Sökning: "Mechanical engineering"
Visar resultat 1 - 5 av 6992 avhandlingar innehållade orden Mechanical engineering.
1. Distributed thermal response tests : New insights on U-pipe and Coaxial heat exchangers in groundwater-filled boreholes
Sammanfattning : U-pipe Borehole Heat Exchangers (BHE) are widely used today in ground source heating and cooling systems in spite of their less than optimal performance. This thesis provides a better understanding on the function of U-pipe BHEs and Investigates alternative methods to reduce the temperature difference between the circulating fluid and the borehole wall, including one thermosyphon and three different types of coaxial BHEs. LÄS MER
2. Large-Eddy Simulation of Gasoline Fuel Spray Injection at Ultra-High Injection Pressures
Sammanfattning : Gasoline direct injection is a state-of-the-art technique that reduces hydrocarbon and particulate emissions. However, further improvement is needed to meet current as well as future emission regulations. LÄS MER
3. Modular Battery Systems for Electric Vehicles based on Multilevel Inverter Topologies - Opportunities and Challenges
Sammanfattning : Modular battery systems based on multilevel inverter (MLI) topologies can possibly overcome some shortcomings of two-level inverters when used for vehicle propulsion. The results presented in this thesis aim to point out the advantages and disadvantages, as well as the technical challenges, of modular vehicle battery systems based on MLIs in comparison to a conventional, two-level IGBT inverter drivetrain. LÄS MER
4. Thermal insulation of the combustion chamber in a light duty diesel engine
Sammanfattning : Reduction of heat loss from the combustion chamber in an engine has great potential to decrease fuel consumption and CO2 emissions. Research on thermal barrier coatings (TBC) has been performed since the early eighties to address this potential. LÄS MER
5. On the Analysis of Energy Efficient Aircraft Engines
Sammanfattning : Aero engine performance analysis is highly multidimensional using various measures of component performance such as turbomachinery and mechanical efficiencies, and pressure loss coefficients. Using conventional performance analysis, relying on only the laws of thermodynamics, it is possible to understand how the performance parameters affect the component performance, but it is difficult to directly compare the magnitude of various loss sources. LÄS MER