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  • 301.
    Andersons, J.
    et al.
    University of Latvia, Riga.
    Sparnins, Edgars
    Institute of Polymer Mechanics, University of Latvia.
    Joffe, Roberts
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Stiffness and strength of flax fiber/polymer matrix composites2006In: Polymer Composites, ISSN 0272-8397, E-ISSN 1548-0569, Vol. 27, no 2, p. 221-229Article in journal (Refereed)
    Abstract [en]

    Flax fiber composites with thermoset and thermoplastic polymer matrices have been manufactured and tested for stiffness and strength under uniaxial tension. Flax/polypropylene and flax/maleic anhydride grafted polypropylene composites are produced from compound obtained by coextrusion of granulated polypropylene and flax fibers, while flax fiber mat/vinylester and modified acrylic resin composites are manufactured by resin transfer molding. The applicability of rule-of-mixtures and orientational averaging based models, developed for short fiber composites, to flax reinforced polymers is considered.

  • 302.
    Andersons, Janis
    et al.
    Institute of Polymer Mechanics, University of Latvia.
    Joffe, Roberts
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Initiation and propagation controlled intralaminar cracking in cross-ply laminates: Chapter 102009In: Encyclopedia of Polymer Composites: Properties, Performance and Applications, New York: Nova Science Publishers, Inc., 2009Chapter in book (Other academic)
  • 303.
    Andersons, Janis
    et al.
    Institute of Polymer Mechanics, University of Latvia.
    Joffe, Roberts
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Mechanical damage characteristics of elementary hemp fibers and scale effect of fiber strength2012In: High Performance Structure and Materials VI: papers presented at the 6th International Conference on High Performance Structures and Materials held at the Wessex Institute of Technology in the New Forest, UK] / [ed] W.P. De Wilde; C.A. Brebbia; S. Hernandez, Southampton: WIT Press, 2012, p. 157-167Conference paper (Refereed)
    Abstract [en]

    Ecological and economical considerations foster replacement of man-made fibers by natural renewable fibers in various industrial applications. Bast fibers of such plants as, e.g., flax, hemp, jute etc., are particularly attractive as a reinforcement of polymer-matrix composites due to their high specific stiffness and strength in the axial direction. The elementary bast fibers exhibit pronounced scatter of strength. It necessitates probabilistic description of their strength via a distribution function that reflects damage morphology and severity in fibers. Fiber fracture is shown to originate from mechanical defects of the bast cell wall, the most prominent of them being kink bands. While the number of kink bands in a fiber is easily determined by optical microscopy, direct experimental measurement of their strength is complicated. Therefore, alternative approaches are sought, enabling extraction of strength characteristics of the kink bands from fiber tests via appropriate probabilistic models. Analytical distribution function of bast fiber strength has been derived, allowing for the effect of mechanical damage in the form of kink bands. The fiber characteristics measured have been used to evaluate the kink band density and strength distributions. The theoretical distribution is verified against experimental tensile strength data of elementary hemp fibers at several gauge lengths and found to provide acceptable accuracy in predicting the scale effect of strength.

  • 304. Andersons, Janis
    et al.
    Joffe, Roberts
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Sparnins, Edgars
    Institute of Polymer Mechanics, University of Latvia.
    Evaluation of interfacial shear strength by tensile tests of impregnated flax fiber yarns2012In: Journal of composite materials, ISSN 0021-9983, E-ISSN 1530-793X, Vol. 46, no 3, p. 351-357Article in journal (Refereed)
    Abstract [en]

    Adhesion of flax fibers and polymer matrix as well as mutual bonding of elementary fibers in a technical fiber are among the principal factors governing the mechanical response of flax fiber reinforced polymer-matrix composites. A method for evaluation of adhesion is proposed based on tension tests of impregnated fiber yarns, with subsequent characterization by optical microscopy of length distribution of fibers pulled out of the yarn fracture surfaces. An elementary probabilistic model is derived relating aspect ratio distribution of the pulled out fibers to the fiber tensile strength distribution and the effective interfacial shear strength. The method was applied to flax fiber/vinylester resin yarns and an estimate of interfacial shear strength at 17 MPa was obtained.

  • 305.
    Andersons, Janis
    et al.
    Institute of Polymer Mechanics, University of Latvia.
    Joffe, Roberts
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Sparnins, Edgars
    Statistical model of the transverse ply cracking in cross-ply laminates by strength and fracture toughness based failure criteria2008In: Engineering Fracture Mechanics, ISSN 0013-7944, E-ISSN 1873-7315, Vol. 75, no 9, p. 2651-2665Article in journal (Refereed)
    Abstract [en]

    Cross-ply laminate subjected to tensile loading provides a relatively well understood and widely used model system for studying progressive cracking of the transverse ply. This test allows to identify material strength and/or toughness characteristics as well as to establish relation between damage level and the composite stiffness reduction. The transverse ply cracking is an inherently stochastic process due to the random variability of local material properties of the plies. The variability affects both crack initiation (governed by the local strength) and propagation (governed by the local fracture toughness). The primary aim of the present study is elucidation of the relative importance of these phenomena in the fragmentation process at different transverse and longitudinal ply thickness ratios. The effect of the random crack distribution on the mechanical properties reduction of the laminate is also considered. Transverse ply cracking in glass fiber/epoxy cross-ply laminates of the lay-ups [02/902]s, [0/902]s, and [0/904]s is studied. Several specimens of each lay-up were subjected to uniaxial quasistatic tension to obtain crack density as a function of applied strain. Crack spacing distributions at the edge of the specimen also were determined at a predefined applied strain. Statistical model of the cracking process is derived, calibrated using crack density vs. strain data, and verified against the measured crack spacing distributions.

  • 306.
    Andersons, Janis
    et al.
    Institute of Polymer Mechanics, University of Latvia.
    Joffe, Roberts
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Sparnins, Edgars
    Rubenis, Oskars
    Institute of Polymer Mechanics, University of Latvia.
    Progressive cracking mastercurves of the transverse ply in a laminate2009In: Polymer Composites, ISSN 0272-8397, E-ISSN 1548-0569, Vol. 30, no 8, p. 1175-1182Article in journal (Refereed)
    Abstract [en]

    In this study, progressive cracking of a transverse layer in a cross-ply composite laminate subjected to tensile loading is considered. Using the results of a probabilistic cracking model, approximate relations for crack density as a function of stress are derived for initiation-controlled and propagation-controlled cracking. It is shown that the crack density evolution in the transverse ply can be represented by a mastercurve in suitably normalized coordinates. The mastercurve approach is applied to progressive cracking in glass/epoxy laminates

  • 307.
    Andersons, Janis
    et al.
    Institute of Polymer Mechanics, University of Latvia.
    Modniks, Janis
    Institute of Polymer Mechanics, University of Latvia.
    Joffe, Roberts
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    An Improved Method For Identification Of The Interfacial Shear Strength By Tensile Tests Of Short-Fiber Composites2015In: Proceedings of 7th International Conference on Composites Testing and Model Identification / [ed] C. González; C. López; J. LLorca, Madrid, Spain: IMDEA, Madrid (SPAIN) , 2015Conference paper (Refereed)
  • 308.
    Andersons, Janis
    et al.
    Institute of Polymer Mechanics, University of Latvia.
    Modniks, Janis
    Institute of Polymer Mechanics, University of Latvia.
    Joffe, Roberts
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Madsen, Bo
    Technical University of Denmark, Risø Campus, Materials Research Division, Risø National Laboratory for Sustainable Energy, Technical University of Denmark.
    Nättinen, Kalle
    Bemis Flexible Packaging Europe, Bemis Valkeakoski Oy.
    Apparent interfacial shear strength of short-flax-fiber/starch acetate composites2016In: International Journal of Adhesion and Adhesives, ISSN 0143-7496, E-ISSN 1879-0127, Vol. 64, p. 78-85Article in journal (Refereed)
    Abstract [en]

    The paper deals with an indirect industry-friendly method for identification of the interfacial shear strength (IFSS) in a fully bio-based composite. The IFSS of flax fiber/starch acetate is evaluated by a modified Bowyer and Bader method based on an analysis of the stress-strain curve of a short-fiber-reinforced composite in tension. A shear lag model is developed for the tensile stress-strain response of short-fiber-reinforced composites allowing for an elasticperfectly plastic stress transfer. Composites with different fiber volume fractions and a variable content of plasticizer have been analyzed. The apparent IFSS of flax /starch acetate is within the range of 5.5 to 20.5 MPa, depending on composition of the material. The IFSS is found to be greater for composites with a higher fiber loading and to decrease with increasing content of plasticizer. The IFSS is equal or greater than the yield strength of the neat polymer, suggesting good adhesion, as expected for the chemically compatible constituents.

  • 309.
    Andersons, Janis
    et al.
    Institute of Polymer Mechanics, University of Latvia.
    Sparnins, Edgars
    Joffe, Roberts
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    The onset of mixed mode intralaminar cracking in a cross-ply composite laminate2008In: Mechanics of composite materials, ISSN 0191-5665, E-ISSN 1573-8922, Vol. 44, no 6, p. 549-556Article in journal (Refereed)
    Abstract [en]

    The intralaminar fracture toughness of a unidirectionally reinforced glass/epoxy composite is determined experimentally at several mode I and mode II loading ratios. The crack propagation criterion, expressed as a quadratic form in terms of single-mode stress intensity factors (alternatively, linear in terms of energy release rates), approximates the test results reasonably well. The mixed-mode cracking criterion obtained is used to predict the intralaminar crack on set in a cross-ply glass/epoxy composite under off-axis tensile loading.

  • 310.
    Andersons, Janis
    et al.
    Institute of Polymer Mechanics, University of Latvia.
    Sparnins, Edgars
    Joffe, Roberts
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Uniformity of filament strength within a flax fiber batch2009In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 44, no 2, p. 685-687Article in journal (Refereed)
  • 311.
    Andersons, Janis
    et al.
    Institute of Polymer Mechanics, University of Latvia.
    Sparnins, Edgars
    Institute of Polymer Mechanics, University of Latvia.
    Joffe, Roberts
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Wallström, Lennart
    Strength distribution of elementary flax fibres2005In: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 65, no 3-4, p. 693-702Article in journal (Refereed)
    Abstract [en]

    Flax fibres, along with a number of other natural fibres, are being considered as an environmentally friendly alternative of synthetic fibres in fibre-reinforced polymer composites. A common feature of natural fibres is a much higher variability of mechanical properties. This necessitates study of the flax fibre strength distribution and efficient experimental methods for its determination. Elementary flax fibres of different gauge lengths are tested by single fibre tension in order to obtain the stress-strain response and strength and failure strain distributions. The applicability of single fibre fragmentation test for flax fibre failure strain and strength characterization is considered. It is shown that fibre fragmentation test can be used to determine the fibre length effect on mean fibre strength and limit strain.

  • 312.
    Andersons, Janis
    et al.
    Institute of Polymer Mechanics, University of Latvia.
    Sparnins, Edgars
    Nyström, Birgitha
    Joffe, Roberts
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Scale effect of the tensile strength of flax-fabric-reinforced polymer composites2011In: Journal of reinforced plastics and composites (Print), ISSN 0731-6844, E-ISSN 1530-7964, Vol. 30, no 23, p. 1969-1974Article in journal (Refereed)
    Abstract [en]

    The development of UD natural fiber composites, considered for application as structural materials, necessitates evaluation of the scale effect of their strength. Alignment of the fibers in flax bast fiber composites can be achieved by employing textile reinforcement, such as yarns and fabrics. Cutting specimens for mechanical tests out of such textile-reinforced composite plates results in a complex non-uniform reinforcement structure at their edges, which may affect the strength of specimens. Scale effect of the tensile strength in the fiber direction of flax fabric reinforced composites is studied in the current work. A model accounting for both volume and edge effect of the specimens on their tensile strength is proposed.

  • 313.
    Andersons, Janis
    et al.
    Institute of Polymer Mechanics, University of Latvia.
    Sparnins, Edgars
    Porike, Evija
    Institute of Polymer Mechanics, University of Latvia.
    Joffe, Roberts
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Strength distribution of elementary flax fibres due to mechanical defects2008In: 11th International Inorganic-Bonded Fiber Composites Conference (IIBCC): Madrid, Nov. 4 - 7, 2008. Proceedings / [ed] Blanco Suárez; Maria Ángeles, Madrid: Universidad Complutense de Madrid , 2008Conference paper (Refereed)
  • 314.
    Andersons, Janis
    et al.
    Institute of Polymer Mechanics, University of Latvia.
    Sparnins, Edgars
    Rubenis, Ojars
    Institute of Polymer Mechanics, University of Latvia.
    Joffe, Roberts
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Estimation of laminate stiffness reduction due to cracking of a transverse ply by employing crack initiation- and propagation-based master curves2008In: Mechanics of composite materials, ISSN 0191-5665, E-ISSN 1573-8922, Vol. 44, no 5, p. 441-450Article in journal (Refereed)
    Abstract [en]

    The applicability range of toughness-and strength-based criteria for progressive cracking of a transverse layer in a cross-ply composite laminate subjected to tensile loading is considered. Using a deterministic cracking model, approximate relations for the crack density as a function of stress are derived for initiation-and propagation-controlled types of cracking. The master-curve approach is applied to progressive cracking in glass/epoxy laminates. The accuracy of estimation of laminate stiffness reduction by using crack density master curves is evaluated.

  • 315. Andersson, A.
    et al.
    Fernberg, P.
    Sjödahl, Mikael
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Optical methods to study fracture of notched glass mat composites2000In: Proceedings / International Conference on Trends in Optical Nondestructive Testing: May 3 - 5, 2000, Hotel de la Paix, Lugano, Switzerland / [ed] Pramod K. Rostagi, Lugano: Ecole Polytechnique Fédérale de Lausanne , 2000Conference paper (Refereed)
  • 316.
    Andersson, Anders
    et al.
    Luleå tekniska universitet.
    Engström, Hans
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Wiklund, Greger
    Påsvetsning, upplegering och ytomsmältning (glasering) med högeffektlaser1983Report (Other academic)
  • 317.
    Andersson, Anders G.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Modelling flow with free and rough surfaces in the vicinity of hydropower plants2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Flow with free and rough surfaces near hydropower stations is of interest for both engineering and environmental applications. Here, Computational Fluid Dynamics simulations of free surface flow and flow over rough surfaces in regulated rivers were performed in applications such fish migration, spillway design and flow over rough surfaces as in hydropower tunnels or natural channels. For all the investigated applications it is typical with very large geometrical scales, high flow rates and highly turbulent flow. Modelling boundaries such as free water surfaces and rough walls presents a challenge and was given special attention as well as the treatment of turbulence. Validation of the numerical simulations was performed in all cases with methods such as acoustic measurements with an Acoustic Doppler Current Profiler (ADCP), Acoustic Doppler Velocimeter (ADV) and optical measurements with Particle Image Velocimetry (PIV).Numerical simulations have been used to evaluate the flow downstream the Stornorrfors hydropower plant in Umeälven with regards to upstream migrating fish. Field measurements with an ADCP were performed and the measurements were used to validate the simulations. By adding a fish ladder in the simulations it was possible to investigate the attraction water created from the fishway at different positions and angles. An additional possibility to create better attraction water and improve the conditions for upstream migrating fish was simulated by guiding the spill water from the hydropower dam through a smaller passage from the old river bed.Fish population data from the same location was compared with flow fields from numerical simulations. The population data was compared with variables such as velocity, vorticity and turbulence intensity. A correlation between fish detections and turbulence intensity was shown.Simulations on the spilling from a dam were performed and compared to experimental results from a physical scale model. ADV was used to measure the velocity and validate the simulations. Two different spillway configurations were considered and simulations with both the Rigid Lid model and the Volume of Fluids method were carried out. Water levels, velocities and the shape of the water surface were compared between simulations and experiments. The simulations capture both qualitative features such as a vortex near the outlet and show good quantitative agreement with the experiments.A wall with large surface roughness was created by laser scanning a tunnel. One of the side walls was down-scaled and used to create a rough wall in a channel with rectangular cross-section for both a numerical model and an experimental model. Numerical simulations were performed and validated by PIV-measurements in the experimental model.The resolution of the geometry for the rough surface was lowered in two steps and numerical simulations were performed for flow over all three surfaces. The difference in flow fields in the bulk and near wall region was investigated as well as the difference in turbulent quantities which can provide good input for a new model for surface roughness in applications with very large surface roughness and high velocities such as flow in hydropower tunnels or natural channels and rivers.

  • 318.
    Andersson, Anders G.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Simulations and measurements of free surface flow in regulated rivers2010Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Open channel flow near hydropower stations is of interest for both engineering and environmental applications. In this research project Computational Fluid Dynamics simulations of free surface flow in regulated rivers were applied with both fish migration and validation of numerical simulations in focus. In the first paper, numerical simulations has been used to evaluate the flow downstream a hydropower plant with regards to upstream migrating fish. Field measurements with an Acoustic Doppler Current Profiler were performed and the measurements were used to validate the simulations. In the second paper ,simulations on the spilling from a dam were performed and compared to experimental results from a physical scale model. The third paper deals with more in depth analysis of field measurements where the variations in the flow downstream a hydropower plant was examined.

  • 319.
    Andersson, Anders G.
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Andreasson, Patrik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Hellström, J. Gunnar I.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Lundström, T. Staffan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Modelling and validation of flow over a wall with large surface roughness2012Conference paper (Refereed)
  • 320.
    Andersson, Anders G.
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Andreasson, Patrik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Lundström, T. Staffan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    CFD-modelling and validation of free surface flow during spilling of reservoir in down-scale model2013In: Engineering Applications of Computational Fluid Mechanics, ISSN 1994-2060, E-ISSN 1997-003X, Vol. 7, no 1, p. 159-167Article in journal (Refereed)
  • 321.
    Andersson, Anders G.
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Andreasson, Patrik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Lundström, T. Staffan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Modellering av avbördning med fri vattenyta och validering i en skalmodell2011Conference paper (Refereed)
  • 322.
    Andersson, Anders G.
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Hellström, J. Gunnar I.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Andreasson, Patrik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Lundström, T. Staffan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Effect of spatial resolution of rough surfaces on numerically computed flow fields with application to hydraulic engineering2014In: Engineering Applications of Computational Fluid Mechanics, ISSN 1994-2060, E-ISSN 1997-003X, Vol. 8, no 3, p. 373-381Article in journal (Refereed)
    Abstract [en]

    In numerical simulations of flow over rough surfaces, the roughness is often not resolved but represented by a numerical model. The validity of such an assumption is investigated in this paper by Reynolds-Averaged Navier-Stokes simulations of flow over a surface with a large roughness. The surface was created from a high-resolution laser scanning of a real rock blasted tunnel. By reducing the geometrical resolution of the roughness in two steps, the importance of an appropriate surface description could be examined. The flow fields obtained were compared to a set-up with a geometrical flat surface where the roughness was represented by a modified form of the Launder and Spalding wall-function. The flow field over the surface with the lowest resolution was substantially different from those of the two finer resolutions and rather close to the results from the set-up with the wall-function. The results also yield that the finer the resolution is the more vorticity is formed close to the rough surface and more turbulence is generated.

  • 323. Andersson, Anders G.
    et al.
    Lindberg, Dan-Erik
    Swedish University of Agricultural Sciences, Department of Wildlife, Fish and Environmental Studies.
    Lindmark, Elianne
    Leonardsson, Kjell
    Swedish University of Agricultural Sciences, Department of Wildlife, Fish and Environmental Studies.
    Andreasson, Patrik
    Lundqvist, Hans
    Swedish University of Agricultural Sciences, Department of Wildlife, Fish and Environmental Studies.
    Lundström, Staffan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    A numerical study of the location and function of the entrance of a fishway in a regulated river2010In: 8th International Symposium on ECOHYDRAULICS: Bridging between Ecology and Hydraulics and Leading the Society's New Need - Living with Nature, 2010, p. 277-284Conference paper (Refereed)
    Abstract [en]

    Simulation driven design with Computational Fluid Dynamics has been used to evaluate the flow downstream a hydropower plant with regards to upstream migrating fish. Field measurements with an Acoustic Doppler Current Profiler were performed and the measurements were used to validate the simulations. The measurements indicate a more unstable flow than the simulations and the tailrace jet from the turbines is stronger in the simulations. The simulations are however considered to capture the important features of the flow in a way that makes them viable for attraction water simulations. A fishway entrance was included in the simulations and the subsequent attraction water was evaluated for two positions and two angles of the entrance at different turbine discharges. Results show that both positions are viable and that a position where the flow from the fishway does not have to compete with the flow from the power plant will generate superior attraction water. Simulations were also performed further downstream where the flow from the turbines meets the old river bed which is the current fish passage for upstream migrating fish. A modification of the old river bed was made in the model as one scenario to generate better attraction water. This considerably increases the attraction water although it cannot compete with the flow from the tailrace tunnel.

  • 324.
    Andersson, Anders G.
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Lindberg, Dan-Erik
    SLU.
    Lindmark, Elianne
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Leonardsson, Kjell
    SLU.
    Andreasson, Patrik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Lundqvist, Hans
    SLU.
    Lundström, T. Staffan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    A study of the location of the entrance of a fishway in a regulated river with CFD and ADCP2012In: Modelling and Simulation in Engineering, ISSN 1687-5591, E-ISSN 1687-5605, Vol. 2012, article id 327929Article in journal (Refereed)
    Abstract [en]

    Simulation-driven design with computational fluid dynamics has been used to evaluate the flow downstream of a hydropower plant with regards to upstream migrating fish. Field measurements with an Acoustic Doppler Current Profiler were performed, and the measurements were used to validate the simulations. The measurements indicate a more unstable flow than the simulations, and the tailrace jet from the turbines is stronger in the simulations. A fishway entrance was included in the simulations, and the subsequent attraction water was evaluated for two positions and two angles of the entrance at different turbine discharges. Results show that both positions are viable and that a position where the flow from the fishway does not have to compete with the flow from the power plant will generate superior attraction water. Simulations were also performed for further downstream where the flow from the turbines meets the old river bed which is the current fish passage for upstream migrating fish. A modification of the old river bed was made in the model as one scenario to generate better attraction water. This considerably increases the attraction water although it cannot compete with the flow from the tailrace tunnel.

  • 325. Andersson, Anders G.
    et al.
    Lindmark, Elianne
    Lundström, Staffan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    CFD-modell av turbinutloppet i Stornorrfors2009In: Svenska mekanikdagarna: Södertälje 2009, Stockholm: Svenska nationalkommittén för mekanik , 2009, p. 106-Conference paper (Other academic)
  • 326.
    Andersson, Anders G.
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Lundström, Kristoffer
    Andreasson, Patrik
    Lundström, Staffan
    Simulation of free surface flow in a spillway with the rigid lid and volume of fluid methods and validation in a scale model2010In: Proceedings, Fifth European Conference on Computational Fluid Dynamics / [ed] Jose C. F. Pereira; Adelia Sequeira; Jose M. C. Pereira, 2010Conference paper (Refereed)
    Abstract [en]

    Simulations on the spilling from a dam were performed and compared to experimental results from a physical scale model. Both mechanical and acoustic methods to measure the velocity were used. The model has three gates leading into the spillway that can be maneuvered separately. At first two of the gates were closed and the inlet flow was high enough to get a fully wetted outlet at the third gate. This case was simulated with a rigid lid approximation since the water surface was considered to be plane. The water surface level was taken from the scale model. In the second case, all three gates were open resulting in a free water surface through all the gates to the spillway. This case was simulated with the Volume of Fluids method were both water and air phase were considered. Water levels, velocities and the shape of the water surface were compared between simulations and experiments. The simulations capture both qualitative features such as a vortex near the outlet and show good quantitative agreement with the experiments.

  • 327. Andersson, Anders G.
    et al.
    Westerberg, Lars-Göran
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Papathanasiou, T.D.
    Department of Mechanical Engineering, University of Thessaly.
    Lundström, Staffan
    Flow through a two-scale porosity material2009In: Research Letters in Materials Science, ISSN 1687-6822, E-ISSN 1687-6830, article id 701512Article in journal (Other academic)
    Abstract [en]

    Flow through a two-scale porous medium is here investigated by a unique comparison between simulations performed with computational fluid dynamics and the boundary element method with microparticle image velocimetry in model geometries.

  • 328. Andersson, Anders G.
    et al.
    Westerberg, Lars-Göran
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Papathanasiou, Thanasis
    Lundström, Staffan
    Fluid flow through porous media with dual scale porosity2008In: Proceedings of the 19th International Symposium on Transport Phenomena (ISTP-19): Reykjavik, Iceland, August 17-21, 2008 / [ed] Sigurdur Brynjolfsson; Olafur Petur Palsson; Jong H. Kim, University of Iceland, Faculty of Industrial Engineering, Mechanical Engineering and Computer Science , 2008Conference paper (Refereed)
    Abstract [en]

    Flow in two scale porous media takes place in applications such as advanced composites manufacturing. Knowledge of this flow is of general importance and is crucial for filtration mechanisms when functional filler-particles are added to the liquid resin impregnating the fibrous preform. Means to model and experimentally visualise this flow is here investigated. In particular simulations performed with computational fluid dynamics and the boundary element method are compared to micro particle image velocimetry in a model geometry.

  • 329.
    Andersson, Anders
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Leonardsson, Kjell
    Swedish University of Agricultural Sciences, Department of Wildlife, Fish and Environmental Studies.
    Lindberg, Dan-Erik
    Swedish University of Agricultural Sciences, Department of Wildlife, Fish and Environmental Studies.
    Lundström, Staffan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Hellström, Gunnar
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Lundqvist, Hans
    Swedish University of Agricultural Sciences, Department of Wildlife, Fish and Environmental Studies.
    Describing fish passage in a river confluence with telemetry and CFD2016In: / [ed] Webb, JA, Costelloe, JF, CasasMulet, R, Lyon, JP, Stewardson, MJ, Melbourne: University of Melbourne , 2016Conference paper (Refereed)
    Abstract [en]

    The confluence between hydropower tailrace and the old river bed in Stornorrfors in the river Umeälven in the northern part of Sweden has shown to be the largest obstacle for upstream migrating salmon and sea trout during the migrating season. Fish are attracted to the high flow rate from the tailrace and will not migrate upstream in the old river bed being the passage to the fishway leading past the hydropower dam. By triangulating the movements of radio tagged fish using eight antennas in the confluence, it is here possible to describe the individual fish tracks left by radio tagged fish during the migrating season. These tracks are then compared with three-dimensional Computational Fluid Dynamics (CFD) simulations of the confluence. By simulating the most common combinations of turbine flow and spill flow in the old river bed it is then possible to find correlations between individual fish movements and flow parameters such as velocity, turbulence intensity or vorticity for different flow combinations. It was previously assumed that fish had trouble locating the old river bed, the results of the triangulation however shows that most fish finds the old river bed within a few days but does not chose to migrate until several days (or weeks) later. The main issue to be solved is therefore not how to attract the fish to the old river bed but rather how to create favorable conditions in the old river bed so that migrating fish are more inclined to take that path upstream.

  • 330. Andersson, Angelica
    et al.
    Mohan, N. Krishna
    Sjödahl, Mikael
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Molin, Nils-Erik
    TV shearography: quantitative measurement of shear-magnitude fields by use of digital speckle photography2000In: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 39, no 16, p. 2565-2568Article in journal (Refereed)
    Abstract [en]

    Digital speckle photography combined with TV shearography is developed for precise measurement of the magnitude of the shear field in a linear shear configuration. As an application the method is implemented to determine the slope-change variations of a three-dimensional object with TV shearography in which the shear magnitude is obtained with the digital speckle photography technique

  • 331.
    Andersson, Angelica
    et al.
    Luleå tekniska universitet.
    Runnemalm, Anna
    Luleå tekniska universitet.
    Sjödahl, Mikael
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Digital speckle pattern interferometry: fringe retrieval for large in-plane deformations with digital speckle photography1999In: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 38, no 25, p. 5408-5412Article in journal (Refereed)
    Abstract [en]

    The compensation of large in-plane motions in digital speckle-pattern interferometry (DSPI) with the use of digital speckle photography (DSP) is demonstrated. Ordinary recordings of DSPI are recombined and analyzed with DSP. The DSP result is used to compensate for the bulk speckle motion prior to calculation of the phase map. This results in a high fringe contrast even for deformations of several speckle diameters. In addition, for the case of an in-plane deformation, it is shown that the absolute phase change in each pixel may be unwrapped by use of the DSP result as an initial guess. The principles of this method and experiments showing the in-plane rotation of a plate and the encounter of two rounded plates are presented

  • 332. Andersson, Börje
    et al.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Thermal stresses in large butt-welded plates1981In: Journal of thermal stresses, ISSN 0149-5739, E-ISSN 1521-074X, Vol. 4, no 3-4, p. 491-500Article in journal (Refereed)
    Abstract [en]

    In shipyard panel-production lines several rectangular plates ae butt welded to form large panels. One problem is the tendency of hot cracking in the end portion of the butt weld. In this paper transient temperature fields and stress fields in butt-welded plates are calculated using the finite-element method. The calculations are performed for different welding speeds, for different heat inputs, and for one-sided and two-sided welding.

  • 333.
    Andersson, H.M.
    et al.
    Luleå tekniska universitet.
    Lundström, Staffan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Gebart, Rikard
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Synnergren, Per
    Luleå tekniska universitet.
    Application of digital speckle photography to measure thickness variations in the vacuum infusion process2003In: Polymer Composites, ISSN 0272-8397, E-ISSN 1548-0569, Vol. 24, no 3, p. 448-455Article in journal (Refereed)
    Abstract [en]

    A new method to measure the movement of the flexible bag used in vacuum infusion is presented. The method is based on an in-house developed stereoscopic digital speckle photography system (DSP). The advantage with this optical method, which is based on cross-correlation, is that the deflection of a large area can be continuously measured with a great accuracy (down to 10 μm. The method is at this stage most suited for research but can in the long run also be adopted in production control and optimization. By use of the method it was confirmed that a ditch is formed at the resin flow front and that there can be a considerable and seemingly perpetual compaction after complete filling. The existence of the ditch demonstrates that the stiffness of the reinforcement can be considerably reduced when it is wetted. Hence, the maximum fiber volume fraction can be larger than predicted from dry measurements of preform elasticity. It is likely that the overall thickness reduction after complete filling emanates from lubrication of the fibers combined with an outflow of the resin. Besides, the cross-linking starts and the polymer shrinks. Hence, the alteration in height will continue until complete cross-linking is reached.

  • 334.
    Andersson, Håkan A.
    et al.
    Umeå universitet.
    Isaksson, Anders
    Umeå universitet.
    Lindbergh, Lars
    Umeå universitet.
    Nilsson, Henrik
    Umeå universitet.
    Peterson, Christer
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Företagets finanser2008Book (Other (popular science, discussion, etc.))
  • 335.
    Andersson, Jan-Erik
    et al.
    SP Sveriges Tekniska Forskningsinstitut, SP Trä.
    Nordman, Roger
    SP Sveriges Tekniska Forskningsinstitut, SP Energiteknik.
    Vikberg, Tommy
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Energy mapping in the sawmill industry with focus on drying kilns2013Conference paper (Refereed)
    Abstract [en]

    The forest industry stands for approximately 11 % of Sweden’s total export. However, the forest industry is energy intensive. In 2008, sawmill industry alone consumed almost 8,7 TWh of energy, corresponding to 5 % of the Swedish industries total energy consumption. Out of their total consumption, 2200 GWh was electric power, 194 GWh heating oil , 4229 GWh bio-fuel, 574 GWh district heating, and other fuels such as diesel 1503 GWh [1].The project ”EESI- Energy Efficiency in the Sawmill Industry” was started in the spring of 2010 with the aim of demonstrating the possibilities to reduce the energy consumption in the sawmill industry with 20 % by 2020. 16 sawmill corporations and 14 equipment suppliers has joined the project which is carried out in two phases of which the first phase was carried out during 2010 and 2011. EESI has now reached half time and the first energy-saving implementations have been completed at the participating sawmills.This paper presents the energy-mapping, measurements and modelling performed by the participating sawmills during the first phase of the project [2, 3]. The average energy consumption per sawn cubic metre of boards varied between approximately 300 to 500 kWh/m3. Out of this, the electricity consumption was on average 85 kWh/m3, bio-fuel 290 kWh/m3 and diesel 1.8 l/m3.However, the main concern from sawmills regarding energy consumption was the wood drying process. The striking results from the preliminary measurements were the large variation in energy consumption even with similar drying kilns. This was especially apparent for the heat consumption in kiln dryers which could vary as much as 50 % for the same dimension of spruce planks.The results from the first phase of the project resulted in a large number of actions in order to reduce the energy consumption which are now being implemented or have already been completed. Examples of those actions are: simplified management system adapted to sawmills, weighing of packages for more accurate wood drying, reduced speed or intermittent operation of the air circulating fans in batch kilns and moisture content measurements of bio-fuel.References[1] Statistiska centralbyrån (SCB), 2013, Industrins årliga energianvändning 2011, Slutliga uppgifter, EN23SM1301, ISSN 1654-367X. (In Swedish). [2] Andersson, J-E., Lycken, A., Nordman, R., Olsson, M., Räftegård, O., and Wamming, T. State of the art – Energianvändning i den svenska sågverksindustrin. SP Rapport 2011:42, ISBN 978-91-86622-72-5. (In Swedish).[3] Andersson, J-E., Räftegård, O., Lycken, A., Olsson, M., Wamming, T., and Nordman, R. Sammanställning av energimätningar från EESI fas 1. SP Rapport 2011:41, ISBN 978-91-86622-71-8. (In Swedish).

  • 336.
    Andersson, Jan-Olof
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Energy and Resource Efficiency in Convective Drying Systems in the Process Industry2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Growing concern about environmental problems has increased the public’s interest in energy usage. The subsidies for biomass, together with the rising energy prices have madebiomass a desirable product on the energy market. This has led to higher biomass prices and an increased interest in improving the resource and energy efficiency associated withbiomass production. Biofuel is an interesting substitute for fossil fuels to decrease the greenhouse gas emissions. One challenge with biofuels is to find sufficient amounts of biomass since the foresting is already close to its maximum sustainable capacity. Sawmills are important suppliers to the biomass market, since the sawmill industries produce a significant part of the available biomass. This Doctoral thesis focuses on strategies to decrease biomass usage in order to increase the biomass availability at the market. This is done through mapping and system analysis of energy and material streams for process industries using convective drying techniques. The energy analysis is mainly done through thermodynamics and psychrometry. Available state-of-the-art technologies on the market are studied to determine their potential for decreasing the total energy usage in sawmills. Integration possibilities between biomass consumers are also investigated through process integration with mathematical programming and pinch analysis. Energy efficiency of berry drying in a juice plant is also studied. The main conclusions are as follows. The heat demand of drying lumber in Swedish sawmills is about 4.9 TWh/year. Using available state-of-the-art technologies (heat pumps,heat exchangers and open absorption system) it is possible to reduce the energy usagesubstantially. If the recovered heat is used for heat sinks inside, or close to, the sawmill, the energy efficiency can be improved significantly. Using mechanical heat pumps nationally could save 4.9 TWh/year ofheatandgenerate0.62 TWh/year of surplus heat, at the cost of 1TWh/year of electricity. Using open absorption systems nationally, could save 3.4 TWh/year of heat, at the cost of only 0.05 TWh/year of electricity. Saving this heat means that an even larger amount of biomass will be saved, since there are heat losses during the combustion and distribution. Another way of saving energy is to displacethe starting time between batch kilns, and recycle evacuation air between the kilns. Nationally, this could save 0.44 TWh/year of heat. Industrial site integration between sawmills and the main biomass users (pelleting plants an d CHP plants) can decrease the use of biomass in the industrial site with 43% wt compared to a standalone site with a comparable production. Nationally, this could save up to 7.1 TWh/year of biomass. Despite the significant savings in terms of resources, it is not profitable due to the currentprice ratio between district heating and biomass. Finally, drying and separationof berry press cake in a juice plant is found to be possible using only energy from the exhaust gases of the steam boiler, if the drying air is sufficientlyrecycled. Instead of composting the press cake, the dried and separated skins and seeds could then be sold.

  • 337.
    Andersson, Jan-Olof
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Improving energy use in sawmills: from drying kilns to national impact2012Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Increased concern about environmental problems has amplified the public`s interest inenergy usage. The improved subsidies for biomass, together with the rising energy priceshave made biomass a desirable product on the energy market. Energy intensive industries inthe field of wood and biomass now have nowadays an opportunity to decrease energyconsumption and to sell their biomass surplus on the energy market.This Licentiate thesis focuses on strategies to decrease biomass usage in sawmill industriesin order to increase their surplus biomass and increase their profit. This is done throughsystem analysis of sawmill industries in terms of mass and energy flows. The energyanalysis focuses on the drying kiln using psychrometric and thermodynamic relationships.State-of-the-art technologies, available on the market, have been studied to determine theirpossible effect on the total energy usage in the sawmills.This study was undertaken to determine the national use of energy due to sawmills and thepotential magnitude of improvements. Sawmills are important suppliers to the biomassmarket, since medium to large capacity sawmills contribute with 95% of the Swedish annuallumber (sawn boards) production (17.3 Mm3) with a lumber interchange of only 47%. Therest of the timber (unsawn logs) is transformed into biomass through the lumber productionprocesses. An essential part (12%) of the timber is used for supplying heat to the productionprocesses, mainly to the drying process which is the most time and heat consuming processin the sawmill. The main conclusions are that the heat demand for drying lumber in Swedishsawmills was found to be 4.9 TWh per year and the drying process can be made moreeffective by use of state-of-the-art technologies. Hence the internal use of biomass insawmills can be decreased, thereby increasing the biomass that can be sold to the marketand/or to generate heat and/or electricity, resulting in more profitable sawmills and asignificant increased supply of biomass to the market.It was also found that with available state-of-the-art technologies it is possible to recycle theheat in the evacuated air from the dryer, and if the recovered heat is used for heat sinksinside or close to the sawmill a large decrease of the energy usage can be achieved. If thetechnologies are implemented up to 5.56 TWh of equivalent biomass can be saved,depending on the technology, the specific sawmill conditions, kiln settings and dryingsystem operation. However, some of the considered technologies consume a substantialamount of electricity, so the economic benefit should be carefully evaluated.

  • 338.
    Andersson, Jan-Olof
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Elfgren, Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Grip, Carl-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Improved energy efficiency in juice production through waste heat recycling2013In: International Conference on Applied Energy, ICAE 2013, 2013Conference paper (Refereed)
    Abstract [en]

    The global demand for Nordic wild berries has increased steadily, partly due to their healthy properties and their good taste. Juice concentrate is produced by pressing berries and heating up the juice. The by-products are berry skins and seeds. Traditionally, the by-products have been composted. Higher competiveness can be achieved by decreasing the production cost and increasing the product values. The berry skins and seeds have a commercial value since they are rich in vitamins and nutrients. To use and sell these by-products, they need to be separated from each other and dried to a moisture content of less than 10 %wt. A berry juice industry in the north of Sweden has been studied in order to increase the energy and resource efficiency and optimize the quality and yield of different berry fractions. This was done by means of process integration with thermodynamics and psychrometry along with measurements of the berry juice production processes. Our calculations show that the drying system could be operated at full without any external heat supply. This could be achieved by increasing the efficiency of the dryer by recirculating 80 % of the drying air and by heating the air with heat from the flue gases from the industrial boiler. This change would decrease the need for heat in the dryer with about 64 %. The total heat use for the plant could thereby be decreased from 1204 kW to 1039 kW. The proposed changes could be done without compromising the production quality or the lead time.

  • 339.
    Andersson, Jan-Olof
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Elfgren, Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Westerlund, Lars
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Improved energy efficiency in juice production through waste heat recycling2014In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 130, no S1, p. 757-763Article in journal (Refereed)
    Abstract [en]

    Berry juice concentrate is produced by pressing berries and heating up the juice. The by-products are berry skins and seeds in a press cake. Traditionally, these by-products have been composted, but due to their valuable nutrients, it could be profitable to sell them instead. The skins and seeds need to be separated and dried to a moisture content of less than 10 %wt (on dry basis) in order to avoid fermentation. A berry juice plant in the north of Sweden has been studied in order to increase the energy and resource efficiency, with special focus on the drying system. This was done by means of process integration with mass and energy balance, theory from thermodynamics and psychrometry along with measurements of the juice plant. Our study indicates that the drying system could be operated at full capacity without any external heat supply using waste heat supplied from the juice plant. This would be achieved by increasing the efficiency of the dryer by recirculation of the drying air and by heat supply from the flue gases of the industrial boiler. The recirculation would decrease the need of heat in the dryer with about 52%. The total heat use for the plant could thereby be decreased from 1262 kW to 1145 kW. The improvements could be done without compromising the production quality.

  • 340.
    Andersson, Jan-Olof
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Toffolo, Andrea
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Improving energy efficiency of sawmill industrial sites by integration with pellet and CHP plants2013In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 111, p. 791-800Article in journal (Refereed)
    Abstract [en]

    An essential strategy to lower energy and resources consumption is the development of highly integrated industrial sites including different kind of plants complementing one another. Sawmills are huge biomass suppliers to other industries, such as pulp and paper mills, pellet plants and CHP plants, and part of the biomass is also used for the internal heat requirement. In this paper the integration of a sawmill with a pellet plant and a CHP plant is investigated using advanced process integration techniques, so that the thermal energy and the electricity produced in the CHP plant by burning part of the sawmill biomass output are used for the heat and power requirements of the other two industries. The results show that up to 18% of the biomass by-products from the sawmill can be saved, but from the economic point of view the ratio between prices of the thermal energy sold for district heating and the low quality biomass has to be lower than the present one to make the integrated design solution more attractive than separate plant operation.

  • 341.
    Andersson, Jan-Olof
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Westerlund, Lars
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Improved energy efficiency in sawmill drying system2014In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 113, p. 891-901Article in journal (Refereed)
    Abstract [en]

    The worldwide use of biomass has increased drastically during the last decade. At Swedish sawmills about half of the entering timber becomes lumber, with the remainder considered as by-product (biomass). A significant part of this biomass is used for internal heat production, mainly for forced drying of lumber in drying kilns. Large heat losses in kilns arise due to difficulties in recovering evaporative heat in moist air at low temperatures. This paper addresses the impact of available state-of-the-art technologies of heat recycling on the most common drying schemes used in Swedish sawmills. Simulations of different technologies were performed on an hourly basis to compare the heat and electricity demand with the different technologies. This was executed for a total sawmill and finally to the national level to assess the potential effects upon energy efficiency and biomass consumption. Since some techniques produce a surplus of heat the comparison has to include the whole sawmill. The impact on a national level shows the potential of the different investigated techniques. The results show that if air heat exchangers were introduced across all sawmills in Sweden, the heat demand would decrease by 0.3 TWh/year. The mechanical heat pump technology would decrease the heat demand by 5.6 TWh/year and would also produce a surplus for external heat sinks, though electricity demand would increase by 1 TWh/year. The open absorption system decreases the heat demand by 3.4 TWh/year on a national level, though at the same time there is a moderate increase in electricity demand of 0.05 TWh/year. Introducing actual energy prices in Sweden gives an annual profit (investment cost excluded) on national level for the open absorption system of almost 580 million SEK. For the mechanical heat pump technology the profit is 204 million SEK and for the traditional heat exchanger the profit is significant lower. It has been found that a widespread implementation of available energy recovery technologies across Swedish sawmills would result in substantial savings of biomass for other purposes in the society

  • 342.
    Andersson, Jan-Olof
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Westerlund, Lars
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    MIND based optimisation and energy analysis of a sawmill production line2010In: PRES 2010: 13th Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction, 28 August - 1 September 2010, Prague, Czech Republic, 2010, p. 1-5Conference paper (Refereed)
    Abstract [en]

    The lumber drying process uses about 80 % of the total heat consumption in sawmills. Efforts to increase energy efficiency in lumber kilns were very restricted due to the low biomass prices between the 80th and 90th. Today with higher production and biomass prices, companies want to decrease their own use of biomass and increase the heating system efficiency. The study proposes alternative ways to reduce the heat consumption at batch kilns by recirculation of the evacuation air and addresses particular problem encountered in sawmills. Which produce their own heat and suffer from bottlenecks in the heating system due to high heat load from the dryers and increased production. The study shows the possibility to recycle the evacuation air from each kiln which reduces the overall heat consumption of the kilns by 12 %. At nationally basis this corresponds to a decrease of heat consumption of 440 GWh annually, among Swedish sawmill. This will decrease the individual heat consumption of the kilns, heat load in the heating system and the bottleneck effect in the drying process. The decreased own use of biomass brings benefits of more available biomass to the market and increased profits for the sawmill.

  • 343.
    Andersson, Jan-Olof
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Westerlund, Lars
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Surplus biomass through energy efficient kilns2011In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 88, no 12, p. 4848-4853Article in journal (Refereed)
    Abstract [en]

    The use of biomass in the European Union has increased since the middle of the 1990s, mostly because of high subsidies and CO2 emission regulation through the Kyoto protocol. The sawmills are huge biomass suppliers to the market; out of the Swedish annual lumber production of 16.4 Mm3, 95% is produced by medium to large-volume sawmills with a lumber quotient of 47%. The remaining part is produced as biomass. An essential part (12%) of the entering timber is used for supply of heat in their production processes, mostly in the substantial drying process. The drying process is the most time and heat consuming process in the sawmill. This study was undertaken to determine the sawmills’ national use of energy and potential magnitude of improvements. If the drying process can be made more effective, sawmills’ own use of biomass can be decreased and allow a considerably larger supply to the biomass market through processed or unprocessed biomass, heat or electricity production. The national electricity and heat usage when drying the lumber have been analysed by theoretical evaluation and experimental validation at a batch kiln. The main conclusion is that the heat consumption for drying lumber among the Swedish sawmills is 4.9 TW h/year, and with available state-of-the-art techniques it is possible to decrease the national heat consumption by approximately 2.9 TW h. This additional amount of energy corresponds to the market’s desire for larger energy supply.

  • 344.
    Andersson, Jim
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Systems Analysis of Chemicals Production via Integrated Entrained Flow Biomass Gasification: Quantification and improvement of techno-economic performance2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Lignocellulosic biomass gasification is a promising production pathway for green chemicals, which can support the development towards a more sustainable society where fossil fuels are replaced. To be able to compete with fossil fuels, a highly efficient production of biomassbased products is required in order to maximize overall process economics and to minimizenegative environmental impact. Large production plants will likely be required to obtain favourable economy-of-scale effects and reasonable production cost. Entrained flow gasification (EFG) is a favourable technology due to its suitability for large-scale implementation and ability to produce a high quality syngas from various biomass feedstocks. In order to estimate overall energy efficiency and production costs for gasification-based biorefineries, it is important to be able to characterise the gasifiers’ performance. This in turnrequires reliable estimations of the gasification process. Integration of EFG-based biorefineries with existing pulp mills or other large-scale forestindustries can be achieved by integration of material and/or energy flows, as well as by coutilisation of process equipment. This could potentially induce both technical and economic added-values. At chemical pulp mills, an important feedstock for green chemical production may be the black liquor from the pulp production, since it provides an attractive combinationof advantages. The black liquor availability is, however, directly correlated to the pulp production (i.e. the mill size) and the potential green chemical production volume via pure black liquor gasification (BLG) is therefore limited.In this thesis, two systems are considered that expand on the BLG concept with the intent to increase the chemical production volume, since this could generate positive economy-of-scale effects and is a rather unexamined area. In addition to this, an EFG configuration entailing a lower availability related risk for the considered host pulp mill is also considered. The threeconsidered integrated systems are: (i) co-gasification of biomass-based pyrolysis oil blended with black liquor for methanol production, (ii) parallel operation of BLG and solid biomass EFG for methanol or ammonia production, and (iii) replacing the bark boiler with solid biomass EFG for methanol or ammonia production. These system solutions establish a combination of material, energy and equipment integration. The main aim of this thesis is to increase the knowledge of the characteristics of entrained flow biomass gasification systems and their opportunities for integration in existing industries for production of green chemicals (methanol and ammonia). An appropriate modelling framework that combines chemical modelling on a high level of detail with holistic industrial site modelling is designed and used to identify and quantify energetic and economic addedvalues for the integrated biorefineries. Mathematical process integration models based on Mixed Integer Linear Programming (MILP) of pulp mills are used to study integration of the biomass gasification systems with the mills. An iterative modelling approach is applied between the process integration model and the detailed biomass gasification models based on Aspen Plus or a Matlab-based thermodynamic equilibrium model. As a complement to themodelling framework, a multi-scale equivalent reactor network (ERN) solid biomass-based EFG model is developed to be able to identify and study influential parameters on the gasifiers’ performance in the Aspen Plus platform. This is approached by considering the effect of mass and heat transfer as well as chemical kinetics. The results show that replacing a recovery or a bark boiler with EFG for green chemicals production improves the overall energy system efficiency and the economic performance,compared to the original operation mode of the mill as well as compared to a stand-alone gasification plant. Significant economy-of-scale effects can be obtained from co-gasification of black liquor and pyrolysis oil. Co-gasification will add extra revenue per produced unit of methanol and reduces the production cost significantly compared to gasification of pure pyrolysis oil. In general, integrated EFG systems producing methanol sold to replace fossilgasoline are shown to constitute attractive investments if the product is exempted from taxes. Ammonia produced via EFG is per unit of produced chemical significantly more capital intense than the corresponding system producing methanol. The economic viability in the considered ammonia configurations is therefore found to be lower compared to methanol.The ERN model is shown to be able to estimate key performance indicators such as carbon conversion, cold gas efficiency, syngas composition, etc. for a real gasification process, showing good agreement with experimental results obtained from a pilot scale gasifier. This simulation tool can in future work be implemented in more global models to study and use to improve the techno-economic performance of EFG-based biorefineries, by quantifying theinfluence of important operational parameters. The main conclusion from this work is that production of green chemicals from biomass EFG integrated with a pulp mill is techno-economically advantageous compared to stand-alonealternatives. It is also concluded that the pulp mill size will be decisive for what integration route is the most favourable. Integration of an individual BLG plant with a pulp mill of maximum size would be the most economically beneficial alternative. However, the possibility to increase the green chemical production from a given black liquor volume improves the viability for integration in smaller mills. Increasing the production volume would therefore result in the highest efficiency and economic benefits given mill sizes up to300 kADt/y. From a resource perspective, this would however lead to an increased demand for biomass import to the mill, and this expansion could be limited by the overall availability of biomass resources.Keywords: Pulp mills, integration, biomass, gasification, green chemicals, methanol, ammonia.

  • 345.
    Andersson, Jim
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Techno-economic analysis of integrated biomass gasification for green chemical production2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Production of renewable motor fuels and green chemicals is important in the development towards a more sustainable society where fossil fuels are replaced. The global annual production of methanol and ammonia from fossil fuels is very large. Alternative production pathways are therefore needed to reduce emission of anthropogenic greenhouse gases and to reduce the fossil fuel dependency. Gasification of lignocellulosic biomass is one promising renewable alternative for that purpose. However, to be able to compete with fossil feedstocks, a highly efficient production of biomass-based products is required to maximize overall process economics and to minimize negative environmental impact. In order to reach reasonable production costs, large production plants will likely be required to obtain favourable economy-of-scale effects.Integrating large scale biofuel or green chemical production processes in existing pulp mills or in other large forest industries may provide large logistical and feedstock handling advantages due to the already existing biomass handling infrastructure. In addition, there are large possibilities to make use of different by-products. In chemical pulp mills, black liquor, a residue from pulp making, provides a good feedstock for the production of chemicals. It has previously been shown that investment in a black liquor gasification plant is advantageous regarding efficiency and economic performance compared to investment in a new recovery boiler. The potential production volume of green chemicals from black liquor is however limited since the availability of black liquor is strongly connected to pulp production. Increased chemical production volumes and thereby potential positive scale effects can be obtained either by adding other types of raw material to the gasification process or by increasing the syngas production by other gasification units operating in parallel. Several publications can be found regarding biomass gasification using one single feedstock and/or gasifier, but only a few consider cogasification of different fuels and dual gasification units. The overall aim of this thesis has therefore been to investigate technoeconomically the integration of biomass gasification systems in existing pulp and paper mills for green chemical production with the focus on creating economy-of-scale effects. The following system configurations were selected: i) a solid biomass gasifier that replaces the bark boiler in a pulp mill for methanol or ammonia production, ii) a solid biomass gasifier operated in parallel with a black liquor gasifier for methanol production, and iii) methanol production from gasification of black liquor blended with biomass-based pyrolysis oil. The main objectives were to find possible and measurable technically and economically added values for different integrated system solutions.The gasifier, the gas conditioning and synthesis were modelled in the commercial software Aspen Plus for material and energy balance calculations. A thermodynamic model developed for gasification of black liquor was used to simulate co-gasification of black liquor blended with pyrolysis oil. The outputs served as inputs for the process integration studies, where models based on Mixed Integer Linear Programming (MILP) were used. An iterative modelling approach between the two models was adopted to ensure that all constraints of the pulp and paper mill as well as for the gasification plant were met. The resulting material and energy balances were used to analyze the different system configurations in terms of overall energy efficiency and process economics. The results show that replacing the recovery or bark boiler with a biomass gasifier for green chemical production improves the overall energy system efficiency and the economic performance compared to the original operation mode of the mill and a non-integrated standalone gasification plant. Significant economy-of-scale effects were obtained when co-gasifying black liquor and pyrolysis oil. This adds extra revenue per produced unit of methanol compared to gasification of pure black liquor, even for pyrolysis oil prices that are considerably higher than projected future commercial scale production costs. Ingeneral, methanol sold to replace fossil gasoline showed good investment opportunities if exempted from taxes. Ammonia produced via gasification of lignocellulosic biomass is per unit of produced chemical significantly more capital intensive than methanol. The investment opportunity of the ammonia configuration is therefore diminished in comparison to methanol production.The main conclusion is that production of green chemicals via biomass gasification integrated in a pulp and paper mill is advantageous compared to stand-alone alternatives. Highest efficiencies and economic benefits are obtained for the systems where co-utilization of upstream (air separation unit) as well as downstream process equipment (gas conditioning units and synthesis loop) is possible.

  • 346.
    Andersson, Jim
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Furusjö, Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Wetterlund, Elisabeth
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Lundgren, Joakim
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Landälv, Ingvar
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Co-gasification of black liquor and pyrolysis oil: Evaluation of blend ratios and methanol production capacities2016In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 110, p. 240-248Article in journal (Refereed)
    Abstract [en]

    The main aim of this study is to investigate integrated methanol production via co-gasification of black liquor (BL) and pyrolysis oil (PO), at Swedish pulp mills. The objectives are to evaluate techno-economically different blends ratios for different pulp mill capacities. Furthermore, the future methanol production potential in Sweden and overall system consequences of large-scale implementation of PO/BL co-gasification are also assessed.It is concluded that gasification of pure BL and PO/BL blends up to 50% results in significantly lower production costs than what can be achieved by gasification of unblended PO. Co-gasification with 20–50% oil addition would be the most advantageous solution based on IRR for integrated biofuel plants in small pulp mills (200 kADt/y), whilst pure black liquor gasification (BLG) will be the most advantageous alternative for larger pulp mills. For pulp mill sizes between 300 and 600 kADt/y, it is also concluded that a feasible methanol production can be achieved at a methanol market price below 100 €/MW h, for production capacities ranging between 0.9 and 1.6 TW h/y for pure BLG, and between 1.2 and 6.5 TW h/y for PO/BL co-gasification. This study also shows that by introducing PO/BL co-gasification, fewer pulp mills would need to be converted to biofuel plants than with pure BLG, to meet a certain biofuel demand for a region. Due to the technical as well as organizational complexity of the integration this may prove beneficial, and could also potentially lower the total investment requirement to meet the total biofuel demand in the system. The main conclusion is that PO/BL co-gasification is a technically and economically attractive production route for production biomethanol.

  • 347.
    Andersson, Jim
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Lundgren, Joakim
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Techno-economic analysis of ammonia production via integrated biomass gasification2013Conference paper (Refereed)
  • 348.
    Andersson, Jim
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Lundgren, Joakim
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Techno-economic analysis of ammonia production via integrated biomass gasification2014In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 130, no S1, p. 484-490Article in journal (Refereed)
    Abstract [en]

    Ammonia (NH3) can be produced by synthesis of nitrogen and hydrogen in the Haber–Bosch process, where the economic challenge is the hydrogen production. Currently, substantial amounts of greenhouse gases are emitted from the ammonia industry since the hydrogen production is almost exclusively based on fossil feedstocks. Hydrogen produced via gasification of lignocellulosic biomass is a more environmentally friendly alternative, but the economic performance is critical. The main objective of this work was to perform a techno-economic evaluation of ammonia production via integrated biomass gasification in an existing pulp and paper mill. The results were compared with a stand-alone production case to find potential technical and economic benefits deriving from the integration. The biomass gasifier and the subsequent NH3 production were modelled using the commercial software Aspen Plus. A process integration model based on Mixed Integer Linear Programming (MILP) was used to analyze the effects on the overall energy system of the pulp mill. Important modelling constraints were to maintain the pulp production and the steam balance of the mill. The results showed that the process economics and energy performance are favourable for the integrated case compared to stand-alone production. The main conclusion was however that a rather high NH3 selling price is required to make both production cases economically feasible.

  • 349.
    Andersson, Jim
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Lundgren, Joakim
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Furusjö, Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Co-gasification of pyrolysis oil and black liquor for methanol production2013Conference paper (Refereed)
  • 350.
    Andersson, Jim
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Lundgren, Joakim
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Furusjö, Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Landälv, Ingvar
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Co-gasification of pyrolysis oil and black liquor for methanol production2015In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 158, p. 451-459Article in journal (Refereed)
    Abstract [en]

    One alternative to reduce the motor fuel production cost and improve the operational flexibility of a black liquor gasification (BLG) plant is to add pyrolysis oil to the black liquor feed and co-gasify the blend. The objective of this study was to investigate techno-economically the possibility to increase methanol production at a pulp mill via co-gasification of pyrolysis oil and black liquor. Gasifying a blend consisting of 50% pyrolysis oil and 50% black liquor on a wet mass basis increases the methanol production by more than 250%, compared to gasifying the available black liquor only. Co-gasification would add extra revenues per produced unit of methanol (IRR > 15%) compared to methanol from unblended BLG (IRR 13%) and be an attractive investment opportunity when the price for pyrolysis oil is less than 70 €/MW h. The economic evaluation was based on a first plant estimate with no investment credit for the recovery boiler and a methanol product value volumetric equivalent to conventional ethanol, both these conditions will not applicable when the technology has been fully commercialized.

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