modelPartialRack
Extends from Buildings.Fluid.Interfaces.PartialTwoPort (Partial component with two ports).
Information
Partial model of an IT rack.
Electrical and fluid characterization
The model takes as an input the electrical power consumption, and assumes all is converted to the heat that needs to be rejected through the fluid ports, e.g.,
Q_flow = P.
The fluid outlet temperature is computed using a first order delay to mimic
the transient effect. This first order delay is characterized by the user-configurable
time constant tau, set by default to tau=2 seconds.
For exact transient response, this value should be identified based on measurements.
To compute the pressure drop, the model uses Buildings.Fluid.FixedResistances.PressureDrop. Therefore, the mass flow rate and pressure drop are related as
m_flow ⁄ m_flow_nominal = (dp ⁄ dp_nominal)m,
where
m_flow_nominal is a parameter for the design flow rate,
dp is the pressure difference between inlet and outlet,
dp_nominal is a parameter for the design pressure difference, and
m is a parameter for the flow exponent.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Buildings.Fluid.DataCenterEquipment.Racks.BaseClasses.Data.Generic | dat | Performance data | |
| Assumptions | |||
| Boolean | allowFlowReversal (from PartialTwoPort) | true | = false to simplify equations, assuming, but not enforcing, no flow reversal |
| Dynamics › Conservation equations | |||
| Modelica.Fluid.Types.Dynamics | energyDynamics | Modelica.Fluid.Types.Dynamics.DynamicFreeInitial | Type of energy balance: dynamic (3 initialization options) or steady state |
| Dynamics | |||
| Modelica.Units.SI.Time | tau | 2 | Time constant of fluid outlet temperature at nominal flow |
| Initialization | |||
| Medium.Temperature | T_start | Medium.T_default | Start value of temperature |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Fluid.Interfaces.FluidPort_a | port_a (from PartialTwoPort) | Fluid connector a (positive design flow direction is from port_a to port_b) | |
| Modelica.Fluid.Interfaces.FluidPort_b | port_b (from PartialTwoPort) | Fluid connector b (positive design flow direction is from port_a to port_b) | |
| Modelica.Blocks.Interfaces.RealInput | P | Electrical power consumption |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Real | utiIT | P/dat.PIT_nominal | IT utilization |
| Fluid.Delays.DelayFirstOrder | vol | Fluid control volume | |
| Modelica.Units.SI.MassFlowRate | m_flow | port_a.m_flow | Mass flow rate from port_a to port_b |
Contents
| Name | Description |
|---|---|
 Medium | Medium in the component |
Revisions
-
June 26, 2026, by Michael Wetter:
First implementation.