A numerical investigation of transient natural convective heat transfer to isobutane in the supercritical region
A numerical investigation of transient natural convective heat transfer to isobutane in the supercritical region
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DOI：
10.1016/j.molliq.2017.11.074
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发表时间：
2018
影响因子：
6
通讯作者：
G. J. Reddy;H. Basha;N. S. V. Narayanan
中科院分区：
文献类型：
--
作者：
G. J. Reddy;H. Basha;N. S. V. Narayanan
本文数值研究了超临界流体层流绕流圆柱的非定常自由对流流动。两个新的热力学模型的SCF已被认为是。在此基础上，基于Redlich-Kwong状态方程（RK-EOS）和货车德尔瓦尔斯状态方程（VW-EOS），得到了两个新的超临界流体热膨胀系数方程。结果表明，热膨胀系数是温度、压力和压缩因子的函数。用RK-EOS估算的体积热膨胀系数的解析值与实验值更接近，证实了RK-EOS比VW-EOS具有更高的精度。得到了垂直圆柱上SCF流动的无量纲偏微分方程组，它们是时间相关的、高度非线性的和耦合的。因此，这些复杂的方程求解使用计算技术，如Crank-Nicolson隐式有限差分格式。数值模拟了一个著名的化合物，如异丁烷在其临界点的区域。结果有关的速度，温度，平均动量和热输运系数剖面整个边界层的图形显示和讨论的控制参数的各种值。从所获得的图形数据中可以清楚地看出，在超临界条件下，温度比压力起着突出的作用。
Current research article investigates numerically the time-dependent laminar free convective supercritical fluid (SCF) flow past a vertical cylinder. Two new thermodynamic models for the SCF have been considered. Based on these proposed models, in SCF two new equations for thermal expansion coefficient is obtained on the basis of Redlich-Kwong equation of state (RK-EOS) and Van der Waals equation of state (VW-EOS). It is shown that the thermal expansion coefficient is a function of temperature, pressure and compressibility factor. The evaluated analytical values of volumetric thermal expansion coefficient using RK-EOS are closer to the experimental values which confirm the greater accuracy of proposed RK-EOS as compared to that of VW-EOS. The set of non-dimensional partial differential equations for the SCF flow over a vertical cylinder are obtained and they are time-dependent, highly non-linear and coupled. Therefore, these complex equations are solved using the computational techniques such as Crank-Nicolson implicit finite difference scheme. Numerical simulations are performed for a well-known chemical compound like isobutane in the region of its critical point. The results concerning the velocity, temperature, and average momentum and heat transport coefficient profiles across the boundary layer are shown graphically and discussed for various values of control parameters. From the obtained graphical data, it is clear that temperature plays a prominent role than the pressure under supercritical condition.