Aluminium matrices are also available with an applied hygroscopic coating, and the use of this, or the use of porous synthetic fibre matrices, allows for the adsorption and release of water vapour, at moisture levels much lower than that normally required for condensation and latent heat transfer to occur.
During the automotive industry's interest in gas turbines for vehicle propulsion (around 1965), Chrysler invented a unique type of rotary heat exchanger[REF] that consisted of a rotary drum constructed from corrugated metal (similar in appearance to corrugated cardboard).