Thermal conductivity of rigid foam insulations for aerospace vehicles

The present work describes measurements of the effective thermal conductivity of NCFI 24-124 foam, a spray-on foam insulation used formerly on the Space Shuttle external fuel tank. A novel apparatus to measure the effective thermal conductivity of rigid foam at temperatures ranging from 20 K to 300 K was developed and used to study three samples of NCFI 24-124 foam insulation. In preparation for measurement, the foam samples were either treated with a uniquely designed moisture absorption apparatus or different residual gases to study their impact on the effective thermal conductivity of the foam. The resulting data are compared to other measurements and mathematical models reported in the literature.

► The thermal conductivity of spray-on foam insulation for aerospace vehicles is measured.
► The thermal conductivity ranges from 0.002 W/m K at 20 K to 0.1 W/m K at 300 K.
► Residual gas and condensation are significant factors in thermal conductivity at low temperature.