Sökning: "Thermal insulation"

Visar resultat 21 - 25 av 137 avhandlingar innehållade orden Thermal insulation.

1. 21. Characterization of Conduction and Polarization Properties of HVDC Cable XLPE Insulation Materials

   Författare :Hossein Ghorbani; Hans Edin; Erling Ildstad; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; HVDC insulation; power cable insulation; cross-linked polyethylene insulation; conductivity; dielectric losses; space charge; HVDC isolation; kraftkabel isolation; tvärbunden polyeten isolationsmaterial; elektrisk ledningsförmåga; dielektriska förluster; rymdladdning; Electrical Engineering; Elektro- och systemteknik;

   Sammanfattning : Since its first introduction in 1998, extruded direct current (DC) cable technology has been growing rapidly leading to many cable system installations with operation voltages up to 320 kV. Cable manufacturers invest heavily on technology development in this field and today extruded DC cable systems for operation voltages as high as 525 kV are commercially available. LÄS MER

3. 22. Mechanisms of Electrical Ageing of Oilimpregnated Paper due to Partial Discharges

   Författare :Mohamad Ghaffarian Niasar; Hans Edin; Ernst Gockenback; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; partial discharges; oil-impregnated paper; oil; transformer insulation; dielectric frequency response; breakdown strength; ion mobility; thermal ageing; electrical ageing; moisture in paper; life time; thermal breakdown.; Electrical Engineering; Elektro- och systemteknik;

   Sammanfattning : In this thesis, partial discharge (PD) phenomenon in oil-impregnated paper (OIP) is investigated under accelerated electrical stress. The thesis is mainly focused on the characteristic of PD activity and the influence it has on the insulation properties of OIP. LÄS MER

4. 23. Predicting the Long-Term Insulation Performance of District Heating Pipes

   Författare :Camilla Persson; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; heat conduction; polyurethane foam; insulation capacity; diffusion; thermal conductivity; cyclopentane; solubility coefficient; long-term performance;

   Sammanfattning : The aim of the studies that comprise this thesis was to predict the heat loss over timefrom a range of district heating pipes insulated with closed-cells foam. The thermalconductivity of the foam changes over time when it is not diffusion-tight encapsulatedagainst the environment, as diffusion alters the cell gas composition until it reachesequilibrium with the surrounding air. LÄS MER

5. 24. Determination of the thermal conductivity of the insulation in district heating mains : Field measurements

   Författare :Karin Margaretha Borgström; Högskolan i Halmstad; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; district heating main; field measurements; thermal conductivity; measuring method; heat flow measurement; heat flux sensor; Material physics with surface physics; Materialfysik med ytfysik;

   Sammanfattning : This thesis concerns the development of a measurement method for determination in the field of the thermal conductivity of the insulation in buried district heating mains. The thermal conductivity of the insulation is calculated from the measured value of the radial heat flow through the heating main, the measured temperature difference across the insulation, and the dimensions of the heating main. LÄS MER

7. 25. Failure of thermal barrier coatings under thermal and mechanical fatigue loading : microstructural observations and modelling aspects

   Författare :Håkan Brodin; Anette M. Karlsson; Linköpings universitet; []
   Nyckelord :thermal barrier coating; TBC; delamination; crack initiation; crack propagation; crack growth; oxidation; alumina; spinel; MCrAIY; diffusion; fatigue; modelling; modeling; degradation; TECHNOLOGY; TEKNIKVETENSKAP;

   Sammanfattning : Industrial and air-borne gas turbine hot components suffer from creep, oxidation, corrosion and microstructural degradation if not shielded from the hot and aggressive combustion gases. Two major strategies commercially available are adopted; film cooling by pressurised air and application of protective coatings. LÄS MER