Chemical Heat Transfer
In regenerative air preheater (as practised in heating of coke ovens), the heat is transferred_________________?

A. Through a metallic wall
B. By direct contact of hot flue gas with air
C. By heating an intermediate material (like chequor bricks) and then heating the air from this hot material
D. None of these

Steam condensate is recovered by steam traps and recycled for use as boiler feed water, because of its low___________________?

A. Hardness
B. Dissolved solids content
C. Suspended solids content
D. All A., B. and C.

For what value of Prandtl number, the Col-burn analogy is valid ?

A. 0.06 to 120
B. 0.6 to 120
C. 1 to 103
D. 1 to 50

For specified tube outside diameter, higher BWG means higher___________________?

A. Tube thickness
B. Cross-sectional area
C. Weight per unit length
D. None of these

It is not preferable to use superheated steam in evaporators, because of its very_________________?

A. High temperature
B. High pressure
C. Low film co-efficient
D. None of these