Advanced gravity-film & double-helix heat exchangers (gfx+™ & dhx™)

Abstract: This invention teaches how to reduce the copper content of a commercially available, all-copper, double-wall-vented, coil & tube Gravity Film Heat Exchangers (“GFX”) developed for the GFX™ system of U.S. Pat. No. 4,619,311. For example, a GFX+™ equivalent of a residential Model G3-60 GFX can be made using 71% less copper. Such significant copper-savings, with comparable heat transfer coefficient (“U”), effectiveness and coil pressure drop, is achieved by improvements in innovations disclosed in Provisional Patent Application 60/709,889 (Filing date: Aug. 22, 2005). Unlike conventional, single and multi-coil GFX's currently produced by several manufacturers, the present invention enables the use of a variety of metal and/or plastic components to achieve either single or vented-double-wall construction and lower manufacturing costs. In fact, higher U-values can be achieved by increasing the potable-water pressure drop of a GFX+ equivalent of any coil & tube GFX. The present invention also teaches how to simultaneously optimize U-values & pressure drop[s] and means of introducing controlled turbulence & mixing. Such trade-offs cannot be achieved in a conventional GFX design having one or more coils wound singly or in parallel. It also teaches how to manufacture an improved version of the Double-Helix Heat Exchanger (“DHX”), which is also disclosed in said Provisional Patent Application 60/709,889. Unlike a GFX, which must be installed vertically for best effectiveness, a DHX can be operated in any orientation. For applications permitting higher pressure drop, a DHX can be designed with a much higher U-value than a comparable GFX or GFX+.