Heat Exchanger

The Heat Exchanger junction type is internal to the system and requires two connecting pipes. This junction type allows you to model the irrecoverable loss that occurs through heat exchanger equipment. You also have the ability to specify loss factors as a function of a flow parameter.

The Heat Exchanger Properties window follows the first of the two basic Properties window formats, displaying the connecting pipes in a fixed format. The flow direction through the junction is determined by the defined directions of the connecting pipes.

Subsonic losses in the Heat Exchanger junction can be represented using a K factor or by entering a resistance curve. When you select Resistance Curve, the Heat Exchanger Properties window makes additional features available. Using these new features you can input heat exchanger loss factors or pressure drops that vary with flow. To enter these factors, you can specify polynomial constants, fit a curve to available data, or use interpolated x-y data.

Heat Transfer

On the Thermal Data tab you can select from twelve different heat exchanger models.

Note that similar to flow rate definition, heat flow is positive when flowing into the system, and negative when flowing out.

When modeling convective heat exchangers (such as parallel or counterflow) two heat exchanger junctions can be linked thermally. This thermal linkWhen modeling heat transfer, heat input to heat exchangers can be modeled. A thermal link is when two heat exchanger junctions, which are hydraulically isolated, can exchange heat with each other. Typical use is when the two heat exchangers represent two sides of the same physical heat exchanger. When thermal linking is specified in a heat exchanger Specifications window, the user must specify the heat transfer area and overall convection coefficient. AFT Arrow will force the two heat exchanger junctions to use the same value. allows the two heat exchanger junctions to represent two sides of the same heat exchanger. This capability can also be used to model heat transfer between loops with different gases.

Special Conditions

The Special Condition for a Heat Exchanger junction functions differently than other junctions. Here you can turn off the heat transfer for the heat exchanger.