| 1. |
- Boman, Christoffer, et al.
(författare)
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Development of innovative small(micro)-scale biomass-based CHP technologies
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- To enhance the overall efficiency of the use of biomass in the energy sector in Europe, the large electricity production potential from small-scale biomass heating systems should be utilised. So far, no technologically sound (in terms of efficiency and reliability) and economically affordable micro- and small-scale biomass CHP technologies are, however, available. Therefore, the present ERA-NET project (MiniBioCHP) aimed at the further development and test of new CHP technologies based on small-scale biomass combustion in the electric capacity range between some W and 100 kW. Within the project, an international consortium consisting of 12 partners from 4 countries, including university institutions, institutes and industry (both engineering and manufacturing), collaborated closely to perform high level R&D on three promising micro/small-scale biomass based CHP technologies which are covering a broad range of applications in the residential heating sector. The Austrian engineering company BIOS, coordinated the international project. The project was based on earlier basic research and development work related to these promising new technologies and aimed at the achievement of a technological level which allows a first (commercial) demonstration after the end of the project. The three CHP concepts included in the MiniBioCHP project were;1. Pellet stoves with a thermoelectric generator (TEG)2. Small-scale biomass boilers (10-30 kWth) with a micro-ORC process3. High temperature heat exchanger (HT-HE) for an externally fired gas turbine (EFGT)The Swedish part of the project was focused on the development of the concept of biomass based EFGT with dedicated R&D activities related to the development of the HT-HE system. The Swedish project consisted of the research partners Umeå University (project leader), Luleå University of Technology, Chalmers University of Technology and RISE Research Institutes of Sweden, together with the industrial partners Enertech AB/Osby Parca and Ecergy. The expertise of the Swedish partners regarding ash related problems, grate boiler combustion and modelling, deposit formation and high temperature corrosion, were combined with the know-how of a Polish partner regarding HT-HE design, construction, testing and optimisation.The HT-HE is the most crucial component in EFGT processes significantly influencing the investment costs, availabilities as well as the efficiencies that can be achieved. With a thermal capacity from several hundred kW up to 2-3 MWth) the CHP technology based on a biomass boiler and an EFGT is suitable for district heating systems, or process heat consumers. The electricity produced by the gas turbine (up to some 100 kWel) can be used to cover the own electricity consumption of a company and/or fed into the grid. Even though the concept of biomass based EFGT has been an interesting alternative for small-scale CHP production for some decades, and R&D activities have been undertaken, tackling both economic and technical aspects, only a few pilot-plants have been in operation and no initiative has so far reached the level of commercial implementation. Thus, the concept of EFGT fed with biomass is still considered to be in a rather early development stage and the main technical challenges are related to alkali deposit induced corrosion and thermal stress of the HT-HE material, turbine design/operation and system integration.Within the present project, a HT-HE prototype aimed for an EFGT system was therefore designed, constructed and successfully tested at flue gas temperatures up to 900°C. Thus, appropriate guidelines for a compact design of the HT-HE and recommendations have been worked out to minimize thermal stresses as well as ash related problems regarding ash deposit formation and high temperature corrosion in a biomass boiler system. Furthermore, different concepts for the overall biomass based EFGT system have been worked out and evaluated. The outcome of the project will hopefully be used in the further development work and form the basis for a first testing and demonstration plant within the coming years.
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| 2. |
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| 3. |
- Dalmo, Erika, et al.
(författare)
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Targeting SOX2 in glioblastoma cells reveals heterogeneity in SOX2 dependency
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Glioblastoma (GBM) is a lethal disease with no curative treatment. SOX2 is a stem cell transcription factor which is widely expressed across human GBM tumors. Downregulation of SOX2 inhibits tumor formation and its depletion leads to a complete stop of cell proliferation. Despite its known important role in GBM, there is a lack of SOX2 overexpression studies in human GBM cells cultured under stem cell conditions. Previous work in our lab suggests that SOX2 levels need to be precisely maintained for GBM cells to thrive. In this project, we have investigated how altered SOX2 expression affects primary human GBM lines. We found that elevated SOX2 expression inhibited proliferation in a dose-dependent manner in three out of four GBM cell lines. Global gene expression in the resistant line was shifted towards that of the proliferation-inhibited lines upon SOX2 induction. However, SOX2 induction also led to an increase in a GBM stem cell injury response phenotype, which was not present in proliferation-inhibited lines. Furthermore, CRISPR/Cas9-mediated SOX2 knockout revealed a SOX2 independence in the resistant cell line, where SOX2-negative cells could be propagated both in vitro and in vivo.
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| 4. |
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| 5. |
- Frenning, Göran, et al.
(författare)
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Li conduction in sputtered amorphous Ta2O5
- 2001
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Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 148:5, s. A418-A421
-
Tidskriftsartikel (refereegranskat)abstract
- Electron and Li ion conducting properties of room temperature sputtered amorphous tantalum oxide (a-Ta2O5) films were studied in order to evaluate the feasibility of using a-Ta2O5 in electrochromic device applications. The films were investigated using the galvanostatic intermittent titration technique, impedance spectroscopy, and isothermal transient ionic current measurements. It was found that the a-Ta2O5 met two out of three requirements posed on a Li ion conductor in a WO3 based electrochromic device. There was a negligible intercalation in the potential window used in WO3-based electrochromic devices (above 2.4-2.5 V vs. Li/Li+). Furthermore, in this potential region, the chemical diffusion coefficient for Li was larger than the corresponding quantity in WO3. However, there was a nonzero electron conductivity in the a-Ta2O5 films, not observed in the chemical vapor deposition-made β-Ta2O5 investigated earlier. Still, the ionic conductivity was approximately one order of magnitude larger than the electronic one.
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| 6. |
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| 7. |
- Johansson, Andreas, et al.
(författare)
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Dynamics of furnace processes in a CFB boiler
- 2007
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Ingår i: Chemical Engineering Science. - : Elsevier BV. - 0009-2509 .- 1873-4405. ; 62:1-2, s. 550-560
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Tidskriftsartikel (refereegranskat)abstract
- With the aim of understanding the dynamics of combustion, this work examines simultaneous fluctuations in fluid dynamic parameters and gas composition measured in a CFB furnace operated with coal as a fuel. The fluid dynamic parameters investigated are pressure and air flow entering the furnace. Gas composition was recorded by a zirconia-cell probe and a gas suction probe connected to a mass spectrometer having a high time resolution (10 Hz). The principal fluctuations detected are around I Hz and below 0.3 Hz. The fluctuations below 0.3 Hz mostly originate from variations in the fuel-feed rate. These variations create periods of reducing conditions caused by a momentarily high fuel input accompanied by a pressure rise in the furnace and a reduction of the air feed, which occurs concurrent with the release of an enhanced quantity of volatiles. Modelled pressure fluctuations based on the relation between volatile release and pressure in the furnace give similar pressure fluctuations as the measured pressure fluctuations, with respect to amplitude and characteristic time scale of the fluctuations. There is also a correlation between reducing conditions and the concentration of hydrocarbons. (c) 2006 Elsevier Ltd. All rights reserved.
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| 8. |
- Johansson, Fredrik
(författare)
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Evaluating the performance of TEWA systems
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- It is in military engagements the task of the air defense to protect valuable assets such as air bases from being destroyed by hostile aircrafts and missiles. In order to fulfill this mission, the defenders are equipped with sensors and firing units. To infer whether a target is hostile and threatening or not is far from a trivial task. This is dealt with in a threat evaluation process, in which the targets are ranked based upon their estimated level of threat posed to the defended assets. Once the degree of threat has been estimated, the problem of weapon allocation comes into the picture. Given that a number of threatening targets have been identified, the defenders need to decide on whether any firing units shall be allocated to the targets, and if so, which firing unit to engage which target. To complicate matters, the outcomes of such engagements are usually stochastic. Moreover, there are often tight time constraints on how fast the threat evaluation and weapon allocation processes need to be executed. There are already today a large number of threat evaluation and weapon allocation (TEWA) systems in use, i.e. decision support systems aiding military decision makers with the threat evaluation and weapon allocation processes. However, despite the critical role of such systems, it is not clear how to evaluate the performance of the systems and their algorithms. Hence, the work in thesis is focused on the development and evaluation of TEWA systems, and the algorithms for threat evaluation and weapon allocation being part of such systems. A number of algorithms for threat evaluation and static weapon allocation are suggested and implemented, and testbeds for facilitating the evaluation of these are developed. Experimental results show that the use of particle swarm optimization is suitable for real-time target-based weapon allocation in situations involving up to approximately ten targets and ten firing units, while it for larger problem sizes gives better results to make use of an enhanced greedy maximum marginal return algorithm, or a genetic algorithm seeded with the solution returned by the greedy algorithm.
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| 9. |
- Jones, Frida, et al.
(författare)
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Effects of Reduced Bed Temperature in Laboratory- and Full-Scale Fluidized-Bed Boilers : Particle, Deposit, and Ash Chemistry
- 2013
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 27:8, s. 4999-5007
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Tidskriftsartikel (refereegranskat)abstract
- This study focuses on how the temperature of the bed in a waste-fired fluidized-bed boiler affects the chemical composition of ash and deposits. The aim was to reduce the concentration of corrosive elements in the convection pass, which can lead to both less frequent soot blowing intervals and extended superheater lifetimes. Complementary laboratory-scale tests were carried out in a single-pellet reactor to study online alkali and Zn emissions during temperature changes, using an ICP-MS instrument. The full-scale study was based on full-scale experiments at a plant consisting of two 20 MWth fluidized-bed boilers firing a mixture of municipal solid waste and industrial waste. The boilers are normally operated at bed temperatures of about 870 C. This normal operation was compared in this work to a test case in which the bed temperature was reduced below 720 C by altering the air staging and flue gas recycling. The experimental work included collecting samples of fuel, ash, and particles under the two different sets of operating conditions. Furthermore, deposits on temperature-controlled probes were sampled upstream of the superheaters. By reducing the bed temperature, the sand consumption of the plant could be reduced by roughly 25%. The measurements showed that the amount of submicrometer particles decreased and the fouling rate on deposit probes was reduced by about 20%. The measured concentration of HCl in the flue gas increased as the bed temperature was reduced. This might be a consequence of the reduced formation of alkali chlorides. In addition, results from the laboratory-scale tests indicated a trend of reduced alkali emissions from the fluidized bed with reduced temperature, and thermodynamic equilibrium calculations confirmed the trends.
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| 10. |
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| 11. |
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| 12. |
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| 13. |
- Larsson, Oscar, 1978-
(författare)
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The Governmentality of Meta-governance : Identifying Theoretical and Empirical Challenges of Network Governance in the Political Field of Security and Beyond
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Meta-governance recently emerged in the field of governance as a new approach which claims that its use enables modern states to overcome problems associated with network governance. This thesis shares the view that networks are an important feature of contemporary politics which must be taken seriously, but it also maintains that networks pose substantial analytical and political challenges. It proceeds to investigate the potential possibilities and problems associated with meta-governance on both theoretical and empirical levels.The theoretical discussion examines meta-governance in relation to governmentality, and it puts forward the claim that meta-governance may be understood as a specific type of neo-liberal governmentality. The meta-governance perspective regards networks as a complementary structure to traditional administration that can be utilized in the implementation and realization of public policy, but which also preserves the self-regulating and flexible character of networks. This generates a contradiction between the goals of public management and the character of networks that requires further investigation.The combination of the specific dynamics of the political field of security, the diminishing role of sovereign powers, the emergence of security networks, and the meta-governance stance adopted by the Swedish state constitutes a situation that should have been favorable for the successful employment of meta-governance. The empirical investigation of meta-governance is divided into two parts. The first part reviews the historical process involved and shows how the Swedish government and public authorities have adopted a meta-governance stance. The second analyzes the specific instruments and strategies that have been deployed in the governance of security communications and in the management of Sweden’s new security communications system which is an important aspect of security networks. The historical study together with the analysis of the meta-governance tools deployed reveals that the meta-governors neither reached the goals specified, nor fulfilled the overall purpose of successful security communications.I argue on the basis of the theoretical and empirical findings obtained in the present study that it is very difficult to successfully employ meta-governance in respect to security and crisis management, and that we have sound reasons to suspect that meta-governance will run into similar difficulties in other political fields as well. I conclude that meta-governance is a far more difficult practice than has been anticipated by existing theories and policy recommendations. Turning to meta-governance as a way to govern and control organizations may in fact lead to further fragmentation and distortion of public politics.
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| 14. |
- Nevalainen, H., et al.
(författare)
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Firing of coal and biomass and their mixtures in 50 kW and 12 MW circulating fluidized beds - Phenomenon study and comparison of scales
- 2007
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Ingår i: Fuel. - : Elsevier BV. - 0016-2361. ; 86:14, s. 2043-2051
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Tidskriftsartikel (refereegranskat)abstract
- The combustion dynamics of coal, wood chips and their mixture is investigated. Load change capability and the effect of the individual control variables, for example the mixture ratio of different fuels, on pilot-scale CFB boiler dynamics were also studied. Disturbances in fuel feeding cause fluctuations in the flue gas concentrations. Changes in the heating value are possible due to varying moisture content of the fuel. Both these disturbances affect the instantaneous firing rate in a boiler. Also the characteristics of the fuels have to be taken into consideration when designing boiler control systems. When co-firing two fuels with clearly distinct combustion characteristics, direct assumptions based on each fuel's characteristies cannot be made about combustion behaviour of their mixture. Combustion experiments with coal and wood chips and their co-firing were carried out in a pilot-scale CFB reactor (VTT) and a large-scale CFB boiler (Chalmers). A comparison of the combustion in the two different size reactors, provides information about scaling. The combustion responses due to changes in the fuel feeding of the two circulating fluidized beds are analyzed by a dynamic model. (c) 2007 Elsevier Ltd. All rights reserved.
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| 15. |
- Niklasson, Fredrik, 1972, et al.
(författare)
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Biomas co-firing in a CFB boiler
- 2006
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Ingår i: Proceedings of the 19th FBC Conference. ; 1
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Konferensbidrag (refereegranskat)abstract
- The aim of present paper is to investigate the effects on gas distribution in a CFB furnace fromburning varied fractions of wood fuel with coal as a base fuel. The work is based on in-situmeasurements of gas concentrations at different locations in the furnace of the Chalmers12 MWth CFB boiler. The boiler was operated at two different pressure drops over the furnace,corresponding to different amounts of bed material. The latter was done since a reducedpressure drop over the furnace improves the overall boiler efficiency as long as the combustionperformance can be maintained. The gas-concentration measurements in the furnace arecompared to results from experiments in a cold laboratory scale fluidized bed unit in which therates of mixing of solids (fuel particles) are determined at varied bed heights and gas velocitiesby frame-by-frame digital image analysis of video recordings. Thus, the gas distribution in thefurnace is assumed to be related to the mixing of fuel particles.The cold bed experiments show a pronounced reduction in solids-mixing rate when lowering thebottom bed height. Since an increased fraction of wood in the fuel mixture leads to a largeramount of volatile gases emitted in the bottom region, a combination of a low bed height and ahigh biomass fraction in the fuel could result in significant maldistribution of combustible gasesover the furnace cross section. The conclusion from the present boiler measurements is that theperformance of an existing CFB boiler, operated satisfactorily with a low furnace pressure dropwhen firing coal, may deteriorate when adding wood to the fuel mixture due to lateralmaldistribution of combustible gases. The results show that this effect can, to some extent becounteracted by increasing the amount of bed material in the furnace, at the cost of higherpressure-drop losses.
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| 16. |
- Niklasson, Fredrik, et al.
(författare)
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Branschgemensam forskning för småskaliga biobränslepannor inför ekodesign
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Nytillverkade småskaliga biobränslepannor måste uppfylla ekodesignkraven senast år 2020. I en marknadsundersökning från 2014 klarade ingen av 11 testade pelletspannor alla ställda krav, vilket tydligt visar på ett utvecklingsbehov. Föreliggande projekt har haft som syfte att panntillverkare och forskningsinstitut branschgemensamt ska bemöta de förbränningstekniska utmaningar som tillverkarna står inför.För pelletspannor är den största utmaningen med ekodesigndirektivet att prestanda till största delen beräknas från drift vid partiell last (låg last). Tidigare har prestanda bara fastställts vid nominell last och designen optimerats därefter. I detta projekt har tester körts med två moderna pelletspannor som har olika typer av pelletsbrännare: en med horisontellt brännarrör och en med undermatad brännarkopp. Resultaten visar att tillräckligt god förbränning kunde upprätthållas vid partiell last med båda brännartyperna. Dock uppvisade rörbrännaren betydligt lägre emissioner vid partiell last, troligtvis beroende på att förbränningszonen i denna brännare är skyddad från värmestrålningsutbyte med kylande pannväggar. Ett ganska omfattande arbete lades ned på att förse koppbrännaren med en skyddande krage som skulle skydda förbränningszonen. Det resulterade dock inte in någon betydande förbättring, antagligen beroende på att tillförseln av sekundärluft inte blev optimal. Ett mer omfattande arbete krävs för att utveckla en optimal brännardesign av denna typ.För vedpannor är det en utmaning att klara ekodesigndirektivets NOx-krav på 200 mg/Nm³. En mängd temperaturmätningar i en vedpanna för villabruk resulterade i att termisk NOx-bildning kunde uteslutas. Pannan förseddes med ett system för rökgasåterföring, men det minskade inte NOx-emissionen. Därefter provades olika vedsorter. NOx-emissionen kunde minskas till att klara gränsvärdet med avbarkad björkved. Kemiska analyser visade att björkbarken innehöll 0,49% kväve jämfört med 0,09% i stamveden. Även granved gav låga NOx-emissioner, men det bränslet medförde ökade emissioner av CO och OGC. För att vedpannor ska klara kraven på CO, OGC och stoft krävs optimering med avseende på vedens slutförbränningsfas. I det skedet är emissionerna som högst, vilket beror på att värmeeffekten avtar och luftflödet tenderar att kyla ned rökgasen innan de brännbara gaserna brunnit ut. Den optiska partikelmätningen visade tydlig korrelation mellan stoft och CO i rökgasen. Om pannan uppfyller gränsvärdet för CO så finns goda chanser att även kravet på partiklar uppfylls.Verkningsgraden som anges i ekodesigndirektivet beräknas utgående från bränslets övre värmevärde. Dessutom subtraheras vissa förlustfaktorer. Detta innebär att pannan inte får ha några onödigt stora värmeförluster eller omotiverat hög elförbrukning för att klara satta krav. Mätningar visade att den största förlusten sker via värmen i rökgasen. Den näst största förlustposten är värmetransport från pannkroppen. För verkningsgraden ökar betydelsen av en välisolerad pannkropp vid partiell last. De två pelletspannor som användes inom projektet låg väl till för att kunna uppfylla ekodesigndirektivets krav på verkningsgrad.
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| 17. |
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| 18. |
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| 19. |
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| 20. |
- Niklasson, Fredrik, 1968, et al.
(författare)
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Estimation of the temperature in the bottom region of a fluidized-bed furnace burning biomass
- 2006
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Ingår i: Science in Thermal and Chemical Biomass Conversion. - 1872691978
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Konferensbidrag (refereegranskat)abstract
- The heat and mass balance of the bottom region of a fluidized bed boiler burning biomass is established with the aim of determining the furnace temperature. The influence on the temperature by the flow of solids in the upper part of the bottom region is investigated. Heat and mass balances of gas and fuel were applied over a control volume containing the bottom region, i.e. both the bed and the adjacent splash zone. The mass balance is based on given input flow rates of gas and fuel and concentrations in the gas leaving the control volume. The measured gas concentrations were used to determine the rate of fuel burnout inside the control volume. Pressure drop measurements along the height of the furnace estimate the solids concentration. Experiments were performed in a furnace with a cross-section area of 2.2 m2. The walls of the furnace are refractory lined up to a height of 2 m and, for simplicity, the control volume is chosen from the air distributor up to this height. Two fuel mixtures were used: one biomass and one of biomass and coal. The results show that the gas temperature at the top of the control volume strongly depends on the flow-rate of fine particles present in the fluid, even when the volume fraction of particles is small. The particles carry heat to the freeboard, where they transfer heat to the walls before returning to the bottom region. This process has previously been neglected in models of fluidized-bed combustion under bubbling conditions, overestimating the fluid temperature.
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| 21. |
- Niklasson, Fredrik, 1968
(författare)
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Heat Balance Modeling of a Stationary Fluidized-Bed Furnace Burning Biomass
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The influence of biomass fuel properties on the heat balance of the bottom region (bed and splash zone) of a commercial-scale bubbling fluidized-bed furnace is investigated theoretically and experimentally. The experiments have been carried out at the Chalmers 12 MWth research boiler, operated under non-circulating conditions during most of the experiments. The different parts of the work are summarized as follows. A two-phase flow model of the bed and the splash zone in a boiler is presented. The combustion rate in the bed is estimated by global kinetic expressions, limited by the gas exchange between oxygen-rich bubbles and a fuel-rich emulsion phase, whereas the combustion rate above the bed is determined from turbulence properties. A heat balance of the bottom region shows that the average temperature of the gas leaving the bottom region strongly depends on the flow rate of fine particles present in the fluid. The particles carry heat to the freeboard, where they transfer heat to the boiler walls before returning to the bottom region. A method is proposed for estimation of the effective lateral dispersion of fuel in a fluidized-bed combustor. By correlating the drying of the fuel particles and the measured moisture concentrations above the bed, the effective lateral dispersion coefficient of the fuel particles is determined. This coefficient was estimated to be on the order of 0.1m2/s, which is considerably higher than predicted by most of the expressions given in the literature. The local air ratios in the furnace are estimated by fluctuating signals from zirconia cell probes, which are compared to simultaneous gas concentrations of extracted gas samples. The time fraction during which the fluctuating zirconia cell signal shows oxidizing gas conditions is strongly correlated with the local air ratio of the gas. When this correlation is determined, the fluctuating signals from zirconia-cell sensors can be used to obtain the air ratio at different heights in the furnace. This provides a cheap and robust technique for on-line monitoring of the gas conditions in the furnace when, for example, optimizing the operation of a fluidized-bed boiler to reduce nitrous oxide emissions.
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| 22. |
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| 23. |
- Niklasson, Fredrik, et al.
(författare)
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Marknadspotential för bio- och solvärmesystem
- 2008
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- I denna rapport analyseras marknaden för kombinerade sol- och pelletsystem, medfokus på småhus. Syftet är att presentera antalet objekt inom olika kategorier av husoch värmesystem som kan vara intressanta för konvertering till bio-sol system samtatt ge en uppskattning av årliga uppvärmningsbehov inom respektive kategori.Energistatistik från Statistiska centralbyrån (SCB) har använts i kombination medtidigare studier av byggnadsbestånd och byggnadsutformning. Dessutom harinformation inhämtats från olika branschorganisationer.Från föreliggande genomgång står det klart att den största potentialen för bio-solsystem finns på villamarknaden både för helt nya system och för kompletteringar tillbefintliga system. År 2006 fanns det 775 000 småhus med vattenburen värme varav ca183 000 hade vattenburen el. Uppskattningsvis fanns 109 000 småhus med bådevattenburen el och lokaleldstad för biobränsle och ca 118 000 hus bedöms ha haftmöjlighet till oljeeldning (denna grupp har troligtvis minskat ytterligare efter 2006).Bland de elvärmda husen finns också ca 102 000 småhus med frånluftvärmepumpareller luft/vattenvärmepumpar. 365 000 av husen hade en biobränslepanna. Därtillkommer 504 000 hus med direktelvärme, varav ca 292 000 med lokaleldstad.Medelförbrukningen för uppvärmning och varmvatten för hus som enbart värms medolja är ca 27 MWh/år, medan motsvarande värde för småhus med vattenburen el är ca15 MWh/år. Småhusen med direktel använder ca 12 MWh/år för uppvärmning ochvarmvatten. Det betyder att ekonomin blir betydligt sämre vid konvertering avelvärmda hus jämfört med oljekonvertering, eftersom energibehovet är lägre samt attinstallationskostnaden kan vara högre.En uppskattning av antalet komponenter som inom 10 år kan komma att installeras idessa hus är 213 000 solfångare, 108 000 ackumulatortankar, 106 000 skorstenar,84 000 luftburna pelletkaminer och varmvattenberedare, 40 000 vattenmantladekaminer och 28 000 pannrumspannor. Dessutom tillkommer en utbytesmarknad,kanske speciellt bland husen med biobränslepanna, där gamla pannor byts ut elleräldre människor som tidigare orkat elda med ved till slut byter till pelleteldning.Av nybyggda villor uppvärms ca 30 % med el i kombination med biobränsle(troligtvis lokaleldstad) och ungefär lika stor andel värms med enbart vattenburen el(antagligen ofta kompletterat med frånluftvärmepump). Det borde vara av intresse attredan vid nybyggnationen få in integrerade solfångare och pelleteldning i störreutsträckning i nya hus och det kan bli lättare efter att byggreglerna ändras den 1:ajanuari 2010 med en skärpning av kraven för nybyggda hus som använder el föruppvärmning, alltså även el till värmepumpar.Potentialen för bio-solsystem till flerbostadshus och lokaler är begränsad då 86 % avflerbostadshusen och nära 70 % av lokalerna värms med fjärrvärme. Det fanns år2006 ca 6200 lokaler med oljeeldning, 4600 lokaler med vattenburen elvärme och5700 lokaler med direktverkande elvärme. I lokalerna som redovisas av SCB ingårinte tillverkande industri. För lägenheter i flerbostadshus gäller att ca 42 000lägenheter värms med enbart olja, 44 000 lägenheter med olja och värmepump,48 000 lägenheter använder direktel och 31 000 lägenheter vattenburen el.
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| 24. |
- Niklasson, Fredrik, et al.
(författare)
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Marknadspotential för sol- och biovärmesystem
- 2010
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- I denna rapport analyseras marknaden för kombinerade sol- och pelletsystem, med fokus påsmåhus. Syftet är att presentera antalet objekt inom olika kategorier av hus och värmesystemsom kan vara intressanta för konvertering till bio-sol system samt att ge en uppskattning avårliga uppvärmningsbehov inom respektive kategori.Energistatistik från Statistiska centralbyrån (SCB) har använts i kombination med tidigarestudier av byggnadsbestånd och byggnadsutformning. Dessutom har information inhämtatsfrån olika branschorganisationer.Från föreliggande genomgång står det klart att den största potentialen för bio-sol systemfinns på villamarknaden både för helt nya system och för kompletteringar till befintliga system.År 2006 fanns det 775 000 småhus med vattenburen värme varav ca 183 000 hade vattenburenel. Uppskattningsvis fanns 109 000 småhus med både vattenburen el och lokaleldstadför biobränsle och ca 118 000 hus bedöms ha haft möjlighet till oljeeldning (dennagrupp har troligtvis minskat ytterligare efter 2006). Bland de elvärmda husen finns också ca102 000 småhus med frånluftvärmepumpar eller luft/vattenvärmepumpar. 365 000 av husenhade en biobränslepanna. Därtill kommer 504 000 hus med direktelvärme, varav ca 292 000med lokaleldstad.Medelförbrukningen för uppvärmning och varmvatten för hus som enbart värms med olja ärca 27 MWh/år, medan motsvarande värde för småhus med vattenburen el är ca 15 MWh/år.Småhusen med direktel använder ca 12 MWh/år för uppvärmning och varmvatten. Det betyderatt ekonomin blir betydligt sämre vid konvertering av elvärmda hus jämfört med oljekonvertering,eftersom energibehovet är lägre samt att installationskostnaden kan vara högre.En uppskattning av antalet komponenter som inom 10 år kan komma att installeras i dessahus är 213 000 solfångare, 108 000 ackumulatortankar, 106 000 skorstenar, 84 000 luftburnapelletkaminer och varmvattenberedare, 40 000 vattenmantlade kaminer och 28 000 pannrumspannor.Dessutom tillkommer en utbytesmarknad, kanske speciellt bland husen medbiobränslepanna, där gamla pannor byts ut eller äldre människor som tidigare orkat elda medved till slut byter till pelleteldning.Av nybyggda villor uppvärms ca 30 % med el i kombination med biobränsle (troligtvis lokaleldstad)och ungefär lika stor andel värms med enbart vattenburen el (antagligen oftakompletterat med frånluftvärmepump). Det borde vara av intresse att redan vid nybyggnationenfå in integrerade solfångare och pelleteldning i större utsträckning i nya hus och det kanbli lättare efter att byggreglerna ändras den 1:a januari 2010 med en skärpning av kraven förnybyggda hus som använder el för uppvärmning, alltså även el till värmepumpar.Potentialen för bio-solsystem till flerbostadshus och lokaler är begränsad då 86 % av flerbostadshusenoch nära 70 % av lokalerna värms med fjärrvärme. Det fanns år 2006 ca 6200lokaler med oljeeldning, 4600 lokaler med vattenburen elvärme och 5700 lokaler med direktverkandeelvärme. I lokalerna som redovisas av SCB ingår inte tillverkande industri. Förlägenheter i flerbostadshus gäller att ca 42 000 lägenheter värms med enbart olja, 44 000lägenheter med olja och värmepump, 48 000 lägenheter använder direktel och 31 000 lägenhetervattenburen el.
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| 25. |
- Niklasson, Fredrik, 1968-, et al.
(författare)
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On-line monitoring of agglomeration in fluidised bed boilers
- 2018
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Combustion in fluidized beds has several benefits, but a potential problem is bed agglomeration causing defluidisation. The most used counter measure is to regularly renew the bed material, inferring costs for new sand and deposition of spent material. For an adaptive optimization there is a need of a method which indicates when bed agglomeration is initializing, before it is too late to counteract.In this project, the conductivity of fluidized beds has been measured by a novel in-situ probe. The probe has been tested in a fluidized bed of sand and ashes at temperatures up to 1000°C. In addition, the probe has been tested in a fluidized bed while burning different fuels.The results show that the conductivity of the bed increases with temperature and concentration of ash. The conductivity varies strongly between different fuels. The signal from the probe reacts strongly to the onset of severe bed agglomeration, but it is hard to find any consistent tendencies that can be applied to predict it.
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| 26. |
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| 27. |
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| 28. |
- Niklasson, Lars, et al.
(författare)
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Effects of Cortisol on the Intestinal Mucosal Immune Response during Cohabitant Challenge with IPNV in Atlantic Salmon (Salmo salar)
- 2014
-
Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 9:5
-
Tidskriftsartikel (refereegranskat)abstract
- Infectious pancreatic necrosis virus (IPNV) causes high incidence of disease in salmonids during the first period after SW transfer. During this period as well as during periods of stress, cortisol levels increase and indications of a relationship between IPNV susceptibility and cortisol have been suggested. The intestine is an entry route and a target tissue for IPNV displaying severe enteritis and sloughing of the mucosa in infected fish. The mechanisms behind effects of the virus on the intestinal tissue and the impact of cortisol on the effect remain unclear. In the present study, Atlantic salmon post smolts treated with or without slow release cortisol implants were subjected to a cohabitant IPNV challenge. Analysis of genes and proteins related to the innate and acquired immune responses against virus was performed 6 days post-challenge using qPCR and immunohistochemistry. An increased mRNA expression of anti-viral cytokine interferon type I was observed in the proximal intestine and head kidney as a response to the viral challenge and this effect was suppressed by cortisol. No effect was seen in the distal intestine. T-cell marker CD3 as well as MHC-I in both intestinal regions and in the head kidney was down regulated at the mRNA level. Number of CD8 alpha lymphocytes decreased in the proximal intestine in response to cortisol. On the other hand, mRNA expression of Mx and IL-1 beta increased in the proximal intestine and head kidney in IPNV challenged fish in the presence of cortisol suggesting that the immune activation shifts in timing and response pathway during simulated stress. The present study clearly demonstrates that IPNV infection results in a differentiated epithelial immune response in the different intestinal regions of the Atlantic salmon. It also reveals that the epithelial immune response differs from the systemic, but that both are modulated by the stress hormone cortisol.
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| 29. |
- Niklasson, Lars, et al.
(författare)
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Extending the scope of Situation Analysis
- 2008
-
Ingår i: Proceedings of the 11th International Conference on Information Fusion (FUSION 2008)<em></em>, Cologne, Germany, June 30–July 3, 2008. - : IEEE Press. - 9783000248832 ; , s. 454-461
-
Konferensbidrag (refereegranskat)abstract
- The use of technology to assist human decision making has been around for quite some time now. In the literature, models of both technological and human aspects of this support can be identified. However, we argue that there is a need for a unified model which synthesizes and extends existing models. In this paper, we give two perspectives on situation analysis: a technological perspective and a human perspective. These two perspectives are merged into a unified situation analysis model for semi-automatic, automatic and manual decision support (SAM)2. The unified model can be applied to decision support systems with any degree of automation. Moreover, an extension of the proposed model is developed which can be used for discussing important concepts such as common operational picture and common situation awareness.
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| 30. |
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| 31. |
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| 32. |
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| 33. |
- Odenberger, Eva-Lis, et al.
(författare)
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Direct-hit development of manufacturing processes: Thermo-mechanical forming of Titanium aero engine structures
- 2013
-
Ingår i: Book of Abstracts for the 4:th CEAS Conference, 2013. - Linköping : Linkoping University Electronic Press. - 9789175195209 ; , s. 175-
-
Konferensbidrag (refereegranskat)abstract
- In order to increase the competitiveness of the Swedish aerospace industry, alternative manufacturing processes for static load carrying aero engine structures are desired. Presently, these components mainly consist of large-scaled single castings. To increase the in-house level of processing, the Swedish aero engine industry focus on fabricated alternatives by introducing new manufacturing processes and create relations with adjacent sub-suppliers. Theconcept of fabrication involves forgings, sheet metals and small ingots assembled by welding. The possibility to reduce weight, i.e. fuel consumption and product cost also exists. In the aerospace industry extremely highdemands on safety and reliability exists which requires precise knowledge regarding the influence on the material and its properties through the whole fabrication chain. The advanced Finite Element (FE) technology makes precise analyses possible assuming that proper material descriptions are used. Analyses of sheet metal forming provides with information of formability, thinning, springback, resultant mechanical properties and residual stress state which are important input to analyses of subsequent welding and heat treatments. One challenge in producing complete structures based on fabrication isrelated to the accuracy in numerical predictions of shape deviation using FE-analyses, in order to effectively compensate forming tools forspringback and accumulated shape distortions. By fundamental research on and development of thermo-mechanical processes for hot sheet metal forming of titanium, this project shall result in that a few SME can further developtheir processes for product and process development. The project gather competence from the Swedish aero engine industry GKN Aerospace, acknowledged R&D within forming processes, FE-modelling and SME withexperience of forming. The aims of the project are:Development of methodologies for thermomechanical material characterisation of Ti-6Al- 4V and FE-models for hot sheet metal forming. Suggestion of forming procedures suitable for production of titanium components in which resultant geometry and properties are secured.Activities where Swedish SME takes necessary development steps, in order to produce desired titanium sheet metal parts and develop into new sub-suppliers for the Aero engine industry. This presentation summarise results obtained inpresent and previous research and development projects regarding short lead time design, compensation and manufacturing of deep drawing tools of titanium and super alloys. The research funding by VINNOVA - NFFP 4 and 5for SME, BFS and GKN Aerospace Sweden are gratefully acknowledged.
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| 34. |
- Pérez Caro, Lluís, 1985-, et al.
(författare)
-
Prediction of shape distortions during forming and welding of a double-curved strip geometry in alloy 718
- 2020
-
Ingår i: The International Journal of Advanced Manufacturing Technology. - : Springer. - 0268-3768 .- 1433-3015. ; 107:7-8, s. 2967-2981
-
Tidskriftsartikel (refereegranskat)abstract
- The finite element method (FEM) has considerably contributed to the development of advanced manufacturing methods for metal structures. The prediction of the final shape of a component is of great interest to the manufacturing industry. The level of demand may increase due to multistage processes. Therefore, including all steps of the manufacturing chain in the simulations is a key to being successful. This has been done for a long time in the stamping industry, which involves sequences of forming, trimming, and springback. However, more complex manufacturing procedures that include assembling of formed parts with forgings and castings via welding have been modelled with simplifications, resulting in a reduced prediction accuracy. In the present study, a double-curved part manufactured from alloy 718 is formed at 20 °C and laser-welded using the bead-on-plate procedure. The coupling of different manufacturing analyses, including cold forming, trimming, result mapping, welding, cooling, and springback, is achieved using LS-DYNA. Additionally, the effect of adding a damage and failure model in the forming simulation is studied. The results of the forming analysis are used as inputs for the material model *MAT_CWM in the welding simulation. The anisotropic thermomechanical properties of alloy 718 are determined at temperatures up to 1000 °C. Encouraging agreement is found between the model predictions and the results of forming and welding tests. The findings underscore the importance of including the material history and accurate process conditions along the manufacturing chain to both the prediction accuracy of shape distortions, and to the potential of the industry.
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| 35. |
- Pérez Caro, Lluís, 1985-, et al.
(författare)
-
Shape prediction of a hot formed component in nickel-base superalloys
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Current manufacturing processes of advanced aero engine components in nickel-base superalloys are performed at approximately 950 °C, with varying holding times, to reduce the amount of residual stresses, and thereby shape deviations, over the part. The aim of such procedures is to obtain the final geometry of the component within tolerance and avoid costly tryouts, which can be unfavorable to the competitiveness of the aerospace industry. In addition, a reduction in the forming temperature or holding time may significantly reduce the energy consumption and carbon dioxide (CO2) emissions while increasing the ecological sustainability of the process. In this work, the numerical study of a hot forming procedure of a double-curved component in Haynes® 282® is presented. The influence of the forming temperature and holding time on the predicted amount of springback at different stages of the hot forming procedure is assessed. The resulting shape distortions are compared with identical FE analyses in alloy 718 at 870 °C available in literature. The anisotropic properties of the material are determined at temperatures ranging from 20 to 1000 °C. A qualitative analysis of the different types of serrations present in the hardening curves between 300 and 900 °C is included in the study. Microstructural observations of selected specimens are correlated to the material-characterization tests. The thermo-mechanical data is used as input to the novel version of the Barlat Yld2000-2D material model in LS-DYNA. The results show that forming of Haynes® 282® at 870 °C produces high shape distortions over the part with values beyond the sheet thickness, in contrast to the response of alloy 718. A comparison of the stress-relaxation rate with available data in literature for alloy 718 at 870 °C reveals that Haynes® 282® relaxes about 50% slower than alloy 718, whereas reasonably analogous at 950 °C. An increase in the forming temperature to 950 °C significantly reduces the amount of springback. Therefore, it can be concluded that forming of Haynes® 282® requires a higher temperature than reported for alloy 718 to reach similar amount of springback. The presented studies indicate that the use of advanced anisotropic models together with the thermo-mechanical properties and stress-relaxation behavior of the material is of utmost importance to accurately predict the final geometry of lightweight components of interest to the aerospace industry.
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| 36. |
- Pérez Caro, Lluís, 1985-, et al.
(författare)
-
Springback prediction and validation in hot forming of a double-curved component in alloy 718
- 2021
-
Ingår i: International Journal of Material Forming. - : Springer-Verlag Italia s.r.l.. - 1960-6206 .- 1960-6214. ; 14:6, s. 1355-1373
-
Tidskriftsartikel (refereegranskat)abstract
- The demands associated with the production of advanced parts made of nickel-base superalloys are continuously increasing to meet the requirements of current environmental laws. The use of lightweight components in load-carrying aero-engine structures has the potential to significantly reduce fuel consumption and greenhouse gas emissions. Furthermore, the competitiveness of the aero-engine industry can benefit from reduced production costs and shorter development times while minimizing costly try-outs and increasing the efficiency of engines. The manufacturing process of aero-engine parts in superalloys at temperatures close to 950 °C produces reduced stamping force, residual stresses, and springback compared to traditional forming procedures occurring at room temperature. In this work, a hot forming procedure of a double-curved component in alloy 718 is studied. The mechanical properties of the material are determined between 20 and 1000 °C. The presence and nature of serrations in the stress–strain curves are assessed. The novel version of the anisotropic Barlat Yld2000-2D material model, which allows the input of thermo-mechanical data, is used in LS-DYNA to model the behaviour of the material at high temperatures. The effect of considering the stress-relaxation data on the predicted shape distortions is evaluated. The results show the importance of considering the thermo-mechanical anisotropic properties and stress-relaxation behaviour of the material to predict the final geometry of the component with high accuracy. The implementation of advanced material models in the finite element (FE) analyses, along with precise process conditions, is vital to produce lightweight components in advanced materials of interest to the aerospace industry.
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| 37. |
- Pettersson, Anita, et al.
(författare)
-
Comparison of ashes and deposits obtained by RDF combustion in a BR-boiler applying different bed temperatures
- 2010
-
Konferensbidrag (refereegranskat)abstract
- Chemical fractionation and SEM-EDX was used for characterisation of ashes and deposits from different combustion tests in a commercial 20 MW bubbling fluidized bed (BFB) boiler. The fuel combusted was a mix of sorted MSW (Municipal Solid Waste) and industrial waste often referred to as RDF (Refuse Derived Fuel) mostly containing combustible material as paper, plastics and wood. This fuel type often contains a lot of alkali and chlorine and is therefore considered as a risk fuel prone to cause bed agglomeration, deposit formation and corrosion. In order to investigate the impact of the bed temperature on the alkali and chlorine distribution in the boiler combustion tests were performed. The bed temperature for this boiler is designed to be in the range 850-900°C. In this investigation however the bed temperature was reduced to 700-750°C. Two deposit probes, each carrying two rings made of high alloy steel, were used for collection of deposits during combustion. In addition, samples taken on the bed ash, return sand, return shaft ash, cyclone ash and textile filter ash were analysed. By reducing the bed temperature the need for fresh bed sand was reduced and the fly ash flow decreased. In addition, the agglomerates found in the tests with the normal bed temperature disappeared totally when the bed temperature was reduced. The deposits formed on the bed ash and on the return sand particles were found to consist of compounds with melting temperatures between 675 and 801C, which could explain the difference in agglomeration tendency.
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| 38. |
- Pettersson, Anita, et al.
(författare)
-
Examples of Full scale tests on BFB Waste to Energy boilers (WtE) with direct impact on the future operation of the facility
- 2012
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The growing problem with municipal solid waste has helped to accelerate de development of Waste to Energy plants (WtE). However, WtE-plants have problems with agglomeration, deposition and corrosion. And at the same time new waste streams are considered for combustion. Co-combustion has sometimes proven to have positive effects on the combustion environment. In this project full scale tests were performed on two twin 20 MWth WtE Bubbling Fluidized Bed (BFB) boilers in Borås, Sweden. The aim of the research was to investigate if a lowered bed temperature by means of flue gas recirculation or addition of animal waste to the normal waste mix (NWM) could improve the boiler performance. The bed temperature was decreased from 870°C, the boiler design temperature, to around 750°C. The animal waste is a pumpable slurry consisting of crushed carcasses and slaughterhouse waste classified with risk of infection because of BSE (Bovine spongiforme encephalopathy or the mad cow disease). The result shoved both decreased deposit formation rate and decreased agglomeration tendency of the bed. And in the case with animal waste addition the NOx emission was reduced with 50% compared to ordinary performance. Furthermore the ammonia addition for NOx reduction was also cut by half in this case.
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| 39. |
- Pettersson, Anita, et al.
(författare)
-
Reduced bed temperature in a commercial waste to energy boiler : Impact on ash and deposit formation
- 2013
-
Ingår i: Fuel processing technology. - : Elsevier BV. - 0378-3820 .- 1873-7188. ; 105, s. 28-36
-
Tidskriftsartikel (refereegranskat)abstract
- Waste combustion for power production is associated with many problems due to the composition and inhomogeneity of the fuel stream. A reduction of alkaline and chlorine products in the superheater region should ease these problems significantly. Ashes and deposits from different combustion tests in a commercial 20 MWth bubbling fluidised bed (BFB) boiler were characterised by XRD and SEM-EDX. The fuel combusted was a mix of sorted municipal solid waste (MSW) and industrial waste, often referred to as RDF (refuse derived duel). These waste fuels often contain more alkali and chlorine than does biomass and are therefore considered risky fuels prone to causing bed agglomeration, deposit formation, and corrosion. The aim of this study was to investigate whether a lowered bed temperature could change alkali and chlorine distribution in the boiler to reduce corrosion and deposit formation. The boiler used was designed for a bed temperature in the range of 850–900 °C, which in this investigation was decreased by approximately 150 °C. Data were collected through deposit measurements and solid sampling. The lowered bed temperature resulted in reduced demand for fresh sand, decreased agglomeration, and reduced rates of deposit formation.
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| 40. |
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| 41. |
- Shen, L. H., et al.
(författare)
-
Biomass mixing in a fluidized bed biomass gasifier for hydrogen production
- 2007
-
Ingår i: Chemical Engineering Science. - : Elsevier BV. - 0009-2509. ; 62:1-2, s. 636-643
-
Tidskriftsartikel (refereegranskat)abstract
- To investigate the biomass mixing in the bubbling fluidized bed gasifier, a digital image processing based technique is developed in the paper. Red wooden balls are used as tracer particles to study biomass mixing in a two-dimensional fluidized bed gasifier. The experimental results show a high degree of biomass mixing in the vertical direction in the bed, whereas horizontal mixing in the bottom zone is found to be relatively limited. Along the vertical direction of the bed, a more uniform distribution of biomass particles is found at a low superficial velocity than at a high superficial velocity. With respect to lateral mixing, the biomass concentration in the center increases with the superficial velocity, whereas it decreases in the wall region. The biomass concentration in the bottom region decreases with the superficial velocity, but increases in the upper region of the bed. (c) 2006 Elsevier Ltd. All rights reserved.
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| 42. |
- Sikström, Fredrik, 1971-, et al.
(författare)
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Tools for simulation based fixture design to reduce deformation in advanced fusion welding
- 2008
-
Ingår i: Intelligent Robotics and ApplicationsLecture Notes in Computer Science Volume 5315, 2008. - Berlin, Heidelberg : Springer. ; , s. 398-407
-
Konferensbidrag (refereegranskat)abstract
- The traditional fusion welding and fixture simulations are performed using advanced finite element simulation tools, commonly used are e.g. MSC.Marc, ANSYS, ABACUS and COMSOL Multiphysics. These simulations are made one at a time and separately due to heavy calculation load for each case. Such an approach does not give a full description of the integrated work piece and fixture behaviour. We propose a strategy to decrease the computational time and solve the problem accurately enough for industrial needs. Focus of the simulation result is on residual deformation. The work piece is a simplified component composed by metal sheets, and rigid and loose clamping was investigated. Simulation results give the size of forces and deformations in the clamped edge. Deformation measurements are performed using 3D-scanning of the work piece after cooling and released from fixture, same situation as in the FE-simulations. The proposed strategy has shown to be useful and is industrially competitive due to reduced engineering manpower, computation time, and need for practical experiments. The strategy is to use full off-line programming where computer aided robotics for weld sequencies is integrated with finite element modelling in order to obtain weld parameters and fixture design.
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| 43. |
- Sjolander, KB, et al.
(författare)
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Evaluation of serological methods for diagnosis of Puumala hantavirus infection (nephropathia epidemica)
- 1997
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Ingår i: Journal of clinical microbiology. - : American Society for Microbiology. - 0095-1137 .- 1098-660X. ; 35:12, s. 3264-3268
-
Tidskriftsartikel (refereegranskat)abstract
- Nephropathia epidemica (NE), Puumala (PUU) virus infection, is a febrile disease which is commonly associated with acute renal impairment. To differentiate NE from other acute febrile illnesses, a rapid and reliable serological diagnosis is important, and a number of different protocols have recently been introduced. In the present report we describe a comparative evaluation of six PUU virus immunoglobulin M (IgM) and seven IgG enzyme-linked immunosorbent assay (ELISA) protocols based on native, Escherichia coli-expressed, or baculovirus-expressed nucleocapsid protein (N). Neutralization and immunofluorescence assays were included for comparison. Equally high sensitivities and specificities were obtained with three mu-capture-based IgM ELISAs using native, baculovirus-expressed, and E. coli-expressed N antigens, respectively, and by an ELISA based on purified E. coli-expressed full-length N adsorbed to solid phase. The assays based on truncated amino-terminal N proteins, including a commercially available PUU virus IgM ELISA, all showed lower sensitivities. For detection of PUU virus-specific IgG, ELISAs based on monoclonal antibody-captured native or baculovirus-expressed N antigens showed optimal sensitivities and specificities, while the assays based on E. coli-expressed N did not detect all PUU virus IgG-positive serum samples. A commercially available PUU virus IgG ELISA based on E. coli-expressed amino-terminal N showed a significantly lower sensitivity than those of all other IgG assays.
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| 44. |
- Squillaci, Linda, et al.
(författare)
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Extending powder particle size distribution of laser powder bed fusion Ti-6Al-4V : investigation of single tracks and multilayer experiments
- 2023
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper explores the effects of varying process parameters (i.e., laser power, laser scanning speed, hatch distance) on the characteristics of single tracks, triple tracks and cubes, in order to provide answers to Research Question 1. A full factorial DoE approach was adopted to produce the experiments. Data was extracted from different sources to find correlations between tracks and multilayer geometries. A digital microscope was used to obtain height profiles, whilst polished/etched cross sections cut parallel to the build direction were imaged using a LOM to obtain measurements of track height, width, melt pool depth, subsurface porosity and residual defect content in cubes. Track height was found to exceed the recoated value of 70μm for both single and triple tracks. The width of single tracks showed a clear upward trend when displayed against VED, showing a lateral expansion as energy input increased. It was also revealed that single tracks expand laterally as they grow above the substrate, indicating swelling. The melt pool depth showed a steady upward trend when plotted against LED, though less systematic than track width. A martensitic microstructure was detected, with hierarchical α’ needles growing at prescribed crystallographic directions within vertical prior-β grains. A large portion of spatter particles and unmelted powder granules were detected on the substrate and tracks, with many accumulating on the side of the tracks forming a denudation zone.
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| 45. |
- Steffenburg-Nordenström, Joachim, 1962-
(författare)
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Process chain simulation of forming, welding and heat treatment of Alloy 718
- 2017
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Manufacturing of aero engine components requires attention to residual stress and final shape of the product in order to meet high quality product standards.This sets very high demands on involved manufacturing steps to meet design requirements. Simulation of manufacturing processes can therefore be animportant tool to contribute to quality assurance.The focus in this work is on simulation of a manufacturing process chain comprising of sheet metal forming, welding and a stress relief heat treatment.Simulation of sheet metal forming can be used to design a forming tool design that accounts for the material behaviour, e.g. spring back, and avoid problems such as wrinkling, thinning and cracking. Moreover, the simulation can also show how the material is stretched and work hardened. The residual stresses after forming may be of local character or global depending on the shape that is formed. However, the heat affected zone due to welding is located near the weld.The weld also causes large residual stresses with the major component along the weld. It is found that the magnitude of the residual stresses after welding is affected by remaining stresses from the previous sheet metal forming. The final stress relieve treatment will relax these residual stresses caused by e.g. forming and welding. However, this causes additional deformations.The main focus of this study is on how a manufacturing process step affects the subsequent step when manufacturing a component of the nickel-based super alloy 718. The chosen route and geometry is a simplified leading edge of an exhaust case guide vane. The simulations were validated versus experiments. The computed deformations were compared with measurements after each manufacturing step. The overall agreement between experiments and measurement was good. However, not sufficiently accurate considering the required tolerance of the component. It was found from simulations that the residual stresses after each process affects the subsequent step. After a complete manufacturing process chain which ends with a stress relief heat treatment the residual stresses were not negligible. VIII Special experiments were performed for studying the stress relief in order to understand how the stresses evolve through the heat treatment cycle during relaxation. It was found that the stresses were reduced already during the beginning of the heating up sequence due to decreasing Young´s modulus and yield stress with increasing temperature. Relaxation due to creep starts when a certain temperature was reached which gave a permanent stress relief.
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| 46. |
- Ström, Henrik, 1981, et al.
(författare)
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Advanced modeling of the combustion process in fixed beds to enable a biomass based EFGT concept with high combustion stability and low alkali related deposit problems
- 2017
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Ingår i: Small-scale BM based CHP Final project report (ed: I. Obernberger). ; , s. 11-13
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Electricity generation from solid biomass is mainly realised in combustion based medium and large-scale CHP plants (> 200 kWel). Especially in large-scale systems the limited heat demand often reduces the total plant efficiencies. In order to gain a maximum utilisation of the biomass fuel power, a fully heat controlled operation is definitely of advantage. Moreover, biomass is a locally available energy source and should therefore preferably be utilised in decentralised applications due to transport and logistic reasons. These arguments clearly support the idea of making the large electricity production potential from small-scale biomass heating systems in Europe available.So far no technologically sound (in terms of efficiency and reliability) and economically affordable micro and small-scale biomass CHP technologies are available. Therefore, the project aimed at the further development and test of new CHP technologies based on small-scale biomass combustion in the electric capacity range between some W and 100 kW, based on basic research and development work already performed for promising new technologies and aimed at the achievement of a technological level which allows a first commercial demonstration after the end of the project.Due to the high diversity regarding thermal capacities and applications, the project focused on three CHP concepts suitable for different types and sizes of small-scale biomass combustion systems.Pellet stoves with a thermoelectric generator (TEG): The pellet stove with TEG is suitable for stove owners who want to cover their need for auxiliary energy by own electricity production and thereby facilitate grid-independent operation. With a TEG heat is directly converted into electricity. The system is a wear- and maintenance-free as well as noiseless technology and thus ideally suitable for applications in living rooms. The electricity produced by the TEG system is stored in an accumulator and covers the energy demand for operation and start-up of the pellet stove. The surplus electricity produced can be used to charge mobile phones or other small consumers via an USB-port. In addition, due to the water cooling system of the TEG, a second living room can be heated by the new technology. Within the project appropriate system components have been selected and two testing plants have been constructed, manufactured, tested and optimised. The electricity demand of the pellet stove could be reduced by more than 50% and the electricity production of the TEG has been optimised by adjusting the TEG position and cooling system. Market introduction is planned within the next two years.Small-scale biomass boilers with a micro-ORC process: With a thermal power of 10 to 30 kWth, residential/public buildings or micro-grids can be heated by the new micro-ORC. The electric output of 0.4 to 1.3 kWel is suitable to cover the base electricity demand of the customers. To achieve high electric efficiencies a high temperature difference between input and output is needed. Thus, the micro-ORC system is especially suitable for customers with low temperature heating systems (e.g. floor heating). The micro-ORC has a very compact design and can be directly mounted in the boiler room. Due to the add-on solution only minor adaptations of the biomass boiler are needed and thus, in addition to new installations of biomass boilers with the micro-ORC also retrofitting of existing boilers becomes possible. Within the project the new micro-ORC technology has been tested and optimised. Currently, tests with the final design of the ORC are ongoing, a market introduction is planned within 2018.High temperature heat exchanger (HT-HE) for an externally fired gas turbine (EFGT): With a thermal capacity of about 1,500 kWth the CHP technology based on a biomass boiler and an EFGT is suitable for district heating systems (base load), or process heat consumers (e.g. wood manufacturing industry). The electricity produced by the gas turbine (up to 100 kWel) can be used to cover the own electricity consumption of a company and/or fed into the grid. Within the project the HT-HE which represents the core component of the system has been designed, constructed and successfully tested at flue gas temperatures up to 900°C. Thus, appropriate guidelines for a compact design of the HT-HE and recommendations have been worked out to minimize thermal stresses as well as ash related problems regarding ash deposit formation and high temperature corrosion. Furthermore, different concepts for the overall EFGT system have been worked out and evaluated. A first testing plant shall be installed and assessed within the next two years.
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| 47. |
- Ström, Henrik, 1981, et al.
(författare)
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Experimental and Numerical Investigations of Ash Behaviour in Fixed-Bed Combustion of Woody Biomass Pellets
- 2017
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Ingår i: Proceedings of the Nordic Flame Days 2017, Stockholm, Sweden.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Combustion of woody biomass in a fixed-bed configuration could play an important role in the development of small-scale combined-heat-and-power solutions, such as externally-fired micro-gas turbines. However, many challenges still remain with regard to the complexity of maintaining high availability with an acceptable fuel flexibility, as ash transformations in the fuel bed can cause serious problems for the robustness of the process as well as for downstream components. In this work, fixed-bed combustion of two woody biomasses of different ash contents is studied experimentally and numerically in an attempt to advance the understanding of ash-related disturbances. A mathematical model for fixed-bed conversion of biomass is extended to account for ash transformations on both the single-pellet level and the bed level, and the predictions from this model are assessed against the experimental results. The agreement between simulations and experiments is good for low air-flow rates, whereas additional considerations are needed for air-flow rates closer to the stoichiometric limit. Although there was no catastrophic slagging observed in the experiments, the capabilities of the model to describe effects of such slagging, down to only slightly reduced combustion rates due to milder ash transformations, are confirmed by the simulations.
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| 48. |
- Ström, Henrik, 1981, et al.
(författare)
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Experimental and Numerical Investigations of Ash Behaviour in Fixed-Bed Combustion of Woody Biomass Pellets
- 2018
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Ingår i: Industrial Combustion Journal. - 2075-3071.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Combustion of woody biomass in a fixed-bed configuration could play an important role in the development of small-scale combined-heat-and-power solutions, such as externally-fired micro-gas turbines. However, many challenges still remain with regard to the complexity of maintaining high availability with an acceptable fuel flexibility, as ash transformations in the fuel bed can cause serious problems for the robustness of the process as well as for downstream components. In this work, fixed-bed combustion of two woody biomasses of different ash contents is studied experimentally and numerically in an attempt to advance the understanding of ash-related disturbances. A mathematical model for fixed-bed conversion of biomass is extended to account for ash transformations on both the single-pellet level and the bed level, and the predictions from this model are assessed against the experimental results. The agreement between simulations and experiments is good for low air-flow rates, whereas additional considerations are needed for air-flow rates closer to the stoichiometric limit. Although there was no catastrophic slagging observed in the experiments, the capabilities of the model to describe effects of such slagging, down to only slightly reduced combustion rates due to milder ash transformations, are confirmed by the simulations.
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| 49. |
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| 50. |
- Sundh, Henrik, 1976, et al.
(författare)
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Translocation of infectious pancreatic necrosis virus across the intestinal epithelium of Atlantic salmon (Salmo salar L.)
- 2011
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Ingår i: Aquaculture. - 0044-8486. ; 321:1-2, s. 85-92
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Tidskriftsartikel (refereegranskat)abstract
- Infectious pancreatic necrosis virus (IPNV) is a viral disease that afflicts salmon aquaculture worldwide. Transmission of viral diseases may occur via the skin, gills or intestine but the main entry route for IPNV is not known. However, acute inflammation of the intestinal mucosa is an early symptom in infected fish which suggests transmission through an oral route. The main aim of this study is to determine if IPNV can translocate across the intestinal epithelium. It also aims to investigate how acute and chronic IPNV exposure as well as stress affects the physiological barrier functions of the intestinal epithelium. Possible translocation of IPNV across the intestinal mucosa as well as effects of virus on intestinal barrier function was measured in vitro, using the Ussing chamber technique. IPNV was translocated across both proximal and distal segments of the intestine with a higher rate in distal compared to proximal intestine. The translocated virions caused cytopathic effects on cultured Chinook salmon embryo cells (CHSE-214), proving viability and high virulence. Intestinal barrier function was disturbed as assessed by increased permeability for 14C-mannitol in the proximal region after exposure to IPNV in vitro. The same pattern was observed after prolonged exposure to IPNV in vivo. Further, the intestine appeared to respond with an increased mucus secretion, as indicated through increased TER after prolonged IPNV exposure. No additional effects of cortisol implantation on barrier function were observed. In conclusion, this study demonstrates that both proximal and distal intestine can be used by IPNV as a route of infection and that the intestinal barrier function is negatively affected by exposure to IPNV.
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