings of this study are summarized as a number of steps that we suggest to be taken to improve analysis and predictions of wind driven flow in buildings.

Place, publisher, year, edition, pages
Elsevier, 2015
Keywords
Infiltration, Wind, Particle Image Velocimetry, Openings, Stagnation points, Drag force
National Category
Building Technologies
Identifiers
urn:nbn:se:hig:diva-19278 (URN)10.1016/j.buildenv.2015.05.001 (DOI)000358807800046 ()2-s2.0-84930645066 (Scopus ID)
Projects
Church project
Funder
Swedish Energy Agency, 34964-1
Available from: 2015-05-04 Created: 2015-05-04 Last updated: 2018-12-03Bibliographically approved
Hayati, A., Mattsson, M., Sandberg, M. & Linden, E. (2013). Evaluation of two air infiltration models on a church. In: Conference proceedings: Cultural heritage preservation – 3rd European Workshop on Cultural Heritage Preservation: . Paper presented at Cultural heritage preservation – 3rd European Workshop on Cultural Heritage Preservation (EWCHP), Bozen, Italy, September 16-17, 2013 (pp. 47-53).
Open this publication in new window or tab >>Evaluation of two air infiltration models on a church
2013 (English)In: Conference proceedings: Cultural heritage preservation – 3rd European Workshop on Cultural Heritage Preservation, 2013, p. 47-53Conference paper, Published paper (Refereed)
Abstract [en]

Air infiltration in ancient churches and other historical and monumental buildings is of great importance considering moisture transfer, energy consumption, thermal comfort and indoor surface soiling. Two of the most established models for simulatingand predicting air infiltration in buildings are the Lawrence BerkeleyLaboratory (LBL) model and the Alberta air Infiltration Model (AIM-2). The applicability of these models in superimposing wind and buoyancy driven infiltration in large single zone buildings such as churches are evaluated in this study by comparing model predictions with field measurements in a 19thcentury stone church. Both tested air infiltration models yielded significant positive correlations between measured and predicted data, and it is concludedthat the AIM-2 model works better than the LBL model for the studied church. Both models tend however to over-predict the air infiltration rate significantly. The over‑predictions were larger in cases with high wind speed and it seems that the models are more fragile in wind dominating conditions. Inclusion of crawl space coefficients in the AIM-2 model improved however the predictions, especially at high wind speeds. It seems that models of the tested kind can be useful in predicting air infiltration in churches and similar buildings, but that some empirically attained model coefficients might need some adjustment to suit this kind of buildings better.

Keywords
Air infiltration, Air leakage, Modeling, Churches.
National Category
Building Technologies
Identifiers
urn:nbn:se:hig:diva-15410 (URN)978-88-88307-26-8 (ISBN)
Conference
Cultural heritage preservation – 3rd European Workshop on Cultural Heritage Preservation (EWCHP), Bozen, Italy, September 16-17, 2013
Projects
Church project
Funder
Swedish Energy Agency, 2011-002440
Available from: 2013-09-24 Created: 2013-09-24 Last updated: 2018-12-03Bibliographically approved
Linden, E. & Sandberg, M. (2011). Control of jets for ventilation by using different combinations of blowing and suction. In: Proceedings Roomvent 2011 Trondheim Norway Juni 2011: . Paper presented at ROOMVENT 2011 Trondheim Norway, June 19-22, 2011. Tapir Academic Press
Open this publication in new window or tab >>Control of jets for ventilation by using different combinations of blowing and suction
2011 (English)In: Proceedings Roomvent 2011 Trondheim Norway Juni 2011, Tapir Academic Press , 2011Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Tapir Academic Press, 2011
Keywords
Ventilation Jets Suction Blowing Colliding jets
National Category
Engineering and Technology
Identifiers
urn:nbn:se:hig:diva-10165 (URN)
Conference
ROOMVENT 2011 Trondheim Norway, June 19-22, 2011
Available from: 2011-09-21 Created: 2011-09-21 Last updated: 2018-12-03Bibliographically approved
Mattsson, M., Broström, T., Linden, E., Lindström, S. & Sandberg, M. (2011). Fan Convectors vs. Bench heaters in Churches – impact on air velocities. In: Tor Broström & Lisa Nilsen (Ed.), EEHB 2011: Conference on Energy Efficiency in Historic Buildings. Paper presented at EEHB 2011 : Conference on Energy Efficiency in Historic Buildings. Visby. Sweden.. Visby: Gotland University Press
Open this publication in new window or tab >>Fan Convectors vs. Bench heaters in Churches – impact on air velocities
Show others...
2011 (English)In: EEHB 2011: Conference on Energy Efficiency in Historic Buildings / [ed] Tor Broström & Lisa Nilsen, Visby: Gotland University Press, 2011Conference paper, Published paper (Refereed)
Abstract [en]

Air movements in churches affect the deposition rate of airborne particles on surfaces, and hence influence soiling of valuable artifacts of different kinds. Sooting from candles and the thermal comfort of people is also affected by indoor air velocities. In an experimental field study, two different heating systems were compared regarding their effect on room air velocities in a church: air-to-air heat pumps with indoor fan convectors vs. a combination of bench heaters and radiators. Hot-sphere and 3-D sonic anemometers were used to record air velocities in the church. Strong buoyant air flows were found both in the supply air flow path of the heat pumps and above the bench heaters, but the air velocities were rather low outside of these air currents. A ~25 cm thick downdraught air flow was found along walls and windows, with a magnitude that was similar at both heating systems and much larger than the outdoor air infiltration rate.

Place, publisher, year, edition, pages
Visby: Gotland University Press, 2011
Keywords
Churches, Air velocities, Heating system, Heat pump, Surface soiling
National Category
Other Civil Engineering
Identifiers
urn:nbn:se:hig:diva-8760 (URN)978-91-86343-11-8 (ISBN)
Conference
EEHB 2011 : Conference on Energy Efficiency in Historic Buildings. Visby. Sweden.
Projects
Church project
Available from: 2011-05-02 Created: 2011-05-02 Last updated: 2018-12-03Bibliographically approved
Mattsson, M., Broström, T., Linden, E., Lindström, S. & Sandberg, M. (2011). Impact of heating system on air velocities in a medieval stone church. In: Roomvent 2011: 12th International conference on air distribution in rooms. Paper presented at Roomvent 2011, 12th International conference on air distribution in rooms. Trondheim. Norway. June 19-22, 2011. Trondheim, Norge: Tapir Akademisk Forlag
Open this publication in new window or tab >>Impact of heating system on air velocities in a medieval stone church
Show others...
2011 (English)In: Roomvent 2011: 12th International conference on air distribution in rooms, Trondheim, Norge: Tapir Akademisk Forlag , 2011Conference paper, Published paper (Refereed)
Abstract [en]

The air flow pattern and magnitude of air velocities in churches and other historic buildings are of interest since they influence the deposition rate of airborne particles on surfaces, and hence affect soiling of valuable artifacts of different kinds. Increased air movements might also cause enhanced sooting from candles and it has an influence on the thermal comfort of people. The type of installed indoor heating units is likely to be important here since these usually induce substantial air movements through natural or forced convection. In an experimental field study, two different heating systems were compared regarding their effect on room air velocities in a medieval stone church: air-to-air heat pumps with indoor fan convectors vs. a combination of bench heaters and radiators. Hot-sphere anemometers were used to record air velocities in the near-zone of the heat pumps and their surroundings, and 3-D sonic anemometers were used to measure downdraught air velocities at the surfaces of a wall and a window. Smoke was used to visualize air flow patterns.

It was found that the heat pumps caused strong buoyant air jets that rose to the ceiling, but that the air velocities were rather low outside of these jets. The bench heaters caused buoyant plumes, which also seemed to attain rather high air velocities and reach the ceiling. As regards downdraught along wall and window, no significant difference between the two heating systems could be seen, although there was a tendency towards slightly higher air velocities at these surfaces when the heat pumps were in use. Since the air flow pattern at the surfaces appeared similar, also the particle deposition mechanisms and soiling rate can be expected to be similar.

Place, publisher, year, edition, pages
Trondheim, Norge: Tapir Akademisk Forlag, 2011
Keywords
Churches, air velocities, heating system, heat pump, surface soiling
National Category
Building Technologies
Identifiers
urn:nbn:se:hig:diva-8879 (URN)978-82-519-2812-0 (ISBN)
Conference
Roomvent 2011, 12th International conference on air distribution in rooms. Trondheim. Norway. June 19-22, 2011
Projects
Church project
Note

Paper No. 236.

Available from: 2011-05-02 Created: 2011-05-02 Last updated: 2018-12-03Bibliographically approved
Mattsson, M., Lindström, S., Linden, E. & Sandberg, M. (2011). Methods to Identify Air Leakages in the Building Envelope of Churches. In: Tor Broström & Lisa Nilsen (Ed.), EEHB 2011: Conference on Energy Efficiency in Historic Buildings. Paper presented at Conference on Energy Efficiency in Historic Buildings. Visby. Sweden, 9-11 February 2011. Visby, Sweden
Open this publication in new window or tab >>Methods to Identify Air Leakages in the Building Envelope of Churches
2011 (English)In: EEHB 2011: Conference on Energy Efficiency in Historic Buildings / [ed] Tor Broström & Lisa Nilsen, Visby, Sweden, 2011Conference paper, Published paper (Refereed)
Abstract [en]

Frequently there is a wish to reduce the natural ventilation rate in churches in order to save energy and/or improve the thermal comfort. It is then often difficult to ascertain exactly which the dominating leaks in the building envelope are, and where tightening measures would be most effective. A number of different methods to identify these leakages are discussed here. It appears that valuable help can be attained by a combination of several measuring techniques, including IR-thermography, tracer gas and pressure measurements. These techniques can also be useful in verifying the effect of tightening measures.

Place, publisher, year, edition, pages
Visby, Sweden: , 2011
Keywords
Churches, Natural ventilation, Air leakage, Air infiltration, Building tightness
National Category
Other Civil Engineering
Identifiers
urn:nbn:se:hig:diva-8759 (URN)978-91-86343-11-8 (ISBN)
Conference
Conference on Energy Efficiency in Historic Buildings. Visby. Sweden, 9-11 February 2011
Projects
Church project
Available from: 2011-05-02 Created: 2011-05-02 Last updated: 2018-12-03Bibliographically approved
Sandberg, M., Neophytou, M., Fokaides, P., Panagiotou, I., Ioannou, I., Petrou, M., . . . Ivanov, A. (2011). Towards optimization of urban planning and architectural parameters for energy use minimization in Mediterranean cities. In: WREC 2011: . Paper presented at The Word Renewable Energy Congress 2011, Linköping 8-13 May 2011.
Open this publication in new window or tab >>Towards optimization of urban planning and architectural parameters for energy use minimization in Mediterranean cities
Show others...
2011 (English)In: WREC 2011, 2011Conference paper, Published paper (Refereed)
Keywords
Urban Heat Island Field measurements CFD modelling Wind tunnel
National Category
Engineering and Technology
Identifiers
urn:nbn:se:hig:diva-10134 (URN)
Conference
The Word Renewable Energy Congress 2011, Linköping 8-13 May 2011
Funder
Swedish Research Council Formas, ? 2008-327
Available from: 2011-09-15 Created: 2011-09-15 Last updated: 2019-10-04Bibliographically approved
Organisations

Search in DiVA

Show all publications