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IJCT Vol.12(2) [March 2005] >


Title: Chaotic analysis of pressure fluctuations in a gas-solid fluidized bed
Authors: Ahuja, Pradeep
Agrawal, Harshit
Sethi, Anadi Kishore
Raj, Utpal
Keywords: Chaotic analysis
pressure fluctuations
gas-solid fluidized bed
Lyapunov exponent
Hurst exponent
Issue Date: Mar-2005
Publisher: CSIR
IPC CodeF23C10/00; F23C101/00
Abstract:  The aim of the present work is to determine the superficial gas velocity range for which chaos occurs in a gas-solid fluidized bed for various static-bed-height to bed diameter ratios and sand/plastic-bead mixtures and to observe the change in deterministic chaos parameters. Four piezo-resistive pressure transducer along the height of fluidized bed have been used to record pressure fluctuations at 600 Hz. Amplitude Adjusted Fourier Transform (AAFT) technique has been used for generating surrogate data. Data have been analyzed for the superficial gas velocity range of 0 to 16 times the minimum fluidization velocity. For the various static bed heights and sand plastic-bead mixtures it is seen that chaos is observed in the superficial gas velocity range of 8 to 12 times the minimum fluidization velocity. The Hurst exponent rises with superficial gas velocity and then falls after a maximum. The change in the fractal dimension between surrogate and original time series also follows the same trend. The superficial velocity range for which chaos occurs is confirmed when there is change in fractal dimension between original and surrogate series greater than 0.55, Hurst exponent is above 0.5 and Lyapunov exponent is positive.
Page(s): 212-219
ISSN: 0975-0991 (Online); 0971-457X (Print)
Source:IJCT Vol.12(2) [March 2005]

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