Effect of Cold Orifice Diameter and Geometry of Hot end Valves on Performance of Converging Type Ranque Hilsch Vortex Tube

Refrigeration by vortex tube works on the principle of heat transfer between two layers moving opposite to each other. Various experiments have been performed and has revealed two different approaches one for attaining high cold mass fraction and the other for attaining cold end temperature. The geometry requirement is different for the two approaches. The need is to have a tube to produce higher mass of cold air coming out at low temperature. For this purpose converging type of vortex tube is experimented and the results are promising. The results show increase in cold mass fraction as well as cold end temperature. The overall change in cold end temperature drop was 63% and the COP of the converging tube as compared to straight divergent tube increased by 102%. For conical valve angle of 45° air supply pressure of 5 bars and cold orifice diameter as 7 mm the lowest temperature observed was 5 °C producing cold mass fraction of about 0.9.