Experimental investigation for thermal performance of series and parallel Ranque-Hilsch vortex tube systems

The present study investigated experimentally the cooling and heating performance of two identical counter flow vortex tubes arranged in-series (VTS) and parallel (VTP). The vortex tube used has general specifications of: aspect ratio AR = 1.6, hot tube length L = 112.5 mm, hot tube inner diameter D = 7.5 mm, cold end diameter dc = 5 mm, and generator of three nozzles, N = 3. Dry air is used as a working fluid with different inlet air pressures adjusted from 2 to 6 bars. The experimental results revealed that the maximum cold temperature difference occurred at the inlet air pressure of 6 bars and cold mass fraction of 0.4 for both VTS and VTP systems. The conducted results demonstrated that the values of COPref for VTS system were higher than the values of VTP system. However, the VTP yielded higher values of COPHP over the range of investigation. The VTS system improved the COPref by 22.5% and 31.5% compared with the VTP and the single vortex tube system (VTO), respectively. For the case of VTP system, the COPHP is enhanced by 18.2% and 27.3% than VTS and VTO, respectively.