African Journal of
Agricultural Research

  • Abbreviation: Afr. J. Agric. Res.
  • Language: English
  • ISSN: 1991-637X
  • DOI: 10.5897/AJAR
  • Start Year: 2006
  • Published Articles: 6691

Full Length Research Paper

Mathematical modeling and thermodynamic properties for drying soybean grains

Daniel Emanuel Cabral de Oliveira*
  • Daniel Emanuel Cabral de Oliveira*
  • IF Goiano, Avenida Oeste, s/n, saida para Piranhas - Ipora ? GO, Brazil.
  • Google Scholar
Osvaldo Resende
  • Osvaldo Resende
  • IF Goiano, Rodovia Sul Goiana, Km 01. Zona Rural. C. Postal 66, Rio Verde ? GO, Brazil.
  • Google Scholar
Jaqueline Ferreira Vieira Bessa
  • Jaqueline Ferreira Vieira Bessa
  • IF Goiano, Rodovia Sul Goiana, Km 01. Zona Rural. C. Postal 66, Rio Verde ? GO, Brazil.
  • Google Scholar
Adrieli Nagila Kester
  • Adrieli Nagila Kester
  • IF Goiano, Rodovia Sul Goiana, Km 01. Zona Rural. C. Postal 66, Rio Verde ? GO, Brazil.
  • Google Scholar
Thais Adriana Souza Smaniotto
  • Thais Adriana Souza Smaniotto
  • IF Goiano, Rodovia Sul Goiana, Km 01. Zona Rural. C. Postal 66, Rio Verde ? GO, Brazil.
  • Google Scholar


  •  Received: 17 March 2014
  •  Accepted: 15 May 2014
  •  Published: 01 January 2015

Abstract

The aims of this work were to adjust different mathematical models to experimental data describing the drying of the Valiosa cultivar soybean grain, to determine and to evaluate the effective diffusion coefficient and to obtain the activation energy and the thermodynamic properties of the drying process under different air conditions. The Valiosa cultivar soybean grains, with an initial moisture content on a dry basis of 0.56 (d.b., decimal), were dried in an oven with forced air ventilation at five different temperatures (40, 55, 70, 85 and 100°C) until reaching a moisture content of 0.133 ± 0.019 (d.b.). Of the models analyzed, Page’s model was selected to best represent the drying phenomenon. The effective diffusion coefficient of soybeans increased with the air temperature and was described by the Arrhenius equation; an activation energy of 22.77 kJ mol-1 was reported for liquid diffusion in the drying of the soybeans. The enthalpy and entropy decreased with increasing temperature, while the Gibbs free energy increased with increasing drying temperature.

 

Key words: Glycine max, liquid diffusivity, enthalpy, entropy, Gibbs free energy.