A _____________ surface has the maximum thermal emissivity out of the following ?

Related Mcqs:

Heat flux increases with temperature drop beyond the Leiden frost point in the plot of heat flux vs. temperature drop for a boiling liquid, because___________________?

A. Convection becomes important B. Conduction becomes important C. Radiation becomes important D. Sub-cooled boiling occurs...

Radiator of an automobile engine is a ______________ type of heat exchanger?

A. Co-current B. Cross-current C. Counter-current D. Direct contact...

Fqra cold viscous feed, backward feed gives _____________ than forward feed?

A. A higher capacity B. A lower capacity C. Lower economy D. None of these...

Kirchoff’s law is applicable to________________?

A. Monochromatic radiation only B. Total radiation only C. Both A. and B. D. Only volumes and not to surfaces...

A 10 cm dia steam pipe, carrying steam at 180°C, is covered with an insulation (conductivity = 0.6 W/m.°C). It losses heat to the surroundings at 30°C. Assume a heat transfer co-efficient of 0.8 W/m2.°C for heat transfer from surface to the surroundings. Neglect wall resistance of the pipe and film resistance of steam. If the insulation thickness is 2 cms, the rate of heat loss from this insulated pipe will be__________________?

A. Greater than that for un-insulated steam pipe B. Less than that of the un-insulated steam pipe C. Equal to that of the un-insulated steam pipe D. Less than the steam pipe with 5 cms insulation...