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Title Determination of Moisture Diffusivity during Drying of Rectangular Cassava Pellets: Experimental and
Journal International journal of Engineering And Applied Science
Publisher Faculty of Engineering, Nnamdi Azikiwe University, Awka Nigeria.
Issue 1
ISSN 1119-8109
Pages 56-63
Subject Mechanical Engineering
Date of Publication December 08,2019

AUTHOR(S) Onyemazuwa Andrew Azaka, Samuel Ogbonna Enibe, Chinonso Hubert Achebe

ABSTRACT

The aim of this study is to experimentally determine the drying dynamics of cassava pellets during convective drying. TMS 30572 specie of Cassava tubers were hand peeled and cut into slabs with a rectangular mold (40 mm×20 mm×10 mm) designed for the purpose. The drying tests were conducted using a hot air-convective dryer that can dry samples weighing from 0 to 100g. The response of the drying curve or the drying kinetic depends on the applied drying conditions. The dryer was set at different heater temperatures of 150°C, 140°C, 130°C, 120°C and 110°C which gave corresponding hot air temperatures of 81°C, 78°C,75°C,70°C, and 66°C respectively. The hot air velocity was kept constant at 4m/s. The drying dynamics dictated by Fick’s second law for a 2-dimensional element as influenced by both initial condition and Neumann Boundary condition was used to define the mass transfer process, by assuming isotropic behavior of the samples. The comparison between the experimental results and the proposed analytical solutions of the equation of diffusion represented by Fick’s law, applied to 2–dimensional analysis for a finite shape, allows determination of the values of the diffusion coefficient. The diffusivity of the rectangular samples was determined to be in range of 2.3304 x 109 – 1.4260 x 109 m2s-1 and described using a 3rd order polynomial equation (y=-9E-05x^3-0.0343x^2-4.4281x+189.6) with the value of R² = 0.8989. The diffusivity plots clearly explainthat the moisture diffusivity of cassava pellets can be expressed as a function of temperature using a 3rd order polynomial equation.The study could provide theoretical bases for equipment design and process optimization for hot air drying of Cassava pellets


Keywords: Thermal Energy, Convective Drying, Moisture Diffusivity, Cassava Pellets.




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