scholarly journals LNT microwave-multiphase transport model for the microwave drying of lignite thin layer

2018 ◽  
Author(s):  
Bi An Fu ◽  
Meiqian Chen ◽  
Q. H. Li
Keyword(s):  
Thin Layer ◽  
Transport Model ◽  
Power Level ◽  
Microwave Energy ◽  
Moisture Distribution ◽  
Microwave Drying ◽  
Drying Time ◽  
Multiphase Transport ◽  
Mass Transfer Mechanism ◽  
Simulation Results

The LNT microwave-multiphase transport model has been applied to the microwave drying of lignite thin layer. Microwave energy, temperature and moisture distribution were obtained to gain a comprehensive understanding on the heat and mass transfer mechanism of the drying process. The required drying time of experiments decreased by 50, 63, 67, and 83%, respectively, with the power level rising from 119 to 700 W, while that decreased by 60, 72, 76 and 86%, respectively, for simulation results. The temperature values of the corner and edge of the lignite thin layer were higher than that of the center region, which corresponded to the microwave energy distribution. The moisture ratio profiles, temperature profiles and temperature distribution indicated good agreement between the experimental and simulation results, providing confidence in the modeling approach, which made it possible to obtain the moisture distribution successfully via simulation method.Keywords: microwave; lignite; thin layer.  

scholarly journals Effect of Microwave Drying on the Drying Characteristics, Color, Microstructure, and Thermal Properties of Trabzon Persimmon

Foods ◽  
2019 ◽  
Vol 8 (2) ◽  
pp. 84 ◽  
Author(s):  
Soner Çelen
Keyword(s):  
Energy Consumption ◽  
Color Change ◽  
Power Level ◽  
Effective Diffusion ◽  
Microwave Energy ◽  
Microwave Drying ◽  
Slice Thickness ◽  
Fresh Sample ◽  
Drying Time ◽  
Color Changes

In this study, changes in the drying kinetics, color change, and the energy consumption for microwave energy were investigated for Trabzon persimmon. In addition to that, the microstructure of the persimmon was also investigated by considering its thermal changes. It is important to be aware of the purpose of the drying process for determining the drying system. Results of this research showed that 460 W for 7 mm slice thickness depending on energy consumption, 600 W for 5 mm slice thickness depending on drying time, and 600 W depending on color changes were found as suitable drying processes depending on drying conditions. The effective diffusion values varied between 2.97 × 10−8 m2 s−1 and 4.63 × 10−6 m2 s−1. The activation energy values for 5 mm, 7 mm and 9 mm slice thickness were estimated as 32.82, 18.64, and 12.80 W g−1, respectively. The drying time and energy consumption decreased, whereas drying rate increased with an increase in the microwave energy. The number of pores increased compared to structure of fresh sample, and the pores got to be larger for 5 mm slice thickness as the power level increased. Results showed that the applied microwave energy had an important effect on the heating of the material and the change in the microstructure.

Study of color kinetics of banana (Musa cavendish) under microwave drying by application of image analysis

2020 ◽  
pp. 108201322098133
Author(s):  
Sagar Nagvanshi ◽  
Subbarao Kotra Venkata ◽  
TK Goswami
Keyword(s):  
Microwave Power ◽  
Vision System ◽  
Power Level ◽  
Microwave Drying ◽  
Slice Thickness ◽  
Order Kinetic ◽  
Drying Time ◽  
Volumetric Heating ◽  
Kinetics Of ◽  
Microwave Power Level

Microwave drying works on the volumetric heating concept promoted by electromagnetic radiation at 0.915 or 2.450 GHz. In this study, banana ( Musa Cavendish) was taken as the sample and treated under microwave drying. The effect of two process variables, namely slice thickness (2, 3.5, and 5 mm) and microwave power (180 W, 360 W, and 540 W), were studied on drying kinetics and color kinetics. It was observed that the inverse variation relationship exists between drying time and microwave power level while drying time and slice thickness exhibited a direct variation relationship. A Computer Vision System (CVS) was developed to measure the color values of banana in CIELab space using an algorithm written in MATLAB software. Once the color parameters were obtained, they were fitted in First and Zero-order kinetic models. Both models were found to describe the color values adequately. This study concludes that microwave drying is a promising dehydration technique for banana drying that reduces the significant time of drying. Application of CVS is an excellent approach to measure the surface color of banana.

scholarly journals MATHEMATICAL MODELING OF MICROWAVE HEATING OF BALL-SHAPED PRODUCTS

2019 ◽  
Author(s):  
Vadim Karelin ◽  
Vladimir Salomatov
Keyword(s):  
Mathematical Modeling ◽  
Microwave Heating ◽  
High Performance ◽  
Nonlinear Models ◽  
Heating Time ◽  
Microwave Energy ◽  
Moisture Distribution ◽  
Microwave Drying ◽  
Food Industries ◽  
Analytical Approaches

Microwave heating is widely used in the energy, construction, forestry, chemical and food industries, etc. There are many publications that discuss the main mechanisms that occur during microwave heating. For a better understanding of these processes and the development of high-performance microwave installations, mathematical modeling is necessary. As a rule, nonlinear models that most adequately describe these phenomena use a numerical algorithm for calculations. The authors of this report are engaged in approximate analytical approaches for microwave heating and microwave drying of bodies, which, with a controlled decrease in accuracy, nevertheless allow you to display the main processes and evaluate such heating and drying parameters as: temperature and moisture distribution, heating time, drying speed, reaching maximum values, etc. In this work, we consider a model of microwave heating in the form of a ball with uniform irradiation of microwave energy in the conditions of radiation-convective interaction of the product with the environment. The absorption of the microwave inside the material is given by the law of the Bouguer. In this case, a number of simplifications were made: the electrophysical and thermophysical properties of the material are constant, the material is homogeneous in composition and properties.

scholarly journals Influence of intermittent and continuous microwave heating on drying kinetics and wood behavior of Eucalyptus Gomphocephala

2018 ◽  
Author(s):  
Mariam Habouria ◽  
Sahbi Ouertani ◽  
Soufien Azzouz ◽  
Wahbi Jomaa ◽  
Mohamed Taher Elaib ◽  
...  
Keyword(s):  
Power Level ◽  
Drying Kinetics ◽  
Microwave Drying ◽  
Continuous Heating ◽  
Average Moisture Content ◽  
Processing Parameter ◽  
Drying Time ◽  
Optimal Processing ◽  
Eucalyptus Wood ◽  
Eucalyptus Gomphocephala

 The aim of this work was to determine the microwave drying kinetics of Eucalyptus Gomphocephala wood  and to investigate the influence of intermittent and continuous heating  processes on the end quality of dreid samples.  The average moisture content evolution and temperature of wood samples under different microwave powers were analyzed in terms of drying time and internal temperature level. Results show that the increase of microwave power level decreses the drying time and increases the internal wood temperature. Based on qualitative observations on the state of dried samples, the intermittent microwave powers intensity process present the optimal processing parameter in microwave drying of  Eucalyptus wood species.Keywords: microwave drying; power; intermittent; continuous; Eucalyptus wood.  

scholarly journals Determination of Drying Patterns of Radish Slabs under Different Drying Methods Using Hyperspectral Imaging Coupled with Multivariate Analysis

Foods ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 484 ◽  
Author(s):  
Dongyoung Lee ◽  
Santosh Lohumi ◽  
Byoung-Kwan Cho ◽  
Seung Hyun Lee ◽  
Hyunmo Jung
Keyword(s):  
Moisture Content ◽  
Hyperspectral Image ◽  
Partial Least Square ◽  
Least Square ◽  
Moisture Distribution ◽  
Microwave Drying ◽  
Drying Methods ◽  
Drying Method ◽  
Drying Time ◽  
Hot Air

Drying kinetics and the moisture distribution map of radish slabs under different drying methods (hot-air drying (HAD), microwave drying (MD), and hot-air and microwave combination drying (HMCD)) were determined and visualized by hyperspectral image (HSI) processing coupled with a partial least square regression (PLSR)-variable importance in projection (VIP) model, respectively. Page model was the most suitable in describing the experimental moisture loss data of radish slabs regardless of the drying method. Dielectric properties (DP, ε ) of radish slices decreased with the decrease in moisture content (MC) during MD, and the penetration depth of microwaves in radish was between 0.81 and 1.15 cm. The PLSR-VIP model developed with 38 optimal variables could result in the high prediction accuracies for both the calibration ( R c a l 2 = 0.967 and RMSEC = 4.32 % ) and validation ( R v a l 2 = 0.962 and RMSEC = 4.45 % ). In visualized drying patterns, the radish slabs dried by HAD had a higher moisture content at the center than at the edges; however, the samples dried by MD contained higher moisture content at the edges. The nearly uniform drying pattern of radish slabs under HMCD was observed in hyperspectral images. Drying uniformity of radish slabs could be improved by the combination drying method, which significantly reduces drying time.

Modeling of Thin Layer Drying of Banana (Nendran Spp) under Microwave, Convective and Combined Microwave-Convective Processes

2011 ◽  
Vol 6 (1) ◽  
Author(s):  
Magesh Ganesapillai ◽  
I. Regupathi ◽  
Thanapalan Murugesan
Keyword(s):  
Thin Layer ◽  
Microwave Drying ◽  
Convective Drying ◽  
Mean Bias Error ◽  
Bias Error ◽  
Slice Thickness ◽  
Drying Process ◽  
Chi Square ◽  
Drying Time ◽  
Thin Layer Drying

Drying kinetics of microwave, convective and microwave assisted convective drying of thin layer Nendran banana was investigated on a modified microwave oven. The drying characteristics through the operating parameters of the drying process, such as power output, air temperature, slice thickness and sample mass in terms of drying rate equation, were analyzed. An appropriate empirical model to represent the drying process was established by analyzing the available literature models with current experimental data. The statistical analysis for the selected model was performed, parameters like Mean Bias Error, Root Mean Square Error, reduced chi square and t-stat were estimated to examine the consistency of the model to represent the present experimental results. Higher rates and shorter drying times were achieved at a higher temperature and microwave heating power and lesser sample thickness and load. Microwave drying resulted in a substantial decrease in the drying time with better quality product when dried at higher power (300 W) level compared to other processes.

scholarly journals Modelling the kinetics of microwave drying of shallot (Allium cepa) slices

2021 ◽  
Vol 1195 (1) ◽  
pp. 012033
Author(s):  
C L Hii ◽  
C Govind ◽  
C L Chiang ◽  
D Mohammad
Keyword(s):  
Thin Layer ◽  
Allium Cepa ◽  
Microwave Power ◽  
Drying Kinetics ◽  
Microwave Drying ◽  
Convective Drying ◽  
Drying Methods ◽  
Drying Time ◽  
Thin Layer Drying ◽  
Drying Rates

Abstract Convective drying is typically used to dry shallot (Allium cepa) commercially. However, a long drying time with a relatively low efficiency has led to the pursuit of new and improved drying methods. Microwave drying was chosen to be used due to its numerous advantages such as improved drying time, high drying efficiency and better product quality. In this research, three microwave power (180 W, 300 W, 450 W) and convective drying at 100°C were used. Results showed that drying kinetics (moisture content and drying rates) decreased the fastest at higher microwave power and the slowest using convective drying. In order to determine the best model to describe the thin-layer drying kinetics, four semi-empirical models were used namely Newton, Page, Logarithmic and Two-term models. Page model was found to be the best in describing the thin-layer microwave drying kinetics. Effective diffusivity values increased with higher microwave power and were found to be in the range of 6.62 × 10−6 m2/s to 3.69 × 10−5 m2/s with convective drying being the lowest (6.62 × 10−6 m2/s) and 450W being the highest (3.69 × 10−5 m2/s). Microwave drying is therefore able to improve drying kinetics compared to convective drying.

Microwave Drying Characteristics and Antidiabetic Properties of Aquilaria subintegra and Aquilaria malaccensis Leaves

2015 ◽  
Vol 1113 ◽  
pp. 352-357 ◽  
Author(s):  
Sxureha Yunus ◽  
Nurul Asyikin Md Zaki ◽  
Ku Halim Ku Hamid
Keyword(s):  
Power Level ◽  
Microwave Treatment ◽  
Microwave Drying ◽  
Drying Time ◽  
Drying Characteristics ◽  
Aquilaria Malaccensis ◽  
Treatment Of Diabetes ◽  
Drying Curves ◽  
Vitro Analysis

The present study was aimed to investigate the effect of microwave drying on the anti-diabetic potential of the leaves of Aquilaria subintegra and Aquilaria malaccensis with regard to its efficacy by local herbalists in the treatment of diabetes frailties. The drying process was carried out at 50, 100 and 150 W, and the drying curves were developed to analyse the drying characteristics of both species of Aquilaria leaves. Solid-liquid extraction was done by using ethanol as solvent prior to in-vitro analysis of the inhibition activity on α-amylase. Following that, HPLC and FTIR were done to support findings on the antidiabetic compounds of the leaves extract. The results indicated that an increase in power level will reduce the drying time during microwave treatment. Findings showed that both species of Aquilaria leaves extract could remarkably inhibit the activity of α-amylase and provide a rationale for the use of the leaves in the treatment of diabetes mellitus.

scholarly journals A study about signal variation with minor receiver displacement in a meeting room at 60 GHz: measurements and simulations

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Muhammad Usman Sheikh ◽  
Kalle Ruttik ◽  
Riku Jäntti ◽  
Jyri Hämäläinen
Keyword(s):  
Power Level ◽  
Three Dimensional ◽  
60 Ghz ◽  
System Configuration ◽  
Conference Room ◽  
Channel Characteristics ◽  
Received Power ◽  
Simulation Results ◽  
Small Change ◽  
The Impact

AbstractThe aim of this work is to study the impact of small receiver displacement on a signal propagation in a typical conference room environment at a millimeter wave frequency of 60 GHz. While channel measurements provide insights on the propagation phenomena, their use for the wireless system performance evaluation is challenging. Whereas, carefully executed three-dimensional ray tracing (RT) simulations represent a more flexible option. Nevertheless, a careful validation of simulation methodology is needed. The first target of this article is to highlight the benefits of an in-house built three-dimensional RT tool at 60 GHz and shows the effectiveness of simulations in predicting different characteristics of the channel. To validate the simulation results against the measurements, two different transmitter (Tx) positions and antenna types along with ten receiver (Rx) positions are considered in a typical conference room. In first system configuration, an omnidirectional antenna is placed in the middle of the table, while in the second system configuration a directed horn antenna is located in the corner of the meeting room. After validating the simulation results with the measurement data, in the second part of this work, the impact of a small change, i.e., 20 cm in the receiver position, is studied. To characterize the impact, we apply as performance indicators the received power level, root mean square delay spread (RMS-DS) and RMS angular spread (RMS-AS) in azimuth plane. The channel characteristics are considered with respect to the direct orientation (DO), i.e., the Rx antenna is directed toward the strongest incoming path. Different antenna configurations at the Tx and Rx side are applied to highlight the role of antenna properties on the considered channel characteristics. Especially, in the second system configuration the impact of different antenna half power beamwidth on different considered channel characteristics is highlighted through acquired simulation results. The validation of results shows the RMS error of only 2–3 dB between the measured and simulated received power levels for different Tx configurations in the direction of DO. Results indicate that only a small change of the Rx position may result a large difference in the received power level even in the presence of line-of-sight between the Tx and Rx. It is found that the STD of received power level across the room increases with the decrease in HPBW of the antenna. As can be expected, directed antennas offer lower value of RMS-DS and RMS-AS compared with isotropic antenna.

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