radiatorConductance

UAEle of Buildings RadiatorEN442_2: the conductance of each element giving the nominal power (bisections)

FastSmoothBuildings.Hydronics.radiatorConductance, function (source)

Purpose

Conductance UAEle of each element of a Radiator such that the radiator gives Q_flow_nominal at its nominal temperatures and flow.

Algorithm

The nominal flow is ṁ = Q_flow_nominal / (c_p (T_a_nominal − T_b_nominal)). Starting from the conductance of a single element at the mean water temperature,

UA₀ = Q_flow_nominal / (((T_a_nominal + T_b_nominal)/2 − ((1 − f) TAir_nominal + f TRad_nominal))ⁿ nEle),

80 bisections on [UA₀/10, 10 UA₀] find the conductance at which the nEle elements in series give Q_flow_nominal. For a given conductance, the water of each element is at the temperature T_w it leaves with, solved by 80 bisections between min(TAir_nominal, TRad_nominal) and the temperature of the water entering it:

T_w = T_up − Q_ele(T_w) / (ṁ c_p),   Q_ele = UA (f max(T_w − TRad_nominal, 0)ⁿ + (1 − f) max(T_w − TAir_nominal, 0)ⁿ),

with f = fraRad, and the water leaving one element enters the next.

Relation to Buildings

The parameter UAEle of Buildings.Fluid.HeatExchangers.Radiators.RadiatorEN442_2.

Use

Called in the binding of the parameter UAEle of Radiator. It depends on parameters only, so its branches and its max cause no event in the model.

Revisions

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