The Research On Energy Separation Characteristic And Throttling Technology Of High Pressure Natural Gas In Vortex Tube

Since the advent of vortex tube,its energy separation mechanism has always been the research focus of experts and scholars in related fields at home and abroad.Due to the theoretical value of vortex tube's energy separation mechanism and the broad prospect of its application,it is of great significance to study the energy separation characteristics of the vortex tube.In this paper,the countercurrent vortex tube is as the research object,numerical simulation and experimental research methods are used to study the energy separation effect in the vortex tube.The main contents and conclusions are as follows:Based on the energy conservation equation when the compressible gas moving in the vortex tube,and combined with the knowledge of fluid mechanics,the energy separation mechanism of the vortex tube is analyzed.The results show that the energy separation in the vortex tube is the result of the uncertainty of pressure,the viscosity of the gas and the heat transfer between the air streams.At the same time,the thermodynamics model of the energy separation process in the vortex tube is established based on the first law of thermodynamics and the second law of thermodynamics.The change of entropy in vortex tube is analyzed by minimized entropy production analysis method.The entropy change in the vortex tube is divided into two parts: the entropy change caused by the temperature change and the entropy change caused by the pressure change.The three-dimensional numerical model of the vortex tube with six channels and four channels are established.The Realizable k-? turbulence model was used to simulate the flow and heat transfer process in the vortex tube,and the velocity,pressure and temperature distribution of the vortex tube are obtained,and the effects of inlet pressure and cold flow rate on the energy separation effect of vortex tube are studied.The simulation results show that: when keeping the inlet pressure constant,the cooling effect of vortex tube increases first and then decreases with the increase of cold flow fraction,so there was a best cooling effect,and the heating effect increases with the increase of the cold flow rate.When the cold flow rate is the same,with the increase of the inlet pressure,the cooling effect and the heating effect show an increasing trend.There are two streams of airflow inside the vortex tube,and the axial velocity of the two streams is the opposite,and the internal swirling flows out from the cold end of the vortex tube and the outer swirling flows out from the hot end of the vortex tube.At the same time,there is a circulation flow inside the vortex tube,and the existence of the circulation flow transfers the energy from the internal swirling flow to the outer swirling flow which makes the energy separation phenomenon exist in the vortex tube.The performance evaluation index of energy separation effect in vortex tube is established,the energy separation characteristics of the vortex tube with six channels and four channels are studied by the experimental method.The effects of inlet pressure,cold flow rate and nozzle number on the energy separation characteristics of vortex tube are studied.The change rule of the cooling effect,the heating effect,the unit cooling capacity,the unit heating capacity and the cooling efficiency with the changes of inlet pressure and cold flow rate can be obtained.The results show that the heating performance of the vortex tube with six channels is better than that of the vortex tube with four channels,but the cooling performance of the vortex tube with four channels is better than that of the vortex tube with six channels.According to the energy separation characteristics of the vortex tube,the temperature control implementation plan based on vortex tube throttling process can be put foward,using the vortex tube instead of throttling process,in order to simplify the collection process,reduce investment and operating costs.