Related Mcqs:

1. The actual temperature drop across the heating surface of an evaporator depends on the_______________?

   A. Liquid depth over the heating surface
   B. Solution being evaporated
   C. Pressure difference between the steam chest and the vapor space above the boiling liquid
   D. All A., B. and C.

2. 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

3. Heat flux increases with temperature drop beyond the Leiden frost point in the plot of heat flux vs. temperature drop for a boiling liquid, because___________________?

   A. Convection becomes important
   B. Conduction becomes important
   C. Radiation becomes important
   D. Sub-cooled boiling occurs

4. For concentrating an aqueous solution of a material like anhydrous Na2SO4, whose solubility decreases with rise in temperature, the most suitable evaporator is a _______________ evaporator?

   A. High pressure
   B. Vacuum
   C. Backward feed
   D. None of these

5. A composite flat wall of a furnace is made of two materials ‘A’ and ‘B’. The thermal conductivity of ‘A’ is twice of that of material ‘B’, while the thickness of layer of ‘A’ is half that of B. If the temperature at the two sides of the wall are 400 and 1200°K, then the temperature drop (in °K) across the layer of material ‘A’ is________________?

   A. 125
   B. 133
   C. 150
   D. 160

6. A wall has two layers of materials A and B; each made of a different material. Both the layers have the same thickness. The thermal conductivity of material A is twice that of B. Under the equilibrium, the temperature difference across the wall is 36°C. The temperature difference across the layer A is ______________ °C?

   A. 6
   B. 12
   C. 18
   D. 24

7. The radiation heat flux from a heating element at a temperature of 800°C, in a furnace maintained at 300°C is 8 kW/m2. The flux, when the element temperature is increased to 1000°C for the same furnace temperature is_____________________?

   A. 11.2 kW/m2
   B. 12.0 kW/m2
   C. 14.6 kW/m2
   D. 16.5 kW/m2

8. In a single evaporator system, the steam economy ________________ by creating vacuum in the evaporator?

   A. Increases
   B. Decreases
   C. Remain constant
   D. May increase or decrease, depends on the vacuum

9. It is desired to concentrate a 20% salt solution (20 kg of salt in 100 kg of solution) to a 30% salt solution in an evaporator. Consider a feed of 300 kg/min at 30°C. The boiling point of the solution is 110°C, the latent heat of vaporisation is 2100 kJ/kg and the specific heat of the solution is 4 kJ/kg.K. The rate at which the heat has to be supplied in (kJ/min) to the evaporator is____________________?

   A. 3.06 × 105
   B. 6.12 × 105
   C. 7.24 × 105
   D. 9.08 × 105

10. Steam consumption in kg/hr in case of an evaporator is given by (where, C & E are capacity the economy of the evaporator respectively) ?

    A. C/E
    B. E/C
    C. CE
    D. 1/CE