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32.3.39 Define/User-Defined/Heat Exchanger...

The Define/User-Defined/Heat Exchanger... menu item opens the Heat Exchanger Model panel. (This item is available only in 3D.)



Heat Exchanger Model Panel


The Heat Exchanger Model panel allows you to define a heat exchanger as part of your model. It is available only in 3D. See Section  7.25.3 for details about using the items below.

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Controls

Fluid Zone   specifies the zone that represents the heat exchanger.

Model Data   contains the parameters related to heat transfer model.

Options   allows you to choose one of the following settings:
Fixed Heat Rejection   specifies that FLUENT should compute the coolant inlet temperature for a specified heat rejection.

Fixed Inlet Temperature   specifies that FLUENT should compute the total heat rejection of the core for a given inlet coolant temperature.

Heat Transfer Model   allows you to specify either the ntu-model or the simple-effectiveness-model for heat transfer.

Core Porosity Model   contains a drop-down list of all available core porosity models.

Edit...   opens the Core Porosity Model panel (see Section  7.25.3).

Heat Exchanger Performance Data   contains the parameters for heat transfer.
Heat Transfer Data...   opens the Heat Transfer Data Table panel (see Section  2e). This item will appear for NTU model only.

Auxiliary Fluid Temperature   specifies the coolant fluid temperature. This item will appear only for NTU model.

Primary Fluid Temperature   specifies the gas stream temperature. This item will appear only for NTU model.

Velocity Effectiveness Curve...   opens the Velocity Effectiveness Curve panel in which you can define the effectiveness of the heat exchanger core ( $\epsilon$ in Equation  7.25-11). This item will appear for simple effectiveness model only.

Geometry   contains parameters to define the macro grid.

Width   sets the width of the heat exchanger core. The Width is measured in the pass-to-pass direction.

Height   sets the height of the heat exchanger core. The Height is measured in the coolant inlet direction.

Depth   sets the depth of the heat exchanger core.

Number of Passes   specifies the number of passes for the macro grid. (See Figure  7.25.6.)

Number of Rows/Pass, Number of Columns/Pass   specify the number of macro rows and columns per pass in the macro grid. (See Figure  7.25.6.)

View Passes   displays the macro grid. (This button becomes available after you click Set.) The path of the coolant is color-coded in the display: macro $0$ is red and macro $n-1$ is blue.

Draw Grid   toggles between displaying and not displaying the grid when the macro grid is displayed (using the View Passes button). The Grid Display panel opens when Draw Grid is selected.

Update from Plane Tool   updates the Coolant Inlet Direction and Pass-to-Pass Direction from the plane tool orientation. The Width, Height, and Depth will also be updated. See Section  27.6.1 for information about using the plane tool.

Auxiliary Fluid Inlet Direction (height)   specifies the direction in which the coolant enters the heat exchanger. See Figure  7.25.6.

Pass-to-Pass Direction (width)   specifies the direction in which the coolant moves at the end of each pass through the heat exchanger. See Figure  7.25.6.

Auxiliary Fluid   contains the option to specify the coolant properties.
Auxiliary Fluid Properties Method   contains options for specifying coolant properties.
constant-specific-heat   allows you to specific a constant value for the coolant specific heat.

user-defined-enthalpy   allows you to specify a user-defined function for the coolant enthalpy.

Auxiliary Fluid Specific Heat   specifies the value of $c_{p,coolant}$ in Equation  7.25-17. This value is specified only if constant-specific-heat is selected.

Auxiliary Fluid Enthalpy UDF   allows you to specify a UDF for the coolant enthalpy (see Equation  7.25-17). This option is available only when user-defined-enthalpy is selected.

Auxiliary Fluid Flow Rate   sets the flow rate of the coolant ( $\dot{m}$ in Equation  7.25-16).

Heat Rejection   sets the total heat rejection ( $q_{\rm total}$ in Equation  7.25-15). This value is specified only if Fixed Heat Rejection is selected.

Initial Temperature   sets an initial guess for the inlet temperature ( $T_{_{\rm in}}$ in Equations  7.25-11 and 7.25-16). This value is specified only if Fixed Heat Rejection is selected.

Inlet Temperature   sets the coolant initial temperature ( $T_{_{\rm in}}$ in Equations  7.25-11 and 7.25-16). This value is specified only if Fixed Inlet Temperature is selected in the Model Data tab.

Inlet Pressure   sets the coolant inlet pressure. This value is specified only if user-defined-enthalpy is selected.

Inlet Quality   specifies the value of $x$ in Equation  7.25-20. This value is specified only if user-defined-enthalpy is selected.

Pressure Drop   specifies the value of $p_{in}$ in Equation  7.25-21. This value is specified only if user-defined-enthalpy is selected.

Apply   saves all the settings for the heat exchanger specified in the Fluid Zone list.

Delete   deletes the heat exchanger specified in the Fluid Zone list.



Velocity Effectiveness Curve Panel


The Velocity Effectiveness Curve panel allows you to define effectiveness curve. It is opened by clicking Velocity Effectiveness Curve... in the Heat Exchanger Model panel.

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Controls

Number of Points   specifies the number of data pairs in the effectiveness profile. The default value of 1 indicates a constant effectiveness.

Velocity, Effectiveness   specify the data pairs for the effectiveness profile. These items are available only if the simple effective model has been selected.



Heat Transfer Data Table Panel


The Heat Transfer Data Table panel opens when you click Heat Transfer Data... (which appears only for NTU model) in the Heat Exchanger Model panel. This panel allows you to define the heat transfer for different primary and auxiliary fluid flow rates.

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Controls

Number of Auxiliary Fluid Flow Rates   sets the number of coolant flow rates.

Number of Primary Fluid Flow Rates   sets the number of gas stream flow rates.

Auxiliary Fluid Flow Rate   sets fluid flow rates for the coolant.

Primary Fluid Flow Rate   sets fluid flow rates for gas stream.

Heat Transfer   sets the heat transfer for corresponding coolant and gas stream flow rates.


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