Buildings.Applications.DataCenters.ChillerCooled.Examples
Collection of models that illustrate model use and test models
Information
This package contains examples for the use of models that can be found in Buildings.Applications.DataCenters.ChillerCooled.
Extends from Modelica.Icons.ExamplesPackage (Icon for packages containing runnable examples).
Package Content
Name | Description |
---|---|
IntegratedPrimaryLoadSideEconomizer | Example that demonstrates a chiller plant with integrated primary load side economizer |
IntegratedPrimarySecondaryEconomizer | Example that demonstrates a chiller plant with integrated primary-secondary side economizer |
NonIntegratedPrimarySecondaryEconomizer | Example that demonstrates a chiller plant with non-integrated primary-secondary side economizer |
BaseClasses | Base classes for examples |
Buildings.Applications.DataCenters.ChillerCooled.Examples.IntegratedPrimaryLoadSideEconomizer
Example that demonstrates a chiller plant with integrated primary load side economizer
Information
System Configuration
This example demonstrates the implementation of a chiller plant with water-side economizer (WSE) to cool a data center. The system is a primary-only chiller plant with two chillers and an integrated WSE located on the load side. The system schematics is as shown below.
Control Logic
This section describes the detailed control logic used in this chilled water plant system.
Cooling Mode Control
The chilled water system with integrated waterside economizer can run in three modes: free cooling (FC) mode, partially mechanical cooling (PMC) mode and fully mechanical cooling (FMC) mode. The detailed control logics about how to switch among these three cooling modes are described in Buildings.Applications.DataCenters.ChillerCooled.Controls.CoolingMode. Details on how the valves are operated under different cooling modes are presented in Buildings.Applications.DataCenters.ChillerCooled.Equipment.IntegratedPrimaryLoadSide.
Chiller Staging Control
The staging sequence of multiple chillers are descibed as below:
- The chillers are all off when cooling mode is FC.
- One chiller is commanded on when cooling mode is not FC.
- Two chillers are commanded on when cooling mode is not FC and the cooling load served by the chillers is larger than a critical value.
The detailed implementation is shown in Buildings.Applications.DataCenters.ChillerCooled.Controls.ChillerStage.
Pump Staging Control
For constant speed pumps, the number of running pumps equals to the number of running chillers.
For variable speed pumps, the number of running pumps is controlled by the speed signal and the mass flow rate. Details are shown in Buildings.Applications.DataCenters.ChillerCooled.Controls.VariableSpeedPumpStage. The speed is controlled by maintaining a fixed differential pressure between the outlet and inlet on the waterside of the Computer Room Air Handler (CRAH).
Cooling Tower Speed Control
The control logic for cooling tower fan speed is described as:
- When in FMC mode, the cooling tower speed is controlled to maintain the condenser water supply temperature (CWST) at its setpoint.
- When in PMC mode, the fan is set to run at 100% speed to make the condenser water as cold as possible and maximize the WSE output.
- When in FC mode, the fan speed is modulated to maintain chilled water supply temperature at its setpoint.
Detailed implementation of cooling tower speed control can be found in Buildings.Applications.DataCenters.ChillerCooled.Controls.CoolingTowerSpeed.
Room temperature control
The room temperature is controlled by adjusting the fan speed of the AHU using a PI controller.
Note that for simplicity, the temperature and differential pressure reset control are not implemented in this example.
Extends from Modelica.Icons.Example (Icon for runnable examples), Buildings.Applications.DataCenters.ChillerCooled.Examples.BaseClasses.PostProcess (Post-processing), Buildings.Applications.DataCenters.ChillerCooled.Examples.BaseClasses.PartialDataCenter (Partial model that impliments cooling system for data centers).
Parameters
Type | Name | Default | Description |
---|---|---|---|
replaceable package MediumA | Air | Medium model | |
replaceable package MediumW | Water | Medium model | |
Integer | numChi | 2 | Number of chillers |
MassFlowRate | m1_flow_chi_nominal | 34.7 | Nominal mass flow rate at condenser water in the chillers [kg/s] |
MassFlowRate | m2_flow_chi_nominal | 18.3 | Nominal mass flow rate at evaporator water in the chillers [kg/s] |
PressureDifference | dp1_chi_nominal | 46.2*1000 | Nominal pressure [Pa] |
PressureDifference | dp2_chi_nominal | 44.8*1000 | Nominal pressure [Pa] |
Power | QEva_nominal | m2_flow_chi_nominal*4200*(6.... | Nominal cooling capaciaty(Negative means cooling) [W] |
MassFlowRate | m1_flow_wse_nominal | 34.7 | Nominal mass flow rate at condenser water in the chillers [kg/s] |
MassFlowRate | m2_flow_wse_nominal | 35.3 | Nominal mass flow rate at condenser water in the chillers [kg/s] |
PressureDifference | dp1_wse_nominal | 33.1*1000 | Nominal pressure [Pa] |
PressureDifference | dp2_wse_nominal | 34.5*1000 | Nominal pressure [Pa] |
Generic | perPumCW[numChi] | Performance data for condenser water pumps | |
Time | tWai | 1200 | Waiting time [s] |
ThermalConductance | UA_nominal | numChi*QEva_nominal/Building... | Thermal conductance at nominal flow for sensible heat, used to compute time constant [W/K] |
MassFlowRate | mAir_flow_nominal | 161.35 | Nominal air mass flowrate [kg/s] |
Real | yValMinAHU | 0.1 | Minimum valve openning position [1] |
Temperature | TCHWSet | 273.15 + 8 | Chilled water temperature setpoint [K] |
Temperature | TSupAirSet | TCHWSet + 10 | Supply air temperature setpoint [K] |
Temperature | TRetAirSet | 273.15 + 25 | Supply air temperature setpoint [K] |
Pressure | dpSetPoi | 80000 | Differential pressure setpoint [Pa] |
Generic | perPumPri[numChi] | Performance data for primary pumps |
Connectors
Type | Name | Description |
---|---|---|
Bus | weaBus | Weather data bus |
Modelica definition
Buildings.Applications.DataCenters.ChillerCooled.Examples.IntegratedPrimarySecondaryEconomizer
Example that demonstrates a chiller plant with integrated primary-secondary side economizer
Information
System Configuration
This example demonstrates the implementation of a chiller plant with water-side economizer (WSE) to cool a data center. The system schematics is as shown below.
The system is a primary-secondary chiller plant with two chillers and an integrated WSE.
Control Logic
This section describes the detailed control logic used in this chilled water plant system.
Cooling Mode Control
The chilled water system with integrated waterside economizer can run in three modes: free cooling (FC) mode, partially mechanical cooling (PMC) mode and fully mechanical cooling (FMC) mode. The detailed control logics about how to switch among these three cooling modes are described in Buildings.Applications.DataCenters.ChillerCooled.Controls.CoolingMode. Details on how the valves are operated under different cooling modes are presented in Buildings.Applications.DataCenters.ChillerCooled.Equipment.IntegratedPrimarySecondary.
Chiller Staging Control
The staging sequence of multiple chillers are descibed as below:
- The chillers are all off when cooling mode is FC.
- One chiller is commanded on when cooling mode is not FC.
- Two chillers are commanded on when cooling mode is not FC and the cooling load addressed by chillers is larger than a critical value.
The detailed implementation is shown in Buildings.Applications.DataCenters.ChillerCooled.Controls.ChillerStage.
Pump Staging Control
For constant speed pumps, the number of running pumps equals to the number of running chillers.
For variable speed pumps, the number of running pumps is controlled by the speed signal and the mass flow rate. Details are shown in Buildings.Applications.DataCenters.ChillerCooled.Controls.VariableSpeedPumpStage. And the speed is controlled by maintaining a fixed differential pressure between the outlet and inlet on the waterside of the Computer Room Air Handler (CRAH).
Cooling Tower Speed Control
The control logic for cooling tower fan speed is described as:
- When in FMC mode, the cooling tower speed is controlled to maintain the condenser water supply temperature (CWST) at its setpoint.
- When in PMC mode, the fan is enabled to run at 100% speed to make the condenser water as cold as possible and maximize the WSE output.
- When in FC mode, the fan speed is modulated to maintain chilled water supply temperature at its setpoint.
Detailed implementation of cooling tower speed control can be found in Buildings.Applications.DataCenters.ChillerCooled.Controls.CoolingTowerSpeed.
Room temperature control
The room temperature is controlled by adjusting the fan speed of the AHU using a PI controller.
Note that for simplicity, the chilled water supply temperature and differential pressure reset control are not implemented in this example.
Extends from Modelica.Icons.Example (Icon for runnable examples), Buildings.Applications.DataCenters.ChillerCooled.Examples.BaseClasses.PostProcess (Post-processing), Buildings.Applications.DataCenters.ChillerCooled.Examples.BaseClasses.PartialDataCenter (Partial model that impliments cooling system for data centers).
Parameters
Type | Name | Default | Description |
---|---|---|---|
replaceable package MediumA | Air | Medium model | |
replaceable package MediumW | Water | Medium model | |
Integer | numChi | 2 | Number of chillers |
MassFlowRate | m1_flow_chi_nominal | 34.7 | Nominal mass flow rate at condenser water in the chillers [kg/s] |
MassFlowRate | m2_flow_chi_nominal | 18.3 | Nominal mass flow rate at evaporator water in the chillers [kg/s] |
PressureDifference | dp1_chi_nominal | 46.2*1000 | Nominal pressure [Pa] |
PressureDifference | dp2_chi_nominal | 44.8*1000 | Nominal pressure [Pa] |
Power | QEva_nominal | m2_flow_chi_nominal*4200*(6.... | Nominal cooling capaciaty(Negative means cooling) [W] |
MassFlowRate | m1_flow_wse_nominal | 34.7 | Nominal mass flow rate at condenser water in the chillers [kg/s] |
MassFlowRate | m2_flow_wse_nominal | 35.3 | Nominal mass flow rate at condenser water in the chillers [kg/s] |
PressureDifference | dp1_wse_nominal | 33.1*1000 | Nominal pressure [Pa] |
PressureDifference | dp2_wse_nominal | 34.5*1000 | Nominal pressure [Pa] |
Generic | perPumCW[numChi] | Performance data for condenser water pumps | |
Time | tWai | 1200 | Waiting time [s] |
ThermalConductance | UA_nominal | numChi*QEva_nominal/Building... | Thermal conductance at nominal flow for sensible heat, used to compute time constant [W/K] |
MassFlowRate | mAir_flow_nominal | 161.35 | Nominal air mass flowrate [kg/s] |
Real | yValMinAHU | 0.1 | Minimum valve openning position [1] |
Temperature | TCHWSet | 273.15 + 8 | Chilled water temperature setpoint [K] |
Temperature | TSupAirSet | TCHWSet + 10 | Supply air temperature setpoint [K] |
Temperature | TRetAirSet | 273.15 + 25 | Supply air temperature setpoint [K] |
Pressure | dpSetPoi | 80000 | Differential pressure setpoint [Pa] |
Generic | perPumSec[numChi] | Performance data for secondary chilled water pumps | |
Generic | perPumPri[numChi] | Performance data for secondary chilled water pumps |
Connectors
Type | Name | Description |
---|---|---|
Bus | weaBus | Weather data bus |
Modelica definition
Buildings.Applications.DataCenters.ChillerCooled.Examples.NonIntegratedPrimarySecondaryEconomizer
Example that demonstrates a chiller plant with non-integrated primary-secondary side economizer
Information
System Configuration
This example demonstrates the implementation of a chiller plant with water-side economizer (WSE) to cool a data center. The system schematics is as shown below.
The system is a primary-secondary chiller plant with two chillers and a non-integrated WSE.
Control Logic
This section describes the detailed control logic used in this chilled water plant system.
Cooling Mode Control
The chilled water system with non-integrated waterside economizer can run in two modes: free cooling (FC) mode, and fully mechanical cooling (FMC) mode. The detailed control logics about how to switch between these two cooling modes are described in Buildings.Applications.DataCenters.ChillerCooled.Controls.CoolingModeNonIntegrated. Details on how the valves are operated under different cooling modes are presented in Buildings.Applications.DataCenters.ChillerCooled.Equipment.NonIntegrated.
Chiller Staging Control
The staging sequence of multiple chillers are descibed as below:
- The chillers are all off when cooling mode is FC.
- One chiller is commanded on when cooling mode is not FC.
- Two chillers are commanded on when cooling mode is not FC and the cooling load addressed by chillers is larger than a critical value.
The detailed implementation is shown in Buildings.Applications.DataCenters.ChillerCooled.Controls.ChillerStage.
Pump Staging Control
For constant speed pumps, the number of running pumps equals to the number of running chillers.
For variable speed pumps, the number of runing pumps is controlled by the speed signal and the mass flowrate. Details are shown in Buildings.Applications.DataCenters.ChillerCooled.Controls.VariableSpeedPumpStage. And the speed is controlled by maintaining a fixed differential pressure between the outlet and inlet on the waterside of the Computer Room Air Handler (CRAH).
Cooling Tower Speed Control
The control logic for cooling tower fan speed is described as:
- When in FMC mode, the cooling tower speed is controlled to maintain the condenser water supply temperature (CWST) at its setpoint.
- When in FC mode, the fan speed is modulated to maintain chilled water supply temperature at its setpoint.
Detailed implementation of cooling tower speed control can be found in Buildings.Applications.DataCenters.ChillerCooled.Controls.CoolingTowerSpeed.
Room temperature control
The room temperature is controlled by adjusting the fan speed of the AHU using a PI controller.
Note that for simplicity, the temperature and differential pressure reset control are not implemented in this example.
Extends from Modelica.Icons.Example (Icon for runnable examples), Buildings.Applications.DataCenters.ChillerCooled.Examples.BaseClasses.PostProcess (Post-processing), Buildings.Applications.DataCenters.ChillerCooled.Examples.BaseClasses.PartialDataCenter (Partial model that impliments cooling system for data centers).
Parameters
Type | Name | Default | Description |
---|---|---|---|
replaceable package MediumA | Air | Medium model | |
replaceable package MediumW | Water | Medium model | |
Integer | numChi | 2 | Number of chillers |
MassFlowRate | m1_flow_chi_nominal | 34.7 | Nominal mass flow rate at condenser water in the chillers [kg/s] |
MassFlowRate | m2_flow_chi_nominal | 18.3 | Nominal mass flow rate at evaporator water in the chillers [kg/s] |
PressureDifference | dp1_chi_nominal | 46.2*1000 | Nominal pressure [Pa] |
PressureDifference | dp2_chi_nominal | 44.8*1000 | Nominal pressure [Pa] |
Power | QEva_nominal | m2_flow_chi_nominal*4200*(6.... | Nominal cooling capaciaty(Negative means cooling) [W] |
MassFlowRate | m1_flow_wse_nominal | 34.7 | Nominal mass flow rate at condenser water in the chillers [kg/s] |
MassFlowRate | m2_flow_wse_nominal | 35.3 | Nominal mass flow rate at condenser water in the chillers [kg/s] |
PressureDifference | dp1_wse_nominal | 33.1*1000 | Nominal pressure [Pa] |
PressureDifference | dp2_wse_nominal | 34.5*1000 | Nominal pressure [Pa] |
Generic | perPumCW[numChi] | Performance data for condenser water pumps | |
Time | tWai | 1200 | Waiting time [s] |
ThermalConductance | UA_nominal | numChi*QEva_nominal/Building... | Thermal conductance at nominal flow for sensible heat, used to compute time constant [W/K] |
MassFlowRate | mAir_flow_nominal | 161.35 | Nominal air mass flowrate [kg/s] |
Real | yValMinAHU | 0.1 | Minimum valve openning position [1] |
Temperature | TCHWSet | 273.15 + 8 | Chilled water temperature setpoint [K] |
Temperature | TSupAirSet | TCHWSet + 10 | Supply air temperature setpoint [K] |
Temperature | TRetAirSet | 273.15 + 25 | Supply air temperature setpoint [K] |
Pressure | dpSetPoi | 80000 | Differential pressure setpoint [Pa] |
Generic | perPumSec[numChi] | Performance data for secondary chilled water pumps | |
Generic | perPumPri[numChi] | Performance data for secondary chilled water pumps |
Connectors
Type | Name | Description |
---|---|---|
Bus | weaBus | Weather data bus |