Study On The Performance Of Intersection Damp Gas Wave Refrigerator

Gas Wave Refrigerator(GWR),a kind of gas expansion refrigeration equipment,has many features such as high throughput,long operation period,low cost,easy operation,simple maintenance and good anti-erosion against drops or particles.At present,GWR has already been used in light hydrocarbon recovery from oil-field gas,natural gas dehydration,chemical plant exhaust or waste gas purification,scientific research,etc.However,little research work on GWR has been done,and the previous work focused only on the experimental research for some special cases.A systemically theoretical and experimental research has not been reported, and the performance of GWR needs to be improved for enlargement of application area.This dissertation is aimed to explore a method for improvement of GWR performance.An experimental platform and a numerical model are established to study the wave motion and heat transfer behavior inside oscillating tube.By the study on the wave motion inside oscillating tube,the operational conditions when GWR achieves the extreme refrigeration efficiency are determined,and a prediction method for extreme jet flow frequency is put forward.By the study on the heat transfer behavior inside oscillating tube,the tube wall temperature distribution and its parameter influences are obtained,and Intersection Oscillating Tube(IOT) is proposed. By the study on IOT performance,IOT structure is effectively improved,and Intersection Damp Oscillating Tube(IDOT) is determined because of its better performance.By the study on parameter influences on the refrigeration performance of GWR with IDOT,the operation principles of this GWR are obtained.The main research work and achievements are as following.(1) Two experimental machines,60-tube whole machine and multi-tube series machine, are designed and produced.The GWR experimental platform with changeable boundary conditions is set up.Thus,it is possible to complete many experimental works on oscillating tube,such as the inner transient pressure,the outer wall temperature,the refrigeration performance and the structure optimization.Besides,the differences between experimental GWR and industrial GWR can be reduced.A numerical model of GWR is set up using sliding mesh technique,and the tube wall temperature distribution which is obtained from experiments is considered.This model can complete the multi-period computation,and simulate the influence of the adjacent oscillating tubes.It can overcome the disadvantages of the conventional model such as inaccurate initial conditions and inaccurate boundary conditions,and make up for the deficiency of long computing time and big accumulated error for oscillating tube to achieve thermal equilibrium. The numerical model is verified by experiments and it is in good agreement with the experimental results.(2) The flow inside the oscillating tube is investigated by the numerical and experimental study on wave moving status and heat transfer process.The results show that,the existence of extreme refrigeration performance is mainly because of the optimal match relation between shock wave and nozzle structure.The numerical analysis can ideally forecast the extreme jet frequency of GWR.As the shock wave disturbance inside oscillating tube can cause the rapid increase of gas temperature and heat flow rate of the inner wall,it is considered as the main influencing factor of the wall temperature distribution.As there is a disturbance range for shock wave inside oscillating tube,the jumping and rebound phenomena appear in the tube wall temperature distribution.(3) By analyzing the wall temperature distribution of oscillating tube,the intersection dissipation phenomenon of waves has been detected under the higher order extreme jet frequency.Then,Intersection Oscillating Tube(IOT) is put forward and its internal flow and refrigeration performance are studied.The results show that the utilization ratio and refrigeration performance of oscillating tube have been enhanced by using IOT.As IOT can not eliminate the shock wave,there are still the obvious extreme phenomena in refrigeration performance.When the second oscillating tube of lOT achieves the optimal match relation between shock wave and nozzle structure,the extreme isentropic refrigeration efficiency appears.(4) The structural parameter influences on weakening-wave performance of the expansion chamber(a sudden-expansion structure) are investigated.Then the oscillating tube with series expansion chambers is proposed considering the effect of chamber diameter on the GWR volume,and its internal flow and refrigeration performance are studied.The results show that, series expansion chambers can absorb the injected shock waves,and the reflected waves are expansion waves.Therefore,the refrigeration performance of oscillating tube is enhanced and its change range with jet frequency becomes small.For the reflected expansion waves can cause the second injected shock waves,there is the optimal match relation between the reflected expansion waves and nozzle structure,leading to the slight extreme phenomena in refrigeration performance of oscillating tube with series expansion chambers.The oscillating tube inlet has already been closed by the nozzle forehead when the reflected expansion waves get to the inlet, which is the condition for oscillating tube with series expansion chambers to achieve the extreme isentropic refrigeration efficiency(5) IDOT is put forward by combining two weakening-wave methods,intersection dissipation and damp absorption,and its internal flow and refrigeration performance are studied. The results show that IDOT has the merit of IOT and oscillating tube with series expansion chambers,makes up for the deficiency of IOT in match relation.Comparing with the straight oscillating tube,the utilization ratio and refrigeration performance of IDOT are enhanced,the increase of isentropic refrigeration efficiency may reach above 15%to the most and the peak efficiency has increased more than 5%.The refrigeration performance and the throughput of IDOT are both more stable because the reflected wave is expansion wave.The extreme isentropic refrigeration efficiency of IDOT can be achieved if its inlet has already been closed by the nozzle forehead when the reflected expansion wave gets to the inlet.(6) The influences of some parameters,including expansion ratio,pressure value,nozzle width and nozzle jet angle,on the refrigeration performance of GWR with IDOT are investigated,and the influence mechanisms are analyzed.Furthermore,the operation law of GWR with IDOT is found,and its industrial application is guaranteed.