Large eddy simulations of turbulent heat transfer in packed bed energy storage systems
Large eddy simulations of turbulent heat transfer in packed bed energy storage systems
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DOI：
10.1016/j.est.2022.106449
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发表时间：
2023-03
影响因子：
9.4
通讯作者：
M. Jadidi;H. K. Param;A. Revell;Y. Mahmoudi
中科院分区：
文献类型：
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作者：
M. Jadidi;H. K. Param;A. Revell;Y. Mahmoudi
研究了填充床储能系统中局部阻塞和流型对多孔区和非多孔区相互湍流相互作用的影响。为此，高保真孔尺度大涡模拟（LES）进行了两个PBESS配置，即完全堵塞和部分堵塞下的放电过程中，在3600，7200，和14400。流动的主要特征，包括流动沟道和泄漏，对传热率（努塞尔数）和压降的影响进行了研究，为各种流动雷诺数（Re）。结果表明，多孔区域内的沟道效应强烈影响温度分布，导致孔元上下两侧的努塞尔数出现局部极大值.对于部分堵塞，观察到在Re = 3600时，进入多孔块的79%的流量通过多孔流体界面从多孔区域泄漏到非多孔区域，当Re增加到14，400时，该流量减少26%。流动泄漏导致多孔块内部和多孔块上方形成反向旋转的涡对结构。在多孔体前缘靠近多孔体-流体界面处，多孔体的流动会引起局部最大值的出现，从而改变了驻点的位置。与完全堵塞配置相比，多孔块内部的温度分布对部分堵塞情况下的雷诺数的依赖性较小。最后，在Re = 3600和14,400时，完全阻塞的压力阻力分别约为部分阻塞的21.4和30.9倍。而在这些数值下，完全阻塞的平均数值比部分阻塞的平均数值高出近51.2%和57.3%。因此，阻塞整个流体流动区域可能不一定是最佳设计，因为它可能导致过度的压降而没有显著的传热增强。
The present paper aims to study the effect of partial blocking and flow regime on the mutual turbulent interplay between porous and non-porous regions in packed bed energy storage systems (PBESSs). To this end, high-fidelity pore-scale large eddy simulations (LES) are conducted for two PBESS configurations, namely full blockage and partial blockage under the discharge process at threeRenumbers 3600, 7200, and 14,400. The influences of the flow major features, including flow channelling and leakage, on the rate of heat transfer (Nusselt number) and pressure drop are investigated for various flow Reynolds (Re) numbers. Results demonstrate that the channelling effect inside the porous region strongly affects the temperature profiles and leads to local maximum peaks of Nusselt (Nu) number on the upper and lower sides of pore elements. For the partial blockage, it is observed that 79 % of the flow entering the porous block leaks from the porous region into the non-porous region through the porous-fluid interface atRe= 3600, which reduces by 26 % as theReincreases to 14,400. The flow leakage leads to the formation of counter-rotating vortex pair structures inside and over the porous block. It also causes local maximum peaks ofNunumber at the lower sides of pore elements and changes the stagnation points' position at the leading edge of the porous block near the porous-fluid interface. Compared to the full blockage configuration, temperature profiles inside the porous block are less dependent on theRenumber for the partial blockage case. Finally, the pressure drag force for the full blockage is about 21.4 and 30.9 times that of partial blockage atRe= 3600 and 14,400, respectively. Whereas at theseRenumbers, the averageNunumber for the full blockage is nearly 51.2 % and 57.3 % higher than that of the partial blockage. Consequently, blocking the entire fluid flow area may not necessarily be the best design, since it may result in excessive pressure drops without significant heat transfer enhancement.