Numerical analysis of a novel miniature Joule-Thomson cryocooler

In this paper, a novel miniature Joule-Thomson (J-T) cryocooler was proposed and its steady-state cooling characteristics were analyzed via CFD numerical simulation. The performance characteristics were assessed for nitrogen under different inlet pressure and temperature, as well as different orifice widths. The results have outlined the structural advantages of the cooler – its excellent cooling performance, small axial height and simple fabrication. Owing to the structural characteristics of the spiral channel and the centrifugal force and gas viscous force actions, the fluid formed vortexes and secondary flow on the axial shear plane. This improved the heat transfer between the incoming flow and backflow fluid. Therefore, the heat transfer increase will further reduce the cooler stable operating temperature, and the minimum temperature can reach 138.3 K when the inlet pressure is 10 MPa. Meanwhile, there is an optimal throttle orifice width δ value between 0.1 mm and 0.2 mm, the cryocooler can get maximum cooling capacity under minimum temperature. In addition, the inlet pressure increases with the decrease in the throttle orifice width and inlet temperature. The minimum cooler temperature is gradually reduced, extending the cooling duration time. On the other hand, should the minimum temperature and cooling duration time decrease, the mass flow rate will also increase.