1497. Low thermal conductivity of heat insulating materials is due to its
Dense structure
High proportion of air space
High specific heat
None of these
✅ The correct answer is option B.
1499. Choose the most important factor on which the heat conducted through a wall in a unit time will depend on?
Thickness of the wall
Area of the wall perpendicular to heat flow
Material of the wall
Temperature difference between the two surfaces of the wall
✅ The correct answer is option D.
1501. Solid angle subtended by the finite surface at the radiating element is
Called the view factor
Called the angle of vision
Proportional to the square of the distance between surfaces
Expressed in terms of radians
✅ The correct answer is option B.
1503. Vibrations in the tubes of a shell and tube heat exchanger is induced due to the
Flow of fluid on the tube and shell sides
Oscillations in the flow of shell/tube sides fluid
Vibrations transmitted through piping and/or supports due to external reasons
All of the above
✅ The correct answer is option D.
1506. Which one gives the monochromatic emissive power for black body radiation?
Planck’s law
Kirchhoffs law
Wien’s law
Stefan-Boltzman law
✅ The correct answer is option A.
1509. jH factor for heat transfer depends upon the __________ number.
Biot
Nusselt
Reynolds
Prandtl
✅ The correct answer is option C.
1512. Fresh orange juice contains 12% (by weight) solids and the rest water 90% of the fresh juice is sent to an evaporator to remove water and subsequently mixed with the remaining 10% of fresh juice. The resultant product contains 40% solids. The kg of water removed from 1 kg fresh juice is
0.4
0.5
0.6
0.7
✅ The correct answer is option D.
1515. The characteristic dimensionless groups for heat transfer to a fluid flowing through a pipe in laminar flow are
Re.Gz
Nu, Pr
Nu, Pr, Re
Nu, Gz
✅ The correct answer is option D.
1518. Open pan evaporators are preferred to be used, when the solution to be concentrated is
Scaling
Highly viscous
Corrosive
Salty
✅ The correct answer is option B.
1521. Baffle spacing
Is not the same as baffle pitch
Should be less than one fifth the diameter of the shell
Should be less than the inside diameter of the shell
None of these
✅ The correct answer is option C.