BuildingSystems.Fluid.Actuators.Valves.ThreeWayTable

# .BuildingSystems.Fluid.Actuators.Valves.ThreeWayTable

Three way valve with table-specified characteristics

## Information

Three way valve with table-specified opening characteristics. A separate characteristic for each flow path is used.

Each flow path uses an instance of the model BuildingSystems.Fluid.Actuators.Valves.TwoWayTable. Therefore, this model needs to be parameterized the same way as BuildingSystems.Fluid.Actuators.Valves.TwoWayTable. Specifically, the mass flow rate for the fully open valve is determined based on the value of the parameter `CvData`. For the different valve positions y ∈ [0, 1], this nominal flow rate is scaled by the values of the parameter `flowCharacteristics1` and `flowCharacteristics3`, respectively. These parameters declare a table of the form

y | 0 | ... | 1
φ | l | ... | 1

where l = Kv(y=0)/Kv(y=1) > 0 is the valve leakage. The first row is the valve opening, and the second row is the mass flow rate, relative to the mass flow rate of the fully open valve, under the assumption of a constant pressure difference across the valve. A suggested value for the valve leakage is l=0.0001. If l = 0, then this model will replace it with l = 10-8 for numerical reasons. For example, if a valve has Kv=0.5 [m3/h/bar1/2] and a linear opening characteristics and a valve leakage of l=0.0001, then one would set

     CvData=BuildingSystems.Fluid.Types.CvTypes.Kv
     Kv = 0.5
     flowCharacteristics1(y={0,1}, phi={0.0001,1})
     flowCharacteristics3(y={0,1}, phi={0.0001,1})

Note, however, that BuildingSystems.Fluid.Actuators.Valves.ThreeWayLinear provides a more efficient implementation for this simple case.

The parameters `flowCharacteristics1` and `flowCharacteristics3` must meet the following requirements, otherwise the model stops with an error:

- Their arrays `y` and `phi` must be strictly monotonic increasing.
- The first value must satisfy `y[1]=0`, and `phi[1]` must be equal to the leakage flow rate, which must be bigger than zero. Otherwise, a default value of `1E-8` is used.
- The last values must satisfy `y[end]=1` and `phi[end]=1`.

This model is based on the partial valve model BuildingSystems.Fluid.Actuators.BaseClasses.PartialTwoWayValve. Check this model for more information, such as the regularization near the origin.

For an example that specifies an opening characteristics, see BuildingSystems.Fluid.Actuators.Valves.Examples.TwoWayValveTable.

## Revisions

- March 7, 2022, by Michael Wetter:
  Set `final massDynamics=energyDynamics`.
  This is for #1542.
- June 10, 2021, by Michael Wetter:
  Changed implementation of the filter and changed the parameter `order` to a constant as most users need not change this value.
  This is for #1498.
- November 28, 2019, by Michael Wetter:
  Revised implementation.
- November 15, 2019, by Alexander Kümpel:
  First implementation.

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