Buildings.Fluid.HeatPumps.ModularReversible.RefrigerantCycle.Frosting.Functions

Package with functions to calculate current icing factor on evaporator

Information

This package contains functions for calculation of an icing factor used in Buildings.Fluid.HeatPumps.ModularReversible.RefrigerantCycle.Frosting.FunctionalIcingFactor.

Package Content

Name	Description
partialIcingFactor	Base function for all icing factor functions
wetterAfjei1997	Correction of COP for icing and defrost according to Wetter, Afjei and Glass

Buildings.Fluid.HeatPumps.ModularReversible.RefrigerantCycle.Frosting.Functions.partialIcingFactor

Base function for all icing factor functions

Information

Base function for calculation of the icing factor iceFac. It represents the reduction of heat exchange as a result of icing of the evaporator.

This function is used in the model Buildings.Fluid.HeatPumps.ModularReversible.RefrigerantCycle.Frosting.FunctionalIcingFactor.

Typically, functions should only require evaporator side data for calculation of the iceFac.

For more information on the iceFac, see the documentation of Buildings.Fluid.HeatPumps.ModularReversible.RefrigerantCycle.BaseClasses.PartialRefrigerantCycle

Extends from Modelica.Icons.Function (Icon for functions).

Inputs

Type	Name	Description
ThermodynamicTemperature	TEvaInMea	Evaporator supply temperature. Should be equal to outdoor air temperature [K]
ThermodynamicTemperature	TEvaOutMea	Evaporator return temperature [K]
MassFlowRate	mEva_flow	Mass flow rate at the evaporator [kg/s]

Outputs

Type	Name	Description
Real	iceFac	Icing factor (0: no heat transfer; 1: no effect) [1]

Modelica definition

partial function partialIcingFactor "Base function for all icing factor functions" extends Modelica.Icons.Function; input Modelica.Units.SI.ThermodynamicTemperature TEvaInMea "Evaporator supply temperature. Should be equal to outdoor air temperature"; input Modelica.Units.SI.ThermodynamicTemperature TEvaOutMea "Evaporator return temperature"; input Modelica.Units.SI.MassFlowRate mEva_flow "Mass flow rate at the evaporator"; output Real iceFac(final unit="1", min=0, max=1) "Icing factor (0: no heat transfer; 1: no effect)"; end partialIcingFactor;

Buildings.Fluid.HeatPumps.ModularReversible.RefrigerantCycle.Frosting.Functions.wetterAfjei1997

Correction of COP for icing and defrost according to Wetter, Afjei and Glass

Information

Correction of the coefficient of performance due to icing/frosting according to Wetter, Afjei and Glass (1997).

For more information on the iceFac, see the documentation of Buildings.Fluid.HeatPumps.ModularReversible.RefrigerantCycle.BaseClasses.PartialRefrigerantCycle

References

Thomas Afjei, Michael Wetter and Andrew Glass.
TRNSYS type: Dual-stage compressor heat pump including frost and cycle losses. Model description and implementation in TRNSYS.
TRNSYS user meeting, November 1997, Stuttgart, Germany.
https://simulationresearch.lbl.gov/wetter/download/type204_hp.pdf

Extends from Buildings.Fluid.HeatPumps.ModularReversible.RefrigerantCycle.Frosting.Functions.partialIcingFactor (Base function for all icing factor functions).

Inputs

Type	Name	Description
ThermodynamicTemperature	TEvaInMea	Evaporator supply temperature. Should be equal to outdoor air temperature [K]
ThermodynamicTemperature	TEvaOutMea	Evaporator return temperature [K]
MassFlowRate	mEva_flow	Mass flow rate at the evaporator [kg/s]

Outputs

Type	Name	Description
Real	iceFac	Icing factor (0: no heat transfer; 1: no effect) [1]

Modelica definition

function wetterAfjei1997 "Correction of COP for icing and defrost according to Wetter, Afjei and Glass" extends Buildings.Fluid.HeatPumps.ModularReversible.RefrigerantCycle.Frosting.Functions.partialIcingFactor; protected parameter Real offLin=0.03 "First factor for linear term, offset"; parameter Real sloLin=-0.004 "Second factor for linear term, slope"; parameter Real gauFac=0.1534 "Parameter for gaussian curve, factor"; parameter Real gauMea=0.8869 "Parameter for gaussian curve, mean"; parameter Real gauSig=26.06 "Parameter for gaussian curve, sigma"; Real fac "Probability of icing"; Real linTer "Linear part of equation"; Real gauTer "Gaussian part of equation"; algorithm linTer :=offLin + sloLin*TEvaInMea; gauTer :=gauFac*Modelica.Math.exp(-(TEvaInMea - gauMea)*(TEvaInMea - gauMea)/ gauSig); fac := gauTer + Buildings.Utilities.Math.Functions.smoothMax( x1=1E-5, x2= linTer, deltaX=0.25E-5); iceFac:=1 - fac; end wetterAfjei1997;