For small temperature difference, the heat transfer rate as per Newton’s law of cooling is proportional to (where, Δt = excess temperature) ?
A. Δt
B. Δt2
C. Δt3
D. √(Δt)
Month: March 2019
Overall heat transfer co-efficient for cooling of hydrocarbons by water is about_________________?
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
Intermittent tube cleaning is possible to be done in case of a _____________ evaporator?
Intermittent tube cleaning is possible to be done in case of a _____________ evaporator?
A. Basket type
B. Horizontal tube
C. Calandria
D. None of these
In case of vertical tube evaporator, with increase in liquor level, the overall heat transfer co-efficient______________?
In case of vertical tube evaporator, with increase in liquor level, the overall heat transfer co-efficient______________?
A. Increases
B. Decreases
C. Is not affected
D. May increase or decrease; depends on the feed
In evaporators, lowering the feed temperature_______________?
In evaporators, lowering the feed temperature_______________?
A. Increases the heating area required
B. Reduces the economy
C. Both A. and B.
D. Decreases the heating area required
Shell side pressure drop in a shell and tube heat exchanger does not depend upon the_________________?
Shell side pressure drop in a shell and tube heat exchanger does not depend upon the_________________?
A. Baffle spacing & shell diameter
B. Tube diameter & pitch
C. Viscosity, density & mass velocity of shell side fluid
D. None of these
The most conducive surface for dropwise condensation to occur is the _____________ surface?
The most conducive surface for dropwise condensation to occur is the _____________ surface?
A. Coated
B. Oily
C. Glazed & polished
D. Smooth
Out of 100 kcal/second of incident radiant energy on the surface of a thermally transparent body, 300 kcal/second is reflected back. If the transmissivity of the body is 0.25, the emissivity of the surface will be_________________?
Out of 100 kcal/second of incident radiant energy on the surface of a thermally transparent body, 300 kcal/second is reflected back. If the transmissivity of the body is 0.25, the emissivity of the surface will be_________________?
A. 0.35
B. 0.45
C. 0.55
D. 0.85
The critical radius of insulation for a spherical shell is (where, K = thermal conductivity of insulating material h0 = heat transfer coefficient at the outer surface) ?
The critical radius of insulation for a spherical shell is (where, K = thermal conductivity of insulating material h0 = heat transfer coefficient at the outer surface) ?
A. K/h0
B. 2K/h0
C. h0/K
D. h0/2K
Analogy between mass and heat transfer is not applicable in case of____________________?
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.