Experimental Investigation On The Effect Of Length To Diameter Ratio (L/D) On The Performance Of Vortex Tube

Abstract

Vortex tube is a simple device that produces cold and hot streams from the pressurized gases. The
separation of air steams by using of vortex tube principles can be utilized in many industrial applications,
such as cooling of work piece in machining processes. The implementation of vortex tube for cooling
purposes would provide many benefits, including simplicity, light weight, quietness and no need for
refrigerants. This study aims to investigate experimentally the effect of the length to diameter ratio (L/D)
on the performance of the vortex tube. A simple vortex tube was fabricated and tested for different L/D
ratios: 27.50, 22.94 and 18.34. Besides, different air pressures of 2, 3 and 4 bars were applied. The
collected temperature results on the cold air stream showed an inverse relationship with the pressure. It
was noticed that the cold stream temperature starts to decrease with the decrease of L/D ratio until it
reached 22.94 where it starts to increase again. The lowest cold air temperature for the tested system
was found to be 7.6oC, which was observed at L/D ratio of 22.94. A similar trend was observed for the
isentropic efficiency of the system as it was found that the highest efficiency was 27.41% at the L/D ratio
of 22.94.