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  • 201.
    Takami, Kourosh Mousavi
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Mahmoudi, Jafar
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Lindenmo, Magnus
    Cogent Power Ltd, Surahammars Bruk.
    Multivariable data analysis of a cold rolling control system to minimise defects2011In: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 54, no 5-8, p. 553-565Article in journal (Refereed)
    Abstract [en]

    This paper focuses on the application of principal component analysis (PCA) to thoroughly analyse and interpret multidimensional data from a cold rolling process. The analysis includes the effects of variables on the final properties of strips in a cold rolling mill. Unscrambler software was used to analyse and identify hidden variables. Variable correlations were also used to derive correlations between the control parameters. The results of this research will be used to improve the selection of material in order to reduce the occurrence of defects in the cold rolling process and to improve the adjustment of the set points that are performed in every pass or section of the cold rolling process. The hot rolled strips that enter the cold rolling mill are made of different materials and are produced by different strip manufacturers. Some strips break during the thickness reduction process in the cold rolling mill. This paper focuses on two possible causes of breakage: non-uniform strip material properties and failures in the rolling mill process. Two types of rolled strips (those that break and those that do not break) were compared to identify causes of breakage. The results indicate that breakages are caused by material or process failures. PCA was applied to the dataset in order to identify and analyse the relationships between the variables in the process. This information was used to interpret and diagnose the process behaviour. Swarm analysis and relating observations to process behaviour were able to distinguish between different start-up conditions, and between desirable and undesirable process conditions.

  • 202.
    Tao, J.
    et al.
    North China Electric Power University, Beijing, China.
    Lu, Q.
    North China Electric Power University, Beijing, China.
    Dong, C.
    North China Electric Power University, Beijing, China.
    Du, X.
    North China Electric Power University, Beijing, China.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Effects of electric current upon catalytic steam reforming of biomass gasification tar model compounds to syngas2015In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 100, p. 56-63Article in journal (Refereed)
    Abstract [en]

    Electrochemical catalytic reforming (ECR) technique, known as electric current enhanced catalytic reforming technique, was proposed to convert the biomass gasification tar into syngas. In this study, Ni-CeO<inf>2</inf>/γ-Al<inf>2</inf>O<inf>3</inf> catalyst was prepared, and toluene was employed as the major feedstock for ECR experiments using a fixed-bed lab-scale setup where thermal electrons could be generated and provided to the catalyst. Several factors, including the electric current intensity, reaction temperature and steam/carbon (S/C) ratio, were investigated to reveal their effects on the conversion of toluene as well as the composition of the gas products. Moreover, toluene, two other tar model compounds (benzene and 1-methylnaphthalene) and real tar (tar-containing wastewater) were subjected to the long period catalytic stability tests. All the used catalysts were analyzed to determine their carbon contents. The results indicated that the presence of electric current enhanced the catalytic performance remarkably. The toluene conversion reached 99.9% under the electric current of 4 A, catalytic temperature of 800 °C and S/C ratio of 3. Stable conversion performances of benzene, 1-methylnaphthalene and tar-containing wastewater were also observed in the ECR process. H<inf>2</inf> and CO were the major gas products, while CO<inf>2</inf> and CH<inf>4</inf> were the minor ones. Due to the promising capability, the ECR technique deserves further investigation and application for efficient tar conversion.

  • 203.
    Tao, Jun
    et al.
    North China Electric Power University ,China.
    Dong, Changqing
    North China Electric Power University, China.
    Lu, Qiang
    North China Electric Power University, China.
    Liao, Xiaolang
    North China Electric Power University, China.
    Yang, Yongping
    North China Electric Power University, China.
    Du, Xiaoze
    North China Electric Power University, China.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Catalytic cracking of biomass high-temperature pyrolysis tar using NiO/AC catalysts2015In: International Journal of Green Energy, ISSN 1543-5075, E-ISSN 1543-5083, Vol. 12, no 8, p. 773-779Article in journal (Refereed)
    Abstract [en]

    Nickel oxide supported on activated carbon (NiO/AC) catalysts were prepared and used for catalytic cracking of tars from inert high-temperature pyrolysis of biomass. Rice husk was selected as the feedstock, and pyrolyzed at 800 °C using a lab-scale pyrolysis set. The pyrolysis vapors were subjected to either thermal cracking or catalytic cracking under 500-700 °C. The results indicated the thermal cracking was not very efficient to convert the tars, while the catalytic cracking reduced both the light and heavy tars significantly. The yield of the light and heavy tars were decreased from 4.4 wt% and 1.9 wt% in the non-catalytic process to 0.2 wt% and 0.1 wt% in the catalytic process by the NiO/AC (4.3 wt%) at 700 °C. The catalytic cracking also increased the gas product remarkably, mainly the H2 and CO2. The catalytic performance of the NiO/AC catalyst could enhance at elevated catalytic temperatures and increased NiO content of the catalyst.

  • 204.
    Tao, Jun
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. North China Electric Power Univ (NCEPU), China.
    Lu, Qiang
    NCEPU, China.
    Dong, Changqing
    NCEPU, China.
    Du, Xiaoze
    NCEPU, China.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Electric current enhanced catalytic steam reforming of biomass gasification tar model compounds to syngas2014Conference paper (Refereed)
    Abstract [en]

    An efficient approach was proposed to convert biomass gasification tar into syngas via electrochemical catalytic reforming (ECR) using the Ni-CeO2/γ-Al2O3 catalyst. Three tar model compounds (toluene, benzene and 1-methyl naphthalene) were selected for ECR experiments in a lab-scale experimental set where an electrified Ni-Cr wire was installed in the catalyst bed to provide thermal electrons. Experiments were performed to reveal the effects of several factors on the conversion of the tar model compounds and product gas composition, as well as the catalytic stability over a long experimental period. The results indicated that the presence of the electric current enhanced the performance (carbon conversion and anti-coke deposition) of the catalyst remarkably. The toluene conversion reached as high as 99.9% under the electric current of 4 A, temperature of 850 °C and steam/carbon (S/C) ratio of 3.

     

  • 205.
    Tao, Jun
    et al.
    NCEPU, China.
    Zhao, Leiqiang
    NCEPU, China.
    Dong, Changqing
    NCEPU, China.
    Lu, Qiang
    NCEPU, China.
    Du, Xiaoze
    NCEPU, China.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology. Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Catalytic Steam Reforming of Toluene as a Model Compound of Biomass Gasification Tar Using Ni-CeO2/SBA-15 Catalysts2013In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 7, no 6, p. 3284-3296Article in journal (Refereed)
    Abstract [en]

    Nickelsupported on SBA-15 doped with CeO2 catalysts (Ni-CeO2/SBA-15)was prepared, and used for steam reforming of toluene which was selected as amodel compound of biomass gasification tar. A fixed-bed lab-scale set wasdesigned and employed to evaluate the catalytic performances of the Ni-CeO2/SBA-15catalysts. Experiments were performed to reveal the effects of several factorson the toluene conversion and product gas composition, including the reactiontemperature, steam/carbon (S/C) ratio, and CeO2 loading content.Moreover, the catalysts were subjected to analysis of their carbon contentsafter the steam reforming experiments, as well as to test the catalyticstability over a long experimental period. The results indicated that theNi-CeO2/SBA-15 catalysts exhibited promising capabilities on thetoluene conversion, anti-coke deposition and catalytic stability. The toluene conversionreached as high as 98.9% at steam reforming temperature of 850 °C and S/C ratioof 3 using the Ni-CeO2(3wt%)/SBA-15 catalyst. Negligible cokeformation was detected on the used catalyst. The gaseous products mainlyconsisted of H2 and CO, together with a little CO2

  • 206.
    Thorin, Eva
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Lindmark, Johan
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Kastensson, Jan
    Pettersson, Carl-Magnus
    Persson, Per-Erik
    PERFOMANCE OPTIMIZATION OF THE VÄXTKRAFT BIOGAS PRODUCTION PLANT –THE USE OF MEMBRANE FILTRATION2009In: Proceedings of ICAE'09, 2009, p. 594-602Conference paper (Refereed)
    Abstract [en]

    Today we can see a large potential for biogas production from any kind of organic residue as well as from different crops, farm land residues or graze. However, the technology for biogas production is not optimized and thus not fully cost-effective. To be fully commercially competitive with other types of fuels, efficiency improvements of the process are needed. In the research project BioGasOpt, performed in cooperation between Mälardalen University and industry, performance optimization of the Växtkraft biogas production plant and surrounding systems are studied.  In this paper the project will be presented and the possibility for improvements by using membrane filtration to reduce the dry matter in the recirculated water is addressed.

    In the Växtkraft biogas plant, in Västerås, Sweden, organic wastes from households and restaurants are mixed and fermented with crops from graze land. A lot of water is used in the process and the surplus is filtered off in decanter centrifuges. The decantate from the centrifuges is partly recirculated in the process and the problem is that the content of dry matter in the decantate is increasing and is today around 4 %.  In this paper the potential to use membrane filtration to improve the performance of biogas plants is studied. The consequences concerning production capacity, energy use, and operation of the plant are discussed. The first results from tests on using ceramic membrane filters at the Växtkraft biogas plant show that it possible to decrease the content of dry matter in the process water to 2 % at operation temperatures around 100˚C.   

  • 207.
    Thorin, Eva
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Lindmark, Johan
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Nordlander, Eva
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Odlare, Monica
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Kastensson, Jan
    Mercatus Engineering AB.
    Leksell, Niklas
    Svensk Växtkraft AB.
    Pettersson, Carl-Magnus
    Svensk Växtkraft AB.
    Performance Optimization of the Växtkraft Biogas Production Plant2011In: ICAE2011 - International Conference on Applied Energy, 2011, p. 1833-1844Conference paper (Refereed)
    Abstract [en]

    All over the world there is a strong interest and also potential for biogas production fromorganic residues as well as from different crops. However, to be commercially competitive withother types of fuels, efficiency improvements of the biogas production process are needed. In this paper the results of the project BioGasOpt, Performance optimization of the Växtkraft biogas production plant and surrounding system, are summarized. The project is performed in cooperation between Mälardalen University, the biogas plant Svensk Växtkraft AB, the membrane filtration company Mercatus Engineering AB and the farm Nibble Lantbruk AB.

    In the Växtkraft biogas plant organic wastes from households and restaurants are mixed and digested with crops from graze land. Four areas of importance for the performance of the plant are addressed in the BioGasOpt project: treatment of the feed material to enhance the fermentation rate, transport performance of gas and nutrients in the reactor, limitation of the ballast of organics in the water stream recirculated in the process, and use of the biogas plant residues at farms.

    The results indicate a potential to increase the biogas yield from the process with up to 40 % with pre-treatment of the feed and including membrane filtration in the process. The possibilities to improve the mixing in the digester also show a significant potential for even higher biogas yields. Modelling of the biogas process for better process control is also identified as a possible way to further improve the biogas yield. However, model development taking into account what input data is possible to get at a biogas plant in operation is needed.

    Further, the results from the project show that the residues from biogas production can be used as fertilizers but that the emission of N2O from the fertilised soil is dependent on the soil type and spreading technology.

  • 208.
    Thorin, Eva
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Lindmark, Johan
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Nordlander, Eva
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Odlare, Monica
    Mälardalen University, School of Business, Society and Engineering.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering.
    Kastensson, Jan
    Mercatus Engineering AB.
    Leksell, Niklas
    Svensk Växtkraft AB.
    Pettersson, Carl-Magnus
    Svensk Växtkraft AB.
    Performance optimization of the Växtkraft biogas production plant2012In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 97, p. 503-508Article in journal (Refereed)
    Abstract [en]

    All over the world there is a strong interest and also potential for biogas production from organic residues as well as from different crops. However, to be commercially competitive with other types of fuels, efficiency improvements of the biogas production process are needed. In this paper, results of improvements studies done on a full scale co-digestion plant are presented

     

    In the plant organic wastes from households and restaurants are mixed and digested with crops from graze land. The areas for improvements of the plant addressed are treatment of the feed material to enhance the digestion rate, limitation of the ballast of organics in the water stream recirculated in the process, and use of the biogas plant residues at farms. Results from previous studies on pre-treatment and membrane filtration of recirculated process water are combined for estimation of the total improvement potential. Further, the possibility to use neural networks to predict biogas production using historical data from the full-scale biogas plant was investigated. Results from investigation of using the process residues as fertilizer are also presented.

     

    The results indicates a potential to increase the biogas yield from the process with up to over  30 % with pre-treatment of the feed and including membrane filtration in the process. Neural networks have the potential to be used for prediction of biogas production. Further, it is shown that the residues from biogas production can be used as fertilizers but that the emission of N2O from the fertilised soil is dependent on the soil type and spreading technology.

  • 209.
    Thorin, Eva
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Nordlander, Eva
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Lindmark, Johan
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Yan, Jinyue
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Bel Fdhila, Rebei
    Mälardalen University, School of Sustainable Development of Society and Technology.
    MODELING OF THE BIOGAS PRODUCTION PROCESS- A REVIEW2012Conference paper (Refereed)
    Abstract [en]

    Production of biogas by digestion of organic wastes and other feedstock is one of the important technical solutions that contribute to the transform of the energy system from being fossil fuel dependent to renewable energy originated. To be fully commercial and competitive, the production of biogas needs to be further developed and optimized based on the technical, economic and environmental aspects. Thus, comprehensive understanding of fluid dynamics and microbial reactions in the digestion process is necessary to accurately and robustly model, predict and control the biogas production.

    In this paper possible pathways for modeling the biogas reactor is discussed based on previous work on anaerobic digestion modeling and modeling of the fluid flow in reactors. Important parameters for modeling biogas production, with a focus on processes using waste as feedstock, are considered. Identification of knowledge gaps for the modeling of the biogas process is performed and how to overcome the obstacles is addressed.

  • 210.
    Tomas Aparicio, Elena
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Li, Hailong
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Starfelt, Fredrik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dynamic Simulation of Torrefaction2012Conference paper (Refereed)
  • 211.
    Tora, Eman
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    CFD Ansys - Fluent simulation of prevention of dioxins formation via controlling homogeneous mass and heat transfer within circulated fluidized bed combustor2015In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 75, p. 130-136Article in journal (Refereed)
    Abstract [en]

    Internal mass and heat distribution within a combustor is a key factor of successful combustion process as it influences the contact between the reacting materials and helps reduce formation of undesired products such as dioxins via diminishing emerged hot or cold spots. Nevertheless in case of circulated fluidized bed combustor CFBC, it is difficult to keep a homogeneous heat and mass distribution due to the usage of combusting materials with variable and in some situations unpredictable compositions such as municipal and agricultural wastes. Thus this work investigates CFD Ansys -Fluent simulation as a tool to help the plant operator attain uniform heat and mass transfer via enabling the plant operator to adjust the operating conditions to fit well the used fuel. That is through: (a) visualizing the internal mass and heat distribution within a combustor, (b) manipulating the operating conditions of pressure, velocity, and bed particulates flow rate to determine the correct values considering the inevitable feature of the used fuels, (c) exploring operation deficits and sorting out the problems and (d) studying the feasibility of proposed modifications or changes. An illustrative case study is given as a methodology to demonstrate how likely reasons beyond combustor operation deficits can be defined and tackled. The case study is designed to exemplify the tool to achieve the objective of internal uniform heat and mass transfer within a combustor for given fuel composition and the operating conditions. 

  • 212.
    Trosten, Torbjörn
    et al.
    Mälardalen University, School of Innovation, Design and Engineering. Bombardier Transportation, Västerås, Sweden.
    Moskull, Henrik
    Bombardier Transportation, Västerås, Sweden.
    Lindahl, Martin
    Bombardier Transportation, Västerås, Sweden.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Maher, Azaza
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Energy Optimal Switching Frequency for a 750V Metro Traction Drive Using Silicon Carbide MOSFET Inverter2018In: Energy Optimal Switching Frequency for a 750V Metro Traction Drive Using Silicon Carbide MOSFET Inverter, 2018Conference paper (Refereed)
    Abstract [en]

    The introduction of Silicon Carbide (SiC) MOSFET based inverters into the traction drive makes it possible to increase the inverter switching frequency and reduce energy consumption. This paper describes how to model switching frequency dependent losses in the traction drive and compares the calculated losses to measurements done on a newly developed SiC MOSFET based traction drive. The results from the developed loss models of motor and inverter agrees well with the results from energy measurements. This paper concludes that the energy use of the traction motor and inverter can be simulated well using simple models where skin-effect losses in the motor are modelled in detailed. This paper also concludes that in terms of energy efficiency, the optimal switching frequency using a SiC MOSFET based inverter, is in the range of 3-6 kHz.

  • 213.
    Vassileva, Iana
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Bartusch, Cajsa
    Dahlquist, Erik
    Differences in electricity and hot water consumption in apartments of different sizes2008Conference paper (Refereed)
  • 214.
    Vassileva, Iana
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Bartusch, Cajsa
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Yan, Jinyue
    Mälardalen University, School of Sustainable Development of Society and Technology. KTH, Stockholm.
    Interactions between power producers and customers2009Conference paper (Refereed)
    Abstract [en]

    In the future we can expect new types of more interactive communications between singlecustomers and groups of customers towards the energy market companies. These can be developas a result of the introduction of individual metering of electricity, and then utilize thisinformation both for information to the customers, as well as different kind of control of thepower system. The information can be through interactive displays where instant and aggregatedenergy and power utilization is presented, but also with a possibility to react to differences inprices by e.g. shutting of some power consumers to avoid high costs. Different types ofinteractions are discussed in the paper.

  • 215.
    Vassileva, Iana
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Bartusch, Cajsa
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Wallin, Fredrik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    A simulation model of the interactions between power producers and customers2008In: Conference proceedings SIMS 2008 in Oslo, October 7-8, 2008 / [ed] Bernt Lie, 2008Conference paper (Refereed)
    Abstract [en]

    We have had a strong mechanism for interaction between power production companies and the power trading/supplier companies for a number of years by now. In the future we can expect new types of more interactive communications between single customers and groups of customers towards the energy market companies. We can expect a stronger request side from customers to buy only green energy, only nuclear etc.

    Power (kW) will be a part aside of energy (kWh) and there will be new possibilities to buy energy when it is as cheap as possible. This may include new applications like charging batteries for your car when the electricity price is low. Differentiation of price may be not only as a direct function of time, but also energy availability like when it is windy, as wind power becomes a major part of many energy systems. Energy storage will be more important and perhaps we will get new possibilities to buy shares in central energy storages like you buy space at servers for your web-pages etc.

    Other type of functions may develop as a result of the introduction of individual metering of first electricity and later on hot water and temperature. By metering the individual consumption and invoicing just what has been spent, you will have a driving force also to do actions like shutting of high demand functions like “infra-heating”, “large screen TV” and similar, when other usages are on, and the price is high. We expect displays with interaction possibilities in all homes, where you can see your consumption and pricing information.

    These new type of systems will put new demands on both hardware for supply and software to handle the services/functions. As part of developing this, mathematical modelling of the systems and tests with simulators will be an important tool. Also new soft ware functions will be developed to support the actual services, like simulators giving information on how different actions you make as a user will influence your energy consumption in the future, both short term and more long term. For the more long term case, new investments in new hardware and software may be proposed and evaluated for you in both technical and economic terms.

    In this paper the system aspects including the costs is analysed through a simulation model. This includes the physical system as well as the user behaviour and possible effects of different price models, like a combination of kW and kWh. The effect on the users, the distributors and the power producers are evaluated.

  • 216.
    Vassileva, Iana
    et al.
    Mälardalen University, School of Business, Society and Engineering.
    Campillo, Javier
    Mälardalen University, School of Business, Society and Engineering.
    Dahlquist, Erik
    Increasing energy efficiency in low- income Swedish households through targeting awareness and behavior2013Conference paper (Refereed)
  • 217.
    Vassileva, Iana
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Campillo, Javier
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Wallin, Fredrik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    COMPARING THE CHARACTERISTICS OF DIFFERENT HIGH-INCOME HOUSEHOLDS IN ORDER TO IMPROVE ENERGY AWARENESS STRATEGIES2013Conference paper (Refereed)
  • 218.
    Vassileva, Iana
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Analysis of the influence of individual payment and tenants’ behavior on electricity consumption2010In: Conference proceedings 3rd International Scientific Conference on“Energy systems with IT” at Alvsjö fair in association with Energitinget March 16-17 2010., 2010Conference paper (Refereed)
  • 219.
    Vassileva, Iana
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Economical savings through lowering energy consumption in rented apartments: A case study in Västerås area2008In: Journal of Numerical and Applied Mathematics, ISSN 0868-6912, Vol. 96, no 1, p. 234-245Article in journal (Refereed)
    Abstract [en]

    Electricity and heat consumption were recorded for 24 apartments distributed in two buildings over a 2-year monitoring period. The consumption of different built-form groups (according to their floor area) is also investigated. In general buildings located in Västerås (Sweden) are characterized by the fact that energy costs are included in the rent and therefore tenants are not encouraged to save energy. Data obtained from the company renting out apartments, Mimer was analyzed in order to find out if there were any general trends describing the connection between energy use, the level of surface area and number of rooms, or the main driving force behind is the individual behaviour of tenants (since in these two buildings tenants pay themselves for the total energy consumption). It was found that the analysis by various parameters is as important as analysis of each individual apartment. Some tendencies were well defined such as increase of total electricity consumption during the winter months and lowest both electricity and hot water consumption in June and July. The number of rooms at equal surface area could not be accepted as a pattern of electricity consumption. Bearing in mind the interactive contact between the energy distributor companies and the respective tenants, a positive trend of lowering both studied parameters was well manifested when a comparison of data obtained during 2005 and 2006 was carried out. This study shows that the economical savings for both buildings for the period 2005-2006, are 8000 SEK for electricity and 2300 SEK for district heating. Further improvements in company-tenants relations in terms of more detailed mutual information would probably change tenants’ behaviour thus improving energy and economic saving tendency in both buildings. We strongly believe that similar research approaches should be further included in larger programmes aimed at developing efficiency measures to quantify energy savings advantages in economic terms. Therefore, it would be economically reasonable for owners and housing promoters to invest in energy-saving measures.

     

  • 220.
    Vassileva, Iana
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Campillo, Javier
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    The citizens' role in energy smart city development2016In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 88, p. 200-204Article in journal (Refereed)
    Abstract [en]

    The purpose of the paper was to investigate citizens' experiences and feedback related to strategies and products targeting energy savings and emission reduction in Sweden. Survey results presented in this paper showed that consumers did not make use of the advantages of the smart meters and that tailored feedback is necessary to help them save electricity. Moreover, despite the high satisfaction levels among electric vehicles owners, additional improvements (e.g. reliable charging infrastructure) and information are needed to attract potential owners. Effective information dissemination is thus a crucial part of increasing urban sustainability. 

  • 221.
    Vassileva, Iana
    et al.
    Mälardalen University, School of Business, Society and Engineering.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering.
    Lundh, Magdalena
    Efficiency of interactive information on energy consumption in households in Sweden2009Conference paper (Refereed)
    Abstract [en]

    Measurements of electricity, hot water consumption and indoor temperatures were carried out in 24 apartments during the years 2005 and 2006. Buildings located in Västerås (Sweden) are characterized by the fact that energy costs are included in the rent. Data obtained from the company renting out apartments, “MIMER”, was analyzed in order to find out if there were any general trends describing the connection between the level of surface area, number of rooms, or the main driving force behind is the individual behaviour of tenants. It was found that the analysis by various parameters is as important as the analysis of each individual apartment. Some tendencies were well defined such as increase of total electricity consumption during the winter months and lowest both electricity and hot water consumption in June and July. The number of rooms at equal surface area could not be accepted as a pattern of electricity consumption. Bearing in mind the interactive contact between the energy company and the respective tenants, a positive trend of lowering both studied parameters was well manifested when a comparison of data obtained during 2005 and 2006 was carried out. Our results confirmed the importance of indoor temperature measurements as well. Further improvements in company-tenants relations in terms of more detailed mutual information would probably change tenants’ behaviour thus improving energy saving tendency in both buildings.

  • 222.
    Vassileva, Iana
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology. Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Wallin, Fredrik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Campillo, Javier
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Energy consumption feedback devices’ impact evaluation on domestic energy use2013In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 106, p. 314-320Article in journal (Refereed)
    Abstract [en]

    Household energy accounts for one of the major contributors to the countries energy balances. It has been shown, that an effective way to achieve energy saving in that sector, is by providing consumers with information and feedback. This measure increases home inhabitants’ awareness that leads to behavioral changes, and could help reduce energy consumption between 15% and 25% in some cases. Inhabitants’ energy use awareness is also crucial for the success of demand response programs; one of the most important features of smart-grid adoption for the current and upcoming smart cities.

    The effects of different feedback strategies and information devices in households located in different cities in Sweden have been evaluated in this paper, since the impact on users’ behavior of this feedback information vary depending on the way it is provided.

    Mobile text messages (SMSs) and digital displays placed in the building’s common areas did not cause any noticeable behavioral changes, while the use of a TV channel and personal in-home displays were the most popular devices amongst households with high incomes.

    This paper concluded that even though feedback helped reduce domestic energy consumption and induce behavioral changes, it only reaches the consumers interested in it. It is important therefore to provide customized information to the consumer and select precise feedback tools for specific household groups. Special attention should be paid to increasing the energy consumption awareness in households with low income levels.

  • 223.
    Vassileva, Iana
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Odlare, Monica
    Mälardalen University, School of Business, Society and Engineering.
    Wallin, Fredrik
    Mälardalen University, School of Business, Society and Engineering.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering.
    The impact of consumers' feedback preferences on domestic electricity consumption2012In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 93, no SI, p. 575-582Article in journal (Refereed)
    Abstract [en]

    Despite all initiatives introduced for maximizing energy savings domestic energy consumption is in constant increase. However, very little investigation has been carried out on the integration of household' consumption trends, the parameters influencing them and the characteristics of the provided feedback. 2000 Swedish households were included in this study. Electricity consumption data for apartments and houses has been analyzed for a 4 year period as well as possible household socio-economic factors affecting it. The data has been further compared to other households located in different cities in Sweden. The effects of the different ways of presenting feedback used for the different households groups have also been evaluated. From the results obtained from the questionnaire used, several households' characteristics were proposed together with consumers' preferences to be considered during the development of feedback. Web based feedback resulted in being the most effective (when compared to display and bills), achieving electricity savings of approximately 15% within households that visited the web-site. The monthly income is amongst the most influential factors determining electricity consumption although only in high and low income groups

  • 224.
    Vassileva, Iana
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Wallin, Fredrik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Analytical comparison between electricity consumption and behavior characteristics of Swedish households in rented apartments2012In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 90, no SI, p. 182-188Article in journal (Refereed)
    Abstract [en]

    Sufficient data of electricity consumption during large periods of time are accumulated and analyzed in order to develop appropriate electricity-saving measures. An important first step is to analyze and identify buildings/households that have an energy saving potential. In this work an evaluation of monthly electricity consumption data was conducted in identical buildings in the city of Vasteras in Sweden. Different behavioral consumption profiles have been analyzed using information from two sources: technical data of electricity consumption and behavioral parameters for each household obtained from a questionnaire survey. The questionnaire was formed by three groups of questions which concerned residents' characteristics, type and usage of electrical appliances, and attitudes towards energy consumption. The results show that electricity consumption profile of individual household can be mostly related to a given parameter. For example, the total household's income resulted one of the important factors determining the consumer behavior and as a rule is related to higher electricity consumption. Another important conclusion of our questionnaire-based analysis is the necessity for more detailed information about household/tenants behavior specifying the technical features of appliances for a given household.

  • 225.
    Vassileva, Iana
    et al.
    Mälardalen University, School of Business, Society and Engineering.
    Wallin, Fredrik
    Mälardalen University, School of Business, Society and Engineering.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering.
    Consumption patterns today and tomorrow with respect to energy and how the energy system will be affected by this2009Conference paper (Other (popular science, discussion, etc.))
    Abstract [en]

    Nowadays we can see a high consumption of energy for transportations and in offices, for lightning, ventilation, computers etc. We also have a significant household consumption of electricity. However, in the future we can expect a trend where the houses are consuming significantly less energy for heating, with thicker insulation, four glass windows and better constructions giving less unwanted diffusion of heat due to leakages. In Vasteras city, the trend has been a reduced heat demand of approximately 1.5-2 % per year during the last 25 years. This means that the district heating sink has been reduced by 30 %. This makes district heating less competitive as the reduced heat demand give lower potential for electricity production in co-generation. Similar adequate measures should be performed in the field of household electricity consumption. As a first step and what is the aim of this report, sufficient data of electricity consumption along large periods of time should be accumulated and carefully analyzed in order to develop appropriate further electricity-saving measures. Data included in this study was collected from two buildings in Vasteras area over several years (from 2004 until 2008) and further comparatively analyzed and discussed bearing also in mind some complementary information gathered in form of a paper based questionnaires. The results of our study indicate that it is important to change patterns for ‘consumption’ of electricity. More emphasis should be made on two main research directions: a) detailed analysis of tenants’ consumption behavior; b) development of appropriate information tools that will offer the consumers a possibility to both get information about the electricity consumption in an easily accessible way, e.g. by displays with information that is easy to catch. 

  • 226.
    Vassileva, Iana
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Wallin, Fredrik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Understanding energy consumption behavior for future demand response strategy development2012In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 46, no 1, p. 94-100Article in journal (Refereed)
    Abstract [en]

    Encouraging consumers to use less electricity through information is essential for sustainable use of energy and demand response is indeed a key component of the smart grids concept. The aim with this study is to understand differences between consumer categories and what this could mean e.g. to develop effective demand response measures. In-depth analyses of answers from a questionnaire sent out to 2000 households, contribute to a better understanding of Swedish households' energy related behavior. The households have been provided with a web-site enabling them to check their daily electricity consumption compared to previous months/years and even get advice and tips on how to reduce electricity consumption. The results show clear differences in the response rates from different type of residence, different income areas of the city and in the most preferred ways of receiving information-feedback. The web based feedback, provided by the local energy company, received more visits (and more frequently) from respondents living in houses than from apartments.

    The analysis of the answers raises questions about the effectiveness of using only one tool of providing energy consumption information to the customers (web-site, in this case) and stresses the importance of applying an individual approach to different energy users.

  • 227.
    Vassileva, Iana
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Wallin, Fredrik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Roots, Peter
    Mälardalen University, School of Sustainable Development of Society and Technology.
    The relation between consumption of electricity and hot water and different consumer variables2010Conference paper (Other (popular science, discussion, etc.))
    Abstract [en]

    24 apartments of different size in Vasteras, Sweden were thoroughly investigated with respect to consumption of electricity/hot water during a period of six/two years, respectively. Questionnaires were answered by 19 of the 24 households, and correlations between their energy consumption and behaviour were determined. A total of 40 tenants occupied the apartments (mostly two persons per apartment), and no single individual was below 18 years old. Despite the similar conditions significantly large differences (up to ten times) were registered between households with the same apartment size and number of inhabitants for both hot water and electricity. Consumption patterns are presented in this work as well as how different behaviour variables determine energy saving potential. Analyzing the results, it can be concluded that the most important variable to explain the difference in energy consumption was the household income. Families with high income had high consumption while those with low income stayed at home much longer time every day, were watching TV more, but still consumed less. On the other hand, behavioural characteristics of electricity consumers are not applicable to the respective consumption of hot water. Therefore, different approach should be applied when developing saving strategies for different energy-derived products.

     

  • 228.
    Vassileva, Iana
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Wallin, Fredrik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Ding, Yong
    Research Group of Pervasive Computing Systems (TecO), Karlsruhe Institute of Technology .
    Beigl, Michael
    Research Group of Pervasive Computing Systems (TecO), Karlsruhe Institute of Technology .
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Household indicators for developing innovative feedback technologies2011Conference paper (Refereed)
    Abstract [en]

    Numerous studies have shown that households' consumption is an important part of the total energy consumed in different countries. However, there is very little work done on finding appropriate strategies of giving households' effective feedback on their energy consumption. This study analyzes several indicators that could be considered before analyzing residential overall energy consumption and providing information, feedback, or developing demand-response measures. A questionnaire sent out to 2000 households having 33% response rate shows that the total households' income and characteristics, occupants' age and users' energy attitudes and interest are the key components designing relevant energy information strategies

  • 229.
    Wallin, Fredrik
    et al.
    Mälardalen University, Department of Public Technology.
    Bartusch, Cajsa
    Mälardalen University, Department of Public Technology.
    Thorin, Eva
    Mälardalen University, Department of Public Technology.
    Bäckström, Tobias
    Smedjebacken Energi Nät AB.
    Dahlquist, Erik
    Mälardalen University, Department of Public Technology.
    The Use of Automatic Meter Readings for a Demand-Based Tariff2005In: Proceedings of the 2005 IEEE/PES Transmission and Distribution Conference & Exhibition: Asia and Pacific, 2005, p. 1-6Conference paper (Refereed)
    Abstract [en]

    A determining factor for a successful implementation of a demand-based pricing model or control strategy in electricity markets is not only the effects of peak load management, but also the financial consequences for the utility operator and the end customer. In this economic modelling a subset of 460 residential customers has been implemented in a software tool analysing the economic outcome of three different tariffs. Two demand-based tariffs were investigated and compared with a traditional energy-based tariff. The demand-based tariffs transform the flat income curve into a more complex, due to a stronger economic dependency to the system peak loads. The demand-based tariffs move the revenues to the high-peak period, November – March, and the utility operator gains a good matching between system peaks and distribution of incomes.

  • 230.
    Wallin, Fredrik
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Bartusch, Cajsa
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Thorin, Eva
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Important parameters for prediction of power loads - a bottom-up approach utilizing measurements from an automatic meter reading system2007In: IEEE PES Power Africa 2007 Conference and Exposition, 2007, p. 1-7Conference paper (Refereed)
  • 231.
    Wallin, Fredrik
    et al.
    Mälardalen University, Department of Public Technology.
    Dahlquist, Erik
    Mälardalen University, Department of Public Technology.
    A Web-Based Dynamic Simulator For Applications In Process Industry And For Education.2002In: Proceedings of the 43rd Conference on Simulation and Modelling: SIMS 2002, 2002, p. 151-158Conference paper (Refereed)
    Abstract [en]

    This paper presents a project with a purpose to develop an energy process simulator with a Web-based interface. The advantage with a Web-based interface is that the user can access simulation tools with only a Web browser. The cost for any organisation would also be reduced due to smaller fees and less maintenance time as only a central server needs to be updated. The system architecture has been divided into three major parts; Graphical User Interface (GUI), storage of data and calculating applications. This object-oriented design has shown to be very useful due to its high flexibility. Two different pplications are described in the paper; one energy model used to simulate an energy process and one system with remote electricity data collection (both power and energy) and processing, both displaying the results in a Web-based GUI. The two applications have recently been evaluated with a promising result and will therefore form the basis for future research projects.

  • 232.
    Wallin, Fredrik
    et al.
    Mälardalen University, Department of Public Technology.
    Dahlquist, Erik
    Mälardalen University, Department of Public Technology.
    Ekwall, Håkan
    ABB Industry, Västerås, Sweden.
    Dynamic simulators for process control and optimization as well as for operator training in pulp and paper industry2002In: Proceedings of the 43rd Conference on Simulation and Modelling: SIMS 2002, 2002Conference paper (Other (popular science, discussion, etc.))
    Abstract [en]

    By using a dynamic physical model, that is adapted to real process data, robust mathematical process models can be created. By doing this it is possible to build in process know how from many different sources, and also to include factors, that are not easy to measure. From the dynamic model a training simulator can be made. From the dynamic model it may also be possible to do a model reduction to get an MPC, a Model Predictive Control. Data reconciliation is needed, to keep control of the measurements of all kind. A decision support system keeps control over the process status, to support operators. The production is also optimized at several levels. These functions may also be achieved by using principally the same mathematical models and algorithms.

  • 233.
    Wallin, Fredrik
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dotzauer, Erik
    Fortum.
    Thorin, Eva
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Automatic meter reading provides opportunities for new prognosis and simulation methods2007In: 2007 IEEE Lausanne POWERTECH, Proceedings, 2007, p. 2006-2011Conference paper (Refereed)
    Abstract [en]

    The use of top-down models, for load forecasting purposes, has been the dominating method over the last decades. However, there is now a discussion regarding the performance of the top-down models, e.g. in situations with unusual weather conditions due to the lack of historical data. This paper considers an alternative bottom-up approach with a stronger relation to the laws of physics. Electricity companies in Sweden are installing automatic meter reading systems for their customers, and using the consumption data gives new possibilities when adapting the modeling parameters in a bottom-up model for each single customer. A method for analyzing individual consumption series is suggested, where different periods in time is used to divide and identify different parts of the electricity load; base load, heat load and household loads. A review of previous work is presented, and suggestions how to link the load analysis to construction parameters for an individual building is proposed.

  • 234.
    Wallin, Fredrik
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Thorin, Eva
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Kvarnström, Andreas
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Kvarnström, Johan
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    A method to refine electricity consumption data from automatic meter reading systems2006In: Proceedings of the 2006 International Conference on Power System Technology, IEEE , 2006, p. 1-6Conference paper (Refereed)
    Abstract [en]

    In this work data from an AMR system delivering consumption data on a daily basis with an aggregated electricity consumption post combined with a maximum peak load within the period has been utilized. The paper suggests a method to create individual hour based daily consumption profiles and to increase the knowledge of the aggregated consumption patterns over the day. As a validation the method has been applied on rearranged data from an AMR system providing hour based metering series to regenerate the same consumption series. Implementing the method can provide consumption series that can be used to increase the accuracy e.g. when forecasting the electricity consumption for individual customers. The created consumption series can also be a valuable resource when estimating aggregated hour based profiles for different areas using a bottom-up approach.

  • 235.
    Wang, C.
    et al.
    Tianjin University, Tianjin, China.
    Yan, Jinyue
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. KTH, Stockholm, Sweden.
    Marnay, C.
    Lawrence Berkeley National Laboratory, CA, United States.
    Djilali, N.
    University of Victoria, Victoria, Canada.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Wu, J.
    Cardiff University, Cardiff, United Kingdom.
    Jia, H.
    Tianjin University, Tianjin, China.
    Distributed Energy and Microgrids (DEM)2018In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 210, p. 685-689Article in journal (Refereed)
  • 236.
    Wang, Weilong
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Hu, Yukun
    Royal Institute of Technology, Stockholm, Sweden.
    Yan, Jinyue
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Nyström, Jenny
    Eskilstuna Energi och Miljo AB, Eskilstuna, Sweden.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Combined heat and power plant integrated with mobilized thermal energy storage (M-TES) system2010In: Frontiers of Energy and Power Engineering in China, ISSN 1673-7393, Vol. 4, no 4, p. 469-474Article in journal (Refereed)
    Abstract [en]

    Energy consumption for space heating and hot tap water in residential and service sectors accounts for one third of total energy utilization in Sweden. District heating (DH) has been used for heat supply to areas with high energy demand. However, there are still a lot of detached houses and sparse areas with no connection to a DH network where electrical heating or oil/pellet boilers are used to meet heat demand. Sometimes, extending the existing DH network to those spare areas is not economically feasible because of the small heat demands and the large investment. Mobilized thermal energy storage (M-TES) system is an alternative way to supply heat for detached buildings or sparse areas by using industrial heat. In this paper, integration of a combined heat and power (CHP) plant and an M-TES system is analyzed. The impacts of four options of the integrated system are discussed including the power and heat output in the CHP plant, as well as the performance of M-TES system.

  • 237.
    Wang, Weilong
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Yan, Jinyue
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Thermal performance of the mobilized thermal energy storage system2011Conference paper (Refereed)
    Abstract [en]

    A direct-contact mobilized thermal energy storage (M-TES) system with high heat density and heat transfer rate has been exploited to transport industrial heat for distributed users. In this paper, a lab-scale experimental setup has been built consisting of a direct-contact thermal energy storage (TES) container, oil/water tank, electrical boiler, oil/water pump and plate heat exchanger. Erythritol was chosen to work as an organic phase change material (PCM) due to its large heat density, suitable melting point (118oC) for industrial heat recovery, and non toxic and corrosive. Heat transfer oil (HTO) served as a heat transfer medium to carry and transfer heat. The theoretical heat capacity of the TES container is 13.1 kWh with 74 kg of Erythritol and 42 kg of HTO. In the charging process, electrical boiler heated HTO first, and then HTO was pumped into the bottom of the TES container to melt Erythritol directly. In the discharging process, heat was transferred to the cooling water through a plate heat exchanger. Results show that, the sub-cooling problem of Erythritol, which was found in the static experiments, was totally solved by dynamic heat exchange between Erythritol and HTO. During the whole process, the two liquid phases (oil and melted Erythritol) were separated clearly due to the big difference of their densities, and meanwhile a foam layer was also observed between the two sectors. In the charging process, the higher the flow rate of HTO, the less the charging time was needed, which resulted in the lower charging heat consumption. In the discharging process, the maximum heat of 10.6 kWh was released with the HTO flow rate of 12.5 l/min, which accounted for 80.9 % of the theoretical heat capacity of the TES container.

  • 238.
    Weidl, Galia
    et al.
    Mälardalen University, Department of Energy.
    Dahlquist, Erik
    Root Cause Analysis for Pulp and Paper ApplicationsManuscript (Other academic)
  • 239.
    Weidl, Galia
    et al.
    Mälardalen University, Department of Energy.
    Madsen, Anders
    Dahlquist, Erik
    Bayesian Networks for Root Cause Analysis in process operationManuscript (Other academic)
  • 240.
    Weidl, Galia
    et al.
    Mälardalen University, Department of Energy.
    Madsen, Anders
    Dahlquist, Erik
    Condition Monitoring, Root Cause Analysis and Decision Support on Urgency of ActionsManuscript (Other academic)
  • 241.
    Weidl, Galia
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology. University of Stuttgart.
    Madsen, Anders
    HUGIN Expert A/S, Denmark.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Decision support on complex industrial process operation2008In: Bayesian networks: Apractical guide to applications / [ed] Olivier Pourret, Patrik Naim and Bruce Marcot, Chichester, UK: John Wiley & sons , 2008, 1st, p. 311-328Chapter in book (Other (popular science, discussion, etc.))
    Abstract [en]

    A practical guide to applications of Bayesian Networks. Theoretical aspects of BNs together with a number of applications in different areas like sensor validation, process industry applications, forensic science, terrorism risk management, robotics risk management, classification of wines, pavement and bridge management, and enhancing human cognition.

  • 242.
    Weidl, Galia
    et al.
    Mälardalen University, Department of Energy.
    Wollmar, G
    Dahlquist, Erik
    Adaptive Root Cause Analysis under Uncertainties in Industrial Process OperationManuscript (Other academic)
  • 243. Wen, Z.
    et al.
    Yu, X.
    Tu, S-T
    Yan, Jinyue
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Intensification of transesterification for synthesis of biodielsel using micro channel reactor2008Conference paper (Refereed)
  • 244.
    Wen, Zhenzhong
    et al.
    School of Mechanical and Power Engineering, East China University of Science and Technology.
    Yu, Xinhai
    School of Mechanical and Power Engineering, East China University of Science and Technology.
    Tu, Shan-Tung
    School of Mechanical and Power Engineering, East China University of Science and Technology.
    Yan, Jinyue
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Intensification of biodiesel synthesis using zigzag micro-channel reactors2009In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 100, no 12, p. 3054-3060Article in journal (Refereed)
    Abstract [en]

    Zigzag micro-channel reactors have been fabricated and used for continuous alkali-catalyzed biodiesel synthesis. The influences of the main geometric parameters on the performance of the micro-channel reactors were experimentally studied. It has been found that the zigzag micro-channel reactor with smaller channel size and more turns produces smaller droplets which result in higher efficiency of biodiesel synthesis. Compared to conventional stirred reactors, the time for high methyl ester conversion can be shortened significantly with the methyl ester yield of 99.5% at the residence time of only 28 s by using the optimized zigzag micro-channel reactor, which also exhibits less energy consumption for the same amount of biodiesel during biodiesel synthesis. The results indicate that zigzag micro-channel reactors can be designed as compact and mini-fuel processing plant for distributive applications.

  • 245.
    Wen, Zhenzhong
    et al.
    School of Mechanical and Power Engineering, East China University of Science and Technology.
    Yu, Xinhai
    School of Mechanical and Power Engineering, East China University of Science and Technology.
    Tu, Shan-Tung
    School of Mechanical and Power Engineering, East China University of Science and Technology.
    Yan, Jinyue
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Synthesis of biodiesel from vegetable oil with methanol catalyzed by Li-doped magnesium oxide catalysts2010In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 87, no 3, p. 743-748Article in journal (Refereed)
    Abstract [en]

    The preparation of a Li-doped MgO for biodiesel synthesis has been investigated by optimizing the catalyst composition and calcination temperatures. The results show that the formation of strong base sites is particularly promoted by the addition of Li, thus resulting in an increase of the biodiesel synthesis. The catalyst with the Li/Mg molar ratio of 0.08 and calcination temperature of 823 K exhibits the best performance. The biodiesel conversion decreases with further increasing Li/Mg molar ratio above 0.08, which is most likely attributed to the separated lithium hydroxide formed by excess Li ions and a concomitant decrease of BET values. In addition, the effects of methanol/oil molar ratio, reaction time, catalyst amount, and catalyst stability were also investigated for the optimized Li-doped MgO. The metal leaching from the Li-doped MgO catalysts was detected, indicating more studies are needed to stabilize the catalysts for its application in the large-scale biodiesel production facilities.

  • 246.
    Widarsson, Björn
    et al.
    Mälardalen University, Department of Public Technology.
    Karlsson, Christer
    Mälardalen University, Department of Public Technology.
    Dahlquist, Erik
    Mälardalen University, Department of Public Technology.
    Bayesian Network for Decision Support on Soot Blowing Superheaters in a Biomass Fuelled Boiler2004In: 2004 International Conference on Probabilistic Methods Applied to Power Systems, 2004, p. 212-217Conference paper (Other academic)
    Abstract [en]

    In a process for combined heat and power generation there is a need for fault detection, decision support and risk assessment to prevent operational disturbances and reduction in performance. A method to achieve decision support is to use Bayesian networks, where knowledge about the process is combined with operational experience. The network covers the convectional superheaters in the flue gas train, which is a major problem domain in biomass-fuelled boilers. The superheaters are exposed to fouling from flue gases. Fouling reduces the heat transfer and result in a decreased power plant performance. The Bayesian network is constructed to give decision support on preventive action to reduce abnormal fouling. Validation of the Bayesian network show that the prediction of hard fouling works well under uncertainty.

  • 247.
    Widén, J.
    et al.
    The Ångström Laboratory, Uppsala, Sweden.
    Lundh, M.
    The Ångström Laboratory, Uppsala, Sweden.
    Vassileva, Iana
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Ellegård, K.
    Linköping University, Sweden.
    Wäckelgård, E.
    The Ångström Laboratory, Uppsala, Sweden.
    Constructing load profiles for household electricity and hot water from time-use data: Modelling approach and validation2009In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 41, no 7, p. 753-768Article in journal (Refereed)
    Abstract [en]

    Time-use data, describing in detail the everyday life of household members as high-resolved activity sequences, have a largely unrealized potential of contributing to domestic energy demand modelling. A model for computation of daily electricity and hot-water demand profiles from time-use data was developed, using simple conversion schemes, mean appliance and water-tap data and general daylight availability distributions. Validation against detailed, end-use specific electricity measurements in a small sample of households reveals that the model for household electricity reproduces hourly load patterns with preservation of important qualitative features. The output from the model, when applied to a large data set of time use in Sweden, also shows correspondence to aggregate profiles for both household electricity and hot water from recent Swedish measurement surveys. Deviations on individual household level are predominantly due to occasionally ill-reported time-use data and on aggregate population level due to slightly non-representative samples. Future uses and developments are identified and it is suggested that modelling energy use from time-use data could be an alternative, or a complement, to energy demand measurements in households.

  • 248.
    Yan, Jinyue
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Chou, S. K.
    National University of Singapore, Singapore.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Innovative research for sustainable energy systems2015In: International Journal of Green Energy, ISSN 1543-5075, E-ISSN 1543-5083, Vol. 12, no 3, p. 191-191Article in journal (Other academic)
  • 249.
    Yan, Jinyue
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Chou, S.K.
    National University Singapor (NUS).
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology. Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Special issue Recent Progress in Sustainable energy systems2013In: International journal of energy research (Print), ISSN 0363-907X, E-ISSN 1099-114X, Vol. 37, no 15, p. 1937-2028Article in journal (Refereed)
    Abstract [en]

    Guest editors for special issue from the International Conference on Applied Energy in Souzhou, July 2012. The papers covers different areas of Applied energy and with special focus on Sustainable energy systems

  • 250.
    Yan, Jinyue
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Editorial for Special Issue of the Third International Green Energy Conference, Västerås, Sweden, June 18-20, 2007 at Applied Energy2009In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 86, no 2, p. 125-125Article in journal (Refereed)
23456 201 - 250 of 257
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