| 1. |
- Ossman, Lisa, et al.
(författare)
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Nulägesanalys för satsning på NNE byggnader : slutrapport etapp 1
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Det övergripande syftet med uppdraget är att få en detaljerad bild över byggnaders energiprestanda i Sverige. Den första etappen, förstudien, går ut på att beskriva metoden för hur denna analys ska göras. Som etapp 2 genomförs själva nulägesanalysen och slut¬ligen i etapp 3 analyseras resultat och slutsatser presenteras. I denna rapport redogörs för etapp 1, dvs metodbeskrivningen för nulägesanalysen. Nulägesanalysen ska senare kunna användas för att följa upp hur satsningar på Näranoll¬energibyggnader (NNE) påverkar energianvändningen i hela byggnadsbeståndet, inte bara i de faktiska demonstrationsprojekt som beviljas stöd och där uppföljning är betydligt enklare. Resultatet av nulägesanalysen, och den uppföljande analysen (planerad till 2015), ska i förlängningen kunna vara ett stöd när de nationella målnivåerna för näranollenergi-byggnader bestäms. I denna rapport redogörs för etapp 1, dvs metodbeskrivningen för nulägesanalysen. Rapporten beskriver vilka statistikkällor som finns idag samt en metod för hur dessa kan bidra till en mer detaljerad bild av byggnaders energiprestanda under ett valt referensår.
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| 2. |
- Gustafsson, Ola, et al.
(författare)
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Flat tube heat exchangers - Direct and indirect noise levels in heat pump applications
- 2014
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Ingår i: Applied Thermal Engineering. - : Elsevier BV. - 1359-4311. ; 66:1-2, s. 104-112
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Tidskriftsartikel (refereegranskat)abstract
- In the outdoor unit of an air-source heat pump the fan is a major noise source. The noise level from the fan is dependent on its state of operation: high air-flow and high pressure drop often result in higher noise levels. In addition, an evaporator that obstructs an air flow is a noise source in itself, something that may contribute to the total noise level. To be able to reduce the noise level, heat exchanger designs other than the common finned round tubes were investigated in this study. Three types of heat exchanger were evaluated to detect differences in noise level and air-side heat transfer performance at varying air flow. The measured sound power level from all the heat exchangers was low in comparison to the fan sound power level (direct effect). However, the heat exchanger design was shown to have an important influence on the sound power level from the fan (indirect effect). One of the heat exchangers with flat tubes was found to have the lowest sound power level, both direct and indirect, and also the highest heat transfer rate. This type of flat tube heat exchanger has the potential to reduce the overall noise level of a heat pump while maintaining heat transfer efficiency.
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| 5. |
- Haglund Stignor, Caroline, et al.
(författare)
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Energy-efficient flat-tube heat exchangers in indirect display cabinet and air-conditioning applications
- 2011
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Ingår i: 23nd International Congress of Refrigeration, International Institute of Refrigeration.
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Konferensbidrag (refereegranskat)abstract
- The possible performance of flat-tube heat exchangers in indirectly cooled display cabinets and airconditioning systems has been studied. Experimental investigations of plain fin flat-tube heat exchangers have been sandwiched with theoretical parameter studies. The results show that flat-tube heat exchangers with plain fins provide considerable savings in the required electric drive power compared to the use of traditional coil designs in supermarket display cabinets. The savings can be up to 15 %. The flat-tube heat exchangers can operate with a small temperature difference which makes frost-free operation possible and thereby the savings potential even larger. In addition, results from experiments and calculations for the same flat-tube heat exchanger designs in indirect air-conditioning applications show that this type of heat exchanger can deliver the desired heat transfer performance at considerably lower pressure drop, both on the air and on the liquid side compared to traditional cooling-coils.
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| 6. |
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| 7. |
- Haglund Stignor, Caroline, et al.
(författare)
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Heat Transfer and Pressure Drop Under Dry and Humid Conditions in Flat-Tube Heat Exchangers With Plain Fins
- 2010
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Ingår i: Heat Transfer Engineering. - : Informa UK Limited. - 0145-7632 .- 1521-0537. ; 31:3, s. 179-192
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Tidskriftsartikel (refereegranskat)abstract
- Flat-tube heat exchangers could be an interesting alternative to make indirect cooling of display cabinets more energy-efficient. This application involves low air velocities in combination with condensation of water vapor on the air side, so plain fins could be suitable. Two different heat exchangers having flat tubes and plain fins on the air side were evaluated experimentally. One of the heat exchangers had continuous plate fins, and the other had serpentine fins. The performances during dry and wet test conditions were compared and related to theoretical predictions for different assumptions. The influence of air velocity, air humidity, and inclination angle was investigated. The results show that, in most cases, the heat transfer performance is somewhat reduced under wet conditions in comparison with dry test conditions, and that wet heat transfer surfaces lead to an increased pressure drop. At the lower air velocity range that was investigated, the heat exchanger having continuous plate fins drained better than the one with serpentine fins.
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