modelFanCoil2PipeCooling
Model of a sensible only two-pipe fan coil unit for cooling,
computing a required chilled water mass flow rate
Extends from Buildings.DHC.Loads.BaseClasses.PartialTerminalUnit.
Information
This is a simplified model of a two-pipe fan coil unit for cooling. It is intended to be used
- in a case where the room thermal loads are provided as time series: it therefore takes the load as an input, and
- in conjunction with Buildings.DHC.Loads.BaseClasses.FlowDistribution: it therefore computes the water mass flow rate required to meet the load.
For the sake of computational performance, a PI controller is used instead of an inverse model of the heat exchanger to assess the required water mass flow rate. The controller output signal is mapped linearly to both,
- the water mass flow rate, from zero to its nominal value, and
- the air mass flow rate, from zero to its nominal value.
The controller tracks the load while the impact of an unmet load on the room air temperature is assessed with Buildings.DHC.Loads.BaseClasses.SimpleRoomODE.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Real | k | 1 | Gain of controller |
| Modelica.Units.SI.Time | Ti | 10 | Time constant of integrator block |
| hexConfiguration | hexConCoo | hexConfiguration.CounterFlow | Cooling heat exchanger configuration |
| Nominal condition | |||
| Modelica.Units.SI.PressureDifference | dpLoa_nominal | 250 | Load side pressure drop |
| Modelica.Units.SI.HeatFlowRate | QEnv_flow_nominal | Nominal envelope heat loss (for room air temperature prediction) | |
| Modelica.Units.SI.TemperatureDifference | dTEnv_nominal | 15 | Design temperature difference at which envelope heat loss is QEnv_flow_nominal |
| Configuration | |||
| Boolean | have_speVar | true | Set to true for a variable speed fan (otherwise fan is always on) |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Buildings.Controls.OBC.CDL.Reals.PIDWithReset | con | PI controller | |
| Buildings.Fluid.Movers.FlowControlled_m_flow | fan | Fan | |
| Fluid.HeatExchangers.WetCoilEffectivenessNTU | hexWetNtu | Cooling coil | |
| Buildings.Controls.OBC.CDL.Reals.MultiplyByParameter | gaiMasFlo | Scale water flow rate | |
| Modelica.Blocks.Sources.RealExpression | Q_flowCoo | ||
| Buildings.Controls.OBC.CDL.Reals.MultiplyByParameter | gaiFloNom2 | Scale air flow rate | |
| Fluid.Sources.Boundary_pT | sinAir | Sink for supply air | |
| Fluid.Sources.Boundary_pT | retAir | Source for return air | |
| Buildings.DHC.Loads.BaseClasses.SimpleRoomODE | TLoaODE | Predicted room air temperature | |
| Buildings.Controls.OBC.CDL.Reals.MultiplyByParameter | gaiHeaFlo | ||
| Buildings.Controls.OBC.CDL.Reals.MultiplyByParameter | gaiHeaFlo1 | ||
| Buildings.Controls.OBC.CDL.Reals.GreaterThreshold | greThr | Reset when demand rises from zero | |
| Fluid.FixedResistances.PressureDrop | resLoa | Load side pressure drop | |
| Buildings.Controls.OBC.CDL.Reals.Sources.Constant | one | One constant | |
| Buildings.Controls.OBC.CDL.Logical.Sources.Constant | con1 | ||
| Buildings.Controls.OBC.CDL.Reals.Switch | swi | Logical switch |
Revisions
-
February 21, 2020, by Antoine Gautier:
First implementation.