Numerical simulations of the piston effect for near-critical fluids in spherical cells under small thermal disturbance
Numerical simulations of the piston effect for near-critical fluids in spherical cells under small thermal disturbance
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DOI：
10.1016/j.ijthermalsci.2016.03.019
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发表时间：
2016-09
影响因子：
4.5
通讯作者：
Zhan-Chao Hu;Xin‐Rong Zhang
中科院分区：
文献类型：
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作者：
Zhan-Chao Hu;Xin‐Rong Zhang
在汽液临界点附近，热力学和输运性质的强烈异常引起活塞效应。在本研究中，活塞效应的球形细胞填充近临界流体在零重力和小的热扰动条件下，通过数值求解的热力学模型进行了研究。结果表明，近临界流体的特殊性质决定了其具有典型的体温快速响应特性和高而稳定的温度效率。特别地，通过对八种近临界流体的模拟，建立了一种无因次化方法来研究比热比对活塞效应的影响。结果表明，比热容比是一个有效的指标，它与无量纲体温度变化呈负相关。本文还研究了近临界二氧化碳气体的特征长度和边界条件对活塞效应的影响。此外，还讨论和总结了边界热流和总传热的一些规律。
Near the liquid–vapor critical point, strong anomalies in thermodynamic and transport properties induce the piston effect. In the present study, the piston effect is investigated in spherical cells filled with near-critical fluids under zero gravity and small thermal disturbance conditions by numerically solving the thermodynamic model. The results show typical fast-responding bulk temperature, together with high and stable temperature efficiency, which is determined by the particular nature of near-critical fluids. Particularly, a nondimensionalization method is developed to study the influences of the specific heat ratio on the piston effect by simulations for eight near-critical fluids. Results show the specific heat ratio is an efficient indicator, which is negatively correlated with the nondimensional bulk temperature change. The influences of the characteristic length and the boundary conditions on the piston effect are also studied for near-critical carbon dioxide. In addition, some rules concerning the boundary heat flux and the overall heat transfer are also discussed and concluded.