## What is G in Ergun equation?

G = superficial mass velocity. MW = molecular weight of fluid. NRe = Reynolds number, dimensionless. P = fluid pressure, psia. PD = particle diameter, in.

**How is Ergun equation derived?**

The Ergun equation, derived by the Turkish chemical engineer Sabri Ergun in 1952, expresses the friction factor in a packed column as a function of the modified Reynolds number.

### Is the Ergun equation accurate?

The Ergun equation is only able to accurately predict the pressure drop of single-phase flow over spherical particles, whereas it systematically under predicts the pressure drop of single-phase flow over non-spherical particles.

**How do you calculate bed voidage?**

The actual calculation of voidage is simple: it is the amount of empty space divided by the total volume.

## Is Ergun equation empirical?

The results are compared to the Ergun equation, which is empirically based on experimental measurements, and the correspondence is shown to be remarkably close.

**How do you calculate the volume of a packed bed reactor?**

By definition, space velocity can be expressed mathematically as SV = Vo / V. In this expression, Vo represents the volumetric flow rate of the reactants entering the reactor and V represents the volume of the reactor itself.

### What is bed voidage?

(i) Voidage Voidage, e, is defined as the fraction of the total volume which is free space available for the flow of fluids, and thus the fractional volume of the bed occupied by solid material is (1 − ε). Depending upon the nature of the porous medium, the voidage may range from near zero to almost unity.

**How is bed porosity calculated?**

The first equation uses the total volume and the volume of the void. Porosity = (Volume of Voids / Total Volume) x 100%. The second equation uses the total volume and the volume of the solid. Porosity = ( ( Total Volume – Volume of the Solid ) / Total Volume ) x 100%.

## What is formula for calculating a volume of reactor?

It is calculated in cubic meters per sec is calculated using Reactor Volume = (Mean cell residence time*Maximum yield coefficient*Average daily influent flow rate*(Influent substrate concentration-Effluent substrate concentration))/(MLVSS*(1+(Mean cell residence time*Endogenous decay coefficient))).

**What is Voidage in fluidisation?**

### What is a Geldart?

Geldart defined four types of materials which differ by the cohesion forces between particles. An experimental apparatus containing fluidized beds of four pipe diameters and fully controlled by LabVIEW was used to perform the fluidization tests.

**What is soil porosity formula?**

A fairly straightforward formula is used as follows: Soil Porosity = ( 1 – (Bulk Density ÷ Particle Density) ) x 100. This will indicate the percentage of the soil that contains pores.

## What is Forchheimer coefficient?

While the shear forces are represented by a linear equation (Darcy equation), pressure forces are represented by a quadratic equation (Forchheimer equation). Therefore d is a linear resistance coefficient (Darcy coefficient) and f is a quadratic resistance coefficient (Forchheimer coefficient).

**What is the Ergun equation?**

The Ergun equation, derived by the Turkish chemical engineer Sabri Ergun in 1952, expresses the friction factor in a packed column as a function of the modified Reynolds number . is the void fraction ( porosity) of the bed.

### Does the Ergun equation include the pressure drop due to inertia?

On the continuum level, the second order velocity term demonstrates that the Ergun equation also includes the pressure drop due to inertia, as described by the Darcy–Forchheimer equation . The extension of the Ergun equation to fluidized beds, where the solid particles flow with the fluid, is discussed by Akgiray and Saatçı (2001).

**What is the relationship between Ergun and Kozeny-Carman equations?**

This arrangement of the Ergun equation makes clear its close relationship to the simpler Kozeny-Carman equation which describes laminar flow of fluids across packed beds via the first term on the right hand side.

## What is the value of (L′ / G′) √ (ρ g / ρ L)?

A value of (L′ / G′) √ (ρ G / ρ L) = 16 is well in excess of the normal operating range of the column (especially of a distillation column operating at reduced pressure), as seen in Figure 4.17.