Modelica.Thermal.FluidHeatFlow.Interfaces.Partials

Partial models

Information


This package contains partial models, defining in a very compact way the basic thermodynamic equations used by the different components.
Main Authors:

Anton Haumer
Technical Consulting & Electrical Engineering
A-3423 St.Andrae-Woerdern, Austria
email: a.haumer@haumer.at

Dr.Christian Kral
Österreichisches Forschungs- und Prüfzentrum Arsenal Ges.m.b.H.
arsenal research
Giefinggasse 2
A-1210 Vienna, Austria

Copyright © 1998-2009, Modelica Association, Anton Haumer and arsenal research.

The Modelica package is free software; it can be redistributed and/or modified under the terms of the Modelica license, see the license conditions and the accompanying disclaimer here.

Extends from Modelica.Icons.Library (Icon for library).

Package Content

NameDescription
SimpleFriction Simple friction model
Modelica.Thermal.FluidHeatFlow.Interfaces.Partials.TwoPort TwoPort Partial model of two port
Modelica.Thermal.FluidHeatFlow.Interfaces.Partials.Ambient Ambient Partial model of ambient
Modelica.Thermal.FluidHeatFlow.Interfaces.Partials.AbsoluteSensor AbsoluteSensor Partial model of absolute sensor
Modelica.Thermal.FluidHeatFlow.Interfaces.Partials.RelativeSensor RelativeSensor Partial model of relative sensor
Modelica.Thermal.FluidHeatFlow.Interfaces.Partials.FlowSensor FlowSensor Partial model of flow sensor


Modelica.Thermal.FluidHeatFlow.Interfaces.Partials.SimpleFriction

Simple friction model

Modelica.Thermal.FluidHeatFlow.Interfaces.Partials.SimpleFriction

Information


Definition of relationship between pressure drop and volume flow rate:
-V_flowLaminar < VolumeFlow < +V_flowLaminar: laminar i.e. linear dependency of pressure drop on volume flow.
-V_flowLaminar > VolumeFlow or VolumeFlow < +V_flowLaminar: turbulent i.e. quadratic dependency of pressure drop on volume flow.
Linear and quadratic dependency are coupled smoothly at V_flowLaminar / dpLaminar.
Quadratic dependency is defined by nominal volume flow and pressure drop (V_flowNominal / dpNominal).
See also sketch at diagram layer.

Parameters

TypeNameDefaultDescription
Simple Friction
VolumeFlowRateV_flowLaminar Laminar volume flow [m3/s]
PressuredpLaminar Laminar pressure drop [Pa]
VolumeFlowRateV_flowNominal Nominal volume flow [m3/s]
PressuredpNominal Nominal pressure drop [Pa]
RealfrictionLoss0Part of friction losses fed to medium

Modelica definition

partial model SimpleFriction "Simple friction model"

  parameter Modelica.SIunits.VolumeFlowRate V_flowLaminar(min=Modelica.Constants.small, start=0.1) 
    "Laminar volume flow";
  parameter Modelica.SIunits.Pressure dpLaminar(start=0.1) 
    "Laminar pressure drop";
  parameter Modelica.SIunits.VolumeFlowRate V_flowNominal(start=1) 
    "Nominal volume flow";
  parameter Modelica.SIunits.Pressure dpNominal(start=1) 
    "Nominal pressure drop";
  parameter Real frictionLoss(min=0, max=1) = 0 
    "Part of friction losses fed to medium";
  Modelica.SIunits.Pressure pressureDrop;
  Modelica.SIunits.VolumeFlowRate volumeFlow;
  Modelica.SIunits.Power Q_friction;
protected 
  parameter Modelica.SIunits.Pressure dpNomMin=dpLaminar/V_flowLaminar*V_flowNominal;
  parameter Real k(final unit="Pa.s2/m6", fixed=false);
initial algorithm 
  assert(V_flowNominal>V_flowLaminar,
    "SimpleFriction: V_flowNominal has to be > V_flowLaminar!");
  assert(dpNominal>=dpNomMin,
    "SimpleFriction: dpNominal has to be > dpLaminar/V_flowLaminar*V_flowNominal!");
  k:=(dpNominal - dpNomMin)/(V_flowNominal - V_flowLaminar)^2;
equation 
  if     volumeFlow > +V_flowLaminar then
    pressureDrop = +dpLaminar/V_flowLaminar*volumeFlow + k*(volumeFlow - V_flowLaminar)^2;
  elseif volumeFlow < -V_flowLaminar then
    pressureDrop = +dpLaminar/V_flowLaminar*volumeFlow - k*(volumeFlow + V_flowLaminar)^2;
  else
    pressureDrop =  dpLaminar/V_flowLaminar*volumeFlow;
  end if;
  Q_friction = frictionLoss*volumeFlow*pressureDrop;
end SimpleFriction;

Modelica.Thermal.FluidHeatFlow.Interfaces.Partials.TwoPort Modelica.Thermal.FluidHeatFlow.Interfaces.Partials.TwoPort

Partial model of two port

Modelica.Thermal.FluidHeatFlow.Interfaces.Partials.TwoPort

Information


Partial model with two flowPorts.
Possible heat exchange with the ambient is defined by Q_flow; setting this = 0 means no energy exchange.
Setting parameter m (mass of medium within pipe) to zero leads to neglection of temperature transient cv*m*der(T).
Mixing rule is applied.
Parameter 0 < tapT < 1 defines temperature of heatPort between medium's inlet and outlet temperature.

Parameters

TypeNameDefaultDescription
MediummediumFluidHeatFlow.Media.Medium()Medium in the component
Massm Mass of medium [kg]
TemperatureT0 Initial temperature of medium [K]
RealtapT1Defines temperature of heatPort between inlet and outlet temperature

Connectors

TypeNameDescription
FlowPort_aflowPort_a 
FlowPort_bflowPort_b 

Modelica definition

partial model TwoPort "Partial model of two port"

  parameter FluidHeatFlow.Media.Medium medium=FluidHeatFlow.Media.Medium() 
    "Medium in the component";
  parameter Modelica.SIunits.Mass m(start=1) "Mass of medium";
  parameter Modelica.SIunits.Temperature T0(start=293.15, displayUnit="degC") 
    "Initial temperature of medium";
  parameter Real tapT(final min=0, final max=1)=1 
    "Defines temperature of heatPort between inlet and outlet temperature";
  Modelica.SIunits.Pressure dp=flowPort_a.p - flowPort_b.p "Pressure drop a->b";
  Modelica.SIunits.VolumeFlowRate V_flow=flowPort_a.m_flow/medium.rho 
    "Volume flow a->b";
  Modelica.SIunits.HeatFlowRate Q_flow "Heat exchange with ambient";
  output Modelica.SIunits.Temperature T(start=T0) 
    "Outlet temperature of medium";
  output Modelica.SIunits.Temperature T_a=flowPort_a.h/medium.cp 
    "Temperature at flowPort_a";
  output Modelica.SIunits.Temperature T_b=flowPort_b.h/medium.cp 
    "Temperature at flowPort_b";
  output Modelica.SIunits.TemperatureDifference dT=if noEvent(V_flow>=0) then T-T_a else T_b-T 
    "Temperature increase of coolant in flow direction";
protected 
  Modelica.SIunits.SpecificEnthalpy h = medium.cp*T 
    "Medium's specific enthalpy";
  Modelica.SIunits.Temperature T_q = T  - noEvent(sign(V_flow))*(1 - tapT)*dT 
    "Temperature relevant for heat exchange with ambient";
public 
  Interfaces.FlowPort_a flowPort_a(final medium=medium);
  Interfaces.FlowPort_b flowPort_b(final medium=medium);
equation 
  // mass balance
  flowPort_a.m_flow + flowPort_b.m_flow = 0;
  // energy balance
  if m>Modelica.Constants.small then
    flowPort_a.H_flow + flowPort_b.H_flow + Q_flow = m*medium.cv*der(T);
  else
    flowPort_a.H_flow + flowPort_b.H_flow + Q_flow = 0;
  end if;
  // massflow a->b mixing rule at a, energy flow at b defined by medium's temperature
  // massflow b->a mixing rule at b, energy flow at a defined by medium's temperature
  flowPort_a.H_flow = semiLinear(flowPort_a.m_flow,flowPort_a.h,h);
  flowPort_b.H_flow = semiLinear(flowPort_b.m_flow,flowPort_b.h,h);
end TwoPort;

Modelica.Thermal.FluidHeatFlow.Interfaces.Partials.Ambient Modelica.Thermal.FluidHeatFlow.Interfaces.Partials.Ambient

Partial model of ambient

Modelica.Thermal.FluidHeatFlow.Interfaces.Partials.Ambient

Information


Partial model of (Infinite) ambient, defines pressure and temperature.

Parameters

TypeNameDefaultDescription
MediummediumFluidHeatFlow.Media.Medium()Ambient medium

Connectors

TypeNameDescription
FlowPort_aflowPort 

Modelica definition

partial model Ambient "Partial model of ambient"

  parameter FluidHeatFlow.Media.Medium medium=FluidHeatFlow.Media.Medium() 
    "Ambient medium";
  output Modelica.SIunits.Temperature T "Outlet temperature of medium";
  output Modelica.SIunits.Temperature T_port=flowPort.h/medium.cp 
    "Temperature at flowPort_a";
protected 
  Modelica.SIunits.SpecificEnthalpy h = medium.cp*T;
public 
  Interfaces.FlowPort_a flowPort(final medium=medium);
equation 
  // massflow -> ambient: mixing rule
  // massflow <- ambient: energy flow defined by ambient's temperature
  flowPort.H_flow = semiLinear(flowPort.m_flow,flowPort.h,h);
end Ambient;

Modelica.Thermal.FluidHeatFlow.Interfaces.Partials.AbsoluteSensor Modelica.Thermal.FluidHeatFlow.Interfaces.Partials.AbsoluteSensor

Partial model of absolute sensor

Modelica.Thermal.FluidHeatFlow.Interfaces.Partials.AbsoluteSensor

Information


Partial model for an absolute sensor (pressure/temperature).
Pressure, mass flow, temperature and enthalpy flow of medium are not affected.

Parameters

TypeNameDefaultDescription
MediummediumFluidHeatFlow.Media.Medium()Sensor's medium

Connectors

TypeNameDescription
FlowPort_aflowPort 
output RealOutputy 

Modelica definition

partial model AbsoluteSensor "Partial model of absolute sensor"

  parameter FluidHeatFlow.Media.Medium medium=FluidHeatFlow.Media.Medium() 
    "Sensor's medium";
  Interfaces.FlowPort_a flowPort(final medium=medium);
  Modelica.Blocks.Interfaces.RealOutput y;
equation 
  // no mass exchange
  flowPort.m_flow = 0;
  // no energy exchange
  flowPort.H_flow = 0;
end AbsoluteSensor;

Modelica.Thermal.FluidHeatFlow.Interfaces.Partials.RelativeSensor Modelica.Thermal.FluidHeatFlow.Interfaces.Partials.RelativeSensor

Partial model of relative sensor

Modelica.Thermal.FluidHeatFlow.Interfaces.Partials.RelativeSensor

Information


Partial model for a relative sensor (pressure drop/temperature difference).
Pressure, mass flow, temperature and enthalpy flow of medium are not affected.

Parameters

TypeNameDefaultDescription
MediummediumFluidHeatFlow.Media.Medium()Sensor's medium

Connectors

TypeNameDescription
FlowPort_aflowPort_a 
FlowPort_bflowPort_b 
output RealOutputy 

Modelica definition

partial model RelativeSensor "Partial model of relative sensor"

  parameter FluidHeatFlow.Media.Medium medium=FluidHeatFlow.Media.Medium() 
    "Sensor's medium";
  Interfaces.FlowPort_a flowPort_a(final medium=medium);
  Interfaces.FlowPort_b flowPort_b(final medium=medium);
  Modelica.Blocks.Interfaces.RealOutput y;
equation 
  // no mass exchange
  flowPort_a.m_flow = 0;
  flowPort_b.m_flow = 0;
  // no energy exchange
  flowPort_a.H_flow = 0;
  flowPort_b.H_flow = 0;
end RelativeSensor;

Modelica.Thermal.FluidHeatFlow.Interfaces.Partials.FlowSensor Modelica.Thermal.FluidHeatFlow.Interfaces.Partials.FlowSensor

Partial model of flow sensor

Modelica.Thermal.FluidHeatFlow.Interfaces.Partials.FlowSensor

Information


Partial model for a flow sensor (mass flow/heat flow).
Pressure, mass flow, temperature and enthalpy flow of medium are not affected, but mixing rule is applied.

Extends from TwoPort (Partial model of two port).

Parameters

TypeNameDefaultDescription
MediummediumFluidHeatFlow.Media.Medium()Medium in the component
Massm0Mass of medium [kg]
TemperatureT00Initial temperature of medium [K]
RealtapT1Defines temperature of heatPort between inlet and outlet temperature

Connectors

TypeNameDescription
FlowPort_aflowPort_a 
FlowPort_bflowPort_b 
output RealOutputy 

Modelica definition

partial model FlowSensor "Partial model of flow sensor"

  extends TwoPort(final m=0, final T0=0, final tapT=1);
  Modelica.Blocks.Interfaces.RealOutput y;
equation 
  // no pressure drop
  dp = 0;
  // no energy exchange
  Q_flow = 0;
end FlowSensor;

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