Development of a microfabricated silicon motor-driven compression system

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2000.Includes bibliographical references (p. 237-243).by Luc G. Fréchette.Ph.D

IMECE2005-81435 DEMONSTRATION AND CHARACTERIZATION OF A MULTI-STAGE SILICON MICROTURBINE

Abstract -This paper presents the experimental testing and characterization of a microscale radial outflow turbine with four concentric stages. The device is a five layer structure composed of shallow and deep reactive ion etched silicon wafers and an ultrasonically drilled Pyrex glass wafer that are assembled using anodic and fusion bonding techniques. They enclose a 4mm diameter rotor that was spun up to 330,000 rpm and produced roughly 0.1W of mechanical power from each stage totaling 0.38W with 0.75 atm differential pressure across the microturbine. Modeling of the turbine based on a mean line analysis with loss correlations extracted from CFD suggests a turbine isentropic efficiency of 35% and Re=266 at the maximum speed. The pressure distribution across the blades rows was measured and showed close agreement with the calculation results. Using the model, the microturbine is predicted to produce 3.2 watts with an isentropic efficiency of 63% at a rotor speed of 1.1 million rpm

Sensors Connecting the Cyber and Physical Worlds

International audienc

Implications of stability modeling for high-speed axial compressor design

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1997.Includes bibliographical references (leaves 166-170).by Luc G. Fréchette.M.S

IMECE2009-11579 CONTROLLED FLOW EVAPORATION IN COMPLEX MICROCHANNELS WITH NON- UNIFORM WALL TEMPERATURES

ABSTRACT This paper presents an experimental study of flow evaporation in non-uniform microchannels, demonstrating the ability to provide a stable flow of evaporated fluid for energy conversion and chip cooling applications. Two mechanisms are proposed to stabilize the internal flow evaporation. The first mechanism is to establish a temperature gradient along the channel to separate the room temperature inlet fluid from the steam exit flow. The second mechanism is to change the direction of the surface tension forces acting on the meniscus to fix its position along the channel. To achieve this, shaped channels are formed of contractions and expansions with varied wall angles. The device consists of a silicon wafer with through-etched complex microchannels, that is anodically bonded to a glass wafer on each side. Inlet and exit holes for the fluid are machined in the glass wafers. Water is forced through the chip while it is heated on the exit side of the three layer chip. The qualitative nature of the two-phase flow along the shaped channels is observed through the glass cover wafer, for different flow rates and wall temperatures. The temperature gradient achieved with different thickness of channel walls shows agreement with the modeling results. Also, the benefit of having multiple expansions in the channels was demonstrated. By using these two mechanisms the onset of water evaporation was fixed along the channel. This will lead to the development of adequate two-phase flow micro heat exchangers

Paper-based water management system for microfabricated packageless fuel cell

International audienc

Thermal and Structural Considerations in the Design of a Rankine Vapor Microturbine

Abstract: This paper reports a global modeling and design approach to design a Rankine Microturbine for micro power generation from waste heat. The primary performance metrics and design challenges were identified, and models were developed for conjugate thermal and structural analyses. The results of these models, and their implications for size, shape, and materials selection, are presented. The need for low conductivity materials for the rotor and static structure of the microturbine is highlighted and a viable device configuration is proposed for elevated temperature operation