Viscous & heat sensitive liquids are concentrated in _____________ evaporators?

Related Mcqs:

1. Which of the following forced convection heat transfer equation accounts for the liquid viscosity effect for viscous liquids ?

   A. Dittus-Boelter equation
   B. Sieder-Tate equation
   C. Nusselt equation
   D. None of these

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

   A. Long vertical evaporator
   B. Horizontal tube evaporator
   C. Agitated film evaporator
   D. Calandria vertical tube evaporator

3. Heat sensitive materials can be concentrated in an evaporator employing_______________?

   A. Vacuum
   B. High pressure
   C. High residence time
   D. None of these

4. Fruit juice (a heat sensitive material) can be concentrated in a ____________ evaporator?

   A. Long tube
   B. Falling film
   C. High pressure
   D. None of these

5. Open pan evaporators are preferred to be used, when the solution to be concentrated is_________________?

   A. Scaling
   B. Highly viscous
   C. Corrosive
   D. Salty

6. Forced circulation evaporators are normally used for concentrating liquids having ___________________?

   A. Scaling characteristics
   B. High viscosity
   C. Both A. & B.
   D. Neither A. nor B.

7. Air is to be heated by condensing steam. Two heat exchangers are available (i) a shell and tube heat exchanger and (ii) a finned tube heat exchanger. Tube side heat transfer area are equal in both the cases. The recommended arrangement is________________?

   A. Finned tube heat exchanger with air inside and steam outside
   B. Finned tube heat exchanger with air outside and steam inside
   C. Shell and tube heat exchanger with air inside tubes and steam on shell side
   D. Shell and tube heat exchanger with air on shell side and steam inside tubes

8. 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 un-insulated steam pipe
   B. Less than that of the un-insulated steam pipe
   C. Equal to that of the un-insulated steam pipe
   D. Less than the steam pipe with 5 cms insulation

9. Extended heat transfer surface like fins are used to increase the heat transfer rate. Fin efficiency is defined as the ratio of heat transferred across the fin surface to the theoretical heat transfer across an equal area held at the________________?

   A. Surrounding temperature
   B. Average temperature of the fin
   C. Temperature of the fin end
   D. Constant temperature equal to that of the base

10. LMTD for evaporators & condensers for a given terminal parameters & set of conditions for counter-flow is equal to that for parallel flow. In such heat exchangers, with one of the fluids condensing or evaporating, the surface area required is the least in the ______________ flow?

    A. Parallel
    B. Mixed
    C. Counter flow
    D. Same in either A , B. or C.