A Research Of Structural Characteristic On Vortex Tube

Vortex tube is a simple device which can separate high-pressure gas into cold and hot flow simultaneously. The features of simple structure, non-moving parts, convenient maintenance, and credible operation make it especially attractive for applications in many domains such as refrigeration, air conditioning, separation of natural gas, mechanical process. However, its disadvantages of low efficiency and less refrigerating output limit it's more extensive applications. Until now, most of the researchers have been concentrating on single vortex tube, whereas investigations of integrated vortex tube have never been involved.This thesis mainly investigates performance mechanics and structural characteristic of integrated vortex tube (vortex board) from two aspects of theoretic and practice. Through present study, it provides an effective means for increases of refrigerating output and extensions of more applications.With vortex model and circulation for free vortex of entrance flow solved, potential equation and stream function equation were derived. Flow motion in space of the vortex tube is superposed to free vortex of inlet plane, sink and the constant axial velocity by means of hodograph transformation and superposition theory. On the basis of energy distribution and viscosity effect, centrifugal force and inner viscous friction make free vortex change into forced vortex vortex. Then, such conclusion was made that the centrifugal force and inner viscous friction are the main reason for energy separation inside the vortex tube.The idea, design method and technological details of integrated vortex tube were mainly discussed, which possess important practical value for development and applications of vortex board.Thermodynamic model of vortex tube was proposed according to thermodynamic first and second law. Pressure drop ratio is the main motivation for energy separation of vortex board when energy separation process is analyzed from the view of entropy and exergy. The relations of function among the pressure ratios of inlet and out flow, the temperature of inlet and out flow, cold air fraction was derived. The minimum pressure ratio of inlet and out flow must meet when needed temperature of cold flow is obtained. The irreversible factors of energy separation process inside the vortex board were analyzed. This indicates that the degrees of energy separation have direct relation with irreversible factors.An experimental apparatus for vortex board was specially designed and corresponding experimental tests were conducted. Under the different operating conditions, the characteristic of vortex board was tested. On the basis of experimental results, effects of inlet parameters and cold air fraction on various performance parameters were analyzed. The results show that vortex board has the same energy separation effect as the single vortex tube.This thesis mainly investigated the influence of structural parameters on the performance of vortex board. Such structural parameters consist of numbers of vortex chamber, the diameters of separation orifice, the length of hot tube, various nozzles pattern and so on. It provides a new approach for designing and applicating vortex board.The exploratory work for the optimum design of vortex board through orthogonal experiment was futher investigated. The experiment of vortex board was designed using the method of orthogonal experiment. The structure parameters of vortex board was further optimized when the influences of structure parameters of vortex board on its operating performance was analysed using the method of analysis of variance.