ALEXANDRIA, Va., June 6 -- United States Patent no. 12,281,818, issued on April 22.
"Wavy smoke tube structure of boiler" was invented by Sung-Hwan Choi (Seoul, South Korea).
According to the abstract* released by the U.S. Patent & Trademark Office: "The present disclosure relates to a wavy smoke tube structure of a boiler, which improves heat exchange efficiency of a smoke tube. The wavy smoke tube structure includes: a main body formed in a columnar shape and having a space therein; a plurality of first concave portions concavely formed along a first side portion in a longitudinal direction of the main body; a plurality of second concave portions concavely formed along a second side portion in the longitudinal direction of the main body...