Abstract: A heat exchanger for transmitting thermal energy from one moving fluid to another of the type having a casing housing a thermal transfer core, the core including a folded sheet of heat conductive material defining adjacent fluid flow passages, the individual fold sections of the sheet having a multiplicity of pairs of dimples formed therein, each dimple pair including a raised dimple and an adjacent depressed dimple, the height of each dimple being substantially equal to one-half the width of the fluid flow passages. The dimple arrangement provides a relatively low pressure drop for the fluids passing through the fluid flow passages.

Abstract: Packaging systems for gas to gas counter-flow heat exchangers include locating individual heat exchanger modules adjacent to each other within a housing and providing a plurality of plenum chambers partially defined by suitably arranged baffles. The arrangements disclosed provide heat exchanger assemblies wherein the length of fluid flow path is significantly larger than at least one of the width dimensions of the flow stream thus minimizing entrance effects which tend to reduce the efficiency of the system.