modelAirLiquidRearDoorHexPassive
Extends from Buildings.Fluid.DataCenters.Racks.Hybrid.Examples.AirLiquid (Example model for hybrid liquid-cooled and air-cooled rack).
Information
Example model of a hybrid IT rack with liquid-cooled, air-cooled, and rear door heat exchanger components. This model extends Buildings.Fluid.DataCenters.Racks.Hybrid.Examples.AirLiquid and replaces the rack with a rack that has 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. Note that these values are slightly higher than the ones in Buildings.Fluid.DataCenters.Racks.Hybrid.Examples.AirLiquid. The reason is that 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 therefore slightly lower, leading to a higher rack outlet temperature, which is upstream of the rear door heat exchanger. The air leaving the rear door heat exchanger is 30.1°C.
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 of 35.3°C, which is above the design temperature of 35°C 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 liquid cooling and pump control loops operate identically to the base example.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Units.SI.Power | PLiq_nominal (from AirLiquid) | 48*13200 | Design power for liquid-cooled IT |
| Modelica.Units.SI.Power | PAir_nominal (from AirLiquid) | 0.1*PLiq_nominal | Design power for air-cooled IT |
| Modelica.Units.SI.TemperatureDifference | dTLiq_nominal (from AirLiquid) | 7 | Design temperature difference of liquid coolant |
| Modelica.Units.SI.Temperature | TLiqIn_nominal (from AirLiquid) | 273.15 + 42 | Supply coolant temperature to rack at design conditions |
| Modelica.Units.SI.MassFlowRate | mLiq_flow_nominal (from AirLiquid) | PLiq_nominal/dTLiq_nominal/cpLiq_default | Nominal mass flow rate for liquid cooling at design conditions |
| Modelica.Units.SI.SpecificHeatCapacity | cpLiq_default (from AirLiquid) | MediumLiq.specificHeatCapacityCp(state = MediumLiq.setState_pTX(T = MediumLiq.T_default, p = MediumLiq.p_default, X = MediumLiq.X_default[1:MediumLiq.nXi])) | Heat capacity of liquid coolant |
| Modelica.Units.SI.PressureDifference | dpValve_nominal (from AirLiquid) | 5000 | Nominal pressure drop of fully open valve |
| Buildings.Fluid.DataCenters.Racks.Liquid.Data.OCP_1kW_OAM_PG25 | datLiq (from AirLiquid) | Liquid-cooled rack performance data | |
| Buildings.Fluid.DataCenters.Racks.Air.Data.Generic | datAir (from AirLiquid) | Air-cooled rack performance data | |
| Buildings.Fluid.DataCenters.Racks.Hybrid.Data.AirLiquid.Generic | dat (from AirLiquid) | ||
| Modelica.Units.SI.Temperature | TAirDatHal (from AirLiquid) | 303.15 | Air temperature in data hall |
| Modelica.Units.SI.SpecificHeatCapacity | cpAir_default (from AirLiquid) | 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 |
| 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 |
Components
Contents
| Name | Description |
|---|---|
 MediumReaDooHex | Water for rear door heat exchanger loop |
Revisions
-
September 13, 2026, by Michael Wetter:
First implementation.