Microstructure Devices for efficient Evaporation of Liquids

Different microstructure devices used for evaporation and generation of steam are described in this publication. Starting with simple liquid-heated devices, electrically powered devices containing micro channels as well as non-channel microstructures are shown. An electrically powered device for optical inspection of the microstructures and the processes inside has been designed and manufactured. Exchangeable metallic micro channel array foils as well as an optical inspection of the evaporation process by high-speed videography have been integrated into this test system. Fundamental research onto the influences of the inlet flow distribution system geometry and the geometry and dimensions of the micro channels have been performed. A pre-calculation sheet for micro evaporators with micro channel arrays based on the measurement of inlet parameters for the liquid only was generated. While evaporation of liquids in micro channel devices of more or less conventional design is possible, it is, in many cases, not feasible to generate superheated steam due to certain boundary conditions. Therefore a new design was proposed to obtain complete evaporation and steam superheating, consisting of an arrangement of numerous circular blanks with connecting nozzles. A maximum power density of 1400 kW · m−2 has been transferred while water could be completely evaporated and the generated steam superheated.