modelFlowDependentHeatTransferCoefficient
Extends from BaseClasses.DistributedHeatTransferFV (Base class for distributed heat transfer models - finite volumes).
Information
This component assumes a uniform heat transfer coefficient gamma_nom*(w/wnom_ht)^alpha. When w/wnom_ht < beta the heat transfer coefficient stops decreasing, to avoid numerical problems at low flows.
If useAverageTemperature=false, the outlet fluid temperature of each volume is used to compute the heat transfer, otherwise the average temperature between inlet and outlet is used.
In the latter case, the temperature distribution is accurately predicted if N > NTU. However, non-physical temperature distributions and numerical problems can arise at low flows, when NTU increases. If adaptiveAverageTemperature=true, then the outlet temperature is used instead of the average one when w/wnom_ht < sigma. This leads to physically realistic temperature distributions and better numerical properties at low or zero flows.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Boolean | useAverageTemperature (from DistributedHeatTransferFV) | true | = true to use average temperature for heat transfer |
| SI.Length | l (from DistributedHeatTransferFV) | L/(Nw) | Length of a single volume |
| Modelica.SIunits.PerUnit | kc (from DistributedHeatTransferFV) | 1 | Correction factor for heat transfer |
| SI.CoefficientOfHeatTransfer | gamma_nom | Nominal heat transfer coefficient | |
| SI.PerUnit | alpha | Exponent in the flow-dependency law | |
| SI.PerUnit | beta | 0.1 | Fraction of nominal flow rate below which the heat transfer is not reduced |
| SI.MassFlowRate | wnom_ht | wnom | Nominal flow rate for heat transfer correlation (single tube) |
| Boolean | adaptiveAverageTemperature | true | Adapt the average temperature at low flow rates |
| Modelica.SIunits.PerUnit | sigma | 0.1 | Fraction of nominal flow rate below which the heat transfer is computed on outlet volume temperatures |
| Boolean | useHomotopy | true | use nominal heat transfer coefficient for simplified model |
| Set by Flow1D model | |||
| Integer | Nf (from DistributedHeatTransferFV) | 2 | Number of nodes on the fluid side |
| Integer | Nw (from DistributedHeatTransferFV) | Nf - 1 | Number of volumes on the wall side |
| Integer | Nt (from DistributedHeatTransferFV) | Number of tubes in parallel | |
| SI.Distance | L (from DistributedHeatTransferFV) | Tube length | |
| SI.Area | A (from DistributedHeatTransferFV) | Cross-sectional area (single tube) | |
| SI.Length | omega (from DistributedHeatTransferFV) | Wet perimeter of heat transfer surface (single tube) | |
| SI.Length | Dhyd (from DistributedHeatTransferFV) | Hydraulic Diameter (single tube) | |
| SI.MassFlowRate | wnom (from DistributedHeatTransferFV) | Nominal mass flow rate (single tube) | |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| ThermoPower.Thermal.DHTVolumes | wall (from DistributedHeatTransferFV) |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Medium.ThermodynamicState[Nf] | fluidState (from DistributedHeatTransferFV) | ||
| Medium.MassFlowRate[Nf] | w (from DistributedHeatTransferFV) | ||
| Medium.Temperature[Nf] | T (from DistributedHeatTransferFV) | Temperatures at the fluid side nodes | |
| Medium.Temperature[Nw] | Tw (from DistributedHeatTransferFV) | Temperatures of the wall volumes | |
| SI.Power[Nw] | Qw (from DistributedHeatTransferFV) | Heat flows entering from the wall volumes | |
| SI.Power[Nf - 1] | Qvol (from DistributedHeatTransferFV) | Qw | Heat flows going to the fluid volumes |
| SI.Power | Q (from DistributedHeatTransferFV) | Total heat flow through lateral boundary | |
| Medium.Temperature[Nw] | Tvol | Fluid temperature in the volumes | |
| SI.CoefficientOfHeatTransfer | gamma | Actual heat transfer coefficient | |
| SI.PerUnit | w_wnom | Ratio between actual and nominal flow rate | |
| SI.PerUnit | w_wnom_reg | Regularized ratio between actual and nominal flow rate |