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.Management Sciences
Category: Chemical Heat Transfer
The ratio of kinematic viscosity to thermal diffusivity is called the _______________ number?
A. Peclet
B. Prandtl
C. Stanton
D. Nusselt
Dittus-Boelter equation used for the determination of heat transfer co-efficient is valid ___________________?
A. For fluids in laminar flow
B. For fluids in turbulent flow
C. When Grashoff number is very important
D. For liquid metals
Viscous & heat sensitive liquids are concentrated in _____________ evaporators?
A. Open pan
B. Long tube
C. Agitated film
D. None of these
Critical value of the _____________ number governs the transition from laminar to turbulent flow in free convection heat transfer?
A. Grashoff
B. Reynolds
C. Both ‘a’ & ‘b’
D. Prandtl & Grashoff
The rate of heat transfer through a pipe wall is given by, q = 2π k (Ti – T0)/ln (ri/r0). For cylinder of very thin wall, q can be approximated by__________________?
A. q = [2π k (Ti + T0)/2]/ln (ri/r0)
B. q = 2π ri k (Ti – T0)/(r0/ri)
C. q = 2π k (Ti – T0)/(r0/ri)
D. q = 2π k (Ti – T0)/[(r0 + ri)/2]
Economy of a multiple effect evaporator is not influenced much by the_______________________?
A. Boiling point elevations
B. Temperature of the feed
C. Rate of heat transfer
D. Ratio of the weight of the thin liquor to thick liquor
Circulation pump is located below the evaporator to___________________?
A. Avoid cavitation
B. Avoid frequent priming
C. Create more suction head
D. None of these
Which of the following is not used as a medium for high temperature heating ?
A. Dowtherm
B. Mercury
C. Liquid metal (e.g. molten sodium)
D. Fused salts (e.g., an eutectic mixture of 53% KNO3, 40% NaNO2and 7% NaNO3)
_____________ heat exchanger is the most suitable, when the temperature of shell side fluid is much higher than that of tube side?
A. Single pass, fixed tube sheet
B. U-tube
C. Three pass, fixed tube sheet
D. None of these
In a 1-1 concurrent heat exchanger, if the tube side fluid outlet temperature is equal to the shell side fluid outlet temperature, then the LMTD is_________________?
A. ∞
B. 0
C. Equal to the difference between hot and cold fluids inlet temperature
D. Equal to the difference between hot fluid inlet temperature and cold fluid outlet temperature
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