modelAirRearDoorHexActive
Extends from Buildings.Fluid.DataCenters.Racks.Hybrid.BaseClasses.PartialAirRearDoorHex (Partial model for air-cooled rack with a rear door heat exchanger).
Information
Model of an air-cooled IT rack with an active rear door heat exchanger.
This model extends Buildings.Fluid.DataCenters.Racks.Hybrid.BaseClasses.PartialAirRearDoorHex and adds an active rear door heat exchanger using Buildings.Fluid.DataCenters.Racks.RearDoorHeatExchangers.Active.
Unlike
Buildings.Fluid.DataCenters.Racks.Hybrid.AirRearDoorHexPassive,
this model includes a dedicated fan that actively drives air flow through the
heat exchanger. The fan speed is modulated by a PI controller to maintain
zero back pressure. The fan power is reported through the output
PReaDooHexFan.
The fan is part of the rear door heat exchanger model and positioned downstream
of the heat exchanger.
The rear door heat exchanger cools the warm rack exhaust air using a coolant loop connected
through portReaDooHex_a (inlet) and portReaDooHex_b (outlet).
The medium for the rear door heat exchanger coolant is MediumReaDooHex.
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. The fan of the rear door heat exchanger is controlled to have zero back pressure. Therefore, if the CPU fan speed increases, it will build up back pressure, and the rear door heat exchanger then increases its speed as well.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Performance data | |||
| Buildings.Fluid.DataCenters.Racks.Hybrid.Data.AirRearDoorHexPassive.Generic | dat (from Air) | Performance data | |
| Dynamics › Air cooling | |||
| Modelica.Fluid.Types.Dynamics | energyDynamicsAir (from Air) | 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 Air) | 2 | Time constant of air outlet temperature at nominal flow |
| Initialization › Air cooling | |||
| Modelica.Units.SI.Temperature | TAir_start (from Air) | 293.15 | Start value of air temperature |
| Fan controller | |||
| Buildings.Fluid.DataCenters.Racks.FanControllers.Types.Strategy | fanControl (from Air) | Buildings.Fluid.DataCenters.Racks.FanControllers.Types.Strategy.Load | Type of fan control strategy |
| Real[:,:] | fanSpeed (from Air) | [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 Air) | dat.air.TOut_nominal | Set point temperature for rack outlet air |
| Real | k (from Air) | 1 | Gain of fan PI controller |
| Modelica.Units.SI.Time | Ti (from Air) | 60 | Integrator time constant of fan PI controller |
| Assumptions | |||
| Boolean | allowFlowReversal (from Air) | true | = false to simplify equations, assuming, but not enforcing, no flow reversal |
| Boolean | allowFlowReversalCoo (from PartialAirRearDoorHex) | true | = false to simplify equations, assuming, but not enforcing, no flow reversal for rear door heat exchanger coolant |
| Rear door heat exchanger fan controller | |||
| Real | kReaDooHex | 1 | Gain of PI controller |
| Modelica.Units.SI.Time | TiReaDooHex | 10 | Integrator time constant of PI controller |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Fluid.Interfaces.FluidPort_a | portAir_a (from Air) | Air cooling inlet port | |
| Modelica.Fluid.Interfaces.FluidPort_b | portAir_b (from Air) | Air cooling outlet port | |
| Modelica.Blocks.Interfaces.RealInput | PAir (from Air) | Power consumed by air-cooled IT | |
| Modelica.Blocks.Interfaces.RealOutput | PAirTot (from Air) | Electric power consumed by air-cooled IT, including fan energy | |
| Modelica.Blocks.Interfaces.RealOutput | PAirFan (from Air) | Electric power consumed by fan for air-cooled IT | |
| Modelica.Fluid.Interfaces.FluidPort_a | portReaDooHex_a (from PartialAirRearDoorHex) | Rear door heat exchanger coolant inlet port | |
| Modelica.Fluid.Interfaces.FluidPort_b | portReaDooHex_b (from PartialAirRearDoorHex) | Rear door heat exchanger coolant outlet port | |
| Modelica.Blocks.Interfaces.RealOutput | PReaDooHexFan | Power consumed by rear door heat exchanger fan |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Buildings.Fluid.DataCenters.Racks.Air.Rack_P | air (from Air) | Air-cooled rack component | |
| Buildings.Fluid.DataCenters.Racks.RearDoorHeatExchangers.BaseClasses.PartialRearDoorHeatExchanger | reaDooHex (from PartialAirRearDoorHex) |
Revisions
-
September 29, 2026, by Michael Wetter:
First implementation.