1638. At constant temperature, the thermal conductivities of gases __________ with rise in pressure.
Decrease
Increase
Remain unchanged
May increase or decrease; depends on the pressure
✅ The correct answer is option A.
1641. In counter flow compared to parallel flow,
LMTD is greater
Less surface area is required for a given heat transfer rate
Both A and B
More surface area is required for a given heat transfer rate
✅ The correct answer is option C.
1644. Which of the following has the highest thermal conductivity?
Brick
Air
Water
Silver
✅ The correct answer is option D.
1647. Removal of __________ heat is involved in the condensation of a vapor under saturated conditions.
Super
Sensible
Latent
Both B & C
✅ The correct answer is option B.
1650. For flow over a flat plate, the ratio of thermal boundary layer thickness, ‘xt’ and hydrodynamic boundary layer thickness ‘x’ is equal to (where, NPr = Prandtl number)
NPr
NPr1/3
NPr-1
NPr-1/3
✅ The correct answer is option B.
1652. With increase in temperature, the thermal conductivity of most liquids
Increases
Decreases
Remains same
First increases upto a certain temperature and then becomes constant
✅ The correct answer is option B.
1654. Heat flux through several resistances in series in analogous to the current flowing through several
Resistances in parallel
Capacitors in series
Resistances in series
None of these
✅ The correct answer is option C.
1656. The equation, (NSt x N2/3Pr) = f/2, is the __________ analogy.
Colburn
Reynolds
Prandtl
None of these
✅ The correct answer is option A.
1658. An equipment which converts the latent or sensible heat of one fluid into the latent heat of vaporisation of another, is called a
Boiler
Heat exchanger
Recuperator
Regenerator
✅ The correct answer is option B.
1660. The equation, Nst = f/2, is the __________ analogy.
Colburn
Reynolds
Prandtl
None of these
✅ The correct answer is option B.