.AixLib.Fluid.Chillers.ModularReversible.RefrigerantCycle.ConstantCarnotEffectiveness

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

Revisions

• October 2, 2022 by Fabian Wuellhorst:
  First implementation (see issue #1576)