UC Riverside

Producing enough drinkable water for long-term deep space missions is a great challenge. A small scale photocatalytic microreactor with nano-porous TiO2 coated titanium micropillar arrays is designed to solve the problem. The COMSOL Multiphysics is used to simulate several parts of the microreactor. The first objective is to model the tree-branched bifurcating flow distribution design and the diamond-shaped flow distribution design, then subsequently compare the pressure drop between the two. Based on simulation results, the tree-branched bifurcating flow distribution design can provide a longer residence time for the waste liquid due to the lower pressure drop inside the distribution channels which increases the photocatalytic efficiency. However, the extension of channels increases the area that this design takes up, thus reducing the size of the reactor chamber. The diamond-shaped distributor is more compact in size because of its geometry which gives more space to the reactor chamber. However, the pressure drop in the microreactor increases about 256% compared to the pressure drop of tree-branched bifurcating distributor which reduces the residence time. The second objective is to simulate photon interaction among micropillars and light intensity along the micropillars under UV irradiation, then find how the micropillar height influences the light intensity on the micropillar. According to simulation, light intensity on the 50 µm height micropillar creates an ideal photocatalytic efficiency. For the 100 µm height micropillar, 50% of the micropillar has low light intensity which causes low photocatalytic efficiency. And 66.67% of the 150 µm height micropillar’s surface has low light intensity. As the height of the micropillar increases, a larger percentage of the micropillar’s surface will have low light intensity. This leads to a decrease in photocatalytic efficiency.