ALEXANDRIA, Va., June 6 -- United States Patent no. 12,281,861, issued on April 22, was assigned to CARRIER Corp. (Palm Beach Gardens, Fla.).

"Methods of anodizing the internal surface of heat transfer tubes" was invented by Kerry Allahar (Syracuse, N.Y.), Jefferi J. Covington (Baldwinsville, N.Y.) and Matthew Patterson (East Syracuse, N.Y.).

According to the abstract* released by the U.S. Patent & Trademark Office: "Disclosed is a method of anodizing the interior surface of a heat transfer tube comprising placing a plurality of contact electrodes in electrical communication with, and along, an exterior surface of the heat transfer tube, inserting a counter electrode into an interior space of the heat transfer tube, providing an electroly...