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  • 51.
    Henriksson, Lisa
    et al.
    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).
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Andersson, Simon
    Emerging Cooking Solutions Sweden AB.
    Ohlson, Mattias
    Emerging Cooking Solutions Sweden AB.
    Bioresources for Sustainable Pellet Production in Zambia: Twelve Biomasses Pelletized at Different Moisture Content2019In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 14, no 2, p. 2550-2575Article in journal (Refereed)
    Abstract [en]

    The use of charcoal and firewood for cooking is common in Zambia,and its utilization is suchthat the deforestation rate is high, energy utilization is low, and unfavorable cooking methods lead to high death rates due to indoor air pollution mainly from particulate matter and carbon monoxide.Byusing an alternative cooking method, such as pellet stoves, it is possible to offer a sustainable solution, provided that sustainable pelletproduction can be achieved. In this study, 12different available biomaterials were pelletizedina single pellet unitto investigate their availability as raw materials for pellet production in Zambia. The study showedthat sicklebush and pigeon pea generatedthe same pelleting properties correlated withcompression and frictionand that both materials showedlow moisture uptake. The study also identifiedtwo groups of materials that broadenedthe raw material base and helpedto achieve sustainable pellet production.Group 1consisted of materials with equal pelletingabilities (miombo, peanut shell, pigeon pea,and sicklebush) andGroup 2 consistedof materialsthat showed low impact of varying moisture content(eucalyptus, miombo, peanut shell, pigeon pea, and sicklebush). The hardest pellet was made from Tephrosia, which wasfollowed by Gliricidia.

  • 52. Jansson, C.
    et al.
    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.
    Interdisciplinary Basic Course in Engineering Teamwork2002Conference paper (Refereed)
  • 53.
    Mattsson, Lisa
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Williams, Helén
    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.
    Waste of fresh fruit and vegetables at retailers in Sweden: Measuring and calculation of mass, economic cost and climate impact2018In: Resources, Conservation and Recycling, ISSN 0921-3449, E-ISSN 1879-0658, Vol. 130, p. 118-126Article in journal (Refereed)
    Abstract [en]

    Food waste is a significant problem for environmental, economic and food security reasons. The retailer, food service and consumers have been recognised as the parts of the food supply chain where the possibility of reducing food waste is greatest in industrialised countries. In this study, primary data on fresh fruit and vegetables (FFV) waste collected through direct measurements in three large retail stores in Sweden were analysed from the perspectives of wasted mass, economic cost and climate impact. A method of measuring and calculating the economic cost of FFV waste was developed and includes the cost of wasted produce, the cost of personnel time for waste management and the cost of waste collection and disposal. The results show that seven FFV categories, which have been termed "hotspot categories", contributed to the majority of the waste, both in terms of wasted mass, economic cost and climate impact. The "hotspot categories" are apple, banana, grape, lettuce, pear, sweet pepper, and tomato. The cost benefit analysis conducted showed that it is economically wise to invest in more working time for employees in waste management to accomplish a reduction of wasted mass and climate impact without an economic loss for the store. These results are relevant for supporting the implementation of policies and initiatives aimed at food waste reduction at retail level.

  • 54.
    Ottosson, Anders
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Nilsson, Lars
    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).
    A mathematical model of heat and mass transfer in Yankee drying of tissue2017In: Drying Technology, ISSN 0737-3937, E-ISSN 1532-2300, Vol. 35, no 3, p. 323-334Article in journal (Refereed)
    Abstract [en]

    Final dewatering in the production of dry creped tissue is performed by Yankee drying, which includes hot pressing followed by simultaneous contact and impingement drying. The present study models Yankee drying and compares simulation results to the data obtained from trials on a pilot tissue machine. It advances models published previously by the representations developed for the transport of heat in the pressing stage and for the heat transfer involved in the dehydration of the cylinder coating spray. The model predicts an average specific drying rate within 4% in the range of the experimental data used.

  • 55. Ottosson, Anders
    et al.
    Nilsson, Lars
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013). Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Berghel, Jonas
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Analogies between heat and mass transfer for estimation of air humidity2013In: Sixth Nordic Drying Conference NDC 2013, Copenhagen, Denmark, 2013Conference paper (Refereed)
  • 56. Persson, T.
    et al.
    Berghel, Jonas
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    How Inlet Moisture Content and Outlet Temperature Controls Outlet Moisture Content in a Spouted Bed Dryer2005Conference paper (Other (popular science, discussion, etc.))
  • 57.
    Persson, Tomas
    et al.
    Dalarna University.
    Riedel, Jochen
    Dalarna University.
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Becksell, Ulf
    Dalarna University.
    Win, Kaung Myat
    Dalarna University.
    Deposit formation in a small-scale wood pellet boiler using pellet with additives2013In: Journal of Fuel Chemistry and Technology, ISSN 1872-5813, Vol. 41, no 5, p. 530-539Article in journal (Refereed)
    Abstract [en]

    This work studies the amount of gaseous and particle emissions and deposits on heat exchanger surfaces in a boiler fired with commercially available pellets and with pellets primed with magnesium oxide and magnesium hydroxide. The combustion experiments were performed on a residential boiler of 20 kW. Substrates placed in the heat exchanger was analysed with SEM-EDX-mapping to evaluate the chemical composition of the deposits. The results show that particle emissions (PM 2.5) using the additives increased by about 50% and the mass of the deposits in the flue gas heat exchanger (excluding loose fly ash) increased by about 25% compared to the combustion of pellets without additives. The amount of additives was found to be eight times higher than the amount of the main alkali metals potassium (K) and sodium (Na) which leads to the assumption that the additives were overdosed and therefore caused the problems reported. The SEM analysis of the substrates placed in the flue gas heat exchanger indicate that the deposits of sodium (Na), potassium (K), chlorine (Cl) and sulphur (S) decrease using the additives. If this was due to the expected chemical reactions or due to the loose fly ash covering the substrates after the test, could not be determined in this study.

  • 58.
    Persson, Tomas
    et al.
    School of Technology and Business Studies, Dalarna University.
    Riedel, Jochen
    School of Technology and Business Studies, Dalarna University.
    Berghel, Jonas
    Becksell, Ulf
    School of Technology and Business Studies, Dalarna University.
    Win, Kaung Myat
    School of Technology and Business Studies, Dalarna University.
    Emissions and deposit properties from combustion of wood pellet with magnesium additives2013In: Journal of Fuel Chemistry and Technology, ISSN 1872-5813, Vol. 41, no 5, p. 530-539Article in journal (Refereed)
    Abstract [en]

    This work studies the amount of gaseous and particle emissions and deposits on heat exchanger surfaces in a boiler fired with commercially available pellets and with pellets primed with magnesium oxide and magnesium hydroxide. The combustion experiments were performed on a residential boiler of 20 kW. Substrates placed in the heat exchanger was analysed with SEM-EDX-mapping to evaluate the chemical composition of the deposits. The results show that particle emissions (PM 2.5) using the additives increased by about 50% and the mass of the deposits in the flue gas heat exchanger (excluding loose fly ash) increased by about 25% compared to the combustion of pellets without additives. The amount of additives was found to be eight times higher than the amount of the main alkali metals potassium (K) and sodium (Na) which leads to the assumption that the additives were overdosed and therefore caused the problems reported. The SEM analysis of the substrates placed in the flue gas heat exchanger indicate that the deposits of sodium (Na), potassium (K), chlorine (Cl) and sulphur (S) decrease using the additives. If this was due to the expected chemical reactions or due to the loose fly ash covering the substrates after the test, could not be determined in this study.

  • 59.
    Renström, Roger
    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.
    Concrete Results of the Cooperation on Drying Issues Between ASKO Applications AB and Karlstad University2009Conference paper (Other academic)
  • 60.
    Renström, Roger
    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.
    Drying of sawdust in an atmospheric pressure spouted bed steam dryer2002In: Drying Tecnology, Vol. Vol.20(2)Article in journal (Refereed)
  • 61.
    Renström, Roger
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Experimental results from drying sawdust below the fiber saturation point using a vertical pneumatic dryer2014In: IDS 2014, The 19th International Drying Symposium, Lyon, France, 2014Conference paper (Refereed)
  • 62.
    Renström, Roger
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Frodeson, Stefan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Granström, Karin
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Nilsson, Lars
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences. Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Lestelius, Magnus
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering. Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences, Paper Surface Centre. Karlstad University, Faculty of Technology and Science, Materials Science.
    Moons, Ellen
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Stawreberg, Lena
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    The drying process from a product perspective2013Conference paper (Refereed)
  • 63.
    Renström, Roger
    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).
    Experimental data from a spouted bed dryer as a basis for design of a two stage dryer2011In: Proceedings of the 5th Nordic Drying Conference, NDC / [ed] Alves-Filho, O., Eikevik, T.M. & Goncharova-Alves, S., 2011Conference paper (Refereed)
  • 64.
    Rezk, Kamal
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Forsberg, Jan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Nilsson, Lars
    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).
    Characterizing flow resistance in 3-dimensional disordered fibrous structures based on Forchheimer coefficients for a wide range of Reynolds numbers2016In: Applied Mathematical Modelling, ISSN 0307-904X, E-ISSN 1872-8480, Vol. 40, no 21-22, p. 8898-8911Article in journal (Refereed)
    Abstract [en]

    The flow resistance in 3-dimensional fibrous structures are investigated in particle Reynolds number representing flow characteristics with strong inertia. The resistance coefficients are established based on steady state simulations of single-phase processes of water numerically. An automatized simulation process in COMSOL is developed with a MATLAB algorithm in which production runs could be carried for various 3-dimensional fibrous structures. Simulation of flow processes ranging from Reynolds numbers at creeping flow levels to high Reynolds number at approximately 1000 are calculated and a numerical data set is established in order to estimate Forchheimer coefficients which are used to correlate a dimensionless friction factor to a modified Reynolds expression for porous media.

    The friction factor and dimensionless permeability are calculated for fibrous structures with (i) disordered unidirectional fibers (ii) an isotropic fiber orientation in-plane perpendicular to the flow, and (iii) an isotropic fiber structure in a the 3-dimensional space. Empirical correlations of the friction factor and Reynolds number are used to compare our simulation data in order to assess the validity of our models and flow resistance estimations. The dimensionless permeability is moreover compared to other numerical simulations of flow through fibrous structures in order to assess flow resistance at low Reynolds number.

    It is concluded that flow resistance in the isotropic fiber arrangement in space is lower than the in-plane isotropic orientation and disordered unidirectional fiber arrangements at creeping flow conditions, however, all friction actors converges towards the same value at higher Reynolds numbers indicating that fiber orientation is independent at high inertia flow regimes. Overall, our numerical simulations agree well to classical empirical formulations for a wide range of Reynolds number. However, the comparison differs considerably depending on the porosity level.

  • 65.
    Rezk, Kamal
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Forsberg, Jan
    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. Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering.
    Berghel, Jonas
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Using a Level-Set Model to Estimate Dwell Time in a Vacuum Dewatering Process for Paper,2012Conference paper (Refereed)
  • 66.
    Rezk, Kamal
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Nilsson, Lars
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences. Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Forsberg, Jan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Modelling of water removal during a paper vacuum dewatering process using a Level-Set method2013In: Chemical Engineering Science, ISSN 0009-2509, E-ISSN 1873-4405, Vol. 101, p. 543-553Article in journal (Refereed)
    Abstract [en]

    Water removal in paper manufacturing is an energy-intensive process. The dewatering process generally consists of four stages of which the first three stages include mechanical water removal through gravity filtration, vacuum dewatering and wet pressing. In the fourth stage, water is removed thermally, which is the most expensive stage in terms of energy use.

    In order to analyse water removal during a vacuum dewatering process, a numerical model was created by using a Level-Set method. Various different 2D structures of the paper model were created in MATLAB code with randomly positioned circular fibres with identical orientation. The model considers the influence of the forming fabric which supports the paper sheet during the dewatering process, by using volume forces to represent flow resistance in the momentum equation.

    The models were used to estimate the dry content of the porous structure for various dwell times. The relation between dry content and dwell time was compared to laboratory data for paper sheets with basis weights of 20 and 50 g/m2 exposed to vacuum levels between 20 kPa and 60 kPa. The comparison showed reasonable results for dewatering and air flow rates. The random positioning of the fibres influences the dewatering rate slightly. In order to achieve more accurate comparisons, the random orientation of the fibres needs to be considered, as well as the deformation and displacement of the fibres during the dewatering process.

  • 67.
    Rezk, Kamal
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Nilsson, Lars
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013). Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Forsberg, Jan
    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).
    Simulation of water removal in paper based on a 2D Level-Set model coupled with volume forces representing fluid resistance in 3D fiber distribution2015In: Drying Technology, ISSN 0737-3937, E-ISSN 1532-2300, Vol. 33, no 5, p. 605-615Article in journal (Refereed)
    Abstract [en]

    A numerical model of a vacuum dewatering process was established with a Level-Set method to simulate two-phase flow in a 2-dimensional paper sheet model with constructed volume forces representing flow resistance in a 3-dimensional environment. Nine cases of various volume force representations were compared to numerical and experimental data. Based on the dry content and dwell time relation, the case with the influence of the paper/wire interface showed the most pleasing result compared to experimental data. Compared to the other numerical cases, considering the blockage of the pore space at the top layer of the forming fabric plays an essential role in determining the flow resistance during the vacuum process. Also, the dynamics of the dewatering rate is captured well with the influence of the blockage of fibers on the top layer of the forming fabric. The peak of the dewatering rate could be investigated further with a higher frequency of sample points on new experimental data.

    The computational time for the two-phase flow models in this study is extensively reduced due to the removal of the internal structure. This distinction enables time efficient simulations of vacuum dewatering process in which several dewatering parameters such as level of vacuum, influence of moving vacuum pulse and higher basis weights could be investigated.

  • 68.
    Sandberg, Maria
    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.
    Berghel, Jonas
    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.
    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.
    Miljöaspekter på produktion och lagring av träpellets2011Report (Other academic)
  • 69.
    Stahl, Magnus
    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.
    Granstrom, Karin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Improvement of Wood Fuel Pellet Quality Using Sustainable Sugar Additives2016In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 11, no 2, p. 3373-3383Article in journal (Refereed)
    Abstract [en]

    The global production and use of wood fuel pellets has increased significantly in recent years. The raw material and the energy required to dry it are the main production costs. Therefore, it is crucial to minimize energy consumption, production costs, and the environmental impact associated with wood pellets. However, these changes should not negatively affect the quality of the pellets. One way to achieve these goals is to use additives. This work investigates how different types of sugar additives affect both the energy needed by the pellet press and the durability and oxidation of the produced pellets. When sugar was used as an additive, the energy use was practically unaffected. When molasses and SSL were added, a small decrease in energy use was observed (6 to 8%) for admixtures up to 1 wt.%; however, when more molasses was added, the energy use increased. Using these additives increased the bulk density (7 to 15 %) and durability (10 to 20 %) of the pellets. The storage of the pellets also caused a small increase in durability (1 to 3 %). Volatile organic compounds were produced as oxidation peaks within the first two months of storage; thereafter, the peaks tapered off.

  • 70.
    Stawreberg, Lena
    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.
    Energy Losses by Air Leakage in Condensing Tumble Dryers2012In: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 37, no May, p. 373-379Article in journal (Refereed)
    Abstract [en]

    Tumble dryers, used for the drying of textiles, consume a considerable amount of electricity due to the large number of dryers in use. A large amount of this electricity is produced from coal, making it important to reduce the electricity use and, hence, the carbon dioxide emissions. Earlier studies made on the condensing tumble dryer have pointed out that leakage is one of the parameters affecting the electricity use for the drying process. With a view to reducing the energy use, leakage was estimated through measurements and modelling. Energy balances were used in order to verify the leakage. The energy balance showed good agreement with the results from the model and confirms that the leakage out from the dryer arises mainly between the heater and the drum where the air is hot and has low relative humidity. Large leakage at this location is detrimental for the energy efficiency of the dryer, meaning that the leakage must be reduced in order to obtain a reduced energy use. Results from the model also point out that even small changes in the size of gaps, or changes to the pressure in the internal system, result in a significant change in leakage from the dryer

  • 71.
    Ståhl, Magnus
    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.
    Energy Efficient Pilot-Scale Production of Wood Fuel Pellets made from a Raw Material Mix Including Sawdust and Rapeseed Cake2011In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 35, no 12, p. 4849-4854Article in journal (Refereed)
    Abstract [en]

    Presently, most fuel pellets are made from sawdust or shavings. In Sweden, these materials are used to the maximum extent. As the demand for pellets increases, the supply of sawdust will be insufficient and other raw materials or mixes of raw materials will be used. This work investigates sawdust mixed with rapeseed cake. The latter is a residual product from the production of chemically unmodified oil refined from cold-pressed rape oil. At the Department of Energy, Environmental and Building Technology at Karlstad University, Sweden, a complete pilot-scale pellet production unit is located. The pellets are produced and tested for mechanical durability, length, bulk density and moisture content according to the Swedish Standard for pellets. During production, the load current, the die pressure and the die temperature were measured along with other parameters. The main purpose was to examine how the mixture of rapeseed cake and pine sawdust affected the energy consumption of the pelletising machine and mechanical durability of mixed fuel pellets. The results show that the energy consumption decreased and the amount of fines increased with increasing rapeseed cake in the wood fuel pellets. These results indicate that we must compromise between a decrease in the use of energy and a decrease in durability.

  • 72.
    Ståhl, Magnus
    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.
    Validation of a Developed Mathematical Model by Studying the Effects of Recirculation of Drying Gases2008In: Drying TechnologyArticle in journal (Refereed)
  • 73.
    Ståhl, Magnus
    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.
    Validation of a Developed Mathematical Model Studying the Effects of Recirculation of Drying Gases2006Conference paper (Refereed)
    Abstract [en]

    Drying is a costly and energy consuming process. Consequently, it is of great practical importance to improve its energy efficiency. Our objective, therefore, is to develop and validate a theoretical drying model by studying the recirculation of drying gases. The results show that the amount of recovered energy over the condenser and the dryer efficiency increase with increased recirculation, implying an energy efficient operation. The validation shows that the model correlates well with industrial data. Accordingly, it should be possible to use the model industrially to predict capacity changes and energy recovered when changes in drying gas recirculation are made

  • 74.
    Ståhl, Magnus
    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.
    Validation of a Mathematical Model by Studying the Effects of Recirculation of Drying Gases2008In: Drying Technology, ISSN 0737-3937, E-ISSN 1532-2300, Vol. 26, no 6, p. 786-792Article in journal (Refereed)
  • 75.
    Ståhl, Magnus
    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).
    Additives for wood fuel pellet production - A win, win, win situation2016Conference paper (Other academic)
    Abstract [en]

    The production and use of wood-fuel pellets, preferably made from sawdust or shavings, have increased significantly worldwide in recent years. If wood-fuel pellets should continue to be a successful biofuel at the energy market there are several factors to take into consideration. The pellet production industry already tries to reduce the production cost, since it is a low margin business. Further, it tries to produce pellets from a broader raw material base and at the same time satisfy the customer requirements while producing a sustainable product. The wood fuel pellet industry has the possibility to meet all these criteria; however, it also has the potential for improvements.

    This work focuses on energy efficiency, technical aspects and environmental factors, i.e., the electricity consumption, the physical and mechanical properties of the pellets, and the CO

    2 equivalent emitted during production, respectively. 20 various additives, with an admixture of up to 2 % (wt.), have been tested during wood fuel pellet production at Karlstad University. This work presents the benefits of using different additives in pellet production and the cost associated with different additives. The results shows that additive from the sea and from farmlands (algae, rape seed cake and grass) decrease the energy use in the pellet press but unfortunately also decrease the durability. Additives from wood (resins, lignin) and molasses increases the durability of the pellet but shows almost no or little change in electricity consumption. However, using starch grades, white sugar or spent sulphite liquor as an additive increases the mechanical properties while it decreases both the electricity consumption and the climate impact, hence a win-win-win situation. To justify the use of additives from a climate impact perspective in regions with an OECD European electricity mix or the Swedish electricity mix, the usage of additives from the rest products where the CO2 equivalent emissions are allocated to the main product are crucial.

    In conclusion, it is necessary to do research that systematically investigates the consequences of using additives for wood fuel pellets to continuously be a successful biofuel at the energy market

  • 76.
    Ståhl, Magnus
    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).
    Research Experience From The Use Of Different Additives In Wood-Fuel Pellet Production2017In: International Journal of Energy Production and Management, ISSN 2056-3272, E-ISSN 2056-3280, Vol. 2, no 3, p. 288-293Article in journal (Refereed)
    Abstract [en]

    The use of wood-fuel pellets has increased signi cantly worldwide in recent years, especially in the United Kingdom. If wood-fuel pellets should continue to be a successful biofuel at the energy market, the pellet production industry has to reduce the production cost, since it is a low-margin business. Further, improved pellets regarding storability and strength of the pellets are crucial to manage the overseas transportation that causes material losses. In addition, the industry tries to produce pellets from a broader raw material base and at the same time satisfy the customer requirements while produc- ing a sustainable product. The wood-fuel pellet industry has the possibility to meet all these criteria; however, it also has the potential for improvements. Using additives in pellet production is one way to meet the criteria. In conclusion, it is necessary to do the research that systematically investigates the consequences of using additives for wood-fuel pellets, and this work presents a compilation of results and experiences from more than 20 different additive studies and the test bed for pellet produc- tion research at Karlstad University– a pellet production unit adapted for additives studies. Additives, with an admixture of up to 2% (wt.), have been tested in the NewDeP (New Development for Pellet Technology) pilot plant for pellet production at Karlstad University. The research has focused on the electricity consumption, the physical and mechanical properties of the pellets, and the CO2 equivalents emitted during production. The results showed that the additives Wetland grass, Algae, Turpentine and Lignin decreased the electricity consumption in the pellet press but unfortunately also decreased the durability. The additives Resins, Molasses, White sugar, Native potato starch and Oxidized potato starch increased the durability of the pellet but showed almost no change in the electricity consumption. However, Oxidized corn starch, Spent sulphite liquor and Native wheat starch as additives increased the mechanical properties while it decreases both the electricity consumption and the climate impact, hence a Win-Win-Win situation. 

  • 77.
    Ståhl, Magnus
    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.
    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.
    Effects on Pellet Properties and Energy Use When Starch Is Added in the Wood-Fuel Pelletizing Process2012In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 26, no 3, p. 1937-1945Article in journal (Refereed)
    Abstract [en]

    The production and use of wood-fuel pellets have increased significantly worldwide in recent years. The increased use of biomaterials has resulted in higher raw material prices, and there are no signs that indicate a decrease in raw material competition. Additives can be used for different purposes. Partly, they are used to facilitate the use of new raw materials to increase the raw material base, and partly, they are used to decrease the energy use in the pelletizing process. They are also used to increase durability or shelf life. Consequently, it is necessary to do research that systematically investigates the consequences of using additives. In this work, it is investigated how various percentages of different kinds of starch influence pellet properties, including shelf life and energy use in the pelletizing process. Four different starch grades were used: native wheat starch, oxidized corn starch, native potato starch, and oxidized potato starch. The pellets were produced in a small industrial pellet press located at Karlstad University, Karlstad, Sweden. The result shows that starch increases the durability of the pellets. Oxidized starches increase the durability more than native starches, and the best results were obtained by adding oxidized corn starch. The durability did not decrease with storage time when the pellets were stored indoors during 7 months. The oxidation process was not consistently altered by the addition of starch. The energy consumption of the pellet press decreases when starch is added. Again, the oxidized corn starch showed the best result; when 2.8% of corn starch was added, the average energy consumption was reduced by 14%

  • 78.
    Ståhl, Magnus
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Frodeson, Stefan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Energy reduction in wood-fuel pellet production2013In: Forest bioenergy review, ISSN 2045-8614, Vol. 4, no 19, p. 6-Article in journal (Other academic)
  • 79.
    Ståhl, Magnus
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Granström, Karin
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Improvement of Wood Fuel Pellets Quality Using Sustainable Sugar Additives2015In: Proceedings of ECOS 2015 – The 28th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, Pau, France, 2015, p. 1-8Conference paper (Refereed)
  • 80.
    Ståhl, Magnus
    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).
    Williams, Helén
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Energy efficiency, greenhouse gas emissions and durability when using additives in the wood fuel pellet chain2016In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 152, p. 350-355Article in journal (Refereed)
    Abstract [en]

    The use of renewable resources for bioenergy should be performed to support sustainable development. Since the use of bioenergy has increased significantly worldwide in recent years and biomass is made of limited resources it must be used efficiently and with a low environmental impact The wood fuel pellet industry has the possibility to meet these criteria; however, it also has the potential for improvements. This work investigates how the additives, cornstarch and molasses, affect: the electricity consumption of the pellet press, the emission of Carbon dioxide equivalents (CO2 eq.) from the production of wood fuel pellets in three different countries with different emissions from electricity, the durability of the pellets and its effects on energy efficiency. The results show that pellet production is more energy efficient when additives are used, and that the amount of CO2 eq. increases with an increased use of additives. In countries with a low usage of fossil fuels for electricity production, the global warming impact gets higher due to the additives; while in countries that use a lot of fossil fuels to produce electricity, the global warming impact will be reduced because of the additives by up to 1%. The increased global warming impact from the additives can be balanced by the decrease in the reduced amount of rejected material within the production. That is because the durability of the pellets increases with an increasing amount of additive.

  • 81.
    Ståhl, Magnus
    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.
    Williams, Helén
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Sustainable improvements in the wood fuel pellet chain2014In: The Sustainable Energy and Environmental Protection, 2014Conference paper (Refereed)
    Abstract [en]

    A path towards sustainability should include growth with sustainable means such as the concept of Bioeconomy. The use of renewable resources for bioenergy should be performed to support sustainable development; however, biomass is made of limited resources and must be used efficiently and with a low environmental impact. The wood fuel pellet industry has the possibility to meet these criteria, but also has the potential for improvements. Earlier work on wood fuel pellet production has concluded that using oxidised cornstarch as an additive during pellet production decreases the energy used and also produces pellets with high durability. This work presents how additives such as cornstarch and molasses, affect the electricity use of the pellet press and also affect the emission of CO2 eq. from wood fuel pellet production. The results are presented for two different locations of the pellet plant, since the results will depend on how the electricity used is produced, e.g. using more or less renewable or fossil fuels in the electricity mix. 

  • 82.
    Ståhl, Magnus
    et al.
    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).
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Olsson, Stefan
    Stora Enso.
    Using Secondary Pea Starch in Full-Scale Wood Fuel Pellet Production Decreases the Use of Steam Conditioning2019In: World Sustainable Energy Days 2019: European Pellet Conference, 2019Conference paper (Refereed)
  • 83.
    Ståhl, Magnus
    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.
    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.
    Industrial processes for biomass drying and their effects on the quality properties of wood pellets2002Conference paper (Refereed)
  • 84.
    Ståhl, Magnus
    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.
    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.
    Industrial processes for biomass drying and their effects on the quality properties of wood pellets2004In: Biomass and Bioenergy 27:621-628, 2004, Vol. Vol.27, p. 621-628Article in journal (Refereed)
    Abstract [en]

    This paper contributes to the discussion of how different kinds of industrial scale dryers for biomass influence the quality properties of wood pellets. It also discusses how the drying technique can affect the environment. The most common biomass drying processes in use, i.e., convection dryers are discussed. The discussion of drying techniques is based on advantages and disadvantages with a focus on the drying medium,temperature and residence time. The choice of drying technique is particularly important if the end-users choice of pellets is made due to the specific requirements for the heating system used. Some specific parameters were tested in order to investigate how the choice of drying technique affects the pellet quality. The parameters tested were moisture content and the emissions of volatile hydrocarbons. Pellets available on the market were chosen for the tests. The amount of volatile hydrocarbons left in sawdust after drying vary with drying technique, as emissions of terpenes are larger in dryers with long residence times. Low emissions of volatile hydrocarbons would improve the energy content of the sawdust, and by decreasing air pollution improve the work environment and the environment in the surroundings of the dryers

12 51 - 84 of 84
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