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  • 1.
    Anukam, Anthony
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Famewo, Elizabeth Bosede
    University of Fort Hare, South Africa.
    Frodeson, Stefan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Improving the understanding of the bonding mechanism of primary components of biomass pellets through the use of advanced analytical instruments2019In: Journal of wood chemistry and technology, ISSN 0277-3813, E-ISSN 1532-2319, p. 1-18Article in journal (Refereed)
    Abstract [en]

    Previous studies have attempted to explain forces holding particles together in densified biomass pellets using theories of forces of attraction between solid particles, forces of adhesion and cohesion, solid bridges and mechanical interlocking bonds including interfacial forces and capillary pressure. This study investigated the bonding mechanism of primary biomass components in densified pellets through the use of advanced analytical instruments able to go beyond what is visible to the naked eye. Data obtained were used to predict how primary biomass components combine to form pellets based on the theory of functional groups and the understanding of structural chemistry. Results showed that hydroxyl and carbonyl functional groups played key roles in helping to identify the type of forces acting between individual particles, at a molecular level. At a microscopic level, morphological examination of the pellet clearly showed solid bridges caused by intermolecular bonding from highly electronegative polar functional groups linked to cellulose and hemicellulose.

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  • 2.
    Anukam, Anthony
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Henrikson, G.
    Frodeson, Stefan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Ståhl, Magnus
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    A review of the mechanism of bonding in densified biomass pellets2021In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 148, article id 111249Article in journal (Refereed)
    Abstract [en]

    The production of durable biomass pellets have always been challenged by several factors including the lack of understanding of the mechanism involved in how particles combine to form pellets under standard conditions of the pellet press. This is because contributing factors span several molecular, microscopic, and even nanoscopic levels as biomass undergoes pelleting. The characteristics of the bonds formed between the combining particles and their relevance to the quality of pellets remains vague, no matter how quality is defined. However, even though few researchers have attempted to explain the mechanism of bonding in densified biomass pellets using different theories, none of their hypotheses supports particle bonding from a structural chemistry perspective. There are still no clear explanations which consider the role of molecular structure and the interactions of substances as milled biomass undergo pelleting. In view of these arguments therefore, this review presents an in-depth analysis of a structural chemistry perspective of the mechanism of bonding and the use of additives in densified biomass pellets and helps identify research areas needed to facilitate better understanding of bonding in densified biomass pellets. The status of current research in biomass pelleting, types of materials suitable as additives and their structural characteristics, as well as the current technical specifications of using additives are also discussed.

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  • 3.
    Anukam, Anthony Ike
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Frodeson, Stefan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Bosede Famewo, Elisabeth
    University of Fort Harare, South Africa.
    Nyamukamba, Pardon
    Cape Peninsula University, South Africa.
    Characterization of pure and blended pellets made from Norway spruce and pea starch: A comparative study of bonding mechanism relevant to quality2019In: Energies, E-ISSN 1996-1073, Vol. 12, no 23, p. 1-22, article id 4415Article in journal (Refereed)
    Abstract [en]

    The mechanism of bonding in biomass pellets is such a complex event to comprehend, as the nature of the bonds formed between combining particles and their relevance to pellet quality are not completely understood. In this study, pure and blended biomass pellets made from Norway spruce and pea starch were characterized using advanced analytical instruments able to provide information beyond what is visible to the human eye, with intent to investigate differences in bonding mechanism relevant to quality. The results, which were comprehensively interpreted from a structural chemistry perspective, indicated that, at a molecular level, the major disparity in bonding mechanism between particles of the pellets and the quality of the pellets, defined in terms of strength and burning efficiency, were determined by variation in the concentration of polar functional groups emanating from the major organic and elemental components of the pellets, as well as the strength of the bonds between atoms of these groups. Microscopic-level analysis, which did not provide any clear morphological features that could be linked to incongruity in quality, showed fracture surfaces of the pellets and patterns of surface roughness, as well as the mode of interconnectivity of particles, which were evidence of the production of pellets with dissimilarities in particle bonding mechanism and visual appearance.

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  • 4.
    Anukam, Anthony
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013). University of Fort Hare, South Africa.
    Okoh, Omobola
    University of Fort Hare, South Africa.
    Mamphweli, Sampson
    Stellenbosch University, South Africa.
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    A comparative analysis of the gasification performances of torrefied and untorrefied bagasse: Influence of feed size, gasifier design and operating variables on gasification efficiency2018In: International Journal of Engineering & Technology, E-ISSN 2227-524X, Vol. 7, no 2, p. 859-867Article in journal (Refereed)
    Abstract [en]

    This study conducted a comparative assessment of the gasification performances of torrefied and untorrefied bagasse with emphasis on feed size, gasifier design and operating conditions that would influence gasification efficiency. Torrefaction greatly improved the characteristics of bagasse and had significant impact on its gasification performance. The gasifier design parameters studied were throat angle and throat diameter. Temperature of input air and feed input were the gasifier operating conditions examined in the course of the gasification processes of both torrefied and untorrefied bagasse. These parameters were considered the most critical operating parameters that affect gasifier performance and, correlation between the parameters was established in the course of gasification. The results obtained showed higher gasification efficiency for torrefied bagasse in comparison to untorrefied bagasse under varied conditions of gasification, which was attributed mainly to changes in the characteristics of the torrefied material.  

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  • 5.
    Bengtsson, Peder
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013). ASKO Appliances AB, Lidköping, Sweden.
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Concept Study of a New Method for Drying Dishware in a Heat Pump Dishwater2017In: Energy Efficiency, ISSN 1570-646X, E-ISSN 1570-6478, p. 1-10Article in journal (Refereed)
    Abstract [en]

    In a heat pump dishwasher, the whole dishwasher with the cabinet, dishware and process water is the heat sink, while a water tank, whose contents will freeze, is the heat source. The aim of the experimental concept study presented here was to evaluate a new drying method for a heat pump dishwasher. In this method, the drying of the dishware occurs as a fan circulates humid air in a closed system in which the water on the dishware evaporates inside the warm dishwasher cabinet and then condenses on a cold surface of the frozen water tank. The evaluation of drying performance was based on the European standard EN50242, which considers visible water drops left on the dishware after a completed dishwashing cycle. The results showed that this new closed drying method was more energy efficient compared to an existing open drying method, and that the drying start temperature and the drying time had a significant effect on the drying performance. Its lower electricity consumption and the fact that it does not vent humid air into the kitchen gives this heat pump dishwasher a competitive advantage over dishwashers using an open drying method.

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    Bengtsson_Berghel_2017
  • 6.
    Bengtsson, Peder
    et al.
    ASKO Appliances AB, Sockerbruksgatan 3, SE-53140 Lidkoping, Sweden.
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Study of using a capillary tube in a heat pump dishwasher with transient heating2016In: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081, Vol. 67, p. 1-9Article in journal (Refereed)
    Abstract [en]

    For competitive purposes, manufacturers of household appliances need to produce appliances that use less electricity. One way of doing this for a dishwasher is to add a heat pump system. Previous studies using R134a as refrigerant have shown that the addition of a heat pump can reduce total electricity consumption by about 24%. This paper reports on the use of a capillary tube in a heat pump dishwasher during the transient heating period. Working with an available compressor, the mass of R600a and the length of a 0.9 mm capillary tube were varied in order to find the configuration with the lowest electricity consumption. Three methods of calculating the length of the capillary tube were used to determine five lengths for evaluation. The results show that using a single capillary tube throughout the transient heating period yields similar electricity consumption to a variable expansion device which occurred by switching the capillary tube between two or three different lengths during the heating period.

  • 7.
    Bengtsson, Peder
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Berghel, Jonas
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    A household dishwasher heated by a heat pump system using an energy storage unit with water as the heat source2015In: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081, Vol. 49, p. 19-27Article in journal (Refereed)
    Abstract [en]

    Electricity usage by a household dishwasher can be reduced by using a heat pump system to heat the dishwasher cabinet, dishware and washing water. The evaporator obtains the energy from an energy storage unit which consists of a container filled with water which freezes to ice. The majority of the heat transfer from the energy storage to the evaporator occurs when ice is created in the energy storage unit. A transient simulation model of a dishwasher with a heat pump system was developed and compared to an experimental setup with good agreement. A simulation study of the compressor cylinder volume and the compressor operating time was performed. The results showed a 24% reduction in total electricity use compared to a dishwasher cycle using a traditional electric element.

  • 8.
    Bengtsson, Peder
    et al.
    ASKO Appliances AB, Lidköping, Sweden.
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Renström, Roger
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Performance Study of a Closed-Type Heat Pump Tumble Dryer Using A Simulation Model and an Experimental Set-Up2014In: Drying Technology, ISSN 0737-3937, E-ISSN 1532-2300, Vol. 32, no 8, p. 891-901Article in journal (Refereed)
    Abstract [en]

    In the interests of competitiveness, manufactures of tumble dryers are seeking to reduce both their electricity use and the drying time. This study examines how the cylinder volume of the compressor and the total heat transfer of the condenser influence the drying time and electricity use in a heat pump tumble dryer. A transient simulation model was developed and compared to an experimental set-up with good similarity. The simulations show that increasing the cylinder volume of the compressor by 50% decreases the drying time by 14% without using more electricity.

  • 9.
    Berghel, Jonas
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Experimental results: Drying Sawdust in a Spouted Bed Dryer2003In: 2nd Nordic Drying Conference / [ed] Eikevik, Trygve M., Alves-Filho, Odilio, Strømmen, Ingvald, Trondheim: SINTEF , 2003, , p. 7Conference paper (Other academic)
  • 10.
    Berghel, Jonas
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Improved Fluidized Bed Drying Technology for Wood Fuels2004Doctoral thesis, monograph (Other academic)
    Abstract [en]

    In this thesis, I discuss experiences from designing, building and evaluating two research plants, which use circulating, atmospheric pressure superheated steam as drying medium for drying sawdust in a fluidized bed.



    The increased use of pellets has created a demand for new drying equipment at the Swedish pellet plants. The underlying cause is that almost all of the available dried material, such as wood shavings, is already in use. The remaining biofuel materials, primarily wet sawdust need drying before entering the pellet process.



    The primary demands on the drying process were an uncomplicated design and efficient energy use. A key aim was to improve the drying technique used in the Swedish wood fuel system with specially interest on the control system.



    Sawdust has been tested in both a full scale and a laboratory scale dryers. The tests were done in a spouted bed. The product of the steam mass flow and the enthalpy difference limits the drying capacity. The tests showed that it is possible to use the temperature after the dryer as a control parameter for the outgoing moisture content in a spouted bed dryer. The results and conclusions can be very useful when designing a similar full scale drying system.

  • 11.
    Berghel, Jonas
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Increased Capacity in an Existing Spouted Dryer Using a Heating Tube2008Conference paper (Refereed)
  • 12.
    Berghel, Jonas
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    The Effect of Using a Heating Tube in an Existing Spouted Bed Superheated Steam Dryer2011In: Drying Technology, ISSN 0737-3937, E-ISSN 1532-2300, Vol. 29, no 2, p. 183-188Article in journal (Refereed)
  • 13.
    Berghel, Jonas
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    The gas to Particle Heat Transfer and Hydrodynamics in Spouted Bed Drying of Sawdust2005In: Drying Tecnology, Vol. Vol.23(5)Article in journal (Refereed)
  • 14.
    Berghel, Jonas
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    The Heat Transfer Coefficients Dependency on Spouted Bed Heights, Material Flow and Mean Residence Time2002Conference paper (Refereed)
  • 15.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Beiron, Jens
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Olin, Malin
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Individuell Examination i en Projektbaserad Kurs2000Conference paper (Other (popular science, discussion, etc.))
  • 16.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Brunzell, L.
    Bengtsson, P.
    Performance Analysis of a Tumble Dryer2004Conference paper (Refereed)
  • 17.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Eriksson, Bengt
    Biobränsletorkning: - torkning av rörflen1996Report (Other academic)
  • 18.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Frodeson, Stefan
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Granström, Karin
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Ståhl, Magnus
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Kartläggning och nulägesbeskrivning av pelletskedjan2011Report (Other academic)
  • 19.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Frodeson, Stefan
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Granström, Karin
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Ståhl, Magnus
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Lösningarna finns! Är pelletsproducenterna medvetna om problemen?2011In: Bioenergi: utmaningar och möjligheter / [ed] Delin, Karin, Persson, Lars, Wikström, Per-Arne, Gävle: Region Gävleborg , 2011, p. 25-29Chapter in book (Other academic)
    Abstract [sv]

    Sverige är inte längre världsledande som pelletsproducent. USA producerar allra mest pellets i världen. Kanada och Ryssland producerar också allt mer pellets. Ingen av dessa länder har någon omfattande inhemsk konsumtion. I stort sett all pellets exporteras och det sker huvudsakligen till Europa. Sannolikt kommer det att leda till att priset på pellets i Europa sjunker, med följd att lönsamheten för svenska pelletsproducenter minskar.

  • 20.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Frodeson, Stefan
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Granström, Karin
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Ståhl, Magnus
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Varför får inte villaägaren driva kvalitetsutvecklingen på bränslepellets?2011In: Bioenergi: utmaningar och möjligheter / [ed] K. Delin, L. Persson, P.-A. Wikström, Gävle: Region Gävleborg , 2011, p. 31-33Chapter in book (Other academic)
  • 21.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Frodeson, Stefan
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Granström, Karin
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Ståhl, Magnus
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Nordgren, Daniel
    Innventia, Box 5604, SE-11486 Stockholm, Sweden.
    Tomani, Per
    Innventia, Box 5604, SE-11486 Stockholm, Sweden.
    The effects of kraft lignin additives on wood fuel pellet quality, energy use and shelf life2013In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 112, no 0, p. 64-69Article in journal (Refereed)
    Abstract [en]

    In 2011, the total consumption of pellets in Sweden amounted to 1.9 million tons, which represents an energy value of 9 TWh. The pellets are used in large-scale as well as in small-scale applications, and increased demands on pellet quality are likely to force pellet producers to improve on the pellet properties. One way of increasing pellet quality is by using additives. The purpose of this article, therefore, is to examine kraft lignin as an additive. Pelletswere produced in a small industrial pellet press located at KarlstadUniversity, Karlstad, Sweden, and 1–4% of kraft lignin was added to the pellets. The results indicate that the addition of an increased amount of kraft lignin to the pellets increases their mechanical durability and their lengths. The results also indicate that dry kraft lignin yields pellets with higher durability as compared to wet kraft lignin. The energy demand was unaffected by the increased use of kraft lignin. The general results presented in this paper are useful for producers of lignin, pellet producers and end-users of pellets, who are interested in developing their products and/or improving the production processes.

  • 22.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Frodesson, Stefan
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Granström, Karin
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Ståhl, Magnus
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Tillsatser som kvalitetshöjare för pellets2011Report (Other academic)
  • 23.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Granström, Karin
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Ståhl, Magnus
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    From sawdust to pellets. Still a challenge...2012In: Public Service Review European Union, no 33, p. 398-399Article in journal (Other academic)
    Download full text (pdf)
    fulltext
  • 24.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Nilsson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Particle mixing and residence time when drying sawdust in a continuous spouted bed2008In: Chemical Engineering and Processing, ISSN 0255-2701, E-ISSN 1873-3204, Vol. 47, no 8, p. 1252-1257Article in journal (Refereed)
  • 25.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Renström, Roger
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    An Experimental Study on the Influence of Using a Draft Tube in a Continuous Spouted Bed Dryer2014In: Drying Technology, ISSN 0737-3937, E-ISSN 1532-2300, Vol. 32, no 5, p. 519-527Article in journal (Refereed)
    Abstract [en]

    Further increasing the production of processed biofuel also increases the demands on drying capacity. With the aim of increasing the heat capacity flow, experimental tests have been performed on the process of drying sawdust in a continuous spouted bed dryer with nine different draft tube designs. The results showed that a draft tube with an increased length and an increased disengagement height decreased the dry substances' flow rate throughout the dryer. The results also showed that the mass of the material in the dryer was approximately the same in all the tests. This means that the draft tubes, no matter their size, do not influence the amount of material in the dryer.

  • 26.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Analysis of Superheated Steam Drying of Sawdust in Spouted Bed From Design Perspective2010Conference paper (Refereed)
  • 27.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Basic design criteria and corresponding results performance of a pilot-scale fluidized superheated atmospheric condition steam dryer2002In: Biomass and Bioenergy, Vol. Vol.23(2), p. 103-112Article in journal (Refereed)
  • 28.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Controllability of Product Moisture Content when Non-Screened Sawdust is Dried in a Spouted Bed2004In: Drying Tecnology, Vol. Vol.22(3)Article in journal (Refereed)
  • 29.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Design Criteria, Key Parameters and Performance Results of a Fluidized Bed1999Licentiate thesis, monograph (Other academic)
  • 30.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Effects of Using Draft Tubes in a Continued Spouted Bed Dryer2012Conference paper (Refereed)
  • 31.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Shi yong dao liu guan dui lian xu pen dong gan zao qi de ying xiang: (Effects of using draft tubes in a continued spouted bed)2013In: Drying Technology & Equipment, ISSN 1727-3080, Vol. 1727-3080, no 3, p. 9-18Article in journal (Refereed)
  • 32.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Superheated steam drying of sawdust in continuous feed spouted beds: a design perspective2014In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 71, no 0, p. 228-234Article in journal (Refereed)
    Abstract [en]

    Spouted bed drying technology shows promising results for the drying of unscreened sawdust in superheated steam. In this paper, the experiences from designing, running and evaluating two spouted bed continuous feed dryers are presented. Stable running conditions and drying results have been achieved. This has been particularly important for sawdust that will be compressed into pellets or briquettes. The spouted bed superheated steam dryer also shows high potential for energy efficient integration into sawmills. Our recommendation is thus, to use the outlet steam temperature as the control parameter for the outlet moisture content. A drying rate above and one below the fibre saturation level, can be identified. Visual observations through the viewing glass in the drying zone in both the dryers clearly showed that not all of the material participated in the spout at all times; there were, however, no indications of dead zones. A heat transfer analysis indicated that only about 70% of the surface area of the material was in thermal contact with the steam. This paper sums up the experiences regarding drying properties, control and system properties obtained when sawdust is dried using superheated steam as the drying medium. Further work on standardised dryers in series or in parallel is necessary to increase the capacity in the spouted bed dryer.

  • 33.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Technical presentation of a 200kW Superheated Steam Dryer1998Conference paper (Other (popular science, discussion, etc.))
  • 34.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Temperature Measurement as Indicators of the Quality of the Spouting Bed when Non-screened Sawdust is Dried2004Conference paper (Other (popular science, discussion, etc.))
  • 35.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    The Use of Temperature after The Spouting Bed as a Control Parameter of Outgoing Moisture Content When Sawdust is Dried2002Conference paper (Refereed)
  • 36.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Usefulness and significance of energy and mass balances of a superheated steam dryer2001In: Drying Tecnology, Vol. Vol.19(6), p. 1083-1098Article in journal (Refereed)
  • 37.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Kullendorff,, Anders
    Biobränslen: - utvärdering av fluidiserad ångtorkprojektet fluidtork1997Report (Other academic)
  • 38.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Kullendorff, Anders
    Biobränsletorkning - en lägesrapport projektet Fluidtork1996Report (Other academic)
  • 39.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Kullendorff,, Anders
    Biobränsletorkning: - en lägesrapport projektet fluidtork1996Report (Other academic)
  • 40.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Stawreberg, Lena
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Integrating tumble dryer in the heating systems in block of flats2009Conference paper (Other (popular science, discussion, etc.))
  • 41.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Stawreberg, Lena
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Utveckling av energieffektivare kondenstumlare för en- och flerfamiljshus2008Report (Other academic)
  • 42.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Ståhl, Magnus
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    How residence time in the mixing conditioner affects the quality in wood fuel pellets2016Conference paper (Other academic)
  • 43.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Ståhl, Magnus
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Frodeson, Stefan
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    The amount of dust and rejects as well as the electricity consumption during production decreases with the use of adequate additives2017Conference paper (Other academic)
  • 44.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Ståhl, Magnus
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Frodeson, Stefan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Pichler, Wilfried
    Holzforschung Austria, AUS.
    Weigl-Kuska, Martin
    Holzforschung Austria, AUS.
    A comparison of relevant data and results from single pellet press research is Mission Impossible: A review2022In: Bioresource Technology Reports, ISSN 2589-014X, Vol. 18, article id 101054Article in journal (Refereed)
    Abstract [en]

    A global increase in the wood fuel pellet market requires knowledge of new biomasses pelleting abilities. As large-scale industrial tests of new materials are costly, tests in e.g., a single pellet press (SPP) are desirable. SPPs have many different configurations and it typically produces one pellet at a time and can give results of its pelletability. This review has surveyed the research that has been carried out of SPPs to ascertain the feasibility of comparing their obtained data and the results. The results show that it is almost impossible to compare the data and results of the various different SPP studies, e.g., some information from the data used was missing, resulting in that only 27 out of 70 papers were comparable. One solution could be the introduction of a common SPP testing method using a determined set of data that enables a reference pellet to be produced in every study.

    Download full text (pdf)
    fulltext
  • 45.
    Frodeson, Stefan
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Anukam, Anthony
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Ståhl, Magnus
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Kudahettige-Nilsson, Rasika Lasanthi
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Henriksson, Gunnar
    KTH.
    Aladejana, Elizabeth Bosede
    The University of Fort Hare, ZAF.
    Densification of Wood-Influence on Mechanical and Chemical Properties when 11 Naturally Occurring Substances in Wood Are Mixed with Beech and Pine2021In: Energies, E-ISSN 1996-1073, Vol. 14, no 18, article id 5895Article in journal (Refereed)
    Abstract [en]

    The need to increase the use of renewable biomasses for energy supply, such as fuel pellets is significant. However, different types of biomasses have different mechanical properties to be pelletized, which entails a limitation in available raw materials for pellet producers. Within this study eleven different pure substances from biomasses were separately mixed with European beech and Scots pine, to identify its impact on the densification process. Beech and pine pellets were used as control materials against their corresponding pellets mixed with substances representing: cellulose, hemicelluloses, other polysaccharides, lignin, protein, and extractives. The mechanical properties were investigated as well as FT-IR and SEM analyses on the pellets. The results showed that the addition of the substances xylan and galactan created the hardest pellets for both pine and beech and that adding extractives to wood affects pine more than beech in relation to hardness. The FT-IR data could not provide clear explanations as to the variation in hardness and springback behavior through the identification of major functional groups in each pellet. It can be concluded that biomass residues rich in xylan and galactan increase pellet quality in terms of strength and durability without affecting the production process.

  • 46.
    Frodeson, Stefan
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Berghel, Jonas
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Study of Drying Processes and Air Flow Distribution in a Drying Cabinet Using an Infrared Camera2009In: Proceedings of the 4th Nordic Drying Conference NDC2009 / [ed] Trygve M. Eikevik, Odilio Alves-Filho, Trondheim: Norwegian University of Science and Technology, SINTEF , 2009Conference paper (Refereed)
  • 47.
    Frodeson, Stefan
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Renström, Roger
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Pneumatic dryer as a second step in a two step drying technique2013In: Sixth Nordic Drying Conference NDC 2013, 2013Conference paper (Refereed)
  • 48.
    Frodeson, Stefan
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Berghel, Jonas
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    The potential in using two step drying techniques for improving energy efficiency and increasing the drying capacity in fuel pellet industries2012In: Drying Technology, ISSN 0737-3937, E-ISSN 1532-2300, Vol. 31, no 15Article in journal (Other academic)
  • 49.
    Frodeson, Stefan
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Renström, Roger
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    The Potential of Using Two-Step Drying Techniques for Improving Energy Efficiency and Increasing Drying Capacity in Fuel Pellet Industries2013In: Drying Technology, ISSN 0737-3937, E-ISSN 1532-2300, Vol. 31, no 15, p. 1863-1870Article in journal (Refereed)
    Abstract [en]

    The use of wood fuel pellets has increased worldwide in recent years, and pellet producers conclude that the lack of drying capacity is a barrier to increased production. In this study, we develop a concept of two different dryers called the two-step drying technique. The aim is to show the potential for increasing the drying capacity and improving energy efficiency when introducing a second dryer into the pellet plant. The study is theoretical and based on an industrial packed moving bed dryer. It shows that the drying capacity increased by 22% when a pneumatic second dryer was used.

  • 50.
    Frodeson, Stefan
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Ståhl, Magnus
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Granström, Karin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Romlin, Carl
    Drinor AB, Karlstad.
    Thelander, Alexander
    Drinor AB, Karlstad,.
    The Potential for a Pellet Plant to Become a Biorefinery2019In: Processes, ISSN 2227-9717, Vol. 7, no 4, p. 1-11, article id 233Article in journal (Refereed)
    Abstract [en]

    The use of bioenergy has increased globally in recent years, as has the utilization of biomaterials for various new product solutions through various biorefinery concepts. In this study, we introduce the concept of using a mechanical dewatering press in combination with thermal drying in a pellet plant. The purpose of the study is to increase the understanding of the effects a mechanical dewatering press has in a pellet production chain and investigate whether a pellet plant could thus become a biorefinery. The evaluations in this study are based on industrial data and initial tests at the university. The results show that the concept of using the mechanical dewatering press together with a packed moving bed dryer reduces energy use by 50%, compared to using only a packed moving bed dryer. The press water could be used as a raw material for biogas, bioplastics, and biohydrogen. Hence, this study points out the possibilities of a pellet plant increasing the efficiency of the drying step, while moving towards becoming a biorefinery.

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    fulltext
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