Chemical Engineering:: Heat Transfer

In a packed absorption tower, if the equilibrium and operating lines are both straight lines, then the ratio, HETP/HTUOG __________ the absorption factor.

A. increases with increase in
B. is one at unity value of
C both (a) and (b)
D. neither (a) nor (b)

A 10 cm dia steam pipe, carrying steam at 180°C, is covered with an insulation (conductivity = 0.6 W/m.°C). It losses heat to the surroundings at 30°C. Assume a heat transfer co-efficient of 0.8 W/m2.°C for heat transfer from surface to the surroundings. Neglect wall resistance of the pipe and film resistance of steam. If the insulation thickness is 2 cms, the rate of heat loss from this insulated pipe will be

A. greater than that for uninsulated steam pipe.
B. less than that of the uninsulated steam pipe.
C equal to that of the uninsulated steam pipe.
D. less than the steam pipe with 5 cms insulation.

A backward feed multiple effect evaporator is better than forward feed for concentrating cold feed, because it provides

A. higher economy
B. lower capacity
C both (a) & (b)
D. lower economy

With increase in temperature, the thermal conductivity of non-metallic amorphous solids

A. decreases
B. increases
C remains constant
D. first decreases upto certain temperature and then increases

Fourier's law applies to the heat transfer by

A. convection
B. radiation
C conduction
D. all (a), (b) & (c)

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