Numerical Simulation On The Flow And Heat Transfer Characteristics Of A Coaxial Gas-Solid Two-Impinging-Streams (TIS) Dryer

The conception of Impinging Streams( IS ) was first put forward by a famous Russian scientist—Elperin. The essence of the method of Impinging Streams lies in directing two streams of a suspension of particles one against the other streams, on the same axis. At the impingement zone of the streams, particles penetrate into the other stream. Then the air stream against them slows the particles down until their velocity is zero. Then, particles are accelerated by the air stream in the opposite direction. After several times of damping oscillations, the particles lose their energy and run away from the system. The impingement of the streams causes intensive mixing of the continuous phase which contributes as well to the enhancement of the heat and mass transfer. As a consequence, Impinging Streams have much application in industry.The method of the study of Impinging Streams is experiments. But this method always cost much money, time and materials,and the results are limited by the equipment, environment, occasion so that the results are not so accurate.With the fast development of computer science, People find a new method to carry out the research of the Impinging Streams. That is numerical simulation. The researcher tries to use this method to investigate the flow and heat transfer characteristics of a coaxial gas-solid two-impinging-streams (TIS) dryer.The researcher recurred to the powerful CFD software—FLUENT to simulate the TIS. First, the researcher set up a geometrical model of the TIS dryer, then produced grid in the model. After choosing some proper CFD equations, the researchers began the calculation and do the postprocessing when the results were received.First, the researcher studied the distribution of the fluid field and the pressure of the continuous phase. Then, the main factors that affect the maximal radial speed were discussed. After that, the researcher studied the tracks and velocity of particles. And the heat transfer coefficient was discussed and the relationship of the coefficient with the mass flow rate of particles was obtained.In conclusion, after the comparison of the results from the experiment and numerical simulation, it is found that the numerical simulation method can succeed in simulating the TIS dryer. Then we can draw the conclusion that the model is suitable and it is applicable to use the numerical simulation to carry out the research of Impinging Streams. We can also make it a step stone for the further theoretical study and design of the Impinging Streams dryers.