Heat and Mass Transfer
Which of the following would lead to a reduction in thermal resistance?

All of these
In convection, stirring of the fluid and cleaning the heating surface.
In radiation, increasing the temperature and reducing the emissivity.
In conduction, reduction in the thickness of the material and an increase in thermal conductivity.

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Heat and Mass Transfer
The time constant of a thermocouple is

The time taken to attain 50% of the value of initial temperature difference
The time taken to attain the final temperature to be measured
The time taken to attain 63.2% of the value of initial temperature difference
Determined by the time taken to reach 100°C from 0°C

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Heat and Mass Transfer
A steam pipe is to be insulated by two insulating materials put over each other. For best results

Whether to put inferior OIL over pipe or the better one would depend on steam temperature
Better insulation should be put over pipe and better one over it
Both may be put in any order
Inferior insulation should be put over pipe and better one over it

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