What is meant by Biot number?

What is meant by Biot number?

The Biot number (Bi) is a dimensionless quantity used in heat transfer calculations. It is named after the eighteenth century French physicist Jean-Baptiste Biot (1774–1862), and gives a simple index of the ratio of the thermal resistances inside of a body and at the surface of a body.

What is meant by Nusselt number?

Definition. The Nusselt number is the ratio of convective to conductive heat transfer across a boundary. The convection and conduction heat flows are parallel to each other and to the surface normal of the boundary surface, and are all perpendicular to the mean fluid flow in the simple case.

What is the unit of Biot number?

Nomenclature

Bi	Biot number
Pe	Peclet number
Pr	Prandtl number
q′	heat flux per unit length, W/m
q ′ ′	heat flux, in W/m2

What is the formula Nusselt number?

Nusselt number basically calculated by using the formula (Nu=((hLc)/k), Where h- convective heat transfer coefficient, Lc is characteristic length. In your case, the distance between parallel plates is Lc. and Finally k is thermal conductivity of the material. If the flow is laminar, conductive heat transfer dominates.

How is Biot number calculated?

We can compute the characteristic length Lc knowing the volume V and the area A of a surface through which the material is heated up (or cooled down): Lc = V / A . For example for a copper pan of water with characteristic length Lc = 15 cm , the Biot number is Bi = 2.807 .

What is Biot number in mass transfer?

The Biot number is a dimensionless group that compares the relative transport resistances, external and internal. It arises when formulating and non-dimensionalizing the boundary conditions for the typical conservation of species/energy equation for heat/mass transfer problems.

What is Biot and Fourier number?

Fourier number is a measure of heat conducted through a body relative to heat stored. The Biot number is the ratio of the internal resistance of a body to heat conduction to its external resistance to heat convection.

Why Nusselt number is important?

Nusselt number is an important parameter that can contribute to a better rate of heat exchange. It is basically a function of Reynolds and Prandtl number. The correlation is provided in Eq. This is the so-called Dittus Boelter-type correlation.

What are Biot and Fourier numbers?

What does Nusselt number depends on?

The Nusselt number in the fully developed laminar flow is constant and depends on the channel geometry and the wall heat transfer boundary condition.

Why do we use Nusselt number?

The Nusselt number is a dimensionless number closely related to Péclet number and both numbers are used to describe the ratio of the thermal energy convected to the fluid to the thermal energy conducted within the fluid.

What is magnitude of Biot number in case of cylinder?

Explanation: Biot number = h l/k = 0.48.

What is the difference between Biot number and netnusselt number?

Nusselt number is the ratio of heat transfer resistance by conduction through the fluid to the heat transfer resistance by convection of the fluid. Biot number is the ratio of heat trasnfer resistance offered by conduction through the solid to heat trasnfer resistance by convection of the fluid.

What is the difference between Bi and Nusselt number?

The Biot number (Bi) is a dimensionless number used in the heat transfer calculations in the transition phase. It compares the resistance to heat transfer within and on the surface of a body. Biot number uses thermal conductivity of the body (not fluid), whereas Nusselt number uses thermal conductivity of the fluid.

What is the significance of Biot number?

The Biot number is used the characterize the heat transfer resistance “inside” a solid body. In that case k is the thermal conductivity of the solid body, and h is the heat transfer coefficient that describes the heat transferred from the “surface of the solid body” to the surrounding fluid.

What is the Biot number of a solid body?

Biot number as we know is the ratio of convective heat transfer from the body to the conduction heat transfer with in the body . h= heat transfer coefficient of the fluid surrounding the body. K=thermal conductivity of the solid body.