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March 2019

The heat transfer by radiation from a mild steel surface is to be reduced by reducing the emissivity of the surface. This can be best achieved by__________________?

Chemical Heat Transfer /
The heat transfer by radiation from a mild steel surface is to be reduced by reducing the emissivity of the surface. This can be best achieved by__________________?

A. Painting the surface black
B. Painting the surface white (with aluminium paint)
C. Giving the surface a mirror finish
D. Roughening the surface

The heat transfer by radiation from a mild steel surface is to be reduced by reducing the emissivity of the surface. This can be best achieved by__________________? Read More »

Chemical Heat Transfer

As per Kirchoff‟s law, the ratio of the total radiating power to the absorptivity of a body depends on the_______________?

Chemical Heat Transfer /
As per Kirchoff‟s law, the ratio of the total radiating power to the absorptivity of a body depends on the_______________?

A. Temperature of the body only
B. Wavelength of monochromatic radiation
C. Both A. and B.
D. Nature of material of body

As per Kirchoff‟s law, the ratio of the total radiating power to the absorptivity of a body depends on the_______________? Read More »

Chemical Heat Transfer

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________________?

Chemical Heat Transfer /
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________________?

A. Surrounding temperature
B. Average temperature of the fin
C. Temperature of the fin end
D. Constant temperature equal to that of the base

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________________? Read More »

Chemical Heat Transfer

The actual temperature drop across the heating surface in an evaporator depends on the_________________?

Chemical Heat Transfer /
The actual temperature drop across the heating surface in an evaporator depends on the_________________?

A. Feed
B. Depth of liquid over heating surface
C. Pressure difference between steam chest and vapour space
D. All A., B. and C.

The actual temperature drop across the heating surface in an evaporator depends on the_________________? Read More »

Chemical Heat Transfer