Buildings.Fluid.DataCenters.CDUs.LiquidToLiquid.Data
Package with data records for racks
Information
This package contains data records for models of the package Buildings.Fluid.DataCenters.CDUs.
For a description of the required and derived data, see Buildings.Fluid.DataCenters.CDUs.LiquidToLiquid.Data.Generic_epsNTU.
Extends from Modelica.Icons.MaterialPropertiesPackage (Icon for package containing property classes).
Package Content
| Name | Description |
|---|---|
 Generic_2MW
|
Generic data record for a 2 MW CDU |
| Generic_epsNTU
|
Generic data record for a CDU that uses the epsilon-NTU method to compute the thermal performance |
| GoogleProjectDeschutes_2MW
|
Data record for a Google Project Deschutes CDU |
| VertivLiebertXDU1350
|
Data record for a Vertiv Liebert XDU 1350 CDU |
 BaseClasses
|
Package with base classes |
Buildings.Fluid.DataCenters.CDUs.LiquidToLiquid.Data.Generic_2MW
Generic data record for a 2 MW CDU
Information
Generic record for a 2 MW CDU.
Extends from Buildings.Fluid.DataCenters.CDUs.LiquidToLiquid.Data.Generic_epsNTU (Generic data record for a CDU that uses the epsilon-NTU method to compute the thermal performance).
Contents
| Type | Name | Default | Description |
|---|---|---|---|
| efficiencyParameters | pumpEfficiency | Total pump efficiency vs. volumetric flow rate | |
| Nominal thermal performance | |||
| HeatFlowRate | Q_flow_nominal | 2E6 | Nominal heat flow rate (negative as it is for cooling) [W] |
| TemperatureDifference | TApp_nominal | Approach temperature on IT loop size (to cooling minus from rack) [K] | |
| Temperature | TRacOut_nominal | 273.15 + 45 | Outlet temperature to IT rack loop [K] |
| Nominal condition | |||
| MassFlowRate | mPla_flow_nominal | Nominal mass flow rate on cooling plant side [kg/s] | |
| MassFlowRate | mRac_flow_nominal | Nominal mass flow rate on rack side [kg/s] | |
| PressureDifference | dpHexPla_nominal | 80000 | Heat exchanger design pressure drop at plant side [Pa] |
| PressureDifference | dpHexRac_nominal | dpHexPla_nominal | Heat exchanger design pressure drop at rack side [Pa] |
| PressureDifference | dpFilRac_nominal | 65000 | Clean filter design pressure drop at rack-side [Pa] |
| Plant-side medium for performance data | |||
| Media | medPla | Buildings.Fluid.DataCenters.... | Media for which performance data are specified |
| Real | phiGlyPla | 0 | Glycol volume fraction for which performance data are specified |
| Rack-side medium for performance data | |||
| Media | medRac | Media for which performance data are specified | |
| Real | phiGlyRac | Glycol volume fraction for which performance data are specified. Set to 0 if only water is used. [1] | |
| Valve | |||
| PressureDifference | dpValve_nominal | dpHexPla_nominal | Nominal pressure drop of fully open valve on chiller plant side [Pa] |
| Pump | |||
| PressureDifference | dpPumpExt_nominal | 500000 | Pump head available for flow network that is connected to the CDU on the rack-side at m_flow_nominal [Pa] |
| flowParameters | pumpHead | Actual head of the pump, composed of external pump head, and head used for heat exchanger and filter | |
| Flow resistance | |||
| Medium 1 | |||
| Real | deltaMPla | 0.1 | Fraction of nominal flow rate where flow transitions to laminar on cooling plant side |
| Real | nPla | 2 | Flow exponent, n=1 for laminar, n=2 for turbulent |
| Medium 2 | |||
| Real | nRac | 2 | Flow exponent, n=1 for laminar, n=2 for turbulent |
| Real | nFilRac | 1.76 | Flow exponent for filter on rack-side, n=1 for laminar, n=2 for turbulent |
| Real | deltaMRac | 0.1 | Fraction of nominal flow rate where flow transitions to laminar on rack side |
| Dynamics | |||
| Valve | |||
| Time | strokeTime | 120 | Time needed to fully open or close actuator [s] |
| Pump | |||
| Time | riseTime | 30 | Time needed to change motor speed between zero and full speed [s] |
| Advanced | |||
| Heat transfer coefficients | |||
| Real | r_nominal | (kPla_default*(mPla_flow_nom... | Ratio between convective heat transfer coefficients at nominal conditions, r_nominal = hAPla_nominal/hARac_nominal |
| Real | nConPla | 0.8 | Exponent for convective heat transfer coefficient, h~m_flow^nCon |
| Real | nConRac | nConPla | Exponent for convective heat transfer coefficient, h~m_flow^nCon |
| Expansion vessel | |||
| Volume | VExp | -0.056/2E6*Q_flow_nominal | Size of expansion vessel on IT loop side [m3] |
Modelica definition
record Generic_2MW
"Generic data record for a 2 MW CDU"
extends Buildings.Fluid.DataCenters.CDUs.LiquidToLiquid.Data.Generic_epsNTU(
Q_flow_nominal=2E6,
TRacOut_nominal=273.15 + 45,
dpHexPla_nominal=80000,
dpPumpExt_nominal=500000,
pumpExtHead(
V_flow=mRac_flow_nominal/rhoRac_default*{0.000, 0.250, 0.500, 0.750, 1.000},
dp=dpPumpExt_nominal*({3.846, 3.676, 3.231, 2.538, 1.0})));
end Generic_2MW;
Buildings.Fluid.DataCenters.CDUs.LiquidToLiquid.Data.Generic_epsNTU
Generic data record for a CDU that uses the epsilon-NTU method to compute the thermal performance
Information
Generic record for a CDU that models the heat transfer using the epsilon-NTU method.
This is the base record that is used to characterize the performance data of CDU. The data record is structured as follows.
Required Parameters
These parameters have no default values and must be provided by the user.
| Parameter | Description | Type / Unit |
|---|---|---|
Q_flow_nominal |
Nominal heat flow rate (negative as it is for cooling). | [W] |
TApp_nominal |
Approach temperature on IT loop size (to cooling minus from rack). | [K] |
TRacOut_nominal |
Outlet temperature to IT rack loop. | [K] |
mPla_flow_nominal |
Nominal mass flow rate on cooling plant side. | [kg/s] |
mRac_flow_nominal |
Nominal mass flow rate on rack side. | [kg/s] |
dpHexPla_nominal |
Heat exchanger design pressure drop at plant side. | [Pa] |
medRac |
Media for which performance data are specified. | Types.Media |
phiGlyRac |
Glycol volume fraction for which rack-side performance data are specified. Set to 0 if only water is used. | [1] |
dpPumpExt_nominal |
Pump head available for flow network that is connected to the CDU on the rack-side at m_flow_nominal. | [Pa] |
pumpExtHead |
Pump head available for flow network that is connected to the CDU on the rack-side. | flowParameters |
Defaulted Parameters (Overridable)
These parameters are pre-configured with default values or initial equations, but may be overridden by the user.
| Parameter | Description | Type / Unit | Default Value / Equation |
|---|---|---|---|
deltaMPla |
Fraction of nominal flow rate where flow transitions to laminar on cooling plant side. | [1] |
0.1 |
dpHexRac_nominal |
Heat exchanger design pressure drop at rack side. | [Pa] |
dpHexPla_nominal |
dpFilRac_nominal |
Clean filter design pressure drop at rack-side. | [Pa] |
65000 |
nPla |
Flow exponent, n=1 for laminar, n=2 for turbulent (plant side). | [1] |
2 |
nRac |
Flow exponent, n=1 for laminar, n=2 for turbulent (rack side). | [1] |
2 |
nFilRac |
Flow exponent for filter on rack-side, n=1 for laminar, n=2 for turbulent. | [1] |
1.76 |
deltaMRac |
Fraction of nominal flow rate where flow transitions to laminar on rack side. | [1] |
0.1 |
medPla |
Media for which performance data are specified (plant side). | Types.Media |
Water |
phiGlyPla |
Glycol volume fraction for which performance data are specified (plant side). Set to 0 if only water is used. | [1] |
0 |
dpValve_nominal |
Nominal pressure drop of fully open valve on chiller plant side. | [Pa] |
dpHexPla_nominal |
strokeTime |
Time needed to fully open or close actuator. | [s] |
120 |
riseTime |
Time needed to change motor speed between zero and full speed. | [s] |
30 |
pumpEfficiency |
Total pump efficiency vs. volumetric flow rate. | efficiencyParameters |
V_flow = mRac_flow_nominal/rhoRac_default*{1}, eta = {0.7} |
pumpHead |
Actual head of the pump, composed of external pump head, and head used for heat exchanger and filter. | flowParameters |
Computed from pumpExtHead, dpHexRac_nominal, dpFilRac_nominal |
r_nominal |
Ratio between convective heat transfer coefficients at nominal conditions (hAPla_nominal/hARac_nominal). | [1] |
(kPla_default * (mPla_flow_nominal/etaPla_default)^nConPla * PrPla_default^(1/3)) / (kRac_default * (mRac_flow_nominal/etaRac_default)^nConRac * PrRac_default^(1/3)) |
nConPla |
Exponent for convective heat transfer coefficient (h~m_flownCon) on plant side. | [1] |
0.8 |
nConRac |
Exponent for convective heat transfer coefficient (h~m_flownCon) on rack side. | [1] |
nConPla |
VExp |
Size of expansion vessel on IT loop side. | [m3] |
-0.056/2E6*Q_flow_nominal |
The filter pressure drop and flow exponent is obtained from a data fit using catalogue data from Vertiv Liebert XDU 1350.
For the parameter pumpExtHead, it is recommended to use a array such as of the form
pumpExtHead(
V_flow = mRac_flow_nominal/rhoRac_default * {0.000, 0.250, 0.500, 0.750, 1.0},
dp = dpPumpExt_nominal * {11.90, 11.61, 9.810, 6.202, 1.0})
With this setting, at design flow rate (the last element of V_flow, which is set to 1),
the pressure available to the flow network connected to the CDU is equal to dpPumpExt_nominal,
and at lower volume flow rates, the available pressure will increase, as it is customary for pumps.
The increase is steeper than is typical for a pump because the CDU-internal resistance for the heat exchanger
and filter decrease as the volume flow rate decreases, and hence, the resulting curve for the pump head
that is available for pressure drops that are outside the CDU is steep.
The size of the expansion vessel VExp is by default set to the size used for the CDU
Buildings.Fluid.DataCenters.CDUs.LiquidToLiquid.Data.GoogleProjectDeschutes_2MW, which is
0.056 m3 for a cooling capacity of 2 MW.
Derived Parameters
These parameters are calculated by the model based on the above parameters and cannot be changed by the user.
| Parameter | Description | Type / Unit |
|---|---|---|
TPlaIn_nominal |
Inlet temperature from cooling plant loop. | [K] |
TPlaOut_nominal |
Outlet temperature to cooling plant loop. | [K] |
TRacIn_nominal |
Inlet temperature from IT rack loop. | [K] |
XGlyPla |
Glycol mass fraction for performance data (plant side). | [1] |
XGlyRac |
Glycol mass fraction for performance data (rack side). | [1] |
etaPla_default |
Dynamic viscosity for plant-side performance data. | [Pa.s] |
cpPla_default |
Specific heat capacity at constant pressure for plant-side performance data. | [J/(kg.K)] |
kPla_default |
Thermal conductivity for plant-side performance data. | [W/(m.K)] |
PrPla_default |
Prandtl number for plant-side performance data. | [1] |
etaRac_default |
Dynamic viscosity for rack-side performance data. | [Pa.s] |
cpRac_default |
Specific heat capacity at constant pressure for rack-side performance data. | [J/(kg.K)] |
kRac_default |
Thermal conductivity for rack-side performance data. | [W/(m.K)] |
PrRac_default |
Prandtl number for rack-side performance data. | [1] |
rhoRac_default |
Mass density for rack-side performance data. | [kg/m3] |
CPla_flow_nominal |
Capacity flow rate at nominal conditions on cooling plant side. | [W/K] |
CRac_flow_nominal |
Capacity flow rate at nominal conditions on rack side. | [W/K] |
dTPla_nominal |
Fluid temperature difference at nominal conditions on cooling plant side. | [K] |
dTRac_nominal |
Fluid temperature difference at nominal conditions on rack side. | [K] |
Extends from Modelica.Icons.Record (Icon for records).
Contents
| Type | Name | Default | Description |
|---|---|---|---|
| efficiencyParameters | pumpEfficiency | pumpEfficiency(V_flow=mRac_f... | Total pump efficiency vs. volumetric flow rate |
| Nominal thermal performance | |||
| HeatFlowRate | Q_flow_nominal | Nominal heat flow rate (negative as it is for cooling) [W] | |
| TemperatureDifference | TApp_nominal | Approach temperature on IT loop size (to cooling minus from rack) [K] | |
| Temperature | TRacOut_nominal | Outlet temperature to IT rack loop [K] | |
| Nominal condition | |||
| MassFlowRate | mPla_flow_nominal | Nominal mass flow rate on cooling plant side [kg/s] | |
| MassFlowRate | mRac_flow_nominal | Nominal mass flow rate on rack side [kg/s] | |
| PressureDifference | dpHexPla_nominal | Heat exchanger design pressure drop at plant side [Pa] | |
| PressureDifference | dpHexRac_nominal | dpHexPla_nominal | Heat exchanger design pressure drop at rack side [Pa] |
| PressureDifference | dpFilRac_nominal | 65000 | Clean filter design pressure drop at rack-side [Pa] |
| Plant-side medium for performance data | |||
| Media | medPla | Buildings.Fluid.DataCenters.... | Media for which performance data are specified |
| Real | phiGlyPla | 0 | Glycol volume fraction for which performance data are specified |
| Rack-side medium for performance data | |||
| Media | medRac | Media for which performance data are specified | |
| Real | phiGlyRac | Glycol volume fraction for which performance data are specified. Set to 0 if only water is used. [1] | |
| Valve | |||
| PressureDifference | dpValve_nominal | dpHexPla_nominal | Nominal pressure drop of fully open valve on chiller plant side [Pa] |
| Pump | |||
| PressureDifference | dpPumpExt_nominal | Pump head available for flow network that is connected to the CDU on the rack-side at m_flow_nominal [Pa] | |
| flowParameters | pumpExtHead | Pump head available for flow network that is connected to the CDU on the rack-side | |
| flowParameters | pumpHead | pumpHead(V_flow=pumpExtHead.... | Actual head of the pump, composed of external pump head, and head used for heat exchanger and filter |
| Flow resistance | |||
| Medium 1 | |||
| Real | deltaMPla | 0.1 | Fraction of nominal flow rate where flow transitions to laminar on cooling plant side |
| Real | nPla | 2 | Flow exponent, n=1 for laminar, n=2 for turbulent |
| Medium 2 | |||
| Real | nRac | 2 | Flow exponent, n=1 for laminar, n=2 for turbulent |
| Real | nFilRac | 1.76 | Flow exponent for filter on rack-side, n=1 for laminar, n=2 for turbulent |
| Real | deltaMRac | 0.1 | Fraction of nominal flow rate where flow transitions to laminar on rack side |
| Dynamics | |||
| Valve | |||
| Time | strokeTime | 120 | Time needed to fully open or close actuator [s] |
| Pump | |||
| Time | riseTime | 30 | Time needed to change motor speed between zero and full speed [s] |
| Advanced | |||
| Heat transfer coefficients | |||
| Real | r_nominal | (kPla_default*(mPla_flow_nom... | Ratio between convective heat transfer coefficients at nominal conditions, r_nominal = hAPla_nominal/hARac_nominal |
| Real | nConPla | 0.8 | Exponent for convective heat transfer coefficient, h~m_flow^nCon |
| Real | nConRac | nConPla | Exponent for convective heat transfer coefficient, h~m_flow^nCon |
| Expansion vessel | |||
| Volume | VExp | -0.056/2E6*Q_flow_nominal | Size of expansion vessel on IT loop side [m3] |
Modelica definition
record Generic_epsNTU
"Generic data record for a CDU that uses the epsilon-NTU method to compute the thermal performance"
extends Modelica.Icons.Record;
parameter Modelica.Units.SI.HeatFlowRate Q_flow_nominal(max=0)
"Nominal heat flow rate (negative as it is for cooling)";
parameter Modelica.Units.SI.TemperatureDifference TApp_nominal(min=0)
"Approach temperature on IT loop size (to cooling minus from rack)";
parameter Modelica.Units.SI.Temperature TRacOut_nominal
"Outlet temperature to IT rack loop";
final parameter Modelica.Units.SI.Temperature TPlaIn_nominal=
TRacOut_nominal - TApp_nominal
"Inlet temperature from cooling plant loop";
final parameter Modelica.Units.SI.Temperature TPlaOut_nominal=
TPlaIn_nominal - Q_flow_nominal/CPla_flow_nominal
"Outlet temperature to cooling plant loop";
final parameter Modelica.Units.SI.Temperature TRacIn_nominal=
TRacOut_nominal - Q_flow_nominal/CRac_flow_nominal "Inlet temperature from IT rack loop";
// Design mass flow rates
parameter Modelica.Units.SI.MassFlowRate mPla_flow_nominal(min=0)
"Nominal mass flow rate on cooling plant side";
parameter Modelica.Units.SI.MassFlowRate mRac_flow_nominal(min=0)
"Nominal mass flow rate on rack side";
// Flow resistances
parameter Modelica.Units.SI.PressureDifference dpHexPla_nominal(
min=0,
displayUnit="Pa") "Heat exchanger design pressure drop at plant side";
parameter Real deltaMPla=0.1
"Fraction of nominal flow rate where flow transitions to laminar on cooling plant side";
parameter Modelica.Units.SI.PressureDifference dpHexRac_nominal(
min=0,
displayUnit="Pa") = dpHexPla_nominal "Heat exchanger design pressure drop at rack side";
parameter Modelica.Units.SI.PressureDifference dpFilRac_nominal(
min=0,
displayUnit="Pa")=65000
"Clean filter design pressure drop at rack-side";
parameter Real nPla(min=1, max=2) = 2
"Flow exponent, n=1 for laminar, n=2 for turbulent";
parameter Real nRac(min=1, max=2) = 2
"Flow exponent, n=1 for laminar, n=2 for turbulent";
parameter Real nFilRac(min=1, max=2) = 1.76
"Flow exponent for filter on rack-side, n=1 for laminar, n=2 for turbulent";
parameter Real deltaMRac=0.1
"Fraction of nominal flow rate where flow transitions to laminar on rack side";
// Volume fractions
parameter Buildings.Fluid.DataCenters.CDUs.Types.Media medPla=Buildings.Fluid.DataCenters.CDUs.Types.Media.Water
"Media for which performance data are specified";
parameter Real phiGlyPla = 0
"Glycol volume fraction for which performance data are specified";
final parameter Modelica.Units.SI.MassFraction XGlyPla =
if medPla ==Buildings.Fluid.DataCenters.CDUs.Types.Media.Water
then
0
elseif medPla ==Buildings.Fluid.DataCenters.CDUs.Types.Media.EthyleneGlycol
then
Buildings.Media.Antifreeze.Functions.EthyleneGlycolWater.volumeToMassFraction(
phi=phiGlyPla,
T=TRacOut_nominal)
else
Buildings.Media.Antifreeze.Functions.PropyleneGlycolWater.volumeToMassFraction(
phi=phiGlyPla,
T=TRacOut_nominal)
"Glycol mass fraction for which performance data are specified. Set to 0 if only water is used.";
parameter Buildings.Fluid.DataCenters.CDUs.Types.Media medRac
"Media for which performance data are specified";
parameter Real phiGlyRac(
min=0,
final unit="1")
"Glycol volume fraction for which performance data are specified. Set to 0 if only water is used.";
final parameter Modelica.Units.SI.MassFraction XGlyRac =
if medRac ==Buildings.Fluid.DataCenters.CDUs.Types.Media.Water
then
0
elseif medRac ==Buildings.Fluid.DataCenters.CDUs.Types.Media.EthyleneGlycol
then
Buildings.Media.Antifreeze.Functions.EthyleneGlycolWater.volumeToMassFraction(
phi=phiGlyRac,
T=TRacOut_nominal)
else
Buildings.Media.Antifreeze.Functions.PropyleneGlycolWater.volumeToMassFraction(
phi=phiGlyRac,
T=TRacOut_nominal)
"Glycol mass fraction for which performance data are specified";
// Plant-side fluid properties
final parameter Modelica.Units.SI.DynamicViscosity etaPla_default =
Buildings.Fluid.DataCenters.CDUs.LiquidToLiquid.Data.BaseClasses.dynamicViscosity_TX_a(
medium=medPla, X_a=XGlyPla, T=TRacOut_nominal)
"Dynamic viscosity for plant-side performance data";
final parameter Modelica.Units.SI.SpecificHeatCapacity cpPla_default =
Buildings.Fluid.DataCenters.CDUs.LiquidToLiquid.Data.BaseClasses.specificHeatCapacityCp_TX_a(
medium=medPla, X_a=XGlyPla, T=TRacOut_nominal)
"Specific heat capacity at constant pressure for plant-side performance data";
final parameter Modelica.Units.SI.ThermalConductivity kPla_default =
Buildings.Fluid.DataCenters.CDUs.LiquidToLiquid.Data.BaseClasses.thermalConductivity_TX_a(
medium=medPla, X_a=XGlyPla, T=TRacOut_nominal)
"Thermal conductivity for plant-side performance data";
final parameter Modelica.Units.SI.PrandtlNumber PrPla_default =
Buildings.Fluid.DataCenters.CDUs.LiquidToLiquid.Data.BaseClasses.prandtlNumber_TX_a(
medium=medPla, X_a=XGlyPla, T=TRacOut_nominal)
"Prandtl number for plant-side performance data";
// Rack-side fluid properties
final parameter Modelica.Units.SI.DynamicViscosity etaRac_default =
Buildings.Fluid.DataCenters.CDUs.LiquidToLiquid.Data.BaseClasses.dynamicViscosity_TX_a(
medium=medRac, X_a=XGlyRac, T=TRacOut_nominal)
"Dynamic viscosity for rack-side performance data";
final parameter Modelica.Units.SI.SpecificHeatCapacity cpRac_default =
Buildings.Fluid.DataCenters.CDUs.LiquidToLiquid.Data.BaseClasses.specificHeatCapacityCp_TX_a(
medium=medRac, X_a=XGlyRac, T=TRacOut_nominal)
"Specific heat capacity at constant pressure for rack-side performance data";
final parameter Modelica.Units.SI.ThermalConductivity kRac_default =
Buildings.Fluid.DataCenters.CDUs.LiquidToLiquid.Data.BaseClasses.thermalConductivity_TX_a(
medium=medRac, X_a=XGlyRac, T=TRacOut_nominal)
"Thermal conductivity for rack-side performance data";
final parameter Modelica.Units.SI.PrandtlNumber PrRac_default =
Buildings.Fluid.DataCenters.CDUs.LiquidToLiquid.Data.BaseClasses.prandtlNumber_TX_a(
medium=medRac, X_a=XGlyRac, T=TRacOut_nominal)
"Prandtl number for rack-side performance data";
final parameter Modelica.Units.SI.Density rhoRac_default =
Buildings.Fluid.DataCenters.CDUs.LiquidToLiquid.Data.BaseClasses.density_TX_a(
medium=medRac, X_a=XGlyRac, T=TRacOut_nominal)
"Mass density for rack-side performance data";
// Valve
parameter Modelica.Units.SI.PressureDifference dpValve_nominal(
displayUnit="Pa") = dpHexPla_nominal
"Nominal pressure drop of fully open valve on chiller plant side";
parameter Modelica.Units.SI.Time strokeTime=120
"Time needed to fully open or close actuator";
// Pump configuration
parameter Modelica.Units.SI.Time riseTime=30
"Time needed to change motor speed between zero and full speed";
parameter Buildings.Fluid.Movers.BaseClasses.Characteristics.efficiencyParameters
pumpEfficiency(
V_flow=mRac_flow_nominal/rhoRac_default*{1},
eta={0.7}) "Total pump efficiency vs. volumetric flow rate";
// Rack-side pump configuration
parameter Modelica.Units.SI.PressureDifference dpPumpExt_nominal(
displayUnit="Pa",
min=0)
"Pump head available for flow network that is connected to the CDU on the rack-side at m_flow_nominal";
parameter Buildings.Fluid.Movers.BaseClasses.Characteristics.flowParameters pumpExtHead
"Pump head available for flow network that is connected to the CDU on the rack-side";
parameter Buildings.Fluid.Movers.BaseClasses.Characteristics.flowParameters pumpHead(
V_flow=pumpExtHead.V_flow,
dp=pumpExtHead.dp +
{(pumpExtHead.V_flow[i]*rhoRac_default)^nRac * dpHexRac_nominal/mRac_flow_nominal^nRac for i in 1:size(pumpExtHead.V_flow, 1)} +
{(pumpExtHead.V_flow[i]*rhoRac_default)^nFilRac * dpFilRac_nominal/mRac_flow_nominal^nFilRac for i in 1:size(pumpExtHead.V_flow, 1)})
"Actual head of the pump, composed of external pump head, and head used for heat exchanger and filter";
parameter Real r_nominal(min=0)=
(kPla_default * (mPla_flow_nominal/etaPla_default)^nConPla * PrPla_default^(1/3)) /
(kRac_default * (mRac_flow_nominal/etaRac_default)^nConRac * PrRac_default^(1/3))
"Ratio between convective heat transfer coefficients at nominal conditions, r_nominal = hAPla_nominal/hARac_nominal";
parameter Real nConPla(
min=0,
max=1) = 0.8
"Exponent for convective heat transfer coefficient, h~m_flow^nCon";
parameter Real nConRac(
min=0,
max=1) = nConPla
"Exponent for convective heat transfer coefficient, h~m_flow^nCon";
final parameter Modelica.Units.SI.ThermalConductance CPla_flow_nominal=
mPla_flow_nominal * cpPla_default
"Capacity flow rate at nominal conditions on cooling plant side";
final parameter Modelica.Units.SI.ThermalConductance CRac_flow_nominal=
mRac_flow_nominal * cpRac_default
"Capacity flow rate at nominal conditions on rack side";
final parameter Modelica.Units.SI.TemperatureDifference dTPla_nominal(min=0)=
-Q_flow_nominal / CPla_flow_nominal
"Fluid temperature difference at nominal conditions on cooling plant side";
final parameter Modelica.Units.SI.TemperatureDifference dTRac_nominal(max=0)=
Q_flow_nominal / CRac_flow_nominal
"Fluid temperature difference at nominal conditions on rack side";
parameter Modelica.Units.SI.Volume VExp = -0.056/2E6*Q_flow_nominal
"Size of expansion vessel on IT loop side";
end Generic_epsNTU;
Buildings.Fluid.DataCenters.CDUs.LiquidToLiquid.Data.GoogleProjectDeschutes_2MW
Data record for a Google Project Deschutes CDU
Information
This data record is for the 5th generation CDU unit of Google, named Project Deschutes. This unit is specified for the following data (OCP, 2026):
| Description | Value | Unit |
|---|---|---|
| IT Loop flow | 31.48 | kg/s |
| Facility Loop flow | 32.30 | kg/s |
| IT Loop dP available | 80-90 551,581 - 620,528 |
psi Pa |
| Facility Loop dP | 15-27 103,421 - 186,159 |
psid Pa |
| Thermal load | 2000 | kW |
| Approach temperature | 3 | °C |
| Facility Loop entering temperature | 26.8 | °C |
| Power consumption | 74 | kW |
| Liquids | DI water, PG25 |
References
OCP 2026. Open Compute Project meeting, CDU Information WP. March 24, 2026.
Extends from Buildings.Fluid.DataCenters.CDUs.LiquidToLiquid.Data.Generic_epsNTU (Generic data record for a CDU that uses the epsilon-NTU method to compute the thermal performance).
Contents
| Type | Name | Default | Description |
|---|---|---|---|
| efficiencyParameters | pumpEfficiency | Total pump efficiency vs. volumetric flow rate | |
| Nominal thermal performance | |||
| HeatFlowRate | Q_flow_nominal | 2E6 | Nominal heat flow rate (negative as it is for cooling) [W] |
| TemperatureDifference | TApp_nominal | 3 | Approach temperature on IT loop size (to cooling minus from rack) [K] |
| Temperature | TRacOut_nominal | 273.15 + 45 | Outlet temperature to IT rack loop [K] |
| Nominal condition | |||
| MassFlowRate | mPla_flow_nominal | Nominal mass flow rate on cooling plant side [kg/s] | |
| MassFlowRate | mRac_flow_nominal | Nominal mass flow rate on rack side [kg/s] | |
| PressureDifference | dpHexPla_nominal | 80000 | Heat exchanger design pressure drop at plant side [Pa] |
| PressureDifference | dpHexRac_nominal | dpHexPla_nominal | Heat exchanger design pressure drop at rack side [Pa] |
| PressureDifference | dpFilRac_nominal | 65000 | Clean filter design pressure drop at rack-side [Pa] |
| Plant-side medium for performance data | |||
| Media | medPla | Buildings.Fluid.DataCenters.... | Media for which performance data are specified |
| Real | phiGlyPla | 0 | Glycol volume fraction for which performance data are specified |
| Rack-side medium for performance data | |||
| Media | medRac | Buildings.Fluid.DataCenters.... | Media for which performance data are specified |
| Real | phiGlyRac | 0.25 | Glycol volume fraction for which performance data are specified. Set to 0 if only water is used. [1] |
| Valve | |||
| PressureDifference | dpValve_nominal | dpHexPla_nominal | Nominal pressure drop of fully open valve on chiller plant side [Pa] |
| Pump | |||
| PressureDifference | dpPumpExt_nominal | 827000 | Pump head available for flow network that is connected to the CDU on the rack-side at m_flow_nominal [Pa] |
| flowParameters | pumpHead | Actual head of the pump, composed of external pump head, and head used for heat exchanger and filter | |
| Flow resistance | |||
| Medium 1 | |||
| Real | deltaMPla | 0.1 | Fraction of nominal flow rate where flow transitions to laminar on cooling plant side |
| Real | nPla | 2 | Flow exponent, n=1 for laminar, n=2 for turbulent |
| Medium 2 | |||
| Real | nRac | 2 | Flow exponent, n=1 for laminar, n=2 for turbulent |
| Real | nFilRac | 1.76 | Flow exponent for filter on rack-side, n=1 for laminar, n=2 for turbulent |
| Real | deltaMRac | 0.1 | Fraction of nominal flow rate where flow transitions to laminar on rack side |
| Dynamics | |||
| Valve | |||
| Time | strokeTime | 120 | Time needed to fully open or close actuator [s] |
| Pump | |||
| Time | riseTime | 30 | Time needed to change motor speed between zero and full speed [s] |
| Advanced | |||
| Heat transfer coefficients | |||
| Real | r_nominal | (kPla_default*(mPla_flow_nom... | Ratio between convective heat transfer coefficients at nominal conditions, r_nominal = hAPla_nominal/hARac_nominal |
| Real | nConPla | 0.8 | Exponent for convective heat transfer coefficient, h~m_flow^nCon |
| Real | nConRac | nConPla | Exponent for convective heat transfer coefficient, h~m_flow^nCon |
| Expansion vessel | |||
| Volume | VExp | -0.056/2E6*Q_flow_nominal | Size of expansion vessel on IT loop side [m3] |
Modelica definition
record GoogleProjectDeschutes_2MW
"Data record for a Google Project Deschutes CDU"
extends Buildings.Fluid.DataCenters.CDUs.LiquidToLiquid.Data.Generic_epsNTU(
Q_flow_nominal=2E6,
TApp_nominal=3,
TRacOut_nominal=273.15 + 45,
dpHexPla_nominal=80000,
medPla=Buildings.Fluid.DataCenters.CDUs.Types.Media.Water,
medRac=Buildings.Fluid.DataCenters.CDUs.Types.Media.PropyleneGlycol,
phiGlyRac=0.25,
dpPumpExt_nominal=827000,
pumpExtHead(
V_flow=mRac_flow_nominal/rhoRac_default*{0.000, 0.250, 0.500, 0.750, 1.000},
dp=dpPumpExt_nominal*({11.90, 11.61, 9.810, 6.202, 1.0})));
end GoogleProjectDeschutes_2MW;
Buildings.Fluid.DataCenters.CDUs.LiquidToLiquid.Data.VertivLiebertXDU1350
Data record for a Vertiv Liebert XDU 1350 CDU
Information
This data record is for a Vertiv Liebert XDU 1350. This unit is specified for the following data:
| Description | Value | Unit |
|---|---|---|
| Thermal load | 1368 | kW |
| Approach temperature | 4 | °C |
| Liquids | DI water, PG20 |
References
Vertiv, Liebert XDU 1350 data sheet, SL-70799 (R10/25)
Extends from Buildings.Fluid.DataCenters.CDUs.LiquidToLiquid.Data.Generic_epsNTU (Generic data record for a CDU that uses the epsilon-NTU method to compute the thermal performance).
Contents
| Type | Name | Default | Description |
|---|---|---|---|
| efficiencyParameters | pumpEfficiency | Total pump efficiency vs. volumetric flow rate | |
| Nominal thermal performance | |||
| HeatFlowRate | Q_flow_nominal | 1350E3 | Nominal heat flow rate (negative as it is for cooling) [W] |
| TemperatureDifference | TApp_nominal | 4 | Approach temperature on IT loop size (to cooling minus from rack) [K] |
| Temperature | TRacOut_nominal | 273.15 + 32 | Outlet temperature to IT rack loop [K] |
| Nominal condition | |||
| MassFlowRate | mPla_flow_nominal | 20.6 | Nominal mass flow rate on cooling plant side [kg/s] |
| MassFlowRate | mRac_flow_nominal | 20.6 | Nominal mass flow rate on rack side [kg/s] |
| PressureDifference | dpHexPla_nominal | 84000 | Heat exchanger design pressure drop at plant side [Pa] |
| PressureDifference | dpHexRac_nominal | dpHexPla_nominal | Heat exchanger design pressure drop at rack side [Pa] |
| PressureDifference | dpFilRac_nominal | 65000 | Clean filter design pressure drop at rack-side [Pa] |
| Plant-side medium for performance data | |||
| Media | medPla | Buildings.Fluid.DataCenters.... | Media for which performance data are specified |
| Real | phiGlyPla | 0 | Glycol volume fraction for which performance data are specified |
| Rack-side medium for performance data | |||
| Media | medRac | Buildings.Fluid.DataCenters.... | Media for which performance data are specified |
| Real | phiGlyRac | 0.2 | Glycol volume fraction for which performance data are specified. Set to 0 if only water is used. [1] |
| Valve | |||
| PressureDifference | dpValve_nominal | dpHexPla_nominal | Nominal pressure drop of fully open valve on chiller plant side [Pa] |
| Pump | |||
| PressureDifference | dpPumpExt_nominal | 500000 | Pump head available for flow network that is connected to the CDU on the rack-side at m_flow_nominal [Pa] |
| flowParameters | pumpHead | Actual head of the pump, composed of external pump head, and head used for heat exchanger and filter | |
| Flow resistance | |||
| Medium 1 | |||
| Real | deltaMPla | 0.1 | Fraction of nominal flow rate where flow transitions to laminar on cooling plant side |
| Real | nPla | 2 | Flow exponent, n=1 for laminar, n=2 for turbulent |
| Medium 2 | |||
| Real | nRac | 2 | Flow exponent, n=1 for laminar, n=2 for turbulent |
| Real | nFilRac | 1.76 | Flow exponent for filter on rack-side, n=1 for laminar, n=2 for turbulent |
| Real | deltaMRac | 0.1 | Fraction of nominal flow rate where flow transitions to laminar on rack side |
| Dynamics | |||
| Valve | |||
| Time | strokeTime | 120 | Time needed to fully open or close actuator [s] |
| Pump | |||
| Time | riseTime | 30 | Time needed to change motor speed between zero and full speed [s] |
| Advanced | |||
| Heat transfer coefficients | |||
| Real | r_nominal | (kPla_default*(mPla_flow_nom... | Ratio between convective heat transfer coefficients at nominal conditions, r_nominal = hAPla_nominal/hARac_nominal |
| Real | nConPla | 0.8 | Exponent for convective heat transfer coefficient, h~m_flow^nCon |
| Real | nConRac | nConPla | Exponent for convective heat transfer coefficient, h~m_flow^nCon |
| Expansion vessel | |||
| Volume | VExp | 24E-3 | Size of expansion vessel on IT loop side [m3] |
Modelica definition
record VertivLiebertXDU1350
"Data record for a Vertiv Liebert XDU 1350 CDU"
extends Buildings.Fluid.DataCenters.CDUs.LiquidToLiquid.Data.Generic_epsNTU(
Q_flow_nominal=1350E3,
mRac_flow_nominal=20.6,
mPla_flow_nominal=20.6,
TApp_nominal=4,
TRacOut_nominal=273.15 + 32,
dpHexPla_nominal=84000,
medPla=Buildings.Fluid.DataCenters.CDUs.Types.Media.Water,
medRac=Buildings.Fluid.DataCenters.CDUs.Types.Media.PropyleneGlycol,
phiGlyRac=0.2,
dpPumpExt_nominal=500000,
pumpExtHead(
V_flow=mRac_flow_nominal/rhoRac_default*{0.000, 0.250, 0.500, 0.750, 1.000},
dp=dpPumpExt_nominal*({3.846, 3.676, 3.231, 2.538, 1.0})),
VExp=24E-3);
end VertivLiebertXDU1350;