Study on the dynamic cooling performance of a -150°C reverse Brayton cycle air cryocooler

A turboexpander having a working wheel with a diameter of 24 mm and a plate-fin heat exchanger were applied in a retrofitted -150°C air cryocooler system. A vacuum cryogenic trap (absolute pressure < 10^-3 Pa) was used for insulation. The dynamic cooling performance of the whole system was studied under the conditions of different brake wheel configurations. A numerical model in respect of the dynamic cooling performance of the -150°C air cryocooler system was established. The results show that the brake wheel size significantly affects the cooling performance of the cryocooler, and the lowest system temperature is under -150°C. Additionally, the numerical results agree well with the experimental data.