Document Type : Research Paper

Abstract

Concentration decreases the amount of waterin liquid food and increases shelf life. Several types of evaporators are used for concentration, thus, it is necessary to simulate the process before design to control efficiency. The flow of pomegranate juice was simulated in a forward-feed flat plate evaporator at concentrations of 18 to 50 Brix in a two-phase mixture model using computational fluid dynamics. The results show that a vacuum developed in the evaporator column causing a slight drop in pressure at the inlet. Temperature increased at high intensities at the flow entrance zone. The magnitude of the velocity of the vapor increased as the flow increased from the inlet toward the outlet of the evaporator. Radial velocity was at a maximum in the middle of the flow medium and decreased gradually toward the boundary layer. The volume fraction of the pomegranate juice decreased and the volume fraction of the steam increased gradually from the inlet toward the outlet of the evaporator. This model can be applied for other liquids, but it is first necessary to define the thermo-physical properties of the liquid at different concentrations.  

Keywords

Altan, A. and Maskan, M. 2005. Rheological behavior of pomegranate (punica granatum L.) juice and concentrate. J. Texture Stud. 36(1): 68-77.
Anon.  2005. FLUENT 6.2 User's Guide Manual. Fluent Inc.
Anon. 2011. Statistic of Agricultural Production. Jihad-Agriculture Organization of Fars Province. Shiraz. Iran. (in Farsi)
Cadet, C., Toure, Y., Gilles, G. and Chabriat, J. P. 1999. Knowledge modeling and non- linear predictive control of evaporators in cane sugar production plants. J. Food Eng. 40(1-2): 59-70.
Cavallini, A., Censi, G., Del Col, D., Doretti, L., Longo, G. A. and Rossetto, L. 2001. Experimental investigation on condensation heat transfer and pressure drop of new HFC refrigerants (R134a, R125, R32, R410A R236ea) in a horizontal smooth tube. Int. J. Refrig. 24, 73-87.
Chernysheva, M. A. and Maydanik, Y. F. 2012. 3D-model for heat and mass transfer simulation in flat evaporator of copper-water loop heat pipe. Appl. Therm. Eng. (33-34), 124-134.
Hou, H., Bi, Q. and Zhang, X. 2012. Numerical simulation and performance analysis of horizontal-tube falling-film evaporators in seawater desalination. Int. Commun. Heat Mass. 39, 46-51.
Johnson, D. E. 1960. Simulation and analysis improve evaporator control. ISA J. 7(7): 46.
Kakac, S., Liu, H. and Kakag, K. 2002. Heat Exchangers: Selection, Rating and Thermal Design. CRC Press. Boca Raton. Florida. USA.
Kothandaraman, C. P. and Subramanyan, S. 1989. Heat and Mass Transfer Data. 4th Ed. New Age International. New Delhi. India.
Kubota, A., Kato, H. and Yamaguchi, H. 1992. A new modeling of cavitating flows: A numerical study of unsteady cavitation on a hydrofoil section. J. Fluid Mech. 240, 59-96.
Lathinen, S. T. 2001. Identification of fuzzy controller for use with a falling film evaporator. Food Control. 12, 179-180.
Li, Q., Zhao, K. and Xuan, Y. M. 2011. Simulation of flow and heat transfer with evaporation in a
porous wick of a CPL evaporator on pore scale by lattice Boltzmann method. Int. J. Heat Mass.
54, 2890-2901.
Magerramov, M. A., Abdulagatov, A. I., Azizov, N. D. and Abdulagatov, I. M. 2007. Effect of temperature, concentration, and pressure on the viscosity of pomegranate and pear juice concentrates. J. Food Eng. 80, 476-489.
Miranda, V. and Simpson, R. 2005. Modeling and simulation of an industrial multiple effect evaporator: tomato concentrate. J. Food Eng. 66, 203-210.
Morales-Ruiz, S., Rigola, J., Perez-Segarra, C. D. and Garcia-Valladares, O. 2009. Numerical analysis of two-phase flow in condensers and evaporators with special emphasis on single-phase/two-phase transition zones. Appl. Therm. Eng. 29, 1032-1042.
Paramalingam, S., Winchester, J. A. and Marsh, C. 2000. On the fouling of falling film evaporators due to film break-up. Food Bioprod. Process. 78(2): 79-84.
Paramalingam, S., Bakker, H. and Chen, H. 2001. Dynamic modeling of falling film evaporators for milk products. Institute of Technology and Engineering. Paper No. 576.
Riverol, C. and Napolitano, V. 2000. Non- linear control of an evaporator using an error trajectory technique. J. Chem. Technol. Biot. 75, 1047-1053.
Roustapour, O. R., Jokar, A., Gazor, H. R. and Jokar, L. 2013. Effects of concentration and temperature on the thermophysical properties of clarified pomegranate juice. Iranian J. Nutr. Sci. Food Technol.
37, 77-91. (in Farsi)
Runyon, C. H., Rumsey, T. R. and McCarthy K. L. 1991. Dynamic simulation of a non- linear model of a double effect evaporator. J. Food Eng. 14, 185-201.
Sanieenezhad, M. 2004. An Introduction to Turbulent Flows and Turbulence Modeling. 3th Ed. Daneshnegar Press. (in Farsi)
Tonelli, S., Romagnoli, J. A. and Porras J. A. 1990. Computer package for transient analysis of industrial multiple effect evaporators. J. Food Eng. 12, 267-281.
Winchester, J. A. and Marsh, C. 1999. Dynamics and control of falling film evaporators with mechanical vapor recompression. Chem. Eng. Res. Des. 77(5): 357-371.