Improving the performance of small Joule–Thomson cryocooler Original Research Article

This paper presents a new cycle for improving the performance of small Joule–Thomson (JT) cryocooler by applying an additional ejector in cycle system. Based on the presented JT cycle with an additional ejector (JTE), the performance of small JT cryocooler operating with pure N2 and the mixture N2−CH4 for cryogenic applications in a temperature range of 80–130 K is investigated by theoretical calculations. It can be found that the refrigeration efficiency of the JTE cryocooler operating with pure N2 increase by 55.6–25.1%, and the refrigeration capacity increase by a factor of 4.9–1.5 compared to a conventional JT cryocooler. Similar performance improvements are also obtained when the mixture N2−CH4 is used as the working gas. The refrigeration efficiency increase by 46.6–17.7% and the refrigeration capacity increase by a factor of 3.8–1.3. It is concluded that the performance of small JT cryocooler can be significantly improved based on the presented JTE cycle.