Additional models for heat exchangers

Extends from Modelica.Icons.BasesPackage (Icon for packages containing base classes).

Name | Description |
---|---|

BasicHX | Simple heat exchanger model |

WallConstProps | Pipe wall with capacitance, assuming 1D heat conduction and constant material properties |

Simple heat exchanger model

Simple model of a heat exchanger consisting of two pipes and one wall in between. For both fluids geometry parameters, such as heat transfer area and cross section as well as heat transfer and pressure drop correlations may be chosen. The flow scheme may be concurrent or counterflow, defined by the respective flow directions of the fluids entering the component. The design flow direction with positive m_flow variables is counterflow.

Name | Description |
---|---|

length | Length of flow path for both fluids [m] |

nNodes | Spatial segmentation |

Fluid 1 | |

modelStructure_1 | Determines whether flow or volume models are present at the ports |

replaceable package Medium_1 | Fluid 1 |

crossArea_1 | Cross sectional area [m2] |

perimeter_1 | Flow channel perimeter [m] |

replaceable model HeatTransfer_1 | Heat transfer model |

area_h_1 | Heat transfer area [m2] |

replaceable model FlowModel_1 | Characteristic of wall friction |

roughness_1 | Absolute roughness of pipe (default = smooth steel pipe) [m] |

Fluid 2 | |

modelStructure_2 | Determines whether flow or volume models are present at the ports |

replaceable package Medium_2 | Fluid 2 |

crossArea_2 | Cross sectional area [m2] |

perimeter_2 | Flow channel perimeter [m] |

replaceable model HeatTransfer_2 | Heat transfer model |

area_h_2 | Heat transfer area [m2] |

replaceable model FlowModel_2 | Characteristic of wall friction |

roughness_2 | Absolute roughness of pipe (default = smooth steel pipe) [m] |

Wall properties | |

s_wall | Wall thickness [m] |

k_wall | Thermal conductivity of wall material [W/(m.K)] |

c_wall | Specific heat capacity of wall material [J/(kg.K)] |

rho_wall | Density of wall material [kg/m3] |

Assumptions | |

allowFlowReversal | Allow flow reversal, false restricts to design direction (port_a -> port_b) |

Dynamics | |

energyDynamics | Formulation of energy balance |

massDynamics | Formulation of mass balance |

momentumDynamics | Formulation of momentum balance, if pressureLoss options available |

Initialization | |

Wall | |

Twall_start | Start value of wall temperature [K] |

dT | Start value for pipe_1.T - pipe_2.T [K] |

use_T_start | Use T_start if true, otherwise h_start |

Fluid 1 | |

p_a_start1 | Start value of pressure [Pa] |

p_b_start1 | Start value of pressure [Pa] |

T_start_1 | Start value of temperature [K] |

h_start_1 | Start value of specific enthalpy [J/kg] |

X_start_1[Medium_1.nX] | Start value of mass fractions m_i/m [kg/kg] |

m_flow_start_1 | Start value of mass flow rate [kg/s] |

Fluid 2 | |

p_a_start2 | Start value of pressure [Pa] |

p_b_start2 | Start value of pressure [Pa] |

T_start_2 | Start value of temperature [K] |

h_start_2 | Start value of specific enthalpy [J/kg] |

X_start_2[Medium_2.nX] | Start value of mass fractions m_i/m [kg/kg] |

m_flow_start_2 | Start value of mass flow rate [kg/s] |

Name | Description |
---|---|

port_b1 | |

port_a1 | |

port_b2 | |

port_a2 | |

Fluid 1 | |

replaceable package Medium_1 | Fluid 1 |

replaceable model HeatTransfer_1 | Heat transfer model |

replaceable model FlowModel_1 | Characteristic of wall friction |

Fluid 2 | |

replaceable package Medium_2 | Fluid 2 |

replaceable model HeatTransfer_2 | Heat transfer model |

replaceable model FlowModel_2 | Characteristic of wall friction |

Pipe wall with capacitance, assuming 1D heat conduction and constant material properties

`n`

) is meant to correspond to a connected fluid model discretization.
Name | Description |
---|---|

n | Segmentation perpendicular to heat conduction |

s | Wall thickness [m] |

area_h | Heat transfer area [m2] |

rho_wall | Density of wall material [kg/m3] |

c_wall | Specific heat capacity of wall material [J/(kg.K)] |

k_wall | Thermal conductivity of wall material [W/(m.K)] |

m[n] | Distribution of wall mass [kg] |

T_start | Wall temperature start value [K] |

dT | Start value for port_b.T - port_a.T [K] |

Assumptions | |

Dynamics | |

energyDynamics | Formulation of energy balance |

Name | Description |
---|---|

heatPort_a[n] | Thermal port |

heatPort_b[n] | Thermal port |