Experimental Investigation Of Multistage Nozzle Manifolds In A Vortex Tube For Enhanced Energy Separation

Abstract

The vortex tube is a simple mechanical apparatus that utilizes the temperature separation phenomenon to divide compressed air into hot and cold streams, without any moving parts. The aims of this study are to enhance the energy separation efficiency and to increase the temperature differential between the cold and hot ends of the vortex tube, thereby improving its overall performance.

This study is distinguished by its investigation of a vortex tube equipped with a multi-stage nozzle system installed at various inclination angles. To the best of our knowledge, and based on the reviewed literature, this specific configuration has not been explicitly addressed in previous research.

A locally fabricated test rig was constructed, comprising an air inlet, chamber, nozzle manifold, hot tube, cold outlet, and hot outlet. The effects of varying inlet air pressure and multiple nozzle stages were investigated experimentally.

The results showed that increasing the inlet air pressure leads to an increase in ΔTh, while both ΔTc and the coefficient of performance (COP) decrease. Furthermore, the optimal tube lengths were found to be 600, 620, 750, and 800 mm for nozzle inclination angles of 0°, 5°, 10°, and 15°, respectively. These optimal lengths were influenced solely by the nozzle inclination angle and not by the number of nozzle stages. Among the tested angles, 5° proved to be the most effective.

The triple-nozzle manifold with a 5° inclination achieved optimal outlet temperatures of 2.5 °C and 43.2 °C for the cold and hot streams, respectively. Additionally, the optimum COPh and COPc values were observed for the triple-stage configuration at 5°, with average improvements of 4.92% and 15.01%, respectively.

This study contributes new insights to the field, as the effect of employing multi-stage nozzles with varying inclination angles on the performance of the vortex tube has not been explicitly addressed in previous research. These findings highlight the potential of using multi-stage nozzles with optimized inclination angles to significantly improve the thermal performance of vortex tubes, making them more effective for practical applications in energy separation and industrial spot cooling systems