Study On Heat And Mass Transfer Of Sieve Plate Hot Water Tower And Effect Of Solid Particles On Bubble Movement

In this paper,the sieve plate type evaporative hot water tower is taken as the research object.The high-speed camera and image processing software are used to study the behavior of the bubble on the tray.The deformation process and motion characteristics of the bubble in a complete motion cycle are obtained.The design and industrial practice of the evaporative hot water tower has certain guiding significance.The movement process and characteristics of single bubble in the hot water tower were visualized by changing the vapor-liquid operating conditions.The results show that the bubble can be divided into the formation area,the rising region and the oscillation area.In the formation area,the equivalent radius of the bubble increases rapidly,and increases slowly in the rising region and the oscillation area.In the formation area,the bubble diameter ratio becomes smaller from large to small,increases rapidly in the rising region,and is smoother in the oscillation area.The centroid rise rate of the bubble appears rising first and then fluctuating smoothly.A mixture of non-condensable N2 and solid particles was added to the steam to study the effect of solid particles on the bubble motion process,and the influence of the hydrophilicity and particle size of the solid particles entering the column on the bubble motion was investigated.The results show that when the pulverized coal particles are entrained in the ascending airflow,the time ratio of the oscillation area of the bubble is significantly increased,which is beneficial to the heat and mass transfer in the tower.The smaller the particle size,the more heat and mass transfer process in the tower.It is advantageous to change the operating conditions and find that the decrease in particle size and vapor-to-nitrogen ratio a promotes heat and mass transfer;the effect of particle hydrophilicity on bubble motion is investigated using a microscope with a protractor and a high-speed camera.The results show that the stronger the hydrophilicity,the more effective the heat transfer and mass transfer process between gas and liquid.