modelAirRearDoorHexPassive
Extends from Modelica.Icons.Example (Icon for runnable examples).
Information
Example model of an air-cooled IT rack with a passive rear door heat exchanger.
The room inlet air temperature is set to 30°C. The air-cooled rack raises the air temperature around 11.7 K, so the air entering the rear door heat exchanger is at approximately 41.7°C. The rear door heat exchanger is passive, i.e., it does not have fans. Due to its air-side flow resistance, the air flow rate through the rack is slightly lower than when no rear door heat exchanger is present, leading to a higher rack outlet temperature, which is upstream of the rear door heat exchanger.
Water at 25°C is supplied to the rear door heat exchanger. In this simplified model, the water flow rate is uncontrolled, leading to a leaving water temperature above the design temperature due to the reduced air flow rate that causes the air inlet temperature into the rear door heat exchanger to be slightly warmer than the design temperature.
The air-cooled utilization is kept constant at 100% throughout the simulation.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Units.SI.Power | PAir_nominal | 48*1320 | Design power for air-cooled IT |
| Modelica.Units.SI.Temperature | TAirDatHal | 303.15 | Air temperature in data hall |
| Modelica.Units.SI.SpecificHeatCapacity | cpAir_default | MediumAir.specificHeatCapacityCp(MediumAir.setState_pTX(T = MediumAir.T_default, p = MediumAir.p_default, X = MediumAir.X_default[1:MediumAir.nXi])) | Specific heat capacity of air |
| Buildings.Fluid.DataCenters.Racks.Air.Data.Generic | datAir | Air-cooled rack performance data | |
| Modelica.Units.SI.Temperature | TReaDooCooIn_nominal | 273.15 + 25 | Rear door heat exchanger coolant supply temperature |
| Modelica.Units.SI.Temperature | TReaDooCooOut_nominal | 273.15 + 35 | Rear door heat exchanger coolant return temperature |
| Modelica.Units.SI.Temperature | TAirReaDooIn_nominal | TAirDatHal + (datAir.TOut_nominal - datAir.TIn_nominal) | Nominal air temperature entering the rear door heat exchanger |
| Modelica.Units.SI.MassFlowRate | mReaDoo_flow_nominal | (PAir_nominal + datAir.PFan_nominal)/((TReaDooCooOut_nominal - TReaDooCooIn_nominal)*Buildings.Utilities.Psychrometrics.Constants.cpWatLiq) | Nominal mass flow rate for rear door heat exchanger at design conditions |
| Buildings.Fluid.DataCenters.Racks.RearDoorHeatExchangers.Data.Passive.Generic | datReaDooHex | ||
| Buildings.Fluid.DataCenters.Racks.Hybrid.Data.AirRearDoorHexPassive.Generic | dat |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Buildings.Controls.OBC.CDL.Reals.Sources.Constant | utiAir | Utilization of air-cooled hardware | |
| Modelica.Blocks.Math.Gain | PITAir | Power consumption by the air-cooled IT equipment | |
| Buildings.Fluid.DataCenters.Racks.Hybrid.AirRearDoorHexPassive | rac | ||
| Buildings.Fluid.Sources.Boundary_pT | datHal | Temperature and pressure of air in data hall | |
| Fluid.Sensors.TemperatureTwoPort | senTAir_a | Air inlet temperature | |
| Fluid.Sensors.TemperatureTwoPort | senTAir_b | Air outlet temperature | |
| Buildings.Fluid.Sources.Boundary_pT | souReaDoo | Rear door heat exchanger coolant supply at elevated pressure | |
| Sources.Boundary_pT | sinReaDoo | Sink rear door heat exchanger coolant | |
| Sensors.TemperatureTwoPort | senTReaDooLvg | Coolant outlet temperature from rear door heat exchanger |
Contents
| Name | Description |
|---|---|
 MediumAir | Medium for air cooling loop |
 MediumReaDooHex | Water for rear door heat exchanger loop |
Revisions
-
September 29, 2026, by Michael Wetter:
First implementation.