CFD simulation of convective heat transfer in vessel with mechanical agitation for milk
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ORIGINAL ARTICLE
CFD simulation of convective heat transfer in vessel with mechanical agitation for milk E. Rajasekaran1 • B. Kumar1 • R. Muruganandhan2 • S. V. Raman3 G. Nandhini Devi4
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Revised: 9 December 2019 / Accepted: 1 April 2020 Association of Food Scientists & Technologists (India) 2020
Abstract Computational fluid dynamics (CFD) analysis using ANSYS Fluent software has been carried out to investigate velocity profiles and thermal characteristics of milk during heating under mechanically agitated condition. In earlier article experimental data on forced convection heat transfer coefficient h and correlations of the form Nu ¼ a Reb Pr0:33 for cow milk, standardised milk and full cream milk in Baffled vessel and Unbaffled vessel with scraping, using Propeller, Flat Six Blade Turbine (FBT), Inclined Six Blade Turbine (IBT) and Paddle impellers were reported. It was noted milk in Baffled vessel with Paddle impeller provided highest h even at lower rotational speeds followed by Propeller, FBT and IBT impellers. In Unbaffled vessel with scraping, Propeller provided the
& E. Rajasekaran [email protected] B. Kumar [email protected] R. Muruganandhan [email protected]
Keywords Milk Stirred vessel Impellers CFD simulations Velocity profiles Nomenclature Cpm J Specific heat KgK Da Dt E W L g
S. V. Raman [email protected]
G. Nandhini Devi [email protected]
H J km m n Nu
1
Department of Printing Technology, Anna University, Tamil Nadu, Chennai 600025, India
2
Department of Mechanical Engineering, Anna University, Tamil Nadu, Chennai 600025, India
3
Department of Biotechnology, Anna University, Tamil Nadu, Chennai 600025, India
4
highest h followed by FBT and IBT impellers. Hence, the present investigation has been carried out to validate and understand how different velocity of flow currents and their magnitude influence the heat transfer coefficient values in CFD simulation. It also justifies the relative performance of the impellers delineated in the earlier paper. In addition, theoretical values of heat transfer coefficients computed using CFD shows close agreement with experimental values.
Centre for Food Technology, Department of Biotechnology, Anna University, Tamil Nadu, Chennai 600025, India
h
Diameter of impeller (mm) Diameter of milk vessel (mm) Height of the impeller position from vessel bottom (mm) Width of the impeller blade (mm) Length of the impeller blade (mm) Acceleration due gravity sm2 Forced convection heat transfer coefficient W m2 K
p Pr
Milk level in the vessel (mm) Baffle width (mm) W Thermal conductivity of milk mK Mass of milk (kg) Speed of rotation of impeller (rpm) Nusselt number dimensionless h Dt Pressure
N m2
km
Prandtl numberdimensionless
Cpmlm km
123
J Food Sci Technol
q Re
Heat transfer by conduction (Watt)
SS t
Stainless steel Vessel thickness (mm), blade thickness (mm) and time (s) Milk temperature (K) Vessel bottom surface temperature (K) Initial temperature of milk (K
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