Batch and continuous spouted bed drying of cereal grains: The thermal equilibrium model

Zahed, Adnan Hamza Mohammad; Epstein, Norman

doi:10.1002/cjce.5450700517

Cited by 39 publications

(31 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…X e is the equilibrium moisture content which was determined making use of the correlations reported in the literature (Vizcarra Mendoza, Martı´nez Vera, & Caballero Domı´nguez, 2003;Zahed & Epstein, 1992). The diffusion coefficients were estimated taking into account only the first term of the infinite Fourier series solution and following a linear regression procedure.…”

Section: Diffusion Coefficient Estimationmentioning

confidence: 99%

Hydration of grain kernels and its effect on drying

Ruiz

Vizcarra

Martínez

2008

LWT - Food Science and Technology

View full text Add to dashboard Cite

Section: Diffusion Coefficient Estimationmentioning

confidence: 99%

Hydration of grain kernels and its effect on drying

Ruiz

Vizcarra

Martínez

2008

LWT - Food Science and Technology

View full text Add to dashboard Cite

“…Precious few complete sets of drying data are reported in the open literature. However, Zahed and Epstein (1992), while theoretically treating the spouted bed drying of rice, also comprehensively cite the experimental data of Zuritz and Singh (1982). Zahed and Epstein's analysis assumes that particledrying rates are dominated by the mass transfer within the particle.…”

Section: Application To Actual Measurements: Spouted Bed Drying Of Ricementioning

confidence: 99%

“…The batch drying data of interest are found in Tables 4 and 5 of Zahed and Epstein (1992) for two inlet air temperatures, 52.0ºC and 70.2ºC. The 52.0ºC inlet air temperature case was used to determine optimum values of h, k G , Nu IN and Sh IN .…”

Section: Application To Actual Measurements: Spouted Bed Drying Of Ricementioning

confidence: 99%

See 1 more Smart Citation

A Quasi‐Steady State Shell and Shrinking Core Approach to the Drying of Porous Particles and an Example of Parameter Identification

Manganaro

2007

Can J Chem Eng

View full text Add to dashboard Cite

of cooler solvent vapour away from the wet core and through the porous shell was neglected.In this paper, the scope of the heat transport equation is broadened to include convective heat transfer. In fact, without the convective heat transfer term, it is possible to obtain satisfactory agreement between model predictions and actual drying data only if the thermal conductivity of the particle shell is set to an unreasonably small value.The mean fi eld model presented here allows for heat and mass transfer resistances in both the gas and particle phases. Thus, the model is free of any assumption of which mode, if any, or which phase, if any, is controlling. The equations comprising the model are incorporated in a standard Excel spreadsheet and with the input of experimental drying data, provide a means of characterizing the drying process for particulate solids.A quasi-steady state shell and shrinking core approach which recognizes heat and mass transfer resistances in both the gas and particle phases for drying of a porous particle is proposed. A mean fi eld model (constant properties) using this approach was embedded in a spreadsheet combined with a genetic algorithm for parameter identifi cation to provide an easy means of characterizing the drying process from drying data. In drying, assuming a mean fi eld, four major parameters are typically unknown: two related to the process (heat and mass transfer coeffi cients) and two which incorporate porous particle properties (shell thermal conductivity and vapour diffusivity). It is shown how these four parameters may be determined from experimental drying data. The model was applied to data for spouted bed drying of rice. For the particular case studied, external heat transfer was found to be the controlling mode, although resistance to moisture diffusion within the particle is important. The approach presented admits of future refi nements to improve its scope and utility.On propose une approche à noyau rétrécissant et peau en régime quasi permanent qui prend en considération les résistances aux transferts de chaleur et de matière des phases gazeuse et particulaires pour le séchage d'une particule poreuse. Un modèle de champ moyen (propriétés constantes) utilisant cette approche a été programmé dans un tableur combiné à un algorithme génétique pour l'identifi cation des paramètres, dans le but d'obtenir une manière facile pour caractériser le procédé de séchage à partir de données de séchage. En séchage, en supposant un champ moyen, quatre paramètres principaux sont typiquement inconnus: deux qui sont reliés au procédé (coeffi cients de transfert de chaleur et de matière) et deux qui incorporent les propriétés des particules poreuses (conductivité thermique de la peau et diffusivité de la vapeur). On montre comment ces quatre paramètres peuvent être déterminés à partir des données de séchage expérimentales. Le modèle a été appliqué aux données de séchage de riz en lit jaillissant. Pour le cas particulier étudié, on a trouvé que le transfert de chaleur externe est le...

show abstract

“…In the last decades, many researches related to food and grain drying and heat treatment have been carried on to obtain the required physical and thermal properties required for proper drier or process design (Churchill, 1977;Zahed & Epstein, 1992Muthu & Chattopadhyay, 1993;de Ville & Smith, 1996;Galan-Domingo & Martinez-Vera, 1996;Smith, 1996;Sotocinal et al, 1997;Tolaba et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

Transport coefficients for low and high-rate mass transfer along a biological horizontal cylinder

Barreto¹,

Fortes

Ferreira

et al. 2006

Rev. bras. eng. agríc. ambient.

View full text Add to dashboard Cite

Knowledge of heat and mass transfer coefficients is essential for drying simulation studies or design of food and grain thermal processes, including drying. This work presents the full development of a segregated finite element method to solve convection-diffusion problems. The developed scheme allows solving the incompressible, steady-state Navier-Stokes equations and convective-diffusive problems with temperature and moisture dependent properties. The problem of simultaneous energy, momentum and species transfer along an infinite, horizontal cylinder under drying conditions in forced convection is presented, considering conditions normally found in biological material thermal treatment or drying. Numerical results for Nusselt and Sherwood numbers were compared against available empirical expressions; the results agreed within the associated experimental errors. For high rate mass transport processes, the proposed methodology allows to simulate drying conditions involving wall convective mass flux by a simple inclusion of the appropriated boundary conditions. Key words: drying, heat transfer, convection, diffusion Coeficientes de transporte para baixas e altas taxas de transferência de massa ao longo de um cilindro biológico horizontal RESUMO O conhecimento dos coeficientes de transferência de calor e massa é essencial para o estudo de simulação de secagem e para o projeto de processamento térmico de grãos e alimentos, inclusive secagem. Este trabalho apresenta o desenvolvimento completo de um método de elementos finitos segregado para resolver problemas de convecção-difusão. O esquema desenvolvido permite que se resolvam as equações de Navier-Stokes incompressíveis em regime permanente, além de problemas convectivos-difusivos com propriedades dependentes da temperatura e da umidade. Apresenta-se o problema de transferência simultânea de energia, momentum e espécies ao longo de um cilindro horizontal, infinito sob condições de secagem em convecção forçada, considerando-se condições normalmente encontradas em tratamento tér-mico ou secagem de material biológico. Compararam-se resultados numéricos para Nusselt e Sherwood com expressões empíricas disponíveis; os resultados concordaram dentro dos erros experimentais associados. Para processos com altas taxas de transporte de massa, a metodologia proposta permite simular condições de secagem envolvendo fluxo convectivo de massa na parede, por meio de uma simples inclusão de condições de contorno apropriadas.

show abstract

Batch and continuous spouted bed drying of cereal grains: The thermal equilibrium model

Cited by 39 publications

References 16 publications

Hydration of grain kernels and its effect on drying

Hydration of grain kernels and its effect on drying

A Quasi‐Steady State Shell and Shrinking Core Approach to the Drying of Porous Particles and an Example of Parameter Identification

Transport coefficients for low and high-rate mass transfer along a biological horizontal cylinder

Contact Info

Product

Resources

About