Ann: VHD Technology - Thermal Performance Breakthrough, page-69

Thank you for attaching the paper. it describes a novel VHD graphite Sorrell et al developed for harnessing thermal energy.

IA search tools I use could not find any information on the production method or process for making this novel material, nor could I find any relevant patent application.

like others, I am confused about the change of tack by GCM now reporting Diffusivity instead of following through as forecast in previous announcements. It causes uncertainty. E.G , I was concerned by a suggestion on HC that the reported thermal conductivity of 617 W/m·K should be substantially discounted to be consistent with the reported thermal diffusivity of 288 mm², an assertion based on an assumed specific heat capacity.

I am confident that all the characteristics as reported by GCM are consistent with each other, accepting minor discrepancies because of small variations between test results. My confidence is based on specific heat capacity data available on the internet for VHD graphite over a range densities, as reported by IA search tools I use. DYOR.
I have shared my findings with Spatula in an earlier post.