Question

Statement 1: Where Pg is power for a gassed system and Po is power for an ungassed system, Pg/Po is _____

Statement 2: Na stands for _____

(a) < 1, aeration number

(b) > 1, aeration number

(c) < 1, consistency index

(d) > 1, consistency index

I had been asked this question by my college professor while I was bunking the class.

I would like to ask this question from Unit Operations topic in division Sedimentation and Centrifuge, Mixing, Size Reduction and Separation and Material Handling and Transportation of Food Engineering

Answer 1

Correct choice is (a) < 1, aeration number

The best I can explain: Power required for an ungassed system Po is more than that required for a gassed system Pg. This is because when gas is sent into the fluid via a nozzle, the density of the fluid near the impeller decreases and hence the power required for it is lesser.