Chemical Engineering - Heat Transfer

36.
The advantage of backward feed multiple effect evaporators over forward feed units is that
heat sensitive material can be handled.
there is no additional cost of pumping.
most concentrated liquid is at highest temperature.
equal heat transfer co-efficients exist in various effects.
Answer: Option
Explanation:
No answer description is available. Let's discuss.

37.
Which of the following is the most controlling factor for the rate of bubble detachment from the hot solid surface ?
Liquid density
Liquid viscosity
Hot surface temperature
Interfacial tension
Answer: Option
Explanation:
No answer description is available. Let's discuss.

38.
Which characteristic of a fluid is not important in deciding its route in a shell and tube heat exchanger ?
Corrosiveness
Fouling characteristic
Viscosity
None of these
Answer: Option
Explanation:
No answer description is available. Let's discuss.

39.
Thermal conductivities of most of the liquids __________ with rise in temperature.
increases
decreases
remains unchanged
may increase or decrease; depends on the liquid
Answer: Option
Explanation:
No answer description is available. Let's discuss.

40.
A metal ball of radius 0.1 m at a uniform temperature of 90°C is left in air at 30°C. The density and the specific heat of the metal are 3000 kg/m3 and 0.4 kJ/kg.K respectively. The heat transfer co-efficient is 50 W/m2.K Neglecting the temperature gradients inside the ball, the time taken (in hours) for the ball to cool to 60°C is
555
55.5
0.55
0.15
Answer: Option
Explanation:
No answer description is available. Let's discuss.