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기체유동층에서 온도와 높이가 난류흐름영역으로의 전이속도에 미치는 영향

Effects of Temperature and Height on the Transition Velocity to Turbulent Flow Regime in a Gas Fluidized Bed

류호정 최정후 김상돈 손재익 선도원 이창근

Ryu HJ Choi JH Kim SD Son JE Shun DW Yi CK

HWAHAK KONGHAK, April 1999, 37(2), 178-185(8), NONE

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Abstract

난류유동층 전이유속(U_c)에 미치는 온도와 분산판으로부터의 높이영향을 이해하기 위해서 기체유동층(직경 0.1 m, 높이 2.1 m)에서 온도(15-500 ℃), 압력요동 측정지점의 높이(0.02-0.10, 0.10-0.15, 0.15-0.24, 0.24-0.29, 0.02-1.97 m), 입자크기(평균입경 0.134mm, 0.256mm)의 변화에 따른 난류유동층 전이유속을 측정하였다 난류유동층 전이유속은 온도가 증가함에 따라 증가하였으며, 분산판으로부터 높이가 증가함에 따라 감소하였다. 본 실험결과와 기존에 보고된 난류유동층 전이유속에 관한 상관식들을 비교하였다. 기존 상관식들은 난류유동층 전이유속에 미치는 온도와 높이의 영향을 해석하기에 미흡하였다.

Qualitative effects of temperature and height from the distributor plate on the transition velocity to turbulent_x000D_ flow regime(U_c) have been measured in a gas fluidized bed(0.1 m i.d. and 2.1 m height) using sand as bed material. Bed temperature(15-500 ℃), height from the distributor plate(0.02-0.10, 0.10-0.15, 0.15-0.24, 0.24-0.29, 0.02-1.97 m), and mean particle size(0.134, 0.256 mm) were considered as experimental variables. The transition velocity to turbulent flow regime increased with increasing bed temperature, however, decreased with increasing height from the distributor plate. The previous_x000D_ correlations on transition velocity to turbulent flow regime compared with the measured values. Most correlations reported in the literature appeared inadequate to determine the effects of temperature and height from the distributor plate on transition velocity to turbulent flow regime.

Keywords

Gas Fluidization Transition Velocity Turbulent Flow Regime Height Effect Temperature Effect

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