螺杆膨胀机有机朗肯循环有机工质研究

从工程项目实际应用角度出发,根据螺杆膨胀机的特性提出了有机朗肯循环(ORC)有机工质的筛选准则。根据等熵理论建立了理论模型,对常推荐的9种有机工质,分别从压差、体积流量、内容积比等方面进行了对比研究。模拟结果表明:并没有一种工质能够很好地满足所提出的筛选准则,但R245fa,R600a具有比较平均的性能可以选用,还需要研究、开发适用于螺杆膨胀机的有机工质。搭建了干式螺杆膨胀机ORC实验平台,验证了R245fa作为工质的可行性,并讨论了机组效率、工质泵效率和排气温度等问题。研究对螺杆膨胀机ORC有机工质的选择指出方向,对ORC产业发展具有理论和实践意义。     

焦炉煤气双级螺杆压缩机的研究与应用

针对焦炉煤气综合利用项目的高排压需求，分别从双级螺杆压缩的工艺和机械开展研究。重点分析级间压力选用及稳定原理，提出压缩过程物料能量计算手段；优化传统双级压缩流程，提高运行经济性及机组可操作性。调整二级压缩机转子结构，并设置平衡盘，克服受力加大带来的不利因素；分析不同主机布置方式的优劣，满足项目实际需求。最终实现在焦炉煤气提氢等工艺中的应用。     

基于Aspen Plus与Matlab联用的ORC系统优化

ORC系统设计过程中,工质的选用和操作参数的选定是设计的关键。为辅助进行ORC系统的设计和优化,先采用Aspen进行ORC模拟模型建立,选取了几种常用工质,使用ActiveX实现了Matlab和Aspen的联用,设计了计算程序。以某公司35 t/h的150℃热水提供工业余热、冷却器的冷凝温度为42℃的ORC系统作为案例,进行了优化计算,最终得到该工况下R134A工质的输出功率最高,输出功率为201 kW,工质的蒸发压力为27 bar,蒸发温度为81℃,流量为56 900 kg/h。     

智能仪表中的量程切换电路

分析智能仪表中常见的量程切换电路原理,给出了常用切换器件的特性与误差分析,提出了避免开关电阻影响的若干设计原则,并给出电工测量仪表中的几种实用的量程切换电路.     

小型矿用本安型DC-DC隔离电源模块设计

矿用本安电源上电时,容易因负载电容充电造成本安电源误动、可靠性变差;因负载供电线路压降差异导致负载可靠性变差。为解决以上问题,对负载端直流-直流(DC-DC)电源模块进行研究,提出一种新的本安型DC-DC隔离电源模块的设计方案。在该方案中采用特有的三级缓启动电路,具有开机冲击小、输入端等效电容小等特点;采用高稳定度的小环反馈式稳压结构既保证了电源的动态响应速度,又能避免输入端长线造成的自激振荡。     

孕育剂及孕育工艺对球铁组织及性能的影响

研究了含有Sr、Bi的孕育剂和"一次孕育+随流孕育"处理工艺对球铁汽车转向节铸件及Y型试块中石墨形态、基体组织和力学性能的影响.结果表明:用含Sr的孕育剂处理后基体组织中存在"牛眼状"铁索体和大量的珠光体,伸长率和冲击韧性低下;用含Bi的孕育剂处理后基体组织中有较多的铁素体,经过"一次孕育+随流孕育"处理后主要为铁素体组织.后两种工艺处理后,石墨球数量多、球化率在80%以上,球铁的综合力学性能也有明显改善.     

关于小井眼射孔技术的创新研究

文章介绍了小直径井眼射孔的技术内容、技术指标、现场实验及安全措施等几方面内容。为更好地服务于市场、贡献于企业，此项技术有必要在生产中加以推广。     

无溶剂型水溶性农药体系的研制

以分子量为50～2000的新型两亲高分子为乳化剂,硅藻土为悬浮剂,A13为转相剂,通过研磨等工艺制成10%功夫菊酯无溶剂型水乳剂农药.该水乳剂农药化学稳定性好,冷热贮前后的流动性好,不结块,无析水、析油现象.     

Numerical and experimental studies on the effectiveness of time-varying electromagnetic fields in reducing electron density

When an aircraft or a hypersonic vehicle re-enters the atmosphere, the plasma sheath generated can severely attenuate electromagnetic wave signals, causing the problem of communication blackout. A new method based on time-varying E × B fields is proposed to improve on the existing static E × B fields and mitigate the radio blackout problem. The use of the existing method is limited by the invalid electron density reduction resulting from current density j = 0 A m^-2in plasma beyond the...     

Mitigation of blackout problem for reentry vehicle in traveling magnetic field with induced current

In this paper, a novel solution mitigating the radio blackout problem is proposed, which improves existing traveling magnetic field (TMF)-based methods. The most significant advance lies in replacing the external injection with self-induced current, which does not require electrodes. The improved analytical model is derived to evaluate the electron density reduction taking into consideration the self-induced current for various TMF velocities. The plasma reduction performance is analyzed for several conditions including the total absence of injected current. The results show that the velocity may be used to trade off the injected current and, when sufficiently large, eliminates the need for an injected current while mitigating radio blackout. The effectiveness of this solution to the blackout problem is demonstrated in commonly used aerospace communication bands. With a field strength of less than 0.15 T, increasing the velocity from 40 m s⁻¹ to 3100 m s⁻¹ is all that is required to obviate the need for an injected current. Moreover, typical reduction ratios for electronic density tolerance (2, 1.9, 1.75 and 3 times for the L-, S-, C- and X-bands, respectively, at an altitude of 40 km) remain unchanged. Increasing the velocity of the TMF is much easier than injecting current via a metal electrode into a high-temperature flow field. The TMF method appears practical in regard to possible future applications.