Modelica.Thermal.FluidHeatFlow.Components

Basic components (pipes, valves)

Information

This package contains components:

pipe without heat exchange
pipe with heat exchange
valve (simple controlled valve)

Pressure drop is taken from partial model SimpleFriction.
Thermodynamic equations are defined in partial models (package Partials).

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

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.Library2 (Icon for library where additional icon elements shall be added).

Package Content

Name Description

IsolatedPipe Pipe without heat exchange

HeatedPipe Pipe with heat exchange

Valve Simple valve

Name	Description
IsolatedPipe	Pipe without heat exchange
HeatedPipe	Pipe with heat exchange
Valve	Simple valve

Modelica.Thermal.FluidHeatFlow.Components.IsolatedPipe

Pipe without heat exchange

Modelica.Thermal.FluidHeatFlow.Components.IsolatedPipe

Information

Pipe without heat exchange.
Thermodynamic equations are defined by Partials.TwoPortMass(Q_flow = 0).
Note: Setting parameter m (mass of medium within pipe) to zero leads to neglection of temperature transient cv*m*der(T).

Extends from Interfaces.Partials.TwoPort (Partial model of two port), Interfaces.Partials.SimpleFriction (Simple friction model).

Parameters

Type Name Default Description

Medium medium FluidHeatFlow.Media.Medium() Medium in the component

Mass m Mass of medium [kg]

Temperature T0 Initial temperature of medium [K]

Real tapT 1 Defines temperature of heatPort between inlet and outlet temperature

Length h_g Geodetic height (heigth difference from flowPort_a to flowPort_b) [m]

Simple Friction

VolumeFlowRate V_flowLaminar Laminar volume flow [m3/s]

Pressure dpLaminar Laminar pressure drop [Pa]

VolumeFlowRate V_flowNominal Nominal volume flow [m3/s]

Pressure dpNominal Nominal pressure drop [Pa]

Real frictionLoss 0 Part of friction losses fed to medium

Type	Name	Default	Description
Medium	medium	FluidHeatFlow.Media.Medium()	Medium in the component
Mass	m		Mass of medium [kg]
Temperature	T0		Initial temperature of medium [K]
Real	tapT	1	Defines temperature of heatPort between inlet and outlet temperature
Length	h_g		Geodetic height (heigth difference from flowPort_a to flowPort_b) [m]
Simple Friction
VolumeFlowRate	V_flowLaminar		Laminar volume flow [m3/s]
Pressure	dpLaminar		Laminar pressure drop [Pa]
VolumeFlowRate	V_flowNominal		Nominal volume flow [m3/s]
Pressure	dpNominal		Nominal pressure drop [Pa]
Real	frictionLoss	0	Part of friction losses fed to medium

Connectors

Type Name Description

FlowPort_a flowPort_a

FlowPort_b flowPort_b

Type	Name	Description
FlowPort_a	flowPort_a
FlowPort_b	flowPort_b

Modelica definition

model IsolatedPipe "Pipe without heat exchange"

  extends Interfaces.Partials.TwoPort(final tapT=1);
  extends Interfaces.Partials.SimpleFriction;
  parameter Modelica.SIunits.Length h_g(start=0) 
    "Geodetic height (heigth difference from flowPort_a to flowPort_b)";
equation 
  // coupling with FrictionModel
  volumeFlow = V_flow;
  dp = pressureDrop + medium.rho*Modelica.Constants.g_n*h_g;
  // no energy exchange with medium
  Q_flow = Q_friction;
end IsolatedPipe;

Modelica.Thermal.FluidHeatFlow.Components.HeatedPipe

Pipe with heat exchange

Modelica.Thermal.FluidHeatFlow.Components.HeatedPipe

Information

Pipe with heat exchange.
Thermodynamic equations are defined by Partials.TwoPort.
Q_flow is defined by heatPort.Q_flow.
Note: Setting parameter m (mass of medium within pipe) to zero leads to neglection of temperature transient cv*m*der(T).
Note: Injecting heat into a pipe with zero massflow causes temperature rise defined by storing heat in medium's mass.

Extends from Interfaces.Partials.TwoPort (Partial model of two port), Interfaces.Partials.SimpleFriction (Simple friction model).

Parameters

Type	Name	Default	Description
Medium	medium	FluidHeatFlow.Media.Medium()	Medium in the component
Mass	m		Mass of medium [kg]
Temperature	T0		Initial temperature of medium [K]
Real	tapT	1	Defines temperature of heatPort between inlet and outlet temperature
Length	h_g		Geodetic height (heigth difference from flowPort_a to flowPort_b) [m]
Simple Friction
VolumeFlowRate	V_flowLaminar		Laminar volume flow [m3/s]
Pressure	dpLaminar		Laminar pressure drop [Pa]
VolumeFlowRate	V_flowNominal		Nominal volume flow [m3/s]
Pressure	dpNominal		Nominal pressure drop [Pa]
Real	frictionLoss	0	Part of friction losses fed to medium

Connectors

Type Name Description

FlowPort_a flowPort_a

FlowPort_b flowPort_b

HeatPort_a heatPort

Type	Name	Description
FlowPort_a	flowPort_a
FlowPort_b	flowPort_b
HeatPort_a	heatPort

Modelica definition

model HeatedPipe "Pipe with heat exchange"

  extends Interfaces.Partials.TwoPort;
  extends Interfaces.Partials.SimpleFriction;
  parameter Modelica.SIunits.Length h_g(start=0) 
    "Geodetic height (heigth difference from flowPort_a to flowPort_b)";
  Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a heatPort;
equation 
  // coupling with FrictionModel
  volumeFlow = V_flow;
  dp = pressureDrop + medium.rho*Modelica.Constants.g_n*h_g;
  // energy exchange with medium
  Q_flow = heatPort.Q_flow + Q_friction;
  // defines heatPort's temperature
  heatPort.T = T_q;
end HeatedPipe;

Modelica.Thermal.FluidHeatFlow.Components.Valve

Simple valve

Modelica.Thermal.FluidHeatFlow.Components.Valve

Information

Simple controlled valve.
Standard characteristic Kv=f (y) is given at standard conditions (dp0, rho0),
either linear : Kv/Kv1 = Kv0/Kv1 + (1-Kv0/Kv1) * y/Y1 or exponential: Kv/Kv1 = Kv0/Kv1 * exp[ln(Kv1/Kv0) * y/Y1] where: Kv0 ... min. flow @ y = 0 Y1 .... max. valve opening Kv1 ... max. flow @ y = Y1 Flow resistance under real conditions is calculated by
V_flow**2 * rho / dp = Kv(y)**2 * rho0 / dp0

Extends from Interfaces.Partials.TwoPort (Partial model of two port).

Parameters

Type Name Default Description

Medium medium FluidHeatFlow.Media.Medium() Medium in the component

Temperature T0 Initial temperature of medium [K]

Real tapT 1 Defines temperature of heatPort between inlet and outlet temperature

Real frictionLoss Part of friction losses fed to medium

Standard characteristic

Boolean LinearCharacteristic Type of characteristic

Real y1 Max. valve opening

VolumeFlowRate Kv1 Max. flow @ y = y1 [m3/s]

Real kv0 Leakage flow / max.flow @ y = 0

Pressure dp0 Standard pressure drop [Pa]

Density rho0 Standard medium's density [kg/m3]

Type	Name	Default	Description
Medium	medium	FluidHeatFlow.Media.Medium()	Medium in the component
Temperature	T0		Initial temperature of medium [K]
Real	tapT	1	Defines temperature of heatPort between inlet and outlet temperature
Real	frictionLoss		Part of friction losses fed to medium
Standard characteristic
Boolean	LinearCharacteristic		Type of characteristic
Real	y1		Max. valve opening
VolumeFlowRate	Kv1		Max. flow @ y = y1 [m3/s]
Real	kv0		Leakage flow / max.flow @ y = 0
Pressure	dp0		Standard pressure drop [Pa]
Density	rho0		Standard medium's density [kg/m3]

Connectors

Type Name Description

FlowPort_a flowPort_a

FlowPort_b flowPort_b

input RealInput y

Type	Name	Description
FlowPort_a	flowPort_a
FlowPort_b	flowPort_b
input RealInput	y

Modelica definition

model Valve "Simple valve"

  extends Interfaces.Partials.TwoPort(m(start=0), final tapT=1);
  parameter Boolean LinearCharacteristic(start=true) "Type of characteristic";
  parameter Real y1(min=small, start=1) "Max. valve opening";
  parameter Modelica.SIunits.VolumeFlowRate Kv1(min=small, start=1) 
    "Max. flow @ y = y1";
  parameter Real kv0(min=small,max=1-small, start=0.01) 
    "Leakage flow / max.flow @ y = 0";
  parameter Modelica.SIunits.Pressure dp0(start=1) "Standard pressure drop";
  parameter Modelica.SIunits.Density rho0(start=10) "Standard medium's density";
  parameter Real frictionLoss(min=0, max=1, start=0) 
    "Part of friction losses fed to medium";
protected 
  constant Modelica.SIunits.VolumeFlowRate unitVolumeFlowRate = 1;
  constant Real small = Modelica.Constants.small;
  constant Modelica.SIunits.VolumeFlowRate smallVolumeFlowRate = eps*unitVolumeFlowRate;
  constant Real eps = Modelica.Constants.eps;
  Real yLim = max(min(y,y1),0) "Limited valve opening";
  Modelica.SIunits.VolumeFlowRate Kv "Standard flow rate";
public 
  Modelica.Blocks.Interfaces.RealInput y;
initial algorithm 
  assert(y1>small, "Valve characteristic: y1 has to be > 0 !");
  assert(Kv1>smallVolumeFlowRate, "Valve characteristic: Kv1 has to be > 0 !");
  assert(kv0>small, "Valve characteristic: kv0 has to be > 0 !");
  assert(kv0<1-eps, "Valve characteristic: kv0 has to be < 1 !");
equation 
  // evaluate standard characteristic
  Kv/Kv1 = if LinearCharacteristic then (kv0 + (1-kv0)*yLim/y1) else kv0*exp(Modelica.Math.log(1/kv0)*yLim/y1);
  // pressure drop under real conditions
  dp/dp0 = medium.rho/rho0*(V_flow/Kv)*abs(V_flow/Kv);
  // no energy exchange with medium
  Q_flow = frictionLoss*V_flow*dp;
end Valve;

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