Biot Number
Consider a 5 m long metal cube has a convection heat transfer coefficient of 35 W/m^2∙K, and a thermal conductivity of 700 W/m∙K. What is its Biot number?
Expand Hint
The Biot number (Bi) is a dimensionless positive quantity that describes the ratio of thermal resistance for conduction inside a body to the resistance for convection at that same body’s surface.
Hint 2
$$$Bi=\frac{hV}{kA_s}$$$
where
$$Bi$$
is the Biot Number,
$$h$$
is the convection heat transfer coefficient,
$$V$$
is the volume,
$$k$$
is the thermal conductivity, and
$$A_s$$
is the surface area of the body.
The Biot number (Bi) is a dimensionless positive quantity that describes the ratio of thermal resistance for conduction inside a body to the resistance for convection at that same body’s surface.
$$$Bi=\frac{hV}{kA_s}$$$
where
$$Bi$$
is the Biot Number,
$$h$$
is the convection heat transfer coefficient,
$$V$$
is the volume,
$$k$$
is the thermal conductivity, and
$$A_s$$
is the surface area of the body.
$$$Bi=\frac{(35W)(5m\cdot 5m \cdot 5m)(m\cdot K)}{(m^2\cdot K)(700W)(5m\cdot 5m\cdot 6)}$$$
$$$=\frac{35W\cdot 125m^4\cdot K}{700W\cdot 150m^4\cdot K}=0.042$$$
0.042
Time Analysis
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