This component assumes a uniform heat transfer coefficient gamma_nom*(w/wnom_ht)^alpha. When w/wnom_ht < beta the heat transfer coefficient stops decreasing, to avoid numerical problems at low flows.
If useAverageTemperature=false, the outlet fluid temperature of each volume is used to compute the heat transfer, otherwise the average temperature between inlet and outlet is used.
In the latter case, the temperature distribution is accurately predicted if N > NTU. However, non-physical temperature distributions and numerical problems can arise at low flows, when NTU increases. If adaptiveAverageTemperature=true, then the outlet temperature is used instead of the average one when w/wnom_ht < sigma. This leads to physically realistic temperature distributions and better numerical properties at low or zero flows.