The oscillatory tube respresents a simple arrangement for gas cooling by its decompression

and has many applications in chemical processes and energy transformation. The mechanism of the cooling effect of oscillatory tube is the conversion of the pressure energy of gas to heat through the movement of pressure waves

which are moving shock wave and unsteady expansion wave. The radial heat transfer through the tube wall will influence the performance of the oscillatory tube significantly. In the present paper

the effects of heat transfer conditions outside of an oscillatory tube on the performance of the tube are investigated experimentally. In the experiments

two kinds of typical heat transfer conditions

natural convection and forced convection(axially water cooled)

are studied. The oscillatory tube is a red copper tube

14 mm in diameter and 4 2 m in length. The pressure ratio is in the range of 2 0—6 0. The ambient temperature is 15 ℃. The inlet temperature of the cooling water is 17 7 ℃ at a flow rate of 0 81 kg·s -1 . The experimental results show that the refrigerating efficiency of the tube is increased by 4 6%—5 4% when the heat transfer condition outside the tube wall is improved by axial water cooling. Also

the optimum pulsing frequency ( f opt ) of the driving jet flow is reduced significantly and the value of f opt is no longer affected greatly by the pressure ratio when the heat transfer outside of the tube is intensified. The theoretical analyses of the experimental results are also presented.