Modelica.Thermal.FluidHeatFlow.Components

Basic components (pipes, valves)

Information

This package contains components.

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

Extends from Modelica.Icons.Package (Icon for standard packages).

Package Content

Name	Description
Pipe	Pipe with optional heat exchange
Valve	Simple valve
OpenTank	Model of a tank under ambient pressure
Cylinder	Simple model of a piston in a cylinder
OneWayValve	Simple one-way valve

Modelica.Thermal.FluidHeatFlow.Components.Pipe

Pipe with optional heat exchange

Information

Pipe with optional heat exchange.

Thermodynamic equations are defined by BaseClasses.TwoPort. Q_flow is defined by heatPort.Q_flow (useHeatPort=true) or zero (useHeatPort=false).

Note: Setting parameter m (mass of medium within pipe) to zero leads to neglect of temperature transient cv*m*der(T).

Note: Injecting heat into a pipe with zero mass flow causes temperature rise defined by storing heat in medium's mass.

Extends from FluidHeatFlow.BaseClasses.TwoPort (Partial model of two port), FluidHeatFlow.BaseClasses.SimpleFriction (Simple friction model).

Parameters

Connectors

Modelica.Thermal.FluidHeatFlow.Components.Valve

Simple 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[log(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 FluidHeatFlow.BaseClasses.TwoPort (Partial model of two port).

Parameters

Connectors

Modelica.Thermal.FluidHeatFlow.Components.OpenTank

Model of a tank under ambient pressure

Information

This is a simple model of an open tank with volume A*h. The level and the temperature of the medium are measured and provided as output.

Note: If the level of the medium reaches 0 (minimum) or h (maximum), an assertion is triggered.

Note: The flowPort is assumed to be at the bottom. Therefore the pressure at the flowPort is ambient pressure + level*rho*g.

• If the mass flow rate at the port goes into the tank the level increases and the mixing rule is applied to obtain the temperature change of the medium in the tank.
• If the mass flow rate at the port goes out of the tank the level decreases, the temperature of the outflowing medium is defined by the the temperature of the medium in the tank.

It is assumed that the medium in the tank has the same temperature over the whole volume, i.e. mixed thoroughly.

Via the optional heatPort the medium in the tank can be cooled or heated.

Extends from FluidHeatFlow.BaseClasses.SinglePortBottom (Partial model of a single port at the bottom).

Parameters

Connectors

Modelica.Thermal.FluidHeatFlow.Components.Cylinder

Simple model of a piston in a cylinder

Information

This is a simple model of a piston in a cylinder:

The translational flange is connected to the piston, the cylinder has a flowPort at the bottom.

The position of the piston within the cylinder goes from 0 at the bottom to L (length of the cylinder) at the top of the cylinder. If the piston leaves the cylinder, an assertion is triggered.

• A movement of the piston is coupled with volume flow through the flowPort.
• The force at the piston is equal to pressure of the fluid times A (cross section of the piston).

The piston is considered without mass.

Note: Take care of the initial conditions. The position of the piston (relative to the support) should be in the range (0, L). The position of the flange (as well as of the support, if useSupport=true) is influenced by connected components.

Extends from FluidHeatFlow.BaseClasses.SinglePortLeft (Partial model of a single port at the left), Modelica.Mechanics.Translational.Interfaces.PartialElementaryOneFlangeAndSupport2 (Partial model for a component with one translational 1-dim. shaft flange and a support used for textual modeling, i.e., for elementary models).

Parameters

Connectors

Modelica.Thermal.FluidHeatFlow.Components.OneWayValve

Simple one-way valve

Information

Simple one-way valve, comparable to the electrical ideal diode model.

• from flowPort_a to flowPort_b: small pressure drop, linearly dependent on volumeFlow
• from flowPort_b to flowPort_a: small leakage flow, linearly dependent on pressure drop

Extends from FluidHeatFlow.BaseClasses.TwoPort (Partial model of two port).

Parameters

Connectors