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Larsson, Ulf
Publications (10 of 14) Show all publications
Cehlin, M., Karimipanah, T., Larsson, U. & Ameen, A. (2019). Comparing thermal comfort and air quality performance of two active chilled beam systems in an open-plan office. Journal of Building Engineering, 22, 56-65
Open this publication in new window or tab >>Comparing thermal comfort and air quality performance of two active chilled beam systems in an open-plan office
2019 (English)In: Journal of Building Engineering, E-ISSN 2352-7102, Vol. 22, p. 56-65Article in journal (Refereed) Published
Abstract [en]

The traditional air distribution and supply devices in ventilated rooms are not always able to effectively remove excess heat from the space. Therefore, chilled beams, especially the active systems, are used to achieve the desired cooling demand. The focus of this paper was the potential benefit of a newly designed active chilled beam (ACB) system, to improve heat removal effectiveness local thermal condition and indoor air quality in the occupants’ breathing zone. The system based on 1-way flow design (1W-ACB) was installed in an open-plan office and its performance was studied by analysing the temperatures, velocities and tracer gas concentrations in predetermined risky zones. The system was compared against a traditional 4-way flow design (4W-ACB).

The obtained results showed that heat removal effectiveness was slightly higher for the 1W-ACB system compared to the 4W-ACB system. The local thermal condition was very good close to the workstations when using 1W-ACB. The benefits of the new system were also shown in the occupied zone by analysing the mean age of air and air-change effectiveness (ACE) in the breathing level at the workstation locations. The 1W-ACB system provided air with lower mean age (fresher air), and therefore higher ACE, near the breathing zone at the workstations compared to the 4W-ACB. On the other hand, the 4W-ACB system had the advantage of providing high thermal and mean age of air uniformity throughout the room.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Active Chilled Beam, Air Change Effectiveness, Heat Removal Effectiveness
National Category
Energy Engineering
Identifiers
urn:nbn:se:hig:diva-28583 (URN)10.1016/j.jobe.2018.11.013 (DOI)2-s2.0-85057839765 (Scopus ID)
Available from: 2018-11-22 Created: 2018-11-22 Last updated: 2019-01-07Bibliographically approved
Ameen, A., Cehlin, M., Larsson, U. & Karimipanah, T. (2019). Experimental investigation of ventilation performance of different air distribution systems in an office environment – cooling mode. Energies, 12(7), Article ID 1354.
Open this publication in new window or tab >>Experimental investigation of ventilation performance of different air distribution systems in an office environment – cooling mode
2019 (English)In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, no 7, article id 1354Article in journal (Refereed) Published
Abstract [en]

The performance of a newly designed corner impinging jet air distribution method with an equilateral triangle cross section was evaluated experimentally and compared to that of two more traditional methods (mixing and displacement ventilation). At nine evenly chosen positions with four standard vertical points, air velocity, turbulence intensity, temperature, and tracer gas decay measurements were conducted for all systems. The results show that the new method behaves as a displacement ventilation system, with high air change effectiveness and stratified flow pattern and temperature field. Both local air change effectiveness and air exchange effectiveness of the corner impinging jet showed high quality and promising results, which is a good indicator of ventilation effectiveness. The results also indicate that there is a possibility to slightly lower the airflow rates for the new air distribution system, while still meeting the requirements for thermal comfort and indoor air quality, thereby reducing fan energy usage. The draught rate was also lower for corner impinging jet compared to the other tested air distribution methods. The findings of this research show that the corner impinging jet method can be used for office ventilation.

Keywords
Corner impinging jet, mixing ventilation, displacement ventilation, tracer gas, air exchange effectiveness, air change effectiveness, draught rate
National Category
Energy Engineering
Identifiers
urn:nbn:se:hig:diva-29443 (URN)10.3390/en12071354 (DOI)
Available from: 2019-04-05 Created: 2019-04-05 Last updated: 2019-04-09
Larsson, U. & Moshfegh, B. (2018). Comparison of the thermal comfort and ventilation effectiveness in an office room with three different ventilation supply devices: a measurement study. In: Proceedings of14th International Conference of Roomvent & Ventilation: . Paper presented at Roomvent & Ventilation 2018, Aalto University, Espoo, Finland, June 2-5 2018 (pp. 187-192). Aalto University
Open this publication in new window or tab >>Comparison of the thermal comfort and ventilation effectiveness in an office room with three different ventilation supply devices: a measurement study
2018 (English)In: Proceedings of14th International Conference of Roomvent & Ventilation, Aalto University , 2018, p. 187-192Conference paper, Published paper (Refereed)
Abstract [en]

People spend a significant part of their time in an indoor environment, whether at home, school or workplace. The aim of this paper is to experimentally study the ventilation effectiveness (mean age of air, MAA) and thermal comfort (PMV and PPD) of three different ventilation supply devices, i.e., mixing supply device (MSD), displacement supply device (DSD) and wall confluent jet supply device (WCJSD) in an office room.

This paper is based on analysis from full-scale measurements performed in a laboratory at University of Gävle. The size of the room corresponds to a typical office module for one person. The test room has dimensions of 4.2 x 3.0 x 2.4 m with a volume of 31.24 m3, with the size of the room corresponding to a typical office. Different heat sources are used to simulate the office environment, which corresponds to 31.75 W/m2.

The PMV and PPD are comparable to MSD, WCJSD and DSD as it turns out that MSD has poorer comfort than DSD and WCJSD. DSD and WCJSD have more or less the same thermal comfort performance. When comparing the local mean age of air (MAA) for the studied supply devices, the air is significantly much younger for the DSD and WCJSD than for MSD.  

Place, publisher, year, edition, pages
Aalto University, 2018
Keywords
Mixing ventilation, Displacement ventilation, Wall confluent jet ventilation, Thermal comfort, Ventilation effectiveness
National Category
Energy Systems
Identifiers
urn:nbn:se:hig:diva-27913 (URN)9789525236484 (ISBN)
Conference
Roomvent & Ventilation 2018, Aalto University, Espoo, Finland, June 2-5 2018
Available from: 2018-07-26 Created: 2018-09-17 Last updated: 2018-09-17Bibliographically approved
Cehlin, M., Larsson, U. & Chen, H. (2018). Numerical investigation of Air Change Effectiveness in an Office Room with Impinging Jet Ventilation. In: K. Inthavong*, C.P Cheung, G. Yeoh, J.Y. Tu (Ed.), Proceedings of the 4th international Conference on Building Energy & Environment: . Paper presented at COBEE2018, 4th international Conference on Building Energy & Environment,5-9 February 2018, Melbourne, Australia (pp. 641-646). Melbourne: Conference On Building Energy & Environment - COBEE2018, Melbourne Australia
Open this publication in new window or tab >>Numerical investigation of Air Change Effectiveness in an Office Room with Impinging Jet Ventilation
2018 (English)In: Proceedings of the 4th international Conference on Building Energy & Environment / [ed] K. Inthavong*, C.P Cheung, G. Yeoh, J.Y. Tu, Melbourne: Conference On Building Energy & Environment - COBEE2018, Melbourne Australia , 2018, p. 641-646Conference paper, Published paper (Refereed)
Abstract [en]

Providing occupant comfort and health with minimum use of energy is the ultimate purpose of heating, ventilating and air conditioning systems. This paper presents the air-change effectiveness (ACE) within a typical office room using impinging jet ventilation (IJV ) in combination with chilled ceiling (CC) under different heat loads ranging from 6.5 - 51 W per square meter floor area. In this study, a validated CFD model based on the v2f turbulence model is used for the prediction of air flow pattern and ACE. The interaction effect of chilled ceiling and heat sources results in a complex flow with air circulation. The thermal plumes and air circulation in the room result in a variation of ACE within the room but also close to the occupant. For all studied cases, ACE is above 1.2 close to the occupants, indicating that IJV is more energy efficient than mixing ventilation.

Place, publisher, year, edition, pages
Melbourne: Conference On Building Energy & Environment - COBEE2018, Melbourne Australia, 2018
Keywords
Impinging jet ventilation
National Category
Energy Engineering
Identifiers
urn:nbn:se:hig:diva-26567 (URN)978-0-646-98213-7 (ISBN)
Conference
COBEE2018, 4th international Conference on Building Energy & Environment,5-9 February 2018, Melbourne, Australia
Available from: 2018-05-15 Created: 2018-05-15 Last updated: 2018-09-17Bibliographically approved
Larsson, U. (2018). On the performance of stratified ventilation. (Doctoral dissertation). Linköping: Linköping University Electronic Press
Open this publication in new window or tab >>On the performance of stratified ventilation
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

People nowadays spend most of their time indoors, for example in their homes, cars, in trains, at work, etc. In Sweden, the energy demand in the built environment is a growing issue. The building sector accounts for 40% of total energy use and 15% of total CO2 emissions, and around one-third of the energy use in the world is related to providing a healthy and good comfort indoors. To achieve acceptable indoor climates new designs for the ventilation systems have been proposed in recent decades, among them stratified ventilation systems.

Stratified ventilation is a concept that often allows good performance for both indoor air quality and thermal comfort. Stratified ventilation systems are effective in reducing cross contamination, since there is virtually no mixing in the space; the temperature and the pollutant concentration increase linearly from the heat source with the height of the occupied zone. There are many different ventilation supply devices using the stratified principle, such as displacement supply device (DSD), impinging jet supply device (IJSD) and wall confluent jet supply device (WCJSD).

The main aim of this thesis is to analyze and compare different supply devices based on stratified ventilation, with different setups, related to thermal indoor climate, energy efficiency and ventilation efficiency. The ultimate goal is to contribute to an increased understanding of how ventilation systems with stratified supply devices perform.

Two scientific methods have mainly been used in this thesis, i.e., experimental and numerical investigations. For numerical experiments the CFD (Computational Fluid Dynamics) code ANSYS and FIDAP have been used. Experimental studies have been performed with thermocouples, Hot-Wire Anemometry (HWA) and Hot-Sphere Anemometry, thermal comfort measurement equipment and tracer gas measurement equipment.

This thesis mainly focuses on three research questions: Interaction between a supply device based on stratified ventilation and downdraft from windows; Flow behavior, energy performance and air change effectiveness for different supply devices based on stratified ventilation; and Thermal comfort for different supply devices based on stratified ventilation.

Research question one showed that the arrangement of displacement supply device and window in cold climate has significant effect on the flow pattern below the window. Different supply airflow rates have an effect on both the velocity and the temperature of the downdraft. In this case the velocity decreased by approximately 9.5% and the temperature in the downdraft decreased 0.5°C when the flowrate from the supply device increased from 10 to 15 l/s.

Research question two showed that airflow patterns between different air supply systems were essentially related to characteristics of air supply devices, such as the type, configuration and position, as well as air supply velocities and momentum. For WCJSD, IJSD and DSD, positions of heat sources (such as occupant, computers, lights and external heat sources) played an important role in formation of the room airflow pattern. One interesting observation is that the temperature in the occupied zone is lower and a more stratified temperature field implies a more efficient heat removal by a stratified air supply device. The results revealed that the lowest temperature in the occupied zone was achieved for DSD, but with IJSD and WCJSD slightly warmer, while the system with a mixing supply device (MSD) showed a much higher temperature. The results confirm that air change effectiveness (ACE) for the DSD, WCJSD and IJSD is close to each other. However, MSD shows lower ACE in all the present papers than IJSD, WCJSD and DSD.

Research question three showed that ventilation systems with stratified supply devices in almost all of the studied cases showed an acceptable level for predicted percentage dissatisfied (PPD), predicted mean vote (PMV) and percentage dissatisfied due to draft (DR). If comparing ventilation systems, using IJSD, WCJSD or DSD with MSD always showed thermal comfort better or at the same level.

Abstract [sv]

Människor spenderar en stor del av sin tid inomhus, exempelvis i sina bostäder och bilar, på tåg och på arbetet. Sveriges energibehov i den byggda miljön har en växande trend. Byggnadssektorn står för 40 % av det totala energibehovet och för 15 % av CO2 utsläppet och för cirka en tredjedel av energianvändningen i världen för att tillhandahålla en hälsosam och bra inomhusmiljö. För att skapa en bra inomhusmiljö har nya sätt att ventilera inomhusmiljön utvecklats under de senaste årtiondena. De olika principer som används för att ventilera en byggnad kan indelas i: kolvströmning, omblandande strömning och deplacerande strömning. De genererar rumsförhållanden som ger olika fördelning av hastighet, temperatur och föroreningar i det ventilerade utrymmet.

Stratifierad ventilation är ett koncept som ofta ger ett bra utfall av både inomhusluftkvalitet och termisk komfort. Stratifierade system är effektiva för att minska korskontaminering, eftersom det nästan inte finns någon omblandning i rummet, temperaturen och föroreningskoncentration ökar linjärt från värmekällan med höjden i vistelsezonen. Det finns många olika ventilationsdon som använder den stratifierade principen, såsom deplacerande ventilationsdon (DSD), impinging jet-ventilationsdon (IJSD) och väggbaserad confluent jet-ventilationsdon (WCJSD).

Huvudsyftet med denna avhandling är att analysera och jämföra olika tilluftsdon baserat på stratifierad princip i olika rumskonfigurationer med avseende på termiskt inomhusklimat, energieffektivitet och ventilationseffektivitet. Det yttersta målet är att bidra till ökad förståelse för hur ventilationssystem med olika stratifierade tilluftsdon fungerar.

Två vetenskapliga metoder har huvudsakligen använts i denna avhandling: experimentella och numeriska analyser. För numeriska analyser har CFD (Computational Fluid Dynamics) använts. De simuleringsprogram som utnyttjats för detta ändamål är ANSYS och FIDAP. Experimenten har utförts med hjälp av termoelement, varmtråds- och varmsfärsteknik, mätutrustning för termisk komfort och mätutrustning för spårgas.

Denna avhandling fokuserar framför allt på tre forskningsfrågor: interaktion mellan ett tilluftsflöde från ett deplacerande don och kallraset från ett fönster; strömningsbilden, energiprestandan och luftbyteseffektiviteten för olika tilluftsdon baserat på stratifierad ventilation; och termisk komfort för olika tilluftsdon baserade på stratifierad ventilation.

Forskningsfråga ett visade att kombinationen av tilluftsflöde genom ett deplacerande don och fönster i kallt klimat har tydlig effekt på strömningsbilden för kallraset under fönstret. Olika tilluftsflöden har en effekt på både hastigheten och temperaturen i kallraset. I detta fall minskade hastigheten med ca 9,5% och temperaturen i kallraset minskade med 0,5°C när flödeshastigheten från tilluftsdonet ökade från 10 till 15 l/s.

Forskningsfråga två visade att luftflödesmönstren mellan olika luftförsörjningssystem väsentligen var relaterade till egenskaper hos tilluftsdonen, såsom typ, konfiguration och position samt lufttillförselhastigheter och impulskraft. För WCJSD, IJSD och DSD spelade värmekällans placering, d.v.s. människor, datorer, belysning och externa värmekällor, en viktig roll vid utformningen av rummets luftflödesmönster. En intressant observation är att temperaturen i vistelsezonen är lägre och rummet har ett mer stratifierat temperaturfält, vilket innebär en effektivare ventilering av den zonen. Resultaten visade att den lägsta temperaturen i vistelsezonen uppnåddes för DSD medan IJSD och WCJSD visade en något högre temperatur, systemet med ett omblandande don (MSD) visade en påtagligt högre temperatur. Resultaten bekräftar också att luftförändringseffektiviteten (ACE) för DSD, WCJSD och IJSD ligger nära varandra. MSD visar dock i alla ingående artiklar lägre ACE än IJSD, WCJSD och DSD.

Forskningsfråga tre visade att ventilationssystem med stratifierade tilluftsdon i nästan samtliga studerade fallen haren acceptabel nivå för predicted mean vote (PPD), predicted mean vote (PMV) och percentage dissatisfied due to draft (DR). Om man jämförde ventilationssystem IJSD, WCJSD eller DSD med MSD visade det sig alltid att den termiska komforten var bättre eller på samma nivå som för MSD.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2018. p. 87
National Category
Energy Engineering
Identifiers
urn:nbn:se:hig:diva-27909 (URN)10.3384/diss.diva-149815 (DOI)9789176852514 (ISBN)
Public defence
2018-09-14, ACAS, A-huset, Campus Valla, 10:15 (English)
Opponent
Supervisors
Available from: 2018-09-17 Created: 2018-09-17 Last updated: 2018-09-17Bibliographically approved
Larsson, U. & Moshfegh, B. (2017). Comparison of ventilation performance of three different air supply devices: a measurement study. The International Journal of Ventilation, 16(3), 244-254
Open this publication in new window or tab >>Comparison of ventilation performance of three different air supply devices: a measurement study
2017 (English)In: The International Journal of Ventilation, ISSN 1473-3315, E-ISSN 2044-4044, Vol. 16, no 3, p. 244-254Article in journal (Refereed) Published
Abstract [en]

People today spend a significant part of their time in an indoor environment, whether it be home, school, vehicle or workplace. This has put greater demands on indoor environment, in terms of both air quality and thermal comfort. The main objective of building ventilation is to take care of pollutants and lower their concentration, but it is also used to cool or heat indoor air. The aim of this paper was to study the behavior of three different ventilation supply devices, i.e. mixing supply device, displacement supply device and confluent jet supply device, in an office room. Different cases have been studied experimentally with different airflow rates, supply air temperature and supply devices. The results shows that mostly that we can expect, but the results show a very small difference in ventilation efficiency between the different systems and in theory there should be a larger difference. © 2017 Informa UK Limited, trading as Taylor & Francis Group.

Place, publisher, year, edition, pages
Taylor and Francis Ltd., 2017
Keywords
air exchange efficiency, confluent jet ventilation, displacement ventilation, measurement, Mixing ventilation, Air quality, Efficiency, Indoor air pollution, Measurements, Mixing, Ventilation, Air exchange efficiencies, Building ventilations, Jet ventilations, Supply air temperature, Ventilation efficiency, Ventilation performance, Fighter aircraft
National Category
Energy Systems
Identifiers
urn:nbn:se:hig:diva-24325 (URN)10.1080/14733315.2017.1299519 (DOI)000406118900008 ()2-s2.0-85016093683 (Scopus ID)
Available from: 2017-06-16 Created: 2017-06-16 Last updated: 2018-09-17Bibliographically 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: 2018-12-03Bibliographically approved
Larsson, U. & Moshfegh, B. (2015). Comparison of ventilation performance of three different air supply devices - A measurement study. In: Li Z., Li X., Zhang X., and Taipale A. (Ed.), Ventilation 2015: Proceedings of the 11th International Conference on Industrial Ventilation. Paper presented at 11th International Conference on Industrial Ventilation, Ventilation 2015, 26-28 October 2015, Shanghai, China (pp. 359-366). International Conference on Industrial Ventilation, 1
Open this publication in new window or tab >>Comparison of ventilation performance of three different air supply devices - A measurement study
2015 (English)In: Ventilation 2015: Proceedings of the 11th International Conference on Industrial Ventilation / [ed] Li Z., Li X., Zhang X., and Taipale A., International Conference on Industrial Ventilation , 2015, Vol. 1, p. 359-366Conference paper, Published paper (Refereed)
Abstract [en]

People today spend a significant part of their time in an indoor environment, whether it be home, school, vehicle or workplace. This has put greater demands on indoor air, in terms of both air quality and thermal comfort. The main objective of building ventilation is to take care of pollutants and lower their concentration, but it is also used to cool or heat indoor air. However, exchanging air in a room creates indoor air movements, which can have a major influence on the perception of thermal comfort inside the building. The use of ventilation systems also affects energy use and CO2 discharge to the environment. Therefore it is important to optimize the ventilation system with respect to both indoor climate and energy demand. The aim of this paper was to study the behavior of three different ventilation supply systems, i.e., mixing supply device, displacement supply device and confluent jet supply device, in an office room. The measurements for the present paper were carried out in a special test room at the University of Gᅵᅵvle, Sweden. The room is well insulated and specially designed for full-scale experiments. The size of the room corresponds to a normal office, to produce a heat-load corresponding to an occupied office room with a computer and a person-simulator placed in the middle of the room. The lighting system was working inside the office room during all the experiments. Twelve different cases have been studied experimentally with different airflow rates, supply air temperature and supply devices. The results show that the confluent jets ventilation with the device placed at 2.2 m provides the highest value of ventilation efficiency, followed by displacement ventilation, while the lowest ventilation efficiency is found in the mixing ventilation system. The temperature gradient looks like what one can expect for both mixing and displacement, and confluent jet is a combination of these two. The results also show that the confluent jets ventilation system provides lower air temperature in the occupied zone compared to both displacement and mixing ventilation.

Place, publisher, year, edition, pages
International Conference on Industrial Ventilation, 2015
Keywords
Air; Air quality; Atmospheric temperature; Buoyancy; Carbon dioxide; Energy utilization; Fighter aircraft; Indoor air pollution; Measurements; Mixing; Thermal comfort, Air exchange efficiencies; Building ventilations; Displacement ventilation; Jet ventilations; Mixing ventilation; Supply air temperature; Ventilation efficiency; Ventilation performance, Ventilation
National Category
Energy Systems
Identifiers
urn:nbn:se:hig:diva-22741 (URN)2-s2.0-84987970991 (Scopus ID)978-000-000-000-2 (ISBN)
Conference
11th International Conference on Industrial Ventilation, Ventilation 2015, 26-28 October 2015, Shanghai, China
Available from: 2016-11-11 Created: 2016-11-11 Last updated: 2018-03-13Bibliographically approved
Chen, H., Janbakhsh, S., Larsson, U. & Moshfegh, B. (2015). Numerical investigation of ventilation performance of different air supply devices in an office environment. Building and Environment, 90, 37-50
Open this publication in new window or tab >>Numerical investigation of ventilation performance of different air supply devices in an office environment
2015 (English)In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 90, p. 37-50Article in journal (Refereed) Published
Abstract [en]

The aim of this study was to compare ventilation performance of four different air supply devices in an office environment with respect to thermal comfort, ventilation efficiency and energy-saving potential, by performing numerical simulations. The devices have the acronyms: Mixing supply device (MSD), Wall confluent jets supply device (WCJSD), Impinging jet supply device (IJSD) and Displacement supply device (DSD). Comparisons were made under identical set-up conditions, as well as at the same occupied zone temperature of about 24.2°C achieved by adding different heat loads and using different air-flow rates. Energy-saving potential was addressed based on the air-flow rate and the related fan power required for obtaining a similar occupied zone temperature for each device. Results showed that the WCJSD and IJSD could provide an acceptable thermal environment while removing excess heat more efficiently than the MSD, as it combined the positive effects of both mixing and stratification principles. This benefit also meant that this devices required less fan power than the MSD for obtaining equivalent occupant zone temperature. The DSD showed a superior performance on heat removal, air exchange efficiency and energy saving to all other devices, but it had difficulties in providing acceptable vertical temperature gradient between the ankle and neck levels for a standing person. 

Keywords
Air supply devices, Energy-saving potential, Thermal comfort, Ventilation performance, Air, Energy efficiency, Flow rate, Mixing, Ventilation, Air exchange efficiencies, Air supply, Energy saving potential, Numerical investigations, Thermal environment, Ventilation efficiency, Vertical temperature gradients, Energy conservation, building, computer simulation, indoor air, numerical method, performance assessment
National Category
Mechanical Engineering Building Technologies
Identifiers
urn:nbn:se:hig:diva-19292 (URN)10.1016/j.buildenv.2015.03.021 (DOI)000356189000004 ()2-s2.0-84926464708 (Scopus ID)
Funder
Swedish Research Council Formas, 242-2008-835Knowledge Foundation, 2007/0289
Available from: 2015-05-05 Created: 2015-05-05 Last updated: 2018-09-17Bibliographically approved
Karimipanah, T., Larsson, U. & Cehlin, M. (2014). Investigation of flow pattern for a confluent-jets system on a workbench of an industrial space. In: Indoor Air 2014: 13th International Conference on Indoor Air Quality and Climate. Paper presented at 13th International Conference on Indoor Air Quality and Climate, July 7-12, 2014, Hong Kong (pp. 192-199).
Open this publication in new window or tab >>Investigation of flow pattern for a confluent-jets system on a workbench of an industrial space
2014 (English)In: Indoor Air 2014: 13th International Conference on Indoor Air Quality and Climate, 2014, p. 192-199Conference paper, Published paper (Refereed)
Abstract [en]

A new air supply terminal based on confluent jets was installed on a workbench, in vicinity of a CNC machine, of an industrial space. The flow pattern and temperature field was carried out by CFD calculations and infrared camera imaging technique. A main goal of this technique is to save energy therefore the jet should distribute the air where it is desired. This is possible because the confluent jets system uses the benefits of both mixing (high momentum for better spreading of the air jet) and displacement (cleaner air in occupied zone). The results show that thermal comfort and air quality analysis relies on consistent facts and is in good agreements with the existed standards. It was shown that the supply terminal is able to spread the fresh air to the needed work area. This is an advantage of the high momentum air distribution system used in this investigation.

Keywords
Workbench, Ventilation, Thermal comfort, Confluent Jets, CFD
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:hig:diva-17859 (URN)2-s2.0-84924711434 (Scopus ID)
Conference
13th International Conference on Indoor Air Quality and Climate, July 7-12, 2014, Hong Kong
Available from: 2014-11-09 Created: 2014-11-09 Last updated: 2018-03-13Bibliographically approved
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