Functions for valve characteristics
Extends from Modelica.Icons.VariantsPackage (Icon for package containing variants).
Name | Description |
---|---|
baseFun | Base class for valve characteristics |
linear | Linear characteristic |
one | Constant characteristic |
quadratic | Quadratic characteristic |
equalPercentage | Equal percentage characteristic |
Base class for valve characteristics
This is a partial function that defines the interface of valve characteristics. The function returns "rc = valveCharacteristic" as function of the opening "pos" (in the range 0..1):
dp = (zeta_TOT/2) * rho * velocity^2 m_flow = sqrt(2/zeta_TOT) * Av * sqrt(rho * dp) m_flow = valveCharacteristic * Av * sqrt(rho * dp) m_flow = rc * Av * sqrt(rho * dp)
Extends from Modelica.Icons.Function (Icon for functions).
Name | Description |
---|---|
pos | Opening position (0: closed, 1: fully open) |
Name | Description |
---|---|
rc | Relative flow coefficient (per unit) |
Linear characteristic
Extends from baseFun (Base class for valve characteristics).
Name | Description |
---|---|
pos | Opening position (0: closed, 1: fully open) |
Name | Description |
---|---|
rc | Relative flow coefficient (per unit) |
Constant characteristic
Extends from baseFun (Base class for valve characteristics).
Name | Description |
---|---|
pos | Opening position (0: closed, 1: fully open) |
Name | Description |
---|---|
rc | Relative flow coefficient (per unit) |
Quadratic characteristic
Extends from baseFun (Base class for valve characteristics).
Name | Description |
---|---|
pos | Opening position (0: closed, 1: fully open) |
Name | Description |
---|---|
rc | Relative flow coefficient (per unit) |
Equal percentage characteristic
d(rc)/d(pos) = k d(pos).
The constant k is expressed in terms of the rangeability, i.e., the ratio between the maximum and the minimum useful flow coefficient:
rangeability = exp(k) = rc(1.0)/rc(0.0).
The theoretical characteristic has a non-zero opening when pos = 0; the implemented characteristic is modified so that the valve closes linearly when pos < delta.
Extends from baseFun (Base class for valve characteristics).
Name | Description |
---|---|
pos | Opening position (0: closed, 1: fully open) |
rangeability | Rangeability |
delta |
Name | Description |
---|---|
rc | Relative flow coefficient (per unit) |