High-power Stirling-type pulse tube cooler working below 30 K

High-power Stirling-type pulse tube coolers (PTCs) are promising candidates for cooling HTS devices and gas liquefaction or separation applications. Nevertheless, till now most high-power Stirling-type PTCs are not able to reach a refrigeration temperature below 35 K. Here, a high-power two-stage Stirling-type PTC was designed, manufactured and experimentally investigated. In order to realize a convenient coupling with a thermal load, U-shape configuration is adopted in both stages, which makes it more challenging to distribute the gas flow and reduce dead volume in the cold end heat exchanger. By optimizing operating conditions, flow straightener, and double-inlet opening, the cooler has reached no-load refrigeration temperatures of 29.6 K and 27.1 K at 55 Hz and 40 Hz, respectively. Furthermore, the cooler is able to provide cooling powers of 50 W at 45.6 K and 100 W at 59.3 K when input pV powers are 4.77 kW and 4.59 kW, respectively.