modelPartialVelocityBased
Extends from AixLib.Fluid.HeatPumps.ModularReversible.RefrigerantCycle.Frosting.BaseClasses.PartialIcingFactor (Partial model to calculate the icing factor).
Information
Partial model to estimate the icing factor based on ice mass and a frost-growth velocity. Using the maximal ice mass and the current mass, the ice factor is calculated using:
iceFac=1 - mIce/mIceMax.
The concept was first used by Vering et al. and further developed during the PhD from Fabian Roemer and published in the paper Roemer et al.
Note, it is important to add the QEva_flow and relHum to the signal bus in order for the frosting models to work properly.
Density of the frost layer can be constant or dynamic using AixLib.Fluid.HeatPumps.ModularReversible.RefrigerantCycle.Frosting.BaseClasses.FrostDensityKorn .
References
Römer, Fabian and Fuchs, Nico and Fuchs, Nico and Müller, Dirk, Practical, Near-Optimal Design Rule Extraction for Heat Pumps in Single-Family Buildings (September 03, 2025). Available at SSRN: https://ssrn.com/abstract=5633891
Vering, C., Wüllhorst, F., Mehrfeld, P., and Müller, D. (2021). Towards an integrated design of heat pump systems: Application of process intensification using two-stage optimization. Energy Conversion and Management, 250, 114888. https://doi.org/10.1016/j.apenergy.2024.123225
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Units.SI.Area | A | 15 | Area of heat exchanger, all fins from both sides |
| Boolean | use_reset | false | = true, if reset port enabled |
| Advanced › Medium properties | |||
| Modelica.Units.SI.SpecificHeatCapacity | cpEva (from PartialIcingFactor) | Evaporator medium specific heat capacity | |
| Density | |||
| Boolean | use_varDen | false | =true to use variable density based on PT1 Element, e.g. Korn et al. |
| Modelica.Units.SI.Density | den_constant | 659 | Constant density of frost, based on Korn at -5 frost temperature |
| Real | k | 3.77 | Gain |
| Modelica.Units.SI.Time | T | 8000 | Time Constant |
| Real | den_min | 50 | Minimal density |
| Ice mass | |||
| Boolean | estimateMaximalIceMass | true | =false to specify maximal ice mass directly |
| Modelica.Units.SI.Mass | mIce_max | den_constant*A*d/2 | Maximal possible mass of ice on HE surface. This value is limited by the volume between the fin tube |
| Modelica.Units.SI.Distance | d | 3e-3 | Distance between two fins. Used to calculate the maximal mass of ice on the HE |
| Melting | |||
| Real | natConvCoeff | 1e-7 | Parameter to be calibrated for natural defrost |
| Modelica.Units.SI.SpecificEnthalpy | hWatFus | 333.5e3 | Fusion enthalpy of water |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| AixLib.Fluid.HeatPumps.ModularReversible.BaseClasses.RefrigerantMachineControlBus | sigBus (from PartialIcingFactor) | Bus-connector used in a heat pump | |
| Modelica.Blocks.Interfaces.RealOutput | iceFac (from PartialIcingFactor) | Icing factor from 0 to 1 to estimate influence of icing |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Blocks.Sources.RealExpression | groRatFor_internal | Growth rate for forced convection from internal calcuations | |
| Modelica.Blocks.Sources.RealExpression | groRatNat_internal | Growth rate for natural convection from internal calcuations | |
| Modelica.Blocks.Logical.Switch | switchGrowthRate | ||
| Modelica.Blocks.Logical.Switch | swiMFloIce | Switch between ice growth rates | |
| Modelica.Blocks.Math.Gain | gaiADen | Gain with area and density | |
| Modelica.Blocks.Math.Product | gaiDenCoeff | Gain with density coefficient | |
| Modelica.Blocks.Math.Gain | gaiWatFus | Negate and divide by fusion enthalpy | |
| Modelica.Blocks.Logical.And | and1 | Is on and heating | |
| Modelica.Blocks.Math.Gain | divIceMax | Divide by maximal ice mass | |
| Modelica.Blocks.Math.Add | gaiADen2 | Gain with area and density | |
| Modelica.Blocks.Sources.Constant | conOne | Upper efficiency limit | |
| Modelica.Blocks.Sources.RealExpression | denCoe_internal | Internal density coefficient calculation based on zones | |
| Modelica.Blocks.Routing.RealPassThrough | reaPasThrTOda | Outdoor air temperature | |
| Modelica.Blocks.Math.Product | proAGroRatDen | Gain with area and density | |
| Modelica.Blocks.Sources.Constant | conDen | Constant density | |
| AixLib.Fluid.HeatPumps.ModularReversible.RefrigerantCycle.Frosting.BaseClasses.IceMassIntegrator | iceMassIntegrator | ||
| AixLib.Fluid.HeatPumps.ModularReversible.RefrigerantCycle.Frosting.BaseClasses.FrostDensityKorn | froDenKornPT1 | Frost density according to Korn |
Revisions
-
December 22, 2025 by Fabian Roemer:
First implementation (see issue AixLib #1623)