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Ｔｈｒｅｅ ｄｉｍｅｎｓｉｏｎａｌ ｒａｎｄｏｍ ｇｅｏｍｅｔｒｉｃ ｓｔｒｕｃｔｕｒｅ ｏｆ ｐｅｌｌｅｔｓ ｐａｃｋｅｄ ｂｅｄ ｗａｓ ｍｏｄｅｌｅｄ ｕｓｉｎｇ ｔｈｅ ｄｉｓｃｒｅｔｅ ｅｌｅｍｅｎｔ ｓｏｆｔｗａｒｅ ＬＩＧＧＧＨＴＳ. Ｌａｒｇｅ ｅｄｄｙ ｓｉｍｕｌａｔｉｏｎ ｍｅｔｈｏｄꎬ ｔｗｏ-ｔｅｍｐｅｒａｔｕｒｅ ｍｏｄｅｌ ａｎｄ ＥＢＵ-Ａｒｒｈｅｎｉｕｓ ｃｏｍｂｕｓｔｉｏｎ ｍｏｄｅｌ ｗｅｒｅ ｅｍｐｌｏｙｅｄ ｔｏ ｓｉｍｕｌａｔｅ ｔｈｅ ｐｒｅｍｉｘｅｄ ｃｏｍｂｕｓｔｉｏｎ ｐｒｏｃｅｓｓ ｏｆ ｍｅｔｈａｎｅ-ａｉｒ ｉｎ ｔｈｅ ｒａｎｄｏｍｌｙ ｐａｃｋｅｄ ｂｅｄ. Ｔｈｅ ｃａｌｃｕｌａｔｅｄ ｒｅｓｕｌｔｓ ａｒｅ ｃｏｍｐａｒｅｄ ｗｉｔｈ ｅｘｐｅｒｉｍｅｎｔ ｄａｔａ ｔｏ ｖｅｒｉｆｙ ｅｆｆｅｃｔｉｖｅｎｅｓｓ ｏｆ ｔｈｅ ｍｏｄｅｌ. Ｔｈｅ ｓｔｒｕｃｔｕｒｅ ａｎｄ ｔｈｅ ｓｈａｐｅ ｏｆ ｔｈｅ ｆｌａｍｅ ａｎｄ ｔｈｅ ｔｅｍｐｅｒａｔｕｒｅ ｄｉｓｔｒｉｂｕｔｉｏｎ ｉｎ ｔｈｅ ｐａｃｋｅｄ ｂｅｄ ｗｅｒｅ ａｎａｌｙｚｅｄ. Ｔｈｅ ｓｉｍｕｌａｔｉｏｎ ｒｅｓｕｌｔｓ ｓｈｏｗ ｔｈａｔ ｔｈｅ ｔｅｍｐｅｒａｔｕｒｅ ｏｆ ｓｏｌｉｄ ｉｓ ｈｉｇｈｅｒ ｔｈａｎ ｔｈａｔ ｏｆ ｇａｓ ｏｎ ｔｈｅ ｓａｍｅ ｈｅｉｇｈｔ ｏｆ ｔｈｅ ｐａｃｋｅｄ ｂｅｄ ｄｕｒｉｎｇ ｔｈｅ ｌａｔｅ ｓｔａｇｅ ｏｆ ｃｏｍｂｕｓｔｉｏｎꎬ ｗｈｉｃｈ ｒｅｆｌｅｃｔｓ ａ ｇｏｏｄ ｔｈｅｒｍａｌ ｓｔｏｒａｇｅ ｃａｐａｃｉｔｙ ｏｆ ｔｈｅ ｐｏｒｏｕｓ ｍｅｄｉｕｍ. Ｔｈｅ ｈｅｉｇｈｔ ｄｉｆｆｅｒｅｎｃｅ ｏｆ ｔｈｅ ｆａｍｅ ｓｕｒｆａｃｅ ｂｅｔｗｅｅｎ ｔｈｅ ｔｕｂｅ ｗａｌｌ ａｎｄ ｔｈｅ ｃｅｎｔｅｒ ｉｎ ｔｈｅ ｐａｃｋｅｄ ｂｅｄ ｉｓ ｍｕｃｈ ｓｍａｌｌｅｒ ｔｈａｎ ｔｈａｔ ｉｎ ｔｕｂｅ ｗｉｔｈｏｕｔ ｐｏｒｏｕｓ ｍｅｄｉａꎬ ｗｈｉｃｈ ｓｕｇｇｅｓｔｓ ｔｈａｔ ｔｈｅ ｆｌａｍｅ ｉｓ ｄｉｖｉｄｅｄ ｂｙ ｔｈｅ ｐａｃｋｅｄ ｂｅｄ ａｎｄ ｔｈｅｎ ｔｈｅ ｕｎｉｆｏｒｍｉｔｙ ａｎｄ ｓｔａｂｉｌｉｔｙ ｏｆ ｔｈｅ ｃｏｍｂｕｓｔｉｏｎ ｗｉｔｈｉｎ ａ ｐｏｒｏｕｓ ｍｅｄｉｕｍ ａｒｅ ｉｍｐｒｏｖｅｄ. [ABSTRACT FROM AUTHOR]

Discrete element software LIGGGHTS is introduced to reproduce the forming process of sphere packed bed by gravity， and a 3D random geometric model similar to the actual accumulation structure is presented. Two ordered models， the in-line packed model and the staggered packed model， are also established to contrast with the random packed model. CFD software of Fluent 14.0 is employed to study the turbulence flows in the packed bed. The effectiveness of the random model is validated by analysis of the macroscopic pressure drop and the resistance coefficient， and the velocity field and the turbulence parameters of the three structures are predicted and discussed. Simulation results show that the macroscopic resistance coefficient and the macroscopic pressure drop of the random packed bed model are consistent with the classical formula of Ergun， with maximum relative error less than 6%. Compared with the orderly packed bed， the random packed model is characterized with more homogeneous velocity field， larger tail vortex size， stronger disturbance and extremely larger turbulence dissipation. [ABSTRACT FROM AUTHOR]

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