The global trend for the machine design is energy efficiency and it can be achieved by using novel technologies with the improved design. In practice, this means lightweight structures, integrated functions of components and smaller size overall. In many cases the power-to-weight ratio is increased which engender new challenges for the design engineers. The thermal expansion of materials is well known phenomena, but when the operational temperature is high, up to 800 °C, the thermo-mechanical design of systems becomes indispensable and thermal effects sets many requirements for the design. Not only thermal expansion sets challenges, but also creep, heat loss and corrosion should be addressed. This thesis presents six cases where these challenges are studied. The first four investigates the Solid Oxide Fuel Cell (SOFC) systems. System design, theoretical conceptual studies and concept selection methods for thermal insulation are investigated first. Then research proceeds to interdisciplinary fields such as corrosion experiments at high temperature and component design. The fifth and sixth cases present medium and low temperature technologies, where the thermal design has a major effect to the system performance. The friction stir channeling is a novel manufacturing technology that enables the manufacturing of thermal management channels into structural components. The empirical calorimeter experiments were used to measure heat transfer properties and results were compared to results from the numerical analysis. During the entire design and research work, the computer aided design tools and numerical calculation methods were used. Especially the sixth case analyses the dimensional errors caused by gravity and thermal expansion during the manufacturing and inspection process. As a result, the system design for the high temperature applications has progressed, and lower cost and increased system lifetime can be achieved. Novel thermal insulation method, component supports and components were designed and tested offering new possibilities for new energy systems. The results from the friction stir channel experiments prove that this new technology is suitable for built-in thermal management of the structural components. Furthermore, with the detailed numerical analysis of the end plate of the wind power gearbox, the manufacturing and inspection procedures achieve higher accuracy, thus leading to products with higher quality. As a conclusion, thermo-mechanical design of new energy systems has been studied and improved. However, further investigations will benefit from the swiftly developing calculation power of computers and enhanced software making the system design more straightforward. Nonetheless, there are still many challenges remaining, especially in the field of materials for the high operational temperatures.
|Translated title of the contribution||Uusien energiantuotantojärjestelmien mekaniikan ja lämmönhallinnan kehittäminen|
|Publication status||Published - 2017|
|MoE publication type||G4 Doctoral dissertation (monograph)|
- thermal expansion
- fuel cell
- wind power
- quality control