Check valve (TL)#

The Check valve (TL) block is a model of a check valve with free flow from the inlet port to the outlet port and limited in the opposite direction.

The Opening pressure specification property allows the user to select pressure control points:

when the DifPressure value is selected, the valve controls the pressure difference between the ports of the block;
when selecting the value Pressure at port A - the pressure value in the inlet port.

When the valve operates in the differential pressure control mode between ports, the valve begins to open and fully opens when the differential pressure thresholds set by the user between ports are exceeded – the corresponding values are configured through the block properties:

Cracking pressure drop;
Full open pressure drop.

Similarly, when the valve operates in the pressure control mode in port A, the user sets the properties:

Cracking pressure at port;
Full open pressure at port.

The check valve supports 3 types of parameterization of its flow characteristics:

The open area of the valve depends linearly on the magnitude of the actual differential pressure (or pressure in port A - depending on the settings) as shown below;
The open area of the valve is specified in a table and is dependent on the actual pressure difference between the ports (or the pressure in port A), while intermediate values are calculated using interpolation;
The volumetric flow rate of liquid through the valve is specified in a table and is dependent on the actual pressure difference between the ports (pressure in port A), while intermediate values are calculated using interpolation.

Opening area and pressure (for linear parameterization of area)

Linear dependence of valve opening area (1) :

(1)#\[ A_{valve}=p^\wedge \cdot(A_{max}-A_{leak})+A_{leak}\]

where normalized pressure (2):

(2)#\[ p^\wedge =\frac{p_{control}-p_{cracking}}{p_{max}-p_{cracking}}\]

where:

\(A_{max}\) - is the cross-section area of the valve in the fully open position, [m\(^2\)];

\(A_{leak}\) - leakage area in fully closed valve position, [m\(^2\)].

Equation for mass flow rate

Law of conservation of mass (3):

(3)#\[ \dot m_{А}+\dot m_{B}=0\]

Mass flow rate through valve (4):

(4)#\[\dot m = \frac{C_{d}\cdot A_{valve}\cdot \sqrt{2\cdot \bar\rho}}{\sqrt{PR_{loss}\cdot (1-(\frac{А_{valve}}{А_{port}})^2)}}\cdot \frac{\Delta p}{(\Delta p^2+ \Delta p_{crit}^2)^{1/4}}\]

where:

\(C_{d}\) - loss coefficient at pressure recovery;

\(A_{valve}\) - cross-section area of the valve, [m\(^2\)];

\(А_{port}\) - cross-section area of flow, [m\(^2\)];

\(\bar ho\) – average density of liquid, [kg/m\(^3\)];

\(\Delta p\) – pressure drop across the valve, [Pa].

Critical pressure drop \(\Delta p_{crit}\) is the pressure drop associated with the critical Reynolds number, the point of transition of the flow mode from laminar to turbulent (5):

(5)#\[ \Delta p_{crit}=\frac{\pi \cdot \bar\rho}{8 \cdot A_{valve}} \cdot (\frac {\nu \cdot Re_{crit}}{C_{d}} )^2\]

Pressure decrease describes the pressure decrease in the valve when the valve cross-section area is decreased.

\(PR_{loss}\) is calculated using the following formula (6):

(6)#\[ PR_{loss}=\frac {\sqrt {1-(\frac {A_{valve}}{A_{port}})^2 \cdot (1-C_{d}^2)}-C_{d} \cdot \frac {A_{valve}}{A_{port}}}{\sqrt {1-(\frac {A_{valve}}{A_{port}})^2 \cdot (1-C_{d}^2)}+C_{d} \cdot \frac {A_{valve}}{A_{port}}}\]

Pressure recovery describes a positive pressure change in the valve when the area increases.

Law of conservation of energy (7):

(7)#\[\phi_A+\phi_B=0\]

1. Properties#

Property	Default value	Description	Units of measurement
Opening parametrization: Linear; Tab (areaVSpd); Tab (flowVSpd)	Linear	-	-
Opening pressure specification: DifPressure; Pressure at port A, available when `Opening parametrization` - `Linear`	По перепаду давлений	-	-
Cracking pressure drop, available when `Opening parametrization` - `Linear`, `Opening pressure specification` - `DifPressure`	10000.0	-	Pa
Full open pressure drop, available when `Opening parametrization` - `Linear`, `Opening pressure specification` - `DifPressure`	20000.0	-	Pa
Cracking pressure at port, available when `Opening parametrization` - `Linear`, `Opening pressure specification` - `Pressure at port A`	100000.0	-	Pa
Full open pressure at port, available when `Opening parametrization` - `Linear`, `Opening pressure specification` - `Pressure at port A`	200000.0	-	Pa
Maximum valve cross area, , available when `Opening parametrization` - `Linear`	1.0E-4	-	m\(^2\)
Port cross area, available when `Opening parametrization` - `Linear`	1.0E-10	-	m\(^2\)
Port cross area, available when `Opening parametrization` - `Linear`	0.1	-	m\(^2\)
Discharge coefficient	0.64	-	-
Critical Reynolds number	150.0	The Reynolds number at which the transition from a laminar flow regime to a turbulent one occurs	-
Pressure drop vector, available when `Opening parametrization` - `Tab (areaVSpd)`, `Tab (flowVSpd)`	10000.0; 20000.0; 30000.0; 40000.0; 50000.0; 60000.0; 70000.0; 80000.0; 90000.0; 100000.0	-	Pa
Area vector, available when `Opening parametrization` - `Tab (areaVSpd)`	1.0E-10; 1.0E-5; 2.0E-5; 3.0E-5; 4.0E-5; 5.0E-5; 6.0E-5; 7.5E-5; 8.5E-5; 1.0E-4	-	m\(^2\)
Mass flow vector, available when `Opening parametrization` - `Tab (flowVSpd)`	3.58E-4; 0.045; 0.11; 0.191; 0.284; 0.39; 0.505; 0.63; 0.764; 0.905	-	kg/s

2. Inputs and outputs#

Parameters	Input/Output	Description	Units of measurement	Port type
Input	Input	-	-	Thermohydraulics
Output	Output	-	-	Thermohydraulics

In order to see the connection capabilities of the block, you need to go to page Description of block ports