Mathematical modelling of thin-layer infrared drying of wet olive husk

Celma, Antonio Ruiz; Rojas, S.; Rodríguez, Fernando López

doi:10.1016/j.cep.2007.10.003

Cited by 108 publications

(50 citation statements)

References 28 publications

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“…Several studies [21][22][23][24][25][26][27][28] have examined the drying of olive mill wastes using different drying systems. The drying process is generally a complex phenomenon where convection and diffusion phenomena participate.…”

Section: Introductionmentioning

confidence: 99%

Olive Mill Wastewater: From a Pollutant to Green Fuels, Agricultural Water Source and Bio-Fertilizer—Part 1. The Drying Kinetics

et al. 2017

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Abstract:Olive Mill Wastewater (OMWW) treatment is considered to be one of the main challenges that Mediterranean countries face. Although several procedures and technologies are mentioned in the literature, these techniques have several disadvantages or have been limited to laboratory pilot validation without posterior industrial projection. Recently, an advanced environmental friendly strategy for the recovery of OMWW was established involving the impregnation of OMWW on dry biomasses, drying of these impregnated samples, and finally green fuels and biochar production. This established strategy revealed that the drying step is crucial for the success of the entire recovery process. Hence, two impregnated samples were prepared through OMWW impregnation on sawdust (IS) and olive mill solid waste (ISW). The drying kinetics of OMWW and impregnated samples (IS and ISW) were examined in a convective dryer (air velocity range from 0.7-1.3 m/s and the temperature from 40-60 • C). The experimental results indicated that the drying of the impregnated samples occurred twice as fast as for the OMWW sample. Such behavior was attributed to the remaining thin layer of oil on the OMWW surface Furthermore, the Henderson and Pabis model showed the suitable fit of the drying curves with a determination coefficient R 2 above 0.97. The drying rates were extracted from the mathematical models and the drying process was analyzed. The coefficient of effective diffusivity varied between 2.8 and 11.7 × 10 −10 m 2 /s. In addition, the activation energy values ranged between 28.7 and 44.9 kJ/mol. These values were in the same range as those obtained during the drying of other agrifood byproducts. The final results could be very helpful to engineers aiming to improve and optimize the OMWW drying process.

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Section: Introductionmentioning

confidence: 99%

Olive Mill Wastewater: From a Pollutant to Green Fuels, Agricultural Water Source and Bio-Fertilizer—Part 1. The Drying Kinetics

et al. 2017

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“…Besides, this type of dehydration is usually applied for by-products from industrial processes (Freire et al, 2001;Doymaz et al, 2004;Ruiz Celma et al, 2008). To control the process itself, mathematical modeling of the process is required.…”

Section: Introductionmentioning

confidence: 99%

Dehydrated olive-waste cake as a source of high value-added bioproduct: Drying kinetics, physicochemical properties, and bioactive compounds

Uribe¹,

Lemus‐Mondaca²,

Pastén³

et al. 2014

Chilean J. Agric. Res.

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Olive (Olea europaea L.) oil processing produces significant amount of waste that can be utilized for the production of high value-added ingredients for various industrial applications. In this work, the effects of temperature on drying kinetics and quality indexes of the olive-waste cake during convective dehydration (40-90 °C) were investigated. Results on effective moisture diffusivity, physicochemical parameters, fatty acid profile, total phenolic, flavonoid, and flavanol contents as well as antioxidant capacity are also reported. Most of the fatty acids increased their content with respect to control sample with a temperature increase, i.e. oleic and linoleic acids increased 48% and 43% at 70 and 40 °C, respectively. Total flavanol content increased with temperature (48-62 mg catechin equivalents [CTE] 100 g -1 DM) except for 80 °C. Total phenolic and total flavonoid contents were highly correlated to antioxidant capacity (0.923 < r < 0.992), except for 70 and 80 °C, the rest of the samples maintained their initial antioxidant capacity by ORAC analysis. Thus, these parameters show that dried olive-waste cake has a high bioactive compounds with potential use as additives for the food or other industries.

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“…The activation energy for infrared-dried coated seeds was found to be 33 kJ/mol, which is within the range of 12 -110 kJ/mol reported for several agricultural materials [15][16][17][18] …”

Section: Influence Of Shrinkage On Effective Moisture Diffusivitymentioning

confidence: 63%

“…An increase in drying rates with an increase in IR radiation power or intensity has commonly been reported in the literature [7][8][9][10][11][12][13][14][15][16][17][18]. Table 1 summarizes the values of moisture flux density during the constant flux period (N w,c ), critical moisture content (X cr ), and critical drying time (t cr ) for all IR source temperatures (T IR ) investigated in this study.…”

Section: A M B Neto Et Almentioning

confidence: 99%

“…A lot of work has been devoted to the research on IR drying of various materials, such as: paper [10], polymers [7], pharmaceutical films [11], paints and pigments [12,13], hydrous ferrous sulphate [14], and agricultural products [15][16][17][18]. However, there is still no information available in the literature regarding the use of IR radiation for drying systems composed by seeds coated by gel-based polymeric matrices.…”

Section: Introductionmentioning

confidence: 99%

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Mass Transfer in Infrared Drying of Gel-Coated Seeds

Neto¹,

Marques²,

Prado

et al. 2014

ACES

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In order to contribute for a better understanding of mass transfer in drying of shrinking particles, in this study shrinkage and drying characteristics of sorghum seeds encapsulated into gel-based polymeric matrix were experimentally determined by using infrared (IR) radiation. IR drying of gel coated seeds was carried out at three different temperatures (65˚C, 80˚C and 93˚C). The shrinkage of the individual particles during drying was quantified by means of the volume and surface area changes evaluated from geometric measurements. The product quality was evaluated in terms of the changes of particle density and percent of cracks in gel coating incurred during drying. Surface area and volume of the gel-seed system decreased about 65% and 80% until the end of the process, respectively, stressing the need to take into account the surface area changes to calculate water flux density as function of moisture content and obtain an accurate interpretation of the drying mechanisms well as to include the volume shrinkage in mass transfer models to determine reliable values of moisture diffusivity. The IR drying behavior of gel-coated seeds was then characterized by the presence of three drying periods: heating up, constant moisture flux and falling moisture flux. Accelerated drying of gel coated seeds was obtained by applying higher IR radiation intensities. The effect of IR source temperature on the particle shrinkage was more pronounced at the constant moisture flux period and practically negligible at the decreasing moisture flux period. Neglecting shrinkage of individual coated-seeds during IR drying led to an erroneous absence of constant flux period and overestimation of the mass transfer by diffusion. Apparent density of the particles was greater at lowtemperature IR drying than at high-temperature IR drying. Coated particles keep their original geometry, but a significant cracking of gel coating was observed at rapid drying rate conditions.

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Mathematical modelling of thin-layer infrared drying of wet olive husk

Cited by 108 publications

References 28 publications

Olive Mill Wastewater: From a Pollutant to Green Fuels, Agricultural Water Source and Bio-Fertilizer—Part 1. The Drying Kinetics

Olive Mill Wastewater: From a Pollutant to Green Fuels, Agricultural Water Source and Bio-Fertilizer—Part 1. The Drying Kinetics

Dehydrated olive-waste cake as a source of high value-added bioproduct: Drying kinetics, physicochemical properties, and bioactive compounds

Mass Transfer in Infrared Drying of Gel-Coated Seeds

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