Chemical Heat Transfer | Test For NTS PPSC FPSC, TEST

Pick out the wrong statement/

A. The emissivity of a surface decreases, if it gets corroded by atmospheric environment
B. The emissivity of a surface increases with increase in surface roughness
C. The emissivity of a polished surface is quite low
D. The emissivity of a non-metallic surface decreases with increase in the temperature

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Category: Chemical Heat Transfer

Boiling point of a solution according to Duhring’s rule is a linear function of the _____________ of water?

Three materials A, B and C of equal thickness and of thermal conductivity of 20, 40 & 60 kcal/hr. m. °C respectively are joined together. The temperature outside of A and C are 30°C and 100°C respectively. The interface between B and C will be at a temperature of ____________ °C?

Absorptivity of a perfect black body is unity. Which of the following has maximum absorptivity ?

For the same heat load and mass flow rate in the tube side of a shell and tube heat exchanger, one may use multipass on the tube side, because it__________________?

The thickness of condensate layer in filmwise condensation depends on the__________________?

Agitated film evaporator is suitable for concentrating _____________ liquids?

In case of a vertical tube evaporator, with increase in the liquor level, the___________________?

Absorptivity and reflectivity of a perfect black body are respectively _______________?

Extended heat transfer surface like fins are used to increase the heat transfer rate. Fin efficiency is defined as the ratio of heat transferred across the fin surface to the theoretical heat transfer across an equal area held at the________________?

Pick out the wrong statement/