Influence of Hot Tube Diameter on Behavior of Vortex Tube Refrigerator: A Simulation Study

The fluid fields, in vortex tube refrigerator with CO₂ gas medium, were mathematically formulated with standard k-ε model, theoretically analyzed and numerically simulated with software Fluent.The influence of the hot-tube diameter on the performance of vortex tube refrigerator was investigated.The simulated results show that significant temperature separation occurs in the swirl-chamber, and that the hot-tube diameter has a major impact, under the pre-defined conditions, including an inlet CO₂ flow-rate of 0.0166 kg/s at 398.15 K, a cold flow ratio in 0.1-0.9 range and a hot-tube diameter in 4.0~6.0 mm range.To be specific, as the hot-tube diameter increases, the cooling-rate and COP change in an increase-decrease mode.With the hot-tube diameter of 4.5 mm, a cold-flow ratio of 0.7 generates the largest temperature difference of 28.1 K, whereas a cold-flow ratio of 0.6 produces a cooling power of 87.37 W and a COP of 9.78%.