Development of MEMS Boiler Tank for Miniature ORC Power Generation System

This paper proposed a silicon boiler tank for a miniature organic Rankine cycle power generation system. Demand for miniature power generation systems is increasing with the spread of loT (Internet of Things) devices. Energy harvesting technology is attracting attention as a power generation system that can replace conventional batteries, but the amount of power generated is low. Therefore, we focused on the miniaturization of the organic Rankine cycle (ORC), which can utilize low-temperature waste heat and generates power through electromagnetic induction. The target ORC power generation system is a heat cycle that utilizes waste heat below 473 K on a centimeter-scale. The boiler tank to be developed has both boiler and storage functions in the cycle. By using MEMS (Micro Electro Mechanical Systems) technology, a silicon microfabrication technology, the millimeter-scale boiler tank of 8.0 mm, 10 mm, and 4.5 mm in height will be realized. The developed MEMS boiler tank was filled with low-boiling-point material and evaluated through heating and turbine rotation experiments. In the heating experiment, phase change of the internal fluid was confirmed. In addition, it became clear that the relationship between the direction of heating, the flow path, and the location of the storage section was important. In the rotation experiment, the developed MEMS turbine was connected to the boiler tank and observed. The rotational speed of 2631.6 rpm was obtained when the boiler tank was heated at 373K. These results suggest that the silicon boiler tank shows expected as an element of a small ORC power generation system.