a two-input two-output closed heater, which is a shell-and-tube-type recuperators in which the feedwater temperature increases as the extracted stream condenses on the outside of the tubes carrying the feedwater
(Forall (?Self ?Time) (<=> (Active ?Time 2-2-Closed-Feedwater-Heater ?Self) (And (2-2-Closed-Feedwater-Heater ?Self) (Active ?Time 2-2-Port-Thermal-Component ?Self) (Active ?Time Heat-Exchanger ?Self))))