Model of a discretized coil with water vapor condensation.
The coil consists of two flow paths which are, at the design flow direction,
in opposite direction to model a counterflow heat exchanger.
The flow paths are discretized into nEle
elements.
Each element is modeled by an instance of
Buildings.Fluid.HeatExchangers.BaseClasses.HexElementLatent.
Each element has a state variable for the metal.
The convective heat transfer coefficients can, for each fluid individually, be computed as a function of the flow rate and/or the temperature, or assigned to a constant. This computation is done using an instance of Buildings.Fluid.HeatExchangers.BaseClasses.HADryCoil.
In this model, the water (or liquid) flow path
needs to be connected to port_a1
and port_b1
, and
the air flow path needs to be connected to the other two ports.
The mass transfer from the fluid 2 to the metal is computed using a similarity law between heat and mass transfer, as implemented by the model Buildings.Fluid.HeatExchangers.BaseClasses.MassExchange.
This model can only be used with medium models that
implement the function enthalpyOfLiquid
and that contain
an integer variable Water
whose value is the element number where
the water vapor is stored in the species concentration vector. Examples for
such media are
Buildings.Media.Air and
Modelica.Media.Air.MoistAir.
To model this coil for conditions without humidity condensation, use the model Buildings.Fluid.HeatExchangers.DryCoilCounterFlow instead of this model.
mas.T
in
Buildings.Fluid.HeatExchangers.BaseClasses.HexElementLatent.mas.T
in
Buildings.Fluid.HeatExchangers.BaseClasses.HexElementLatent
to correct latent heat exchange calculation.final
declaration in redeclaration.simplify_mWat_flow
.QLat_flow
to be consistent with
how it is computed in
Buildings.Fluid.HeatExchangers.BaseClasses.HexElementLatent.each
keyword.
Medium2
to be Modelica.Media.Interfaces.PartialCondensingGases
because it is used in vol2
and because
the model calls Medium2.enthalpyOfCondensingGas
,
which requires the medium to extend
from this subclass.dp2_nominal
in the base class.
The previous assignment caused a pressure drop in all except one element,
instead of the opposite. This caused too high a flow resistance
of the heat exchanger.