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MapleSim Hydraulics Library from Modelon

Piston Gas Accumulator  A gas filled piston accumulator

The gas model in the accumulator is based on the model from:

Span, R., Lemmon, E.W., Jacobsen, R.T, Wagner, W., and Yokozeki, A. "A Reference Equation of State for the Thermodynamic Properties of Nitrogen for Temperatures from 63.151 to 1000 K and Pressures to 2200 MPa," J. Phys. Chem. Ref. Data, 29(6):1361-1433, 2000.

The equation of state (EOS) has been compared to the implementation of REFPROP and gives the same results. This implementation covers only the 1-phase region. It is possible to choose a version that uses the corresponding ideal part only, but this is not recommended.

Connections

Name

Description

Modelica ID

portA

 

port_A

Parameters

General Parameters

Name

Default

Units

Description

Modelica ID

nports

0

 

Number of ports

nPorts

di

 

m

Inner diameter of cylinder

d_i

Vdead

10-6

m3

Minimum oil volume

dead_volume

m

110

kg

Mass of piston

m

smax

12

m

Piston maximum stroke (between stiff, compliant cylinder walls)

s_max

piston

0.02

m

Length of piston

piston_length

sstart

12smax

m

Cylinder initial stroke: default is half full

s_start

ppreload

4.·107

Pa

Preload pressure for empty accumulator

p_preload

ΔTsystem

0

K

Temperature offset from system temperature

dT_system

Tstart

300

K

Initial gas Temperature

T_start

use time constant

true

 

If true, a time constant is used for the thermal behavior, otherwise a heat transfer law

use_time_constant

tthermal

60

s

Thermal time constant

t_thermal

α

150

Wm2K

Heat transfer coefficient

alpha

Tenv

298.15

K

Fixed environment temperature

T_env

initial filling

1

 

Initial filling of gas cylinder as fraction of total

initialFilling

Friction Parameters

Name

Default

Units

Description

Modelica ID

dviscous

4.·103

Nsm

 

viscous_damping

Constant Parameters

Name

Default

Units

Description

Modelica ID

Apiston

[1]

m2

Piston area

piston_area

Vstart

sstartApiston

m3

Oil volume at initialization

V_start

[1] 14di2π

See Also

Volumes, MapleSim Hydraulics Library from Modelon Overview


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