Investigation of An Additively Manufactured Two-Phase Heat Exchanger with Built-In Thermal Storage

For thermal management systems designed and developed for spacecrafts, it is imperative to reduce the total mass of on-board thermal storage systems while minimizing temperature fluctuations upon dramatic changes of the environmental temperature within the orbiting stage. Since the outer space fails to have an atmosphere, heat can be dissipated to the space only through thermal radiators. By taking advantage of phase-change materials (PCMs) and integrating them into a passive two-phase heat exchanger (e.g., a vapor chamber), the size of thermal radiators can be shrunk based on the design for the average rather than the maximum heating power. To further contribute to addressing thermal challenges for space applications in the present study, a prototype of the proposed design of the two- phase heat exchanger is developed and manufactured additively using the Direct Metal Laser Sintering (DMLS) technique with Maraging Steel. The proposed prototype is a heat exchanger integrating PCMs into a vapor chamber via multiple thin-walled drawers of certain shape loaded with bulk phase-change materials. Contingent upon the PCM melting point and the heat sink temperature, the fabricated heat exchanger may operate either as a heat capacitor or a normal heat exchanger with heat storage capability, reflecting two operation modes which can be in service for landing/launching stage or orbit stage of spacecrafts, respectively. In this study, an improved design of the PCM- integrated heat exchanger is introduced and compared with the original design developed in our earlier study. The new design aims to achieve an improvement in the system mass ratio (the mass ratio of PCM inventory to the entire heat exchanger) and thermal storage capability within the heat exchanger mode of operation.