Chemical Engineering Equations

Barometric equation

This equation gives the relation between the pressures of the air with altitude. This equation is used for calculating air pressure under different conditions. 

Ostwald-de Waele equation

This is also known as Power law. This empirical equation expresses the relation between share stress and the velocity gradient. This equation describes the behavior of a fluid, especially the behavior of non-Newtonian fluid. 

Continuity equation

In fluid mechanics the continuity equation states that

Rate of mass flow in – Rate of mass flow out = Rate of mass accumulation

The equation of continuity can be written as

 

Navier-Stokes equation

The equation of motion with constant density and viscosity is known as Navier-Stokes equation.

 

Euler’s Equation

The equation of motion with constant density and zero viscosity (for potential flow) is known as Euler’s equation.

 

Bernoulli Equation

Bernoulli equation is an equation of conservation of mechanical energy for flowing fluids.

Without friction the equation can be written as

 

Hagen-Poiseuille equation

This equation is applicable for laminar flow through a pipe of uniform cross sectional area. Pressure drop can be calculated using this equation. The equation is

 

 

Reference

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

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