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 (Partial model for HVAC terminal unit).
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 |
| Assumptions | |||
| Boolean | allowFlowReversal (from PartialTerminalUnit) | false | Set to true to allow flow reversal in building distribution system |
| Boolean | allowFlowReversalLoa (from PartialTerminalUnit) | true | Set to true to allow flow reversal on the load side |
| Scaling | |||
| Real | facMul (from PartialTerminalUnit) | 1 | Multiplier factor |
| Real | facMulZon (from PartialTerminalUnit) | 1 | Zone multiplier factor |
| Configuration | |||
| Boolean | have_heaWat (from PartialTerminalUnit) | false | Set to true if the system uses heating water |
| Boolean | have_chiWat (from PartialTerminalUnit) | false | Set to true if the system uses chilled water |
| Boolean | have_chaOve (from PartialTerminalUnit) | false | Set to true if the chilled water based heat exchanger operates in change-over |
| Boolean | have_eleHea (from PartialTerminalUnit) | false | Set to true if the system has electric heating system |
| Boolean | have_eleCoo (from PartialTerminalUnit) | false | Set to true if the system has electric cooling system |
| Boolean | have_heaPor (from PartialTerminalUnit) | false | Set to true for heat ports on the load side |
| Boolean | have_fluPor (from PartialTerminalUnit) | false | Set to true for fluid ports on the load side |
| Boolean | have_TSen (from PartialTerminalUnit) | false | Set to true for measured temperature as an input |
| Boolean | have_QReq_flow (from PartialTerminalUnit) | false | Set to true for required heat flow rate as an input |
| Boolean | have_weaBus (from PartialTerminalUnit) | false | Set to true to use a weather bus |
| Boolean | have_fan (from PartialTerminalUnit) | false | Set to true if fan power is computed |
| Boolean | have_pum (from PartialTerminalUnit) | false | Set to true if pump power is computed |
| Boolean | have_speVar | true | Set to true for a variable speed fan (otherwise fan is always on) |
| Nominal condition | |||
| Modelica.Units.SI.HeatFlowRate | QHea_flow_nominal (from PartialTerminalUnit) | 0 | Nominal heating capacity (>=0) |
| Modelica.Units.SI.HeatFlowRate | QCoo_flow_nominal (from PartialTerminalUnit) | 0 | Nominal cooling capacity (<=0) |
| Modelica.Units.SI.MassFlowRate | mHeaWat_flow_nominal (from PartialTerminalUnit) | 0 | Heating water mass flow rate at nominal conditions |
| Modelica.Units.SI.MassFlowRate | mChiWat_flow_nominal (from PartialTerminalUnit) | 0 | Chilled water mass flow rate at nominal conditions |
| Modelica.Units.SI.MassFlowRate | mLoaHea_flow_nominal (from PartialTerminalUnit) | 0 | Load side mass flow rate at nominal conditions in heating mode |
| Modelica.Units.SI.MassFlowRate | mLoaCoo_flow_nominal (from PartialTerminalUnit) | 0 | Load side mass flow rate at nominal conditions in cooling mode |
| Modelica.Units.SI.Temperature | T_aHeaWat_nominal (from PartialTerminalUnit) | 273.15 + 60 | Heating water inlet temperature at nominal conditions |
| Modelica.Units.SI.Temperature | T_bHeaWat_nominal (from PartialTerminalUnit) | T_aHeaWat_nominal - 22.2 | Heating water outlet temperature at nominal conditions |
| Modelica.Units.SI.Temperature | T_aChiWat_nominal (from PartialTerminalUnit) | 273.15 + 7.2 | Chilled water inlet temperature at nominal conditions |
| Modelica.Units.SI.Temperature | T_bChiWat_nominal (from PartialTerminalUnit) | T_aChiWat_nominal + 5.6 | Chilled water outlet temperature at nominal conditions |
| Modelica.Units.SI.Temperature | T_aLoaHea_nominal (from PartialTerminalUnit) | 273.15 + 21.1 | Load side inlet temperature at nominal conditions in heating mode |
| Modelica.Units.SI.Temperature | T_aLoaCoo_nominal (from PartialTerminalUnit) | 273.15 + 26.7 | Load side inlet temperature at nominal conditions in cooling mode |
| Modelica.Units.SI.MassFraction | w_aLoaCoo_nominal (from PartialTerminalUnit) | 0.011 | Load side inlet humidity ratio at nominal conditions in cooling mode |
| 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 |
Connectors
Components
Revisions
-
February 21, 2020, by Antoine Gautier:
First implementation.