Refrigeration Performance Analysis Of The Variable Cross-section Double-opening Pressure Oscillation Tube

Gas Wave Refrigeration is a type of refrigeration technology which realizes separation of heat and cold,then achieves the purpose of cooling by using the movement of shock waves and expansion waves in the pressure oscillation tube.With the development of technology,the double-opening pressure oscillation tube has gradually become a research hotspot.Those studies found,the reverse compression wave system(Including reflected shock,reverse compression wave,etc.)in the pressure oscillation tube will compress the cooled gas and reduce the expansion depth,then reduce the refrigeration efficiency.So the reverse compression wave system is the serious problem of the technology development.Therefore,theoretical analysis and numerical simulation are combined in this paper to study wave system motion in double-opening pressure oscillation tube.To improve the expansion depth,the structure of the variable cross-section double-opening pressure oscillation tube is put forward,and then its refrigeration performance is analyzed.Research results of the paper are as follows:(1)The inlet expansion wave and reaction expansion wave in double-opening pressure oscillation tube are main wave system which leads to refrigeration.Under the same expansion ratio,expansion depth with the action of reaction expansion wave raises more than 60% on the basis of that just with the action of inlet expansion wave.It illustrates that reaction expansion wave plays the leading role when realizing refrigeration.Reaction wave system will decrease the expansion depth in the tube,making adverse effect on refrigeration performance.With the increase of pressure in high temperature exhaust nozzle,expansion depth decreases linearly.(2)The variable cross-section double-opening pressure oscillation tube does not only weaken the intensity of the reaction wave system,but also enhance the intensity of the expansion wave,and then improve the refrigeration performance of the pressure oscillation tube.Relative to the straight double-opening pressure oscillation tube,in the same operating conditions,the expansion depth of the variable cross-section double-opening pressure oscillation tube increased by about 14%,and with the increase of the pressure at the high temperature exhaust nozzle,the difference of the expansion depth between the two oscillation tubes shows a decreasing trend.(3)In the scope of the width and the condition in this paper,when the time at which the high-pressure inlet nozzle and the pressure oscillation tube are turned on is the same,with the increase of the pressure oscillation tube,the expansion depth increases,the temperature drop of the gas in expansion zone increases,the rate of jet loss decreases,the supercharging efficiency of shock wave decreases and the percentage of leaks decreases.Combined with the performance indicators with the pressure oscillation tube width of the law of change,the width of the pressure oscillation tube should be remained within a certain range.When the expansion ratio is 3,the width of the pressure oscillation tube should be kept in the range of 14 ~ 22 mm.(4)Through the optimization of the structure parameters of the double-opening straight pressure oscillation tube,it is found when the length of the sudden-expansion segment is about 30mm~60mm and the width of the sudden-expansion segment is about non-expansion segment width of 1.5~1.8 times.When the structure of the variable cross-section double-opening pressure oscillation tube is designed,the variable cross-section structure should give priority to slanting mutation or concave arc mutation structure.(5)This paper established the model of the pressure exchange refrigerator,comparative analysis the refrigeration efficiency of the variable cross-section double-opening pressure oscillating tube,it is higher nearly 4% than the straight double-opening pressure oscillation tube.