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  • 101.
    Gupta, Apoorv
    KTH, Skolan för kemivetenskap (CHE).
    Vätgaslagring, -distribution och -rening2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Rising greenhouse gas (GHG) emissions is a major cause of concern today. The primary source of energy all over the globe is fossil fuels, a non-renewable source of energy that is expected to get exhausted in the next 60-100 years. Damage to environment cannot be easily reversed but the initial steps are to reduce the damage done.  Other alternative cleaner sources of energy are being looked into as viable options to replace fossil fuels. The objective of this study is to identify options for using hydrogen as an energy carrier in the future with a major focus on the transportation sector. This project is limited to theoretical study looking into the options for hydrogen storage and distribution. Gaseous and liquid hydrogen storage have been looked in to thoroughly and are far from meeting Department of Energy, USA, (DOE) ultimate targets for automobile fleets, hence a shift to other storage options is imminent. Metal hydride storage is believed to be the upcoming technology as the mid-term solution to storage issues and hence is given a lot of attention in this project. On-board storage in metal hydrides is studied and it can be concluded that no metal hydride known to us today is capable of satisfying the DOE ultimate targets. Finally, the study ends with options accessible to AGA to purchase hydrogen within Sweden and how they can be cleaned to meet the fuel cell gas purity requirements. 

  • 102.
    GUTIÉRREZ VARONA, PABLO
    KTH, Skolan för kemivetenskap (CHE).
    Experimental testing of catalysts for hybrid combustion2013Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    A hybrid heating system for the vehicle industry was customized at the Chemical Engineering and Technology unit, KTH School of Chemical Science and Engineering. This work was performed by Pablo Gutiérrez Varona as his final project work and was carried out in co-operation between KTH-Royal Institute of Technology, Universitat de Barcelona, and ReformTech Heating Technologies Sweden AB.

    The aim of the thesis was to evaluate the performance of three different catalysts (an uncoated cordierite, a lanthanum manganese hexaaluminate, and palladium over alumina) for a 5 kW adiabatic power hybrid heater developed by ReformTech Heating Technologies Sweden AB. Three different catalysts were tested for the combustion of diesel. The catalysts performances were observed for a wide working range of air-to-fuel ratios in order to find an optimum operation point. The catalysts were evaluated based on the emissions and temperatures profiles.

    The most promising results for this application was the Pd-Al2O3 catalyst, 2 CO ppm and 37 NOx ppm for a lambda of 2,3.

  • 103.
    GÓMEZ AGUILERA, Miguel
    KTH, Skolan för kemivetenskap (CHE).
    Metaloxid katalysatorer för oxidering av kolmonoxid och förbränning av sot2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The aim of this work was to manufacture and test non noble metal catalysts for CO oxidation and soot combustion. The feeding gases consist in the products of the combustion diesel in a Reformtech heater. These gases contain CO, CO2, H2O as well as small amounts of NOx and hydrocarbons.

    Two different catalysts were prepared for CO oxidation, based on cobalt oxide supported on ceria. 12Co/CeO2 with 12% weight of cobalt and 15CoOx/CeO2 with 15%. The first one was prepared by impregnation of cobalt nitrates in cerium oxide support; the second one was prepared by co-precipitation of cobalt and cerium nitrates.

    Another catalyst called 12Co4.5K/CeO2, with 12% cobalt and 4.5% potassium, was made for the simultaneous combustion of soot and oxidation of CO. The base also consisted in cobalt oxide supported on ceria, but with the addition of potassium which could stabilize the cobalt oxide particles.

    Both co-precipitation and impregnation methods gave the desired catalyst structure in the CO oxidation catalysts and both catalysts (12Co/CeO2 and 15CoOx/CeO2) showed activity. Nevertheless, the activity was lower than desired due to low surface area and mass transfer limitations. The catalysts also deactivated in less than three hours on stream, probably due to poisoning.

    The co-precipitation method for the 12Co4.5K/CeO2 catalyst gave the desired cobalt and cerium oxides, but no conclusion can be drawn regarding potassium since it was not shown in the XRD tests.

    The catalyst for both CO oxidation and soot combustion (12Co4.5K/CeO2) showed no activity for any of the reactions. Nevertheless, the tests performed to test the soot combustion ability were not conclusive and should be improved in future studies.

  • 104.
    Göransson, Kristina
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för tillämpad naturvetenskap och design.
    Söderlind, Ulf
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för tillämpad naturvetenskap och design.
    Zhang, Wennan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för tillämpad naturvetenskap och design.
    Tar/CH4 Reforming by Catalytic Bed Materials in a Biomass Fluidised Bed Gasifier2012Inngår i: 20th European Biomass Conference & Exhibition: Proceedings of the International Confernce held in Milano, Italy, 18 - 22 June 2012, 2012Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    A study on in-bed catalytic material reforming of tar/methane (CH4) has been performed in the 150 kW allothermal biomass gasifier at Mid Sweden University (MIUN). The MIUN gasifier, built for research on synthetic fuel production, is a dual fluidised bed gasifier (DFBG). The syngas for automotive fuels synthesis has a strict specification of impurities. The biggest challenge for biomass fluidised-bed gasification is the reforming of tars and CH4. Internal reforming should be considered before downstream reforming. The MIUN gasifier has a unique design suitable for in-bed tar/CH4 catalytic reforming and continuously internal regeneration of the reactive bed material. The experimental tests are carried out in three cases: 1) basic condition with silica sand (no catalytic activity), 2) calcinated olivine, and 3) Fe-impregnated olivine (10%wtFe/Olivine Catalyst). The measurement results have been evaluated by comparing tar/CH4 content in the syngas from the gasifier operated under different operation conditions. These results in BFB mode have initiated the ongoing investigations of the catalytic effects and regeneration in DFB mode. It can be concluded that the Fe-impregnated olivine showed a surprising low reactivity for tar and CH4 reforming in the BFB model. 

  • 105.
    H. Moud, Pouya
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Catalytic Conversion of Undesired Organic Compounds to Syngas in Biomass Gasification and Pyrolysis Applications2017Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Reliable energy supply is a major concern and crucial for development of the global society. To address the dependency on fossil fuel and the negative effects of this reliance on climate, there is a need for a transition to cleaner sources. An attractive solution for replacing fossil-based products is renewable substitutes produced from biomass. Gasification and pyrolysis are two promising thermochemical conversion technologies, facing challenges before large-scale commercialization becomes viable. In case of biomass gasification, tar is often and undesired by-product. An attractive option to convert tar into syngas is nickel-based catalytic steam reforming (SR). For biomass pyrolysis, catalytic SR is in early stages of investigation as a feasible option for bio-crude conversion to syngas.

    The focus of the thesis is partly dedicated to describe research aimed at increasing the knowledge around tar reforming mechanisms and effect of biomass-derived impurities on Ni-based tar reforming catalyst downstream of gasifiers. The work focuses on better understanding of gas-phase alkali interaction with Ni-based catalyst surface under realistic conditions. A methodology was successfully developed to enable controlled investigation of the combined sulfur (S) and potassium (K) interaction with the catalyst. The most striking result was that K appears to lower the sulfur coverage and increases methane and tar reforming activity. Additionally, the results obtained in the atomistic investigations are discussed in terms of naphthalene adsorption, dehydrogenation and carbon passivation of nickel.

    Furthermore, the thesis describes research performed on pyrolysis gas pre-conditioning at a small-industrial scale, using an iron-based catalyst. Findings showed that Fe-based materials are potential candidates for application in a pyrolysis gas pre-conditioning step before further treatment or use, and a way for generating a hydrogen-enriched gas without the need for bio-crude condensation.

  • 106.
    H. Moud, Pouya
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik. KTH.
    Kantarelis, Efthymios
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    J. Andersson, Klas
    Engvall, Klas
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Biomass pyrolysis gas conditioning over an iron-based catalyst for mild deoxygenation and hydrogen production2017Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 211, s. 149-158Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    Bio-crude is a renewable source for production of valuable energy carriers. Prior to its utilization, a conditioning step of the raw pyrolysis gas can be beneficial before the bio-crude is converted via catalytic hydrodeoxygenation (HDO) into liquid hydrocarbon products, or via steam reforming (SR) to synthesis gas/hydrogen. An experimental small industrial scale study for the chemistry of atmospheric pressure pyrolysis gas conditioning resulting in bio-crude deoxygenation and a hydrogen-rich gas using an iron-based catalyst without addition of hydrogen or steam is presented and discussed. Following a short catalyst stabilization period with fluctuating bed temperatures, the catalyst operated near 450°C at a space velocity of 1100 h-1 for 8 hours under stable conditions during which no significant catalyst deactivation was observed. Experimental results indicate a 70-80% reduction of acetic acid, methoxy phenols, and catechol, and a 55-65% reduction in non-aromatic ketones, BTX, and heterocycles. Alkyl phenols and phenols were least affected, showing a 30-35% reduction. Conditioning of the pyrolysis gas resulted in a 56 % and a 18 wt% increase in water and permanent (dry) gas yield, respectively, and a 29 % loss of condensable carbon. A significant reduction of CO amount (-38 %), and production of H2 (+1063 %) and CO2 (+36 %) over the catalyst was achieved, while there was no or minimal change in light hydrocarbon content. Probing the catalyst after the test, the bulk phase of the catalyst was found to be magnetite (Fe3O4) and the catalyst exhibited significant water gas shift (WGS) reaction activity. The measured gas composition during the test was indicative of no or very limited Fischer-Tropsch (FT) CO /CO2 hydrogenation activity and this infers that also the active surface phase of the catalyst during the test was Fe-oxide, rather than Fe-carbide. The results show that iron-based materials are potential candidates for application in a pyrolysis gas pre-conditioning step before further treatment or use, and a way of generating a hydrogen-enriched gas without the need for bio-crude condensation.

  • 107.
    Hagberg, Johan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Carbon Fibres for Multifunctional Lithium-Ion Batteries2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The transportation industry today faces many challenges because of the rapid movement towards electrification. One major challenge is the weight of the battery, which limits the effectiveness of the vehicles. One of the possible routes to reduce the weight on a system-level is introducing structural batteries, batteries that simultaneously storeenergy and hold a mechanical load. Placing these batteries in a load-bearing part of the structure reduces weight and increases effectiveness on a system level. Carbon fibres are especially suited for structural batteries because of the high performance as reinforcement material in a polymer composite, as well as the ability to insert lithium to function as negative electrodes in batteries.

    Another field that has attracted attention the latest years is flexible batteries due to the emerging of flexible displays and wearable electronics. Carbon fibres can be a suitable material in flexible batteries due to the good conductivity, mechanical integrity and ability to forman integrated flexible film with cellulose nanofibrils (CNF) as binder.

    This thesis focuses on the usage of carbon fibres in structural and flexible batteries. Lignin based and commercial carbon fibres are evaluated as negative electrodes using a combination of electrochemical methods, material characterization and mechanical testing. Further, the diffusion is characterized using nuclear magnetic resonance spectroscopy, revealing an inequality of axial and radial diffusion in carbon fibres. The carbon fibres with a largely disordered structure show most promise as a negative electrode, with a capacity similar to graphite and having a high coulombic efficiency.

    Carbon fibres used as current collectors are evaluated as well, both continuous LiFePO4 coated carbon fibres with electrophoretic deposition for structural positive electrode applications and chopped carbonfibres bounded by CNF as a layer in a flexible electrode. The LiFePO4 coated carbon fibres show promise as a structural electrode with moderatecapacity, high coulombic efficiency, good rate performance and good adhesion between fibres and coating. The flexible electrodes with carbon fibres as current collectors perform well with a high capacity, good rate performance, low weight and high flexibility. The electrodes withstand bending for 4000 times without any performance degradation.

  • 108.
    Hagberg, Johan
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Maples, Henry A.
    Polymer and Composite Engineering (PaCE) Group, Institute of Materials Chemistry and Research, Faculty of Chemistry, University of Vienna, Währinger Straße 42, A-1090 Vienna, Austria .
    Alvim, Kayne S. P.
    Polymer and Composite Engineering (PaCE) Group, Institute of Materials Chemistry and Research, Faculty of Chemistry, University of Vienna, Währinger Straße 42, A-1090 Vienna, Austria .
    Xu, Johanna
    Polymeric Composite Materials, Department of Engineering Sciences and Mathematics, Luleå University of Technology, SE-97187 Luleå, Sweden .
    Johannisson, Wilhelm
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Bismarck, Alexander
    Polymer and Composite Engineering (PaCE) Group, Institute of Materials Chemistry and Research, Faculty of Chemistry, University of Vienna, Währinger Straße 42, A-1090 Vienna, Austria ; Polymer and Composite Engineering (PaCE) Group, Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK .
    Zenkert, Dan
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Lindbergh, Göran
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Lithium iron phosphate coated carbon fiber electrodes for structural lithium ion batteries2018Inngår i: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 162, s. 235-243Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A structural lithium ion battery is a material that can carry load and simultaneously be used to store electrical energy. We describe a path to manufacture structural positive electrodes via electrophoretic deposition (EPD) of LiFePO4 (LFP), carbon black and polyvinylidene fluoride (PVDF) onto carbon fibers. The carbon fibers act as load-bearers as well as current collectors. The quality of the coating was studied using scanning electron microscopy and energy dispersive X-ray spectroscopy. The active electrode material (LFP particles), conductive additive (carbon black) and binder (PVDF) were found to be well dispersed on the surface of the carbon fibers. Electrochemical characterization revealed a specific capacity of around 60–110 mAh g−1 with good rate performance and high coulombic efficiency. The cell was stable during cycling, with a capacity retention of around 0.5 after 1000 cycles, which indicates that the coating remained well adhered to the fibers. To investigate the adhesion of the coating, the carbon fibers were made into composite laminae in epoxy resin, and then tested using 3-point bending and double cantilever beam (DCB) tests. The former showed a small difference between coated and uncoated carbon fibers, suggesting good adhesion. The latter showed a critical strain energy release rate of ∼200–600 J m−2 for coated carbon fibers and ∼500 J m−2 for uncoated fibers, which also indicates good adhesion. This study shows that EPD can be used to produce viable structural positive electrodes.

  • 109. Hagberg, Johan
    et al.
    Morozov, Evgeny
    Furo, Istvan
    KTH, Tidigare Institutioner (före 2005), Kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Centrum för Industriell NMR-teknik. KTH, Tidigare Institutioner (före 2005), Fysik.
    Lindbergh, Göran
    KTH, Tidigare Institutioner (före 2005), Kemiteknik.
    Inequality of Axial and Radial Diffusion of Inserted Lithium Ions in Carbon Fibres as Revealed by Pulsed-Field Gradient NMRManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Nuclear Magnetic Resonance (NMR) studies has characterized lithiated polyacrylonitrile-based carbon fibres. The local dynamics has been probed by spin-lattice and spin-spin relaxation measurements and long range motion (diffusion) by pulsed field gradient NMR. Differences in fibre orientation was investigated by axially and radially aligned samples. One single peak related to lithium insertion was observed around 12-25 ppm, increasing with lithium load. A small effect of fibre orientation was observed on the relaxation behavior. The diffusion though was found to be around three times higher in axial compared to radial direction of the carbon fibres. This is believed to be due to the microstructure, with oriented crystallites along the carbon fibres contributing more in the axial direction to the average measured diffusion. The diffusion coefficients varied from around 10-12 m2/s to 4·10-12 m2/s, increasing with lithium load.

  • 110.
    Han, Shaobo
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Laboratoriet för organisk elektronik. Linköpings universitet, Tekniska fakulteten.
    Alvi, Naveed
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Granlof, Lars
    RISE Bioecon, Sweden.
    Granberg, Hjalmar
    RISE Bioecon, Sweden.
    Berggren, Magnus
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Laboratoriet för organisk elektronik. Linköpings universitet, Tekniska fakulteten.
    Fabiano, Simone
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Laboratoriet för organisk elektronik. Linköpings universitet, Tekniska fakulteten.
    Crispin, Xavier
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Laboratoriet för organisk elektronik. Linköpings universitet, Tekniska fakulteten.
    A Multiparameter Pressure-Temperature-Humidity Sensor Based on Mixed Ionic-Electronic Cellulose Aerogels2019Inngår i: ADVANCED SCIENCE, ISSN 2198-3844, Vol. 6, nr 8, artikkel-id 1802128Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Pressure (P), temperature (T), and humidity (H) are physical key parameters of great relevance for various applications such as in distributed diagnostics, robotics, electronic skins, functional clothing, and many other Internet-of-Things (IoT) solutions. Previous studies on monitoring and recording these three parameters have focused on the integration of three individual single-parameter sensors into an electronic circuit, also comprising dedicated sense amplifiers, signal processing, and communication interfaces. To limit complexity in, e.g., multifunctional IoT systems, and thus reducing the manufacturing costs of such sensing/communication outposts, it is desirable to achieve one single-sensor device that simultaneously or consecutively measures P-T-H without cross-talks in the sensing functionality. Herein, a novel organic mixed ion-electron conducting aerogel is reported, which can sense P-T-H with minimal cross-talk between the measured parameters. The exclusive read-out of the three individual parameters is performed electronically in one single device configuration and is enabled by the use of a novel strategy that combines electronic and ionic Seebeck effect along with mixed ion-electron conduction in an elastic aerogel. The findings promise for multipurpose IoT technology with reduced complexity and production costs, features that are highly anticipated in distributed diagnostics, monitoring, safety, and security applications.

  • 111.
    Hansson, Björn
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper.
    Evaluation of Compression Testing and Compression Failure Modes of Paperboard: Video analysis of paperboard during short-span compression and the suitability of short- and long-span compression testing of paperboard2013Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The objectives of the thesis were to find the mechanisms that govern compression failures in paperboard and to find the link between manufacturing process and paperboard properties. The thesis also investigates two different test methods and evaluates how suitable they are for paperboard grades. The materials are several commercial board grades and a set of hand-formed dynamic sheets that are made to mimic the construction of commercial paperboard. The method consists of mounting a stereomicroscope on a short-span compression tester and recording the compression failure on video, long-span compression testing and standard properties testing. The observed failure modes of paperboard under compression were classified into four categories depending on the appearance of the failures. Initiation of failure takes place where the structure is weakest and fiber buckling happens after the initiation, which consists of breaking of fiber-fiber bonds or fiber wall delamination. The compression strength is correlated to density and operations and raw materials that increase the density also increases the compression strength. Short-span compression and Long-span compression are not suitable for testing all kinds of papers; the clamps in short-span give bulky specimens an initial geometrical shape that can affect the given value of compression strength. Long-span compression is only suitable for a limited range of papers, one problem with too thin papers are low wavelength buckling. 

  • 112.
    Hasegawa, Yuki
    et al.
    Saitama Univ, Japan.
    Lloyd Spetz, Anita
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Sensor- och aktuatorsystem. Linköpings universitet, Tekniska fakulteten.
    Puglisi, Donatella
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Sensor- och aktuatorsystem. Linköpings universitet, Tekniska fakulteten.
    Ethylene Gas Sensor for Evaluating Postharvest Ripening of Fruit2017Inngår i: 2017 IEEE 6TH GLOBAL CONFERENCE ON CONSUMER ELECTRONICS (GCCE), IEEE , 2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    It is widely known that ethylene treatment is an effective method for postharvest handling of fruit. In this study, we employed a field effect transistor based on silicon carbide (SiC-FET) gas sensor for detecting ethylene produced from fruits. The characteristics of the sensor was evaluated regarding several parameters. The selectivity and sensitivity of SiC-FET sensors can be controlled toward a few target gases by changing the operating temperature, gate material and material structure. We studied an iridium and a platinum gated SiC-FET sensors and characterized the sensing of these for different ethylene concentrations as the target gas at different operating temperatures. The results showed that the iridium gated SiC-FET sensor has high sensitivity to ethylene, and the highest response is achieved at 200 degrees C.

  • 113.
    Hellström, Lisbeth
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Energy Efficiency Improvement Potential in TMP and CTMP by Axial Precompression of Wood During ChippingManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    It has recently been shown that there is a possibillity to improve the energy efficiency during first stage TMP (thermomechanical pulp) refining by performing the wood chipping so as to increase the compressive damage in the chips and hence breaking up the wood structure. The parameter that was varied was the spout angle i.e. the angle between the fibre direction of the wood specimen and the cutting plane. In this article is investigated how the refining of chips produced at two different spout angles i.e. 30 and 50, influenced the properties of CTMP (chemithermomechanical pulp). It was found that the specific energyinput for a certain CSF (Canadian Standard Freeness) value was lower for chips produced at the spout angle of 50 but that the addition of chemicals (NaHSO3) to the dilution water had no influence on the specific energy value for a given CSF value. However, the tensile index and specific light scattering coefficient was substantially higher for handsheets made of the pulp refined from chips produced at the spout angle 50 and with NaHSO3 added compared to handsheets from pulp made from 30 and 50 chips without chemicals added.

  • 114.
    Hellström, Lisbeth
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för tillämpad naturvetenskap och design.
    Carlberg, Torbjörn
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för tillämpad naturvetenskap och design.
    Engstrand, Per
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för tillämpad naturvetenskap och design.
    Gradin, Per
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för tillämpad naturvetenskap och design.
    Gregersen, Øyvind
    Department for Chemical Engineering, NTNU, Norway.
    Evaluation Of Collimated Chipping Technology For Reducing Energy Consumption In Mechanical Pulping2012Inngår i: Journal of Science & Technology for Forest Products and Processes, ISSN 1927-6311, E-ISSN 1927-632X, Vol. 2, nr 3, s. 6-9Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    It has recently been shown that the energy efficiency during first-stage TMP (thermo-mechanical pulp) refining can be improved using amodified chipping method (collimated chipping), where the angle between the fibre direction of the wood specimen and the cutting plane is increased. This paper reports the differences in properties of TMP refined from wood chips produced at two different spout angles, 30° and 50°, with and without the addition of sodium bisulphite (NaHSO3) to the dilution water. It was found that the specific energy input for a certain CSF (Canadian Standard Freeness) value was lower for chips produced at spout 50°, but that the addition of chemicals to the dilution water had no influence on the specific energy value for a given CSF value. However, the tensile index and specific light-scattering coefficient were substantially higher for handsheets made from the pulp refined from chips produced at spout angle 50° and with NaHSO3 added compared to handsheets from pulp made from 30° and 50° chips without chemicals added.

  • 115.
    Hellström, Lisbeth
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Engstrand, Per
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    The effect on the energy consumption in mechanical pulping of different wood chipping conditions2010Inngår i: Proceedings of 7th International Seminar of Fundamental Mechanical Pulp Research (IFMPRS 2010), 2010, s. 124-126Konferansepaper (Annet vitenskapelig)
  • 116.
    Hellström, Lisbeth
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Gradin, Per
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Engstrand, Per
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Gregersen, Øyvind
    Department for Chemical Engineering, NTNU, Trondheim, Norway.
    Properties of wood chips for thermomechanical pulp (TMP) production as a function of spout angle2011Inngår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 65, nr 6, s. 805-809Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Spruce woodchipswere produced under well-controlled conditions in a laboratory woodchipper at spout angles of 30°, 40°, and 50° at a cutting rate of 20 m s-1 and with a nominalchip length of 25 mm. Thechips were then refined under thermomechanical pulp (TMP) conditions in a pilot refiner plant. The pulpproperties such as freeness, average fiber length, and shives content were determined and evaluated as a function of specific energy consumption. For a first stage refining and for a freeness value of 350 ml, a decrease in specific electrical energy consumption could be achieved by performing thewood chipping at a spout angle of 50° as compared to 30° which is the spout angle commonly used. A patent application regarding this method has been filed and is pending. It is realized that a freeness value is not directly indicative of any quality measure, such as, for example tensile index and light scattering coefficient but the obtained results can be interpreted to be promising. Further studies are needed regarding the impact of the modified chipping process.

  • 117.
    Hemmilä, Venla
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Zabka, Michal
    IKEA Sweden.
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Evaluation of dynamic microchamber as a quick factory formaldehyde emission control method for industrial particleboards2018Inngår i: Advances in Materials Science and Engineering, ISSN 1687-8434, E-ISSN 1687-8442, artikkel-id 4582383Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The most common formaldehyde control method for wood panels in Europe, the perforator method, measures formaldehyde content, while most of the legal requirements in the world are based on emissions. Chamber methods typically used for emission measurements require too much time to reach steady state for factory quality control. The aim of this study was therefore to investigate whether emission values of particleboards measured one day after production would be usable for quality control purposes. The correlation between 1-day and 7-day emission values was determined using a dynamic microchamber (DMC). Three industrial board types that differed in density and emission levels were used for the evaluation. The online emission measuring equipment Aero-laser AL4021 connected to the 1 m3 chamber was used to gain further information on the emission reduction behaviour of the different board types. Only the two particleboard types with higher densities showed good correlation between the 1-day and 7-day emissions. The overall results suggested that 1-day emission values can be used for factory quality control purposes; however, if the initial 1-day values are above the permitted level, extensive evaluation for each individual board type needs to be performed

  • 118.
    Henshaw Osong, Sinke
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Dahlström, Christina
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Forsberg, Sven
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Andres, Britta
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Engstrand, Per
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Norgren, Sven
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Engström, Ann-Christine
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Development of CTMP-based nanofibrillated Cellulose /nanographite composites for paper applications2015Konferansepaper (Annet vitenskapelig)
  • 119.
    Holmgren, Jonna
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström.
    Growth of TiN on WC surfaces2012Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    The growth of TiN on cemented carbide, deposited by chemical vapour deposition (CVD), was studied. Today TiN is used as a seeding layer between the cemented carbide and the following layer. Previous experiments have shown that the coverage is uneven on the cemented carbide surface showing pits with a different growth than the main part of the surface. These pits most likely occur on some of the WC surfaces. Therefore the growth and orientation relation between the two phases were examined.

    Cemented carbide specimens were deposited with TiN under two different pressures and with different deposition time to give a layer as thick as the seeding layer used in the production and one about ten times thicker to study growth after the whole surface had been covered. Two pre-treatments where used on the specimens; one which were polishing with diamond and the other where the specimens were boiled in acid to remove the binder phase and expose the WC surfaces.

    The specimens were studied using XRD and a SEM equipped with EDS and EBSD detectors. The pictures taken with SEM showed that initial growth occurred at grain boundaries and polishing scratches. It also showed that growth occurred on all surfaces, which were confirmed by EDS. Both processes showed about the same appearance in the thinner layers but very different appearance in the thicker. This was confirmed by XRD were the thinner layers showed about the same result while the thicker ones differ from one another. Thus further growth is dependent on the parameters of the CVD process and not the surface beneath.

    EBSD showed an orientation relation between TiN and WC crystals in both processes. The process at lower pressure gave much finer grains which were difficult to index with EBSD, giving results in only three points. The process at higher pressure gave coarser grains which were more easily indexed. The relations WC{0001}-TiN{110}, giving WC{101̅0}-TiN{100}, and WC{0001}-TiN{111}, giving WC{101̅0}-TiN{211}, could be seen in more than one point. These results are consistent with previous studies of the growth of TiC on WC.

    This comparison between TiC and TiN makes it possible to draw the conclusion that also Ti(C,N) should behave the same. It also shows an orientation relation that is consistent no matter what WC plane is on the surface. The poor growth and the pits depend on the growth orientation of TiN on each specific WC surface.

  • 120.
    Holmgren, Per
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Broström, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Backman, Rainer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Slag Formation during Entrained Flow Gasification: Silicon Rich Grass Fuel with KHCO3 Additive2018Inngår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 32, nr 10, s. 10720-10726Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Prediction of ash particle adherence to walls, melting, and flow properties are important for successful operation of slagging entrained flow gasifiers. In the present study, silicon-rich reed canary grass was gasified at 1000 and 1200 °C with solid KHCO3 added at 0, 1, or 5 wt % to evaluate the impact and efficiency of the dry mixed additive on slag properties. The fuel particles collided with an angled flat impact probe inside the hot reactor, constructed to allow for particle image velocimetry close to the surface of the probe. Ash deposit layer buildup was studied in situ as well as ash particle shape, size, and velocity as they impacted on the probe surface. The ash deposits were analyzed using scanning electron microscopy–energy-dispersive X-ray spectroscopy, giving detailed information on morphology and elemental composition. Results were compared to thermodynamic equilibrium calculations for phase composition and viscosity. The experimental observations (slag melting, flow properties, and composition) were in good qualitative agreement with the theoretical predictions. Accordingly, at 1000 °C, no or partial melts were observed depending upon the potassium/silicon ratio; instead, high amounts of additive and a temperature of at least 1200 °C were needed to create a flowing melt.

  • 121.
    Holmgren, Per
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Wagner, David R.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Strandberg, Anna
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Molinder, Roger
    Wiinikka, Henrik
    Umeki, Kentaro
    Broström, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Size, shape, and density changes of biomass particles during rapid devolatilization2017Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 206, s. 342-351Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Particle properties such as size, shape and density play significant roles on particle flow and flame propagationin pulverized fuel combustion and gasification. A drop tube furnace allows for experiments athigh heating rates similar to those found in large-scale appliances, and was used in this study to carryout experiments on pulverized biomass devolatilization, i.e. detailing the first stage of fuel conversion.The objective of this study was to develop a particle conversion model based on optical informationon particle size and shape transformation. Pine stem wood and wheat straw were milled and sieved tothree narrow size ranges, rapidly heated in a drop tube setup, and solid residues were characterized usingoptical methods. Different shape descriptors were evaluated and a shape descriptor based on particleperimeter was found to give significant information for accurate estimation of particle volume. The opticalconversion model developed was proven useful and showed good agreement with conversion measuredusing a reference method based on chemical analysis of non-volatilized ash forming elements.The particle conversion model presented can be implemented as a non-intrusive method for in-situ monitoringof particle conversion, provided density data has been calibrated.

  • 122.
    Holmström, Nicklas
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Wiezell, Katarina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Studying Low-Humidity Effects in PEFCs Using EIS I: Experimental2012Inngår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 159, nr 8, s. F369-F378Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A suitable electrochemical characterization technique for studying water effects at low-humidity conditions is electrochemical impedance spectroscopy (EIS). In general, an EIS spectrum for a PEFC shows one or several capacitive loops and in some situations an inductive loop at the lowest frequencies depending on operating conditions. In this study, low-humidity effects in an operating polymer electrolyte fuel cell have been investigated by using electrochemical impedance spectroscopy (EIS), with the focus on the low-frequency impedance. Measurements have been carried out using several membranes with different thicknesses at various current densities and operating conditions. At frequencies, around 1 Hz down to 5 mHz a pseudo-inductive loop was seen. The magnitude of this loop increased with thicker membranes and at lower humidities. Based on the results the pseudo-inductive loop was attributed to water transport characteristics in the membrane, where the capacitive part is attributed to drying out of the anode and parts of the membrane closest to the anode while the inductive part is attributed to rehydration of the membrane and the anode by product water from the oxygen reduction reaction on the cathode. In addition, both the magnitude and the top-frequencies of the pseudo-inductive loop were affected by the flow rate.

  • 123. Hou, Jungang
    et al.
    Sun, Yiqing
    Cao, Shuyan
    Wu, Yunzhen
    Chen, Hong
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD. KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Graphene Dots Embedded Phosphide Nanosheet-Assembled Tubular Arrays for Efficient and Stable Overall Water Splitting2017Inngår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, nr 29, s. 24600-24607Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Bifunctional electrocatalysts are highly desired for overall water splitting. Herein, the design and fabrication of three-dimensional (3D) hierarchical earth-abundant transition bimetallic phosphide arrays constructed by one-dimensional tubular array that was derived from assembling two-dimensional nanosheet framework has been reported by tailoring the Co/Ni ratio and tunable morphologies, and zero-dimensional (0D) graphene dots were embedded on Co-Ni phosphide matrix to construct 0D/2D tubular array as a highly efficient electrode in the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). On the basis of advanced merits, such as the high surface-active sites, well-dispersed graphene dots, and enhanced electron transfer capacity as well as the confinement effect of the graphene dots on the nanosheets, the integrated GDs/Co0.8Ni0.2P tubular arrays as anode and cathode exhibit excellent OER and HER performance. By use of GDs/Co0.8Ni0.2 arrays in the two-electrode setup of the device, a remarkable electrocatalytic performance for full water splitting has been achieved with a high current density of 10 mA cm-2 at 1.54 V and outstanding long-term operation stability in an alkaline environment, indicating a promising system based on nonprecious-metal electrocatalysts toward potential practical devices of overall water splitting.

  • 124.
    Hou, Jungang
    et al.
    DUT, Inst Energy Sci & Technol, KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Zhang, Bo
    DUT, Inst Energy Sci & Technol, KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Li, Zhuwei
    DUT, Inst Energy Sci & Technol, KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Cao, Shuyan
    DUT, Inst Energy Sci & Technol, KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Sun, Yiqing
    DUT, Inst Energy Sci & Technol, KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Wu, Yunzhen
    DUT, Inst Energy Sci & Technol, KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Gao, Zhanming
    DUT, Inst Energy Sci & Technol, KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Vertically Aligned Oxygenated-CoS2-MoS2 Heteronanosheet Architecture from Polyoxometalate for Efficient and Stable Overall Water Splitting2018Inngår i: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 8, nr 5, s. 4612-4621Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    To achieve efficient conversion of renewable energy sources through water splitting, low-cost, earth-abundant, and robust electrocatalysts for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) are required. Herein, vertically aligned oxygenated-CoS2-MoS2 (O-CoMoS) heteronanosheets grown on flexible carbon fiber cloth as bifunctional electrocatalysts have been produced by use of the Anderson-type (NH4)(4)[CoIIMo(6)O(2)4H(6)]center dot 6H(2)O polyoxometalate as bimetal precursor. In comparison to different O-FeMoS, O-NiMoS, and MoS2 nanosheet arrays, the O-CoMoS heteronanosheet array exhibited low overpotentials of 97 and 272 mV to reach a current density of 10 mA cm(-2) in alkaline solution for the HER and OER, respectively. Assembled as an electrolyzer for overall water splitting, O-CoMoS heteronanosheets as both the anode and cathode deliver a current density of 10 mA cm(-2) at a quite low cell voltage of 1.6 V. This O-CoMoS architecture is highly advantageous for a disordered structure, exposure of active heterointerfaces, a "highway" of charge transport on two-dimensional conductive channels, and abundant active catalytic sites from the synergistic effect of the heterostructures, accomplishing a dramatically enhanced performance for the OER, HER, and overall water splitting. This work represents a feasible strategy to explore efficient and stable bifunctional bimetal sulfide electrocatalysts for renewable energy applications.

  • 125.
    Hoveskog, Maya
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Centrum för innovations-, entreprenörskaps- och lärandeforskning (CIEL), Centre for Technology, Innovation and Marketing Management (CTIM2).
    Innovation-related Activities in a Low-tech Industry: A Study of the Electroplating and Surface Treatment Industry in Sweden2011Inngår i: Research on Technology, Innovation and Marketing Management 2009‐2011: Introducing the Research Area of Innovation Science / [ed] Sven-Åke Hörte, Halmstad: Högskolan i Halmstad , 2011, s. 55-81Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    Given the complex and interdependent nature of innovation, it is a diverse phenomenon which takes place both in high‐ and low‐tech industries. The purpose of this paper is to increase our understanding about low‐tech industries’ innovation‐related activities and the specific capabilities of the companies that influence those. To achieve this purpose this study has performed an empirical analysis of the Swedish context of the Swedish Electroplating and Surface Treatment Industry (ESTI) and the characteristics of the companies operating in it. It investigated how the companies perceived their expertise and innovative activities in comparison with their main competitors. The main types of innovation the ESTI companieshad undertaken in a three‐year period (2004–2006) were studied. The research and development (R&D) and personnel qualification improvement expenditures were explored. The study looked into collaboration and the factors which companies perceived as important in order to collaborate. Our empirical evidence shows that innovation in the ESTI is shaped notby R&D but by other determinants, such as specific and rare capabilities in, for example, processing technologies, logistics, ability to spot, evaluate and exploit external knowledge as well as their ability to establish and sustain intercompany relationships. Strong relationships and integration with customers and suppliers emerge as pivotal for the innovation‐related activities in the ESTI. Additionally, close collaboration, facilitated by a strong intermediate institution, such as the Swedish Association of Surface Treatment Companies (Svensk YtbehandlingsFörening – SYF, also shape the innovation‐related activities in the ESTI.

  • 126.
    Hu, Lan
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Ekström, Henrik
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi. COMSOL AB, Sweden.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lagergren, Carina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    A Model for Analysis of the Porous Nickel Electrode Polarization in the Molten Carbonate Electrolysis Cell2017Inngår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 164, nr 8, s. H5197-H5201Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    It is important to know the electrode kinetics of hydrogen production as well as to understand the effect of the mass transport in the gas phase for the analysis of the molten carbonate electrolysis cell (MCEC). A one-dimensional model based on the Maxwell-Stefan diffusion equations was applied to predict the mass transfer behavior in gas phase of the porous nickel electrode in the MCEC, combined with equations describing the current distribution in the electrolyte phase. The model gave a fair match to the experimental polarization data of the Ni electrode for varied inlet gas compositions of H2O, CO2 and H-2 between 10 and 40%. The model was also deployed to evaluate the effect of the water-gas shift reaction (WGSR). The fitted kinetic coefficients and electrode porosity differed in the case when including the WGSR compared to when not including the WGSR. In both cases the model was able to well describe the porous nickel electrode behavior in the molten carbonate electrolysis cell.

  • 127.
    Hu, Lan
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lagergren, Carina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Operating the nickel electrode with hydrogen-lean gases in the molten carbonate electrolysis cell (MCEC)2016Inngår i: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 41, nr 41, s. 18692-18698Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    If a molten carbonate electrolysis cell (MCEC) is applied for fuel gas production it is important to know the polarization of the nickel electrode when operated at low concentration of hydrogen. Thus, the electrochemical performance of the Ni electrode was investigated under hydrogen-lean gases containing 1/24.5/24.5/50%, 1/49.5/24.5/25%, 1/24.5/49.5/25% and 1/49.5/49.5/0% H-2/CO2/H2O/N-2 in the temperature range of 600-650 degrees C and was then compared to the reference case with 25/25/25/25% H-2/CO2/H2O/N-2. The electrochemical measurements included polarization curve coupled with current interrupt, and electrochemical impedance spectroscopy. Polarization resistances of the Ni electrode obtained by the two different techniques agreed well. For the inlet gases containing low amounts of hydrogen the Ni electrode exhibited higher polarization losses than when using the reference case in the electrolysis cell. The electrochemical impedance measurements showed that both charge-transfer and mass-transfer polarizations were higher for hydrogen-lean gases at all measured temperatures. Except under the condition with 1/49.5/49.5% H-2/CO2/H2O at 650 degrees C, the Ni electrode exhibited lower mass-transfer polarization when compared to the reference case. Furthermore, the mass-transfer polarization was strongly dependent on temperature under H-2-lean gases, differing from the reference case when the temperature has almost no effect on mass-transfer polarization. The activation energy for hydrogen production was calculated to be in the range of 69 -138 kJ mol(-1) under all measured gases, indicating that the Ni electrode is under kinetic and/or mixed control in the MCEC.

  • 128.
    Huotari, Joni
    et al.
    University of Oulu, Finland.
    Lloyd Spetz, Anita
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad sensorvetenskap. Linköpings universitet, Tekniska högskolan.
    Lappalainen, Jyrki
    University of Oulu, Finland.
    Gas sensing properites of pulsed laser deposited vanadium oxide thin films2012Inngår i: IMCS 2012, 2012, s. 279-282Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Vanadium oxide thin films were fabricated by pulsed laser deposition (PLD). The crystal structure and symmetry of the deposited films was studied with X-ray diffraction (XRD) and Raman spectroscopy, respectively. The surface morphology was studied with atomic force microscope (AFM). The thin films consisted mostly of V2O5 phase of vanadium oxides, but also of another phase, which is generally found in form of nanotubes. The measured optical transmission spectra of the films also supported the existence of different phases. The electrical resistivity of the films as a function of temperature behaved like in a typical semiconductor. The gas sensing properties of the films were characterized for different NO concentrations. The results showed a response to NO, which varied from oxidative to reducing according to the film composition.

  • 129.
    Håkansson, Andreas
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Mat- och måltidsvetenskap. Högskolan Kristianstad, Forskningsmiljön Food and Meals in Everyday Life (MEAL).
    Scale-down failed: dissimilarities between high-pressure-homogenizers of different scales due to failed mechanistic matching2017Inngår i: Journal of Food Engineering, ISSN 0260-8774, E-ISSN 1873-5770, Vol. 195, s. 31-39Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The high-pressure homogenizer (HPH) is used extensively in the processing of non-solid foods. Food researchers and producers use HPHs of different scales, from laboratory-scale (∼10 L/h) to the largest production-scale machines (∼50 000 L/h). Hence, the process design and interpretation of academic findings regarding industrial condition requires an understanding of differences between scales. This contribution uses theoretical calculations to compare the hydrodynamics of the different scales and interpret differences in the mechanism of drop-breakup.

    Results indicate substantial differences between HPHs of different scales. The laboratory-scale HPH operates in the laminar regime whereas the production-scale is in the fully turbulent regime. The smaller scale machines are also less prone to cavitation and differ in their pressure profiles. This suggest that the HPHs of different scales should be seen as principally different emulsification processes. Conclusions on the effect or functionality of a HPH can therefore not readily be translate between scales.

  • 130.
    Håkansson, Andreas
    et al.
    Högskolan Kristianstad, Forskningsmiljön Food and Meals in Everyday Life (MEAL). Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Mat- och måltidsvetenskap.
    Zishan, Chaudhry
    Tetra Pak Processing Systems AB.
    Fredrik, Innings
    Tetra Pak Processing Systems AB.
    Model emulsions to study the mechanism of industrial mayonnaise emulsification2016Inngår i: Food and Bioproducts Processing, ISSN 0960-3085, E-ISSN 1744-3571, Vol. 98, s. 189-195Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Mechanistic understanding of industrial food-emulsification is necessary for optimal operation and design. Industrial mayonnaise production is yet poorly understood, partly due to a lack of experimental data and partly due to the complexity of the product.

    This study suggests a systematic method for building mechanistic insight, by investigating successively more complex model emulsions in industrial rotor–stator mixers, comparing to idealized theories identifying points of departure. As a first step, a high volume fraction (>50%) and high viscosity (>100 mPa s) model emulsion with a non-ionic surfactant acting as emulsifier is investigated in two industrial-scale mixers (one batch and one continuous inline mixer) at varying rotor tip-speeds.

    The resulting drop diameter to rotor tip-speed scaling suggest turbulent viscous fragmentation of the model emulsion in both mixers despite the high volume fraction of disperse phase which could be expected to lead to significant non-idealities such as extensive coalescence and concentration effect-dominated fragmentation. If the other non-idealities (e.g. egg yolk emulsifying system and non-Newtonian rheology) would not influence the emulsification, this suggests the same mechanism for mayonnaise emulsification. An outline for continued work on successively more complex model-emulsions is discussed in order to further enhance understanding.

  • 131.
    Illergård, Josefin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Römling, Ute
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Ek, Monica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Tailoring the effect of antibacterial polyelectrolyte multilayers by choice of cellulosic fiber substrate2013Inngår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 67, nr 5, s. 573-578Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    There is a need for new, antibacterial cellulose-based materials. Antibacterial cellulosic fibers with irreversibly attached polyvinylamine (PVAm) and polyacrylic acid (PAA) in multilayers were developed based on a water-based physical adsorption process. The antibacterial substance is thus prevented from leaching, in contrast to materials containing, for example, silver. It was shown on fibers from different sources that the antibacterial effect against both Escherichia coli and Bacillus subtilis can be tailored. The efficiency correlated with the initial fiber charge, which in turn correlated with the amount of adsorbed PVAm. In the case of highly charged fibers, the antibacterial efficacy was more than 99.9%. A sustainable antibacterial material can be obtained in a simple way based on a water-based process.

  • 132.
    Jeihanipour, Azam
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Waste Textiles Bioprocessing to Ethanol and Biogas2011Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    The work of the present thesis focused on conversion of the cellulosic part of waste textiles into biogas and ethanol, and its challenges. In 2009, the global annual fiber consumption exceeded 70 Mt, of which around 40% consisted of cellulosic material. This huge amount of fibers is processed into apparel, home textiles, and industrial products, ending up as waste after a certain time delay. Regretfully, current management of waste textiles mainly comprises incineration and landfilling, in spite of the potential of cellulosic material being used in the production of ethanol or methane. The volume of cellulose mentioned above would be sufficient for producing around 20 billion liters of ethanol or 11.6 billion Nm3 of methane per year. Nevertheless, waste textiles are not yet accepted as a suitable substrate for biofuel production, since their processing to biofuel presents certain challenges, e.g. high crystallinity of cotton cellulose, presence of dyes, reagents and other materials, and being textiles as a mixture of natural and synthetic fibers. High crystallinity of cotton cellulose curbs high efficient conversion by enzymatic or bacterial hydrolysis, and the presence of non-cellulosic fibers may create several processing problems. The work of the present thesis centered on these challenges. Cotton linter and blue jeans waste textiles, all practically pure cellulose, were converted to ethanol by SSSF, using S. cerevisiae, with a yield of about 0.14 g ethanol/g textile, only 25% of the theoretical yield. To improve the yield, a pretreatment process was required and thus, several methods were examined. Alkaline pretreatments significantly improved the yield of hydrolysis and subsequent ethanol production, the most effective condition being treatment with a 12% NaOH-solution at 0 °C, increasing the yield to 0.48 g ethanol/g textile (85% of the theoretical yield). Waste textile streams, however, are mixtures of different fibers, and a separation of the cellulosic fibers from synthetic fibers is thus necessary. The separation was not achieved using an alkaline pretreatment, and hence another approach was investigated, viz. pretreatment with N-methyl-morpholine-N-oxide (NMMO), an industrially available and environment friendly cellulose solvent. The dissolution process was performed under different conditions in terms of solvent concentration, temperature, and duration. Pretreatment with 85% NMMO at 120 °C under atmospheric pressure for 2.5 hours, improved the ethanol yield by 150%, compared to the yield of untreated cellulose. This pretreatment proved to be of major advantage, as it provided a method for dissolving and then recovering the cellulose. Using this method as a foundation, a novel process was developed, refined and verified, by testing polyester/cellulose-blended textiles, which predominate waste textiles. The polyesters were purified as fibers after the NMMO treatments, and up to 95% of the cellulose content was regenerated. The solvent was then recovered, recycled, and reused. Furthermore, investigating the effect of this treatment on anaerobic digestion of cellulose disclosed a remarkable enhancement of the microbial solubilization; the rate in pretreated textiles was twice the rate in untreated material. The overall yield of methane was, however, not significantly affected. The process developed in the present thesis appears promising for transformation of waste textiles into a suitable raw material, to subsequently be used for biological conversion to ethanol and biogas.

  • 133.
    Johansson, Christoffer
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper.
    Analys av Tjocklut med Akustisk Spektroskopi: Prediktering av Torrhalt2014Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Att driva av vatten ur använd kokvätska (lut) från massakokarna kallas indunstning och är den mest energikrävande processen inom den kemiska massaindustrin. Dock måste det göras för att dessa lutar ska kunna förbrännas i sodapannan och kemikalierna återvinnas. På Gruvöns bruk i Grums innebär samåtervinningen av svartlut och rödlut att beläggningar lättare uppstår på utrustningen och arbetet med att förbättra och effektivisera processen pågår ständigt. Som ett led i detta arbete har luten undersökts med en mätare som bygger på aktiv akustisk spektroskopi. I detta examensarbete har ljudspektrum undersökts i syfte att korrelera dessa till lutens egenskaper med den främsta målsättningen att skapa en modell som kan prediktera torrhalten. Med hjälp av multivariata analysmetoder samt en rad olika förbehandlingar kunde en prediktionsmodell med goda prediktiva egenskaper åstadkommas. Modellen samt ett antal andra intressanta observationer som kan vara av värde för processen redovisas och diskuteras. Även ett flertal vidare arbeten föreslås.

  • 134.
    Johansson, David
    et al.
    KTH, Tidigare Institutioner, Kemiteknik.
    Andrae, Johan
    KTH, Tidigare Institutioner, Kemiteknik.
    Björnbom, Pehr
    KTH, Tidigare Institutioner, Kemiteknik.
    Coupling of CHEMKIN and MATLAB for HCCI combustion application2004Inngår i: International Symposium on Combustion, Abstracts of Works-in-Progress Posters, 2004Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In Homogeneous Charge Compression Ignition (HCCI) engine applications a mixture of fuel and oxidizer is compressed in an engine cylinder until self-ignition occurs. Since no flame propagation or fuel-rich regions exists no soot will form and in-cylinder temperatures will be rather low leading to very low NOx emissions. Another benefit is a high, diesel like, efficiency. The problems will HCCI combustion are mainly high hydrocarbon and CO emissions, high peak pressures, control difficulties, etc. A possible way to utilize the benefits is to use a dual mode engine that works in HCCI mode at low and medium loads and in diesel mode at high loads. A way to link CHEMKIN III to the MATLAB environment is presented. The coupling between the programs gives MATLAB access to rate of production, enthalpy and specific heat producing subroutines from the CHEMKIN III package. All modeling is done in MATLAB after the link has been established. The coupling is then used to make a HCCI engine model, consisting of three zones, each of uniform temperatures and composition, of each zone, and the inputs are temperatures of the different zones, pressure and composition of the initial fuel/ox load and engine data. Analysis of a mixture of 84% iso-octane and 16% and n-heptane/air HCCI combustion was presented and compared to experimental results. This is an abstract of a paper presented at the 30th International Symposium on Combustion (Chicago, IL 7/25-30/2004).

  • 135.
    Johansson, Ted
    KTH, Skolan för kemivetenskap (CHE).
    Integrerad schemaläggning och styrning av en luftsepareringsanläggning vid varierande elpris2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [sv]

    I detta examensarbete presenteras en ny metod för att göra schemaläggningsbeslut inom processindustrin

    och samtidigt ta hänsyn till det dynamiska beteendet hos processen. En modell av en luftsepareringsanläggning

    som producerar kvävgas och utnyttjar ett rörligt elpris användes för att exemplifiera denna

    metod. Modellen omfattade en kryogenisk destillationskolonn med en integrerad återloppskokare /kondensator,

    en multiströms värmeväxlare, en kompressor, två turbiner och en kondensator. Den innehöll

    5079 ekvationer och 437 differentiella variabler. Dynamisk optimering användes för att approximera

    det dynamiska beteendet hos processen vid skiftningar mellan olika driftpunkter. Den registrerade data

    utnyttjades sedan för att identifiera en reducerad modell som fångade det transienta beteendet hos relevanta

    processvariabler. Den reducerade modellen bestod av 525 ekvationer och 67 differentiella variabler.

    Den identifierade modellen visade på god matchning mellan relevanta processvariabler i de simulerade

    övergångarna och den reducerade modellen.

    Den reducerade modellen användes för att optimera schemaläggningen av luftsepareringsprocessen så

    att elkostnaden över en tredagars period minimerades. De optimala resultaten visade på en minskning av

    kostnaden på 2.6 % jämfört med en konstant produktionstakt. Schemat implementerades och simulerades

    i den fullt dynamiska modellen över de första 24 timmarna för att jämföra relevanta processvariabler med

    den reducerade modellen. Resultaten visade på god matchning mellan de båda modellerna.

    Detta examensarbete visar att en exakt reducerade modell kan användas för att snabbt hitta ett

    optimalt schema över ett större processystem. Detta genom att kraftigt minska systemets storlek utan

    att offra noggrannhet av det dynamiska beteendet.

  • 136.
    Jonsson, Alexander
    KTH, Skolan för kemivetenskap (CHE).
    En jämförande studie av bussar i stadskörning2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    In the big cities people are in close contact with traffic; therefore it is of great importance that the purification of vehicle exhaust is done optimal to reduce the harmful effects on humans. Buses have previously been a major contributor to poor air quality in inner cities, but with harder regulations on low levels of harmful substances such as nitrogen oxides, carbon oxides and particulates, the buses become less harmful and more environmentally friendly. The legal requirements for emission standards of heavy duty vehicles set by the EU is today called Euro VI  and  regulates  the  hazardous  emissions  from  all  new  engines  produced  after  2014.  In contrast to this regulation this study focuses on tests performed on the bus as a hole, not only the engine.

    The tests on buses in this study focuses on the real bus driving behavior in the inner city of Stockholm. Through measuring a new Stockholm Bus Driving Cycle and running bus tests on this driving cycle, the emissions and fuel consumption from the buses have been monitored and compared. The tests have been carried out at VTT test center in Helsinki on a heavy-­‐duty dynamometer and emission bench test equipment. Further tests in this study have been performed by Keolis directly on buses driven in the Stockholm area. Emissions and fuel consumption was measured by Portable Emission Measurement System, PEMS.

    The results of these tests shows higher emissions from buses driven in real inner city driving conditions then the buses emitted at the Euro standard engine certification tests performed at the time the bus was certified. In particular buses driven on the Stockholm Bus Driving Cycle had exceptional high NOx values and highest overall emissions of all buses tested. Also buses driven at the Stockholm cycle with no passengers emitted higher NOx emissions in g/km then buses driven with half load of passengers. These results questions if the SCR-­‐catalyst,  (NOx-­‐ converter) which all modern buses are equipped with is suitable for inner city driving conditions where engine exhaust temperature is to low for god NOx-­‐conversion.

    Minor differences were shown between manufacturers. Some differences in emissions were seen from which fuel that was used. Where gas-­‐buses had very low particle emissions, and diesel buses had lowest fuel consumption. The major differences was shown from driving behavior and therefore the recommendation from this study is that buses intended for innercity traffic is to be tested with inner city driving conditions and the real emissions from those buses should be presented to the people living in Stockholm.

  • 137.
    Jónsson, Pétur
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för farmaci.
    Characterization of enzyme sensitive responsive hydrogel/lipid system for triggered release2013Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This master thesis aimed to create and characterize multilayer coatings upon mesoporous silica particles (MSP). The properties of the coating aimed for, was to have a triggerable controlled release, where a targeted enzyme within the intestine, alpha-amylase, is supposed to degrade the coating. The coating was created from a bilayer consisting of DOTAP and DOPC in a 1:3 molar ratio, which serves as a protective coating. The second layer interacting with the surroundings consisted of a starch component, amylopectin, which is degraded by alpha-amylase. The study of the coating was performed with ellipsometry, where the adsorption of the different layers of the coating on a planar silica surface and the enzyme-triggered degradation was recorded. The adsorbed amount of DOTAP/DOPC was 4,22 ± 0,11 mg/m2 and amylopectin 1,82 ± 0,94. The effects of different pH where performed, simulating the coated particle going through the gastro-intestinal system. Two enzymes alpha-amylase and phospholipase A2 (PLA2) where used for degradation of the coating. The knowledge from ellipsometry was applied to coating mesoporous silica particles and it was confirmed that the two layers had formed with zeta- potential measurement. 

  • 138.
    Kanesund, Jan-erik
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling. Linköpings universitet, Tekniska fakulteten.
    Influence of deformation and environmental degradation of Inconel 7922017Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Industrial gas turbines are often used as a mechanical drive for pumps and compressors or in power generation as an electric power supply. The gas turbine has for many years been a popular engine due to its flexibility with respect to different types of fuel and due to a design, that enables a high power-to-weight ratio. A simplified description of a gas turbine is that the engine consists of a cold and hot section. The turbo compressor section belongs to cold section and the combustion chamber together with the turbine section belongs to the hot section. In the hot section of a gas turbine, the condition is extremely severe because of an aggressive environment characterized by high temperatures, increased temperature gradients, high pressure and centrifugal forces resulting in large stresses on individual components together with an oxidizing and corroding atmosphere. Materials used in the high temperature section (hot gas path) of a modern gas turbine are different types of superalloys, as single crystal, directionally solidified or polycrystalline alloys, depending on temperature and load conditions. In the first turbine stage, temperature is very high due to exposure to the combustion gas. To handle the problem with creep, single crystal superalloys are often used in this section. In the second row of turbine blades, the temperature of the gas is lower and polycrystalline superalloys are typically used. IN-792 is a cast polycrystalline superalloy with high strength, good resistance to hot corrosion and a cheaper option than single crystals. In the hot section of gas turbine, IN-792 is a suitable material for components such as turbine blades and vans where a complex load condition, high temperature and severe environment prevails. Due to startup and shutdown of the gas turbine engine during service, the components in the hot section are exposed to cyclic load and temperature. This will generate mechanical and thermal fatigue damage in gas turbine components. Steady state temperature gradient arises by the cooling system acting at cold spots during service to introduce tensile stress, which indirectly gives rise to creep damage in the component. This work includes tree studies of deformation and damage mechanisms of superalloy IN-792. The first study is made on test bars exposed to thermomechanical fatigue in laboratory environment, the second and the third study is made on turbine blades used during service. In the second study, the machines are placed off-shore and exposed to marine environment. In the third study the machine is landbased and exposed to an industrial environment. In the second study, the deformation and damage mechanisms are compared between the turbine blades used during service and the test bars exposed to thermomechanical fatigue testing in the first study.

  • 139.
    Kanninen, Petri
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi. Aalto Univ, Dept Chem & Mat Sci, POB 16100, Aalto 00076, Finland.
    Kallio, Tanja
    Aalto Univ, Dept Chem & Mat Sci, POB 16100, Aalto 00076, Finland..
    Activation of commercial Pt/C catalyst toward glucose electro-oxidation by irreversible Bi adsorption2018Inngår i: Journal of Energy Challenges and Mechanics, ISSN 2095-4956, E-ISSN 2056-9386, Vol. 27, nr 5, s. 1446-1452Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effect of irreversibly adsorbed Bi on commercial Pt/C catalyst toward glucose electro-oxidation reaction (GOR) in different electrolytes (acidic, neutral, alkaline) is studied. Bi is successfully deposited on Pt/C from Bi3+ containing acidic solution from 0 to 90% coverage degree. The stability of the Bi layer in acid and alkaline corresponded to previous studies and started to dissolve at 0.7 V and 0.8 V versus reversible hydrogen electrode (RHE), respectively. However, in neutral phosphate buffer the layer showed remarkable stability to at least 1.2 V versus RHE. Bi modification at low (20%) and high (80%) coverage showed the highest increase in the activity of Pt/C toward GOR by a factor up to 7 due to the increased poisoning resistance of the modified catalyst. The effect of poisoning was especially reduced at high Bi coverage (80%), which shows that adsorbate blocked by Bi through the third-body effect is effective. Finally, with or without Bi modification GOR on Pt/C was most active in alkaline conditions.

  • 140.
    Karlsson, Rasmus
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Theoretical and Experimental Studies of Electrode and Electrolyte Processes in Industrial Electrosynthesis2015Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Heterogeneous electrocatalysis is the usage of solid materials to decrease the amount of energy needed to produce chemicals using electricity. It is of core importance for modern life, as it enables production of chemicals, such as chlorine gas and sodium chlorate, needed for e.g. materials and pharmaceuticals production. Furthermore, as the need to make a transition to usage of renewable energy sources is growing, the importance for electrocatalysis used for electrolytic production of clean fuels, such as hydrogen, is rising. In this thesis, work aimed at understanding and improving electrocatalysts used for these purposes is presented.

    A main part of the work has been focused on the selectivity between chlorine gas, or sodium chlorate formation, and parasitic oxygen evolution. An activation of anode surface Ti cations by nearby Ru cations is suggested as a reason for the high chlorine selectivity of the “dimensionally stable anode” (DSA), the standard anode used in industrial chlorine and sodium chlorate production. Furthermore, theoretical methods have been used to screen for dopants that can be used to improve the activity and selectivity of DSA, and several promising candidates have been found. Moreover, the connection between the rate of chlorate formation and the rate of parasitic oxygen evolution, as well as the possible catalytic effects of electrolyte contaminants on parasitic oxygen evolution in the chlorate process, have been studied experimentally.

    Additionally, the properties of a Co-doped DSA have been studied, and it is found that the doping makes the electrode more active for hydrogen evolution. Finally, the hydrogen evolution reaction on both RuO2 and the noble-metal-free electrocatalyst material MoS2 has been studied using a combination of experimental and theoretically calculated X-ray photoelectron chemical shifts. In this way, insight into structural changes accompanying hydrogen evolution on these materials is obtained.

  • 141.
    Kasai, Nahoko
    et al.
    Nippon Telegraph and Telephone Corporation.
    Shimada, Akiyoshi
    Nippon Telegraph and Telephone Corporation.
    Nyberg, Tobias
    Nippon Telegraph and Telephone Corporation.
    Torimitsu, Keiichi
    Nippon Telegraph and Telephone Corporation.
    Fabrication of an electrochemical sensor array for 2D H2O2 imaging2006Inngår i: Electrochemistry (Tokyo. 1999), ISSN 1344-3542, Vol. 74, nr 8, s. 628-631Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    To achieve accurate real-time 2D H2O2 distribution imaging, we fabricated an H2O2 sensor array by dispensing small quantities of enzyme solution very accurately onto electrodes in an electrode array. We confirmed the accuracy of the dispensing technique. We then investigated the responses of each sensor to H2O2 injection using a 64-channel multipotentiostat and found they varied by 20%. Real-time 2D H2O2 imaging was therefore successfully realized by using our flow cell system. This sensor array will be useful for the non-invasive, real-time monitoring of the H2O2 distribution in biological samples.

  • 142. Kasedde, Hillary
    et al.
    Kirabira, John Baptist
    Bäbler, Matthäus
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    Tilliander, Anders
    Jonsson, Stefan
    Dissolution kinetics of natural halite from Lake Katwe (Uganda) in aqueous salt solutionsManuskript (preprint) (Annet vitenskapelig)
  • 143. Kassman, Håkan
    et al.
    Broström, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik, Energiteknik och termisk processkemi.
    Berg, Magnus
    Åmand, Lars-Erik
    Measures to reduce chlorine in deposits: Application in a large-scale circulating fluidised bed boiler firing biomass2011Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 90, nr 4, s. 1325-1334Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Combustion of biomass with a high content of alkali (mainly potassium, K) and chlorine (Cl) can result in operational problems including deposit formation and superheater corrosion. Among the measures applied to decrease such problems are co-combustion and the use of additives. The positive effects of these measures are to a large extent either sulphation of the alkali chlorides (KCl) to less corrosive alkali sulphates or capture of alkali from KCl during release of HCl. A test campaign was carried out in a large-scale circulating fluidised boiler fired with biomass where the measures applied were sulphation by ammonium sulphate and co-combustion with peat. Their performance was evaluated by means of several advanced measurement tools including: IACM (on-line measurements of gaseous KCl); a low-pressure impactor (size distribution and chemical composition of extracted fly ash particles) and deposit measurements (chemical composition in collected deposits). The overall performance was better for ammonium sulphate, which significantly lowered KCl in the flue gas. Meanwhile no chlorine was found in the deposits. Only a minor reduction of gaseous KCl was obtained during co-combustion with peat although the chlorinecontent in the deposits was greatly reduced. These findings were supported by the results from the impactor measurements.

  • 144.
    Khurshid, Samir Najem Aldeen
    KTH, Skolan för kemivetenskap (CHE).
    Biodiesel production by using heterogeneous catalyst2014Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
  • 145.
    Kihlman, Martin
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper.
    Medronho, Bruno F.
    Univ Algarve, Fac Sci & Technol, IBB, CGB, P-8005139 Faro, Portugal..
    Romano, Anabela L.
    Univ Algarve, Fac Sci & Technol, IBB, CGB, P-8005139 Faro, Portugal..
    Germgård, Ulf
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper.
    Lindman, Bjorn
    Univ Coimbra, Dept Chem, P-3004535 Coimbra, Portugal.;Lund Univ, Ctr Chem & Chem Engn, Div Phys Chem, S-22100 Lund, Sweden..
    Cellulose Dissolution in an Alkali Based Solvent: Influence of Additives and Pretreatments2013Inngår i: Journal of the Brazilian Chemical Society, ISSN 0103-5053, E-ISSN 1678-4790, Vol. 24, nr 2, s. 295-303Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The distinction between thermodynamic and kinetics in cellulose dissolution is seldom considered in the literature. Therefore, herein an attempt to discuss this topic and illustrate our hypotheses on the basis of simple experiments was made. It is well-known that cellulose can be dissolved in a aqueous sodium hydroxide (NaOH/H2O) solvent at low temperature but it is here shown that such an alkaline solvent can be considerably improved regarding solubility, stability and rheological properties as a whole if different additives (salts and amphiphilic molecules) are used in the dissolution stage. This work probes new aqueous routes to dissolve cellulose, thereby improving the potential to commercially dissolve cellulose in an inexpensive and environmentally friendly manner.

  • 146.
    Kindblom, Mikael
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper.
    Abdeljawad, Raghid
    Agha Mohammadi, Sina
    Construction of a Powder Bed 3D Printer2018Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    This project is part of a bigger project where the goal is to be able to create smaller batches of individually designed pills with a high resolution. This could be done by using a powder bed 3D printer, which our job was to find out. This type of machine prints out a thin pattern of binder through a printer head and then sweeps powder over the pattern, making the powder stick to the binder. This process is repeated until the object is formed. The machine necessary was created from scratch using a guide provided by the Internet.

    The results were unfortunately uncertain. We managed to print with ink and the pattern created had a high level of accuracy but due to time limitations, we never got to print with actual binder in the cartridge.

  • 147.
    Klass, Verena
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Battery Health Estimation in Electric Vehicles2015Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    For the broad commercial success of electric vehicles (EVs), it is essential to deeply understand how batteries behave in this challenging application. This thesis has therefore been focused on studying automotive lithium-ion batteries in respect of their performance under EV operation. Particularly, the  need  for  simple  methods  estimating  the  state-of-health  (SOH)  of batteries during EV operation has been addressed in order to ensure safe, reliable, and cost-effective EV operation. Within  the  scope  of  this  thesis,  a  method  has  been  developed  that  can estimate the SOH indicators capacity and internal resistance. The method is solely based on signals that are available on-board during ordinary EV operation  such  as  the  measured  current,  voltage,  temperature,  and  the battery  management  system’s  state-of-charge  estimate.  The  approach  is based on data-driven battery models (support vector machines (SVM) or system  identification)  and  virtual  tests  in  correspondence  to  standard performance  tests  as  established  in  laboratory  testing  for  capacity  and resistance determination. The proposed method has been demonstrated for battery data collected in field tests and has also been verified in laboratory. After a first proof-of-concept of the method idea with battery pack data from a plug-in hybrid electric vehicle (PHEV) field test, the method was improved with the help of a laboratory study where battery electric vehicle (BEV) operation of a battery  cell  was  emulated  under  controlled  conditions  providing  a thorough validation possibility. Precise partial capacity and instantaneous resistance  estimations  could  be  derived  and  an  accurate  diffusion resistance estimation was achieved by including a current history variable in the SVM-based model. The dynamic system identification battery model gave precise total resistance estimates as well. The SOH estimation method was also applied to a data set from emulated hybrid electric vehicle (HEV) operation of a battery cell on board a heavy-duty vehicle, where on-board standard  test  validation  revealed  accurate  dynamic  voltage  estimation performance of the applied model even during high-current situations. In order to exhibit the method’s intended implementation, up-to-date SOH indicators have been estimated from driving data during a one-year time period.

  • 148.
    Klass, Verena
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Behm, Mårten
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Capturing lithium-ion battery dynamics with support vector machine-based battery model2015Inngår i: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 298, s. 92-101Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    During long and high current pulses, diffusion resistance becomes important in lithium-ion batteries. In such diffusion-intense situations, a static support vector machine-based battery model relying on instantaneous current, state-of-charge (SOC), and temperature is not sufficient to capture the time-dependent voltage characteristics. In order to account for the diffusion-related voltage dynamics, we suggest therefore the inclusion of current history in the data-driven battery model by moving averages of the recent current. The voltage estimation performance of six different dynamic battery models with additional current history input is studied during relevant test scenarios. All current history models improve the time-dependent voltage drop estimation compared to the static model, manifesting the beneficial effect of the additional current history input during diffusion-intense situations. The best diffusion resistance estimation results are obtained for the two-step voltage estimation models that incorporate a reciprocal square root of time weighing function for the current of the previous 100 s or an exponential time function with a 20 s time constant (1–8% relative error). Those current history models even improve the overall voltage estimation performance during the studied test scenarios (under 0.25% root-mean-square percentage error).

  • 149.
    Klass, Verena
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Behm, Mårten
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Evaluating real-life performance of lithium-ion battery packs in electric vehicles2012Inngår i: ECS Transactions 2012, Electrochemical Society, 2012, Vol. 41, nr 32, s. 1-11Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In regard to the increasing market launch of plug-in hybrid electric vehicles (PHEVs), understanding battery pack performance under electric vehicle (EV) operating conditions is essential. As lifetime still remains an issue for battery packs, it is a necessity to monitor the battery pack's state-of-health (SOH) on-board. Standard performance tests for health evaluation do not apply since operation interruptions and additional testing equipment are beyond question during ordinary EV usage. We suggest a novel methodology of performance estimation from real-life battery data. On the basis of battery pack data collected during PHEV operation, a support vector machine model is constructed that serves as source for performance evaluation figures. The SOH indicator "10 s discharge resistance" as known from hybrid pulse power characterization (HPPC) tests is chosen to exemplify how performance degradation can be followed over a year.

  • 150.
    Klass, Verena
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Behm, Mårten
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Li-ion battery performance in electric vehicles2010Inngår i: AABC 2010 Conference and Symposia Proceedings, 2010Konferansepaper (Fagfellevurdert)
    Abstract [en]

    When Li-ion batteries are applied in challenging applications like the propulsion of electric vehicles, it is essential to understand their performance and degradation as a function of their use in order to predict and improve their life time. Therefore, data on the behavior of batteries during electric vehicle operation is documented and methods and strategies for the processing of the real-life data are developed. From battery data analysis, insight into the characteristics of Li-ion batteries in electric vehicles can be gained and battery stress factors can be identified. Ultimately, the impact of operation conditions and battery specifications on battery performance and especially on battery performance degradation are intended to be described quantitatively. Recommendations on the optimum operation of the battery in regard of prolonging battery life time are meant to be given.

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