modelCarnotWithLosses
Reversible chiller using Carnot approach with losses (frost, heat, inertia)
Extends from Buildings.Fluid.Chillers.ModularReversible.Modular (Grey-box model for reversible and non-reversible chillers).
Information
Model of a reversible chiller.
This model extends Buildings.Fluid.Chillers.ModularReversible.Modular and selects the constant Carnot effectiveness module for chillers ( Buildings.Fluid.Chillers.ModularReversible.RefrigerantCycle.ConstantCarnotEffectiveness) and heat pumps ( Buildings.Fluid.HeatPumps.ModularReversible.RefrigerantCycle.ConstantCarnotEffectiveness) to model a reversible chiller. For the heating operation, the nominal approach temperatures are used as a constant to avoid nonlinear system of equations.
Furthermore, losses are enabled to model the chiller with a more realistic behaviour:
- Heat losses to the ambient (can be disabled)
- Refrigerant inertia using a first order delay
- Evaporator frosting assuming an air-sink chiller
For more information, see Buildings.Fluid.HeatPumps.ModularReversible.UsersGuide.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Boolean | use_rev (from PartialReversibleRefrigerantMachine) | true | =true if the chiller or heat pump is reversible |
| Buildings.Fluid.HeatPumps.ModularReversible.Controls.Safety.Data.Wuellhorst2021 | safCtrPar (from PartialReversibleRefrigerantMachine) | ||
| Modelica.Units.SI.Density | rhoCon (from PartialReversibleRefrigerantMachine) | MediumCon.density(staCon_nominal) | Condenser medium density |
| Modelica.Units.SI.SpecificHeatCapacity | cpCon (from PartialReversibleRefrigerantMachine) | MediumCon.specificHeatCapacityCp(staCon_nominal) | Condenser medium specific heat capacity |
| Modelica.Units.SI.Density | rhoEva (from PartialReversibleRefrigerantMachine) | MediumEva.density(staEva_nominal) | Evaporator medium density |
| Modelica.Units.SI.SpecificHeatCapacity | cpEva (from PartialReversibleRefrigerantMachine) | MediumEva.specificHeatCapacityCp(staEva_nominal) | Evaporator medium specific heat capacity |
| Real | etaCarnot_nominal | 0.3 | Constant Carnot effectiveness |
| Assumptions | |||
| Boolean | allowFlowReversal1 (from PartialFourPort) | true | = false to simplify equations, assuming, but not enforcing, no flow reversal for medium 1 |
| Boolean | allowFlowReversal2 (from PartialFourPort) | true | = false to simplify equations, assuming, but not enforcing, no flow reversal for medium 2 |
| Nominal condition | |||
| Modelica.Units.SI.MassFlowRate | m1_flow_nominal (from PartialFourPortInterface) | Nominal mass flow rate | |
| Modelica.Units.SI.MassFlowRate | m2_flow_nominal (from PartialFourPortInterface) | Nominal mass flow rate | |
| Modelica.Units.SI.HeatFlowRate | PEle_nominal (from PartialReversibleRefrigerantMachine) | Nominal electrical power consumption | |
| Modelica.Units.SI.HeatFlowRate | QCoo_flow_nominal (from Modular) | Nominal cooling capcaity | |
| Modelica.Units.SI.Temperature | TEvaCoo_nominal (from Modular) | Nominal temperature of the cooled fluid during cooling mode | |
| Modelica.Units.SI.Temperature | TConCoo_nominal (from Modular) | Nominal temperature of the heated fluid during cooling mode | |
| Modelica.Units.SI.TemperatureDifference | TAppCon_nominal | if cpCon < 1500 then 5 else 2 | Temperature difference between refrigerant and working fluid outlet in condenser |
| Modelica.Units.SI.TemperatureDifference | TAppEva_nominal | if cpEva < 1500 then 5 else 2 | Temperature difference between refrigerant and working fluid outlet in evaporator |
| Advanced | |||
| Medium1.MassFlowRate | m1_flow_small (from PartialFourPortInterface) | 1E-4*abs(m1_flow_nominal) | Small mass flow rate for regularization of zero flow |
| Medium2.MassFlowRate | m2_flow_small (from PartialFourPortInterface) | 1E-4*abs(m2_flow_nominal) | Small mass flow rate for regularization of zero flow |
| Boolean | allowDifferentDeviceIdentifiers (from PartialReversibleRefrigerantMachine) | false | if use_rev=true, device data for cooling and heating need to entered. Set allowDifferentDeviceIdentifiers=true to allow different device identifiers devIde |
| Boolean | calEff (from PartialReversibleRefrigerantMachine) | true | =false to disable efficiency calculation, may speed up the simulation |
| Real | limWarSca (from PartialReversibleRefrigerantMachine) | 0.05 | Allowed difference in scaling '|scaFacHea - scaFacCoo| / scaFacHea', if exceeded, a warning will be issued |
| Advanced › Diagnostics | |||
| Boolean | show_T (from PartialFourPortInterface) | false | = true, if actual temperature at port is computed |
| Real | ySet_small (from PartialReversibleRefrigerantMachine) | 0.01 | Threshold for relative speed for the device to be considered on |
| Safety control | |||
| Boolean | use_intSafCtr (from PartialReversibleRefrigerantMachine) | true | =true to enable internal safety control |
| Condenser › Dynamics | |||
| Modelica.Units.SI.Time | tauCon (from PartialReversibleRefrigerantMachine) | 30 | Condenser heat transfer time constant at nominal flow |
| Nominal condition - Pressure losses | |||
| Modelica.Units.SI.TemperatureDifference | dTCon_nominal (from PartialReversibleRefrigerantMachine) | Nominal temperature difference in condenser medium, used to calculate mass flow rate | |
| Modelica.Units.SI.MassFlowRate | mCon_flow_nominal (from PartialReversibleRefrigerantMachine) | Nominal mass flow rate of the condenser medium | |
| Modelica.Units.SI.PressureDifference | dpCon_nominal (from PartialReversibleRefrigerantMachine) | Pressure drop at nominal mass flow rate | |
| Modelica.Units.SI.TemperatureDifference | dTEva_nominal (from PartialReversibleRefrigerantMachine) | Nominal temperature difference in evaporator medium, used to calculate mass flow rate | |
| Modelica.Units.SI.MassFlowRate | mEva_flow_nominal (from PartialReversibleRefrigerantMachine) | Nominal mass flow rate of the evaporator medium | |
| Modelica.Units.SI.PressureDifference | dpEva_nominal (from PartialReversibleRefrigerantMachine) | Pressure drop at nominal mass flow rate | |
| Condenser › Flow resistance | |||
| Real | deltaMCon (from PartialReversibleRefrigerantMachine) | 0.1 | Fraction of nominal mass flow rate where transition to turbulent occurs |
| Real | nCon (from PartialReversibleRefrigerantMachine) | 2 | Flow exponent, n=1 for laminar, n=2 for turbulent |
| Condenser › Heat Losses | |||
| Boolean | use_conCap (from PartialReversibleRefrigerantMachine) | true | =true if using capacitor model for condenser heat loss estimation |
| Modelica.Units.SI.HeatCapacity | CCon (from PartialReversibleRefrigerantMachine) | 0 | Heat capacity of the condenser |
| Modelica.Units.SI.ThermalConductance | GConOut (from PartialReversibleRefrigerantMachine) | 0 | Outer thermal conductance for condenser heat loss calculations |
| Modelica.Units.SI.ThermalConductance | GConIns (from PartialReversibleRefrigerantMachine) | 0 | Inner thermal conductance for condenser heat loss calculations |
| Evaporator › Dynamics | |||
| Modelica.Units.SI.Time | tauEva (from PartialReversibleRefrigerantMachine) | 30 | Evaporator heat transfer time constant at nominal flow |
| Evaporator › Flow resistance | |||
| Real | deltaMEva (from PartialReversibleRefrigerantMachine) | 0.1 | Fraction of nominal mass flow rate where transition to turbulent occurs |
| Real | nEva (from PartialReversibleRefrigerantMachine) | 2 | Flow exponent, n=1 for laminar, n=2 for turbulent |
| Evaporator › Heat Losses | |||
| Boolean | use_evaCap (from PartialReversibleRefrigerantMachine) | true | =true if using capacitor model for evaporator heat loss estimation |
| Modelica.Units.SI.HeatCapacity | CEva (from PartialReversibleRefrigerantMachine) | 0 | Heat capacity of the evaporator |
| Modelica.Units.SI.ThermalConductance | GEvaOut (from PartialReversibleRefrigerantMachine) | 0 | Outer thermal conductance for evaporator heat loss calculations |
| Modelica.Units.SI.ThermalConductance | GEvaIns (from PartialReversibleRefrigerantMachine) | 0 | Inner thermal conductance for evaporator heat loss calculations |
| Assumptions › Evaporator | |||
| Boolean | allowFlowReversalEva (from PartialReversibleRefrigerantMachine) | true | = false to simplify equations, assuming, but not enforcing, no flow reversal |
| Assumptions › Condenser | |||
| Boolean | allowFlowReversalCon (from PartialReversibleRefrigerantMachine) | true | = false to simplify equations, assuming, but not enforcing, no flow reversal |
| Initialization › Parameters | |||
| Modelica.Blocks.Types.Init | initType (from PartialReversibleRefrigerantMachine) | Modelica.Blocks.Types.Init.InitialState | Type of initialization for refrigerant cycle dynamics (InitialState and InitialOutput are identical) |
| Initialization › Condenser | |||
| Modelica.Media.Interfaces.Types.AbsolutePressure | pCon_start (from PartialReversibleRefrigerantMachine) | MediumCon.p_default | Start value of pressure |
| Modelica.Media.Interfaces.Types.Temperature | TCon_start (from PartialReversibleRefrigerantMachine) | MediumCon.T_default | Start value of temperature |
| Modelica.Units.SI.Temperature | TConCap_start (from PartialReversibleRefrigerantMachine) | MediumCon.T_default | Initial temperature of heat capacity of condenser |
| Modelica.Media.Interfaces.Types.MassFraction[MediumCon.nX] | XCon_start (from PartialReversibleRefrigerantMachine) | MediumCon.X_default | Start value of mass fractions m_i/m |
| Initialization › Evaporator | |||
| Modelica.Media.Interfaces.Types.AbsolutePressure | pEva_start (from PartialReversibleRefrigerantMachine) | MediumEva.p_default | Start value of pressure |
| Modelica.Media.Interfaces.Types.Temperature | TEva_start (from PartialReversibleRefrigerantMachine) | MediumEva.T_default | Start value of temperature |
| Modelica.Units.SI.Temperature | TEvaCap_start (from PartialReversibleRefrigerantMachine) | MediumEva.T_default | Initial temperature of heat capacity at evaporator |
| Modelica.Media.Interfaces.Types.MassFraction[MediumEva.nX] | XEva_start (from PartialReversibleRefrigerantMachine) | MediumEva.X_default | Start value of mass fractions m_i/m |
| Dynamics › Equation | |||
| Modelica.Fluid.Types.Dynamics | energyDynamics (from PartialReversibleRefrigerantMachine) | Modelica.Fluid.Types.Dynamics.DynamicFreeInitial | Type of energy balance: dynamic (3 initialization options) or steady state (only affects fluid-models) |
| Advanced › Flow resistance | |||
| Boolean | from_dp (from PartialReversibleRefrigerantMachine) | false | = true, use m_flow = f(dp) else dp = f(m_flow) |
| Boolean | linearized (from PartialReversibleRefrigerantMachine) | false | = true, use linear relation between m_flow and dp for any flow rate |
| Nominal condition - Heating | |||
| Modelica.Units.SI.HeatFlowRate | QHea_flow_nominal (from Modular) | 0 | Nominal heating capacity |
| Modelica.Units.SI.Temperature | TEvaHea_nominal (from Modular) | Nominal temperature of the heated fluid during heating mode | |
| Modelica.Units.SI.Temperature | TConHea_nominal (from Modular) | Nominal temperature of the cooled fluid during heating mode | |
| Refrigerant cycle inertia | |||
| Modelica.Units.SI.Time | refIneTimCon | 300 | Refrigerant cycle inertia time constant for first order delay |
| Integer | nthOrd | 1 | Order of refrigerant cycle interia |
Connectors
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Medium1.MassFlowRate | m1_flow (from PartialFourPortInterface) | port_a1.m_flow | Mass flow rate from port_a1 to port_b1 (m1_flow > 0 is design flow direction) |
| Modelica.Units.SI.PressureDifference | dp1 (from PartialFourPortInterface) | port_a1.p - port_b1.p | Pressure difference between port_a1 and port_b1 |
| Medium2.MassFlowRate | m2_flow (from PartialFourPortInterface) | port_a2.m_flow | Mass flow rate from port_a2 to port_b2 (m2_flow > 0 is design flow direction) |
| Modelica.Units.SI.PressureDifference | dp2 (from PartialFourPortInterface) | port_a2.p - port_b2.p | Pressure difference between port_a2 and port_b2 |
| Medium1.ThermodynamicState | sta_a1 (from PartialFourPortInterface) | if allowFlowReversal1 then Medium1.setState_phX(port_a1.p, noEvent(actualStream(port_a1.h_outflow)), noEvent(actualStream(port_a1.Xi_outflow))) else Medium1.setState_phX(port_a1.p, inStream(port_a1.h_outflow), inStream(port_a1.Xi_outflow)) | Medium properties in port_a1 |
| Medium1.ThermodynamicState | sta_b1 (from PartialFourPortInterface) | if allowFlowReversal1 then Medium1.setState_phX(port_b1.p, noEvent(actualStream(port_b1.h_outflow)), noEvent(actualStream(port_b1.Xi_outflow))) else Medium1.setState_phX(port_b1.p, port_b1.h_outflow, port_b1.Xi_outflow) | Medium properties in port_b1 |
| Medium2.ThermodynamicState | sta_a2 (from PartialFourPortInterface) | if allowFlowReversal2 then Medium2.setState_phX(port_a2.p, noEvent(actualStream(port_a2.h_outflow)), noEvent(actualStream(port_a2.Xi_outflow))) else Medium2.setState_phX(port_a2.p, inStream(port_a2.h_outflow), inStream(port_a2.Xi_outflow)) | Medium properties in port_a2 |
| Medium2.ThermodynamicState | sta_b2 (from PartialFourPortInterface) | if allowFlowReversal2 then Medium2.setState_phX(port_b2.p, noEvent(actualStream(port_b2.h_outflow)), noEvent(actualStream(port_b2.Xi_outflow))) else Medium2.setState_phX(port_b2.p, port_b2.h_outflow, port_b2.Xi_outflow) | Medium properties in port_b2 |
| PartialModularRefrigerantCycle | refCyc (from PartialReversibleRefrigerantMachine) | ||
| Modelica.Units.SI.HeatFlowRate | Q1_flow (from PartialReversibleRefrigerantMachine) | QCon_flow | Heat transferred into the medium 1 |
| Modelica.Units.SI.HeatFlowRate | Q2_flow (from PartialReversibleRefrigerantMachine) | QEva_flow | Heat transferred into the medium 2 |
| Buildings.Fluid.HeatPumps.ModularReversible.BaseClasses.EvaporatorCondenserWithCapacity | con (from PartialReversibleRefrigerantMachine) | Heat exchanger model for the condenser | |
| Buildings.Fluid.HeatPumps.ModularReversible.BaseClasses.EvaporatorCondenserWithCapacity | eva (from PartialReversibleRefrigerantMachine) | Heat exchanger model for the evaporator | |
| Buildings.HeatTransfer.Sources.PrescribedTemperature | varTOutEva (from PartialReversibleRefrigerantMachine) | Forces heat losses according to ambient temperature | |
| Buildings.HeatTransfer.Sources.PrescribedTemperature | varTOutCon (from PartialReversibleRefrigerantMachine) | Forces heat losses according to ambient temperature | |
| Buildings.Fluid.HeatPumps.ModularReversible.Controls.Safety.Safety | safCtr (from PartialReversibleRefrigerantMachine) | Safety control models | |
| Buildings.Fluid.Sensors.MassFlowRate | mEva_flow (from PartialReversibleRefrigerantMachine) | Mass flow sensor at the evaporator | |
| Buildings.Fluid.Sensors.MassFlowRate | mCon_flow (from PartialReversibleRefrigerantMachine) | Mass flow sensor at the condenser | |
| RefrigerantCycleInertia | refCycIneCon (from PartialReversibleRefrigerantMachine) | Inertia model for condenser side | |
| RefrigerantCycleInertia | refCycIneEva (from PartialReversibleRefrigerantMachine) | Inertia model for evaporator side | |
| Modelica.Blocks.Sources.RealExpression | senTConIn (from PartialReversibleRefrigerantMachine) | Real expression for condenser inlet temperature | |
| Modelica.Blocks.Sources.RealExpression | senTEvaIn (from PartialReversibleRefrigerantMachine) | Real expression for evaporator inlet temperature | |
| Buildings.Fluid.HeatPumps.ModularReversible.BaseClasses.CalculateEfficiency | eff (from PartialReversibleRefrigerantMachine) | Calculate efficiencies of device | |
| Modelica.Blocks.Sources.BooleanConstant | conCoo (from Modular) | Locks the device in cooling mode if designated to be not reversible | |
| Modelica.Blocks.Logical.Not | notCoo (from Modular) | Not cooling is heating | |
| Modelica.Blocks.Logical.Hysteresis | hys (from Modular) | Outputs whether the device is on based on the relative speed |
Revisions
-
October 2, 2022 by Fabian Wuellhorst:
First implementation (see issue #1576)