Pressure Compensator Valve (TL)

Pressure compensation valve in the thermal liquid network.

blockType: EngeeFluids.ThermalLiquid.Valves.PressureControl.Compensator

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/Physical Modeling/Fluids/Thermal Liquid/Valves & Orifices/Pressure Control Valves/Pressure Compensator Valve (TL)

Description

The Pressure Compensator Valve (TL) unit is a pressure compensation valve in a thermal liquid network, such as a pressure relief valve or pressure reducing valve. Use this unit to maintain pressure at the valve based on signals from another part of the system.

The differential pressure between ports X and Y is the control pressure . When the control pressure value reaches or exceeds the set pressure, the valve opens or closes depending on the value of the parameter Valve specification. The pressure control range starts at the set pressure .

Pressure control

The unit regulates the pressure when exceeds . The unit continues to regulate pressure up to the value , defined as , where is the pressure control range.

Mass conservation

Mass conservation equation for mass conservation during valve passage:

The mass flow rate through the valve is calculated as follows:

where

- flow coefficient, the value of parameters Discharge coefficient;
- is the instantaneous opening area of the valve;
- parameter value Cross-sectional area at ports A and B;
- average density of the liquid;
- pressure difference in the valve .

Critical pressure drop, - pressure drop associated with the value of critical Reynolds number , set by the parameter Critical Reynolds number, the point of regime transition between laminar and turbulent flow. The block calculates the critical pressure drop as:

where is the dynamic viscosity of thermal liquid.

The pressure loss describes the pressure drop in the valve due to the reduced valve area and is calculated as:

Pressure recovery describes a positive change in valve pressure due to an increase in area. To disregard the pressure recovery, uncheck the box Pressure recovery. In this case the pressure loss .

The block calculates , using the opening parameterization and the valve opening dynamics.

Valve opening parameterization

If the parameter Opening parameterization is set to Linear, the valve area for normally open valves is:

where

- is the value of parameters Leakage area;
- the value of the parameters Maximum opening area.

This figure shows how the block controls the opening area of a normally open valve using linear parameterization.

pressure compensator valve il 1

The valve area for normally closed valves is as follows

This figure shows how the block controls the opening area of a normally closed valve using linear parameterization.

pressure compensator valve il 2

The normalised pressure is

When the valve is in the nearly open or nearly closed position in the linear parameterization, it is possible to maintain numerical stability in the simulation by adjusting the parameter Smoothing factor. If the parameter Smoothing factor is non-zero, the block smoothly maintains the control pressure between and .

If the parameter Opening parameterization is set to a value of Tabulated data, then and are the first and last values of the Opening area vector parameters, respectively. The block calculates the opening area as

where

- control pressure, pressure drop between ports X and Y;
;
- the value of the parameter Pressure differential vector;
- is the change in internal pressure that causes the valve to start closing when ;
- value of the Opening area vector parameters.

This figure shows how the block controls the opening area of a normally open valve using tabular parameterization.

pressure compensator valve il 3

This figure shows how the block controls the opening area of a normally closed valve using a table parameterization.

pressure compensator valve il 4

Opening dynamics

If the check box Opening dynamics is selected, a delay is introduced in the flow response to the modelled control pressure. The pressure becomes the dynamic control pressure . The instantaneous change in the dynamic control pressure is calculated from the Opening time constant :

By default, the check box Opening dynamics is unchecked. For linear parameterization, a non-zero value for the parameter Smoothing factor provides additional numerical stability when the hole is in the nearly closed or nearly open position.

The block calculates the steady-state dynamics according to the parameter Opening parameterization based on the control pressure value .

Energy conservation

The energy conservation equation for the valve is as follows:

where

- is the energy flow entering the valve through port A;
- is the energy flow entering the valve through port B.

Ports

Conserving

# A — thermal liquid port
thermal liquid

Details

Thermal liquid port, corresponding to the A side of the valve.

Program usage name

inlet

# B — thermal liquid port
thermal liquid

Details

Thermal liquid port, corresponding to the B side of the valve.

Program usage name

outlet

# X — thermal liquid pressure
thermal liquid

Details

The thermal liquid port associated with determining the pressure at the X point, .

Program usage name

port_x

# Y — thermal liquid pressure
thermal liquid

Details

Thermal liquid port associated with determining the pressure at the Y point, .

Program usage name

port_y

Parameters

# Valve specification — valve displacement
Normally open | Normally closed

Details

Normal operating condition of the pressure compensator valve. For the pressure reducing valve, select Normally open. For the pressure relief valve, select Normally closed.

Values	`Normally open` \| `Normally closed`
Default value	`Normally open`
Program usage name	`valve_specification`
Evaluatable	Yes

# Opening parameterization — opening parameterization
Linear | Tabulated data

Details

A method for parameterising the opening process of a valve.

Values	`Linear` \| `Tabulated data`
Default value	`Linear`
Program usage name	`opening_parameterization`
Evaluatable	Yes

# Set pressure differential — differential pressure at which the pressure compensation is activated
Pa | GPa | MPa | atm | bar | kPa | ksi | psi | uPa | kbar

Details

The differential pressure at which the pressure compensation is activated.

Units	`Pa` \| `GPa` \| `MPa` \| `atm` \| `bar` \| `kPa` \| `ksi` \| `psi` \| `uPa` \| `kbar`
Default value	`0.0 MPa`
Program usage name	`delta_p_set`
Evaluatable	Yes

# Pressure regulation range — operating pressure range of the valve
Pa | GPa | MPa | atm | bar | kPa | ksi | psi | uPa | kbar

Details

The operating pressure range of the valve. The pressure control range determines the difference between the parameters Set pressure differential and the maximum operating pressure of the valve.

Dependencies

To use this parameter, set the parameter Opening parameterization to . Linear.

Units	`Pa` \| `GPa` \| `MPa` \| `atm` \| `bar` \| `kPa` \| `ksi` \| `psi` \| `uPa` \| `kbar`
Default value	`0.1 MPa`
Program usage name	`p_regulation_range`
Evaluatable	Yes

# Maximum opening area — fully open valve area
m^2 | cm^2 | ft^2 | in^2 | km^2 | mi^2 | mm^2 | um^2 | yd^2

Details

Cross-sectional area of the valve bore in the fully open position.

Dependencies

To use this parameter, set the parameters Opening parameterization to . Linear.

Units	`m^2` \| `cm^2` \| `ft^2` \| `in^2` \| `km^2` \| `mi^2` \| `mm^2` \| `um^2` \| `yd^2`
Default value	`0.0001 m^2`
Program usage name	`max_valve_area`
Evaluatable	Yes

# Leakage area — valve clearance area in fully closed position
m^2 | cm^2 | ft^2 | in^2 | km^2 | mi^2 | mm^2 | um^2 | yd^2

Details

The sum of all clearances when the valve is in the fully closed position. Any area less than this value equates to the specified leakage area. This parameter contributes to the stability of the numerical solution by maintaining flow continuity.

Dependencies

To use this parameter, set the parameter Opening parameterization to the value of Linear.

Units	`m^2` \| `cm^2` \| `ft^2` \| `in^2` \| `km^2` \| `mi^2` \| `mm^2` \| `um^2` \| `yd^2`
Default value	`1e-10 m^2`
Program usage name	`leakage_area`
Evaluatable	Yes

# Cross-sectional area at ports A and B — area at the inlet or outlet of the valve
m^2 | cm^2 | ft^2 | in^2 | km^2 | mi^2 | mm^2 | um^2 | yd^2

Details

The cross-sectional area at the inlet and outlet ports A and B. This area is used when calculating the mass flow rate.

Units	`m^2` \| `cm^2` \| `ft^2` \| `in^2` \| `km^2` \| `mi^2` \| `mm^2` \| `um^2` \| `yd^2`
Default value	`0.01 m^2`
Program usage name	`port_area`
Evaluatable	Yes

# Discharge coefficient — flow coefficient

Details

Correction factor that takes into account the rarefaction losses in theoretical flows.

Default value	`0.64`
Program usage name	`C_d`
Evaluatable	Yes

# Critical Reynolds number — upper limit of Reynolds number for laminar flow

Details

Upper Reynolds number limit for laminar flow through the valve.

Default value	`150.0`
Program usage name	`Re_critical`
Evaluatable	Yes

# Smoothing factor — numerical smoothing factor

Details

Continuous smoothing factor that provides smooth opening by correcting the valve characteristic in the nearly open and nearly closed positions. Set a non-zero value less than one to increase the stability of the simulation in these modes.

Dependencies

To use this parameter, set the parameter Opening parameterization to . Linear.

Default value	`0.01`
Program usage name	`smoothing_factor`
Evaluatable	Yes

# Pressure recovery — whether to take into account the increase in pressure when expanding the area

Details

Whether to take into account the pressure increase when the fluid flows from a region with a smaller cross-sectional area to a region with a larger cross-sectional area.

Default value	`false (switched off)`
Program usage name	`pressure_recovery`
Evaluatable	Yes

# Opening dynamics — whether to take into account the flow response to valve opening

Details

Whether to account for transient effects in the fluid system caused by valve opening. Checking Opening dynamics approximates the opening conditions by introducing a first order lag in the flow response. The Opening time constant parameters also affect the modelled opening dynamics.

Default value	`false (switched off)`
Program usage name	`opening_dynamics`
Evaluatable	Yes

# Opening time constant — valve opening time constant
d | s | hr | ms | ns | us | min

Details

Time constant by which the delay in the opening dynamics is calculated.

Dependencies

To use this parameter, select the check box Opening dynamics.

Units	`d` \| `s` \| `hr` \| `ms` \| `ns` \| `us` \| `min`
Default value	`0.1 s`
Program usage name	`tau`
Evaluatable	Yes

# Pressure differential vector — differential pressure values of the pressure reducing valve for tabular parameterization
Pa | GPa | MPa | atm | bar | kPa | ksi | psi | uPa | kbar

Details

Vector of differential pressure values for tabular parameterization of the valve opening area. The elements of this vector must correspond to the elements of the vector from the Opening area vector parameters. The elements are listed in ascending order.

Dependencies

To use this parameter, set the parameters Valve specification to the value of Normally open`and set the Opening parameterization parameters to . `Tabulated data.

Units	`Pa` \| `GPa` \| `MPa` \| `atm` \| `bar` \| `kPa` \| `ksi` \| `psi` \| `uPa` \| `kbar`
Default value	`[0.2, 0.4, 0.6, 0.8, 1.0, 1.2] MPa`
Program usage name	`delta_p_reducing_vector`
Evaluatable	Yes

# Opening area vector — vector of values for the opening area of the pressure reducing valve for tabular parameterization
m^2 | cm^2 | ft^2 | in^2 | km^2 | mi^2 | mm^2 | um^2 | yd^2

Details

Vector of valve opening area values for tabular parameterization. The elements of this vector must correspond to the elements of the vector from the Pressure differential vector parameters. For normally open valves, the elements are listed in descending order. For normally closed valves, the elements are listed in ascending order.

The Opening area vector must have the same number of elements as the Pressure differential vector. The block uses linear interpolation between points in the data table.

Dependencies

To use this parameter, set the Valve specification parameters to and the parameters to . Normally open`and set the Opening parameterization parameters to . `Tabulated data.

Units	`m^2` \| `cm^2` \| `ft^2` \| `in^2` \| `km^2` \| `mi^2` \| `mm^2` \| `um^2` \| `yd^2`
Default value	`[1.0e-5, 8.0e-6, 6.0e-6, 4.0e-6, 2.0e-6, 1.0e-10] m^2`
Program usage name	`valve_area_reducing_vector`
Evaluatable	Yes

# Pressure differential vector — differential pressure values of the pressure relief valve for tabular parameterization
Pa | GPa | MPa | atm | bar | kPa | ksi | psi | uPa | kbar

Details

Dependencies

To use this parameter, set the parameters Valve specification to the value of Normally closed`and set the Opening parameterization parameters to . `Tabulated data.

Units	`Pa` \| `GPa` \| `MPa` \| `atm` \| `bar` \| `kPa` \| `ksi` \| `psi` \| `uPa` \| `kbar`
Default value	`[0.2, 0.4, 0.6, 0.8, 1.0, 1.2] MPa`
Program usage name	`delta_p_relief_vector`
Evaluatable	Yes

# Opening area vector — vector of pressure relief valve opening area values for tabular parameterization
m^2 | cm^2 | ft^2 | in^2 | km^2 | mi^2 | mm^2 | um^2 | yd^2

Details

Vector of the valve opening area for tabular parameterization. The elements of this vector must correspond to the elements of the vector from the Pressure differential vector parameters. For normally open valves, the elements are listed in descending order. For normally closed valves, the elements are listed in ascending order.

The Opening area vector must have the same number of elements as the Pressure differential vector. The block uses linear interpolation between points in the data table.

Dependencies

To use this parameter, set the Valve specification parameters to and the parameters to . Normally closed`and set the Opening parameterization parameters to . `Tabulated data.

Units	`m^2` \| `cm^2` \| `ft^2` \| `in^2` \| `km^2` \| `mi^2` \| `mm^2` \| `um^2` \| `yd^2`
Default value	`[1.0e-10, 2.0e-6, 4.0e-6, 6.0e-6, 8.0e-6, 1.0e-5] m^2`
Program usage name	`valve_area_relief_vector`
Evaluatable	Yes