Description: "Package with base classes for Buildings.Obsolete.Fluid.Movers"

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## Buildings.Obsolete.Fluid.Movers.BaseClasses

Package with base classes for Buildings.Obsolete.Fluid.Movers

### Information

This package contains base classes that are used to construct the models in Buildings.Obsolete.Fluid.Movers.

Extends from Modelica.Icons.BasesPackage (Icon for packages containing base classes).

### Package Content

Name | Description
--- | ---
Characteristics | Functions for fan or pump characteristics
ControlledFlowMachine | Partial model for fan or pump with ideally controlled mass flow rate or head as input signal
FlowMachineInterface | Partial model with performance curves for fans or pumps
IdealSource | Base class for pressure and mass flow source with optional power input
PartialFlowMachine | Partial model to interface fan or pump models with the medium
PowerInterface | Partial model to compute power draw and heat dissipation of fans and pumps
PrescribedFlowMachine | Partial model for fan or pump with speed (y or Nrpm) as input signal

## Buildings.Obsolete.Fluid.Movers.BaseClasses.ControlledFlowMachine

Partial model for fan or pump with ideally controlled mass flow rate or head as input signal

### Information

This model describes a fan or pump that takes as an input the head or the mass flow rate.

Extends from Buildings.Obsolete.Fluid.Movers.BaseClasses.PowerInterface (Partial model to compute power draw and heat dissipation of fans and pumps), Buildings.Obsolete.Fluid.Movers.BaseClasses.PartialFlowMachine (Partial model to interface fan or pump models with the medium).

### Parameters

Type | Name | Default | Description
--- | --- | --- | ---
Density | rho_default | Medium.density(sta_default) | Fluid density at medium default state [kg/m3]
replaceable package Medium | PartialMedium | Medium in the component
Boolean | addPowerToMedium | true | Set to false to avoid any power (=heat and flow work) being added to medium (may give simpler equations)
Boolean | control_m_flow |  | = false to control head instead of m_flow
Characteristics
Boolean | use_powerCharacteristic | false | Use powerCharacteristic (vs. efficiencyCharacteristic)
Boolean | motorCooledByFluid | true | If true, then motor heat is added to fluid stream
efficiencyParameters | motorEfficiency |  | Normalized volume flow rate vs. efficiency
efficiencyParameters | hydraulicEfficiency |  | Normalized volume flow rate vs. efficiency
Nominal condition
MassFlowRate | m_flow_nominal |  | Nominal mass flow rate [kg/s]
Initialization
MassFlowRate | m_flow.start | 0 | Mass flow rate from port_a to port_b (m_flow > 0 is design flow direction) [kg/s]
Pressure | dp.start | 0 | Pressure difference between port_a and port_b [Pa]
Advanced
Boolean | homotopyInitialization | true | = true, use homotopy method
MassFlowRate | m_flow_small | 1E-4*abs(m_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
Dynamics
Equations
Dynamics | energyDynamics | Modelica.Fluid.Types.Dynamic... | Formulation of energy balance
Dynamics | massDynamics | energyDynamics | Formulation of mass balance
Boolean | dynamicBalance | true | Set to true to use a dynamic balance, which often leads to smaller systems of equations
Real | mSenFac | 1 | Factor for scaling the sensible thermal mass of the volume
Nominal condition
Time | tau | 1 | Time constant of fluid volume for nominal flow, used if dynamicBalance=true [s]
Initialization
AbsolutePressure | p_start | Medium.p_default | Start value of pressure [Pa]
Temperature | T_start | Medium.T_default | Start value of temperature [K]
MassFraction | X_start[Medium.nX] | Medium.X_default | Start value of mass fractions m_i/m [kg/kg]
ExtraProperty | C_start[Medium.nC] | fill(0, Medium.nC) | Start value of trace substances
ExtraProperty | C_nominal[Medium.nC] | fill(1E-2, Medium.nC) | Nominal value of trace substances. (Set to typical order of magnitude.)
Assumptions
Boolean | allowFlowReversal | true | = true to allow flow reversal, false restricts to design direction (port_a -> port_b)

### Connectors

Type | Name | Description
--- | --- | ---
output RealOutput | P | Electrical power consumed [W]
FluidPort_a | port_a | Fluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_b | port_b | Fluid connector b (positive design flow direction is from port_a to port_b)
HeatPort_a | heatPort | Heat dissipation to environment

### Modelica definition

model ControlledFlowMachine "Partial model for fan or pump with ideally controlled mass flow rate or head as input signal" extends Buildings.Obsolete.Fluid.Movers.BaseClasses.PowerInterface( final use_powerCharacteristic = false, final rho_default = Medium.density(sta_default)); extends Buildings.Obsolete.Fluid.Movers.BaseClasses.PartialFlowMachine( preSou(final control_m_flow=control_m_flow)); import cha = Buildings.Obsolete.Fluid.Movers.BaseClasses.Characteristics; // parameter Modelica.SIunits.MassFlowRate m_flow_nominal // "Nominal mass flow rate, used as flow rate if control_m_flow"; // parameter Modelica.SIunits.MassFlowRate m_flow_max = m_flow_nominal // "Maximum mass flow rate (at zero head)"; // what to control constant Boolean control_m_flow "= false to control head instead of m_flow"; Real r_V(start=1) "Ratio V_flow/V_flow_max = V_flow/V_flow(dp=0, N=N_nominal)"; protected final parameter Medium.AbsolutePressure p_a_default(displayUnit="Pa") = Medium.p_default "Nominal inlet pressure for predefined fan or pump characteristics"; parameter Medium.ThermodynamicState sta_default = Medium.setState_pTX( T=Medium.T_default, p=Medium.p_default, X=Medium.X_default[1:Medium.nXi]) "Default medium state"; Modelica.Blocks.Sources.RealExpression PToMedium_flow(y=Q_flow + WFlo) if addPowerToMedium "Heat and work input into medium"; initial equation V_flow_max=m_flow_nominal/rho_default; equation r_V = VMachine_flow/V_flow_max; etaHyd = cha.efficiency(data=hydraulicEfficiency, r_V=r_V, d=hydDer); etaMot = cha.efficiency(data=motorEfficiency, r_V=r_V, d=motDer); dpMachine = -dp; VMachine_flow = -port_b.m_flow/rho_in; // To compute the electrical power, we set a lower bound for eta to avoid // a division by zero. P = WFlo / Buildings.Utilities.Math.Functions.smoothMax(x1=eta, x2=1E-5, deltaX=1E-6); connect(PToMedium_flow.y, prePow.Q_flow); end ControlledFlowMachine;

## Buildings.Obsolete.Fluid.Movers.BaseClasses.FlowMachineInterface

Partial model with performance curves for fans or pumps

### Information

This is an interface that implements the functions to compute the head, power draw and efficiency of fans and pumps. It is used by the model PrescribedFlowMachine.

The nominal hydraulic characteristic (volume flow rate versus total pressure) is given by a set of data points. A cubic hermite spline with linear extrapolation is used to compute the performance at other operating points.

The fan or pump energy balance can be specified in two alternative ways:

- If `use_powerCharacteristic = false`, then the data points for normalized volume flow rate versus efficiency is used to determine the efficiency, and then the power consumption. The default is a constant efficiency of 0.8.
- If `use_powerCharacteristic = true`, then the data points for normalized volume flow rate versus power consumption is used to determine the power consumption, and then the efficiency is computed based on the actual power consumption and the flow work.

#### Implementation

For numerical reasons, the user-provided data points for volume flow rate versus pressure rise are modified to add a fan internal flow resistance. Because this flow resistance is subtracted during the simulation when computing the fan pressure rise, the model reproduces the exact points that were provided by the user.

Also for numerical reasons, the pressure rise at zero flow rate and the flow rate at zero pressure rise is added to the user-provided data, unless the user already provides these data points. Since Modelica 3.2 does not allow dynamic memory allocation, this implementation required the use of three different arrays for the situation where no additional point is added, where one additional point is added and where two additional points are added. The parameter `curve` causes the correct data record to be used during the simulation.

Extends from Buildings.Obsolete.Fluid.Movers.BaseClasses.PowerInterface (Partial model to compute power draw and heat dissipation of fans and pumps).

### Parameters

Type | Name | Default | Description
--- | --- | --- | ---
Density | rho_default |  | Fluid density at medium default state [kg/m3]
Characteristics
Boolean | use_powerCharacteristic | false | Use powerCharacteristic (vs. efficiencyCharacteristic)
Boolean | motorCooledByFluid | true | If true, then motor heat is added to fluid stream
efficiencyParameters | motorEfficiency |  | Normalized volume flow rate vs. efficiency
efficiencyParameters | hydraulicEfficiency |  | Normalized volume flow rate vs. efficiency
AngularVelocity_rpm | N_nominal | 1500 | Nominal rotational speed for flow characteristic [1/min]
flowParameters | pressure |  | Volume flow rate vs. total pressure rise
powerParameters | power |  | Volume flow rate vs. electrical power consumption
Advanced
Boolean | homotopyInitialization | true | = true, use homotopy method
Dynamics
Filtered speed
Boolean | filteredSpeed | true | = true, if speed is filtered with a 2nd order CriticalDamping filter
Time | riseTime | 30 | Rise time of the filter (time to reach 99.6 % of the speed) [s]
Init | init | Modelica.Blocks.Types.Init.I... | Type of initialization (no init/steady state/initial state/initial output)
Real | N_start | 0 | Initial value of speed

### Connectors

Type | Name | Description
--- | --- | ---
output RealOutput | P | Electrical power consumed [W]
output RealOutput | N_actual | [1/min]

### Modelica definition

partial model FlowMachineInterface "Partial model with performance curves for fans or pumps" extends Buildings.Obsolete.Fluid.Movers.BaseClasses.PowerInterface( VMachine_flow(nominal=V_flow_nominal, start=V_flow_nominal), V_flow_max(nominal=V_flow_nominal, start=V_flow_nominal)); import Modelica.Constants; import cha = Buildings.Obsolete.Fluid.Movers.BaseClasses.Characteristics; parameter Modelica.SIunits.Conversions.NonSIunits.AngularVelocity_rpm N_nominal = 1500 "Nominal rotational speed for flow characteristic"; final parameter Modelica.SIunits.VolumeFlowRate V_flow_nominal= pressure.V_flow[size(pressure.V_flow,1)] "Nominal volume flow rate, used for homotopy"; parameter Buildings.Obsolete.Fluid.Movers.BaseClasses.Characteristics.flowParameters pressure "Volume flow rate vs. total pressure rise"; parameter Buildings.Obsolete.Fluid.Movers.BaseClasses.Characteristics.powerParameters power "Volume flow rate vs. electrical power consumption"; parameter Boolean homotopyInitialization = true "= true, use homotopy method"; // Classes used to implement the filtered speed parameter Boolean filteredSpeed=true "= true, if speed is filtered with a 2nd order CriticalDamping filter"; parameter Modelica.SIunits.Time riseTime=30 "Rise time of the filter (time to reach 99.6 % of the speed)"; parameter Modelica.Blocks.Types.Init init=Modelica.Blocks.Types.Init.InitialOutput "Type of initialization (no init/steady state/initial state/initial output)"; parameter Real N_start=0 "Initial value of speed"; // Speed Modelica.Blocks.Interfaces.RealOutput N_actual(min=0, max=N_nominal, final quantity="AngularVelocity", final unit="1/min", nominal=N_nominal); // "Shaft rotational speed in rpm"; Real r_N(min=0, start=N_start/N_nominal, unit="1") "Ratio N_actual/N_nominal"; Real r_V(start=1, unit="1") "Ratio V_flow/V_flow_max"; protected Modelica.Blocks.Interfaces.RealOutput N_filtered(min=0, start=N_start, max=N_nominal) if filteredSpeed "Filtered speed in the range 0..N_nominal"; Modelica.Blocks.Continuous.Filter filter( order=2, f_cut=5/(2*Modelica.Constants.pi*riseTime), final init=init, final y_start=N_start, x(each stateSelect=StateSelect.always), u_nominal=N_nominal, u(final quantity="AngularVelocity", final unit="1/min", nominal=N_nominal), y(final quantity="AngularVelocity", final unit="1/min", nominal=N_nominal), final analogFilter=Modelica.Blocks.Types.AnalogFilter.CriticalDamping, final filterType=Modelica.Blocks.Types.FilterType.LowPass) if filteredSpeed "Second order filter to approximate valve opening time, and to improve numerics"; parameter Modelica.SIunits.VolumeFlowRate VDelta_flow(fixed=false, start=delta*V_flow_nominal) "Small volume flow rate"; parameter Modelica.SIunits.Pressure dpDelta(fixed=false, start=100) "Small pressure"; parameter Real delta = 0.05 "Small value used to transition to other fan curve"; parameter Real cBar[2](each fixed=false) "Coefficients for linear approximation of pressure vs. flow rate"; parameter Modelica.SIunits.Pressure dpMax(min=0, fixed=false); parameter Real kRes(min=0, unit="kg/(s.m4)", fixed=false) "Coefficient for internal pressure drop of fan or pump"; parameter Integer curve(min=1, max=3, fixed=false) "Flag, used to pick the right representatio of the fan or pump pressure curve"; parameter Integer nOri = size(pressure.V_flow,1) "Number of data points for pressure curve"; parameter Buildings.Obsolete.Fluid.Movers.BaseClasses.Characteristics.flowParametersInternal pCur1( final n = nOri, V_flow(each fixed=false), dp(each fixed=false)) "Volume flow rate vs. total pressure rise with correction for pump resistance added"; parameter Buildings.Obsolete.Fluid.Movers.BaseClasses.Characteristics.flowParametersInternal pCur2( final n = nOri + 1, V_flow(each fixed=false), dp(each fixed=false)) "Volume flow rate vs. total pressure rise with correction for pump resistance added"; parameter Buildings.Obsolete.Fluid.Movers.BaseClasses.Characteristics.flowParametersInternal pCur3( final n = nOri + 2, V_flow(each fixed=false), dp(each fixed=false)) "Volume flow rate vs. total pressure rise with correction for pump resistance added"; parameter Real preDer1[nOri](each fixed=false) "Derivatives of flow rate vs. pressure at the support points"; parameter Real preDer2[nOri+1](each fixed=false) "Derivatives of flow rate vs. pressure at the support points"; parameter Real preDer3[nOri+2](each fixed=false) "Derivatives of flow rate vs. pressure at the support points"; parameter Real powDer[size(power.V_flow,1)]= if use_powerCharacteristic then Buildings.Utilities.Math.Functions.splineDerivatives( x=power.V_flow, y=power.P, ensureMonotonicity=Buildings.Utilities.Math.Functions.isMonotonic(x=power.P, strict=false)) else zeros(size(power.V_flow,1)) "Coefficients for polynomial of pressure vs. flow rate"; parameter Boolean haveMinimumDecrease(fixed=false) "Flag used for reporting"; parameter Boolean haveDPMax(fixed=false) "Flag, true if user specified data that contain dpMax"; parameter Boolean haveVMax(fixed=false) "Flag, true if user specified data that contain V_flow_max"; // Variables Modelica.SIunits.Density rho "Medium density"; function getPerformanceDataAsString input Buildings.Obsolete.Fluid.Movers.BaseClasses.Characteristics.flowParameters pressure "Performance data"; input Real derivative[:](unit="kg/(s.m4)") "Derivative"; input Integer minimumLength = 6 "Minimum width of result"; input Integer significantDigits = 6 "Number of significant digits"; output String str "String representation"; algorithm str :=""; for i in 1:size(derivative, 1) loop str :=str + " V_flow[" + String(i) + "]=" + String( pressure.V_flow[i], minimumLength=minimumLength, significantDigits=significantDigits) + "\t" + "dp[" + String(i) + "]=" + String( pressure.dp[i], minimumLength=minimumLength, significantDigits=significantDigits) + "\tResulting derivative dp/dV_flow = " + String( derivative[i], minimumLength=minimumLength, significantDigits=significantDigits) + "\n"; end for; end getPerformanceDataAsString; function getArrayAsString input Real array[:] "Array to be printed"; input String varName "Variable name"; input Integer minimumLength = 6 "Minimum width of result"; input Integer significantDigits = 6 "Number of significant digits"; output String str "String representation"; algorithm str :=""; for i in 1:size(array, 1) loop str :=str + " " + varName + "[" + String(i) + "]=" + String( array[i], minimumLength=minimumLength, significantDigits=significantDigits) + "\n"; end for; end getArrayAsString; initial algorithm // Check validity of data assert(size(pressure.V_flow, 1) > 1, "Must have at least two data points for pressure.V_flow."); assert(Buildings.Utilities.Math.Functions.isMonotonic(x=pressure.V_flow, strict=true) and pressure.V_flow[1] > -Modelica.Constants.eps, "The volume flow rate for the fan pressure rise must be a strictly decreasing sequence with the first element being non-zero. The following performance data have been entered: " + getArrayAsString(pressure.V_flow, "pressure.V_flow")); // Check if V_flow_max or dpMax are provided by user haveVMax :=(abs(pressure.dp[nOri]) < Modelica.Constants.eps); haveDPMax :=(abs(pressure.V_flow[1]) < Modelica.Constants.eps); // Assign V_flow_max and dpMax if haveVMax then V_flow_max :=pressure.V_flow[nOri]; else assert((pressure.V_flow[nOri]-pressure.V_flow[nOri-1])/((pressure.dp[nOri]-pressure.dp[nOri-1]))<0, "The last two pressure points for the fan or pump performance curve must be decreasing. You need to set more reasonable parameters. Received " + getArrayAsString(pressure.dp, "dp")); V_flow_max :=pressure.V_flow[nOri] - (pressure.V_flow[nOri] - pressure.V_flow[ nOri - 1])/((pressure.dp[nOri] - pressure.dp[nOri - 1]))*pressure.dp[nOri]; end if; if haveDPMax then dpMax :=pressure.dp[1]; else dpMax :=pressure.dp[1] - ((pressure.dp[2] - pressure.dp[1])/(pressure.V_flow[ 2] - pressure.V_flow[1]))*pressure.V_flow[1]; end if; // Check if minimum decrease condition is satisfied haveMinimumDecrease :=true; kRes :=dpMax/V_flow_max*delta^2/10; for i in 1:nOri-1 loop if ((pressure.dp[i+1]-pressure.dp[i])/(pressure.V_flow[i+1]-pressure.V_flow[i]) >= -kRes) then haveMinimumDecrease :=false; end if; end for; // Write warning if the volumetric flow rate versus pressure curve does not satisfy // the minimum decrease condition if (not haveMinimumDecrease) then Modelica.Utilities.Streams.print(" Warning: ======== It is recommended that the volume flow rate versus pressure relation of the fan or pump satisfies the minimum decrease condition (pressure.dp[i+1]-pressure.dp[i]) d[i] = ----------------------------------------- < " + String(-kRes) + " (pressure.V_flow[i+1]-pressure.V_flow[i]) is " + getArrayAsString({(pressure.dp[i+1]-pressure.dp[i])/(pressure.V_flow[i+1]-pressure.V_flow[i]) for i in 1:nOri-1}, "d") + " Otherwise, a solution to the equations may not exist if the fan or pump speed is reduced. In this situation, the solver will fail due to non-convergence and the simulation stops."); end if; // Correction for flow resistance of pump or fan // Case 1: if (haveVMax and haveDPMax) or (nOri == 2) then // ----- Curve 1 curve :=1; // V_flow_max and dpMax are provided by the user, or we only have two data points for i in 1:nOri loop pCur1.dp[i] :=pressure.dp[i] + pressure.V_flow[i] * kRes; pCur1.V_flow[i] := pressure.V_flow[i]; end for; pCur2.V_flow := zeros(nOri + 1); pCur2.dp := zeros(nOri + 1); pCur3.V_flow := zeros(nOri + 2); pCur3.dp := zeros(nOri + 2); preDer1:=Buildings.Utilities.Math.Functions.splineDerivatives(x=pCur1.V_flow, y=pCur1.dp); preDer2:=zeros(nOri+1); preDer3:=zeros(nOri+2); // Equation to compute dpDelta dpDelta :=cha.pressure( data=pCur1, V_flow=0, r_N=delta, VDelta_flow=0, dpDelta=0, V_flow_max=Modelica.Constants.eps, dpMax=0, delta=0, d=preDer1, cBar=zeros(2), kRes= kRes); // Equation to compute VDelta_flow. By the affinity laws, the volume flow rate is proportional to the speed. VDelta_flow :=V_flow_max*delta; // Linear equations to determine cBar // Conditions for r_N=delta, V_flow = VDelta_flow // Conditions for r_N=delta, V_flow = 0 cBar[1] :=cha.pressure( data=pCur1, V_flow=0, r_N=delta, VDelta_flow=0, dpDelta=0, V_flow_max=Modelica.Constants.eps, dpMax=0, delta=0, d=preDer1, cBar=zeros(2), kRes= kRes) * (1-delta)/delta^2; cBar[2] :=((cha.pressure( data=pCur1, V_flow=VDelta_flow, r_N=delta, VDelta_flow=0, dpDelta=0, V_flow_max=Modelica.Constants.eps, dpMax=0, delta=0, d=preDer1, cBar=zeros(2), kRes= kRes) - delta*dpDelta)/delta^2 - cBar[1])/VDelta_flow; elseif haveVMax or haveDPMax then // ----- Curve 2 curve :=2; // V_flow_max or dpMax is provided by the user, but not both if haveVMax then pCur2.V_flow[1] := 0; pCur2.dp[1] := dpMax; for i in 1:nOri loop pCur2.dp[i+1] :=pressure.dp[i] + pressure.V_flow[i] * kRes; pCur2.V_flow[i+1] := pressure.dp[i]; end for; else for i in 1:nOri loop pCur2.dp[i] :=pressure.dp[i] + pressure.V_flow[i] * kRes; pCur2.V_flow[i] := pressure.V_flow[i]; end for; pCur2.V_flow[nOri+1] := V_flow_max; pCur2.dp[nOri+1] := 0; end if; pCur1.V_flow := zeros(nOri); pCur1.dp := zeros(nOri); pCur3.V_flow := zeros(nOri + 2); pCur3.dp := zeros(nOri + 2); preDer1:=zeros(nOri); preDer2:=Buildings.Utilities.Math.Functions.splineDerivatives(x=pCur2.V_flow, y=pCur2.dp); preDer3:=zeros(nOri+2); // Equation to compute dpDelta dpDelta :=cha.pressure( data=pCur2, V_flow=0, r_N=delta, VDelta_flow=0, dpDelta=0, V_flow_max=Modelica.Constants.eps, dpMax=0, delta=0, d=preDer2, cBar=zeros(2), kRes= kRes); // Equation to compute VDelta_flow. By the affinity laws, the volume flow rate is proportional to the speed. VDelta_flow :=V_flow_max*delta; // Linear equations to determine cBar // Conditions for r_N=delta, V_flow = VDelta_flow // Conditions for r_N=delta, V_flow = 0 cBar[1] :=cha.pressure( data=pCur2, V_flow=0, r_N=delta, VDelta_flow=0, dpDelta=0, V_flow_max=Modelica.Constants.eps, dpMax=0, delta=0, d=preDer2, cBar=zeros(2), kRes= kRes) * (1-delta)/delta^2; cBar[2] :=((cha.pressure( data=pCur2, V_flow=VDelta_flow, r_N=delta, VDelta_flow=0, dpDelta=0, V_flow_max=Modelica.Constants.eps, dpMax=0, delta=0, d=preDer2, cBar=zeros(2), kRes= kRes) - delta*dpDelta)/delta^2 - cBar[1])/VDelta_flow; else // ----- Curve 3 curve :=3; // Neither V_flow_max nor dpMax are provided by the user pCur3.V_flow[1] := 0; pCur3.dp[1] := dpMax; for i in 1:nOri loop pCur3.dp[i+1] :=pressure.dp[i] + pressure.V_flow[i] * kRes; pCur3.V_flow[i+1] := pressure.V_flow[i]; end for; pCur3.V_flow[nOri+2] := V_flow_max; pCur3.dp[nOri+2] := 0; pCur1.V_flow := zeros(nOri); pCur1.dp := zeros(nOri); pCur2.V_flow := zeros(nOri + 1); pCur2.dp := zeros(nOri + 1); preDer1:=zeros(nOri); preDer2:=zeros(nOri+1); preDer3:=Buildings.Utilities.Math.Functions.splineDerivatives(x=pCur3.V_flow, y=pCur3.dp); // Equation to compute dpDelta dpDelta :=cha.pressure( data=pCur3, V_flow=0, r_N=delta, VDelta_flow=0, dpDelta=0, V_flow_max=Modelica.Constants.eps, dpMax=0, delta=0, d=preDer3, cBar=zeros(2), kRes= kRes); // Equation to compute VDelta_flow. By the affinity laws, the volume flow rate is proportional to the speed. VDelta_flow :=V_flow_max*delta; // Linear equations to determine cBar // Conditions for r_N=delta, V_flow = VDelta_flow // Conditions for r_N=delta, V_flow = 0 cBar[1] :=cha.pressure( data=pCur3, V_flow=0, r_N=delta, VDelta_flow=0, dpDelta=0, V_flow_max=Modelica.Constants.eps, dpMax=0, delta=0, d=preDer3, cBar=zeros(2), kRes= kRes) * (1-delta)/delta^2; cBar[2] :=((cha.pressure( data=pCur3, V_flow=VDelta_flow, r_N=delta, VDelta_flow=0, dpDelta=0, V_flow_max=Modelica.Constants.eps, dpMax=0, delta=0, d=preDer3, cBar=zeros(2), kRes= kRes) - delta*dpDelta)/delta^2 - cBar[1])/VDelta_flow; end if; equation // Hydraulic equations r_N = N_actual/N_nominal; r_V = VMachine_flow/V_flow_max; // For the homotopy method, we approximate dpMachine by an equation // that is linear in VMachine_flow, and that goes linearly to 0 as r_N goes to 0. // The three branches below are identical, except that we pass either // pCur1, pCur2 or pCur3, and preDer1, preDer2 or preDer3 if (curve == 1) then if homotopyInitialization then dpMachine = homotopy(actual=cha.pressure(data=pCur1, V_flow=VMachine_flow, r_N=r_N, VDelta_flow=VDelta_flow, dpDelta=dpDelta, V_flow_max=V_flow_max, dpMax=dpMax, delta=delta, d=preDer1, cBar=cBar, kRes=kRes), simplified=r_N* (cha.pressure(data=pCur1, V_flow=V_flow_nominal, r_N=1, VDelta_flow=VDelta_flow, dpDelta=dpDelta, V_flow_max=V_flow_max, dpMax=dpMax, delta=delta, d=preDer1, cBar=cBar, kRes=kRes) +(VMachine_flow-V_flow_nominal)* (cha.pressure(data=pCur1, V_flow=(1+delta)*V_flow_nominal, r_N=1, VDelta_flow=VDelta_flow, dpDelta=dpDelta, V_flow_max=V_flow_max, dpMax=dpMax, delta=delta, d=preDer1, cBar=cBar, kRes=kRes) -cha.pressure(data=pCur1, V_flow=(1-delta)*V_flow_nominal, r_N=1, VDelta_flow=VDelta_flow, dpDelta=dpDelta, V_flow_max=V_flow_max, dpMax=dpMax, delta=delta, d=preDer1, cBar=cBar, kRes=kRes)) /(2*delta*V_flow_nominal))); else dpMachine = cha.pressure(data=pCur1, V_flow=VMachine_flow, r_N=r_N, VDelta_flow=VDelta_flow, dpDelta=dpDelta, V_flow_max=V_flow_max, dpMax=dpMax, delta=delta, d=preDer1, cBar=cBar, kRes=kRes); end if; // end of computation for this branch elseif (curve == 2) then if homotopyInitialization then dpMachine = homotopy(actual=cha.pressure(data=pCur2, V_flow=VMachine_flow, r_N=r_N, VDelta_flow=VDelta_flow, dpDelta=dpDelta, V_flow_max=V_flow_max, dpMax=dpMax, delta=delta, d=preDer2, cBar=cBar, kRes=kRes), simplified=r_N* (cha.pressure(data=pCur2, V_flow=V_flow_nominal, r_N=1, VDelta_flow=VDelta_flow, dpDelta=dpDelta, V_flow_max=V_flow_max, dpMax=dpMax, delta=delta, d=preDer2, cBar=cBar, kRes=kRes) +(VMachine_flow-V_flow_nominal)* (cha.pressure(data=pCur2, V_flow=(1+delta)*V_flow_nominal, r_N=1, VDelta_flow=VDelta_flow, dpDelta=dpDelta, V_flow_max=V_flow_max, dpMax=dpMax, delta=delta, d=preDer2, cBar=cBar, kRes=kRes) -cha.pressure(data=pCur2, V_flow=(1-delta)*V_flow_nominal, r_N=1, VDelta_flow=VDelta_flow, dpDelta=dpDelta, V_flow_max=V_flow_max, dpMax=dpMax, delta=delta, d=preDer2, cBar=cBar, kRes=kRes)) /(2*delta*V_flow_nominal))); else dpMachine = cha.pressure(data=pCur2, V_flow=VMachine_flow, r_N=r_N, VDelta_flow=VDelta_flow, dpDelta=dpDelta, V_flow_max=V_flow_max, dpMax=dpMax, delta=delta, d=preDer2, cBar=cBar, kRes=kRes); end if; // end of computation for this branch else if homotopyInitialization then dpMachine = homotopy(actual=cha.pressure(data=pCur3, V_flow=VMachine_flow, r_N=r_N, VDelta_flow=VDelta_flow, dpDelta=dpDelta, V_flow_max=V_flow_max, dpMax=dpMax, delta=delta, d=preDer3, cBar=cBar, kRes=kRes), simplified=r_N* (cha.pressure(data=pCur3, V_flow=V_flow_nominal, r_N=1, VDelta_flow=VDelta_flow, dpDelta=dpDelta, V_flow_max=V_flow_max, dpMax=dpMax, delta=delta, d=preDer3, cBar=cBar, kRes=kRes) +(VMachine_flow-V_flow_nominal)* (cha.pressure(data=pCur3, V_flow=(1+delta)*V_flow_nominal, r_N=1, VDelta_flow=VDelta_flow, dpDelta=dpDelta, V_flow_max=V_flow_max, dpMax=dpMax, delta=delta, d=preDer3, cBar=cBar, kRes=kRes) -cha.pressure(data=pCur3, V_flow=(1-delta)*V_flow_nominal, r_N=1, VDelta_flow=VDelta_flow, dpDelta=dpDelta, V_flow_max=V_flow_max, dpMax=dpMax, delta=delta, d=preDer3, cBar=cBar, kRes=kRes)) /(2*delta*V_flow_nominal))); else dpMachine = cha.pressure(data=pCur3, V_flow=VMachine_flow, r_N=r_N, VDelta_flow=VDelta_flow, dpDelta=dpDelta, V_flow_max=V_flow_max, dpMax=dpMax, delta=delta, d=preDer3, cBar=cBar, kRes=kRes); end if; // end of computation for this branch end if; // Power consumption if use_powerCharacteristic then // For the homotopy, we want P/V_flow to be bounded as V_flow -> 0 to avoid a very high medium // temperature near zero flow. if homotopyInitialization then P = homotopy(actual=cha.power(data=power, V_flow=VMachine_flow, r_N=r_N, d=powDer), simplified=VMachine_flow/V_flow_nominal* cha.power(data=power, V_flow=V_flow_nominal, r_N=1, d=powDer)); else P = (rho/rho_default)*cha.power(data=power, V_flow=VMachine_flow, r_N=r_N, d=powDer); end if; // To compute the efficiency, we set a lower bound on the electricity consumption. // This is needed because WFlo can be close to zero when P is zero, thereby // causing a division by zero. // Earlier versions of the model computed WFlo = eta * P, but this caused // a division by zero. eta = WFlo / Buildings.Utilities.Math.Functions.smoothMax(x1=P, x2=1E-5, deltaX=1E-6); // In this configuration, we only now the total power consumption. // Because nothing is known about etaMot versus etaHyd, we set etaHyd=1. This will // cause etaMot=eta, because eta=etaHyd*etaMot. // Earlier versions used etaMot=sqrt(eta), but as eta->0, this function has // and infinite derivative. etaHyd = 1; else if homotopyInitialization then etaHyd = homotopy(actual=cha.efficiency(data=hydraulicEfficiency, r_V=r_V, d=hydDer), simplified=cha.efficiency(data=hydraulicEfficiency, r_V=1, d=hydDer)); etaMot = homotopy(actual=cha.efficiency(data=motorEfficiency, r_V=r_V, d=motDer), simplified=cha.efficiency(data=motorEfficiency, r_V=1, d=motDer)); else etaHyd = cha.efficiency(data=hydraulicEfficiency, r_V=r_V, d=hydDer); etaMot = cha.efficiency(data=motorEfficiency, r_V=r_V, d=motDer); end if; // To compute the electrical power, we set a lower bound for eta to avoid // a division by zero. P = WFlo / Buildings.Utilities.Math.Functions.smoothMax(x1=eta, x2=1E-5, deltaX=1E-6); end if; end FlowMachineInterface;

## Buildings.Obsolete.Fluid.Movers.BaseClasses.IdealSource

Base class for pressure and mass flow source with optional power input

### Information

Model of a fictious pipe that is used as a base class for a pressure source or to prescribe a mass flow rate.

Note that for fans and pumps with dynamic balance, both the heat and the flow work are added to the volume of air or water. This simplifies the equations compared to adding heat to the volume, and flow work to this model.

Extends from Buildings.Fluid.Interfaces.PartialTwoPortTransport (Partial element transporting fluid between two ports without storage of mass or energy).

### Parameters

Type | Name | Default | Description
--- | --- | --- | ---
replaceable package Medium | PartialMedium | Medium in the component
Boolean | control_m_flow |  | = false to control dp instead of m_flow
Assumptions
Boolean | allowFlowReversal | true | = true to allow flow reversal, false restricts to design direction (port_a -> port_b)
Advanced
AbsolutePressure | dp_start | 0 | Guess value of dp = port_a.p - port_b.p [Pa]
MassFlowRate | m_flow_start | 0 | Guess value of m_flow = port_a.m_flow [kg/s]
MassFlowRate | m_flow_small |  | Small mass flow rate for regularization of zero flow [kg/s]
Diagnostics
Boolean | show_T | false | = true, if temperatures at port_a and port_b are computed
Boolean | show_V_flow | true | = true, if volume flow rate at inflowing port is computed

### Connectors

Type | Name | Description
--- | --- | ---
FluidPort_a | port_a | Fluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_b | port_b | Fluid connector b (positive design flow direction is from port_a to port_b)
input RealInput | m_flow_in | Prescribed mass flow rate
input RealInput | dp_in | Prescribed outlet pressure

### Modelica definition

model IdealSource "Base class for pressure and mass flow source with optional power input" extends Buildings.Fluid.Interfaces.PartialTwoPortTransport(show_T=false); // what to control parameter Boolean control_m_flow "= false to control dp instead of m_flow"; Modelica.Blocks.Interfaces.RealInput m_flow_in if control_m_flow "Prescribed mass flow rate"; Modelica.Blocks.Interfaces.RealInput dp_in if not control_m_flow "Prescribed outlet pressure"; protected Modelica.Blocks.Interfaces.RealInput m_flow_internal "Needed to connect to conditional connector"; Modelica.Blocks.Interfaces.RealInput dp_internal "Needed to connect to conditional connector"; equation // Ideal control if control_m_flow then m_flow = m_flow_internal; dp_internal = 0; else dp = dp_internal; m_flow_internal = 0; end if; connect(dp_internal, dp_in); connect(m_flow_internal, m_flow_in); // Energy balance (no storage) port_a.h_outflow = inStream(port_b.h_outflow); port_b.h_outflow = inStream(port_a.h_outflow); end IdealSource;

## Buildings.Obsolete.Fluid.Movers.BaseClasses.PartialFlowMachine

Partial model to interface fan or pump models with the medium

### Information

This is the base model for fans and pumps. It provides an interface between the equations that compute head and power consumption, and the implementation of the energy and pressure balance of the fluid.

Depending on the value of the parameter `dynamicBalance`, the fluid volume is computed using a dynamic balance or a steady-state balance.

The parameter `addPowerToMedium` determines whether any power is added to the fluid. The default is `addPowerToMedium=true`, and hence the outlet enthalpy is higher than the inlet enthalpy if the flow device is operating. The setting `addPowerToMedium=false` is physically incorrect (since the flow work, the flow friction and the fan heat do not increase the enthalpy of the medium), but this setting does in some cases lead to simpler equations and more robust simulation, in particular if the mass flow is equal to zero.

Extends from Buildings.Fluid.Interfaces.LumpedVolumeDeclarations (Declarations for lumped volumes), Buildings.Fluid.Interfaces.PartialTwoPortInterface (Partial model transporting fluid between two ports without storing mass or energy).

### Parameters

Type | Name | Default | Description
--- | --- | --- | ---
replaceable package Medium | PartialMedium | Medium in the component
Boolean | addPowerToMedium | true | Set to false to avoid any power (=heat and flow work) being added to medium (may give simpler equations)
Nominal condition
MassFlowRate | m_flow_nominal |  | Nominal mass flow rate [kg/s]
Initialization
MassFlowRate | m_flow.start | 0 | Mass flow rate from port_a to port_b (m_flow > 0 is design flow direction) [kg/s]
Pressure | dp.start | 0 | Pressure difference between port_a and port_b [Pa]
Dynamics
Equations
Dynamics | energyDynamics | Modelica.Fluid.Types.Dynamic... | Formulation of energy balance
Dynamics | massDynamics | energyDynamics | Formulation of mass balance
Boolean | dynamicBalance | true | Set to true to use a dynamic balance, which often leads to smaller systems of equations
Real | mSenFac | 1 | Factor for scaling the sensible thermal mass of the volume
Nominal condition
Time | tau | 1 | Time constant of fluid volume for nominal flow, used if dynamicBalance=true [s]
Initialization
AbsolutePressure | p_start | Medium.p_default | Start value of pressure [Pa]
Temperature | T_start | Medium.T_default | Start value of temperature [K]
MassFraction | X_start[Medium.nX] | Medium.X_default | Start value of mass fractions m_i/m [kg/kg]
ExtraProperty | C_start[Medium.nC] | fill(0, Medium.nC) | Start value of trace substances
ExtraProperty | C_nominal[Medium.nC] | fill(1E-2, Medium.nC) | Nominal value of trace substances. (Set to typical order of magnitude.)
Assumptions
Boolean | allowFlowReversal | true | = true to allow flow reversal, false restricts to design direction (port_a -> port_b)
Advanced
MassFlowRate | m_flow_small | 1E-4*abs(m_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

### Connectors

Type | Name | Description
--- | --- | ---
HeatPort_a | heatPort | Heat dissipation to environment

### Modelica definition

partial model PartialFlowMachine "Partial model to interface fan or pump models with the medium" extends Buildings.Fluid.Interfaces.LumpedVolumeDeclarations; import Modelica.Constants; extends Buildings.Fluid.Interfaces.PartialTwoPortInterface(show_T=false, port_a( h_outflow(start=h_outflow_start), final m_flow(min = if allowFlowReversal then -Constants.inf else 0)), port_b( h_outflow(start=h_outflow_start), p(start=p_start), final m_flow(max = if allowFlowReversal then +Constants.inf else 0)), final showDesignFlowDirection=false); Buildings.Fluid.Delays.DelayFirstOrder vol( redeclare package Medium = Medium, tau=tau, energyDynamics=if dynamicBalance then energyDynamics else Modelica.Fluid.Types.Dynamics.SteadyState, massDynamics=if dynamicBalance then massDynamics else Modelica.Fluid.Types.Dynamics.SteadyState, T_start=T_start, X_start=X_start, C_start=C_start, m_flow_nominal=m_flow_nominal, p_start=p_start, prescribedHeatFlowRate=true, allowFlowReversal=allowFlowReversal, nPorts=2) "Fluid volume for dynamic model"; parameter Boolean dynamicBalance = true "Set to true to use a dynamic balance, which often leads to smaller systems of equations"; parameter Boolean addPowerToMedium=true "Set to false to avoid any power (=heat and flow work) being added to medium (may give simpler equations)"; parameter Modelica.SIunits.Time tau=1 "Time constant of fluid volume for nominal flow, used if dynamicBalance=true"; // Models Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a heatPort "Heat dissipation to environment"; protected Modelica.SIunits.Density rho_in "Density of inflowing fluid"; Buildings.Obsolete.Fluid.Movers.BaseClasses.IdealSource preSou( redeclare final package Medium = Medium, final m_flow_small=m_flow_small, final allowFlowReversal=allowFlowReversal) "Pressure source"; Buildings.HeatTransfer.Sources.PrescribedHeatFlow prePow if addPowerToMedium "Prescribed power (=heat and flow work) flow for dynamic model"; parameter Medium.ThermodynamicState sta_start=Medium.setState_pTX( T=T_start, p=p_start, X=X_start) "Medium state at start values"; parameter Modelica.SIunits.SpecificEnthalpy h_outflow_start = Medium.specificEnthalpy(sta_start) "Start value for outflowing enthalpy"; equation // For computing the density, we assume that the fan operates in the design flow direction. rho_in = Medium.density( Medium.setState_phX(port_a.p, inStream(port_a.h_outflow), inStream(port_a.Xi_outflow))); connect(prePow.port, vol.heatPort); connect(vol.heatPort, heatPort); connect(port_a, vol.ports[1]); connect(vol.ports[2], preSou.port_a); connect(preSou.port_b, port_b); end PartialFlowMachine;

## Buildings.Obsolete.Fluid.Movers.BaseClasses.PowerInterface

Partial model to compute power draw and heat dissipation of fans and pumps

### Information

This is an interface that implements the functions to compute the power draw and the heat dissipation of fans and pumps. It is used by the model Buildings.Obsolete.Fluid.Movers.BaseClasses.FlowMachineInterface.

#### Implementation

Models that extend this model need to provide an implementation of `WFlo = eta * P`. This equation is not implemented in this model to allow other models to properly guard against division by zero.

### Parameters

Type | Name | Default | Description
--- | --- | --- | ---
Density | rho_default |  | Fluid density at medium default state [kg/m3]
Characteristics
Boolean | use_powerCharacteristic | false | Use powerCharacteristic (vs. efficiencyCharacteristic)
Boolean | motorCooledByFluid | true | If true, then motor heat is added to fluid stream
efficiencyParameters | motorEfficiency |  | Normalized volume flow rate vs. efficiency
efficiencyParameters | hydraulicEfficiency |  | Normalized volume flow rate vs. efficiency
Advanced
Boolean | homotopyInitialization | true | = true, use homotopy method

### Connectors

Type | Name | Description
--- | --- | ---
output RealOutput | P | Electrical power consumed [W]

### Modelica definition

partial model PowerInterface "Partial model to compute power draw and heat dissipation of fans and pumps" import Modelica.Constants; parameter Boolean use_powerCharacteristic = false "Use powerCharacteristic (vs. efficiencyCharacteristic)"; parameter Boolean motorCooledByFluid = true "If true, then motor heat is added to fluid stream"; parameter Boolean homotopyInitialization = true "= true, use homotopy method"; parameter Buildings.Obsolete.Fluid.Movers.BaseClasses.Characteristics.efficiencyParameters motorEfficiency(r_V={1}, eta={0.7}) "Normalized volume flow rate vs. efficiency"; parameter Buildings.Obsolete.Fluid.Movers.BaseClasses.Characteristics.efficiencyParameters hydraulicEfficiency(r_V={1}, eta={0.7}) "Normalized volume flow rate vs. efficiency"; parameter Modelica.SIunits.Density rho_default "Fluid density at medium default state"; Modelica.Blocks.Interfaces.RealOutput P(quantity="Modelica.SIunits.Power", unit="W") "Electrical power consumed"; Modelica.SIunits.Power WHyd "Hydraulic power input (converted to flow work and heat)"; Modelica.SIunits.Power WFlo "Flow work"; Modelica.SIunits.HeatFlowRate Q_flow "Heat input from fan or pump to medium"; Real eta(min=0, max=1) "Global efficiency"; Real etaHyd(min=0, max=1) "Hydraulic efficiency"; Real etaMot(min=0, max=1) "Motor efficiency"; Modelica.SIunits.Pressure dpMachine(displayUnit="Pa") "Pressure increase"; Modelica.SIunits.VolumeFlowRate VMachine_flow "Volume flow rate"; protected parameter Modelica.SIunits.VolumeFlowRate V_flow_max(fixed=false) "Maximum volume flow rate, used for smoothing"; //Modelica.SIunits.HeatFlowRate QThe_flow "Heat input into the medium"; parameter Modelica.SIunits.VolumeFlowRate delta_V_flow = 1E-3*V_flow_max "Factor used for setting heat input into medium to zero at very small flows"; final parameter Real motDer[size(motorEfficiency.r_V, 1)](each fixed=false) "Coefficients for polynomial of pressure vs. flow rate"; final parameter Real hydDer[size(hydraulicEfficiency.r_V,1)](each fixed=false) "Coefficients for polynomial of pressure vs. flow rate"; Modelica.SIunits.HeatFlowRate QThe_flow "Heat input from fan or pump to medium"; initial algorithm // Compute derivatives for cubic spline motDer := if use_powerCharacteristic then zeros(size(motorEfficiency.r_V, 1)) elseif ( size(motorEfficiency.r_V, 1) == 1) then {0} else Buildings.Utilities.Math.Functions.splineDerivatives( x=motorEfficiency.r_V, y=motorEfficiency.eta, ensureMonotonicity=Buildings.Utilities.Math.Functions.isMonotonic(x=motorEfficiency.eta, strict=false)); hydDer := if use_powerCharacteristic then zeros(size(hydraulicEfficiency.r_V, 1)) elseif ( size(hydraulicEfficiency.r_V, 1) == 1) then {0} else Buildings.Utilities.Math.Functions.splineDerivatives( x=hydraulicEfficiency.r_V, y=hydraulicEfficiency.eta); equation eta = etaHyd * etaMot; // WFlo = eta * P; // Flow work WFlo = dpMachine*VMachine_flow; // Hydraulic power (transmitted by shaft), etaHyd = WFlo/WHyd etaHyd * WHyd = WFlo; // Heat input into medium QThe_flow + WFlo = if motorCooledByFluid then P else WHyd; // At m_flow = 0, the solver may still obtain positive values for QThe_flow. // The next statement sets the heat input into the medium to zero for very small flow rates. if homotopyInitialization then Q_flow = homotopy(actual=Buildings.Utilities.Math.Functions.spliceFunction(pos=QThe_flow, neg=0, x=noEvent(abs(VMachine_flow))-2*delta_V_flow, deltax=delta_V_flow), simplified=0); else Q_flow = Buildings.Utilities.Math.Functions.spliceFunction(pos=QThe_flow, neg=0, x=noEvent(abs(VMachine_flow))-2*delta_V_flow, deltax=delta_V_flow); end if; end PowerInterface;

## Buildings.Obsolete.Fluid.Movers.BaseClasses.PrescribedFlowMachine

Partial model for fan or pump with speed (y or Nrpm) as input signal

### Information

This is the base model for fans and pumps that take as input a control signal in the form of the pump speed `Nrpm` or the normalized pump speed `y=Nrpm/N_nominal`.

Extends from Buildings.Obsolete.Fluid.Movers.BaseClasses.FlowMachineInterface (Partial model with performance curves for fans or pumps), Buildings.Obsolete.Fluid.Movers.BaseClasses.PartialFlowMachine (Partial model to interface fan or pump models with the medium).

### Parameters

Type | Name | Default | Description
--- | --- | --- | ---
Density | rho_default | Medium.density_pTX(p=Medium.... | Fluid density at medium default state [kg/m3]
replaceable package Medium | PartialMedium | Medium in the component
Boolean | addPowerToMedium | true | Set to false to avoid any power (=heat and flow work) being added to medium (may give simpler equations)
Characteristics
Boolean | use_powerCharacteristic | false | Use powerCharacteristic (vs. efficiencyCharacteristic)
Boolean | motorCooledByFluid | true | If true, then motor heat is added to fluid stream
efficiencyParameters | motorEfficiency |  | Normalized volume flow rate vs. efficiency
efficiencyParameters | hydraulicEfficiency |  | Normalized volume flow rate vs. efficiency
AngularVelocity_rpm | N_nominal | 1500 | Nominal rotational speed for flow characteristic [1/min]
flowParameters | pressure |  | Volume flow rate vs. total pressure rise
powerParameters | power |  | Volume flow rate vs. electrical power consumption
Initialization
Real | r_V.start | 1 | Ratio V_flow/V_flow_max [1]
MassFlowRate | m_flow.start | 0 | Mass flow rate from port_a to port_b (m_flow > 0 is design flow direction) [kg/s]
Pressure | dp.start | 0 | Pressure difference between port_a and port_b [Pa]
Nominal condition
MassFlowRate | m_flow_nominal | max(pressure.V_flow)*rho_def... | Nominal mass flow rate [kg/s]
Advanced
Boolean | homotopyInitialization | true | = true, use homotopy method
MassFlowRate | m_flow_small | 1E-4*abs(m_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
Dynamics
Filtered speed
Boolean | filteredSpeed | true | = true, if speed is filtered with a 2nd order CriticalDamping filter
Time | riseTime | 30 | Rise time of the filter (time to reach 99.6 % of the speed) [s]
Init | init | Modelica.Blocks.Types.Init.I... | Type of initialization (no init/steady state/initial state/initial output)
Real | N_start | 0 | Initial value of speed
Equations
Dynamics | energyDynamics | Modelica.Fluid.Types.Dynamic... | Formulation of energy balance
Dynamics | massDynamics | energyDynamics | Formulation of mass balance
Boolean | dynamicBalance | true | Set to true to use a dynamic balance, which often leads to smaller systems of equations
Real | mSenFac | 1 | Factor for scaling the sensible thermal mass of the volume
Nominal condition
Time | tau | 1 | Time constant of fluid volume for nominal flow, used if dynamicBalance=true [s]
Initialization
AbsolutePressure | p_start | Medium.p_default | Start value of pressure [Pa]
Temperature | T_start | Medium.T_default | Start value of temperature [K]
MassFraction | X_start[Medium.nX] | Medium.X_default | Start value of mass fractions m_i/m [kg/kg]
ExtraProperty | C_start[Medium.nC] | fill(0, Medium.nC) | Start value of trace substances
ExtraProperty | C_nominal[Medium.nC] | fill(1E-2, Medium.nC) | Nominal value of trace substances. (Set to typical order of magnitude.)
Assumptions
Boolean | allowFlowReversal | true | = true to allow flow reversal, false restricts to design direction (port_a -> port_b)

### Connectors

Type | Name | Description
--- | --- | ---
output RealOutput | P | Electrical power consumed [W]
output RealOutput | N_actual | [1/min]
FluidPort_a | port_a | Fluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_b | port_b | Fluid connector b (positive design flow direction is from port_a to port_b)
HeatPort_a | heatPort | Heat dissipation to environment

### Modelica definition

partial model PrescribedFlowMachine "Partial model for fan or pump with speed (y or Nrpm) as input signal" extends Buildings.Obsolete.Fluid.Movers.BaseClasses.FlowMachineInterface( V_flow_max(start=V_flow_nominal), final rho_default = Medium.density_pTX( p=Medium.p_default, T=Medium.T_default, X=Medium.X_default)); extends Buildings.Obsolete.Fluid.Movers.BaseClasses.PartialFlowMachine( final m_flow_nominal = max(pressure.V_flow)*rho_default, preSou(final control_m_flow=false)); // Models protected Modelica.Blocks.Sources.RealExpression dpMac(y=-dpMachine) "Pressure drop of the pump or fan"; Modelica.Blocks.Sources.RealExpression PToMedium_flow(y=Q_flow + WFlo) if addPowerToMedium "Heat and work input into medium"; equation VMachine_flow = -port_b.m_flow/rho; rho = rho_in; connect(preSou.dp_in, dpMac.y); connect(PToMedium_flow.y, prePow.Q_flow); end PrescribedFlowMachine;