(A) compact thermoelectric power generator heated by a catalytic reactor

Abstract

A compact thermoelectric power generating module heated by a catalytic reactor was developed as a small power source. Thermoelectric power generator is based on the Seebeck effect, and is a unique heat engine of which the working fluid is charge carriers. Merits of thermoelectric power generation in micro-system are absence of moving components and simple integration of components compared with heat engines. Catalytic reaction was also investigated as a heat source since it is stable in small reaction chamber. Preparation of catalyst and catalyst loading method were investigated to develop small heat source for thermoelectric generator. Two different types of micro catalytic reactors were designed and fabricated by MEMS fabrication technology with photosensitive glass wafers with different catalyst loading methods; packed bed type and thin film coating type. In a packed bed micro-reactor design, ceramic foam coated with platinum was the catalyst reactor bed. In the thin film coating type reactor, $Al_2O_3$ was used as catalyst supports and coated on the reaction chamber wall. Pt was coated on the $Al_2O_3$ thin film which was constructed on the wall. The preparation of $Al_2O_3$ coating solution and coating process was set up based on sol-gel method. Both reactors have a reaction chamber whose height was 1 mm and external volume of reactor was 1.8 cc. Both reactors were tested by hydrogen catalytic combustion. New catalyst support was required based on comparisons of reaction and fabrication process between two reactors. Nickel foam was suggested for use in a micro-catalytic reactor. $Al_2O_3$ was coated on nickel foam to increase the surface area using coating slurry prepared by a modified sol-gel process. Hydrogen catalytic combustion was carried out using $Pt/Al_2O_3$ coated nickel foam to confirm the reactivity as catalyst for combustion. Stable and complete combustion was observed with this catalyst. Thermoelectric power generation heated by catalytic ...