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.Management Sciences
Category: Chemical Heat Transfer
For what value of Prandtl number, the Col-burn analogy is valid ?
A. 0.06 to 120
B. 0.6 to 120
C. 1 to 103
D. 1 to 50
Three solid objects of the same material and of equal mass-a sphere, a cylinder (length = diameter) and a cube are at 500°C initially. These are dropped in a quenching bath containing a large volume of cooling oil each attaining the bath temperature eventually. The time required for 90% change in temperature is the smallest for_________________?
A. Cube
B. Cylinder
C. Sphere
D. Equal for all the three
Overall heat transfer co-efficient for cooling of hydrocarbons by water is about_________________?
A. 50 -100 Kcal/hr.m2.°C
B. 50 -100 W/m2.°K
C. 50 -100 BTU/hr. ft.2°F
D. 1000 – 1500 BTU/hr. ft.2°F
Latent heat absorbed by 1 lb of water at 212°F, when it is changed to steam at 212°F, may be around ______________ BTU?
A. 180
B. 970
C. 3.97
D. None of these
The ratio of total radiating power to the absorptivity of the body depends upon the _____________ as per Kirchoff‟s law?
A. Wavelength of radiation
B. Nature of the body
C. Temperature of the body
D. None of these
The steam ejector is used to__________________?
A. Remove condensate from the steam pipelines
B. Create vacuum
C. Superheat the steam
D. None of these
The main purpose of providing fins on heat transfer surface is to increase the_________________?
A. Temperature gradient
B. Mechanical strength of the equipment
C. Heat transfer area
D. Heat transfer co-efficient
Controlling heat transfer film co-efficient is the one, which offers ______________ resistance to heat transfer?
A. No
B. The least
C. The largest
D. Lower
The rate of emission of radiation by a body does not depend upon the__________________?
A. Wavelength of radiation
B. Surface temperature of the body
C. Nature of the surface
D. Shape and porosity of the body
Wavelength corresponding to the maximum energy is inversely proportional to the absolute temperature. This is ________________ law?
A. Stefan’s
B. Dalton’s
C. Wien’s
D. Kirchoff’s
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