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  • 1.
    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, 496-506 p.Article 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.

  • 2.
    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, 875-885 p.Article 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.

  • 3.
    Antón, Raul
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik. Department of Mechanical Engineering, TECNUN, University of Navarra, Navarra, Spain; Division of Applied Thermodynamics and Refrigeration, KTH Energy Technology, Royal Institute of Technology, Stockholm, Sweden.
    Jonsson, Hans
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik. Division of Applied Thermodynamics and Refrigeration, KTH Energy Technology, Royal Institute of Technology, Stockholm, Sweden.
    Moshfegh, Bahram
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Detailed CFD Modelling of EMC Screens for Radio Base Stations: A Parametric Study2009In: IEEE transactions on components and packaging technologies (Print), ISSN 1521-3331, E-ISSN 1557-9972, Vol. 32, no 1, 145-155 p.Article in journal (Refereed)
    Abstract [en]

    The objective of this paper is to make a parametric study of the hydraulic resistance and flow pattern of the flow after an electromagnetic compatibility screen and between two printed circuit boards (PCBs) in a model of a 90 degrees subrack cooling architecture. The parametric study is carried out using a detailed 3-D model of a PCB slot. The detailed model was experimentally validated in a previous paper by the authors. Seven parameters were investigated: velocity, inlet height, screen porosity, PCB thickness, distance between two PCBs, inlet-screen gap and screen thickness. A correlation for the static and dynamic pressure drop, the percentage of dimensionless wetted area, A(omega)*, and the RMS* factor (a function of the How uniformity along the PCB) after the screen is reported as a function of six geometrical dimensionless parameters and the Reynolds number. The correlations, that are based on 174 three dimensional simulations, yield good results for the total pressure drop, in which the values are predicted within the interval of +/- 15%. For the, A(omega)*, all the predicted values are within the interval of +/- 22% of the observed values. Finally, for the RMS* factor, the majority of the values also have a disagreement of less than 20% of the observed values. These last two parameters are believed to provide a correct insight about the flow pattern after the screen.

  • 4.
    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, 754-763 p.Article 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%.

  • 5.
    Antón, Raúl
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik. Royal Institute of Technology, Stockholm, Sweden; TECHUN, University of Navarra, San Sebastián, Spain.
    Jonsson, Hans
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik. Royal Institute of Technology, Stockholm, Sweden.
    Moshfegh, Bahram
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Detailed CFD modelling of EMC screen for radio base stations: A conjugate heat transfer problem2007In: International Journal of Heat Exchangers, ISSN 1524-5608, Vol. 8, no 1, 95-116 p.Article in journal (Refereed)
    Abstract [en]

    The objective of this paper is to perform an experimental as well as CFD investigations of the conjugate heat transfer problem in a sub-rack slot model. A steady-state three-dimensional 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 temperature field. A general model that covers a considerable range of velocities, screen porosities and heat fluxes was validated experimentally by wind tunnel measurements. The result shows that the RNG k-ε model used with correct y+ and mesh strategy accurately predicts the temperature field. The average temperature deviation at several locations is less than 4% compared to experimental data. The influence of the velocity, screen porosity, heat flux and presence of the EMC screen on the PCB temperature field is commented. © 2007 R.T. Edwards, Inc.

  • 6.
    Antón Remírez, Raúl
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Experimental and numerical study of the thermal and hydraulic effect of EMC screens in radio base stations: detailed and compact model2006Doctoral thesis, monograph (Other scientific)
    Abstract [en]

    Today’s telecommunication cabinets use Electro Magnetic Compliance (EMC) screens in order to reduce electromagnetic noise that can cause some miss functions in electronic equipment.

    Many radio base stations (RBSs) use a 90-degree building architecture: the flow inlet is perpendicular to the EMC screen, which creates a complex flow, with a 90-degree air turn, expansions, compressions, perforated plates and PCBs. It is of great interest to study how the EMC screen interacts with the rest of components and analyze the total pressure drop and how much the flow pattern changes due to the placement of the screen.

    Velocity, pressure and temperature measurements as well as flow pattern visualizations have been carried out to gain good insight into the flow and heat transfer characteristics in a subrack model of an RBS. Furthermore, these measurements have been very useful for validating detailed CFD models and evaluating several turbulence models.

    Nowadays, industrial competition has caused a substantial decrease in the time-to-market of products. This fact makes the use of compact models in the first stages of the design process of vital importance. Accurate and fast compact models can to a great extent decrease the time for design, and thus for production.

    Hence, to determine the correlations between the pressure drop and flow pattern on the PCBs as a function of the geometry and the Reynolds number, based on a detailed CFD parametric study, was one objective. Furthermore, the development of a compact model using a porous media approach (using two directional-loss coefficients) has been accomplished. Two correlations of these directional loss coefficients were found as a function of the geometry and Reynolds number.

  • 7.
    Batti, Erich
    University of Gävle, Department of Technology and Built Environment. University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Fjärrkyla till Gävletätort: temperaturberäkningar av distributionsledningar2008Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    In recent year, the need of providing buildings with cooling has increased, especially in offices there the used electrical equipment in the form of computers, lighting and other electrical equipment. In order to chill away the heat that is given from these equipments used for current old chill machines that are owned by real-estate owners in Gävle. Instead in order to change or to fulfil these machines with environment dangerous cold mediums come the thought with providing Gävle with district chill which is a distinguished alternatives and concurrent is environmentally friendly.

     

    The most front aim with this work has been to do temperature calculations around distribution pipes that will be placed on bottom of Gavleån without bigger complications such as isolated pipes and digging for steam disposition, and to convert an assessment if this is possible. Another aim was to do pressure case calculations on these pipes. The work is provided of SWECO-THEORELLS in Gävle, the company had already done temperature calculations, and the work was allocated also in order to compare the results.

     

    The temperature calculations were resort to heat transfer's principles on swiftly-flowing fluid bodies, this in order that the pipes are surrounded by streaming water. The water temperature was assumed to 20ºC that is huge heavily assumption in order to last on a depth up to 6m. The conclusive temperature to the heat bills of exchange is 5.5ºC.

     

    The pressure case calculations were done in one MICROSOFT-EXCEL document, the starting points each one previous course during the education's time that was called energy resources which facilitated calculations.

     

    Arrived results hopefully will lie to shallow for a continued work and an execution of these planning's.

     

    The following results have been brought about:

    • A temperature on 5.8ºC is received to long away located subscriber at 20ºC hot water
    • 203 kPa pressure case on flow into, only distribution pipes

     

     

     

     

     

    The following conclusions could be extracted:

    • A certain difference was detected between earlier calculations, since considerations been taken to extreme relations so decreases this difference's importance
    • Reduction of water flow during the summer mean one risk while spirit that does the delivery of desired temperature uncertain, special during the hottest days

    That estimated available pressures will not cover the need in accordance with calculations performed in this work

  • 8.
    Blanco Gabilondo, Maitane
    University of Gävle, Department of Technology and Built Environment. University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    STUDY THE ENERGY SYSTEM OF THE AUTONOMOUS COMMUNITY OF THE BASQUE COUNTRY.2009Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
  • 9.
    Blomqvist, Per
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik. University of Gävle, Department of Technology and Built Environment.
    Bygelstolpar: Kraft- och spänningsanalys av bygelstolpar tillhörande Bruks mobila hugg 805 CT2009Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report is the result of a thesis as been implemented during the spring term 2009 at

    the University of Gävle.

    The company Bruks produces mobile chippers which are used for chipping logging

    slash, roundwood and parts of trees. The chipper is powered by a separate diesel engine

    and the chipper can be assembled on trucks, trailers or some other carrier vehicles.

    When the chip has passed the chipper drum, the chip is collected in an integrated bin

    which is mounted on the vehicles frame with dumping yokes. When these dumping

    yokes were designed they were probably created with large material dimensions. The

    aim with the degree project is hence to study the strengths of materials and, if possible,

    to suggest an arrangement that can decrease the total weight on the dumping yoke on

    Bruks´ mobile chippers 805 CT.

    The CAD-program Pro/ENGINEER was used during the project for outlining the 2Ddrawings,

    as distributed of constructors on Bruks, to solid 3D-parts. The three-dimensional

    assembly from Pro/ENGINEER was transferred to Pro/MECHANICA. The construction is

    complex and contains many components, and therefore the model has been divided into two

    different parts, the external and the internal dumping yoke.

    The conclusion of the degree project is that the product generally is not over dimensioned.

    However there are many options for optimizing, mainly on the external dumping yokes.

  • 10.
    Cai, Jie
    University of Gävle, Department of Technology and Built Environment. University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Hydropower in China2009Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
  • 11.
    Cehlin, Mathias
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Visualization of Airflow, Temperature and Concentration Indoors: whole-field measuring methods and CFD2006Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

     

    The thermal indoor climate is a complicated combination of a number of physical variables, all of which strongly affect people’s well-being. The indoor climate not only heavily affects people’s health and life quality, but also their productivity and ability to work efficiently.

    One of the reasons why so many problems are associated with indoor climate is that it is more or less invisible; it is hard to understand something that cannot be seen. In particular, the near-zone of supply air diffusers in displacement ventilation is very critical. Complaints about drafts are often associated with this type of ventilation system.

    The main aim of this research is to improve the knowledge of the whole-field techniques used to measure and visualize air temperatures and pollutant concentrations. These methods are explored with respect to applicability and reliability. Computational Fluid Dynamics (CFD) has been used to predict the velocity and temperature distributions and to improve the current limitations.

    Infrared thermography is an excellent technique for visualization of air temperature and airflow pattern, particular in areas with high temperature gradient, such as close to diffusers. It is applicable to both laboratory and field test environments, such as in industries and workplaces. For quantitative measurements the recorded temperatures must be corrected for radiation heat exchange with the environment, a complicated task since knowledge about the local heat transfer coefficients, view factors and surrounding surfaces are needed to be known with good accuracy.

    Computed tomography together with optical sensing is a promising tool in order to study the dispersion of airborne pollutants in buildings. However, the design of the optical sensing configuration and the reconstruction algorithm has a major influence on the performance of this whole-field measuring technique. A Bayesian approach seems to be a rational choice for reconstruction of pollutant concentration indoors, since it avoids the high noise sensitivity frequently encountered with many other reconstruction methods. A modified Low Third Derivative (LTD) method has been proposed in this work that performs well particular for concentration distributions containing steep gradients and regions with very low concentrations.

    CFD simulation is a powerful tool for visualization of velocities, airflow pattern and temperature distribution in rooms. However, for predictions of the absolute value of the physical variables the CFD model have to be validated against some reference case with high quality experimental data. CFD predictions of air temperatures and velocities close to a complex supply diffuser are very troublesome. The performance of CFD prediction of the airflow close to a complex supply diffuser depends mainly on the accuracy of the diffuser, turbulence and wall treatment modeling

  • 12.
    Cehlin, Mathias
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Karlsson, Fredrik
    Linköping Universitet.
    Komfort- och inomhusmiljökonsekvenser av strukturerad energieffektivisering av vårdlokaler2009Report (Other academic)
  • 13.
    Cehlin, Mathias
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Moshfegh, Bahram
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Visualization of Isothermal Low-Reynolds Circular Air Jet Using Computed Tomography.2005In: Proceedings of 6 th World Conference on Experimental Heat Transfer, Fluid Mechanics, and Thermodynamics, 2005Conference paper (Refereed)
    Abstract [en]

    The intention of this paper was to demonstrate the principle and usefulness of computed tomography for concentration field measurements. Radial extinction coefficient profiles have been reconstructed using the LTD approach in the transition region of an isothermal jet of air at Reynolds number of 2 600. Reconstructed profiles were compared against velocity profiles at axial distances ranging from 2 to 20 nozzle diameters downstream. Results indicate that the width parameter of the reconstructed scalar distribution is around 23 % larger than the velocity distribution for distances between 10 and 20 nozzle diameters downstream. This finding is in good agreement with the results of other investigators. This technique has evidently yielded an accurate description of the scalar field of the round isothermal free jet.

    The quality of the reconstructions is very promising considering the relatively few measurement data, projection angles and low pixel resolution used in this study.

    Ccomputed tomography is superior for monitoring chemical concentrations over larger areas (whole room) when PMS and PLIF are unfeasible.

  • 14.
    Cehlin, Mathias
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Moshfegh, Bahram
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Karlsson, Fredrik
    Larsson, Ulf
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Analysis on Thermal Comfort for a Hospital Building by Multi-zone Modeling: Summer Condition2008In: Proceedings of World Renewable Energy Congress X, 2008Conference paper (Refereed)
  • 15.
    Cehlin, Mathias
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Moshfegh, Bahram
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Stymne, Hans
    Mapping of Indoor Climate Parameters in Volvo, Eskilstuna2000Report (Other academic)
  • 16.
    Cehlin, Mathias
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Sandberg, Mats
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Computed tomography for indoor application2006In: The International Journal of Ventilation, ISSN 1473-3315, Vol. 4, no 4, 349-364 p.Article in journal (Refereed)
    Abstract [en]

    This paper deals with tomographic techniques for two-dimensional spatially resolved concentration measurements indoors. This represents a significant advance over the traditional point measuring method for mapping tracer gas and pollutants. Methods for recording of data are stressed as well as different types of tomographic reconstruction algorithms such as the Smooth Basis Function Minimization (SBFM) and the modified Low Third Derivative (LTDm) methods. Among the reconstruction algorithms available today, SBFM and LTDm are among the most promising. These algorithms show potential for reconstruction of gas concentration in rooms, since they are regularized to converge towards smooth concentration distributions. Using the LTD method and ‘snapshot’ configuration enables the examination and real-time monitoring of transient flows.

  • 17.
    Cehlin, Mathias
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Sandberg, Mats
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Computed Tomography for Indoor Applications2006In: The International Journal of Ventilation, ISSN 1473-3315, E-ISSN 2044-4044, Vol. 4, no 4, 349-364 p.Article in journal (Other academic)
    Abstract [en]

    This paper deals with tomographic techniques for two-dimensional spatially resolved concentration measurements indoors. This represents a significant advance over the traditional point measuring method for mapping tracer gas and pollutants. Methods for recording of data are stressed as well as different types of tomographic reconstruction algorithms such as the Smooth Basis Function Minimization (SBFM) and the modified Low Third Derivative (LTDm) methods. Among the reconstruction algorithms available today, SBFM and LTDm are among the most promising. These algorithms show potential for reconstruction of gas concentration in rooms, since they are regularized to converge towards smooth concentration distributions. Using the LTD method and ‘snapshot’ configuration enables the examination and real-time monitoring of transient flows.

  • 18.
    Cehlin, Mathias
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Sandberg, Mats
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Time evolution of gravity currents discharged from low velocity diffusers2007In: Roomvent 2007, 2007, 61-70 p.Conference paper (Refereed)
  • 19.
    Cehlin, Mathias
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Sandberg, Mats
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Time evolution of gravity currents discharged from low velocity diffusers2007In: Roomvent 2007: 10th International Conference on Air Distribution in Rooms, 13-15 June 2007, Helsinki, Finland, 2007, Vol. 3 61-70 p.Conference paper (Refereed)
  • 20.
    DANIERE, Sébastien
    University of Gävle, Department of Technology and Built Environment. University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Energy survey and saving in the ICA maxi Gävle.2009Independent thesis Advanced level (degree of Master (One Year)), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Due to the global warming of the atmosphere it is now time to decrease the consumption of energy. One of the most important consumer is the commercial building area and especialy the supermarket. After a survey of the total consumption and a division into unit process it is possible to find some measures to decrease the global consumption of energy (in the lighting, cooling/freezing and space heating processes).

  • 21.
    Eriksson Enquist, Joel
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik. University of Gävle, Department of Technology and Built Environment.
    China Strategy for ESP Wire: A study of the Chinese market from Sandvik's perspective2008Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Aim: SMT Wire has noticed that their sales of ESP wire are very low in China compared to India. SMT Wire now wonders how they can increase their market share in China.

    Method: Personal interviews, telephone interviews and interactive conversations.

    Result & Conclusions: SMT Wire should work each tier in the supply chain to gain more orders and increase their market share. It is important to have local representation and work close to the customers so that the customers can feel trust for Sandvik and Sandvik’s employees. The market for spiral discharge electrode material is good in China (the annual consumption is about cccc tonnes) and the market will probably be more and more mature for Sandvik’s high quality materials in a couple of years.

    Suggestions for future research: Is it possible to have a more long-term price on the products on the Asia market? How can Sandvik keep its Chinese personnel? How can the Chinese personnel be trained to make contacting new companies easier for them? How can a foreign company create a guanxi-based selling with a high personnel turnover?

    Contribution of the thesis: A strategy that can be adapted for stainless steel wire companies that want to increase their market share in China.

  • 22.
    Guadalfajara, Mateo
    University of Gävle, Department of Technology and Built Environment. University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Interference between supply jet and room surfaces in ventilated room - A model study2009Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 23.
    Hanna, Hanibal
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Konstruktionsförslag på vattensystem till Scanias tillsatsbroms2012Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The aim of the thesis has been to develop a workable proposal on the existing water system between the engine and retarder that is inexpensive and has adjustable mounting, light weight and long life. A retarder is a helping brake and its main task is to reduce wear on the regular brakes.

    To solve this, first a description of the present situation was mapped on the cooling tube. Then, Scania staff was interviewed at the Scania Retarder section and we had a discussion about the company’s previous designs.

    The theories used were Design For Assembly (DFA), Design For Manufacture (DFM), Design For Environment (DFE), Failure Mode and Effect Analysis (FMEA) and Scania Production System (SPS).

    To ensure the type of material and the manufacturing process "out of the box thinking" was made in the construction. The information that emerged was that one could optimize the dimension, possibly amending the existing material and eliminate a bracket on the coolant pipe. The aim of this design is not only to obtain a cheaper and lighter construction but it should also be easier to assemble.

    The design proposal is a Cooling Water Pipe with brackets that are made of bent sheet metal and are mounted on rubber tubes in order to damp vibrations. Here I have replaced the welded brackets with mountable brackets that hold the cooling water pipe in place. Furthermore, the thickness of the cooling water pipe was reduced from 2 mm to 1.5 mm and I have retained the existing material SS-EN 1010216, pressure vessel steel, because both aluminium and plastic are not held at the vibrations that were generated in the vehicle. In addition, brackets which hold up the whole construction of the cooling water pipe against the gearbox were redesigned so that they fit the new structure. These brackets were mounted on the gear housing with two M10 screws on each bracket.

    Simulations that were made in the Finite Element Method (FEM) were conducted to investigate the deformations and stresses that occur when the coolant passes through the cooling water pipe and when vibrations arise from engine, pump, wheel or road. Results from analyzes, using finite element, indicate that the most critical stresses are on the round brackets who are holding up the cooling water pipe. The maximum static stress on these brackets is 75 MPa with yield strength of 500MPa. This is considered to be low and not critical.

    However in the dynamic analysis the natural frequency occurred at 162 Hz which is over Scania’s critical range, 150 Hz. To ensure the structural integrity, a prototype should be made and tested in order to authenticate that the safety margin is sufficient and that the natural frequency is within the critical interval.

    The proposal has been presented to the staff at the assembly department and they were positive about this suggestion due to many reasons such as easier installation, reduced installation time, ergonomic mount ability, quality controlled assembly and ability to pre-mount. In addition, the assemblers thought that this design proposal can minimize staffing as a result of the short assembly times.

  • 24.
    Hansson, Niklas
    University of Gävle, Department of Technology and Built Environment. University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Samband vid Brf. Krönet: studier runt en väderstation2009Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The purpose of this thesis is to study and contingently discover some linkage between the most common climate parameters (air temperature, sun, wind, air humidity and air pressure) and the indoor climate. The indoor climate in this thesis is the same as the air-temperature indoor.

    Also a compilation of two studies about NordIQ´s controlling of the heating system and hot water is done.

     

    A major portion of the work has been to compile and study collected data from among other things a weather station.

    During this period (spring) the sun and the outdoor temperature have the greatest impact on the indoor temperature.

     

    A major portion of the energy sector today is about how to use the energy in a more effective way and decrease the emissions. Hopefully this thesis will help in that direction. To use the free energy and reduce for example district heating is one way, not cooling the high indoor temperatures, rather reduce the bought energy.

     

    Another way to take advantage of the energy in a more efficient approach is to increase annealing and reduce the flow in the heating system. That´s something with the aim of NordIQ`s controlling of the heat and hot water.

    The compilation shows that it´s true.

  • 25.
    Holmgren, Kristina
    et al.
    Department of Mechanical Engineering, Division of Energy Systems, Linköping Institute of Technology, Linköping, Sweden.
    Amiri, Shahnaz
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik. Department of Mechanical Engineering, Division of Energy Systems, Linköping Institute of Technology, Linköping, Sweden.
    Internalising external costs of electricity and heat production in a municipal energy system2007In: Energy Policy, ISSN 0301-4215, E-ISSN 1873-6777, Vol. 35, no 10, 5242-5253 p.Article in journal (Refereed)
    Abstract [en]

    Both energy supply and waste treatment give rise to negative effects on the environment, so-called external effects. In this study, monetary values on external costs collected from the EU's ExternE project are used to evaluate inclusion of these costs in comparison with an energy utility perspective including present policy instruments. The studied object is a municipal district heating system with a waste incineration plant as the base supplier of heat. The evaluation concerns fuels used for heat production and total electricity production, for scenarios with external costs included and for a scenario using the present policy instrument. Impacts of assumptions on marginal power producers (coal or natural gas power plants) are investigated, since locally produced electricity is assumed to replace marginal power and thus is credited for the avoided burden. Varying levels of external costs for carbon dioxide emissions are analysed. The method used is an economic optimisation model, MODEST. The conclusion is that present policy instruments are strong incentives for cogeneration, even when external costs are included. Waste is fully utilised in all scenarios. In cases where coal is the marginal power producer, more electricity is produced; when natural gas is the marginal power producer, less is produced. There are several uncertainties in the data for external costs, both methodological and ethical. In the ExternE data, not all environmental impacts are included. For waste incineration, ashes are not included, and another difficulty is how to treat the avoided burden of other waste treatment methods. 

  • 26.
    Holmström, Susanne
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Fjärrvärmesystem2008Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This is a report written for an examination project C-level, on the subject of energy. The examination project is a product of the FVB Sweden AB (district heating bureau). It started with a meeting with Stefan Jonsson FVB Sweden AB, were he explained the content of the project, and from this a presentation of the problem was made. The problem that needed to be solved was how they could control the valves in the system to provide heating to everyone in the system. The valves are often oversized so the pump in the heating plant would have to be enormous to be able to provide enough flow to be sufficient, if everyone in the system had there valves fully opened.

     

    I came up with two solutions to the problem, one was a wireless network that could keep track of the valves and the other solution was an extra sensor that was placed on the radiator. The purpose for that was to open the valve if the temperature dropped more than one degree inside. With the help of a program called IDA it was calculated that, if the temperature drop five degrees, they would have sixteen hours at the heating power plant to open the flow before the sensor open the valves.

     

    After careful consideration I came up with the conclusion that the wireless network must be the best solution. Mostly because you can monitor all the clients in the system from the heating power plant and that will make it easier to discover faults and temperature differences.

    Wireless networks is already a well tested solution in form of wireless controlled electricity meters so it shouldn’t be to much of a problem connecting these sensors to it either.

  • 27.
    Janbakhsh, Setareh
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Moshfegh, Bahram
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Experimental investigation of a new supply diffuser in an office room2009Conference paper (Refereed)
  • 28.
    Janbakhsh, Setareh
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Moshfegh, Bahram
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Tutkimus toimistohuoneen ilmanvaihdon toiminnasta kerrostavan ilmanvaihdon tuloilmalaitteella2009Conference paper (Refereed)
  • 29.
    Karimipanah, Taghi
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik. Faculty of Engineering and Sustainable Development.
    Awbi, Hazim B.
    University of Reading, UK.
    Performance evaluation of two air distribution systems2001In: Proceedings of 5th International Conference Ventilation for Automotive Industry, 2001Conference paper (Refereed)
    Abstract [en]

    This paper focuses on evaluating the performance of a wall displacement ventilation system and a new impinging jet ventilation system. Ventilation efficiency, local mean age of air and other characteristic parameters were experimentally and numerically obtained for a mock-up classroom. The internal heat load of 25 person-simulators were set to represent a crowded classroom in order to investigate any indoor climate problems caused by increased cooling loads. Four ventilation strategies were compared in a previous paper [1] but here we have chosen only the two systems mentioned. In addition to a large number of costly experiments we used CFD simulations to study certain parameters in more detail and explore the results for other situations such as industrial ventilation. The results presented here are part of a larger search programme to develop alternative and efficient systems for new challenging situations of room airflow distribution.

  • 30.
    Karimipanah, Taghi
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Awbi, Hazim
    University of Reading, UK.
    Bahram, Moshfegh
    Linköping University.
    The Air Distribution Index as an Indicator for Energy Consumption and Performance of Ventilation Systems2008In: Journal of the Human-Environment System, ISSN 1349-7723, Vol. 11, no 2, 77-84 p.Article in journal (Other academic)
    Abstract [en]

    This paper deals with the energy consumption and the evaluation of the performance of air supply systems for a ventilated room involving high- and low-level supplies. The energy performance assessment is based on the airflow rate, which is related to the fan power consumption by achieving the same environmental quality performance for each case. Four different ventilation systems are considered: wall displacement ventilation, confluent jets ventilation, impinging jet ventilation and a high level mixing ventilation system. The ventilation performance of these systems will be examined by means of achieving the same Air Distribution Index (ADI) for different cases.The widely used high-level supplies require much more fan power than those for low-level supplies for achieving the same value of ADI. In addition, the supply velocity, hence the supply dynamic pressure, for a high-level supply is much larger than for low-level supplies. This further increases the power consumption for high-level supply systems.The paper considers these factors and attempts to provide some guidelines on the difference in the energy consumption associated with high and low level air supply systems. This will be useful information for designers and to the authors' knowledge there is a lack of information available in the literature on this area of room air distribution.The energy performance of the above-mentioned ventilation systems has been evaluated on the basis of the fan power consumed which is related to the airflow rate required to provide equivalent indoor environment. The Air Distribution Index (ADI) is used to evaluate the indoor environment produced in the room by the ventilation strategy being used. The results reveal that mixing ventilation requires the highest fan power and the confluent jets ventilation needs the lowest fan power in order to achieve nearly the same value of ADI.

  • 31.
    Karimipanah, Taghi
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik. School of Construction Management and Engineering, University of Reading, United Kingdom.
    Awbi, Hazim
    School of Construction Management and Engineering, University of Reading.
    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 .
    The air distribution as an indicator for energy consumption and performance of ventilation systems2008In: Journal of the Human-Environment System, ISSN 1345-1324, Vol. 11, no 2, 77-84 p.Article in journal (Refereed)
    Abstract [en]

    This paper deals with the energy consumption and the evaluation of the performance of air supply systems for a ventilated room involving high- and low-level supplies. The energy performance assessment is based on the airflow rate, which is related to the fan power consumption by achieving the same environmental quality performance for each case. Four different ventilation systems are considered: wall displacement ventilation, confluent jets ventilation, impinging jet ventilation and a high level mixing ventilation system. The ventilation performance of these systems will be examined by means of achieving the same Air Distribution Index (ADI) for different cases.The widely used high-level supplies require much more fan power than those for low-level supplies for achieving the same value of ADI. In addition, the supply velocity, hence the supply dynamic pressure, for a high-level supply is much larger than for low-level supplies. This further increases the power consumption for high-level supply systems.The paper considers these factors and attempts to provide some guidelines on the difference in the energy consumption associated with high and low level air supply systems. This will be useful information for designers and to the authors' knowledge there is a lack of information available in the literature on this area of room air distribution.The energy performance of the above-mentioned ventilation systems has been evaluated on the basis of the fan power consumed which is related to the airflow rate required to provide equivalent indoor environment. The Air Distribution Index (ADI) is used to evaluate the indoor environment produced in the room by the ventilation strategy being used. The results reveal that mixing ventilation requires the highest fan power and the confluent jets ventilation needs the lowest fan power in order to achieve nearly the same value of ADI.

  • 32.
    Karimipanah, Taghi
    et al.
    Faculty of Engineering and Sustainable Development.
    Moshfegh, Bahram
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    On the performance of confluent jets ventilation system in office space2007In: In Proc. of Roomvent 2007, 10th International Conference on Air Distribution in Rooms, 13-15 June Helsinki, Finland (2007), 2007Conference paper (Refereed)
  • 33.
    Karimipanah, Taghi
    et al.
    Faculty of Engineering and Sustainable Development.
    Moshfegh, Bahram
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Awbi, Hazim
    University of Reading, UK.
    On the energy consumption of high and low-level air suppliers2006Conference paper (Refereed)
  • 34.
    Karlsson, Magnus
    et al.
    Department of Management and Engineering, Division of Energy Systems, Linköping University, Sweden.
    Gebremedhin, Alemayehu
    Department of Management and Engineering, Division of Energy Systems, Linköping University, Sweden.
    Klugman, Sofia
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Henning, Dag
    Optensys Energianalys, Linköping, Sweden.
    Moshfegh, Bahram
    Department of Management and Engineering, Division of Energy Systems, Linköping University, Sweden.
    Regional energy system optimization - Potential for a regional heat market2009In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 86, no 4, 441-451 p.Article in journal (Refereed)
    Abstract [en]

    Energy supply companies and industrial plants are likely to face new situations due to, for example, the introduction of new energy legislation, increased fuel prices and increased environmental awareness. These new prerequisites provide companies with new challenges but also new possibilities from which to benefit. Increased energy efficiency within companies and increased cooperation between different operators are two alternatives to meet the new conditions. A region characterized by a high density of energy-intensive processes is used in this study to find the economic potential of connecting three industrial plants and four energy companies, within three local district heating systems, to a regional heat market, in which different operators provide heat to a joint district heating grid. Also, different investment alternatives are studied. The results show that the economical potential for a heat market amounts to between 5 and 26 million EUR/year with payback times ranging from two to eleven years. However, the investment costs and the net benefit for the total system need to be allotted to the different operators, as they benefit economically to different extents from the introduction of a heat market. It is also shown that the emissions of CO(2) from the joint system would decrease compared to separate operation of the systems. However, the valuation of CO(2) emissions from electricity production is important as the difference of emitted CO(2) between the accounting methods exceeds 650 kton/year for some scenarios. (C) 2008 Elsevier Ltd. All rights reserved.

  • 35.
    Klugman, Sofia
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Karlsson, Magnus
    Department of Mechanical Engineering, Division of Energy Systems, Linköping University, Linköping, Sweden.
    Moshfegh, Bahram
    Department of Mechanical Engineering, Division of Energy Systems, Linköping University, Linköping, Sweden.
    A Scandinavian chemical wood-pulp mill: Part 1. Energy audit aiming at efficiency measures2007In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 84, no 3, 326-339 p.Article in journal (Refereed)
    Abstract [en]

    A Swedish wood-pulp mill is surveyed in terms of energy supply and use in order to determine the energy-saving potential. Conservation measures are of increasing interest to Swedish industry, as energy prices have continued to rise in recent years. The electricity price particularly increased after the deregulation of the Scandinavian electricity market in 1996. The deregulation expanded to all of the EU in July 2004, which may increase the Swedish electricity price further until it reaches the generally higher European price level. Furthermore, oil prices have increased and the emissions trading scheme for CO2 adds to the incentive to reduce oil consumption. The energy system at the surveyed pulp mill is described in terms of electricity and process heat production and use. The total energy-saving potential is estimated and some saving points are identified. The heat that today is wasted at the mill has been surveyed in order to find potential for heat integration or heat export. The result shows that the mill probably could become self-sufficient in electricity. Particularly important in that endeavor is updating old pumps.

  • 36.
    Klugman, Sofia
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Karlsson, Magnus
    Department of Mechanical Engineering, Division of Energy Systems, Linköping University, Linköping, Sweden.
    Moshfegh, Bahram
    Department of Mechanical Engineering, Division of Energy Systems, Linköping University, Linköping, Sweden.
    A Scandinavian chemical wood-pulp mill: Part 2. International and model mills comparison2007In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 84, no 3, 340-350 p.Article in journal (Refereed)
    Abstract [en]

    The energy use at a Swedish chemical wood-pulp mill is compared internationally and for two model mills that aim to use the most efficient available technology. The international comparison is performed between Canadian and Scandinavian pulp-mills on a general level, and on a closer level among eleven Swedish and Finnish non-integrated sulfate pulp-mills, the type of mill considered in the case study. The two model mills that are used for comparison are one Swedish and one Canadian. The Scandinavian pulp-mills are somewhat more energy efficient than the Canadian mills. Still, the variation in energy use is remarkably large among the Scandinavian mills, which indicates that the energy-saving potential is great. If all Swedish freestanding sulfate pulp-mills became as energy efficient as the most efficient Scandinavian mill, electricity savings corresponding to nearly 1% of the national electricity use would be obtained. In the model mills comparison it was found that large amounts of heat could be saved, particularly in the evaporation plant.

  • 37.
    Klugman, Sofia
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Karlsson, Magnus
    Department of Management and Engineering, Division of Energy Systems, Linköping University, Sweden.
    Moshfegh, Bahram
    Department of Management and Engineering, Division of Energy Systems, Linköping University, Sweden.
    A Swedish integrated pulp and paper mill-Energy optimisation and local heat cooperation2009In: Energy Policy, ISSN 0301-4215, E-ISSN 1873-6777, Vol. 37, no 7, 2514-2524 p.Article in journal (Refereed)
    Abstract [en]

    Heat cooperation between industries and district heating companies is often economically and environmentally beneficial. In this paper, energy cooperation between an integrated Swedish pulp and paper mill and two nearby energy companies was analysed through economic optimisations. The synergies of cooperation were evaluated through optimisations with different system perspectives. Three changes of the energy system and combinations of them were analysed. The changes were process integration, extending biofuel boiler and turbine capacity and connection to a local heat market. The results show that the single most promising system change is extending biofuel and turbine capacity. Process integration within the pulp and paper mill would take place through installing evaporation units that yield less excess heat but must in this particular case be combined with extended biofuel combustion capacity in order to be beneficial. Connecting to the local heat market would be beneficial for the pulp and paper mill, while the studied energy company needs to extend its biofuel capacity in order to benefit from the local heat market. Furthermore, the potential of reducing CO(2) emissions through the energy cooperation is shown to be extensive; particularly if biofuel and turbine capacity is increased. (C) 2009 Published by Elsevier Ltd.

  • 38.
    Klugman, Sofia
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Karlsson, Magnus
    Linköpings universitet, Institutionen för konstruktions- och produktionsteknik, Avdelningen för energisystem.
    Moshfegh, Bahram
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    An integrated chemical pulp and paper mill: energy audit and perspectives on regional cooperation2006In: ECOS 2006, 2006, 637-644 p.Conference paper (Other (popular science, discussion, etc.))
    Abstract [en]

    As a case study, an energy audit was performed at an integrated pulp and paper mill. A top-down approach was applied to identify and categorize the use of electricity, steam and hot water and the results of the audit are presented in this paper. Also, the connections and cooperation with both the nearby district heating system and a local steam deliverer, partly owned by the mill, are described. Potential ways to save energy are pointed out and changes in the cooperation are discussed. Moreover, a discussion of how the system can benefit from the taxation structure is presented, as the design of the studied system, in combination with the introduction of tradable green certificates, creates possibilities to exploit such benefits. As a result from this design it is shown that the introduction of these certificates promotes the use of oil to produce electricity.

  • 39.
    Klugman, Sofia
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Karlsson, Magnus
    Department of Mechanical Engineering, Division of Energy Systems, Linköping University, Linköping, Sweden.
    Moshfegh, Bahram
    Department of Mechanical Engineering, Division of Energy Systems, Linköping University, Linköping, Sweden.
    Modeling an industrial energy system: Perspectives on regional heat cooperation2008In: International journal of energy research (Print), ISSN 0363-907X, E-ISSN 1099-114X, Vol. 32, no 9, 793-807 p.Article in journal (Refereed)
    Abstract [en]

    Through energy efficiency measures, it is possible to reduce heat surplus in the Pulp and paper industry. Yet pulp and paper mills situated in Countries with a heat demand for residential and commercial buildings for the major part of the year are potential heat Suppliers. However, striving to utilize the heat within the mills for efficient energy use Could conflict with the delivery of excess heat to a district heating system. As part of a project to optimize a regional energy system, a sulfate pulp mill situated in central Sweden is analyzed, focusing on providing heat and electricity to the mill and its surrounding energy systems. An energy system optimization method based on mixed integer linear programming is used for studying energy system measures on an aggregated level. An extended system, where the mill is integrated in a regional heat market (HM), is evaluated in parallel with the present system. The use of either hot sewage or a heat PUMP for heat deliveries is analyzed along with process integration measures. The benefits of adding a condensing unit to the back-pressure steam turbine are also investigated. The results show that the use of hot sewage or a heat pump for heat deliveries is beneficial only in combination with extended heat deliveries to an HM. Process integration measures are beneficial and even increase the benefit of selling more heat for district heating. Adding a condensing turbine unit is most beneficial in combination with extended heat deliveries and process integration. Copyright (c) 2007 John Wiley & Sons, Ltd.

  • 40.
    Lieyuan, Chen
    et al.
    University of Gävle, Department of Technology and Built Environment. University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Jing, Liang
    University of Gävle, Department of Technology and Built Environment. University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    The district Heating in China2009Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
  • 41.
    Linden, Elisabet
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Cehlin, Mathias
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Sandberg, Mats
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Temperature and velocity measurements on a diffuser for displacement ventilation with whole field methods2000In: The 7th International Conference on Air Distribution in Rooms, 2000Conference paper (Other academic)
  • 42.
    Linden, Elisabet
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Hellström, Jennie
    Cehlin, Mathias
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Sandberg, Mats
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Virtual reality presentation of temperature measurements on a diffuser for displacement ventilation2001In: The 4th International Conference on Indoor Air Quality, Ventilation and Energy Conservation in Buildings, 2001Conference paper (Other academic)
  • 43.
    Lundström, Hans
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Sandberg, Mats
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Moshfegh, Bahram
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Temperature dependence of convective heat transfer from fine wires in air: a comprehensive experimental investigation with application to temperature compensation in hot-wire anemometry2007In: Experimental Thermal and Fluid Science, ISSN 0894-1777, E-ISSN 1879-2286, Vol. 32, no 2, 649-657 p.Article in journal (Refereed)
    Abstract [en]

    Heat transfer from a fine wire to air has been experimentally investigated. High accuracy measurements, where both the air temperature and wire temperature have been varied systematically and independently have made it possible to map the behavior of the heat transfer process for different velocities, air temperatures, and wire temperatures. Based on these results a compensation method is proposed which makes it possible to temperature compensate hot wires of large aspect ratio and at low Reynolds numbers for anemometry measurements with velocity calibration only at one air temperature.

  • 44.
    Midendal, Tomas
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik. University of Gävle, Department of Technology and Built Environment.
    Gustavsson, Johan
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Lastrigg: produktutveckling av rigg för lastning av miljöbränsle2009Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    En hög med bränslebriketter ligger på marken på ett industriområde i Sveg. Det är tillverkaren av dessa som har lagerhållit briketterna på detta sätt och ämnar lasta dessa i sina containrar. Då detta moment inte tillhör den ordinarie produktionen finns en mobil enhet att tillgå för att genomföra inlastningsproceduren. Containern placeras i en rigg som hissar containeröppningen upp i luften varpå en hjullastare matar in briketterna i en transportör. Den förflyttar briketterna upp till containeröppningen vilket leder till att materialet faller ned på containerns botten. Lastningen upplevs inte ske på ett tillfredsställande vis enligt användaren. Detta är utgångspunkten som ligger till grund för detta examensarbete Arbetet har utgått ifrån att skapa en väl lämpad arbetsgång för att utveckla ett konceptförslag och praktisera detta för slutlig utvärdering. Arbetsgången som utvecklades och följdes ledde slutligen fram till ett konceptförslag som uppfyller kundens samtliga krav. Alla ingående metoder bidrog till resultatet och kan därför anses väsentliga för arbetet.

  • 45.
    Moreno Bruned, Natalia
    University of Gävle, Department of Technology and Built Environment. University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    OPTIMIZATION OF A DISTRICT ENERGY SYSTEM IN ZARAGOZA (SPAIN)2009Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 46.
    Nordberg, Jonas
    University of Gävle, Department of Technology and Built Environment. University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Resurssnål klimatisering.: "Som man bygger får man kyla"2008Student thesis
  • 47.
    Olsson, Jonas
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Vindkraftverk: Konstruktion av vindkraftverk2009Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    En idé har väckts, en idé om att skapa sitt egna unika vertikala vindkraftverk som skall gynna intressenter som vill spara pengar på sin el förbrukning. I det här arbetet kommer ett mindre vertikalt vindkraftverks komponenter att presenteras och hur de har utarbetats gentemot beställarens krav och önskemål. Arbetet startade med en informationsinsamling som gav information och kunskap om kommande delarna i arbetet. Denna information har sedan utarbetats inom produktutveckling, analyser och CAD modelleringar för att sedan kunna konstruera komponenterna.

  • 48.
    PANDE, GEETHA
    University of Gävle, Department of Technology and Built Environment. University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    A Case Study of Solar Powered  Cellular Base Stations2009Independent thesis Advanced level (degree of Master (One Year)), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Green power, environment protection and emission reduction are key factors nowadays in the telecom industry. Balancing of these modes while reducing the capital and operational costs are of prime importance.  Cost efficient and reliable supply of electricity for mobile phone base stations must be ensured while expanding the mobile phone network. In this context, solar energy, using sophisticated photovoltaic cell technology, is considered to be playing very important role.

    Currently, companies such as ABI research, Flexenclosure AB, etc believe that the solar powered cellular base stations are capable of transforming the telecom industry into one of the greenest in the world. Hence, lot of research is in progress across the globe to use solar power in telecom industry.

    In this thesis work, the significance of solar power as renewable energy source for cellular base stations is reviewed. Moreover, simulation software called PVSYST4.37 is used not only to obtain an estimate of the cost of generation of solar power for cellular base stations but also to obtain the system parameters such as the number of modules, batteries and inverters needed for designing the solar powered cellular base stations. The simulations were carried out for the Grid-Connected and the Stand-Alone solar power systems by considering the cases of New Delhi, India and Stockholm, Sweden.

    The PVSYST4.37 simulation results shows that the power generation costs for the grid connected solar powered system is less compare to standalone solar powered system both in New Delhi, India as well as in Stockholm, Sweden.

     

  • 49.
    Rodriguez, Ramon
    et al.
    University of Gävle, Department of Technology and Built Environment. University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Sanchéz Pamplona, David
    University of Gävle, Department of Technology and Built Environment. University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    DYNAMIC MODELING OF HYBRID PV/THERMAL SOLAR SYSTEM FOR HYDROGEN PRODUCTION.2008Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 50.
    Rundstrom, Daniel
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Moshfegh, Bahram
    Department of Mechanical Engineering, Linköping University, Linköping, Sweden.
    Investigation of Heat Transfer and Pressure Drop of an Impinging Jet in a Cross-Flow for Cooling of a Heated Cube2008In: Journal of heat transfer, ISSN 0022-1481, E-ISSN 1528-8943, Vol. 130, no 12, 121401Article in journal (Refereed)
    Abstract [en]

    The objective of this study is to investigate the thermal performance and the cost measured in pressure drops of a targeted cooling system with use of an impinging jet in combination with a low-velocity channel flow on a heated wall-mounted cube. The effects of the Reynolds numbers of the impinging jet and the cross flow, as well as the distance between the top and bottom plates, are investigated. A steady-state 3D computational fluid dynamics model was developed with use of a Reynolds stress model as turbulence model. The geometrical case is a channel with a heated cube in the middle of the base plate and two inlets, one horizontal channel flow and one vertical impinging jet. The numerical model was validated against experimental data with a similar geometrical setup. The velocity field was measured by particle image velocimetry and the surface temperature was measured by an infrared imaging system. This case results in a very complex flow structure where several flow-related phenomena influence the heat transfer rate and the pressure drops. The average heat transfer coefficients on each side of the cube and the pressure loss coefficients are presented; correlations for the average heat transfer coefficient on the cube and the pressure loss coefficients are created. [DOI: 10.1115/1.2969266]

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