Ergun’s equation

AP equation arising from simultaneous turbulent kinetie and viseous energy losses that is applieable to all flow types. Ergun s equation relates the pressure drop per unit depth of paeked bed to eharaeteristies sueh as veloeity, fluid density, viseosity, size, shape, surfaee of the granular solids, and void fraetion. The original Ergun equation is ... 

Writing u = umf, the minimum fluidising velocity in Ergun s equation and substituting... 

Writing Ergun s equation for minimum fluidizing conditions, and assuming the particles to be spherical ( =1), gives... 

The gas-phase pressure drop is better evaluated by using the differential form of Ergun s equation and taking into account the gas density variance. However, it is easy to show that the parameter aZIPi is about 0.001, and thus the Ergun equation in its classic form can be accurately used (see subsection Nonisobaric fixed-bed operation). 

Ergun s equation on drop of fluid pressure when flowing through a bed of solid particles [1] ... 

The pressure drop was calculated using Ergun s equation with dp defined as follows, to account for the shape of the annular catalyst particle (27) ... 

These workers, who originally suggested the above approach, made use of the Ergun (E3) packed-bed equation for relating Umt to gas and solids properties by putting APfH in Ergun s equation equal to (ps — Pi) (1 —... 

The model of Tayakout et al. [117,118] in addition accounts for the possibility of axial dispersion effects in the tubeside and shellside. The inclusion of axial dispersion effects in regions (1) and (4) necessitates a different set of initial conditions at Z = 0 and a companion set of conditions at Z = L. The effect of pressure drop through the catalytic bed could be included in this type of model using Ergun s equation. 

The constants in the Ergun s equation depend on the hydrodynamic regime. For example, if Re/(1- ) < 500 then =1.75 and S=150. For larger Reynolds values the correlation of Hicks (1970) can be used ... 

Pressure drops are caused simultaneous kinetic and viscous energy losses and Ergun s equation is the most famous model having the form of the Reynolds equation. 

Some well-known equations for the friction factor for flow in packed beds are Ergun s equation [14]... 

Since Re =110, Ergun s equation should be chosen and not Handley and Hegg s. 

Solution 9.5a. The gas density, pf = MP/RT, equals 0.86 kg m . Since 94% of the gas is air, we can assume that its viscosity is equal to that of air at the reactor operating temperature—0.000033 Pa s. All other operating parameters were defined in the problem. The pressure drop is calculated from Ergun s equation ... 

From the friction factor, one can find several correlations in the literature on this variable. We can use the Ergun s equation (Froment and Bischoff, 1979), which is usually practiced in the literature ... 

For the hoUow-fiber membranes, the flow on the feed-side is across a densely packed bed of fibers. The pressure drop in this membrane side can be calculated using Ergun s equation [24] ... 

Caravella et al. (2008) PBMR - ID - Nonisothermal conditions - Plug flow - Membrane completely selective toward H2 permeation - Ergun s equation - Xu and Froment (1989a) The paper pointed out that the reactive/permeative stage distribution has to be considered an important reactor design parameter. 

The bed pressure drop Ap through the layer of coal can be calculated from the well-known Ergun s equation ... 

The calculation of pressure drop and pressure variation in reactors can be a difficult problem, particularly if a change of phase occurs or more than one phase is present. Although this effect is often small and/or can be neglected (particularly if the reactor is already under pressure), the reader should become familiar with the methods of calculating pressure drop in reactors. The literature provides information for these calculations Fanning s equation may be used to calculate pressure drop for homogenous reactions, while Ergun s equation is normally employed for fixed-bed reac-tors. The mass of the catalyst divided by the cross-sectional area of the reactor... 

Ergun s equation is applied generally to describe the pressure drop in the catalyst bed ... 

The pressure drop is formed due to catalyst packing and can be expressed by Ergun s equation (Eq. (9.8)), in which the average gas velocity is calculated as... 

Ergun s equation is used for pressure drop AP (Pa m ) in the catalyst bed (Ergun,1952). 

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