Buildings.Fluid.DataCenters.CDUs.LiquidToLiquid
Package with liquid-cooled CDUs
Information
This package contains component models for liquid-to-liquid CDUs.
Extends from Modelica.Icons.VariantsPackage (Icon for package containing variants).
Package Content
| Name | Description |
|---|---|
 CDU_epsNTU
|
CDU using epsilon-NTU for heat transfer |
 Data
|
Package with data records for racks |
 Examples
|
Collection of models that illustrate model use and test models |
Buildings.Fluid.DataCenters.CDUs.LiquidToLiquid.CDU_epsNTU
CDU using epsilon-NTU for heat transfer
Information
Model of a coolant distribution unit (CDU) with with a steady-state, counter-flow heat exchanger that uses the epsilon-NTU correlations.
This model configures the heat exchanger that is used in Buildings.Fluid.DataCenters.CDUs.BaseClasses.PartialCDU with a counter-flow heat exchanger that uses the ε-NTU relations, using an instance of Buildings.Fluid.HeatExchangers.PlateHeatExchangerEffectivenessNTU, and hence the heat transfer is calculated with convection coefficients that are a function of the mass flow rate.
See Buildings.Fluid.DataCenters.CDUs.BaseClasses.PartialCDU for a description of the CDU model.
Extends from Buildings.Fluid.DataCenters.CDUs.BaseClasses.PartialCDU (Partial model for a CDU).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| replaceable package MediumPla | PartialMedium | Medium in the plant-side component | |
| replaceable package MediumRac | PartialMedium | Medium in the rack-side component | |
| Generic_epsNTU | dat | Data record for performance characterization | |
| Boolean | addPowerToMedium | true | Set to false to avoid any power from the pump (=heat and flow work) being added to medium (may give simpler equations) |
| flowParameters | pumpHeadMonotone | Actual head of the pump, corrected to impose a minimum descent of the pump curve | |
| Valve controller | |||
| SimpleController | controllerTypeVal | Buildings.Controls.OBC.CDL.T... | Type of controller for valve |
| Real | kVal | 1 | Gain of controller for valve |
| Real | TiVal | 120 | Time constant of integrator block of valve controller |
| Real | TdVal | 0.1 | Time constant of derivative block for valve controller |
| Pump controller | |||
| SimpleController | controllerTypePum | Buildings.Controls.OBC.CDL.T... | Type of controller for pump |
| Real | kPum | 1 | Gain of controller for pump |
| Real | TiPum | 120 | Time constant of integrator block of pump controller |
| Real | TdPum | 0.1 | Time constant of derivative block for pump controller |
| Assumptions | |||
| Boolean | allowFlowReversalPla | true | = false to simplify equations, assuming, but not enforcing, no flow reversal for plant-side medium |
| Boolean | allowFlowReversalRac | true | = false to simplify equations, assuming, but not enforcing, no flow reversal for rack-side medium |
| Advanced | |||
| MassFlowRate | mPla_flow_small | 1E-4*abs(mPla_flow_nominal) | Small mass flow rate for regularization of zero flow [kg/s] |
| MassFlowRate | mRac_flow_small | 1E-4*abs(mRac_flow_nominal) | Small mass flow rate for regularization of zero flow [kg/s] |
| Diagnostics | |||
| Boolean | show_T | false | = true, if actual temperature at port is computed |
| Boolean | checkMedia | true | Set to false to disable media consistency check |
| Flow resistance | |||
| Medium 1 | |||
| Boolean | computeFlowResistancePla | true | =true, compute flow resistance. Set to false to assume no friction |
| Boolean | from_dpPla | false | = true, use m_flow = f(dp) else dp = f(m_flow) |
| Boolean | linearizeFlowResistancePla | false | = true, use linear relation between m_flow and dp for any flow rate |
| Medium 2 | |||
| Boolean | computeFlowResistanceRac | true | =true, compute flow resistance. Set to false to assume no friction |
| Boolean | from_dpRac | false | = true, use m_flow = f(dp) else dp = f(m_flow) |
| Boolean | linearizeFlowResistanceRac | false | = true, use linear relation between m_flow and dp for any flow rate |
| Dynamics | |||
| Valve | |||
| Boolean | use_strokeTime | true | Set to true to continuously open and close valve using strokeTime from instance dat |
| Init | initVal | Modelica.Blocks.Types.Init.I... | Type of initialization (no init/steady state/initial state/initial output) |
| Real | yVal_start | 1 | Initial position of actuator |
| Pump | |||
| Dynamics | energyDynamics | Modelica.Fluid.Types.Dynamic... | Type of energy balance: dynamic (3 initialization options) or steady state |
| Time | tau | 1 | Time constant of fluid volume for nominal flow, used if energy or mass balance is dynamic [s] |
| Boolean | use_riseTime | true | Set to true to continuously change motor speed using risetime from instance dat |
| Real | yPum_start | 0 | Initial value of speed |
Connectors
| Type | Name | Description |
|---|---|---|
| FluidPort_a | port_aPla | Fluid connector aPla (positive design flow direction is from port_aPla to port_bPla) |
| FluidPort_b | port_bPla | Fluid connector bPla (positive design flow direction is from port_aPla to port_bPla) |
| FluidPort_a | port_aRac | Fluid connector aRac (positive design flow direction is from port_aRac to port_bRac) |
| FluidPort_b | port_bRac | Fluid connector bRac (positive design flow direction is from port_aRac to port_bRac) |
| input RealInput | TSet | Set point temperature for water leaving to the IT rack [K] |
| input RealInput | dpSet | Set point for static pressure provided by CDU [Pa] |
| output RealOutput | P | Electrical power consumed by pump [W] |
Modelica definition
model CDU_epsNTU "CDU using epsilon-NTU for heat transfer"
extends Buildings.Fluid.DataCenters.CDUs.BaseClasses.PartialCDU
(
redeclare Fluid.HeatExchangers.PlateHeatExchangerEffectivenessNTU hex(
final from_dp1=from_dpPla,
final dp1_nominal=dat.dpHexPla_nominal,
final linearizeFlowResistance1=linearizeFlowResistancePla,
final n1=dat.nPla,
final deltaM1=dat.deltaMPla,
final from_dp2=from_dpRac,
final dp2_nominal=dat.dpHexRac_nominal,
final linearizeFlowResistance2=linearizeFlowResistanceRac,
final n2=dat.nRac,
final deltaM2=dat.deltaMRac,
configuration=Buildings.Fluid.Types.HeatExchangerConfiguration.CounterFlow,
final use_Q_flow_nominal=true,
final Q_flow_nominal=dat.Q_flow_nominal,
final T_a1_nominal=dat.TPlaIn_nominal,
final T_a2_nominal=dat.TRacIn_nominal,
final r_nominal=dat.r_nominal,
final nCon1=dat.nConPla,
final nCon2=dat.nConRac));
end CDU_epsNTU;