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Prof. L. Fréchette
Université de SHerbrooke
Member of ReSMiQ since 2010
Luc G. Fréchette received the Ph.D. in Energy Conversion from the Massachusetts Institute of Technology, Cambridge, USA. He was a Faculty Member at Columbia University, New York, USA. He is currently Professor in the Department of Mechanical Engineering in the of the Université de Sherbrooke, QC, Canada. He held the Canada Research Chair in Microfluidics and Power MEMS. His expertise is in microengineering of miniature systems for energy conversion, such as heat engines (microturbines), micro fuel cells, cooling microsystems, and vibration energy-harvesting MEMS. He is the author or co-author of 4 patents, 10 book chapters, and several papers in journals and scientific conferences. Several of them have been awarded as the best conference paper. Dr. Fréchette is a member of the American Society of Mechanical Engineers (ASME)and IEEE. More information
Below is a selection of publications in recent years followed by representative work.
Thermal management
1. Azarkish, H., Behzadmehr, A., Fanaei Sheikholeslami, T., Hosseini Sarvari, S. M. Frechette, L., “A novel silicon bi-textured micro-pillar array to provide fully evaporated steam for a micro Rankine cycle application”, J. Phys. D: Appl Phys, vol 47, 475301, 2014.
2. Salimshirazy, M. and Fréchette, L.G., “Effect of Meniscus Recession on the Effective Pore Radius and Capillary Pumping of Copper Metal Foams”, J. Electron. Packag., 2014.
3. Newby, P., Canut, B., Bluet, J.-M., Gomès, S., Isaiev, M., Burbelo, R., Termentzidis, K., Chantrenne, P., Fréchette, L.G., Lysenko, V., “Amorphisation and reduction of thermal conductivity in porous silicon by irradiation with swift heavy ions”, J. Appl. Phys. vol. 114, no. 014903, 2013.
4. Collin, L.-M., Arenas, O., Arès, R., Fréchette, L.G., “Thermal Resistance and Heat Spreading Characterization Platform for Concentrated Photovoltaic Cell Receivers”, IEEE Trans. Components, Packaging & Manufac. Tech., vol. 3, no. 10, p. 1673-1682, 2013.
Power MEMS
5. Dompierre, A., Vengallatore, S., Fréchette, L.G., “Piezoelectric Vibration Energy Harvesters: Modeling, Design, Limits and Benchmarking” in Energy Harvesting with Functional Materials and Microsystems, Editors M. Bhaskaran, S. Sriram & K. Iniewski, CRC Press, Taylor & Francis, 289 pp., 2013.
6. Formosa, F., Fréchette, L.G., “Scaling laws for free piston Stirling engine design: Benefits and challenges of miniaturization”, Energy, vol. 57, p. 796-808, 2013.
7. Mirshekari, G., Brouillette, M., Fréchette, L.G., “Through silicon vias integratable with thin-film piezoelectric structures”, Int’l J. of Nanoscience, vol. 11, no. 4, 2012.
8. Hamel, S., and Fréchette, L.G., “Critical importance of humidification of the anode in miniature air-breathing polymer electrolyte membrane fuel cells,” J. Power Sources, vol. 196, pp. 6242-6248, 2011.
9. Lee, C., Liamini, M., Fréchette, L. G., “A Silicon Microturbopump for a Rankine-Cycle Power Generation Microsystem – Part II: Fabrication and Characterization,” J. Microelectromech. Syst., vol. 20, 01/31, 2011.
A Silicon Micro-Turbopump for a Rankine-Cycle Power Generation Microsystem – Part II: Fabrication and Characterization
In Part I of this two-part article, the design approach for a micro-turbopump was presented. This second part describes the fabrication and experimental characterization of the demo micro-turbopump device, which includes hydrostatic bearings, a spiral groove viscous pump and a multistage microturbine. The device is composed of five wafers: one glass wafer, one silicon-on-insulator (SOI) wafer, and three silicon wafers. The silicon and SOI wafers are patterned using shallow and deep reactive ion etching (total of 14 masks), while the Pyrex glass wafer was ultrasonically drilled. Anodic bonding, fusion bonding and manual assembly with alignment structures were then used to complete the device and enclose the 4 mm diameter rotor. The approach allowed the microfabrication of unique interdigitated blade rows in the microturbine and interchangeable parts for flexible testing. After completion of the device, bearings were first tested in static and dynamic conditions. Then, the turbine was characterized with compressed air only, and spun up to 330,000 RPM producing 0.38 W of mechanical power. The pump performance map was also completely characterized for speeds up to 120,000 RPM showing a maximum pump flow rate of 9 mg/s and maximum pressure rise of 240 kPa. In a turbopump system performance test using compressed air to the turbine and water in the pump, the rotor was spun up to 116,000 RPM, which corresponds to 25 m/s in tip speed. At this condition, the turbine produced 0.073 W of mechanical power with 41kPa of differential pressure and 24 mg/s of flow rate, and the pump pressurized water by 88 kPa with a flow rate of 4 mg/s maintaining constant efficiency of 7.2 % over the operating range. Out of the total power produced by the turbine, 10 % was consumed by the viscous pump, while the rest was dissipated by other components through viscous drag. The system level predictions by models introduced in Part I also match the measured performance, suggesting that a valid design basis has been established for this type of rotating micromachine.
Fig. 1. Cross-section of 5-wafer stack micro-turbopump device, showing the main components, and isometric SEM of the rotor.