icon:

Simplest heat exhchanger model which transfers heat from one fluid flow to another. Sum of heat and enthalpy is conserved.

estimation of change of fluid states (enthalpy, temperature, internal energy) with given HX effectiveness.
rough heat exchanger sizing/scaling if combinated with NTU-effectiveness equation outside of this component.

calculates maximum potential heat to be exchanged (Q_flow_max) from heat capacities of inlets.
calculates actual heat exchanged from maxmum potential heat exchanged and given effectiveness.
outlet states of fluids are calculated by heat conservation equations.
either of Medium 1 or 2 can be hot/cold side. Which side is hot/cold is determined automatically.
either of port 1 or 2 can be inlet/outlet side. Which side is inlet/outlet is determined automatically.

heat capacities are calculated referring to only INLET state. Maximum potential heat exchanged is NOT true if specific heat capacity varies over temerature or if phase change is included. (same definition of maximum potential heat exchanged as ordinary heat transfer textbook)
heat leak is NOT taken into account.
heat soak, or thermal mass, is NOT taken into account.
heat conduction of wall is NOT taken into account.
volume effect, or time delay in mass and enthalpy flow, is NOT taken into account.
2 fluids never mix.
pressure loss does NOT occur.