Hydraulic and heat transfer characteristics of slush hydrogen in a circular pipe under terrestrial and microgravity conditions
Hydraulic and heat transfer characteristics of slush hydrogen in a circular pipe under terrestrial and microgravity conditions
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DOI：
10.1016/j.ijheatmasstransfer.2017.03.024
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发表时间：
2017-07
影响因子：
5.2
通讯作者：
P. Zhang;X. Shi
中科院分区：
文献类型：
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作者：
P. Zhang;X. Shi
氢浆是固态氢和液态氢的混合物。与纯液氢相比，由于它的致密性，它可以用作火箭和空间助推器的燃料。基于欧拉-欧拉模型和颗粒流动力学理论，建立了一个数值模型，研究了重力和微重力条件下圆管内浆氢的水力和传热特性。数值模型首先验证了文献中报道的实验结果。对不同入口速度和固体体积分数的浆氢流动进行了数值模拟，研究了出口截面的固体体积分数分布和速度分布。考虑到浆氢输送的实际应用，本文还研究了在陆地条件下浆氢在倾斜管道中的水力特性和在微重力条件下浆氢在水平管道中的水力特性。结果表明，重力对浆氢的固相体积分数分布和压降有显著影响。研究表明，利用半融氢可以有效地局部降低流体的温度，从而抑制液氢的汽化。小直径的固体氢颗粒可以改善固液两相间的传热，加速固体氢的熔化。结果表明，入口速度和固体体积分数的增加对局部换热系数都有积极的影响。
Slush hydrogen is a mixture of solid hydrogen and liquid hydrogen. Compared with pure liquid hydrogen, it can be used as the fuel of rocket and space booster due to its densified feature. In the present study, a numerical model is built based on the Eulerian-Eulerian model and the kinetic theory of granular flow to investigate the hydraulic and heat transfer characteristics of slush hydrogen in a circular pipe under both terrestrial and microgravity conditions. The numerical model is first validated by the experimental results reported in the literature. The flow of slush hydrogen with different inlet velocities and solid volume fractions are numerically studied to investigate the solid volume fraction distribution and velocity profile of the outlet cross-section. Considering the transportation of slush hydrogen in practical applications, the hydraulic characteristics of slush hydrogen in an inclined pipe under terrestrial condition and in a horizontal pipe under microgravity are also investigated. The results show significant influence of the gravity on the solid volume fraction distribution and pressure drop of slush hydrogen. The heat transfer of slush hydrogen is also studied, which shows that the temperature of fluid can be locally decreased sufficiently using slush hydrogen such that the vaporization of liquid hydrogen can be suppressed. Solid hydrogen particle with small diameter can improve heat transfer between the solid phase and liquid phase, and the melting of solid hydrogen is accelerated. It is clarified that the increases of both the inlet velocity and solid volume fraction show positive effects on the local heat transfer coefficient.