Truefalse Check true or false as appropriate and explain you

True/false. Check true or false, as appropriate, and explain your answer.

(b) Flow around a sphere is laminar for a Reynolds number of 1,000.

(e) The Burke-Plummer and Karmen-Kozeny equations are limiting forms of the Ergun equation, for low and high values of the Reynolds number, respectively.

(f) The Ergun equation applies for both laminar and turbulent flow.

Solution

d)False...

The flow around a sphere is laminar for Re<1

and becomes turbulent for Re>1000

e) False.

Blake-Kozeny equation or as Kozeny-Carman equation is valid for NRe_PM less than about 10.

Burke-Plummer equation, valid for NRe_PM greater than 1000

Ergun just showed that if we add the friction factor term,

f_PM = 1.75 + 150 / NRe_PM

the transition regions data are predicted reasonably well.

f) The Ergun equation combines both the laminar and turbulent components of the pressure loss across a packed bed. In laminar flow conditions the first component of the equation dominates with the Ergun equation essentially reducing to the Carman-Koreny equation