排序方式: 共有14条查询结果,搜索用时 31 毫秒
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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。 相似文献
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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。 相似文献
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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。 相似文献
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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... 相似文献
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Shaoshuai GUO 《等离子体科学和技术》2020,22(12):125301
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. 相似文献