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MapleSim Hydraulics Library from Modelon

Gas Volume BB  Refined model of charge gas

The Gas Volume BB component describes the behavior of the charge gas in an accumulator according to the Beattie-Bridgeman equation.

 

Equations

Variables

Connections

Parameters

Constants

Equations

ρ=ρoilp=pabs,T=Toil,vair=vgasoil,psat=psat

Cv=pgas2temp2C33+pgas2tempC32+pgastemp2C23+pgas2C31+pgastempC22+temp2C13+pgasC21+tempC12+C11

pgas=100000Rtemp1Ctemp3spezVolspezVol+B01BspezVolspezVol2100000A01AAspezVolspezVol2

spezVol=GasVolmgas

GasVolDot=mflowAρ

spezVolDot=GasVolDotmgas

Toil=T0oil+ΔTsystem

pabs=pgas

pabs=pA+patmoil

tGasVol=GasVolDot

ttemp=pgasΤtemp2spezVol4+ΤFtemp2A0+3ΤCFRspezVol2+ΤAAFtemp2A0+3ΤCFRB0spezVol3BB0CFRΤspezVolDot+Θtemp2cv¯+temp3cv¯spezVol4CvΤtemp2spezVol4

Variables

Name

Value

Units

Description

Modelica ID

pabs

 

Pa

Absolute pressure

p_abs

ρ

 

kgm3

Gas Density

rho

Toil

 

K

Local temperature of oil

T_oil

psat

[1]

Pa

Gas saturation pressure

p_sat

temp

 

K

Gas temperature in K, initial condition

temp

GasVol

 

m3

Gas volume in m^3, initial condition

GasVol

GasVolDot

 

 

Change of gas volume, d gasvolume / d time in m^3 / s

GasVolDot

pgas

 

Pa

Gas pressure in Pa

pgas

Cv

 

 

spec. thermal capacity, constant volume

Cv

spezVol

 

 

Gas volume / gm

spezVol

spezVolDot

 

 

 

spezVolDot

[1] oil.gasSaturationPressureT=Toil,vgas=oil.vgas

Connections

Name

Description

Modelica ID

portA

Hydraulic port where oil enters the component

port_A

oil

 

oil

Parameters

Name

Default

Units

Description

Modelica ID

ΔTsystem

0

K

Temperature offset from system temperature

dT_system

mgas

0.0394

kg

Gas mass (default is for 1e-3 m3 und 3.5 MPa)

gm

VgasT0

0.001

m3

Gas volume at t = 0

GasVol_T0

Τ

5

s

Thermal timeconstant

Tau

Θ

300

K

Temperature of environment

Theta

cv¯

750

 

Mean value of cv

CvBar

Constants

Name

Value

Units

Description

Modelica ID

R

0.00297

 

 

R

A0

0.00174

 

 

A0

B0

0.0018

 

 

B0

AA

9.34·10-4

 

 

AA

B

-2.47·10-4

 

 

B

C

5.09·10-8

 

 

C

F

105

 

 

F

C11

745.005

 

 

C11

C12

0.0576

 

 

C12

C13

1.11·10-4

 

 

C13

C21

9.15·10-6

 

 

C21

C22

-3.3·10-8

 

 

C22

C23

3.08·10-11

 

 

C23

C31

-5.61·10-14

 

 

C31

C32

2.15·10-16

 

 

C32

C33

-2.03·10-19

 

 

C33

See Also

Volumes

MapleSim Hydraulics Library from Modelon Overview

 


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