Heat Transfer Operations Practice Test 9

1. A plate condenser is usually designed to be kept vertical. How would the condensation coefficient change if due to site constraints it now has to be kept at an angle of 30o to the horizontal?

16% reduction in condensation coefficient

84% reduction in condensation coefficient

1.53% reduction in condensation coefficient

50% reduction in condensation coefficient

2. The free energy ΔG required to release unit molal quantity of this moisture is given by
ΔG = – RT Ln(Ψ), for an isothermal, reversible process without change of composition.

False

True

3. The moist feed is fed in at the _________ end of a rotary dryer and the material progresses to the ________ end, where it gets discharged.

Lower and Lower

Upper and Upper

Upper and Lower

Lower and Upper

4. For a fluidised bed dryer, which one of the following is correct?

Wet hot air is passed as the fluid on a bed of dry material

Hot fluid outside the tube containing particles

Dry hot air is passed as the fluid on a packed bed of wet material

Dry hot air is passed as the fluid on a bed of wet material

5. What is the relation between the averaged heat transfer coefficient over the entire condenser length vs its value at a point x?

\(\frac{h_{avg}}{h_x}\) =4

\(\frac{h_{avg}}{h_x} =\frac{3}{4} \)

\(\frac{h_{avg}}{h_x} =\frac{4}{3} \)

\(\frac{h_{avg}}{h_x} =\frac{2}{3}\)

6. Any kind of material possible such as coarse ones or granular or even powdery substance can be dried by circulating in a screen conveyor dryer without the requirement of any prior-treatment or loss in feed material.

True

False

7. Which dryer has the following description – ‘a liquid containing dissolved solids or slurry carrying suspended solids forms a thin layer on the outside surface of a large rotating vessel’?

Drum dryer

Rotary dryer

Agitated dryer

Furnace dryer

8. For a single drum, the thickness of the film can be controlled by ___________ and in case of a double drum setup the thickness of product here can be controlled by ______________

An adjustable scraping blade, the gap between the drums

The fins, the drums

The drums, the fins

The Gap between the drums, an adjustable scraping blade

9. Which one of the following is the correct temperature time plot of continuous steady state drying?

10. Which one of the following correctly represents the drying curve?