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  • 351.
    Hansson, Linus
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Larchet, Kevin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Development and implementation of a dynamic TES dispatch control component in a PV-CSP techno-economic performance modelling tool2017In: AIP Conference Proceedings, American Institute of Physics (AIP), 2017, Vol. 1850, article id 160013Conference paper (Refereed)
    Abstract [en]

    The dispatchability offered by thermal energy storage (TES) in concentrated solar power (CSP) and solar hybrid plants based on such technology presents the most important difference compared to power generation based only on photovoltaics (PV). This has also been one reason for recent hybridization efforts of the two technologies and the creation of Power Purchase Agreement (PPA) payment schemes based on offering higher payment multiples during daily hours of higher (peak or priority) demand. Recent studies involving plant-level thermal energy storage control strategies are however to a large extent based on pre-determined approaches, thereby not taking into account the actual dynamics of thermal energy storage system operation. In this study, the implementation of a dynamic dispatch strategy in the form of a TRNSYS controller for hybrid PV-CSP plants in the power-plant modelling tool DYESOPT is presented. In doing this it was attempted to gauge the benefits of incorporating a day-ahead approach to dispatch control compared to a fully pre-determined approach determining hourly dispatch only once prior to annual simulation. By implementing a dynamic strategy, it was found possible to enhance technical and economic performance for CSP-only plants designed for peaking operation and featuring low values of the solar multiple. This was achieved by enhancing dispatch control, primarily by taking storage levels at the beginning of every simulation day into account. The sequential prediction of the TES level could therefore be improved, notably for evaluated plants without integrated PV, for which the predicted storage levels deviated less than when PV was present in the design. While also featuring dispatch performance gains, optimal plant configurations for hybrid PV-CSP was found to present a trade-off in economic performance in the form of an increase in break-even electricity price when using the dynamic strategy which was offset to some extent by a reduction in upfront investment cost. An increase in turbine starts for the implemented strategy however highlights that this is where further improvements can be made.

  • 352. Hantsch, A.
    et al.
    Gross, U.
    Martin, Andrew R.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Heat Transfer Augmentation: Radiative-Convective Heat Transfer in a Tube With Fiber Array Inserts2010In: Journal of heat transfer, ISSN 0022-1481, E-ISSN 1528-8943, Vol. 132, no 2Article in journal (Refereed)
    Abstract [en]

    Gas-phase heat transfer plays a critical role in many high temperature applications, such as preheaters, combustors, and other thermal equipment. In such cases common heat transfer augmentation methods rely on the convective component alone to achieve improved internal performance. Radiatively assisted heat transfer augmentation has been suggested as a way to overcome limitations in convective-only enhancement. One example of such a technique is the fiber array insert; thermal radiation emitted by tube walls is captured by a large number of slender fibers, which in turn convect heat to the flowing fluid. Previous numerical studies have indicated that this technique represents a promising enhancement method warranting further investigation. This paper presents results from an experimentally based feasibility study of fiber array inserts for heat transfer augmentation in an externally heated duct. Fibers composed of 140 mu m silicon carbide and 150 mu m stainless steel were assembled in arrays with porosities around 0.98, and were tested for empty-tube Reynolds numbers ranging from 17,500 to 112,500 and wall temperatures from ambient up to 750 degrees C. The arrays cause a significant pressure drop-roughly two orders of magnitude higher than the empty-tube case-but tube-side heat transfer coefficients were improved by up to 100% over the convective-only case in the low flow rate regime. The stainless steel fiber array exhibited similar heat transfer performance as the silicon carbide case, although pressure drop characteristics differed owing to variations in fluid-structure flow phenomena. Pressure drop data were roughly within the range of d'Arcy law predictions for both arrays, and deviations could be explained by inhomogeneities in fiber-to-fiber spacing. Heat transfer was found to depend nonlinearly on wall temperature and flow rate, in contrast to previously reported numerical data.

  • 353.
    Hassan, Hafiz Muhammad Adeel
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Development and Evaluation of a CFD Model to Simulate Thermal Performance of Phase Change Material (PCM) Based Energy Storage Systems2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Waste heat can be recovered and used in different processes to increase energy efficiency and reduce CO2 emissions. It has become an attractive area of research for scientists and several techniques are being investigated and practiced to recover, store and use waste heat. Thermal Energy Storage is one of the modern techniques that is used to store and use waste heat. Energy can be stored in both sensible and latent forms of heat. Latent heat storage is the most efficient way of storing thermal energy as it provides higher storage density and lower temperature differential between storing and releasing heat. The materials that are used for latent energy storage are termed as Phase Change Materials (PCMs).

    This thesis work investigates the feasibility of a latent heat storage and heat exchanger performance based on phase change material to recover heat at elevated temperatures. The heat transfer study is done by using state of the art commercial CFD tool. Different model geometries of the Thermal Storage equipped with Shell and tube heat exchanger were built with different pipe configurations.

    The 1st type of model is a set of three 2D models built in COMSOL Multiphysics. These models constitute a cross section of a small portion of heat exchanger having four 10 mm outer diameter pipes immersed in PCM. Fins were mounted on the pipes to enhance the area for heat transfer and hence the heat transfer rate in modified models. Simulations were carried out for melting and solidification of PCM with these 2D models. After analyzing the results, a 3D model of the small block was created to get more realistic results and analyze the effect of pipe diameter on melting and solidification of PCM.

    The results of 2D models show the effect of fins on heat transfer rates. The model with eight fins on each pipe shows the best results as compared to other two models. The melting and solidification rates are nearly half for eight fin model as compared to the model without fins. The four fin model shows moderate results but better than the model without fins. The comparison of the results for different diameter pipes in 3D model shows that heat transfer rate increases for increasing diameters of the pipe with same flow rate in the case of melting.

  • 354.
    Hassan, Sunie
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Verification and Improvement of Wind Turbine Unsteady Wake Model2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 355.
    Hassan, Sunie
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Corporella, Matteo
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Robertson, Miwa
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Zhuang, Qingyuan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Effect on the aerodynamic forcing in an axial turbine stage on varying stator blade shape2012In: Proceedings of the 28th Congress of the International Council of the Aeronautical Sciences 2012, ICAS 2012: Vol.4, 2012, p. 2816-2827Conference paper (Refereed)
    Abstract [en]

    The aim of this paper is to describe the procedure and the outcome of a study performed in order understand the dependence of the forced response of the rotor blades in a turbine stage on a selection of different shape modifications, namely lean, sweep and a number of their combination, of the stator blades by means of computational fluid dynamics (CFD. The adopted criterion to compare the different analyzed cases is the generalized force obtained by the projection of the unsteady aerodynamic forces onto the rotor blade natural mode shapes derived by means of a finite element analysis. A mode excitability study was first conducted by putting emphasis on the lower frequencies modes widely considered as the most critical ones in real applications, in an attempt to identify and characterize their behavior with respect to the stator blade shapes. A forced response assessment exercise was then performed for the specific case under exam in order to discover the optimal configuration, intended as with the smallest maximum value of the generalized forces for each possible condition of resonance of the machine. Steady simulations were used to assess the permanence of the working conditions, as expressed by the mass flow, the pressure ratio, the loading and the flow coefficients, within reasonable limits from the baseline case for the entire set of studied variations.

  • 356.
    He, Yunjuan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Faculty of Computer and Information, Hubei University, Wuhan, Hubei, China.
    Fan, Liangdong
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Faculty of Computer and Information, Hubei University, Wuhan, Hubei, China.
    Afzal, Muhammad
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Singh, Manish
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Zhang, Wei
    Zhao, Yufeng
    Li, Junjiao
    Zhu, Bin
    Faculty of Computer and Information, Hubei University, Wuhan, Hubei, China.
    Cobalt oxides coated commercial Ba0.5Sr0.5Co0.8Fe0.2O3-delta as high performance cathode for low-temperature SOFCs2016In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 191, p. 223-229Article in journal (Refereed)
    Abstract [en]

    In order to improve the catalytic activity of commercial Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF) for low-temperature solid oxide fuel cells (LTSOFC) (300-600 degrees C), CoOx has been used to modify the commercial BSCF through a solution coating approach. Phase and morphology of samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and energy-dispersive spectrometry (EDS), respectively. BSCF with 10 wt% CoOx exhibited an improved conductivity of 44 S/cm, and achieved a peak power density of 463 mW/cm(2) at 550 degrees C for LTSOFC, which is a 100% enhancement than that with the BSCF cathode. The cathode oxygen reduction reaction (ORR) promoted by CoOx and enhanced device performance mechanism have been proposed. This work provides a new way for the exploitation of high effective cathode materials for LTSOFCs.

  • 357.
    Heier, Johan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Energy Efficiency through Thermal Energy Storage: Possibilities for the Swedish Building Stock2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The need for heating and cooling in buildings constitutes a considerable part of the total energy use in a country and reducing this need is of outmost importance in order to reach national and international goals for reducing energy use and emissions. One important way of reaching these goals is to increase the proportion of renewable energy used for heating and cooling of buildings. Perhaps the largest obstacle with this is the often occurring mismatch between the availability of renewable energy and the need for heating or cooling, hindering this energy to be used directly. This is one of the problems that can be solved by using thermal energy storage (TES) in order to save the heat or cold from when it is available to when it is needed.

    This thesis is focusing on the combination of TES techniques and buildings to achieve increased energy efficiency for heating and cooling. Various techniques used for TES as well as the combination of TES in buildings have been investigated and summarized through an extensive literature review. A survey of the Swedish building stock was also performed in order to define building types common in Sweden. Within the scope of this thesis, the survey resulted in the selection of three building types, two single family houses and one office building, out of which the two residential buildings were used in a simulation case study of passive TES with increased thermal mass (both sensible and latent). The second case study presented in the thesis is an evaluation of an existing seasonal borehole storage of solar heat for a residential community. In this case, real measurement data was used in the evaluation and in comparisons with earlier evaluations.

    The literature reviews showed that using TES opens up potential for reduced energy demand and reduced peak heating and cooling loads as well as possibilities for an increased share of renewable energy to cover the energy demand. By using passive storage through increased thermal mass of a building it is also possible to reduce variations in the indoor temperature and especially reduce excess temperatures during warm periods, which could result in avoiding active cooling in a building that would otherwise need it. The analysis of the combination of TES and building types confirmed that TES has a significant potential for increased energy efficiency in buildings but also highlighted the fact that there is still much research required before some of the technologies can become commercially available. In the simulation case study it was concluded that only a small reduction in heating demand is possible with increased thermal mass, but that the time with indoor temperatures above 24 °C can be reduced by up to 20%. The case study of the borehole storage system showed that although the storage system worked as planned, heat losses in the rest of the system as well as some problems with the system operation resulted in a lower solar fraction than projected.

    The work presented within this thesis has shown that TES is already used successfully for many building applications (e.g. domestic hot water stores and water tanks for storing solar heat) but that there still is much potential in further use of TES. There are, however, barriers such as a need for more research for some storage technologies as well as storage materials, especially phase change material storage and thermochemical storage.

  • 358.
    Heier, Johan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. Högskolan Dalarna, Energi och miljöteknik.
    Bales, Chris
    Högskolan Dalarna, Energi och miljöteknik.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Combining Thermal Energy Storage with Buildings: A Review2015In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 42, p. 1305-1325Article, review/survey (Refereed)
    Abstract [en]

    Thermal Energy Storage (TES) has been a topic of research for quite some time and has proven to be a technology that can have positive effects on the energy efficiency of a building by contributing to an increased share of renewable energy and/or reduction in energy demand or peak loads for both heating and cooling. There are many TES technologies available, both commercial and emerging, and the amount of published literature on the subject is considerable. Literature discussing the combination of thermal energy storage with buildings is however lacking and it is therefore not an easy task to decide which type of TES to use in a certain building. The goal of this paper is to give a comprehensive review of a wide variety of TES technologies, with a clear focus on the combination of storage technology and building type. The results show many promising TES technologies, both for residential and commercial buildings, but also that much research still is required, especially in the fields of phase change materials and thermochemical storage.

  • 359.
    Heier, Johan
    et al.
    Högskolan Dalarna, Energi och miljöteknik.
    Bales, Chris
    Högskolan Dalarna, Energi och miljöteknik.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Energy Efficiency through Thermal Energy Storage - Evaluation of the Possibilities for the Swedish Building Stock, Phase 12010In: Clima2010, Antalya, Turkiet, 2010Conference paper (Other academic)
    Abstract [en]

    As a first step in assessing the potential of thermal energy storage in Swedish buildings, the current situation of the Swedish building stock and different storage methods are discussed in this paper. Overall, many buildings are from the 1960’s or earlier having a relatively high energy demand, creating opportunities for large energy savings. The major means of heating are electricity for detached houses and district heating for multi dwelling houses and premises. Cooling needs are relatively low but steadily increasing, emphasizing the need to consider energy storage for both heat and cold. The thermal mass of a building is important for passive storage of thermal energy but this has not been considered much when constructing buildings in Sweden. Instead, common ways of storing thermal energy in Swedish buildings today is in water storage tanks or in the ground using boreholes, while latent thermal energy storage is still very uncommon.

  • 360.
    Heier, Johan
    et al.
    Högskolan Dalarna, Energi och miljöteknik.
    Bales, Chris
    Högskolan Dalarna, Energi och miljöteknik.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Thermal energy storage in Swedish single family houses: a case study2012In: InnoStock The 12th International Conference on Energy Storage: Book of Abstract, 2012Conference paper (Other academic)
    Abstract [en]

    In a Nordic climate, space heating (SH) and domestic hot water (DHW) used in buildings constitute a considerable part of the total energy use in the country. For 2010, energy used for SH and DHW amounted to almost 90 TWh in Sweden which corresponds to 60 % of the energy used in the residential and service sector, or almost 24 % of the total final energy use for the country.

    Storing heat and cold with the use of thermal energy storage (TES) can be one way of increasing the energy efficiency of a building by opening up possibilities for alternative sources of heat or cold through a reduced mismatch between supply and demand. Thermal energy storage without the use of specific control systems are said to be passive and different applications using passive TES have been shown to increase energy efficiency and/or reduce power peaks of systems supplying the heating and cooling needs of buildings, as well as having an effect on the indoor climate. Results are however not consistent between studies and focus tend to be on the reduction of cooling energy or cooling power peaks. In this paper, passive TES introduced through an increased thermal mass in the building envelope to two single family houses with different insulation standard is investigated with building energy simulations. A Nordic climate is used and the focus of this study is both on the reduction of space heating demand and space heating power, as well as on reduction of excess temperatures in residential single family houses without active cooling systems. Care is taken to keep the building envelope characteristics other than the thermal mass equal for all cases so that any observations made can be derived to the change in thermal mass.

    Results show that increasing the sensible thermal mass in a single family house can reduce the heating demand only slightly (1-4 %) and reduce excess temperatures (temperatures above 24 degrees C) by up to 20 %. Adding a layer of PCM (phase change materials) to the light building construction can give similar reduction in heating demand and excess temperatures, however the phase change temperature is important for the results.

  • 361.
    Hermannsson, Elvar
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Hydrodynamic Shape Optimization of Trawl Doors with Three-Dimensional Computational Fluid Dynamics Models and Local Surrogates2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Rising fuel prices have been inflating the operating costs of the fishing industry. Trawl doors are used to hold the fishing net open during trawling operations, and they have a great influence on the fuel consumption of vessels. Improvements in the design of trawl doors could therefore contribute significantly to increased fuel efficiency. An efficient optimization algorithm using two- and three-dimensional (2D and 3D) computational fluid dynamics (CFD) models is presented. Accurate CFD models, especially 3D, are computationally expensive. The direct use of traditional optimization algorithms, which often require a large number of evaluations, can therefore be prohibitive. The proposed method is iterative and uses low-order local response surface approximation models as surrogates for the expensive CFD model to reduce the number of iterations. The algorithm is applied to the design of two types of geometries: a typical modern trawl door, and a novel airfoil-shaped trawl door. The results from the 2D design optimization show that the hydrodynamic efficiency of the typical modern trawl door could be increased by 32%, and the novel airfoil-shaped trawl door by 13%. When the 2D optimum designs for the two geometries are compared, the novel airfoil-shaped trawl door results to be 320% more efficient than the optimized design of the typical modern trawl door. The 2D optimum designs were used as the initial designs for the 3D design optimization. The results from the 3D optimization show that the hydrodynamic efficiency could be increased by 6% for both the typical modern and novel airfoil-shaped trawl doors. Results from a 3D CFD analysis show that 3D flow effects are significant, where the values for drag are significantly underestimated in 2D CFD models.

  • 362.
    Hermannsson, Elvar
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Leifsson, L.
    Koziel, S.
    Ogurtsov, S.
    Glubokov, O.
    Fakhraie, Reza
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Hydrodynamic design optimization of trawl-door shapes with local surrogate models2013In: SIMULTECH 2013: Proceedings of the 3rd International Conference on Simulation and Modeling Methodologies, Technologies and Applications, 2013, p. 751-756Conference paper (Refereed)
    Abstract [en]

    Trawl-doors have a large influence on the fuel consumption of fishing vessels. Design and optimization of trawl-doors using computational models are a key factor in minimizing the fuel consumption. This paper presents an optimization algorithm for the shape design of trawl-door shapes using computational fluid dynamic (CFD) models. Accurate CFD models are computationally expensive. Therefore, the direct use of traditional optimization algorithms, which often require a large number of evaluations, may prohibitive. The proposed approach is iterative and uses low-order local response surface approximation models of the expensive CFD model, constructed in each iteration, to reduce the number of evaluations. The algorithm is applied to the design of a two-element trawl-door (slat and airfoil), involving four design variables controlling the angle of attack and the slat position and orientation. The results show that a satisfactory design can be obtained at the cost of a few iterations of the algorithm.

  • 363.
    Hoffman, Victor
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Marmsjö, Anton
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Combustion of sludge in Fortum’s plants with possible phosphorus recycling2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The management of waste is by all means a great challenge to any society. In Sweden, the past decades has seen legislation progressing in congruence with concerns over environmental stress from inefficient waste management. The legislative changes aim primarily to promote waste reduction and better waste utilization. Sludge is a waste-type from different industrial processes and is unfortunately of limited reuse and recycling-value, but sludge combustion for energy recovery appears promising. Also, the oftentimes high phosphorus content in sludge strengthens the potential of extracting phosphorus from combustion ashes.

    The heat and power industry has shown great interest in sludge combustion. Fortum has a set of different sludge types to choose from as well as many different options available based on where and how the sludge can be incinerated. Yet there are many inherent problems, but also operational benefits, of combusting sludge. These factors combined make the venture multifaceted and therefore not straightforward. Based on this, this thesis is a preliminary study aiming to assess the possibility of combusting sludge in Fortum’s existing or future facilities, along with possible phosphorus recovery from the combustion ashes.

    The study was based on applying either sludge mono- or co-combustion. The scenarios evaluated were; firing 70000 tonnes of digested sewage sludge, 50000 tonnes of fibrous sludge and 26400 tonnes of digestate which all are pertinent sludge amounts in this study. Co-combustion involved firing these together with the base fuels fired in Fortum’s grate furnace and fluidized bed boilers in Brista and Högdalen CHP plants. The mixing yielded new characteristics of the combustion input, such as a lower heating value, which were vetted against the boilers’ capability to handle these. Mono-combustion was compared economically with co-combustion to assess investment profitability. The phosphorus concentration in the ashes from the mixes was determined as well in order to assess the possibility for viable extraction. In addition, proper sludge pretreatment methods were examined.

    The results showed that co-incineration of 70000 tonnes digested sewage sludge was possible in boiler P6 in Högdalen and B2 in Brista. These generated an economic gain with an internal rate of return of 96,3 % and 96,4 % respectively. It was possible to co-incinerate 50000 tonnes of fibrous sludge in boilers B1 and B2 in Brista as well as P6 although economic gains were only seen in B1, where the internal rate was 87,5 %. Co‑incinerating 26400 tonnes of digestate was possible in all boilers except P3 assuming that the similar boilers P1 and P2 in Högdalen can incinerate the sludge in tandem. The incineration of digestate yielded an economic gain for these boilers with an internal rate ranging from 25,7 % for P1 and P2 in tandem to 102,6 % for B1. Although mono-combustion is a practical solution it was found not to be an economically feasible alternative under prevailing economic conditions.

    The results also indicated that NOx and SOx formation increased in the raw flue gaseswhen co‑firing sludge, as also was the case with flue gas volume flow and flue gas water vapor. Fossil CO2 emissionsdecreased for all waste fired boilers when co-combusting sludge. Digested sewage sludge and digestate increased combustion ash amounts in all cases, whereas fibrous sludge only did this in B1. All sludge types were found to be beneficial for reducing the risk of corrosion and agglomeration, but digested sewage sludge was remarkably more so than digestate and fibrous sludge. The phosphorus concentration in the co-combustion ashes was deemed insufficient for viable phosphorus extraction, but was promising when firing digested sewage sludge in B1. The concentration was sufficient in a mono-combustion application when firing digested sewage sludge and digestate. Overall environmental impacts are however dubious. There needs to be further investigation in order to properly assess these.

  • 364.
    Hopper, Miles
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Grid-Scale Hydrogen Energy Storage: A Techno-Economic Cost-Benefit Analysis for Sweden2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The transition to a 100% renewable-based energy system in Sweden requires investments in large-scale energy storage to balance the variable output from renewable energy sources. Currently, many energy storage technologies exist and their feasibility and effectiveness needs to be critically evaluated for every particular location with different sets of parameters. Underground hydrogen storage has been suggested by many researchers as one such viable option.

     

    This study explores the potential costs and benefits of developing the technological framework and investing in a grid-scale hydrogen energy storage, from the point of view of electricity distribution system operators in Sweden. A tool called StorageVET was used for the analysis, to simulate three potential scenarios for the implementation of hydrogen energy storage in Sweden, such as: a) offshore underground storage in saline aquifers; b) underground storage in geological formations onshore; and c) liquid hydrogen storage in large steel vessels on land.

     

    All three scenarios were calculated to have a NPV of just over $100 million, for the specific parameters selected, suggesting that investing in hydrogen energy storage could be economically feasible for the case of Sweden. It is believed that this work would lead to increased focus on hydrogen as a grid-scale energy storage technology and to further detailed feasibility evaluation studies by distribution system operators and energy researchers.

  • 365.
    Hosseini, Seyed Mohammad
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fruth, Florian
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Vogt, Damian
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Effect of Scaling of Blade Row Sectors on the Prediction of Aerodynamic Forcing in a Highly-Loaded Transonic Turbine Stage2012In: Proceedings of the ASME Turbo Expo 2011, Vol 6, Parts A And B, New York: American Society of Mechanical Engineers , 2012, p. 1297-1307Conference paper (Refereed)
    Abstract [en]

    The viability of a scaling technique in prediction of forced response of the stator and rotor blades in a turbine stage has been examined. Accordingly the so called parameter, generalized force, is defined which describes the excitation of a modeshape due to the unsteady flow forces at a certain frequency. The capability of this method to accurately predict the generalized forces serves as the viability criterion. The scaling technique modifies the geometry to obtain an integer stator, rotor blade count ratio in an annulus section while maintaining steady aerodynamic similarity. A non-scaled configuration is set up to serve as the reference case. Further configurations with different scaling ratios are also generated for accuracy comparison. Unsteady forces are calculated through 3D Navier-Stokes simulations by VolSol, which is based on an explicit, time-marching. A general purpose finite element model of blades is also provided to enable modal analysis with the harmonic forces. The generalized forces of stator and rotor blades revealed high sensitivity towards modification of stator blades while acceptable accuracy was obtained by moderate modifications of the rotor blades for first harmonic forces. Moreover the influence of variable blade's structural characteristics proved to be remarkable.

  • 366.
    Howells, Mark I.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy Systems Analysis.
    Jonsson, Sandra
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Käck, Emilia
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Lloyd, Philip
    Bennett, Kevin
    Leiman, Tony
    Conradie, Beatrice
    Calabashes for kilowatt-hours: Rural energy and market failure2010In: Energy Policy, ISSN 0301-4215, E-ISSN 1873-6777, Vol. 38, no 6, p. 2729-2738Article in journal (Refereed)
    Abstract [en]

    This paper describes how management and information failures can retard transitions from the traditional use of biomass fuel by low income rural consumers and micro-producers. In general, societies move away from traditional biomass use as economic development takes place. If one accepts the doctrine of revealed preference (built on the initial work of Samuelson, 1938), then these trends imply that such transitions provide net gains in utility. This paper shows how various "failures" entrench existing fuel use patterns-hindering the transition to new fuel use patterns. In order to qualitatively discuss how these transitions may take place, an indicative neo-classical description of consumer and producer behavior is used. Three types fuel-transition "driver" are identified. The effect of information and management failures on these drivers, and thus the energy transition, is discussed. Reference is made to a specific case study in which a partial transition from biomass occurred in response to an intervention to address an environmental management failure (the deforesting of a carbon sink.) It is concluded that interventions to encourage transitions to cleaner sustainable fuel use may need to recognize and address management and information failures in a systematic manner.

  • 367. Hu, H. -Q
    et al.
    Lin, Q. -Z
    Zhu, Binzhu
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Research progress of single layer fuel cell2017In: Xiandai Huagong/Modern Chemical Industry, ISSN 0253-4320, Vol. 37, no 2, p. 31-35 and 37Article in journal (Refereed)
    Abstract [en]

    The definition, working principle and the superior performance of single layer fuel cell are briefly introduced. The latest achievement and research progress in this field are summarized, which lay a foundation for the next development of single layer fuel cell.

  • 368. Hu, Huiging
    et al.
    Lin, Qizhao
    Zhu, Zhigang
    Liu, Xiangrong
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Time-dependent performance change of single layer fuel cell with Li0.4Mg0.3Zn0.3O/Ce0.8Sm0.2O2-delta composite2014In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 39, no 20, p. 10718-10723Article in journal (Refereed)
    Abstract [en]

    A Large-size engineering single layer fuel cell (SLFC) consisting of a nano-structured Li0.4Mg0.3Zn0.3O2-delta/Ce0.8Sm0.2O2-delta (LMZSDC) composite with an active area of 25 cm(2) (6 cm x 6 cm x 0.1 cm) is successfully fabricated. The SLFC is evaluated by testing the cell durability with a time-dependent degradation using an H-2 fuel and an air oxidant at 600 degrees C for over 120 h. A maximum power of 12.8 W (512 mW cm(-2)) is achieved at 600 degrees C. In the initial operation stage around 50 h, the cell's performance decreases from 12.8 to 11.2 W; however, after this point, the performance was consistently stable, and no significant degradation is observed in the current density or the cell performance. The device performed excellently at low temperatures with a delivered power output of more than 250 mW cm(-2) at a temperature as low as 400 degrees C. By curve fitting the X-ray photoelectron spectroscopy (XPS) results, the ratio of Ce3+/(Ce3++Ce4+) before and after the long-time operation is analyzed. The ratio increased from 28.2% to 31.4% in the electrolyte which indicates a reduction occurs in the beginning operation that causes an initial performance loss for the device power output and OCV. Electrochemical impedance analyses indicate that the LMZSDC had a high ionic transport, and the device had quick dynamic processes and, thus, a high fuel cell performance. The LMZSDC is a new type of ionic material that has been successfully applied to SLFCs.

  • 369. Hu, Huiqing
    et al.
    Lin, Qizhao
    Liu, Xiangrong
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Scaled up low-temperature SOFCs with symmetrical electrode for applications2015In: Journal of Solid State Electrochemistry, ISSN 1432-8488, E-ISSN 1433-0768, Vol. 19, no 8, p. 2361-2368Article in journal (Refereed)
    Abstract [en]

    In this study, a new type of the Mg0.4Zn0.6O/Ce0.8Sm0.2O2-delta (MZSDC) composite electrolyte was synthesized using a co-precipitation method. Large-sized engineering cells have been fabricated and tested to meet the demands of applications. X-ray diffraction scanning electron microscopy and X-ray photoelectron spectroscopy have been employed to characterize the microstructure and the morphology of the synthesized samples. MZSDC is a composite system. X-ray electron spectroscopy shows that Ce (3d) binding energy shifted from high to low and the ratio of Ce3+ decreased in comparison to pure CeO2, due to the doping effect. The doping and composite caused the material to have an excellent electrical property, 0.089 S center dot cm(-1), and device performance, with a maximum power of 16.4 W (648 mW center dot cm(-2)) achieved at 600 A degrees C for a larger-sized (6 cm x 6 cm x 1 mm) fuel cell. The open circuit voltage and power of the fuel cell only slightly degrades (less than 1 %) after continually tested for 100 h. This is the first report regarding the large size engineering cell performance for using this new composite electrolyte with both excellent performance and low cost.

  • 370. Hu, Huiqing
    et al.
    Lin, Qizhao
    Zhu, Zhigang
    Liu, Xiangrong
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Afzal, Muhammad
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    He, Yunjuan
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Hubei Univ, Fac Phys & Elect Technol, Hubei Collaborat Innovat Ctr Adv Mat, Wuhan 430062, Hubei, Peoples R China.
    Effects of composition on the electrochemical property and cell performance of single layer fuel cell2015In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 275, p. 476-482Article in journal (Refereed)
    Abstract [en]

    In this study, the enhanced electrochemical performance of single layer fuel cells (SLFCs) based upon mixed ion and electron conductors is analyzed as a function of composition. We synthesize a series of Ce0.8Sm0.2O2-delta-Li0.3Ni0.6Cu0.07Sr0.03O2-delta (SDC-LNCS) with different weight ratios. The microstructure and morphology of the composite materials are characterized through X-ray diffraction (XRD), transmission electron microscope (TEM), and energy-dispersive X-ray spectrometer (EDS). Stability of the synthesized samples is evaluated by thermal gravity analysis (TGA). The SLFC with 6SDC-4LNCS exhibits a uniform distribution of the two compositions as well as demonstrates the highest power density of 312 mW cm-2 at 550 mu C. The performance is correlated to the balance of the conduction properties (ionic and electronic) of the functional SLFC layer. The results are a critical contribution to further development of this new energy transfer device.

  • 371. Hu, Huiqing
    et al.
    Lin, Qizhao
    Zhu, Zhigang
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Liu, Xianrong
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Fabrication of electrolyte-free fuel cell with Mg0.4Zn0.6O/Ce0.8Sm0.2O2-delta-Li0.3Ni0.6Cu0.07Sr0.03O2-delta layer2014In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 248, p. 577-581Article in journal (Refereed)
    Abstract [en]

    Electrolyte-free fuel cell (EFFC) which holds the similar function with the traditional solid oxide fuel cell (SOFC) but possesses a completely different structure, has draw much attention during these years. Herein, we report a complex of MZSDC LNCS (Mg0.4Zn0.6O/Ce0.8Sm0.2O2-delta-Li0.3Ni0.6Cu0.07Sr0.03O2-delta) for EFFC that demonstrates a high electrochemical power output of about 600 mW cm(-2) at 630 degrees C. The co-doped MZSDC is synthesized by a co-precipitation method. Semiconductor material of LNCS is synthesized by direct solid state reaction. The microstructure and morphology of the composite materials are characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and energy-dispersive Xray spectrometer (EDS). The performance of the cell with a large size (6 x 6 cm(2)) is comparable or even better than that of the conventional solid oxide fuel cells with large sizes. The maximum power output of 9.28 W is obtained from the large-size cell at 600 degrees C. This paper develops a new functional nanocomposite for EFFC which is conducive to its commercial use.

  • 372.
    Hultman, Hugo
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Validation of Forced Response Methods for Turbine Blades2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 373.
    Humphrey, John
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Building a US company to manufacture solar PV mounting systems2015Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This paper describes the process of developing a product for the solar industry. It is the story of starting a business in the solar market by designing a product, manufacturing the product and growing sales to over $1 million USD in 2011 and 2012. The author is describing the actual details of a manufacturing company that produces solar racking systems in the USA. The author founded the company in 2009 and left the company at the end of 2012. The document describes the changing landscape of the racking sector of the US PV market, and makes the case for industry standards in solar module dimensions. The range of current sizes of solar modules is described. The inconsistency in sizes creates additional overhead for manufacturers to accommodate different sized parts to hold the different solar panels. A uniform standard size would result in cost reductions for the end customers.

  • 374.
    Ihlis, Johan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Implementation of machine learning to model losses from icing of wind turbines2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis investigates the possibility to use machine learning algorithms to predict the losses due to icing in the Stor-Rotliten wind farm that is situated in the north of Sweden and operated by Vattenfall. The inputs for the machine learning are historical mesoscale modelled variables that are derived from a Weather Research and Forecasting Model code that is tuned for icing (WRF-model). An ice model has been updated and improved so that it would achieve a better indication of icing, based on the equations from Lasse Makkonen.

    A more accurate model of a wind turbine considers the turbine blade as a rotating cylinder at 85% of the length of the blade and not as vertical cylinder that stands still. Besides this, the variables from the mesoscale data are used as inputs for the machine learning algorithm.

    The targets are energy production losses due to icing that is computed from historical SCADA data that covers the same time frame as the WRF data. To reduce the complexity and the computational time of the system a statistical variable selection algorithm, called mutual information, is used with the MILCA toolbox for Matlab. The target for the variable selection and the machine learning is the average loss of power per wind turbine per hour. This is extracted from the production data from Vattenfall. The goal with the thesis is to relate the modelled mesoscale data with the production data (SCADA).

    The overall result of the study is that the neural network method offers a suitable and more accurate way to predict the losses from icing on wind turbines, but there is some work still to be done to reduce the errors in the input variables.

  • 375.
    Imran, Syed Khalid
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Study of (Different) Nano-composite of Fuel cell-A Clean way of Energy2016Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
  • 376.
    Israelsson, Filip
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Sustainable mass handling: Modelling quantities of excavated soil and rock in residential construction projects2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    An efficient handling process of aggregates and excavated soil and rock will be of increasing importance in expanding urban regions. The construction of residences, infrastructure and commercial areas generate significant amounts of soil and rock that can be re-used more efficiently as construction material, minimizing transportation and environmental impact. A key element is the implementation of central intermediate storage sites for re-use purposes and cooperation between several construction projects in a region. The evaluation of storage capacities and optimal site locations is in turn dependent on comprehensive knowledge about what quantities of aggregates and excavated soil and rock that will be generated and utilized in the region.

    The calculation model presented in this thesis provides a way of estimating the amount of excavated soil and rock generated during the construction of new residential areas at an initial stage of the planning process. The excavated volume is expressed as a function of the number of residents and the number of floors in the buildings of the planned area, allowing for an early estimation that may effectively influence the logistical planning of the mass handling process. The simplified calculation model applied to a case study of the existing residential area Annedal in Stockholm produces an estimated amount of 577 500 ton excavated soil and rock, approximately 3.8 % lower than the reference value of 600 000 ton.

    Regional storage sites are advantageous as different construction projects generate and utilize different types of soil, rock and aggregates, resulting in a higher possible re-use share than in individual projects. When regarding the energy usage in transportation, it is shown that intermediate storage sites located within 10 km of the construction site may allow for more than 15 % energy reduction if re-using 25 % of the excavated amount of soil and rock. A distance of 5 km may yield more than 20 % reduction of transportation energy for the same share of re-use.

  • 377.
    Ivankovic, Milos
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    MISTUNING AND DAMPING CHARACTERIZATIONS OF A TURBINE ROTOR FOR FLUTTER INVESTIGATION2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Bladed disk vibrations are recognized to be one of the main challenges in ensuring reliable and safe operation of turbomachinery. The phenomena of low-cycle- and high-cycle-fatigue, caused by flutter and high forced response, are known to be fundamental failure modes of bladed disks. While the first phenomenon is to be avoided at all costs – as it leads to rapid disintegration of the machine, the reduction or suppression of the latter is also desirable, resulting in the overall service cost reduction.

    Critical parameter in determining flutter onset is the damping present in the system. The damping can come from energy extraction/insertion from/to the system by the work of fluid flow (aero damping), or from the energy dissipation arising from the nature of material structure or presence of friction surfaces (mechanical damping). While mechanical damping is always positive, aero damping normally drops with rise of flow speed, and can become negative.

    Energy insertion to the system can be disrupted effectively by introducing (intentional or not) small geometry/mass variations to the number of blades in the bladed disk - called mistuning. While mistuning can suppress flutter, its side effects can be negative as well. In controlling this phenomenon, damping again plays critical role.

    This work deals with analytical predictions of flutter in turbomachinery based on the numerical characterizations of mistuning and mechanical damping. These predictions are based on the utilization of harmonic balance solver for flutter and nonlinear damping problems. The procedures are applied to the FUTURE project LPT blade model. The results obtained are compared to the experimental findings.

  • 378.
    Jahajeeah, Manoj Kumar
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Séblin, Didier Bernard
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Investigating sustainable ways and means of enhancing the overall thermal efficiency of diesel power plants in Mauritius and Rodrigues Islands.2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    During the past century the world has gone through the industrialization era where the focus was placed upon maximization of production at any cost to meet the world demand for basic needs as well as comfort. The law of supply and demand dictated the rules of the game while other factors like environmental preservation and the exhaustion of primary sources of energy were overlooked.

    Such an uncontrolled exploitation of energy resources has led to the fast depletion of the world’s energy reserves (with a very negative impact on the ecosystem). This adapt or perish situation has given rise to a paradigm shift towards sustainability. The depletion of fossil fuel reserves has led to soaring price for this raw material as well as for all other petroleum derived products. Such a situation has paved the way to a new era where the focus has been shifted to the exploitation of other sources of energy capable of reconciling both renewability and sustainability aspects. It is however a matter of fact that the access to technologies and infrastructures enabling efficient exploitation of renewable energy sources (e.g. solar, wind, etc.) is limited on account of their intermittent nature, complexity, and high cost (i.e. not firm power requiring back up when not available). This stands as the main reason why to date only developed countries (with interconnected grids) like Germany, Denmark, etc. have succeeded in diversifying their primary energy mix in such a way to increase the share of renewable energy sources at the expense of conventional petroleum/coal based energy sources.

    For small island states, the exploitation of renewable energy resources to cater for firm power constitutes a real challenge in the short term. Hence this project has for main objective to find ways and means to bring in sustainability in their actual energy conversion processes by achieving the optimized conversion efficiencies when delivering required energy supplies. . Several avenues leading to this goal were studied through literature review and their applications to two power plants (one from Mauritius Island and one from Rodrigues Island, namely Fort Victoria Power Station and Pointe Monnier Power Station respectively) were considered. A feasibility study was hence carried out based on technical and financial implications to ensure that the proposed changes are viable.

    The findings of this study are multiple. The energy audit conducted revealed that only 38-44 % of the primary energy used in the power plants is converted into electrical energy implying that valuable heat energy can be recuperated for polygeneration processes. Considerable amount of energy is indeed lost in the medium and low temperature ranges. Recuperation of part of this energy is achievable through a combination of conversion processes including desalination, heat driven refrigeration, electric power generation through HRSGs, heat driven chilling and supplying process heat to industries through heat distribution network. The study indicated that at Fort Victoria the percentage of recoverable heat through HRSG/Steam turbine, heat driven refrigeration and air-conditioning is of the order of 16.5 %. For Pointe Monnier power station the conversion process can be enhanced by 7.28% in summer and 30.28 % in winter. This is due to the fact that on top of HRSG/Steam turbine and refrigeration, additional heat recoverable can be used either for air conditioning in summer or for desalination in winter.

    It was also found that the above mentioned polygeneration processes are economically viable as the payback time is relatively short. This is due to the fact that the operational cost is on the low side as the energy required to drive the processes is free. The results obtained clearly indicate that it is worth investing in polygeneration as it will not only bring in sustainability but would also contribute towards minimizing harmful emissions while enhancing profitability of the power plants.

  • 379.
    Jarmander, Sara
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Wind Power Forecast Accuracy in Scandinavia:Analysis of Forecast Errors Using TAPM2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Wind power has different characteristics compared to conventional energy sources. The main difference is

    that wind power fluctuates under the influence of meteorological variables. This gives rise to problems

    related to grid stability. It is therefore important to understand these variations and their predictability in

    order to improve the integration of wind power into grids. Wind power forecasts play an important role.

    In this study, the accuracy of Numerical Weather Prediction (NWP) wind speed forecasts over the period

    1st Sept. 2013 – 31st Dec. 2016 has been investigated. This was done for four Scandinavian windfarms;

    Rødsand II, Kårehamn, Jokkmokksliden and Storliden.

     

    The NWP used was The Air Pollution Model (TAPM). The main aim of the study was to examine if the

    implementation of bias correction methodologies could improve the accuracy of uncorrected TAPMforecasts. In addition to this main aim, the study was also intended to investigate the differences in the performance of TAPM between Australian and Scandinavian weather conditions.

     

    The results indicated that TAPM has a tendency to under-predict against actual observations. It was also

    observed that the accuracy varied throughout the year, with the best performance during summer and the

    worst during winter. Additionally, the performance varied between turbines within the wind farms. The

    magnitude of forecast errors was lowest for turbines which experience high degrees of wake effects from

    upstream turbines. Furthermore, the results showed that the implementation of certain bias correction

    methodologies improved the accuracy. The greatest enhancements were achieved by the implementation of two correction methodologies, both based on the combination of bias correction and timing correction. The NRMSE of wind speed was reduced by almost 50% for “hour ahead” forecasts for Rødsand II and Kårehamn when full bias correction was applied and by nearly 70% for Jokkmokksliden and Storliden. A reduction in the wind speed magnitude error by as much as half was also reached.

     

    Based on these results, the overall conclusion is that TAPM can be applied for sites with completely different weather conditions with moderately good accurateness, especially if bias correction is applied. However, due to the limited time frame and other delimitations of this study, further studies are necessary in order to draw deeper conclusions.

  • 380. Javed, Muhammad Sufyan
    et al.
    Raza, Rizwan
    Ahsan, Zishan
    Rafique, M. Shahid
    Shahzadi, Shamaila
    Shaukat, S. F.
    Shaheen, Nusrat
    Khalid, Muhammad Saeed
    Chengou, Hu
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Hubei Univiversitym China.
    Electrochemical studies of perovskite cathode material for direct natural gas fuel cell2016In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 41, no 4, p. 3072-3078Article in journal (Refereed)
    Abstract [en]

    Natural gas is the most promising renewable energy source and its widespread availability ensured its importance for early applications in stationary fuel cells as a reliable and low cost fuel. Therefore it is very important to efficiently utilization of natural gas in low temperature fuel cells. Herein, we demonstrate the synthesis of perovskite material of Yttrium doped Sr0.92FexTi1-xO3-delta (x = 0.25, 030) (YSFT) by solid state reaction method and further investigated as a new cathode material for a low temperature solid oxide fuel cell fueled by natural gas. The YSFT is characterized by X-ray powder diffraction, Brunauer-Emmett-Teller and scanning electron microscopy. The perovskite structure is achieved at relatively low temperature (850 degrees C). The average crystalline size is found 28 nm and 36 nm for x = 0.25 and 0.30 respectively. TGA results showed the lattice oxygen loss of YSFT is about 0.206% in its original weight in the temperature range of 25-1000 degrees C. The maximum electronic conductivities of 2.3 Scm(-1) and 2.07 Scm(-1) are achieved for x = 025 and x = 0.30 at 550 degrees C in air atmosphere respectively. It is observed that the oxygen reduction is enhanced due to the perovskite crystal structure and oxygen vacancies play an important role in the redox reaction to improve the performance of fuel cell. The YSFT perovskite cathode material based fuel cell with natural gas have achieved the power density of 250 mWcm(-2) for x = 025 at 550 degrees C. The fuel cell device has demonstrated very stable results by running continuously for 5 h with domestic available natural gas. 

  • 381.
    Jayasuriya, Jeevan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Experimental Investigations of High Pressure Catalytic Combustion for Gas Turbine Applications2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This work is devoted to generate knowledge and high quality experimental data of catalytic combustion at operational gas turbine conditions.

    The initial task of the thesis work was to design and construct a high pressure combustion test facility, where the catalytic combustion experiments can be performed at real gas turbine conditions. With this in mind, a highly advanced combustion test facility has been designed, constructed and tested. This test facility is capable of simulating combustion conditions relevant to a wide range of operating gas turbine conditions and different kinds of fuel gases. The shape of the combustor (test section) is similar to a “can” type gas turbine combustor, but with significant differences in its type of operation. The test combustor is expected to operate at near adiabatic combustion conditions and there will be no additions of cooling, dilution or secondary supply of air into the combustion process. The geometry of the combustor consists of three main zones such as air/fuel mixing zone, catalytic reaction zone and downstream gas phase reaction zone with no difference of the mass flow at inlet and exit. The maximum capacity of the test facility is 100 kW (fuel power) and the maximum air flow rate is 100g/s.

    The significant features of the test facility are counted as its operational pressure range (1 – 35 atm), air inlet temperatures (100 – 650 °C), fuel flexibility (LHV 4 - 40 MJ/m3) and air humidity (0 – 30% kg/kg of air). Given these features, combustion could be performed at any desired pressure up to 35 bars while controlling other parameters independently. Fuel flexibility of the applications was also taken into consideration in the design phase and proper measures have been taken in order to utilize two types of targeted fuels, methane and gasified biomass.

    Experimental results presented in this thesis are the operational performances of highly active precious metal catalysts (also called as ignition catalysts) and combinations of precious metal, perovskites and hexaaluminate catalysts (also called as fully catalytic configuration). Experiments were performed on different catalytic combustor configurations of various types of catalysts with methane and simulated gasified biomass over the full range of pressure. The types of catalysts considered on the combustor configurations are palladium on alumina (Pd/AL2O3), palladium lanthanum hexaaluminate (PdLaAl11O19), platinum on alumina (Pt/AL2O3),and palladium:platinum bi-metal on alumina (Pd:Pt/AL2O3). The influence of pressure, inlet temperature, flow velocity and air fuel ratio on the ignition, combustion stability and emission generation on the catalytic system were investigated and presented.

    Combustion catalysts were developed and provided mainly by the project partner, the Division of Chemical Technology, KTH. Division of Chemical Reaction Technology, KTH and Istituto di Ricerche sulla Combustione (CNR) Italy were also collaborated with some of the experimental investigations by providing specific types of catalysts developed by them for the specific conditions of gas turbine requirements.

  • 382.
    Jayasuriya, Jeevan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Ersson, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Fredriksson, Jan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Ultra Low Emission Gas Turbine Combustion: An Expoerimental Investigation of Catalytically Stabilizws Lean Pre-mixed Combustion on Modern Gas Turbine Conditions2004Conference paper (Refereed)
  • 383.
    Jayasuriya, Jeevan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Ersson, Andreas
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Fredriksson, Jan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Catalytic Combustion Developments for Ultra Low Emission Gas Turbine Combustion2003Conference paper (Refereed)
  • 384.
    Jayasuriya, Jeevan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Ersson, Andreas
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Fredriksson, Jan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Experimental Investigations of High Pressure Catalytic Combustion of Methane2003Conference paper (Refereed)
  • 385.
    Jayasuriya, Jeevan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fredriksson, Jan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Persson, Katarina
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Thevenin, Philippe
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Bench Scale Experimental Test Rig  for High Pressure Catalytic Combustion2002Conference paper (Refereed)
  • 386.
    Jayasuriya, Jeevan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Manrique, Arturo
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fakhrai, Reza
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fredriksson, Jan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten H.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Experimental investigations of catalytic combustion for high-pressure gas turbine applications2006In: Proceedings of the ASME Turbo Expo 2006, Vol 1, 2006, p. 763-771Conference paper (Refereed)
    Abstract [en]

    Catalytic combustion has proven to be a suitable alternative to conventional flame combustion in gas turbines for achieving Ultra-Low Emission levels (ULE). In the process of catalytic combustion, it is possible to achieve a stable combustion of lean fuel/air mixtures which results in reduced combustion temperature in the combustor. The ultimate result is that almost no thermal-NOx is formed and the emissions of carbon monoxide and hydrocarbon emissions are reduced to single-digit limits. Successful development of catalytic combustion technology would lead to reducing pollutant emissions in gas turbines to ultra-low levels at lower operating costs. Since the catalytic combustion prevents the pollutant formations in the combustion there is no need for costly emission cleaning systems.

  • 387.
    Jayasuriya, Jeevan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Manrique Carrera, Arturo
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fakhrai, Reza
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fredriksson, Jan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten H.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Gasified biomass fuelled gas turbine: Combustion stability and selective catalytic oxidation of fuel-bound nitrogen2006In: Proceedings of the ASME Turbo Expo 2006, Vol 1, 2006, p. 773-780Conference paper (Refereed)
    Abstract [en]

    Low heating value of gasified biomass and its fuel bound nitrogen containing compounds challenge the efforts on utilizing gasified biomass on gas turbine combustor. Low heating value of the gas brings along combustion stability issues and pollutant emission concerns. The fuel bound nitrogen present in gasified biomass could completely be converted to NOx during the combustion process. Catalytic combustion technology, showing promising developments on ultra low emission gas turbine combustion of natural gas could also be the key to successful utilization of biomass in gas turbine combustor. Catalysts could stabilize the combustion process of low heating value gas while the proper design of the catalytic configuration could selectively convert the fuel bound nitrogen into molecular nitrogen. This paper presents preliminary results of the experimental investigations on combustion stability and nitrogen selectivity in selective catalytic oxidation of ammonia in catalytic combustion followed by a brief description of the design of catalytic combustion test facility. The fuel-NOx reduction strategy considered in this study was to preprocess fuel in the catalytic system to remove fuel bound nitrogen before real combustion reactions occurs. The catalytic combustion system studied here contained two stage reactor in one unit containing fuel preprocessor (SCO catalyst) and combustion catalysts. Experiments were performed under lean combustion conditions (lambda value from 6 up to 22) using a simulated mixture of gasified biomass. The Selective Catalytic Oxidation approach was considered to reduce the conversion of NH3 into N-2. Results showed very good combustion stability, higher combustion efficiency and good ignition performances under the experimental conditions. However, the selective oxidation of fuel bound nitrogen into N-2 was only in the range of 20% to 30% under the above conditions.

  • 388.
    Jayasuriya, Jeevan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Manrique, Carrera
    Fakhrai, Reza
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fredriksson, Jan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    High Pressure Catalytic Combustion of Methane in a Multi Segmented Catalytic Combustor2005Conference paper (Other academic)
  • 389.
    Jayasuriya, Jeevan
    et al.
    KTH, School of Industrial Engineering and Management (ITM).
    Manrique, Carrera
    Fredriksson, J
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Ersson, A.T
    Järås, S
    Gasified Biomass Fuelled Gas Turbine: Combustion Stability and Selective Catalytic Oxidation of Fuel-bound Nitrogen2004Conference paper (Refereed)
  • 390.
    Jazzar, Jacques
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Methods of post-treatment of aerodynamic tests of engine boosters2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Aerodynamics studies in a booster such as analysis of the flow through the whole component or study of local turbulent phenomenon constitute a crucial part of its development in order to get better overall performances, like efficiency of the compressor and compression ratio. In order to put in perspective the computational predictions, it is critical to obtain sets of data from tests to caliber numerical analyses and to assure the booster respects design specifications. Aerodynamics testing is then an important part of the development of a compressor. However, it is complicated to obtain such values for many reasons: time constraints, problems regarding support, important costs etc. Thus, it is important to get as much information as possible from these tests data in a limited period in order to spend more time in results interpretation and less in treating raw data. Thus, an optimized tool of treatment to first deduce results from test data; and then to compare different engines or different sets of tests data, to get a wider state of the art and to avoid time-consuming analyses was needed. In order to do so, the first part of the development consists in investigating the existing methods to extract and analyze data from tests already used, and then deducing a general methodology to obtain from raw measures the performances of the studied booster compared to other available data. Once the methods have been set up and validated, the tool in itself was implemented in a practical way. Then, it was important to validate it on real tests values and to observe if it was adjustable for all kind of aerodynamics tests.

  • 391. Jia, R. -L
    et al.
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Wang, C. -Y
    Preparation and characterization of Pt/Sfmcmb electrocatalysts2005In: Proc. Eur. Fuel Cell Technol. Applic. Conf. Book Abstr., 2005Conference paper (Refereed)
    Abstract [en]

    Super fine mesocarbon microbead powders (SFMCMBs) as the new supports for platinum electrocatalysts were first investigated. The Pt/SFMCMB electrocatalysts were prepared by an impregnation-reduction method, with hexachloroplatinic acid as the platinum precursor and formaldehyde as reducing agent. The catalysts were characterized with X-ray diffraction (XRD), field emission gun transmission electron microscope (TEM) and cyclic voltanumetry (CV). TEM photos showed the platinum particles were dispersed uniformly on the surface of SFMCMBs where the average platinum particle size were 4-6 nm and there existed a little aggregation of platinum particles in the Pt/SFMCMB catalysts. The XRD patterns showed the existence of the platinum on the supports. The acute peak corresponding to diffraction of graphitic structure indicate that SFMCMBs have good electric-conducting performance. The electrochemical analysis proved that SFMCMBs are excellent candidates to be used as the support of platinum electrocatalyst for methanol electrochemical oxidation as the potential catalyst candidate for direct methanol fuel cells (DMFCs).

  • 392.
    Jiahui, Lu
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    RANS and LES Numerical Simulation Of Turbulent Flow within High-Temperature Solar Receiver2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 393.
    Jiang, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Separation of water out of highly concentrated electrolyte solutions using multistage vacuum membrane distillation2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Absorption dehumidification requires regeneration system to regenerate diluted desiccant solutions, which are still highly concentrated. A novel multi-stage vacuum membrane distillation system was applied for separating water out of the highly concentrated solution.

    The performance of this novel membrane distillation system with high concentration solution is studied, as well as the effect of solution concentration, heating temperature and feed flow rate on concentration increase, permeate flux and specific energy consumption was studied. Feed solutions are LiCl solution (22-30 wt%) and CH3COOK solution (50-60 wt%).Other experimental parameters studied were: heating temperature, 70-80 °C, feed flow rate, 1.2-2.0 l/min. Response surface method is applied for model building, in order to provide a better understanding of the interactions between different parameters.

    Compared with pure water, high concentration solution has lower vapor pressure, which leads to lower permeate flux. The highest concentration the system can reach is 36.5 wt% for LiCl solution and over 70 wt% for CH3COOK solution, when the heating temperature is 80 °C. Lower concentration and higher heating temperature will result in larger increase in concentration, higher permeate flux and also lower specific energy consumption. But due to the configuration of the system, optimal flow rates can be found under different conditions. Within the testing region, the permeate flux ranges between 0.147-1.802 l/(m2h) for LiCl solution and 0.189-1.263 l/(m2h) for CH3COOK solution. With low concentration, high heating temperature and low feed flow rate, low specific energy consumptions, 0.85 kWh/l and 0.94 kWh/l for LiCl and CH3COOK solutions are observed respectively. With external heating recovery system, this value can be further reduced.

  • 394.
    Jiao, Yuhe
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    CFD Study On The Thermal Performance of Transformer Disc Windings Without Oil Guides2010Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    The hotspot temperature of disc windings has a close relation with the transformer age. In oil immersed transformers, oil guides are applied generally to enhance the cooling effects for disc windings. In some cases disc windings without oil guides are used. However, the lack of oil guides is expected to result in a more complicated thermal behavior of the windings, making it more difficult to predict the location and strength of the hotspot temperature (i.e. the hottest temperature in the winding). To get an improved understanding of the thermal behavior, a CFD study has been performed.  This article describes the implementation of CFD simulation for 2D axisymmetry models without oil guides, and then analyzes the results of a series of parametric studies to see the sensitive factors influencing the cooling effects. These parameters include radial disc width, inlet mass flow rate, horizontal duct height, vertical duct width and the inlet/outlet configurations. Three main characteristics, the hotspot temperature, the location of the hotspot and the number of oil flow patterns are detected to describe the thermal performance. 

  • 395.
    Jing, Yifu
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Qin, Haiying
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Liu, Qinghua
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Singh, Manish
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Synthesis and electrochemical performances of linicuzn oxides as anode and cathode catalyst for low temperature solid oxide fuel cell2012In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 12, no 6, p. 5102-5105Article in journal (Refereed)
    Abstract [en]

    Low temperature solid oxide fuel cell (LTSOFC, 300-600 °C) is developed with advantages compared to conventional SOFC (800-1000 °C). The electrodes with good catalytic activity, high electronic and ionic conductivity are required to achieve high power output. In this work, a LiNiCuZn oxides as anode and cathode catalyst is prepared by slurry method. The structure and morphology of the prepared LiNiCuZn oxides are characterized by X-ray diffraction and field emission scanning electron microscopy. The LiNiCuZn oxides prepared by slurry method are nano Li 0.28Ni 0.72O, ZnO and CuO compound. The nano-crystallites are congregated to form ball-shape particles with diameter of 800-1000 nm. The LiNiCuZn oxides electrodes exhibits high ion conductivity and low polarization resistance to hydrogen oxidation reaction and oxygen reduction reaction at low temperature. The LTSOFC using the LiNiCuZn oxides electrodes demonstrates good cell performance of 1000 mW cm -2 when it operates at 470 °C. It is considered that nano-composite would be an effective way to develop catalyst for LTSOFC.

  • 396.
    Jinghe, Ren
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Development of a Shrouded SteamTurbine Flutter Test Case2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A shrouded blade was designed as a test case for flutter analysis of steam turbine. Flutter is a self-excitedvibration. It can lead to dramatic blade loss and high-cycle fatigue. Shrouded blade is more complicated onflutter analysis, because the mode shapes are more complex with bending and torsion components atdifferent phases. Moreover, the blade mode shape and frequency also vary with nodal diameter. Lack ofopen resource of shrouded blade, there were less researches about shrouded blade test case on flutter. The initial blade geometry was from Di Qi’s 3D free standing blade test case. The material of the blade isTitanium.

    The aim of current study is to design a 3D test case for realistic shrouded blade flutter analysis. The geometryof the proposed shrouded blade test case was fully described in this thesis report. ANSYS ICEM was usedfor presenting the geometry and generating mesh. ANSYS APDL was used for structural analysis.Parameters of shroud parts were based on literature reviews and engineers’ general suggestions. The modeshapes for the first family of modes were calculated and reported.

  • 397.
    Johansson, Jeff
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Operational Validation of SIMLOX as a Simulation Tool for Wind Energy Operations and Maintenance (O&M)2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis validates SIMLOX as a simulation tool for wind energy operation and maintenance (O&M). SIMLOX have been used for modeling O&M in other sectors since 2002 but have recently begun to be used for simulating wind energy. This study validates SIMLOX for the newly introduced sector by creating a model of an existing offshore wind farm. The model used real historical data as input and the output was compared to real system response quantities (SRQs). Example of SRQs which were compared was time based availability, energy based availability, energy production, weather days, and item replacements. The study showed that SIMLOX is very well suited for this type of studies. It also showed that the major difficulty lies in obtaining proper input data. All models simulated the exact right number of major item replacements. The time based availability was considered to be the most important SRQ. The time based availability turned out to be between 0.11 - 0.66 percentage points too high compared to reference data. This most certainly depended on an overestimated work schedule for the technicians. Validation is the process of determining the degree to which a model is an accurate representation of the real world from the perspective of the intended uses of the model. This report presents all necessary knowledge to validate SIMLOX as a tool for wind energy simulations but it is thus up to the user to decide whether or not the output is accurate enough for their intended use.

  • 398.
    Johansson, Petter
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Business Development and Entrepreneurship.
    Chiu, Justin NingWei
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Impact of Convective Heat Transfer Mechanism in Latent Heat Storage Modeling2012Conference paper (Refereed)
  • 399.
    Jourdier, Bénédicte
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Study and implementation of mesoscale weather forecasting models in the wind industry2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As the wind industry is developing, it is asking for more reliable short-term wind forecasts to better manage the wind farms’ operations and electricity production. Developing new wind farms also requires correct assessments of the long-term wind potentials to decide whether to install a wind farm at a specific location. This thesis is studying a new generation of numerical weather forecasting models, named mesoscale models, to see how they could answer those needs. It is held at the company Maïa Eolis which operates several wind farms in France. A mesoscale model, the Weather Research and Forecasting model (WRF), was chosen and used to generate high resolution forecasts based on lower resolution forecasts from NCEP’s Global Forecasting System.

    The stages for implementation of daily forecasts for the company’s wind farms were: explore and configure the model, automate the runs, develop post-processing tools and forecasts visualization software which was intended to be used by the management team. WRF was also used to downscale wind archives of NCEP’s Final Analysis and determine the possibility to use these in assessing wind potentials. Finally the precision of the model in both cases and for each wind farm was assessed by comparing attained data from the model with real power production.

  • 400.
    Juliusson, Magnus
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    HYDRODYNAMIC OPTIMIZATION OF TWO-DIMENSIONAL MULTI-ELEMENT TRAWL-DOOR SHAPES USING LOCAL SURROGATE MODELS AND ANALYSIS OF CONTROLLABLE TRAWL-DOOR SHAPES2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The study is motivated by the quest to lower the fuel consumption of trawlers and reduce green house gas emissions. Conventional trawl-doors contribute to about one third of the trawlers fuel consumption. Design and optimization of trawl-doors using computational models is vital in minimizing the fuel consumption.The main objective of this work is to develope an optimization algorithm for the shape design of trawl-doors using computational uid dynamic (CFD) models. High-fidelity CFD models are computationally expensive and therefore, conventional optimization methods, which often require large number of evaluations are not feasible. The proposed method is iterative and uses local second order response surface approximation models of the high-fidelity CFD model, constructed in each iteration. The RSA are constructed locally and are regenerated at each iteration in new domain. We use a trust region mechanism to move the center of the search domain and to increase or decrease the size ofthe search domain. This reduces the number of evaluations. We propose novel shaped trawl-door shapes and investigate their performance. These shapes are similar to multi-element airfoils on aircraft i.e., airfoil shapes with slats and flaps. We apply the proposed optimization algorithm to the novel-shaped design of two-dimensional multi-element trawl-door shapes with several design variables controlling the slat and flap positions and alignment. The objective is to increase the hydrodynamic efficiency for a given lift constraint. The results are then compared to the performance of a typical trawl-door shape. The results indicate that a satisfactory design can be obtained at the cost of few iterations of the algorithm. We also investigate controllable trawl-doors where the flap angle can be varied, depending on the operational condition.

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