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  • 51. Ryman, Christer
    et al.
    Wang, Chuan
    Larsson, Mikael
    Dahl, Jan
    Grip, Carl-Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Minimization of energy consumption and conversion cost for BF-BOF system based on optimised use of ferrous burden materials2006Ingår i: Proceedings: 5th European Oxygen Steelmaking Conference : 26 - 28 June 2006, Aachen, Germany, Düsseldorf: Verlag Stahleisen , 2006Konferensbidrag (Refereegranskat)
  • 52. Sandberg, Johan
    et al.
    Dahl, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Adaptation and development of process integration tools for an existing iron ore pelletising production system2008Ingår i: Proceedings of the 18th International Congress of Chemical and Process Engineering: 24th - 28th August - Prague - Czech Republic, Prague: ČSCHI - Czech Society of Chemical Engineering , 2008, Vol. 4Konferensbidrag (Refereegranskat)
    Abstract [en]

    Energy consumption has been in focus in the mining industry for some time and efforts to optimise the energy consumption in individual process steps have been made with fairly good results. However, until now process integration techniques has been sparsely utilised. In this paper a project aimed to develop and apply process integration techniques for the processing units of a magnetite based iron ore upgrading plant producing mainly iron ore pellets is described. The iron ore upgrading system in focus within this research project is the LKAB facilities in Kiruna in the north of Sweden. A brief introduction of the iron ore upgrading system of LKAB in Kiruna is given. The background problem is formulated and an overview of MIND/reMIND, the main methods and tools to be used in the project are described. Finally, some of the main focus areas of the optimisation are discussed. The paper ends with some closing statements regarding the current status of the project and the future work.

  • 53.
    Sandberg, Johan
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Larsson, Mikael
    Wang, Chuan
    Dahl, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Lundgren, Joakim
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    A new optimal solution space based method for increased resolution in energy system optimisation2012Ingår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 92, nr 1, s. 583-592Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper a new method for increased time resolution in multi-period Mixed Integer Linear Programming (MILP) optimisation is presented and applied to a district heating system. The proposed method facilitates the analysis of many time periods in multi period MILP optimisation projects. In the paper, a 365 time period model spanning 1 year developed with the novel method is compared to a 12 time period model developed with a more conventional methodology. The new method offers a significant decrease in the amount of input data for multi period models and facilitates changes to the analysed time span or resolution in time. In the application of the new method oil savings of 7% compared to the current operational strategy of the district heating system are revealed.

  • 54. Sandberg, P.
    et al.
    Larsson, Mikael
    Dahl, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Söderström, M.
    Vuorinen, H.
    In search of stability: investigating flexible and stable production strategies for an optimised steel plant2004Ingår i: SCANMET II: 2nd International Conference on Process Development in Iron and Steelmaking, Luleå: MEFOS , 2004Konferensbidrag (Refereegranskat)
  • 55.
    Sandberg, Peter
    et al.
    Asset Management, Business Development, Vattenfall Power Consultant AB, Stockholm.
    Larsson, Mikael
    Dahl, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Söderström, Mats
    Division of Energy Systems, Department of Mechanical Engineering, Linköping Institute of Technology.
    Vuorinen, Henrik
    SSAB Tunnplåt AB.
    In search of stability: investigating flexible and stable production strategies for an optimised steel plant2006Ingår i: International Journal of Green Energy, ISSN 1543-5075, E-ISSN 1543-5083, Vol. 3, nr 2, s. 159-170Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    It is crucial for a steel making production system to operate at the lowest possible production cost, while satisfying stability and reliability conditions. To plan future production strategies, it is therefore important to be able to model the system behaviour when internal and external parameters are changed. In this study the sensitivity and stability of an optimised solution, of an integrated steel plant, have been investigated. The solution's sensitivity has been analysed taking both internal process changes and external price variations into account, through applying both simulation and optimisation. The analysis also includes both costs and environmental issues such as carbon dioxide and sulphur emissions. Based on the methodology suggested, it is possible to determine the stability of the system solution, including both economic and environmental performance.

  • 56.
    Tari, Mehrdad Heidari
    et al.
    Linköpings universitet.
    Larsson, Mikael
    Söderström, Mats
    Linköpings universitet.
    Dahl, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Improvment of energy usage and environmental impacts in a steel plant2002Ingår i: 85th Steelmaking Conference proceedings: March 10 - 13, 2002, Nashville, Tennessee / [ed] David L. Kanagy, Warrendale, Pa: Iron and Steel Society , 2002Konferensbidrag (Refereegranskat)
  • 57. 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

  • 58.
    Vesterlund, Mattias
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Dahl, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    A method for the simulation and optimization of district heating systems with meshed networks2015Ingår i: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 89, s. 555-567Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    There are two main methods nowadays for modeling district heating systems, but a key disadvantage of both is that a real network containing loops cannot be described without artificial simplifications in order to eliminate those distinguishing features. However, loops are very common in mature networks that have developed a meshed structure, and make the distribution of mass and heat flows quite characteristic. For this reason, a new process integration method for modeling complex district heating systems containing loops is described in this paper. This method makes it possible to analyze how loops and bottlenecks affect the behavior of the network, as well as the distribution path of the thermal energy in it. The district heating system in the town of Kiruna (located in the north of Sweden) has a complex design with several loops and part of it is used in the paper as an example of application.

  • 59.
    Vesterlund, Mattias
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Sandberg, Johan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    Lindblom, Bo
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Dahl, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    A new method for modeling district heating systems2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    Due to the mining of iron ore by the local mining industry (LKAB) a deformation zone is approaching the town of Kiruna, which is situated in the north of Sweden. The town is going through an urban transformation and parts of the town is about to be relocated. The relocating of the town is affecting all the infrastructure of the town, one of those is the district heating system. The aim of this paper is to apply a process integration method to study how the existing district heating system is behaving and to create a model for the whole district heating system.The district heating system in the town has a complex design with several loops. When dealing with modeling of a district heating system there are two methods that are most common, the Danish- and the German methods. These methods allow for simplification of the network shape, still with good accuracy in system behavior compared to real system behavior. A disadvantage with these two methods is that they cannot handle a district heating system that contains loops without making changes compared to the real physical system.A method that allows modeling of loops in the district heating system has been developed, using the remind-software. This method makes it possible to analyze how loops in the district heating system are behaving, without making physical changes when modeling the district heating system. The model will be used as a default model for redesigning the district heating system when moving the town. It will also be used to optimize heat deliveries from LKAB district heating system and for analyzing the possibility for seasonal storage of waste energy from LKAB and municipality energy company TVAB or how new heat production plants should optimized.In this paper the method is described and applied in order to model the whole present district heating system for the town.

  • 60.
    Vesterlund, Mattias
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Sandberg, Johan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    Lindblom, Bo
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Dahl, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Evaluation of losses in district heating system, a case study2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    To be able to create a model that accurately describes a district heating system, it is important to identify the thermal losses and how they are distributed. However, general methods targeting the determination of losses are scarce in the literature. In the current case the losses for a district heating system in Kiruna, a town in northern Sweden, has been estimated in the year 2010 to be 12%, which is in the range for a typical Swedish network. Unfortunately, detailed information of the thermal losses is lacking.In this paper two methods to determine loss distribution in a district heating system are presented.Two databases of pipe lengths and diameters have been compiled for two piping categories, loops and feeds. Any missing data regarding pipe diameters in the map has then been determined with the two different methods.In the first method average pipe diameters for loops and feeds are calculated. All pipes with unknown diameter are then assumed to have the average one. The second method considers a percentage based distribution of known diameters and assigns the same distribution to the missing pipe diameters. The losses were estimated in the whole system according to the data from a pipe producer catalogue, in which losses are calculated according to current European standard. The results show that the losses in the system are similar to the losses caused by pipes with the lowest insulating capacity.By using the two methods two fictitious pipe series reproducing exactly the losses in the system are created by scaling the calculated losses of the catalogue pipe series which would give the most similar losses (the one with the lowest insulating capacity). This adjustment was +3.1% by using the first method, and +4.9% by using the second method.The major conclusion of this study is that, both methods can be used for calculating the distribution of thermal losses in the district heating system of Kiruna; moreover, this kind of analysis can be an important tool for analyzing investments in the district heating network in Kiruna.

  • 61.
    Vesterlund, Mattias
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Toffolo, Andrea
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Dahl, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Optimization of multi-source complex district heating network: a case study2016Ingår i: Proceeding of 29th International Conference on efficiency, Cost, Optimization, Simulation and Enviromental Impact of Energy Systems, 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    The level of complexity for a district heating network increases with the maturity of the network, and this affects the pattern of the distribution of the hot water from the heat production sites to the end users. The majority of district heating systems are also multi-source networks, typically supported with heat from one main production site and other smaller satellite sites that are activated when required. In general, local energy companies have a lack of knowledge regarding how a meshed network behaves when different production sites are operated. The schedule of heat generation at the different sites is often based on staff experience and some general rules of thumb.

    In this paper a method for modeling and simulating complex district networks is further developed in order to optimize the total operating costs of a multi-source network, with constraints on the pressure and temperature levels in the user areas and on the heat generation characteristics at each production site.

    The optimization results show that the usage of the cheapest resources is preferred to a distributed generation of heat, even if some of the pipes may exceed the recommended thermal load capacity. The main site water supply temperature is found to be the lowest allowed by the constraint on the temperature of the water supplied to the end users, since the decrease of the costs associated with the lower thermal losses in the network is not counterbalanced by the increase of those associated with the pumping power of a larger water mass flow rate.

  • 62.
    Vesterlund, Mattias
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Toffolo, Andrea
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Dahl, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Optimization of multi-source complex district heating network, a case study2017Ingår i: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 126, s. 53-63Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The level of complexity for a district heating network increases with the maturity of the network, and this affects the pattern of the distribution of the hot water from the heat production sites to the end users. The majority of district heating systems are also multi-source networks, typically supported with heat from one main production site and other smaller satellite sites that are activated when required. In general, local energy companies have a lack of knowledge regarding how a meshed network behaves when different production sites are operated. The schedule of heat generation at the different sites is often based on staff experience and some general rules of thumb.

    In this paper a method for modeling and simulating complex district networks is further developed in order to optimize the total operating costs of a multi-source network, with constraints on the pressure and temperature levels in the user areas and on the heat generation characteristics at each production site.

    The optimization results show that the usage of the cheapest resources is preferred to a distributed generation of heat, even if some of the pipes may exceed the recommended thermal load capacity. The main site water supply temperature is found to be the lowest allowed by the constraint on the temperature of the water supplied to the end users, since the decrease of the costs associated with the lower thermal losses in the network is not counterbalanced by the increase of those associated with the pumping power of a larger water mass flow rate.

  • 63.
    Vesterlund, Mattias
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Toffolo, Andrea
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Dahl, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Simulation and analysis of a meshed district heating network2015Ingår i: ECOS 2015: 28th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems , 2015Konferensbidrag (Refereegranskat)
  • 64.
    Vesterlund, Mattias
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Toffolo, Andrea
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Dahl, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Simulation and analysis of a meshed district heating network2016Ingår i: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 122, s. 63-73Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The flow distribution in a district heating network tends to become no longer obvious when system design is developed and its complexity increased. As a consequence, the network owner, often the local energy company, is in need of a simulation program to have the possibility of analysing network behaviour and expand the understanding about the operation of district heating system. In this paper, a simulation tool developed in MATLAB/Simulink is applied in order to analyse the flow distribution in the district heating network of the town of Kiruna (Sweden). The network in Kiruna has been developing since the 60s and is today a complex network with a meshed structure, i.e. it is formed by a set of loops from which secondary branches depart. The simulation tool is part of a methodology that has specifically been developed to analyse the flow pattern in such kind of networks without altering their physical structure, and it is expected to be a valuable tool for the redesign of the network in the forthcoming relocation of some of the urban districts. The results about the current network configuration show that only a few pipes in the network are exceeding the levels of heat flow recommended by pipe manufacturers. The largest drops in pressure and temperature from the heat production site to the nodes serving the main consumer areas are within 1.2 bar and 9 °C in the days of highest demand.

  • 65.
    Wang, C.
    et al.
    Swerea MEFOS AB.
    Larsson, Mikael
    Yan, Jinyue
    Dahl, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    CO2 emission reduction in the steel industry by using emission trading programs2007Ingår i: International Journal of Green Energy, ISSN 1543-5075, E-ISSN 1543-5083, Vol. 4, nr 5, s. 505-518Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The implementation of the EU Emission Trading Scheme ( ETS) started on January 1(st) 2005 according to national plans for allocating emissions rights. The steel industry is one of the industrial sectors included in this scheme. The objective of this paper is to investigate and evaluate the optimum solution( s) for European steel plants to meet their emission allowance with low reduction cost. An optimization model based on a Swedish steel plant is developed and used. Three scenarios were created in the model, i. e., internal changes within the steel plant, EU ETS, and the Kyoto Protocol's clean development mechanism ( CDM). For the last scenario, China was selected as a country of the non- Annex I Party for the emission trading by CDM. The modeling results show that the studied plant will face an emission gap between allowed and calculated emissions in the near future. Compared to EU ETS, the implementation of CDM projects will make the plant reduce CO2 emissions at a lower cost. The internal changes within the plant will also play an important role for the solution of low abatement cost. The model developed could serve as a benchmark for the future emission trading simulation's purpose within the European steel industry.

  • 66. Wang, Chuan
    et al.
    Chen, Shuming
    National Bio Energy Co., Ltd..
    Lundgren, Joakim
    Dahl, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Technical and economic barriers for utilization of straw-fired co-generation in China2007Ingår i: From Research to Market Deployment: 15th European Biomass Conference & Exhibition ; proceedings of the international conference held in Berlin, Germany, 7 - 11 May 2007 / [ed] K. Maniatis, Florence: ETA - Renewable Energies , 2007Konferensbidrag (Refereegranskat)
    Abstract [en]

    In order to promote the development and utilization of renewable energy, improve the energy structure, diversify energy supplies, safeguard energy security, protect the environment, and realize the sustainable development of the economy and society, the Chinese government is now paying more attention to develop and utilizing the renewable energy in China. The available biomass resources (e.g. straw and crop residues) for energy use in China are abundant. As one bioenergy technology, straw-fired cogeneration technology can provide clean energy in rural areas in China. In recent years, some investors have shown their interests in developing straw-fired cogeneration plants. Some projects are already in the pipeline and the number of projects is expected to increase in the near future. However, there exist technical as well as economic barriers hindering the implementation of straw-fired cogeneration projects. These barriers include 1) feedstock preparation barrier regarding the straw collection, transportation, treatment and storage and less incentives from farmers; 2) some technical and production operation management barriers; 3) over-expected market demands; 4) economic barriers; 5) lack of strong policy support, etc. In this paper, all these barriers have been studied and analyzed. In addition, good management experiences of straw-fired cogeneration plants from European countries have been reviewed as a comparison with those plants in China and based on that, some recommendations have been made to improve the implementation conditions for straw-fired cogeneration projects in China.

  • 67. Wang, Chuan
    et al.
    Johnsson, A.
    Swerea MEFOS AB.
    Wikström, Jan-Olov
    Engdahl, J.
    SSAB Tunnplåt AB.
    Asp, Björn
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Dahl, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Modeling analysis on potential energy saving in a Swedish rolling mill2011Konferensbidrag (Refereegranskat)
  • 68. Wang, Chuan
    et al.
    Larsson, Mikael
    Yan, Jinyue
    Dahl, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Impact on CO2 emission allowance of EU emission trading Scheme (ETS) in a Swedish steel plant by clean development mechanism (CDM)2005Ingår i: Proceedings, International Green Energy Conference, 2005Konferensbidrag (Refereegranskat)
  • 69. 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)
  • 70. Wang, Chuan
    et al.
    Ryman, Christer
    Dahl, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Potential CO2 emission reduction for BF-BOF steelmaking based on optimised use of ferrous burden materials2009Ingår i: International Journal of Greenhouse Gas Control, ISSN 1750-5836, E-ISSN 1878-0148, Vol. 3, nr 1, s. 29-38Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Currently, the blast furnace (BF) to basic oxygen furnace (BOF) is the dominant steel production route in the steel industry. The direct CO2 emission in this process system exceeds 1 t of CO2/t of crude steel produced. Different ferrous burden materials, for instance iron ore and scrap, can be used in various proportions in this steelmaking route. This paper analyses how energy use, conversion costs, and CO2 emissions can be influenced by the use of different ferrous burden materials when producing crude steel. An optimisation mixed integer linear programming (MILP) model has been applied for analysis. By the use of the optimisation model, it is possible to highlight some issues of special importance, such as best practices to increase production at low conversion cost, or best practices to increase production at low CO2 emission. It is found out that more benefits will be gained when using the system-oriented analysis to the steelmaking process. Furthermore, a comprehensive view of the trade-offs between the objectives of Cost and CO2 can provide useful information for decision makers to generate strategies under the future emission trading.

  • 71.
    Wang, Xin
    et al.
    DNV China.
    Wang, Chuan
    Grip, Carl-Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Dahl, Jan
    Implementation of energy audit in the Chinese steel industry: case studies of integrated steel plants2008Ingår i: SCANMET III: 3rd International Conference on Process Development in Iron and Steelmaking, 8-11 June 2008, Luleå, Sweden, Luleå: MEFOS , 2008, Vol. 1, s. 417-426Konferensbidrag (Refereegranskat)
    Abstract [en]

    Steel production is one of the energy intensive industries in the world. Energy saving measures are of increasing interest to Chinese steel industry in recent years. One of the technical instruments of energy saving is energy audit. This paper presents the energy audit analysis of integrate steel plants in China as a case study. The analysis is useful to determine the actual consumption, reveal the anomalies and suggest corrective measures. These will provide clear indication on the pattern of energy losses and will aid in decision support for evolution of energy saving measures. The paper will show the achievements of Chinese steel plants during these years of energy saving activities proposed by government and the potential for energy efficient renovation. Some suggestion has been made in order to widely use this analytical diagnostic tool in Chinese steel industry.

  • 72.
    Westerlund, Lars
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Dahl, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Absorbers in the open absorption system1994Ingår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 48, nr 1, s. 33-49Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper describes an experimental study of four different absorber designs in this type of system: cross-current and counter-current packed-absorbers, the spray absorber and fluid-bed absorber. In a laboratory pilot, plant, working lines for the absorbers were determined under adiabatic conditions. The influences of internal solution flow, gas flow, pressure drop and dissipation are discussed. The working lines represent the efficiency for each absorber. The highest performance occurs with the packed-bed absorbers, followed by the fluid-bed absorber and finally the spray absorber. For open absorption systems in air-conditioning applications (small scale) the fluid-bed absorber should be chosen

  • 73. Westerlund, Lars
    et al.
    Dahl, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Application of an open absorption heat pump for energy conservation in public bath2002Ingår i: Proceedings of the International Sorption Heat Pump Conference: September 24 - 27, 2002, Shanghai / [ed] Ruzhu Wang, Beijing: American Science Press Inc., 2002Konferensbidrag (Refereegranskat)
  • 74. Westerlund, Lars
    et al.
    Dahl, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Avfuktning av luft: Adiac-systemet, funktion och dimensioneringskriterier1983Rapport (Övrigt vetenskapligt)
  • 75. Westerlund, Lars
    et al.
    Dahl, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Avfuktning av luft: Adiac-systemet, ny torkmetod1982Rapport (Övrigt vetenskapligt)
  • 76. Westerlund, Lars
    et al.
    Dahl, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Multiphase flow in a packed bed absorber: comparison to experimental results1999Ingår i: Applied Modelling and Simulation, International conference, 1999Konferensbidrag (Refereegranskat)
  • 77.
    Westerlund, Lars
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Dahl, Jan
    Open absorption system: experimental study in a laboratory pilot plant1991Ingår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 38, nr 3, s. 215-229Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The open absorption system is specially fitted in drying processes using air for the transport of the water. Advantages of the system are that different types of energy supply can be used, and that direct contact between the working media and the solution gives an effective absorber. This experimental study concerns measurements of the capacity of the system when a cross-flow absorber is used. Experiments were done under adiabatic and non-adiabatic conditions, and the results show that non-adiabatic conditions give a considerable increase in the absorption capacity. The dissipation of solution media increases strongly for air velocities over 2m/s. However, a demister can be used to reduce these losses. Investigation of the packing depth shows that the absorption takes place mainly in the first quarter of the packing. Different types of plastic packings were studied, the Telpac packing giving the best results.

  • 78.
    Westerlund, Lars
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Dahl, Jan
    Use of an open absorption heat-pump for energy conservation in a public swimming-pool1994Ingår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 49, nr 3, s. 275-300Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A conventional climatization system at a public swimming-pool normally uses outdoor air to remove the moisture from the facility. This practice results in large heat losses. An open absorption heat-pump can dehumidify the outlet air from the building: this makes it possible to recirculate a larger amount of air and so reduce the heating requirement for the facility significantly. Measurements on two types of systems have been performed during approximately 4000 h in a bath house in northern Sweden. In 1990, the use of an open absorption heat-pump decreased the heat supply by 445 MWh (from 742 MWh), while the electricity supply was increased by 233 MWh. The uncertainty in the annual energy saving with the open system can be estimated to be in the range 10-15%. If the present electric energy supply to the generator is replaced by another energy source, for example natural gas, the electricity demand of the absorption system will decrease considerably. The results show that public baths are an interesting application area for the open absorption technique

  • 79.
    Westerlund, Lars
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Dahl, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Öppet absorptionssystem i badhus: Resultat och utvärdering av långtidsförsök med avfuktningssystemet vid simhallen i Öjebyn1993Rapport (Övrigt vetenskapligt)
  • 80.
    Westerlund, Lars
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Dahl, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hansson, Hans
    Luleå tekniska universitet.
    ADIAC-systemet: Egenskaper hos olika fyllbäddstyper1987Rapport (Övrigt vetenskapligt)
  • 81. 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.

  • 82. 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)
  • 83. Westerlund, Lars
    et al.
    Dahl, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Johansson, Lars
    Theoretical investigation of the heat demand for public baths1996Ingår i: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 21, nr 7-8, s. 731-737Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Public baths normally use outdoor air to remove moisture from the building. This procedure results in large heating demands. A theoretical hour-based method for estimation of the heating demand has been developed. The method allows for dynamic behaviour with correct time periods for each mass-transfer level. Results of predictions with this method have been compared with yearly estimates of the heating demand based on actual measurements in a public bath. The difference is 3%. A parametric study shows that the air temperature and relative humidity in the building strongly influence the heating demand. Comparisons with other prediction methods based on use of the duration curve or mean annual outdoor temperature show differences less than 5% from results obtained with the hour-based method. The simpler approaches (use of a duration curve or mean value) fail when minimum outdoor airflow must be considered, as will be the case, for instance, when comparing different energy-saving systems or design of components for the climate system.

  • 84. Westerlund, Lars
    et al.
    Hansson, Hans
    Luleå tekniska universitet.
    Dahl, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Avfuktning av luft: AFFSE-systemet1986Rapport (Övrigt vetenskapligt)
12 51 - 84 av 84
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