A.6.0:5.5 - PrincipleFrame: heat-flow balance

A thermal-modeling team writes a PrincipleFrame stating that net heat flow across a selected system boundary must balance the change in stored energy. The frame names the observable distinction between inward and outward heat flow at that boundary. It cites separately governed heat-flow characteristics, units, the selected CHR:ReferencePlane, and the measurement declaration needed to check that distinction; its Applicability names the modeled systems and conditions for which the balance claim is made.

A comparison result may show that the residual is below the chosen tolerance. The comparator and tolerance remain under their direct comparison and measurement patterns; operation admission remains under A.6.1, and a gate-passage verdict remains under A.21/C.11. If a laboratory measurement sense is proposed for use in a plant-model sense, resolve both exact F.17 local senses and apply F.9. Cite a Bridge only when its predicate obtains; state the bounded use and any preservation or loss of sign convention, unit, and boundary interpretation separately.

Practical payoff: the physical principle remains reusable while the measurement setup, comparator, run decision, and cross-scheme transport can change or fail independently.