An experimental study was performed to determine the characteristics and drying process of mushroom （Lentinus edodes） by 6 different hot-air drying methods namely isothermal drying, uniform raise drying, non-uniform...An experimental study was performed to determine the characteristics and drying process of mushroom （Lentinus edodes） by 6 different hot-air drying methods namely isothermal drying, uniform raise drying, non-uniform raise drying, uniform intermittent drying, non-uniform intermittent drying and combined drying. The chemical composition （dry matter, ash, crude protein, crude fat, total sugars, dietary fiber, and energy）, color parameters （L, a＊, b＊, c＊, and h~） and rehydration capacities were determined. Among all the experiments, non-uniform intermittent drying reached a better comprehensive results due to the higher chemical composition, better color quality associated with high bright （26.381＋5.842）, high color tone （73.670＋2.975）, low chroma （13.349a：3.456） as well as the highest rehydration （453.76% weigh of dried body）. Nine kinds of classical mathematical model were used to obtained moisture data and the Midili-kucuk model can be described by the drying process with the coefficient （R2 ranged from 0.99790 to 0.99967）, chi-square （X2 ranged from 0.00003 to 0.00019） and root mean square error （RMSE ranged from 0.000486 to 0.0012367）.展开更多
Appropriate drying process with optimized controlling of drying parameters plays a vital role in the improvement of the quality and performance of propellant products.However,few research on solvent transport dynamics...Appropriate drying process with optimized controlling of drying parameters plays a vital role in the improvement of the quality and performance of propellant products.However,few research on solvent transport dynamics within NC-based propellants was reported,and its effect on the evolution of mechanical properties was not interpreted yet.This study is conducted to gain a comprehensive understanding of hot-air drying for NC-based propellants and clarify the effect of temperature on solvent transport behavior and further the change of mechanical properties during drying.The drying kinetic curves show the drying time required is decreased but the steady solvent content is increased and the drying rate is obviously increased with the increase of hot-air temperatures,indicating hot-air temperatures have a significant effect on drying kinetics.A modified drying model was established,and results show it is more appropriate to describe solvent transport behavior within NC-based propellants.Moreover,two linear equations were established to exhibit the relationship between solvent content and its effect on the change of tensile properties,and the decrease of residual solvent content causes an obvious increase of tensile strength and tensile modulus of propellant products,indicating its mechanical properties can be partly improved by adjustment of residual solvent content.The outcomes can be used to clarify solvent transport mechanisms and optimize drying process parameters of double-based gun propellants.展开更多
This study explores the thin-layer convective solar drying of Marrubium vulgare L.leaves under conditions typical of sun-rich semi-arid climates.Drying experiments were conducted at three inlet-air temperatures(40℃,5...This study explores the thin-layer convective solar drying of Marrubium vulgare L.leaves under conditions typical of sun-rich semi-arid climates.Drying experiments were conducted at three inlet-air temperatures(40℃,50℃,60℃)and two air velocities(1.5 and 2.5 m·s^(-1))using an indirect solar dryer with auxiliary temperature control.Moisture-ratio data were fitted with eight widely used thin-layer models and evaluated using correlation coefficient(r),root-mean-square error(RMSE),and Akaike information criterion(AIC).A complementary heattransfer analysis based on Reynolds and Prandtl numbers with appropriate Nusselt correlations was used to relate flow regime to drying performance,and an energy balance quantified the relative contributions of solar and auxiliary heat.The logarithmic model consistently achieved the lowest RMSE/AIC with r>0.99 across all conditions.Higher temperature and air velocity significantly reduced drying time during the decreasing-rate period,with no constantrate stage observed.On average,solar input supplied the large majority of the thermal demand,while the auxiliary heater compensated short irradiance drops to maintain setpoints.These findings provide a reproducible dataset and a modelling benchmark for M.vulgare leaves,and they support energy-aware design of hybrid solar dryers formedicinal plants in sun-rich regions.展开更多
In order to improve the heat and mass transfer process in hot-air drying,power ultrasound was coupled directly to hot-air drying of fresh carrot slices.The effects of ultrasonic power,radiation distance,hot air veloci...In order to improve the heat and mass transfer process in hot-air drying,power ultrasound was coupled directly to hot-air drying of fresh carrot slices.The effects of ultrasonic power,radiation distance,hot air velocity and temperature on drying characteristics were studied.In addition,the Page equation was used to fit the ultrasound assisted hot-air drying process of the carrot slices.The results showed that the drying rate of carrot slices increased with the increase of ultrasound power and the decrease of radiation distance.Power ultrasound had a greater enhancement on hot-air drying at lower air velocity(0.5 m/s)and temperature(40ºC),especially at the middle and later periods(controlled by internal diffusion).The drying time of carrot slices using ultrasound assisted hot-air drying was shortened by 37.5%compared to that using hot-air drying at the condition with power of 150 W,radiation distance of 15 cm,air velocity of 1.0 m/s and temperature of 40ºC.All test indicators of the model meet the accuracy requirements,which show that the model can better fit the experimental values.展开更多
The drying characteristics,physico-chemical and functional properties,as well as starch digestibility,of purple potato slices dried using different methods(such as,vacuum freeze-drying,VFD;hot-air drying,HAD;air-impin...The drying characteristics,physico-chemical and functional properties,as well as starch digestibility,of purple potato slices dried using different methods(such as,vacuum freeze-drying,VFD;hot-air drying,HAD;air-impingement jet drying,AIJD;and far-infrared assisted heat-pump drying,FIHPD)were investigated.Drying rate was the highest(3.0 g 100 g^-1 min^-1)using AIJD,followed by FIHPD and HAD,and the rate of VFD was the lowest one(0.3 g 100 g^-1 min^-1).Drying data were fitted to 12 thin-layer drying models,with the Midilli model giving the best predictions.Moreover,AIJD showed higher diffusivity(5.5×10^-10 m^2 s^–1)and energy efficiency(55 J g^-1)than any other drying method used in this study.With reference to the samples dried by VFD,the starch granules of the samples obtained by HAD,FIHPD,and AIJD exhibited different extent of disruption,which significantly increased their water absorption capacity,swelling power,and in vitro digestibility,but decreased the peak viscosity.The sample resulting from AIJD had the greatest water absorption capacity(7.9 g g^-1)and solubility(21.6%),but the smallest syneresis rate(48%).Good correlation coefficients(R^2>0.98)implied that the pseudofirst order kinetic model adequately described the rate and extent of starch digestion of dried potato flours.Samples from AIJD and FIHPD showed the highest digestibility percentages,reaching to 72.4 and 72.5%.Based on the drying rate,specific energy consumption,functional properties and digestibility,AIJD appeared to be quite effective and suitable to be transferred on the industry scale.展开更多
Exploring new drying technology can help to deal with the challenge of better preservation of rhizome medicinal materials in the traditional Chinese medicine industry.In current work,combined infrared and hot-air dryi...Exploring new drying technology can help to deal with the challenge of better preservation of rhizome medicinal materials in the traditional Chinese medicine industry.In current work,combined infrared and hot-air drying(IR-HAD)was employed to Panax notoginseng roots and its effect on drying kinetics,energy efficiency and quality,i.e.,rehydration ratio(RR),color parameters(L^(*),a^(*),b^(*)),total color difference(ΔE),Panax notoginseng saponins(PNS)content,and ginsenosides content(R_(1),R^(g1),R_(e),R_(d),R_(b1))were evaluated.Hot air drying(HAD)was used as the control.Results showed that the increase in drying temperature significantly shortened drying time and reduced energy consumption.The shortest drying time of 43.0 h and lowest specific energy consumption of 15.9 kW·h/(kg-water)were obtained by IR-HAD at 55°C.The decrease of radiation distance and the increase of radiation power led to the shortening of drying time.However,high drying temperature resulted in largeΔE values,large collapse structure,and RR of samples.The drying time of Panax notoginseng roots dried by IR-HAD at a drying temperature of 50°C was shorter(15.5%)than HAD dried at the same drying temperature.The contents of R_(1),R_(g1),R_(e),R_(b1),and PNS were higher when the samples were dried by IR-HAD than those dried by HAD at the same temperature of 50°C.Moreover,the IR-HAD dried samples shortened 15.5%drying time and saved 22.1%energy consumption compared with HAD.Therefore,the optimal process condition was Panax notoginseng roots under IR-HAD at drying temperature of 50°C,radiation distance of 12 cm and radiation power of 1350 W,which can shorten drying time,maintain high ginsenosides contents and satisfactory apparent qualities.展开更多
Characteristics of cassava drying were investigated by using a microwave hot-air drying system. Two waveguides were installed on a single plane of the microwave cavity. The drying experiments were carried out at two l...Characteristics of cassava drying were investigated by using a microwave hot-air drying system. Two waveguides were installed on a single plane of the microwave cavity. The drying experiments were carried out at two levels of sample surface temperature set-points, 70℃ and 80℃respectively. Cassava (Rayong-9) with 2.5 kg weight and 61% moisture content on wet basis was dried in the dryer for about 300 - 340 minutes until the final values of moisture content of about 20% db were achieved. It was found that the drying time decreased with an increase in sample-surface temperature set point. Approximately 87% of the moisture was removed during the drying period. It was found that there was a rapid decrease in moisture ratio values followed by the gradual decline period in all experiments. With regard to drying kinetics, 5 commonly used mathematical models were examined with the experimental data. It was found that Page’s and diffusion models provided a good agreement between the experimental and predicted moisture ratio values for all temperature set-points. The regression results indicated that highest values of coefficient of determination and adjusted coefficient of determination as well as lowest value of standard error of estimation were reported for the case of Page’s model at 80℃?temperature set-point.展开更多
The drying kinetics of Roselle （Hibiscus sabdariffa L） of variety Terengganu （UMKL-1） and the quality attribution of Roselle were studied. The experiments were conducted using four different drying methods, includ...The drying kinetics of Roselle （Hibiscus sabdariffa L） of variety Terengganu （UMKL-1） and the quality attribution of Roselle were studied. The experiments were conducted using four different drying methods, including solar greenhouse drying （SD）, solar greenhouse with intermittent heat pump drying （SIHP）, hot air drying （HA） and heat pump drying （HP）. Among the four drying methods, HP achieved the highest drying rate at a range from 0.054 g H20-（g DM）-1. rain-1 to 0.212 g H20-（g DM）-1. rain 1 while SD had the lowest drying rate, measured at 0.042 g H2O. （g DM） 1.min- 1. The analysis on colour kinetics revealed that there is no significant colour loss （p 〉 0.05） observed from HP＇s dried Roselle. Greater amount of flavonoid compounds i.e. protocatechuic acid was found in SD and SIHP dried finished product whereas HP＇s dried Roselle contains higher percentage of catechin as compared to other drying methods.展开更多
Though several maize varieties have been developed and introduced over the years in Ghana, farmers still face challenges of access to quality seed maize. Among the major constraint is lack of proper drying systems to ...Though several maize varieties have been developed and introduced over the years in Ghana, farmers still face challenges of access to quality seed maize. Among the major constraint is lack of proper drying systems to guarantee quality of seed produced. As in most parts of Africa, drying of maize in the open, on bare ground along shoulders of roads is still a common practice in Ghana. In this study, a 5-tonne capacity hybrid solar biomass dryer was developed for drying maize for seed and food/feed in Ghana. Effect of air temperature in the dryer on the physiological quality and germination of maize kernels was investigated. Maize grains were dried in the open sun simulating farmers practice and using the dryer at 4 varying levels (L1, L2, L3 and L4) with corresponding heights (0.6 m, 1.2 m, 1.8 m and 2.4 m, respectively) from the ground. Harvested maize at 22.8% moisture content was dried at the varying levels until reaching the final desired moisture content of 12.8% ± 0.2% (wb). Results showed that, air temperatures in the dryer increased in accordance with height with lowest mean temperature of 44.4°C ± 4.6°C recorded at L1 and mean maximum of 52.8°C ± 5.4°C at L4. Drying temperatures recorded at L1 - L3 and ambient had no significant effect (p < 0.05) on kernel damage and viability. Drying conditions at L1-L3 were considered optimum (<50°C) for kernel drying compared to the topmost tray, L4. Kernel stress crack index (multiple and checked) was therefore reduced on average by 14% while kernel germination increased by 33%. This satisfies the dryer’s potential to be used for commercial drying of maize grains for seed production for smallholder farmers in Ghana.展开更多
A modelling study was performed to solve the heat and mass transfer problems between grain and the ambient air encountered during drying by microwave assisted hot-air dryer,under low microwave(MW)density of 0.2 W/g.Ca...A modelling study was performed to solve the heat and mass transfer problems between grain and the ambient air encountered during drying by microwave assisted hot-air dryer,under low microwave(MW)density of 0.2 W/g.Canola(Brassica napus),soybean(Glycine max)and corn(Zea mays)seeds were chosen due to their inherent high oil content.Scanning electron microscopy(SEM)was used to study the effect of drying conditions on the structural characteristics of these oilseeds.A mathematical model was adapted to simulate drying of one seed of canola,soybean and corn.The process of water transfer was modelled based on the effect of vapour pressure on the water molecules inside the seed.It was observed that when the difference between the vapour pressure inside the grain and the surrounding air was higher than,the drying rate increased which led to cracks in the grain.Results showed that the drying rate decreased when the temperature of air inside the cavity of the microwave increased for all the oilseeds studied,because of the reduced differential vapour pressure between the grain and the ambient air.On the other hand,the drying rate increased if the temperature of the inlet air was reduced because the difference between the two pressures increased.It was concluded that by controlling the ambient air,the grains could be protected against popping and cracking because of lower vapour pressure differential during MW assisted hot-air drying.展开更多
Hydric properties evolution during drying differs from one product to another and has been the subject of various studies due to its crucial importance in modeling the drying process. The variation of these parameters...Hydric properties evolution during drying differs from one product to another and has been the subject of various studies due to its crucial importance in modeling the drying process. The variation of these parameters in the solid matrix and in time during the drying of Spirulina platensis has not known an advanced understanding. The objective of this study was to evaluate the evolution of the water content profile, the mass flow, the concentration gradient and the diffusion coefficient during the drying of Spirulina platensis taking into account the shrinkage. Modeling and experimental analysis (at 50°C and HR = 6%) by the cutting method a cylinder 20 mm in diameter and 40 mm thick were carried. The water content profiles of two different products grown in semi-industrial farms from Burkina Faso and France with initial water contents respectively of the range from 2.73 kgw/kgdb and 3.12 kgw/kgdb were determined. These profiles have been adjusted by a polynomial function. Identical water behavior is observed regardless of the origin of the samples. Water distribution is heterogeneous. Mass flow and concentration gradient are greater at the edge than inside the product. The water transport coefficient, ranging from 1.70 × 10?10 to 94 × 10?10 m2/s, is determined from a linear approach.展开更多
本文采用电熔炉冶炼低品位DRI,开展百公斤级扩大化试验,探索低品位DRI电熔炉冶炼特性,包括渣铁分离效果、铁水渗碳效果、铁收得率等,并利用设计软件计算吨铁电耗、煤耗等指标。试验结果表明,DRI球由于具有团疏松多孔的结构,在熔炼过程...本文采用电熔炉冶炼低品位DRI,开展百公斤级扩大化试验,探索低品位DRI电熔炉冶炼特性,包括渣铁分离效果、铁水渗碳效果、铁收得率等,并利用设计软件计算吨铁电耗、煤耗等指标。试验结果表明,DRI球由于具有团疏松多孔的结构,在熔炼过程中始终漂浮在熔池上方;在二次电压120 V下,电极始终为浸没式操作,不能实现刷弧或明弧操作。通过从顶部加入无烟煤和DRI的混合物料可以实现良好的铁还原和铁水渗碳效果,铁水含碳量平均值为3.09%。在低碱度渣型和高渣率下,所得渣Fe O含量平均值为1.47%,铁收得率平均值高达98.84%。低品位DRI热态入炉生产液体热金属所需的理论吨铁电耗为511 k W·h/t,而冷态入炉的理论吨铁电耗为770 k W·h/t,热态DRI直接入炉冶炼可以节能约50%。展开更多
Industrially produced sodium water glasses were dried in climates with controlled temperature and humidity to transparent amorphous water containing sodium silicate materials. The water glasses had molar SiO2:Na2O rat...Industrially produced sodium water glasses were dried in climates with controlled temperature and humidity to transparent amorphous water containing sodium silicate materials. The water glasses had molar SiO2:Na2O ratios of 2.2, 3.3 and 3.9 and were dried up to 84 days at temperatures between 40°C and 95°C and water vapour pressures between 5 and 40 kPa. The materials approached final water concentrations which are equilibrium values and are controlled by the water vapour pressure of the atmosphere and the microstructure of the solids. The microstructure of the dried water glasses was characterized by atomic force microscopy. It has a nanosized substructure built up by the silicate colloids of the educts but deformed by capillary forces. In the final drying equilibrium, the water vapour pressure of the atmosphere in the drying cabinet is equal to the reduced vapour pressure of the capillary system built up by the silicate colloids. Their size scale can be explained by the deformation of colloidal aggregates due to capillary forces.展开更多
Soil microorganisms and labile soil organic carbon(SOC)fractions are essential factors affecting greenhouse gas(GHG)emissions in paddy fields.However,the effects of labile SOC fractions and microorganisms on GHG emiss...Soil microorganisms and labile soil organic carbon(SOC)fractions are essential factors affecting greenhouse gas(GHG)emissions in paddy fields.However,the effects of labile SOC fractions and microorganisms on GHG emissions from flooding to drying after organic fertilizer replacing for chemical fertilizer remain unclear.Here,a long-term experiment was conducted with four treatments:chemical fertilization only(control),organic fertilizer substituting 25%of chemical N fertilizer(NM1),50%of chemical N fertilizer(NM2),and NM2combined with crop straw(NMS).GHG emissions were monitored,and soil samples were collected to determine labile SOC fractions and microorganisms.Results revealed the GHG emissions in the NM2 significantly increased by 196.88%from flooding to drying,mainly due to the higher CO_(2) emissions.The GHG emissions per kg of C input in NMS was the lowest with the value of 9.17.From flooding to drying,organic fertilizer application significantly increased the readily oxidizable organic carbon(ROC)contents and C lability;the NM2 and NMS dramatically increased the SOC and non-readily oxidizable organic carbon(NROC).The bacterial communities showed significant differences among different treatments in the flooding,while the significant difference was only found between the NMS and other treatments in the drying.From flooding to drying,changing soil moisture conditions causes C fractions and microbial communities to jointly affect carbon emissions,and the NMS promoted carbon sequestration and mitigated GHG emissions.Our findings highlight the importance of the labile SOC fractions and microorganisms linked to GHG emissions in paddy fields.展开更多
This present work solves the problem of initial shape influence on transfer during convective drying. A characteristic dimension is found for the cubic, cylindrical and spherical-shaped samples of the sweet potato. Th...This present work solves the problem of initial shape influence on transfer during convective drying. A characteristic dimension is found for the cubic, cylindrical and spherical-shaped samples of the sweet potato. This characteristic dimension corresponds to the diameter D for the sphere, to the edge a for the cube and the diameter = height D = H for the cylinder. Unlike the sphere where this characteristic dimension is perfect, the cubic and cylindrical shapes have space factors which are, among other things, angles and borders. By fixing the same characteristic dimensions, we end up with overlapping curves, showing identical and uniform transfers.展开更多
CeO_(2) based semiconductor are widely used in solar-driven photothermal catalytic dry reforming of methane(DRM)reaction,but still suffer from low activity and low light utilization efficiency.This study developed gra...CeO_(2) based semiconductor are widely used in solar-driven photothermal catalytic dry reforming of methane(DRM)reaction,but still suffer from low activity and low light utilization efficiency.This study developed graphite-CeO_(2) interfaces to enhance solar-driven photothermal catalytic DRM.Compared with carbon nanotubes-modified CeO_(2)(CeO_(2)-CNT),graphite-modified CeO_(2)(CeO_(2)-GRA)constructed graphite-CeO_(2) interfaces with distortion in CeO_(2),leading to the formation abundant oxygen vacancies.These graphite-CeO_(2) interfaces with oxygen vacancies enhanced optical absorption and promoted the generation and separation of photogenerated carriers.The high endothermic capacity of graphite elevated the catalyst surface temperature from 592.1−691.3℃,boosting light-to-thermal conversion.The synergy between photogenerated carriers and localized heat enabled Ni/CeO_(2)-GRA to achieve a CO production rate of 9985.6 mmol/(g·h)(vs 7192.4 mmol/(g·h)for Ni/CeO_(2))and a light-to-fuel efficiency of 21.8%(vs 13.8%for Ni/CeO_(2)).This work provides insights for designing graphite-semiconductor interfaces to advance photothermal catalytic efficiency.展开更多
This study evaluated corn kernel drying performance and quality changes using hot air drying(HAD)and infrared drying(ID)across temperatures ranging from 55℃ to 80℃.Optimal drying parameters were determined by using ...This study evaluated corn kernel drying performance and quality changes using hot air drying(HAD)and infrared drying(ID)across temperatures ranging from 55℃ to 80℃.Optimal drying parameters were determined by using the entropy weight method,with drying time,specific energy consumption,damage rate,fatty acids,starch,polyphenols,and flavonoids as indicators.Results demonstrated that ID significantly outperformed HAD,achieving drying times up to 20%shorter and reducing specific energy consumption and kernel damage by up to 79.3%and 66.7%,respectively,while also better preserving quality attributes.Both methods exhibited drying profiles characterized by acceleration,constant,and falling rate periods,although the constant rate phase was distinctly observable only at lower temperatures.The effective moisture diffusivity under ID was consistently higher than that under HAD,with a maximum increase of 20.4%.The optimal drying conditions were HAD at 65℃ and ID at 80℃.A BP model was also developed and it showed better predictive performance and adaptability than classical mathematical models.展开更多
基金supported by the National High-Tech R&D Program of China(863 Program,2011AA100805-2)the Project from Chongqing Science and Technology Committee(CSTC2011AC1010)supported by the National Natural Science Foundation of China(31271825)
文摘An experimental study was performed to determine the characteristics and drying process of mushroom （Lentinus edodes） by 6 different hot-air drying methods namely isothermal drying, uniform raise drying, non-uniform raise drying, uniform intermittent drying, non-uniform intermittent drying and combined drying. The chemical composition （dry matter, ash, crude protein, crude fat, total sugars, dietary fiber, and energy）, color parameters （L, a＊, b＊, c＊, and h~） and rehydration capacities were determined. Among all the experiments, non-uniform intermittent drying reached a better comprehensive results due to the higher chemical composition, better color quality associated with high bright （26.381＋5.842）, high color tone （73.670＋2.975）, low chroma （13.349a：3.456） as well as the highest rehydration （453.76% weigh of dried body）. Nine kinds of classical mathematical model were used to obtained moisture data and the Midili-kucuk model can be described by the drying process with the coefficient （R2 ranged from 0.99790 to 0.99967）, chi-square （X2 ranged from 0.00003 to 0.00019） and root mean square error （RMSE ranged from 0.000486 to 0.0012367）.
基金the National Natural Science Foundation of China(Grant No.22075146).
文摘Appropriate drying process with optimized controlling of drying parameters plays a vital role in the improvement of the quality and performance of propellant products.However,few research on solvent transport dynamics within NC-based propellants was reported,and its effect on the evolution of mechanical properties was not interpreted yet.This study is conducted to gain a comprehensive understanding of hot-air drying for NC-based propellants and clarify the effect of temperature on solvent transport behavior and further the change of mechanical properties during drying.The drying kinetic curves show the drying time required is decreased but the steady solvent content is increased and the drying rate is obviously increased with the increase of hot-air temperatures,indicating hot-air temperatures have a significant effect on drying kinetics.A modified drying model was established,and results show it is more appropriate to describe solvent transport behavior within NC-based propellants.Moreover,two linear equations were established to exhibit the relationship between solvent content and its effect on the change of tensile properties,and the decrease of residual solvent content causes an obvious increase of tensile strength and tensile modulus of propellant products,indicating its mechanical properties can be partly improved by adjustment of residual solvent content.The outcomes can be used to clarify solvent transport mechanisms and optimize drying process parameters of double-based gun propellants.
文摘This study explores the thin-layer convective solar drying of Marrubium vulgare L.leaves under conditions typical of sun-rich semi-arid climates.Drying experiments were conducted at three inlet-air temperatures(40℃,50℃,60℃)and two air velocities(1.5 and 2.5 m·s^(-1))using an indirect solar dryer with auxiliary temperature control.Moisture-ratio data were fitted with eight widely used thin-layer models and evaluated using correlation coefficient(r),root-mean-square error(RMSE),and Akaike information criterion(AIC).A complementary heattransfer analysis based on Reynolds and Prandtl numbers with appropriate Nusselt correlations was used to relate flow regime to drying performance,and an energy balance quantified the relative contributions of solar and auxiliary heat.The logarithmic model consistently achieved the lowest RMSE/AIC with r>0.99 across all conditions.Higher temperature and air velocity significantly reduced drying time during the decreasing-rate period,with no constantrate stage observed.On average,solar input supplied the large majority of the thermal demand,while the auxiliary heater compensated short irradiance drops to maintain setpoints.These findings provide a reproducible dataset and a modelling benchmark for M.vulgare leaves,and they support energy-aware design of hybrid solar dryers formedicinal plants in sun-rich regions.
基金The authors gratefully acknowledge the financial support from the National Natural Science Foundation of China(11004049)Science and Technology Innovation Team of Henan University of Science and Technology.
文摘In order to improve the heat and mass transfer process in hot-air drying,power ultrasound was coupled directly to hot-air drying of fresh carrot slices.The effects of ultrasonic power,radiation distance,hot air velocity and temperature on drying characteristics were studied.In addition,the Page equation was used to fit the ultrasound assisted hot-air drying process of the carrot slices.The results showed that the drying rate of carrot slices increased with the increase of ultrasound power and the decrease of radiation distance.Power ultrasound had a greater enhancement on hot-air drying at lower air velocity(0.5 m/s)and temperature(40ºC),especially at the middle and later periods(controlled by internal diffusion).The drying time of carrot slices using ultrasound assisted hot-air drying was shortened by 37.5%compared to that using hot-air drying at the condition with power of 150 W,radiation distance of 15 cm,air velocity of 1.0 m/s and temperature of 40ºC.All test indicators of the model meet the accuracy requirements,which show that the model can better fit the experimental values.
基金supported by the Shanghai Municipal Agricultural Commission, China (2016NY001)
文摘The drying characteristics,physico-chemical and functional properties,as well as starch digestibility,of purple potato slices dried using different methods(such as,vacuum freeze-drying,VFD;hot-air drying,HAD;air-impingement jet drying,AIJD;and far-infrared assisted heat-pump drying,FIHPD)were investigated.Drying rate was the highest(3.0 g 100 g^-1 min^-1)using AIJD,followed by FIHPD and HAD,and the rate of VFD was the lowest one(0.3 g 100 g^-1 min^-1).Drying data were fitted to 12 thin-layer drying models,with the Midilli model giving the best predictions.Moreover,AIJD showed higher diffusivity(5.5×10^-10 m^2 s^–1)and energy efficiency(55 J g^-1)than any other drying method used in this study.With reference to the samples dried by VFD,the starch granules of the samples obtained by HAD,FIHPD,and AIJD exhibited different extent of disruption,which significantly increased their water absorption capacity,swelling power,and in vitro digestibility,but decreased the peak viscosity.The sample resulting from AIJD had the greatest water absorption capacity(7.9 g g^-1)and solubility(21.6%),but the smallest syneresis rate(48%).Good correlation coefficients(R^2>0.98)implied that the pseudofirst order kinetic model adequately described the rate and extent of starch digestion of dried potato flours.Samples from AIJD and FIHPD showed the highest digestibility percentages,reaching to 72.4 and 72.5%.Based on the drying rate,specific energy consumption,functional properties and digestibility,AIJD appeared to be quite effective and suitable to be transferred on the industry scale.
文摘Exploring new drying technology can help to deal with the challenge of better preservation of rhizome medicinal materials in the traditional Chinese medicine industry.In current work,combined infrared and hot-air drying(IR-HAD)was employed to Panax notoginseng roots and its effect on drying kinetics,energy efficiency and quality,i.e.,rehydration ratio(RR),color parameters(L^(*),a^(*),b^(*)),total color difference(ΔE),Panax notoginseng saponins(PNS)content,and ginsenosides content(R_(1),R^(g1),R_(e),R_(d),R_(b1))were evaluated.Hot air drying(HAD)was used as the control.Results showed that the increase in drying temperature significantly shortened drying time and reduced energy consumption.The shortest drying time of 43.0 h and lowest specific energy consumption of 15.9 kW·h/(kg-water)were obtained by IR-HAD at 55°C.The decrease of radiation distance and the increase of radiation power led to the shortening of drying time.However,high drying temperature resulted in largeΔE values,large collapse structure,and RR of samples.The drying time of Panax notoginseng roots dried by IR-HAD at a drying temperature of 50°C was shorter(15.5%)than HAD dried at the same drying temperature.The contents of R_(1),R_(g1),R_(e),R_(b1),and PNS were higher when the samples were dried by IR-HAD than those dried by HAD at the same temperature of 50°C.Moreover,the IR-HAD dried samples shortened 15.5%drying time and saved 22.1%energy consumption compared with HAD.Therefore,the optimal process condition was Panax notoginseng roots under IR-HAD at drying temperature of 50°C,radiation distance of 12 cm and radiation power of 1350 W,which can shorten drying time,maintain high ginsenosides contents and satisfactory apparent qualities.
文摘Characteristics of cassava drying were investigated by using a microwave hot-air drying system. Two waveguides were installed on a single plane of the microwave cavity. The drying experiments were carried out at two levels of sample surface temperature set-points, 70℃ and 80℃respectively. Cassava (Rayong-9) with 2.5 kg weight and 61% moisture content on wet basis was dried in the dryer for about 300 - 340 minutes until the final values of moisture content of about 20% db were achieved. It was found that the drying time decreased with an increase in sample-surface temperature set point. Approximately 87% of the moisture was removed during the drying period. It was found that there was a rapid decrease in moisture ratio values followed by the gradual decline period in all experiments. With regard to drying kinetics, 5 commonly used mathematical models were examined with the experimental data. It was found that Page’s and diffusion models provided a good agreement between the experimental and predicted moisture ratio values for all temperature set-points. The regression results indicated that highest values of coefficient of determination and adjusted coefficient of determination as well as lowest value of standard error of estimation were reported for the case of Page’s model at 80℃?temperature set-point.
基金Supported by the Ministry of Agriculture and Agro-Based Industry(MOA),Malaysia(NER30001)
文摘The drying kinetics of Roselle （Hibiscus sabdariffa L） of variety Terengganu （UMKL-1） and the quality attribution of Roselle were studied. The experiments were conducted using four different drying methods, including solar greenhouse drying （SD）, solar greenhouse with intermittent heat pump drying （SIHP）, hot air drying （HA） and heat pump drying （HP）. Among the four drying methods, HP achieved the highest drying rate at a range from 0.054 g H20-（g DM）-1. rain-1 to 0.212 g H20-（g DM）-1. rain 1 while SD had the lowest drying rate, measured at 0.042 g H2O. （g DM） 1.min- 1. The analysis on colour kinetics revealed that there is no significant colour loss （p 〉 0.05） observed from HP＇s dried Roselle. Greater amount of flavonoid compounds i.e. protocatechuic acid was found in SD and SIHP dried finished product whereas HP＇s dried Roselle contains higher percentage of catechin as compared to other drying methods.
文摘Though several maize varieties have been developed and introduced over the years in Ghana, farmers still face challenges of access to quality seed maize. Among the major constraint is lack of proper drying systems to guarantee quality of seed produced. As in most parts of Africa, drying of maize in the open, on bare ground along shoulders of roads is still a common practice in Ghana. In this study, a 5-tonne capacity hybrid solar biomass dryer was developed for drying maize for seed and food/feed in Ghana. Effect of air temperature in the dryer on the physiological quality and germination of maize kernels was investigated. Maize grains were dried in the open sun simulating farmers practice and using the dryer at 4 varying levels (L1, L2, L3 and L4) with corresponding heights (0.6 m, 1.2 m, 1.8 m and 2.4 m, respectively) from the ground. Harvested maize at 22.8% moisture content was dried at the varying levels until reaching the final desired moisture content of 12.8% ± 0.2% (wb). Results showed that, air temperatures in the dryer increased in accordance with height with lowest mean temperature of 44.4°C ± 4.6°C recorded at L1 and mean maximum of 52.8°C ± 5.4°C at L4. Drying temperatures recorded at L1 - L3 and ambient had no significant effect (p < 0.05) on kernel damage and viability. Drying conditions at L1-L3 were considered optimum (<50°C) for kernel drying compared to the topmost tray, L4. Kernel stress crack index (multiple and checked) was therefore reduced on average by 14% while kernel germination increased by 33%. This satisfies the dryer’s potential to be used for commercial drying of maize grains for seed production for smallholder farmers in Ghana.
基金the University of Djillali Bounaama Khemis Miliana,Algeria for this study,cnepru(A16N01UN440120150002)Punit Kohli and Nathalie Becerra acknowledge NSF(CHE-0748676 and CHE-0959568),NIH(GM 106364 and GM 080711)Office of Sponsored Project Administration(OSPA)at SIUC for partial funding.Arosha Umagiliyage,doctoral student of Plant,Soil and Agricultural Systems,SIU provided help on freeze drying of oilseed samples.
文摘A modelling study was performed to solve the heat and mass transfer problems between grain and the ambient air encountered during drying by microwave assisted hot-air dryer,under low microwave(MW)density of 0.2 W/g.Canola(Brassica napus),soybean(Glycine max)and corn(Zea mays)seeds were chosen due to their inherent high oil content.Scanning electron microscopy(SEM)was used to study the effect of drying conditions on the structural characteristics of these oilseeds.A mathematical model was adapted to simulate drying of one seed of canola,soybean and corn.The process of water transfer was modelled based on the effect of vapour pressure on the water molecules inside the seed.It was observed that when the difference between the vapour pressure inside the grain and the surrounding air was higher than,the drying rate increased which led to cracks in the grain.Results showed that the drying rate decreased when the temperature of air inside the cavity of the microwave increased for all the oilseeds studied,because of the reduced differential vapour pressure between the grain and the ambient air.On the other hand,the drying rate increased if the temperature of the inlet air was reduced because the difference between the two pressures increased.It was concluded that by controlling the ambient air,the grains could be protected against popping and cracking because of lower vapour pressure differential during MW assisted hot-air drying.
文摘Hydric properties evolution during drying differs from one product to another and has been the subject of various studies due to its crucial importance in modeling the drying process. The variation of these parameters in the solid matrix and in time during the drying of Spirulina platensis has not known an advanced understanding. The objective of this study was to evaluate the evolution of the water content profile, the mass flow, the concentration gradient and the diffusion coefficient during the drying of Spirulina platensis taking into account the shrinkage. Modeling and experimental analysis (at 50°C and HR = 6%) by the cutting method a cylinder 20 mm in diameter and 40 mm thick were carried. The water content profiles of two different products grown in semi-industrial farms from Burkina Faso and France with initial water contents respectively of the range from 2.73 kgw/kgdb and 3.12 kgw/kgdb were determined. These profiles have been adjusted by a polynomial function. Identical water behavior is observed regardless of the origin of the samples. Water distribution is heterogeneous. Mass flow and concentration gradient are greater at the edge than inside the product. The water transport coefficient, ranging from 1.70 × 10?10 to 94 × 10?10 m2/s, is determined from a linear approach.
文摘本文采用电熔炉冶炼低品位DRI,开展百公斤级扩大化试验,探索低品位DRI电熔炉冶炼特性,包括渣铁分离效果、铁水渗碳效果、铁收得率等,并利用设计软件计算吨铁电耗、煤耗等指标。试验结果表明,DRI球由于具有团疏松多孔的结构,在熔炼过程中始终漂浮在熔池上方;在二次电压120 V下,电极始终为浸没式操作,不能实现刷弧或明弧操作。通过从顶部加入无烟煤和DRI的混合物料可以实现良好的铁还原和铁水渗碳效果,铁水含碳量平均值为3.09%。在低碱度渣型和高渣率下,所得渣Fe O含量平均值为1.47%,铁收得率平均值高达98.84%。低品位DRI热态入炉生产液体热金属所需的理论吨铁电耗为511 k W·h/t,而冷态入炉的理论吨铁电耗为770 k W·h/t,热态DRI直接入炉冶炼可以节能约50%。
文摘Industrially produced sodium water glasses were dried in climates with controlled temperature and humidity to transparent amorphous water containing sodium silicate materials. The water glasses had molar SiO2:Na2O ratios of 2.2, 3.3 and 3.9 and were dried up to 84 days at temperatures between 40°C and 95°C and water vapour pressures between 5 and 40 kPa. The materials approached final water concentrations which are equilibrium values and are controlled by the water vapour pressure of the atmosphere and the microstructure of the solids. The microstructure of the dried water glasses was characterized by atomic force microscopy. It has a nanosized substructure built up by the silicate colloids of the educts but deformed by capillary forces. In the final drying equilibrium, the water vapour pressure of the atmosphere in the drying cabinet is equal to the reduced vapour pressure of the capillary system built up by the silicate colloids. Their size scale can be explained by the deformation of colloidal aggregates due to capillary forces.
基金the support of the National Natural Science Foundation of China(No.42107247)the National Key Research and Development Project(No.2022YFD1901605)+1 种基金the Natural Science Foundation of Sichuan Province(Nos.2025YFHZ0142 and 2024NSFSC0800)the Tobacco Science Foundation of Sichuan Province(No.SCYC202407)。
文摘Soil microorganisms and labile soil organic carbon(SOC)fractions are essential factors affecting greenhouse gas(GHG)emissions in paddy fields.However,the effects of labile SOC fractions and microorganisms on GHG emissions from flooding to drying after organic fertilizer replacing for chemical fertilizer remain unclear.Here,a long-term experiment was conducted with four treatments:chemical fertilization only(control),organic fertilizer substituting 25%of chemical N fertilizer(NM1),50%of chemical N fertilizer(NM2),and NM2combined with crop straw(NMS).GHG emissions were monitored,and soil samples were collected to determine labile SOC fractions and microorganisms.Results revealed the GHG emissions in the NM2 significantly increased by 196.88%from flooding to drying,mainly due to the higher CO_(2) emissions.The GHG emissions per kg of C input in NMS was the lowest with the value of 9.17.From flooding to drying,organic fertilizer application significantly increased the readily oxidizable organic carbon(ROC)contents and C lability;the NM2 and NMS dramatically increased the SOC and non-readily oxidizable organic carbon(NROC).The bacterial communities showed significant differences among different treatments in the flooding,while the significant difference was only found between the NMS and other treatments in the drying.From flooding to drying,changing soil moisture conditions causes C fractions and microbial communities to jointly affect carbon emissions,and the NMS promoted carbon sequestration and mitigated GHG emissions.Our findings highlight the importance of the labile SOC fractions and microorganisms linked to GHG emissions in paddy fields.
文摘This present work solves the problem of initial shape influence on transfer during convective drying. A characteristic dimension is found for the cubic, cylindrical and spherical-shaped samples of the sweet potato. This characteristic dimension corresponds to the diameter D for the sphere, to the edge a for the cube and the diameter = height D = H for the cylinder. Unlike the sphere where this characteristic dimension is perfect, the cubic and cylindrical shapes have space factors which are, among other things, angles and borders. By fixing the same characteristic dimensions, we end up with overlapping curves, showing identical and uniform transfers.
文摘CeO_(2) based semiconductor are widely used in solar-driven photothermal catalytic dry reforming of methane(DRM)reaction,but still suffer from low activity and low light utilization efficiency.This study developed graphite-CeO_(2) interfaces to enhance solar-driven photothermal catalytic DRM.Compared with carbon nanotubes-modified CeO_(2)(CeO_(2)-CNT),graphite-modified CeO_(2)(CeO_(2)-GRA)constructed graphite-CeO_(2) interfaces with distortion in CeO_(2),leading to the formation abundant oxygen vacancies.These graphite-CeO_(2) interfaces with oxygen vacancies enhanced optical absorption and promoted the generation and separation of photogenerated carriers.The high endothermic capacity of graphite elevated the catalyst surface temperature from 592.1−691.3℃,boosting light-to-thermal conversion.The synergy between photogenerated carriers and localized heat enabled Ni/CeO_(2)-GRA to achieve a CO production rate of 9985.6 mmol/(g·h)(vs 7192.4 mmol/(g·h)for Ni/CeO_(2))and a light-to-fuel efficiency of 21.8%(vs 13.8%for Ni/CeO_(2)).This work provides insights for designing graphite-semiconductor interfaces to advance photothermal catalytic efficiency.
基金financially supported by the Natural Science Foundation of Hunan Province(project No.2024JJ8037:https://kjt.hunan.gov.cn/kjt/xxgk/tzgg/tzgg_1/202403/t20240311_33144606.html,accessed on 27 October 2025)。
文摘This study evaluated corn kernel drying performance and quality changes using hot air drying(HAD)and infrared drying(ID)across temperatures ranging from 55℃ to 80℃.Optimal drying parameters were determined by using the entropy weight method,with drying time,specific energy consumption,damage rate,fatty acids,starch,polyphenols,and flavonoids as indicators.Results demonstrated that ID significantly outperformed HAD,achieving drying times up to 20%shorter and reducing specific energy consumption and kernel damage by up to 79.3%and 66.7%,respectively,while also better preserving quality attributes.Both methods exhibited drying profiles characterized by acceleration,constant,and falling rate periods,although the constant rate phase was distinctly observable only at lower temperatures.The effective moisture diffusivity under ID was consistently higher than that under HAD,with a maximum increase of 20.4%.The optimal drying conditions were HAD at 65℃ and ID at 80℃.A BP model was also developed and it showed better predictive performance and adaptability than classical mathematical models.
