Comparison of the standard Euler-Euler and hybrid Euler-Lagrange approaches for modeling particle transport in a pilot-scale circulating fluidized bed

Particle transport phenomena in small-scale circulating fiuidized beds （CFB） can be simulated using the Euler-Euler, discrete element method, and Euler-Lagrange approaches. In this work, a hybrid Euler-Lagrange model known as the dense discrete phase model （DDPM）, which has common roots with the multiphase particle-in-cell model, was applied in simulating particle transport within a mid-sized experimental CFB facility. Implementation of the DDPM into the commercial ANSYS Fluent CFD package is relatively young in comparison with the granular Eulerian model. For that reason, validation of the DDPM approach against experimental data is still required and is addressed in this paper. Additional difficulties encountered in modeling fluidization processes are connected with long calculation times. To reduce times, the complete boiler models are simplified to include just the combustion chamber. Such simplifications introduce errors in the predicted solid distribution in the boiler. To investigate the conse- quences of model reduction, simulations were made using the simplified and complete pilot geometries and compared with experimental data. All simulations were performed using the ANSYSFLUENT 14.0 package. A set of user defined functions were used in the hybrid DDPM and Euler-Euler approaches to recirculate solid particles.     

制冷压缩机性能试验台

该试验装置可对10～60kW制冷压缩机进行制冷量、输入功率、单位功率制冷量等性能进行自动测试,其主测与辅测试验偏差小于4%,主测重复精度小于2%.试验台中所选用的各类仪器、仪表的量程和准确度符合GB5773-86标准的要求.试验台测试与控制自动化程度高,采用的首级控制与次级控制的方法先进,工况入稳时间短,测试精度高,制冷量测试范围宽,功能全,整体性能达到了90年代国际水平.     

沪东重机——用创新挑战未来

沪东重机有限公司是一家以船用低速柴油机制造为主的国营大中型企业，并积极开发柴油机配件、盾构和GE排气缸等产品，形成船用中、低速柴油机、地铁盾构、柴油机陆用电站、GE排气缸、大型铸钢、铸铁件等多门类产品同步发展的良好态势，最近又积极地进入核电应急发电机组成套设备供应、“机轴浆”打包供应等新领域。     

制冷技术教学方法探讨

对制冷技术教学方法,进行了一些有益的探讨.     

自立式起重设备中四连杆机构的优化

对起重机械中四连杆机构建立力学及优化设计模型,确定相关尺寸和构件相对位置并与传统设计进行比较,进一步说明方案选择的合理性.结果表明优化后的结构受力得到明显改善,并减轻结构质量.     

SKLB10摆式逆流冷却器

该设备采用可调试旋转匀料机构及自动液压排料机构,排料速度及排料流量可调、料位、摆动角度可调.设备适用于团块料、粉状料及其他形状物料的冷却.经检测,该设备制造质量和技术性能指标均符合Q/320481LJ155-1998标准的要求.     

住宅给排水优化设计初探

如何满足不同用户对住宅布局的要求，作者从厨房设施，平面布局，水表设置、管线安装，新技术的应用及专业配合等方面做了具体阐述。     

ASON技术的应用与发展研究

ASON是下一代光传输网的发展方向，目前从标准研究和设备开发的角度来看，都已经达到较高的水平，但是在应用方面还刚刚起步，缺乏应用经验，特别是从初步应用中看出，没有发挥出ASON的特点或特性。     

高校设备配置资源优化的思考

高校实验仪器设备的优化配置对高校的办学效益及长远发展具有相当的现实意义及紧迫性，本文就此问题进行了探析。