14.3.3 Specifying the Auxiliary Fluid Inlet and Pass-to-Pass Directions

To define the auxiliary fluid direction and flow path, you will specify direction vectors for the Auxiliary Fluid Inlet Direction and the Pass-to-Pass Direction in the Geometry tab. Figure  14.3.6 shows these directions relative to the macros.

For some problems in which the principal axes of the heat exchanger core are not aligned with the coordinate axes of the domain, you may not know the auxiliary fluid inlet and pass-to-pass direction vectors a priori. In such cases, you can use the plane tool as follows to help you to determine these direction vectors.

1.   "Snap'' the plane tool onto the boundary of the heat exchanger core. (Follow the instructions in Section  28.6.1 for initializing the tool to a position on an existing surface.)

2.   Translate and rotate the axes of the tool appropriately until they are aligned with the principal directions of the heat exchanger core. The depth direction is determined by the red axis, the height direction by the green axis, and the width direction by the blue axis.

3.   Once the axes are aligned, click the Update from Plane Tool button in the Ungrouped Macro Heat Exchanger dialog box. The directional vectors will be set automatically. (Note that the Update from Plane Tool button will also set the height, width, and depth of the heat exchanger core.)