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  • 1.
    Aasa, Ulrika
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, CBF. University of Gävle, Centre for Musculoskeletal Research. Department of Community Medicine and Rehabilitation, Physiotherapy, University of Umeå, Sweden.
    Jensen, B. R.
    Sandfeld, J.
    Richter, Hans
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, CBF. University of Gävle, Centre for Musculoskeletal Research.
    Lyskov, Eugene
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, CBF. University of Gävle, Centre for Musculoskeletal Research.
    Crenshaw, Albert G.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, CBF. University of Gävle, Centre for Musculoskeletal Research.
    The impact of object size and precision demands on fatigue during computer mouse use2011In: Advances in Physiotherapy, ISSN 1403-8196, E-ISSN 1651-1948, Vol. 13, no 3, p. 118-127Article in journal (Refereed)
    Abstract [en]

    Prolonged computer use, especially if fatigue ensues, is associated with visual and musculoskeletal symptoms. The aim was to determine the time-course of perceived fatigue in the wrist, forearm, shoulder and eyes during a 60-min mouse task (painting rectangles), and whether object size and/or mouse use demands were of influence. Also, we investigated performance (number of rectangles painted), and whether perceived fatigue was paralleled by local muscle fatigue or tissue oxygenation. Ten women performed the task for three conditions (crossover design). At condition 1, rectangles were 45 × 25 mm, square paint cursor size 1.3 × 1.3 mm, and mousepointer movement ratio 1:26. At condition 2, the same cursor size and mousepointer movement ratio was used, but rectangles were smaller. At condition 3, the smaller rectangles were used, but the cursor size was also smaller and mousepointer movement ratio was 1:8. The results showed increased self-reported fatigue over time, with the observed increase greater for the eyes, but no change in physiological responses. Condition 2 resulted in higher performance and increased eye fatigue. Perceived fatigue in the muscles or physiological responses did not differ between conditions. In conclusion, computer work tasks imposing high visual and motor demands, and with high performance, seemed to have an influence on eye fatigue. 

  • 2.
    Abbas, Wasim
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Asghar, Imran
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    The Role of Leadership In Organizatinal Change: Relating the successful Organizational Change with Visionary and Innovative Leadership2010Independent thesis Advanced level (degree of Master (One Year)), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    The globalization has converted the world into a small global village; a village in which there is an ever high stream of contentions and competitions between organizations. In this scenario the most effective and beneficial maneuver for any organization is to create innovative ways in conducting business. This thesis deals with the role of leadership in the phenomena of organizational change and innovation. The leader as a person in charge or as a change agent can manage an organization or the process of organizational change more effectively and successfully if h/she is capable and competent. Rapid technological advancements, high expectations of customers, and ever changing market situations have compelled organizations to incessantly reassess and reevaluate how they work and to understand, adopt and implement changes in their business model in response of changing trends. Organizational change is a demand of the day, and needed for organizations to survive. Organizations now a days, well understand the importance of the matter, and are serious to prepare themselves not only the current, but also for the future trends to get the level of sustainable success, but Along with all of its implications and importance the process of organizational change is also a very complex and challenging.  Research shows that 70 percent of organizational changes fail to get their goals. As leadership has a central role in evolution and cultivating an organization, the process of organizational change demands a very effective and highly competent leadership that is well capable to perceive the most desirable shape of an organization and address the issue of organizational change in most appropriate way. The analysis of literature reviewed and the results of real life cases of organizations which are studied for this thesis shows, that a leadership with the competencies of “Vision” and “Innovative Approach” along with other characteristics can prove more effective to conclude the complex phenomena of organizational change with success. Further the successful organizational change can leads to innovation for organization, which is the key of long term success and sustainability. This thesis as a result proposed a model which is derived from the leadership competencies, organizational change, and sustainable success and innovation literature. This model expresses relationship between successful organizational change and leadership on the basis of h/her characteristics, which are ‘Vision” and “Innovative Approach”. With the help of proposed model this relationship can be viewed graphically.

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  • 3.
    Abeywardana, Asela Janaka
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Solar - Biomass hybrid system for process heat supply in medium scale hotels in Sri Lanka2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This study aimed at evaluating and demonstrating the feasibility of using Concentrated Solar Thermal technology combined with biomass energy technology as a hybrid renewable energy system to supply the process heat requirements in small scale industries in Sri Lanka. Particularly, the focus was to apply the concept to the expanding hotel industry, for covering the thermal energy demand of a medium scale hotel.

    Solar modules utilize the rooftop area of the building to a valuable application. Linear Fresnel type of solar concentrator is selected considering the requirement of the application and the simplicity of fabrication and installation compared to other technologies. Subsequently, a wood-fired boiler is deployed as the steam generator as well as the balancing power source to recover the effects due to the seasonal variations in solar energy. Bioenergy, so far being the largest primary energy supply in the country, has a good potential for further growth in industrial applications like small hotels. 

    When a hotel with about 200-guests capacity and annual average occupancy of 65% is considered, the total annual CO2 saving is accounted as 207 tons compared with an entirely fossil fuel (diesel) fired boiler system. The annual operational cost saving is around $ 40,000 and the simple payback period is within 3-4 years. The proposed hybrid system can generate additional 26 employment opportunities in the proximity of the site location area.  

    This solar-biomass hybrid concept mitigates the weaknesses associated with these renewable technologies when employed separately. The system has been designed in such a way that the total heat demand of hot water and process steam supply is managed by renewable energy alone. It is thus a self-sustainable, non-conventional, renewable energy system. This concept can be stretched to other critical medium temperature applications like for example absorption refrigeration. The system is applicable to many other industries in the country where space requirement is available, solar irradiance is rich and a solid biomass supply is assured.    

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  • 4.
    Abhary, Kazem
    et al.
    University of South Australia, Adelaide, Australia.
    Kovacic, Zlatko
    The Open Polytechnic of New Zealand, Lower Hutt, New Zealand.
    Lundberg, Sven-Erik
    Association of International Roll Pass Designers and Rolling Mill Engineers, Dortmund, Germany.
    Narayanan, Ramadas
    Central Queensland University, Bundaberg, Australia.
    Spuzic, Sead
    University of South Australia, Adelaide, Australia.
    The application of a hybrid algorithm to roll pass design2015In: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 79, no 5-8, p. 1063-1070Article in journal (Refereed)
    Abstract [en]

    Human–computer interface was utilized to amplify the power of a hybrid algorithm that combines fuzzy logic, regression analysis, and non-linear optimization to extract knowledge from a roll pass design database. This strategy is applied to grooves with vertical and horizontal symmetry which are employed in initial passes to roll a broad range of steel products. The results presented here from the case study are both statistically significant and valid from the viewpoint of roll pass design theory. © 2015, Springer-Verlag London.

  • 5.
    Abid, Muhammad
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Industrial economics. University of Gävle, Center for Logistics and Innovative Production. KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management.
    Global Supply Chain Design: Exploring configurational and coordination factors2015Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis addresses the topic of global supply chain design. One major challenge concerns how to manage the tension between separation and integration pertaining to the localization of business activities. In this regard Ferdows (2008) worked to create two new production network models (rooted production network and footloose production network). Earlier studies have highlighted the choices that are involved in the network of facilities but lack in providing a comprehensive picture in terms of both configurational and coordination factors that govern the design of global supply chain. There is a need for a conceptual model where factors affecting the design process of a global supply chain can be applied. Two main research questions have been addressed in this study. First, exploring and identifying the factors affecting global supply chain design. Second, investigating the factors that influence the position on the spectrum of rooted and footloose supply chain design.      

    A literature review analysis and multi-case studies have been performed for this study in order to explore the factors. The companies were selected in order to reflect upon the two types of network, i.e., rooted and footloose. The primary data were selected through interviews with the managers.

    This study highlighted that there are many factors that affect configurational and coordination decision areas within a global supply chain. This study categorized the factors and the configurational/coordination decision areas with two main competitive priorities, i.e., cost and differentiation in the form of a “conceptual model.” The study also highlighted the factors in a matrix, which showed their position on the spectrum of rooted and footloose network configurations. For instance, the coordination factors that drive towards a footloose network include: high orchestration capabilities, need access to new technology and knowledge, proximity to suppliers, etc. The configurational factors that drive towards a rooted network include: economic stability, proximity to market, concerns for sustainability issues, high transportation cost, need for high proximity between key functions, need for intellectual property rights protection, etc.

  • 6.
    Abid, Muhammad
    KTH, Skolan för industriell teknik och management (ITM), Industriell ekonomi och organisation.
    Relationship between competitive priorities and global supply chain design: A conceptual frameworkManuscript (preprint) (Other academic)
  • 7.
    Abid, Muhammad
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Industrial economics. University of Gävle, Center for Logistics and Innovative Production.
    Bengtsson, Lars
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Industrial economics. University of Gävle, Center for Logistics and Innovative Production.
    Dabhilkar, Mandar
    Stockholm University, School of Business.
    Factors affecting shifts in global supply chain networks: A configurational approach2013In: Proceedings of the 20th International Annual EurOMA conference, Dublin, Ireland, 9-12 June 2013, 2013Conference paper (Refereed)
    Abstract [en]

    In certain situations, global companies strive to take advantage of short-term changes in economic and exchange rates on the never-ending journey of competitiveness. This paper seeks to extend Ferdows’s (2008) production network models by adding the factors affecting shifts between rooted and footloose network configurations. Two companies were selected in order to illustrate the models and reveal other possible factors. The identified factors are differentiated in terms of configuration and coordination and merged in a matrix. The trends and implications on global supply chains are also discussed. 

  • 8.
    Abid, Muhammad
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Industrial economics. University of Gävle, Center for Logistics and Innovative Production.
    Bengtsson, Lars
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Industrial economics. University of Gävle, Center for Logistics and Innovative Production.
    Hellberg, Roland
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Industrial economics. University of Gävle, Center for Logistics and Innovative Production.
    Dabhilkar, Mandar
    KTH Royal Institute of Technology, Department of Industrial Economics and Management .
    Factors affecting global supply chain design2012Conference paper (Refereed)
    Abstract [en]

    Due to the limited existing knowledge pertaining to the factors which govern localization of operations and capabilities in a global supply chain, the purpose of the paper is to find out which factors and how they jointly affect the design of global supply chains. The relevant literature is reviewed and a concept matrix is developed. Five companies were selected in order to illustrate the issues of global supply chain design. Among them, three companies are considered to have efficient supply chain and less complex products, while the two others are considered to have responsive supply chain and more complex products. The issues discussed with the selected companies cover global sourcing, challenges, technological advancement and issues related to management control. The study identifies about fifty factors that affect global supply chain design, and specifically how theses relate to design decisions on location of factories and production, supplier selection and development, distribution of products and organisation of interfaces along the supply chain. The discrepancies between theory and practice as well as the implications for further research are discussed.

  • 9.
    Abid, Muhammad
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Industrial economics. University of Gävle, Center for Logistics and Innovative Production.
    Bengtsson, Lars
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Industrial economics. University of Gävle, Center for Logistics and Innovative Production.
    Hellberg, Roland
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Industrial economics. University of Gävle, Center for Logistics and Innovative Production.
    Mandar, Dabhilkar
    KTH Royal Institute of Technology, Department of Industrial Economics and Management .
    Global supply chain design: Building a decision model2012Conference paper (Refereed)
    Abstract [en]

    The knowledge pertaining to the factors, which govern localization of operations and capabilities in a global supply chain, is limited. The purpose of the paper is to find out which factors and how they jointly affect the design of a global supply chain. The relevant literature is reviewed and a concept matrix is developed. The study identifies 30 factors that affect a global supply chain design and specifically how theses relate to the design decisions on location of factories and production, supplier selection and development, distribution logistics, organisation of interfaces/enterprise information infrastructure along the supply chain and human resource development. The decision model is developed and the description of the model is done with the help of an example (location of a factory) by using the Analytical Hierarchy Process (AHP) (Saaty, 1990).  

  • 10.
    Abolghasemi Kordestani, Arash
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för industriell ekonomi.
    Farhat, Farshad
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för industriell ekonomi.
    Supply Chain Maturity and Financial Performance: Study of Swedish SMEs2009Independent thesis Advanced level (degree of Master (One Year)), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Purpose - The goal of this research is to demonstrate that financial performance of current year is dependent to the amount of maturity of the supply chain processes. This aim is achieved through considering current supply chain process maturities of the firm together with financial performance of prior years.

     

     

    Research question - How supply chain process maturities in relation to financial performance of prior years are related to current financial performance  

     

     

    Methodology - The deductive approach has been followed to use theories and literatures to build the hypothetical model in order to test it empirically.

    This quantitative research is benefited from the primary data of Swedish steel SMEs including the secondary data from financial ratios from Scandinavian financial database

     

     

    Findings - The effect between supply chain process maturity and current year financial performance, the effect between prior year financial performance and current year financial performance, and also total effect of prior year financial performance and supply chain process maturity on current year financial performance proved empirically.

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  • 11.
    Abrahamsson, Emilie
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Relationen mellan kalkyleringsmetoder, Lean och produktionsflöden av kundanpassad karaktär: Hur kostnadsprecisionen i förkalkyleringen i denna typ av produktion kan ökas samt vilken kalkyleringsmetod som passar bäst2015Independent thesis Basic level (university diploma), 180 HE creditsStudent thesis
    Abstract [en]

    Since the manufacturing industry is heading for a higher level of customization and implementation of Lean, at the same time as outmoded traditional costing methods is still used in modern industrial organizations, it is interesting to explore the relations between production flows of customized character, Lean and different costing methods.

    The purpose of this thesis is to increase the cost precision in the preliminary calculation for a product flow of customer adapted and Lean character, and to describe a generalizable work process for this. The purpose is also to develop general recommendations regarding the choice of costing methods by, on a basis of the character of this production, a comparative analysis of costing methods (traditional costing methods, ABC and Lean accounting/VSC). Through a literature study and a case study of a production flow with a high level of variety and influence from Lean, both of the purposes has been fulfilled.

    The case study has been accomplished through interviews and observations. Problems and positive elements that according to literature characterize the production of customized products have also been found in the case company. That connection has been used to support the analysis of the relations. The relations between costing methods, Lean and production flows of customized character has been analyzed through a comparison between findings in literature and results from the case study. It has been found that Value Stream Costing (VSC) is the most appropriate costing method for production flows of customized products that has reached a high maturity level of Lean.

    The preliminary costing is dependent on reliable operation times which have been produced on the case study company, while a general work process has been developed. The operation times were in this case identified through video recordings of the production moments and a following analysis in the software AviX. By following the general work process that has been developed, useful material for preliminary costing and continuous improvements in the production flow will be obtained.

    Since research is showing that Lean should be implemented in the whole organization if full advantages of Lean shall be obtained, VSC is found to be an ideal costing method to replace outmoded, traditional costing methods at the same time as this costing method simplifies costing in production flows of customized character.

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  • 12.
    Afzali Gorouh, Hossein
    et al.
    Shahid Bahonar University of Kerman, Iran.
    Salmanzadeh, Mazyar
    Shahid Bahonar University of Kerman, Iran.
    Nasseriyan, Pouriya
    Shahid Bahonar University of Kerman, Iran.
    Hayati, Abolfazl
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Cabral, Diogo
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Karlsson, Björn
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Thermal modelling and experimental evaluation of a novel concentrating photovoltaic thermal collector (CPVT) with parabolic concentrator2022In: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 181, p. 535-553Article in journal (Refereed)
    Abstract [en]

    In the present study, a zero-dimensional thermal model has been developed to analyze a novel low concentration photovoltaic-thermal (CPVT) collector. The model has been developed by driving heat transfer and energy balance equations for each part of the collector and then solving all the equations simultaneously. Moreover, a Monte-Carlo ray-tracing software has been used for optical stimulations of the parabolic trough solar collector. The novel CPVT collector has been experimentally tested at Gävle University (Sweden) and the model has been validated against the experimental results. The primary energy saving equivalent to the thermal-electrical power cogeneration of the CPVT collector has been determined. The effect of glass cover removal, heat transfer fluid (HTF) inlet temperature and mass flow rate on the collector performance has been investigated. The optimum HTF mass flow rates of the collector for maximum electrical yield and overall primary energy saving were determined under specified operating conditions by considering the pump consumption. The effect of mean fluid temperature on the thermal and electrical efficiencies has been studied and the characteristic equation of the thermal efficiency has been obtained. The thermal and electrical peak efficiencies of the collector have been found to be 69.6% and 6.1%, respectively.

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  • 13.
    Agostini, Lara
    et al.
    University of Padova, Italy.
    Bengtsson, Lars
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Industrial economics. University of Gävle, Center for Logistics and Innovative Production.
    Lazzarotti, Valentina
    Carlo Cattaneo University LIUC, Italy.
    Manzini, Raffaella
    Carlo Cattaneo University LIUC, Italy.
    Nosella, Anna
    University of Padova, Italy.
    Pellegrini, Luisa
    Stefan, Ioana
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Industrial economics. University of Gävle, Center for Logistics and Innovative Production.
    Combining an external with an internal perspective on open innovation with scientific partners and patenting2017In: 18th International CINet Conference: Digitalization and innovation: designing the organization of the future, 2017Conference paper (Refereed)
  • 14.
    Ahnfeldt, Tomas
    University of Gävle, Department of Technology and Built Environment.
    Geometry for CAD Toolbox2008Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
  • 15.
    Al Khatib, Bayan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Management, Industrial Design and Mechanical Engineering, Mechanical Engineering.
    Vakuumlyftverktyg för Rullborrkroneben2021Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Sandvik Mining and Rock Technology (SMRT) manufactures various roller-cone bits that are used for rock drilling. The roller-cone bit consists of three welded cones. The cones are forged and delivered from an external supplier. The roller-cone bit’s cones are collected in an EU-table then lifted into a milling machine for processing. After the milling, the roller-cone bit’s cone is lifted again to a pattern table. Today, the method used today to lift the roller cone bit’s cones is not considered optimal for the operators. To improve the ergonomics of the operators, a vacuum lifting tool has been developed. The purpose of the work is to improve ergonomics through the lifting process of roller-cone bit cones. The goal is to develop a safer lifting tool. The lifting tool must be ergonomic and easy to use. To achieve the goal, previous research was examined on risk assessments of the working positions and standard SS-EN 13155:2009 followed. The Ovako Working Posture Analyzing System (OWAS) method was used to determine which working positions are considered most stressful for operators and needed to be addressed. The result from OWAS showed that the most stressful working position is the lifting of the roller-cone bit from the EU table. The concept, that was developed, consists of a suction pin connected to a vacuum pump with a T-piece. A pressure sensor is also connected to the t-piece to control the vacuum bar for the lifting tool. With the help of a non-return valve, the maintenance of the vacuum is ensured in case of power failure. After using the lifting tool, there will be no need to lift the roller-cone bit to load and unload the lifting strap. This means that the work positions with a high risk for load damage are going to be minimized.

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  • 16.
    Ali, Ali Talib
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Resilient cooling technologies: Simulation study to determine the cooling capacity in old residentialbuildings located in mid-Sweden2022Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The Long-term changes in the climate conditions have increased the need foradequate thermal comfort systems. These alternations influence extremeevents, which their intensity and frequency have increased over the past years.Moreover, this study focuses on space cooling and parameters that the systemshould have to be considered as resilient. Literature study was done to presentthe concept of resilience as well as the different methods used to provide spacecooling. In addition, the cooling systems suggested in this study, which aredistrict cooling and absorption cooling, were presented and explained.Furthermore, the study focuses on cooling demand in a group of residentialbuildings based on different thermal characteristics, which were implementedbased on building regulations from late 1960s to early 1980s. The buildingthermal properties were used as input to obtain their cooling demand by usingbuilding energy simulation tool. Based on the acquired results, an evaluationhas been made for the cooling demand of those buildings. Further analysispresented a correlation between the cooling demand and thermal properties ofthe buildings and aided in the determination of the required cooling capacity.The selection of the capacities was based on the resilience criterion as the systemhas to be able to provide adequate performance and safety for the occupantsduring extreme events. Furthermore, an assessment was done to compare thesuggested system based on their capacities and the primary energy use.

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  • 17.
    Alieva, Jamila
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Management, Industrial Design and Mechanical Engineering, Industrial Management.
    von Haartman, Robin
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Management, Industrial Design and Mechanical Engineering, Industrial Management.
    Waste under the impact of digital technologies: Evidence from European manufacturing survey (EMS)2022In: The proceedings of the 29th international EurOMA conference, 2022Conference paper (Refereed)
    Abstract [en]

    This paper is based on European Manufacturing Survey collected in 2019 for five countries -Sweden, Spain, Croatia, Austria, and Slovenia. The study reveals that majority of companieshave technologies that allow them automatically to collect data. Companies are also using thedata for different purposes, and often more than one purposes. We also found that many ofcommonly used digital technologies are also associated with automatically collected data.Although the literature suggests that ignorance of data collection may lead to defects, we findno connection to actual waste in this study.

  • 18.
    Allabwani, Omar
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Management, Industrial Design and Mechanical Engineering.
    Problemidentifiering och lösningskonstruktion för fixering av rör i skärmaskin2021Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This work aims to identify the challenges of the process of cutting pipe samples with the current cutting machine at Sandvik Materials Technology SMT. The purpose is to create a design that avoids the identified problems.

    The design aims to improve the quality of the piece that is cut from the pipe before examining it by the material testing machine (stress /strain testing) that checks the quality of the produced tubes of Sandvik Factory before selling.

    The new design is expected to reduce the number of defective pieces. It will also make the work easier, faster, and more precise. Currently, the pipes are of various diameters and lengths are secured by clamps driven by pneumatic cylinder. These clamps hold a pipe by each end. Then the pipe is placed on a water table where a water jet cuts the test piece.

    After observation and interviewing with customers, the problems were identified. We realized that the existing mechanism was very complicated, and a new mechanism was needed.

    Three proposals were developed. These proposals were evaluated by using a Pugh matrix and the best proposal was selected.

    The chosen solution requires : a balanced movable table which moves up and down by a waterproof electrically- linear actuator, a V-shaped piece fixed to the table that fits pipes of various diameters and lengths, a pneumatic cylinder which clamps the pipe and secures it in place.

    An alternative solution was to improve the current fixture, but the customer want-ed to focus on developing a completely new concept. An important factor in the concept development was that the fixture must be able to function in an unique environment of a water bath with sand. This environment entails major limitations regarding the choice of materials and machine elements. Two support legs were developed to reduce the bureau loss effect when the table goes up or down due to the weight not evenly distributed on the table surface. During the development concept, the need was identified for a sensor that can ensure that the table is lowered to the correct level. Selection of the sensor requires automation knowledge, this is why it was eliminated from the work. This new mechanism ensures securing the pipe in place and reduces the number of required actions in the process. This leads to reduction of the defects in the test piece. The new design is simpler, faster, requires less space and is more precise.

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  • 19.
    Ameen, Arman
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Efficient Cooling with multiple impinging jets: Obtaining boundary condition and verification for a CFD model2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Saving energy and optimizing industrial processes are major priorities for companies around the world. In this study the cooling process (with air) of large rollers are examined. The result of these examinations are used to create a computational fluid dynamic model. These examination consists of geometry, volume flows, velocities, velocity profiles, temperature and pressure. A complication in the measurements occurred due to the nonsymmetrical installation of the nozzles in the cooling setup. The results highlights how this nonsymmetrical installation affects the cooling. Multiple methods were used to carry out this work, and some additional side project were implemented. The results in this thesis is not enough to create a CFD model and further work have to be carried out in the future.

  • 20.
    Ameen, Arman
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Bahrami, Alireza
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    El Tayara, Khaled
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Energy Performance Evaluation of Historical Building2022In: Buildings, E-ISSN 2075-5309, Vol. 12, no 10, article id 1667Article in journal (Refereed)
    Abstract [en]

    Retrofitting measures in old buildings aimed at reducing energy usage have become important procedures meant to counteract the effects of climate change and greenhouse gas emissions. The aim of this study is to evaluate energy usage, thermal comfort, and CO2 emissions of an old building by changing parameters such as building orientation, shading systems, location, low energy film application, and alternative energy supply in the form of a geothermal heat pump. When evaluating the buildings in terms of geographical location with or without applying the low energy film, the results show that the city of Gävle in Sweden requires the most heating energy, 150.3 kWh/m2∙year (B0) compared to Jakarta (L0), which requires 23.8 kWh/m2∙year. When examining the thermal comfort, cases B4 and L4 demonstrate the best results in their respective categories (B0–B4 are cases without low energy film and L0–L4 are cases with applied low energy film). The results for the CO2 emissions levels for B0–B4 and L0–L4 indicate that B4 has the highest value, 400 kg CO2 eq/year higher than B0, and L1 has the lowest value, 731 kg CO2 eq/year lower than B0. The economic feasibility study illustrates that the installation of a geothermal heat pump with at least a coefficient of performance of 4.0 leads to a shorter payback period than solely applying LEF.

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  • 21.
    Ameen, Arman
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Cehlin, Mathias
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Reducing energy usage in multi-family housing2019In: 2019 9th International Conference on Future Environment and Energy 9–11 January 2019, Osaka, Japan, Institute of Physics Publishing (IOPP), 2019, Vol. 257, article id 012030Conference paper (Refereed)
    Abstract [en]

    The energy usage in residential sector have been around 22% of the total energy use in the world and increasing due to the population growth and higher living standards. The energy sources for this are made up primarily of non-renewable energy resources which generates a large amount of global greenhouse gases. A lot of countries have implemented various regulations and rules to reduce the energy usage in buildings and promoting the use of renewable energy technologies. This paper presents a parametric study of a typical multi-family building in its pre-design stage. The climate location used is Sweden (Gothenburg) and Japan (Osaka). The aim of the study is to compare various configurations and to examine how they affect the energy use. The most interesting configurations are the use of heat pump and solar cells. Other configurations that are examined are infiltration levels, pressure coefficients, wind impact, ventilation with heat recovery, ventilation scheduling, building orientation and finally changing U-values in the building material. Results of this study show that the energy saving, by utilizing a heat pump and solar panels, can reduce the total energy use by 34.9% for Gothenburg and 32% for Osaka. The results also show that the difference in total energy use between the two cities reduce substantially (3% difference) when utilizing a heat pump in combination with solar panels.

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  • 22.
    Ameen, Arman
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Cehlin, Mathias
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Larsson, Ulf
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Karimipanah, Taghi
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Experimental investigation of ventilation performance of different air distribution systems in an office environment – cooling mode2019In: Energies, E-ISSN 1996-1073, Vol. 12, no 7, article id 1354Article in journal (Refereed)
    Abstract [en]

    The performance of a newly designed corner impinging jet air distribution method with an equilateral triangle cross section was evaluated experimentally and compared to that of two more traditional methods (mixing and displacement ventilation). At nine evenly chosen positions with four standard vertical points, air velocity, turbulence intensity, temperature, and tracer gas decay measurements were conducted for all systems. The results show that the new method behaves as a displacement ventilation system, with high air change effectiveness and stratified flow pattern and temperature field. Both local air change effectiveness and air exchange effectiveness of the corner impinging jet showed high quality and promising results, which is a good indicator of ventilation effectiveness. The results also indicate that there is a possibility to slightly lower the airflow rates for the new air distribution system, while still meeting the requirements for thermal comfort and indoor air quality, thereby reducing fan energy usage. The draught rate was also lower for corner impinging jet compared to the other tested air distribution methods. The findings of this research show that the corner impinging jet method can be used for office ventilation.

  • 23.
    Ameen, Arman
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Cehlin, Mathias
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Larsson, Ulf
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Yamasawa, Haruna
    Kyushu University, Fukuoka, Japan.
    Kobayashi, Tomohiro
    Osaka University, Osaka, Japan.
    Numerical investigation of the flow behavior of an isothermal corner impinging jet for building ventilation2022In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 223, article id 109486Article in journal (Refereed)
    Abstract [en]

    The corner impinging jet concept has been proposed as a new air distribution system for use in office environments. The present paper reports the mean flow field behavior of an isothermal corner-based turbulent impinging jet in a room. A detailed experimental study is carried out to validate the numerical simulations, and the predictions are performed using three turbulence models. RNG k−ε model was chosen for this study. This study investigates the influence different configuration parameters such as jet discharge height, diffuser geometry (shape and size) and supply airflow rate have on the flow field. The results show that the diffuser geometries used in this study had in general a minor effect on the velocity developments along the centerline of the floor, maximum velocity decay and jet spreading rate except for some specific cases. When evaluating the triangle geometry cases, the results show that all the cases with volume flow <20 L/s are able to meet Boverket's building regulations velocity requirement both for summer and winter. The applicability evaluation show that the results can be considered for room sizes between ≈25 and 100 m2. In addition, the wall confinement effect (90° vs. 180°) is having a significant impact on the maximum velocity decay for corner impinging jet ventilation. In the regression analysis the results shows that the distance along the diagonal centerline of the room has the most impact on the evaluation of maximum velocity decay and jet spreading rate.

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  • 24.
    Ameen, Arman
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Yamasawa, Haruna
    Kyushu University, Fukuoka, Japan..
    Kobayashi, Tomohiro
    Osaka University, Osaka, Japan..
    Numerical Evaluation of the Flow Field of An Isothermal Dual-Corner Impinging Jet for Building Ventilation2022In: Buildings, E-ISSN 2075-5309, Vol. 12, no 10, article id 1767Article in journal (Refereed)
    Abstract [en]

    The corner impinging jet ventilation is a new air distribution system for use in office environments. This study reports the mean flow field behavior of dual isothermal corner-placed inlets based on an impinging jet in a square-shaped room with the size of 7.2 m × 7.2 m. A detailed numerical study is carried out to evaluate the influence the different configuration parameters, such as the inlet placement, same side or opposite side, and supply airflow rate, have on the flow field. The results show that the highest velocity peak for all cases is obtained at x = 0.5 m and the lowest at x = 3.5 m. The velocity profiles development remains similar when increasing the flow rate. For the zone evaluation, the results show that Case 1 and 2 (V = 20 L/s) meet the requirement of not exceeding 0.15 m/s during the heating season in the occupied zone according the BBR standard both for same-side and opposite-side configurations. For Case 4, the optimal placement of the inlets is opposite to each other when V = 30 L/s for the BBR requirements. Case 1, 2, 3, 4, 5, and 7 all meet the requirement of not exceeding 0.25 m/s during the cooling season both for the same-side and opposite-side configurations. For Case 8, the optimal placement of the inlets is opposite to each other when V = 50 L/s.

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  • 25.
    Amiri, Shahnaz
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy engineering.
    Moshfegh, Bahram
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy engineering.
    Possibilities and consequences of deregulation of the European electricity market for connection of heat sparse areas to district heating systems2010In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 87, no 7, p. 2401-2410Article in journal (Refereed)
    Abstract [en]

    The objective of the study is to analyse the conditions for connection of residential buildings in heat sparse areas to district heating systems in order to increase electricity production in municipal combined heat and power plants. The European electricity market has been assumed to be fully deregulated. The relation between connection of heat sparse areas, increased electricity and heat production as well as electricity prices, fuel prices and emissions rights is investigated. The results of the study show that there is potential to expand the district heating market to areas with lower heat concentrations in the cities of Gavle, Sandviken and Borlange in Sweden, with both economic and environmental benefits. The expansion provides a substantial heat demand of approximately 181 GWh/year, which results in an electricity power production of approximately 43 GWh/year. Since the detached and stand-alone houses in the studied heat sparse areas have been heated either by oil boiler or by direct electricity, connection to district heating also provides a substantial reduction in emissions of CO(2). The largest reductions in CO(2) emissions are found to be 211 ktonnes/year assuming coal-fired condensing power as marginal electricity production. Connection of heat sparse areas to district heating decrease the system costs and provide a profitability by approximately 22 million EURO/year for the studied municipalities if the price of electricity is at a European level, i.e. 110 EURO/MWh. Sensitivity analysis shows, among other things, that a strong relation exists between the price of electricity and the profitability of connecting heat sparse areas to district heating systems.

  • 26.
    Amiri, Shahnaz
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik. Department of Management and Engineering, Division of Energy Systems, Linköping University, Linköping, Sweden.
    Trygg, Louise
    Department of Management and Engineering, Division of Energy Systems, Linköping University, Linköping, Sweden.
    Moshfegh, Bahram
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik. Department of Management and Engineering, Division of Energy Systems, Linköping University, Linköping, Sweden.
    Assessment of the natural gas potential for heat and power generation in the County of Östergötland in Sweden2009In: Energy Policy, ISSN 0301-4215, E-ISSN 1873-6777, Vol. 37, no 2, p. 496-506Article in journal (Refereed)
    Abstract [en]

    The aim of this study is to investigate the potential use of natural gas for heat and power production for the municipality of Linkoping, Norrkoping and Finspang in the County of Ostergotland, Sweden. The results of the study revealed that these three municipalities with the present heating demand can convert 2030 GWh/year of the present fuel mixed to natural gas. The expansion of natural gas provides the possibility to increase the electricity generation with approximately 800 GWh annually in the County of Ostergotland. The global emissions of CO(2) reduce also by approximately 490 ktonne/year by assuming the coal condensing power plant as the marginal power plant. The total system cost decreases by 76 Mkr/year with the present electricity price which varies between 432 and 173 SEK/MWh and with 248 Mkr/year if the present electricity price increases to 37% which is approximately corresponding to European electricity prices. Sensitivity analysis is done with respect to the different factors such as price of electricity, natural gas, etc. The findings show that increased price of electricity and increased district heating demand increases the profitability to convert to natural gas using CHP plant. (C) 2008 Elsevier Ltd. All rights reserved.

  • 27.
    Anastasopoulou, Kyriaki
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Creation of a Low Energy Building with the help of Energy Simulation2017Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this Thesis Project, the creation of a Low Energy building was examined in order to investigate how complex was to select the suitable parameters and systems of the dwelling, aiming to achieve the lowest possible energy consumption in one year period. All the technologies implemented into the system intended to be as energy efficient and profitable as possible. Another objective of this study was also to present the potential of the system to produce a part of the consumed energy, through renewable energy sources, approaching by this way also the standards of a Zero Energy Building. Firstly, the floor plan of the 150 m2 detached house, was drawn in the designing program AutoCAD. In continuation, this 2D floor plan was imported into the simulation program as well as all the initial input data so as for the Base model of the building to be created For the analysis of the building, the Simulation Program IDA ICE 4.7 was used. Gradually, alternations and adjustments were made into the Base model. Different models were created planning to analyze their results and conclude to the proper solution. All the simulations run for one year time period in order to present the total energy usage, system’s losses and demands in each case. In addition, as for the current study, the location of the construction was Athens, all building’s characteristics were chosen to comply with the Greek Regulation for Low Energy Buildings. Finally, through the procedure followed after having accomplished a series of simulations, the final annually energy demands managed to be within the required limits.

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  • 28.
    Andersen, Niklas
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Wind Turbine End of Life: Characterisation of Waste Material2015Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Wind power is growing fast all over the world, and in Sweden alone thousands of turbines has been installed the last few decades. Although the number of decommissioned turbines so far is very low, the rapid installation rate indicates that a similar rapid decommissioning rate is to be expected shortly. If the waste material from these turbines is not handled sustainably the whole concept of wind power as a clean energy alternative is challenged.

    This study aims to present an accurate estimate of the amounts of waste material that will be generated from wind turbines in Sweden during the coming decades, allowing the waste management industry to plan for this and by extension prevent unnecessary energy losses through imperfect waste treatment. It should also present helpful information on how problematic waste can be reduced or avoided.

    VindStat’s annual report, presenting installation date and other relevant data for most installed turbines in Sweden, has been used as the base for the calculations. Information on material composition in different types and sizes of wind turbines has been extracted from various life cycle assessments, and by using the available parameters in the data base each turbine has been assigned a specific amount of steel, iron, copper, aluminum, blade material and electronics. An average life time of 20 years has been assumed, based on prior research and comparison with empiric data, and the material of each turbine is therefore seen as generated waste 20 years after installation date.

    To calculate the amount of waste material from replacing faulty components, empiric data over replacement rates in further developed markets has been combined with a prognosis over future development of installed wind capacity in Sweden based on a method described by prior research. As no sufficient way to predict how the future second hand market for turbines and components has been found, three different possible scenarios have been investigated to see how this may affect waste amounts.

    The results show that annual waste will grow slowly at about 12 % increase per year until around 2026, and then the average increase is 41 % per year until 2034. By then, annual waste amounts are estimated to have reached 237 600 tonne steel and iron (16 % of currently recycled amounts), 2 300 tonne aluminium (4 %), 3 300 tonne copper (5 %), 343 tonne electronics (<1 %) and 28 100 tonne blade material. There is no industrial scale recycling method for commonly used blade materials, and a high strength steel developed by Sandvik is proposed as a fully recyclable material to consider for further research. A well-functioning second hand market is shown to possibly have a major impact on waste amounts, at least in postponing it until better recycling systems are in place.

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    Wind turbines end-of-life - Characterisation of Waste Material
  • 29.
    Andersen, Niklas
    et al.
    Energi Funktion Komfort Skandinavien AB, Nacka, Sweden.
    Eriksson, Ola
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Environmental engineering.
    Hillman, Karl
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Environmental engineering.
    Wallhagen, Marita
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Environmental engineering.
    Wind turbines’ end-of-life: Quantification and characterisation of future waste materials on a national level2016In: Energies, E-ISSN 1996-1073, Vol. 9, no 12, article id 999Article in journal (Refereed)
    Abstract [en]

    Globally, wind power is growing fast and in Sweden alone more than 3000 turbines have been installed since the mid-1990s. Although the number of decommissioned turbines so far is few, the high installation rate suggests that a similarly high decommissioning rate can be expected at some point in the future. If the waste material from these turbines is not handled sustainably the whole concept of wind power as a clean energy alternative is challenged. This study presents a generally applicable method and quantification based on statistics of the waste amounts from wind turbines in Sweden. The expected annual mean growth is 12% until 2026, followed by a mean increase of 41% until 2034. By then, annual waste amounts are estimated to 240,000 tonnes steel and iron (16% of currently recycled materials), 2300 tonnes aluminium (4%), 3300 tonnes copper (5%), 340 tonnes electronics (<1%) and 28,000 tonnes blade materials (barely recycled today). Three studied scenarios suggest that a well-functioning market for re-use may postpone the effects of these waste amounts until improved recycling systems are in place.

  • 30.
    Andersson, Harald
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Numerical and experimental study of confluent jets supply device with variable airflow2019Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    In recent years, application of confluent jets for design of ventilation supply devices has been studied. Similarly, numerus studies have been made on the potential and application of variable air volume (VAV) in order to reduce the energy demand of ventilation systems. This study investigates the combination of supply devices based on confluent jets and VAV, both in terms of the nearfield flow behavior of the device and the impact on thermal comfort, indoor air quality and energy efficiency on a classroom-level space when the airflow rate is varied.

    The method used in this study is an experimental field study where the confluent jets-based supply devices were compared to the previously installed displacement ventilation. The field study evaluated the energy efficiency, thermal comfort and indoor air quality of the two systems. In the case of the confluent jets supply devices, airflow rate was varied in order to see what impact the variation had on the performance of the system for each airflow rate. Furthermore, the confluent jets supply devices were investigated both experimentally and numerically in a well insulated test room to get high resolution data on the particular flow characteristics for this type of supply device when the airflow rate is varied. The results from the field study show nearly uniform distribution of the local mean age of air in the occupied zone, even in the cases of relatively low airflow rates. The airflow rates have no significant effect on the degree of mixing. The thermal comfort in the classroom was increased when the airflow rate was adapted to the heat load compared to the displacement system. The results lead to the conclusion that the combination of supply devices based on confluent jets can reduce energy usage in the school while maintaining indoor air quality and increasing the thermal comfort in the occupied zone.

    The results from the experimental and numerical study show that the flow pattern and velocity in each nozzle is directly dependent on the total airflow rate. However, the flow pattern does not vary between the three different airflow rates. The numerical investigation shows that velocity profiles for each nozzle have the same pattern regardless of the airflow rate, but the magnitude of the velocity profile increases as the airflow increases. Thus, a supply device of this kind could be used for variable air volume and produce confluent jets for different airflow rates.

    The results from both studies show that the airflow rate does not affect the distribution of the airflow on both near-field and room level. The distribution of air is nearly uniform in the case of the near-field results and the room-level measurement shows a completely uniform degree of mixing and air quality in the occupied zone for each airflow rate. This means that there is potential for combining these two schemes for designing air distribution systems with high energy efficiency and high thermal comfort and indoor air quality.

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  • 31.
    Andersson, Harald
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Optimization of confluent jets ventilation with variable airflow2022Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In recent years, applications of confluent jets for design of ventilation supply devices have been widely studied. Similarly, numerous studies have been made on the potential and application of variable air volume (VAV) in order to reduce the energy demand of ventilation systems. This study investigates the combination of confluent jets ventilation (CJV) and VAV, both in terms of the near-field flow behavior of the device and the impact on thermal comfort, indoor air quality and energy efficiency in conference room and classroom environments when the airflow rate is varied. For the investigation of CJV with VAV in a classroom environment two experimental studies were performed. One was a field study in a school classroom with a constant supply temperature and four cases with varying heat loads and airflow rates. The other took place in a laboratory environment with five cases, all with varying heat loads, supply temperatures and airflow rates. The two experimental studies measured mean age of air, air speeds and temperatures in the occupied zone. Both studies showed that CJV had higher energy efficiency and indoor air quality than conventional mixing ventilation. The main effects of lower supply temperatures were higher velocities in the occupied zone as well as lower temperatures due to higher energy efficiency . CJV produces mixing ventilation conditions at lower airflow rates (<4.2 ACH) and non-uniform conditions at higher airflow rates. The thermal comfort was similar to that of conventional mixing ventilation and had very small temperature gradients compared to displacement ventilation. For the investigation of CJV with VAV in a conference room environment three combined experimental and numerical studies were performed. One focused on the jet velocity profiles from the CJV supply device, the results of which were used as boundary conditions for the two other studies. The second study measured the conditions in the confluent jet development area and the occupied zone experimentally for six cases with different supply temperatures, airflow rates and nozzle matrix configurations. The results were used for validating the numerical model which was used in the last paper. The final paper was a parametric numerical study which used the response surface method to investigate the impact of four design variables: heat load, number of nozzles, airflow rate and supply temperature on energy efficiency, indoor air quality and thermal comfort. The results show that indoor air quality is increased with higher airflow rates. The energy efficiency has a negative correlation to the heat load but a positive correlation to the airflow rate which results in relatively stable heat removal effectiveness of 110% as heat load is increased and the VAV system compensates with higher airflow rates. The results also show that in a VAV system which aims at providing  uniform temperatures in the occupied zone, the thermal comfort is mostly dependent on a combination of the CLO value and the range of the airflow rates. At low CLO values the range of the airflow rate needs to be increased to create a satisfactory thermal climate.

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  • 32.
    Andersson, Harald
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Cehlin, Mathias
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Moshfegh, Bahram
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology. Linköping Universitet.
    An Investigation Concerning Optimal Design of Confluent Jets Ventilation with Variable Air Volume2024In: The International Journal of Ventilation, ISSN 1473-3315, E-ISSN 2044-4044Article in journal (Refereed)
    Abstract [en]

    This  parametric study aims to predict the  performance of confluent jets ventilation (CJV) with variable air  volume (VAV) from four  CJV  design parameters. A  combination of  computational fluid dynamics (CFD), and response surface method (RSM) has  been used to  predict the  energy efficiency, thermal comfort and  IAQ  for  the  four  expected vital  design variables, i.e.,  heat load (XH),  number of  nozzles (XN),  airflow rate  (XQ) and  supply temperature (XTS).  The  RSM was  used to  generate a  quad-ratic  equation for  the  response variables exhaust temperature (TE),  sup-ply  temperature (TP),  PMV, DR, eT and  ACE. The  RSM  shows that  the  TE, TP and PMV were independent of the number of nozzles. The proposed equations were used to  generate setpoints optimized for  thermal com-fort  (PMV) for  summer, spring and  winter cases with different CLO  fac-tors  and  different TS under a  scenario where the  heat load varied between 10-30W/m2.  TE was  used as  setpoint to  regulate the  airflow rate  to  keep the  PMV values close to  zero. The  results show that  by adapting the TS to the CLO factor both thermal comfort and the energy efficiency can  be  improved. Further energy reduction can  be  gained by downregulating the airflow rate to keep the TP at a fixed setpoint when the  heat load is  decreased. This  means that  a  CJV  can  effectively be combined with VAV  to  improve environmental performance with good thermal comfort (-0.5<PMV <0.5,  DR <20%), above average IAQ (ACE = 106%) and  with a  higher heat removal efficiency (eT = 110%) than conventional mixing ventilation

  • 33.
    Andersson, Harald
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Cehlin, Mathias
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Moshfegh, Bahram
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Experimental and numerical investigations of a new ventilation supply device based on confluent jets2018In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 137, p. 18-33Article in journal (Refereed)
    Abstract [en]

    In developed countries, heating, ventilation, air conditioning (HVAC) systems account for more than 10% of national energy use. The primary function of a HVAC system is to create proper indoor environment. A number of ventilation strategies have been developed to minimize HVAC systems’ energy use whilst still maintaining a good indoor environment. Among these strategies are confluent jet ventilation and variable air volume. In this study, an air supply device with a novel nozzle design that uses both of the above-mentioned strategies was investigated both experimentally and numerically at three different airflow rates. The results from the numerical investigation using the SST k - ω turbulence model regarding velocities and flow patterns are validated by experimental data carried out by Laser Doppler Anemometry. The results from both studies show that the flow pattern and velocity in each nozzle is directly dependent on the total airflow rate. However, the flow pattern does not vary between the three different airflow rates. The numerical investigation shows that velocity profiles for each nozzle have the same pattern regardless of the airflow rate, but the magnitude of the velocity profile increases as the airflow increases. Thus, a supply device of this kind could be used for variable air volume and produce confluent jets for the airflow rates investigated.

  • 34.
    Andersson, Harald
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Kabanshi, Alan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Cehlin, Mathias
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Moshfegh, Bahram
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology. Linköpings universitet.
    On the ventilation performance of low momentum confluent jets supply device in a classroom2020In: Energies, E-ISSN 1996-1073, Vol. 13, no 20, article id 5415Article in journal (Refereed)
    Abstract [en]

    The performance of three different confluent jets ventilation (CJV) supply devices was evaluated in a classroom environment concerning thermal comfort, indoor air quality (IAQ) and energy efficiency. The CJV supply devices have the acronyms: high-momentum confluent jets (HMCJ), low-momentum confluent jets (LMCJ) and low-momentum confluent jets modified by varying airflow direction (LMCJ-M). A mixing ventilation (MV) slot jet (SJ) supply device was used as a benchmark. Comparisons were made with identical set-up conditions in five cases with different supply temperatures (TS) (16–18 °C), airflow rates (2.2–6.3 ACH) and heat loads (17–47 W/m2). Performances were evaluated based on DR (draft rating), PMV (predicted mean vote), ACE (air change effectiveness) and heat removal effectiveness (HRE). The results show that CJV had higher HRE and IAQ than MV and LMCJ/LMCJ-M had higher ACE than HMCJ. The main effects of lower Ts were higher velocities, DR (HMCJ particularly) and HRE in the occupied zone as well as lower temperatures and PMV-values. HMCJ and LMCJ produce MV conditions at lower airflow rates (<4.2 ACH) and non-uniform conditions at higher airflow rates. LMCJ-M had 7% higher HRE than the other CJV supply devices and produced non-uniform conditions at lower airflow rates (<3.3 ACH). The non-uniform conditions resulted in LMCJ-M having the highest energy efficiency of all devices.

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  • 35.
    Andersson, Jesper
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Management, Industrial Design and Mechanical Engineering.
    Englund, Max
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Management, Industrial Design and Mechanical Engineering.
    Effektivisering och flödeskartläggning: En jämförelse av arbetsflöden i ett industriserviceföretag2023Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Introduction: To stay relevant, it is required that companies work with continuous improvements.Finding inefficiencies is not always easy. One way to try to find inefficiencies is throughflow mapping. This study examines what causes inefficient activities for industrial servicecompanies.

    Purpose: The purpose of the study is to investigate how a workflow at an industrial servicecompany can be made more efficient with the help of flow mapping.

    Method: The study is conducted through a case study at a service industry company that maintainsand repairs motors and frequency converters. Flow mapping was used to map activitiesin the workflow and literature was collected to be able to conduct a flow mappingcorrectly. Interviews and observations have been used to support the flow mapping.

    Results: The company has two service workshops that have similar activities in their flow. Evenso, one of the workflows is more efficient than the other. Based on the comparison of theworkflows, inspiration has been used to adjust the workflow for the frequency converterworkshop. Using flow mapping and methods from lean, a future flow map has beencreated where non-value-added activities have been eliminated.

    Conclusion: Based on the results, several improvement proposals have been drawn up for thecompany's workshops. Industrial service companies can use flow mapping and VSM toeliminate non-value-added activities. Lean tools can be used to create order and structurethat lead to shorter lead times. 

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  • 36.
    Andersson, Martin
    et al.
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Sosa, Mario
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Sjöberg, Sören
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Mechanical Engineering.
    Olofsson, Ulf
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Effect of Assembly Errors in Back-to-Back Gear Efficiency Testing2015In: Power Transmission Engineeing, Vol. December, p. 72-77Article in journal (Other academic)
  • 37.
    Andersson, Niklas
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Energieffektivisering av byggnad med enkla medel: en fallstudie på Hofors mödravårdscentral2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In the central parts of Hofors a healthcenter is located which is included in Hoforshus AB's building stock, the building itself is divided into a main building and a smaller one in which the child health center and maternity care is located. The buildings are connected by a corridor substantially glazed. Now they are interested in maping the building's energyusage as this is relatively high, in addition, the users of the building had been dissatisfied with the indoor climate in both summer and winter. Because of the healtcare activities the owners were most interested in finding solutions that would not interfere with it.

    The study conducted has had a primary focus on the building envelope and above all on the glazed corridor’s impact on the rest of the building. One can assume that the high proportion of glass in this part of the building affects the indoor climate negatively keeping in mind the low U-value of the glass and the solar heat load, this gives during the summer when heat gain is not desired. A literature study to investigate how people perceive the climate as well as how to make a reliable simulation model of a building has been completed. The study resulted in an understanding of how the indoor climate is perceived and quantified, and also in an understanding of what is important in the collection of data for the simulation model.

    Keeping in mind how data should be collected according to the literature reviwe- have as much data as possible measured through surveys and own observations, blueprints have been studied and their validity has been investigated by measuring the building, blower door has been performed and temperature- and relative humidityloggning. Instantaneous values of the FTX system was made to calculate its efficiency. Linear thermal bridges have been investigated by finite element method in the program COMSOL Multiphysics 3.5. For validation of the simulated model the results of it were compared with the acutal measured energyconsumption of the building. The simulations were performed in BV2.

    The results of the study show, as expected, the glazed corridor’s negative impact on the building's indoor climate. Temperature was logged between 160412-160509 highest temperature was 30 ° C and minimum 15 ° C, which is more widespread than in other areas where the temperature was logged. The simulations that were performed on the glazed corridor shows that it consumes between 5000-5500 kWh on the area of 13.5 m2. Finally the study resulted in recommendations for the building that includes additional insulation of the attic, replacement of a smaller wall section, lowering the temperature by 1 ° C, as well as some maintenance measures to improve the indoor climate. The measures are believed to be possible to implement without significant interference with the health care acitivities. In addition the proposed measures seem profitable according to the pay of method.

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  • 38.
    Andersson, Niklas
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Mechanical Engineering.
    Modelling of metal removal rate in titanium alloy milling2018Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Titanium is one of fourth most abundant structural metal in earths soil. It is in a composition with other elements, forming titanium alloys. These alloys are used in many different areas, such as medical, energy and sports, but is most commonly used in aerospace applications. Titanium alloys have different solid phases, α, α+β and β depending on temperature and the amount of α and β-stabilizers.When machining titanium alloys, one of the most important factors to control is the temperature in the cutting zone. The built-up heat in the cutting edge of the tool, are connected to titanium alloys low thermal conductivity and high heat capacity, which means that the alloy has low heat conduction from the cutting zone. The temperature is strongly depending on the cutting speed, which is the relative speed difference between the cutting tool and the workpiece. Many studies and research work have been conducted surrounding this fact, focusing on the physical and chemical quantities, to model tool wear progression and how this affects the tool life and the metal removal. These models are often implemented and analyzed in finite element software providing detailed but time-consuming solutions.The focus for this work have been on developing a suitable tool life expectancy model, using design of experiments in combination with metamodeling to establish a model connecting cutting parameters and measured responses in terms of tool life, from a conducted milling experiment. This models where supposed to provide a platform for customer recommendation and cutting data optimization to secure reliable machining operations. The study was limited to focus on the common α+β titanium alloy 6Al-4V. The outcome and conclusion for this study, is that the tool life is strongly connected to the choice of cutting speed and the radial width of cut and that these parameters can be predicted by the two models that have been develop in this project. The models ensure the highest possible metal removal rate, to selected parameters.

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  • 39.
    Andersson, Nils
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Lindberg, Samuel
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Dynamisk energieffektivisering med hjälp av elektrokroma fönster i ett svenskt klimat: En fallstudie av en simulerad kontorslokal med geografisk variabilitet.2022Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Det används stora mängder energi inom kontorslandskap för att reglera inomhusklimatet. Intresset har ökat för energisparande åtgärder både politiskt och privat. För kontorsbyggnader är fönster en stor andel av klimatskärmen vilket har en stor påverkan på värme- och kylvärmeenergin som tillförs in i kontorsbyggnaden.

    Elektrokroma fönster kan, genom att skicka en spänning till ett av fönstrets skikt, aktivt förändra sina egenskaper för att steglöst begränsa solinstrålning i en byggnad.   

    Denna fallstudie är framtagen för att undersöka var och hur elektrokroma fönster kan användas för att effektivisera inomhusklimatet, med betoning på kylbehov, i Sverige.

    Undersökningen gjordes genom att göra flertal simuleringar på en kontorslokal i IDA ICE där lokalen simuleras på olika orter. Orter varieras från norr till söder och från kust till inland. Fönsterfasaden simulerades även i olika väderstreck.

    Resultaten visar att användning av tekniken sänker inkommande värmeenergi genom fönster med runt 60 procent oavsett på omgivande medeltemperatur. Därför motiveras användandet bäst på sydliga fasader och vid orter nära kust eller stora vatten där solvärmelasten är som störst.

     

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  • 40.
    Angele, Kristian
    et al.
    Vattenfall Research & Development AB, Älvkarleby, Sweden.
    Cehlin, Mathias
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy engineering. Vattenfall Research & Development AB, Älvkarleby, Sweden.
    Högström, Carl-Maikel
    Vattenfall Research & Development AB, Älvkarleby, Sweden.
    Odemark, Ylva
    Vattenfall Research & Development AB, Älvkarleby, Sweden.
    Henriksson, Mats
    Vattenfall Research & Development AB, Älvkarleby, Sweden.
    Tinoco, Hernan
    Forsmarks Kraftgrupp AB, Östhammar, Sweden.
    Lindqvist, Hans
    Forsmarks Kraftgrupp AB, Östhammar, Sweden.
    Hemström, Bengt
    Vattenfall Research & Development AB, Älvkarleby, Sweden.
    Flow Mixing Inside a Control-Rod Guide Tube: Part 2—Experimental Tests and CFD-Simulations2010In: 18th International Conference on Nuclear Engineering: Volume 4, Parts A and B, 2010, p. 655-663Conference paper (Refereed)
    Abstract [en]

    Alarge number of control rod cracks were detected during therefuelling outage of the twin reactors Oskarshamn 3 and Forsmark3 in the fall of 2008. The extensive damage investigationfinally lead to the restart of both reactors at theend of 2008 under the condition that further studies wouldbe conducted in order to clarify all remaining matters. Also,all control rods were inserted 14% in order to locatethe welding region of the control rod stem away fromthe thermal mixing region of the flow. Unfortunately, this measureled to new cracks a few months later due toa combination of surface finish of the new stems andthe changed flow conditions after the partial insertion of thecontrol rods. The experimental evidence reported here shows an increasein the extension of the mixing region and in theintensity of the thermal fluctuations. As a part of thecomplementary work associated with the restart of the reactors, andto verify the CFD simulations, experimental work of the flowin the annular region formed by the guide tube andcontrol rod stem was carried out. Two full-scale setups weredeveloped, one in a Plexiglass model at atmospheric conditions (inorder to be able to visualize the mixing process) andone in a steel model to allow for a highertemperature difference and heating of the control rod guide tube.The experimental results corroborate the general information obtained through CFDsimulations, namely that the mixing region between the cold crud-removalflow and warm by-pass flow is perturbed by flow structurescoming from above. The process is characterized by low frequent,high amplitude temperature fluctuations. The process is basically hydrodynamic, causedby the downward transport of flow structures originated at theupper bypass inlets. The damping thermal effects through buoyancy isof secondary importance, as also the scaling analysis shows, howevera slight damping of the temperature fluctuations can be seendue to natural convection due to a pre-heating of thecold crud-removal flow. The comparison between numerical and experimental resultsshows a rather good agreement, indicating that experiments with plantconditions are not necessary since, through the existing scaling lawsand CFD-calculations, the obtained results may be extrapolated to plantconditions. The problem of conjugate heat transfer has not yetbeen addressed experimentally since complex and difficult measurements of theheat transfer have to be carried out. This type ofmeasurements constitutes one of the main challenges to be dealtwith in the future work.

  • 41.
    Angele, Kristian
    et al.
    Vattenfall Research & Development AB, Älvkarleby, Sweden.
    Odemark, Ylva
    Vattenfall Research & Development AB, Älvkarleby, Sweden.
    Cehlin, Mathias
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy engineering. Vattenfall Research & Development AB, Älvkarleby, Sweden.
    Hemström, Bengt
    Vattenfall Research & Development AB, Älvkarleby, Sweden.
    Högström, Carl-Maikel
    Vattenfall Research & Development AB, Älvkarleby, Sweden.
    Henriksson, Mats
    Vattenfall Research & Development AB, Älvkarleby, Sweden.
    Tinoco, Hernan
    Forsmarks Kraftgrupp AB, Östhammar, Sweden.
    Lindqvist, Hans
    Forsmarks Kraftgrupp AB, Östhammar, Sweden.
    Flow mixing inside a control-rod guide tube: Experimental tests and CFD simulations2011In: Nuclear Engineering and Design, ISSN 0029-5493, E-ISSN 1872-759X, Vol. 241, no 12, p. 4803-4812Article in journal (Refereed)
  • 42.
    Anton, Raul
    et al.
    TECNUN, University of Navarra, Navarra, Spain.
    Jonsson, Hans
    Royal Institute of Technology (KTH), Stockholm, Sweden.
    Moshfegh, Bahram
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik. Division of Energy Systems, Department of Management and Engineering, Linköping University, Linköping.
    Compact CFD Modeling of EMC screen for radio base stations: a porous media approach and a correlation for the directional loss coefficients2007In: IEEE transactions on components and packaging technologies (Print), ISSN 1521-3331, E-ISSN 1557-9972, Vol. 30, no 4, p. 875-885Article in journal (Refereed)
    Abstract [en]

    A methodology to obtain the directional pressure loss coefficients in a porous media model of an electromagnetically compatible screen of a radio base station model is presented. The directional loss coefficients of this compact model are validated against a detailed computational fluid dynamics model not only by comparing the total pressure drop, but also by evaluating the flow pattern after the screen. The detailed model was validated in an earlier article by the authors. A parametric study is conducted for 174 cases. Seven parameters were investigated: velocity, inlet height, screen porosity, printed circuit board (PCB) thickness, inlet-screen gap, distance between two PCBs and screen thickness. Based on the compact model parametric study, two correlations for the directional loss coefficients are developed as a function of the Reynolds number and the above geometrical parameters. The average disagreement between the compact model that uses the directional loss coefficients from the correlations and the detailed model was of 3% for the prediction of the total pressure drop and less than 6.5% and 9.5% for two coefficients that accurately characterize the flow pattern.

  • 43.
    Antoniou, Nestoras
    et al.
    Department of Civil and Environmental Engineering, University of Cyprus, Nicosia, Cyprus; Department of the Built Environment, Eindhoven University of Technology, Eindhoven, The Netherlands.
    Montazeri, Hamid
    Department of the Built Environment, Eindhoven University of Technology, Eindhoven, The Netherlands; Department of Civil Engineering, KU Leuven, Leuven, Belgium.
    Wigö, Hans
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Neophytou, Marina
    Department of Civil and Environmental Engineering, University of Cyprus, Nicosia, Cyprus.
    Blocken, Bert
    Department of the Built Environment, Eindhoven University of Technology, Eindhoven, The Netherlands; Department of Civil Engineering, KU Leuven, Leuven, Belgium.
    Sandberg, Mats
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    CFD and wind-tunnel analysis of outdoor ventilation in a real compact heterogeneous urban area: evaluation using “air delay”2017In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 126, p. 355-372Article in journal (Refereed)
    Abstract [en]

    Outdoor urban ventilation in a real complex urban area is investigated by introducing a new ventilation indicator – the "air delay". Computational Fluid Dynamics (CFD) simulations are performed using the 3D steady Reynolds-Averaged Navier-Stokes (RANS) and Large Eddy Simulation (LES) approaches. The up-to-date literature shows the lack of detailed evaluations of the two approaches for real compact urban areas. This study further presents a systematic evaluation of steady RANS and LES for the assessment of the ventilation conditions in a dense district in Nicosia, Cyprus. The ventilation conditions within the urban area are investigated by calculating the distribution of the age of air. To better assess the outdoor ventilation, a new indicator, the "air delay" is introduced as the difference between the local mean age of air at an urban area and that in an empty domain with the same computational settings, allowing the comparison of the results in different parts of the domain, without impact of the boundary conditions. CFD results are validated using wind-tunnel measurements of mean wind speed and turbulence intensity performed for the same urban area. The results show that LES can accurately predict the mean wind speed and turbulence intensity with the average deviations of about 6% and 14%, respectively, from the wind-tunnel measurements while for the steady RANS, these are 8% and 31%, respectively. The steady RANS simulations overestimate the local mean air delay. The deviation between the two approaches is 52% at pedestrian level (2 m).

  • 44.
    Antón, Raúl
    et al.
    Department of TECNUN, University of Navarra, Navarra, Spain.
    Jonsson, Hans
    Royal Institute of Technology, Stockholm.
    Moshfegh, Bahram
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik. Division of Energy Systems, Department of Management and En- gineering, Linköping University, Linköping, Sweden.
    Detailed CFD modeling of EMC screen for radio base stations: a benchmark study2007In: IEEE transactions on components and packaging technologies (Print), ISSN 1521-3331, E-ISSN 1557-9972, Vol. 30, no 4, p. 754-763Article in journal (Refereed)
    Abstract [en]

    The objective of this paper is to investigate the performance of five well-known turbulence models, in order to find a model that predicts the details of the flow patterns through an electromagnetic compatibility (EMC) screen. The turbulence models investigated in the present study are five different eddy-viscosity models; the standard k-epsilon model, the renormalization group (RNG) k-epsilon model, the realizable k-epsilon model, the standard k-omega model, as well as the shear stress transport k-w model. A steady-state 3-D detailed model, which serves as the most accurate representation of the model, was used in order to evaluate the details of the airflow paths and pressure field. The flow was assumed to be isothermal, turbulent and incompressible. A general model that covers a considerable range of velocities and geometries was validated experimentally by wind tunnel measurements. The result shows that for most of the k-epsilon models used with correct y(+) and mesh strategy, the pressure drop and the velocity field deviation is small compared to experimental data. The k-omega models overpredict the overall pressure drop. When using the RNG k-epsilon model, the total static pressure drop predicted differs around 5%-10% and the average velocity deviation at several locations before and after the screen is around 5%.

  • 45.
    Apell, Oscar
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Energikartläggning av Fridhemsskolan 16:22014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Increased energy consumption in the world has created an increased supply of various fuels, especially fossil fuels. The Swedish government has set up various energy targets for 2020. To reach these goals it’s important to increase the energy efficiency in local buildings such as schools. This work illustrates the breakdown between energy supply and energy losses over the school. It also shows various suggestions to reduce the energy usage. The results shows that energy losses from transmission is definitely the greatest. Significant savings can be made by replacing windows, add insulation and install motion sensor lightning. If the proposed savings would be made, the energy consumption of the school could decrease by approximately 165MWh/year. This represent an annual saving of about 123600 SEK.

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  • 46.
    Arfan, Muhammad
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science. 202100-2890.
    Biogas Value Chain in Gävleborg: Feedstock, Production and Use2019Report (Other academic)
    Abstract [en]

    This report aims to identify the current status and future opportunities for biogas as an alternative fuel for road transport in the Gävleborg region. The regional actors along the value chain are mapped by their role in feedstock supply, production and use of the biogas. Mapping and analysis of biogas development generally in Sweden and particularly in the Gävleborg region has been conducted primarily through literature, national and regional statistics and through interviews with the regional actors. About 15 companies were reached through emails and phone calls during the interview process.

    In 2017, about 3.5-4.0 million Nm3 of raw biogas (50-65% CH4) was produced in the region of which 3.6 GWh was upgraded. The region has two plants with upgrading facilities, one in Forsbacka, which produces gas mainly from food waste and Duvbacken, the wastewater treatment plant in Gävle. The gas produced at these two big facilities is upgraded and mostly used as transport fuel in the region, and for the industry. Gas produced from other sources is either used for heat and electricity production or flared to avoid methane emissions to the environment. The region has 14 buses and more than 500 other vehicles running on biogas. The gas infrastructure is not well developed in the region except for two filling stations situated in Gävle and Forsbacka. However, some developments on building biogas infrastructure for transport are in process.

    Analysis of interviews with actors and literature studies revealed that the region has much more feedstock for biogas production than used in the currently installed capacity of biogas technologies. Many actors showed great interest in its use as transport fuel but had very serious concerns about its future scope. Lack of supporting infrastructure such as filling stations, very low market demand and regional long-term strategies on biogas as transport fuel are considered barriers in the sector´s further development in the region. The value chain actors need to work more closely to get the most out of this valuable resource. Additionally, future planning on biogas should also consider its other uses such as an energy source for manufacturing industry, shipping and as raw material for chemicals or intermediate products.

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  • 47.
    Arizcun Zúñiga, Paula María
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Ram pump hydraulic air test. Pressure conditions and flow measurements: Experimental research and case study2018Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This study consists of the development of a ram pump, which will allow the pumping of water without the need of external energy sources. It is considered an analysis of interest since, once it is finished; it can be applied in reality improving and facilitating different activities related to agriculture and health.

    Previous studies have been made related to the ram pump; however, in this case, it is intended to understand the system that has been built in the laboratory in order to find the best combination of parameters that will lead to obtain the highest possible efficiency. 

    The study will be carried out by studying scientific literature and by experimenting in the laboratory. Encompassing the experimental and literary field, it is expected to understand perfectly the advantages and disadvantages of the ram pump in order to determine if it is worth it to install in certain places.

    After the study, the most favourable parameters for the operation of the Bruzaholms Bruk pump have been obtained. It has been found that the use of a longer drive pipe favours the operation of the system, as it is possible to obtain a higher efficiency, although it must be taken into account that the mentioned length needs to be controlled, as it could reduce the working rhythm of the pump. It has also been seen that the pump gives better results if the impulse valve is completely opened. Finally, it has been proven that, as long as the height difference between the two tanks is enough, increasing the height of the water source will favour the operation of the system.

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  • 48.
    Arnfelt, Emma
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    En byggnads energiprestanda: En utredande och jämförande studie av Boverkets författningssamling BEN12017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report is an exploratory and comparative study of Boverkets constitution BEN1. In this study the constitution BEN1 is examined, why the constitution was established, when is it applicable and what advantages and disadvantages will come with it. Today the housing and service sector is using a major part of Europe’s final energy use, in addition to this, these sectors also represents a major part of the total carbon dioxide emissions. The EU-commission aims to reduce the housing and service sectors energy use and emissions. In 2002 the European parliament established directives and demands for buildings energy performance. These directives were changed in 2009-2010, which led to an inspection of the already existing Swedish constitution, this was found to be inadequate by the EU-commission. Sweden decided to create a new constitution in order to satisfy EU’s new directives and demands. The focus is on a normal usage of the building in a normal year in the new constitution, BEN1. 

    The reader should receive an idea and understanding about BEN1 and why it was established in this report. Beyond this, the study will show the changes that happen to a buildings energy performance after the constitution is applied and what advantages and disadvantages this could bring. 

    This study was performed by simulating the buildings energy use with the input from BEN1 in a simulation tool, IDA Indoor Climate and Energy. 

    The study shows that the energy performance will change but it also shows that further studies should be made in order to obtain a more carefully drawn and common conclusion.

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    En byggnads energiprestanda
  • 49.
    Arushanyan, Yevgeniya
    et al.
    Division of Environmental Strategies Research, Department of Sustainable development, Environmental Science and Engineering, School of Architecture and Built Environment, KTH Royal Institute of Technology, Stockholm, Sweden.
    Bjorklund, Anna
    Division of Environmental Strategies Research, Department of Sustainable development, Environmental Science and Engineering, School of Architecture and Built Environment, KTH Royal Institute of Technology, Stockholm, Sweden.
    Eriksson, Ola
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Environmental engineering.
    Finnveden, Göran
    Division of Environmental Strategies Research, Department of Sustainable development, Environmental Science and Engineering, School of Architecture and Built Environment, KTH Royal Institute of Technology, Stockholm, Sweden.
    Soderman, Maria Ljunggren
    Division of Environmental Systems Analysis, Department of Energy and Environment, Chalmers University of Technology, Göteborg, Sweden.
    Sundqvist, Jan-Olov
    IVL Swedish Environmental Research Institute, Stockholm, Sweden.
    Stenmarck, Åsa
    IVL Swedish Environmental Research Institute, Stockholm, Sweden.
    Environmental Assessment of Possible Future Waste Management Scenarios2017In: Energies, E-ISSN 1996-1073, Vol. 10, no 2, article id 247Article in journal (Refereed)
    Abstract [en]

    Waste management has developed in many countries and will continue to do so. Changes towards increased recovery of resources in order to meet climate targets and for society to transition to a circular economy are important driving forces. Scenarios are important tools for planning and assessing possible future developments and policies. This paper presents a comprehensive life cycle assessment (LCA) model for environmental assessments of scenarios and waste management policy instruments. It is unique by including almost all waste flows in a country and also allow for including waste prevention. The results show that the environmental impacts from future waste management scenarios in Sweden can differ a lot. Waste management will continue to contribute with environmental benefits, but less so in the more sustainable future scenarios, since the surrounding energy and transportation systems will be less polluting and also because less waste will be produced. Valuation results indicate that climate change, human toxicity and resource depletion are the most important environmental impact categories for the Swedish waste management system. Emissions of fossil CO2 from waste incineration will continue to be a major source of environmental impacts in these scenarios. The model is used for analyzing environmental impacts of several policy instruments including weight based collection fee, incineration tax, a resource tax and inclusion of waste in a green electricity certification system. The effect of the studied policy instruments in isolation are in most cases limited, suggesting that stronger policy instruments as well as combinations are necessary to reach policy goals as set out in for example the EU action plan on circular economy.

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  • 50.
    Ascic, Ivana
    et al.
    Jönköping University.
    Ascic, Josip
    Jönköping University.
    Hilletofth, Per
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Management, Industrial Design and Mechanical Engineering, Industrial Management. University of Gävle, Center for Logistics and Innovative Production. Jönköping University.
    Pimenta, Marcio Lopes
    Federal University of Uberlandia, Brazil.
    Hilmola, Olli-Pekka
    LUT University, Finland; Estonian Maritime Academy, Tallinn University of Technology (Taltech).
    An evaluation of critical capabilities and improvement areas for competitive manufacturing in a developed country environment2022In: Sustainability, E-ISSN 2071-1050, Vol. 14, no 11, article id 6678Article in journal (Refereed)
    Abstract [en]

    This research evaluates the critical capabilities and improvement areas for competitive manufacturing in a developed-country environment. A multiple-case-study approach is applied, consisting of three manufacturing firms located in Sweden. The case study combines both quantitative and qualitative evaluations of the critical capabilities found in the extant literature. The research reveals fifteen critical capabilities and sixteen improvement areas for competitive manufacturing in a developed-country environment. The results show that the firms develop capabilities in a cumulative manner, starting with cost and quality, continuing with time and flexibility, and finally trying to improve innovation and sustainability. To develop competitive manufacturing operations in developed counties, it is therefore vital to improve capabilities related to time, flexibility, innovation, or sustainability. Irrespective of the targeted capabilities, they must contribute to cost-efficient operations and high quality must always be maintained. The efforts to develop capabilities related to innovation and sustainability may be expensive in the short term, however they can provide better cumulative results and competitiveness in the long term. 

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