Liquefaction and solidification are two common phenomena in engineering fluid systems. The low temperatures of the boiling point and melting point of cryogenic fluids make it relatively difficult to observe the liquefaction and solidification processes under controlled conditions. An experimental setup for visualization of such processes has been designed and fabricated to capture the moments of the vapor-liquid and liquid-solid phase transition of nitrogen (44-80 K)

argon (50-90 K) and oxygen (50-90 K)

based on a G-M cryocooler as the cold source. The experimental results showed that these three cryogenic fluids behave considerably different during the solidification process.