Heat Transfer

141. For what value of Prandtl number, St = f/2?

1. 1.5
2. 1
3. > 1
4. < 1

View answer

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

1. 0.06 to 120
2. 0.6 to 120
3. 1 to 103
4. 1 to 50

View answer

143. Forced circulation evaporators are normally used for concentrating liquids having

1. Scaling characteristics
2. High viscosity
3. Both (A) & (B)
4. Neither (A) nor (B)

View answer

144. Forced circulation evaporators are useful for the concentration of viscous, salting and scale forming liquors. Which of the following is a forced circulation evaporator?

1. Long vertical evaporator
2. Horizontal tube evaporator
3. Agitated film evaporator
4. Calandria vertical tube evaporator

View answer

145. Fouling factor

1. Is a dimensionless quantity
2. Does not provide a safety factor for design
3. Accounts for additional resistances to heat flow
4. None of these

View answer

146. Fouling factor for a heat exchanger is given by (where, U₁ = heat transfer co-efficient of dirty surface U₂ = heat transfer co-efficient of clean surface).

1. U₁ - U₂
2. 1/U₁ - 1/U₂
3. 1/U₂ - 1/U₁
4. U₂ - U₁

View answer

147. Fourier's law applies to the heat transfer by

1. Convection
2. Radiation
3. Conduction
4. All (A), (B) & (C)

View answer

148. Fourier's law of heat conduction applies to _________ surfaces.

1. Isothermal
2. Non-isothermal
3. Both (A) and (B)
4. Neither (A) and (B)

View answer

149. Fqra cold viscous feed, backward feed gives _________ than forward feed.

1. A higher capacity
2. A lower capacity
3. Lower economy
4. None of these

View answer

150. Fresh orange juice contains 12% (by weight) solids and the rest water 90% of the fresh juice is sent to an evaporator to remove water and subsequently mixed with the remaining 10% of fresh juice. The resultant product contains 40% solids. The kg of water removed from 1 kg fresh juice is

1. 0.4
2. 0.5
3. 0.6
4. 0.7

View answer