modelConstantCarnotEffectiveness
Extends from AixLib.Fluid.Chillers.ModularReversible.RefrigerantCycle.BaseClasses.PartialChillerCycle, AixLib.Fluid.HeatPumps.ModularReversible.RefrigerantCycle.BaseClasses.PartialCarnot.
Information
This model uses a constant Carnot effectiveness approach to compute the efficiency of the chiller.
PEle_nominal is computed from the provided
QCoo_flow_nominal and other nominal conditions.
PEle_nominal stays constant over all boundary conditions
and is used to calculate PEle by multiplying it with the
relative compressor speed.
QEva_flow is computed using the Carnot approach:
QEva_flow = PEle_nominal * etaCarnot_nominal * yMea *
(TEvaOut - TAppEva) /
(TConOut + TAppCon - (TEvaOut - TAppEva))
PEle = PEle_nominal * yMea
These equations follow the same methods used in
AixLib.Fluid.Chillers.Carnot_y
Similarly, the variables TAppCon and
TAppEva define the approach (pinch) temperature differences.
The approach temperatures are calculated using the following equation:
TApp = TApp_nominal * Q_flow / Q_flow_nominal
This introduces nonlinear equations to the model, which
can lead to solver issues for reversible operation.
You can use the nominal values as a constant by
enabling use_constAppTem
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Nominal condition | |||
| Real | EER_nominal | etaCarnot_nominal*(TEva_nominal - TAppEva_nominal)/(TCon_nominal + TAppCon_nominal - (TEva_nominal - TAppEva_nominal)) | Nominal EER |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Blocks.Sources.Constant | constNegOne | Negative one to negative evaporator heat flow rate |
Revisions
-
October 2, 2022 by Fabian Wuellhorst:
First implementation (see issue #1576)