1350. Mode of heat transfer in which the fluid moves under the influence of changes in fluid pressure produced by external work is called
Radiation
Natural convection
Forced convection
Conduction
✅ The correct answer is option C.
1352. Fourier’s law of heat conduction applies to __________ surfaces.
Isothermal
Non-isothermal
Both A and B
Neither A and B
✅ The correct answer is option C.
1354. In case of a multipass shell and tube heat exchanger, providing a baffle on the shell side __________ the heat transfer rate.
Increases
Decreases
Does not affect
May increase or decrease, depends on the type of baffle
✅ The correct answer is option A.
1356. The rate of heat transfer from a vertical plate by natural convection depends upon the temperature differences (ΔT) between wall and outside bulk. The proportionality is given as
(ΔT)1/4
(ΔT)1/2
(ΔT)5/4
(ΔT)3/4
✅ The correct answer is option D.
1358. 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.
High pressure
Vacuum
Backward feed
None of these
✅ The correct answer is option B.
1361. Thermal conductivity of a conducting solid material depends upon its
Temperature
Porosity
Both A & B
Neither A nor B
✅ The correct answer is option C.
1364. The number of kg vaporised per kg of steam fed to the evaporator is defined as
Capacity
Rate of evaporation
Economy
Rate of vaporisation
✅ The correct answer is option C.
1367. With increase in temperature, the thermal conductivity of steel
Increases
Decreases
Remains unchanged
Increases exponentially
✅ The correct answer is option B.
1370. For a given ambient air temperature with increase in the thickness of insulation of a hot cylinderical pipe, the rate of heat loss from the surface would
Decrease
Increase
First decrease and then increase
First increase and then decrease
✅ The correct answer is option D.
1335. Vacuum is generally maintained in the vapour space of an evaporator mainly to
Get economical temperature difference by using moderate pressure steam
Facilitate forward feeding in multiple effect evaporation
Concentrate heat sensitive materials
Achieve very high concentration of the final product
✅ The correct answer is option A.