Surface‐center temperature differences within milk droplets during convective drying and drying‐based Biot number analysis

Patel, Kamleshkumar Chhanabhai; Chen, Xiao

doi:10.1002/aic.11608

Cited by 33 publications

(17 citation statements)

References 36 publications

(98 reference statements)

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“…Profiles of Bi tend to increase at the end of drying, but profiles of Ch_Bi during drying time are more complex because evaporation flux and temperature difference of drying air temperature and surface temperature are taken into account in the calculation. Patel and Chen [52] found a similar phenomenon for analysis of Biot number of milk droplets. However, at the end of the drying process, the temperature difference between sample and the drying medium is becoming smaller and does not lead to practical problems in modeling.…”

Section: Analysis Of Biot Number (Bi) and Chen-biot Number (Ch_bi)mentioning

confidence: 53%

Modeling of Drying of Food Materials with Thickness of Several Centimeters by the Reaction Engineering Approach (REA)

2011

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Food materials are highly perishable. Drying is necessary to restrict biological and chemical activity to extend shelf life. A good drying model is useful for design of a better dryer, evaluation of dryer performance, prediction of product quality, and optimization. The reaction engineering approach (REA) is a simple-lumped parameter model revealed to be accurate and robust to model drying of various thin layers or small objects. Modeling drying behavior of different sizes is essential for a good drying model, yet it is still very challenging, even for a traditional diffusion-based model, which requires several sets of experiments to generate the diffusivity function. The REA is implemented in this study, for the first time, to model drying of rather thick samples of food materials. An approximate spatial distribution of sample temperature is introduced and combined with the REA to model drying kinetics. Results have indicated that the REA can model both moisture content and temperature profiles. The accuracy and effectiveness of the REA to model drying of thick samples of food materials are revealed in this study. This has extended the application of REA substantially. The application of the REA is currently not restricted for thin layesr or small objects but also for thick samples.ALAS (Australian Leadership Award Scholarship

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Section: Analysis Of Biot Number (Bi) and Chen-biot Number (Ch_bi)mentioning

confidence: 53%

Modeling of Drying of Food Materials with Thickness of Several Centimeters by the Reaction Engineering Approach (REA)

2011

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“…The relative activation energy profiles for skim milk concentrates of different initial moisture contents are shown in Figure 1. For skim milk having 20 and 30 wt% (all dry basis) initial solids contents, the relative activation energy profiles were evaluated using weight loss and temperature data directly from the experimental work and equations (1) and (2) [17,77], while for 40 wt% and higher solid concentrations these profiles were approximated using a method shown by Patel et al [79]. A comparison of these relative activation energy curves in Figure 1 provides an insight for using an appropriate fingerprint.…”

Section: Reamentioning

confidence: 99%

“…Temperature gradients across the droplet can be assessed using a method proposed by Patel and Chen [77]. If the temperature 1-D Simulation of spray drying -pros & consgradients are small or exist only for a short drying period, the assumption of uniform temperature can be used when estimating the droplet's average temperature profiles using equation (6) [77,78].…”

Section: Heat Balancementioning

confidence: 99%

“…If the temperature 1-D Simulation of spray drying -pros & consgradients are small or exist only for a short drying period, the assumption of uniform temperature can be used when estimating the droplet's average temperature profiles using equation (6) [77,78]. The temperature profile of hot gas can be evaluated using the following heat balance [71]:…”

Section: Heat Balancementioning

confidence: 99%

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One-dimensional simulation of co-current, dairy spray drying systems – pros and cons

Patel

Chen

Jeantet

et al. 2010

Dairy Sci. Technol.

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-One-dimensional (1-D) simulation is a useful technique for the evaluation of dryer operating parameters and product properties before conducting real spray drying trials. The main advantage of a 1-D simulation tool is its ability to perform fast calculations with significant simplicity. Mathematical models can be formulated using heat, mass and momentum balances at the droplet level to estimate time-dependent gas and droplet parameters. One of the purposes of this paper is to summarize key mathematical models that may be used to perform 1-D simulation for spray drying processes, predict essential product-drying gas parameters, assess the accuracy of prediction using pilot-scale spray drying data and perhaps most importantly address the main benefits and limitations of the 1-D simulation technique in relation to industrial spray drying operations. The results of a recent international collaborative study on the development of spray drying process optimization software for skim milk manufacture are presented as an example of the application of 1-D simulation in milk processing.spray drying / one-dimensional simulation / modeling / drying kinetics / dairy product / droplet drying Article published by EDP Sciences à l'échelle de la gouttelette pour estimer les paramètres de vapeur et de gouttelette qui varient au cours du temps. Un des objectifs de cet article est de présenter de façon synthétique les modèles mathé-matiques clés qui peuvent être utilisés pour réaliser une simulation 1-D, prédire les paramètres de vapeur essentiels pour le séchage du produit, évaluer la précision de la prédiction en utilisant les données du séchage par atomisation obtenues à l'échelle pilote, et enfin d'aborder les principaux bénéfices et limites de la technique de simulation 1-D en relation avec les opérations de séchage par atomisation industrielles. Les résultats d'une récente étude réalisée en collaboration internationale sur le développement d'un logiciel d'optimisation du procédé de séchage par atomisation pour la production de poudre de lait écrémé sont présentés pour illustrer l'application de la simulation 1-D.séchage par atomisation / simulation mono-dimensionnelle / modélisation / cinétique de séchage / produit laitier / séchage d'une gouttelette

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“…[53] When material is thermally thin, the surface temperature is considered to be the same as the sample temperature; that is, T s % T. [54,55] The mass balance (Eq. (1)) is then expressed as…”

Section: Putranto and Chenmentioning

confidence: 99%

Examining the Suitability of the Reaction Engineering Approach (REA) to Modeling Local Evaporation/Condensation Rates of Materials with Various Thicknesses

Putranto

Chen

2013

Drying Technology

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The reaction engineering approach (REA) is examined here to investigate its suitability as the local evaporation rate to be used in multiphase drying. For this purpose, REA is first implemented to model the convective drying of materials with various thicknesses. The relative activation energy, as the fingerprint of REA, generated from one size of a material is used to model the convective drying of the same material with different thicknesses. Because the results indicate that REA parameters can model the drying of materials with various thicknesses, REA can be scaled down to describe the local evaporation rate (at the microscale as affected by local composition and temperature). The relative activation energy is used to describe the global drying rate in modeling the local evaporation rate. REA is combined with a system of equations of conservation of heat and mass transfer in order to yield the spatial reaction engineering approach (S-REA) as a nonequilibrium multiphase drying model. By using S-REA, the spatial profiles of moisture content, concentration of water vapor, temperature, and local evaporation rate can be generated, which can assist in comprehending the transport phenomena. INTRODUCTIONDrying is a process of water removal involving simultaneous heat and mass transfer. The study of drying is important because drying is an energy-intensive process and affects product quality. Several drying schemes, controlled drying operations, and process intensification of drying need to be implemented to minimize energy consumption during drying and maintain the product quality of the materials being dried. [1][2][3][4] Innovative dryer process designs and dryer operating conditions have been

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Surface‐center temperature differences within milk droplets during convective drying and drying‐based Biot number analysis

Cited by 33 publications

References 36 publications

Modeling of Drying of Food Materials with Thickness of Several Centimeters by the Reaction Engineering Approach (REA)

Modeling of Drying of Food Materials with Thickness of Several Centimeters by the Reaction Engineering Approach (REA)

One-dimensional simulation of co-current, dairy spray drying systems – pros and cons

Examining the Suitability of the Reaction Engineering Approach (REA) to Modeling Local Evaporation/Condensation Rates of Materials with Various Thicknesses

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