Experimental studies on a high performance compact loop heat pipe with a square flat evaporator

A thorough experimental investigation was carried out on a copper–water compact loop heat pipe (LHP) with a unique flat, square evaporator with dimension of 30 mm (L)×30 mm (W)×15 mm (H) and a connecting tube having an inner diameter of 5 mm. Using a carefully designed experimental system, the startup process of the LHP when subjected to different heat loads was studied and the possible mechanisms behind the observed phenomena were explored. Two main modes, boiling trigger startup and evaporation trigger startup, were proposed to explain the varying startup behavior for different heat loads. In addition, an expression was developed to describe the radius of the receding meniscus inside the wick, to balance the increased pressure drop along the LHP with increasing heat loads. Finally, insight into how the compact LHP can transfer heat loads of more than 600 W (with a heat flux in excess of 100 W/cm²) with no occurrence of evaporator dry-out was provided.     

Effects of hydrothermal temperatures on properties of magnetic titanate nanotubes

NiFe2O4 dopeded with magnetic titanate nanotubes(MTNT)were prepared by a hydrothermal method using magnetic nanoparticles TiO2/SiO2/NiFe2O4 as the precursor.The effects of hydrothermal temperatures on their composition,morphologies and magnetic properties of products were characterized by transmission electron microscopy(TEM),scanning electron microscopy(SEM),X-ray diffraction(XRD),vibration sample magnetometer(VSM)and energy dispersive X-ray spectroscopy(EDS).The results show that the hydrothermal temperature has a significant impact on the morphology of the products.The MTNT is synthesized in the temperature range of 120-160 ℃ and the inner diameter of MTNT is about 3-10 nm,the wall thickness 4-12nm and the length 100-200 nm.The components of MTNT are Na0.8H1.2Ti3O7 and a little of anatase TiO2 and NiFe2O4.The ferrimagnetisms and magnetic hysteresis phenomena are shown in the prepared MTNT.The hydrothermal temperature has no clear effect on the magnetic properties in the range of 120-180 ℃.The visible-light photo-catalytic activity of the products decreases as the temperature increases.The decolorization of methylene blue is 94.6% by the MTNT obtained at 120 ℃ and the recovery rate of MTNT is more than 95 percent.The MTNT has excellent photocatalytic activity and is easy to recovery.     

大空间下送风分层空调的同步求解模型的研究

提出了一种大空间下送风分层空调环境下的同步求解模型,用于预测室内空气垂直温度分布和内壁面温度分布以及下送风环境下的空调冷负荷;进行了大空间建筑下送风环境下的夏季热环境实验,实测室内空气垂直温度分布和内壁面温度分布以及夏季冷负荷,并验证对比了实验值和模型计算值,结果表明温度数据吻合良好,冷负荷的相对误差小于10％.     

多物理场耦合软件GTEA开发及应用

围绕多物理场耦合问题,基于连续介质假设,采用非结构化网格和有限体积方法开发多物理场耦合并行计算软件GTEA。该软件包括计算流体力学、结构应力波传播、流 声耦合和声 固耦合等4个功能模块。介绍GTEA前处理网格读取、网格格式转换、求解器开发等关键技术。通过柴油机缸内工作过程模拟、船舶水动力计算、自然对流与辐射传热耦合作用、流场动力噪声计算和结构 声耦合计算等5个典型应用展示该软件的应用能力和适用范围。     

A High Order Control Volume Finite Element Method for Transient Heat Conduction Analysis of Multilayer Functionally Graded Materials with Mixed Grids

This paper describes a new two-dimensional(2-D)control volume finite element method(CV-FEM)for transient heat conduction in multilayer functionally graded materials(FGMs).To deal with the mixed-grid problem,9-node quadrilateral grids and 6-node triangular grids are used.The unknown temperature and material properties are stored at the node.By using quadratic triangular grids and quadratic quadrilateral grids,the present method offers greater geometric flexibility and the potential for higher accuracy than the linear CV-FEM.The properties of the FGMs are described by exponential,quadratic and trigonometric grading functions.Some numerical tests are studied to demonstrate the performance of the developed method.First,the present CV-FEM with mixed high-order girds provides a higher accuracy than the linear CV-FEM based on the same grid size.Second,the material properties defined location is proved to have a significant effect on the accuracy of the numerical results.Third,the present method provides better numerical solutions than the conventional FEM for the FGMs in conjunction with course high-order grids.Finally,the present method is also capable of analysis of transient heat conduction in multilayer FGM.     

基于DS18820分组方式测温系统设计

DS18B20用于多点测温时一般采用将多个DS18B20同时挂在微处理器的某根总线上,然后利用轮流读转换值的方式进行读温度数据,在测温点较多时,造成处理器系统开销明显增大,从而导致测温系统巡检周期明显增长,本文采用对DS18B20进行合理分组的方法,并结合软件上采取一定的措施,从而使巡检速度明显得到提高.     

基于AMESim的车辆悬架系统建模与仿真

介绍了高级工程系统仿真建模环境AMESim,利用该软件建立了车辆悬架系统的模型,并对该模型进行时域仿真分析,仿真过程中给出了阶跃输入下车辆轮胎的弹性形变、悬架系统对车辆垂直速度的响应以及对车身加速度的影响情况。结果表明,该仿真环境较为真实的模拟车辆悬架系统的实际响应,为其他车辆悬架系统的仿真与优化提供了基础模型。