Hot Air Temperature Research Articles

Heat transfer and electromagnetic property investigation on the hot air quartz fiber/PTFE capillary/epoxy resin anti/de‐icing composites

AbstractTo achieve the wave‐transparent and anti/de‐icing requirements of electromagnetic functional structural components on the windward surface of the aircraft, the PTFE capillary hot air tubes were pre‐buried inside the quartz fiber cloth and the hot air anti/de‐icing quartz fiber/PTFE capillary/epoxy resin (QF/PTFE/EP) composite components was prepared to that met the wave‐transparent performance. A multi‐field coupled numerical finite element simulation model was established, and the anti/de‐icing performance of the QF/PTFE/EP composite with different built‐in tube diameters were investigated by combining experiments and simulations under different hot air temperatures and pressures. The feasibility of hot air anti/de‐icing was verified through anti/de‐icing experiments and numerical simulation. The electromagnetic transmittance of the prepared hot air anti/de‐icing QF/PTFE/EP composite components was tested to characterize the effect on the stealth performance of the aircraft under the service environment. The experimental results demonstrated that with 5 mm tube pitch and hot air of 60°C ± 1°C, the surface temperature of the component with three tube diameters could reach more than 10°C. Furthermore, the decrease in the transmittance of the hot air anti/de‐icing QF/PTFE/EP composite components caused by different incidence angles and two polarization modes was less than 3%.Highlights The hot air QF/PTFE/EP anti/de‐icing composite components were fabricated. The heat transfer, anti/de‐icing, and electromagnetic transmittance performance of the hot air QF/PTFE/EP anti/de‐icing QF/PTFE/EP components were investigated. The experimental and simulation results verified the hot air anti/de‐icing QF/PTFE/EP components met the requirement of aircraft anti/de‐icing and wave transmission.

Airflow Characteristics in Conveyor Type Damper for Hot Air Temperature Changes

The aim of this study was to present the characteristics of a hot airflow in a conveyor type dampers under the hot air temperature changes. The amount of space occupied by the damper was reduced by 50 %, and by efficiently managing the damper's airflow rate even in the face of extreme external conditions and constant air volume proportional control, a conveyor-type damper with a significant energy-saving effect has been explored. It was configured to control the degree to which it was opened by operating the folding conveyor drive mechanism, enabling the damper to modify airflow. In this study, the mass flow rate of heated air through the conveyor-type damper increased in proportion to the damper port's expansion. The mass flow rate of air decreased as the temperature of air intensified. In addition, the thermal energy of the air flowing in the conveyor-type damper improved in ratio to the increase in the damper opening. The findings indicate a 50 % reduction in the damper's occupied space, indicating a significant energy-saving impact of the conveyor-type damper. This is because the damper's air volume is effectively controlled even in the face of severe external conditions, as it is proportionately controlled throughout. The understanding of the properties of airflow for the hot temperature change is strengthened by this research. Furthermore, this study may provide useful direction for future research and industry optimization.

Evaluation of the effect of ultrasound-assisted hot air drying on the drying characteristics and physicochemical properties of cherries based on the entropy-weighted TOPSIS method.

To address the challenges associated with prolonged traditional hot air drying (HAD) times and significant nutrient loss in cherries, this study employs ultrasound-assisted hot air drying (USA-HAD) technology. The study investigates the impacts of various ultrasound (US) frequencies, US powers, and hot air temperatures on the drying kinetics, physicochemical properties, texture attributes, and microstructure of cherries during drying. Cherry physicochemical quality serves as the evaluation criterion, with the entropy-weighted TOPSIS method used to identify the optimal drying parameters. The findings indicate that USA-HAD accelerates the drying process, reduces drying time, and enhances drying efficiency. In comparison to natural drying, USA-HAD significantly preserves polysaccharides, total phenolic content, total flavonoid content, and organic acids in cherries, while boosting antioxidant activity. Concurrently, it reduces color intensity, as well as the hardness, chewiness, and gumminess of dried cherry products. Microstructural observations under different drying methods reveal an increase in surface micropores and relatively intact tissue structure. Under conditions of 55°C, 48W, and 28kHz, cherries exhibit superior overall quality based on the TOPSIS relative closeness degree. This study offers practical insights for optimizing post-harvest processing of cherries. PRACTICAL APPLICATION: In this rapidly evolving era, the application of combination drying technology is clearly on the rise. The USA-HAD treated cherries had better nutritional and bioactive than HAD. The conclusions obtained indicate that the USA-HAD technology has more potential for development.

Analysis of Corn Drying Rack Position on Tray Type Dryer on Drying Rate

This research aims to determine the drying characteristics of corn kernels using a tray-type dryer, including the moisture content of the corn kernels over time, the mass of the tested corn kernels over time and the drying rate over time. This research uses the experimental method. The drying process uses an incoming drying hot air temperature of 65ºC with an incoming hot drying air speed of 2 m/s, repeated three times until a water content of 14 ± 0.5% is reached. The dryer in this study used four stacking shelves counting from the bottom, which were filled with 500 grams per shelf. This research shows that the further the shelf is positioned from the incoming hot drying air, the lower the drying rate. Vice versa, the closer the drying Shelf is to the incoming hot air, the greater the drying rate. The average decrease in corn kernel mass was 0.95% for shelf 1, 0.93% for shelf 2, 0.90% for shelf 3 and 0.88% for shelf 4 during a drying period of 3.5 hours. The average decrease in water content was 4.4% for shelf 1, 4.29% for shelf 2, 4.15% for shelf 3 and 4% for shelf 4 during a drying period of 3.5 hours. The further the position of the shelf from the hot air dryer, the less air content contained in the material on the shelf can be absorbed by the hot air dryer and vice versa. The average drying rate was 16.8% for shelf 1, 15% for shelf 2, 13.6% for shelf 3 and 12.8% for shelf 4 during a drying period of 3.5 hours at a drying hot air temperature of 65oC with a drying air speed of 2 m/s. The research data analysis results showed that the hot air dryer should not be passed from below but rather from the side. This affects the drying process in the dryer and makes it evener.

Numerical simulation and analysis on melting characteristics of a solid-liquid phase change process based on hot air riveting

To improve welding efficiency, a hot air riveting technology applicable to simultaneous welding at multiple stations is proposed, with the challenge lying in clarifying the melting state of the weldment. A numerical simulation method is proposed to investigate the melting state of the tag, using the Audi airbag tag as an example. The effects of various process parameters, including the exhaust duct distance, hot air temperature, hot air velocity, and the diameter ratio β, on the melting state of the tag are discussed. The melting mass, internal contour plots of the weldment and the melting rates are compared among the different parameter settings. The results indicate that under a heating temperature of 240 °C, the increase in hot air velocity has the most significant promotional effect on the melting of the weldment. Moreover, regardless of the velocity level, an increase in hot air temperature consistently enhances the melting of the weldment. Concurrently, an increase in the exhaust duct distance has an adverse impact on melting, yet this effect diminishes as the heating temperature rises. Finally, it is observed that at lower temperatures (200 ℃), diameter ratio β = 2.0 is more conducive to melting, whereas at higher heating temperatures (240, 280 ℃), β = 2.5 is more favorable for the melting of the weldment. This method effectively grasps the melting behavior of the weldment, enabling the selection of appropriate process parameters for hot air welding in actual production based on specific requirements.

Integrating Microwave Heating with Foam-Mat Drying: Drying Kinetics and Optimization for Thick Foamed Mango Pulp

This study addresses the challenge of processing undersized or overripe mangoes by integrating microwave heating with traditional foam-mat drying technique. The study aims at investigating drying kinetics coupled with thin-layer drying modeling and influences of microwave power (300 - 600 W) and hot-air temperature (55 - 75 °C). Among ten drying models, the so-called Midilli equation fitted well with experimental data. Results showed enhanced drying process associated with microwave heating, providing reduced drying time from 600 - 700 min (for conventional hot-air mode) to 30 - 100 min (for microwave-assisted mode). Standard deviations of moisture content and dried foam thickness measured at various points revealed uneven heat distribution when using high microwave energy, evidenced by burnt spots at 600 W. Additionally, foam collapse was observed under the mild process with low microwave powers, possibly due to prolonged drying periods. Response surface methodology demonstrated that microwave power was more important factor, positively affecting effective diffusivity coefficient (Deff) while inversely influencing specific energy consumption (SEC) and color difference (DE). Deff value increased from 5.41´10-6 m²×s-1 at 300 W and 55 °C to 18.43´10-6 m²×s-1 at 600 W and 75 °C, confirming enhance drying performance. As assisted with microwave heating, drying foamed mango sample consumed less energy up to 92 %. Optimal drying parameters were determined based on balancing the enhancement of drying performance and color alteration, suggesting drying the thick foamed mango pulp at temperature of 55 °C combined with microwave heating at 520 W, which can be served as a basis for further industrial scale-up. HIGHLIGHTS Novel method for thick mango pulp snacks. Reduced drying time from 600 - 700 to 30 - 100 min. Lowered energy use to 5.83 kWh×kg-1. Optimal conditions at 520 W, 55 °C, desirability 0.669. Applied Midilli model with 99 % accuracy. GRAPHICAL ABSTRACT

粮食干燥机自吸式热风变温装置设计与试验验证

During the grain drying process, in order to adjust the temperature, it is necessary to match the proportion of hot and cold air. This is the problem that the two components in the mixed gas cannot fully mix with each other in a short period of time, resulting in the problem that it takes a long time for the gas flow temperature to reach a stable value. Based on the process and technical requirements of the dryer, a self-priming hot air temperature changing device suitable for the dryer was designed. The two gas components used to improve the variable temperature ratio of the dryer are fully mixed with each other in a short time and a short distance, thereby reducing the loss caused by the food not reaching safe moisture. Based on Bernoulli's principle and the basic theory of airflow mixing in fluid dynamics, a mathematical model of airflow mixing in the constriction section of the main pipeline was established. Fluent was used to numerically simulate the distribution of uniform mixing distance and temperature field in the necking section. The results show that the mixing uniformity in the necking section reaches 75%-80%, which effectively improves the mixing efficiency. A self-priming hot air temperature change device test bench developed independently was used, and the quadratic orthogonal rotation combined test method was used for parameter optimization. Design-Expert.V8.0.6.1 was used for analysis and testing, and the regression equation and response surface were obtained to analyze the effects. Interaction between factors to determine the best combination of optimization parameters: when the number of air inlet pipes is 3.16, the incision axial angle is 27.6°, the temperature difference is 43.5°C, and the pipe diameter is 23.8mm, the post-mixing temperature is 50.93°C, and the mixing distance is uniform is 39.33mm. The test results are consistent with the optimization results. The self-priming hot air temperature changing device of the dryer has certain practical application value.

太阳能-热泵联合干燥条件下紫花苜蓿动态干燥特性

To promote the application of solar energy-heat pump combined drying technology in forage processing and enhance the drying efficiency of alfalfa, an experimental study was conducted. The research utilized a solar energy-heat pump drying system and a mesh belt dynamic drying device to investigate the drying characteristics of alfalfa. Drying characteristic curves were obtained, and the drying model and parameters were determined through model comparison. The study also analysed the impact of factors such as hot air velocity, temperature, alfalfa stacking thickness, turning angle of the spinner rack, and conveyor belt speed on the drying characteristic curves and parameters of alfalfa. A predictive model for alfalfa moisture content was developed, and the effective moisture diffusivity and activation energy were calculated. The findings revealed that alfalfa does not exhibit a constant speed drying stage, and its drying primarily occurs during the deceleration drying stage. The Logarithmic model was found to accurately describe the moisture change pattern during the dynamic drying process of alfalfa, with a model fitting coefficient R^2 exceeding 0.994, with an effective moisture diffusivity ranging from 2.776×10-10 m2/s to 4.7324×10-9 m2/s, and an activation energy of 37.02 kJ/mol. The study suggests that increasing the hot air velocity and temperature, reducing the conveyor belt speed, and adjusting the alfalfa stacking thickness can further enhance the drying rate and reduce the drying time.

Ultrasonic atomization technique for enhancing humidification process in thermal desalination

The need for desalination is expected to evolve, and interests in novel techniques to enhance thermal desalination are developing. Research studies on ultrasonic atomization for desalination application has been observed in the last few years. Hence, this study aims to examine humidification process enhancement using ultrasonic atomization and interaction of atomized droplets with hot air in the humidifier. In the Humidification and Dehumidification (HDH) desalination system examined, the humidifier is equipped with a single ultrasonic atomizer unit which operates continuously with preheated hot air entering the humidifier chamber. The system is investigated for different air flowrates (40 – 100 LPM) and hot air temperatures (40, 50, and 60 °C). The average relative humidity at the humidifier outlet was maximum reaching 94 % for the highest flowrate. The results indicate that increasing hot air temperatures have significant improvement in droplet evaporation which causes higher relative humidity at the outlet, and increasing hot air flowrates have significant impact on the faster response of the humidification process to reach equilibrium.

Reduction of carbon emission in iron sintering process based on hot air sintering technology

Reducing carbon dioxide (CO2) emissions in the iron and steel industry plays a crucial role in addressing global climate change. One significant technological solution for reducing CO2 emissions in iron and steel production is the recycling of waste heat. Hot air sintering has the potential to decrease CO2 emissions from flue gas by reusing hot flue gas in the production process. This can result in a reduction in the consumption of fossil fuels. Usually, the relationship between the hot air temperature and the carbon content determines the CO2 emission reduction effect. In order to meet the demand for reducing CO2 emissions, this paper thoroughly investigates the mechanism of CO2 reduction by hot air sintering through sintering pot experiments. It precisely establishes the correlation between hot air temperature and carbon content, and suggests strategies for effectively managing hot air sintering based on scientific principles. The results show that hot air sintering achieves a reduction in CO2 emissions by enhancing fuel combustion heat utilization and heat substitution. On the one hand, the heat of the sinter bed surface layer is increased, which improves the mineralization conditions and increases the sintered mineral quantity and quality, thus reducing the CO2 emission by 4.4%; on the other hand, the waste heat is returned to the sinter bed to replace part of the fuel combustion heat, thus reducing the CO2 emission by 17.7%. The experimental results show that the best carbon reduction effect is achieved at a hot air temperature of 300 °C and a solid fuel ratio of 4.7% (labelled T300-C47), which reduces carbon emissions by 17.7% and improves the quality of the sintered minerals. Combined with the actual production, in the range of 200–300 °C hot air, by increasing the hot air temperature to replace the solid fuel with equal heat can realize the hot air sintering to reduce CO2 emissions and improve the sintering production. The research provides theoretical guidance for the clean production of iron and steel sintering and energy saving and carbon reduction.

Experimental study on the performance of enhanced air-cooled photovoltaic thermal energy-supplied manure treatment technology

Implementing renewable energy technologies for manure treatment to reduce energy consumption and environmental damage is steadily becoming more prevalent. In this work, an air-cooled photovoltaic thermal (PV/T) device was enhanced and constructed to provide energy for bio-composting manure treatment. Experiments were conducted to analyze the performance data such as air supply temperature, energy and exergy efficiency, and mass flow rate. When calculating the mass flow rate of the PV/T-supplied manure treatment technology, factors such as exergy efficiency, and hot air temperature must be considered. The results of the study indicate that the thermal performance of the developed equipment is adequate for manure composting treatment. The thermal exergy efficiencies of the V2, V3, and V4 cases are approximately 1/3 greater than the thermal exergy efficiency of the V1 case, indicating a considerable change in thermal efficiency. The mass flow rate of 0.020 kg/s is determined to be a more suitable set value. Its total exergy efficiency can reach 46.79%, and the apparatus could heat up to 43.63 kg/m2 of compost to begin the bio-composting process. This study lays the groundwork for future research and deployment of PV/T-powered manure treatment devices.

Double-ended vacuum tube collector based solar powered atmospheric water harvesting by using composite desiccant material ‘Jute/CaCl₂’

ABSTRACT Amidst increasing fresh water crisis, sorption based solar powered atmospheric water harvesting (SPAWH) offers a promising solution to this problem. The available sorption based systems use composite desiccants that are expensive and artificially processed, which restricts their scalability and practical implementation. Moreover, the required desorption temperature available from the system is also low. The proposed system develops and experimentally investigates a novel composite desiccant material synthesized using anhydrous CaCl₂ impregnated in Jute (intrinsic host material), which is cheap and naturally available. To desorb the composite desiccant, 4.86 m2 double-ended vacuum tube collector is used, which produces peak hot air temperature of 134.2°C. The developed system using 12 kg composite of Jute/CaCl₂ harvests 5850 ml/day of water at 0.086 $/L cost with 13.93% thermal and 8.66% exergy efficiency. The results of the water analysis verify that the harvested water is of good quality and is safe for use.

Nonlinear vibration characteristics of thermo-viscoelastic coupling of moving PET films with temperature-dependent elastic modulus

In order to improve the transport stability of roll-to-roll produced polyethylene terephthalate films (PET films) in high temperature environments, this paper investigates the nonlinear vibrational properties of moving PET films under a uniform temperature field by considering the temperature dependence of the elastic modulus. Firstly, constant tensile tests were conducted to test the elastic modulus values of PET films at different hot air temperatures, and the Wachtman model was improved to establish a temperature-dependent elastic modulus model for PET films. Secondly, based on the Kelvin-Voigt model, the nonlinear vibrational equilibrium differential equations of the system were established by applying the Bubnov-Galerkin method of discretization according to D’Alembert’s principle. Finally, numerical simulations based on the 4th-order Runge-Kutta method were carried out to analyze the effects of films width, external excitation frequency, external excitation amplitude, transfer velocity, ambient temperature, damping coefficient and viscoelasticity coefficient on the nonlinear vibration of the system. This provides a theoretical basis for the commissioning of stabilized transfer parameters for roll-to-roll production of PET films.

American Ginseng Slice Drying and Optimization: Effect of Different Drying Methods on Drying Kinetics and Physicochemical Properties

This study compared four drying methods, namely hot-air and vacuum combined drying (HAVCD), hot-air drying (HAD), vacuum drying (VD), and vacuum freeze-drying (VFD), with the aim to select a high-quality and efficient drying method to dry American ginseng slices. Drying kinetics and various physicochemical properties, such as color, rehydration ratio, total ginsenoside content, total ginsenoside residual rate, hardness, and microstructure were explored. An improved multi-indicator test formula method was used to score the experimental results quantitatively. HAVCD resulted in comprehensive advantages, with the highest product score for the dried American ginseng slices. Therefore, HAVCD was subjected to a response surface methodology (RSM) analysis and process optimization. The interaction of hot-air temperature and vacuum temperature on the comprehensive score of American ginseng drying was highly significant (p < 0.01). The optimized and validated process parameters obtained were a hot-air temperature of 57 °C, a vacuum temperature of 54 °C, and a moisture content at the conversion point of 39% (wet basis). Under these conditions, the best drying time was 170 min; the total ginsenoside content was 2.3 mg/100 g; the L* value was 91.68; the rehydration ratio was 3.10; and the comprehensive score was 96.77. The findings of this work indicated HAVCD as a promising drying method for American ginseng slices, considering the drying time and dried-product quality attributes.

Effects of different drying methods on physicochemical, textural, flavor, and sensory characteristics of yak jerky

The work aimed to study the effect of four drying methods, namely constant temperature hot air drying (HD), microwave drying (MD), hot air microwave drying (HMD), and gradient hot air drying (GHD), on quality characteristics of dried yak meat. The analyses of physicochemical, textural, flavor, and sensory characteristics were carried out based on these four drying methods. The results revealed that microwave dried yak jerky exhibited better color and received the highest sensory score. Hardness of samples were affected by the drying methods, which showed significant differences. There were 21 free amino acids (FAAs) detected in dried yak samples. The samples treated by microwave drying showed the highest total free amino acid content (73.30 mg/100 g) and the EUC value was significantly higher than other methods, indicating the sample displayed greater flavor. A total of 153 volatile compounds were identified in dried yak meat samples, primarily including aldehydes, ketones, and esters. Moreover, the sensory evaluation indicated that the drying methods could significantly affect on color, flavor, and overall acceptability of different samples. Microwave drying samples scored higher than other drying methods. Overall, considering aspects of quality, time savings, and energy efficiency, microwave drying of yak jerky emerges as a more satisfactory option. This study could provide important theoretical support for the application of drying methods to improve the quality of yak jerky and enhance production efficiency.

Study on the characteristics and kinetics of microwave hot air combined drying of peanut pods

Drying is an important means to maintain the quality of peanut pods and reduce the risk of mildew. Microwave hot air combined drying is renowned for its efficacy, low-energy consumption, and superior processing quality, rendering it suitable for peanut pod drying. However, its efficacy hinges greatly on various parameters. To enhance drying efficiency and quality, the drying kinetics of peanut pods using microwave hot air combined drying equipment were investigated. Varying microwave power (1.2 kW, 2.4 kW, 3.6 kW), hot air temperature (30 °C, 35 °C, 40 °C, 45 °C), air velocity (0.4 m/s, 0.7 m/s, 1 m/s), and microwave radiation time (4 min, 6 min) were examined. Results indicated a decline in drying time, moisture ratio, and drying rate with increasing microwave power, hot air temperature, air velocity, and microwave radiation time. Peroxide and acid values complied with national standards. The Verma model exhibited optimal fitting. At 45 °C, peanut pod moisture diffusion coefficient was 3.022 × 10−9 m2 s−1, specific energy consumption at 30 °C was 5302 kJ/kg, and thermal efficiency was 42.6 %. The synergistic drying of peanut pods by microwave and hot air has a high moisture diffusion coefficient and thermal efficiency. The kinetic and energy analysis of the drying process can furnish some theoretical foundation for subsequent microwave hot air drying and equipment parameter adjustment.

Convective drying of bitter yam slices (Dioscorea bulbifera): Mass transfer dynamics, color kinetics, and understanding the microscopic microstructure through MATLAB image processing

The objective of this research endeavor was to enhance the quality and storability of Dioscorea bulbifera through the investigation of the effects of pre-treatment (soaking) and different dehydration temperatures (50, 60, and 70°C) on its mass transfer, color kinetics, texture, microstructure, and rehydration properties. Ten drying and four-color kinetics models were employed to describe drying behavior and color changes. The drying process demonstrated a falling rate, with reduced drying time (from 960 to 540 min) as the convective temperature increased from 50 to 70°C. Moisture diffusivity increased with increasing hot air temperatures (4.15 ×10–10 – 1.03 ×10–9 m2/s), and the activation energy was determined as 41.82 kJ/mol. Slices dried at 70 °C exhibited higher color change than those dried at 50°C. The modified color model fitted the best color parameters, followed by the fraction model. Slices dried at 60°C showed lower hardness (34.73 N) and higher porosity (27.03 %) as compared with 50°C (49.33 N and 19.82 %) and 70°C (40.16 N and 21.90 %) temperature. Microstructure, moisture diffusion, and texture were closely linked to temperature and moisture content. Boiling and potassium metabisulfite significantly affected drying rate and texture of yam slices . MATLAB analysis provided detailed pore information for each hot air-dried sample, correlating with texture characteristics. This research offers substantial industrial significance by providing methods to enhance dried yam products' quality, shelf-life enhancement, and further exploration of starch extraction and recovery of valuable bioactive compounds.

Experimental investigation of a hybrid photovoltaic-thermal energy system for hot air production

Solar energy as a non-fossil alternative energy source has become the best choice to overcome the problem of energy demand in most countries in the world. There are two different techniques to convert solar energy: photovoltaic (PV) panels to produce electricity and thermal collectors to generate heat. The two technologies can be combined to provide electrical and thermal energy either simultaneously or separately. In order to optimize the performance of a hybrid photovoltaic-thermal (PVT) solar air heater, it is necessary to collect experimental data on solar irradiation and temperature. This paper emphasized the development of a PVT energy system for hot air production in a temperature range of 50-55 °C. Additionally, experiments were constructed to monitor the information acquired from the proposed PVT solar air heater and the environment, such as hot air temperature, ambient temperature, and solar irradiation. The real-time monitoring system was set for five sample days. A microcontroller unit was used to control the hot air temperature and save the measurement data into memory. The experimental results showed that the proposed PVT solar air heater is capable of maintaining a certain level of hot air temperature throughout the day and night.

Coupling drying of wet and heat field of corn pile based on porous medium model

AbstractCorn that are not properly dried can result in a lot of waste. Therefore, in this study, the corn pile was used as porous medium for hot air drying, and the coupling method of multiple physical fields was used to simulate and analyze the corn air‐drying silo with different initial conditions and different sizes. The results show that increasing the temperature of hot air could increase the temperature gradient inside corns and promote the evaporation of water. The higher the wind speed, the better the convective heat transfer effect between corn and air, thus improving the drying efficiency. The smaller the ratio of height to diameter of air‐drying silo, the more corn dried in the direction of hot air flow, resulting in poor drying effect. Increasing the inner diameter of the air‐drying silo will reduce the heat transfer efficiency. The lower the bed of the air‐drying silo, the closer the corns are to the hot air inlet, the faster the heating rate and the better the drying effect. The model has good performance and can be used as a mathematical tool to predict the change of maize wet heat field.Practical applicationsIn order to solve the integral problem of corn drying, the model uses corn grain pile as porous medium for hot air drying. The model investigated the changes of temperature field and humidity field during the drying process of grain pile in corn air‐drying silo. In addition, the characteristics of the model introduced in this study may qualify it for automatic control of corn air‐drying silo and online prediction of drying times to achieve the desired drying effect.

The effect of spray drying parameters on drying of magnesium silicate hydroxide microspheres

Magnesium hydroxide silicate (MSH), as an antiwear additive for lubricating oil, effectively solves the problem that conventional additives contain chlorine, phosphorus and sulfur, which are harmful to environment. However, it is ineffective to prepare MSH powder by traditional drying combined with mechanical ball milling. So the purpose of this study is to prepare smooth MSH microspheres with controllable particle size and moisture content by adjusting spray drying parameters based on hydrothermal synthetic MSH suspension. Results showed that the particle size of MSH microsphere was reduced from 5.5 ± 2.9 μm to 2.78 ± 1.37 μm, and the moisture content was reduced from 7.3% to 4.43% by decreasing solid-liquid ratios and rotating speed of peristaltic pump, or raising inlet temperature of hot air, flow rate of compressed gas and inlet air. In addition, due to the surface energy difference at the interface between liquid-gas and solid-gas during the drying process, nano flaky MSH continuously moved to the center of the droplet, and the capillary force generated by gaps between MSH nanosheets discharges the moisture in the wet core, so that the MSH nanosheets gather and finally form dense and smooth MSH microspheres.