modelAirLiquidRearDoorHexPassive
Extends from Buildings.Fluid.DataCenters.Racks.Hybrid.BaseClasses.PartialAirLiquidRearDoorHex (Partial model for hybrid rack combining liquid-cooled and air-cooled components with a rear door heat exchanger).
Information
Model of a hybrid IT rack that combines liquid-cooled and air-cooled components with a rear door heat exchanger.
This model extends Buildings.Fluid.DataCenters.Racks.Hybrid.BaseClasses.AirLiquid and adds a rear door heat exchanger using Buildings.Fluid.DataCenters.Racks.RearDoorHeatExchangers.Passive.
The rear door heat exchanger is connected between the air outlet of the
air-cooled rack component air.port_b and the top-level air outlet
port portAir_b.
It cools the warm rack exhaust air using a liquid coolant loop connected
through portReaDooHex_a (inlet) and portReaDooHex_b (outlet).
The medium for the rear door heat exchanger coolant is MediumReaDooHex,
which is separate from the liquid cooling medium MediumLiq used to cool the
cold plate components.
The model has separate fluid ports for each cooling loop.
For liquid cooling, portLiq_a and portLiq_b serve as the inlet and outlet ports.
For air cooling, portAir_a and portAir_b serve as the inlet and outlet ports.
For the rear door heat exchanger coolant, portReaDooHex_a and portReaDooHex_b
serve as the inlet and outlet ports.
If the fan of the air-cooled IT is controlled based on the rack outlet temperature, then the temperature between the rack and the rear door heat exchanger is used as the measurement signal; otherwise, the IT load is used as an input for the fan controller
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Performance data | |||
| Buildings.Fluid.DataCenters.Racks.Hybrid.Data.AirLiquid.Generic | dat (from AirLiquid) | Performance data | |
| Dynamics › Liquid cooling | |||
| Modelica.Fluid.Types.Dynamics | energyDynamicsLiq (from AirLiquid) | Modelica.Fluid.Types.Dynamics.DynamicFreeInitial | Type of energy balance for liquid-cooled component: dynamic (3 initialization options) or steady state |
| Modelica.Units.SI.Time | tauLiq (from AirLiquid) | 2 | Time constant of liquid outlet temperature at nominal flow |
| Initialization › Liquid cooling | |||
| Modelica.Units.SI.Temperature | TLiq_start (from AirLiquid) | 293.15 | Start value of liquid temperature |
| Liquid cooling | |||
| Modelica.Units.SI.VolumeFlowRate | VColPla_flow_nominal (from AirLiquid) | sum(dat.liq.theRes.V_flow)/size(dat.liq.theRes.V_flow, 1) | Design flow rate of one cold plate for liquid cooling |
| Real | nColPla (from AirLiquid) | dat.liq.PIT_nominal/(VColPla_flow_nominal*1000*4200*(dat.liq.PIT_nominal/(dat.liq.m_flow_nominal*4200))) | Number of cold plates for liquid cooling |
| Advanced › Liquid cooling | |||
| Boolean | linearizedLiq (from AirLiquid) | false | = true, use linear relation between m_flow and dp for liquid cooling |
| Dynamics › Air cooling | |||
| Modelica.Fluid.Types.Dynamics | energyDynamicsAir (from AirLiquid) | Modelica.Fluid.Types.Dynamics.DynamicFreeInitial | Type of energy balance for air-cooled component: dynamic (3 initialization options) or steady state |
| Modelica.Units.SI.Time | tauAir (from AirLiquid) | 2 | Time constant of air outlet temperature at nominal flow |
| Initialization › Air cooling | |||
| Modelica.Units.SI.Temperature | TAir_start (from AirLiquid) | 293.15 | Start value of air temperature |
| Fan controller | |||
| Buildings.Fluid.DataCenters.Racks.FanControllers.Types.Strategy | fanControl (from AirLiquid) | Buildings.Fluid.DataCenters.Racks.FanControllers.Types.Strategy.Load | Type of fan control strategy |
| Real[:,:] | fanSpeed (from AirLiquid) | [0.0, 0.0; 1.0, 1.0] | Load and fan speed matrix (1st column normalized IT load, 2nd fan speed), e.g., fanSpeed=[0, 0; 0.5, 0.7; 1, 1]) |
| Modelica.Units.SI.Temperature | TAirOut_set (from AirLiquid) | dat.air.TOut_nominal | Set point temperature for rack outlet air |
| Real | k (from AirLiquid) | 1 | Gain of fan PI controller |
| Modelica.Units.SI.Time | Ti (from AirLiquid) | 60 | Integrator time constant of fan PI controller |
| Assumptions | |||
| Boolean | allowFlowReversalAir (from AirLiquid) | true | = false to simplify equations, assuming, but not enforcing, no flow reversal for air loop |
| Boolean | allowFlowReversalLiq (from AirLiquid) | true | = false to simplify equations, assuming, but not enforcing, no flow reversal for liquid loop |
| Boolean | allowFlowReversalCoo (from PartialAirLiquidRearDoorHex) | true | = false to simplify equations, assuming, but not enforcing, no flow reversal for rear door heat exchanger coolant |
Connectors
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Buildings.Fluid.DataCenters.Racks.Liquid.ColdPlateR_P | liq (from AirLiquid) | Liquid-cooled rack component | |
| Buildings.Fluid.DataCenters.Racks.Air.Rack_P | air (from AirLiquid) | Air-cooled rack component | |
| Buildings.Fluid.DataCenters.Racks.RearDoorHeatExchangers.BaseClasses.PartialRearDoorHeatExchanger | reaDooHex (from PartialAirLiquidRearDoorHex) |
Revisions
-
September 12, 2026, by Michael Wetter:
First implementation.