modelPartialCarnot_T
Partial model for chiller with performance curve adjusted based on Carnot efficiency
Extends from Buildings.Fluid.Chillers.BaseClasses.Carnot.
Information
This is a partial model of a chiller whose coefficient of performance (COP) changes with temperatures in the same way as the Carnot efficiency changes. This base class is used for the Carnot chiller and Carnot heat pump that uses the compressor part load ratio as the control signal.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Boolean | homotopyInitialization (from Carnot) | true | = true, use homotopy method |
| 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 | QEva_flow_nominal (from Carnot) | Nominal cooling heat flow rate (QEva_flow_nominal < 0) | |
| Modelica.Units.SI.HeatFlowRate | QCon_flow_nominal (from Carnot) | Nominal heating flow rate | |
| Modelica.Units.SI.TemperatureDifference | dTEva_nominal (from Carnot) | -10 | Temperature difference evaporator outlet-inlet |
| Modelica.Units.SI.TemperatureDifference | dTCon_nominal (from Carnot) | 10 | Temperature difference condenser outlet-inlet |
| Modelica.Units.SI.Pressure | dp1_nominal (from Carnot) | Pressure difference over condenser | |
| Modelica.Units.SI.Pressure | dp2_nominal (from Carnot) | Pressure difference over 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 |
| Advanced › Diagnostics | |||
| Boolean | show_T (from PartialFourPortInterface) | false | = true, if actual temperature at port is computed |
| Efficiency | |||
| Boolean | use_eta_Carnot_nominal (from Carnot) | true | Set to true to use Carnot effectiveness etaCarnot_nominal rather than COP_nominal |
| Real | etaCarnot_nominal (from Carnot) | 0.3 | Carnot effectiveness (=COP/COP_Carnot) used during simulation if use_eta_Carnot_nominal = true |
| Real | COP_nominal (from Carnot) | etaCarnot_nominal*TUseAct_nominal/(TCon_nominal + TAppCon_nominal - (TEva_nominal - TAppEva_nominal)) | Coefficient of performance at TEva_nominal and TCon_nominal, used during simulation if use_eta_Carnot_nominal = false |
| Modelica.Units.SI.Temperature | TCon_nominal (from Carnot) | 303.15 | Condenser temperature used to compute COP_nominal if use_eta_Carnot_nominal=false |
| Modelica.Units.SI.Temperature | TEva_nominal (from Carnot) | 278.15 | Evaporator temperature used to compute COP_nominal if use_eta_Carnot_nominal=false |
| Real[:] | a (from Carnot) | {1} | Coefficients for efficiency curve (need p(a=a, yPL=1)=1) |
| Modelica.Units.SI.TemperatureDifference | TAppCon_nominal (from Carnot) | if cp1_default < 1500 then 5 else 2 | Temperature difference between refrigerant and working fluid outlet in condenser |
| Modelica.Units.SI.TemperatureDifference | TAppEva_nominal (from Carnot) | if cp2_default < 1500 then 5 else 2 | Temperature difference between refrigerant and working fluid outlet in evaporator |
| Flow resistance › Condenser | |||
| Boolean | from_dp1 (from Carnot) | false | = true, use m_flow = f(dp) else dp = f(m_flow) |
| Real | n1 (from Carnot) | 2 | Flow exponent, n1=1 for laminar, n1=2 for turbulent |
| Boolean | linearizeFlowResistance1 (from Carnot) | false | = true, use linear relation between m_flow and dp for any flow rate |
| Real | deltaM1 (from Carnot) | 0.1 | Fraction of nominal flow rate where flow transitions to laminar |
| Flow resistance › Evaporator | |||
| Boolean | from_dp2 (from Carnot) | false | = true, use m_flow = f(dp) else dp = f(m_flow) |
| Real | n2 (from Carnot) | 2 | Flow exponent, n2=1 for laminar, n2=2 for turbulent |
| Boolean | linearizeFlowResistance2 (from Carnot) | false | = true, use linear relation between m_flow and dp for any flow rate |
| Real | deltaM2 (from Carnot) | 0.1 | Fraction of nominal flow rate where flow transitions to laminar |
| Dynamics › Condenser | |||
| Modelica.Units.SI.Time | tau1 (from Carnot) | 60 | Time constant at nominal flow rate (used if energyDynamics1 <> Modelica.Fluid.Types.Dynamics.SteadyState) |
| Modelica.Units.SI.Temperature | T1_start (from Carnot) | Medium1.T_default | Initial or guess value of set point |
| Dynamics › Evaporator | |||
| Modelica.Units.SI.Time | tau2 (from Carnot) | 60 | Time constant at nominal flow rate (used if energyDynamics2 <> Modelica.Fluid.Types.Dynamics.SteadyState) |
| Modelica.Units.SI.Temperature | T2_start (from Carnot) | Medium2.T_default | Initial or guess value of set point |
| Dynamics › Evaporator and condenser | |||
| Modelica.Fluid.Types.Dynamics | energyDynamics (from Carnot) | Modelica.Fluid.Types.Dynamics.SteadyState | Type of energy balance: dynamic (3 initialization options) or steady state |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Fluid.Interfaces.FluidPort_a | port_a1 (from PartialFourPort) | Fluid connector a1 (positive design flow direction is from port_a1 to port_b1) | |
| Modelica.Fluid.Interfaces.FluidPort_b | port_b1 (from PartialFourPort) | Fluid connector b1 (positive design flow direction is from port_a1 to port_b1) | |
| Modelica.Fluid.Interfaces.FluidPort_a | port_a2 (from PartialFourPort) | Fluid connector a2 (positive design flow direction is from port_a2 to port_b2) | |
| Modelica.Fluid.Interfaces.FluidPort_b | port_b2 (from PartialFourPort) | Fluid connector b2 (positive design flow direction is from port_a2 to port_b2) | |
| Modelica.Blocks.Interfaces.RealOutput | QCon_flow (from Carnot) | Actual heating heat flow rate added to fluid 1 | |
| Modelica.Blocks.Interfaces.RealOutput | P (from Carnot) | Electric power consumed by compressor | |
| Modelica.Blocks.Interfaces.RealOutput | QEva_flow (from Carnot) | Actual cooling heat flow rate removed from fluid 2 |
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 |
| Real | yPL (from Carnot) | if COP_is_for_cooling then QEva_flow/QEva_flow_nominal else QCon_flow/QCon_flow_nominal | Part load ratio |
| Real | etaPL (from Carnot) | if evaluate_etaPL then Buildings.Utilities.Math.Functions.polynomial(a = a, x = yPL) else 1 | Efficiency due to part load (etaPL(yPL=1)=1) |
| Real | COP (from Carnot) | etaCarnot_nominal_internal*COPCar*etaPL | Coefficient of performance |
| Real | COPCar (from Carnot) | TUseAct/Buildings.Utilities.Math.Functions.smoothMax(x1 = 1, x2 = TConAct - TEvaAct, deltaX = 0.25) | Carnot efficiency |
| Modelica.Units.SI.Temperature | TConAct (from Carnot) | Medium1.temperature(staB1) + QCon_flow/QCon_flow_nominal*TAppCon_nominal | Condenser temperature used to compute efficiency, taking into account pinch temperature between fluid and refrigerant |
| Modelica.Units.SI.Temperature | TEvaAct (from Carnot) | Medium2.temperature(staB2) - QEva_flow/QEva_flow_nominal*TAppEva_nominal | Evaporator temperature used to compute efficiency, taking into account pinch temperature between fluid and refrigerant |
Revisions
-
January 26, 2016, by Michael Wetter:
First implementation of this base class.