The equation below, called **Eucken’s equation**, can be used to estimate thermal conductivity of pure gases, up to moderate pressures.

Where:

*μ* = viscosity, cP

*C _{p}* = specific heat capacity, kJ/(kg

^{o}C)

*M* = molecular weight

A little bit about Eucken’s equation. It was found by German chemist and physicist Arnold Thomas Eucken. In the fields of technical and physical chemistry, he made significant contributions. He focused on molecular physics (rotation, oscillation), deuterium and heavy water, homogeneous and heterogeneous gas dynamics, catalysis, chemical engineering, and chemical technology. He also studied specific heat at very low temperatures and the structure of liquids and electrolytic solutions.

He already passed away almost 70 years ago. But his works will remain.

Alright, let’s see example below.

**Example**

Estimate the thermal conductivity of ethane at 1 bar and 450^{o}C.

**Solution**

Viscosity = 0.0136 cP

Specific heat capacity = 2.46 kJ/(kg^{o}C)

Therefore, thermal conductivity of ethane is

k = 0.0136 (2.46 + 10.4 / 30) = __0.038 W/(m ^{o}C)__

Experimental value is 0.043 W/(m^{o}C), therefore 13%.

That’s all the post on how to estimate thermal conductivity of gas. I hope you find this short post useful.

**Reference:**

- Sinnot, R.K., Chemical Engineering Design Volume 6 Fourth Edition, Elsevier Butterworth-Heinemann, 2005.
- Arnold Eucken