Temperature separation characteristics of CH4–CO2 binary gas mixture within a vortex tube

In the natural gas industry, sour gas usually contains some impurities such as CO2. The influence of CO2 fraction on temperature separation within the vortex tube is not fully understood. In the present work, a simulation study has been conducted to investigate the flow and heat transfer behavior of CH4–CO2 binary gas mixtures in a counter flow vortex tube. The model was validated against the experimental data and the predicted temperature separation is found to satisfactorily accord with the experimental values. The mole fraction of CO2 is varied in the range of 0–1.0. The temperature and velocity distribution characteristics of the gas mixture with various CO2 mole fractions are obtained. The results show that velocity and temperature separation increase with increase of mole fraction of CH4 at given inlet flow rate. According to the streamline structure, the area of the backflow region grows as the CH4 mole fraction increases. But the coefficient of performance tends to decrease with improving CH4 content.