Study On Capability Of Sudden-expansion Oscillating Tube And Application

In industry, as a kind of gas expansion refrigeration equipment,Gas Wave Refrigerator(GWR) has good features, such as high throughput, low cost, smooth operation under different conditions easy operation, simple maintenance, long operating life and can be used in gas-liquid two-phase flow. But. it also has some disadvantages, for example, large sized, low utilization rate of oscillating tube,intense vibration. And the investigation indicated that the isentropic refrigeration of the Gas Wave Refrigeration undulate consumingly with the changing of the jet flow frequency, and that is not helpful of the smooth operation. Aiming at these shortcomings, the method of combination of experimental and numerical simulation was adopted by this paper to improve the structure of the oscillating tube which is key components of rotating Gas Wave Refrigerator, and a sudden-expansion structure was proposed. The parameters, such as transient pressure, outer wall temperature, expansion ratio, exit pressure, frequency and inner wave motion, how to affect the refrigeration capability was acquired,realized the operation rules of the GWR.Analyzed and studied the effect of on the refrigeration performance,acquired the operation rules of the GWR. This paper sought the way in which can elevate the isentropic refrigeration efficiency of GWR.The main research and achievements are as following:(1) The reasonable experiment device and measure system were set up to ensure accomplish large of experimental works concerning GWR. Using sliding mesh technique, making a model can complete the multi-period computation and simulate the influence between adjacent oscillating tubes. This model can conquer the shortcoming of old model. There are a number of disadvantages in old model. For example, inaccurate initial conditions and boundary conditions. By solving the problems of long computing time and large accumulated error, this paper adopted the Used Define Function (UDF). UDF can join tube wall temperature distribution which is obtained from experiments in this model. By analyzing the results of experiments and numerical,this model was in good agreement with the experiment.(2) In the kind of operating condition,analyzing and researching the process of the internal flow and heat transfer of one-end-closed oscillating tube.(3) A sudden-expansion structure oscillating tube can absorb the energy of shock wave and become reflected wave into expansion wave. So it is helpful of improving the refrigeration capability. This structure oscillating also presents the "saddle shape'", and also has extremum phenomenon. The isentropic refrigeration efficiency of sudden-expansion structure oscillating is more than one-end-closed oscillating tube and can improve the efficiency to 10% or more.(4) A sudden-expansion structure and one-end-closed structure has the same trend on the wall temperature. With the expansion ratio increases,inlet temperature of oscillating lower, and the end rise.Because in the same condition,a sudden-expansion structure has more superficial heat dissipating capacity,it sends out more quantity of heat. These prove that this structure has greater refrigeration capability.(5) During wave motion,the process of incident shock wave is the same in sudden-expansion structure and one-end-closed structure.But in two kinds of oscillating tubes, the shock wave disturbance scope is respectively different.The scope of sudden-expansion structure is obviously smaller. Add the connectivity chamber, the oscillation amplitude of internal pressure wave obvious weakening.(6) When mandatory centralized heat transfer, reducing heat exchanger medium temperature helps the improvement of refrigeration capability in the same condition.