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低温系统的预冷过程和计算 总被引:5,自引:0,他引:5
对低温系统的预冷过程做了分析,研讨了各种因素对预冷过程的影响,介绍了预冷耗液量计算公式的推导,给出了LHe,LH2,LN2和LO2预冷耗液量计算图。利用计算图可以方便地计算预冷耗液量。 相似文献
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李荣典 《中国新技术新产品》2014,(8):123-124
本文从我国燃气事业的发展现状出发,结合当前天然气的供需矛盾引申出液化天然气(LNG)储配站的建设、预冷和投产,深入论述了LNG储罐预冷的常规做法,指出了其中的不足,并针对常规做法中的不足进行了革新,对LNG储罐的预冷有很大的参考作用。 相似文献
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实施蔬菜产地预冷,完善低温冷藏链 总被引:20,自引:2,他引:20
本文讨论了蔬菜产地预冷的必要性,具体介绍了几种常用的预冷方法及其预冷效果,并就我国目前的实际情况提出了切实可行的实施方案,此外,还就预冷技术今后的研究重点进行了初步探讨。 相似文献
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实施蔬菜产地预冷 完善低温令藏链 总被引:1,自引:0,他引:1
本文计论了蔬菜产地预冷的必要性,初步介绍了常用的预冷方式,并根据预冷效果进行了比较,简述了国、内外预冷发展的历史及现状,并就预冷技术今后的研究方向,研究重点有应用前景发表了个人看法。 相似文献
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在低温管路的预冷过程中总是要产生两相流的。由于预冷过程随时变化,使得流动特性更加复杂化。当低温液体进入常温管路,在冷却管路入口段的过程中液体将剧烈汽化。冷蒸汽沿管路前进,并预冷管路。蒸汽在管路出口处的温度介于蒸汽饱和温度和管路初始温度之间。 相似文献
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从绝热材料的准备、内容器的缠绕、内外容器罐体的套合到夹层抽真空等工艺要点入手,对高真空多层绝热槽车的制造工艺进行了详细叙述。 相似文献
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An estimation method of the plane directional thermal conductivity of fibrous insulations using the cyclic heat method and the transient hot-wire method is proposed. By assuming that the thermal conductivity
h
of anisotropic materials measured by the transient hot-wire method is equivalent to that of the isotropic materials which have the same bulk density and specific heat c as the anisotropic materials, the thermal conductivity
h
is shown to be equal to
, which is a geometrical mean of the thermal conductivities in the direction of the plane
x
and the thickness
y
of the anisotropic materials. For an alumina silica blanket (=125 kg·m–3), the thermal conductivities
h
,
x
, and
y
were measured in the temperature range between –140 and 300°C using the transient hot-wire method for
h
and the cyclic heat method for
x
and
y
. In the same way, the thermal conductivities
h
,
x
, and
y
of a rock wool (=121 kg·m–3) insulation were also measured in the temperature range, 100 to 600°C. From a comparison of the measured results with the estimated values of
x
, it is confirmed that the proposed method can estimate the measured values reasonably well. 相似文献
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低温推进剂贮箱增压过程的传热传质数学模拟 总被引:1,自引:0,他引:1
针对火箭发动机地面试验中低温液氧贮箱的预增压和增压过程建立了气相空间的传热、传质数学模型.运用实际气体的状态方程、连续性方程、能量守恒方程以及推进剂与气相空间的传热、传质方程等组成了关于气相空间参数的微分方程组,并运用四阶Runge-Kutta算法对其进行求解.获得了气相空间的压力、温度、增压气体流量、液氧挥发速率以及贮箱壁温等参数的变化规律.结果表明,在发动机启动前的预增压过程中,气相空间的温度和压力急剧增加,液氧的挥发速率也增加很快;发动机启动后的保持增压阶段,由于气相空间的体积不断发生变化,气相空间参数的变化趋于平缓,液氧表面向气相空间的传质速率也趋于稳定. 相似文献
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《低温学》2015
Sufficient knowledge of thermal performance and pressurization behaviors in cryogenic tanks during rocket launching period is of importance to the design and optimization of a pressurization system. In this paper, ground experiments with liquid oxygen (LO2) as the cryogenic propellant, high-temperature helium exceeding 600 K as the pressurant gas, and radial diffuser and anti-cone diffuser respectively at the tank inlet were performed. The pressurant gas requirements, axial and radial temperature distributions, and energy distributions inside the propellant tank were obtained and analyzed to evaluate the comprehensive performance of the pressurization system. It was found that the pressurization system with high-temperature helium as the pressurant gas could work well that the tank pressure was controlled within a specified range and a stable discharging liquid rate was achieved. For the radial diffuser case, the injected gas had a direct impact on the tank inner wall. The severe gas-wall heat transfer resulted in about 59% of the total input energy absorbed by the tank wall. For the pressurization case with anti-cone diffuser, the direct impact of high-temperature gas flowing toward the liquid surface resulted in a greater deal of energy transferred to the liquid propellant, and the percentage even reached up to 38%. Moreover, both of the two cases showed that the proportion of energy left in ullage to the total input energy was quite small, and the percentage was only about 22–24%. This may indicate that a more efficient diffuser should be developed to improve the pressurization effect. Generally, the present experimental results are beneficial to the design and optimization of the pressurization system with high-temperature gas supplying the pressurization effect. 相似文献
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推进剂与贮箱液固耦合振动的动力学分析 总被引:2,自引:1,他引:1
分析液体燃料运载火箭的推进剂及贮箱的耦合振动时,为了精确建模、工程化快速计算及为火箭整体系统提供液固耦合燃料系统等效模态参数,根据有限元方法得到包含液体节点压力和结构节点位移的非对称形式的耦合动力学方程组,将表征液体运动的节点压力缩聚到液体自由面,使得方程对称化。通过等价Laplace方程边值问题的求解,得到耦合动力学方程中液体对结构的附加质量矩阵、附加刚度矩阵及耦合项。简易贮箱液固耦合模态分析的算例结果表明,该分析方法能够精确、快速地获得液固耦合系统的模态频率等动力学特性。从而使得高效率的液固耦合动力学分析在工程上应用成为可能,并为运载火箭等复杂液固耦合结构的有限元建模由简化模型向三维精确模型建立和工程化应用建立了基础。 相似文献