Project ForgeHeat Transfer
Conduction
GATE 2012
Medium
For heat transfer across a solid-fluid interface, which one of the following statements is NOT true when the Biot number is very small compared to 1?
- AConduction resistance in the solid is very small compared to convection resistance in the fluid
- BTemperature profile within the solid is nearly uniform
- CTemperature drop in the fluid is significant
- Temperature drop in the solid is significant
Explanation
Bi=hLc/ksolid≪1 means the solid's internal conduction resistance is negligible compared to the external convective resistance — so the solid has a nearly uniform temperature (lumped capacitance is valid) and almost the entire temperature drop occurs in the fluid, not the solid. The statement claiming a significant temperature drop IN THE SOLID is the one that is NOT true.
Source: GATE CH 2012 (2012)
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