This is the base class for the Carnot chiller and the Carnot heat pump whose coefficient of performance COP changes with temperatures in the same way as the Carnot efficiency changes.
Set use_eta_Carnot_nominal=true to specify directly
the Carnot effectiveness ηCarnot,0,
in which case the value of the parameter COP_nominal
will not affect the simulation.
If use_eta_Carnot_nominal=false, the model will use
the value of the parameter COP_nominal
together with the specified nominal temperatures
to compute the Carnot effectiveness as
ηCarnot,0 = COP0 ⁄ (Tuse,0 ⁄ (Tcon,0 + Tapp,con,0 - (Teva,0-Tapp,eva,0))),
where
Teva,0 is the evaporator temperature,
Tcon,0 is the condenser temperature,
Tapp,eva,0 is the evaporator approach temperature,
Tapp,con,0 is the condenser approach temperature, and
Tuse,0 is the temperature of the the useful heat.
If COP_is_for_cooling=true,
then Tuse,0 is the condenser temperature of a heat pump plus the approach temperature,
otherwise it is the evaporator temperature minus the approach temperature of a chiller.
The COP is computed as the product
COP = ηCarnot,0 COPCarnot ηPL,
where COPCarnot is the Carnot efficiency and ηPL is the part load efficiency, expressed using a polynomial. This polynomial has the form
ηPL = a1 + a2 y + a3 y2 + ...,
where y ∈ [0, 1] is
either the part load for cooling in case of a chiller, or the part load of heating in
case of a heat pump, and the coefficients ai
are declared by the parameter a.
To make this base class applicable to chiller or heat pumps, it uses
the boolean constant COP_is_for_cooling.
Depending on its value, the equations for the coefficient of performance
and the part load ratio are set up.
etaCarnot_nominal(unit="1") = COP_nominal/(TUseAct_nominal/(TCon_nominal+TAppCon_nominal - (TEva_nominal-TAppEva_nominal)))
to
etaCarnot_nominal(unit="1") = 0.3 to avoid a circular assignment.homotopyInitialization to a constant.evaluate_etaPL and how it is used.
This correction only affects protected variables and does not affect the results.