Peclet Number Calculator

Peclet number calculator

Peclet number calculator is used to calculate peclet number, density, velocity, thermal conductivity, heat capacity, and characteristic length simply and more easily.

What is the Peclet Number?

The Peclet number is a dimensionless quantity that relates the rates of convective and diffusive mass transfer in a fluid. It is named after the French physicist Jean Claude Eugène Péclet. This parameter provides insights into the dominant mode of mass transfer and the overall efficiency of the process.

The Peclet number is widely used in various branches of science and engineering to analyze and optimize mass transfer phenomena.

The Components of the Peclet Number:

The Peclet number combines two fundamental factors: the characteristic length (L) and the characteristic velocity (V). The characteristic length refers to the size or scale of the system under consideration, while the characteristic velocity represents the speed at which the fluid is moving.

By dividing the product of these two parameters by the mass diffusivity (D), the Peclet number is obtained.

Peclet Number Calculation:

To calculate the Peclet number, one needs to determine the characteristic length, characteristic velocity, and mass diffusivity. The specific approach may vary depending on the system and application under consideration. However, a common formula for the Peclet number is:

Pe = (L * V) / D

Where:

• Pe = Peclet number
• L = Characteristic length
• V = Characteristic velocity
• D = Mass diffusivity

Impact of Peclet Number on Mass Transfer Efficiency:

The Peclet number has a direct influence on the efficiency of mass transfer processes. When the Peclet number is high, indicating dominant convection, the mass transfer rate is generally faster and more efficient. On the other hand, when the Peclet number is low, signifying dominant diffusion, the mass transfer rate is slower, and efficiency may be compromised.

Solved Example

Example 

Suppose we have a cylindrical pipe with a diameter of 0.1 meters (characteristic length, L) through which water is flowing at a velocity of 1 meter per second (characteristic velocity, V). The mass diffusivity of a solute in water is 0.2 square meters per second (D).

Solution:

Step 1: Extract the data.

L = 0.1

V = 1

D = 0.2

Step 2: Apply the formula.

To calculate the Peclet number (Pe), we can use the formula:

Pe = (L * V) / D

Substituting the given values:

Pe = (0.1 * 1) / 0.2

Pe = 0.5

In this example, the Peclet number is 0.5. This value indicates that diffusion has a relatively higher influence compared to convection in the mass transfer process within the cylindrical pipe.