Optimization of thermal performance of vortex tube based on spiral nozzle and bulging belly structure

• A novel vortex tube with spiral nozzles and a bulging cavity is proposed. • The new design increases vortex strength and enhances energy separation efficiency. • Bulging cavity improves residence time and boosts heat exchange interface. • Spiral nozzles generate stable tangential flow and reduce interference. • CFD and experimental results confirm a 29.5 K improvement in cooling effect. The conventional vortex tube exhibits limited energy separation efficiency when dividing compressed gas into hot and cold streams. To address this limitation, a novel “bulging belly” vortex tube structure is proposed, aiming to enhance heat exchange efficiency and fluid rotational velocity. This design introduces an expanded cavity in the central section of the main flow channel, incorporates three helically arranged tilted nozzles, and features an internal spiral flow guide. The helical arrangement of the nozzles stabilizes the rotating flow, strengthens the vortex core, and optimizes the energy separation process. Computational Fluid Dynamics (CFD) simulations and experimental investigations demonstrate that the proposed structure significantly improves heat transfer and cooling performance, resulting in a greater temperature differential between the hot and cold streams and higher rotational velocity compared to traditional designs. The findings confirm that this optimized configuration enhances the thermodynamic performance of the vortex tube without increasing energy consumption, offering a promising direction for advanced engineering applications.