Flow Control

Physical Model

The flow control component enforces a specific mass flow between two junctions. This is very helpful to control the mass flow in district heating networks.

Warning

It is recommended to use the flow control components only in looped networks. Using the flow controller in non-looped networks, in particular on stubs, can likely lead to non-convergence of the pipeflow.

Create Function

For creating a single flow control unit:

create_flow_control(net, from_junction, to_junction, controlled_mdot_kg_per_s, control_active=True, name=None, index=None, in_service=True, type='fc', **kwargs)

Adds one flow control with a constant mass flow in table net[“flow_control”].

Parameters:

• net (pandapipesNet) – The net for which this flow control should be created

• from_junction (int) – ID of the junction on one side which the flow control will be connected with

• to_junction (int) – ID of the junction on the other side which the flow control will be connected with

• controlled_mdot_kg_per_s (float) – Mass flow set point

• control_active (bool, default True) – Variable to state whether the flow control is active (otherwise similar to open valve)

• name (str) – Name of the flow control element

• index (int, default None) – Force a specified ID if it is available. If None, the index one higher than the highest already existing index is selected.

• in_service (bool, default True) – True if flow controller is in service or False if it is out of service

• type (str, default "fc") – Currently not used - possibility to specify a certain type of flow control

• kwargs – Additional keyword arguments will be added as further columns to the net[“flow_control”] table

Returns:

index - The unique ID of the created elements

Return type:

int

Example:

>>> create_flow_control(net, 0, 1, 0.5, 0.8)

For creating multiple flow control units at once:

create_flow_controls(net, from_junctions, to_junctions, controlled_mdot_kg_per_s, control_active=True, name=None, index=None, in_service=True, type='fc', **kwargs)

Convenience function for creating many flow controls at once. Parameters ‘from_junctions’ and ‘to_junctions’ must be arrays of equal length. Other parameters may be either arrays of the same length or single values.

Parameters:

• net (pandapipesNet) – The net for which these flow controls should be created

• from_junctions (Iterable(int)) – IDs of the junctions on one side which the flow controls will be connected to

• to_junctions (Iterable(int)) – IDs of the junctions on the other side to which the pressure controls will be connected to

• controlled_mdot_kg_per_s (Iterable or float) – Mass flow set points

• control_active (bool, default True) – Variable to state whether the flow control is active (otherwise similar to open valve)

• name (Iterable or str) – Name of the flow control elements

• index (Iterable(int), default None) – Force specified IDs if they are available. If None, the index one higher than the highest already existing index is selected and counted onwards.

• in_service (Iterable or bool, default True) – True if the flow controls are in service or False if they are out of service

• type (Iterable or str, default "fc") – Currently not used - possibility to specify a certain type of flow control

• kwargs – Additional keyword arguments will be added as further columns to the net[“flow_control”] table

Returns:

index - The unique IDs of the created elements

Return type:

array(int)

Example:

Create two flow controllers between junction 0 and 1 with 0.5 kg/s and junction 2 and 4 with 0.9 kg/s, respectively.

>>> create_flow_controls(net, [0, 2], [1, 4], [0.5, 0.9])

Component Table Data

net.flow_control

Parameter	Datatype	Value Range	Explanation
net	pandapipesNet		The pandapipes net object in whose flow_control table the new unit will be added
from_junction	integer	\(>\) 0	Index of junction at which the flow control unit starts
to_junction	integer	\(>\) 0	Index of junction at which the flow control unit ends
controlled_mdot_kg_per_s	float		The mass flow set point [kg/s]
diameter	float	> 0	diameter to derive the cross-sectional area
control_active	boolean		If false, the unit behaves like an open valve
name	string		Name of the flow control unit
in_service	boolean	True / False	If false, the unit behaves like a closed valve.
type	string		Type variable to classify different kinds of flow control units (not considered by pandapipes’ calculations)

Result Table Data

net.res_flow_control

Parameter	Datatype	Explanation
v_mean_m_per_s	float	The mean velocity of fluid in the flow control unit [m/s]
p_from_bar	float	Pressure at “from”-junction [bar]
p_to_bar	float	Pressure at “to”-junction [bar]
t_from_k	float	Temperature at “from”-junction [K]
t_to_k	float	Temperature at “to”-junction [K]
mdot_from_kg_per_s	float	Mass flow into flow control unit [kg/s]
mdot_to_kg_per_s	float	Mass flow out of flow control unit [kg/s]
vdot_norm_m3_per_s	float	Norm volume flow [m^3/s]
reynolds	float	Average Reynolds number