Pressure Drop and Acceleration Length in Developing Regions

3 Pressure Drop and Acceleration Length in Developing Regions 

Consider a one-dimensional gas-solid pipe flow where the electrostatic effect is negligible. The momentum equation of the particle phase can be expressed as [Klinzing, 1981] 

The acceleration length and the pressure loss in that length can also be estimated by using empirical correlations. Rose and Duckworth (1969) reported that 

The gas-solid flow through a bend represents another typical case of developing regions, in which particles are first decelerated by gas impingement and collision with the wall and then accelerated by the gas after the bend turn. A general empirical relation for the estimation of the additional pressure drop due to particles over a bend can be used [Klinzing, 1981] 

It is noted that the total pressure drop over a bend includes contributions from both the gas and particle phases. The pressure drop of gas over a bend, ApBg, can be estimated by [Ito, 1959 1960] 

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