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  • 201.
    Ellakany, Farid
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Enhancing the Thermo-Economic Performance of a Direct Steam Generation Solar Tower Power Plant through the Implementation of Steam Flow Control Strategies for Flexible Operation2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Above 90% of the current installed concentrating solar power plants are based on conventional steam-turbine cycles. The operation of steam turbines in these plants is distinctive when compared to traditional base-load power plants. The reason goes back to the intermittent nature of solar power which, in the absence of thermal energy storage or a back-up combustion boiler, forces plant operators to shut down the turbines during night time or at times of low solar radiation. Furthermore, such intermittency often leads to undesirable off-design turbine operating circumstances, either by load variations or changes on live-steam conditions.The present study examines the influence of implementing two operating strategies dealing with steam flow control as a function of incoming solar power for enhancing the thermo-economic performance of a direct steam generation solar tower power plant. The first one consists of a simultaneous high pressure turbine stage- and feed-water preheater bypass. This strategy is used during periods in which the solar radiation is higher than nominal. On these occasions, the plant is capable of generating a larger flow of steam, which allows for an increase in the power production when inserting the additional steam in the turbine bypass. On the other hand, the second operating strategy consists of using an additional feed-water preheater when the power from the field is lower than nominal. In this way, the feed water can reach a higher temperature prior entering the boiler, which is not only beneficial during times of cloud-passages, but also during the start-up process.A dynamic model of a direct steam generation solar tower power plant has been developed following design and operation specifications of an existing reference plant. The two proposed strategies were implemented to the reference model, then a whole year worth simulation was performed for both the reference and the modified models. Lastly, the thermodynamic and economic performance of both systems was measured for the purpose of comparison, by means of using KTH in-house tool DYESOPT. Results show that the implementation of the proposed strategies can enhance the economic viability of the systems by yielding a reduction of 8.7% on the levelized cost of electricity, mainly due to allowing achieving a 12% increase in the net electricity production.

  • 202.
    Endale Turie, Samson
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Gas Turbine Plant Modeling for Dynamic Simulation2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Gas turbines have become effective in industrial applications for electric and thermal energy production partly due to their quick response to load variations. A gas turbine power plant is a complex assembly of a varietyof components that are designed on the basis of aero thermodynamiclaws.

    This thesis work presents model development of a single-shaft gas turbine plant cycle that can operate at wide range of load settings in complete dynamic GTP simulator. The modeling and simulation has been done in Dymola 7.3, based on the Modelica programming language. The gas turbine plant model is developed on component-oriented basis. This means that the model is built up by smaller model classes. With this modeling approach, the models become flexible and user-friendly for different plant operational modes.

    The component models of the main steady-state compressor and turbine stages have been integrated with gas plenum models for capturing the performance dynamics of the gas turbine power plant. The method of assembly used for gas turbine plant integration is based on models of the components from an engineering process scheme.

    In order to obtain an accurate description of the gas-turbine working principle, each component is described by a non-linear set of both algebraic and first-order differential equations. The thesis project provides descriptions of the mathematical equations used for component modeling and simulation. A complete dynamic simulation of a gas-turbine plant has been performed by connecting the complete plant model with PI controllers for both design and off-design operating modes.

    Furthermore, turbine blade cooling has been studied to evaluate the changes in power output. This has been done to compare and analyze the blade cooling effect.

  • 203.
    Eppanapelli, Lavan Kumar
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Investigation of wind potential variation at three measurement sites based on atmospheric stability and power production2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As tapping energy from wind expands rapidly worldwide, it is a common procedure to locate a practicable site to extract energy from abundant wind flow by building wind farms. Comprehensive understanding of wind resource at a site   is important to perform the main activities say, wind flow modeling, wind   turbines micro siting, annual energy yield calculation and cost of energy   estimation. Wind measuring campaigns involve using of measuring instruments   such as meteorological tower instrumented with anemometers, wind vanes and   temperature sensors; remote sensing devices such as SoDAR, LiDAR. These   meteorological devices provide detailed information on wind behavior with   respect to the height, time and temperature. These systems were proven in   providing promising wind measurements even though they are susceptible to   certain weather conditions.

    The   study progressed by focusing on the wind behavior at three locations to   investigate the possible factors that varies the wind character. A location   with one met mast and two AQ500 SoDAR systems was considered for this project   where one AQ500 is 800m away and other AQ500 is 5515m away from the point of   Met mast. The location is contemplated as a decent approach to the spatial   analysis of the wind resource as there is a large scope to analyze the wind   character between two nearby sites and two faraway sites. Monostatic 3-beam   SoDAR systems from AQ System, Sweden and 100m meteorological tower with   instruments are used in this project work for collecting the wind data.   One-year worth of wind data at standard 10min intervals has been collected   from the three systems.

    This report outlines the theoretical description of project location, AQ500 SoDAR and Met mast. A detailed explanation of the data quality control and filtering methods are discussed along with respective reasons. The conclusion is drawn after performing the statistical analysis between wind speed and other parameters such as turbulent intensity, wind direction, thermal stability and temperature. Mat lab is used for computing and analyzing the wind data from three systems.

  • 204.
    EREK, ERMAN
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    k-ε turbulence modeling for a wind turbine: Comparison of RANS simulations with ECN wind turbine test site Wieringermeer (EWTW) measurements2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this report we discuss the use of k-ε RANS (Reynolds-averaged Navier-Stokes equations) turbulence model for wind turbine applications. This model has been implemented in the new wind turbine wake CFD code that is being developed at ECN. Simulations of the wind turbine test site EWTW are compared with measurements conducted between 2005 and 2009 and with FarmFlow, ECN's current wind turbine wake code. Based on the results the uncertainties in the current approach are highlighted and areas for possible improvement are discussed.

  • 205.
    Eric, MANIRAGUHA
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. KIST-Rwanda.
    UTILIZATION OF WIND POWER IN RWANDA: Design and Production Option2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This Master Thesis is the research done in the country of Rwanda. The project leads to study the climate of this country in order to establish whether this climate could be used to produce energy from air and to implement the first wind turbine for serving the nation.

     

    After an introduction about the historical background of wind power, the thesis work deals with assessment of wind energy potential of Rwanda in focusing of the most suitable place for wind power plants. The best location with annual mean wind speed, the rate of use of turbine with hub height for an annual production per year, the mean wind speeds for 6 sites of Rwanda based on ECMWF for climatic data for one year at relief of altitude of 100m and coordinates are reported too.

     

    The result of energy produced and calculations were done based on power hitting wind turbine generator in order to calculate Kinetic energy and power available at the best location to the measurement over the period of 12 months, that could be hoped for long term.

     

    With help of logarithmic law, where wind speed usually increases with increasing in elevation and the desired wind speeds at all 6 sites were used. The annual energy production was taken into account at the best site with desired wind speed at the initial cost of turbine as well as the cost of energy (COE).However, with comparison of the tariff of EWSA, the price of Wind designed in this Research per kWh is cheaper and suitable for people of Rwanda.

  • 206.
    Eriksson, Kristina
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Persson, Henrik
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Performance and size assessment of ORCs in mobile military power generation2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this study the suitability of small-scale organic Rankine cycles in military power generation is evaluated. It is presupposed that external combustion engines have favorable characteristics in terms of noise, heat and vibration signals.The work is conducted through a process consisting of three blocks; working fluid selection, component selection and modeling. The research community states that the optimal fluid is a matter of application. Therefore, a screening of working fluids is performed on the basis of a few key properties. A simplistic cycle model is used to determine the operating conditions that yield the best thermodynamic performance. Consequently, these conditions are the starting point of the component selection process. Each component that is selected introduces restrictions to the cycle. The upper pressure is, for example, limited by the material of the boiler. Therefore, an iterative selection methodology is employed in order to consider both cycle performance and component limitations. In the last block the model is refined with realistic properties of the selected components. Size and performance of the system are evaluated for electric outputs between 0.1 and 3.0 kW. The model is realized in Excel VBA and constructed for high user flexibility.It is found that the thermal efficiency is proportional to the size of the system. A water-methanol mixture passes the screening process and provides the best cycle performance. Also, scroll expanders are recommended as the prime mover of the system. With the proposed components, the realizable power range is between 1.8 and 3.0 kW. The most critical components, in terms of size, are the expander and condenser. Finally, this study indicates that the system can be built in sizes competitive to existing solutions.

  • 207.
    Erives Anchondo, Ruben
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Validation of non-linear time marching and time-linearised CFD solvers used for flutter prediction2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The turbomachinery related industry relies heavily on numerical tools for the design and development of modern turbomachines. In order to be competitive turbomachines ought to be highly efficient and robust. This has lead engineers to develop more aggressive designs, which often leads to lower margins of structural reliability.  One of the strongest threats to turbomachines are high cycle fatigue problems which arise from aeroelastic phenomena such as flutter. According to Kielb R. (2013) many of such problems are detected at developing testing stage. This implies that the prediction capabilities for aeroelastic phenomena are in need of further development and/or tuning. This is especially evident for unsteady flow phenomena at transonic regimes.

    A very important step for the improvement of unsteady aerodynamic solvers is the validation and comparison of such solvers. The present thesis concerns with the validation and comparison of a non-linear time marching (ANSYS CFX) and the GKN’s in-house linearised solvers used for flutter analysis. The former has recently implemented a new feature called Transient Blade Row TBR, which drastically reduces the simulation domain to a maximum of two blades.  In order to be included in the deign process, such tool need to be validated. In the same way, the recently launched in-house code LINNEA needs to be validated in order to be considered as a design tool. Experimental data from the aeroelastic standard configuration 4, and the FUTURE project were used for the validation purposes. The validation process showed that the solvers agreed very well between them for the standard configuration. Such agreement was less clear for the FUTURE compressor; nonetheless, the solutions still sit within the bulk of solutions provided from the different FUTURE partners. The validation showed that these tools provide with similar results as the state of the art tools from different companies. This indicates that they can be used in the design process. At the same time it was observed that there is room for improvement in the solvers, as these still present some considerable differences with the experimental results.

  • 208.
    Erlich, Catharina
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Björnbom, Emilia
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Bolado, David
    Giner, Marian
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Pyrolysis and gasification of pellets from sugar cane bagasse and wood2006In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 85, no 10-11, p. 1535-1540Article in journal (Refereed)
    Abstract [en]

    Wood pellets have become a popular form of biomass for power generation and residential heating due to easier handling both for transportation and for feeders in the treatment units, improved conversion and storage possibilities. The research on wood pellets as fuel has also been intensified during the past decade. However, other biomass sorts in pellet form, such as sugar cane bagasse, have not yet been extensively studied, especially not physical effects on the pellets during thermal treatment. Bagasse and wood pellets of different origin and sizes, shredded bagasse and wood chips have been studied in a thermogravimetric equipment to compare the effects of sort, origin, size and form of biomass during slow pyrolysis and steam gasification. Physical parameters such as decrease of volume and mass during treatment, as well as pyrolysis and gasification rates are of primary interest in the study. An important observation from the study is that for pellets the char density decreased during pyrolysis to a minimum around 450 degrees C, but thereafter increased with continued heating. The wood chips behaved differently with a continuous char density decrease during pyrolysis. Another conclusion from the work is that the size of the pellet has larger impact on the shrinkage behaviour throughout the conversion than the raw material, which the pellet is made of.

  • 209.
    Erlich, Catharina
    et al.
    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.
    Downdraft gasification of pellets made of wood, palm-oil residues respective bagasse: Experimental study2011In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 88, no 3, p. 899-908Article in journal (Refereed)
    Abstract [en]

    The downdraft gasification technology has an increased interest among researchers worldwide due to the possibility to produce mechanical and electrical power from biomass in small-scale to an affordable price. The research is generally focused on improvement of the performance and optimizing of a certain gasifier, on testing different fuels, on increasing the user-friendliness of the gasifier and on finding other uses for the product gas than in an IC-engine, for example liquid fuel production.

    The main objective with the gasification tests presented here is to further contribute in the field by studying the impact of the char bed properties such as char bed porosity and pressure drop on the gasification performance as well as the impact of fuel particle size and composition on the gasification process in one and the same gasifier. In addition, there is very little gasification data available in literature of “before disregarded” fuels such as sugar cane bagasse from sugar/alcohol production and empty fruit bunch (EFB) from the palm-oil production. By pelletizing these residues, it is possible to introduce them into downdraft gasification technology which has been done in this study.

    The results show that one and the same reactor can be used for a variety of fuels in pellet form, but at varying air–fuel ratios, temperature levels, gas compositions and lower heating values. Gasification of wood pellets results in a richer producer gas while EFB pellets give a poorer one with higher contents of non-combustible compounds. In this gasification study, there is almost linear relation between the air–fuel ratio and the cold-gas efficiency for the studied fuels: Higher air–fuel ratios result in better efficiency. The pressure drop in the char bed is higher for more reactive fuels, which in turn is caused by low porosity char beds.

  • 210.
    Erlich, Catharina
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Gomez, M
    Hedman, H
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Milling and pelletizing residues from cane sugar and palm oil industries: Physical parameters and electrical energy consumption2009Other (Other academic)
  • 211.
    Erlich, Catharina
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Salomon Popa, Marianne
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    An Extensive Technical, Economical and Environmental Assessment of Energy Recovery from Palm-Oil Residues: SWE-2005-3862009Report (Other academic)
    Abstract [en]

    The Dept. of Energy Technology at KTH, together with Universidad Autónoma de Bucaramanga, Colombia, studied the different possibilities for increasing the usage of palm oil residues for energy production in an optimized way. The main purpose was to maximize the use of the solid residues coming from palm oil extraction, substitute fossil fuels in cooking, reduce emissions and environmental impacts and improve the social/economic conditions of the region. The emphasis was in introducing the discarded solid residues – EFB - as a fuel and the effective use of fibres and shells. The study was based on several innovative and unique approaches that include the pelletization of EFB for gasification purposes, densification of fibres and shells for their use in different energy applications, anaerobic digestion of EFB for biogas production and a complete optimization of the energy system considering efficiency, technology availability, environmental issues and economic factors.

  • 212.
    Erlich, Catharina
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Öhman, Marcus
    Umeå Universitet.
    Björnbom, Emilia
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Thermochemical characteristics of sugar cane bagasse pellets2005In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 84, no 5, p. 569-575Article in journal (Refereed)
    Abstract [en]

    Pelletisation facilitates utilisation of sugar cane bagasse as a fuel and storage for year-round electricity generation. The present work determines thermochemical characteristics of bagasse pellets of different sizes and origins, using various temperatures (600, 750 and 900 degrees C) and gas flow rates (4, 7 and 10 L/min) with varying concentrations of oxygen (5, 10 and 15 %) in mixtures with nitrogen. Of major interest are the effects of raw material, origin and size of pellets, and the treatment conditions on the rate of pyrolysis and the structure and reactivity of char in combustion. The char yield of the larger pellets of high-ash content bagasse was practically independent of treatment conditions. Smaller pellets gave better mechanical stability of the char but lower reactivity.

  • 213.
    Ertl, Felix
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Exergoeconomic Analysis and Benchmark of a Solar Power Tower with Open Air Receiver Technology2012Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
  • 214.
    Estrada, Juan Sebastián
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Solar application of TopSpool gas turbine concept2011Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    The TopSpool gas turbine concept has been proposed as a high efficiency – lower cost alternative to combined cycles for power generation. In the TopSpool concept, a dual gas turbine system comprising separate low pressure and high pressure turbines with steam injection is proposed.

    An initial technical and economical comparison was performed between the TopSpool cycle concept and a combined cycle for power generation in a configuration of power tower concentrated solar power plant.

    A steady state model was developed and updated and used to evaluate which of the technologies can generate power at the lower levelized cost of electricity. The model includes a thermodynamic calculation of the power cycles, calculation of the solar field and receiver, fluid transport pipes, and economical evaluation based on the levelized cost of electricity. Some particular design aspects have been addressed preliminarily and suggestions for further development are proposed.

    The results show that the TopSpool configuration can offer higher efficiency, higher annual solar share and lower levelized cost of electricity compared to a combined cycle configuration. The main limiting factor is the rate of supplementary firing, which is directly influenced by the solar receiver outlet temperature.

  • 215.
    Etienne, Eliane Marie Christina
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Opportunities and constraints for the manufacture of bio-ethanol for transportation needs in Mauritius2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Republic of Mauritius comprises a main island of an area of 1870km2 at latitude 200 south and longitude 580 east and several outer islands, all of volcanic origin. Mauritius has no known oil, natural gas or coal reserves and is therefore heavily dependent on imported energy sources. In 2012, some 458 ktoe of energy were used for transportation, representing an increase from 391 ktoe in 2009 and 418 ktoe of energy in 2010. The consumption of gasoline increased from 121 ktoe to 128 ktoe (+5.8%) and that of diesel oil from 155 ktoe to 162 ktoe (+4.5%). The consumption of aviation fuel increased from 110 ktoe in 2009 compared to 123 ktoe in 2010 (+11.8%) to 146 ktoe in 2012. In Mauritius the transport sector is the heaviest energy consumer, accounting for 48% of total energy imports and pollution problems in term of vehicular emissions which are more acute in towns where there is heavy vehicular traffic. Mauritius as an island state cannot have the benefit of interconnection facilities and the reliance on fossil fuels can only impact severely on the island in case of crisis

    In 2006, a comprehensive set of strategies regrouped under the Multi Annual Adaptation Strategy (MAAS) was thus prepared jointly between the Government of Mauritius and the stakeholders in the sugar sector with the objective to investigate the environmental challenges and considerations to produce a comprehensive set of strategies to maintain the commercial viability and sustainability of the sugar sector. The plan that emerged from the MAAS comprised several measures including the transformation of the sugar industry into a sugarcane cluster coupled with the production of a minimum of 30 million litres of ethanol annually. One local ethanol manufacturer is exporting ethanol on regular basis to foreign markets. Export of ethanol has the added advantage of bringing foreign currency to the country and would be encouraged.

    In line with the Maurice Ile Durable project, to provide with a long-term strategy to progressively reduce the country’s dependence on fossil fuel, the implementation of an ethanol plant in the south of the island, after centralization of the sugar factory activities, has been considered. A case study has been carried out for setting up a 15 million liters dehydrated ethanol plant annexed to the sugar factory.  The cost analysis showed that the annual revenue from the ethanol plant will be $17, 250, 000 and that the payback period will be of 2.9 years.

    It has been concluded that centralization of sugarcane industry provides with feedstock, with steam and power and minimize transportation costs, thereby increasing the operational and economical cost of ethanol production plant. The amount of molasses that will be produced at each cluster will be some 45 000 tons of molasses and for optimized operating plant, producing more than 20 million liters of dehydrated ethanol, final molasses will have to be outsourced from the other sugar factories on the island.

  • 216.
    Fakhrai, Reza
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Saadatfar, Bahram
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Feasibility study and quality assurance of the end-product of Alphakat KDV technology for conversion of biomass2015Report (Other academic)
    Abstract [sv]

    För närvarande finns det ett stort intresse att utveckla ett ekonomiskt och framkomligt system för omvandling av biomassa till flytande bränslen och kemikalier, då hanteringen av bränslen väsentligt underlättas.

    Under 2014, fick avdelningen för Energiteknik, KTH, uppdraget att undersöka och dokumentera KDVs process för konvertering av biomassa till flytande bränsle: Bland annat ingick att analysera processens produkt och restprodukter. Idag marknadsförs tekniken av Alphakat, Eppendorf, Tyskland. Alphakat gör gällande att KDV erbjuder en alternativ teknik för produktion av bränsle, inklusive syntetisk-diesel från fasta bränslen såsom biomassa. Det övergripande syftet med projektet var att samla information, tekniska data, processdata och genomföra test och analysera produkten. Detta för att få en uppfattning om huruvida KDV kan tekniskt användas föratt konvertera biomassa till diesel. Emellertid, KDVs tekniska potential, särskilt för omvandling av biomassa till flytande bränsle kunde inte bevisas baserat på resultaten av den nu aktuella undersökningen med den tillhandahållna informationen av företaget.

    Produkten av processen analyserades enligt ASTM D6715. De relevanta egenskaperna för KDVs produkt dokumenterades genom noggranna tester. Men huruvida produkten kommer från biomassa kunde inte garanteras då KDV är en oljebaserad process. Påverkan av så kallade “Carrier oil”, på produktens kvalitet och kvantitet kan vara betydande då en stor del av värmevärdet hos bränslet kan komma från denna olja. KDVs potential för produktion av flytande bränsle från biomassa kan inte bevisas.

    Vi bedömer att en fördjupad teknisk och vetenskaplig utvärdering av KDV är ett nödvändigt och viktigt steg för att framtiden underlätta kommande investeringar i KDVs teknologin. Denna utvärdering bör utföras i en laboratorieskala, med hjälp av avancerad mätutrustning, i en kontrollerad miljö som kunde garantera vetenskaplig dokumentation och övervakning av processen.

    Förvätskning av biomassa ser vi som lovande då faktorer som medger attförnybara bränslen och kemikalier då kan göras tillgängliga för en allmän användning då de har en stor miljömässig fördel.

  • 217.
    Fakhrai, Reza
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Saadatfar, Bahram
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Multi-disciplinary problem based learning in computational fluid dynamics2014In: STAR Global Conference 2014, Vienna Austria, 2014Conference paper (Refereed)
    Abstract [en]

    KTH Royal Institute of Technology (KTH) is one of European’s key centers of innovation and intellectual talent for almost two centuries. Recognized as Sweden’s most prestigious technical university, KTH is also the country’s oldest and largest. Computerized simulation technique was recognized as a fundamental component of the higher-education sector at KTH as early as the fifties. Although the utilization of these tools in research is now considered to be standard, the educational aspects are not. In this field, the method of instruction followed by practice is considered to be a superior pedagogic method compared to lecture to many. The current method emphasizes on demonstrative activities of the learners known as phenomeno-graphic learning. However, phenomeno-graphic learning is viable if there are breadth and depth in the physic, mathematic, computer science and graphic, operational strategy and methodology, etc. illuminating weakness of learning by doing method.  

    This work aims to report the success and progress of the course, numerical methods in energy technology, which utilizes Computational Fluid Dynamics cods such as STAR-CCM+ as the tool. Learning methodology is based on instructional design and andragogically approach that offers an elaboration on the mechanism of learning process and its premeditated in context of a prescribed framework. The results indicated the prominence of student sensitive and constructive learning process and the advantages of using a preferred framework in guiding the students in a pertinent context (area). The method particularly incorporates the constructivist principles that lead to enhance the learning process. In addition, the conclusions of this study similarly illuminate the vast potentials of computational fluid dynamic for research, evaluation and educational purposes.

  • 218.
    Fakhrai, Reza
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Saadatfar, Bahram
    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.
    The Role of Continuance Project Based Learning in Energy Educational Program2014Conference paper (Refereed)
  • 219.
    Fakhrai, Reza
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Saadatfar, Bahram
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Khodabandeh, Rahmat
    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.
    Utilization Of Numerical Methods In Context Of Learning Process Enhancement For Mutli-Disciplinary Field Of Science2012In: INTED2012 Proceedings: 6th International Technology, Education and Development Conference Valencia, Spain. 5-7 March, 2012, Iated , 2012, p. 6138-6143Conference paper (Refereed)
    Abstract [en]

    Computerized simulation technique is a fundamental component of the higher education and is a vital mechanism, utilized in phenomena-graphic studies in science. The system offers recreation of an alternative reality in front of scientist's eyes, giving an insight into the biggest and smallest scales (astronomy to nanotechnology) yet cannot be comprehended otherwise. Currently the tool is utilized in research and taught one on one. The progress in computational technology and the advent of commercial codes equipped with user-friendly interface have facilities the introduction of computational fluid dynamic in undergraduate education promoting critique of various learning opportunities through visualization technique. Nevertheless the outcomes of each study is highly influenced by the ideas, approaches, knowledge in phenomena, mathematical rules and measures, computer science, cads, post processing and interpretation of the results. The user of such system acts as the facilitator and liaison between the real and virtual phenomena. The user should own the proper education, experience, emphasizing the relevance of the teaching strategy; understanding the key mechanisms in learning process. Unlocking the full power of computational fluid dynamic, some critical topics in educational area need to be addressed. One is to identify the learning process, approaches and methodology. One task with three different definitions was given to groups and the data regarding the learning process, strategies for solving the problem adapted by students for, engagements of the participants in work was monitored. The data were gathered through a net based learning tool. The progress of the groups were scrutinized weekly, aiming at directing the group in pre-define learning scope. This work is based on instructional design and andragogically approach. It offers an elaboration on the mechanism of learning process and is premeditated in context of prescribed framework. The results indicated the prominence of student sensitive and constructive learning process and the advantages of using a preferred framework in guiding the students in pertinent context (area) particularly incorporation of constructivist principles that may lead to enhance learner's learning experience. In addition, the conclusions of this study similarly illuminate the vast potentials of computational fluid dynamic for research, evaluation and educational purposes.

  • 220. Fan, L.
    et al.
    Afzal, Muhammad
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    He, C.
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Hubei University, China.
    Nanocomposites for "nano green energy" applications2017In: Bioenergy Systems for the Future: Prospects for Biofuels and Biohydrogen, Elsevier, 2017, p. 421-449Chapter in book (Refereed)
    Abstract [en]

    The efficient conversion of fuel's chemical energy into electricity in solid oxide fuel cell (SOFC), one of the promising candidates to replace the current combustion process, requires highly active cell components for quick charge transfer and reaction kinetics in the current low-temperature range. Operation at low temperatures enables the deployment of nanostructured materials, while the nanostructured cell components with improved electric properties further assist the reduction of the temperature for given power output. One of the major issues of the single-phase nanoparticle is its aggregation properties under harsh fuel-cell condition, which could be overcome or alleviated by the advanced approaches. Nanocomposite approach not only addresses the instability and some intrinsic issues with the single-phase materials but also brings the interesting synergetic electric properties with multifunctionality. We summarize the research activities in a range of nanocomposite materials in SOFCs in finding the positive roles to improve the cell components (anode, electrolyte, and cathode) electrochemical performances and cell efficiency for green energy applications.

  • 221. Fan, L.
    et al.
    He, C.
    Zhu, Binzhu
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Hubei University Wuhan, China.
    Role of carbonate phase in ceria-carbonate composite for low temperature solid oxide fuel cells: A review2016In: International journal of energy research (Print), ISSN 0363-907X, E-ISSN 1099-114XArticle in journal (Refereed)
    Abstract [en]

    Ceria-salt composites represent one type of promising electrolyte candidates for low temperature solid oxide fuel cells (LT-SOFCs), in which ceria-carbonate attracts particular attention because of its impressive ionic conductivity and unique hybrid ionic conduction behavior compared with the commonly used single-phase electrolyte materials. It has been demonstrated that the introduction of carbonate in these new ceria-based composite materials initiates multi new functionalities over single-phase oxide, which therefore needs a comprehensive understanding and review focus. In this review, the roles of carbonate in the ceria-carbonate composites and composite electrolyte-based LT-SOFCs are analyzed from the aspects of sintering aid, electrolyte densification reagent, electrolyte/electrode interfacial 'glue' and sources of super oxygen ionic and proton conduction, as well as the oxygen reduction reaction promoter for the first time. This summary remarks the significance of carbonate in the ceria-carbonate composites for low temperature, 300-600°C, SOFCs and related highly efficient energy conversion applications.

  • 222.
    Fan, Liangdong
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Development and characterization of functional composite materials for advanced energy conversion technologies2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The solid oxide fuel cell (SOFC) is a potential high efficient electrochemical device for vehicles, auxiliary power units and large-scale stationary power plants combined heat and power application. The main challenges of this technology for market acceptance are associated with cost and lifetime due to the high temperature (700-1000 oC) operation and complex cell structure, i.e. the conventional membrane electrode assemblies. Therefore, it has become a top R&D goal to develop SOFCs for lower temperatures, preferably below 600 oC. To address those above problems, within the framework of this thesis, two kinds of innovative approaches are adopted. One is developing functional composite materials with desirable electrical properties at the reduced temperature, which results of the research on ceria-based composite based low temperature ceramic fuel cell (LTCFC). The other one is discovering novel energy conversion technology - Single-component/ electrolyte-free fuel cell (EFFC), in which the electrolyte layer of conventional SOFC is physically removed while this device still exhibits the fuel cell function. Thus, the focus of this thesis is then put on the characterization of materials physical and electrochemical properties for those advanced energy conversion applications. The major scientific content and contribution to this challenging field are divided into four aspects except the Introduction, Experiments and Conclusions parts. They are:

    1. Continuous developments and optimizations of advanced electrolyte materials, ceria-carbonate composite, for LTCFC. An electrolysis study has been carried out on ceria-carbonate composite based LTCFC with cheap Ni-based electrodes. Both oxygen ion and proton conductance in electrolysis mode are observed. High current outputs have been achieved at the given electrolysis voltage below 600 oC. This study also provides alternative manner for high efficient hydrogen production.
    2.  Compatible and high active electrode development for ceria-carbonate composite electrolyte based LTCFC. A symmetrical fuel cell configuration is intentionally employed. The electro-catalytic activities of novel symmetrical transition metal oxide composite electrode toward hydrogen oxidation reaction and oxygen reduction reaction have been experimentally investigated. In addition, the origin of high activity of transition metal oxide composite electrode is studied, which is believed to relate to the hydration effect of the composite oxide.
    3. A novel all-nanocomposite fuel cell (ANFC) concept proposal and feasibility demonstration. The ANFC is successfully constructed by Ni/Fe-SDC anode, SDC-carbonate electrolyte and lithiated NiO/ZnO cathode at an extremely low in-situ sintering temperature, 600 oC. The ANFC manifests excellent fuel cell performance (over 550 mWcm-2 at 600 oC) and a good short-term operation as well as thermo-cycling stability. All results demonstrated its feasibility and potential for energy conversion.
    4. Fundamental study results on breakthrough research Single-Component/Electrolyte-Free Fuel Cell (EFFC) based on above nanocomposite materials (ion and semi-conductive composite) research activities. This is also the key innovation point of this thesis. Compared with classic three-layer fuel cells, EFFC with an electrolyte layer shows a much simpler but more efficient way for energy conversion. The physical-electrical properties of composite, the effects of cell configuration and parameters on cell performance, materials composition and cell fabrication process optimization, micro electrochemical reaction process and possible working principle were systematically investigated and discussed. Besides, the EFFC, joining solar cell and fuel cell working principle, is suggested to provide a research platform for integrating multi-energy-related device and technology application, such as fuel cell, electrolysis, solar cell and micro-reactor etc.

    This thesis provides a new methodology for materials and system innovation for the fuel cell community, which is expected to accelerate the wide implementation of this high efficient and green fuel cell technology and open new horizons for other related research fields.

  • 223.
    Fan, Liangdong
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Faculty of Physics and Electronic Tech-nology, Hubei University, Wuhan, China .
    Afzal, Mohammed
    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. Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Faculty of Physics and Electronic Tech-nology, Hubei University, Wuhan, China .
    Electrolysis study of ceria-carbonate composite for effective H2 production2013In: EFC 2013 - Proceedings of the 5th European Fuel Cell Piero Lunghi Conference, 2013, p. 79-80Conference paper (Refereed)
    Abstract [en]

    The hybrid ionic conduction of ceria-carbonate composite is an interesting field that has attracted plenty attention in the past decade. However, it has not reached universal agreement among the researcher. Novel characterization method is still needed to reveal this complex system and benefit the future advanced materials design and development. In this work, the electrolysis operation is employed to investigate the possible ionic conduction behavior of ceria-carbonate. The other goal is to optimize the processing technology to maximum the kinetics rate for efficient hydrogen production. An impressive current density of 1.2 A cm-2 has been achieved at 600 °C under voltage of 1.6 V at the absolute humidity of 3% and oxygen ionic operational mode.

  • 224.
    Fan, Liangdong
    et al.
    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.
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Effective hydrogen production by high temperature electrolysis with ceria-carbonate compositeManuscript (preprint) (Other academic)
    Abstract [en]

    The high temperature electrolysis potentially offers an effective approach for large-scale and high purity hydrogen production. Besides, the research on the hybrid oxygen ion/proton conductive behavior is a hot field in the ceria-based composite field. In this present study, single cell assembled by SDC-carbonate electrolyte and Ni-based electrode was fabricated and operated in ceramic electrolysis cells (CECs) model. The effect of the relative humidity and temperature on the electrochemical performance was investigated by electrochemical impedance spectra (EIS) and polarization curves. Under an applied electrolysis voltage of 1.6 V, the maximum consumed current density is 1.2 Acm-2 in oxygen ionic conduction mode. The electrochemical performance in proton conduction mode is comparable to the oxygen ion conduction mode. The results here again demonstrate the hybrid ionic conduction of ceria-carbonate composite, and provide a promising materials system for high efficient hydrogen production.

  • 225.
    Fan, Liangdong
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Chen, Mingming
    Tianjin University, China.
    Wang, Chengyang
    Tianjin University, China.
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Pr2NiO4–Ag composite cathode for low temperature solid oxide fuel cells with ceria-carbonate composite electrolyte2012In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 37, no 24, p. 19388-19394Article in journal (Refereed)
    Abstract [en]

    Pr2NiO4-Ag composite was synthesized and evaluated as cathode component for low temperature solid oxide fuel cells based on ceria-carbonate composite electrolyte. X-ray diffraction analysis reveals that the formation of a single phase K2NiF4-type structure occurs at 1000 °C and Pr2NiO4-Ag composite shows chemically compatible with the composite electrolyte. Symmetrical cells impedance measurements prove that Ag displays acceptable electrocatalytic activity toward oxygen reduction reaction at the temperature range of 500-600 °C. Single cells with Ag active component electrodes present better electrochemical performances than those of Ag-free cells. An improved maximum power density of 695 mW cm-2 was achieved at 600 °C using Pr 2NiO4-Ag composite cathode, with humidified hydrogen as fuel and air as the oxidant. Preliminary results suggest that Pr 2NiO4-Ag composite could be adopted as an alternative cathode for low temperature solid oxide fuel cells.

  • 226.
    Fan, Liangdong
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Ma, Ying
    Wang, Xiaodi
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    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.
    Understanding the electrochemical mechanism of the core-shell ceria-LiZnO nanocomposite in a low temperature solid oxide fuel cell2014In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 2, no 15, p. 5399-5407Article in journal (Refereed)
    Abstract [en]

    Ceria based solid solutions have been considered some of the best candidates to develop intermediate/low temperature solid oxide fuel cells (IT/LT-SOFCs, 600-800 degrees C). However, the barrier to commercialization has not been overcome even after numerous research activities due to its inherent electronic conduction in a reducing atmosphere and inadequate ionic conductivity at low temperatures. The present work reports a new type of all-oxide nanocomposite electrolyte material based on a semiconductor, Li-doped ZnO (LixZnO), and an ionic conductor, samarium doped ceria (SDC). This electrolyte exhibits superionic conductivity (>0.1 S cm(-1) over 300 degrees C), net-electron free and excellent electrolytic performances (400-630 mW cm(-2)) between 480 and 550 degrees C. Particularly, defects related to interfacial conduction and the intrinsic and extrinsic properties of ions are analysed. An internal or interfacial redox process on two-phase particles is suggested as a powerful methodology to overcome the internal short-circuit problem of ceria-based single phase materials and to develop new advanced materials for energy related applications. The combination of the above promising features makes the SDC-LiZnO nanocomposite a promising electrolyte for LTSOFCs.

  • 227.
    Fan, Liangdong
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Wang, C.
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Low temperature ceramic fuel cells using all nano composite materials2012In: Nano Energy, ISSN 2211-2855, Vol. 1, no 4, p. 631-639Article in journal (Refereed)
    Abstract [en]

    The shift to low operational temperature of solid oxide or ceramic fuel cells has induced many new concepts and novel technologies. In the present study, fuel cell assembled by all nano composite materials - NiO/Fe 2O 3-SDC anode, SDC-carbonate electrolyte and lithiated NiO/ZnO cathode - is investigated. A range of techniques, i.e., X-ray diffraction (XRD), Scanning electron microscopy (SEM) and electrochemical impedance spectroscopy as well as polarization measurements are employed to characterize the crystalline structures, morphologies and electrochemical properties of the synthesized nanocomposite materials and cells. Performance comparison is made between single cells with and without a pre-sintering process. Finally, single cell short term stability and thermo cycle behaviors are also examined. Combined the facile fabrication process, relative high performance and reasonable stability, the current all nanocomposite system may be a promising functional system for low temperature ceramic fuel cells.

  • 228.
    Fan, Liangdong
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Wang, Chengyang
    Chemical engineering and technology.
    Di, Jin
    Tianjin University, China.
    Chen, Mingming
    Chemical engineering and technology.
    Zhen, Jiaming
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Study of Ceria-Carbonate Nanocomposite Electrolytes for Low-Temperature Solid Oxide Fuel Cells2012In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 12, no 6, p. 4941-4945Article in journal (Refereed)
    Abstract [en]

    Composite and nanocomposite samarium doped ceria-carbonates powders were prepared by solidstatereaction, citric acid-nitrate combustion and modified nanocomposite approaches and used aselectrolytes for low temperature solid oxide fuel cells. X-ray Diffraction, Scanning Electron Microscope,low-temperature Nitrogen Adsorption/desorption Experiments, Electrochemical ImpedanceSpectroscopy and fuel cell performance test were employed in characterization of these materials.All powders are nano-size particles with slight aggregation and carbonates are amorphous incomposites. Nanocomposite electrolyte exhibits much lower impedance resistance and higher ionicconductivity than those of the other electrolytes at lower temperature. Fuel cell using the electrolyteprepared by modified nanocomposite approach exhibits the best performance in the whole operationtemperature range and achieves a maximum power density of 839 mW cm−2 at 600 C withH2 as fuel. The excellent physical and electrochemical performances of nanocomposite electrolytemake it a promising candidate for low-temperature solid oxide fuel cells.

  • 229. Fedorov, Yu. N.
    et al.
    Maslov, A. V.
    Ronkin, Yu. L.
    Kutcherov, Vladmir G.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Alekseev, V. P.
    Geochemical investigation of crude oil samples from West Siberia Megabasin2010In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 74, no 12, p. A283-A283Article in journal (Other academic)
  • 230. Feng, B.
    et al.
    Wang, C. -Y
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Catalysts and performances for direct methanol low temperature (300 to 600°C) ceramic fuel cells2005In: Proc. Eur. Fuel Cell Technol. Applic. Conf. Book Abstr., 2005Conference paper (Refereed)
    Abstract [en]

    Low temperature (300 to 600°C) ceramic fuel cells promise high efficiencies in a range of fuels other than pure hydrogen. In this case, liquid hydrocarbon fuels, e.g., methanol can be easily thermally decomposed to H2 and CO that can be directly used for fuel cell operation without external reformer leading to simple system and high efficient operation. In the present work, a novel anode catalyst C-MO-CeO2 (C=activated carbon/carbon black, M=Cu, Ni, Co) was synthesized employing citrate/nitrate combustion technique. And acceptable performances, e.g. power intensity of 0.20 W cm-2, were achieved by directly operating the methanol at 560°C. Also the carbon deposition and cracking on anode were studied as thermal decomposing of methanol. Transition metal oxides of CuO with n-type conductivity and NiO, CoO with p-type conductivity, possess catalytic activity of the electrochemical oxidation for liquid hydrocarbon fuels. CeO2 becomes an oxide-ion and electron mixed conductor in the reducing fuel environment, which can expand the reaction zone beyond three-phase boundaries, can store and transfer oxygen ions, so it can also enhance the catalytic oxidation of methanol. In addition, carbon materials e.g., activated carbon and carbon black were used to improve the characters of anode materials, especially to enhance the anode electronic conductivity and catalyst function to liquid hydrocarbon fuels. In contrast to LaCrO3-based, Ni-YSZ-based anode materials, C-MO-CeO2 can be synthesized more economically. Thus there arc considerable interests and demands in finding alternative anodes composites.

  • 231.
    Fernandes, Rita
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Efficient Volvo Bus Cooling System,Using Electrical Fans: A comparison between hydraulic and electrical fans2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Economical and environmental factors together with energy policies towards more efficient systemsare the driving force for the development of the vehicle industry. Significant changes have beenmade to fulfill new emissions legislation but the basic internal combustion vehicle architecture hasbeen kept. New emission treatment systems that increase the thermal loading of the cooling systemhad been added within the same package envelope as before, which means less space to place coolingfans and a greater need for airflow. Changes in the cooling system, namely the replacement of thehydraulic fan drive system by electrical fans is one of the energy efficient alternatives for severalcity buses under certain environments, like the ”typical red city buses”, well-known in the UnitedKingdom. In this thesis study, hydraulic fans are compared with electrical fans and a road-mapof the benefits and drawbacks of the two systems is developed, based on real traffic performanceperformance data and the results of existing simulations and tests. In addition, new simulations arepresented in order to find the most efficient design for the cooling system as well as a comparisonof these results with previous ones. This road map will be used later by Volvo-Buses Group as atool to better understand in which circumstances electrical fans can be beneficial, in terms of fuelconsumption, noise production, cooling performance, control of the fans and associated costs.

  • 232.
    Ferria, Hakim
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Experimental Campaign on a Generic Model for Fluid-Structure Interaction Studies2007Independent thesis Advanced level (degree of Master (One Year)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    Fluid-structure interactions appear in many industrial applications in the field of energy technology. As the components are more and more pushed to higher performance, taking fluid-structure interaction phenomena into account has a great impact on the design as well as in the cost and safety. Internal flows related to propulsion systems in aerodynamics area are of our interest; and particularly aeroelasticity and flutter phenomena.

    A new 2D flexible generic model, so called bump, based on previous studies at the division of Heat and Power Technology about fluid-structure interactions is here presented. The overall goal is to enhance comprehension of flutter phenomenon. The current study exposes a preliminary experimental campaign regarding mechanical behaviour on two different test objects: an existing one made of polyurethane and a new one of aluminium. The setup is built in such a way that it allows the bumps to oscillate until 500Hz. The objective is to reach this frequency range by remaining in the first bending mode shape which is indeed considered as fundamental for flutter study. In this manner being as close as possible to the bending flutter configuration in high-subsonic and transonic flows will provide a deeper understanding of the shock wave boundary layer interaction and the force phase angle related to it. The results have pointed out that the bumps can reach a frequency of 250Hz by remaining in the first bending mode shape. The one in polyurethane can even reach frequency up to 350Hz; however, amplitude is higher than the theoretical one fixed to 0.5mm. Then unsteady pressure measurements for one operating point have been performed based on using recessed-mounted pressure transducers with Kulite fast response sensors. Variation amplitudes and phases of the unsteady pressure are thus correlated with the vibrations of the model. The operating point has been defined with respect to previous studies on the same static geometric model in order to use steady state base line; the steady flows appear consistent with each other. The results have pointed out that the shock wave induces strong amplification of the steady static pressure; however, this rise decreases when the reduced frequency increases. Finally some elements regarding propagating waves are suggested in the analysis for deeper investigations on such complex phenomena.

  • 233.
    Ferria, Hakim
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Pacull, François
    Aubert, Stéphane
    Ferrand, Pascal
    Aknouche, Sébastien
    Pouffary, Benoît
    2D Elementary Geometric Decomposition to Study Flutter Motion of a Space Turbine Blisk2009In: PROCEEDINGS OF THE ASME TURBO EXPO 2009, VOL 6, PTS A AND B, 2009, p. 455-463Conference paper (Refereed)
    Abstract [en]

    Within the framework of aerospace turbines, an isolated integral bladed disk is examined. The blisk presents very high eigenfrequencies with complex deformations of the blades.

    A 3D steady RANS computation is at first performed with the aim of characterizing the subsonic flow. Then a simplified 2D approach is considered in order to study fluid-structure interaction and to evaluate the stability: the blades have been found stable.

    In addition, an original method to better understand the level of stability is presented: the blade vibration is decomposed into elementary geometric movements in order to dissociate the different mechanisms that participate to reach stability. With the assumption of first-order behaviors, the linearized RANS unsteady fields corresponding to both the full deformation and the elementary movements are calculated. Some elementary relative blade movements appear to be either stabilizing or destabilizing when looking at the aerodynamic damping coefficient. The coupling between these elementary movements has also been investigated. Either constructive or destructive interference have been observed.

    The conclusions that emerge from this study are in line with the results of the classical bending-torsion flutter theory and lead to the improvement of the structure in terms of stability by modifying its mode shape.

  • 234. Ferruzza, D.
    et al.
    Topel, Monika
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Basaran, Ibrahim
    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.
    Haglind, F.
    Start-up performance of parabolic trough concentrating solar power plants2017In: SOLARPACES 2016: International Conference on Concentrating Solar Power and Chemical Energy Systems, American Institute of Physics (AIP), 2017, Vol. 1850, article id 160008Conference paper (Refereed)
    Abstract [en]

    Concentrating solar power plants, even though they can be integrated with thermal energy storage, are still subjected to cyclic start-up and shut-downs. As a consequence, in order to maximize their profitability and performance, the flexibility with respect to transient operations is essential. In this regard, two of the key components identified are the steam generation system and steam turbine. In general it is desirable to have fast ramp-up rates during the start-up of a power plant. However ramp-up rates are limited by, among other things, thermal stresses, which if high enough can compromise the life of the components. Moreover, from an operability perspective it might not be optimal to have designs for the highest heating rates, as there may be other components limiting the power plant start-up. Therefore, it is important to look at the interaction between the steam turbine and steam generator to determine the optimal ramp rates. This paper presents a methodology to account for thermal stresses limitations during the power plant start up, aiming at identifying which components limit the ramp rates. A detailed dynamic model of a parabolic trough power plant was developed and integrated with a control strategy to account for the start-up limitations of both the turbine and steam generator. The models have been introduced in an existing techno-economic tool developed by the authors (DYESOPT). The results indicated that for each application, an optimal heating rates range can be identified. For the specific case presented in the paper, an optimal range of 7-10 K/min of evaporator heating rate can result in a 1.7-2.1% increase in electricity production compared to a slower component (4 K/min).

  • 235.
    Ferruzza, Davide
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Thermocline storage for concentrated solar power: Techno-economic performance evaluation of a multi-layered single tank storage for Solar Tower Power Plant2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Solar Tower Power Plants with thermal energy storage are a promising technology for dispatchable renewable energy in the near future. Storage integration makes possible to shift the electricity production to more profitable peak hours. Usually two tanks are used to store cold and hot fluids, but this means both higher related investment costs and difficulties during the operation of the variable volume tanks. Another solution can be a single tank thermocline storage in a multi-layered configuration. In such tank both latent and sensible fillers are employed to decrease the related cost by up to 30% and maintain high efficiencies. 

    The Master thesis hereby presented describes the modelling and implementation of a thermocline-like multi-layered single tank storage in a STPP. The research work presents a comprehensive methodology to determine under which market structures such devices can outperform the more conventional two tank storage systems. As a first step the single tank is modelled by means of differential energy conservation equations. Secondly the tank geometrical design parameters and materials are taken accordingly with the applications taken into consideration. Both the steady state and dynamic models have been implemented in an existing techno-economic tool developed in KTH, in the CSP division (DYESOPT).

    The results show that under current cost estimates and technical limitations the multi-layered solid PCM storage concept is a better solution when peaking operating strategies are desired, as it is the case for the two-tier South African tariff scheme. In this case the IRR of an optimal designed power plant can be decreased by 2.1%. However, if a continuous operation is considered, the technology is not always preferred over the two tank solution, yet is a cheaper alternative with optimized power plants. As a result the obtained LCOE can be decreased by 2.4%.

  • 236.
    Ferruzza, Davide
    et al.
    Tech Univ Denmark, Dept Mech Engn, Nils Koppels Alle,Bldg 403, DK-2800 Lyngby, Denmark..
    Topel, Monika
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Haglind, Fredrik
    Tech Univ Denmark, Dept Mech Engn, Nils Koppels Alle,Bldg 403, DK-2800 Lyngby, Denmark..
    Optimal start-up operating strategies for gas-boosted parabolic trough solar power plants2018In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 176, p. 589-603Article in journal (Refereed)
    Abstract [en]

    Concentrating solar power plants are taking an increasing share in the renewable energy generation market. Parabolic trough is one of such technologies and the most commercially mature. However, this technology still suffers from technical challenges that need to be addressed. As these power plants experience daily start-up procedures, the optimal performance in transient operation needs to be considered. This paper presents a performance based modelling tool for a gas-boosted parabolic trough power plant. The objective of the paper is to define an optimal operational strategy of the power plant start-up procedure with the aim of minimizing its fuel consumption while at the same time maximizing its electric energy output, taking into account all the thermo-mechanical constraints involved in the procedure. Heating rate constraints of the steam generator and the booster heater, and the steam turbine start-up schedule were considered. The simulation model was developed based on a power plant located near Abu Dhabi, and was validated against real operational data with a maximum integral relative deviation of 4.3% for gross electric energy production. A multi-objective optimization was performed for a typical operating week during winter and spring weather conditions. The results suggest that in order to minimize the fuel consumption and at the same time maximize the electric energy production, an evaporator heating rate of 6 K/min is an optimal value both for winter and spring conditions.

  • 237. Fikari, Stamatia Gkiala
    et al.
    Ghaem Sigarchian, Sara
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Chamorro, Harold R.
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Modeling and Simulation of an Autonomous Hybrid Power System2017In: 2017 52nd International Universities Power Engineering Conference (UPEC), IEEE, 2017Conference paper (Refereed)
    Abstract [en]

    Renewable energy sources contribute to overcome the problem of environmental pollution and secure the energy independency every country needs, while at the same time the autonomous microgrids can improve the electrification rates of poorer countries. In this article, the modeling process and operation of an autonomous hybrid power system are studied for a hypothetical case study of electrification of a remote village of 100 inhabitants in Kenya. The microgrid consists of photovoltaics, wind turbine, batteries, diesel genset, basic loads of different priorities, water pumping and purification load. The system is modeled in Simulink MATLAB and is simulated in terms of power management. The primary load is categorized in different priorities, while water pumping and purification is used as deferrable load. The "load following" dispatch strategy is adopted. The outputs of the model are the power produced by the various sources and the power consumed by all loads during the simulation time, as well as the produced and consumed energy, information on the battery operation and the dumped power or the power shortage. Both the microgrid's operation and the performance of the dispatch strategy are evaluated considering the level on which the citizens' energy needs are covered and the efficient management of the produced energy. Managing the extra power or tackling the deficit of power in the system are the key issues to be addressed. After all, the model represents reliably the behavior of the microgrid and several improving actions are suggested, based on the results analysis.

  • 238.
    Firmansyah, Husni
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Power and Methanol Production from Biomass Combined With Solar and Wind Energy: Analysis and Comparison2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of this work is to investigate the feasibility of an integrated system consisting of biomass-based power generation built-in with carbon capture technology combined with a water electrolysis unit operated by solar cells and wind turbines to produce fuel through the methanol synthesis process. The configurations are examined both technically and economically to determine their feasibility, and subjected to sensitivity analysis to determine their economic viability and optimum performance. Each integrated system has the same subsystems configuration including electrical power generation, electrolysis unit and solar/wind renewable electricity input.

    Three main system configuration variations for carbon extraction from biomass feedstock have been evaluated, based on pre-CCS in the form of integrated biomass gasification combined cycle (IGCC), in-situ CCS represented by Oxy-fuel combustion concept, and post-CCS via exhaust gas treatment, assuming the same access to woodchip feedstock.Two important substances for methanol production are carbon dioxide coming from biomass and hydrogen supplied by water electrolysis based on intermittent renewable energy sources. Coil evaporation system to provide CO2 separation would perform differently in each system; oxy-fuel, pre-CCS and post-CCS alternatives. Meanwhile, H2 supply is provided by the electrolysis process using water supply and electricity produced from solar and wind power. In addition, the effect of location and uncertainty factors is discussed among the sensitivity studies.

    The technical analysis shows that with 5 ton/hour of biomass feed, each system configuration could produce up to 5.8 t/h of methanol. On the other hand, the economic analysis shows LCOE of Oxy-fuel and the IGCC approaches the lowest possible to 0.086 €/kWh and 0.1060 respectively; while for the gasification process 689 €/ton methanol is produced. The interest rate risk can deviate from the energy cost up to 16% higher when the interest rate is increased from 8% to 9%.

  • 239.
    Fogdal, Hanna
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Baars, Adrian
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Utilization of Forest Residue through Combined Heat and Power or Biorefinery for Applications in the Swedish Transportation Sector: a comparison in efficiency, emissions, economics and end usage2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Sweden has the goal of reaching a fossil independent transportation sector by 2030. Two ways to reach the goal is to increase the use of electric vehicles or produce more biofuels. Both alternatives could be powered by forest residue, which is an underutilized resource in the country. Electricity could be produced in a biomass fired Combined Heat and Power (CHP) plant, and biofuel could be produced in a biorefinery through gasification of biomass and Fischer-Tropsch process. When located in Stockholm County, both system can also distribute heat to the district heating system. It is however important to use the biomass in an energy-efficient way. The scope of this work has been to analyze the efficiency together with environmental and economic aspects of the two systems. 

    To assess the efficiency and environmental impact of the two systems a forest to wheel study was made of the systems where the product was studied from harvesting of forest residue to driving the vehicle. The studied functional units were: kilometers driven by vehicle, kWh of district heating, CO2-equivalents of greenhouse gases and MWh of forest residue. The system using CHP technology and electric vehicles outperformed the biorefinery system on the two first functional units. Using the same amount of forest residue more than twice as much district heating and almost twice as many driven kilometers were produced in this system. The study also showed that both systems avoids significant greenhouse gas emissions and can be part of the solution to decrease emissions from road transportation. 

    The profitability of investing in a CHP plant or a biorefinery was calculated through the net present value method. It showed that the expected energy prices are too low for the investments to be profitable. The CHP plant investment has a net present value of -1.6 billion SEK and the biorefinery investment has a net present value of -4.6 billion SEK. Furthermore, the biorefinery investment entails higher risk due to the high investment cost and uncommercialized technology. Both systems face barriers for implementation, these barriers have been studied qualitatively. 

  • 240.
    Fortkamp, Uwe
    et al.
    IVL Svenska Miljöinstitutet/IVL Swedish Environmental Research.
    Royen, Hugo
    IVL Svenska Miljöinstitutet/IVL Swedish Environmental Research.
    Klingspor, Magnus
    IVL Svenska Miljöinstitutet/IVL Swedish Environmental Research.
    Ekengren, Östen
    IVL Svenska Miljöinstitutet/IVL Swedish Environmental Research.
    Martin, Andrew
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Woldemariam, Daniel
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Membrane Distillation pilot tests for different wastewaters: Separation of pharmaceutical residues and treatment of flue gas condensate with Xzero Membrane Distillation in Pilot Scale at Hammarby Sjöstadsverk2015Report (Refereed)
    Abstract [en]

    The purpose of the project was to evaluate membrane distillation as an alternative separation technology for different water purification applications. Membrane distillation (MD) is a unit operation that uses water repellent (hydrophobic) membranes as a barrier for contaminated water. The driving force for the process is the vapor pressure over the membrane achieved by applying temperature differences between a warm and a cold side. The process takes place at temperatures below 100 °C and at ambient pressure. Pilot studies were performed at Hammarby Sjöstadsverk to test the separation of pharmaceutical residues from municipal wastewater after biological treatment as well as final treatment of flue gas condensate. In both cases, most target compounds were separated to a very high degree, often more than 90 %. The project also included energy studies that showed some potential for energy optimisation of the current equipment and provided input for energy efficient set-up, e.g. by using waste heat such as the return flow from district heating. Varying results for the single modules also indicated optimisation potential. The project was performed in cooperation between IVL Swedish Environmental Research Institute, Xzero AB as technology provider, and KTH (Royal institute of technology) for energy studies

  • 241.
    Fragoso, Joshua
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Setup of a laser system for structuring organic solar cells and ablation of the silver electrode2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 242.
    Fransson, Jimmy
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Market Role, Profitability, and Competitive Features of Combined Heat and Power Plants in the Swedish Future Electricity Market with High Renewable Integration2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 243.
    Fransson, Torsten
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Kazachkov, I.V.
    Popa, Marianne Salomon
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Konoval, O.V
    Collaboration of the Swedish-ukrainian universities in the development and implementation of the interactive multimedia teaching-learning system2011Other (Other academic)
  • 244. Freund, O.
    et al.
    Bartelt, M.
    Mittelbach, M.
    Montgomery, M.
    Vogt, Damian M.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Seume, J. R.
    Impact of the flow on an acoustic excitation system for aeroelastic studies2012In: Proceedings of the ASME Turbo Expo, 2012, no PARTS A AND B, p. 1609-1620Conference paper (Refereed)
    Abstract [en]

    The flow in turbomachines is highly unsteady. Effects like vortices, flow separation, and shocks are an inevitable part of the turbomachinery flow. Furthermore, high blade aspect ratios, aerodynamically highly loaded and thin profiles increase the blade sensitivity to vibrations. According to the importance of aeroelasticity in turbomachines, new strategies for experimental studies in rotating machines must be developed. A basic requirement for aeroelastic research in rotating machines is to be able to excite the rotor blades in a defined manner. Approaches for active blade excitation in running machines may be piezoelectric elements, magnetism, or acoustics. Contact-free excitation methods are preferred, since additional mistuning is brought into the investigated system otherwise. A very promising method for aeroelastic research is the non-contact acoustic excitation method. In this paper investigations on the influence of an annular cascade flow on the blade vibration, excited by an acoustic excitation system, are presented for the first time. These investigations are carried out at the Aeroelastic Test Rig (AETR) of the Royal Institute of Technology in Stockholm. By varying the excitation angle, the outlet Mach number, and the relative position of the excited blade to the excitation system, the influence of the flow on the acoustic excitation is quantified. The results show that there is a strong dependency of the excited vibration amplitude on the excitation angle if the outlet Mach number is increased, which implies that preferable excitation directions exist. Furthermore, it is shown that a benefit up to 23% in terms of excited vibration amplitude can be reached if the flow velocity is raised.

  • 245.
    Fridh, Jens
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Experimental Investigation of Performance, Flow Interactions and Rotor Forcing in Axial Partial Admission Turbines2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The thesis comprises a collection of four papers with preceding summary and supplementary appendices. The core investigation solely is of experimental nature although reference and comparisons with numerical models will be addressed. The first admission stage in an industrial steam turbine is referred to as the control stage if partial admission is applied. In order to achieve high part load efficiency and a high control stage output it is routinely applied in industrial steam turbines used in combined heat and power plants which frequently operate at part load. The inlet flow is individually throttled into separate annular arcs leading to the first stator row. Furthermore, partial admission is sometimes used in small-scale turbine stages to avoid short vanes/blades in order to reduce the impact from the tip leakage and endwall losses. There are three main aspects regarding partial admission turbines that need to be addressed. Firstly, there are specific aerodynamic losses: pumping-, emptying- and filling losses attributed to the partial admission stage. Secondly, if it is a multistage turbine, the downstream stages experience non-periodic flow around the periphery and circumferential pressure gradients and flow angle variations that produce additional mixing losses. Thirdly, the aeromechanical condition is different compared to full admission turbines and the forcing on downstream components is also circumferentially non-periodic with transient load changes. Although general explanations for partial admission losses exist in open literature, details and loss mechanisms have not been addressed in the same extent as for other sources of losses in full admission turbines. Generally applicable loss correlations are still lacking. High cycle fatigue due to unforeseen excitation frequencies or due to under estimated force magnitudes, or a combination of both causes control stage breakdowns. The main objectives of this thesis are to experimentally explore and determine performance and losses for a wide range of partial admission configurations. And, to perform a forced response analysis from experimental data for the axial test turbine presented herein in order to establish the forced response environment and identify particularities important for the design of control stages. Performance measurements concerning the efficiency trends and principal circumferential and axial pressure distortions demonstrate the applicability of the partial admission setup employed in the test turbine. Findings reveal that the reaction degree around the circumference varies considerably and large flow angle deviations downstream of the first rotor are present, not only in conjunction to the sector ends but stretching far into the admission sector. Furthermore, it is found that the flow capacity coefficient increases with reduced admission degree and the filling process locally generates large rotor incidence variation associated with high loss. Moreover, the off design conditions and efficiency deficit of downstream stages are evaluated and shown to be important when considering the overall turbine efficiency. By going from one to two arcs at 52.4% admission nearly a 10% reduction in the second stage partial admission loss, at design operating point was deduced from measurements. Ensemble averaged results from rotating unsteady pressure measurements indicate roughly a doubling of the normalized relative dynamic pressure at rotor emptying compared to an undisturbed part of the admission jet for 76.2% admission. Forced response analysis reveals that a large number of low engine order force impulses are added or highly amplified due to partial admission because of the blockage, pumping, loading and unloading processes. For the test turbine investigated herein it is entirely a combination of number of rotor blades and low engine order excitations that cause forced response vibrations. One possible design approach in order to change the force spectrum is to alter the relationship between admitted and non-admitted arc lengths.

  • 246.
    Fridh, Jens
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Bunkute, Birute
    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.
    Fransson, Torsten H.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    An experimental study on partial admission in a two-stage axial air test turbine with numerical comparisons2004In: Proceedings of the ASME Turbo Expo 2004, Vienna, 2004, Vol. 5 B, p. 1285-1297Conference paper (Refereed)
    Abstract [en]

    This paper presents ongoing experimental aerodynamic and efficiency measurements on a cold flow two-stage axial air test turbine with low reaction steam turbine blades at different degrees of partial admission. The overall objectives of the work are to experimentally investigate and quantify the steady and unsteady aerodynamic losses induced by partial admission. The first results show that both the total-to-static turbine efficiency drops and that the efficiency peak appears at lower isentropic velocity ratios with lower degrees of admission. Detailed steady traverse measurements of the static wall pressures downstream of sector-ends show strong local variations. The pressure wake from the partial admission blockage moves almost axially through the turbine while the temperature wake is located in a tangential position that represents the position of a particle trace based on velocity triangles, in the direction of the rotor rotation. Comparisons with 2D compressible flow computations around the circumference demonstrate the importance of the radial flow component in these experiments.

  • 247.
    Fridh, Jens
    et al.
    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.
    Andersson, Nils-Erik
    Siemens Industrial Turbomachinery AB.
    Magnusson, Peter
    Siemens Industrial Turbomachinery AB.
    REDUNDANT ROTATING MEASUREMENTS IN AN AXIAL COLD FLOW TEST TURBINE: Development and Procedure2006Conference paper (Other academic)
    Abstract [en]

    A rotating measurement system has been designed and commissioned for a cold flow test turbine and tested under the influence of partial admission. A shrouded turbine rotor of impulse design is equipped with miniature pressure transducers and strain gauges. This paper discusses the selected experimental design and procedure. Overall, the first test runs went well and necessary data were collected and could be evaluated accordingly. Encountered specific measurement technique problems are addressed where the importance of high redundancy is stressed. Results demonstrate one effect that imbedded sensor technology may encounter as regards of dynamic measurements and calibrations.

  • 248.
    Fridh, Jens
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    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.
    Forced Response in axial turbines under the influence of partial admission2012In: ASME Turbo Expo 2012 - Turbine Technical Conference and Exposition, Copenhagen, June 11-15, 2012: Volume 7, Issue PARTS A AND B, 2012, ASME Press, 2012, p. 1419-1429Conference paper (Refereed)
    Abstract [en]

    High cycle fatigue (HCF) due to unforeseen excitation frequencies or due to under predicted force magnitudes, or a combination of both causes control stage failures for steam turbine stakeholders. The objectives of this paper is to provide an extended design criteria toolbox and validation data for control stage design based on experimental data, with the aim to decrease HCF incidents for partial admission turbines. The upstream rotor in a two stage air test turbine is instrumented with pressure transducers and strain gauges. Admission degrees stretching from 28.6% to 100% as one or two admission arcs are simulated by blocking segmental arcs immediately upstream of first stator vanes by aerodynamically shaped filling blocks. Sweeps across a speed range from 50 to 105% of design speed are performed at constant turbine pressure ratio during simultaneous high speed acquisition. A forced response analysis is performed and results presented in Campbell diagrams. Partial admission creates a large number of low engine order forced responses because of the blockage, pumping, loading and unloading processes. Combinations of the number of rotor blades and low engine order excitations are the principal sources of forced response vibrations for the turbine studied herein. Altering the stator and/or rotor pitches will change the excitation pattern. A relation between the circumferential lengths of the admitted and non-admitted arcs that dictates the excitation forces is observed that may serve as a design parameter.

  • 249.
    Fridh, Jens
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    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.
    Forced Response in Axial Turbines Under the Influence of Partial Admission2013In: Journal of turbomachinery, ISSN 0889-504X, E-ISSN 1528-8900, Vol. 135, no 4, p. 041014-Article in journal (Refereed)
    Abstract [en]

    High cycle fatigue (HCF) due to unforeseen excitation frequencies, underestimated force magnitudes, or a combination of both causes control-stage failures for steam turbine stakeholders. This paper provides an extended design criteria toolbox, as well as validation data, for control-stage design based on experimental data to reduce HCF incidents in partial-admission turbines. The upstream rotor in a two-stage air test turbine is instrumented with pressure transducers and strain gauges. Admission degrees extend from 28.6% to 100%, as one or two admission arcs are simulated by blocking segmental arcs immediately upstream of the first stator vanes with aerodynamically shaped filling blocks. Sweeps across a speed range of 50%-105% of design speed are performed at a constant turbine pressure ratio during simultaneous high-speed acquisition. A forced-response analysis is performed and results presented in Campbell diagrams. Partial admission creates a large number of low-engine-order forced responses because of the blockage, pumping, loading, and unloading processes. Combinations of the number of rotor blades and low-engine-order excitations are the principal sources of forced-response vibrations for the turbine studied here. Altering the stator and/or rotor pitches changes the excitation pattern. We observed that a relationship between the circumferential lengths of the admitted and nonadmitted arcs dictates the excitation forces and may serve as a design parameter.

  • 250.
    Fridh, Jens
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Wikström, Rolf
    Siemens Industrial Turbomachinery AB.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    DYNAMIC FEATURES OF PARTIAL ADMISSION: OUTCOMES FROM ROTATING MEASUREMENTS2007In: Euroturbo 7: Proceedings of the 7th European Conference on Turbomachinery, Fluid Dynamics and Thermodynamics, Athens: Local Conference Organising Committee , 2007, p. 451-462Conference paper (Refereed)
    Abstract [en]

    A system for rotating measurements has been designed and commissioned for a two-stage axial turbine of impulse design. Relative total pressure and strain gauge measurements in the rotating frame of reference have been performed during partial admission tests in this turbine. The overall project objectives are to determine unsteady aerodynamic losses related to admission sector-ends and rotor forcing functions. Some outcomes are presented and discussed herein. The unsteadiness in the measured relative total pressure is observed to be largest downstream of the suction side of the partial admission blockage where the high momentum fluid vividly interacts with the rotor. Strain gauge results show a high strain peak downstream of the suction side of the blockage. When reducing the shaft speed at constant pressure ratio, the dip in relative total pressure and the peak in tensile strain, that occur when a blade enters the blocked region, are shifted in the counter rotational direction. This is believed to reflect earlier emptying of the rotor blade channel. Furthermore, an increase of the flow capacity coefficient with a decrease of admission degree has been observed.

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