Guidelines for the desirable operation of batch freeze driers during the removal of free water

Millman, M. J.; Liapis, Athanasios I.; Marchello, J. M.

doi:10.1111/j.1365-2621.1984.tb01892.x

Cited by 14 publications

(4 citation statements)

References 8 publications

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“…These models describe the transport of frozen water (sublimation model) or the frozen and bound water (sorption sublimation model), investigate the mechanism of heat and diffusion, define stable or unstable processes. The semi‐empirical models are obtained by simplifying the general series solution of Fick's second law that mass transfer mechanism (Millman, Liapis, & Marchello, 2007). This conducted study was performed to investigate the suitability of semi‐empirical models in terms of mass transfer for freeze‐drying process.…”

Section: Resultsmentioning

confidence: 99%

Drying kinetics behavior of turkey breast meat in different drying methods

Elmas

Bodruk

Köprüalan

et al. 2020

J Food Process Engineering

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In this study, turkey breast meat samples were dried with hot air (60, 75, 90 C), microwave (180, 360, 540 W) and freeze (0.1, 0.15, 0.2 mbar) drying and parameters related to the drying kinetics of turkey breast meat were investigated. Although a constant drying rate was not observed for all drying methods, the drying process occurred only during the falling drying rate period. Microwave drying process times were lower than those of hot air and freeze drying because of volumetric heating. Drying times decreased by increasing temperature, power and vacuum pressure. Kinetic parameters were determined by using the semi-empirical models of 2. Fick's diffusion equation. Two terms, Logarithmic and Page models were found to be better for hot air, microwave and freeze drying, respectively. In addition, the effective diffusion coefficient values were found in range of 2.03-2.53 × 10 −10 , 27.89-103.96 × 10 −10 and 2.99-3.36 × 10 −10 m 2 /s for hot air, microwave and freeze drying, respectively. Effective diffusion coefficients increased in direct proportion with temperature, microwave power and vacuum pressure. The activation energy obtained by the modified Arrhenius equation were 7.481 kJ/mol to 6.043 W/g for hot air and microwave drying respectively. Practical Applications The drying kinetics behavior of foods is important for protecting the final product quality, determining the process method and optimizing the process parameters in the food industry. Despite the availability of many drying kinetics studies, meat products exhibit different behaviors during the drying process due to their structure and composition. The drying kinetics behavior of turkey breast meat with different drying techniques was investigated in this study. When the effective diffusion coefficient and activation energy data were considered, it was noticed that microwave drying provided a faster and more effective drying process. The moisture content and water activity values, which are very important especially for meat products, showed that freeze drying provided a more reliable product by reducing the moisture content and water activity of final product more than other drying methods.

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Section: Resultsmentioning

confidence: 99%

Drying kinetics behavior of turkey breast meat in different drying methods

Elmas

Bodruk

Köprüalan

et al. 2020

J Food Process Engineering

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show abstract

“…Such models are unsuitable for RTO purposes as they require long simulation times. Alternatively, 1D models, in which the transition between primary and secondary drying is instantaneous, are operational and yet accurate to describe systems where one of the spatial dimensions is much smaller than the other two [26,31,38,39], as it is the case in the present study. Besides, chamber pressure in the transition between primary and secondary drying has little effect on the desorption kinetics [40,41] and, therefore, on the product quality.…”

Section: The Condenser Modelmentioning

confidence: 94%

Model-Based Real Time Operation of the Freeze-Drying Process

et al. 2020

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Background: Freeze-drying or lyophilization is a dehydration process employed in high added-value food and biochemical goods. It helps to maintain product organoleptic and nutritional properties. The proper handling of the product temperature during the operation is critical to preserve quality and to reduce the process duration. Methods: Mathematical models are useful tools that can be used to design optimal policies that minimize production costs while keeping product quality. In this work, we derive an operational mathematical model to describe product quality and stability during the freeze-drying process. Model identification techniques are used to provide the model with predictive capabilities. Then, the model is used to design optimal control policies that minimize process time. Results and conclusion: Experimental measurements suggest splitting the process into two subsystems, product and chamber, to facilitate the calibration task. Both models are successfully validated using experimental data. Optimally designed control profiles are able to reduce the process duration by around 30% as compared with standard policies. The optimization task is introduced into a real time scheme to take into account unexpected process disturbances and model/plant mismatch. The implementation of the real time optimization scheme shows that this approach is able to compensate for such disturbances.

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“…In this paper, skim milk is selected as reference material. The physical parameters used to define the different work cases developed in this paper have been taken from literature (Liapis & Bruttini, 1994;Mascarenhas et al, 1997;Millman et al, 1984).…”

Section: Methodsmentioning

confidence: 99%

“…Classical freeze-drying references (Litchfield & Liapis, 1979;Millman et al, 1984;Pikal et al, 1983) offer an exhaustive description of the process dynamics, involving a high number of parameters. Still accurate, these models and their subsequent improvements e.g.…”

Section: Introductionmentioning

confidence: 99%

Time-scale modeling and optimal control of freeze–drying

López-Quiroga

Antelo

Alonso

2012

Journal of Food Engineering

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Freeze-drying is considered to be an attractive dehydration method of preserving the quality of high value foods products. Unfortunately, it is an expensive operation, which calls for efficient tools capable of minimizing time and/or energy while preserving product quality. In this work, timescale analysis has been applied to a detailed firstprinciple based model. From such analysis a simplified model, capable of describing freeze-drying at the time scales relevant to quality, has been proposed. The model has been solved by the Finite Element method, showing good agreement with the results in literature. Likewise, the efforts associated with the computation of optimal operation policies have been reduced. In this regard, different operational scenarios that take into account shelf temperature (T L) and chamber pressure (P c) have been considered on a simulation basis. In all cases the resulting optimal control profiles obtained led to significant reductions of cycle time while ensuring product quality.

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Guidelines for the desirable operation of batch freeze driers during the removal of free water

Cited by 14 publications

References 8 publications

Drying kinetics behavior of turkey breast meat in different drying methods

Drying kinetics behavior of turkey breast meat in different drying methods

Model-Based Real Time Operation of the Freeze-Drying Process

Time-scale modeling and optimal control of freeze–drying

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