Viscous & heat sensitive liquids are concentrated in _____________ evaporators?
A. Open pan
B. Long tube
C. Agitated film
D. None of these
Month: March 2019
In case of surface condensers, a straight line is obtained on plotting 1/U vs. ____________ on an ordinary graph paper?
In case of surface condensers, a straight line is obtained on plotting 1/U vs. ____________ on an ordinary graph paper?
A. 1/V̅ -0.8
B. V̅ -0.8
C. V̅ -2
D. 1/ V̅ -2
Viscosity of gases ______________ with increase in temperature?
Viscosity of gases ______________ with increase in temperature?
A. Increase very rapidly
B. Increase slowly
C. Decrease slowly
D. Remain unaffected
During crystallisation, formation of crystal can occur in ______________ solution only?
During crystallisation, formation of crystal can occur in ______________ solution only?
A. Saturated
B. Supersaturated
C. Under-saturated
D. All A., B. and C.
When does the heat generated by fluid friction becomes appreciable compared to the heat transferred between the fluids ?
When does the heat generated by fluid friction becomes appreciable compared to the heat transferred between the fluids ?
A. At high fluid velocity
B. At low velocity
C. When fluid flows past a smooth surface
D. None of these
Condensing film co-efficient for steam on horizontal tubes ranges from 5000 to 15000 Kcal/hr.m2.°C. Condensation of vapor is carried out inside the tube in a shell and tube heat exchanger, when the_________________?
Condensing film co-efficient for steam on horizontal tubes ranges from 5000 to 15000 Kcal/hr.m2.°C. Condensation of vapor is carried out inside the tube in a shell and tube heat exchanger, when the_________________?
A. Higher condensing film co-efficient is desired
B. Condensate is corrosive in nature
C. Lower pressure drop through the exchanger is desired
D. Temperature of the incoming vapor is very high
A cube, sphere & a thin circular plate (all having same mass and made of same material) are all heated to 300°C and allowed to cool in natural air. Which one will cool the slowest ?
A cube, sphere & a thin circular plate (all having same mass and made of same material) are all heated to 300°C and allowed to cool in natural air. Which one will cool the slowest ?
A. Cube
B. Plate
C. Sphere
D. All will cool at the same rate
A steel sphere of radius 0.1 m at 400°K is immersed in an oil at 300°K. If the centre of the sphere reaches 350°K in 20 minutes, how long will it take for a 0.05 m radius steel sphere to reach the same temperature (at the centre) under identical conditions? Assume that the conductive heat transfer co-efficient is infinitely large ?
A steel sphere of radius 0.1 m at 400°K is immersed in an oil at 300°K. If the centre of the sphere reaches 350°K in 20 minutes, how long will it take for a 0.05 m radius steel sphere to reach the same temperature (at the centre) under identical conditions? Assume that the conductive heat transfer co-efficient is infinitely large ?
A. 5 minutes
B. 10 minutes
C. 20 minutes
D. 40 minutes
Presence of a non-condensing gas in a condensing vapour___________________?
Presence of a non-condensing gas in a condensing vapour___________________?
A. Increases the rate of condensation
B. Decreases thermal resistance
C. Is desirable to increase the film co-efficient
D. None of these
The critical radius of insulation for cylindrical pipe is (where, hi = heat transfer coefficient at inside of the pipe) ?
The critical radius of insulation for cylindrical pipe is (where, hi = heat transfer coefficient at inside of the pipe) ?
A. K/h0
B. 2K/h0
C. hi/K
D. 2hi/K