Valve¶

Two-way valve: sets the flow of its branch to ym_flow_nominal (set flows), or opens to y as Buildings.Fluid.Actuators.Valves.TwoWayEqualPercentage, linearized (pressure-driven flows)*

FastSmoothBuildings.Hydronics.Valve, model (source)

Extends PartialConserving.

Purpose

Two-way valve of a branch, for instance the thermostatic valve of a radiator. The water passes at the inlet temperature, TOut = TIn.

Set flows and pressure-driven flows

With set flows, the valve sets the flow of its branch: ṁ = y m_flow_nominal, the input y being the flow relative to the nominal flow.

With pressure-driven flows, y is the opening. Limited to [0, 1] by smoothLimit (blends of 10⁻³), it gives the equal-percentage characteristic φ = equalPercentage(y, R, l, delta0): R^{y − 1} above 1.5 delta0, linear from the leakage l at y = 0 below delta0/2, a cubic between. The conductance of the valve and of the pipes in series (valveConductance) is

G = m_flow_nominal / (dpFixed_nominal + dpValve_nominal / φ²),

and each of the n_b outlets passes port_b[j].m_flow = −G (p_in − p_b,j) / n_b: the flow is linear in the pressure drop at a given opening. The compliance of the inlet node is scaled by the conductance of the open valve and its pipes, GNom.

Relation to Buildings

Buildings.Fluid.Actuators.Valves.TwoWayEqualPercentage with its flow law linearized (linearized = true), the fixed resistance dpFixed_nominal in series.

Parameters¶

Parameter	Type	Unit	Default	Description
m_flow_nominal	Real	kg/s		Nominal flow
dpValve_nominal	Real	Pa	1e4	Pressure drop of the open valve at the nominal flow
dpFixed_nominal	Real	Pa	0	Pressure drop of the pipes in series at the nominal flow
R	Real		50	Rangeability
l	Real		1e-4	Leakage
delta0	Real		0.01	Linear range of the characteristic near closure
GNom	Real	kg/(s.Pa)	m_flow_nominal/(dpValve_nominal + dpFixed_nominal)	Conductance of the open valve and its pipes

Revisions¶

October 2026: moved from trano's FastModel.Hydronics.