Sökning: "vätgas"

Visar resultat 16 - 20 av 58 avhandlingar innehållade ordet vätgas.

1. 16. Limiting processes in anion-exchange membrane fuel cells

   Författare :Henrik Grimler; Göran Lindbergh; Rakel Wreland Lindström; Carina Lagergren; Marc Secanell; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; anion-exchange membrane fuel cell; hydrogen oxidation reaction; oxygen reduction reaction; water transport; physics-based modelling; Chemical Engineering; Kemiteknik;

   Sammanfattning : Fuel cells allow for converting chemical energy stored in hydrogen into electrical energy, with only heat and water as by-products. In a sustainable energy society, hydrogen may play an important role due to its ability to act both as an energy carrier and as a valuable chemical in the process industry. LÄS MER

3. 17. Electrode degradation in proton exchange membrane fuel cells

   Författare :Alejandro Oyarce; Göran Lindbergh; Carina Lagergren; Steven Holdcroft; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; PEMFC; PEFC; Porous electrodes; Carbon corrosion; Carbon nanotubes; Carbon fibers; Polyhedral carbon nanofoams; Phosphonated hydrocarbon ionomer; Mass-transport losses; Electrode morphology; Electrode collapse; Start-up and shut-down; System strategies; Stainless steel; Bi-polar plates; In-situ contact resistance.;

   Sammanfattning : The topic of this thesis is the degradation of fuel cell electrodes in proton exchange membrane fuel cells (PEMFCs). In particular, the degradation associated with localized fuel starvation, which is often encountered during start-ups and shut-downs (SUs/SDs) of PEMFCs. At SU/SD, O2 and H2 usually coexist in the anode compartment. LÄS MER

4. 18. Development and Application of Pure Rotational CARS for Reactive Flows

   Författare :Alexis Bohlin; Förbränningsfysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Raman linewidths; gas-phase thermometry; combustion diagnostics; laser spectroscopy techniques; coherent anti-Stokes Raman scattering; molecular spectroscopy; Herman-Wallis factor; Fysicumarkivet A:2012:Bohlin;

   Sammanfattning : The thesis deals with the further development of pure rotational coherent anti-Stokes Raman spectroscopy (RCARS) for improving the capabilities of gas phase thermometry. The main effort has been to make the technique more robust when employed under a wide range of temperatures and operational conditions. LÄS MER

5. 19. Electrochemical Reactions in Polymer Electrolyte Fuel Cells

   Författare :Maria Wesselmark; Svein Sunde; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Fuel cell; model electrodes; oxygen reduction; methanol oxidation; formic acid oxidation; hydrogen oxidation; CO oxidation; degradation; tungsten oxide; carbon support; Bränslecell; modellelektroder; syrgasreduktion; metanoloxidation; myrsyraoxidation; vätgasoxidation; CO oxidation; degradering; wolfram oxid; kolsupport; Chemical engineering; Kemiteknik;

   Sammanfattning : The polymer electrolyte fuel cell converts the chemical energy in a fuel, e.g. hydrogen or methanol, and oxygen into electrical energy. The high efficiency and the possibility to use fuel from renewable sources make them attractive as energy converters in future sustainable energy systems. LÄS MER

7. 20. Solid Oxide Fuel Cell Modeling at the Cell Scale - Focusing on Species, Heat, Charge and Momentum Transport as well as the Reaction Kinetics and Effects

   Författare :Martin Andersson; Värmeöverföring; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; SOFC; anode-supported; modeling; CFD; charge species heat momentum transport; electrochemical internal reforming reactions; TPB; area-to-volume ratio; COMSOL Multiphysics;

   Sammanfattning : Fuel cells are electrochemical devices that directly transform chemical energy into electricity. They are promising for future energy systems, since they are energy efficient, able to use renewable fuels and, when hydrogen is used as fuel, there are no direct emissions of greenhouse gases. LÄS MER