Heat Exchanger Modelling

The heat exchangers, such as condenser and radiators, are modelled using porous media model. Since the actual geometry may consist of a lot of tubes and fins, creating a mesh becomes complicated. The advantage of using porous media model is that there is no need to model the actual geometry. The heat exchanger is modelled using source terms, with a pressure drop across it.

This model incorporates a pressure drop (DP) that is a function of the fluid velocity (V). The flow resistance data is usually obtained from experimental results.

In Simerics-MP+, the resistance model is activated to model the heat exchangers. The linear and quadratic coefficients are provided under the resistance model. The procedure for the calculation of coefficients is explained as follows:

From the DP- V curve, the data (see, Table 7.1) is plotted in an excel sheet and obtained as the second order polynomial equation using trend line (see, Figure 7.10).

Coefficients from the curve fit are:

Linear Coefficient (a): 28.624

Quadratic Coefficient (b): 3.0983

Thickness of the radiator (t): 0.02536 m

Calculated Linear Coefficient = 1128.706

Calculated Quadratic Coefficient = 103.276

Figure 7.10 - Radiator Coefficient

Velocity (m/s)	Pressure, dp (Pa)
6.52	318.3
6.74	333.8
7.06	356.4
7.48	387.5

Table 7.1 - Flow and Pressure data

Note: For more information on derivation of porous media parameters, refer porous media.