Pump¶
Pump: pass-through with set flows; with pressure-driven flows, the flow at its head from the curve of Buildings.Fluid.Movers.Preconfigured.SpeedControlled_y (1.14, 1 and 0.42 times dp_nominal at 0, 1 and 2 times the nominal flow), scaled to the speed y by the affinity laws
FastSmoothBuildings.Hydronics.Pump, model (source)
Extends PartialConserving.
Purpose
Circulation pump. With set flows the circuit flows are set by the valves and the pump only passes the water
through and computes its power; with pressure-driven flows it delivers the flow of its curve at the head the
circuit puts on it, at the relative speed y.
Equations
The water passes at the inlet temperature, TOut = TIn. The head is
dp = p̄b − pin, p̄b the mean
pressure of the nodes downstream (0 with set flows).
Set flows and pressure-driven flows
With set flows, what enters leaves, and the electrical power is taken at the nominal head:
P = dp_nominal ṁ / (ρ η), η =
eta. The input y is not used.
With pressure-driven flows, the head of the pump relative to Δp0 = dp_nominal
follows a parabola in the flow relative to the nominal flow, x, through the points (0, 1.14), (1, 1) and
(2, 0.42):
h(x) = a + b x + c x2, a = 1.14, b = 0.08, c = −0.22,
scaled to the speed y by the affinity laws (flow as y, head as y2). For each of the nb outlets, the flow is the root of the parabola at the head of that outlet:
xj = (−b − √positivePart(b2 − 4 c (a − hj), 10−3)) / (2 c), hj = (pb,j − pin) / (Δp0 (y2 + 10−4)),
port_b[j].m_flow = −y m_flow_nominal xj /
nb.
Beyond the shut-off head the argument of the root would be negative: positivePart keeps it positive and the flow
stays at the top of the curve. The 10−4 keeps the relative head defined at y = 0. The
power counts the forward head and flow only, P = positivePart(dp, 1) mTra /
(ρ η), so the pump draws no negative power while the pressures settle. The compliance of the
inlet node is scaled by m_flow_nominal/dp_nominal.
Relation to Buildings
The curve is that of Buildings.Fluid.Movers.Preconfigured.SpeedControlled_y: 1.14, 1 and 0.42 times
dp_nominal at 0, 1 and 2 times the nominal flow. The electrical power is not added to the water
(TOut = TIn).
Use
In Examples.BoilerCircuit, the speed follows the opening of the radiator valve through Controls.CollectorControl.
Parameters¶
| Parameter | Type | Unit | Default | Description |
|---|---|---|---|---|
| dp_nominal | Real | Pa | 3e4 | Pressure head at the nominal flow |
| m_flow_nominal | Real | kg/s | 1 | Nominal flow |
| eta | Real | 0.5 | Overall efficiency |
Revisions¶
- October 2026: moved from trano's
FastModel.Hydronics.