Process Equipment and Plant Design
In a double pipe (concentric) heat exchanger, the hydraulic radius for heat transfer (for a fluid flowing through the annulus) would be

D₂ - D₁ (D₁ and D₂ are I.D. of inner and outer pipes respectively)
Less than that for fluid flow
Same as that for fluid flow
More than that for fluid flow

ANSWER DOWNLOAD EXAMIANS APP

Process Equipment and Plant Design
Practical dividing line between a ductile and brittle materials is suggested, when the ultimate elongation is about 5%. Generally, larger the knuckle radius, stronger is the corner torus section of a head. The knuckle radius provided should be less than __________ of the head.

3 times the thickness
6% of I.D.
Either A or B, whichever is smaller
Either A or B, whichever is larger

ANSWER DOWNLOAD EXAMIANS APP