Air Valve - MapleSim Help
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Air Valve

Control the flow of Air

 

Description

Equations

Variables

Connections

Parameters

See Also

Description

The Air Valve component models a generic valve which is to control the flow for the lumped thermal fluid simulation of Air. In this component, pressure difference and mass flow rate is calculated based mainly on valve opening.

 

Equations

The calculation is changed based on parameter values of Type of flow, Calculation Type, and Dynamics of mass in the Air Settings component.

 

Type of flow = Linear and Dynamics of mass = Static

Calculation Type = true

   Pressure difference is calculated with:

dp=1Aα__linearmflow

   Mass flow rate is calculated with:

mflow=opening__act`port_a.mflow`

`port_b.mflow`=mflow

Calculation Type = false

   Pressure difference is calculated with:

dp=1Aopening__actα__linearmflow

   Mass flow rate is calculated with:

mflow=`port_a.mflow`

`port_b.mflow`=mflow

Type of flow = Linear and Dynamics of mass = Dynamic

Mass flow rate is calculated with:

mflow=opening__actAα__lineardp

Mass flow rate is calculated with:

`port_a.mflow`=mflow

`port_b.mflow`=mflow

Type of flow = Square root and Dynamics of mass = Static

Calculation Type = true

   Pressure difference is calculated with:

dp=1Aα__sqrt2mflow2signmflow

   Mass flow rate is calculated with:

mflow=opening__act`port_a.mflow`

`port_b.mflow`=mflow

Calculation Type = false

   Pressure difference is calculated with:

dp=1Aopening__actα__sqrt2mflow2signmflow

   Mass flow rate is calculated with:

mflow=`port_a.mflow`

`port_b.mflow`=mflow

Type of flow = Square root and Dynamics of mass = Dynamic

In theory, Mass flow rate is calculated with:

mflow=opening__actAα__sqrtdp

In the Heat Transfer Library, the following equation is used to resolve difficulties of the numerical calculation:

mflow=opening__actAα__sqrt`HeatTransfer.Functions.regRoot`dp,sharpness

Mass flow rate is calculated with:

`port_a.mflow`=mflow

`port_b.mflow`=mflow

(*) `HeatTransfer.Functions.regRoot` is the same function as `Modelica.Fluid.Utilities.regRoot`. To check the details of the package and view the original documentation, which includes author and copyright information, click here.

 

Type of flow = Darcy-Weisbach and Dynamics of mass = Static

Calculation Type = true

   Pressure difference is calculated with:

dp=12λLD__hA2{inStream`port_a.rho`dp0inStream`port_b.rho`othersmflow2signmflow

   Mass flow rate is calculated with:

mflow=opening__act`port_a.mflow`

`port_b.mflow`=mflow

Calculation Type = false

   Pressure difference is calculated with:

dp=12λLD__hAopening__act2{inStream`port_a.rho`dp0inStream`port_b.rho`othersmflow2signmflow

   Mass flow rate is calculated with:

mflow=`port_a.mflow`

`port_b.mflow`=mflow

Type of flow = Darcy-Weisbach and Dynamics of mass = Dynamic

Mass flow rate is calculated with in theory:

mflow=2D__hopening__actA2λL{inStream`port_a.rho`dp0inStream`port_b.rho`othersdp

In the Heat Transfer Library, the following equation is used to resolve difficulties of the numerical calculation:

mflow=2D__hopening__actA2λL`HeatTransfer.Functions.regRoot2`dp,dp_small,inStream`port_a.rho`,inStream`port_b.rho`,true,sharpness

Mass flow rate is calculated with:

`port_a.mflow`=mflow

`port_b.mflow`=mflow

(*) `HeatTransfer.Functions.regRoot2` is the same function as `Modelica.Fluid.Utilities.regRoot2`. To check the details of the package and view the original documentation, which includes author and copyright information, click here.

 

If Dynamic of mass = Static, valve opening is calculated with:

opening__act=min1.0,maxopening,1.01010

On the other hand, if Dynamic of mass = Dynamic, it is calculated with:

ⅆopening__actⅆt=min1.0,maxopening,1.01010opening__actT__const

Common definitions are the following:

dp=`port_a.p``port_b.p`

v=mflow{inStream`port_a.rho`dp0inStream`port_b.rho`othersopening__actA

`port_a.hflow`=inStream`port_b.hflow`

`port_b.hflow`=inStream`port_a.hflow`

`port_a.rho`=inStream`port_b.rho`

`port_b.rho`=inStream`port_a.rho`

`port_a.T`=inStream`port_b.T`

`port_b.T`=inStream`port_a.T`

 

Variables

Symbol

Units

Description

Modelica ID

dp

Pa

Pressure difference

p

mflow

kgs

Mass flow rate

mflow

v

ms

Velocity of flow

v

opening__act

Valve opening used for Flow calculation

opening_act

typeA_opening

Valve opening used if Calculation type = true and Dynamic of mass = Static (Internal calculation use only)

typeA_opening

typeB_opening

Valve opening used if Calculation type = false and Dynamic of mass = Static (Internal calculation use only)

typeB_opening

Connections

Name

Description

Modelica ID

port__a

Air Port

port_a

port__b

Air Port

port_b

opening

Valve opening

opening

Parameters

Symbol

Default

Units

Description

Modelica ID

Airsimulationsettings 

AirSettings1

Specify a component of Air simulation settings

Settings

Type offlow

Linear

Select Flow calculation type

 - Linear

 - Square root

 - Darcy-Weisbach

TypeOfFlow

α__linear

10

Flow coefficient for Linear type

alpha_lin

α__sqrt

60

Flow coefficient for Square root type

alpha_sqrt

L

0.1

m

Pipe length (Only for Darcy-Weisbach)

L

D__h

0.1

m

Internal hydraulic diameter (Only for Darcy-Weisbach)

Dh

A

Pi400

m2

Flow area

A

λ

0.000015

Friction coefficient for Darcy-Weisbach equation

lambda

dp__small

0.1

Pa

Approximation of function for |dp| <= dp_small

dp_small

sharpness

1.0

Sharpness of approximation for sqrt(dp) and sqrt(rho * dp)

sharpness

T__const

0.001

s

Time constant for Valve opening (Only if Dynamic of mass = Dynamic)

T_const

Calculation Type

true

If true, Mass flow rate is controlled by Valve opening directly. If false, the calculation of Mass flow rate is consistent with Dynamic of mass = Dynamic (Only if Dynamic of mass = Static)

CalType

See Also

Heat Transfer Library Overview

Air Overview

Air Basic Overview