Conductive Heat Transfer
Conductive thermal conductivity.
blockType: AcausalFoundation.Thermal.Elements.Conduction
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Conductive Heat Transfer Path in the library: |
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Variable Conductive Heat Transfer Path in the library: |
Description
Block Conductive Heat Transfer It is the transfer of heat through conductive heat exchange between two layers of the same material.
The block icon changes depending on the value of the Conductivity type parameter.
For a flat surface, the transfer is described by Fourier’s law:
where:
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— heat flow;
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— thermal conductivity of the material;
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— the cross-sectional area perpendicular to the direction of the heat flow;
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— the distance between the layers, that is, the thickness of the material;
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— temperature of layer A;
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— temperature of layer B.
Thermal conductivity through the cylindrical pipe wall:
where:
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— pipe length;
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— inner diameter;
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— outer diameter.
Thermal conductivity can be specified using the Conductivity type parameter.:
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Constant— thermal conductivity remains constant during simulation. You set the thermal conductivity using the Thermal conductivity parameter. -
Variable input— Thermal conductivity is set using the input signal on port K, which can change during simulation. The Minimum thermal conductivity parameter sets the lower limit of the signal. -
Tabulated data— Thermal conductivity is indicated using temperature-based tabular data. In this case, the thermal conductivity may also change during the simulation process.
Option Tabulated data uses the average temperature of the unit to determine the thermal conductivity. For a flat wall geometry, the average temperature is
For the cylindrical geometry of the wall, the average temperature is
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which suggests that it is located inside the cylinder.
A and B are the thermal ports corresponding to the material layers. The positive direction of heat transfer from port A to port B, in this case, the value of the heat flow is positive.
Ports
Entrance
K is the thermal conductivity control signal, W/(K*m)
scalar
The input signal controlling the thermal conductivity. The signal is saturated when the value exceeds the minimum limit set by the Minimum thermal conductivity parameter.
Dependencies
To use this port, set the Conductivity type parameter to Variable input.
Parameters
Conductivity type — the type of setting the properties of thermal conductivity
Constant (by default)| Variable input| Tabulated data
Type of thermal conductivity assignment:
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Constant— thermal conductivity remains constant during simulation. You set the thermal conductivity using the Thermal conductivity parameter. -
Variable input— Thermal conductivity is set using the input signal on port K, which can change during simulation. The Minimum thermal conductivity parameter sets the lower limit of the signal. -
Tabulated data— Thermal conductivity is indicated using temperature-based tabular data. In this case, the thermal conductivity may also change during the simulation process.
Wall geometry — wall shape for thermal conductivity
Planar (by default)| Cylindrical
Wall shape for thermal conductivity:
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Planar— heat transfer is carried out through a flat rectangular wall. The area and thickness of the wall are indicated. -
Cylindrical— heat transfer is carried out through the cylindrical wall of the pipe. The inner diameter, outer diameter and length of the pipe are indicated.
Area — heat exchange area
1e−4 m2 (default) | positive scalar
The cross-sectional area perpendicular to the direction of the heat flow.
Dependencies
To use this parameter, set the Wall geometry parameter to Planar.
Thickness — thickness of the pass material:q[<br>] 0.1 m (default) | positive scalar
The thickness of the material, that is, the distance between the layers.
Dependencies
To use this parameter, set the Wall geometry parameter to Planar.
Inner diameter — inner diameter of the pipe
0.05 m (default) | positive scalar
The inner diameter of the pipe, that is, the diameter of the inner layer of the material.
Dependencies
To use this parameter, set the Wall geometry parameter to Cylindrical.
Outer diameter — the outer diameter of the pipe
0.1 m (default) | positive scalar
The outer diameter of the pipe, that is, the diameter of the outer layer of the material.
Dependencies
To use this parameter, set the Wall geometry parameter to Cylindrical.
Length — pipe length
1.0 m (default) | positive scalar
Pipe length.
Dependencies
To use this parameter, set the Wall geometry parameter to Cylindrical.
Thermal conductivity — thermal conductivity of the material
401.0 W/(K*m) (default) | positive scalar
Thermal conductivity of the material.
Dependencies
To use this parameter, set the Conductivity type parameter to Constant.
Minimum thermal conductivity — lower limit of thermal conductivity
10W/(K*m) (default) | positive scalar
The lower limit of the thermal conductivity value. The input signal on the K port is saturated at this value to prevent further reduction of thermal conductivity.
Dependencies
To use this parameter, set the Conductivity type parameter to Variable input.
Thermal conductivity vector — a vector of thermal conductivity values to use in the pass:q search table[<br>] [413, 401, 392, 383, 371, 357, 342] W/(K*m) (default) | vector of positive values
A vector of thermal conductivity values corresponding to the values of the Temperature vector parameter. The size of the vector must be the same as the Temperature vector parameter. The block performs a one-dimensional search on the thermal conductivity table using the average temperature of the block, linear interpolation and the nearest extrapolation.
Dependencies
To use this parameter, set the Conductivity type parameter to Tabulated data.
Temperature vector is a vector of temperature values for use in the thermal conductivity table
[200, 273, 400, 600, 800, 1000, 1200] K (default) | strictly increasing vector
A vector of temperature values corresponding to the values of the parameter Thermal conductivity vector. The vector must be strictly increasing. The values may be unevenly spaced. The vector must contain at least two values.
Dependencies
To use this parameter, set the Conductivity type parameter to Tabulated data.