Heat Transfer
The variation of thermal conductivity of a metal with temperature is often correlated using an expression of the form K = K₀ + at. where, K is the thermal conductivity and T is the temperature (in °K). The units of 'a' in SI system will be

W/m.k²
W/m.k
W/m
None, A is just a number

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Heat Transfer
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

Greater than that for uninsulated steam pipe
Less than the steam pipe with 5 cms insulation
Equal to that of the uninsulated steam pipe
Less than that of the uninsulated steam pipe

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