Document Type : Research Paper

**Authors**

Department of Chemical Engineering, University of Sistan and Baluchestan, Zahedan, Iran

**Abstract**

Bubble columns are gas- liquid contactors that are widely used in chemical and bio- chemical industries. High mixing that result in high heat and mass transfer rates are amongst their advantages. Heat transfer in a bubble column having a bundle of heaters investigated and the variation of heat transfer coefficient with variation in heaters pitch to diameter ratios in a bundle of heaters reported. The bubble column modeled in a three-dimensional in the Eulerian framework by using computational fluid dynamic simulation. It was 0.292 m in diameter and 1.5 m in height. Simulations performed for five heaters and for nine heaters in a bundle. The bubble column with a five heaters bundle was investigated in the pitch to diameter ratios of 1.5, 2 and 2.5. The bubble column with nine heaters bundle was investigated with the pitch to diameter ratios of 1.25, 1.5, 2.25 and 2.46. The range of the gas velocity was 0.0025 to 0.04 m/s.

The heat transfer results show that, with decreasing the pitch to diameter ratios the heat transfer coefficient decreases. In bubble column with bundle of nine heaters at a constant superficial gas velocity, with decreasing the pitch to diameter ratio from 2.46 to 1.5 the heat transfer coefficient decreases; whereas in the pitch to diameter ratio of 1.25 heat transfer coefficient is high.

The heat transfer results show that, with decreasing the pitch to diameter ratios the heat transfer coefficient decreases. In bubble column with bundle of nine heaters at a constant superficial gas velocity, with decreasing the pitch to diameter ratio from 2.46 to 1.5 the heat transfer coefficient decreases; whereas in the pitch to diameter ratio of 1.25 heat transfer coefficient is high.

**Keywords**

[1] Degaleesan, S., Dudukovic, M.P. and Pan, Y. (2001). "Experimental study of gas induced liquid flow structures in bubble columns." *AIChE J*, Vol. 47, pp. 1913-1931.

[2] Shah, Y.T., Kelkar, B.G., Godbole, S.P. and Deckwert, W.D. (1982). "Design parameters estimations for bubble column reactors." *AIChE J*, Vol. 28, pp. 353-379.

[3] Tongyan Li, Tim C. Keener, Lei Cheng (2014). "Carbon dioxide removal by using Mg(OH)_{2} in a bubble column: Effects of various operating parameters."* Int J Greenhouse Gas*, Vol. 31, pp. 67–76.

[4] Kantarci, N., Borak, F. and Ulgen, A.K.O. (2005) "Review Bubble column reactors." *Process Biochem*, Vol. 40, pp. 2262-2283.

[5] Sheikhi, A., Sotudeh-Gharebagh, R., Zarghami, R., Mostoufi, N. and Alf, M. (2013). "Understanding bubble hydrodynamics in bubble columns." *Exp Therm Fluid Sci*, Vol. 45, pp. 63–74.

[6] Schumpe, A. and Grund, G. (1986) "The gas disengagement technique for studying gas holdup structure in bubble columns." *Chem Eng*, Vol. 64, pp.891-897.

[7] Deckwer, W.D. (1992).* Bubble Column Reactors*, Wiley.

[8] Saxena, S.C. and Vadivel, R. (1988). "Heat transfer from a tube bundle in a bubble column." *Int Comm Heat mass transfer*, Vol. 15, pp. 657-667.

[9] Rahimi, R. and Tayebi, A.V. (2011). "Study of heat transfer from an immersed bar in a simple batch bubble column by CFD*.*"* IRECHE J*., Vol. 3, pp. 67-75.

[10] Colmenares, A., Sevilla, M., Goncalves, J. J., Gonzalez-Mendizabal, D.(2001)."FluidDynamic experimental study in a bubble column with internals." *Int Comm Heat mass transfer,* Vol.28, pp. 389-398.

[11] Deckwer, W.D., Zaidi, A., Ralek, M.(1980). "Hydrodynamic properties of the Fischer-Tropsch slurry process." *Ind Eng Chem Process Des Dev,* Vol. 19.

[12] Kolbel, H., B. E., M. J., (1960). "Warmeubergang in blasensaulen. III. Messungen an gasdurchstromten suspensionen."* Chem. Eng. Tech*, pp. 3284-92.

[13] Li, H., P. A. (1997*).*"Heat transfer and hydrodynamics in a three-phase slurry bubble column." *Ind Eng. Chem,* Vol. 36, pp. 4688-4694.

[14] Saxena, S.C., Rao, N.S. (1993). "Estimation of gas holdup in a slurry bubble column with internals: nitrogen thermion magnetite system*." Powder Technol*, Vol. 75, pp. 153-158.

[15] Faical, Larachia., Damien, Desvignea., Ludovic, Donnatb., Schweichc, D. (2006)."Simulating the effects of liquid circulation in bubble columns with internals."* Chem Eng Sci,* Vol. 61, pp. 4195-4206.

[16] Saxena, S.C., Verma, A.K., Vadivel, R., Saxena, A.C. (1989)."Heat transfer from a cylindrical probe in a slurry bubble column."* Int Comm Heat mass transfer*, Vol. 16, pp. 267-281.

[17] Schluter, S., Steiff, A., Weinspach, P.M. (1995)."Heat transfer in two- and three-phase bubble column reactors with internals."* Chem Eng Procc*, Vol. 34, pp. 157-172.

[18] Lewise, D.A., Field, R.W., Xavier, A.M., Edwards, D. (1982)."Heat transfer in bubble column." *Trans. IChem J, *Vol. 60, pp. 40-47.

[19] Emily, W. Tow., John, H., Leinhard, V. (2014)."Heat transfer to a horizontal cylinder in shallow bubble column."* Int J Heat Mass Trans*, Vol. 79, pp. 353-361.

[20] Jhawar, A.K., Prakash, A. (2014)."Bubble column with internals: Effects on hydrodynamics and local heat transfer." *Chem Eng Res Des,* Vol. 92, pp. 25–33.

[21] Masood, R.M.A., Rauh, C., Delgado, A. (2014)."CFD simulation of bubble column flows: An explicit algebraic Reynolds stress model approach."* Int J Multiphase Flow*, Vol. 66, pp.11–25.

[22] Fair, J.R., Lambright, A. J., Andersen, J. W. (1962). "Heat Transfer and Gas Holdup in a Sparged Contactor*.*"* Ind Eng ChemProcess Des. Dev*, Vol. 1, pp. 33-36.

[23] Krishna, R., Swart, De., Jeroen, W. A., Hennephof, Daniëlle E., Ellenberger, Jürg, Hoefsloo., Hubertus C. J. (1994)."Influence of increased gas density on hydrodynamics of bubble-column reactors." *AIChE J*, No. 40, pp. 112-119.

[24] C. Ansys Inc.,(2005).*Solver*, USA.

[25] Ranade,V.V. ( 2002). *Computational Flow Modeling for Chemical Reactor engineering*, Academic Press.

[26] Simonnet,C.G. M., Olmos, N.M. E. (2008)."CFD simulation of the flow field in a bubble column reactor: Importance of the drag force formulation to describe regime transitions." *Chem Eng Proc, *Vol. 47, pp. 1726–1737.

[27] Dhotre, M.T., Vitankar,V.S., Joshi, J.B. (2005). "CFD simulation of steady state heat transfer in bubble columns." *Chem. Eng. J*, Vol. 108 , pp. 117-125.

[28] Rahimi, R. (1962). "Heat Trahsfer in Bubble Column, in, PhD Thesis, Bath University, UK, 1988. Contactor." *Ind. Eng. Chem. Process Des. Dev*., No. 1, pp. 33-36.

[29] Hart,W.F. (1976). "Heat Transfer in Bubble-Agitated Systems. A General Correlation." *Ind. Eng. Chem. Process Des. Dev*., Vol. 15, pp. 109-114.

[30] Burkel,W. (1972). "Der WKrmeubergang an Heizund Kiihlflachen in Begasten Fliissigkeiten." *Chem.lng.Tech*, Vol. 44, pp. 265-268.

[31] Deckwer,W.D. (1980)."On the mechanism of heat transfer in bubble column reactors." *Chem. Eng. Sci*, Vol. 35, pp. 1341-1346.

[32] Kolbel, H., Siemes, W., Muller, R. (1958)."Warmeiibergang in Blasensaiilen." *Chem. Ing.Tech*, Vol. 30, pp. 400-404.

[33] Kast, W. (1962). "Analyse des warmeubergangs in blasensaulen." *Int J Heat and Mass Transfer*, Vol. 5, pp. 329-336