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  • 1.
    Alvfors, Per
    et al.
    Energiprocesser, Kungliga Tekniska Högskolan, KTH, Stockholm.
    Ellegård, Kajsa
    Linköpings universitet, Institutionen för tema, Tema teknik och social förändring. Linköpings universitet, Filosofiska fakulteten.
    Harvey, Simon
    Energiteknik/Rymd-, geo- och miljövetenskap, Chalmers Tekniska högskola, Göteborg.
    Karlsson, Magnus
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska fakulteten.
    Moshfegh, Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska fakulteten.
    Palm, Jenny
    Linköpings universitet, Institutionen för tema, Tema teknik och social förändring. Linköpings universitet, Filosofiska fakulteten.
    Söderström, Mats
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska fakulteten.
    Widén, Joakim
    Institutionen för teknikvetenskaper, Byggteknik, Uppsala universitet.
    Forskarskolan Program Energisystem: Kunskapsutveckling genom samverkanmellan teknik- och samhällsvetenskap: Slutrapport 2016, Forskningssyntes för konsortiet Byggnader i energisystem2016Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Denna rapport ger en kortfattad översikt och syntes av tvärvetenskapliga forskningsresultat från verksamheten i konsortiet Byggnader i energisystem inom forskarskolan Program Energisystem. Tonvikten ligger på tiden från forskarskolans start 1997 till dess 15-årsjubileum 2012, men hänvisningar görs även till forskning publicerad därefter. Utgångspunkten har varit att lyfta fram det tvärvetenskapliga inom forskningen för att visa hur forskarskolan har bidragit till tvärvetenskaplig kunskaps- och metodutveckling.

    I rapporten ges en översikt över fallstudier och avhandlingar inom konsortiet och de tvärvetenskapliga forskningsresultaten sammanfattas inom tre huvudsakliga tematiska områden: (1) Passivhus: boende och energieffektiva byggnadstekniker,

    (2) Energieffektivisering: processer och aktörer, samt (3) Energianvändning, vardagsaktiviteter och småskalig solenergi i hushåll. Tvärvetenskapliga metoder och resultat sammanfattas och utvecklingen av samarbeten och angreppssätt beskrivs. Rapporten avslutas med några sammanfattande reflektioner kring hur framgångsrik tvärvetenskaplig forskning bör bedrivas.

  • 2.
    Alvfors, Per
    et al.
    Energiprocesser, Kungliga Tekniska Högskolan, KTH, Stockholm.
    Ellegård, Kajsa
    Linköpings universitet, Institutionen för tema, Tema teknik och social förändring. Linköpings universitet, Filosofiska fakulteten.
    Harvey, Simon
    Energiteknik/Rymd-, geo- och miljövetenskap, Chalmers Tekniska högskola, Göteborg.
    Karlsson, Magnus
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska fakulteten.
    Moshfegh, Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska fakulteten.
    Palm, Jenny
    Linköpings universitet, Institutionen för tema, Tema teknik och social förändring. Linköpings universitet, Filosofiska fakulteten.
    Söderström, Mats
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska fakulteten.
    Widén, Joakim
    Institutionen för teknikvetenskaper, Byggteknik, Uppsala universitet.
    Forskarskolan Program Energisystem: Kunskapsutveckling genom samverkanmellan teknik- och samhällsvetenskap: Slutrapport 2016, Forskningssyntes för konsortiet Industriella energisystem2016Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Denna syntesrapport är en sammanfattning och analys av den forskning som bedrivits inom ramen för det Industriella konsortiet från år 1997 (konsortiets verksamhet startade 1999) inom ramen för forskarskolan Program Energisystem. Under denna tid har 25 doktorsavhandlingar och en licentiatavhandling producerats inom det Industriella konsortiet. Avhandlingarna sammanfattas och analyseras i denna syntesrapport och arbetet avgränsas då till att studera avhandlingarnas Problemområde, Verktyg/Metod/Teori, Systemgräns, studerad Sektor och Övergripande resultat. Vidare ges, med utgångspunkt från dessa forskningsresultat, förslag på fortsatt forskning för hållbara och effektiva energisystem.

    Många viktiga problemområden har studerats inom ramen för forskarskolans Industrikonsortium. Ett flertal avhandlingar behandlar möjligheter att minska utsläppen av växthusgaser från industrin och här har flera sektorer studerats, bland annat massa- och pappersindustrin, järn- och stålindustrin, kemiindustrin och oljeraffinaderiindustrin. Ett centralt tema i avhandlingarna är potentialer för energieffektivisering i industrisektorn, inte minst vid införande av bioraffinaderikoncept i framtiden. Här analyseras t.ex. tekniska potentialer, kostnadseffektivitet för energieffektiviseringsåtgärder, samt betydelsen av energiledning och styrmedel.

    I avhandlingarna har en mängd olika metoder och verktyg använts. Den i särklass mest använda vetenskapliga metoden är intervjuer (15) följt av scenarioanalys (10), dokumentstudier (9), simuleringsberäkningar (9), pinchanalys (9) och optimering (8). Fallstudiemetodik där mer än en metod används för att studera ett specifikt fall, t.ex. ett företag, förekommer i flera avhandlingar. En grundtanke i forskarskolan Program Energisystem har varit att forskaren måste vara medveten om att resultat från energisystemanalyser kan påverkas av vilka systemgränser som valts. I flertalet av Industrikonsortiets avhandlingar har Europas elsystem utgjort systemgräns då effekter av förändrad elanvändning eller elproduktion analyserats.

    Industrikonsortiets forskningsresultat visar på många intressanta slutsatser. Det påvisas att det finns energieffektiviseringspotentialer både i nya investeringar och i energiledningsåtgärder, som att justera driftsbetingelser för befintlig teknisk utrustning och ändra beteenden. Det konstateras också att energisamarbeten mellan industri och energibolag med syfte att öka användningen av industriell överskottsvärme i många fall är en hållbar lösning som minskar regioners behov av primärenergi och reducerar utsläppen av växthusgaser. Hinder mot sådana samarbeten kan vara att detta inte är en del av industrins kärnverksamhet. Det konstateras även att energisamarbeten mellan närliggande anläggningar i ett industrikluster kan leda till avsevärt större energieffektiviseringspotentialer än om var och en av de ingående industrierna arbetar enbart med interna åtgärder. Hinder mot denna typ av samarbete är brist på etablerade affärsmodeller. Forskningen visar på ett behov av fortsatta studier kring begreppet kärnverksamhet och dess påverkan på energifrågan i svensk industrin. Avskiljning och lagring av koldioxid (CCS) från industrin har studerats och här konstateras att denna lösning inte är ekonomiskt lönsam med dagens förutsättningar. Det rekommenderas därför att framtida forskning bedrivs för att studera vilka styrmedel som skulle behövas för att CCS ska bli ekonomiskt intressant för industrin. En annan viktig fråga är hur energitjänsteföretag ska formulera affärsmodeller och strategier kring CCS, samt hur de kan samarbeta med industrin för att på affärsmässiga grunder få till stånd CO2– avskiljning, transport och lagring. Även framtida forskning kring styrmedel, t.ex. energitjänster, för ökad energieffektivitet i industrisektorn förordas. Resultat från Industrikonsortiets avhandlingar visar att processintegrationsverktyget pinchanalys kan kombineras med optimeringsverktyg (i detta fall MIND) vid analys av industriella energisystem. Denna metodkombination ger intressanta resultat varför fortsatt forskning förordas kring kombinationer av olika processintegrationsmetoder. I flertalet avhandlingar har företagsdata använts som indata vid exempelvis modellering och processintegrationsstudier. Detta har accentuerat behovet av ett standardiserat protokoll vid insamling av företagsdata. Ett sådant protokoll kan öka reliabiliteten på indata och förslagsvis användas vid fallstudier.

    Avslutningsvis kan konstateras att trots närmare 20 års tvärvetenskaplig forskning mellan samhällsvetare och teknikvetenskaperna finns det fortfarande mycket mer att beforska och utveckla.

  • 3.
    Alvfors, Per
    et al.
    Energiprocesser, Kungliga Tekniska Högskolan, KTH, Stockholm.
    Ellegård, Kajsa
    Linköpings universitet, Institutionen för tema, Tema teknik och social förändring. Linköpings universitet, Filosofiska fakulteten.
    Harvey, Simon
    Energiteknik/Rymd-, geo- och miljövetenskap, Chalmers Tekniska högskola, Göteborg.
    Karlsson, Magnus
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska fakulteten.
    Moshfegh, Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska fakulteten.
    Palm, Jenny
    Linköpings universitet, Institutionen för tema, Tema teknik och social förändring. Linköpings universitet, Filosofiska fakulteten.
    Söderström, Mats
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska fakulteten.
    Widén, Joakim
    Institutionen för teknikvetenskaper, Byggteknik, Uppsala universitet.
    Forskarskolan Program Energisystem: Kunskapsutveckling genom samverkanmellan teknik- och samhällsvetenskap: Slutrapport 2016, Forskningssyntes för konsortiet Lokala och regionala energisystem2016Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Forskarskolan Program Energisystem har med sina fem deltagande forskningsavdelningar från Chalmers tekniska högskola, Linköpings universitet, KTH och Uppsala universitet varit banbrytande inom tvärvetenskaplig energisystemforskning och dess tre konsortier har spelat en viktig roll för forskarskolans utveckling. Konsortierna är inriktade på byggnader i energisystem, industriella energisystem samt lokala och regionala energisystem. I varje konsortium har doktorander och seniorer från minst två av de deltagande avdelningarna bedrivit tvärvetenskaplig forskning.

    I det lokala och regionala konsortiet har forskningsfrågorna kretsat kring aktörer och processer av betydelse för energisystemen i svenska kommuner, län och regioner. Inom konsortiet har frågeställningar om miljömässigt, socialt och ekonomiskt hållbara lokala och regionala energisystem bland annat studerats genom att analysera aktörers agerande och politiska processer inom de tekniska, ekonomiska och institutionella villkor som utgör begränsningar och möjligheter för energisystemen. En tydlig trend inom konsortiets forskning under forskarskolans arton år är att inriktningen gått i riktning från lokal till regional och från stationära till mobila energisystem. Den förskjutningen följer också den ökande betydelse som regioner i form av länsstyrelser har fått för samordningen av energi- och klimatplaneringen i Sverige under det senaste decenniet. Kommunerna har fortfarande en dominerande position genom den energirelaterade infrastruktur som de förfogar över men en förskjutning mot ett mer regionalt inflytande är tydlig.

    Totalt har 26 doktors- och en licentiatexamen avlagts av konsortiets doktorander och dessa alumner är nu verksamma inom energirelaterade verksamheter Sverige. Den främsta representationen finns inom myndigheter och akademier.

  • 4.
    Alvfors, Per
    et al.
    Energiprocesser, Kungliga Tekniska Högskolan, KTH, Stockholm.
    Ellegård, Kajsa
    Linköpings universitet, Institutionen för tema, Tema teknik och social förändring. Linköpings universitet, Filosofiska fakulteten.
    Harvey, Simon
    Energiteknik/Rymd-, geo- och miljövetenskap, Chalmers Tekniska högskola, Göteborg.
    Karlsson, Magnus
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska fakulteten.
    Moshfegh, Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska fakulteten.
    Palm, Jenny
    Linköpings universitet, Institutionen för tema, Tema teknik och social förändring. Linköpings universitet, Filosofiska fakulteten.
    Söderström, Mats
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska fakulteten.
    Widén, Joakim
    Institutionen för teknikvetenskaper, Byggteknik, Uppsala universitet.
    Forskarskolan Program Energisystem: Kunskapsutveckling genom samverkanmellan teknik- och samhällsvetenskap: Slutrapport 2016, Huvudrapport2016Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Idén att samhällsvetenskaplig och teknisk energisystemforskning måste vävas samman för att utveckla ny kunskap och få ökad samhällsnytta var utgångspunkt när Program Energisystem startade år 1997.

    Program Energisystem identifierade tidigt kärnvärden som visades vara viktiga framgångsfaktorer:

    • Energisystem med tyngdpunkt på användarsidan
    • Tvärvetenskaplig, universitets- och fakultetsöverskridande
    • forskning och forskarutbildning
    • Sammanhållen forskarskola
    • Finansiering av hela doktorandprojekt
    • Samarbeten i tematiska forskningsområden
    • Kontinuerlig tvärvetenskaplig utveckling
    • Långsiktig finansiering av samordningsstruktur

    Program Energisystems arbete har kännetecknats av:

    • Val av samhällsrelevanta projekt av hög vetenskaplig kvalitet
    • Gemensamma tvärvetenskapliga kurser och projektarbeten
    • Tvärvetenskaplig handledning
    • Kontinuerligt arbetande fora för diskussion
    • och kontakter över ämnesgränser
    • Forskningssamarbeten mellan seniorer i olika ämnen
    • Aktivt doktorand- och alumninätverk

    Forskarutbildningens målsättning har varit att utbilda bättre samhällsvetare

    och bättre ingenjörer, inte att göra samhällsvetare av ingenjörerna eller ingenjörer

    av samhällsvetarna.

    I den kontinuerliga utvecklingen av Program Energisystem har ett förtroendefullt samarbete utvecklats som möjliggjort kontinuerliga förbättringar av forskningen och forskarutbildningen.

    Arvet från Program Energisystem har förts vidare i den nya Forskarskola Energisystem. Forskarskola Energisystem har en delvis annan struktur men bygger innehållsmässigt vidare på centrala idéer från Program Energisystem. Det finns ett fortsatt stort behov av tvärvetenskaplig kunskapsutveckling på energiområdet som främst handlar om att förstå komplicerade samband och processer och hur dessa kan påverkas.

  • 5.
    Alvfors, Per
    et al.
    Energiprocesser, Kungliga Tekniska Högskolan, KTH, Stockholm.
    Ellegård, Kajsa
    Linköpings universitet, Institutionen för tema, Tema teknik och social förändring. Linköpings universitet, Filosofiska fakulteten.
    Harvey, Simon
    Energiteknik/Rymd-, geo- och miljövetenskap, Chalmers Tekniska högskola, Göteborg.
    Karlsson, Magnus
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska fakulteten.
    Moshfegh, Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska fakulteten.
    Palm, Jenny
    Linköpings universitet, Institutionen för tema, Tema teknik och social förändring. Linköpings universitet, Filosofiska fakulteten.
    Söderström, Mats
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska fakulteten.
    Widén, Joakim
    Institutionen för teknikvetenskaper, Byggteknik, Uppsala universitet.
    Forskarskolan Program Energisystem: Kunskapsutveckling genom samverkanmellan teknik- och samhällsvetenskap: Slutrapport 2016, Publikationer från Program Energisystem2016Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Det finns en omfattande publicering från Program Energisystem. Förutom 78 doktorsavhandlingar och 16 licentiatavhandlingar så har forskarstuderande och seniorer publicerat ytterligare minst 500 publikationer inom ramen för Program Energisystem.

    I denna rapport förtecknas dessa publikationer.

  • 6.
    Amiri, Shahnaz
    et al.
    University of Gävle.
    Moshfegh, Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    Possibilities and consequences of deregulation of the European electricity market for connection of heat sparse areas to district heating systems2010Ingår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 87, nr 7, s. 2401-2410Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The objective of the study is to analyse the conditions for connection of residential buildings in heat sparse areas to district heating systems in order to increase electricity production in municipal combined heat and power plants. The European electricity market has been assumed to be fully deregulated. The relation between connection of heat sparse areas, increased electricity and heat production as well as electricity prices, fuel prices and emissions rights is investigated. The results of the study show that there is potential to expand the district heating market to areas with lower heat concentrations in the cities of Gavle, Sandviken and Borlange in Sweden, with both economic and environmental benefits. The expansion provides a substantial heat demand of approximately 181 GWh/year, which results in an electricity power production of approximately 43 GWh/year. Since the detached and stand-alone houses in the studied heat sparse areas have been heated either by oil boiler or by direct electricity, connection to district heating also provides a substantial reduction in emissions of CO2. The largest reductions in CO2 emissions are found to be 211 ktonnes/year assuming coal-fired condensing power as marginal electricity production. Connection of heat sparse areas to district heating decrease the system costs and provide a profitability by approximately 22 million EURO/year for the studied municipalities if the price of electricity is at a European level, i.e. 110 EURO/MWh. Sensitivity analysis shows, among other things, that a strong relation exists between the price of electricity and the profitability of connecting heat sparse areas to district heating systems.

  • 7.
    Amiri, Shahnaz
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    Trygg, Louise
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    Moshfegh , Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    Assessment of the natural gas potential for heat and power generation in the County of Ostergotland in Sweden2009Ingår i: Energy Policy, ISSN 0301-4215, E-ISSN 1873-6777, Vol. 37, nr 2, s. 496-506Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The aim of this study is to investigate the potential use of natural gas for heat and power production for the municipality of Linkoping, Norrkoping and Finspang in the County of Ostergotland, Sweden.

    The results of the study revealed that these three municipalities with the present heating demand can convert 2030 GWh/year of the present fuel mixed to natural gas. The expansion of natural gas provides the possibility to increase the electricity generation with approximately 800 GWh annually in the County of Ostergotland. The global emissions of CO2 reduce also by approximately 490 ktonne/year by assuming the coal condensing power plant as the marginal power plant. The total system cost decreases by 76 Mkr/year with the present electricity price which varies between 432 and 173 SEK/MWh and with 248 Mkr/year if the present electricity price increases to 37% which is approximately corresponding to European electricity prices.

    Sensitivity analysis is done with respect to the different factors such as price of electricity, natural gas, etc. The findings show that increased price of electricity and increased district heating demand increases the profitability to convert to natural gas using CHP plant.

  • 8. Anton, R
    et al.
    Castiella, M
    Jonsson, H
    Moshfegh, Bahram
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem.
    Smoke and CFD visualization of the flow after an EMC screen in a subrack model2005Ingår i: The Therminic,2005, 2005Konferensbidrag (Refereegranskat)
  • 9.
    Anton, R.
    et al.
    Antón, R., TECNUN, University of Navarra, Navarra 31080, Spain.
    Jonsson, H.
    Royal Institute of Technology, Stockholm SE-10044, Sweden, Department of Energy Technology, Stockholm 10044, Sweden.
    Moshfegh, Bahram
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem.
    Compact CFD modeling of EMC screen for radio base stations: A porous media approach and a correlation for the directional loss coefficients2007Ingår i: IEEE transactions on components and packaging technologies (Print), ISSN 1521-3331, E-ISSN 1557-9972, Vol. 30, nr 4, s. 875-885Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A methodology to obtain the directional pressure loss coefficients in a porous media model of an electromagnetically compatible screen of a radio base station model is presented. The directional loss coefficients of this compact model are validated against a detailed computational fluid dynamics model not only by comparing the total pressure drop, but also by evaluating the flow pattern after the screen. The detailed model was validated in an earlier article by the authors. A parametric study is conducted for 174 cases. Seven parameters were investigated: velocity, inlet height, screen porosity, printed circuit board (PCB) thickness, inlet-screen gap, distance between two PCBs and screen thickness. Based on the compact model parametric study, two correlations for the directional loss coefficients are developed as a function of the Reynolds number and the above geometrical parameters. The average disagreement between the compact model that uses the directional loss coefficients from the correlations and the detailed model was of 3% for the prediction of the total pressure drop and less than 6.5% and 9.5% for two coefficients that accurately characterize the flow pattern. © 2007 IEEE.

  • 10.
    Anton, R.
    et al.
    Antón, R., Department of TECNUN, University of Navarra, Navarra 31080, Spain.
    Jonsson, H.
    Royal Institute of Technology, Stockholm, SE-100 44, Sweden, Deparment of Energy Technology, Stockholm SE-100 44, Sweden.
    Moshfegh, Bahram
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem.
    Detailed CFD modeling of EMC screen for radio base stations: A benchmark study2007Ingår i: IEEE transactions on components and packaging technologies (Print), ISSN 1521-3331, E-ISSN 1557-9972, Vol. 30, nr 4, s. 754-763Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The objective of this paper is to investigate the performance of five well-known turbulence models, in order to find a model that predicts the details of the flow patterns through an electromagnetic compatibility (EMC) screen. The turbulence models investigated in the present study are five different eddy-viscosity models, the standard k-e model, the renormalization group (RNG) k-e model, the realizable k-e model, the standard k-? model, as well as the shear stress transport k-? model. A steady-state 3-D detailed model, which serves as the most accurate representation of the model, was used in order to evaluate the details of the airflow paths and pressure field. The flow was assumed to be isothermal, turbulent and incompressible. A general model that covers a considerable range of velocities and geometries was validated experimentally by wind tunnel measurements. The result shows that for most of the k-e models used with correct y+ and mesh strategy, the pressure drop and the velocity field deviation is small compared to experimental data. The k-? models overpredict the overall pressure drop. When using the RNG k-e model, the total static pressure drop predicted differs around 5%-10% and the average velocity deviation at several locations before and after the screen is around 5%. © 2007 IEEE.

  • 11. Antón, R
    et al.
    Jonsson, H
    Moshfegh, Bahram
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem.
    Detail CFD modelling of EMC Screens for Radio Base Stations, a conjugate Heat Transfer Problem2007Ingår i: International journal of heat exchangers, ISSN 1524-5608, Vol. VIII, s. 95-116Artikel i tidskrift (Refereegranskat)
  • 12.
    Broström, Tor
    et al.
    Uppsala University, Sweden .
    Eriksson, Petra
    Uppsala University, Sweden .
    Liu, Linn
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    Rohdin, Patrik
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    Ståhl, Fredrik
    SP Technical Research Institute of Sweden.
    Moshfegh, Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    A Method to Assess the Potential for and Consequences of Energy Retrofits in Swedish Historic Buildings2014Ingår i: The Historic Environment: Policy & Practice, ISSN 1756-7505, E-ISSN 1756-7513, Vol. 5, nr 2, s. 150-166Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Swedish research project Potential and Policies for Energy Efficiency in Swedish Historic Buildings aims to investigate the interdependency between political energy targets and effects on the built heritage. The first part of this paper presents an iterative and interactive method to assess the potential for and consequences of improving the energy performance in a stock of historic buildings. Key elements in the method are: categorisation of the building stock, identifying targets, assessment of measures, and life-cycle cost optimisation. In the second part of the paper, the method is applied to a typical Swedish building. The selected case study shows how the method allows for an interaction between the quantitative assessment of the techno-economic optimisation and the qualitative assessment of vulnerability and other risks. Through a multidisciplinary dialogue and iteration it is possible to arrive at a solution that best balances energy conservation and building conservation in a given decision context.

  • 13. Buchanan, M
    et al.
    Aas, G M
    Moshfegh, Bahram
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem.
    Enchancing efficiency in PV systems: A New Solar Cooling Module2007Ingår i: Solar Energy applications,2007, 2007Konferensbidrag (Refereegranskat)
  • 14.
    Carlander, Jakob
    et al.
    University of Gävle, Gävle, Sweden.
    Trygg, Kristina
    Linköpings universitet, Institutionen för tema, Tema teknik och social förändring. Linköpings universitet, Filosofiska fakulteten.
    Moshfegh, Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska fakulteten.
    Integration of Measurements and Time Diaries as Complementary Measures to Improve Resolution of BES2019Ingår i: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, nr 11, s. 1-29, artikel-id 2072Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Building energy simulation (BES) models rely on a variety of different input data, and the more accurate the input data are, the more accurate the model will be in predicting energy use. The objective of this paper is to show a method for obtaining higher accuracy in building energy simulations of existing buildings by combining time diaries with data from logged measurements, and also to show that more variety is needed in template values of user input data in different kinds of buildings. The case studied in this article is a retirement home in Linköping, Sweden. Results from time diaries and interviews were combined with logged measurements of electricity, temperature, and CO2 levels to create detailed occupant behavior schedules for use in BES models. Two BES models were compared, one with highly detailed schedules of occupancy, electricity use, and airing, and one using standardized input data of occupant behavior. The largest differences between the models could be seen in energy losses due to airing and in household electricity use, where the one with standardized user input data had a higher amount of electricity use and less losses due to airing of 39% and 99%, respectively. Time diaries and interviews, together with logged measurements, can be great tools to detect behavior that affects energy use in buildings. They can also be used to create detailed schedules and behavioral models, and to help develop standardized user input data for more types of buildings. This will help improve the accuracy of BES models so the energy efficiency gap can be reduced.

  • 15.
    Cehlin, M.
    et al.
    University of Gävle.
    Moshfegh, Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    Numerical modeling of a complex diffuser in a room with displacement ventilation2010Ingår i: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 45, nr 10, s. 2240-2252Artikel i tidskrift (Refereegranskat)
    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.

  • 16. Cehlin, M
    et al.
    Moshfegh, Bahram
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem.
    Karlsson, Fredrik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem.
    Larsson, Ulf
    Högskolan i Gävle .
    Analysis on Comfort and Indoor Climate for a Hospital Building by Multizone Modeling2008Ingår i: Analysis on Comfort and Indoor Climate for a Hospital Building by Mujltizone Modeling,2008, 2008Konferensbidrag (Refereegranskat)
  • 17.
    Cehlin, Mattias
    et al.
    Högskolan i Gävle.
    Moshfegh, Bahram
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem.
    Visualization of isothermal low-Reynolds circular air jet using computed tomography2005Ingår i: 6th World Conference on Experimental Heat Transfer, Fluid Mechanics, and Thermodynamics,2005, 2005Konferensbidrag (Refereegranskat)
  • 18.
    Chen, Huijuan
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan. Department of Building, Energy and Environmental Engineering, University of Gävle, Sweden.
    Janbakhsh, Setareh
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling. Linköpings universitet, Tekniska högskolan. Department of Building, Energy and Environmental Engineering, University of Gävle, Sweden.
    Larsson, Ulf
    Department of Building, Energy and Environmental Engineering, University of Gävle, Sweden.
    Moshfegh, Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan. Department of Building, Energy and Environmental Engineering, University of Gävle, Sweden.
    Numerical investigation of ventilation performance of different air supply devices in an office environment2015Ingår i: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 90, s. 37-50Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 19.
    Chen, Huijuan
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    Moshfegh, Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    Comparing k-ε Models On Predictions Of An Impinging Jet For Ventilation Of An Office Room2011Ingår i: Proceedings of Roomvent 2011, 11th International Conference on Air Distribution in Rooms 19 - 22 June 2011 Torendheim, Norway, 2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    The objective of this study is to compare the performance of different k-ε models, i.e. the Standard k-ε, the Renormalization Group (RNG) k-ε, and the Realizable k-ε, with a two-layer model for the prediction of the mean velocity field and the temperature pattern from a newly designed impinging jet supply device for ventilation of an office room. The numerical predictions are validated against the detailed experimental measurements. The experimental investigation was performed in a test room with the dimensions 4.2×3.6×2.5 m, as a mock-up of a single-person office. Detailed velocity and temperature field measurements including the comfort zone and the jet developing region along the floor were carried out. The in-house made single-sensor hot-wire probe and the thermocouple are measuring instruments used to investigate the mean velocity, turbulence intensity and temperature. The boundary conditions for Computational Fluid Dynamics (CFD) study are obtained from the same set-up measurement. The results mainly consist of the flow field presentation, i.e., the velocity and temperature profiles in the comfort zone and the jet developing region along the floor. The comparisons between the results from the three versions of the k-ε models and measurements show generally satisfactory agreement, and better consistency is observed at the free jet region and the wall jet region that farther from the impingement zone. Among the three tested turbulence models, RNG shows the best overall performance.

  • 20.
    Chen, Huijuan
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    Moshfegh, Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    Cehlin, Mathias
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    Computational investigation on the factors influencing thermal comfort for impinging jet ventilation2013Ingår i: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 66, s. 29-41Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Impinging jet ventilation (IJV) has been proposed to achieve an effective ventilation of an occupied zone in office and industrial buildings. For IJV systems, draught discomfort is the issue of most concern since it supplies cooled air directly to the occupied zone. This study investigated a number of factors influencing draught discomfort and temperature stratification in an office environment equipped with IJV. The factors considered were: shape of air supply device, discharge height, supply airflow rate and supply air temperature. The Response Surface Methodology (RSM) was used to identify the level of the significance of the parameters studied, as well as to develop the predictive models for the local thermal discomfort. Computational fluid dynamics (CFD) was employed to perform a set of required studies, and each simulation condition was determined by the Box – Behnken design (BBD) method. The results indicated that at a low discharge height, the shape of air supply device had a major impact on the flow pattern in the vicinity of the supply device because of the footprint from impinging jet, which consequently affected the draught risk level in the occupied zone. A square-shaped air supply device was found to result in lower overall draught discomfort than rectangular and semi-elliptic shapes. The RSM analysis revealed that the supply airflow rate had a significant impact on the draught discomfort, while the shape of air supply device and discharge height had moderate effects. The temperature stratification in the occupied zone was mostly influenced by the supply air temperature within the range studied.

  • 21.
    Chen, Huijuan
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    Moshfegh, Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    Cehlin, Mathias
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Numerical investigation of the flow behavior of an isothermal impinging jet in a room2012Ingår i: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 49, s. 154-166Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The impinging jet concept has been proposed as a new ventilation strategy for use in office and industrial buildings. The present paper reports the mean flow field behavior of an isothermal turbulent impinging jet in a room. The detailed experimental study is carried out to validate the numerical simulations, and the predictions are performed by means of the RNG k-ε and SST k-ω model. The comparisons between the predictive results and the experimental data reveal that both of the tested turbulence models are capable of capturing the main qualitative flow features satisfactorily. It is found that the predictions from the RNG k-ε model predicts slightly better of the maximum velocity decay as jet approaching the floor, while the SST k-ω model accords slightly better in the region close to the impingement zone.

    Another important perspective of this study is to investigate the influence of different flow and configuration parameters such as jet discharge height, diffuser geometry, supply airflow rate and confinement from the surrounding environment on the impinging jet flow field with the validated model. The obtained data are presented in terms of the jet dimensionless velocity distribution, maximum velocity decay and spreading rate along the centerline of the floor. The comparative results demonstrate that all the investigated parameters have certain effects on the studied flow features, and the diffuser geometry is found to have the most appreciable impact, while the supply airflow rate is found to have marginal influence within the moderate flow range. 

  • 22.
    Chen, Huijuan
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan. Department of Building, Energy and Environmental Engineering, Faculty of Engineering and Sustainable Development, University of Gävle, Gävle, Sweden.
    Moshfegh, Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan. Department of Building, Energy and Environmental Engineering, Faculty of Engineering and Sustainable Development, University of Gävle, Gävle, Sweden.
    Cehlin, Mattias
    Department of Building, Energy and Environmental Engineering, Faculty of Engineering and Sustainable Development, University of Gävle, Gävle, Sweden.
    Investigation on the flow and thermal behavior of impinging jet ventilation systems in an office with different heat loads2013Ingår i: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 59, s. 127-144Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents the flow and temperature field within an office using impinging jet ventilation (IJV) under different heat loads ranging from 17 to 65 W per square meter floor area. The measurement was carried out in a full-scale test room to verify the reliability of three turbulence models, i.e., the RNG k-epsilon, SST k-omega and (nu(2)) over bar - f models. It is found that all the tested models show good agreements with measurements, while the (nu(2)) over bar - f model shows the best performance, especially on the overall temperature prediction. less thanbrgreater than less thanbrgreater thanThe (nu(2)) over bar - f model is used further to investigate a number of important factors influencing the performance of the IJV. The considered parameters are: cooling effect of chilled ceiling, external heat load as well as its position, number of occupants and supplied air conditions. The interaction effect of chilled ceiling and heat sources results in a complex flow phenomenon but with a notable feature of air circulation. The appearance and strength of the air circulation mainly depends on the external heat load on window and number of occupants. It is found that with higher external heat load on window (384 W and 526 W), the air circulation has a strong tendency towards the side wall in the opposite direction to occupant, while with lower power on window (200 W) the air circulation has a strong tendency in the center of the room and extends to a larger area. When two occupants are present, two swirling zones are formed in the upper region. The effects of air circulation consequently alter the temperature field and the level of local thermal comfort.

  • 23.
    Gebremedhin, Alemayehu
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för konstruktions- och produktionsteknik, Energisystem.
    Moshfegh, Bahram
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för konstruktions- och produktionsteknik, Energisystem.
    Modelling and optimization of district heating and industrial energy system - An approach to a locally deregulated heat market2004Ingår i: International journal of energy research (Print), ISSN 0363-907X, E-ISSN 1099-114X, Vol. 28, nr 5, s. 411-422Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Regions with densely concentration of industries and district heating systems (DHS) could be interesting study object from the light of an integrated heat market on local basis. System analysis with a widened system boundary could be used as an approach to evaluate the benefit of an integrated heat supply system. In this study, an energy system model consisting of totally seven different participants is designed and the optimization results of the system analysis are presented. With applied data and assumptions, the study shows that a significant amount of the heat demand within two sub-systems can be covered by heat supply from the heat market (the entire heat comes from two industries). Shadow prices, which can be used for heat pricing, indicate the advantage of an integrated system. The system cost reduction through integration and the availability of several actors with diverse energy supply system, makes the region under study an interesting area to prove a locally deregulated heat market.

  • 24.
    Ghahremanian, Shahriar
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan. University of Gävle.
    Moshfegh, Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    A study on proximal region of low Reynolds confluent jets Part I: Evaluation of turbulence models in prediction of inlet boundary conditions2014Ingår i: ASHRAE Transactions 2014: ASHRAE Winter Conference, January 18-22, 2014, New York, New York. Pt. 1., New York: ASHRAE , 2014, Vol. 120, nr Part 1, NY-14-021, s. 256-270Konferensbidrag (Refereegranskat)
    Abstract [en]

    Conventional ventilation systems (mixing and displacement) produce low air quality in industrial premises.A newair supply system (confluent jets system) may improve the ventilation efficiency and the energy efficiency. When round jets issue from co-planar nozzles with enough spacing, they converge, merge, and combine at certain downstream distances, which are called confluent jets. In order to numerically predict confluent jets, it is crucial to provide inlet boundary conditions for these jets at the nozzles’ exit. Numerical prediction of inlet boundary conditions of confluent jets was chosen due to two reasons: the difficulty of measurement at the nozzles’ exit, and lack of information about the shape of the employed nozzles to make artificial inlet profiles. Numerical predictions by two turbulence models (Realizable k –and RSM) of the supply device producing the confluent jets was verified by hot-wire measurements at 0.26 d0 downstream of the nozzles’ exit in both lateral and vertical direction. The verification was carried out for different nozzles in an array by measuring axial velocity and its turbulence intensity. The axial velocity profile at the nozzles exit has a saddle-back shape with two distinct off-centered overshoots. The convergence of the velocity profile shows the existence ofVena contracta phenomena. Low turbulence intensity at the central part of nozzles was found with narrow shear layer upstream of confluent jet flow. Differences of velocity components, turbulent kinetic energy (TKE), and turbulent dissipation rate (TDR) of the studied contraction nozzle were examined with a flow issuing from a typical long pipe. Reynolds number dependency in the studied range has been carried out and Re effects were observed on TKE but not on TDR.

  • 25.
    Ghahremanian, Shahriar
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan. University of Gävle.
    Moshfegh, Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    A study on proximal region of low Reynolds confluent jets Part II: Numerical verification of the flow field2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    Conventional ventilation systems (mixing and displacement) produce low air quality in industrial premises.A new air supply system (confluent jet system) may improve both ventilation and energy efficiency. When round jets are issued from coplanar nozzles with enough spacing, they converge, merge, and combine at a certain downstream distance, which are called “confluent jets.” In this study, the velocity field of the proximal region of confluent jets was recorded by traversing a hot-wire probe across the jets in one column at selected distances from the nozzles’ exit in order to examine the performance of SST turbulence model. The experimental and numerical results from this work are summarized in a set of mapping fields of mean velocity for the confluent jet zones, which are presented in a generalized non-dimensional form. The existence of an initial, a converging, a merging, and a combined region in the confluent jets has been found for three low Reynolds numbers. Three different confluent jets can be seen in the array of jets studied placed six by six symmetrically on the long side of a cylindrical supply device. The streamwise velocity of the geometrical centerline of side jets and corner jets decays faster than that for the fully confluent jets, due to deflection towards their adjacent neighboring jets. Side jets and corner jets deflect to their adjacent jets and finally merge and combine with them, while fully confluent jets normally spread and amalgamate with each other. Low local pressure is responsible for the amalgamation of confluent jets, but the static pressure reaches a minimum value between side jets and their neighboring jets, which results in the deflection of the side jets.

  • 26.
    Ghahremanian, Shahriar
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan. University of Gävle.
    Moshfegh, Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    Evaluation of RANS Models in Predicting Low Reynolds, Free, Turbulent Round Jet2014Ingår i: Journal of Fluids Engineering - Trancactions of The ASME, ISSN 0098-2202, E-ISSN 1528-901X, Vol. 136, nr 1, s. 011201-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In order to study the flow behavior of multiple jets, numerical prediction of the three-dimensional domain of round jets from the nozzle edge up to the turbulent region is essential. The previous numerical studies on the round jet are limited to either two-dimensional investigation with Reynolds-averaged Navier-Stokes (RANS) models or three-dimensional prediction with higher turbulence models such as large eddy simulation (LES) or direct numerical simulation (DNS). The present study tries to evaluate different RANS turbulence models in the three-dimensional simulation of the whole domain of an isothermal, low Re (Re = 2125, 3461, and 4555), free, turbulent round jet. For this evaluation the simulation results from two two-equation (low Re k - epsilon and low Re shear stress transport (SST) k - omega), a transition three-equation (k - kl - omega), and a transition four-equation (SST) eddy-viscosity turbulence models are compared with hot-wire anemometry measurements. Due to the importance of providing correct inlet boundary conditions, the inlet velocity profile, the turbulent kinetic energy (k), and its specific dissipation rate (omega) at the nozzle exit have been employed from an earlier verified numerical simulation. Two-equation RANS models with low Reynolds correction can predict the whole domain (initial, transition, and fully developed regions) of the round jet with prescribed inlet boundary conditions. The transition models could only reach to a good agreement with the measured mean axial velocities and its rms in the initial region. It worth mentioning that the round jet anomaly is still present in the turbulent region of the round jet predicted by the low Re k - epsilon. By comparing the k and the omega predicted by different turbulence models, the blending functions in the cross-diffusion term is found one of the reasons behind the more consistent prediction by the low Re SST k - omega.

  • 27.
    Ghahremanian, Shahriar
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan. University of Gävle, Sweden.
    Moshfegh, Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan. University of Gävle, Sweden.
    Investigation in the near-field of a row of interacting jets2015Ingår i: Journal of Fluids Engineering - Trancactions of The ASME, ISSN 0098-2202, E-ISSN 1528-901X, Vol. 137, nr 12Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Multiple interacting jets (confluent jets) are employed in many engineering applications, and the significant design factors must be investigated. Computational fluid dynamics (CFD) is used to numerically predict the flow field in the proximal region of a single row of round jets. The numerical results that are obtained when using the low Reynolds kε are validated with the experimental data that is acquired by particle image velocimetry (PIV). The low Reynolds kε underpredicts the streamwise velocity in the onset of the jets’ decay. The characteristic points are determined for various regions between two neighboring jets. The comparison of the merging point and the combined point computed from measurements and simulations shows good agreement in the different regions between the jets. In this study, a computational parametric study is also conducted to determine the main effects of three design factors and the interactions between them on the flow field development using response surface methodology. The influences of the inlet velocity, the spacing between the nozzles and the diameter of the nozzles on the locations of the characteristic points are presented in the form of correlations (regression equations). CFD is used to numerically predict the characteristic points for a set of required studies, for which the design values of the simulation cases are determined by the Box-Behnken method. The results indicate that the spacing between the nozzles has a major impact on the flow characteristics in the near-field region of multiple interacting jets. The response surface methodology shows that the inlet velocity has a marginal effect on the merging and combined points.

  • 28.
    Ghahremanian, Shahriar
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan. University of Gävle, Sweden.
    Svensson, Klas
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    Tummers, Mark J.
    Delft University of Technology, The Netherlands.
    Moshfegh, Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan. University of Gävle, Sweden.
    Near-field development of a row of round jets at low Reynolds numbers2014Ingår i: Experiments in Fluids, ISSN 0723-4864, E-ISSN 1432-1114, Vol. 55, nr 8, s. 1789-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This article reports on an experimental investigation of the near-field behavior of interacting jets at low Reynolds numbers (Re = 2125, 3290 and 4555). Two measurement techniques, particle image velocimetry (PIV) and laser Doppler anemometry (LDA), were employed to measure mean velocity and turbulence statistics in the near field of a row of six parallel coplanar round jets with equidistant spacing. The overall results from PIV and LDA measurements show good agreement, although LDA enabled more accurate measurements in the thin shear layers very close to the nozzle exit. The evolution of all six coplanar jets showed initial, merging, and combined regions. While the length of the potential core and the maximum velocity in the merging region are Reynolds number-dependent, the location of the merging points and the minimum velocity between jets were found to be independent of Reynolds number. Side jets at the edges of the coplanar row showed a constant decay rate of maximum velocity after their core region, which is comparable to a single round jet. Jets closer to the center of the row showed reducing velocity decay in the merging region, which led to a higher maximum velocity compared to a single round jet. A comparison with the flow for an in-line array of 6 × 6 round jets showed that the inward bending of streamwise velocity, which exists in the near field of the 6 × 6 jet array, does not occur in the single row of coplanar jets, although both setups have identical nozzle shape, spacing, and Reynolds number.

  • 29.
    Ghahremanian, Shahriar
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan. University of Gävle, Sweden.
    Svensson, Klas
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    Tummers, Mark J.
    Delft University of Technology, The Netherlands.
    Moshfegh, Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan. University of Gävle, Sweden.
    Near-field mixing of jets issuing from an array of round nozzles2014Ingår i: International Journal of Heat and Fluid Flow, ISSN 0142-727X, E-ISSN 1879-2278, Vol. 47, s. 84-100Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This article presents results of an experimental study of the confluence of low Reynolds number jets inthe near field of a 6 6 in-line array of round nozzles. Particle Image Velocimetry (PIV) and Laser DopplerAnemometry (LDA) were employed to measure mean velocities and turbulence statistics. The comparisonof the results from PIV and LDA measurements along different cross-sectional profiles and geometricalcenterlines showed good agreement. However, LDA enabled more accurate results very close to the nozzleexits. The evolution of all the individual jets in the array into a single jet showed flow regions similarto twin jets (i.e., initial, converging including mixing transition, merging and combined regions). The lateraldisplacements play an important role for a confluent jet, where all jets to some degree are deflectedtowards the center of the nozzle plate. The jet development in terms of velocity decay, length of potentialcore and lateral displacement varies significantly with the position of the jet in the array. A comparisonwith single jet and twin jets flow showed considerable differences in velocity decay as well as locationand velocity in the combined point. The flow field of confluent jets showed asymmetrical distributionsof Reynolds stresses around the axis of the jets and highly anisotropic turbulence. Additionally, the lateraldisplacement as well as the turbulence development in the proximal region of the studied confluent jetwas shown to be dependent on Reynolds number.

  • 30.
    Govik, Alexander
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    Nilsson, Larsgunnar
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    Moshfegh, Ramin
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    Stochastic analysis of a sheet metal assembly considering its manufacturing process2014Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    In order to accurately predict the mechanical properties of a sheet metal assembly it has been shown important to account for how the geometry and material properties are affected by the manufacturing process. It is also of a great interest to predict the variations of important responses, and how these variations depend on the manufacturing process.

    In this study, the variation of properties during the multi-stage manufacturing process of a sheet metal assembly is evaluated and the variability of a response due to loading is studied. A methodology to investigate how variations evolve during the assembling process is presented. The multi-stage assembling process is virtually segmented, such that stochastic analyses of each process stage are performed and coupled to succeeding stages in order to predict the variation in properties of the final assembly. The methodology is applied to an industrial assembly and experimental validations have been conducted. The prediction of the geometry of the final assembly is in good agreement with the experimental results, while the prediction of the variation of this geometry is in fair agreement.

  • 31.
    Janbakhsh, Setareh
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling. Linköpings universitet, Tekniska högskolan. University of Gävle, Department of Technology and Built Environment, Division of Energy and Mechanical Engineering.
    Moshfegh, Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    Experimental investigation of a new supply diffuser in an office room2009Ingår i: Proceedings of 11th International Conference on Air Distribution in Rooms. ROOMVENT, 2009,Busan, Korea, 2009Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Full-scale measurements were carried out for investigation of thermal comfort in an office room for a new supply air diffuser. Results of the measurements were performed with both wholefield measuring and traditional point measuring techniques. Experimental results were carried out for supply Archimedes numbers varying from 0.03 to 0.16 and two cooling loads, i.e. 55 and 70 W/m2. Characteristics of indoor environment and occupants’ comfort were explored and analyzed. It was concluded that the airflow pattern and thermal comfort from the investigated low-velocity diffuser were in good agreement with standard ISO 7730.

  • 32.
    Janbakhsh, Setareh
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling. Linköpings universitet, Tekniska högskolan.
    Moshfegh, Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    Experimental investigation of a ventilation system based on wall confluent jets2014Ingår i: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 80, s. 18-31Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The flow behavior of isothermal and non-isothermal wall confluent jets (WCJ) ventilation system was investigated experimentally in a mock-up office environment. Two flow regions were identified: first, a primary region is developed below the supply device, with axis along the inlet wall, and a secondary wall-jet forms along the floor. The velocity and temperature fields were recorded by traversing a hot wire and thermistor anemometers for both primary and secondary regions. The results show self-similarity characteristic of the velocity and temperature profiles for both isothermal and non-isothermal WCJ. Maximum velocity decay and its spreading rate are linear and independent of the inlet airflow rate. Minimum temperature difference and its spread also show linear decay. The spreading rates for maximum velocity are similar in both the primary and secondary regions normal to the inlet wall and floor, respectively, which is consistent with previous studies on wall jets. The variation of draught rating is evaluated via mean velocity, turbulence intensity and temperature. Although the WCJ has slow velocity decay, which enables it to cover almost the entire floor of the test room, the draught is acceptable in the occupied zone according to ISO 7730. PMV (predicted mean vote) and PPD (predicted percentage dissatisfied) are presented for the occupied zone of the room.

  • 33.
    Janbakhsh, Setareh
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling. Linköpings universitet, Tekniska högskolan. Department of Building, Energy and Environmental Engineering, University of Gävle, Sweden.
    Moshfegh, Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    Investigation of design parameters for an air supply device based on wall confluent jets2015Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Numerical predictions of the flow field generated by an air supply device based on wall confluent jets are investigated. The numerical predictions of three turbulence models (RNG 𝑘 − 𝜀, Re 𝑘 − 𝜀, and SST 𝑘 − 𝜔) are compared by velocity and temperature measurements. Ventilation performance in terms of thermal comfort and ventilation efficiency is numerically investigated by systematically varying the design of the air supply (nozzle array configuration, nozzle diameter, number of nozzles, and inlet discharge height). The numerical predictions accomplished by the SST 𝑘 − 𝜔 model provide the best agreement with the experimental results. The numerical predictions for supply devices of varying design configuration show that different device designs provide acceptable thermal environments and efficient heat removal. The nozzle diameter and number of nozzles play important roles in determining the airflow pattern, temperature field, and draught distribution. Increased temperature stratification and less draught distribution are achieved by increasing the nozzle diameter and number of nozzles. The spreading rates of the wall jet along the vertical direction for the cases studied are in close agreement with each other and independent of the studied parameters. The flow behavior is rarely independent of the inlet discharge height and configuration of the nozzle array for the studied range.

  • 34.
    Janbakhsh, Setareh
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling. Linköpings universitet, Tekniska högskolan.
    Moshfegh, Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    Numerical study of a ventilation system based on wall confluent jets2014Ingår i: HVAC & R RESEARCH, ISSN 1078-9669, E-ISSN 1938-5587, Vol. 20, nr 8, s. 846-861Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study presents numerical investigation of an air supply device based on wall confluent jets in a ventilated room. Confluent jets can be described as multiple round jets issuing from supply device apertures. The jets converge, merge, and combine at a certain distance downstream from the supply device and behave as a united jet, or so-called confluent jet. The numerical predictions of the velocity flow field of isothermal confluent jets with three Reynolds-averaged Navier-Stokes turbulence models (renormalization group k-epsilon, realizable k-epsilon, and shear stress transport k-omega) are reported in the present study. The results of the numerical predictions are verified with detailed experimental measurements by a hot wire anemometer and constant temperature anemometers for two airflow rates. The box method is used to provide the inlet boundary conditions. The study of the airflow distribution shows that a primary wall jet (wall confluent jet) exists close to the supply device along the wetted wall, and a secondary wall jet is created after the stagnation region along the floor. It is presented that the flow field of the primary and secondary wall jet predicted by turbulence models is in good agreement with the experimental data. The current study is also compared with the literature in terms of velocity decay and the spreading rate of the primary and secondary wall jet, the results of which are consistent with each other. Velocity decay and the spreading rate of the secondary wall jet in vertical and lateral directions were studied for different inlet airflow rates and inlet discharge heights. The comparative results demonstrate that the flow behavior is nearly independent of the inlet flow rate. Inlet discharge height is found to have impact close to the inlet, where the velocity decays faster when the jet discharges at higher level. The decay tendency is similar as the jet enters into the room for all discharge heights.

  • 35.
    Janbakhsh, Setareh
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan. University of Gävle, Department of Technology and Built Environment, Division of Energy and Mechanical Engineerin.
    Moshfegh, Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan. University of Gävle, Department of Technology and Built Environment, Division of Energy and Mechanical Engineerin.
    Ghahremanian, Shahriar
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling. Linköpings universitet, Tekniska högskolan. University of Gävle, Department of Technology and Built Environment, Division of Energy and Mechanical Engineerin.
    A Newly Designed Supply Diffuser for Industrial Premises2010Ingår i: The International Journal of Ventilation, ISSN 1473-3315, E-ISSN 2044-4044, Vol. 9, nr 1, s. 59-67Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The results of this investigation revealed the airflow distribution from a new design of supply diffuser under non-isothermal conditions. To illustrate the indoor climate parameters in the occupied zone, for both the heating and cooling seasons, an experimental investigation was carried out in industrial premises. The indoor climate was explored at ankle, waist and neck levels for a standing person at different positions, to determine the variation of the thermal comfort indexes and draught rating (DR) with position in the facility. The observed PPD and DR values indicate acceptable levels of thermal comfort in the facility for both summer and winter cases. The conclusion can be drawn that well-distributed airflow saves energy by removing the need for an additional heating and cooling systems during cold and hot weather seasons.

  • 36.
    Johansson, Per-Erik
    et al.
    DynaMate Industrial Services AB, Stockholm, Sweden.
    Thollander, Patrik
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    Moshfegh, Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    Towards increased energy efficiency in industry – a manager’s perspective2011Ingår i: Proceedings of the World Renewable Energy Congress 2011 (WREC 2011), 9-13 May, Linköping., Linköping University Electronic Press, 2011, Vol. 7, s. 1644-1651Konferensbidrag (Refereegranskat)
    Abstract [en]

    Industry is one of the major users of fossils fuels resulting in emissions of GHG (Green House Gases), leading to global climate change. One means of promoting energy efficiency in industry is energy management. The aim of this paper is to outline a number of energy management related factors which affects energy management in industry positively. The paper is a result of collaboration between industry professionals and researchers within an ongoing research project and addresses the issue using a bottom-up energy management perspective. Results indicate that that the “soft” issues of energy management play a crucial role in the success (or not) of energy management in industry, e.g. the manager’s role and attitude towards the employees cannot be understated. Instead it addresses that implementation is not only about technology but equally or even more important, concerns the diffusion and adoption of energy management practices and principals.

  • 37.
    Joudi, Ali
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska fakulteten. Energy and Environmental Technology, Dalarna University, Falun, Sweden.
    Cehlin, Mathias
    Building, Energy & Environmental Engineering, University of Gävle, Gävle, Sweden.
    Svedung, Harald
    SSAB Europe, Borlänge, Sweden.
    Rohdin, Patrik
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska fakulteten.
    Moshfegh, Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska fakulteten.
    Influence of reflective interior surfaces on indoor thermal environment and energy use using a coupling model for energy simulation and CFD2015Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    The importance of reducing the building energy use and maintaining the desired indoor climate has long inspired creative solution such as optimized optical properties for building surfaces. This paper aims to address the influence of interior thermal reflective surfaces on both indoor thermal environments with high spatial resolution and energy use. To do so, this work employs a coupling method using building energy simulation (BES) and computational fluid dynamics (CFD). The results indicate increase in the mean radiation temperature (MRT) and reduction in the floor heating energy use by the use of interior reflective surfaces. The study yields analysis of operative temperatures and interior surface heat fluxes. Overall, the interior reflective surfaces can contribute to improved building thermal performance and energy saving.

  • 38.
    Joudi, Ali
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska fakulteten. Energy Technology, Dalarna University, Falun, Sweden; SSAB Europe, Borlänge, Sweden.
    Cehlin, Mathias
    Building, Energy & Environmental Engineering, University of Gävle, Gävle, Sweden .
    Svedung, Harald
    Energy Technology, Dalarna University, Falun, Sweden; SSAB Europe, Borlänge, Sweden.
    Rönnelid, Mats
    Energy Technology, Dalarna University, Falun, Sweden .
    Moshfegh, Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska fakulteten. Building, Energy & Environmental Engineering, University of Gävle, Gävle, Sweden .
    Numerical and experimental investigation of the influence of infrared reflective interior surfaces on building temperature distributions2017Ingår i: Indoor + Built Environment, ISSN 1420-326X, E-ISSN 1423-0070, Vol. 26, nr 3, s. 355-367Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Radiative properties of interior surfaces can affect not only the building heat flux but also the indoor environment, the latter of which has not been thoroughly investigated. The aim of this study is to analyse the effect of surface emissivity on indoor air and surface temperature distributions in a test cabin with reflective interior surfaces. This was done by comparing experimental and simulation data of the test cabin with that of a normal cabin. This study employs transient computational fluid dynamics (CFD) using re-normalisation group (RNG) kε model, surface-to-surface radiation model and an enhanced wall function. Boundary conditions were assigned to exterior surfaces under variable outdoor conditions. The numerical and the measurement results indicate that using interior reflective surfaces will affect the indoor air temperature distribution by increasing the vertical temperature gradient depending on the time of the day. CFD simulations with high spatial resolution results show increased interior surface temperature gradients consistent with the increased vertical air temperature gradient. The influence of reflective surfaces is potentially greater with higher indoor surface temperature asymmetry. The vertical indoor air temperature gradient and surface temperatures are important parameters for indoor thermal comfort.

  • 39.
    Jönsson, Johanna
    et al.
    Chalmers University.
    Svensson, Inger-Lise
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    Berntsson, Thore
    Chalmers University.
    Moshfegh, Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    Excess heat from kraft pulp mills: Trade-offs between internal and external use in the case of Sweden - Part 22008Ingår i: Energy Policy, ISSN 0301-4215, E-ISSN 1873-6777, Vol. 36, nr 11, s. 4186-4197Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper the trade-off between internal and external use of excess heat from a kraft pulp mill is investigated for four different future energy market scenarios. The work follows the methodology described in Svensson et al. [2008. Excess heat from kraft pulp mills: trade-offs between internal and external use in the case of Sweden-Part 1: methodology. Energy Policy, submitted for publication], where a systematic approach is proposed for investigating the potential for profitable excess heat cooperation. The trade-off is analyzed by economic optimization of an energy system model consisting of a pulp mill and an energy company (ECO). In the model, investments can be made, which increase the systems energy efficiency by utilization of the mills excess heat, as well as investments that increase the electricity production. The results show that the trade-off depends on energy market prices, the district heating demand and the type of existing heat production. From an economic point of view, external use of the excess heat is preferred for all investigated energy market scenarios if the mill is studied together with an ECO with a small heat load. For the cases with medium or large district heating loads, the optimal use of excess heat varies with the energy market price scenarios. However, from a CO2 emissions perspective, external use is preferred, giving the largest reduction of global emissions in most cases.

  • 40. Karimipanah, T
    et al.
    Awbi, H B
    Moshfegh, Bahram
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem.
    The air distribution as an indictor for energy comsumption and performance of ventilation systems2008Ingår i: Journal of the human-environment system, ISSN 1345-1324, Vol. 11, nr 2, s. 77-84Artikel i tidskrift (Refereegranskat)
  • 41. Karimipanah, T
    et al.
    Awbi, H.B.
    Moshfegh, Bahram
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem.
    On the Energy consumption of High-and-Low.Level Air Supplies2006Ingår i: 7th International Renewable Energy Congress,2006, 2006Konferensbidrag (Refereegranskat)
  • 42. Karimipanah, T
    et al.
    Moshfegh, Bahram
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem.
    On the performance of confluent jets ventilation system in office space2007Ingår i: 10th International Conference on Air Distribution in Rooms,2007, 2007Konferensbidrag (Refereegranskat)
    Abstract [en]

       

  • 43.
    Karlsson, Fredrik
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    Moshfegh, Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    A comprehensive investigation of a low-energy building in Sweden2007Ingår i: Renewable Energy, ISSN 0960-1481, Vol. 32, nr 11, s. 1830-1841Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In Sweden, the building sector alone accounts for almost 40% of the total energy demand and people spend more than 80% of their time indoors. Reducing energy demand in the buildings is essential to the achievement of a sustainable built environment. At the same time, it is important to not deteriorate people's health, well-being and comfort in buildings. Thus, designing healthy and energy efficient buildings are one of the most challenging tasks for building scientists. A low-energy building that uses less than half of the purchased energy of a comparable typical Swedish building has been investigated from different viewpoints in an attempt to represent the building at different system levels. First, the ventilation performance in different rooms using the tracer gas method is reported. Second, results from simulations and in situ measurements are used to analyse the building's power demand and energy performance. The household's behaviour and their impact on energy usage as well as acceptance are reported. Finally, the CO2 emissions with regard to the energy usage are analysed on the basis of different supply energy forms from surrounding energy systems, for example a Swedish and European electricity mix, or district heating as a substitute for electrical heating.

  • 44.
    Karlsson, Fredrik
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    Moshfegh, Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    Energy demand and indoor climate in a low energy building : changed control strategies and boundary conditions2006Ingår i: Energy and Buildings, ISSN 0378-7788, Vol. 38, nr 4, s. 315-326Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Energy demand in the built environment is an important issue. In Sweden, 39% of energy use originates from the building sector, and this figure is increasing. Several attempts have been made to improve the energy use, for example low-energy houses, which are built with the aim of decreasing the use of energy, but still providing a good environment for the occupants. An energy simulation program, ESP-r, was used for simulation of the energy requirement and indoor climate in a well-insulated terraced house in Sweden. The building model was compared to measured values from the real object. A computational fluid dynamics (CFD)-model for one room was used to simulate and visualize the airflow and temperature pattern. Increased set-point temperature increases the power demand by about 200 kWh/°C. Thinner insulation increases the heat demand but decreases the demand for passive cooling by airing and deteriorates the indoor climate. Different types of windows affect both the energy demand and the indoor climate significantly. Load management was simulated by restriction on the heating possibilities and an economical comparison was made to investigate the advantage of such an operation. The extra insulation has a payoff time of about 38 years at common Swedish energy prices.

  • 45.
    Karlsson, Fredrik
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    Moshfegh, Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    Energy usage and thermal environment in a low-energy building2004Ingår i: Proceedings of Roomvent 2004, 9th International Conference on Air Distribution in Rooms, 5–8 Sept., Coimbra, Portugal, 2004Konferensbidrag (Refereegranskat)
  • 46.
    Karlsson, Fredrik
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för ekonomisk och industriell utveckling.
    Moshfegh, Bahram
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem.
    Whole building CFD simulation of a Swedish low-energy building2007Ingår i: CLIMA 2007 - Wellbeing indoors,2007, 2007Konferensbidrag (Refereegranskat)
    Abstract [en]

           

  • 47.
    Karlsson, J.Fredrik
    et al.
    Linköpings universitet, Institutionen för konstruktions- och produktionsteknik, Energisystem. Linköpings universitet, Tekniska högskolan.
    Moshfegh, Bahram
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem.
    Investigation of indoor climate and power usage in a data center2005Ingår i: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 37, nr 10, s. 1075-1083Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Thermal management of data centers is an important issue for many high technology companies. The power requirement to provide proper indoor climate in data centers is considerable. Thus, possibilities for energy savings and efficient electricity utilization are quite important. In this paper, the airflow and temperature patterns, as well as the electrical power requirement within a small data center, have been investigated. The power requirement within the data center is considerably high, due to an oversized air conditioning system. An infrared camera was used to visualize the airflow and temperature pattern, showing that cool air does not reach the upper levels of the racks, despite a very high air exchange rate. Point measurements of temperatures in a rack show that recirculation cells are present, causing accumulation of heat and improper cooling of electronic equipments. Thus, the chilled air is not distributed properly and consequently the cooling energy is not used effectively. © 2005 Elsevier B.V. All rights reserved.

  • 48.
    Karlsson, Magnus
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    Gebremedhin, Alemayehu
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    Klugman, Sofia
    Gävle University.
    Henning, Dag
    Optensys Energianal.
    Moshfegh , Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    Regional energy system optimization - Potential for a regional heat market2009Ingår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 86, nr 4, s. 441-451Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Energy supply companies and industrial plants are likely to face new situations due to, for example, the introduction of new energy legislation, increased fuel prices and increased environmental awareness. These new prerequisites provide companies with new challenges but also new possibilities from which to benefit. Increased energy efficiency within companies and increased cooperation between different operators are two alternatives to meet the new conditions. A region characterized by a high density of energy-intensive processes is used in this study to find the economic potential of connecting three industrial plants and four energy companies, within three local district heating systems, to a regional heat market, in which different operators provide heat to a joint district heating grid. Also, different investment alternatives are studied. The results show that the economical potential for a heat market amounts to between 5 and 26 million EUR/year with payback times ranging from two to eleven years. However, the investment costs and the net benefit for the total system need to be allotted to the different operators, as they benefit economically to different extents from the introduction of a heat market. It is also shown that the emissions of CO2 from the joint system would decrease compared to separate operation of the systems. However, the valuation of CO2 emissions from electricity production is important as the difference of emitted CO2 between the accounting methods exceeds 650 kton/year for some scenarios.

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