Abstract: A heat exchanger core of the plate and fin type having intrinsic capabilities of controlled resistance to heat flow. Objectives are achieved without a need for special materials and without departing from practiced structural and fabrication standards. A concept of resistance layers is used, with heat flux being controlled primarily in the resistance layers.

Abstract: A plate and fin type heat exchanger in which different flowing fluids are placed in a segregated heat transfer relation and in which provision is made to deny opportunity for a leaked fluid from one flow or circuit to join or mix with fluid of another flow or circuit. A concept of vented buffer zones is used to protect against leakage through plate elements and through defined joints between plate and spacer elements. The concept allows and provides for relatively simple manifolding and for fabrication to conventional configurations using for the most part standard easily manufactured parts.