The image above represents knudsen diffusion of moulding sand.

To compute for knudsen diffusion of moulding sand, three essential parameters are needed and these parameters are **Pore Radius (r), Temperature (T) **and **Molecular Weight (M).**

The formula for calculating knudsen diffusion of moulding sand:

D_{k} = 9700r√(^{T}/_{M})

Where:

D_{k} = Knudsen Diffusion of Moulding Sand

r = Pore Radius

T = Temperature

M = Molecular Weight

Let’s solve an example;

Find the knudsen diffusion of moulding sand when the pore radius is 24, the temperature is 18 and the molecular weight is 12.

This implies that;

r = Pore Radius = 24

T = Temperature = 18

M = Molecular Weight = 12

D_{k} = 9700r√(^{T}/_{M})

D_{k} = 9700(24)√(^{18}/_{12})

D_{k} = 9700(24)√(1.5)

D_{k} = 9700(24)(1.22)

D_{k} = 285120.6

Therefore, the **knudsen diffusion of moulding sand** is **285120.6 cm²/s.**

**Calculating the Pore Radius when the Knudsen Diffusion of Moulding Sand, the Temperature and the Molecular Weight is Given.**

r = ^{Dk} / _{9700 √(T / }_{M})

Where:

r = Pore Radius

D_{k} = Knudsen Diffusion of Moulding Sand

T = Temperature

M = Molecular Weight

Let’s solve an example;

Find the pore radius when the knudsen diffusion of moulding sand is 20, the temperature is 14 and the molecular weight is 10.

This implies that;

D_{k} = Knudsen Diffusion of Moulding Sand = 20

T = Temperature = 14

M = Molecular Weight = 10

r = ^{Dk} / _{9700 √(T / }_{M})

r = ^{20} / _{9700 √(14 / }_{10})

r = ^{20} / _{9700 √(1.4)}

r = ^{20} / _{11446}

r = 0.00174

Therefore, the **pore radius **is **0.00174.**

Continue reading How to Calculate and Solve for Knudsen Diffusion of Moulding Sand | Mass Transfer