基于热电效应的高效环控系统

部分空间科学实验对环境温度有较高的要求，环境温度高于或低于空间科学系统能够提供的热沉温度，需要有可靠有效的加温降温处理措施。使用可靠性强的热电制冷片作为制冷制热方式和气液换热器二次换热来实现环境温度控制的需求，并对不同流体温度制冷制热效果进行分析，结果表明流体温度和目标温度差越小，热电制冷制热的效果越好。在环境温度制冷工况中，热电单元数量随电流增加先减少后增加，在制热工况中则单调递减，设计中需按照制冷工况进行热电单元数量的确定。当流体温度接近制冷制热的目标温度时，会出现整个系统总效率优于热电系统效率的区间。通过对热电单元和气液换热器的组合系统的性能计算，提供一种适于热电环控系统的计算方法和部件选型思路，对空间站环控系统的设计有重要参考意义。     

Effects of CMC and Micelle Formation on the Removal of Sodium Benzoate or Sodium Stearate in a Sodium Aluminate Solution

JOM - Micelle formation over a critical micelle concentration (CMC) is related to the economic removal of organics in a sodium aluminate solution. In this research, removal of organics was...     

埋地管道泄漏内封堵装置设计与研究

针对流体输送埋地管道泄漏问题,设计了一种利用管道机器人携带封堵气囊进行快速应急封堵修复的埋地管道泄漏内封堵装置。采用矩阵变换方法建立了牵引系统驱动轮过弯方程,利用MATLAB软件对过弯方程进行了验证,同时利用ADAMS软件仿真分析过弯路径与驱动轮转角对牵引系统行走速度的影响。研究结果表明:由两个串联封堵器组成的应急封堵系统可满足复杂工况下的管道泄漏封堵要求;牵引系统驱动轮在弯管内部行走时,单轮速度呈周期性变化,但三个驱动轮整体周期运动特性一致;驱动轮转角在25°~40°时,牵引系统行走速度与驱动轮转角成正比,且转角为30°时驱动效果最好。该内封堵装置的结构设计可为管道泄漏应急封堵领域装备的研发提供重要参考。     

Effects of hydrolysis of precursor on the structures and properties of polymer-derived SiBN ceramic fibers

In this paper, polyborosilazane precursor was synthesied from HMDZ, HSiCl₃, BCl₃ and CH₃NH₂ using a multistep method. By controlling the storage conditions, parts of the polyborosilazane fibers were hydrolyzed. FT-IR, NMR, XRD, TEM and monofilament tensile strength test were employed to study the effects of hydrolysis of precursor on the structures and properties of polymer-derived SiBN ceramic fibers. FT-IR and NMR results indicate that Si-N group in PBSZ reacts with H₂O to form Si-O-Si group. After pyrolysis reaction at 1400℃, Si-O-Si group will finally transformed into highly ordered cristobalite and β-quartz, resulting in formation of the wrinkled surface of the obtained SiBN ceramic fiber. The strip-like defects on fiber surface, according to monofilament tensile strength test, had a significant effect on mechanical property of the obtained SiBN ceramic fiber and caused no increase in fiber tensile strength of hydrolytic polyborosilazane fiber before and after pyrolytic process.     

N,N'-二(2-羟丙基)哌嗪-硫酸钠-水三元体系相平衡测定与计算

采用等温溶解平衡法测定N,N′-二(2-羟丙基)哌嗪(HPP)?Na2SO4?H2O三元体系在273.15和298.15 K下的相平衡数据，采用湿渣法测定其平衡固相数据，绘制等温相图。用改进的单组分电解质Pitzer方程计算该体系中Na2SO4和Na2SO4?10H2O的溶解平衡常数，并对相平衡数据进行理论计算。结果表明，273.15 K时存在3个结晶区，298.15 K时存在4个结晶区。HPP的存在降低了Na2SO4和Na2SO4?10H2O的相转变温度，使298.15 K下的相图中存在Na2SO4的结晶区域，且273.15和298.15 K的相图中不存在纯HPP的结晶区域。理论计算与实验数据的均方根偏差不高于0.0290，表明相平衡数据计算值与实验值较吻合，证实了改进的单组分电解质Pitzer方程适用于该体系计算。