共查询到15条相似文献,搜索用时 80 毫秒
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针对低温容器夹层真空失效工况,建立了低温容器夹层真空度与通过内罐壁面热流密度的理论模型,结合ANSYS-FLUENT软件对某立式低温容器内的液氮蒸发过程进行了仿真模拟,研究了初始充满率为50%时,低温容器内罐空间温度及压力随夹层真空度变化的规律。结果表明,随着夹层真空度降低,通过低温容器内罐壁面的平均热流密度增大,内罐中液体温度升高速率增大;当夹层真空完全失效时,内罐压升率分别是夹层真空度为10-3 Pa、1 Pa和10 Pa时的10.4倍、5倍和1.2倍。 相似文献
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《低温与超导》2020,(8)
支撑结构作为低温容器的关键部件,跨常温—低温温区工作,并承接充装低温液体的内筒体重量,其性能好坏很大程度决定了低温容器技术的发展。本文介绍BOG再液化装置用低温容器径向支撑的结构设计,并进行热力耦合有限元分析,得到工作条件下结构的热流密度场、温度场、应力场和位移场。结果表明:该径向支撑平均热流密度0.003 1 W/mm~2,玻璃钢管与KF真空内丝快装接头接触部位的温度已接近热端温度,可见绝热效果良好;最大热应力16.212 MPa,位于玻璃钢管的通气孔周围,满足强度要求;最大位移变形量0.001 7 mm,位于热端,在材料允许变形范围内。通过分析,验证了低温容器径向支撑结构的合理性,有效提升了低温容器的机械性能和绝热性能。 相似文献
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V. G. Baidakov 《Journal of Engineering Thermophysics》2007,16(3):109-118
The kinetics of spontaneous boiling-up of superheated binary solutions of cryogenic liquids is studied. Within the framework
of the Kramers-Zeldovich method, an expression is obtained for the steady state rate of homogeneous nucleation in a solution
that takes into account free-molecular and diffusion regimes of the substance supply to a growing bubble. Viscous and inertial
forces are also taken into account in the study of the nucleus growth dynamics. The work of critical nucleus formation is
determined within the framework of the Gibbs and van der Waals capillarity theories. The dependence of the surface tension
of critical bubbles in the solution on their size is investigated.
The temperature of attainable superheating and nucleation rates in superheated solutions of cryogenic liquids with complete
or partial solubility of the components are determined by a method of lifetime measurement. The experiments were conducted
in a wide range of pressures and solution concentrations. The measurement results are compared with the theory of homogeneous
nucleation taking or not taking into account the size effect in nucleation. It has been found that, by taking into account
the size dependence of the surface tension of a nucleus, better agreement between the theory and experiment is obtained. The
boundary of essential instability of the solution, that is, the diffusion spinodal, is computed. 相似文献
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In this Letter, an N-body theory for the radiative heat exchange in thermally nonequilibrated discrete systems of finite size objects is presented. We report strong exaltation effects of heat flux which can be explained only by taking into account the presence of many-body interactions. Our theory extends the standard Polder and van Hove stochastic formalism used to evaluate heat exchanges between two objects isolated from their environment to a collection of objects in mutual interaction. It gives a natural theoretical framework to investigate the photon heat transport properties of complex systems at the mesoscopic scale. 相似文献
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CMOS电路低温特性及其仿真 总被引:1,自引:0,他引:1
本文采用0.25微米工艺制备了CMOS器件和电路,通过对300K、77K和4K温度下器件和电路特性的测量,研究了工作温度降低对CMOS电路特性的影响.通过讨论MOSFET器件和互连线主要特性参数随温度的变化情况,修改了常温CMOS BSIM3模型以及互连线参数,建立了77K、4K温度下的低温电路仿真模型.利用上述新建立的低温电路仿真模型对CMOS电路进行仿真,并将仿真结果与实际测量结果比较,获得了比较一致的结果.研究表明在4K温度下CMOS电路的工作性能大约有50%到60%的改善. 相似文献