Pressure Drop Calculations for Grilles

The pressure drop across grilles is determined based on the selected pressure loss type - either loss coefficient or loss curve.

Loss Coefficient

Icepak calculates the loss coefficients based on the free area ratio of the grill and the type of grille. For the given grille type, the loss coefficient is computed as follow, where A is the free area ratio:

• Perforated thin vent, with a loss coefficient of

  

• Circular metal wire screen, with a loss coefficient of

  

• Two-plane screen with cylindrical bars, with a loss coefficient of

  

From the calculated loss coefficient above, the pressure drop is calculated as:

where v is the velocity that Icepak calculates based on the surrounding environment.

Loss Curve

You specify a piecewise-linear profile for the pressure drop as a function of speed. The pressure drop is then interpolated from the loss curve profile and the velocity that Icepak calculates based on the surrounding environment.