ALEXANDRIA, Va., March 17 -- United States Patent no. 12,578,121, issued on March 17, was assigned to Rinnai Corp. (Aichi, Japan).
"Heat exchanger" was invented by Hidenao Negi (Aichi, Japan) and Toshimitsu Nagasaka (Aichi, Japan).
According to the abstract* released by the U.S. Patent & Trademark Office: "In a heat exchanger, a respective meander passage in each of two stages connecting heat absorbing tubes divided into the two stages and arranged in a flow direction of a combustion gas in an inside of a casing from one side to the other side in a Y-axis direction is constituted, and a heat absorbing tube at an upstream end of the meander passage in a first stage at an upstream side of the flow direction of the combustion gas and a heat ...