Change search
Refine search result
891011121314 501 - 550 of 952
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 501. Lu, Yuzheng
    et al.
    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. Hubei Univ, Peoples R China.
    Wang, Baoyuan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. Hubei Univ, Peoples R China.
    Wang, Jun
    Xia, Chen
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Nanotechnology Based Green Energy Conversion Devices with Multifunctional Materials at Low Temperatures2017In: RECENT PATENTS ON NANOTECHNOLOGY, ISSN 1872-2105, Vol. 11, no 2, p. 85-92Article, review/survey (Refereed)
    Abstract [en]

    Background: Nanocomposites (integrating the nano and composite technologies) for advanced fuel cells (NANOCOFC) demonstrate the great potential to reduce the operational temperature of solid oxide fuel cell (SOFC) significantly in the low temperature (LT) range 300-600 degrees C. NANOCOFC has offered the development of multi-functional materials composed of semiconductor and ionic materials to meet the requirements of low temperature solid oxide fuel cell (LTSOFC) and green energy conversion devices with their unique mechanisms. Description: This work reviews the recent developments relevant to the devices and the patents in LTSOFCs from nanotechnology perspectives that reports advances including fabrication methods, material compositions, characterization techniques and cell performances. Conclusion: Finally, the future scope of LTSOFC with nanotechnology and the practical applications are also discussed.

  • 502. Lu, Yuzheng
    et al.
    Zhu, Binzhu
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Hubei Univ, Peoples R China.
    Cai, Yixiao
    Kim, Jung-Sik
    Wang, Baoyuan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. Hubei Univ, Peoples R China.
    Wang, Jun
    Zhang, Yaoming
    Li, Junjiao
    Progress in Electrolyte-Free Fuel Cells2016In: FRONTIERS IN ENERGY RESEARCH, ISSN 2296-598X, Vol. 4, article id UNSP 17Article, review/survey (Refereed)
    Abstract [en]

    Solid oxide fuel cell (SOFC) represents a clean electrochemical energy conversion technology with characteristics of high conversion efficiency and low emissions. It is one of the most important new energy technologies in the future. However, the manufacture of SOFCs based on the structure of anode/electrolyte/cathode is complicated and time-consuming. Thus, the cost for the entire fabrication and technology is too high to be affordable, and challenges still hinder commercialization. Recently, a novel type of electrolyte-free fuel cell (EFFC) with single component was invented, which could be the potential candidate for the next generation of advanced fuel cells. This paper briefly introduces the EFFC, working principle, performance, and advantages with updated research progress. A number of key R&D issues about EFFCs have been addressed, and future opportunities and challenges are discussed.

  • 503.
    Lucio, Monaco
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Bergmans, John
    Vogt, Damian
    Fransson, Torsten H.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    A Remotely Operated Aeroelastically Unstable Low Pressure Turbine Cascade for Turbomachinery Aeromechanics Education and Training-Remote Flutter Lab2015In: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 137, no 3, article id 032507Article in journal (Refereed)
    Abstract [en]

    The use of advanced pedagogical methodologies in connection with advanced use of modern information technology for delivery enables new ways of communicating, of exchanging knowledge, and of learning that are gaining increasing relevance in our society. Remote laboratory exercises offer the possibility to enhance learning for students in different technical areas, especially to the ones not having physical access to laboratory facilities and thus spreading knowledge in a world-wide perspective. A new "Remote Flutter Laboratory" has been developed to introduce aeromechanics engineering students and professionals to aeroelastic phenomena in turbomachinery. The laboratory is world-wide unique in the sense that it allows global access for learners anywhere and anytime to a facility dedicated to what is both a complex and relevant area for gas turbine design and operation. The core of the system consists of an aeroelastically unstable turbine blade row that exhibits self-excited and self-sustained flutter at specific operating conditions. Steady and unsteady blade loading and motion data are simultaneously acquired on five neighboring suspended blades and the whole system allows for a distant-based operation and monitoring of the rig as well as for automatic data retrieval. This paper focuses on the development of the Remote Flutter Laboratory exercise as a hands-on learning platform for online and distant-based education and training in turbomachinery aeromechanics enabling familiarization with the concept of critical reduced frequency and of flutter phenomena. This laboratory setup can easily be used "as is" directly by any turbomachinery teacher in the world, free of charge and independent upon time and location with the intended learning outcomes as specified in the lab, but it can also very easily be adapted to other intended learning outcomes that a teacher might want to highlight in a specific course. As such it is also a base for a turbomachinery repository of advanced remote laboratories of global uniqueness and access. The present work documents also the pioneer implementation of the LabSocket System for the remote operation of a wind tunnel test facility from any Internet-enabled computer, tablet or smartphone with no end-user software or plug-in installation.

  • 504. Lucisano, M. F. C.
    et al.
    Martin, Andrew R.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Visualization of liquid-vapor phase change phenomena in impulse technology2006In: TAPPI Journal, ISSN 0734-1415, Vol. 5, no 6, p. 15-21Article in journal (Refereed)
    Abstract [en]

    This paper addresses two unresolved aspects in the physics of impulse technology. In our initial study, we used a modified laboratory platen press to investigate contact phenomena at the interface between the wet web and the hot press. We replaced the heated press platen with a preheated glass plate and used high-speed photography to visualize the interfacial interactions. The results confirm that little or no steam is formed before the point of maximum applied load for contact times typical of industrial pressing operations (25 ms). Steam generation during the nip compression phase could be observed only for pulse lengths well beyond-those encountered in industrially relevant impulse press nips (250 ms). In a complementary study, flashing phenomena were investigated in STFI's FlashLab, an experimental facility for the study of phase-change phenomena in water-saturated porous media. Model experiments under well-defined conditions showed that delamination can be prevented by an appropriate unloading strategy. Moreover, we observed that flashing-assisted displacement dewatering occurred when the hydraulic pressure was released. We discuss its significance for impulse pressing efficiency in this report. Application: Insights from this study will help in the further development and possible commercialization of impulse drying systems.

  • 505.
    Ma, Ying
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Wang, Xiaodi
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Khalifa, Hassan Ahmed
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Enhanced ionic conductivity in calcium doped ceria - Carbonate electrolyte: A composite2012In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 37, no 24, p. 19401-19406Article in journal (Refereed)
    Abstract [en]

    Recently, ceria-based nanocomposites, as a proton and oxygen ion conductor, has been developed as promising electrolyte candidates for low-temperature solid oxide fuel cells (LTSOFCs). Up to now, samarium doped ceria (SDC) was studied as a main oxide for nanocomposite electrolyte; while calcium doped ceria (CDC) is considered as a good alternative from both material performance and economical aspects. Yet the conduction behavior of CDC-based composite has not been reported. In the present study, calcium doped ceria was prepared by oxalate co-precipitation method, and used for the fabrication of CDC/Na2CO3 composite. The thermal decomposition process, structure and morphology of the samples were characterized by TGA, XRD, SEM, etc. The oxygen ion conductivity of single phase CDC sample was measured by electrochemical impedance spectroscopy (EIS), while the proton and oxygen ion conductivity of CDC/Na2CO3 nanocomposite sample were determined by four-probe d.c. measurements. The CDC/Na2CO3 samples show significantly enhanced overall ionic conductivity compared to that of single phase CDC samples, demonstrating pronounced composite effect. This confirms that the use of nanocomposite as electrolyte can effectively lower the operation temperature of SOFC due to improved ionic conductivity.

  • 506.
    Ma, Ying
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Wang, Xiaodi
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Microwave synthesis of mesoporous Cu-Ce0.8Sm0.2O 2-δ composite anode for low-temperature ceramic fuel cells2013In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 38, no 1, p. 597-602Article in journal (Refereed)
    Abstract [en]

    In recent year, new nanocomposite electrolytes materials have been developed for low-temperature ceramic fuel cells (CFCs). To further improve the performance of CFCs based on the nanocomposite electrolyte, compatible active anode with sufficient low polarizations is needed. To improve the performance of anode, i.e. to enlarge tripe phase boundaries (TPB), anode materials with both porous structure and phase homogeneity of metal and ceramic are preferred. In the present study, we developed a novel microwave-assisted template-, surfactant-free synthesis route for mesoporous CuO-Ce0.8Sm 0.2O2-δ composite anode by homogeneous precipitation of microspherical precursor in aqueous solutions followed by calcination. The composite anode sample was characterized by thermogravimetry analysis, X-ray diffraction, SEM, EDX, etc. The characterization results indicated that CuO-SDC composite anode with mesoporous structure was prepared and both SDC and CuO phases were homogenously distributed. Fuel cells have been constructed using as-prepared composite as anodes and lithiated NiO as cathode based on the SDC-carbonate nanocomposite electrolyte. Fuel cell performance tests indicated that the cell with mesoporous Cu-SDC anode had better performance than conventional Cu-SDC anode prepared by solid-state method.

  • 507.
    Ma, Ying
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Wang, Xiaodi
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Microwave synthesis of mesoporous CuO-Ce0.8Sm0.2O2-δ composite anode for low-temperature SOFCsArticle in journal (Other academic)
  • 508.
    MABILLE DE LA PAUMELIERE, Louis-Vianney
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Functional and thermomechanical analysis of heat exchanger structure2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    To keep the combustion chamber of a rocket engine in a good mechanical state, the chamber is cooled by hydrogen flowing through channels alongside the chamber wall. Those channels are drilled into the chamber wall and then closed. Nevertheless, the process used to manufacture the cooling channels is long, difficult, and expensive.

     

    This document analyses the feasibility of a new concept of combustion chamber whose channels are not closed by the usual process. The main issue concerns the behavior of the hot gas wall under the loading of the channel internal pressure and the hot gas thermal dilatation that counteract on the evolution of chamber radius and so on the radial gap between channels fins and structural external liner.

    A logic has been built in order to analyze the coupling between hot gas wall behavior and hydrogen cooling efficiency, in different configuration (engine size, pressure level,…) and taking into account scattering of manufacturing processes.

     

    In that way, the document contains a functional and thermomechanical analysis dealing with the effect of such a combustion chamber for different wall cases. The functional analysis was carried out with ANSYS FLUENT, a CFD solver. As for the thermomechanical analysis, it was carried out with ANSYS Workbench / SAMCEF FEM solver taking into account both the thermal and the mechanical effects. This document compares the heat flux in the case of a classical combustion chamber and a new combustion chamber (heat flux extracted, maximal wall temperature) and presents the mechanical consequences implied by this new type of chamber (pressure effects, thermal effects, strains, stresses).

    This document also suggests a method predicting the behavior of such a chamber with different chamber radius, different kind of material, different pressure difference between the channels and the chamber. This method eases the conception of this new type of rocket engine.

    Eventually, this document deals with non symmetrical problems due to manufacturing.

  • 509.
    Madaan, Sushant
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Comprehensive Study of Single component electrolyte-free fuel cell: Joint solar cell and fuel cell mechanism2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 510.
    Mainali, Brijesh
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    Hassan, Ahmed
    Khan, Ershad
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Silveira, Semida
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    Martin, Andrew
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Addressing the rural energy and drinking water needs by using Biogas in rural Bangladesh2012Conference paper (Other academic)
  • 511.
    Malakhatka, Elena
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Diagnostics of valves on the gas pipeline2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The work of the gas transmission pipeline system is regulated by the thousands of valveses and other elements of the shut-off valves, located in different places. Information about the current status of each valve, and confidence in its technical serviceability is an important element in the control of pipeline system. There are a number of problems that adversely affect the  valving operation. Principal among them - is the lack of siystematical approach in valving diagnostics.

    To solve this problem, developed a new approach to the valving diagnostics – multi-level diagnostics. Depending on the level of diagnosis, we get a different amount of information about the object.

     

    The focus is on the 3rd level of diagnosis, which allows to determine the leackages of valves, and identify type of defects quantitatively. This level of diagnosis is regarded as an example of Method «Micropuls».

    The method «Micropuls» based on the theory of mechanical vibrations and forced with high accuracy to set the time, frequency and spectral characteristics of noise in the details of the valve, and their spatial location and intensity of that in the presence of a system of analysis allows to determine the state of the object, its faults and defects.

    Micropulse technology is based on the impact on the measured object micropower impulses, records the response and subsequent filtering, decoding and analyzing the data.                    Specially designed calibrated pulses can effectively influence the measured objects (valve) over a wide range of structural dimensions and mounting schemes, regardless of physical location of the valve.

     

  • 512.
    Mamaev, Boris
    et al.
    Siemens LLC Energy Oil & Gas Design Department, Russia.
    Saha, Ranjan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fridh, Jens
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Aerodynamic investigation of turbine cooled vane block2015In: Thermal Engineering, ISSN 0040-6015, Vol. 62, no 2, p. 97-102Article in journal (Refereed)
    Abstract [en]

    The vane block (VB) has been investigated and it gives several important results related to test methods and calculation procedures. The vane block is characterized by a developed film and convective cooling system. Blowing tests demonstrate that there is a weak correlation between cooling type and energy loss. Superposition of these effects is true for the central part over VB height without secondary flows. Coolant discharge increases profile loss and it rises if coolant flow rate is increased. Discharge onto profile convex side through the trailing edge slot influences the most considerably. The discharge through perforation decreases the vane flow capacity and insufficiently influences onto the flow outlet angle, but the trailing edge discharge increases this angle according to loss and mixture flow rate growth. The secondary flows reduce the effect of coolant discharge, which insufficiently changes losses distribution at turbine blades tips and even decreases the secondary losses. The flow outlet angle rises significantly and we are able to calculate it only if we correct the ordinary flow model. In the area of secondary flows, the outlet angle varies insufficiently under any type of cooling. This area should be investigated additionally.

  • 513. Mamaev, Boris
    et al.
    Saha, Ranjan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fridh, Jens
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    The influence of a special fillet between the endwall and airfoil at the leading edge on the performance of the turbine nozzle diaphragm2013In: Thermal Engineering, ISSN 0040-6015, Vol. 60, no 3, p. 217-222Article in journal (Refereed)
    Abstract [en]

    It is shown from the results of experimental investigations carried out on a nozzle diaphragm’s sector that an enlarged fillet at the vane leading edge does not have an essential effect on the flow and energy losses in the nozzle diaphragm

  • 514.
    MAMOTTE, DANIEL GERALD
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Assessment of the Specific Fuel Consumption of a Cogeneration Power Plant2012Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
  • 515.
    Mancini, Roberta
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Volumetric Solar Receiver for a Parabolic Dish and Micro-Gas Turbine system: Design, modelling and validation using Multi-Objective Optimization2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Concentrated Solar Power (CSP) constitutes one suitable solution for exploiting solar resources for power generation. In this context, parabolic dish systems concentrate the solar radiation onto a point focusing receiver for small-scale power production. Given the modularity feature of such system, the scale-up is a feasible option; however, they offer a suitable solution for small scale off-grid electrification of rural areas. These systems are usually used with Stirling engines, nevertheless the coupling with micro-gas turbines presents a number of advantages, related to the reliability of the system and the lower level of maintenance required. The OMSoP project, funded by the European Union, aims at the demonstration of a parabolic dish coupled with an air-driven Brayton cycle. By looking at the integrated system, a key-role is played by the solar receiver, whose function is the absorption of the concentrated solar radiation and its transfer to the heat transfer fluid. Volumetric solar receivers constitute a novel and promising solution for such applications; the use of a porous matrix for the solar radiation absorption allows reaching higher temperature within a compact volume, while reducing the heat transfer losses between the fluid and the absorption medium. The aim of the present work is to deliver a set of optimal design specifications for a volumetric solar receiver for the OMSoP project. The work is based on a Multi-Objective Optimization algorithm, with the objective of the enhancement of the receiver thermal efficiency and of the reduction of the pressure drop. The optimization routine is coupled with a detailed analysis of the component, based on a Computational Fluid Dynamics model and a Mechanical Stress Analysis. The boundary conditions are given by the OMSoP project, in terms of dish specifications and power cycle, whilst the solar radiation boundary is modelled by means of a Ray Tracing routine. The outcome of the analysis is the assessment of the impact on the receiver performance of some key design parameters, namely the porous material properties and the receiver geometrical dimensions. From the results, it is observed a general low pressure drop related to the nominal air mass flow, with several points respecting the materials limitations. One design point is chosen among the optimal points, which respects the OMSoP project requirements for the design objectives, i.e. a minimum value of efficiency of 70%, and pressure losses below 1%. The final receiver configuration performs with an efficiency value of 86%, with relative pressure drop of 0.5%, and it is based on a ceramic foam absorber made of silicon carbide, with porosity value of 0.94.  Moreover, the detailed analysis of one volumetric receiver configuration to be integrated in the OMSoP project shows promising results for experimental testing and for its actual integration in the system. 

  • 516. Manna, A. K.
    et al.
    Sen, M.
    Martin, Andrew R.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Pal, P.
    Removal of arsenic from contaminated groundwater by solar-driven membrane distillation2010In: Environmental Pollution, ISSN 0269-7491, E-ISSN 1873-6424, Vol. 158, no 3, p. 805-811Article in journal (Refereed)
    Abstract [en]

    Experimental investigations were carried out on removal of arsenic from contaminated groundwater by employing a new flat-sheet cross flow membrane module fitted with a hydrophobic polyvinylidenefluoride (PVDF) microfiltration membrane The new design of the solar-driven membrane module in direct contact membrane distillation (DCMD) configuration successfully produced almost 100 per cent arsenic-free water from contaminated groundwater in a largely fouling-free operation while permitting high fluxes under reduced temperature polarization For a feed flow rate of 0120 m(3)/h, the 013 mu m PVDF membrane yielded a high flux of 74 kg/(m(2) h) at a feed water temperature of 40 degrees C and, 95 kg/m(2) h at a feed water temperature of 60 degrees C. The encouraging results show that the design could be effectively exploited in the vast arsenic-affected rural areas of South-East Asian countries blessed with abundant sunlight particularly during the critical dry season.

  • 517.
    Manrique Carrera, Arturo
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Catalytic Combustion in Gas Turbines: Experimental Study on Gasified Biomass Utilization2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Environmental and geopolitical concerns encourage societies towards the utilization of renewable energy sources (RES). Photovoltaic and wind power can produce electricity directly, although their intermittent characteristic negatively affects the security and safety of the energy supply chain; moreover, in order to be viable it is necessary to establish energy storage systems and to find mechanisms to adapt the power distribution grid to larger production variability. In contrast, biomass (a carbon neutral fuel if adequately managed) can be stored, is relatively widely available, and after simple treatments can be gasified and ready to be used for power production. Correspondingly, gas turbines are a well-established technology that first became relevant in industrial applications and power production since 1940’s. The use of biomass in gas turbines is an important step forward towards more sustainable power production; however, this combination presents some technical challenges that have yet to be overcome.

    Gasified biomass is generally a gas with low or medium heating value that is usually composed of a mixture of gases such as CO, H2, CH4, CO2, and N2 as well as other c60*6nents in small fractions. Its firing in standard gas turbine combustors might be unstable at certain load conditions. Moreover, gasified biomass contains undesirable compounds; in particular the nitrogen-containing compounds that may produce elevated NOx emissions once the biomass is burned.

    Catalytic combustion is an alternative for using gasified biomass in a gas turbine, and it is investigated in this study. Using catalytic combustion is possible to burn such a mixture of gases under very lean conditions, extending the normal flammability limits, reducing the maximum temperature of the reaction zone, and thus reducing the thermal NOx formation. It also reduces the vibration levels, and it is possible to avoid fuel-NOx formation using alternative catalytic techniques, such as Selective Catalytic Oxidation (SCO).

    In the present study the feasibility of using catalytic combustion in a gas turbine combustor is evaluated. The tests performed indicate the necessity of using hybrid combustion chamber concepts to achieve turbine inlet temperatures levels of modern gas turbines. The different catalytic burning characteristic of H2, CO and CH4 was evaluated and different techniques were applied to equalize their burning behaviour such as the diffusion barrier, and partially coated catalyst. Fuel-NOx is another subject treated in this work, where a Selective Catalytic Oxidation (SCO) technique is applied reaching up to 42% of fuel NOx reduction. Finally, the use of Catalytic Partial Oxidation (CPO) of methane was experimentally investigated.

    In this study, two one-of-a-kind test facilities were used directly, namely the high-pressure test facility and the pilot scale test facility. This gives a unique characteristic to the study performed. Finally, the catalytic combustion approach allows the utilization of gasified biomass with some restrictions depending on whether it is a Catalytic Lean, Catalytic Rich or Catalytic Partial Oxidation (CPO) approach.

  • 518.
    Manrique Carrera, Arturo
    et al.
    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
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Catalytic Combustion of Gasified Biomass for Gas Turbine Applications: Experimental Study for Reducing Fuel NOx Formation2005In: 14th European Biomass Conference & Exhibition, 2005, Vol. 100Conference paper (Refereed)
  • 519.
    Manrique Carrera, Arturo
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Jayasuriya, Jeevan
    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
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Persson, Katarina
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Catalytic Combustion of Gasified Biomass for Gas Turbine Applications: Experimental Investigation at High Pressure2005In: Proceedings of the 6th International Workshop on Catalytic Combution, 2005, Vol. 100, p. 9-14Conference paper (Refereed)
  • 520. Manyumbu, E.
    et al.
    Martin, V
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Fransson, Torsten H.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Simple mathematical modeling and simulation to estimate solar-regeneration of a silica gel bed in a naturally ventilated vertical channel for Harare, Zimbabwe2014In: Energy Procedia, 2014, p. 1733-1742Conference paper (Refereed)
    Abstract [en]

    Passive air conditioning (humidity and temperature control) in buildings is more desirable on sustainable basis. One of the challenges of passive humidity control is regeneration of the materials applied for the purpose. This paper looks at solar regeneration of a silica gel layer (bed) for typical seasons of the year in Harare, Zimbabwe. This bed forms the primary system that is then used for drying room internal surfaces during the night. The extent of silica gel solar drying is the main attention of this investigation. Solar regeneration of a silica gel bed that forms a solar 'absorber' surface of a rectangular solar channel is investigated. Simple mathematical models are developed and subsequent spreadsheet simulations are carried out. Silica gel sorption models are from literature or estimated through curvefitting of available data. Solar radiation falling on a vertical surface at a given orientation is evaluated from the global solar radiation data using a developed simulator based on correlations obtained from literature and measured solar radiation data from the local meteorological department. For a vertical solar channel of an air gap of 20mm, and a height of 3m, silica gel is regenerated to some quite low moisture content of circa 0.06kg/kg. Comparable degree of regeneration is achieved for both seasons.

  • 521.
    Martin, Andrew
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Jonsson, Hans
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Martinac, Ivo
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Sustainable Building Systems.
    Sustainable Energy Engineering:  An International Master Degree Program2002In: Proc. Engineering in Sustainable Development Conference, October 24th/25th 2002, Delft, The Netherlands, 2002, p. Paper no. 143-Conference paper (Refereed)
  • 522.
    Martin, Andrew R.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Lucisano, M. F. C.
    Characterizing liquid-vapor phase change phenomena in impulse technology with resistivity probes2006In: TAPPI Journal, ISSN 0734-1415, Vol. 5, no 5, p. 22-26Article in journal (Refereed)
    Abstract [en]

    This study used resistivity probes for the dynamic detection of liquid-vapor phase change inside wet paper webs undergoing impulse pressing. The probes were made from thin copper wires insulated with a high-temperature polymeric material (overall diameter-of 50 mu m). The gap between the exposed ends served as the probe tip. The validity of this technique in impulse pressing experiments was demonstrated in two ways: (1) tests with both dry and wet sheets showed that the probe response was unaffected by the fiber network itself; and (2) heated trials with low applied pressure and long residence times (> 1 s) clearly showed the propagation of a vapor front through the sheet, as predicted by theory. Impulse pressing, experiments were subsequently conducted with a platen press under realistic operating conditions (i.e. surface tempera tures up to 300 degrees C, nip residence times of approximately 25 ms, and maximum applied pressure around 4 MPa). Results show that steam was detected inside the sheet only upon unloading of the hot nip for the layers closest to the heated surface.

  • 523.
    Martin, Viktoria
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    He, Bo
    Setterwall, Fredrik
    Direct contact PCM-water cold storage2010In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 87, no 8, p. 2652-2659Article in journal (Refereed)
    Abstract [en]

    Comfort cooling demand continues to increase throughout the world Conventional cooling production results in high demand for electrical power during peak hours, leading to high emissions for producing cooling, and potential power shortages in electric grids With a cold storage, the peak power demand is effectively managed and enables free-cooling. This paper examines one concept using phase change materials (PCM) for storing of cold, where the cold carrier (water) is in direct contact with the PCM. This is in order to enable high power for charging and discharging while providing a high storage capacity. A theoretical model highlights important design parameters for reaching large storage and power capacity The capacity increases with the Packing Factor and temperature difference across the storage. For high power, the flow rate, temperature difference, and drop size is important parameters which is also verified in an experimental evaluation. The obtainable power is between 30 and 80 kW/m(3) storage Practical limitations of this concept are shown to be PCM-water bed expansion and non-uniform channeling due to asymmetric and unstable PCM shells.

  • 524.
    Marty, Pierre-Francois
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Design of a hybrid power PV – Genset – Battery storage system for a remote off-grid application in Malaysia2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The thesis project presented in this report focuses on an analysis of the electrification prospects for a remote village in the Malaysian state of Sabah, where a micro grid is planned to be built. The main goal is to define the best sizing for a hybrid power plant to serve the micro grid, coupling a solar PV array with a storage system and a diesel genset.

    The first step of the study case consists of defining the energy needs of the village in order to draw its consumption curve and assume its evolution over time. Then a model of the hybrid power plant was built in Matlab and Simulink. It simulates the behavior of the power plant components – mainly the solar power plant, the storage system, the genset and the energy management system – and the interactions between these elements.

    The model is then used in order to run simulations according to four scenarios corresponding to four different power plant configurations: genset standalone power plant, genset & solar power plant, genset & solar & storage automatically operated, and genset & solar & storage manually operated. For each one of these scenarios, simulations were run and the optimal sizing and settings were defined according to different criteria related mainly to the fuel consumption, the genset penetration and the cost of electricity.

    The different scenarios and consequently the related hybrid plant configurations were compared according to the abovementioned criteria and an optimal design was selected, allowing the best trade-off between the cost of electricity and the genset penetration. This solution should guarantee a reliable and affordable access to electricity for this village over the assumed lifetime of ten years. 

  • 525.
    Mata Yandiola, Cristina
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Feasibility Analysis of the Use of Hybrid Solar PV-Wind Power Systems for Grid Integrated Mini-grids in India2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 526.
    Mayorca, Maria Angelica
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Numerical Methods for Turbomachinery Aeromechanical Predictions2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In both aviation and power generation, gas turbines are used as key components. An important driver of technological advance in gas turbines is the race towards environmentally friendly machines, decreasing the fuel burn, community noise and NOx emissions. Engine modifications that lead to propulsion efficiency improvements whilst maintaining minimum weight have led to having fewer stages and lower blade counts, reduced distance between blade rows, thinner and lighter components, highly three dimensional blade designs and the introduction of integrally bladed disks (blisks). These changes result in increasing challenges concerning the structural integrity of the engine. In particular for blisks, the absence of friction at the blade to disk connections decreases dramatically the damping sources, resulting in designs that rely mainly on aerodynamic damping. On the other hand, new open rotor concepts result in low blade-to-air mass ratios, increasing the influence of the surrounding flow on the vibration response.

     

    This work presents the development and validation of a numerical tool for aeromechanical analysis of turbomachinery (AROMA - Aeroelastic Reduced Order Modeling Analyses), here applied to an industrial transonic compressor blisk. The tool is based on the integration of results from external Computational Fluid Dynamics (CFD) and Finite Element (FE) solvers with mistuning considerations, having as final outputs the stability curve (flutter analysis) and the fatigue risk (forced response analysis). The first part of the study aims at tracking different uncertainties along the numerical aeromechanical prediction chain. The amplitude predictions at two inlet guide vane setups are compared with experimental tip timing data. The analysis considers aerodynamic damping and forcing from 3D unsteady Navier Stokes solvers. Furthermore, in-vacuo mistuning analyses using Reduced Order Modeling (ROM) are performed in order to determine the maximum amplitude magnification expected. Results show that the largest uncertainties are from the unsteady aerodynamics predictions, in which the aerodynamic damping and forcing estimations are most critical. On the other hand, the structural dynamic models seem to capture well the vibration response and mistuning effects.

     

    The second part of the study proposes a new method for aerodynamically coupled analysis: the Multimode Least Square (MLS) method. It is based on the generation of distributed aerodynamic matrices that can represent the aeroelastic behavior of different mode-families. The matrices are produced from blade motion unsteady forces at different mode-shapes fitted in terms of least square approximations. In this sense, tuned or mistuned interacting mode families can be represented. In order to reduce the domain size, a static condensation technique is implemented. This type of model permits forced response prediction including the effects of mistuning on both the aerodynamic damping as well as on the structural mode localization. A key feature of the model is that it opens up for considerations of responding mode-shapes different to the in-vacuo ones and allows aeroelastic predictions over a wide frequency range, suitable for new design concepts and parametric studies.

  • 527.
    Mayorca, Maria Angelica
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Vogt, Damian M.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Mårtensson, H.
    Fransson, Torsten H.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Prediction of Turbomachinery Aeroelastic Behavior From a Set of Representative Modes2013In: Journal of turbomachinery, ISSN 0889-504X, E-ISSN 1528-8900, Vol. 135, no 1, p. 011032-Article in journal (Refereed)
    Abstract [en]

    A method is proposed for the determination of the aeroelastic behavior of a system responding to mode-shapes which are different from the tuned in vacuo ones, due to mistuning, mode family interaction, or any other source of mode-shape perturbation. The method is based on the generation of a data base of unsteady aerodynamic forces arising from the motion of arbitrary modes and uses least square approximations for the prediction of any responding mode. The use of a reduced order technique allows for mistuning analyses and is also applied for the selection of a limited number of arbitrary modes. The application of this method on a transonic compressor blade shows that the method captures the aeroelastic properties well in a wide frequency range. A discussion of the influence of the mode-shapes and frequency on the final stability response is also provided.

  • 528.
    Mayorca, Maria Angelica
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Vogt, Damian M.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Mårtensson, Hans
    VOLVO Aero Corporation.
    Fransson, Torsten H.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Prediction of Turbomachinery Aeroelastic Behavior from a Set of Representative Modes2012In: Proceedings of the ASME Turbo Expo 2011, Vol 6, Parts And B / [ed] Presented by ASME International Gas Turbine Institute, Vancouver, Canada: American Society of Mechanical Engineers , 2012, p. 1449-1461Conference paper (Refereed)
    Abstract [en]

    A method is proposed for the determination of the aeroelastic behavior of a system responding to mode-shapes different to the tuned in-vacuo ones, due to mistuning, mode family interaction or any other source of mode-shape perturbation. The method is based on the generation of a data base of unsteady aerodynamic forces arising from the motion of arbitrary modes and uses Least Square approximations for the prediction of any responding mode. The use of a reduced order technique allows for mistuning analyses and is also applied for the selection of a limited number of arbitrary modes. The application on a transonic compressor blade shows that the method captures well the aeroelastic properties in a wide frequency range. A discussion of the influence of the mode-shapes and frequency on the final stability response is also provided.

  • 529.
    Mayorca, María A.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    De Andrade, Jesus A.
    Vogt, Damian M.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Mårtensson, Hans
    Fransson, Torsten H.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Effect of Scaling of Blade Row Sectors on the Prediction of Aerodynamic Forcing in a Highly Loaded Transonic Compressor Stage2011In: Journal of turbomachinery, ISSN 0889-504X, E-ISSN 1528-8900, Vol. 133, no 2, p. 021013-Article in journal (Refereed)
    Abstract [en]

    An investigation of the sensitivity of a geometrical scaling technique on the blade forcing prediction and mode excitability has been performed. A stage of a transonic compressor is employed as a test object. A scaling ratio is defined, which indicates the amount of scaling from the original geometry. Different scaling ratios are selected and 3D Navier-Stokes unsteady calculations completed for each scaled configuration. A full-annulus calculation (nonscaled) is performed serving as reference. The quantity of interest is the generalized force, which gives a direct indication of the mode excitability. In order to capture both up- and downstream excitation effects, the mode excitability has been assessed on both rotor and stator blades. The results show that the first harmonic excitation can be predicted well for both up-and downstream excitations using moderate amounts of scaling. On the other hand, the predictions of second harmonic quantities do show a higher sensitivity to scaling for the investigated test case.

  • 530.
    Mayorca, María A.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Vogt, Damian M.
    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.
    Mårtensson, H.
    A New Reduced Order Modeling for Stability and Forced Response Analysis of Aero-Coupled Blades Considering Various Mode Families2012In: Journal of turbomachinery, ISSN 0889-504X, E-ISSN 1528-8900, Vol. 134, no 5, p. 051008-Article in journal (Refereed)
    Abstract [en]

    This paper presents the description and application of a new method for stability and forced response analyses of aerodynamically coupled blades considering the interaction of various mode families. The method, here referred as multimode least square, considers the unsteady forces due to the blade motion at different modes shape families and calculates the aerodynamic matrixes by means of a least square (L2) approximations. This approach permits the prediction of mode families' interaction with capabilities of structural, aerodynamic and force mistuning. A projection technique is implemented in order to reduce the computational domain. Application of the method on tuned and structural mistuned forced response and stability analyses is presented on a highly loaded transonic compressor blade. When considering structural mistuning the forced response amplitude magnification is highly affected by the change in aerodynamic damping due to mistuning. Analyses of structural mistuning without aerodynamic coupling might result in over-estimated or under-estimated response when the source of damping is mainly aerodynamic. The frequency split due to mistuning can cause that mode families' interact due to reducing their frequencies separation. The advantage of the present method is that the effect of mode family interaction on aerodynamic damping and forced response is captured not being restricted to single mode families.

  • 531.
    Mayorca, María A.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Vogt, Damian M.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Mårtensson, Hans
    VOLVO Aero Corporation, Trollhättan, Sweden.
    Fransson, Torsten H.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    A New Reduced Order Modeling for Stability and Forced Response Analysis of Aero-Coupled Blades Considering Various Mode Families2010In: Proceedings of ASME Turbo Expo 2010: Scottish Exhibition & Conference Centre / [ed] ASME 2010, Glasgow, UK: ASME 2010 , 2010, p. 1-10Conference paper (Refereed)
    Abstract [en]

    This paper presents the description and application of a new method for stability and forced response analyses of aerodynamically coupled blades considering the interaction of various mode families. The method, here referred as MLS (Multimode Least Square), considers the unsteady forces due to the blade motion at different modes shape families and calculates the aerodynamic matrixes by means of a least square (L2) approximations. This approach permits the prediction of mode families’ interaction with capabilities of structural, aerodynamic and force mistuning. A projection technique is implemented in order to reduce the computational domain. Application of the method on tuned and structural mistuned forced response and stability analyses is presented on a highly loaded transonic compressor blade. When considering structural mistuning the forced response amplitude magnification is highly affected by the change in aerodynamic damping due to mistuning. Analyses of structural mistuning without aerodynamic coupling might result in over-estimated or under-estimated response when the source of damping is mainly aerodynamic. The frequency split due to mistuning can cause that mode families’ interact due to reducing their frequencies separation. The advantage of the present method is that the effect of mode family interaction on aerodynamic damping and forced response is captured not being restricted to single mode families.

  • 532.
    Mayorca, María Angélica
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Development and Validation of a Numerical Tool for the Aeromechanical Design of Turbomachinery2010Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    In aeromechanical design one of the major rules is to operate under High Cyclic Fatigue (HCF) margins and away from flutter. The level of dynamic excitations and risk of HCF can be estimated by performing forced response analyses from blade row interaction forces or Low Engine Order (LEO) excitation mechanisms. On the other hand, flutter stability prediction can be assessed by calculation of aerodynamic damping forces due to blade motion. In order to include these analyses as regular practices in an industrial aeromechanical design process, interaction between the fields of fluid and structural dynamics must be established in a rather simple yet accurate manner. Effects such as aerodynamic and structural mistuning should also be taken into account where parametric and probabilistic studies take an important role.

    The present work presents the development and validation of a numerical tool for aeromechanical design. The tool aims to integrate in a standard and simple manner regular aeromechanical analysis such as forced response analysis and aerodynamic damping analysis of bladed disks.

    Mistuning influence on forced response and aerodynamic damping is assessed by implementing existing model order reduction techniques in order to decrease the computational effort and assess results in an industrially applicable time frame.  The synthesis program solves the interaction of structure and fluid from existing Finite Element Modeling (FEM) and Computational Fluid Dynamics (CFD) solvers inputs by including a mapping program which establishes the fluid and structure mesh compatibility. Blade row interaction harmonic forces and/or blade motion aerodynamic damping forces are inputs from unsteady fluid dynamic solvers whereas the geometry, mass and stiffness matrices of a blade alone or bladed disk sector are inputs from finite element solvers. Structural and aerodynamic damping is also considered.

    Structural mistuning is assessed by importing different sectors and any combinations of the full disk model can be achieved by using Reduced Order Model (ROM) techniques. Aerodynamic mistuning data can also be imported and its effects on the forced response and stability assessed. The tool is developed in such a way to allow iterative analysis in a simple manner, being possible to realize aerodynamically and structurally coupled analyses of industrial bladed disks. A new method for performing aerodynamic coupled forced response and stability analyses considering the interaction of different mode families has also been implemented. The method is based on the determination of the aerodynamic matrices by means of least square approximations and is here referred as the Multimode Least Square (MLS) method.

    The present work includes the program description and its applicability is assessed on a high pressure ratio transonic compressor blade and on a simple blisk.

  • 533.
    Mayorca, María Angélica
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    De Andrade, Jesús A.
    Universidad Simon Bolivar - USB Laboratorio de Conversión de Energia Mecánica Sartenejas, Miranda, Venezuela.
    Vogt, Damian
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Mårtensson, Hans
    VOLVO Aero Corporation, Trollhättan, Sweden.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Effect of scaling of blade row sectors on the prediction of aerodynamic forcing in a highly-loaded transonic compressor stage2009In: PROCEEDINGS OF THE ASME TURBO EXPO 2009, VOL 6, PTS A AND B, 2009, p. 535-546Conference paper (Refereed)
    Abstract [en]

    An investigation of the sensitivity of a geometrical scaling technique on the blade forcing prediction and mode excitability has been performed. A stage of a transonic compressor is employed as test object. A scaling ratio is defined which indicates the amount of scaling from the original geometry. Different scaling ratios are selected and 3D Navier Stokes unsteady calculations completed for each scaled configuration. A full annulus calculation (non-scaled) is performed serving as reference. The quantity of interest is the generalized force, which gives a direct indication of the mode excitability. In order to capture both up- and downstream excitation effects the mode excitability has been assessed on both rotor and stator blades. The results show that first harmonic excitation can be predicted well for both up- and downstream excitation using moderate amount of scaling. On the other hand, the predictions of second harmonic quantities do show a higher sensitivity to scaling for the investigated test case.

  • 534.
    Mayorca, María Angélica
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Vogt, Damian M.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Andersson, C.
    Mårtensson, Hans
    VOLVO Aero Corporation.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Uncertainty of forced response numerical predictions of an industrial blisk - Comparison with experiments2012In: Proceedings of the ASME Turbo Expo 2012: Volume 7, Issue PARTS A AND B, 2012, ASME Press, 2012, p. 1537-1548Conference paper (Refereed)
    Abstract [en]

    Numerical methods, both Computational Fluid Dynamics (CFD) as well as Finite Elements (FE) methods, are widely used in industry with the purpose of predicting potential fatigue problems early in the design process. However, the uncertainty of such predictions is not clearly identified. The present paper presents the prediction of the vibration response of a rotor blisk part of 1 1/2 transonic compressor stage with comparison with experiments. Different uncertainty sources along the numerical aeromechanical chain are then identified. CFD solvers are employed for the prediction of both blade row interaction forces as well as the aerodynamic damping determination. Mistuning is assessed by the use of Reduced Order Modeling analyses and results compared with tip timing data. The peak amplitude response of a resonance mode of interest is determined for two different inlet conditions and thus the accuracy dependence on the excitation level is discussed. Results show that the largest uncertainties come from the unsteady aerodynamics, in which both aerodynamic damping and forcing estimations are critical. The structural dynamic models seem to capture the vibration response and mistuning effects well. Additionally, the challenges of tip timing data processing for detailed one-to-one validation of the tools are highlighted.

  • 535.
    Mayorca, María Angélica
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Vogt, Damian
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Mårtensson, Hans
    VOLVO Aero Corporation, Trollhättan, Sweden.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Numerical tool for prediction of aeromechanical phenomena in gas turbines2009In: 19th ISABE Conference / [ed] ISABE, Montreal: American Institute of Aeronautics and Astronautics Inc. , 2009, p. 1-11Conference paper (Refereed)
    Abstract [en]

    A numerical tool for aeromechanic design is presented. The output of the tool is the fatigue risk of the critical blade obtained by the Haigh diagram, and stability curves for the stability analyses. The tool integrates results from commercial Computational Fluid Dynamics (CFD) and Finite Element (FE) solvers. It uses a Reduced Order Modeling (ROM) technique in order to account for mistuning effects in an efficient way. The description of the numerical tool and an overview of typical results are presented in this paper. The applicability of the tool in the industrial design process is discussed as well as the outlook of the targeted capabilities.

  • 536.
    McGee, Seán
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Thermal energy management and chemical reaction investigation of micro-proton exchange membrane fuel cell and fuel cell system using finite element modelling2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Fuel cell systems are becoming more commonplace as a power generation method and are being researched, developed, and explored for commercial use, including portable fuel cells that appear in laptops, phones, and of course, chargers. This thesis examines a model constructed on inspiration from the myFC PowerTrekk, a portable fuel cell charger, using COMSOL Multiphysics, a finite element analysis software. As an educational tool and in the form of zero-dimensional, two-dimensional, and three-dimensional models, an investigation was completed into the geometric construction, air conditions and compositions, and product materials with a best case scenario completed that summarizes the results identified. On the basis of the results of this research, it can be concluded that polyoximetylen and high-density polyethylene were considered as possible materials for the majority of the product, though a more thorough investigation is needed. Air flow of above 10 m/s, air water vapour mass fraction below 50% and initial temperature between 308K and 298K was considered in this best scenario. Suggestions on future expansions to this project are also given in the conclusion.

  • 537.
    Meng, Yuanjing
    et al.
    Jilin Univ, Minist Educ, Key Lab Phys & Technol Adv Batteries, Coll Phys, Changchun 130012, Jilin, Peoples R China.;Hubei Univ, Fac Phys & Elect Sci, Hubei Collaborat Innovat Ctr Adv Organ Chem Mat, Wuhan 430062, Hubei, Peoples R China..
    Mi, Youquan
    Hubei Univ, Fac Phys & Elect Sci, Hubei Collaborat Innovat Ctr Adv Organ Chem Mat, Wuhan 430062, Hubei, Peoples R China..
    Xu, Fuzhan
    Jilin Univ, Minist Educ, Key Lab Phys & Technol Adv Batteries, Coll Phys, Changchun 130012, Jilin, Peoples R China..
    Wang, Xunying
    Hubei Univ, Fac Phys & Elect Sci, Hubei Collaborat Innovat Ctr Adv Organ Chem Mat, Wuhan 430062, Hubei, Peoples R China..
    Xia, Chen
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Dong, Wenjing
    Hubei Univ, Fac Phys & Elect Sci, Hubei Collaborat Innovat Ctr Adv Organ Chem Mat, Wuhan 430062, Hubei, Peoples R China..
    Ji, Yuan
    Jilin Univ, Minist Educ, Key Lab Phys & Technol Adv Batteries, Coll Phys, Changchun 130012, Jilin, Peoples R China..
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Hubei Univ, Fac Phys & Elect Sci, Hubei Collaborat Innovat Ctr Adv Organ Chem Mat, Wuhan 430062, Hubei, Peoples R China.
    Low-temperature fuel cells using a composite of redox-stable perovskite oxide La0.7Sr0.3Cr0.5Fe0.5O3-delta and ionic conductor2017In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 366, p. 259-264Article in journal (Refereed)
    Abstract [en]

    A novel solid oxide fuel cell (SOFC) incorporating the semiconductor with the ionic conductor to replace the traditional electrolyte layer with improved performance has been recently reported. In the present work, we found that the redox stable electrode material La0.7Sr0.3Cr0.5Fe0.5O3-delta(LSCrF) can be considered as a good candidate for such configuration, electrolyte layer-free fuel cells (EFFCs), due to its high ionic and electronic conductivities, excellent catalytic activity and good chemical stability. EFFCs based on the composite of perovskite oxide LSCrF and ionic conductor Ce0.8Sm0.2O2-delta (SDC) offered promising performances, i.e., 1059 mW cm(-2) at 550 degrees C without any electronic short circuiting problem. It even exhibited a highly promising result of 553 mW cm(-2) at 470 degrees C in further low-temperature operation. These high performances can be attributed to the improved conductivity, more triple-phase boundaries (TPB) and accelerated oxygen reduction reaction (ORR) of LSCrF-SDC composite. The influence of the weight ratio between LSCrF and SDC on the EFFC electrochemical performance was investigated. This new discovery indicates a great potential for exploring multifunctional perovskites for the new SOFC technologies.

  • 538.
    Meng, Yuanjing
    et al.
    Jilin Univ, Coll Phys, Minist Educ, Key Lab Phys & Technol Adv Batteries, Changchun 130012, Jilin, Peoples R China.;Hubei Univ, Fac Phys & Elect Sci, Hubei Collaborat Innovat Ctr Adv Organ Chem Mat, Wuhan 430062, Hubei, Peoples R China..
    Wang, Xunying
    Hubei Univ, Fac Phys & Elect Sci, Hubei Collaborat Innovat Ctr Adv Organ Chem Mat, Wuhan 430062, Hubei, Peoples R China..
    Xia, Chen
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Wang, Baoyuan
    Hubei Univ, Fac Phys & Elect Sci, Hubei Collaborat Innovat Ctr Adv Organ Chem Mat, Wuhan 430062, Hubei, Peoples R China..
    Dong, Wenjing
    Hubei Univ, Fac Phys & Elect Sci, Hubei Collaborat Innovat Ctr Adv Organ Chem Mat, Wuhan 430062, Hubei, Peoples R China..
    Ji, Yuan
    Jilin Univ, Coll Phys, Minist Educ, Key Lab Phys & Technol Adv Batteries, Changchun 130012, Jilin, Peoples R China..
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Faculty of Physics and Electronic Science, Hubei University, Wuhan, Hubei 430062, China.
    High-performance SOFC based on a novel semiconductor-ionic SrFeO3-delta-Ce0.8Sm0.2O2-delta membrane2018In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 43, no 28, p. 12697-12704Article in journal (Refereed)
    Abstract [en]

    The semiconductor-ionic composite membrane has been recently developed for a novel solid oxide fuel cell (SOFC), i.e., the semiconductor-ion membrane fuel cell (SIMFC). In this work, the perovskite-type SrFeO3-delta (SFO) as semiconductor material was composited with ionic conductor Ce0.8Sm0.2O2-delta (SDC) to form the SFO-SDC composite membrane for SIMFCs. The SFO-SDC SIMFCs using the optimized weight ratio of 3:7 SFO-SDC membrane obtained the best performances, 780 mW cm(-2) at 550 degrees C, compared to 348 mW cm(-2) obtained from the pure SDC electrolyte fuel cell. Introduction of SFO into SDC can extend the triple phase boundary and provide more active sites for accelerating the fuel cell reactions, thus significantly enhanced the cell power output. Moreover, SFO was employed as the cathode, and a higher power output, 907 mW cm(-2) was achieved, suggesting that SFO cathode is more compatible for the SFO-SDC system in SIMFCs. This work provides an attractive strategy for the development of low temperature SOFCs.

  • 539.
    Menigoz, Chloé
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Establishment of a robust sizing tool for Centrifugal Compressors2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis examines the possibility of creation of a robust sizing tool for centrifugal compressor. The sizing tool will be based on a 1D-analysis, a very quick and reliable way to design a centrifugal compressor. The aim of the sizing method is to have the best possible efficiency.

    This study is based on the available literature on turbomachinery. With that scientific content, the development of the sizing tool has been attempted in two manners.

    The first was based on publications on centrifugal compressors. The methodology was to implement scientific content on centrifugal compressors into a simple and intuitive sizing method, with the minimum input parameters.

    The second implemented method was based on publications dedicated to radial turbines. It was based on the observation that radial turbines look very similar to centrifugal compressors. As the literature on radial turbines is much more developed than literature on centrifugal compressors, the attempt was made to transform radial turbine sizing methods into centrifugal compressors sizing method.

    After having read publications and having implemented the content into several sizing methods, the third part of the thesis is the analysis of the results. All results from turbine-based methods have been compared to each other in order to determine if they were relevant. The next step was to compared compressor-based method to turbine-based method. This highlighted the fact that a turbine method has results similar to the compressor-based method, which prove that this attempt was not senseless.

    Results from all methods have been compared to usual ratios to determine if they were adequate. Unfortunately some figures seem false and they will need a further investigation.

    Unfortunately there are some inconsistencies in the resutls of the different assessed methods that may need further investigation.

    After having solved the few problems that remains, the 1D-design of the compressor will be completed and it will be a good starting point for the 3D-analysis, last step of the compressor design. The use of a 1D-analysis to design primarily the compressor is a very smart way of doing compared to the time-consuming 3D-analysis.

  • 540.
    Menya, Emmanuel
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Assessment of Pollution Levels Resulting from Biomass Gasification2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Today the large scale introduction of biomass gasification is hampered by health, safety and environmental issues which present a major barrier in the deployment of this technology. The condensate in particular resulting from producer gas cooling before use in gas engines is highly toxic and carcinogenic which, if not adequately controlled, can lead to detrimental impacts on human health and the environment. The study was therefore aimed at assessment of pollution levels resulting from biomass gasification organic condensates. The study involved assessing the concentration of polycyclic aromatic hydrocarbons (PAHs) and BTEX (i.e. benzene, toluene, ethylbenzene and xylene) in the condensate deemed toxic and carcinogenic, mention their impact on human health and the environment as well as recommend measures aimed at minimizing pollution levels resulting from biomass gasification.

     

    The gasifier installation at Makerere University was run in downdraft mode using maize cobs as biomass fuel. The producer gas was cooled using a water cooled condenser connected to the exhaust pipe of the gasifier. The condensate was then transferred into sampling bottles made of opaque glass to minimize photochemical reactions in water samples and preserved in a cooler at 2oC to 6oC until the time for analysis to minimize volatilization and bacterial degradation of the hydrocarbons. The capillary gas chromatography with mass spectrometric detector (CGCMSD) was used to analyze the condensate for the selected hydrocarbons.

    The procedures involved preparation of PAHs and BTEX standard solutions using standard mixtures and internal standards, calibration of the CGCMSD, extraction of the aromatic hydrocarbons using hexane, performing a surrogate analysis to assess percent recoveries and injecting a 2 µl aliquot of the final solution of each test sample in a CGCMSD for analysis. Identification of targeted hydrocarbons was based on the retention time match and mass spectra match against the calibration standards while quantitation was done by use of internal standards.

     

    The average concentration of naphthalene was 204.3 mg/m3, benzene-16.8 mg/m3,toluene-105.5 mg/m3, ethylbenzene-200.9 mg/m3, 1,2-dimethyl benzene-209.5 mg/m3 and 1,3+1,4-dimethyl benzene-790.4 mg/m3. Acenaphthylene, acenaphthene, fluorene, phenanthrene and anthracene were not detected in the condensate by the CGCMSD due to their concentration levels being below the detection limit of the CGCMSD. The concentrations of naphthalene and xylene were considerably high compared to the recommended permissible exposure limits thus posing risks on both human health and the environment. It is therefore important to treat the condensate before disposal to the environment. On the other hand, the concentrations of benzene, toluene and ethylbenzene were below the permissible exposure limit and therefore for this study, the liquid effluent was considered to meet the regulatory standards. The recommendations aimed at minimizing pollution levels during biomass gasification were also discussed.

  • 541.
    Mergulhao, Vasco
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Innovation and Optimization of Energy Systems in the Temporary Entertainment Events Industry: Modeling & Optimization of temporary energy systems2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    An unprecedented view into the nature of energy systems in the Temporary Entertainment Events Industry (TEEI) is developed. A characterization of the context of the latter and its energy systems state-of-the-art is performed. Allowing for the main development of the present study, the modeling of temporary energy systems in the TEEI, ultimately delivering a tool for the assessment of the performance of these systems at a level of analytical detail previously inexistent in the industry. In the absence of previews literature on the topic, state-of-the-art modeling techniques have been reviewed from the field of small-scale polygeneration system to develop a customized approach for the modeling of temporary energy systems. An Integrated Design, Synthesis and Operation Optimization (IDSOO) approach has been adapted in a Mixed Integer Linear Programing (MILP) model and contextualized for the TEEI. Additionally, a customized approach has been developed for the treatment and compression of the original energy demand curves in a separate optimization algorithm defined in respect to the constraints and priorities of the given context. The model has been developed to cater to the evaluation of the targets set by the Festival Vision 2025 pledge. Which is then applied in a case study event set in the United Kingdom (UK), with over 50 000 visitors over a period of 4 days. In addition to the evaluation of the pledge’s targets, two additional scenarios are created to better explore to full potential of the methodology presently developed. Namely, first an integrated system approach and its benefits has been evaluated to counterpose the established practice of isolating the event’s energy sub-systems. Secondly, the effects of the prevailing energy demand uncertainty in TEEI and its typical preference of overgenerous systems’ designs are analyzed in a hypothetical, yet representative, scenario. Finally, given the pioneering nature of the developed study, a listing has been made with the argued most relevant future study topics that were found to offer the highest benefits to the TEEI. In conclusion, it has been found that there seems to be more potential than previously thought for the improvement of the performance of the TEEI’s current energy systems. It is shown that even when optimized, isolated generator-based systems in some cases will inevitably incur into undesired operational conditions, thus demonstrating the limits of the current practices and technology selection. Nevertheless, it was found that, at least for the given case study, the Festival Vision 2025 medium term targets are achievable even when resorting solely to the optimization of the current diesel-based systems. Reinstating the need for better energy systems planning and designs. Ultimately, it was concluded that the developed model fulfills the objective of representing the TEEIs energy systems to a level of detail unprecedented and that it, or similar tools, could be used to quantify and substantiate the implications of the industry’s environmental goals for its energy systems.

  • 542.
    Michaut, Stephane
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Market Analysis for Gas Engine Technology in Algeria2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The objective of this diploma thesis is to investigate the potential of combined heat and power plants based on gas engine technology in Algeria. This market analysis has been performed in order to identify the key markets for the newly created French subsidiary of Clarke Energy Group to expand its business in North Africa. After analyzing the structure of the Algerian energy sector and the potential of each gas engine application, three key sectors were identified. For each sector, a technical and economical analysis was conducted in order to define its potential, its constraints, and the time frame under which they could become mature markets.

    With a potential of 300 MW, the first targeted sector is related to the national power utility Sonelgaz and consists in small scale power plants with a nominal power output < 20 MW, in which the use of gas engines instead of gas turbines could reduce up to 50% the price of kWh generated over the lifecycle of the plant. With a total of 450 MW, the second market representing a great potential for gas engines development in Algeria is the industrial sector and in particular brick factories, in which cogeneration plants become profitable within 4 years, can save up to 40% of primary energy and generate electricity whose cost of production is 30% lower than the average grid price. Finally, the third sector identified is the associated petroleum gas from which 9% – 5.10

    ⁹ cubic meters – are is still being flared in Algeria while they could be used to generate up to 300 MW for the O&G utilities if only 10% of them would be recovered, reducing thus CO2 emissions and diesel costs.

    This report presents the method and the tools that were developed in order to analyze the economical viability of gas engine based power plants for the three targeted markets in Algeria, and the final results from the study.

  • 543.
    Mikaillian, Navid
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Test Turbine Measurements and Comparison with Meanline and Throughflow Calculations2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis is a collaboration between Siemens Industrial Turbomachinery(SIT) and Royal Institute of Technology(KTH). It is aimed to study and compare the outputs of two different computational approaches in axial gas turbine design procedure with the data obtained from experimental work on a test turbine. The main focus during this research is to extend the available test databank and to further understand and investigate the turbine stage efficiency, mass flow parameters and reaction degree under different working conditions. Meanwhile the concept and effect of different loss mechanisms and models will be briefly studied.

     The experimental part was performed at Heat and Power  Technology department on a single stage test turbine in its full admission mode. Three different pressure ratios were tested. For the medium pressure ratio a constant temperature anemometry (CTA) method was deployed in two cases, with and without turbulence grid, to determine the effect of free-stream turbulence intensity on the investigated parameters. During the test campaign the raw gathered data was processed with online tools and also they served as boundary condition for the computational codes later.

     The computational scope includes a one-dimensional design approach known as mean-line calculation and also a two-dimensional method known as throughflow calculation. An in-house SIT software, CATO, generated the stage geometry (vane, blade and the channel) and then two other internal computational codes, MAC1 and BETA2, were employed for the one-dimensional and two-dimensional computations respectively. It was observed that to obtain more accurate mass flow predictions a certain level of channel blockage should be implemented to represent the boundary layer development and secondary flow which is typically around 2%. The codes are also equipped with two options to predict the friction loss: One is a more empirical correlation named as the Old approach in SIT manuals and the other works based on allocation of boundary layer transition point, named as BL in the present thesis. Simulations were done by use of both approaches and it turned out that the latter works more accurately if it is provided with appropriate transition point and blockage estimation.

     The measured data also suggests the idea that the transition point of the vane and blade is not affected by a change in turbulence intensity at least up to 6% in the tested Reynolds numbers, . Amongst different solutions the one which used BL approach and constant transition point (while the turbulence intensity changed) managed to predict this behavior. Also it was investigated and revealed that the codes inherently predict poor results in off-design loadings which is mainly due to positive incidence angle in addition to high spanwise gradient of the flow parameters.

  • 544.
    Mingaleeva, Renata
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Wind turbines application for energy savings in Gas transportation system2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Thesis shows the perspectives of involving renewable energy resources into the energy balance of Russia, namely the use of wind energy for the purpose of energy supply for the objects of the Russian Gas transportation system. The methodology of the wind energy technical potential calculation is designed and the wind energy technical potential assessment for onshore and offshore zones of Russia is presented.

    The analysis of Russian Gas transportation system in terms of energy consumption is carried out when comparing the map of wind resources in Russia with the map of Russian Gas transportation system and the perspective of wind turbines installation is shown in order to offset energy consumption of the selected object of the Gas transportation system.

    The decision-making algorithm for wind turbines selection is developed for installation on the wind farm.

    Also indicators of investment attractiveness of the project of using wind turbines for compression stations energy supply were calculated.

  • 545.
    Mironovs, A.
    et al.
    D un D Centrs.
    Doronkins, P.
    D un D Centrs.
    Fridh, Jens
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    MODELING OF VARIABLE AERODYNAMIC FORCES IN TURBINE BASED ON EXPERIMENTAL DATA2009In: Proceedings of the 12th International Symposium on Unsteady Aerodynamics, Aeroacoustics & Aeroelasticity of Turbomachines ISUAAAT12 1-4 September 2009, Imperial College London, UK, Imperial College Press, 2009Conference paper (Other academic)
    Abstract [en]

    Effective methods of vibration diagnostics of a turbomachine’s flow duct are necessary for efficient condition based maintenance. Modern equipments provide extended opportunities for vibration measurements. However, there are few adequate models of high frequency vibration. A majority of the existing diagnostic techniques are limited within the low frequency range. This paper suggests the variable forces model intended for high frequency vibration diagnostics. For modeling of variable forces acting on the vane the test series are performed using a two-stage air test turbine. High frequency signals of total pressure and casing vibration are measured in order to investigate the airflow and vibration structure generated by the blades. Parameters of the blade wake are investigated and the wake’s dual nature is determined. Harmonic and random components of blade wakes are related to specific blade aerodynamic features as well as upstream airflow characteristics. Air duct failures are simulated with upstream static and rotating disturbances. The model of flow velocity oscillation, which acconts for both harmonic and random features of blade wakes is presented. Dynamic forces acting on a single vane are also modeled based on the model of blade wakes.

  • 546.
    Miti, Wilson
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. The University of Zambia, Department of Physics.
    Energy Efficiency and Carbon Management in Mineral Processing Plants2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Copper processing plants involved in smelting, electro-refining and electro-winning are heat-intensive undertakings that provide extensive challenges for attainment of high energy efficiency. Literature has shown that most of these plants, especially smelters, operate at low overall energy efficiency due to the seemingly complex energy scenario where heat and electricity as forms of energy are treated distinctively from each other. Many copper processing plants have not yet explored both available and emerging waste heat recovery technologies hence remain operating at lower energy efficiencies.

    In the copper processing plants under study in particular the Nchanga tailings leach plant (TLP), plant operators hinted that some of the processes that ought to operate in heated environments operate at ambient temperatures because of lack of a heating mechanism. The project discusses possible heating mechanisms from available local resources and applicable technologies. As the competing options for providing the required heat at the Nchanga TLP present different carbon emission scenarios, the carbon emissions associated to the recommended installations shall be quantified against a suitable baseline. Flue gas waste heat from the nearby Nchanga smelter has been taken as the available local energy source on which the applicable heating scenarios at TLP are analyzed.

    The project analyzed waste heat scenarios for three furnaces at Nchanga smelter where it has been established that flue gases from the furnaces contain 37.31 MW of waste heat. Analysis for channeling the waste heat into heat recovery steam generators gave the steam turbine power generation potential of 7.06 MW. The project also demonstrated how energy efficiency undertakings can be used as a driver for carbon emission reduction measures and for participation to the available carbon trading mechanisms such as CDM. Selection of suitable baseline scenarios revealed a lot of potential for carbon finance undertakings in the three case study plants. At the Nchanga smelter, the 7.06 MW power generation capacity has an associated potential of 61,820 tCO2/year emission reductions that can be monetized through the available carbon trading markets. The research established that Nchanga TLP has a heating demand of 10.87MW. If this heating demand was to be met by using the smelter waste heat, the undertaking can be taken as CDM activity or other carbon trading platform with an associated potential of 95,183 tCO2/year.

  • 547.
    Mitrokhin, Alexey
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Gubkin Russian State University of Oil and Gas.
    Energy saving in the process of gas pipeline overhaul2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The problem of energy saving during overhaul of a linear part of gas trunkline is regarded in this paper. This issue has been analyzed from different perspectives.

    Thermodynamic analysis of gas evacuation from a string that is off operation for the overhaul to a parallel or adjacent string with the use of mobile compressor systems was made. Economical attractiveness of mobile compressor systems applications was proved.

    Various methods of gas trunklines linear parts overhaul have been considered. For each of the methods problems of minimization of necessary for the overhaul amount of energy consuming machines have been solved.

    The results can be used in the development of overhaul projects of the gas trunklines linear parts.

  • 548.
    Mitrus, Andrea
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    NUMERICAL INVESTIGATION OF BLADE LEADING EDGE CONTOURING BY FILLET AND BASELINE CASE OF A TURBINE VANE: A comparative study of the effect on secondary flow2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The understanding of secondary flow behavior has become an important aspect in the design of modern gas turbines. Secondary flow gives rise to aerodynamic losses, distorts the thermal field and affects the flow conditions at the exit of a passage negatively. Therefore, reducing secondary flow is a major concern for efficiency improvement. Many passive control-methods have been suggested by turbine designers and researchers, and one very promising modification is blade leading edge contouring near the endwall. At the Division of Heat and Power Technology KTH, Stockholm, a detailed experimental investigation of three filleted nozzle guide vanes in an annular sector cascade has been performed, providing excellent experimental data for numerical validation of complex turbine flows.

    Based on the above, a numerical study and aerodynamic investigation for a leading edge filleted vane and baseline vane has been performed. The potential effect of the leading edge fillet on flow structure and secondary losses has been evaluated based on a number of flow parameters, and computational predictions have been compared to experimental results.

    The numerical investigation has shown some differences in the flow behavior between the filleted and baseline case. All results indicate that the fillet affects the flow structure in regions close to the hub endwall. It shifts the position of vortices and loss core. However, the overall effect on reducing secondary losses downstream of the passage is insignificant. Additionally, the numerical results show good qualitative agreement with experimental results.

  • 549. Moghaddam, V. H.
    et al.
    Kazachkov, Ivan V.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. National Technical University of Ukraine.
    About modeling of the corium jet penetrating the pool of volatile coolant under reactor vessel2010In: Applied computer science, 2010, p. 89-95Conference paper (Refereed)
    Abstract [en]

    The mathematical model developed and some results of its application to an element of a passive protection system against severe accidents at the nuclear power plant (NPP) with a water pool under reactor vessel for corium melt and particles' cooling are presented in the paper. This is an important element of a passive protection system against severe accidents at NPP, which must keep nuclear fuel and other radioactive materials (corium) inside the containment. The penetration behavior of a high-temperature corium jet into a pool of volatile coolant (water), with account of the vapor produced on a melt jet penetration, has been investigated. Success of the problem's solution determines an effectiveness and durability of the passive protection system against severe accidents. Therefore the results obtained may be useful for the development and calculation of such passive protection systems at the NPP. Except theoretical interest for the dynamics of multiphase flows, the problem is of interest for practical applications in nuclear power safety problems, which are probably the most important in further development of the nuclear power industry in the world. Present operation of the nuclear power plants (NPP) still considered by many countries as the highest priority energy source requires strict nuclear power safety substantiation. In the nuclear reactors of the third generation, which are necessary at the change to the operable reactors of the second generation, the passive systems (they are capable for work even under the conditions of the complete NPP de-energizing) must work perfect under any severe accident scenario, to localize emergency and prevent spreading of the radioactive fuel outside the containment.

  • 550. Mohan, G.
    et al.
    Kumar, U.
    Pokhrel, M. K.
    Martin, Andrew
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    A novel solar thermal polygeneration system for sustainable production of cooling, clean water and domestic hot water in United Arab Emirates: Dynamic simulation and economic evaluation2016In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 167, p. 173-188Article in journal (Refereed)
    Abstract [en]

    In this paper, a novel solar thermal polygeneration (STP) system for production of cooling, clean water and domestic hot water is modeled and analyzed for the weather conditions of United Arab Emirates (UAE). The system comprises of solar collectors for production of thermal energy, single stage LiBr-H2O absorption chiller (VAC) for providing air conditioning to office cabins and membrane distillation (MD) modules for clean water production along with domestic hot water generation as by-product. The performance of STP is analyzed with three different solar collectors - flat plate collectors (FPC), evacuated tube collector (ETC) and compound parabolic collector (CPC). The system is modeled and dynamically simulated using TRNSYS software for optimization of various design parameters like slope of the collectors, mass flow rate through the collector loop, storage capacity and area of collectors. Combined and system efficiency of the STP system has been determined for optimum conditions. Economic benefits are analyzed for different collectors and fuel costs savings. A lowest payback period of 6.75 years is achieved by STP with evacuated tube collector field having gross area of 216 m2. STP system has cumulative savings of $520,000 over the life time of the project through roof top solar collector installation. In terms of environmental benefits, 109 metric tons/year of CO2 emissions would be avoided and hence the overall payback period would be reduced by 8% based on cost saving through carbon credits. Economic and environmental benefits were aided by steady system performances of absorption chiller (35 kW), membrane distiller (80 l/day) and heat recovery system (1.2 m3/h) throughout the year. The complete simulation results of the STP system is utilized for the development, installation and testing of a polygeneration system at RAKRIC.

891011121314 501 - 550 of 952
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf