A. The heat transfer rate is low in view of the large temperature drop
B. It is difficult to maintain
C. It is not economic
D. None of these
Related Mcqs:
- 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 - In case of _______________ boiling, the liquid temperature is below the saturation temperature and the boiling takes place in the vicinity of the heated surface?
A. Nucleate
B. Local
C. Pool
D. Saturated - Boiling point elevation for a strong and concentrated solution is found by Duhring’s rule, which states that at the same pressure, the boiling point of a solution is a linear function of the _______________ of pure water?
A. Boiling point
B. Dynamic viscosity
C. Kinematic viscosity
D. Density - Boiling of milk in an open vessel is an example of ______________ boiling?
A. Film
B. Sub-cooled
C. Saturated nucleate
D. None of these - When vaporisation takes place through a blanketting film of gas, the phenomenon is termed as ___________________ boiling?
A. Pool
B. Nucleate
C. Transition
D. Film - Film boiling occurs at ________________ pressure?
A. Atmospheric
B. Sub-atmospheric
C. Negative
D. Very high - The film co-efficient is decreased due to the presence of non-condensing gases in the vapors. The film co-efficient of superheated vapor as compared to that of saturated vapor is___________________?
A. More
B. Less
C. Some
D. Either more or less; depends on the nature of vapor - If h1 = inner film co-efficient and /h2 = outer film co-efficient, then the overall heat transfer co-efficient is________________?
A. Always less than h1
B. Always between h1 and h2
C. Always higher than h2
D. Dependent on metal resistance - The local surface conductance for laminar film condensation on vertical surface is (where, t = film thickness) _________________?
A. ∝ t
B. ∝ 1/t
C. ∝ √t
D. Independent of ‘t’ - The film thickness for laminar film condensation on vertical surface _____________ from top to bottom?
A. Cumulatively increases
B. Cumulatively decreases
C. Remain constant
D. And the surface conductance increase
