effects of nozzle number, diameter and inlet pressure on performance of a double-circuit vortex tube system: experimental investigation

Present study discussed an experimental and numerical investigation into thermal performance of a double-circuit vortex tube (dcvt) under varying operational and geometric parameters, including nozzle number, nozzle diameter, and inlet pressure. fifteen dcvt prototypes were tested, incorporating nozzle counts of 2, 3, 4, 5, and 6, nozzle diameters of 1.5 mm, 2 mm, and 2.5 mm, and inlet air pressures of 8, 9, 10 and second circuit 1.5 bar. the findings indicate that reducing the number of nozzles from 6 to 2 resulted in an increase of 10.82% in cooling efficiency and 12.77% in heating efficiency. similarly, decreasing the nozzle diameter from 2.5 mm to 1.5 mm led to improvements of 3.48% in cooling efficiency and 6.05% in heating efficiency. the optimal inlet pressure was found to be 9 bar, where cooling efficiency improved by 2.41% and heating efficiency by 3.10%, compared to operation at 8 bar. in contrast, performance declined at 10 bar, with cooling and heating efficiencies decreasing by 1.38% and 2.58%, respectively. under the optimal conditions, the system exhibited the highest coefficients of performance (cop), with enhancement of 18.39%, relative to the base case. complementary computational fluid dynamics (cfd) simulations using the k-ε turbulence model in fluent software confirmed the experimental results, showing maximum temperature separation and velocity distribution when using two 1.5 mm nozzles at 9 bar inlet pressure. these results provide a comprehensive dataset for optimizing vortex tube design in energy-efficient, refrigerant-free cooling systems for industrial applications.