The influence of different cold end orifice diameter on the performance of vortex tube was studied using the test bench. In the 0.3-0.5 MPa range of inlet pressure

the effect of cold end pore size on the temperature drop

the characteristics of refrigeration capacity

the efficiency of the temperature and the COP characteristics were analyzed. The experimental results showed that the cold end orifice diameter on the vortex tube has a great impact on performance

and there exists a cold end orifice diameter of a vortex tube which makes the cold end temperature drop and refrigeration capacity reach the maximum. Under the current conditions of the vortex tube

the optimal diameter of the cold end orifice is 5 mm

and the ratio between the best cold end orifice diameter and the best hot end diameter is 0.5.