Development and performance test of a mixed-refrigerant cryogenic environment test facility for building elements

Abstract The development of cryogenic-related buildings requires cryogenic environment test facilities with large inside space and low testing temperature. A -120°C cryogenic environment test facility is developed and tested by the Technical Institute of Physics and Chemistry, Chinese Academy of Sciences (TIPC, CAS), including a cryogenic chamber and several visualized cryogenic loading test boxes. The cooling power is provided by mixed-refrigerant (MR) refrigerators directly or through liquid nitrogen, precisely controlling the test environment temperature along with PID heaters. Building elements of pillars and beams in concrete, steel and other materials can be cooled down (in the chamber and boxes) and tested (mainly in loading test boxes), with maximum length of 3 m (beams) or height of 1.8 m (pillars). Optical measurement can also be conducted through the large visual windows of cryogenic loading test boxes during the loading tests. This cryogenic environment test facility is successfully utilized in the research on cryogenic mechanical properties of the building technology laboratory of Tianjin University. Operating temperatures below -120 °C are reached in the cryogenic chamber and loading test boxes, with temperature heterogeneity of ±2°C and temperature fluctuation of ±1.5°C.