Temperature Control Valve (G)

The temperature control valve in the gas network.

blockType: EngeeFluids.Gas.Valves.FlowControl.Temperature

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Description

Block Temperature Control Valve (G) It is an opening with a thermostat as a flow control mechanism. The thermostat contains a temperature sensor and an opening mechanism. The sensor is located at the input and reacts to temperature changes with a small delay, fixed by a first-order time delay.

When the sensor detects a temperature exceeding the set actuation value, the opening mechanism is triggered and the valve begins to open or close, depending on the operating mode set by the parameter. Valve operation. The change in the opening area continues to the limit of the valve’s temperature range, beyond which the opening area becomes constant. Within the temperature range, the opening area is a linear function of temperature.

The flow can be laminar or turbulent and can reach sonic velocities. The maximum velocity occurs in the valve seat, where the flow is narrowest and fastest. The flow reaches a critical mode and maximum speed when the pressure drop downstream can no longer increase the speed. The flow is blocked when the pressure drop reaches a critical value characteristic of the valve. The unit does not calculate supersonic flow.

Temperature control

The inlet temperature readings are a control signal for the valve. The more the temperature reading exceeds the operating temperature, the more the opening area deviates from the area when the valve is maximally closed, if for the parameter Valve operation the value is set Opens above activation temperature, or from the area with the valve fully open, if for Valve operation the value is set Closes above activation temperature.

The difference between the temperature sensor readings and the trigger temperature is the temperature release. The unit normalizes this variable to the temperature control range of the valve. The degree of valve opening is

where

— parameter value Activation temperature;
— temperature sensor readings:
- If for the parameter Temperature sensing the value is set Valve inlet temperature Then — this is the temperature at the valve inlet;
- If for the parameter Temperature sensing the value is set Gas sensing port Then — this is the temperature of the gas network at the point of its connection to the port T;
- If for the parameter Temperature sensing the value is set Thermal sensing port Then — this is the temperature of the heating network at the point of its connection to the port T;
— parameter value Temperature regulation range.

calculated smoothing

When the parameter Smoothing factor has a non-zero value, the block applies numerical smoothing to the degree of valve opening. . Enabling anti-aliasing helps maintain the numerical stability of the simulation.

dynamic characteristics of sensors

To emulate a real temperature sensor that can detect temperature changes only gradually, the unit adds a first-order time delay to the temperature readings. . This time delay adds a transient response to temperature changes to the sensor. The expression for it has the form

where

— the actual inlet temperature at the current time step of the simulation;
— parameter value Sensor time constant. The lower this parameter, the faster the sensor reacts.

Parameterization of the valve

The behavior of the block depends on the parameter Valve parameterization:

Cv flow coefficient — expense ratio determines the dependence of throughput on pressure drop;
Kv flow coefficient — expense ratio determines the dependence of throughput on pressure drop, ;
Sonic conductance — steady-state acoustic conductivity determines the throughput at critical flow, a condition in which the flow velocity is equal to the local speed of sound. The flow becomes critical when the ratio of outlet pressure to inlet pressure reaches a value called the critical pressure ratio.;
Orifice area — the area of the hole determines the throughput.

The unit scales the set flow rate according to the degree of valve opening. When increasing the degree of valve opening from 0 before 1 The throughput indicator increases from a set minimum to a set maximum.

Conservation of momentum

Parameter Valve parameterization determines which equations will be used to calculate the flow rate. If for the parameter Valve parameterization the value is set Cv flow coefficient, then the mass consumption will be defined as

where

— expense ratio;
— a constant equal to 27.3 for mass flow rate in kg/hour, pressure in bar and density in kg/m3³;
— expansion coefficient;
— inlet pressure;
— outlet pressure;
— density at the entrance.

The expansion coefficient is defined as

where

— the ratio of the adiabatic index to 1.4;
— parameter value xT pressure differential ratio factor at choked flow.

When is the pressure ratio exceeds the value of the parameter Laminar flow pressure ratio, , there is a smooth transition to using the linearized equation:

where

When is the pressure ratio falls lower , the flow becomes critical, and the equation is used

If for the parameter Valve parameterization the value is set Kv flow coefficient, then the block uses the same equations, but replaces on using a relationship . More detailed information about the mass flow equations when for the parameter Valve parameterization the value is set Kv flow coefficient or Cv flow coefficient, is given in [2] and [3].

If for the parameter Valve parameterization the value is set Sonic conductance, then the mass flow rate defined as

where

— acoustic conductivity;
— critical pressure ratio;
— parameter value Subsonic index;
— parameter value ISO reference temperature;
— parameter value ISO reference density;
— temperature at the entrance.

When is the pressure ratio exceeds the value of the parameter Laminar flow pressure ratio, , there is a smooth transition to using the linearized equation:

When is the pressure ratio falls below the critical pressure ratio , the flow becomes critical, and the equation is used

More detailed information about the mass flow equations when for the parameter Valve parameterization the value is set Sonic conductance, is given in [1].

If for the parameter Valve parameterization the value is set Orifice area, then the mass consumption defined as

where

— the area of the hole or valve;
— parameter value Cross-sectional area at ports A and B;
— parameter value Discharge coefficient;
— the adiabatic index.

When is the pressure ratio exceeds the value of the parameter Laminar flow pressure ratio, , there is a smooth transition to using the linearized equation:

When is the pressure ratio falls lower , the flow becomes critical, and the equation is used

More detailed information about the mass flow equations when for the parameter Valve parameterization the value is set Orifice area, is given in [4].

Conservation of mass

It is assumed that the volume and mass of gas inside the valve are very small, and these values are not taken into account, so gas cannot accumulate in the valve. According to the principle of conservation of mass, the mass flow rate of gas entering through one port is equal to the flow rate of gas exiting through another port:

where and — the mass flow rate at ports A and B respectively.

Energy conservation

The valve is an adiabatic component. There is no heat exchange between the gas and the valve wall. When the gas passes through the valve, no work is performed on it. Under these assumptions, energy can enter and exit the valve only through convection through ports A and B. According to the principle of energy conservation, the sum of energy flows through ports is always zero:

where and — the flow of energy entering the valve through ports A and B, respectively.

Assumptions and limitations

Meaning Sonic conductance the parameter Valve parameterization designed for pneumatic systems. If this parameter is used for gases other than air, it may be necessary to adjust the acoustic conductivity value by the square root of the relative density.
The equation for parameterization Orifice area it has lower accuracy for gases that are far from ideal.
This block does not simulate supersonic flow.

Ports

Conserving

# A — valve inlet
gas

Details

The gas port connected to the valve inlet.

Program usage name

port_a

# B — valve outlet
gas

Details

The gas port connected to the valve outlet.

Program usage name

port_b

# T — gas network temperature sensor
gas

Details

A non-directional gas port connected to a temperature sensor. There is no mass or energy flow through this port. The T port determines the temperature in the gas network.

Dependencies

To use this port, set the parameter Temperature sensing meaning Gas sensing port.

Program usage name

gas_sensing_port

# T — thermal network temperature sensor
warm

Details

A non-directional heat port connected to a temperature sensor. There is no mass or energy flow through this port. The T port determines the temperature in the heating network.

Dependencies

To use this port, set the parameter Temperature sensing meaning Thermal sensing port.

Program usage name

thermal_sensing_port

Parameters

# Valve operation — The sign of the opening square change
Opens above activation temperature | Closes above activation temperature

Details

A sign of a change in the opening area caused by an increase in temperature. The opening area may increase or decrease as the temperature increases. The change begins at the operating temperature and continues when heated over the entire temperature range of the valve control.

Default value Opens above activation temperature corresponds to a normally closed valve that opens when the temperature rises. The second value Closes above activation temperature corresponds to a normally open valve that closes at the same temperature.

Values	`Opens above activation temperature` \| `Closes above activation temperature`
Default value	`Opens above activation temperature`
Program usage name	`operation`
Evaluatable	No

# Temperature sensing — the method of measuring the temperature controlling the valve
Valve inlet temperature | Gas sensing port | Thermal sensing port

Details

The method used by the unit to measure the temperature controlling the valve:

Valve inlet temperature — The inlet temperature is used to control the valve.
Gas sensing port — The temperature on the gas sensor T is used to control the valve. Connect this port to any part of the gas network to use this temperature to control the valve. The T port is used only as a sensor, no gas flow passes through it.
Thermal sensing port — The temperature on the heat sensor T is used to control the valve. Connect this port to any part of the heating network to use this temperature to control the valve. The T port is used only as a sensor and has no heat exchange with the environment.

Values	`Valve inlet temperature` \| `Gas sensing port` \| `Thermal sensing port`
Default value	`Valve inlet temperature`
Program usage name	`temperature_sensing_port_type`
Evaluatable	No

Details

The temperature at which the opening mechanism is triggered. When heated above this temperature, the valve either opens or closes, depending on the parameter value. Valve operation. The opening area varies over the entire temperature control range of the valve.

Units	`K` \| `degC` \| `degF` \| `degR` \| `deltaK` \| `deltadegC` \| `deltadegF` \| `deltadegR`
Default value	`330.0 K`
Program usage name	`T_activation`
Evaluatable	Yes

Details

The temperature control range in which the valve opening area varies depending on the temperature.

The interval in which the valve area changes begins with the valve’s operating temperature Activation temperature and ends with the sum of the trigger temperature Activation temperature and the range of regulation Temperature regulation range.

Units	`K` \| `degC` \| `degF` \| `degR` \| `deltaK` \| `deltadegC` \| `deltadegF` \| `deltadegR`
Default value	`8.0 deltaK`
Program usage name	`T_range`
Evaluatable	Yes

# Sensor time constant — time for recording temperature changes on the input sensor
s | ns | us | ms | min | hr | d

Details

The typical time for recording temperature changes on the input sensor. This parameter defines the delay between the start of the change and its stable measurement, which is carried out as the sensor approaches a new stable state. Meaning 0 This means that the sensor responds instantly to temperature changes.

Units	`s` \| `ns` \| `us` \| `ms` \| `min` \| `hr` \| `d`
Default value	`1.5 s`
Program usage name	`tau`
Evaluatable	Yes

# Valve parameterization — the method of defining the characteristics of the flow through the hole
Cv flow coefficient | Kv flow coefficient | Sonic conductance | Orifice area

Details

The method of calculating the mass flow rate is based on:

Cv flow coefficient — the expense ratio ;
Kv flow coefficient — the expense ratio , which is defined as ;
Sonic conductance — acoustic conductivity in steady state;
Orifice area — the area of the hole.

Values	`Cv flow coefficient` \| `Kv flow coefficient` \| `Sonic conductance` \| `Orifice area`
Default value	`Cv flow coefficient`
Program usage name	`valve_parameterization`
Evaluatable	No

# Maximum Cv flow coefficient — the flow rate corresponding to the maximum opening area

Details

The value of the flow coefficient , when the cross-sectional area of the hole is maximal. The flow coefficient determines the dependence of the throughput on the pressure drop.

Dependencies

To use this parameter, set for the parameter Valve parameterization meaning Cv flow coefficient.

Default value	`4.0`
Program usage name	`C_v_max`
Evaluatable	Yes

# xT pressure differential ratio factor at choked flow — critical pressure drop ratio

Details

The ratio between inlet pressure and the outlet pressure , defined as at which point the flow becomes critical. If this value is not known, then you can find it in Table 2 in ISA-75.01.01. [3]. Default value 0.7 suitable for many valves.

Dependencies

To use this parameter, set for the parameter Valve parameterization meaning Cv flow coefficient.

Default value	`0.7`
Program usage name	`delta_p_ratio_C_v`
Evaluatable	Yes

# Leakage flow fraction — cost ratio

Details

The ratio of flow through a closed and through an open hole.

Default value	`1.0e-6`
Program usage name	`leakage_fraction`
Evaluatable	Yes

# Smoothing factor — numerical smoothing factor

Details

The continuous smoothing coefficient, which ensures smooth opening by correcting the characteristic of the hole in the almost open and almost closed positions.

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

# Laminar flow pressure ratio — the pressure ratio at which the flow transitions between laminar and turbulent modes

Details

The ratio of outlet pressure to inlet pressure at which the flow transitions between laminar and turbulent flow modes.

Typical values range from 0.995 before 0.999.

Default value	`0.999`
Program usage name	`B_laminar`
Evaluatable	Yes

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

Details

This area is used when calculating the mass flow through ports.

The ports have the same size. The value of this parameter must correspond to the area of the inlet of the component to which the unit is connected.

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

# Maximum Kv flow coefficient — the flow rate corresponding to the maximum opening area

Details

The value of the flow coefficient , when the cross-sectional area of the hole is maximal. The flow coefficient determines the dependence of the throughput on the pressure drop.

Dependencies

To use this parameter, set for the parameter Valve parameterization meaning Kv flow coefficient.

Default value	`3.6`
Program usage name	`K_v_max`
Evaluatable	Yes

# xT pressure differential ratio factor at choked flow — critical pressure drop ratio

Details

The ratio between inlet pressure and the outlet pressure , defined as at which point the flow becomes critical. If this value is not known, it can be found in table 2 in ISA-75.01.01 [3]. Default value 0.7 suitable for many valves.

Dependencies

To use this parameter, set for the parameter Valve parameterization meaning Kv flow coefficient.

Default value	`0.7`
Program usage name	`delta_p_ratio_K_v`
Evaluatable	Yes

# Maximum sonic conductance — acoustic conductivity corresponding to the maximum hole area
l/(bar*s) | gal/(min*psi) | m^3/(Pa*s)

Details

The value of acoustic conductivity, when the cross-sectional area of the hole is maximum.

Dependencies

To use this parameter, set for the parameter Valve parameterization meaning Sonic conductance.

Units	`l/(bars)` \| `gal/(minpsi)` \| `m^3/(Pa*s)`
Default value	`12.0 l/(bar*s)`
Program usage name	`C_max`
Evaluatable	Yes

# Critical pressure ratio — critical pressure ratio

Details

The pressure ratio at which the flow becomes critical and the flow velocity reaches a maximum determined by the local speed of sound. The ratio between the outlet pressure and inlet pressure : .

Dependencies

To use this parameter, set for the parameter Valve parameterization meaning Sonic conductance.

Default value	`0.3`
Program usage name	`B_critical_linear`
Evaluatable	Yes

# Subsonic index — the value of the degree used to calculate the mass flow rate in subsonic flow mode

Details

An empirical value used for more accurate calculation of mass flow rate in subsonic flow mode.

Dependencies

To use this parameter, set for the parameter Valve parameterization meaning Sonic conductance.

Default value	`0.5`
Program usage name	`m`
Evaluatable	Yes

Details

The temperature in the standard reference atmosphere in the ISO 8778 standard.

The ISO reference parameter values need to be adjusted only if acoustic conductivity values obtained with excellent reference values are used.

Dependencies

To use this parameter, set for the parameter Valve parameterization meaning Sonic conductance.

Units	`K` \| `degC` \| `degF` \| `degR` \| `deltaK` \| `deltadegC` \| `deltadegF` \| `deltadegR`
Default value	`293.15 K`
Program usage name	`T_reference`
Evaluatable	Yes

# ISO reference density — reference density according to ISO 8778
kg/m^3 | g/m^3 | g/cm^3 | g/mm^3 | lbm/ft^3 | lbm/gal | lbm/in^3

Details

The density in the standard reference atmosphere in the ISO 8778 standard.

The ISO reference parameter values need to be adjusted only if acoustic conductivity values obtained with excellent reference values are used.

Dependencies

To use this parameter, set for the parameter Valve parameterization meaning Sonic conductance.

Units	`kg/m^3` \| `g/m^3` \| `g/cm^3` \| `g/mm^3` \| `lbm/ft^3` \| `lbm/gal` \| `lbm/in^3`
Default value	`1.185 kg/m^3`
Program usage name	`rho_reference`
Evaluatable	Yes

# Maximum orifice area — the area of the flow passage section corresponding to the maximum opening area
m^2 | um^2 | mm^2 | cm^2 | km^2 | in^2 | ft^2 | yd^2 | mi^2 | ha | ac

Details

The maximum cross-sectional area of the flow is when the cross-sectional area of the opening is maximum.

Dependencies

To use this parameter, set for the parameter Valve parameterization meaning Orifice area.

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

# Discharge coefficient — expense ratio

Details

The correction factor is the ratio of the actual mass flow to the theoretical mass flow.

Dependencies

To use this parameter, set for the parameter Valve parameterization meaning Orifice area.

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

Literature

ISO 6358-3. «Pneumatic fluid power — Determination of flow-rate characteristics of components using compressible fluids — Part 3: Method for calculating steady-state flow rate characteristics of systems». 2014.
IEC 60534-2-3. «Industrial-process control valves — Part 2-3: Flow capacity — Test procedures». 2015.
ANSI/ISA-75.01.01. «Industrial-Process Control Valves — Part 2-1: Flow capacity — Sizing equations for fluid flow underinstalled conditions». 2012.
P. Beater. «Pneumatic Drives.» Springer-Verlag Berlin Heidelberg. 2007.