Sökning: "gas diffusion"

Visar resultat 1 - 5 av 276 avhandlingar innehållade orden gas diffusion.

1. 1. Alternative methods for analysing moisture transport in buildings : Utilisation of tracer gas and natural stable isotopes

   Författare :Kjartan Gudmundsson; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; tracer gas; water vapour permeability; diffusion; surface diffusion; isotopic analysis; deuterium; oxygen-18; fractionation; vapour barrier; transient numerical modelling of diffusion; Building engineering; Byggnadsteknik;

   Sammanfattning : New methods, based on tracer gas measurements and isotopicanalysis can be used to evaluate the moisture properties ofbuilding materials and provide the means for forensic analysisof the origins and history of excessive water in buildings, theimmediate practical consequences of which will be the abilityto improve the moisture performance of constructions. It is shown, in theory and through measurements how thewater vapour permeability of porous building materials can witha good degree of accuracy be estimated with tracer gasmeasurements that provide an efficient alternative to the cupmethod. LÄS MER

3. 2. Hydrogen in nano-sized metals : Diffusion and hysteresis effects

   Författare :Wen Huang; Björgvin Hjörvarsson; Max Wolff; Gavin Walker; Uppsala universitet; []
   Nyckelord :Hydrogen; diffusion; hysteresis; optical technique; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

   Sammanfattning : Metal hydrides can be used as hydrogen storage materials for fuel cells and batteries, and as sensors for detecting hydrogen gas. The use of metal hydrides for hydrogen storage can be hindered by poor kinetics and low capacity. Moreover, poor sensitivity, long recovery and response time, limit the applications of metal hydrides as hydrogen sensors. LÄS MER

4. 3. On Diffusion Transport Properties in Fuel Cell Gas Diffusion Layers Using the Lattice Boltzmann Method

   Författare :Mayken Espinoza Andaluz; Värmeöverföring; []
   Nyckelord :PEFC; lattice Boltzmann method; gas diffusion layers; porosity; Gas-phase tortuosity; permeability; inertial coefficient; diffusibility; pore-scale modeling;

   Sammanfattning : The polymer electrolyte fuel cell (PEFC) is considered as one of the most promising devices for providing efficient, clean and noiseless conversion of chemical energy to electrical energy. This device can provide electrical and thermal energy for transport, mobile and stationary applications ranging in a wide range of power requirements. LÄS MER

5. 4. Real-time breath gas analysis of carbon monoxide : laser-based detection and pulmonary gas exchange modeling

   Författare :Ramin Ghorbani; Florian M. Schmidt; Anders Blomberg; Christoffer Boman; Staffan Schedin; Jonathan Beauchamp; Umeå universitet; []
   Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; carbon monoxide CO ; pulmonary gas exchange; computational modeling; real-time breath gas analysis; single-exhalation profile; laser absorption spectroscopy; nonlinear least-squares fitting; breath sampling; baseline level; diurnal variation; healthy population; exposure study; fysik; Physics; Physiology; fysiologi;

   Sammanfattning : Breath gas analysis is a promising approach for non-invasive medical diagnostics and physiological monitoring. Real-time, breath-cycle resolved biomarker detection facilitates data interpretation and has the potential to improve the diagnostic value of breath tests as exhalation profiles carry spatiotemporal information about biomarker origin and gas exchange in the respiratory tract. LÄS MER

7. 5. Evaluation, Experience and Potential of Gas Turbine Based Cycles with Humidification

   Författare :Torbjörn Lindquist; Kraftverksteknik; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Model Validation; Recuperator; Flue Gas Condensation; Humidification; Gas Turbine; Advanced Thermodynamic Cycles; HAT; Humid Air Turbine; Evaporative Gas Turbine Cycle; EvGT; Operating Experience; EvGT Pilot Plant; Thermal engineering; applied thermodynamics; Termisk teknik; termodynamik;

   Sammanfattning : Gas turbines, in simple and combined cycle, are common and economically profitable on the power generating market today. Several new cycles have been proposed as future competing technologies, but all studies about these cycles have, so far, been paperwork. LÄS MER