DEM Study Of Heat Transfer In Rotating Drums

Drum cooler is an important equipment in rotary hearth furnace process line.Traditional way of cooling mainly including cooling water soaking the cylinder or spraying water on the outer wall of cylinder,is inefficient,serious material waste,high cost and not environmentally friendly.Spray cooling technology has a broad application prospect with high cooling efficiency and less energy waste,however people know less about the temperature distribution of the cylinder wall,the atomization nozzle arranged with experience has a great influence on the cooling efficiency.The paper takes drum cooler as the research project.The main purpose of research is through the analysis of the heat transfer process of particles and wall,establishing the particle heat transfer models based on the discrete element method,improving collision search algorithm for granular materials,and using the experiment and numerical simulation to verify models and check the collision search algorithm.What's more,the paper investigates the heat transfer process in rotary cylinder with granular material filling rate,particle size,cylinder speed,number of lifting blade and height of lifting blade.Through the study of heat transfer process of the drum cooler,the paper provides the design reference for the layout of atomization nozzle.From the perspective of the simulation method,the paper is divided into three aspects: establishing the particle model based discrete element method;verifying model and checking algorithm;the application of the model.First,this paper expounds the basic principle of discrete element method,and analyzes two simplified particles model: soft ball model and hard ball of the discrete element,and take the soft ball model as the research object.Then the paper expounds the heat transfer theory of granular material moving in the rotary cylinder.Second,the paper introduces the application of particles simulated based on discrete element method,and improves a neighbor search algorithm based on grid method by studying the three search algorithm: Neighbor List Method,Boundary Box method and Grid Method,and accomplish through the open source software LIGGGHTS.Meanwhile,the paper establishes the model of discrete element method and by comparing the simulation results of EDEMTMAcademic2.5 software and the open source software LIGGGHTS with neighbor collision search algorithm,the workverifies the rationality of the algorithm and the correctness of the model of discrete element method.Finally,based on the above research,the paper investigates the heat transfer process in rotary cylinder with granular material filling rate,particle size,cylinder speed,number of lifting blade and height of lifting blade through open source software LIGGGHTS.The simulation results show that:(1)the average temperature's cooling rate of particles decreased with increasing the rate of filling and the filling rate is smaller,the faster of the cooling rate.(2)The average temperature's cooling rate of particles decreased with increasing the particle size,the smaller the particle size,the faster of the cooling rate.(3)Increasing the speed of cylinder can speed up the average temperature's cooling rate of particles.(4)Increasing the number of lifting blade within a certain range can speed up the average temperature's cooling rate of particles,but when the number of lifting blade reaching a certain value,increasing the number of lifting blade reduces the cooling speed of particles instead.(5)Increasing the height of lifting blade can speed up the cooling of particles.