Question

The larger the Bi number, the more accurate the lumped system analysis. a)-True b)- False

Answer 1

Answer:

b). False

Explanation:

Lumped body analysis :

Lumped body analysis states that some bodies during heat transfer process remains uniform at all times. The temperature of these bodies is a function of temperature only. Therefor the heat transfer analysis based on such idea is called lumped body analysis.

                      Biot number is a dimensionless number which governs the heat transfer rate for a lumped body. Biot number is defined as the ratio of the convection transfer at the surface of the body to the conduction inside the body. the temperature difference will be uniform only when the Biot number is nearly equal to zero.  

                      The lumped body analysis assumes that there exists a uniform temperature distribution within the body. This means that the  conduction heat resistance should be zero. Thus the lumped body analysis is exact when biot number is zero.

In general it is assume that for a lumped body analysis, Biot number $\leq$ 0.1

Therefore, the smaller the Biot number, the more exact is the lumped system analysis.