Assessment of the Use of Nanofluids in Spacecraft Active Thermal Control Systems

The addition of metallic nanoparticles to a base heat transfer fluid can substantially increase its thermal conductivity. These nanofluids have been shown to have advantages in some heat transport systems. Their thermal properties allow the system volumetric flow rate to be reduced, thus reducing the required pumping power. Nanofluids have been suggested as working fluids in spacecraft Active Thermal Control Systems (ATCSs). However, spacecraft ATCSs are unique in that they have stringent temperature control requirements and use specialized heat transfer devices. In the present work, a parametric study was performed to assess the use of nanofluids in spacecraft ATCSs. The tabulated thermophysical properties of various nanofluids, the design requirements of NASA’s Orion ATCS and the performance parameters of its key heat transfer components were used to assess the effects of the incorporation of nanofluids. The study shows that the unique system and component-level design parameters of spacecraft ATCSs do not lend themselves to the use of nanofluids. The addition of nanoparticles to typical spacecraft internal flow loop working fluids actually results in an increase in either the system mass or the required pumping power, the opposite of the hoped-for effect. The intermediate results obtained in the study also suggest that that the addition of nanoparticles to an external ATCS loop is not likely to result in a significant overall system benefit.