油松林木废弃物热压成型颗粒介质传热、传力特性研究

STUDY ON HEAT TRANSFERAND STRESS-PASSING CHARACTERISTICS OF SOLID GRANULES MEDIUM IN HOT BRIQUETTING PROCESS OF PINUS TABULAEFORMIS WASTE

该研究旨在确定油松热压成型微观机理,并用宏观试验验证微观结果。选取离散元软件EDEM进行微观仿真模拟,用C++语言编写对应的传热应用程序设计(API),实现热压成型仿真。结果表明:颗粒位移、接触力随应变变化,在形变约为0.5时,逐渐由弹性变形转变为塑性变形阶段,模具内颗粒位移逐渐一致,整体呈现较为杂乱的状态,无上下层颗粒之分,接触力在此处突然激增。生物质成型所受应力越大接触力越杂乱,相互交错程度越明显。模具内颗粒温度上升速率的快慢与微观接触程度有关,宏观压缩程度越大,温度上升速度越快;热量传递的速度与温差相关,然而最终所需传热时间相近。

The purpose of this study is to determine the microstructure mechanism of hot pressing of Pinus tabulaeformis waste and verify the microstructure results with experiments.The discrete element software EDEM was selected for micro simulation,and the corresponding heat transfer API was written in C++language to realize the simulation of hot pressing.The results show that particle displacement and contact force changed with strain,the elastic deformation gradually turned into plastic deformation,the particle displacement in the mold was gradually consistent,however,the whole was disorganized and particles didn’t distinguish between upper and lower layers,the contact force surged when the deformation was about 0.5.The greater the pressure on biomass briquetting,the more disordered the contact force and the more obvious the degree of interlacing.The rising rate of particle temperature in mold is related to the degree of microscopic contact,the greater the compression,the faster the temperature rises;The speed of heat transfer was related to the temperature difference,but the final heat transfer time was similar.