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.Management Sciences
Category: Chemical Heat Transfer
The equation, (NSt × N2/3 Pr) = f/2, is the ____________ analogy ?
A. Colburn
B. Reynolds
C. Prandtl
D. None of these
Which of the following has the lowest Prandtl number ?
A. Molten sodium (a coolant used in fast breeder reactor)
B. Water
C. Transformer oil
D. Dilute H2SO4
Terminal point temperature differences between fluids in case of a heat exchanger is termed as__________________?
A. Approach
B. Log mean temperature difference
C. Arithmetic mean temperature difference
D. Geometric mean temperature difference
The Sieder-Tate correlation for heat transfer in turbulent flow in pipe gives Nu α Re0.8, where, Nu is the Nusselt number and Re is the Reynolds number for the flow. Assuming that this relation is valid, the heat transfer co-efficient varies with the pipe diameter D. as _________________?
A. D-1.8
B. D-0.2
C. D0.2
D. D1.8
Analogy between mass and heat transfer is not applicable in case of____________________?
A. Same velocity profile or equal eddy diffusivities
B. Thermal or pressure mass diffusion
C. Viscous heating or chemical reaction
D. Both B. and C.
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
At constant temperature, the thermal conductivities of gases _____________ with rise in pressure?
A. Decrease
B. Increase
C. Remain unchanged
D. May increase or decrease; depends on the pressure
Rate of heat transfer by vaporisation from pools of water is affected by the ____________________?
A. Nature of heating surface and distribution of bubbles
B. Surface tension of water
C. Viscosity of water
D. All A., B. and C.
If heat transfer rate varies with the time, it is termed as__________________?
A. Forced convection
B. Steady state conduction
C. Monochromatic radiation
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
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