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  • 101. Bestill onlineKjøp publikasjonen >>
    Björling, Mikael
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Miljöteknik.
    Kemi för de yngre åren2016Inngår i: Ämnesdidaktiska utmaningar inom matematik, naturvetenskap och teknik / [ed] Mikael Björling, Gävle: Gävle University Press , 2016, 1, s. 109-132Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [sv]

    Detta är bakgrunden till att små barn är fascinerande av att leka Titt-ut,men som alla föräldrar vet så försvinner den lekens lockelse när barnet blir äldre. Barn utvecklas snabbt i de yngre åren, vilket skapar både möjligheter och begränsningar för hur lärande i naturvetenskap och kemi uppstår i förskolan och grundskolan. Det finns många skäl till att kemirelaterade aktiviteter bör introduceras i de yngre åren och i det här kapitlet diskuteras några av dessa skäl ur ett kemididaktiskt perspektiv. Kapitlet är uppbyggt kring några av de betydande framsteg som gjorts i den utvecklingspsykologiska forskningen under de senaste tjugo åren (Gärdenfors, 2006). Idag vet vi ganska mycket om hur våra hjärnor fungerar och utvecklas. Insprängt i denna beskrivning kommer jag att reflektera kring hur detta skulle kunna påverka valet av innehåll när det gäller naturvetenskapligt lärande för yngre barn. På slutet sammanfattar jag tankarna om innehåll med ett speciellt fokus på kemi.

  • 102.
    Björling, Mikael
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Miljöteknik.
    Sustainable science policy - in whom shall we trust?2017Inngår i: A good life for all: Essays on sustainability celebrating 60 years of making life better / [ed] Fagerström, Arne and Cunnigham, Gary M., Mjölby: Atremi AB , 2017, 1, s. 21-43Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    The role of science as a provider of well-tested and trustworthy knowledgre in a sustainable society is discussed with respect to other social institutions: government and state bureaucracy, the market, the media and the public. In particular, societal pressures that threaten scientific endeavour are problematised with a slight bias towards examples from sustainability science. Global challenges of today transcend social institutions and therefore require novel modes of trans-institutional cooperation. Such modes of cooperation may produce unwanted clashes of institutional norms that imperil objective and mutually accepted norms need to be developed. The science policy for a democratic, sustainable society should strive for clear divisions among social institutions while encouraging suitable modes of cooperation to address global challenges to the sustainability of human life.

  • 103. Bestill onlineKjøp publikasjonen >>
    Björling, Mikael
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Miljöteknik.
    Ämnesdidaktiska utmaningar inom matematik, naturvetenskap och teknik2016Collection/Antologi (Annet vitenskapelig)
    Abstract [sv]

    Den här boken samlar ett axplock av ämnesdidaktiska utmaningar inom matematik, naturvetenskap och teknik från lärare och forskare med anknytning till Högskolan i Gävle (HiG). Den röda tråden är en vilja att göra ämnena mer tillgängliga samt stimulera utveckling av undervisning och lärande i dessa ämnen.

    Författarna till den här boken förenas av ett brinnande intresse för sina olika ämnen och en stark önskan att finna vägar till utveckling av undervisningen för att underlätta lärande och väcka nyfikenhet. Boken är skriven till dig som delar våra intressen. Vi hoppas att den ska inspirera till ytterligare utveckling av ämnesdidaktiken.

  • 104. Bestill onlineKjøp publikasjonen >>
    Björling, Mikael
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Miljöteknik.
    Ämnesdidaktiska utmaningar inom matematik, naturvetenskap och teknik2016Inngår i: Ämnesdidaktiska utmaningar– inom matematik, naturvetenskap och teknik / [ed] Mikael Björling, Gävle: Gävle University Press , 2016, 1, s. 9-14Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 105.
    Björling, Mikael
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Miljöteknik.
    Akander, Jan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Steen Englund, Jessika
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    On Measuring Air Infiltration Rates Using Tracer Gases in Buildings with Presence Controlled Mechanical Ventilation Systems2016Inngår i: Indoor Air 2016: The 14th International Conference of Indoor Air Quality and Climate, July 3-8 2016, Ghent, Belgium: Conference Proceedings / [ed] E. Van Kenhove, J. Laverge, P. De Vlieger, ISIAQ , 2016, artikkel-id 875Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The ventilation and air leakage of a school building was investigated. Information was collected from the parameters of the mechanical ventilation system and from measurements of the local mean age of air using the homogeneous emission method. While the average local mean ages of air can be accurately measured by passive integrative samplers, the estimation of the average room specific air change rate by taking the inverse of the measured average local mean age of air did not give correct results. The main problem is that integrative sampling represents a linear averaging process that is inappropriate to capture the average of nonlinearly related properties. This problem is accentuated when the ventilation rates for different periods differ a lot. A simple computational model was developed to discuss the system behavior. A partial solution to the measurement problem is to actively sample the different populations of air change rates separately.

  • 106.
    Björling, Mikael
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Miljöteknik.
    Jönsson, D.
    Building Services LTH, Lund University, Lund, Sweden .
    Bagge, H.
    Building Physics LTH, Lund University, Lund, Sweden.
    Johansson, D.
    Building Services LTH, Lund University, Lund, Sweden .
    Air infiltration into naturally ventilated apartments in multifamily dwellings2014Inngår i: Indoor Air 2014 - 13th International Conference on Indoor Air Quality and Climate, 2014, s. 34-40Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This study presents the ACH for ten apartments in naturally ventilated multifamily dwellings for two cases inlet vent manipulations: i) fully opened inlet vents; and ii) fully closed and taped inlet vents. Even with fully opened inlet vents the resulting ventilation is rather poor. The average ACH is 0.26±0.16 h-1. All apartments fall in the lower quartile in terms of ACH when compared to other multifamily dwellings in Sweden. A method using two different tracers A and B is presented that allow for measurement of the partial flow from the stairway zone and the partial flow from other pathways into the apartment. On the average 10-20% of the airflow into a typical apartment in a naturally ventilated multifamily dwelling seems to originate from the stairway zone when the inlet vents are fully opened. By closing and taping the inlet vents, the airtightness of the apartments have been investigated. The average direct leakage flow, i.e. not from the stairway zone, is 17 m3/h but the variation is large. Layout B seems to leak the most, followed by A and then C.

  • 107.
    Björling, Mikael
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Miljöteknik.
    Kumlin, Anders
    Anders Kumlin AB.
    Carlsson, Peter
    Bengt Dahlgren AB.
    Local Determination of the Building Envelope Air Leakage2018Inngår i: Indoor Air 2018 / [ed] Michael Waring and Brent Stephens, 2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A method to determine the rate of local transport into the indoor air of a substance originating from the construction frame of a building has been devised and tested. In particular we demonstrate that a tracer located outside the air and vapour barrier in the construction frame of an office building can be detected in varying concentrations in the office indoor air. The tracer may either diffuse directly or follow with outside air leaking through the barrier. Cor-recting for the local air change rate yields an apparent emission rate as an estimate of the rate of local transport from the construction frame to the indoor air. Our interpretation is that high-er apparent emission rates predominantly reflect higher local air leakage rates through the air and vapor barrier. This information could be useful for interpreting office worker complaints and for decisions on renovation options. The tracer techniques used in the study are also more generally applicable to convert measured concentrations of indoor substances into apparent emission rates. Emission rates are more indicative of the location of pollution sources and may therefore be useful in other investigations of polluted buildings.

  • 108.
    Björling, Mikael
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Miljöteknik.
    Mattsson, Magnus
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Akander, Jan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Infiltration of Air into two World Heritage Farmhouses in Sweden during Winter Conditions2018Inngår i: Roomvent & Ventilation 2018: Excellent Indoor Climate and High Performing Ventilation / [ed] Risto Kosonen, Mervi Ahola, Jarkko Narvanne, Helsinki, Finland, 2018, s. 1079-1084Konferansepaper (Fagfellevurdert)
    Abstract [en]

    As a part of an ongoing study, we report measurements of air infiltration during winter conditions into two Decorated Farmhouses of Hälsingland designated as UNESCO World Heritage Sites. In winter these two-storied farmhouses are rarely heated, except for special occasions. In this measurement one farmhouse  was  unheated,  whereas  one  room  was  heated  for  a  brief  period  in  the  other  one.  The observed local mean ages of air measured with tracer gas techniques generally increase with height, both  locally  within  each  room  and  between  floors.  The  average  temperature  and  humidity  also increases from the first to the second floor. The indoor temperature follows the outdoor temperature with a time lag. The differences in water content between inside and outside air correlate with changes of the indoor relative humidity. The correlation is stronger for humidity increase than for humidity decrease, possibly due to moisture absorption by interior text.

  • 109.
    Björnsdotter, Matilda
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Design och formgivning.
    Har du mens eller?: Mensskyddsförpackningar och genus2018Independent thesis Basic level (degree of Bachelor), 15 poäng / 22,5 hpOppgave
    Abstract [sv]

    Problemet jag valde att utgå ifrån var att en stor del av de produkter vi använder marknadsförs på ett väldigt stereotypt sätt till män eller kvinnor, vilket resulterar i att de som inte passar in i tvåkönsnormen utesluts. Mitt syfte under projektets gång blev därför att undersöka och i slutändan belysa och kritisera problemet på ett passande sätt.

    Produktkategorin jag senare gick in på närmare var mensskydd, specifikt deras förpackningar. Dessa är genom marknadsföringen endast riktade till kvinnor och agerar därför uteslutande mot dem som inte är ciskvinnor. Dessutom är mens ett laddat och aktuellt ämne inom vissa kretsar som de flesta har någon känsla eller åsikt kring vilket jag hoppades skulle hjälpa projektet att väcka uppmärksamhet.

    Arbetet startade i att samla ihop en bred grund av teori att bygga resterande delar av projektet på. All fakta och information kring normer, stereotyper, genus, förpackningar, transpersoner, mens och mensskydd blev något jag alltid kunde gå tillbaka till för att backa upp mina val under projektets gång. Även kontakten med användarna genom enkäter har skapat en stor förståelse för andras upplevelse av dessa förpackningar samt vad som väcker uppmärksamhet och känslor, vilket har varit värdefullt i arbetet mot att belysa ett problem genom kritisk design.

    Förpackningen är framtagen som en kontrast till dagens mensskyddsförpackningar. Här får mensen ta plats med illustrationer av mensskydd i en blodröd färg och med genomskinliga sidor som visar innehållet. Typsnittet är en blandning av det hårda maskulina och det tunna runda feminina för att skapa en könsneutralt uttryck. Företagsnamnet ”har du mens eller” är valt efter frasen som ofta sägs av män i syfte att trycka ner och nedvärdera kvinnors åsikter och känslor, men i detta fall skrivet i ett typiskt feminint typsnitt som är så vanligt inom den valda produktkategorin. Förhoppningen är att de olika delarna och förpackningen i stort ska väcka uppmärksamhet och eftertanke kring hur produkter omkring oss är marknadsförda och hur det påverkar oss.

  • 110.
    Blom, Linus
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Hedlund, Dan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Tilläggsisolering och fuktproblem i grundkonstruktionen platta på mark: En fallstudie i flerbostadshus inom stadsdelen Sätra i Gävle2014Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [en]

    Between 1965 and 1974, the Swedish Parliament decided to build one million dwellings, called Million Program. The million program buildings were erected with new, untried design solutions, in a short range of time, and at low cost. The residential buildings from that time are now greatly in need of renovation. The municipal housing company, Gavlegårdarna, renovates and improves the energy efficiency at some of it’s apartment buildings in the district Sätra, Gävle. One problem is how to make the basic design of the slab on ground more energy efficiency and moisture proof. The study covers four representative flooring types in the Gavlegårdarnas million program area in Sätra.

    This study aims to investigate and evaluate proven methods for adding insulation in the four floor types. Also to look for solutions by designing additional insulation to treat damp problems and improve energy efficiency in an economical way. Existing flooring types are to be examined to check for new solutions as well. The aim is to produce a number of measures to provide property owners with different energy efficiency solutions.

    Results of calculations show that the perimeter area of the slab is exposed to moisture problems, while the centre of it does not have any notable problems. According to calculations, improved floor types have U-values reduced by 31% – 40% depending on the insulation thickness and design. However, investments have a long payback period and this is sometimes not economically viable. When a redevelopment project is performed, it is beneficial to simultaneously add insulation. If investors promote sustainable development, reduced energy consumption by the proposed measures is viable, as advocated by the environmental goals set by Sweden and the EU. 

  • 111.
    Blomqvist, Sofia
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Sundby, Dennis
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Energianalys av fastighet Brynäs 12:1: Energikartläggning med effektiviseringsåtgärder inriktning mot ventilation2014Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Energianvändningen i Sverige och världen förväntas öka och bostads- och servicesektorn står för 40 % av världens totala energibehov. Det är viktigt att energieffektivisera redan befintliga byggnader och optimera dess system då en lägre energianvändning gynnar både miljön och ekonomin. En byggnads ventilationssystem står för en stor del av en fastighets energianvändning och det finns ofta stor potential för systemet att optimeras och effektiviseras.

    En fastighetsägare vill inte ha fastigheter som står outhyrda. Outhyrda lokaler betyder minskade intäkter i hyror och i vissa fall tillkommer energianvändning för de tomma lokalerna i form av uppvärmning och ventilation som fastighetsägaren måste betala. System som helt kan stängas av eller styras beroende på ventilationsbehov behövs för att den sistnämnda kostnaden ska reduceras helt under tiden lokalen är outhyrd och för att den totala energianvändningen ska minska när en hyresgäst flyttar in.

    Ventilationens syfte är att ventilera bort fukt, värme, partiklar och koldioxid så att ett bra inomhusklimat skapas för de personer som vistas i byggnaden. Den vanligaste ventilationsprincipen för offentliga byggnader är att ventilera luft med ett konstant luftflöde genom ett constant air volume-system. Med behovsanpassad ventilation i form av ett variable air volume-system kan stora besparingar göras då man anpassar luftflödet efter det verkliga ventilationsbehovet istället för att ventilera byggnaden med ett konstant maxflöde. En installation av ett VAV-system i form av CO2- eller närvarostyrning sänker ventilationens energianvändning samtidigt som kvaliteten på inomhusmiljön bibehålls.

    Arbetet som har utförts innefattar en energikartläggning av fastigheten Brynäs 12:1 då en energikartläggning hjälper till att förstå en byggnads energianvändning och identifierar möjliga energisparåtgärder. Energianvändningen för fastighetens delsystem har kartlagts och analyserats för att ta fram förslag på besparingsåtgärder. Resultatet av energikartläggningen visade att det fanns stor besparingspotential för ventilationsaggregat TA1, TA2 och TA3:s el- och värmeanvändning. Om de åtgärder rörande ventilationen som presenteras i arbetet som till exempel flödes- och tidsreducering vidtas kan en energibesparing på 333 MWh/år uppnås, vilket är 28 % av fastighetens totala årliga energianvändning. 

  • 112.
    Bodell, Erik
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Åhlander, Simon
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Energianalys av byggnad med installerat ångsystem för matlagningsprocesser: Kan ånga vara mer effektivt än el för matlagning?2017Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Det finns ett stort behov av att minska energianvändningen i världen. Igenom att minska energibehovet så minskar den negativa miljöpåverkan. I en ständigt växande värld där det byggs i allt snabbare takt så ökar också energibehovet. Igenom att effektivisera befintliga byggnader kan energibehovet stagnera eller till och med minska trots utbyggnaden. Igenom att energieffektivisera så kan mer av den energi som används nyttjas istället för att den ska stå för onödiga förluster.

    Fortifikationsverket har en restaurangbyggnad de anser använder för mycket energi. Denna byggnad innehåller en restaurang som använder ett ångsystem för matproduktion, vilket gör byggnadens energisystem unikt. För att kunna minska byggnadens energianvändning kartläggs och analyseras den i denna rapport. Denna fallstudie genomförs med en litteraturstudie för att utveckla kunskaperna inom området. Sedan utförs mätningar i byggnaden som därefter analyseras och presenteras så att eventuella avvikelser och brister påpekas.

    Under arbetets gång upptäcktes att en säkring var felinstallerad för mätningen av elanvändningen till en av ångpannorna. Igenom att ha åtgärdat detta för att kunna fakturera rätt så spar Fortifikationsverket nästan 170 000 kr per år som den ångpannan går. Utöver detta så analyserades ångsystemet och uppskattningar gjordes för att kunna svara på om ånga är effektivare än el för matlagning. Det visar sig att ångsystemet kan vara effektivt om stor mängd mat tillagas. Med hänsyn till nätter, helger och de dagar då mindre mat tillagas så är el-utrustning effektivare eftersom att det helt stängs av när det inte används. Till skillnad från ångsystemet som måste täcka upp för förlusterna för att behålla temperatur och tryck, även när systemet inte används. Igenom att byta ut ångsystemet till motsvarande utrustning som drivs av el skulle det gå att spara 205 MWh/år, enligt uppskattningar. Ångsystemet står för 35% av byggnadens totala elanvändning och är den största posten för energianvändningen och är därför den del som fokuserats mest på.

    Utöver ångsystemet så analyserades övrig energianvändning för att kunna ge förslag på besparingar. Många av förslagen är grundade på vissa uppskattningar och antaganden vilket måste beaktas. Några konkreta exempel på besparingar som kan göras är att sänka inomhustemperaturen för att spara 50 MWh/år, installera tilläggsfönster för att spara upp till 140 MWh/år, installera effektivare kylaggregat – 200 MWh/år, installera bättre styrning till ventilationen – 110 MWh/år, installera bättre styrning till belysning – 40 MWh/år.

  • 113.
    Boman, Tomas
    et al.
    Högskolan i Gävle, Akademin för hälsa och arbetsliv, Avdelningen för socialt arbete och psykologi, Socialt arbete. Swedish Institute for Disability Research, Örebro University.
    Kjellberg, Anders
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Miljöpsykologi.
    Danermark, Berth
    Swedish Institute for Disability Research, Örebro University, Örebro, Sweden.
    Boman, Eva
    Högskolan i Gävle, Akademin för hälsa och arbetsliv, Avdelningen för socialt arbete och psykologi, Psykologi.
    Can people with disabilities gain from education?: Similarities and differences between occupational attainment among persons with and without disabilities2014Inngår i: Work: A journal of Prevention, Assesment and rehabilitation, ISSN 1051-9815, E-ISSN 1875-9270, Vol. 49, nr 2, s. 193-204Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: More knowledge is needed ofoccupational attainment of persons with disabilities, i.e. the relationship between their educational level and their profession, and factors of importance for this relationship.

    Objective: To compare occupational attainment among persons with and without a disability.

    Method: 3 396 informants with disabilities and 19 004 non-disabled informants participated (control group) in a survey study by Statistics Sweden.The informants with disabilities were divided into six groups.

    Results: Occupational attainment did not differ between the disability groups, neither between persons with and without a disability. Follow-up analysis showed that men with disabilities with primary or secondary school had an occupation above their educational level to a significantlylarger extent than women with disabilities. This pattern was even clearer in comparison with the control group. Persons without disabilities, with secondary or higher education, were more successful in the labor market than persons with disabilities. Occupational attainment increased with age in both groups.

    Conclusions: Young women with disabilities who only have primary or secondary education run a higher risk of having a job that is below their educational level than men at the same educational level. This indicates discriminating mechanisms in the society related to gender and ability.

  • 114.
    Boman, Tomas
    et al.
    Högskolan i Gävle, Akademin för hälsa och arbetsliv, Avdelningen för socialt arbete och psykologi, Socialt arbete. Swedish Institute for Disability Research, Örebro University, Örebro, Sweden.
    Kjellberg, Anders
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Miljöpsykologi.
    Danermark, Berth
    Swedish Institute for Disability Research, Örebro University, Örebro, Sweden.
    Boman, Eva
    Högskolan i Gävle, Akademin för hälsa och arbetsliv, Avdelningen för socialt arbete och psykologi, Psykologi.
    Employment opportunities for persons with different types of disability2015Inngår i: Alter;European Journal of Disability Research ;Journal Europeen de Recherche Sur le Handicap, ISSN 1875-0672, E-ISSN 1875-0680, Vol. 9, nr 2, s. 116-129Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The employment status of groups with different disabilities wasanalysed as were potentially important moderating factors (workability, structural and individual factors). A secondary analy-sis was performed on 4359 respondents with disabilities fromStatistics Sweden's Labour Market Investigation. The respondentswere divided into six disability groups (communicative-hearing,communicative-speech-reading, communicative-vision, psycho-logical disability, medical disability, physical disability). Logisticregression analyses showed that the probability of being employedwas highest among respondents with hearing disabilities andrespondents with psychological disabilities were least likely tobe employed. Being a woman (very young or old) with onlyprimary education and with partially or very impaired workability, reduced employment opportunities. Higher education didnot increase employment opportunities for respondents withimpaired work ability. In summary, the type of disability is essentialfor employment opportunities, and differences between disabil-ity groups cannot be explained by differences in other variables. 

  • 115.
    Bosnjak, Vjekoslav
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Waste Heat Recovery in Intensive Small and Medium Sized Industries: Case Study - Gästrike Härdverkstad2012Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    In order to keep a high level and to stay competitive in the world market in the future, it is important for the Swedish steel industry to improve their efficiencies continuously and to reduce the energy consumption. In order to realize these goals, the Swedish steel association Jernkotoret was found and by their initiative Triple Steelix was found in 2006 in Berglanden, a significant area for the steel industry. In 2009, the Clean Production Centre was found in Hofors in order to build a cluster of local steel manufacturers, factories and companies. One of those companies is Gästrike Härdverkstad, a small steal heat treatment industry with six employees and about 700.000 tons treated materials every year.

    The aim for this thesis is to suggest solutions for recovering waste heat and lowering the total energy consumption in furnaces for heat treatment in the case of Gästrike Härdverkstad.

    Some limitations were necessary to complete the analysis and to come to conclusions. The yearly treated material and energy prices were assumed to be constant and the yearly power consumption was estimated by an extrapolation of a one to five days measurement.

    Gästrike Härdverkstad is located in Uhrfors, the southern part of Åshammar, a village with 727 inhabitants. There are not any buildings with a possibility to supply heat and there is no district heating in the surroundings. The company has a power consumption of 1.40 GWh/year, of which 65.7% is consumed by the 12 main furnaces. The rest is used by eight seldom used furnaces, devices and auxiliary machines of the support process like fans, pumps, compressor, office heating, and some other. The efficiencies of the main furnaces are between 10% and 20%.The estimated energy consumption of the space heating is about 27 MWh/year, which completely can be covered by the material coolant and the combustion heat of the exhaust gases from the hardening furnaces. Since there are 10 different types of furnaces with different duties and efficiencies, the preheating furnace was taken as an example and compared with a new furnace. According to the needs of Gästrike Härdverkstad, the furnace VAW 60/100-650°C from the company Vötsch was chosen at the cost of 248,827 SEK. The payback time depends on the efficiency. With an efficiency of 40% the payback time would be about 13 years, see Figure 20.

    After the annealing and ageing, the finished products are cooled down in the building hall by the ambient air. In future, the possibility of preheating the material with the heat of the finished products should be considered. With an efficiency of 30.87%, one preheating furnace could bereplaced, and taken a payback time of 5 years into account; the price of the construction would be allowed to be up to 253,200 SEK.

  • 116.
    BOUCHANE, Sofia
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Energy auditing and saving for a four floor building: Diös building, ventilation and heating system2015Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
  • 117.
    Bravo Jimenez, Ismael
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Detection and removal of wind turbine ice: Method review and a CFD simulation test2018Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    Nowadays, the energy sector is facing a huge demand that needs to be covered. Wind energy is one of the most promising energy resources as it is free from pollution, clean and probably will arise as one of the main energy sources to prevent global warming from happening. Almost 10% of the global energy demand is coming from renewable resources. By 2050 this percentage is expected to grow to 60%. Therefore, efforts on wind turbine technology (i.e. reliability, design…) need to be coped with this growth.

    Currently, large wind energy projects are usually carried out in higher altitudes and cold climates. This is because almost all of the cold climates worldwide offer profitable wind power resources and great wind energy potential. Operating with wind turbines in cold climates bring interesting advantages as a result of higher air density and consequently stronger winds (wind power is around 10% higher in the Nordic regions). Not only benefits can be obtained but extreme conditions force to follow harsh conditions. Low temperatures and ice accretion present an important issue to solve as can cause several problems in fatigue loads, the balance of the rotor and aerodynamics, safety risks, turbine performance, among others. As wind energy is growing steadily on icy climates is crucial that wind turbines can be managed efficiently and harmlessly during the time they operate.

    The collected data for the ice detection, de-icing and anti-icing systems parts was obtained through the company Arvato Bertelsmann and is also based on scientific papers. In addition, computer simulations were performed, involving the creation of a wind tunnel under certain conditions in order to be able to carry out the simulations (1st at 0ºC, 2nd at -10ºC) with the turbine blades rotating in cold regions as a standard operation.

    In this project, Computational Fluids Dynamics (CFD) simulation on a 5MW wind turbine prototype with ice accretion on the blades to study how CL and CD can change, also different measures of ice detection, deicing and anti-icing systems for avoiding ice accumulation will be discussed. Simulation results showed a logical correlation as expected, increasing the drag force about 5.7% and lowering the lift force 17,5% thus worsening the turbine's efficiency.

  • 118.
    Bren d'Amour, Christopher
    et al.
    Mercator Research Institute on Global Commons and Climate Change, Germany; Department Economics of Climate Change, Technische Universität Berlin, Berlin, Germany.
    Reitsma, Femke
    Department of Geography,Canterbury University, Christchurch, New Zealand.
    Baiocchi, Giovanni
    Department of Geographical Sciences, University of Maryland, College Park, MD, USA.
    Barthel, Stephan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Miljöteknik. Stockholm Resilience Centre, Stockholm University, Stockholm, Sweden.
    Güneralp, Burak
    Center for Geospatial Science, Applications and Technology (GEOSAT), Texas A&M University, College Station, TX, USA.
    Erb, Karl-Heinz
    Institute of Social Ecology Vienna, Alpen-Adria Universitaet Klagenfurt, Vienna, Austria.
    Haberl, Helmut
    Institute of Social Ecology Vienna, Alpen-Adria Universitaet Klagenfurt, Vienna, Austria.
    Creutzig, Felix
    Mercator Research Institute on Global Commons and Climate Change, Germany; Department Economics of Climate Change, Technische Universität Berlin, Berlin, Germany.
    Seto, Karen C.
    Yale School of Forestry and Environmental Studies, Yale University, New Haven, CT, USA.
    Future urban land expansion and implications for global croplands2017Inngår i: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 114, nr 34, s. 8939-8944Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Urban expansion often occurs on croplands. However, there is little scientific understanding of how global patterns of future urban expansion will affect the world's cultivated areas. Here, we combine spatially explicit projections of urban expansion with datasets on global croplands and crop yields. Our results show that urban expansion will result in a 1.8-2.4% loss of global croplands by 2030, with substantial regional disparities. About 80% of global cropland loss from urban expansion will take place in Asia and Africa. In both Asia and Africa, much of the cropland that will be lost is more than twice as productive as national averages. Asia will experience the highest absolute loss in cropland, whereas African countries will experience the highest percentage loss of cropland. Globally, the croplands that are likely to be lost were responsible for 3-4% of worldwide crop production in 2000. Urban expansion is expected to take place on cropland that is 1.77 times more productive than the global average. The loss of cropland is likely to be accompanied by other sustainability risks and threatens livelihoods, with diverging characteristics for different megaurban regions. Governance of urban area expansion thus emerges as a key area for securing livelihoods in the agrarian economies of the Global South.

  • 119.
    Broberg, Per
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Energisystemåtgärder i fastigheter: en stadsdelsförnyelse2011Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Detta arbete beskriver möjligheten att renovera och energieffektivisera fyra fastigheter i stadsdelen Sätra i Gävle. Den totala ytan på alla fyra huskroppar är ca 4200m2. Ägare till fastigheterna är Gavlegårdarna AB och arbetet utförs åt Tema-gruppen som har ansvar för bland annat energiavsnittet i restaureringen.

     

    Målet med renoveringen var att sänka energiförbrukningen med ca 60 % samt att byta fastigheternas energilösning, både för uppvärmning och tappvarmvatten. Den planerade renoveringen kan sedan fungera som en vägvisare för övriga fastighetsbolag vilka kan dra nytta av resultaten i detta projekt.

     

    Arbetet omfattar även teoretiska beskrivningar på funktionen hos olika system som tas upp som intressanta för projektet, såsom olika ventilationslösningar, funktionen hos en värmepump, energilager samt hur solens strålar påverkar energibalansen i en fastighet.

     

    Olika åtgärder för energibesparing och energiproduktion som inte är planerade för detta projekt, men som skulle kunna appliceras även här, har också tagits upp för att ge en större bild av hur mycket som finns att åtgärda på gamla hus när det gäller energibesparing. Förslag på extra åtgärder är: energibesparing vid byte av belysningskällor, återvinning av gråvatten, byte av cirkulationspumpar, injustering av värmesystemet samt egen produktion av el från vinden.

     

    Resultatet av detta arbete visar att det är fullt möjligt att, efter att de presenterade åtgärderna verkställts, minska energiförbrukningen med de 60 % som målet var. Detta ger självklart en lägre driftkostnad för fastighetsägaren, men huruvida installationskostnaden överstiger de besparingar som görs tas ej upp i denna rapport. Resultaten visar således på en tydlig energibesparing vilket innebär minskad belastning på vår miljö.

  • 120. Broberg Viklund, Sarah
    et al.
    Johansson, Maria T.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Technologies for utilization of industrial excess heat: Potentials for energy recovery and CO2 emission reduction2014Inngår i: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 77, s. 369-379Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Industrial excess heat is a large untapped resource, for which there is potential for external use, which would create benefits for industry and society. Use of excess heat can provide a way to reduce the use of primary energy and to contribute to global CO2 mitigation. The aim of this paper is to present different measures for the recovery and utilization of industrial excess heat and to investigate how the development of the future energy market can affect which heat utilization measure would contribute the most to global CO2 emissions mitigation. Excess heat recovery is put into a context by applying some of the excess heat recovery measures to the untapped excess heat potential in Gavleborg County in Sweden. Two different cases for excess heat recovery are studied: heat delivery to a district heating system and heat-driven electricity generation. To investigate the impact of excess heat recovery on global CO2 emissions, six consistent future energy market scenarios were used. Approximately 0.8 TWh/year of industrial excess heat in Gavleborg County is not used today. The results show that with the proposed recovery measures approximately 91 GWh/year of district heating, or 25 GWh/year of electricity, could be supplied from this heat. Electricity generation would result in reduced global CO2 emissions in all of the analyzed scenarios, while heat delivery to a DH system based on combined heat and power production from biomass would result in increased global CO2 emissions when the CO2 emission charge is low. 

  • 121.
    Broström, Simon
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Energianalys av byggnad i industriell miljö: Energikartläggning med effektiviseringsförslag till byggnad innehå̊llande betningsprocess hos Ovako Hofors AB2015Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Världen står inför stora utmaningar där energibehovet ständigt ökar i takt med den globala ekonomin. Något de flesta människor idag känner till är kopplingen mellan energianvändning och negativ påverkan av miljö samt klimat.

    Sveriges industrier står inför stora utmaningar med ständigt växande global marknad. Följder blir tuffare konkurrenssituation för många företag. Konkurrenssituationen medför att företag flyttar sin verksamhet till länder med lägre produktionskostnader. Kostnader vilka i Sverige har ökat väldigt mycket de senaste decennierna. För att stoppa utflyttning av industriverksamhet krävs stora effektiviseringar i industriföretags energianvändning och förändring av attityd gentemot energianvändning.

    Studien vilken ligger till grund för rapporten utfördes med energikartläggning av en lokal hos ståltillverkaren Ovako Sweden AB i Hofors. Lokalen där energikartläggningen utförts innehåller en process kallad betning. Kartläggningen grundas på data erhållna av ÅF, vilka även har varit samarbetspartners i studien.

    Väldigt stora mängder energi används i lokalen, närmare bestämt 14 000 MWh. Störst andel energi går till produktionsprocesser i form av ånga och elektricitet. Ånganvändning står för 8 500 MWh medan elektricitetsanvändning uppgår till 4 500 GWh. För ånga kan kostnadsminskning med 60 % implementeras. Elektricitetskostnader kan med föreslagna metoder minskas med uppskattningsvis 14 %.

    För uppvärmning av lokalen beräknades användningen uppgå till 2 500 MWh. Användning av uppvärmningsenergi kan minskas drastiskt då byggnaden är väldigt dåligt isolerad och använder mycket energi till uppvärmning. Vid införande av samtliga föreslagna åtgärder för uppvärmning sparas totalt 95 % av uppvärmningskostnader 

  • 122.
    Brunke, Jean-Christian
    et al.
    Institute for Energy Economics and the Rational Use of Energy (IER), University of Stuttgart, Stuttgart, Germany .
    Johansson, Maria
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem. Department of Management and Engineering, Division of Energy Systems, Linköping University.
    Thollander, Patrik
    Department of Management and Engineering, Division of Energy Systems, Linköping University, Linköping, Sweden .
    Empirical investigation of barriers and drivers to the adoption of energy conservation measures, energy management practices and energy services in the Swedish iron and steel industry2014Inngår i: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 84, nr 1, s. 509-525Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Swedish iron and steel industry is focused on the production of advanced steel grades and accounts for about 5% of the country's final energy consumption. Energy efficiency is according to the European Commission a key element for the transition towards a resource-efficient economy. We investigated four aspects that are associated with the adoption of cost-effective energy conservation measures: barriers, drivers, energy management practices and energy services. We used questionnaires and follow-up telephone interviews to collect data from members of the Swedish steel association. The heterogeneous observations implied a classification into steel producers and downstream actors. For testing the significance, the Mann–Whitney U test was used. The most important barriers were internal economic and behavioural barriers. Energy service companies, in particular third-party financing, played a minor role. In contrast, high importance was attached to energy management as the most important drivers originated from within the company. Energy management practices showed that steel companies are actively engaged in the topic, but need to raise its prioritisation and awareness within the organisation. When sound energy management practices are included, the participants assessed the cost-effective energy conservation potential to be 9.7%, which was 2.4% higher than the potential for solely adopting cost-effective technologies.

  • 123.
    Buccoliere, Riccardo
    et al.
    Universita di Lecce.
    Sandberg, Mats
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Byggvetenskap - installationsteknik.
    Di Sabatino, Silvana
    Universita di lecce.
    An application of ventilation efficiency concepts to the analysis of building density effects on urban flow and pollutant concentration2011Inngår i: International Journal of Environment and Pollution, ISSN 0957-4352, E-ISSN 1741-5101, Vol. 47, nr 1-4, s. 248-256Artikkel i tidsskrift (Fagfellevurdert)
  • 124.
    Buccoliere, Riccardo
    et al.
    Univ Salento, Dipartimento Sci Mat, Lecce, Italy, and Univ Ca Foscari Venezia, Dipartimento Informat, Venice, Italy.
    Sandberg, Mats
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Byggvetenskap - installationsteknik.
    Di Sabatino, Silvana
    Univ Salento, Dipartimento Sci Mat, Lecce, Italy .
    City breathability and its link to pollutant concentration distribution within urban-like geometries2010Inngår i: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 44, nr 15, s. 1894-1903Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper is devoted to the study of pollutant concentration distribution within urban-like geometries. By applying efficiency concepts originally developed for indoor environments, the term ventilation is used as a measure of city “breathability”. It can be applied to analyse pollutant removal within a city in operational contexts. This implies the evaluation of the bulk flow balance over the city and of the mean age of air. The influence of building packing density on flow and pollutant removal is, therefore, evaluated using those quantities. Idealized cities of regular cubical buildings were created with packing density ranging from 6.25% to 69% to represent configurations from urban sprawl to compact cities. The relative simplicity of these arrangements allowed us to apply the Computational Fluid Dynamics (CFD) flow and dispersion simulations using the standard k turbulence model. Results show that city breathability within the urban canopy layer is strongly dependent from the building packing density. At the lower packing densities, the city responds to the wind as an agglomeration of obstacles, at larger densities (from about 44%) the city itself responds as a single obstacle. With the exception of the lowest packing density, airflow enters the array through lateral sides and leaves throughout the street top and flow out downstream. The air entering through lateral sides increases with increasing packing density.

    At the street top of the windward side of compact building configurations, a large upward flow is observed. This vertical transport reduces over short distance to turn into a downward flow further downstream of the building array. These findings suggest a practical way of identifying city breathability. Even though the application of these results to real scenarios require further analyses the paper illustrates a practical framework to be adopted in the assessment of the optimum neighbourhood building layout to minimize pollution levels.

  • 125.
    Buccolieri, R.
    et al.
    Dipartimento di Informatica, Università Ca' Foscari Venezia, Mestre-Venezia, Italy; Dipartimento di Scienza Dei Materiali, University of Salento, Lecce, Italy.
    Sartoretto, F.
    Dipartimento di Informatica, Università Ca' Foscari Venezia, Mestre-Venezia, Italy.
    Giacometti, A.
    Dipartimento di Scienza Dei Materiali, University of Salento, Lecce, Italy.
    Di Sabatino, S.
    Dipartimento di Scienza Dei Materiali, University of Salento, Lecce, Italy.
    Leo, L.
    Dipartimento di Scienza Dei Materiali, University of Salento, Lecce, Italy.
    Pulvirenti, B.
    Dipartimento di Ingegneria Energetica, Nucleare e Del Controllo Ambientale, University of Bologna, Bologna, Italy.
    Sandberg, Mats
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Byggvetenskap - installationsteknik.
    Wigö, Hans
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Byggvetenskap - installationsteknik.
    Flow and pollutant dispersion within the Canal Grande channel in Venice (Italy) via CFD techniques2010Inngår i: HARMO 2010 - Proceedings of the 13th International Conference on Harmonisation within Atmospheric Dispersion Modelling for Regulatory Purposes / [ed] Albergel, A., 2010, s. 760-764Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The present paper is aimed at the analysis of flow and pollutant dispersion in a portion of the Canal Grande (Grand Canal) in Venice (Italy) by means of both Computational Fluid Dynamics (CFD) FLUENT simulations and wind tunnel experiments performed at the University of Gävle (Sweden). For this application, Canal Grande can be viewed as a sort of street canyon where the bottom surface is water and bus boat emissions are the major source of pollution. Numerical investigations were made to assess the effect of the water surface on air flow and pollutant concentrations in the atmosphere. One of the challenges has been to deal with the interface between two immiscible fluids which requires ad-hoc treatment of the wall in terms of the numerical scheme adopted and the grid definition which needs to be much finer than in typical numerical airflow simulations in urban street canyons. Preliminary results have shown that the presence of water at the bottom of the street canyon modifies airflow and turbulence structure with direct consequences on concentration distribution within the domain.

  • 126.
    Buccolieri, R.
    et al.
    Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali, University of Salento, Lecce, Italy.
    Wigö, Hans
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Sandberg, Mats
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Sabatino, S. D.
    Department of Physics and Astronomy, University of Bologna, Italy.
    On the drag force distribution over arrays of cubical buildings: Wind tunnel experiments2017Inngår i: HARMO 2017 - 18th International Conference on Harmonisation within Atmospheric Dispersion Modelling for Regulatory Purposes, Proceedings, Hungarian Meteorological Service , 2017, s. 384-388Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper we discuss the distribution of drag force along aligned arrays of cubes of different packing density. The distribution is evaluated via wind tunnel measurements performed on individual cubes located along the middle column of the array using a balance provided by a standard load cell. Results are compared with the drag force estimated by a pressure-derived method and clearly show a change of the distribution of the drag force. The force is uniform at low packing densities, while mostly acting on first rows of the arrays at large packing densities. This work leaves room for research tailored to a better parameterization of urban effects in dispersion models.

  • 127.
    Buccolieri, Riccardo
    et al.
    Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali, University of Salento, Lecce, Italy.
    Wigö, Hans
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Sandberg, Mats
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Di Sabatino, Silvana
    Department of Physics and Astronomy, University of Bologna, Bologna, Italy.
    Direct measurements of the drag force over aligned arrays of cubes exposed to boundary-layer flows2017Inngår i: Environmental Fluid Mechanics, ISSN 1567-7419, E-ISSN 1573-1510, Vol. 17, nr 2, s. 373-394Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Wind tunnel measurements of the total drag force for aligned arrays of cubes exposed to two different boundary-layer flows at three flow velocities are discussed. The drag force for eight different building packing densities λp (from 0.028 to 1) is measured with a standard load cell generating a novel dataset. Different λp are reproduced by increasing the number of buildings on the same lot area; this represents a real situation that an urban planner is faced with when a lot area of a given (fixed) size is allocated to the development of new built areas. It is assumed that the surrounding terrain is uniform and there is a transition from a given roughness (smooth) to a new roughness (rough). The approaching flow will adjust itself over the new surface within a distance that in general may be larger than the horizontal length covered by the array. We investigate the region where the flow adjustment occurs. The wide range of packing densities allowed us to analyse in detail the evolution of the drag force. The drag force increases with increasing packing densities until it reaches a maximum at an intermediate packing density (λp = 0.25 in our case) followed by a slight decrease at larger packing densities. The value of the drag force depends on the flow adjustment along the array which is evaluated by introducing the parameter “drag area” to retrieve information about the drag distribution at different λp. Results clearly suggest a change of the distribution of the drag force, which is found to be relatively uniform at low packing densities, while most of the force acts on first rows of the arrays at large packing densities. The drag area constitutes the basis for the formulation of a new adjustment length scale defined as the ratio between the volume of the air within the array and the drag area. The proposed adjustment length scale automatically takes into account the change in drag distribution along the array for a better parameterization of urban effects in dispersion models. 

  • 128.
    Bueno Rosete, Isabel
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Energy Audit of an industrial building in Sweden: Case study of a CNC processed components’ producer company2018Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    The industrial sector accounts for almost 40 % of the Swedish energy use and in order to meet the EU’s 2020 targets, an efficient production of high quality and great finish goods are more and more in demand. Moreover, it is important to develop the activities with the lowest environmental impact possible. 

    The energy audit process is an effective tool to achieve it. Thus, in this document the energy audit of an industrial company, Automat Industrier in Gävle, Sweden, was carried out.

    The energy balance of the building and the potential energy efficiency measures were analyzed with the IDA ICE simulation.

    The proposed energy retrofitting was apropos of the building envelope, the lighting system, the ventilation system and the installation of a PV system on the roof of the building.

    The survey indicated that the potential energy savings of the company accounted for 62.5 % of the current electricity use and 48.8 % of the current DH use if all the proposed ameliorations were performed. The main promoter of the electricity savings is the installation of the PV system, with 85 % of influence. Almost 90 % of the DH savings are due to the measures in the ventilation system.

    Financially, these savings can reach the amounts of 531 597 SEK/year for electricity and 174 201 SEK/year for DH.

    Nevertheless, the ameliorations regarding the building envelope have very long payback periods. Thus, it was recommended to not pursue them. Fortunately, the energy efficiency measures providing the greatest savings’ payback periods are between 3.47 years and 10.22 years long. As they are independent from each other, the owner has the freedom to decide whether to apply them or not and when if so.

  • 129.
    Buske, Elias
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Fuktegenskaper hos Quartzene impregnerat med salter2012Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Svenska Aerogel AB has developed the material Quartzene® which is of the typeprecipitated silica and contains calcium - magnesium silicate ((Ca, Mg) SiO3). Thematerial is used for molecular filtration of contaminated air. Qartzene™, which is inpellet form, is porous and has a high internal surface which is a requirement for themolecular filtration. With the use of various impregnations, filtration can affect thedesired outcome. As an example Quartzene® can be impregnated with Potassiumhydroxide and clear the air of Sulfur dioxide, SO2 (Svenska Aerogel AB, n.d).Svenska Aerogel AB has developed Quartzene® further and new areas of application hasarosee, one of these areas is how the material function within dehumidification. Thepurpose of this study is to research and analyze how different impregnation salts effecthow Quartzene® function in terms of moisture absorption and moisture desorption.Quartzene® is a hygroscopic material, which is a material that easily absorbs and exudatesmoisture from the air. Materials with high porosity absorb moisture by adsorption andcapillary condensation. A hygroscopic material strives for equilibrium with ambientenvironment which is illustrated in a sorption curve where moisture absorption is set inrelation to relative humidity. In this study the jar method is used to measure moistureabsorption, this is shown with the use of sorption curves. The jar method uses saturatesalt solutions to create environments whit a set relative humidity. Quartzene® – pellets areplaced in jars and weighed at regular intervals to determine the moisture absorption.The results of this study indicate that impregnations affect the way that Quartzene®function in terms of moisture absorption and moisture desorption. Some of theimpregnations affect the material to absorb more moisture than Quartzene® that has notbeen impregnated, while others affect the material to absorb less moisture. The resultsalso show that sodium – based impregnation gives similar results as Quartzene® that hasnot been impregnated.

  • 130.
    Cabral, Diogo
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Simulation of Electrical Performance of a Newly Developed Symmetrical Low Concentrator PVT Solar Collector: Low Latitudes2017Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
  • 131.
    Cabral, Diogo
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem. Solarus Sunpower Sweden AB.
    Simulation of Electrical Performance of a Newly Developed Symmetrical Low Concentrator PVT Solar Collector: Low Latitudes2017Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
  • 132.
    Cabral, Diogo
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Gomes, João
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem. Solarus Sunpower Sweden AB, Gävle, Sweden.
    Dostie-Guindon, Paul-Antoine
    Ecole Polytechnique Montréal, Montréal, Canada.
    Karlsson, Björn O.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Ray tracing simulations of a novel low concentrator PVT solar collector for low latitudes2017Inngår i: ISES Solar World Congress 2017 - IEA SHC International Conference on Solar Heating and Cooling for Buildings and Industry 2017, Proceedings, International Solar Energy Society , 2017, s. 1068-1079Konferansepaper (Fagfellevurdert)
    Abstract [en]

    One way to reduce solar collector's production costs is to use concentrators that increase the output per photovoltaic cell. Concentrating collectors re-direct solar radiation that passes through an aperture into an absorber. The current study evaluates electrical performance of symmetric C-PVT solar collectors with a vertical bifacial receiver, through a numerical ray tracing model software, Tonatiuh. Several designs have been analysed, such as the Pure Parabola (PP) and MaReCo CPC geometries, both symmetric. Parameters such as concentration factor, electrical performance, transversal and longitudinal IAM (Incidence Angle Modifier), the influence of optical elements and influence of the length of the reflector in the shadow effect have been studied for different geometries. The simulations were performed for Mogadishu, Somalia and showed good results for the Pure Parabola collector (PPc) annual received energy, 379 and 317 kWh/m2/year for a focal length of 15 e 30 mm, respectively. A symmetrical double MaReCo CPC collector has been simulated with the annual received energy of 315 kWh/m2/year. The addition of the optical elements will decrease the annual received energy of the PPc by around 11.5%, where the optical properties (7.1%) and glass (4.1%) have the biggest impact in the annual received energy. Overall, symmetric geometries proved to be the most suitable geometries for low latitudes applications, being the geometry f1 (focal length of 15 mm) the best one. 

  • 133.
    Cabral, Diogo
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Karlsson, Björn O.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Electrical and thermal performance evaluation of symmetric truncated C-PVT trough solar collectors with vertical bifacial receivers2018Inngår i: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 174, s. 683-690Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    One way to reduce solar collectors’ production costs is to use concentrators that increase the output per photovoltaic cell. Concentrating collectors re-direct solar radiation that passes through an aperture into an absorber/receiver. Symmetrical truncated non-tracking C-PVT trough collectors based on a parabola and compound parabolic concentrator (CPC) geometries have been developed. The collector type has a central vertical bifacial (fin) receiver and it was optimized for lower latitudes. In this paper, the electrical and thermal performance of symmetric truncated non-tracking low concentrator PVT solar collectors with vertical bifacial receivers is analysed, through a numerical ray-tracing model software and a multi-paradigm numerical computing environment. A thermal (quasi-dynamic testing method for liquid heating collectors described in the international standard for solar thermal collectors ISO 9806:2013) and electrical performance models were implemented to evaluate the design concepts. The evaluation was made for heating Domestic Hot Water for a Single Family House in Fayoum (Egypt), where CPC geometries with a concentration factor of 1.6 achieved 8 to 13%rel higher energy yields (in kWh/m2/year) than the Pure Parabola geometries.

  • 134.
    Calance, Marius Alexandru
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Energy Losses Study on District Cooling Pipes: Steady-state Modeling and Simulation2014Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Distributionsförluster är en viktig faktor i fjärrenergisystem. Genom att optimera förluster i sådana system, kan både ekonomiska och miljömässiga aspekter uppfyllas. Tyvärr finns det ringa information om rörförluster i fjärrkylasystem. Föreliggande studie fokuserar på förluster i ett fjärrkylanät genom att både använda ett R-nätverk och FEM simuleringsmodeller. Ett R-nätverksmodell bestående av termiska konduktanser har utvecklats genom analytiska ekvationer och simuleringar med FEM har utfört för validering av modellen. Därefter har ett fjärrkylanätverk som konstrueras i Gävle, analyserats. Undersökningen omfattar 15 olika rördiametrar i tre utföranden (dubbelrör med två symmetriska och en osymmetrisk värmeisolering) och i tre förläggningsdjup (0,8; 2 och 4 meter) för en säsong om 7 månader (April t o m Oktober). Särskilt utreds ökningen av temperaturen hos framledningsmediet, där matningsrören förlagts i en å mitt i staden om en sträcka av 1 km. Den maximala förlusten under säsongen, bland alla rörkonfigurationer, motsvarar 2 % av den totala levererade energin. Slutligen konstateras att kombinationen av isolerad framledningsrör och oisolerade returrör verkar som en gångbar investering, ekonomiskt och tekniskt, men kan inte användas i hela nätet eftersom stora delar har redan byggts med oisolerade plaströr. R-nätverksmodellen, som visades vara effektiv och pålitlig i undersökningen, kan som beräkningsverktyg, framförallt för dimensionering och för att uppskatta energiförluster. 

  • 135.
    Campbell, T. A.
    et al.
    Department of Psychology and Logopedics, Faculty of Medicine, University of Helsinki, Helsinki, Finland.
    Marsh, John E.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Miljöpsykologi. School of Psychology, University of Central Lancashire, Preston, United Kingdom.
    Commentary: Donepezil enhances understanding of degraded speech in Alzheimer's disease2018Inngår i: Frontiers in Aging Neuroscience, ISSN 1663-4365, E-ISSN 1663-4365, Vol. 10, artikkel-id 197Artikkel i tidsskrift (Fagfellevurdert)
  • 136.
    Campbell, T. A.
    et al.
    Department of Psychology and Logopedics, Faculty of Medicine, University of Helsinki, Helsinki, Finland.
    Marsh, John E.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Miljöpsykologi. School of Psychology, University of Central Lancashire, Preston, UK.
    On corticopetal-corticofugal loops of the new early filter: from cell assemblies to the rostral brainstem2019Inngår i: NeuroReport, ISSN 0959-4965, E-ISSN 1473-558X, Vol. 30, nr 3, s. 202-206Artikkel i tidsskrift (Fagfellevurdert)
  • 137.
    Cano, Unai
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Energy Audit for an Old Industrial Building in Gävle2016Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    The Swedish industrial sector has overcome the oil crisis and has maintained the energy use constant even though the production has grown. This has been achieved thanks to the development of several energy policies, by the Swedish government, towards the 2020 goals.

    This thesis carries on this path and performs an energy audit for an old industrial building in Gävle (Sweden) in order to propose different energy efficiency measures to use less energy while maintaining the thermal comfort. The building is in quite a bad shape and some of the areas are unused making them a waste of money.

    By means of the invoices provided by different companies, the information from the staff and some measures that have been carried out in-situ, the energy balance has been calculated from where conclusions have been drawn.

    Although it is an industrial building, the study is not going to be focused in the industrial process but in the building’s envelope and support processes, since the unit combines both production and office areas. Therefore, the energy balance is divided in energy supplies (district heating, free heating and sun irradiation) and energy losses (transmission, ventilation hot tap water and infiltrations).

    The results show that the most important supply is that of the DH whereas the most important losses are the transmission and infiltration. Thus, the measures proposed are focused on the reduction of this relevant parameters. The most important measures are the renovation of the windows, heating systems valves and the ventilation. The glazing of the dwelling is old and some of it is broken accounting for quite a large amount of the losses. The radiator valves are not properly working and there does not exist any temperature control. Therefore the installation of thermostatic valves turns out to be a must. Moreover, some part of the building has no mechanical ventilation but conserves the ducts. These could be utilized if they are connected to the workshop’s ventilation which is capable of generating sufficient flow for the entire building.

    Finally, although other measures could also be carried out, the ones proposed appear to be the essential ones. A further analysis should be carried out in order to analyze the payback time or investment capability of the company so as to decide between one measure or another. A market study for possible new tenants for the unused parts of the building is also advisable.

  • 138.
    Carlsson, Johan
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Blomberg, Patric
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Geoenergi: En studie på Nyköpings lassarets möjlighet till fri-värme/kyla m.h.a. ett borrhålslager2014Independent thesis Basic level (degree of Bachelor), 180 hpOppgave
  • 139.
    Carreras Bertran, Antoni
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Energy system and economic analysis of district cooling at the city hall of GävleIndependent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
  • 140.
    Casao, Marah
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Study of quality of drinking water: In rural areas of Souss Massa region2018Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [en]

    The scarcity of water affects many developing nations. Today, Morocco,characterized by an arid and semi-arid climate, is approaching absolute scarcityof freshwater availability of 730 m3/capita/year. The effect of the scarcity ofwater is highly evident in rural localities, which are driven to rely on wellwater and rainwater harvesting. Potability of alternative water sources isuncertain as it is not monitored by municipal treatment plants.The objective of this investigation was to study the quality and quantity ofdrinking water in rural areas of Souss Massa region. Water samples collectedfrom seven study sites were sent to private laboratories for microbiologicaland physicochemical analysis.The results of the tests revealed that the drinking water in Agadir Ouguejgal,Ben Anfar and Ait Said was unsafe for human consumption due to fecalcontamination. Concerning physicochemical examination, nitrate levels inTouamal as well as iron levels in Agadir Ouguejgal exceeded the maximumallowable concentration provided by the WHO and the Moroccan regulations.This constitutes serious health risk to its population. To prevent diseaseoutbreaks and long-term illness in these areas, anomalies to MoroccanStandards, should be addressed.The scarcity of water is highly evident in Agadir Ouguejgal, where waterconsumption is approximately 8 l/capita/day. With this amount of waterconsumption, proper sanitation cannot be assured.Statistically, a strong correlation was found between E. coli and totalcoliform. Trend analysis demonstrated a downward trend on water balance inthe Souss Massa region.To mitigate water quality issues in the Souss Massa region, a morecomprehensive investigation is mandatory which focuses on the exact sourceof the pollution and measures that is applicable to rural villages.

  • 141.
    Castelltort Viñallonga, Emma
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Cold tap water usage for a chilling system2014Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    Both the increasing demand for comfort levels and growth in population are facts that assure that the energy demand in buildings will keep growing in the future. Heating, ventilation and air conditioning systems (HVAC systems) are the principal users of this total energy demand, where percentages over 50% have been reached. Air conditioning is essential to maintain the thermal comfort inside the buildings, and for this reason, innovative cooling systems should be analysed in order to reduce and improve energy usage of these systems.

     

    The aim of this thesis is to explore the viability and limitations of a new chilling system that uses tap water as a cooling source. The project has been focused on a building owned by an insurance company in Gävle, where a cooling system has been designed to satisfy the cooling need for an extremely hot day in summer. Water is taken from the main pipe and, via a heat exchanger, it absorbs heat from the chilling circuit. The destination of the tap water, once has been used, has been discussed proposing 3 different options: deliver it to the waste, bring it back to the tap water network and reuse it for hot tap water. Later, based on the results, an overview of the system has been done pointing out the weak and strong parts.

     

    When implementing this new system it has to be taken into account that cooling capacity is limited and extra requisites and limitations have to be accomplished since drinking water is used. The most energy efficient design is reusing the water for hot tap water use, since less heat will be needed to warm it up. However, if water is wanted to be reused it should not exceed 15  in order to avoid an environment where legionella could grow and become a health human threat.

    A suitable situation for this system would be for building which needs cooling and has a high hot tap water demand. 

  • 142.
    Castro Herce, Anabel
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Analysis of the condensation problem on the inner surface of Fullriggaren's large vertical window2013Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    This Thesis is focused on the study of the problem of condensation on the inner surface of Fullrigaren building’s large single pane window. This has serious consequences as water on the floor, corrosion or mould growth.

    As the climate in Nordic countries is cold for several months a year, windows are a crucial part in building envelopes. Condensation on a window may be suitably discussed only with respect to the climate considered as cold, moderate and warm climates pose different requirements on the windows, and this is why a characterization of Gävle by its climate is necessary.

    This Thesis will include the energy analysis of the staircase considered which is required to understand the source of the actual problem. Both heat and moisture transfer will be studied. In this purpose, an IDA model will be built to simulate the conditions throughout the year and hand-made calculations will be done for the average and most critical situations. The results show that condensation will already occur for the monthlyaverage conditions having as an additional problem that if temperature drops below zero it will freeze.

    Results will also be compared to an initial installation of a 2 pane window reaching as a conclusion that its original installation would had avoided the problems for most of the time.

    The Thesis will end with several proposals posed to solve the problem by either increasing the temperature or reducing the moisture content of the ambient air, and the selection of the best one. The final aim of the Thesis is to achieve an energy efficient window which should provide good lighting during the day and good thermal comfort both during day and night at minimum demand of paid energy. And for this, the selection of the electrically heated window is proposed.

  • 143.
    Catalan Ros, Leyre
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Analysis of human exposure at local exhaust ventilation by means of 3D air velocity measurements, tracer gas tests and controlled turbulence environment2015Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    Local exhaust (LE) ventilation is a ventilation technique where contaminated air is locally extracted close to the contaminant source usually with the purpose to reduce the exposure of workers to dust, fumes or vapour, which can be hazardous to their health. The performance of a LE installation depends however on many influential factors, and there is not yet an international standardized way to test LE constructions. The present study is the natural continuation of some previous studies at the University of Gävle that aimed at contributing to the establishment of such tests.

    The study entails full scale experimental measurements that include 3-D air velocity measurements and tracer gas tests in a controlled air turbulence environment generated through physical movements of a vertical, human-sized cylinder. These measurements were focused on human exposure, which was analysed by means of a seated human simulator for different configurations in which the exhaust flow rate, turbulence level, the exhaust hood arrangement and the measuring/injecting distance varied.

    The use of a sonic 3-D anemometer, that yielded both magnitude and direction of the air movement, proved very useful in analysing the generated air turbulence. As a measure of the LE performance, PNV value (Percentage of Negative Velocities) was used. This measure represents the percentage of time when the air flow at the measuring point in front of the exhaust hood is directed away from the nozzle, i.e. when the velocity component in the direction towards the exhaust hood opening is negative. Regarding the results obtained, in an otherwise undisturbed environment, measurement data showed that the natural convection from the human simulator sitting in front of the LE introduces some disturbances of the air flow in the suction region, proportional to the exhaust flow rate. However, when additional turbulence was generated through the controlled movements of the human-sized cylinder, thus creating a controlled turbulence setting, natural human convection leaded to a lower percentage of negative velocities (PNV) in comparison with the case in which human simulator was not present, especially for low exhaust air flow rates and when the exhaust hood was raised from the table.

    The tracer gas tests implied injection of a neutrally buoyant tracer gas through a perforated sphere placed in front of the exhaust hood. The amount of tracer gas that escaped from the suction flow was measured both in the room air and in the breathing zone. The first measurements yielded a sensitive method for measuring the capture efficiency (CE) of the exhaust hood. The CE is the percentage of injected tracer gas that is directly captured by the exhaust hood. This parameter showed that although the  convection flow generated by the human simulator leads to low PNV values, it seems that the tracer gas is not actually being captured, but trapped in that convection flow. As a consequence, PNV and CE get a strong correlation, which is even more intense when injection and capture point are closer together. Hence, PNV represents a good alternative to tracer gas measurements only if the relationship between the correlation of PNV and CE with respect to the distance from the injection to the capture point is known. Finally, measurements of tracer gas in the breathing zone showed random, short and high exposures when turbulence was generated and those exposures got worse by natural human convection.

  • 144.
    Catalan Solsona, Juan Antonio
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    The flow impact on a radiator system: A case study in district heating system2016Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
  • 145.
    Cehlin, Mathias
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Karimipanah, Taghi
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Prediction of indoor airflow close to a supply device using SST-SAS Model2015Inngår i: Ventilation 2015 - Proceedings of the 11th International Conference on Industrial Ventilation / [ed] Taipale A., Li Z., Li X., and Zhang X, International Conference on Industrial Ventilation , 2015, Vol. 2, s. 681-688Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Modern diffusers applied in the field of ventilation of rooms are often complex in terms of geometry, including perforated plates, dampers, guide rails, curved surfaces and other components inside the diffuser, with the intention to create satisfying thermal comfort for the occupants. Also connecting ducts can be different for the same diffuser in different situations, affecting the supply velocity profile. It is obvious that simulation of airflow and air temperature particularly in rooms with displacement ventilation is very troublesome, particularly if the near-zone of the diffuser is of interest. Experiments commonly indicate very high turbulence intensities in the near-zone of displacement ventilation supply devices, especially close to the floor where high mean flow gradient occurs. This indicates that the air flow from inlet devices designed for displacement ventilation might be very unsteady; the position of the stream leaving the diffuser and entering the room is changing with time, hence diffusion of momentum and temperature are increased. Also Kelvin-Helmholtz instabilities occurs, resulting in mixing and entrainment of surrounding air into the gravity current. These effects are not captured correctly in RANS simulations, since it is performed with the assumption of time-independent conditions. In this paper URANS simulations were performed for prediction of velocity and temperature distribution close to a complex air supply device in a room with displacement ventilation. The presented study show that URANS with the SST-SAS ᅵᅵ - ᅵᅵ turbulence model predicts the air velocities and air temperatures very well close to the air supply device. The URANS computation using the SST-SAS model seems to successfully contribute to the reproduction of large-scale unsteady flow patterns in the near-zone of the supply device, and therefore enable more accurate prediction of the velocity and temperature distributions compared to the steady-RANS computation and dissipative URANS models.

  • 146.
    Cehlin, Mathias
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Karimipanah, Taghi
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Larsson, Ulf
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Unsteady CFD simulations for prediction of airflow close to a supply device for displacement ventilation2014Inngår i: Indoor Air 2014 - 13th International Conference on Indoor Air Quality and Climate, 2014, s. 47-54Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Modern diffusers applied in the field of ventilation of rooms are often complex in terms of geometry, including perforated plates, dampers, guide rails, curved surfaces and other components inside the diffuser, with the intention to create satisfying thermal comfort for the occupants. Also connecting ducts can be different for the same diffuser in different situations, affecting the supply velocity profile. It is obvious that simulation of airflow and air temperature particularly in rooms with displacement ventilation is very troublesome, particularly if the near-zone of the diffuser is of interest. Experiments commonly indicate very high turbulence intensities in the near-zone of displacement ventilation supply devices, especially close to the floor where high mean flow gradient occurs. This indicates that the air flow from inlet devices designed for displacement ventilation might be very unstable; the position of the stream leaving the diffuser and entering the room is changing with time, hence diffusion of momentum and temperature are increased. This effect is not captured in RANS simulations, since it is performed with the assumption of time-independent conditions. In this paper URANS simulations were performed for prediction of velocity and temperature distribution close to a complex air supply device in a room with displacement ventilation. The presented study show that unsteady simulations with the realizable turbulence k-ε model generates too high eddy viscosity and therefore damps out the unsteadiness of the flow especially inside the diffuser.

  • 147.
    Cehlin, Mathias
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Karimipanah, Taghi
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Larsson, Ulf
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Comparing thermal comfort and air quality performance of two active chilled beam systems in an open-plan office2019Inngår i: Journal of Building Engineering, E-ISSN 2352-7102, Vol. 22, s. 56-65Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 148.
    Cehlin, Mathias
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Larsson, Ulf
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Chen, Huijuan
    RISE Research Institutes of Sweden, Division of Built Environment - Energy and circular economy, Borås, Sweden.
    Numerical investigation of Air Change Effectiveness in an Office Room with Impinging Jet Ventilation2018Inngår i: 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, s. 641-646Konferansepaper (Fagfellevurdert)
    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.

  • 149.
    Cehlin, Mathias
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energiteknik.
    Moshfegh, Bahram
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energiteknik.
    Numerical Modeling of a Complex Diffuser in a Room with Displacement Ventilation2010Inngår i: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 45, nr 10, s. 2240-2252Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A micro/macro-level approach (MMLA) has been proposed which makes it possible for HVAC engineers to easily study the effect of diffuser characteristics and diffuser placement on thermal comfort and indoor air quality. In this article the MMLA has been used to predict the flow and thermal behavior of the air in the near-zone of a complex low-velocity diffuser. A series of experiment has been carried out to validate the numerical predictions in order to ensure that simulations can be used with confidence to predict indoor airflow. The predictions have been performed by means of steady Reynolds Stress Model (RSM) and the results have good agreement both qualitatively and quantitatively with measurements. However, measurements indicated that the diffusion of the velocity and temperature was to some extent under-predicted by the RSM, which might be related to high instability of the airflow close to the diffuser. This effect might be captured by employing unsteady RSM. The present study also shows the importance of detailed inlet supply modeling in the accuracy of indoor air prediction.

  • 150.
    Celander, Sanna
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Att bygga i trä eller lättbetong: en jämförelse mellan väggkonstruktioner2013Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [en]

    Hudiksvall Municipality will build a new preschool. The goal is that the pre-school should reflect the municipality's environmental goals and meet building regulations. The wall structures that are compared in the report is an insulated wooden frame and a frame of lightweight concrete blocks from H + HWall structures are compared within the areas of U-values, air tightness, thermal storage capacity, fire ratings, moisture, durability, emissions and environment. In these categories the two wall structures will be rated in a scale from 1 to 5 and then the categories are weighted against each other. The weighting is based on Hudiksvall Municipality's assessment of the categories importanse for their final selection.The results of the comparison show that the concrete structure is recommended for the construction of pre-school with 27.55 points against the wooden structures 23.70 points. The highest possible score after weighting is 34 points.

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