Vibro-fluidized Bed Dryer Research Articles

Green tea drying in a closed cycle continuous vibro fluidized bed dryer with dehumidified air

There is potential for the development of zeolite as an adsorbent material for drying high-value items. This study aims to compare the green tea drying characteristic utilizing vibro-fluidized bed dryers that operate without dehumidification and with dehumidification. The research was carried out experimentally. The drying chamber was set at temperatures of 50oC, 60oC, and 70oC. In the drying with dehumidification setup, zeolite was placed in a dehumidifier with a weight-to-tea leaf ratio of 1:2.86, 1:3.33, 1:4, and 1:5. The results showed that zeolite's impact on decreasing drying time is effective at a specific temperature, in this case is 60oC. The effect is negligible at low temperatures (50oC), while at high temperatures (70oC) it is minor and drying time is primarily influenced by temperature. Utilizing zeolite for dehumidification can enhance the rate of drying during the falling rate period.

Experimental study on drying characteristic of black tea using agitated vibro fluidized bed dryer

Experimental study on drying characteristic of black tea using agitated vibro fluidized bed dryer

Statistical approach to investigate the effect of vibro‐fluidized bed drying on bioactive compounds of muskmelon ( Cucumis melo ) seeds

Muskmelon seeds hold tremendous potential to be utilized as a source of bioactive compounds as these seeds are discarded as waste during melon processing. Hence, the present study aims to optimize the process parameters of a vibro-fluidized bed drying i.e., temperature (40–60°C), vibration strength (0.55–1.23), and air velocity (7–11 m/s) on bioactive compound of muskmelon seeds. Maximum retention total phenolic content (977.56 mg GAE/100 g), total antioxidant activity (47.84% DPPH reduction), oil yield (50.40%), and linoleic acid content (39.54%) were obtained at optimal conditions of 54.20°C drying temperature, 10.98 m/s air velocity, and 1.23 vibration intensity with the desirability of 0.917. The effect of temperature in comparison to air velocity and vibration strength is predominant on bioactive compounds retention. Practical applications Muskmelon seeds have been recognized as the proficient source of essential oils and bioactive compounds such as polyphenols and antioxidants, due to which they hold an immense potential to be utilized as a nutritional source in the food and pharmaceutical industries. From optimization of vibro-fluidized bed drying process of muskmelon seeds, it has been confirmed that intervention of vibration in fluidization could produce high-quality dried seeds. Vibro-fluidized bed dryer can be implemented as an alternative drying method to reduce drying time, processing costs, and provide a better quality of the product.

Vibro-Fluidized Bed Drying of Pumpkin Seeds: Assessment of Mathematical and Artificial Neural Network Models for Drying Kinetics

Pumpkin seeds were dried in a vibro-fluidized bed dryer (VFBD) at different temperatures at optimized vibration intensity of 4.26 and 4 m/s air velocity. The drying characteristics were mapped employing semiempirical models and Artificial Neural Network (ANN). Prediction of drying behavior of pumpkin seeds was done using semiempirical models, of which, one was preferred as it indicated the best statistical indicators. Two-term model showed the best fit of data with R2 − 0.999, and lowest χ2 − 1.03 × 10−4 and MSE 7.55 × 10−5. A feedforward backpropagation ANN model was trained by the Levenberg–Marquardt training algorithm using a TANSIGMOID activation function with 2-10-2 topology. Performance assessment of ANN showed better prediction of drying behavior with R2 = 0.9967 and MSE = 5.21 × 10−5 for moisture content, and R2 = 0.9963 and MSE = 2.42 × 10−5 for moisture ratio than mathematical models. In general, the prediction of drying kinetics and other drying parameters was more precise in the ANN technique as compared to semiempirical models. The diffusion coefficient, Biot number, and hm increased from 1.12 × 10−9 ± 3.62 × 10−10 to 1.98 × 10−9 ± 4.61 × 10−10 m2/s, 0.51 ± 0.01 to 0.60 ± 0.01, and 1.49 × 10−7 ± 4.89 × 10−8 to 3.10 × 10−7 ± 7.13 × 10−8 m/s, respectively, as temperature elevated from 40 to 60°C. Arrhenius’s equation was used to the obtain the activation energy of 32.71 ± 1.05 kJ/mol.

A Detailed Study of Vibro Fluidized Bed Dryer Exergy and Energy Models of Tea Process Application

A Detailed Study of Vibro Fluidized Bed Dryer Exergy and Energy Models of Tea Process Application

Drying of Matricaria recutita Flowers in Vibrofluidized Bed Dryer: Optimization of Drying Conditions Using Response Surface Methodology

Drying of Matricaria recutita flower was investigated experimentally in a VibroFluidized Bed Dryer (VFBD). The aim of the present work was to optimize the best operating conditions for the drying of Matricaria recutita flower in the VFBD based on experimental design techniques. Response Surface Methodology (RSM) and Central Composite Design (CCD) based on 4-variable with 5-level have been employed to achieve the desirable possible combinations of frequency of vibration (7-15 Hz), inlet air temperature (36-68 °C), air flow rate (16-24 m3/h), and drying time (30-70 min) for the highest responses in terms of moisture removal (MR) and thermal efficiency (). A full quadratic model was used to describe the effects of individual and interactive parameters on the responses. The analysis of the obtained results showed that the inlet air temperature has the largest effect on responses. The optimal process parameters were as follows: frequency of vibration of 10.88 Hz, inlet air temperature of 64.08 °C, air flow rate of 20.63 m3/h and drying time of 69.11 min in which the predicted value for the MR (%) and  (%) was 86.76 and 53.05, respectively. The proposed optimal conditions were examined in the laboratory and MR (%) and  (%) achieved as 87.12±0.25% and 52.78±0.34%, respectively. The experimental values agreed with those predicted by RSM models, thus indicating the suitability of the model employed and the success of RSM in optimizing the drying conditions.

Static and Dynamic Analysis of Vibro Fluidized Bed Dryer using Finite Element Method

Vibro Fluidized bed dryer is a widely used tea dryer now. Its function is to stop the enzymatic oxidation process and decrease water content up to 2,8-3,8%. The working principle is to use the vibrations generated by the eccentric motor so that the tea powder that runs on the bed will vibrate. The purpose of this research is to model, static and dynamic of vibro fluidized bed dryer. The analysis was to determine the maximum stress and natural frequency of the vibro fluidized bed dryer to the variation of green tea mass being processed. Using dynamic analysis the obtained first three natural frequencies of the vibro fluidized bed dryer were 5,8876 Hz, 9,5267 Hz, and 10,512 Hz. The results showed that at 695 kg tea mass the natural frequency has the same as the excitation frequency. In this case, the safety factor of the vibro fluidized bed dryer is 27.6. It can be concluded that the maximum capacity of the vibro fluidized bed dryer is 695 kg..

The influence of vibrational acceleration on drying kinetics in vibro-fluidized bed

This present work aims to analyze the drying kinetics of alumina particles in vibro-fluidized bed dryer. Observed drying kinetic data were predicted by the empirical Page model. Parameters of the model were estimated for different operating conditions and it was used to evaluate the universality of the dimensionless vibrating parameter. It was obtained different values of the parameters of the Page model for similar values of this vibrating parameter, leading to different drying kinetics, once it depends on the different combinations of amplitude and frequency of vibration. It was concluded that the dimensionless parameter is not unique to set the vibrational effect on drying kinetics.

Vibro-fluidized bed heat pump drying of mint leaves with respect to phenolic content, antioxidant activity, and color indices

Because of high porosity and stickiness of mint leaves, they could not be fluidized well during fluidization. In this study, a vibro-fluidized bed dryer assisted heat pump system was designed and fabricated to overcome this problem. The drying experiments were carried out at temperatures of 40, 50 and 60 ?C. The quality of the dehydrated samples was assessed based on color indices, antioxidant activity, and total phenolic content. Drying process primarily occurred in falling rate period. The effective coefficient of moisture transfer of the samples was increased with air temperature and varied from 4.26656?10-11 to 2.95872?10-10 m2 s-1 for heat pump drying (HPD) method, and 3.71918?10-11 to 1.29196?10-10 m2 s-1 for none-heat pump drying (NHPD) method. The color indices for temperatures of 40 and 50 ?C were very close to each other, whereas by increasing temperature to 60 ?C, a remarkable loss of green color was observed. The highest phenolic content was found in methanolic extract for HPD at 60 ?C, and NHPD at 50 ?C contained the lowest amount of phenolic compounds. NHPD treatments showed lower antioxidant activity compared to HPD treatments at the same temperature due to the longer drying times.

A New Model and Quality of Unfrozen and Frozen Cooked Rice Dried in a Microwave Vibro-Fluidized Bed Dryer

This study aimed to develop a suitable drying model for microwave vibro-fluidized bed drying in a single-mode applicator (MVFB-SMA drying) of cooked rice with and without prefreezing treatment and to investigate the effects of prefreezing treatment and drying temperature (110–185°C) on quality of dried cooked rice. During the process of drying cooked rice from 60 to 10% (wet basis), results indicated that drying rate increased, whereas drying time decreased with prefreezing treatment and increased drying temperature. The drying rate and drying time of unfrozen and frozen cooked rice ranged from 0.196 to 0.497 g water/g dry matter/min and 0.228 to 0.554 g water/g dry matter/min; and from 7 to 2.5 min and 5.5 to 2 min, respectively. A new model was proposed in this study (MR = exp(−k t n ) + bt + c) to compare with 11 commonly used drying models. The new model describes the MVFB-SMA drying data most satisfactorily. The values of effective diffusivity were between 1.70 × 10−7 and 5.72 × 10−7 m2/s for the unfrozen sample and between 1.99 × 10−7 and 5.86 × 10−7 m2/s for the frozen sample. Their activation energy values were 23.66 and 21.19 kJ/mol, respectively. Prefreezing treatment provided a whiter product with a less uniform porous structure and higher bulk density. Slower ability to rehydrate was also observed for the frozen cooked rice dried at 160 and 185°C. An increase in drying temperature resulted in changes in whiteness, microstructure, bulk density, and rehydration capability. No prefreezing treatment and drying at 160°C seemed to be the optimal process condition for cooked rice, ensuring whiteness, a porous structure, low bulk density, and high rehydration capability.

Thesis Summary: Study of a New Atmospheric Freeze Drying System Incorporating a Vortex Tube and Multimode Heat Input

Atmospheric freeze drying (AFD) in a vibro-fluidized bed dryer coupled with an adsorbent and multimode heat input is proposed for dehydration of food products. An experimental setup was designed and built to permit simultaneous application of convection, conduction and radiation heat input to the drying material above its freezing point to ensure sublimation using a vortex tube to produce low temperature dry air. Comparison with AFD using fixed bed, fluidized bed dryer, traditional vacuum freeze drying and heat pump drying were carried out to investigate the viability of this new system. A two-layer moving boundary model was developed to simulate the drying kinetics and temperature scenario of thin slab product. Fairly good agreement was found between the predicted values and the experimental data. Finally a three-dimensional (3D) CFD simulation for a vortex tube is carried out to capture the highly swirling compressible flow behavior and to gain basic understanding of temperature separation process. An experimental setup was built to validate the simulation results.

A Novel Atmospheric Freeze-Drying System Using a Vibro-Fluidized Bed with Adsorbent

Atmospheric freeze drying (AFD) in a vibro-fluidized bed dryer coupled with an adsorbent and multimode heat input is proposed for dehydration of food products at lower cost than the traditional freeze-drying process under vacuum. The aim of this project is to study the proposed AFD system using a vortex tube to produce low-temperature dry air, an alternative for producing dried food products of high quality. An experimental setup was designed and built to permit simultaneous application of convection, conduction, and radiation heat input to the drying material above its freezing point to ensure sublimation. A parametric evaluation over a broad range of possible parameter values was carried out using cubic-shaped potato and carrot as model heat-sensitive products. The influence of various system parameters on drying kinetics, quality, and functional properties of the dried products (color, rehydration properties, and morphology) were investigated. Comparison between physical quality and drying characteristics of the AFD system with AFD using fixed bed, fluidized bed dryer, and also with traditional vacuum freeze drying were carried out to investigate the viability of this new system. Results indicate that proposed system is an alternative to reduce the process time as well as to maintain the product quality at lower cost.

A First Principles–Neural Networks Approach to Model a Vibrated Fluidized Bed Dryer: Simulations and Experimental Results

: This article presents the modeling and simulation of a batch pilot-scale vibrofluidized bed dryer. The model considers the effect of back-mixing by establishing interconnected drying zones. The model's equations consist of the mass and energy balances for each zone in the solid phase, while a complete mixing is assumed in the gas phase. The drying and heat transfer parameters are correlated with the operating conditions by means of three neural networks that have been adapted from data obtained experimentally. The system of algebraic-differential equations provides the solid's moisture content and temperature profiles as a function of time. The model was validated by experiments with turnip seeds. Good fit was obtained using only four drying zones.

Quality Enhancement for Thermosensitive Materials Dried with Solid Carriers

Thermal drying is a widely applied method for dewatering of bioproducts. However, due to high thermolability of biomaterials, such a drying process may cause serious damage of the product quality. To minimize product degradation, the drying of biomass with porous solid carriers was applied. A set of experiments designed by the orthogonal method was carried out in a laboratory vibrofluidized bed dryer. A substantial improvement is documented in the final quality of the products when dried in the presence of a porous solid carrier. The effect of process parameters on quality retention is also presented.

INTERMITTENT DRYING OF CARROT IN A VIBRATED FLUID BED: EFFECT ON PRODUCT QUALITY

ABSTRACT Drying of diced carrot was studied experimentally in a laboratory batch-type vibrofluidized bed dryer (VFB) The kinetics of the degradation reaction of P-carotene chosen as the dominant quality index were determined for various time-temperature conditions. Relationships were obtained for instantaneous concentration of β-carotene, and for the degradation rate constant as a function of moisture content and material temperature. It was shown that the best quality product is obtained when carrot is dried in a VFB dryer down to the critical moisture content, than conditioned (tempered) in a single layer exposed to ambient air, and then finish dried to the final moisture content in a VFB dryer.

HYDRODYNAMICS OF VIBRO-FLUIDIZED BEDS

ABSTRACT Vibro-fluidized bed dryers are being extensively used in the industry to dry granular particles of wide particle size distribution. For drying applications of limited air inlet temperature and hard to dry granules--high diffusion resistance of moisture inside the qranules--baffles are normally provided in these dryers to increase the residence time of particles. The residence time distribution of granules in vibro-fluidized bed dryers is of high importance to successfully model such dryers. There has been some studies reported in the literature for average residence time of granules in vibro-fluidized beds without baffles, but there has been no work reported for average residence time in vibro-fluidized beds with baffles and residence time distribution for beds with or without baffles. Experimental runs were carried out in this study in the 0.93 m2 (10 ft2 ) pilot plant vibro-fluidized bed dryer with baffles to determine the residence time distribution of dry granules and granule height profile through the length of the dryer. Among all the dryer operating variables considered in this study, vibration amplitude and baffle spacing were identified as most significant. Values of the average residence time and particle diffusivity were obtained for the entire range of the expected operation of the pilot-scale or commercial scale dryers. These values of average residence time and particle diffusivity, along with the appropriate drying rate (kinetic) data, enable full modeling of vibro-fluidized bed dryers.