Effective diffusivity and convective mass transfer coefficient during the drying of bananas

Silva, Cleide M. D. P. da S. E; Silva, Wilton P. da; Farias, Vera Solange de Oliveira

doi:10.1590/s0100-69162012000200014

Cited by 10 publications

(5 citation statements)

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“…The average value of the moisture diffusivity of banana and potato chips varies from 4.63E −11 to 8.49E −11 m 2 /s and 3.58E −11 to 4.97E −11 m 2 /s for open and closed system drying. The average value of the mass transfer coefficient of banana and potato chips varies from 1.12E −8 to 7.17E −8 m/s and 4.1E −7 to 5.16 E −7 m/s for open and closed system drying, and these values are close to the experimental result of mass transfer coefficient (2.064E −7 m/s) obtained in convective drying of the banana chips by Silva, Silva, Farias, and Gomes (). The mass transfer coefficient and moisture diffusivity were quite higher for the closed system due to higher drying temperature as compared to an open system.…”

Section: Resultssupporting

confidence: 87%

Experimental energy‐exergy performance and kinetics analyses of compact dual‐mode heat pump drying of food chips

Singh

Sarkar

Sahoo

2020

J Food Process Engineering

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Batch-type heat pump dryer operating in both closed and open-cycle modes with improved tray design is developed to investigate the energetic and exergetic performances, and drying kinetics of banana and potato chips. Effects of drying time on various performances and drying kinetic parameters are presented. Coefficient of performance of heat pump as well as whole system is higher for open-cycle mode.Higher specific moisture extraction rate is obtained as 1.248 kg/kWh for closed cycle drying of banana chips. Drying efficiency is also found higher for the closed cycle.The specific energy consumption is lower (0.8 kWh/kg) in closed system drying for banana. Total exergy destruction is found higher for the closed system. Mass transfer coefficient and moisture diffusivity are better for the closed system. On the basis of studied performance parameters, the closed system drying is found better than the open system drying in humid and hot ambient conditions. Practical Applications: This study develops a heat pump dryer (HPD) operated with both closed and open-cycle modes, which can control the air recirculation to provide optimum main drying parameters to get the best drying performance. The novelty of this study is twofold: controlling of air recirculation to get optimum condition and improved design of trays in drying cabinet for best possible air distribution to get maximum SMER (the obtained SMER value is more than the reported SMER values of other developed prototypes available in the literature). The results have been evaluated to provide better information about the benefits of varying air recirculation in the HPD system. Drying kinetic has also been determined experimentally, which will be helpful for modeling potato and banana drying. This study will help to develop commercial HPD operated in closed/open mode depending on environmental conditions for food chips drying.

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Section: Resultssupporting

confidence: 87%

Experimental energy‐exergy performance and kinetics analyses of compact dual‐mode heat pump drying of food chips

Singh

Sarkar

Sahoo

2020

J Food Process Engineering

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“…The study of drying, in various situations, uses diffusion theory to describe the transport of matter in a medium (Silva et al, 2012). As a result, the appropriate mathematical model to describe the phenomenon involves solving the diffusion equation.…”

Section: Methodsmentioning

confidence: 99%

Analysis of drying of melon peels using numerical solution of the diffusion equation

Pereira

Farias

Silva

et al. 2023

J Food Process Engineering

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The objective of this work was to apply a diffusive model to describe the drying of melon peels and use them to analyze the process for various operating conditions. For this, a numerical solution was developed considering shrinkage and diffusivity as a function of the local moisture content. This solution was obtained considering a boundary condition of the third kind. In the present work, drying of melon peels was carried out in an oven (with and without osmotic pretreatment) at temperatures of 60 and 70 C. The osmotic pretreatments were carried out in binary solutions (sucrose and distilled water) with 20 Brix at a ratio of 1:3 (g/g) (peel to solution).According to the statistical indicators obtained, the model proposed adequately fitted to the experimental data, providing values for the chi-square and the coefficient of determination of 7.682 Â 10 À4 to 2.356 Â 10 À3 and .99953-.99982, respectively.Both pretreatment and temperature influenced the drying parameters of the process.

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“…Propõe-se a implementação do modelo, para a descrição do processo de extração de óleos essenciais, considerando inicialmente o coeficiente de difusão constante. Assim como o trabalho desenvolvido por SIQUEIRA et al (2012), que estuda o resfriamento de morangos com ar forçado, e o estudo desenvolvido por SILVA et al (2012), que trata da transferência de massa durante o processo de secagem de bananas, o modelo apresentado inicialmente possui solução analítica. Entretanto, nestes dois trabalhos da literatura e no presente trabalho, a inserção de modificações no modelo faz com que ele não tenha mais solução analítica e só possa ser resolvido numericamente.…”

Section: Odelagem Da Extração De óLeos Essenciais Empregando Coeficunclassified

Modelagem da extração de óleos essenciais empregando coeficiente de difusão variável

2015

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RESUMO:Óleos essenciais são compostos químicos voláteis, característicos por sua fragrância e frequentes atividades antimicrobianas e antioxidantes. São extraídos dos tricomas de plantas aromáticas a partir de diversos métodos diferentes de extração. As indústrias dão preferência à extração por arraste a vapor (destilação a vapor), por ser um processo tradicional, de simples operação e baixo custo. A modelagem matemática deste processo é um passo inevitável para projetar plantas industriais de extração de óleo essencial visando a boas condições operacionais. O modelo empregado neste trabalho é baseado na difusão do óleo no interior da folha. Apresentam-se o procedimento de discretização deste modelo por método de diferenças finitas e a validação deste por comparação com a solução analítica. Dados da literatura de perfis de rendimento por tempo de extração foram empregados para a estimação do coeficiente de difusão. Propôs-se a melhoria do modelo por meio da estimação de parâmetros de equações empíricas para a descrição do coeficiente de difusão como função da concentração de óleo. A partir desta modificação, o modelo não possui mais solução analítica, o que justifica o procedimento numérico adotado. O modelo foi validado através de um conjunto de dados disponíveis na literatura. PALAVRAS-CHAVE: óleos essenciais, modelagem, estimação de parâmetros. MODELING OF ESSENTIAL OIL EXTRACTION WITH VARIABLE DIFFUSION COEFFICIENTABSTRACT: Essential oils are volatile chemical co mpounds, characteristic for its fragrance and frequent antimicrobial and antioxidant activities. Essential oils are extracted from the glandular trichomes of herbs from various extraction methods. Industries give preference to extraction by steam distillation, for its traditional method, simple operation and low cost. The mathematical modeling of this process is an inevitable step for designing industrial plants of essential oil extraction with good operating condition. The model used in this artic le is based on the diffusion of the oil within the leaf. The discretization procedure of this model is presented through finite differences and its validation by comparing with the analytical solution. Data of profiles yield by extraction time were used to estimate the diffusion coefficient. In order to improve the model empirical equations were applied to describe de diffusion coefficient as a function of the oil concentration and the parameters of these equations were estimated. Using this modification, the model has no longer analytical solution, which justifies the adopted numerical procedure. The model was validated using data from literature.

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Effective diffusivity and convective mass transfer coefficient during the drying of bananas

Cited by 10 publications

References 10 publications

Experimental energy‐exergy performance and kinetics analyses of compact dual‐mode heat pump drying of food chips

Experimental energy‐exergy performance and kinetics analyses of compact dual‐mode heat pump drying of food chips

Analysis of drying of melon peels using numerical solution of the diffusion equation

Modelagem da extração de óleos essenciais empregando coeficiente de difusão variável

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