ADDITIVE MANUFACTURING OF HIGH TEMPERATURE CERAMIC HEAT EXCHANGER

With increasing space exploration over recent years, there is growing interest in the reusability of launch vehicles. Re-entry vehicles experience ablation on the surface due to aerothermal heating imposed on them during the atmospheric entry, and the temperatures at the leading edge can be as high as above 2000 °C. These vehicles required a heat regulator to ensure the surface temperatures are within operating tolerances and reduce the maintenance needs upon return. Ceramics are known for its stable properties and high heat resistivity and the primary material selected is a commercial alumina resin. The heat exchanger proposed forms a honeycomb structure of consecutive matrix panels aligning to one another in a stairway pattern. Due to the complexity and capability of scaling, the structure was additively printed through polymerization of the ceramic resin utilizing digital light processing (DLP) and then undergoing polymerization to form the final structure. The part was sintered at 1510 °C in a single firing schedule spanning approximately 86 hours. It was measured that there is a horizontal shrinkage of around 19 % after furnace treatment and 93% relative density. The study presents the design and geometry of ceramic heat exchanger, shrinkage of the part after pyrolysis, material characterization, and a simulation and analysis of heat transfer and circulation of cooling fluid to maintain temperatures. The simulation study was conducted using COMSOL Multiphysics where the diffusing of heat through the solid ceramic panel and a cooling fluid was introduced.