Chemical Engineering Equations

Kozeny - Carman equation

This equation is used for calculating pressure drop for flow through packed beds. The equation is valid for the particle Reynolds number up to about 1.0. 

Burke – Plummer equation

This equation is applied for calculating pressure drop in packed beds at high Reynolds number (Re_p > 1000). 

Ergun equation

The Ergun equation is applicable for entire range of flow rates in flow through packed bed. Here the viscous losses and the kinetic losses are assumed to be additive.

Expression for NPSH

To avoid cavitation in pump, the pressure in the pump inlet must exceed the vapour pressure by a certain value, called the net positive suction head (NPSH). The equation of NPSH can be written as 

Expression for volumetric flow rate in venturi meter

The volumetric flow rate through the venturi meter can be written by the expression

 

Expression for volumetric flow rate in orifice meter

The volumetric flow rate through a orifice meter can be written as

 

Expression for Friction loss because of sudden expansion and contraction in cross section

The expression for expansion loss coefficient is

Where, S_a and S_b are the cross sectional area a of upstream and downstream conduits, respectively.

 

Reference:

1.      Unit operations of Chemical Engineering, 6^th edition, by Warren L. McCabe, Julian C. Smith, and Peter Harriott.

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