High Energy Density Micro-actuation based on Gas Generation by means of Catalysis of Liquid Chemical Energy

This thesis describes the research for, and the assessment of a new type of energy source and actuation, applicable to a Micro Aerial Vehicle (MAV). From the preliminary study resulted a promising energy source: hydrogen peroxide (H2O2) which is combined with the basic principle of the internal combustion engine for conversion to mechanical energy. The combination of this energy carrier and the conversion into mechanical energy is achieved by applying catalytic decomposition. The focus of this thesis is to assess whether a catalytic driven process using H2O2, is suitable for functioning as: means of energy conversion at micro scale. To verify the potential of the proposed combination of principles, experiments are performed. A number of different catalysts are prepared and tested in an experimental setup which monitors process behavior, speed and temperature. The process behavior is recorded by a high speed camera, pressures are measured simultaneously by means of pressure sensors and the temperature is measured using a small thermocouple. Test results show that the use of manganese oxide deposited using acetate as precursor, leads to the fastest processes and highest pressures. Reaction times as low as 70ms have been recorded, resulting in pressure peaks exceeding 13kPa which is higher than predictions. The static pressures do correspond with theory and consist of only the pressure caused by the generation of oxygen. The water vapor generated during the reaction quickly condensates as the gas mixture cools down, leaving behind only oxygen gas at room temperature. This indicates an advantage of using a cyclic process, using the short term high pressure. The temperatures occurring during the decomposition process of H2O2, are around the 100oC due to the production of water vapor. This temperature is not exceeded since too little energy is present in the used 30% weight to weight (w/w) concentration of H2O2, as predicted. From high speed camera recordings the process behavior is monitored and shows that a catalyst deposited on a blank ceramic tile without the use of a porous zirconia layer, comes loose from the tile during reaction. This allows for an increased reaction surface which corresponds to shorter reaction times. Based on the theory and the tests performed, flight duration for 1ml of H2O2, will be around 17-57 minutes for respectively 30-98% w/w concentrated H2O2. Regarding the use of the proposed means of energy conversion from liquid chemical energy into mechanical motion, a number of sub system components are proposed, for smart system design. At the chemical side, further developments lie in the characterization, miniaturization and optimization of the catalytic process for use at micro scale. At the mechanical side, developments lie in the actuation system design which operates on the gas formation driven by catalysis of H2O2. Smart system design has to be applied in order to obtain a sufficiently high energy density regarding weight while still allowing for sufficient system endurance and fabrication.BioMechanical EngineeringMechanical, Maritime and Materials Engineerin