Effect of heat transfer on the instabilities and transitions of supercritical CO2 flow in a natural circulation loop
Effect of heat transfer on the instabilities and transitions of supercritical CO2 flow in a natural circulation loop
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DOI：
10.1016/j.ijheatmasstransfer.2010.05.030
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发表时间：
2010-09
影响因子：
5.2
通讯作者：
Lin Chen;Xin‐Rong Zhang;H. Yamaguchi;Zhong‐sheng Liu
中科院分区：
文献类型：
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作者：
Lin Chen;Xin‐Rong Zhang;H. Yamaguchi;Zhong‐sheng Liu
系统稳定性在自然循环应用中至关重要。研究表明，考虑到超临界CO2流体的温度敏感性，自然对流系统中的超临界CO2流动具有新的特性。本文对超临界CO2自然循环回路进行了数值模拟，研究了该系统的流动转变和不稳定性。在本模型中，热沉温度保持在298 K，而热源温度作为控制参数在310- 1023 K范围内变化。首次发现，对于本模型，存在一个过渡热源温度，在该温度下，系统随温度的升高由不稳定的反复逆流转变为稳定的单向流动，这与以往对正常流体的研究有着根本的不同.特别是，临界转变流体温度被发现是在第二个“伪临界温度”附近，在375 K左右，流体性质经历主要转变与温度的增加。此外，还详细分析了流动稳定性的特点。
System stabilities are of critical importance in natural circulation applications. Investigations show that for supercritical CO2flow new behaviors can be seen in natural convection systems considering its temperature-sensitive physical properties. In the present study, numerical simulations on a supercritical CO2natural circulation loop have been carried out to investigate the flow transitions and instabilities of such systems. In the present model heat sink temperature is kept at 298K while heat source temperature varies in the range of 310–1023K as a controlling parameter. It is found for the first time that for the present supercritical CO2model there exists a transition heat source temperature at which the system changes from unstable repetitive-reversal flow into stable one-direction flow with the increase of temperature, which is fundamentally different from previous studies for normal fluid. In particular, the critical transition fluid temperature is found to be near the second “pseudo-critical temperature” at around 375K where the fluid properties experience major transitions with the increase of temperature. In addition, characteristics of flow stability behaviors are also analyzed in detail.