Process Equipment and Plant Design
Fouling factor must be included in the calculation of over all design heat transfer coefficient, when the liquid

Is of high specific gravity
Containing suspended solids flows at low velocity
Containing suspended solids flows at high velocity
Is highly viscous

ANSWER DOWNLOAD EXAMIANS APP

Process Equipment and Plant Design
In a shell and tube heat exchanger, triangular pitch arrangement as compared to square pitch arrangement

Facilitates easier shell side cleaning; hence is more suitable for handling high dirt factor shell side fluid
Creates relatively lower turbulence on the shell side resulting in lower shell side heat transfer co-efficient
Can accomodate less number of tubes for a given shell diameter
Results in higher shell side pressure drop

ANSWER DOWNLOAD EXAMIANS APP