Modeling Of Drying Kinetics Research Articles

Heat pump drying kinetics modeling and prediction for Lentinus edodes based on orthogonal experimental

To accurately understand the moisture variation and drying characteristics of Lentinus edodes (L. edodes) during the drying process, the kinetics model of L. edodes with a wider application range was investigated. First, the heat pump drying kinetics model for L. edodes was fitted, verified and extended based on the orthogonal experimental data. Then, the expression of moisture ratio of L. edodes with respect to drying time, air supply temperature (AST), loading density (LD) and circulating air volume (CAV) was proposed, and interaction effects of the three key parameters on the drying time were studied based on the prediction model. The findings indicated a substantial agreement between the predicted and experimental values. The drying time could be shortened by increasing the air supply temperature and the circulating air volume or decreasing the loading density. Among these three factors, the AST had the greatest impact on drying time, followed by CAV and LD. For every 48 g/m2 reduction in LD and 11.3 m3/h increase in CAV, the drying time could be reduced by 10.5 to 29.9 minutes. Similarly, increasing the AST by 1 °C and the CAV by 11.3 m3/h could decrease the drying time by 13.7 to 100.6 minutes. The research results are helpful to optimize the drying process, improve the drying efficiency, and provide guidance and references for practical production of L. edodes HPD.

Drying kinetics and mathematical modeling of coconut meat slices: Insight into pretreatment and drying synergic effect

Coconut consumption provides nutritional and health benefits to humans. Yet, poor postharvest and preservation methods result in the loss of coconut fruit bunches yearly. Investigations into achieving drying techniques that result in optimum drying rates coupled with consumer's desired end products that are both commercially and nutritionally viable remain paramount in the food industry. Consequently, osmotic dehydration is commendable for its low-cost pretreatment merit. Therefore, the study examined the drying-kinetics, energy consumption, effective moisture diffusivity (Deff), vitamin C retention, color, and rehydration behavior of coconut cultivars (Sri Lanka Green Dwarf × Vanuatu Tall (SGD × VTT), Catigan (CAT), and Tacunan Green Dwarf (TGD)) meat slices. Samples were osmotically pretreated with sucrose solution (30 %/30 min) and subjected to oven drying (80, 90, 100, and 110 °C (air velocity of 2 m/s) and lyophilization (−45 ± 2 °C) methods. A mathematical model was employed to predict the effect of osmotic pretreatment on drying dynamics and the assessment of utilized energy, vitamin C content, color, and rehydration of coconut meat slices at different drying conditions. The oven-dried sample's color changed (p < 0.05) compared to lyophilized samples. Drying-kinetics models were validated using determination coefficient (R2) and root mean square error (RMSE). The Asymptotic model satisfactorily suited the samples' drying data goodness fitting based on R2≥0.90−0.99 and low RMSE ≤0.01−0.12 compared to other models for both drying methods. Deff ranged between 1.10 × 10−07 m2s−1 and 7.90 × 10−08 m2s−1 for all the drying methods. CAT sample retained high vitamin C content compared to SGD × VTT and TGD samples. Rehydration ratio values were significant at lower temperatures among oven-dried experimental samples whereas TGD samples exhibited a significant rehydration values compared to SGD × VTT and CAT lyophilized samples. Among the drying methods, oven drying exhibited low energy consumption with shorter drying time and optimum Deff per adopted temperature ranges compared to lyophilization. The study revealed that temperature, time, the sucrose solution, and the thickness of the coconut slices strongly influenced the drying kinetics of the osmotically pre-treated coconut meat slice's drying features.

Experimental analysis and development of novel drying kinetics model for drying grapes in a double slope solar dryer

This experimental study aimed to evaluate the efficacy of natural and forced convective drying techniques in reducing the moisture content of the grapes in comparison with the conventional open sun drying method. Moisture effective diffusivity and activation energy were graphically determined using the Arrhenius equation. In the initial three-day period, forced convection drying significantly reduced moisture from 2000 g to 353 g, with a minimum loss of 14 g. In the next three days, natural convection reduced moisture from 2787 g to 468 g, with a minimum loss of 11 g. These outcomes were then compared to the results of open-sun drying. The investigation showed that open drying and natural convection methods eliminated 25.05 % and 82.35 % of the moisture content, respectively. However, for three days, open-sun drying removed 30.5 % of grape moisture, while forced convection achieved an impressive 83.21 % reduction. The study's innovative mathematical model explained drying curve characteristics, supported by correlation coefficients and parity plots. The comparison shows that the experimental moisture ratios and those predicted by the new correlation exhibit R2 values ranging from 0.984 to 0.994.

Kinetic study and modelling of drying of Chlorellavulgaris

Microalgae, a versatile source of biofuels, chemicals, and nutraceuticals, necessitates efficient drying for subsequent applications. Extensive studies have been done on the benefits and uses of microalgae, but very few are focusing on drying. This research focused on a specific microalga, Chlorella vulgaris, to analyze the drying kinetics involved in the moisture removal process. Data on drying behavior were collected using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). As the temperature rose, the moisture content of the biomass rapidly decreased and peaked between 65 and 80 °C. From four widely used drying kinetics models, which are typically used to analyze the drying kinetics of agricultural goods, four non-isothermal drying models were derived. These models were assessed using the coefficient of determination (R2) and reduced chi-square (χ2). Page's model emerged as the best fit for describing drying kinetics. This study introduces a novel approach to characterize the intrinsic properties of freshly harvested Chlorella vulgaris by employing TGA and DSC. Unlike other studies focusing on conventional drying methods, our investigation provides real-time insights into the microalgae's thermal behavior during drying.

Quality Parameters and the Modeling of the Microwave Drying Kinetics of Basil ‘Nufar’ (Ocimum basilicum L.) Leaves

Quality Parameters and the Modeling of the Microwave Drying Kinetics of Basil ‘Nufar’ (Ocimum basilicum L.) Leaves

Convective drying of bitter yam slices (Dioscorea bulbifera): Mass transfer dynamics, color kinetics, and understanding the microscopic microstructure through MATLAB image processing

The objective of this research endeavor was to enhance the quality and storability of Dioscorea bulbifera through the investigation of the effects of pre-treatment (soaking) and different dehydration temperatures (50, 60, and 70°C) on its mass transfer, color kinetics, texture, microstructure, and rehydration properties. Ten drying and four-color kinetics models were employed to describe drying behavior and color changes. The drying process demonstrated a falling rate, with reduced drying time (from 960 to 540 min) as the convective temperature increased from 50 to 70°C. Moisture diffusivity increased with increasing hot air temperatures (4.15 ×10–10 – 1.03 ×10–9 m2/s), and the activation energy was determined as 41.82 kJ/mol. Slices dried at 70 °C exhibited higher color change than those dried at 50°C. The modified color model fitted the best color parameters, followed by the fraction model. Slices dried at 60°C showed lower hardness (34.73 N) and higher porosity (27.03 %) as compared with 50°C (49.33 N and 19.82 %) and 70°C (40.16 N and 21.90 %) temperature. Microstructure, moisture diffusion, and texture were closely linked to temperature and moisture content. Boiling and potassium metabisulfite significantly affected drying rate and texture of yam slices . MATLAB analysis provided detailed pore information for each hot air-dried sample, correlating with texture characteristics. This research offers substantial industrial significance by providing methods to enhance dried yam products' quality, shelf-life enhancement, and further exploration of starch extraction and recovery of valuable bioactive compounds.

The effect of drying temperature and material thickness on the drying characteristics and drying kinetics of curcuma drying using an oven

Curcuma is a plant that has medicinal, anti-bacterial, anti-diabetic, anti-hepatotoxic, anti-inflammatoryand anti-tumor properties. Curcuma sold in the market is still fresh rhizomes, so it is impractical and clean and can potentially decrease in quality if stored for a long time. One of the efforts to produce good quality curcuma is the drying process. This study aims to analyze the effect of drying temperature and material thickness on the drying characteristics and drying kinetics of curcuma drying using an oven. Based on this research, it is known that the initial moisture content of content at drying temperature variations of 50, 60 and 70°C is 8.59%, 8.82% and 6.28% (dry base) and after drying, it becomes 0.58%, 0.36% and 0.17% (dry base). The initial moisture content at thickness variations of 5, 10and 15 mm was 8.59%, 5.67% and 3.6% (dry base) and after drying, it became 0.58%, 0.25% and 0.12 % (dry base). Characteristics of curcuma drying using an oven consist of three stages of the drying period. The drying kinetics models suitable for this study are the Page, Logarithmic and Verma et al. models, with R2 values ranging from 0.9737 to 0.9988.

Experimental study on moisture diffusivity, activation energy, and mathematical modeling of drying kohlrabi under different solar drying methods

AbstractThe assessment and enhancement of any drying system for optimal drying processes relies on critical parameters, namely moisture diffusivity and activation energy. In this study, medicinally beneficial kohlrabi of 40‐mm diameter and 6‐mm thickness samples were dried under three different drying methods, namely open sun drying (OSD), natural air‐circulation mode (NACM) single slope direct solar dryer (SSDSD), and forced air‐circulation mode (FACM) SSDSD. The experimental results showed that the drying chamber operating temperature and air velocity played significant roles in the moisture diffusion process and activation energy required to dry the kohlrabi sample. The FACM exhibited the highest average moisture diffusivity values at 7.29 × 10−10 m2/s, surpassing both NACM (5.65 × 10−10 m2/s) and OSD (3.28 × 10−10 m2/s). The activation energy needed for the drying process was the lowest in FACM at 27.44 kJ/mol, followed by NACM at 31.37 kJ/mol and OSD at 35.29 kJ/mol. This is due to the uniform temperature distribution and high airflow rate in the case of FACM. Additionally, 10 thin‐layer models were tested for all three experimental conditions. The statistical analysis showed that for OSD and NACM, the Midilli et al. model, and for FACM, the Page model was best suited for representing drying kinetics with lowest χ2 and root mean square error and highest R2 values. Furthermore, the energy and exergy assessment guaranteed an evaluation of the solar drying system's efficiency.Practical applicationsThis research provides valuable insights into optimizing solar drying methods for kohlrabi preservation. Understanding how temperature and air velocity influence moisture diffusivity and activation energy allows practitioners to enhance drying efficiency. Forced air‐circulation mode (FACM) single slope direct solar dryer (SSDSD) emerges superior, with higher moisture diffusivity and lower activation energy. The study also identifies appropriate drying kinetics models for each method, aiding the accurate prediction of drying behavior. Emphasizing efficiency, the research highlights FACM's superior thermal efficiency and natural air‐circulation mode's higher exergetic efficiency. These insights empower practitioners to make informed decisions, potentially improving agricultural product preservation, reducing energy consumption, and promoting sustainability. Moreover, the research's findings hold significant implications for industrial food processing and preservation applications, suggesting the direct implementation of optimized solar drying techniques in large‐scale settings for kohlrabi and similar agricultural products.

Drying kinetics modeling of hot air drying of emulsion templated oleogels employing hydroxypropyl methylcellulose as structuring agent

This work focused on the drying of O/W emulsions employed to obtain templated structured oils with hydroxypropyl methylcellulose (HPMC) as oleogelator. Sunflower oil/water emulsions with different HPMC content (1%–3% w/w) were dried at different air temperatures (from 70 to 100 °C) employing two different initial thicknesses (0.25 and 0.50 cm). Drying kinetics showed the existence of an initial constant drying rate period followed by a falling drying rate period below critical moisture content. This critical content was constant (0.38 kg water/kg dry solid) independently of drying conditions and HPMC content. Drying rate decreased linearly with moisture content during the falling rate periods. A 3-parameter model was proposed to simulate drying kinetics in the range of drying temperature and HPMC content of tested oleogels. Physical properties of fresh and stored (20 days) oleogels such as oil binding capacity, color, and hardness were measured to evaluate drying conditions effect on product quality. Temperatures above 70 °C were necessary to promote the HPMC gelation. Best characteristics of oleogels in terms of texture, color and oil binding capacity were obtained with HPMC content of 2% w/w, 0.25 cm of emulsion thickness and 80 °C of drying temperature. These results are useful for the design of large-scale dryers for this new kind of products.

Microwave drying of yerba mate leaves: kinetics modeling and techno-economic analysis

Ilex paraguariensis, known as yerba mate, is a native species from South America widely used in the preparation of drinks, with several bioactive compounds. Its industrial drying process is archaic and associated to the contamination of the leaves with carcinogenic compounds. Previous study reported microwave drying of yerba mate as a potential alternative for its drying, but there are no studies on the techno or economic aspects of this process. Hence, this study aims to determine the drying kinetics on the yerba mate leaves (YML) using the microwave assisted drying method, and to provide a techno-economics analysis for different production and rate of return of investment scenarios. Microwave drying (MWD) of yerba mate was conducted at different powers (675, 945, and 1,215 W), and conventional kinetics models were fitted to the experimental data. A techno-economics analysis was conducted considering the processing of 10 – 100 kg YML/h in an agribusiness located in South Brazil. As results, the different microwave powers resulted in different equilibrium moisture content, and only the MWD at 1,215 W achieved Brazilian’s legislation requirement of 10 % of moisture (wet basis). Page’s drying kinetics model presented the best fitting to the experimental data, and its parameters were used in the study of economic viability. Finally, a required selling price of 19.88 US$/kg was calculated for the selling of the dried YML, resulting in a time of return of investment of 1 year for an agribusiness processing 100 kg YML/h.

Drying kinetics of rice using a flatbed dryer with a hot air source from a biomass waste pyrolysis reactor

This study aims to evaluate the process of rice drying using a flatbed dryer integrated with a biomass waste pyrolysis reactor as a heat supplier. The integration of dryer equipment with pyrolysis reactor aims to replace the use of fossil fuel energy with biomass as an eco-friendly source and abundantly available in nature. The current investigation assessed how tray height and drying temperature affected rice’s moisture ratio, drying rate, and drying characteristics. The drying air temperature of 70°C and the tray height of 40 cm were found to yield the optimum drying outcomes, according to the results. The best drying kinetics model that can describe the rice drying process is the Page model.

Effect of drying kinetics model on energy efficiency of drying systems

The effect of drying kinetics models on the energy efficiency of a conveyor-belt convective drying system was investigated. Experiments were conducted on the material to be dried, and the system was modeled using two drying kinetics models. Mathematical models incorporating the drying kinetics model were used to create a module that designs the drying system under given operating conditions. A comparison of the design results of two drying kinetics models under various operating conditions demonstrated that the total drying time of the material can be incorrectly estimated by an average of 35 % when an inappropriate model is used. Furthermore, this inaccurate estimation of the drying time leads to the total energy usage of the system being up to 32 % higher than necessary. These results demonstrate that a good dryer design cannot be guaranteed merely by using experimental data of the material to be dried; the design process must include selection of the most suitable model among various models considering the drying characteristics. Consequently, an appropriate algorithm that incorporates the selection of suitable drying kinetics models can contribute to reduced energy consumption and carbon emissions in various energy-intensive drying processes, especially with the widespread use of conveyor-belt dryers.

MODEL KINETIKA PENGERINGAN MANISAN MANGGA (Mangifera indica L.)

To improve control over the drying process and the quality of the dried products, it is essential to comprehend the drying kinetics model. This study aim to find the best thin-layer drying kinetics model for box-shaped candied mangoes dried in a rotary oven. The source of the data is Rozana’s (2016) research into the moisture content and drying times of candied mangoes at 45 and 50°C in a rotating oven. The Lewis, Page, Henderson and Pabis, Logarithmic, Two Term, Two Term Exponential, Diffusion Approximation, Midilli et al., and Modified Henderson and Perry models are among the kinetic models used. The moisture ratios of mangoes collected during drying at various time intervals were used to fit drying models in order to predict the moisture ratio. The model with the highest coefficient of determination (R2), the lowest root mean square error (χ2), and the lowest root mean square error (RMSE) is the best drying kinetics model. The Midilli et al. model was determined to be the most appropriate drying model for box-shaped candied mangoes dried in a rotating oven with R2 of 0,9989, χ2 of 0,0001, and an RMSE value of 0,0074 for a temperature of 45°C; and R2 is 0,9973, χ2 is 0,0002, and RMSE is 0,0137 at 50°C. The Midilli et al. model equations obtained is MR=1,026 exp(-0,0007t1,0706)+0,0001t at 45°C and MR=1,0129exp(-0,0003t1,3568)+0,0002t at 50°C.

Experimental Study and Drying Kinetics Modeling of an Alkali-Activated Sand-Based Porous Medium, Application to Drying of Inorganic Foundry Cores

Experimental Study and Drying Kinetics Modeling of an Alkali-Activated Sand-Based Porous Medium, Application to Drying of Inorganic Foundry Cores

Mathematical-Based CFD Modelling and Simulation of Mushroom Drying in Tray Dryer

In this study, CFD simulations that incorporate the inherent coupling between the moisture content of the mushroom and hot air flow in the tray dryer were performed. Conservation principles were applied to the fundamental quantities of mass, momentum, and heat. The source terms due to the moisture evaporation, the viscous and inertial resistance, and continuous evaporative cooling were determined through experimental results. Experiments were conducted to study and select the drying kinetics model at the optimum drying conditions and moisture sorption isotherm model at 30, 40, and 50°C temperatures. The best model describing the drying kinetics of mushrooms and moisture sorption isotherm model was chosen based on the lowest RMSE values and the highest R 2 value. Midilli et al.’s drying kinetics model and the modified Henderson sorption isotherm model were adopted in CFD modelling. The CFD software ANSYS Fluent was used for the 3D modelling of mushroom drying in a tray dryer. The mass and energy source term equations were added to the ANSYS Fluent software using a user-defined function (UDF). The parameter permeability of medium ( α ) and pressure-jump coefficient ( C 2 ) appearing in the momentum source term were directly introduced in the Fluent setup as cell zone conditions. The simulation results of the moisture removal and drying temperatures were validated against experimental data. Both results are in good agreement with the experimental data, with R 2 values of 0.9906 for moisture contents and 0.926 for drying temperature. Thus, simulation can be an option to study the drying mechanisms and alleviate some drawbacks of doing experiments.

Mathematical Modeling of Thin-Layer Drying Kinetics of Tomato Peels: Influence of Drying Temperature on the Energy Requirements and Extracts Quality.

Tomato drying implies high energy consumption due to the high moisture content, and limiting drying temperatures is necessary to avoid carotenoid degradation. To explain the mechanism of moisture transport through the material and to scale up the drying process, drying experiments are needed and supported by mathematical modeling. For the Rila tomato peel drying process, ten thin-layer mathematical models were formulated based on experimental data for six temperatures (50-75 °C) and validated by statistical analysis. Considering the slab geometry of the peels sample and Fick's second law of diffusion model, the calculated effective moisture diffusivity coefficient values Deff varied between 1.01 × 10-9-1.53 × 10-9 m2/s with R2 higher than 0.9432. From the semi-theoretical models, Two-term presents the best prediction of moisture ratio with the highest R2 and lowest χ2 and RMSE values. Using the experimental data on extract quality (carotenoid content), two degradation models were formulated. Increasing the drying temperature from 50 °C to 110 °C, a degradation of 94% for lycopene and 83% for β-carotene were predicted. From the energy analysis, a specific energy consumption of 56.60 ± 0.51 kWh is necessary for hot-air drying of 1 kg of Rila tomato peel at 50 °C to avoid carotenoid degradation.

Experimental determination of dynamic pseudo-equilibrium moisture content: A practical limit for the drying process

Simulation and rigorous design of industrial dryers combine a large number of models, which feed three fundamental balances: (1) mass; (2) energy; and (3) quantity of movement of the material through the dryer. Many of these models represent physical phenomena affecting the three balances at the same time, which makes these calculations extremely complex, hence, accurate models are essential. The hypothesis that the kinetic stage of drying of any material culminates in the thermodynamic moisture equilibrium between solid and drying gas has been in effect for many years. However, recent findings show that there is a transition stage between the kinetic stage and the thermodynamic equilibrium, which, experimentally, looks like an equilibrium. The beginning of this transition stage or dynamic pseudo-equilibrium stage would mark the end of the drying kinetics models, which has been named as the dynamic pseudo-equilibrium moisture contents (Xdpe). The non-observance of this phenomenon presupposes a model limited in its prediction capacity, especially in the last stages of drying and even more so at low drying temperatures. As a consequence, sizes of industrial dryers could be underestimated during the simulation and rigorous design process, or underestimate drying times, in batch dryers. On the other hand, the optimal conditions may never be found, during the optimization of existing industrial drying processes. The objective of this work is to present the procedure to determine Xdpe, during the experimental determination of drying curves of any material. Likewise, to propose the practical moisture ratio, which uses Xdpe, instead of the equilibrium moisture, to be used in the modeling of the drying kinetics.•The drying process is divided into three stages: kinetic, transition, and equilibrium.•The dynamic pseudo-equilibrium moisture content divides the kinetic and the transition stages.•The practical moisture ratio should be used in rigorous industrial dryer design calculations.

Mechanistic modeling of semicontinuous fluidized bed drying of pharmaceutical granules by incorporating single particle and bulk drying kinetics

In this work, a mechanistic fluidized bed drying model computing the granule moisture content in function of granule size, drying time, process settings and formulation properties is developed. Modeling the moisture content distribution concerning the granule size is essential for tabletability and drug product quality. This work combines a mechanistic bulk model and a single-particle drying kinetics model in a semicontinuous mode. The added model complexity allows physical approximations of drying phenomena at both the drying system level and the granular level. This includes quantifying the variations in moisture content by taking into account the specific dryer design and the variations in granule size. The model performance was quantified through industrially relevant case studies. It was revealed that the proposed model structure accurately predicts the drying behavior of the yield fraction. However, systematic model biases were observed for the fine and coarse fractions of the granule size distribution. In addition, discrepancies in the predicted outgoing air properties (relative air humidity and air temperature) were obtained. Further enhancement of the model complexity, e.g. complete incorporation of fluidization and segregation phenomena, is likely to improve the model performance. Notwithstanding, the developed model forms a step towards a formulation-generic fluidized bed drying model as interacting mechanisms on different levels of the drying system are considered.

Mathematical modelling of wheat drying by fractional order and assessment of transport properties

AbstractThe purpose of this study is to evaluate both the temperature and the initial moisture content of the material in mathematical models of drying. For this, empirical lumped parameter models were fitted based on experimental data of moisture over time. Furthermore, a new semi‐empirical drying kinetics model was applied. This model was developed using the generalization of arbitrary order of the Lewis equation obtained through the Laplace transform. After performing the fit, the fractional order model for drying wheat seeds as a temperature function was generalized. Distributed parameter models were also fitted to evaluate the influence of initial moisture content on drying kinetics and to estimate the moisture profile along the position inside the seed. It was verified that the fractional order model presented statistical results similar to models with a higher number of constants, being used to generalize the kinetic drying model for the three wheat cultivars. Generalized models showed better fits for the 3 cultivars with first‐degree function, and the maximum global deviation was 10%, 15%, and 20% for the cultivars BRS–Atobá, BRS–Jacana, and BRS–Sanhaço, respectively. In addition, the distribution of moisture content inside the seed was verified by the distributed parameter model, which predicted the experimental data with an overall deviation of around 10%.

Microwave-assisted drying of Ocimum sanctum leaves: Analysis of moisture content, drying kinetic model, and techno-economics

This study aims to evaluate the drying kinetics of basil leaves using microwave-assisted drying (MAD) to determine moisture content, moisture ratio, drying rate, and economic analysis at various microwave power levels (136, 264, 440, and 616 W). This study discusses the economic analysis between microwave versus oven drying and this study has not been discussed in other studies. The leaves of basil are: 2.83 ± 0.1831 × 1.42 ± 0.1398 cm (small leaves); 4.08 ± 0.1619 × 1.83 ± 0.1059 cm (medium leaves); 6.16 ± 0.1713 × 2.70 ± 0.2357 cm (large leaves). They evaluated each condition using five thin layer models: Henderson and Pabis, Midilli et al., Hii et al., Verma et al., and Diffusion Approximation. Coefficient of correlation (R2), Chi-square (X2), Sum of Square Error (SSE), Root Mean Square Error (RMSE), and Mean Square Error (MSE) were used as the statistical parameters to determine the best drying kinetics model. The results show that the Hii et al. model is the most appropriate. An economic study was conducted between the selected microwave-assisted drying kinetics model and the optimum oven drying conditions from previous research results. Using 17 microwaves resulted in a Rate of Investment (ROI) of 46.9188%, Break Even Point (BEP) of 37.1189%, and interest rate (i) of 0.0094%. While using the 17 ovens resulted in an ROI calculation of 30.5957%, BEP of 43.6197%, and interest rate (i) of 0.0465%. Thus the microwave-assisted drying is more optimum than the oven drying. This research is expected to be useful for industry or further research in food science and the food industry.