Component 68: Control Valve (External Pressure Limit)

Specifications

Line connections
1	Inlet
2	Outlet
3	Inlet for measured value

General User Input Values Physics Used Displays Example

General

For FSPEC=0 ("Simple throttle"), this component acts like a throttle.

For FSPEC=1 ("with pressure control"), the pressure P1 is restricted according to the following rule

P1MIN=P2+DP12

P1 = P3 for P1MIN<P3

P1 = P1MIN for P1MIN>P3

This component functions like component 59 with the difference that the holding pressure P1MIN can be changed by means of a control connection.

As these components can also be used as a valve, the design of these components can be toggled between flap and valve.

Model

Besides the instruction for the calculation of pressure explained above, the following relations are valid:

H1 = H2 and M1 = M2

User Input Values

FDP12RN	Pressure loss handling Like in Parent Profile (Sub profile option only) Expression =1: calculated by DP12N=DP12RN (absolute)
DP12RN	Pressure loss (nominal) [absolute or relative to P1]
FVOL	Volume dependency of the pressure loss Like in Parent Profile (Sub profile option only) Expression =0: without ( DP/DPN = (M/MN)*2 ) =1: with ( DP/DPN = V/VN(M/MN)**2 )
FSPEC	Specifications Like in Parent Profile (Sub profile option only) Expression =0: pure throttling =1: with pressure limitation
FMODE	Calculation mode Like in Parent Profile (Sub profile option only) Expression =0: GLOBAL =1: local off-design
M1N	Mass flow (nominal)
V1N	Specific volume at inlet 1 (nominal)

The identification value that is marked in blue is a reference quantity for off-design mode. The actual off-design values refer to these quantities in the equations used.

Generally, all inputs that are visible are required. But, often default values are provided.

For more information on colour of the input fields and their descriptions see Edit Component\Specification values

For more information on design vs. off-design and nominal values see General\Accept Nominal values

Physics used

Equations

All cases

DP12N=DP12RN

if FVOL= Without, then {

F1 = (M1/M1N) ** 2

if FMODE=1 , then F1=1.0

}

if FVOL= With, then {

F1 = V1/V1N*(M1/M1N) ** 2

if FMODE=1 , then F1=1.0

}

DP12=F1*DP12N

P1MIN=P2+DP12

P1 = P3 for P3 < P1MIN (1a)

P1 = P1MIN for P3 < P1MIN (1b)

H2 = H1 (2)

T2 = f (P2, H2)

M2 = M1 (3)

Q2 = Q1

Component Displays

Display Option 1

Display Option 2

Example

Click here >> Component 68 Demo << to load an example.