functionNTU_counterCurrent
Extends from Modelica.Icons.Function (Icon for functions).
Information
This functions computes the Number of Transfer Units (NTU) of an exchanger for counter current flows. The function is mainly used to supply to the solver the inverse function of the effectiveness.
When both flows have the same thermal capacity ( Cr = 1 ), a zero division occurs. However, an analytical relation is existing for this specific case. To get around the problem, when the value of Cr comes closer to one, a polynomial interpolation between the normal relation and the relation for Cr = 1 is performed.
A threshold is applied on the value of the effectiveness Eff = 0.999 to avoid numerical troubles such as zero divisions or infinite values.
Inputs
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.SIunits.Efficiency | Eff | Exchanger effectiveness | |
| Real | Cr | Ratio of thermal condutance |
Outputs
| Type | Name | Default | Description |
|---|---|---|---|
| Real | NTU | Number of transfer unit |