Development of the double two-phase thermosyphon loops used in low temperature Stirling refrigerator

•The double two-phase thermosyphon loops (DTPTLs) used for low temperature Stirling refrigerator is developed.•The characterization of heat transfer and pressure drop in the DTPTLs is investigated by theoretical calculation for various working refrigerants.•The basic structure of the DTPTLs is modified and improved for dragging and moving convenience.•The no-load cooling temperature could reach −80 °C, and the maximum temperature difference all inside the refrigerator container is less than 5 °C during steady-state operation.