Hydrodynamics and local heat transfer measurements in a bubble column with suspension of yeast

Prakash, Anand; Margaritis, Argyrios; Li, H; Bergougnou, M.A.

doi:10.1016/s1369-703x(01)00137-1

Cited by 87 publications

(69 citation statements)

References 21 publications

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“…When heat transfer in different regions of an air-water-yeast bubble column were measured, the heat transfer coefficient in the bulk was more than twice that in the coalescing region [17]. The surface-active properties of yeasts [36] (absent in this experiment) stabilize the air-water-yeast foam and The highest heat transfer coefficients occur in the coalescing region with impact, and nearly as high were measurements in the bulk regardless of impact.…”

Section: Column Region and Bubble Impactmentioning

confidence: 89%

“…The significant drop in heat transfer coefficient as the probe height is reduced from 4.5 to 0.5 cm is unsurprising because the bottom wall (the sparger) acts as a momentum sink, decreasing the turbulent dissipation rate in its vicinity. Prakash et al [17] similarly observe that the heat transfer coefficient in a tall bubble column decreases in the vicinity of the column wall. The data show a critical height (around 3 cm in this experiment) above which the heat transfer coefficient is roughly constant and below which the heat transfer coefficient varies with cylinder height above the sparger.…”

Section: Effect Of Probe Heightmentioning

confidence: 92%

“…Narayan et al [1] proposed that horizontal position of internals with respect to the gas sparger orifices could affect heat transfer coefficients. The heat transfer coefficient in the coalescing region at the top of the column has been shown by Prakash et al [17] to be significantly lower than in the bulk in an air-water-yeast system, but this has not been studied in an air-water system. Finally, to our knowledge, the effect of liquid depth on heat transfer coefficient or flow regime has not been studied.…”

Section: Introductionmentioning

confidence: 98%

See 2 more Smart Citations

Heat transfer to a horizontal cylinder in a shallow bubble column

Tow¹,

Lienhard²

2014

International Journal of Heat and Mass Transfer

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Heat transfer coefficient correlations for tall bubble columns are unable to predict heat transfer in shallow bubble columns, which have unique geometry and fluid dynamics. In this work, the heat transfer coefficient is measured on the surface of a horizontal cylinder immersed in a shallow air-water bubble column. Superficial velocity, liquid depth, and cylinder height and horizontal position with respect to the sparger orifices are varied. The heat transfer coefficient is found to increase with height until reaching a critical height, and a dimensionless, semi-theoretical correlation is developed that incorporates superficial velocity, liquid properties, and height. Additionally, the more minor effects of flow regime, column region, and bubble impact are discussed with the aim of informing design. Notably, the heat transfer coefficient can be as high in the region of bubble coalescence as in the bulk of the column, but only if the probe is placed so that bubbles impact the cylinder. The correlation and discussion provide a framework for modeling and designing * Address all correspondence to lienhard@mit.edu Greek

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Section: Column Region and Bubble Impactmentioning

confidence: 89%

Section: Effect Of Probe Heightmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 98%

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Heat transfer to a horizontal cylinder in a shallow bubble column

Tow¹,

Lienhard²

2014

International Journal of Heat and Mass Transfer

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“…In bioprocess application, bubble column acts as a bioreactor in producing industrial valuable products such as enzymes and antibiotics. Recently, the study was more focused on the hydrodynamics properties of the bubble column (Prakash et al, 2001). In order to enhance the performance of the column, it is essential to understand the hydrodynamics properties.…”

Section: Introductionmentioning

confidence: 99%

Flow visualization of bubble structure in bubble column reactor for fluid mixing

Ibrahim¹,

Khalid²,

Zaman³

et al. 2017

AIP Conference Proceedings

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Bubble columns reactor is widely used as gas-liquid mixing and as reactors in many industries such as in chemical, petrochemical and biochemical. High interfacial area between the gas and liquid phase will enhanced an effective mixing, leading to improved heat and mass transfer characteristics under bubble columns become an attractive choice as reactors for the described processes. In this research, experimental work by using cylindrical acrylic bubble column with internal diameter of 0.15m and height of 1m was done. The bubble column is equipped by four nozzles with orifice diameter of 5 mm function as gas distributor attach at the bottom of the column. For this study, gas phase and liquid phase used are air and water respectively. The investigated variable parameter was mechanism of bubble formation, regime analysis and the relationship between superficial gas holdup and gas holdup. The techniques used in collecting data were visual observation, measurement technique and photographic method. The result showed that there were five stage of bubble formation based on experiment conducted. For gas holdup and superficial gas velocity relationship, it was discovered that the gas holdup increased with the increasing of superficial gas velocity. The relationship was proof to be in good agreement with published data proposed by previous researcher. .

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“…The effect of superficial gas velocity on CHTC in multiphase systems have been studied widely (Deckwer et al, 1980;Prakash et al, 2001;Saxena et al, 1990). Many studies reported enhancement of CHTC at higher superficial gas velocity, although changing solid phase conditions (particle diameter, shape and concentration) and liquid phase properties (such as density and viscosity) affected the CHTC (Deckwer et al, 1980;Prakash et al, 2001;Saxena et al, 1990;Prakash, 1997, 2000).…”

Section: Introductionmentioning

confidence: 99%