Heat transfer medium for rotary heat transferrers

A rotatable heat exchanger wheel comprising a cylindrical, open-ended casing supported for rotation,

• a plurality of wedge-shaped segments of heat exchange medium disposed in and carried by said casing, said heat exchange medium comprising
• alternate planar and corrugated layers of a thin, fiber-reinforced, heat-curable, organic resinous material containing at least 50 weight % of the organic resin and bonded together at their points of contact to form a self-supporting, water-proof structure including uniformly-spaced, tubular flow passages extending axially from one side of the structure to the other in parallel relationship to each other and parallel to the rotational axis of said casing, the portions of said structure defining said flow passages being substantially non-absorbent relative to water, said fiber-reinforced, resinous material comprising sheets of a fibrous material substantially saturated with a phenolic or a melamine resin;
• and
• a film coating the surface of said flow passages exposed to air flow, said film being applied as an aqueous coating solution containing about 15-20 weight % of lithium chloride and a sufficient amount of a water-soluble, wetting agent to provide a continuous film of said solution on said surfaces.

A method for making a heat transfer medium adapted for use in a rotary air-to-air heat transferrer comprising the step of

• impregnating thin sheets of a fibrous material with at least 50 weight % of a heat-curable, organic resin;
• corrugating some of the resin-impregnated sheets and leaving others planar;
• interleaving alternate planar and corrugated resin-impregnated sheets;
• compressing the interleaved sheets together to form a corrugated structure;
• heating the corrugated structure, while maintaining pressure thereon, to an elevated temperature to cure the resin impregnate to a hardened state and thereby form a self-supporting, water-proof structure including a plurality of uniformly-spaced, tubular flow passages having interior surfaces which are substantially non-absorbent relative to water;
• and
• coating the interior surfaces of the flow passages with an aqueous coating solution containing a water-soluble hygroscopic material for exchanging moisture flowing in contact therewith and a sufficient amount of a water-soluble wetting agent to provide a continuous film of the coating solution on the flow passage surfaces.