Increasing the heating value of natural gas by reducing CO2 concentration using vortex tube: A new method

Natural gas (based on methane) is one of the most popular fossil fuels used in the world's energy industries, so, any progress in increasing its heating value can have impressive impacts on the energy efficiency around the world and specially on global warming. Separation of carbon dioxide is one of the most important actions that can increase the heating value of natural gas. For the first time, this experimental investigation is designed to apply thermodynamic performance of a vortex tube for improving the heating value of natural gas through the separation process. Furthermore, this research investigates the effects of the internal structural parameters of the navigator on the separation level of CO2 from the injected natural gas (Pin = 0.5, 0.7 and 0.9 MPa). The considered structural factors are; the middle part diameter (o=12, 13 and 14 mm), the convergence angle (theta = 0 degrees, 1 degrees, 2 degrees, 3 degrees and 4 degrees) and the divergence angle (beta = 0 degrees, 1 degrees, 2 degrees, 3 degrees and 4 degrees), and the results show that there are optimum values (o=13 mm, theta = 3 degrees,beta = 1 degrees) which lead to the maximum level of carbon dioxide separation from the natural gas stream. The results show that the optimum VT decreases the concentration of CO2 at the cold outlet to 1.30 % (P = 0.5 MPa), 1.16 % (P = 0.7 MPa) and 0.79 % (P = 0.9 MPa) via the thermodynamic separation process.