Bilateral Sandwich Thermal Isolation: Pomegranate and Dental Layer Geometry as Templates for Dual-Boundary Heat Transfer

Standard triple-fluid heat exchangers route three fluids at three distinct temperatures through concentric or parallel channels, achieving heat transfer between adjacent fluid pairs. This note proposes a different thermal logic: bilateral sandwich isolation, in which a target fluid occupies a middle layer flanked on both sides by a second fluid at the same temperature, so the target fluid is simultaneously heated or cooled from both boundaries at once without increasing device footprint. Two biological structures are identified as natural geometric templates for this arrangement: the pomegranate (epicarp-mesocarp-aril layering) and the tooth (enamel-dentin-pulp layering). In both cases, the middle biological layer connects structurally to both the inner and outer layers through distinct geometric channels, providing a ready-made dual-boundary fluid routing template. The novel contribution is not the use of biological geometry per se, but the bilateral sandwich thermal logic it enables: two fluids, two temperatures, dual-boundary heat transfer on the sandwiched fluid from both sides simultaneously. No prior art has been identified for this specific thermal arrangement or for pomegranate or dental layer geometry as heat exchanger fabrication templates.