Convective and Microwave Assisted Drying of Wet Porous Materials with Prolate Spheroidal Shape: A Finite-Volume Approach

Silva, Edna G.; Gomez, Ricardo S.; Gomes, Josivanda Palmeira; Figueirêdo, Rossana Maria Feitosa de; Queiroz, A.J.M.; Silva, Wilton Pereira da; Santiago, Ângela Maria; Macedo, Antônio Daniel Buriti de; Ferreira, João P. L.; Gomes, Ítalo A.; Lima, Antônio Gilson Barbosa de

doi:10.3390/agriculture10110507

Cited by 3 publications

(2 citation statements)

References 28 publications

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“…Thus, the spatialtemporal temperature and moisture content are well predicted by these theoretical models. Most of the theoretical models of microwave-assisted drying processes were developed based on the artificial concept of effective moisture diffusivity [5,6,[11][12][13][14][15]. In the diffusion models, the liquid-vapor multiphase flow is treated as a single-phase flow which is named moisture transport and the internal vaporization is omitted.…”

Section: Introductionmentioning

confidence: 99%

Artificial neural network modeling of microwave-assisted heat pump drying process

Nguyen

Tran

2022

IOP Conf. Ser.: Earth Environ. Sci.

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Recently, microwave-assisted drying is an emerging drying technique that can help to accelerate the water removal process. In this paper, a microwave-assisted experimental drying study of carrot slides is presented. A microwave-assisted heat pump dryer is fabricated where the drying agent temperature, the supplied microwave power, and the circulative fan speed are easy to adjust. A series of 61 drying experiments is conducted with a range of drying temperature from 35 °C to 45 °C, a range of microwave power from 0 to 1.25 W/gram, and air velocity varied from 0.55 m/s to 1.70 m/s. The drying kinetics of the dehydration process is analyzed. Based on the obtained result, suitable intensive drying conditions for carrot slices are proposed. To extend the applicability of the experimental study, an artificial neural network (ANN) model of the drying process is developed. Instead of estimating the network for individual drying conditions in previous studies, the network is established for the entire range of drying conditions. The results indicate that the proposed ANN model predicts the microwave-assisted drying process adequately.

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Section: Introductionmentioning

confidence: 99%

Artificial neural network modeling of microwave-assisted heat pump drying process

Nguyen

Tran

2022

IOP Conf. Ser.: Earth Environ. Sci.

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“…Air dehydration is a conventional method to dehydrate wet porous materials. 41 Microwave-air dehydration is highly appreciated as a promising alternative of dehydration technology by providing short dehydration duration and excellent product quality. Microwave and mild air temperature are incorporated to achieve better dehydration effect.…”

Section: Introductionmentioning

confidence: 99%

Possibility of Pulsed Electric Field and Essential Oil Pre-treatment, Microwave-air Dehydration to the Quality of the Dehydrated Sesban (Sesbania sesban) Flower

Minh¹

2021

J. Pure Appl. Microbiol.

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Non-heat ahead-treatment in advance of the main dehydration is essential to preserve the quality and ensure food safety. Pulsed electric field (PEF) utilizes a high-voltage electric field in a very short duration to inhibit microbes and enzymes while maintaining the most sensory and nutritional characteristics. For thermal sensitive components, the dehydration process should be performed at low temperatures. Freeze dehydration, vacuum dehydration required high cost for equipment, energy consumption, low quantity in long dehydration time. Microwave-air dehydration is considered as a promising alternative technical approach. Sesban (Sesbania sesban) flower contains numerous phytochemical components promoting health-benefit. However, it’s highly perishable after harvesting. Consumers enjoy the dried sesban flower as a healthy drink. This study examined the possibility of PEF ahead-treatment in microbial inhibition and enzymatic inactivation; essential oil and Microwave-air dehydration on retention of total phenolic content (TPC), vitamin C, 2,2 diphenyl-1-picrylhydrazyl of free radical scavenging (DPPH), ferric reducing antioxidant power (FRAP) of the dehydrated sesban flower. Research also monitored the microbial stability of the dehydrated sesban flower during 12 months of preservation. Results showed that PEF at pulse strength 1000 kV/cm, pulse duration 90 µs, pulse number 45 was remarkably inactivated polyphenol oxidase and peroxidase in raw material. Rosemary essential oil soaked for sesban flower before dehydration positively preserved the ascorbic acid, phenolic content and antioxidant capacity. These PEF and essential oil ahead-treatments strongly facilitated for the main Microwave-air dehydration. Among different air temperatures from 20°C to 40°C in microwave-air dehydration, the highest Vitamin C, TPC, DPPH and FRAP of the dried flower were recorded at air temperature from 20°C to 30°C with no significant difference. Meanwhile, airspeed 1.2 m/s showed the highest Vitamin C, TPC, DPPH and FRAP of the dried flower with no significant difference with airspeed 1.4 m/s and 1.6 m/s. There was no significant difference in Vitamin C, TPC, DPPH and FRAP of the dried flower by microwave power from 1.15 to 1.45W/g. Therefore, a combination of microwave and air dehydration at air temperature 25°C, airspeed 1.2 m/s, the microwave energy density of 1.45 W/g was recommended to better preserve vitamin C, TPC, DPPH, FRAP. Microbial stability of the dehydrated flower was also observed during 12 months of storage by 3 month-interval sampling. Coliform, yeast and mold criteria in dried product were stable within acceptable limits.

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A Diffusion Model to Describe Water Absorption by Red Rice during Soaking: Variable Mass Diffusivity, Variable Volume, Use of Boundary-Fitted Coordinates

da Silva,

de Lima,

Pereira

et al. 2024

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This article aims to carry out experiments on water absorption by husked red rice at constant temperatures of 28, 40, and 50 °C. The description of the absorption kinetics and the analyses of the water distribution and volumetric expansion of each grain, at a given instant, were carried out using a diffusion model. In order for the model to be as close as possible to the real physical situation, the mesh necessary to numerically solve the diffusion equation was generated from the photograph of a grain. Thus, the diffusion equation was written in Boundary-Fitted Coordinates (BFCs). The solution of the diffusion equation written in generalized coordinates was then discretized in space and time, using the Finite Volume method, with a fully implicit formulation, considering the variable volume and variable mass diffusivity as functions of the local moisture content. Optimizations based on the Levenberg–Marquardt algorithm make it possible to determine the parameters of an exponential function relating mass diffusivity and the local moisture content for each temperature. Statistical indicators (chi-square, determination coefficient, and Student’s t-test) allowed us to conclude that the proposed model was very satisfactory for all temperatures, making it possible to simulate the water absorption, water distribution, and volumetric expansion of the grain over time.

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Convective and Microwave Assisted Drying of Wet Porous Materials with Prolate Spheroidal Shape: A Finite-Volume Approach

Cited by 3 publications

References 28 publications

Artificial neural network modeling of microwave-assisted heat pump drying process

Artificial neural network modeling of microwave-assisted heat pump drying process

Possibility of Pulsed Electric Field and Essential Oil Pre-treatment, Microwave-air Dehydration to the Quality of the Dehydrated Sesban (Sesbania sesban) Flower

A Diffusion Model to Describe Water Absorption by Red Rice during Soaking: Variable Mass Diffusivity, Variable Volume, Use of Boundary-Fitted Coordinates

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