modelPartialIndirect
Partial indirect energy transfer station for district energy systems
Extends from Buildings.DHC.ETS.BaseClasses.PartialETS (Partial class for modeling an energy transfer station).
Information
Indirect cooling energy transfer station (ETS) model that controls the building chilled water supply temperature by modulating a primary control valve on the district supply side. The design is based on a typical district cooling ETS described in ASHRAE's District Cooling Guide. As shown in the figure below, the building pumping design (constant/variable) is specified on the building side and not within the ETS.
Reference
American Society of Heating, Refrigeration and Air-Conditioning Engineers. (2019). Chapter 5: End User Interface. In District Cooling Guide, Second Edition and Owner's Guide for Buildings Served by District Cooling.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Buildings.Fluid.Data.Fuels.Generic[nFue] | fue (from PartialETS) | Fuel type | |
| Configuration | |||
| TypDisSys | typ (from PartialETS) | Buildings.DHC.Types.DistrictSystemType.CombinedGeneration2to4 | Type of district system |
| Integer | nPorts_aHeaWat (from PartialETS) | 0 | Number of heating water return ports |
| Integer | nPorts_bHeaWat (from PartialETS) | 0 | Number of heating water supply ports |
| Integer | nPorts_aChiWat (from PartialETS) | 0 | Number of chilled water return ports |
| Integer | nPorts_bChiWat (from PartialETS) | 0 | Number of chilled water supply ports |
| Boolean | have_heaWat (from PartialETS) | false | Set to true if the ETS supplies heating water |
| Boolean | have_hotWat (from PartialETS) | false | Set to true if the ETS supplies hot water |
| Boolean | have_chiWat (from PartialETS) | false | Set to true if the ETS supplies chilled water |
| Boolean | have_fan (from PartialETS) | false | Set to true if fan power is computed |
| Boolean | have_pum (from PartialETS) | false | Set to true if pump power is computed |
| Boolean | have_eleHea (from PartialETS) | false | Set to true if the ETS has electric heating system |
| Integer | nFue (from PartialETS) | 0 | Number of fuel types (0 means no combustion system) |
| Boolean | have_eleCoo (from PartialETS) | false | Set to true if the ETS has electric cooling system |
| Boolean | have_weaBus (from PartialETS) | false | Set to true to use a weather bus |
| Assumptions | |||
| Boolean | allowFlowReversalSer (from PartialETS) | false | Set to true to allow flow reversal on service side |
| Boolean | allowFlowReversalBui (from PartialETS) | false | Set to true to allow flow reversal on building side |
| Nominal condition | |||
| Modelica.Units.SI.HeatFlowRate | QHeaWat_flow_nominal (from PartialETS) | 0 | Nominal capacity of heating system (>=0) |
| Modelica.Units.SI.HeatFlowRate | QHotWat_flow_nominal (from PartialETS) | 0 | Nominal capacity of hot water production system (>=0) |
| Modelica.Units.SI.HeatFlowRate | QChiWat_flow_nominal (from PartialETS) | 0 | Nominal capacity of cooling system (<=0) |
| Modelica.Units.SI.MassFlowRate | mDis_flow_nominal | Nominal mass flow rate of district side | |
| Modelica.Units.SI.MassFlowRate | mBui_flow_nominal | Nominal mass flow rate of building side | |
| Modelica.Units.SI.PressureDifference | dpConVal_nominal | 6000 | Nominal pressure drop of fully open control valve |
| Heat exchanger | |||
| Modelica.Units.SI.PressureDifference | dp1_nominal | Nominal pressure difference on primary side | |
| Modelica.Units.SI.PressureDifference | dp2_nominal | Nominal pressure difference on secondary side | |
| Boolean | use_Q_flow_nominal | true | Set to true to specify Q_flow_nominal and temeratures, or to false to specify effectiveness |
| Modelica.Units.SI.HeatFlowRate | Q_flow_nominal | Nominal heat transfer (positive for heat transfer from district to building) | |
| Modelica.Units.SI.Temperature | T_a1_nominal | Nominal temperature at port a1 (district supply) | |
| Modelica.Units.SI.Temperature | T_a2_nominal | Nominal temperature at port a2 (building return) | |
| Modelica.Units.SI.Efficiency | eta | 0.8 | Constant effectiveness |
| PID controller | |||
| Modelica.Blocks.Types.SimpleController | controllerType | Modelica.Blocks.Types.SimpleController.PI | Type of controller |
| Real | k | 1 | Gain of controller |
| Modelica.Units.SI.Time | Ti | 120 | Time constant of integrator block |
| Modelica.Units.SI.Time | Td | 0.1 | Time constant of derivative block |
| Real | yMax | 1 | Upper limit of output |
| Real | yMin | 0.01 | Lower limit of output |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Fluid.Interfaces.FluidPorts_a[nPorts_aHeaWat] | ports_aHeaWat (from PartialETS) | Fluid connectors for heating water return (from building) | |
| Modelica.Fluid.Interfaces.FluidPorts_b[nPorts_bHeaWat] | ports_bHeaWat (from PartialETS) | Fluid connectors for heating water supply (to building) | |
| Modelica.Fluid.Interfaces.FluidPorts_a[nPorts_aChiWat] | ports_aChiWat (from PartialETS) | Fluid connectors for chilled water return (from building) | |
| Modelica.Fluid.Interfaces.FluidPorts_b[nPorts_bChiWat] | ports_bChiWat (from PartialETS) | Fluid connectors for chilled water supply (to building) | |
| Modelica.Fluid.Interfaces.FluidPort_a | port_aSerAmb (from PartialETS) | Fluid connector for ambient water service supply line | |
| Modelica.Fluid.Interfaces.FluidPort_b | port_bSerAmb (from PartialETS) | Fluid connector for ambient water service return line | |
| Modelica.Fluid.Interfaces.FluidPort_a | port_aSerHea (from PartialETS) | Fluid connector for heating service supply line | |
| Modelica.Fluid.Interfaces.FluidPort_b | port_bSerHea (from PartialETS) | Fluid connector for heating service return line | |
| Modelica.Fluid.Interfaces.FluidPort_a | port_aSerCoo (from PartialETS) | Fluid connector for cooling service supply line | |
| Modelica.Fluid.Interfaces.FluidPort_b | port_bSerCoo (from PartialETS) | Fluid connector for cooling service return line | |
| Buildings.Controls.OBC.CDL.Interfaces.RealOutput | PHea (from PartialETS) | Power drawn by heating system | |
| Buildings.Controls.OBC.CDL.Interfaces.RealOutput | PCoo (from PartialETS) | Power drawn by cooling system | |
| Buildings.Controls.OBC.CDL.Interfaces.RealOutput | PFan (from PartialETS) | Power drawn by fan motors | |
| Buildings.Controls.OBC.CDL.Interfaces.RealOutput | PPum (from PartialETS) | Power drawn by pump motors | |
| Buildings.Controls.OBC.CDL.Interfaces.RealOutput[nFue] | QFue_flow (from PartialETS) | Fuel energy input rate | |
| BoundaryConditions.WeatherData.Bus | weaBus (from PartialETS) | Weather data bus | |
| Modelica.Blocks.Interfaces.RealInput | TBuiSupSet | Setpoint temperature for building supply | |
| Modelica.Blocks.Interfaces.RealOutput | Q_flow | Measured heating demand at the ETS | |
| Modelica.Blocks.Interfaces.RealOutput | Q | Measured energy consumption at the ETS |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Buildings.Fluid.Sensors.TemperatureTwoPort | senTDisSup | District supply temperature sensor | |
| Buildings.Fluid.Sensors.MassFlowRate | senMasFlo | District supply mass flow rate sensor | |
| Buildings.Fluid.Actuators.Valves.TwoWayEqualPercentage | conVal | Control valve | |
| Buildings.Fluid.HeatExchangers.PlateHeatExchangerEffectivenessNTU | hex | Heat exchanger | |
| Buildings.Fluid.Sensors.TemperatureTwoPort | senTDisRet | District return temperature sensor | |
| Buildings.Fluid.Sensors.TemperatureTwoPort | senTBuiRet | Building return temperature sensor | |
| Buildings.Fluid.Sensors.TemperatureTwoPort | senTBuiSup | Building supply temperature sensor | |
| Controls.OBC.CDL.Reals.PID | con | Building supply temperature controller | |
| Modelica.Blocks.Math.Add | dTDis | Temperature difference on the district side | |
| Modelica.Blocks.Math.Product | pro | product | |
| Modelica.Blocks.Math.Gain | cp | Specific heat multiplier to calculate heat flow rate | |
| Modelica.Blocks.Continuous.Integrator | int | Integration |
Revisions
-
March 11, 2024, by Michael Wetter:
Corrected wrongdisplayUnitstring. -
April 7, 2023, by David Blum:
Changed to partial base class for indirect so can extend to heating and cooling ETS. -
January 11, 2023, by Michael Wetter:
Changed controls to use CDL. Changed PID to PI as default for controller. -
March 21, 2022, by Chengnan Shi:
Update with base class partial model. - Novermber 13, 2019, by Kathryn Hinkelman:
First implementation.