coaxial heat exchangers are structured by twisted heat exchanger tube to provide more heat transfer area for a given length of tubing and create. it have the flowing advantages up to 350% enhancement in btu/hr heat transfer increased internal burst pressure and compression strength plain tube ends for simply connection lower cost compared to other specialized tubing heat exchanger tube materials: copper, cupronickel and titanium applications: fresh water condensers & evaporators, salt water condensers & evaporators, sea water condensers & evaporators, pool water condensers & evaporators. over shapes: round, rectangle, ellipse and customized shapes