Total energy exchange medium and method of making the same

Abstract

Total heat energy exchange medium incorporated in an energy exchange device for transferring heat and moisture between two airstreams in an air supply system. The exchange medium is aluminum having a coating of hydrated calcium and aluminum oxides or hydroxides to render its heat transfer surfaces capable of exchanging latent as well as sensible heat energy. The coating is formed by exposing precleaned aluminum to a heated, preferably boiling solution of water-soluble calcium and aluminum compounds, preferably equal parts of hydrated calcium nitrate and hydrated aluminum nitrate, the pH of the solution having been brought to the range of from about 7 to 11, preferably pH=8 to 9, by adding sodium hydroxide which produces in the solution a mixed gelatinous precipitate of hydrated calcium and aluminum oxides and hydroxides. When the aluminum is exposed to this solution, as by immersing the aluminum therein, further reaction with the aluminum forms a conversion coating portion comprising an hydrated calcium aluminate immediately next to the aluminum surface which, in turn, secures the insoluble gel-like precipitate coating portion of hydrated calcium and aluminum oxides or hydroxides thereto.

Dependencies are inferred from the claim text.