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  • 1.
    Dahl, Jan
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hermansson, Roger
    Feasibility study of a heat storage in a district heating system in northern Sweden1994Ingår i: Thermal energy storage: better economy, environment, technology ; proceedings ; August 22 - 25, 1994, Espoo, Finland / CALORSTOCK '94, 6th International Conference on Thermal Energy Storage / [ed] M.T. Kangas, Helsinki: Helsinki University of Technology , 1994, s. 403-410Konferensbidrag (Refereegranskat)
  • 2.
    Dahl, Jan
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hermansson, Roger
    Korttidslagring av hetvatten: förstudie1985Rapport (Övrigt vetenskapligt)
  • 3.
    Dahl, Jan
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hermansson, Roger
    Korttidslagring av värme: mätning och utvärdering av ett el-baserat ackumulatorsystem1988Rapport (Övrigt vetenskapligt)
  • 4.
    Dahl, Jan
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hermansson, Roger
    Phenomena that effect the thermal stratification in water heat storage's1991Ingår i: IEA-Workshop on Thermal Energy Storage and Low Energy Buildings: Tutzing, Germany 18 - 19 June 1991, München: Universität München , 1991Konferensbidrag (Refereegranskat)
  • 5.
    Dahl, Jan
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hermansson, Roger
    Temperatures and velocities in a thermally stratified water heat storage1988Ingår i: Proceedings, 4th International Conference on Energy Storage for Building Heating and Cooling: JIGASTOCK 88 / [ed] J. Despois, French Agency for Energy Control, AFME , 1988, Vol. 1, s. 161-166Konferensbidrag (Refereegranskat)
  • 6.
    Dahl, Jan
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hermansson, Roger
    The establishing of a gradient zone and its effect on the velocity field in a water heat storage1989Ingår i: Proceedings / North Sun '88 - Solar Energy at High Latitudes / [ed] Lars Broman; Mats Rönnelid, Stockholm: Statens råd för byggnadsforskning , 1989Konferensbidrag (Refereegranskat)
  • 7.
    Dahl, Jan
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hermansson, Roger
    Värmeleveranserna till Piteås fjärrvärmenät: resultat av mätningar som genomförts vid Backens hetvattencentral och Assi Kraftliner under 19901992Rapport (Övrigt vetenskapligt)
  • 8.
    Dahl, Jan
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hermansson, Roger
    Gren, Per
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Benckert, Lars
    Temperatures and velocities near the gradient zone in a short term water heat storage1991Ingår i: Proceedings: Thermastock '91, International Conference on Thermal Energy Storage, Scheveningen, 13 - 16 May 1991, Utrecht: Novem , 1991Konferensbidrag (Refereegranskat)
  • 9.
    Dahl, Jan
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hermansson, Roger
    Tiberg, Sven-Erik
    Veber, Pascal
    Luleå tekniska universitet.
    Use of video-based Particle Image Velocimetry technique for studies of velocity fields in a water heat storage vessel1995Ingår i: Experiments in Fluids, ISSN 0723-4864, E-ISSN 1432-1114, Vol. 18, nr 5, s. 383-388Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A video-based Particle Image Velocimetry technique has been developed. The technique is particularly suitable for measurement of small velocities, below 3 cm/s. It has proved to be useful for the documentation of non-stationary velocity fields in a scaled-down model of a water heat storage vessel. An ordinary video camera is used to record the in-plane movements of particles in a light sheet in seeded water. The hardware used, the experimental method and the accuracy of the method are discussed. The use of two commercially available software packages (NIH-Image and IGOR) for the analyses is described. Examples of velocity fields are presented, showing that the measuring technique can be used for studies of mixing near the inlet of the storage vessel and exchange of water between the boundary layer and the core.

  • 10.
    Dahl, Jan
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hermansson, Roger
    Veber, Pascal
    Luleå tekniska universitet.
    Studies of velocity fields in a water heat storage with a video based particle image velocimetry technique1995Ingår i: Energy technologies for a sustainable future: : proceedings of the 30th Intersociety Energy Conversion Engineering Conference, IECEC, July 30 - August 4, 1995, Orlando, Florida / [ed] D. Yogi Goswami, New York: American Society of Mechanical Engineers , 1995Konferensbidrag (Refereegranskat)
  • 11.
    Dahl, Jan
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hermansson, Roger
    Westerlund, Lars
    Egenskaper hos gaser, vätskor och fasta ämnen2001Ingår i: VVS 2000 Tabeller och diagram, Stockholm: Förlags AB VVS , 2001Kapitel i bok, del av antologi (Övrig (populärvetenskap, debatt, mm))
  • 12.
    Dahl, Jan
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hermansson, Roger
    Westerlund, Lars
    Abel, Enno
    Värmeströmning2008Ingår i: VVS 2000 Tabeller och diagram, Stockholm: Förlags AB VVS , 2008Kapitel i bok, del av antologi (Övrig (populärvetenskap, debatt, mm))
  • 13. Fredriksson, Christian
    et al.
    Hermansson, Roger
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    Leduc, Sylvain
    Förbättrad utformning av sekundärförbränningszon i vedpanna2002Rapport (Övrigt vetenskapligt)
  • 14.
    Hermansson, Roger
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    Short term water heat storage: an experimental and numerical investigation of phenomena that affect the degree of thermal stratification1993Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Thermal stratification was studied by measurements of the temperature and velocity fields in water heat storage's and by numerical simulations. The work includes experimental investigations in three model heat storage's of different size and comparisons to numerical simulations for two of the storages. Thermal stratification is essential for most applications of water heat storage's. Different ways of measuring the degree of stratification were presented. Exergy efficiency was considered as best to use if the spatial resolution of the available temperature field is good. The thermal stratification is strongly dependent of the flow pattern in the storage. Mixing of hot and cold water near the inlet during charging can have a severe impact on the stratification. Much of the work was therefore focused on studies of this effect. Velocity measurements were first performed with Laser Doppler Anemometry techniques and later with the use of a Particle Image Velocimetry technique based on double or multiple exposure photographs of particles in seeded water. These measurements focused on studies of the boundary layer at the wall. The results show that boundary layer velocities increase with the available height up to a limit, determined by the temperature difference, after which the dependence was very weak. They also show an exchange of water between the boundary layer and the core of the storage. A video based Particle Image Velocimetry technique was finally developed which opened the possibility to measure the in plane velocities in a cross section of a small model storage during complete experiments. FLOW3D, a commercial software for flow simulations, was used to simulate measured velocity and temperature fields. Good agreement with the experimental results was found. This justified the use of FLOW3D to simulate the effect on stratification of parameters that could not be studied in the experiments. The simulations for the small storage show that differences in the exergy efficiency obtained in the initial part of charging cycles, due to different charging conditions, tended to be evened out by heat diffusion during the continuation of the cycle. This was found to be true at least as long the Richardson number was kept high enough to avoid forced mixing. An alternative choice of the length and velocity scales to use in the Richardson number was suggested. The width of the inlet slot was used as the characteristic length and the velocity of the inlet jet when it approaches the storage wall, as the characteristic velocity for the mixing. With this definition for the Richardson number the simulations indicate that unstable charging can be expected for Richardson numbers below 0.5-0.05. Further work is needed for verification of these findings for larger storage's. Still it is believed that the results of this work can be valuable for design optimization of short term water heat storage's.

  • 15.
    Hermansson, Roger
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    Short term water heat storage: an experimental investigation of thermal stratification1989Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 16. Hermansson, Roger
    et al.
    Dahl, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Isacsson, P.
    Schroeder, K.
    Supply of steam or nitrogen to obtain an inert atmosphere at the top of a solar water heat storage tank1997Ingår i: Proceedings of the 7th International Conference on Thermal Energy Storage: Megastock 97 / [ed] Kiyoshi Ochifuji, Sapporo, 1997Konferensbidrag (Refereegranskat)
  • 17.
    Hermansson, Roger
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    Eriksson, Gunnar
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Increased combustion stability in modulating biomass boilers for district heating systems2002Rapport (Övrigt vetenskapligt)
    Abstract [en]

    One of the problems in small district heating systems is the large load variation that must be handled by the system. If the boiler is designed to cover the needs during the coldest day in winter time in northern Europe it would have to run at loads as low as 10% of full load during summer time, when heat is needed only for tap water production. Load variations in small networks are quite fast and earlier investigations have shown that existing biomass boilers give rise to large amounts of harmful emissions at fast load variations and at low loads. The problem has been addressed in different ways: Three new boiler concepts have been realized and tested: A prototype of a 500 kW boiler with partitioned primary combustion chamber and supplied with a water heat store. A 10 kW bench scale combustor and a 500 kW prototype boiler based on pulsating combustion. Bench scale boilers to test the influence from applied sound on emissions and a 150 kW prototype boiler with a two-stage secondary vortex combustion chamber. Development of control and regulating equipment: Glow Guard, a control system using infra-red sensors to detect glowing char on the grate, has been constructed and tested. A fast prediction model that can be used in control systems has been developed. Simulation of the combustion process: Code to simulate pyrolysis/gasification of fuel on the grate has been developed. Combustion of the gas phase inside the combustion chamber has been simulated. The two models have been combined to describe the combustion process inside the primary chamber of a prototype boiler. A fast simulation code based on statistical methods that can predict the environmental performance of boilers has been developed. One of the boiler concepts matches the desired load span from 10 to 100% of full load with emissions far below the set limits for CO and THC and close to the set limits for NO{sub x}. The other boilers had a bit more narrow load range, one with very low emissions except for NO{sub x} and the other with emissions close to the set limits. The Glow Guard worked as desired and will be a useful tool for control of combustion on the grate. The simulation of the processes inside the combustion chamber matches the experimental results well in terms of velocity and temperature. Species concentration were reasonable well described at the exit from the combustion chamber but were poorly described above the fuel bed. The dynamic model based on statistics is capable of reproducing the over-all dynamic behaviour of biofuel-fired boilers.

  • 18.
    Hermansson, Roger
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    Lundgren, Joakim
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Solar assisted small-scale biomass district heating system in the northern part of Sweden2004Ingår i: International Journal of Green Energy, ISSN 1543-5075, E-ISSN 1543-5083, Vol. 1, nr 4, s. 467-482Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This article presents a case study of a projected solar assisted biomass district heating system in the north of Sweden. It is generally known that a biomass district heating system combined with solar heat brings many important benefits. The most common system solution is to install a heat store and a large solar collector field near the heating central. No plant of this type is however in operation in the northern part of Sweden. The main reason for this is that the solar irradiation at these latitudes is very low when the demand for heat is high. Solar heat could however be useful during summer in order to generate hot tap water. One problem is that the heat losses, calculated as percentage of the delivered heat, become very large during these months. This article presents the idea of allowing the connected households to generate their own hot tap water using solar collectors and heat stores installed in each house. The district heating network can therefore be closed in summer, which eliminates the heat losses outside the heating period. A case study of a projected plant has been carried out and it is shown that it is possible to reduce the heat losses by 20% compared to a conventional system. This idea also provides many other important technical and economic benefits.

  • 19.
    Leduc, Sylvain
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Fredriksson, Christian
    TPS Termiska Processer AB, Nyköping.
    Hermansson, Roger
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Particle-tracking option in Fluent validated by simulation of a low-pressure impactor2006Ingår i: Advanced Powder Technology, ISSN 0921-8831, E-ISSN 1568-5527, Vol. 17, nr 1, s. 99-111Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To decrease the emission of particles from a domestic wood-log boiler, particle traps based on intertial separation could be used. These could be designed and optimized with simulation tools, i.e. computational fluid dynamics (CFD) modeling. To find out whether the particle-tracking option in a commercial CFD code is reliable, a low-pressure impactor has been studied and each stage of the impactor simulated. By comparing experiments, it has been possible to determine the accuracy of the particle-tracking option for the CFD code. It has been shown that the particle-tracking procedure in the CFD software Fluent V6.0 offers good accuracy at velocities below 12 m/s with Reynolds numbers between 790 and 2150. Acceptable accuracy was shown for velocities of 20-170 m/s at Reynolds numbers between 960 and 2980. Considering actual flow velocities in a wood-log boiler and many other similar applications, the particle-tracking procedure should be accurate enough, at least for flows with a Reynolds number lower than 3000. Thus, it is recommended to use the software Fluent for simulations to find ways to reduce the particle emissions by use of mechanical traps. Three-dimensional simulations with either the Reynolds Stress Model (RSM) turbulence model, for accuracy, or the Renormalization Group (RNG) k-ε model, to save calculation time, should be used together with the stochastic particle tracking.

  • 20. Lindberg, Jenny
    et al.
    Hermansson, Roger
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    Modification of reaction rate parameters for combustion of methane based on experimental investigation at furnace-like conditions2004Ingår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 18, nr 5, s. 1482-1484Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A method for modifying reaction rate parameters in the Arrhenius rate equation for combustion of methane is proposed. Linear least-squares data fit to measured concentrations and temperatures is used to modify reaction rate parameters in the Arrhenius rate equation for combustion of methane in one step. The modified equation is compared to the one provided by the software Fluent by implementing both into a three-dimensional Fluent simulation. The modification of reaction rate parameters influences the result of computational fluid dynamics simulations to predict combustion at experimental conditions where the Fluent rate equation failed. With modified parameters, the size of the reaction zone increases to give better agreement with experiments than that obtained using the Fluent rate equation. This first test indicates that the method has the contingency of becoming a useful tool for modification of reaction rate parameters though it still needs further development.

  • 21. Lundgren, Joakim
    et al.
    Hermansson, Roger
    Dahl, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    A new biomass based boiler concept for small district heating networks2001Ingår i: Proceedings of the 2001 Joint international combustion symposium: Toward efficient zero emission combustion - advances in air-fuel and oxy-fuel technlogies, Houston, Tex: International Energy Agency (IEA), 2001Konferensbidrag (Refereegranskat)
  • 22. Lundgren, Joakim
    et al.
    Hermansson, Roger
    Dahl, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Experimental studies during heat load fluctuations in a 500 kW wood-chips fired boiler2004Ingår i: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 26, nr 3, s. 255-267Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Several long-term experiments with fluctuating thermal outputs have been carried out in a newly developed biomass fuelled boiler suitable for small district heating networks. The experiments have been performed by either using the furnace only or the furnace together with a water heat store. Comparisons between these two operation strategies have been made concerning emissions and overall performance. Furthermore, the plant has been run to match a simulated heat demand during different seasons, in order to study the performance of the system during more realistic operation conditions. The results are very satisfactory concerning both performance and emissions, using any of the control strategies. Typical emissions of CO and NOx during the experiments are in the range of 10–50 mgNm−3 (5–25 mgMJ−1) and 130–175 mgNm−3 (60–90 mgMJ−1), respectively. However, during summer when the heat demand is low or zero, operational problems will occur if the heat store is excluded. Therefore, the main conclusion is that the most appropriate solution for a small district-heating system is to use a water heat store to match the heat load variations, while the furnace operates at as constant thermal output as possible.

  • 23.
    Lundgren, Joakim
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hermansson, Roger
    Dahl, Jan
    Experimental studies of a biomass boiler suitable for small district heating systems2004Ingår i: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 26, nr 5, s. 443-453Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Extensive experiments have been carried out in a newly developed furnace suitable for small district heating networks. The fuel is wood-chips with moisture content in the range of 30-58%. One of the unique features of this new furnace is the broad thermal output span, which makes it possible to run the boiler down to 10% of maximum heat load, with maintained low emissions of CO and total hydrocarbons (THC). The aim of this study has been to evaluate the performance of the combustion chamber during steady-state operation in the complete thermal output range. The experiments show very good results over the entire thermal output range. In the range 60 kW up to 500 kW, the average CO content in the stack gases is typically below 25 mg Nm-3(20 ppm) and the NOx concentration below 195 mg Nm-3(95 ppm) during steady state conditions. At lower thermal outputs, the average CO content is below 105 mg Nm-3(84 ppm). (All values standardised to 10 vol% O 2.)

  • 24. Lundgren, Joakim
    et al.
    Hermansson, Roger
    Dahl, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    New furnace designed for small-scale combustion of wet and inhomogeneous biomass fuels2005Ingår i: Biomass for energy, industry and climate protection: 14th European Biomass Conference & Exhibition ; proceedings of the international conference held in Paris, France, 17 - 21 October 2005 / [ed] L. Sjunnesson, Florence: ETA - Renewable Energies , 2005Konferensbidrag (Refereegranskat)
  • 25.
    Lundgren, Joakim
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hermansson, Roger
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    Lundqvist, M.
    Design of a secondary combustion chamber for a 350 kW wood-chips fired furnace2003Ingår i: Proceedings, 4th International Conference on Fluid and Thermal Energy Conversion: FTEC 2003, 2003Konferensbidrag (Refereegranskat)
  • 26.
    Lundqvist, M.
    et al.
    Luleå tekniska universitet.
    Hermansson, Roger
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    CFD-simulation of a 350 kW Wood-Chip Fired Furnace2001Ingår i: Proceedings of the 2001 Joint international combustion symposium: Toward efficient zero emission combustion - advances in air-fuel and oxy-fuel technlogies, Houston, Tex: International Energy Agency (IEA), 2001Konferensbidrag (Refereegranskat)
  • 27. Pettersson, Esbjörn
    et al.
    Lundgren, Joakim
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hermansson, Roger
    Co-combustion of wood-shavings and horse manure in a small scale heating plant2006Ingår i: Proceedings: World Bioenergy 2006 : taking you from know-how to show-how ; 30 May - 1 June 2006, Jönköping, Stockholm: Swedish Bioenergy Association (SVEBIO) , 2006, s. 396-400Konferensbidrag (Refereegranskat)
  • 28. Veber, Pascal
    et al.
    Dahl, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hermansson, Roger
    Study of the phenomena affecting the accuracy of a video-based particle tracking velocimetry technique1997Ingår i: Experiments in Fluids, ISSN 0723-4864, E-ISSN 1432-1114, Vol. 22, nr 6, s. 482-488Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The development of a video-based particle tracking velocimetry (PTV) technique has focused on the problem of the accuracy of this method. The PTV-method can be decomposed into three parts: the recording of the experiment, the image processing and the evaluation of the velocities. The accuracy of each stage has been studied. Inaccuracies due to resolution, length scale, light intensity and distortion of the x and y direction are analysed. One of the main factors influencing the accuracy is the selection of the time difference between frames. During the evaluation of velocities, incorrect identifications of particles may occur. The relation between the time-step of the frames and the percentage of incorrect identifications has been shown. The percentage of false identifications increases with the size of the time-step. The resolution accuracy is however improved when the time-step is increased. An adequate selection of the time-step has to be made to obtain a high resolution accuracy and a limited number of incorrect identifications

  • 29. Wang, Chuan
    et al.
    Lundgren, Joakim
    Hermansson, Roger
    Dahl, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Straw-fired congeneration as a possibility to provide clean energy in rural areas in China2005Ingår i: Biomass for energy, industry and climate protection: 14th European Biomass Conference & Exhibition ; proceedings of the international conference held in Paris, France, 17 - 21 October 2005, Florence: ETA - Renewable Energies , 2005Konferensbidrag (Refereegranskat)
  • 30. Westerlund, Lars
    et al.
    Dahl, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hermansson, Roger
    Heat and mass transfer simulations of the absorption process in a packed bed absorber1998Ingår i: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 18, nr 12, s. 1295-1308Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Numerical modelling of the absorption process in a cross-current absorber has been performed with FLOW3D, a commercially available software. The simulations are verified by comparisons with experimental results. The modelling of mass and heat transfer is discussed. Comparisons regarding the overall capacity as well as transfer rates show good agreement between experiments and simulations. It is possible to model the mass and heat transfer for a cross-current absorber if the equilibrium line for the absorption solution is known.

  • 31. Westerlund, Lars
    et al.
    Dahl, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hermansson, Roger
    Numerical simulation of multiphase flow in a packed bed absorber: comparision with experimental results1995Ingår i: Multiphase Flow 1995: Proceedings of the Second International Conference on Multiphase Flow / [ed] A. Serizawa; T. Fukano; J. Bataille, Amsterdam: Elsevier, 1995Konferensbidrag (Refereegranskat)
  • 32.
    Westerlund, Lars
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hermansson, Roger
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    Cervantes, Michel
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Computational fluid dynamics optimisation of a pellet burner2012Ingår i: Thermal Science, ISSN 0354-9836, E-ISSN 2334-7163, Vol. 16, nr 4, s. 1275-1286Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Increased capacity of computers has made the computational fluid dynamics technology attractive for the design of different apparatuses. Optimisation of a pellet burner using the computational fluid dynamics was investigated in this paper. To make the design tool work fast, an approach with only mixing of gases was simulated. Other important phenomena such as chemical reactions were omitted in order to speed up the design process. The original design of the burner gave unsatisfactory performance. The optimised design achieved from simulation was validated and the results show a significant improvement. The power output increased and the emission of unburned species decreased but could be further reduced. The contact time between combustion gases and secondary air was probably too short. An increased contact time in high temperature conditions would possibly improve the design further.

  • 33.
    Westerlund, Lars
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hermansson, Roger
    Fagerström, Jonathan
    Energy Technology and Thermal Process Chemistry, Umeå University.
    Flue gas purification and heat recovery: a biomass fired boiler supplied with an open absorption system2012Ingår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 96, s. 444-450Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A new technique for energy recovery combined with particle separation from flue gas has been tested in this project. A conventional small boiler for biofuel produces besides heat also particles to the environment through the flue gas. Decreasing the impact on the environment is desirable. Increased efficiency can be obtained if the temperature and water content of the flue gas can be further reduced. Installing an open absorption system in the heat production unit fulfils both these demands. An experimental unit has been built and tested in the last 2 years. The results show a reduction of particles in the flue gas by 33–44% compared to the ordinary system. At the same time the heat production from the unit increased by 40% when fired with wet biofuels.

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