Drying Characteristics Research Articles

Wear and Corrosion Properties of Pure Mo Coating Layer Manufactured by Atmospheric Plasma Spray Process

A pure molybdenum (Mo) coating layer was manufactured by using the atmospheric plasma spray (APS) process and its wear and corrosion characteristics were investigated in this study. A Mo coating layer was prepared to a thickness of approximately 480 μm, and it had sound physical properties with a porosity of 2.9% and hardness of 434 Hv. Room temperature dry wear characteristics were measured through a ball-on-disk test under load conditions of 5 N, 10 N and 15 N. Based on the coefficient of friction graph at 5 N and 10 N, the oxides formed during wear functioned as a wear lubricant, thereby confirming an increase in wear resistance. However, at 15 N, wear behavior changed, and wear occurred due to splat pulling out. A potentiodynamic polarization test was conducted under an artificial seawater atmosphere, and Ecorr and Icorr measured 0.717 V and 7.2E-5 A/cm2, respectively. Corrosion mainly occurred at the splat boundary and pores that were present in the initial state. Based on the findings above, the potential application of APS Mo coating material was also discussed.

Effect of Ultrasound-Assisted Vacuum Far-Infrared on the Drying Characteristics and Qualities Attributes of Cistanche Slices

This study applied direct-contact ultrasound-assisted Vacuum Far-Infrared (VFIR) to dry Cistanche slices, investigating the influence of radiation temperature (45 °C, 55 °C, 65 °C), ultrasonic frequency (20 kHz, 40 kHz, 60 kHz) and ultrasonic power (72 W, 96 W, 120 W) on the physicochemical properties, drying characteristics, and microstructure of Cistanche slices. The results showed that the application of ultrasound had a significant enhancement effect on the drying process, with drying time decreasing as radiation temperature, ultrasonic power, and ultrasonic frequency increased. The drying rate curves under three experimental factors exhibited a brief acceleration stage followed by a deceleration stage. Under different drying conditions, the contents of Iridoid and phenylethanoid glycosides in dried products were higher than those under natural drying (ND). Specifically, the content of catalpol at 55 °C, 96 W, 40 kHz (0.56 mg/g) and the content of Leonuride at 55 °C, 96 W, 60 kHz (0.67 mg/g) increased by 1.81 and 1.9 times, compared to ND. The rest of the nutrient content and antioxidant activity increased with the increase in ultrasonic frequency. Compared to ND, ultrasonic-assisted VFIR drying improved the color and rehydration capacity of dried products. Observation of the microstructure revealed that the application of ultrasound made the interior of Cistanche slices loose and porous. In summary, ultrasonic-assisted VFIR drying not only enhances the drying rate but also improves the quality of dried products.

Effect of solar radiation and full spectrum artificial sun light drying on the drying characteristics, ultra-structural and textural properties of white radish (Raphanus sativus L.)

Traditional sun drying has long been employed as a method for preserving radishes (Raphanus sativus L.) However, it suffers from various uncertainties, including weather-related factors such as rain and cloudy days, the pressing issue of climatic change can lead to an impact on the traditional drying process and texture of radish. In this research, the full spectrum artificial sunlight drying (FSASLD) has been implemented to simulate the traditional open sun drying of white radish slices which helps to prevent hygienic issues and unstable climatic conditions. Water activity (Aw) was measured and observed to decrease from 0.89 to 0.60 under both drying methods, indicating the removal of moisture from radish cells. Mathematical modelling and color kinetics models were studied with respect to drying time. Texture Profile Analysis (TPA) was employed to assess hardness, and results showed an increase in hardness following both SD (1018.24 g to 1327.67 g) and FSASLD (1018.24 g to 1731.04 g) salt treated radish slices. These findings suggest that FSASLD can serve as a viable alternative to the conventional drying method and contributes to agricultural innovation and the food industry, reducing drying time significantly from 270 min to 200 min and minimizing the impact of adverse weather conditions and interference from animals and microorganisms.

Drying characteristics of sewage sludge pre-conditioned by CaO and sawdust under low-temperature drying conditions

ABSTRACT Heat pump drying is a low-carbon method of sludge drying. The operating temperature of a heat pump is generally not more than 70℃. To improve the drying efficiency of heat pump dryers, the effects of air parameters and additives on sludge drying characteristics at low temperatures were studied. The sludge drying experiments were conducted at an air temperature 50-70℃ and an air velocity of 0.5-1.7 m/s. The experimental results showed that the increase of air temperature, velocity and the addition ratio of additives can accelerate the sludge drying process. The average and maximum drying rates of sludge pre-conditioned by CaO and sawdust increased by 14.23% and 25.71%, respectively, compared with those of pure sludge. The two-way analysis of variance (ANOVA) revealed that the influence of air temperature on the sludge drying was higher than that of air velocity. Five reference models were fitted by the drying experiment data. The Page model has the highest R2, so it is the most suitable model to predict the drying time of sludge at low temperatures.

Drying characteristics of eggplant drying in a heat pump dryer

Drying characteristics of eggplant drying in a heat pump dryer

Experiment, CFD simulation and field synergy characteristics analysis of hot-air drying process in a spouted bed

Combining experimental and simulation methods, the hot-air drying process in the spouted bed was studied from the perspective of heat and mass transfer and multiphase physical field synergy. Based on the experimental system, the rate of drying curve was determined, and a drying prediction model was established and verified. The analysis of the drying characteristics shows that the heat and mass transfer in the spouted bed mainly occurred in the center of the spouting and fountain region, followed by the annulus region, and finally on both sides of the fountain region. The dimensionless parameter σ that simultaneously considered the synergy angle of velocity-velocity gradient and velocity-pressure gradient indicated that the gas drag was mainly concentrated near the gas inlet. The synergy coefficient SC of the velocity-temperature-concentration field was more affected by the variation coefficient of the velocity-concentration field and less affected by the variation coefficient of the velocity-temperature field.

Characteristics of Dry and Wet Changes and Future Trends in the Tarim River Basin Based on the Standardized Precipitation Evapotranspiration Index

Global changes in drought and wetness and their future trends in arid regions have recently become a major focus of research attention. The Tarim River Basin (TRB) in Xinjiang, China, is among the most climate-sensitive regions in the world. This study uses data from the past 60 years (1962–2021) to analyze the spatial and temporal features of drought and wetness conditions in the TRB, calculating the Standardized Precipitation Evapotranspiration Index (SPEI). Trend detection for SPEI is performed using the BEAST mutation test, identification of drought events using the theory of operations, and spatial and temporal analyses of dry and wet changes using Empirical Orthogonal Function (EOF) decomposition. Additionally, the CMIP6 dataset is used to estimate future changes. The study results indicate the following: (1) From 1962 to 1998, the TRB exhibited a “warm and wet” trend that suddenly shifted from “wet-to-dry” in 1998 and subsequently transitioned to a pronounced “warm and dry” trend. (2) After the “wet-to-dry” shift, the frequency of drought events noticeably increased. The northern section of the basin witnessed more frequent drought events, albeit with lower severity, while the southern part had fewer occurrences but with higher severity. The spatial distribution of drought event frequency and severity is inconsistent. (3) The EOF decomposition results for SPEI-variable fields at 1-, 3-, and 6-month time scales show that the cumulative variance contribution rate of the first three principal spatial modal feature vectors exceeds 70%. The spatial distribution of the modes includes a consistent pattern across the entire basin, a north–south opposite pattern, and an east–west opposite pattern. (4) The future trend of drought in the TRB is expected to intensify, manifesting a spatial pattern characterized by dryness in the middle of the basin and wetness around the periphery. These research findings can provide support for decisions addressing regional drought risks.

Performance Evaluation of Indirect Solar Dryer under Passive and Active Modes during Drying Beetroot Slices

In the present work, the drying characteristics of beetroot slabs, thermal and performance characteristics were estimated and analyzed in passive (mode-A) and active (mode-B) indirect solar dryers (ISD). The conventional mode-A dryer was updated with a diverging duct that comprises direct current fans run by photo-voltaic panels to make the mode-B dryer. In mode-B, the drying time of 16.67 and 42.31% is saved compared to mode-A and open sun drying (OSD), respectively, to achieve a final moisture content of 0.057 from 7.7535 kg/kg of dry basis. The Two-term exponential model was observed to be a perfect fit model for beetroot slices in both modes of ISD and OSD, respectively. The improvements in drying rate, dryer and collector efficiencies and specific moisture extraction rate in mode-B over mode-A are found to be 19.97, 19.18, 8.34 and 14.23%, respectively. It is found that mode-B has better thermal and performance properties than mode-A.

Influence of ultrasonic pretreatment on drying and thermodynamic characteristics of Asian seabass fish skin during air-frying process

Influence of ultrasonic pretreatment on drying and thermodynamic characteristics of Asian seabass fish skin during air-frying process

Convective Drying of the Zucchini Slices; Impact of Pretreatments on the Drying Characteristics and Color Properties, Evaluation of Artificial Neural Network Modeling and Thin-Layer Modeling

This study focused on the impact of citric acid, hot water blanching, and ultrasound pretreatment on the drying of zucchini slices, color properties, and the comparison of artificial neural network (ANN) and thin-layer modeling. The pretreatments enhanced the drying rate and reduced drying time. Ultrasound pretreatment was observed as the most effective, with a reduction rate of the drying time as 40%. Besides, mass transfer and moisture diffusion phenomena were positively affected by pretreatments, depending on the increment of the drying rate. The highest mass transfer coefficient (hm), moisture diffusivity (D) by the Dincer and Dost model, and effective moisture diffusivity (Deff) by the Crank equation were obtained with ultrasound pretreatment. On the other hand, Midilli and Kucuk, Parabolic, and Page gave the best predictions among the thin-layer models. However, ANN modeling had a better performance than thin-layer modeling due to a higher determination coefficient (R2) and lower root mean square error (RMSE) values. Color properties of the zucchini slices were affected by drying processes. In general, the redness and yellowness of the zucchini slices increased; however, lightness did not show statistical significance. Additionally, citric acid pretreatment gave the lowest total color difference (∆E).

Drying kinetics and mass transfer parameters of mung beans dried using a convective dryer

Convective drying of mung bean seeds was conducted to investigate drying kinetics and mass transfer parameters at temperatures of 40, 50, 60, 70, and 80°C and a fixed air velocity of 1.2 m s-1. Drying characteristics were determined by drying rate, moisture ratio, diffusion coefficient, activation energy, Biot number, and mass transfer coefficient. Drying models such as Newton, Page, Henderson and Pabis, Logarithmic, Midilli, Two-term, and Diffusion approximation were applied and fitted to the moisture ratio of the experimental data. The drying rate was significantly affected by the drying temperature. The Midilli model was considered the most suitable for experimental drying curves. The effective moisture diffusivity ranged from 3.19×10-9 to 10.76×10-9 m2 s-1, with an activation energy of 59.78 kJ mol-1. Similar to the mass transfer coefficient, the Biot number increased with increasing drying temperature. The simultaneous transfer of heat and mass was controlled by diffusion and surface.

Cu–Ethanolamine Nanozymes Promote Urushiol Oxidation of Lacquer

In order to control the production cost of lacquer products, Cu–ethanolamine nanozymes were synthesized to simulate laccase to catalyze the oxidation and polymerization of urushiol. First-principles calculation results indicate that the D-band center of Cu center in the nanozymes was closer to the Fermi level than that of laccase, so Cu–ethanolamine was more conducive to the adsorption of substrate. The activation energy of Cu-ethanolamine catalyzed the oxidation of urushiol was significantly lower than that of laccase. Therefore, we inferred that the synthesized Cu–ethanolamine had a better catalytic effect on urushiol and was more conducive to paint film drying. By comprehensive comparison, the drying characteristics of the Cu–ethanolamine and raw lacquer with a 1:20 ratio are found to be closest to those of the raw lacquer, and the drying time is significantly shortened. The reaction results of the drying process performance test on the sample indicate that the composite lacquer can achieve the market-desired effect and performance requirements of the paint process.

Evaluation of Low-Pressure Cold Plasma Effect on Phytonutrients, Drying and Microstructural Characteristics, and Changes in Microbial Load of Fresh and Hot-Air-Dried ‘Heidi’ Mango

AbstractAlternative pre-treatment strategies before drying offer the prospect to minimize drying time, replacing the use of chemicals, and preserving quality of dried fresh products. This study explored the application of low-pressure atmospheric cold plasma (CP) for 5- and 10 min (CP5 and CP10) as pre-treatments prior to processing and hot air drying (60 °C) of ‘Heidi’ mango, while non-treated samples served as control. Changes in tissue microstructure and physicochemical properties, bioactive compounds, and microbial load were evaluated, and seven thin layer drying models were applied. Scanned electron microscope images showed that CP pre-treatments altered the tissue microstructure of dried mango slices compared to control. ‘Heidi’ mango slices with the initial moisture content of 80 ± 0.2% on a wet basis was reduced by 81% and 76% in dried CP5 and CP10 samples, respectively. Drying time was reduced by 20% for CP pre-treated samples in comparison to control samples, and the drying behavior of ‘Heidi’ mango slices was best described by the Logarithmic model (R2, 0.9999 and RMSE, 0.0122). Colour attributes were best retained by sodium metabisulphite (SMB) pre-treated samples, followed by CP5 pre-treated, which performed better than CP10 and control (p ≤ 0.05). Highest total flavanols (15.0 ± 0.4 mg CE 100 g−1) and higher total phenolics (1528.2 ± 23.6 mg GA 100 g−1) were found in CP5 pre-treated samples compared to the control (p ≤ 0.05). Lowest antioxidant activities were found in CP10 pre-treated samples compared to the control (p ≤ 0.05). CP-pretreatment and drying resulted in ≥ 2 Log reduction in microbial load on mango slices. These results demonstrate to the role players in mango value addition chain, the potential of low-pressure CP pretreatment in enhancing/maintaining the bioactive compounds, reducing drying time and microbial load.

Mathematical Modeling of Energy Consumption and Mass Transfer for Drying of Phimai Mee by Hot Air

The purpose of this research was to study a drying process that can help conserve Phimai Mee (Korat’s stir-fried noodles) over a long preservation period. In the drying process tests of Phimai Mee, Air flow rates of 1.5, 2.0 and 2.5 m/s at temperature of 40°C, 50°C, and 60°C were applied. In the assessment of the drying process of Phimai Mee. Five distinct mathematical models in a computational setting. the drying characteristics of Phimai Mee, parameters from an mathematical models were used a computational setting. The drying characteristics of Phimai Mee were comprehensively analysed. Empirical formulae parameters were included in the nonlinear regression analysis of collected moisture ratio data. In evaluating the models for their predictive accuracy in the drying kinetics of Phimai Mee, the Demir et al. model was identified as the most precise. Additionally, The moisture diffusion in the Phimai Mee when tested according to Fick’s law, varied between 0.03499 and 0.11816 m2/s.The results also showed that the drying process’s moisture diffusion is temperature-dependent, which the Arrhenius equation, showing an activation energy range from 7.46 to 8.82 kJ/mol in all the conditions examined.

Effect of Different Pretreatment Methods on Drying Characteristics and Quality of Wolfberry (Lycium barbarum) by Radio Frequency-Hot Air Combined Segmented Drying

Effect of Different Pretreatment Methods on Drying Characteristics and Quality of Wolfberry (Lycium barbarum) by Radio Frequency-Hot Air Combined Segmented Drying

Water Supply via Pedicel Reduces Postharvest Pericarp Browning of Litchi (Litchi chinensis) Fruit.

Pericarp browning is the key factor for the extension of shelf life and the maintenance of the commercial value of harvested litchi fruit. Water loss is considered a leading factor of pericarp browning in litchi fruit. In this study, based on the distinct structure of litchi fruit, which is a special type of dry fruit with the aril as the edible part, the effects of water supply via pedicel (WSP) treatment on pericarp browning and the fruit quality of litchi were investigated. Compared with the packaging of the control fruit at 25 °C or 4 °C, the WSP treatment was found to significantly reduce pericarp browning and the decay of litchi fruit. The WSP-treated fruit had a higher L* value, total anthocyanin content, and pericarp water content, and the pericarp was thicker. The WSP treatment significantly suppressed the increase in the electrolyte leakage of the pericarp and maintained higher ascorbic acid (AA) contents in the aril. In addition, the WSP treatment was effective in reducing the activity and gene expression of browning-related genes Laccase (ADE/LAC) and Peroxidase (POD) during the storage period. In conclusion, the WSP treatment could be an effective method to delay pericarp browning and maintain the quality of harvested litchi fruit, and this further supports that litchi fruit has dry fruit characteristics.

Deep‐bed drying kinetics and thermodynamic parameters of high‐moisture parboiled paddy (ASD‐16) in a reversible airflow fixed bed dryer

AbstractReversible airflow fixed bed dryer (RAFBD) is an energy‐efficient, cost‐effective, and dependable dryer for using renewable energy sources in parboiling mills. In this study, a medium‐sized and high‐moisture parboiled paddy, ASD‐16, was dried in the RAFBD to determine its deep drying characteristics and thermodynamic properties. The chosen paddy variety is a commonly cultivated paddy in the southern region of Tamil Nadu, India. The RAFBD experimental setup was designed to dry 30 kg of parboiled paddy. For the statistical analysis, the experimental data for the deep‐bed drying at hot air temperatures 50–80°C and velocities of 0.1 and 0.15 m/s were used at constant specific humidity. To predict drying characteristics, 12 drying models were compared. Based on their statistical parameters, the Midilli et al. model was selected. For the tested conditions, the coefficients for effective moisture diffusion, heat transfer, and mass transfer were between 9.82 × 10−8 and 2.13 × 10−7 m2/s, 0.3802 and 1.325 W/m2 K, and 0.375 × 10−4 and 1.26 × 10−4 m/s, respectively. Furthermore, the determined activation energy ranged from 20.4964 to 20.4390 kJ/mol.Practical ApplicationsASD‐16 is one of the popular paddy varieties cultivated and used in parboiling mills in the study region. The outcome of this research can contribute to the application of a cost‐effective dryer for drying high‐moisture paddy. Furthermore, the drying time and bed height proposed in this work can reduce the drying time in the mills and improve energy efficiency. The drying kinetics and suitability of the models found in this study will contribute to the design and development of low‐cost dryers for the local parboiling industries. As rice husk, which is a waste from paddy processing, is used for the heating process, industries can reduce the cost of energy for closed‐roof drying. This study provides a clear insight to the researchers and designers in standardizing the capacity of the dryer, drying temperature, and airflow rate for any similar kind of paddy variety.

Hot Air Drying of Brazilian Spinach Leaves

Brazilian spinach is one of the best leafy vegetables with tons of nutrients and has a range of health benefits. Its quality also determines the acceptance of customers to buy and consume it. The common method to extend the shelf life of the spinach is through drying treatment and preserving the color and texture quality of the leaves. Therefore, this study aimed to determine the drying characteristics of Brazilian spinach and investigate the effect of drying temperature on the color and texture quality of Brazilian spinach. Brazilian spinach leaves were dried using a hot air dryer under different temperatures (30, 50, 70 and 90°C). Results showed that the drying rate increased when temperature increased. It was found that the Midili model gave the best fitting to the experimental moisture ratio for a specific drying treatment. Drying the Brazilian spinach leaves at 50°C was the best condition for preserving their color and texture properties.

Drying characteristics and thin layer drying model of semi-mature rice paper

Abstract The effects of different hot air speeds and temperatures on the drying characteristics of half-ripe rice paper were investigated by hot air convection drying experiments. The thin-layer drying experiments were carried out at three different combinations of air speeds of 1.97 m/s, 3.00 m/s, and 3.90 m/s and temperatures of 85 °C, 100 °C and 115 °C. The results show that among the 10 drying kinetic models selected, the Modified Page model is the most suitable model to describe the drying characteristics of the thin layer of half-ripe rice paper; the whole drying process exists obvious ascending, constant and descending processes; the effective moisture diffusion coefficient of half-ripe rice paper is in the range of 1.52656 × 10−9 m2/s–3.15816 × 10−9 m2/s, whose size increases with the increase of the hot wind speed and temperature. Its magnitude increases with the increase of wind speed and temperature; the drying activation energy of half-ripe rice paper is 6.55 kJ/mol calculated by Arrhenius equation.

Kinetic analysis and mathematical modeling of low-rank coal drying by using swirl fluidized bed dryer on varied angles of guide vane and temperatures

ABSTRACT Low-rank coal is currently widely used as fuel to cover the increasing needs of boilers. This kind of coal must be upgraded due to its high moisture content to increase its quality. The drying using a fluidized swirl bed has not been studied to reduce the moisture content of Low-Rank Coal. In contrast, the drying kinetic model has never been found. This study used the angle of guide vanes (AGV) 10°, 20°, and 30° to produce swirl flow. Experiments with varying temperatures used temperatures of 40°C, 45°C, and 50°C. The purpose of this work was to determine the drying characteristics, the best-drying kinetics models, the effective moisture diffusion value, SMER, MER, and SEC on swirl fluidized bed drying. The study results show that the Khazaei and Rational drying kinetic model was the most suitable for the two experimental variations. For experiments with varying AGV, the R2 values obtained are 0.9989–0.9992 and 0.9980–0.9983, while for the variable temperature, the values are 0.9990–0.9992 and 0.9983–0.9992 for each model. The research also found that the smaller AGV angle and higher temperature result in a faster drying rate and consume less energy.