Heat Transfer MCQs

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.

The purpose of providing a 'catchall' in the vapor line of an evaporator is to

A dilute aqueous solution is to be concentrated in an evaporator system. High pressure steam is available. Multiple effect evaporator system is employed, because

A metal ball of radius 0.1 m at a uniform temperature of 90°C is left in air at 30°C. The density and the specific heat of the metal are 3000 kg/m3 and 0.4 kJ/kg.K respectively. The heat transfer co-efficient is 50 W/m2.K Neglecting the temperature gradients inside the ball, the time taken (in hours) for the ball to cool to 60°C is

A concentric double pipe heat exchanger as compared to the shell and tube heat exchanger for the same heat load requires

Removal of __________ heat is involved in the condensation of a vapor under saturated conditions.

A hot body will radiate heat most rapidly, if its surface is

Maximum water velocity in tubes of a 1-2 shell and tube heat exchanger may be around __________ metres/second.

At what value of Prandtl number, the hydrodynamic and thermal boundary layers are identical?