Soybean Drying Research Articles

Optimization study of soybean intermittent drying in fixed-bed drying technology

ABSTRACTIntermittent drying of materials is an alternative operation that aims at reducing energy consumption, improve the preservation of dried products or decrease effective drying time. Intermittent drying supplies the system with time-varying input air properties that are opposite to traditional operations, where air properties are constant at the dryer inlet. The major objective of this study is to establish the most satisfactory patterns of air temperature and velocity modulation at the dryer entrance to reduce energy consumption. This optimization study was based on a heterogeneous model for the drying of grains in fixed bed validated with experimental data. Intermittent and conventional operation experiments were conducted using equal energy consumption, and the influence of air temperature and velocity modulation on the drying rates related to the percentage of evaporated water were assessed. Results indicated that higher drying rates can be achieved under intermittent operation, and the validated model based on these results could reasonably predict temperature and moisture content profiles. Simulations pointed out that the best modulation patterns of air properties is a function of a variety of system conditions such as initial temperature and moisture content of both soybean and drying air. However, a tendency to reduce energy consumption was observed when the system operation is initially at high temperature and constantly at low velocity.

The air temperature modulation impact on the drying of soybeans in a fixed bed

ABSTRACTThis work aimed to explore an alternative to reduce costs in the soybean drying process using a periodic drying operation, which can enhance mass and energy transfer, leading to lower energy consumption in comparison with the conventional operation carried out with entrance drying air in steady-state conditions. A fixed bed dryer for laboratory scale was used to dry soybean grains and experiments were carried out, applying the periodic and conventional operations with the same drying time and energy consumption. Results indicated with 5% of significance that the experiments conducted with entrance air temperature modulation achieved higher levels of the percentage of evaporated water improving the dryer performance. These results were in agreement with predicted data obtained with heterogeneous models and they indicated that the periodic drying operation can demand less energy to achieve a specific safe level of soybean moisture content for storage.

Hot‐Air Drying Characteristics of Soybeans and Influence of Temperature and Velocity on Kinetic Parameters

AbstractThe kinetics of the hot‐air drying of soybeans was modeled in order to evaluate the influence of temperature and velocity on the kinetic parameters. A convective dryer with air temperature from 30 to 195C and air flows of 0.75, 1.35, 2.0 and 2.5 m/s was used. Three different mathematical models were applied to simulate the drying process (two empirical equations, exponential and Page's, and Fick's diffusion model) and the diffusivity coefficient increased from 2.5 × 10−11 to 6.69 × 10−10 m2/s for a range of air temperature between 30 and 195C. Both temperature and velocity influenced drying rate. The differential evolution optimization method was used toward parameter estimation. The goodness of fit of the proposed models, evaluated using linear regression coefficient (R2), chi‐squared parameter (χ2) and root mean square error, indicated a satisfactory validation, mainly regarding to the exponential and Page's models.Practical ApplicationsAlthough biological materials are dried to improve shelf life, reduce packaging costs and enhance sensorial aspects, they are highly susceptible to quality deterioration during dehydration if the processing parameters are not well adjusted. The mathematical modeling of food drying provides results about the influence of process parameters on energy efficiency and final product quality in order to help the optimization and upscale application. Given that up to 40% of the agro‐industrial production is lost in developing countries due to the lack of processing and that an energy efficiency improvement of 1% may result in 10% increase in profit, it is important to explore the potential of mathematical tools to properly study drying processes under an energy and qualitative approach.

Effect of Convective Air Attributes with Microwave Drying of Soybean: Model Prediction and Experimental Validation

The heat and mass transfer that occurred during drying of soybeans by a combined process using microwave (MW) and convective hot air was studied. A coupled mathematical model was developed to simulate this phenomenon. The soybean samples were re-wetted to 20% wet basis, the selected level of initial moisture content (IMC), and then dried in a domestic microwave oven under various MW power levels from 300 to 390 W, using inlet air with relative humidity of 35, 55, 75, and 95%. The simulated moisture loss profiles obtained from the coupled model compared well with those obtained in the experiments. Results showed that the drying rate decreased from 6.235 × 10−5 to 6.192 × 10−5 kg water/(kg wb s) as the inlet air temperature increased from 30 to 60°C. Furthermore, the drying rate was observed to increase from 6.192 × 10−5 to 6.211 × 10−5 kg water/(kg wb s) as the relative humidity (RH) increased from 35 to 95%.

Simulation of energetic- and exergetic performance of microwave-assisted fluidized bed drying of soybeans

The performance of microwave-assisted fluidized bed drying of soybeans was simulated (using a previously validated mathematical model) and analyzed based on the first- and second law of thermodynamics. The energy and exergy analysis were carried out for several drying conditions. The effects of inlet air temperature, microwave power density, bed thickness and inlet air velocity on the efficiencies and inefficiencies of drying process have been simulated and discussed. Generally, application of microwave energy during fluidized bed drying enhanced the exergy efficiency of drying process. However, the results showed that it was more efficient not to apply microwave energy at the first stage of fluidized bed drying process. The application of higher levels of drying air temperature led in higher exergy efficiencies. The values of mean relative deviations for the predictions of efficiencies and inefficiencies of drying process were less than 14%, compared with those calculated using experimental data.

CFD Modeling of Microwave-Assisted Fluidized Bed Drying of Moist Particles Using Two-Fluid Model

The drying behavior of moist spherical particles in a microwave-assisted fluidized bed dryer was simulated. The two-fluid Eulerian model incorporating the kinetic theory of granular flow was applied to simulate the gas–solid flow. The simulations were carried out using the commercial computational fluid dynamics (CFD) package Fluent 6.3.26. The effects of different levels of microwave power densities as well as initial gas temperature on the prediction of solids moisture content, gas temperature, and gas absolute humidity were investigated. The effect of microwaves was incorporated into calculations using a concatenated user-defined function (UDF). The simulation results were compared with experimental data obtained from drying of soybeans in a pilot-scale microwave-assisted fluidized bed dryer and reasonable agreement was found. The mean relative deviation for prediction of solids moisture content, gas temperature, and gas absolute humidity were less than 3, 10, and 5%, respectively. Further work is needed to validate the proposed model for large-scale plants.

Simulation and Validation of Microwave-Assisted Fluidized Bed Drying of Soybeans

A general mathematical model of heat and mass transfer was developed to simulate the microwave-assisted fluidized bed drying of bulk grain. The model was solved using the well-known Runge-Kutta-Gill method. The model is capable of predicting the moisture content of soybean as well as the drying air parameters (i.e., drying air temperature and moisture content) during drying. The values of mean relative deviation (MRD) were less than 8 and 10% for prediction of grain moisture content and outlet air parameters, respectively, which reflects an acceptable accuracy. In comparison with conventional fluidized bed drying of soybean, microwave-assisted fluidized bed drying led to 83.39–98.07% savings in drying time and 82.07–95.22% savings in specific energy consumption when reducing soybean moisture content from 18.32 to 12% (db).

Kinetic modelling of drying and conversion/degradation of isoflavones during infrared drying of soybean

Abstract Soy isoflavones, which are well-known for their health benefits, could be affected by the technique and condition that are used to dry soybean prior to its use. In this study the drying kinetics of soybean as well as the inter-conversion and degradation of soy isoflavones during gas-fired infrared combined with hot air vibrating drying (GFIR–HAVD) at various temperatures (50, 70, 130 and 150 °C) were investigated. Simple kinetic models for the evolutions of both moisture content and isoflavones were proposed and tested. The temperature dependency of the effective moisture diffusivity of soybean could be well described by the Arrhenius correlation with the activation energy of 13.88 kJ/mol. In terms of the evolutions of isoflavones the contents of 6″- O -malonylgenistin (MGI) and 6″- O -acetylgenistin (AGI) decreased, while genistin (GI) and genistein increased with an increase in the drying temperature and drying time. First-order kinetic models could be used to describe the changes of isoflavones. At all drying temperatures the conversion of MGI to GI exhibited the highest rate constant; this was followed by the conversion of AGI to GI. In addition, MGI had the highest degradation rate constant; this was followed, in descending order, by AGI, GI and GE. The activation energies of degradation were lower than those of inter-conversion among all forms of isoflavones.

Soybean Drying and Processing Techniques Using Recirculating Batch Dryer

Soybean Drying and Processing Techniques Using Recirculating Batch Dryer

A Study of Drying of Soybean (III)

A Study of Drying of Soybean (III)

On Brack Soybean Drying With De-fumidifier and Vinyl-house

On Brack Soybean Drying With De-fumidifier and Vinyl-house

Comparison of Microwave Drying of Soybean in Static and Rotary Conditions

A rotary device was built in a home microwave oven, where wet soybean was dried in a dynamic moving state to improve the microwave drying uniformity. Experiments were conducted to investigate the relative water removal ratio which was defined to characterize the electromagnetic field distribution in microwave oven, and to compare the drying characteristics between static and rotary microwave drying. It is concluded that the kernel cracking ratio is lower when microwave drying of soybean was carried out in rotary state. Higher unit microwave power input results in rapid removal of water from soybean but an increase of kernel cracking ratio.

Soybean drying characteristics in microwave rotary dryer with forced convection

A new hybrid drying technique by combining microwave and forced convection drying within a rotary drum, i.e., microwave rotary drying, was developed with the purpose to improve the uniformity of microwave drying. In a laboratory microwave rotary dryer, rewetted soybean was utilized as experimental material to study the effects of drum rotating speed, ventilation flow rate, and specific microwave power on the drying kinetics and cracking ratio of soybean. It was found that, with rotation, the cracking ratio can be lowered but without distinct improvement in the drying rate. Increasing ventilation flow rate and specific microwave power can improve the drying rate, but the cracking ratio also increases as a negative result. The cracking ratio lower than 10% can be attained for ventilation flow rate lower than 2.0 m3·h−1 or specific microwave energy lower than 0.4 kW·kg−1 in the present experiments.

Modeling and Energetic Analysis of Soybean Meal Drying in the Indirect Rotary Dryer

The process of soybean meal industrial drying requires a high consumption of energy, and it is usually performed in an indirect rotary dryer. A study aiming for the reduction of this energy consumption is vital for the competitiveness of this product. Thus, the purpose of this work was to develop a mathematical model of soybean meal drying, in permanent regime, in order to assess the optimal operational conditions of the dryer and its energetic performance. The developed model is based on balances of mass and energy, and using constitutive and empirical equations. The model validation was carried out through operational data. From this, the influences of the initial temperature, initial moisture, and relative humidity of air, as well as the dryer energetic performance, were investigated.

Stationary drying of soybean seed using drying air of different relative humidities

Stationary drying of soybean seed using drying air of different relative humidities

Drying and Urease Inactivation Models of Soybean Using Two-dimensional Spouted Bed Technique

The most important factors for examining the quality of soybeans in the animal feed industry are moisture and urease inactivation. Mathematical models for soybean drying and urease inactivation using two-dimensional spouted bed are developed and validated with experimental data. The influences of initial moisture content, inlet air temperature, air recycle on the drying rate, urease inactivation, and energy consumption are also studied. The results revealed that the increase in initial moisture content slightly affected the drying rate and urease inactivation while the inlet air temperature caused a significant effect. To obtain a high drying rate and save energy consumption, the recycle air ratio should be kept in a range of 80–90%.

Análise energética da secagem de farelo de soja em secador rotativo indireto

The soybean meal is an important product of the Brazilian agribusiness. Soybean meal drying, one of the stages of the production, is a great consumer of energy and, normally, it is conducted in a rotary dryer of indirect heating. The study of the soybean meal drying aims to reduce its consumption of energy and it is important to increase market competition of this product. Thus, the objective of this work was to develop a mathematical model, in stationary regimen, in order to evaluate the energy consumption and the efficiency of the process. The model was based on the mass and energy balances, constitutive and empirical equations. The validation of the model was made from operational data of an indirect rotary dryer of Coamo (Cooperativa Agricola Mouraoense)

The use of the orthogonal collocation method on the study of the drying kinetics of soybean seeds

The purpose of this paper is to present numerical solutions of a diffusion model by the orthogonal collocation method applied to soybean seeds when drying, when the effective diffusivity is moisture content dependent. The model used takes into account both internal and external mass transfer resistances. The simulated results were compared with experimental data of soybean drying in a thin layer. The results showed that the convective mass transfer resistance was negligible, for the experimental conditions. That being so, the hypothesis that the moisture at the solid surface instantly attains the equilibrium moisture of the grain is adequate for this case. A functional dependency of the effective diffusivity with the solid's moisture and with temperature was determined in this work.

Soybean Drying by Two-Dimensional Spouted Bed

Urease activity, cracking, and breakage are important factors in considering the quality of raw soybean for feed meal industries. A two-dimensional spouted bed dryer was investigated to determine its capability for thermally inactivating the urease enzyme and maintaining its other qualities. The experimental results have shown that the drying kinetics of soybean in a two-dimensional spouted bed dryer are of the form described in the thin layer drying. The expression for the model parameter in Newton's law of cooling equation accounting for the moisture contents and inlet air temperatures was developed. The initial moisture content and inlet air temperature conditions cause cracks in the kernels. The strong collision between kernels and deflector because of high superficial velocity leads to high percentage of broken soybeans in the spout region. However, the velocity of 15.9 m/s can reduce the breakage below 5%. The inactivation of urease at low-to-moderate moisture content is suitably described by the first order kinetics. The modified Monod equation is applied when the moisture content is higher than 26% dry basis due to the inhibitory effect of water content on the inactivation rate. To complete urease inactivation and maintain protein quality, the temperatures of 150°C should be used.

Study on Ultra-Sonic Drying of Soybean

Study on Ultra-Sonic Drying of Soybean