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- Andrae, Anders, 1973, et al.
(författare)
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Life Cycle Assessment of a telecommunications exchange
- 2000
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Ingår i: Journal of Electronics Manufacturing. ; 10:3, s. 147-160
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes a comparative life cycle assessment (LCA) of a new Business Communication 10 (BC10) and an old Business Communication 8 (BC8) model of the private branch exchange Modular Digital 110 (MD 110), designed and sold by Ericsson Enterprise AB (EE) and produced by Flextronics, in this case for the European Union (EU) market. LCA is a technique for assessing the environmental aspects and potential impact associated with a products whole life cycle from the cradle to the grave. The study meets the requirements of the standards International Organisation for Standardisation (ISO) 14040:1997 English (E), ISO 14041:1998 E and the draft standards ISO/Draft International Standard (DIS) 14042 and ISO/DIS 14043 and was critically reviewed by Henrik Wenzel, Instituttet for ProduktUdvikling (The Institute for Product Development, IPU) in Denmark. The modelling of the system includes manufacturing (hardware and EEs organisation), use stage (electricity consumption), end-of-life (recycling processes) and transports. Electronic devices are modelled in depth (16 groups of components) and data from over 40 suppliers have been collected. EEs organisation (development, marketing & sales, supply, installation, service and maintenance) is modelled for use of offices and business travelling. The following main conclusions of the project are based on results for potential contributions to the environmental impact categories acidification, global warming and eutrophication, which were chosen to be the most relevant. The environmental impact improvements of the new model compared to the old are approximately 10%, and the uncertainty of the results is judged to be smaller than the difference between the systems.The use stage and the manufacturing stage give the largest impacts, both for the new and the old model. In the manufacturing stage, the hardware production clearly dominates. EEs organisation is secondly most important and hardware transport is least important. This is due to more environmental load from service and business travelling in the organisation than environmental load arising from the distribution of the product. The results predominantly reflect energy use, whereas toxicological aspects could not be reliably assessed due to lack of data and reliable methods and needs separate attention. The technology improvements shown for BC10 compared to BC8 only describe design improvements made by EE, and do not take into account potential technology production improvements made by component suppliers.
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- Johansson, David, 1977-
(författare)
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Kinetic modelling of autoignition phenomena
- 2007
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- To fully understand the elementary reactions behind the ignition of automotive fuels the interaction between the fuel components must be known. The ignition initiation is most often caused by loss of an H radical from a reactive fuel molecule, for example n-heptane. The formed alkyl radical is prone to react with oxygen under lean conditions. However, it can also abstract hydrogen from other fuel molecules, hence activating more unreactive species. This type of reactions is called cooxidation reactions and including it in combustion mechanisms improve ignition delay predictions in a wide range of experiments, for Primary Reference Fuel mixtures and toluene/heptane mixtures. Example of such reactions are C7H15• + C8H18 = C7H16+ C8H17• C7H15OO• + C8H18 = C7H15OOH+ C8H17• Adding cooxidation reactions also significantly improves prediction of the general trend of auto-ignition phasing as function of operating conditions in Homogeneous Charge Compression Ignition, HCCI, engine combustion. The effect of NO addition on engine combustion has also been studied in this work. A novel strategy to control ignition onset in HCCI engines is to retain exhaust gases in the cylinder to control the cylinder temperature. While this not only controls the engine temperature it also introduces NOx in the cylinder. The NO will advance ignition onset by several crank angle degrees at concentrations below 10 ppm. This is because NO activates HO2 in the reaction: HO2• + NO = OH• + NO2. At higher concentrations the ignition onset is not as advanced and in the PRF case even retarded. This is because NO has cool flame-inhibiting effects. Kinetic modelling can also be used to predict combustion efficiency in catalytic combustors for power generation. It was shown that at high pressures the number of free sites decreases which limits the combustion efficiency. Thus a hybrid concept could be used where only a fraction of the air and fuel is burned catalytically.
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