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Sample records for microwave convective drying

  1. Soybean drying characteristics in microwave rotary dryer with forced convection

    Institute of Scientific and Technical Information of China (English)

    Ruifang WANG; Zhanyong LI; Yanhua LI; Jingsheng YE

    2009-01-01

    A new hybrid drying technique by combining microwave and forced convection drying within a rotary drum, i.e., microwave rotary drying, was developed with the purpose to improve the uniformity of microwave drying. In a laboratory microwave rotary dryer, rewetted soybean was utilized as experimental material to study the effects of drum rotating speed, ventilation flow rate, and specific microwave power on the drying kinetics and cracking ratio of soybean. It was found that, with rotation, the cracking ratio can be lowered but without distinct improvement in the drying rate. Increasing ventilation flow rate and specific microwave power can improve the drying rate, but the cracking ratio also increases as a negative result. The cracking ratio lower than 10% can be attained for ventilation flow rate lower than 2.0 m3·h-1 or specific microwave energy lower than 0.4 kW·kg-1 in the present experiments.

  2. Drying and color characteristics of coriander foliage using convective thin-layer and microwave drying.

    Science.gov (United States)

    Shaw, Mark; Meda, Venkatesh; Tabil, Lope; Opoku, Anthony

    2007-01-01

    Heat sensitive properties (aromatic, medicinal, color) provide herbs and spices with their high market value. In order to prevent extreme loss of heat sensitive properties when drying herbs, they are normally dried at low temperatures for longer periods of time to preserve these sensory properties. High energy consumption often results from drying herbs over a long period. Coriander (Coriandrum sativum L., Umbelliferae) was dehydrated in two different drying units (thin layer convection and microwave dryers) in order to compare the drying and final product quality (color) characteristics. Microwave drying of the coriander foliage was faster than convective drying. The entire drying process took place in the falling rate period for both microwave and convective dried samples. The drying rate for the microwave dried samples ranged from 42.3 to 48.2% db/min and that of the convective dried samples ranged from 7.1 to 12.5% db/min. The fresh sample color had the lowest L value at 26.83 with higher L values for all dried samples. The results show that convective thin layer dried coriander samples exhibited a significantly greater color change than microwave dried coriander samples. The color change index values for the microwave dried samples ranged from 2.67 to 3.27 and that of the convective dried samples varied from 4.59 to 6.58.

  3. Microwave Assisted Hot Air Convective Dehydration of Fish Slice: Drying Characteristics, Energy Aspects and Colour Assessment

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    Mohd Rozainee Taib

    2011-01-01

    Full Text Available Dried fish is commonly produced by convective hot air drying. Microwave technology was presented in this paper to improve both process and product quality. Catfish (order Siluriformes slices were dehydrated in a microwave assisted hot air convective dehydration (MWHA system to investigate the effects of microwave power and hot air temperature on drying time, dehydration behaviour, energy consumption and colour of dried fish. Three different microwave power outputs namely medium (373 W, medium low (217 W and low (91 W combined with convective hot air temperature of 40°C, 70°C and 130°C accordingly were employed in the drying experiments. Results show that microwave accelerates drying time up to 120 folds faster compared to drying with hot air convective alone. It was also noted that increasing the hot air temperature was not as significant as increasing the microwave power in reducing the drying time. Experiments show that drying time was reduced about 75 % when an increase of microwave power from low (91 W to medium mode (373 W combining with convective hot air. However, drying with microwave alone required longer drying time. Energy consumption analysis shows that microwave assisted drying process requires less energy usage. Drying fish with microwave assisted hot air dehydration treatment make the colour brighter, shifting towards red and yellow.

  4. Thin-layer modeling of convective and microwave-convective drying of oyster mushroom (Pleurotus ostreatus).

    Science.gov (United States)

    Bhattacharya, Mrittika; Srivastav, Prem Prakash; Mishra, Hari Niwas

    2015-04-01

    Oyster mushroom samples were dried under selected convective, microwave-convective drying conditions in a recirculatory hot-air dryer and microwave assisted hot-air dryer (2.45 GHz, 1.5 kW) respectively. Only falling rate period and no constant rate period, was exhibited in both the drying technique. The experimental moisture loss data were fitted to selected semi-theoretical thin-layer drying equations. The mathematical models were compared according to three statistical parameters, i.e. correlation coefficient, reduced chi-square and residual mean sum of squares. Among all the models, Midilli et al. model was found to have the best fit as suggested by 0.99 of square correlation coefficient, 0.000043 of reduced-chi square and 0.0023 of residual sum of square. The highest effective moisture diffusivity varying from 10.16 × 10(-8) to 16.18 × 10(-8) m(2)/s over the temperature range was observed in microwave-convective drying at an air velocity of 1.5 m/s and the activation energy was calculated to be 16.95 kJ/mol. The above findings can aid to select the most suitable operating conditions, so as to design drying equipment accordingly.

  5. Modelling of intermittent microwave convective drying: parameter sensitivity

    Directory of Open Access Journals (Sweden)

    Zhang Zhijun

    2017-06-01

    Full Text Available The reliability of the predictions of a mathematical model is a prerequisite to its utilization. A multiphase porous media model of intermittent microwave convective drying is developed based on the literature. The model considers the liquid water, gas and solid matrix inside of food. The model is simulated by COMSOL software. Its sensitivity parameter is analysed by changing the parameter values by ±20%, with the exception of several parameters. The sensitivity analysis of the process of the microwave power level shows that each parameter: ambient temperature, effective gas diffusivity, and evaporation rate constant, has significant effects on the process. However, the surface mass, heat transfer coefficient, relative and intrinsic permeability of the gas, and capillary diffusivity of water do not have a considerable effect. The evaporation rate constant has minimal parameter sensitivity with a ±20% value change, until it is changed 10-fold. In all results, the temperature and vapour pressure curves show the same trends as the moisture content curve. However, the water saturation at the medium surface and in the centre show different results. Vapour transfer is the major mass transfer phenomenon that affects the drying process.

  6. Modelling of intermittent microwave convective drying: parameter sensitivity

    Science.gov (United States)

    Zhang, Zhijun; Qin, Wenchao; Shi, Bin; Gao, Jingxin; Zhang, Shiwei

    2017-06-01

    The reliability of the predictions of a mathematical model is a prerequisite to its utilization. A multiphase porous media model of intermittent microwave convective drying is developed based on the literature. The model considers the liquid water, gas and solid matrix inside of food. The model is simulated by COMSOL software. Its sensitivity parameter is analysed by changing the parameter values by ±20%, with the exception of several parameters. The sensitivity analysis of the process of the microwave power level shows that each parameter: ambient temperature, effective gas diffusivity, and evaporation rate constant, has significant effects on the process. However, the surface mass, heat transfer coefficient, relative and intrinsic permeability of the gas, and capillary diffusivity of water do not have a considerable effect. The evaporation rate constant has minimal parameter sensitivity with a ±20% value change, until it is changed 10-fold. In all results, the temperature and vapour pressure curves show the same trends as the moisture content curve. However, the water saturation at the medium surface and in the centre show different results. Vapour transfer is the major mass transfer phenomenon that affects the drying process.

  7. Mathematical Modeling of Microwave-Assisted Convective Heating and Drying of Grapes

    Science.gov (United States)

    This research studied the processing performance and product quality of Thompson seedless grapes dried using microwave-assisted convective hot air drying as well as the effect of blanching and dipping pretreatments. Two pretreatment methods were compared, dipping into 2% ethyl oleate (V/V) and 5% p...

  8. Convective and Microwave Dryings of Raffia Fruit: Modeling and Effects on Color and Hardness

    Directory of Open Access Journals (Sweden)

    Raymond G. Elenga

    2013-08-01

    Full Text Available Biodiversity conservation with the improvement of living conditions requires the efficiency in use of all resources. For instance, A better exploitation of the endemic oleaginous plants of the tropical forests should mitigate the extension of the palm plantations which is one of the greatest threats of the biodiversity in this area. The raffia palm fruit contains edible oil richer in nutrients than oil palm. However, oil raffia production remains weak because entirely based on empirical methods. This study compares the effect of convective and microwave dryings on the drying kinetics, color and hardness of the raffia pulp. Moreover, four drying kinetics models and the concept of characteristic drying curve have been tested for this pulp. To this end, six drying temperatures and four power levels have been used. The results show that the drying time passes from 10 h at 40°C to 3 h at 90°C and from 30 min at 140 W to 5 min at 560 W. The results could be represented by one characteristic drying curve. Among the four models used, the Modified Khazaei model is the best. The coefficient of effective diffusivity varies from 0.63×10-10 to 3.8×10-10 m2/s for convective drying and from 10.05×10-10 to 88.5×10-10 m2/s for microwave. The activation energy is 34±2 KJ/mol. It is found that convective drying degrades the color and increases the hardness of the pulp more than microwave drying.

  9. Energy analyses and drying kinetics of chamomile leaves in microwave-convective dryer

    Directory of Open Access Journals (Sweden)

    Ali Motevali

    2016-06-01

    Full Text Available Drying characteristics and energy aspects as well as mathematical modeling of thin layer drying kinetics of chamomile in a microwave-convective dryer are reported in this article. Drying experiments were carried out at 8 microwave power levels (200–900 W, air temperature of 50 °C, and air velocity of 0.5 m/s. Increasing the microwave output power from 200 to 900 W, decreased the drying time from 40 to 10 min. The drying process took place in the falling rate period. The Midilli et al. model showed the best fit to the experimental drying data. Moisture diffusivity values increase with decreasing moisture content down to 1.70 (kg water kg−1 dry matter but decrease with a further decrease in moisture content from 1.72 to 0.96 (kg water kg−1 dry matter. The average values of Deff increased with microwave power from 5.46 to 39.63 × 10−8 (m2 s−1. Energy consumption increased and energy efficiency decreased with moisture content of chamomile samples. Average specific energy consumption, energy efficiency and energy loss varied in the range 18.93–28.15 MJ kg−1 water, 8.25–13.07% and 16.79–26.01 MJ kg−1 water, respectively, while the best energy results were obtained at 400 W, 50 °C and 0.5 m s−1.

  10. Microwave Drying of Moist Coals

    Science.gov (United States)

    Salomatov, Vl. V.; Karelin, V. A.; Sladkov, S. O.; Salomatov, Vas. V.

    2017-03-01

    Physical principles and examples of practical implementation of drying large bodies of coal by microwave radiation are considered. It is shown that energy consumption in microwave drying of brown coals decreases to 1.5-1.8 (kW·h)/ kg as compared with traditional types of drying, for which the expenditures of energy amount to 3.0 (kW·h)/kg. In using microwave drying, the technological time of drying decreases to 4 h, whereas the time of convective drying, with other things being equal, comes to 8-20 h. Parallel with microwave radiation drying, grinding of a fuel takes place, as well as entrainment of such toxic and ecologically harmful elements as mercury, chlorine, phosphorus, sulfur, and nitrogen. An analysis of the prospects of using a microwave energy for drying coal fuel has shown that microwave radiation makes it possible to considerably economize in energy, increase explosional safety, improve the ecological situation, and reduce the metal content and overall dimensions of the equipment.

  11. THE INFLUENCE OF MICROWAVE HEATING OF FRESHLY HARVESTED SUNFLOWER SEEDS BEFORE CONVECTIVE DRYING ON OUTPUT AND QUALITY OF OIL

    Directory of Open Access Journals (Sweden)

    Mustafayev S. K.

    2014-03-01

    Full Text Available This article studies the influence of various methods of thermal, acoustic and electromagnetic exposure on free lipid content, acid and peroxidation number of oil in sunflower seeds during their after harvesting ripening. We have investigated the influence of traditional and microwave heating on lipase activity of seeds. We have also founded the most efficient conditions for the rate and the temperature of microwave heating of freshly harvested sunflower seeds and determined their effect on the rate of drying

  12. ENVIRONMENTAL ASPECTS OF THE INTENSIFICATION CONVECTIVE DRYING

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    A. M. Gavrilenkov

    2012-01-01

    Full Text Available Identified and analyzed the relationship of the intensity convective drying and air pollution emissions of heat. The ways to reduce the thermal pollution of the atmosphere at convective drying.

  13. THE INFLUENCE OF MICROWAVE HEATING OF FRESHLY HARVESTED SUNFLOWER SEEDS BEFORE CONVECTIVE DRYING ON OUTPUT AND QUALITY OF OIL

    OpenAIRE

    Mustafayev S. K.; Smychagin E. O.

    2014-01-01

    This article studies the influence of various methods of thermal, acoustic and electromagnetic exposure on free lipid content, acid and peroxidation number of oil in sunflower seeds during their after harvesting ripening. We have investigated the influence of traditional and microwave heating on lipase activity of seeds. We have also founded the most efficient conditions for the rate and the temperature of microwave heating of freshly harvested sunflower seeds and determined their effect on t...

  14. Convective drying of sludge cake

    Science.gov (United States)

    Chen, Jianbo; Peng, Xiaofeng; Xue, Yuan; Lee, Duujong; Chu, Chingping

    2002-08-01

    This paper presented an experimental study on convective drying of waste water sludge collected from Beijing GaoBeiDian Sewage Treatment Plant, particularly on the correlation between the observed shrinkage dynamics of sludge cake and the drying curve. During the initial stage of drying the process resembles to that of a particulate bed, in which moisture diffuses and evaporates at the upper surface. Conventional drying theory assuming a diffusion-evaporating front interprets this period of drying. Consequently, owing to the very large shrinkage ratio of the dried cake, cracks emerges and propagates on and within the cake body, whence inducing evaporating channel that facilitates the water removal. This occurrence compensates the reduction of surface area for evaporation, whence extending the constant-rate period during the test. Afterwards, the cracks meet with each other and form isolated cake piles, while the subsequent drying occur mainly within these piles and the conventional theory fails. The transition between the drying on a plain cake layer and that on the isolated piles demonstrates the need to adopt distinct descriptions on these two regimes of drying for the sludge cake.

  15. Specific energy consumption in microwave drying of garlic cloves

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, G.P. [Department of Processing and Food Engineering, College of Technology and Agricultural Engineering, Udaipur 313 001, Rajasthan (India); Prasad, Suresh [Agricultural and Food Engineering Department, Indian Institute of Technology, Kharagpur 721 302 (India)

    2006-09-15

    The convective and microwave-convective drying of garlic cloves was carried out in a laboratory scale microwave dryer, which was developed for this purpose. The specific energy consumption involved in the two drying processes was estimated from the energy supplied to the various components of the dryer during the drying period. The specific energy consumption was computed by dividing the total energy supplied by amount of water removed during the drying process. The specific energy consumption in convective drying of garlic cloves at 70{sup o}C temperature and 1.0m/s air velocity was estimated as 85.45MJ/kg of water evaporated. The increase in air velocity increased the energy consumption. The specific energy consumption at 40W of microwave power output, 70{sup o}C air temperature and 1.0m/s air velocity was 26.32MJ/kg of water removed, resulting in about a 70% energy saving as compared to convective drying processes. The drying time increased with increase in air velocity in microwave-convective drying process; a trend reverse to what was observed in convective drying process of garlic cloves. (author)

  16. Mechanism of microwave sterilization in the dry state.

    Science.gov (United States)

    Jeng, D K; Kaczmarek, K A; Woodworth, A G; Balasky, G

    1987-01-01

    With an automated computerized temperature control and a specialized temperature measurement system, dry spores of Bacillus subtilis subsp. niger were treated with heat simultaneously in a convection dry-heat oven and a microwave oven. The temperature of the microwave oven was monitored such that the temperature profiles of the spore samples in both heat sources were nearly identical. Under these experimental conditions, we unequivocally demonstrated that the mechanism of sporicidal action of the microwaves was caused solely by thermal effects. Nonthermal effects were not significant in a dry microwave sterilization process. Both heating systems showed that a dwelling time of more than 45 min was required to sterilize 10(5) inoculated spores in dry glass vials at 137 degrees C. The D values of both heating systems were 88, 14, and 7 min at 117, 130, and 137 degrees C, respectively. The Z value was estimated to be 18 degrees C. PMID:3118807

  17. Acousto-Convective Drying of Pine Nuts

    Science.gov (United States)

    Zhilin, A. A.; Fedorov, A. V.

    2014-07-01

    An experimental investigation of the process of drying pine nut grains has been carried out by three methods: acousto-convective, thermoconvective, and thermal. A qualitative and a quantitative comparison of the dynamics of the processes of moisture extraction from the nut grains for the considered drying methods have been made. To elucidate the mechanism of moisture extraction from the pine nut grains, we carried out a separate investigation of the process of drying the nut shell and the kernel. The obtained experimental data on the acousto-convective drying of nuts are well described by the relaxation model, the data on the thermoconvective drying are well described by the bilinear law, and the data on the thermal drying are well described by the combined method consisting of three time steps characterized by different kinetic regimes of drying.

  18. Study of the microwave vacuum drying process for a granulated product

    Directory of Open Access Journals (Sweden)

    M. N. Berteli

    2009-06-01

    Full Text Available The objectives of this work were to study and evaluate the process of drying a pharmaceutical granule from 21% to 3 % (d.b. moisture, also determining the power absorbed by the product, using a microwave assisted vacuum dryer with two absolute pressures: 50 and 75 mbar. A specific objective was to compare the drying kinetics of the microwave assisted vacuum process (MAVP with two other drying processes, one using hot air convection and the other combining microwaves with hot air convection. The results of such a study showed that the drying kinetics were not affected by the vacuum levels, whereas the absorbed microwave power was higher for smaller vacuum levels. It was also observed that the samples obtained by the microwave assisted vacuum process, when submitted to compression, complied with the required specifications. The drying kinetics of the MAVP showed the shortest drying times when compared to the other drying processes.

  19. Convection in Drying and Freezing Ground

    CERN Document Server

    Faizal, Mir

    2012-01-01

    In this paper we analyse the drying of a soil composed of particles, water and solute impurities, and study the occurrence of convective instabilities during evaporation. We find that the main driving force for instability is the formation of a concentration gradient at the soil surface due to the evaporation of water. A similar phenomenon may occur during the thawing of frozen ground in Arctic regions.

  20. Kinetics of microwave drying of apples

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    G. V. Kalashnikov

    2012-01-01

    Full Text Available The influence of main technological parameters was studied as a result of research of microwave drying of apples and the analysis of kinetic regularity of the process was performed.

  1. Intermittent Microwave Drying of Wheat (Triticum aestivum L.) Seeds

    OpenAIRE

    Yan Li; Tao Zhang; Chenglai Wu; Chunqing Zhang

    2014-01-01

    The purpose of present study was to characterize the intermittent microwave drying of wheat seeds. Results revealed that microwave on time percentage (MOTP) and initial moisture content were the main parameters which influenced the intermittent microwave drying rate and the germination capacity of dried seeds. Best intermittent microwave drying (power: 800 W; seed sample weight: 100 g, microwave on time in each cycle: 32 s) without significantly decreasing the germination rate was...

  2. Microwave emission from dry and wet snow

    Science.gov (United States)

    Chang, T. C.; Gloersen, P.

    1975-01-01

    A microscopic model was developed to study the microwave emission from snow. In this model, the individual snow particles are considered to be the scattering centers. Mie scattering theory for spherical particles is then used to compute the volume scattering and extinction coefficients of the closely packed scattering spheres, which are assumed not to interact coherently. The results of the computations show significant volume scattering effects in the microwave region which result in low observed emissivities from cold, dry snow. In the case of wet snow, the microwave emissivities are increased considerably, in agreement with earlier experimental observations in which the brightness temperatures have increased significantly at the onset of melting.

  3. Microwave-Osmotic/Microwave-Vacuum Drying of Whole Cranberries: Comparison with Other Methods.

    Science.gov (United States)

    Wray, Derek; Ramaswamy, Hosahalli S

    2015-12-01

    A novel drying method for frozen-thawed whole cranberries was developed by combining microwave osmotic dehydration under continuous flow medium spray (MWODS) conditions with microwave vacuum finish-drying. A central composite rotatable design was used to vary temperature (33 to 67 °C), osmotic solution concentration (33 to 67 °B), contact time (5 to 55 min), and flow rate (2.1 to 4.1 L/min) in order to the determine the effects of MWODS input parameters on quality of the dried berry. Quality indices monitored included colorimetric and textural data in addition to anthocyanin retention and cellular structure. Overall it was found that the MWODS-MWV process was able to produce dried cranberries with quality comparable to freeze dried samples in much shorter time. Additionally, cranberries dried via the novel process exhibited much higher quality than those dried via either vacuum or convective air drying in terms of color, anthocyanin content, and cellular structure.

  4. Fast Drying of Agriculture Commodities by Using Microwave

    Science.gov (United States)

    Ode Ngkoimani, La; Megawati; Purwana Saputra, Gde; Cahyono, Edi; Aripin, Haji; Gde Suastika, Komang; Nyoman Sudiana, I.

    2017-05-01

    Some progress has been made and reported previously due to investigate microwave effects to materials. The microwave applications for material processing by using wide range microwave frequencies such as in sintering, chemical reaction, and drying have been performed. Microwave drying is based on a unique volumetric heating mode with electromagnetic radiation at 2,450 MHz. However, the quest for a what a true microwave effect is still plagued with difficulties. This paper provides a experimental and theoretical analysis of drying materials using microwave. For drying experiments, in this investigation, we were using a domestic microwave oven which operated at three power levels for drying chamber. The samples are agriculture commodity collected from local farmers. The experimental results show that microwave accelerate drying in most materials. The experimental data were analyzed by using an available model constructed from fundamental physics by other scholars. The model has been applied to more understanding the behavior of the microwave drying material.

  5. Exergetic simulation of a combined infrared-convective drying process

    Science.gov (United States)

    Aghbashlo, Mortaza

    2016-04-01

    Optimal design and performance of a combined infrared-convective drying system with respect to the energy issue is extremely put through the application of advanced engineering analyses. This article proposes a theoretical approach for exergy analysis of the combined infrared-convective drying process using a simple heat and mass transfer model. The applicability of the developed model to actual drying processes was proved using an illustrative example for a typical food.

  6. Microwave-assisted drying of blueberry (Vaccinium corymbosum L.) fruits: Drying kinetics, polyphenols, anthocyanins, antioxidant capacity, colour and texture.

    Science.gov (United States)

    Zielinska, Magdalena; Michalska, Anna

    2016-12-01

    The aim of the study was to evaluate the effect of hot air convective drying (HACD), microwave vacuum drying (MWVD) and their combination (HACD+MWVD) on the drying kinetics, colour, total polyphenols, anthocyanins antioxidant capacity and texture of frozen/thawed blueberries. Drying resulted in reduction of total polyphenols content and antioxidant capacity (69 and 77%, respectively). The highest content of total polyphenols was noted after HACD at 90°C. Lower air temperature and prolonged exposure to oxygen resulted in greater degradation of polyphenols and antioxidant capacity. Drying processes caused a significant decrease (from 70 to 95%) in the content of anthocyanins. The highest content of anthocyanins and the strongest antioxidant capacity was found in blueberries dried using HACD at 90°C+MWVD. Among drying methods, HACD at 90°C+MWVD satisfied significant requirements for dried fruits i.e. short drying time and improved product quality.

  7. Kinetics and Quality of Microwave-Assisted Drying of Mango (Mangifera indica)

    Science.gov (United States)

    Abano, Ernest Ekow

    2016-01-01

    The effect of microwave-assisted convective air-drying on the drying kinetics and quality of mango was evaluated. Both microwave power and pretreatment time were significant factors but the effect of power was more profound. Increase in microwave power and pretreatment time had a positive effect on drying time. The nonenzymatic browning index of the fresh samples increased from 0.29 to 0.60 while the ascorbic acid content decreased with increase in microwave power and time from 3.84 mg/100g to 1.67 mg/100g. The effective moisture diffusivity varied from 1.45 × 10−9 to 2.13 × 10−9 m2/s for microwave power range of 300-600 W for 2 to 4 minutes of pretreatment. The Arrhenius type power-dependent activation energy was found to be in the range of 8.58–17.48 W/mm. The fitting of commonly used drying models to the drying data showed the Midilli et al. model as the best. Microwave power of 300 W and pretreatment time of 4 minutes emerged as the optimum conditions prior to air-drying at 7°C. At this ideal condition, the energy savings as a result of microwave application was approximately 30%. Therefore, microwave-assisted drying should be considered for improved heat and mass transfer processes during drying to produce dried mangoes with better quality. PMID:26904667

  8. Kinetics and Quality of Microwave-Assisted Drying of Mango (Mangifera indica

    Directory of Open Access Journals (Sweden)

    Ernest Ekow Abano

    2016-01-01

    Full Text Available The effect of microwave-assisted convective air-drying on the drying kinetics and quality of mango was evaluated. Both microwave power and pretreatment time were significant factors but the effect of power was more profound. Increase in microwave power and pretreatment time had a positive effect on drying time. The nonenzymatic browning index of the fresh samples increased from 0.29 to 0.60 while the ascorbic acid content decreased with increase in microwave power and time from 3.84 mg/100g to 1.67 mg/100g. The effective moisture diffusivity varied from 1.45 × 10−9 to 2.13 × 10−9 m2/s for microwave power range of 300-600 W for 2 to 4 minutes of pretreatment. The Arrhenius type power-dependent activation energy was found to be in the range of 8.58–17.48 W/mm. The fitting of commonly used drying models to the drying data showed the Midilli et al. model as the best. Microwave power of 300 W and pretreatment time of 4 minutes emerged as the optimum conditions prior to air-drying at 7°C. At this ideal condition, the energy savings as a result of microwave application was approximately 30%. Therefore, microwave-assisted drying should be considered for improved heat and mass transfer processes during drying to produce dried mangoes with better quality.

  9. Thin layer convection-drying of mushrooms

    Energy Technology Data Exchange (ETDEWEB)

    Pal, U.S.; Chakraverty, A. [Indian Inst. of Tech., Kharagpur (India). Dept. of Agricultural Engineering

    1997-06-01

    Dehydration characteristics of the Oyster Pleurotus variety of mushroom were studied. Both untreated and treated (steam blanching followed by sulphiting and citric acid pretreatment before drying) mushrooms were dried in the thin layer experimental equipment at each of the drying air temperatures of 45, 50 and 60{sup o}C with air velocities of 0.9 and 1.6 m/s. Studies on the equilibrium moisture content (EMC) of both untreated and treated dehydrated mushrooms were performed at different relative humidities ranging from 11.2 to 86.3% at 30{sup o}C. Taking drying time and quality of the dehydrated product into account, a combination of a drying air temperature of 50{sup o}C and an air velocity of 0.9 m/s appears to be suitable for drying of both untreated and treated mushrooms for a good dehydrated product. (author)

  10. Studies on Microwave Heated Drying-rate Equations of Foods

    OpenAIRE

    1990-01-01

    In order to design various microwave heated drying apparatuses, we must take drying-rate equations which are based on simple drying-rate models. In a previous paper (KUBOTA, et al., 1990), we have studied a convenient microwave heated drying instrument, and studied the simple drying-rate equations of potato and so on by using the simple empirical rate equations that have been reported in previous papers (KUBOTA, 1979-1, 1979-2). In this paper, we studied the microwave drying rate of the const...

  11. Mantle Convection in a Microwave Oven: New Perspectives for the Internally Heated Convection

    Science.gov (United States)

    Limare, A.; Fourel, L.; Surducan, E.; Neamtu, C.; Surducan, V.; Vilella, K.; Farnetani, C. G.; Kaminski, E. C.; Jaupart, C. P.

    2015-12-01

    The thermal evolution of silicate planets is primarily controlled by the balance between internal heating - due to radioactive decay - and heat transport by mantle convection. In the Earth, the problem is particularly complex due to the heterogeneous distribution of heat sources in the mantle and the non-linear coupling between this distribution and convective mixing. To investigate the behaviour of such systems, we have developed a new technology based on microwave absorption to study internally-heated convection in the laboratory. This prototype offers the ability to reach the high Rayleigh-Roberts and Prandtl numbers that are relevant for planetary convection. Our experimental results obtained for a uniform distribution of heat sources were compared to numerical calculations reproducing exactly experimental conditions (3D Cartesian geometry and temperature-dependent physical properties), thereby providing the first cross validation of experimental and numerical studies of convection in internally-heated systems. We find that the thermal boundary layer thickness and interior temperature scale with RaH-1/4, where RaH is the Rayleigh-Roberts number, as theoretically predicted by scaling arguments on the dissipation of kinetic energy. Our microwave-based method offers new perspectives for the study of internally-heated convection in heterogeneous systems which have been out of experimental reach until now. We are able to selectively heat specific regions in the convecting layer, through the careful control of the absorption properties of different miscible fluids. This is analogous to convection in the presence of chemical reservoirs with different concentration of long-lived radioactive isotopes. We shall show results for two different cases: the stability of continental lithosphere over a convective fluid and the evolution of a hidden enriched reservoir in the lowermost mantle.

  12. experimental investigation of the effect of microwave drying and ...

    African Journals Online (AJOL)

    Alayande Ibraheem

    Effect of microwave oven drying and reactor temperature has been investigated in this study. Cassava ... sample was water washed to remove excess alkali metal present through hydrolysis, sun dried and ground to obtain a ... and 2050 [1, 2].

  13. Intermittent Microwave Drying of Wheat (Triticum aestivum L. Seeds

    Directory of Open Access Journals (Sweden)

    Yan Li

    2014-02-01

    Full Text Available The purpose of present study was to characterize the intermittent microwave drying of wheat seeds. Results revealed that microwave on time percentage (MOTP and initial moisture content were the main parameters which influenced the intermittent microwave drying rate and the germination capacity of dried seeds. Best intermittent microwave drying (power: 800 W; seed sample weight: 100 g, microwave on time in each cycle: 32 s without significantly decreasing the germination rate was obtained at initial moisture content≤ 20.3% along with 20% MOTP. While, if initial moisture content of seeds was ≤ 16.7%, the seeds can be dried more rapidly using MOTP 30% without affecting germination capacity. The results obtained from this study would provide technical basis to select optimal wheat seed processing and design seed drying equipments.

  14. Controlling mechanisms of moisture diffusion in convective drying of leather

    Science.gov (United States)

    Benmakhlouf, Naima; Azzouz, Soufien; Monzó-Cabrera, Juan; Khdhira, Hechmi; ELCafsi, Afif

    2017-04-01

    Leather manufacturing involves a crucial energy-intensive drying stage in the finishing process to remove its residual moisture. It occurs several times in the tanning course. As it is the target of this paper to depict an experimental way to determine moisture diffusion in the convective drying of leather. The effective diffusion coefficient is estimated by a method derived from Fick's law and by analytic method. The effective diffusion coefficients are obtained from drying tests and the diffusivity behaviour is studied versus the controlling parameter such as the convective airflow temperature. The experiments were conducted at hot air temperatures of 40, 45, 50, 55 and 60 °C and hot air speed of 1 m/s. The hot air temperature had significant effect on the effective moisture diffusivity of the leather sample. The average effective moisture diffusivity in rosehip ranged between 5.87 × 10-11 and 14.48 × 10-11 m2/s for leather at the temperatures studied. Activation energy for convective drying was found to be 38.46 kJ/mol for leather. The obtained results fully confirm the theoretical study in which an exponentially increasing relationship between effective diffusivity and temperature is predicted. The results of this study provide a better understanding of the drying mechanisms and may lead to a series of recommendations for leather drying optimization. It opens the possibility for further investigations on the description of drying conditions.

  15. Controlling mechanisms of moisture diffusion in convective drying of leather

    Science.gov (United States)

    Benmakhlouf, Naima; Azzouz, Soufien; Monzó-Cabrera, Juan; Khdhira, Hechmi; ELCafsi, Afif

    2016-08-01

    Leather manufacturing involves a crucial energy-intensive drying stage in the finishing process to remove its residual moisture. It occurs several times in the tanning course. As it is the target of this paper to depict an experimental way to determine moisture diffusion in the convective drying of leather. The effective diffusion coefficient is estimated by a method derived from Fick's law and by analytic method. The effective diffusion coefficients are obtained from drying tests and the diffusivity behaviour is studied versus the controlling parameter such as the convective airflow temperature. The experiments were conducted at hot air temperatures of 40, 45, 50, 55 and 60 °C and hot air speed of 1 m/s. The hot air temperature had significant effect on the effective moisture diffusivity of the leather sample. The average effective moisture diffusivity in rosehip ranged between 5.87 × 10-11 and 14.48 × 10-11 m2/s for leather at the temperatures studied. Activation energy for convective drying was found to be 38.46 kJ/mol for leather. The obtained results fully confirm the theoretical study in which an exponentially increasing relationship between effective diffusivity and temperature is predicted. The results of this study provide a better understanding of the drying mechanisms and may lead to a series of recommendations for leather drying optimization. It opens the possibility for further investigations on the description of drying conditions.

  16. Drying Strategy of Shrimp using Hot Air Convection and Hybrid Infrared Radiation/Hot Air Convection

    Directory of Open Access Journals (Sweden)

    Supawan TIRAWANICHAKUL

    2008-01-01

    Full Text Available The main objective of the research was to study the effect of drying temperatures using infrared irradiation and electric heating convection on dehydration and was to investigate the effect of drying conditions on the quality of the shrimp. Two sizes of fresh shrimp (100 shrimp/kg and 200 shrimp/kg with initial moisture content of 270 - 350 % dry-basis were dried under various conditions while the final moisture content of dried shrimp was in ranges between 20 and 25 % dry-basis. Hot air flow rates of 1.0 -   1.2 m/s, drying temperatures of 40 - 90 °C and infrared intensities of 1,785.7 - 3,571.4 W/m2 were used in these experiments. The experimental results showed that the rate of moisture content transfer of both sizes of shrimps decreased exponentially with drying time while increasing drying temperature significantly affected to the drying kinetics and quality of the shrimps. Effective diffusion coefficients of both shrimps were determined by a diffusion model forming a finite cylindrical shape was in order of 10-7 m2/s and this effective diffusion coefficient value was relatively dependent on the drying temperature compared to the initial moisture content. The quality analysis of dried shrimp using an infrared source and electric heating source found that the redness value (Hunter a-value of dried samples using hybrid infrared radiation and electric heating had a higher colour uniformity than other drying methods. Additionally, shrinkage and rehydration properties were insignificantly different for all drying strategies (p < 0.05 and drying using infrared radiation had higher drying rates compared to electric heat convection, corresponding to relatively low drying times.

  17. Soft Collagen-Gelatine Sponges by Convection Drying

    Directory of Open Access Journals (Sweden)

    Michael Meyer

    2015-02-01

    Full Text Available This study showed that thermally labile fibrillar collagen could be processed continuously in combination with gelatine as foaming additive by convection drying. The procedure led to stable sponges with similar structural and physical properties as found for freeze-dried collagen samples. The fibrillar collagen remained native, while gelatine acted as foaming additive. The absorbency of the sponges was improved by opening the surface with abrasives. A use as medical device with hemostyptic properties would be possible.

  18. Microwave vacuum drying characteristics of Pinus massoniana wood

    Institute of Scientific and Technical Information of China (English)

    Li Xian-jun; Li Wen-jun; Zhang Bi-guang

    2007-01-01

    Microwave-vacuum (MV) drying characteristics of plantation Masson pine (Pinus massoniana) were studied experimentally for various levels of microwave radiation time, initial moisture content (MC), vacuum level and wood thickness. The results show that the process of MV drying for wood can be significantly divided into a short accelerating rate drying period, a long constant rate drying period and falling rate drying period, and the second drying period can extend to levels of mean MC below the fiber saturation point. With the increase of initial MC and microwave radiation time, the drying rate of wood increases significantly. The vacuum level affects the drying rate in a slightly positive way. Within the range of 2 to 6 cm, the effects of sample thickness on the drying rate can be negligible.

  19. Dynamics of convective hot air drying of filiform Lagenaria siceraria

    Directory of Open Access Journals (Sweden)

    Zhu Aishi

    2013-01-01

    Full Text Available In this study, a laboratory convective hot air dryer was used for the thin-layer drying of filiform Lagenaria siceraria and the influences of the drying temperature and air velocity on the drying process were investigated. The drying temperature and the air velocity were varied in the range of 60-80°C and 0.6-1.04 m•s-1, respectively. The experimental data of moisture ratio of filiform Lagenaria siceraria were used to fit the mathematical models, and the dynamics parameters such as convective heat transfer coefficient α and mass transfer coefficient kH were calculated. The results showed that the drying temperature and air velocity influenced the drying process significantly. The Logarithmic model showed the best fit to experimental drying data. It was also found that, the air velocity and the drying temperature influence notable on both of the convective heat transfer coefficient α and the mass transfer coefficient kH. With the increase of hot air velocity from 0.423 to 1.120 ms-1, the values of α varied from 111.3 to 157.7 W•m-2•K-1, the values of kH varied from 13.12 to 18.58 g•m-2• s-1•ΔH-1. With the increase of air temperature from 60 to 80°C, the values of α varied between 150.2 and 156.9 W•m-2•K-1, the values of kH varied between 18.26 and 18.75 g•m-2•s-1•ΔH-1.

  20. Microwave Enhanced Freeze Drying of Solid Waste Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The development of advanced methods for Microwave Enhanced Freeze Drying of Solid Waste (MEFDSW) is proposed. Methods for the recovery of relatively pure water as a...

  1. Microwave Enhanced Freeze Drying of Solid Waste Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Development of technology for Microwave Enhanced Freeze Drying of Solid Waste (MEFDSW) is proposed. The present state of the art for solid waste stabilization using...

  2. Microwave applications to rock specimen drying in laboratory

    Science.gov (United States)

    Park, Jihwan; Park, Hyeong-Dong

    2014-05-01

    Microwave heating is the process in which electromagnetic wave with 300 MHz - 300 GHz heats dielectric material. Although in the beginning microwave was mainly used in food industry to cook or heat the food, it soon became clear that microwave had a large potential for other applications. It was thus introduced in geological fields of investigation like mineral processing, oil sand and oil shale extraction, soil remediation, waste treatment. However, the drying techniques using microwave was rarely treated in geology field. According to the ISRM suggested methods, experimental rock specimens in laboratory test were dried in 105°C oven for a period of at least 24 hours. In this method, hot air transmits heats to material by means of thermal conduction, and the heat was transferred from the surface to the inside of the rock specimens. The thermal gradient and moisture gradient can deteriorate the specimens, and energy can be wasted in bulk heating the specimens. The aim of our study was to compare physical property, microstructural property, and energy efficiency between microwave drying method and conventional oven drying method, and to suggest new method for rock drying. Granite, basalt, and sandstone were selected as specimens and were made in cylinder shape with 54 mm diameter. To compare two different methods, one set of saturated specimens were dried in 105°C conventional oven and the other set of saturated specimens were dried in microwave oven. After dried, the specimens were cooled and saturated in 20°C water 48 hours. The saturation-drying were repeated 50 cycles, and the physical property and microstructural property were measured every 10 cycles. Absorption and elastic wave velocity were measured to investigate the change of physical property, and microscope image and X-ray computed tomography image were obtained to investigate the change of microstructural property of rock specimens. The electricity consumption of conventional oven and microwave oven

  3. Infrared Drying as a Potential Alternative to Convective Drying for Biltong Production.

    Science.gov (United States)

    Cherono, Kipchumba; Mwithiga, Gikuru; Schmidt, Stefan

    2016-06-03

    Two infrared systems set at an intensity of 4777 W/m(2) with peak emission wavelengths of 2.5 and 3.5 µm were used to produce biltong by drying differently pre-treated meat. In addition to meat texture and colour, the microbial quality of the biltong produced was assessed by quantifying viable heterotrophic microorganisms using a most probable number (MPN) method and by verifying the presence of presumptive Escherichia coli in samples produced using infrared and conventional convective drying. The two infrared drying systems reduced the heterotrophic microbial burden from 5.11 log10 MPN/g to 2.89 log10 MPN/g (2.5 µm) and 3.42 log10 MPN/g (3.5 µm), respectively. The infrared systems achieved an up to one log higher MPN/g reduction than the convective system. In biltong samples produced by short wavelength (2.5 µm) infrared drying, E. coli was not detectable. This study demonstrates that the use of short wavelength infrared drying is a potential alternative to conventional convective drying by improving the microbiological quality of biltong products while at the same time delivering products of satisfactory quality.

  4. Convective Air Drying Characteristics for Thin Layer Carrots

    Directory of Open Access Journals (Sweden)

    Ionut Dumitru Velescu

    2013-11-01

    Full Text Available Introduction: Carrot is one of the most commonly used vegetables for human nutrition due to high vitamin and fibre content. Drying is one of the oldest methods of food preservation, and it represents a very important aspect of food processing. Sun drying is the most common method used to preserve agricultural products in most tropical countries; this technique is extremely weather dependent, and has the problems of contamination with dust, soil, sand particles and insects. Also, the required drying time can be quite long. Therefore, using solar and hot-air dryers, which are far more rapid, providing uniformity and hygiene are inevitable for industrial food drying processes. Aim: This paper presents a kinetic study of convective drying without pre-treatment of carrot. The effects of the temperature of the drying agent, the speed of the drying agent and the thickness of the kinetics of drying the sample of carrots were investigated. Materials and methods: The experiments were carried out with the aid of an installation for drying food products, that is capable of ensuring the temperature of the drying agent (air in the range of +25 ... +125 °C. The drying process was conducted at temperature of 45 °C in first hour of process, 2 hours at 55 °C, and 3 hours at 60 °C. The air velocity was setup  at 1.0 - 2.5 m/s. Carrots were divided into segments of a thickness of 0.4 cm. Two mathematical models available in the literature were fitted to the experimental data. Results: The drying rate increases with temperature and decreases with the sample diameter. The Page model is given better prediction than the Henderson and Pabis model and satisfactorily described drying characteristics of carrot slices. Conclusions: The most important characteristics of carrot required for simulation and optimization of the drying were studied. The values of calculated effective diffusivity for drying at 45, 55 and 60oC of air temperature and 1.0, 1.5, 2.0 and 2.5 m

  5. Microwave-Assisted Drying for the Conservation of Honeybee Pollen

    Directory of Open Access Journals (Sweden)

    Angelo Canale

    2016-05-01

    Full Text Available Bee pollen is becoming an important product thanks to its nutritional properties, including a high content of bioactive compounds such as essential amino acids, antioxidants, and vitamins. Fresh bee pollen has a high water content (15%–30% wt %, thus it is a good substrate for microorganisms. Traditional conservation methods include drying in a hot air chamber and/or freezing. These techniques may significantly affect the pollen organoleptic properties and its content of bioactive compounds. Here, a new conservation method, microwave drying, is introduced and investigated. The method implies irradiating the fresh pollen with microwaves under vacuum, in order to reduce the water content without reaching temperatures capable of thermally deteriorating important bioactive compounds. The method was evaluated by taking into account the nutritional properties after the treatment. The analyzed parameters were phenols, flavonoids, with special reference to rutin content, and amino acids. Results showed that microwave drying offers important advantages for the conservation of bee pollen. Irrespective of microwave power and treatment time, phenol and flavonoid content did not vary over untreated fresh pollen. Similarly, rutin content was unaffected by the microwave drying, suggesting that the microwave-assisted drying could be a powerful technology to preserve bioprotective compounds in fresh pollen.

  6. Desorption isotherms, drying characteristics and qualities of glace tropical fruits undergoing forced convection solar drying

    Energy Technology Data Exchange (ETDEWEB)

    Jamradloedluk, Jindaporn; Wiriyaumpaiwong, Songchai [Mahasarakham Univ. Khamriang, Kantarawichai, Mahasarakham (Thailand)

    2008-07-01

    Solar energy, a form of sustainable energy, has a great potential for a wide variety of applications because it is abundant and accessible, especially for countries located in the tropical region. Drying process is one of the prominent techniques for utilization of solar energy. This research work proposes a forced convection solar drying of osmotically pretreated fruits viz. mango, guava, and pineapple. The fruit cubes with a dimension of 1cm x 1cm x 1cm were immersed in 35% w./w. sucrose solution prior to the drying process. Drying kinetics, color and hardness of the final products obtained from solar drying were investigated and compared with those obtained from open air-sun drying. Desorption isotherms of the osmosed fruits were also examined and five mathematical models were used to fit the desorption curves. Experimental results revealed that solar drying provided higher drying rate than natural sun drying. Color of glace fruit processed by solar drying was more intense, indicated by lower value of lightness and higher value of yellowness, than that processed by sun drying. Hardness of the products dehydrated by both drying methods, however, was not significantly different (p>0.05). Validation of the mathematical models developed showed that the GAB model was most effective for describing desorption isotherms of osmotically pretreated mango and pineapple whereas Peleg's model was most effective for describing desorption isotherms of osmotically pretreated guava. (orig.)

  7. Microwave drying characteristics of coriander (Coriandrum sativum L.) leaves

    Energy Technology Data Exchange (ETDEWEB)

    Sarimeseli, Ayse [Department of Chemical Engineering, Inonu University, 44069 Malatya (Turkey)

    2011-02-15

    Effect of microwave power output on effective moisture diffusivity, colour parameters and rehydration characteristics of coriander leaves (Coriandrum sativum L.) was investigated by using a microwave drier. Within the range of microwave power values, 180-360 W, effective moisture diffusivities were found to be 6.3 x 10{sup -11}-2.19 x 10{sup -10} m{sup 2}/s and the result could successfully be presented with the model suggested by Midilli et al. No significant differences in the colour parameters were obtained between the fresh and dried samples and the changes in their values were not dependent on the power outputs of the microwave drier. The highest rehydration capacity was recorded for the samples dried at 180 W and lowest at 900 W. (author)

  8. Microwave Drying Effects On Dichromated Gelatin Holograms

    Science.gov (United States)

    Andrade, Ana A.; Rebordao, Jose M.

    1989-05-01

    Holograms recorded in dichromated gelatin can easily be destroyed when subjected to high temperatures. In this work, a new treatment of holographic dichromated gelatin layers that improves remarkably the hologram life time under adverse thermal conditions, is presented: exposing the developed hologram to microwave radiaton. Similar holograms were subjected to microwave radiation for variable timelengths and then subjected to heating. The resultant angular and spectral bandwidths were measured after different heating time intervals. Some preliminary results will be presented. The role of water in holograms made with dicromated gelatin will be discussed, in this new context.

  9. Drying kinetics, rehydration and colour characteristics of convective hot-air drying of carrot slices

    Science.gov (United States)

    Doymaz, İbrahim

    2016-03-01

    The effects of air drying temperature, slice thickness and pre-treatment application on the drying kinetics of carrot slices during convective drying in the range 50-70 °C were investigated. Results indicated that drying time, rehydration ratio and colour characteristics of carrot slices were more affected by drying air temperature, followed by pre-treatment applications. Five thin-layer drying models were applied to describe the drying kinetics. Midilli et al. model was the best model to characterize the drying kinetics of carrot slices. The moisture effective diffusivity calculated from the second Fick's law of diffusion ranged from 3.46 × 10-10 to 1.02 × 10-9 m2/s. The values of activation energy determined from the slope of the Arrhenius plot, ln(D eff ) versus 1/(T + 273.15), were 35.53, 43.42, and 37.75 kJ/mol for blanch, potas and control samples, respectively.

  10. Drying kinetics, rehydration and colour characteristics of convective hot-air drying of carrot slices

    Science.gov (United States)

    Doymaz, İbrahim

    2017-01-01

    The effects of air drying temperature, slice thickness and pre-treatment application on the drying kinetics of carrot slices during convective drying in the range 50-70 °C were investigated. Results indicated that drying time, rehydration ratio and colour characteristics of carrot slices were more affected by drying air temperature, followed by pre-treatment applications. Five thin-layer drying models were applied to describe the drying kinetics. Midilli et al. model was the best model to characterize the drying kinetics of carrot slices. The moisture effective diffusivity calculated from the second Fick's law of diffusion ranged from 3.46 × 10-10 to 1.02 × 10-9 m2/s. The values of activation energy determined from the slope of the Arrhenius plot, ln( D eff ) versus 1/(T + 273.15), were 35.53, 43.42, and 37.75 kJ/mol for blanch, potas and control samples, respectively.

  11. Vacuum-assisted microwave drying characteristics of green bell pepper

    Directory of Open Access Journals (Sweden)

    Vivek Kumar

    2017-04-01

    Full Text Available Chopped green bell pepper pieces were blanched (95 °C, 5 min and chemically pretreated (1% potassium metabisulphite solution, 25 min at room temperature before drying in hot air dryer (HAD at various temperature ranges (60 – 80 °C. Three vacuum levels (200, 400, 600 mm Hg and microwave power levels (100, 200, 300 W were also used to dry green bell pepper samples in a vacuum assisted microwave (VAM (2.45 GHz, 0.8 kW dryer. VAM drying methods offered a maximum reduction by four to five times in drying time as compared to that in HAD. The logarithmic model was found to have the best fit based on high R2 and small values of reduced χ2 and RMSE.  VAM method has higher values for effective moisture diffusivity (Deff and lower values for activation energy (Ea, in comparison to the HAD method. 

  12. CONVECTIVE DRYING OF CHERRY TOMATO: STUDY OF SKIN EFFECT

    Directory of Open Access Journals (Sweden)

    R. KHAMA

    2016-03-01

    Full Text Available A whole single cherry tomato was dried in a forced convective micro-dryer. The experiments were carried out at constant air velocity and humidity and temperatures of 50, 60, 70 °C. In order to study the effect of the skin, two sets of experiments were performed using a tomato with and without skin (easily removed. Shorter drying times were obtained when increasing drying temperatures as well as when removing sample skin. X-ray microtomography, a non-destructive 3D imaging technique was used to follow shrinkage of the samples. This phenomenon was introduced in the modelling part of this study. Analytical solutions of the Fick’law were used to determine the diffusion coefficient at the three temperatures studied, and then the activation energy was obtained through fitting the Arrhenius equation. The skin effect was clearly evidenced by showing that the mass transfer parameter values of an original tomato with skin were largely smaller than the one without skin. Indeed, the moisture effective diffusivity ranged from 2.56×10-11 to 7.67×10-11 m2·s-1 with activation energy of 50430 J·mol-1 for tomato with skin an ranged from 4.59×10-10 m2·s-1 to 6.73×10-10 m2·s-1 with activation energy of 17640 J.mol-1 for tomato without skin.

  13. Mathematical modeling of a convective textile drying process

    Directory of Open Access Journals (Sweden)

    G. Johann

    2014-12-01

    Full Text Available This study aims to develop a model that accurately represents the convective drying process of textile materials. The mathematical modeling was developed from energy and mass balances and, for the solution of the mathematical model, the technique of finite differences, in Cartesian coordinates, was used. It transforms the system of partial differential equations into a system of ordinary equations, with the unknowns, the temperature and humidity of both the air and the textile material. The simulation results were compared with experimental data obtained from the literature. In the statistical analysis the Shapiro-Wilk test was used to validate the model and, in all cases simulated, the results were p-values greater than 5 %, indicating normality of the data. The R-squared values were above 0.997 and the ratios Fcalculated/Fsimulated, at the 95 % confidence level, higher than five, indicating that the modeling was predictive in all simulations.

  14. Improved shelf life of dried Beauveria bassiana blastospores using convective drying and active packaging processes.

    Science.gov (United States)

    Mascarin, Gabriel Moura; Jackson, Mark A; Behle, Robert W; Kobori, Nilce N; Júnior, Ítalo Delalibera

    2016-10-01

    The yeast form (blastospore) of the dimorphic insect-pathogenic fungus Beauveria bassiana can be rapidly produced using liquid fermentation methods but is generally unable to survive rapid dehydration processes or storage under non-refrigerated conditions. In this study, we evaluated the influence of two convective drying methods, various modified atmosphere packaging systems, and storage temperatures on the desiccation tolerance, storage stability, and virulence of blastospores of B. bassiana ESALQ 1432. All blastospore formulations were dried to <5 % water content equivalent to aw < 0.3. The viability of B. bassiana blastospores after air drying and spray drying was greater than 80 %. Vacuum-packaged blastospores remained viable longer when stored at 4 °C compared with 28 °C with virtually no loss in viability over 9 months regardless the drying method. When both oxygen and moisture scavengers were added to sealed packages of dried blastospore formulations stored at 28 °C, viability was significantly prolonged for both air- and spray-dried blastospores. The addition of ascorbic acid during spray drying did not improve desiccation tolerance but enhanced cell stability (∼twofold higher half-life) when stored at 28 °C. After storage for 4 months at 28 °C, air-dried blastospores produced a lower LC80 and resulted in higher mortality to whitefly nymphs (Bemisia tabaci) when compared with spray-dried blastospores. These studies identified key storage conditions (low aw and oxygen availability) that improved blastospore storage stability at 28 °C and will facilitate the commercial development of blastospores-based bioinsecticides.

  15. Turmeric (Curcuma longa L.) drying: an optimization approach using microwave-vacuum drying.

    Science.gov (United States)

    Hirun, Sathira; Utama-Ang, Niramon; Roach, Paul D

    2014-09-01

    This study investigated the effect of microwave power (2,400-4,000 W) and drying times (10-30 min) on the quality of dried turmeric in terms of colour (L, a*, b*), moisture content, water activity (aw), ash, antioxidant activity (2,2-dipheneyl-1-picrylhydrazyl; DPPH), total phenolic and curcuminoids content. In addition, Response Surface Methodology (RSM) was implemented to optimize the drying conditions for turmeric. A range of quality parameters, microwave power (W) and time (min) were fitted to quadratic models using a central composite design. The Analysis of Variance (ANOVA) statistic results suggested that the optimal qualities (i.e., aw, value, moisture content, phenolic content, curcuminoid content and EC50 and L value) of dried turmeric were achieved at high vacuum-microwave power (3,500-4,000 W) and long duration (27-30 min). The improvement in the quality of dried turmeric microwave-vacuum drying in these conditions was illustrated through the enzymatic browning reaction via inhibition of polyphenol oxidase which suppressed the formation of the brown pigments and increased the phenol substrates.

  16. Development of microwave-assisted drying methods for sample preparation for dried spot micro-X-ray fluorescence analysis.

    Science.gov (United States)

    Link, Dirk D; Kingston, H M; Havrilla, George J; Colletti, Lisa P

    2002-03-01

    Although dried spot micro X-ray fluorescence (MXRF) is an effective analytical technique for trace elemental analysis, the sample preparation procedures currently used suffer from a number of drawbacks. These drawbacks include relatively long preparation times, lack of control of the sample preparation environment, and possibility of loss of volatile analytes during the drying process. Microwave-assisted drying offers several advantages for dried spot preparation, including control of the environment and minimized volatility because of the differences between microwave heating and conventional heating. A microwave-assisted drying technique has been evaluated for use in preparing dried spots for trace analysis. Two apparatus designs for microwave drying were constructed and tested using multielement standard solutions, a standard reference material, and a "real-world" semiconductor cleaning solution. Following microwave-assisted drying of these aqueous samples, the residues were redissolved and analyzed by ICPMS. Effective recovery was obtained using the microwave drying methods, demonstrating that the microwave drying apparatus and methods described here may be more efficient alternatives for dried spot sample preparation.

  17. Drying performance of fermented cassava (fercaf) using a convective multiple flash dryer

    Science.gov (United States)

    Handojo, Lienda A.; Zefanya, Samuel; Christanto, Yohanes

    2017-05-01

    Fermented cassava (fercaf) is a tropical versatile carbohydrate source flour which is produced by modifying the characteristics of cassava. Drying process is one of the processes that could influence the quality of fercaf. In general, for food application, convective and vacuum drying were used, however recently another advanced method using combination of both convective and vacuum, i.e. convective multiple flash drying (CMFD), was proposed. This method is conducted by repeating cycles of convective and vacuum drying in intermittent manner. Cassava chips with thickness of 0.1-0.2 cm were fermented for 24 hours at room condition. Then, the drying process was conducted by using 3 techniques, i.e. convective, vacuum, and combined method (CMFD), with operation temperatures between 50 and 70°C for 10 hours or until fermented cassava reached a moisture content of less than 20%. The study shows that CMFD was the fastest drying method with only 5-6 hours period compared to 8-10 hours using vacuum and more than 10 hours using convective method. CMFD also produces harder fercaf chips than those of vacuum and convective methods. Moreover, this research also proves that the operating pressure and temperature influence the moisture content.

  18. Effect of microwave power on kinetics and characteristics of microwave vacuum-dried longan (Dimocarpus longan Lour.) pulp.

    Science.gov (United States)

    Su, Dongxiao; Zhang, Mingwei; Wei, Zhencheng; Tang, Xiaojun; Zhang, Ruifen; Liu, Lei; Deng, Yuanyuan

    2015-03-01

    The drying kinetics of longan (Dimocarpus longan Lour.) pulp processed by microwave vacuum under different microwave levels (2.67, 5.33, 8.00, and 10.67 W/g) was investigated (pressure controlled at -85 ± 2 kPa) in the present study. It was found that the drying rate of longan pulp was dependent on the microwave power, and the rehydration rate increased from 1.96 to 2.17 with the increase of microwave power from 2.67 to 10.67 W/g. Among nine selected thin layer models, the microwave vacuum drying of longan pulp was well represented by five models, which were Page, Modified Henderson and Pabis, Wang and Singh, Logarithmic, and Midilli models. Furthermore, the results of statistical analysis indicated that the Midilli model could describe the best experimental data. In addition, scanning electron microscope observation showed that the microwave vacuum-dried longan pulp had a porous structure.

  19. Effects of freezing, freeze drying and convective drying on in vitro gastric digestion of apples.

    Science.gov (United States)

    Dalmau, Maria Esperanza; Bornhorst, Gail M; Eim, Valeria; Rosselló, Carmen; Simal, Susana

    2017-01-15

    The influence of processing (freezing at -196°C in liquid N2, FN sample; freeze-drying at -50°C and 30Pa, FD sample; and convective drying at 60°C and 2m/s, CD sample) on apple (var. Granny Smith) behavior during in vitro gastric digestion was investigated. Dried apples (FD and CD samples) were rehydrated prior to digestion. Changes in carbohydrate composition, moisture, soluble solids, acidity, total polyphenol content (TPC), and antioxidant activity (AA) of apple samples were measured at different times during digestion. Processing resulted in disruption of the cellular structure during digestion, as observed by scanning electron microscopy, light microscopy, and changes in carbohydrate composition. Moisture content increased (6-11% dmo), while soluble solids (55-78% dmo), acidity (44-72% dmo), total polyphenol content (30-61% dmo), and antioxidant activity (41-87%) decreased in all samples after digestion. Mathematical models (Weibull and exponential models) were used to better evaluate the influence of processing on apple behavior during gastric digestion.

  20. Convection forced by a descending dry layer and low-level moist convergence

    Science.gov (United States)

    Russell, Andrew; Vaughan, Geraint; Norton, Emily G.; Ricketts, Hugo M. A.; Morcrette, Cyril J.; Hewison, Tim J.; Browning, Keith. A.; Blyth, Alan M.

    2009-03-01

    A narrow line of convective showers was observed over southern England on 18 July 2005 during the Convective Storm Initiation Project (CSIP). The showers formed behind a cold front (CF), beneath two apparently descending dry layers (i.e. sloping so that they descended relative to the instruments observing them). The lowermost dry layer was associated with a tropopause fold from a depression, which formed 2 d earlier from a breaking Rossby wave, located northwest of the UK. The uppermost dry layer had fragmented from the original streamer due to rotation around the depression (This rotation was also responsible for the observations of apparent descent-ascent would otherwise be seen behind a CF). The lowermost dry layer descended over the UK and overran higher θw air beneath it, resulting in potential instability. Combined with a surface convergence line (which triggered the convection but had less impact on the convective available potential energy than the potential instability), convection was forced up to 5.5 km where the uppermost dry layer capped it. The period when convection was possible was very short, thus explaining the narrowness of the shower band. Convective Storm Initiation Project observations and model data are presented to illustrate the unique processes in this case.

  1. RESEARCH OF MICROWAVE DRYING OF NATURAL ZEOLITE GRANULES AND ITS INFLUENCE ON THE TECHNOLOGICAL PROPERTIES

    Directory of Open Access Journals (Sweden)

    Rybachuk V.D.

    2016-06-01

    Full Text Available Introduction. The wet granulation technique is often used in the preparation of free-flowing granules in the manufacture of tablets and capsules. It is very important that granules obtained by this technology be dried before further processing. And also, it is important that the method of drying is entirely controlled and managed and the result is quite predictable. In recent years, microwave drying of granules make a considerable interest. Microwave drying is especially useful for moisture sensitive materials which are mostly pharmaceutical substances. Microwave drying technology is useful for dosage forms with high purity, since this method provides the possibility of drying in the same container production, which reduces the chance of cross contamination of matter and its direct contact with staff. The aim of this work was to study the effect of microwave radiation on the technological properties of natural zeolite peets compared to traditional convection method and to determine the optimal drying modes and specific humidity of the material. Material & methods. Granules were prepared by wet granulation technology by using a laboratory granulator NG-12. As the humidifier we used potato starch gel and PVP in an amount of 25% by weight of the dry product. The resulting granules were divided into two equal parts and subjected to drying in a microwave oven (Delfa D20MW of installed capacity (119 W, 280 W, 336 W, 462 W, ​​595 W and 700 W and shelf dryer to a residual moisture level of 0.01 g.w./g.d.m. or less. Determination of the specific humidity of granules was carried out by mass loss on drying. Fractional composition of granules was determined using a standard set of sieves with the diameter of the holes 2.0; 1.0; 0.5 and 0.25 mm. The friability of the granules was determined using friabilator Pharma Test PTF 10E / ER, Germany. To characterize the fluidity of granule Carr`s indicator (IC and coefficient Hausnera (HR. Results & discussion

  2. Aircraft microwave observations and simulations of deep convection from 18 to 183 GHz. I - Observations

    Science.gov (United States)

    Adler, Robert F.; Mack, Robert A.; Prasad, N.; Hakkarinen, Ida M.; Yeh, H.-Y. M.

    1990-01-01

    Aircraft passive microwave observations of deep atmospheric convection at frequencies between 18 and 183 GHz are presented in conjunction with visible and infrared satellite and aircraft observations and ground-based radar observations. Deep convective cores are indicated in the microwave data by negative brightness temperature, T/(B) deviations from the land background (270 K) to extreme T(B) values below 100 K at 37, 92, and 183 GHz and below 200 K at 18 GHz. These T(B) minima, due to scattering by ice held aloft by the intense updrafts, are well correlated with areas of high radar reflectivity. For this land background case, T(B) is inversely correlated with rain rate at all frequencies due to T(B)-ice-rain correlations. Mean Delta-T between vertically polarized and horizontally polarized radiance in precipitation areas is approximately 6 K at both 18 GHz and 37 GHz, indicating nonspherical precipitation-size ice particles with a preferred horizontal orientation. Convective cores not observed in the visible and infrared data are clearly defined in the microwave observations, and borders of convective rain areas are well defined using the high-frequency (90 GHz and greater) microwave observations.

  3. Thin layer convective solar drying and mathematical modeling of prickly pear peel (Opuntia ficus indica)

    Energy Technology Data Exchange (ETDEWEB)

    Lahsasni, S.; Mahrouz, M. [Unite de Chimie Agroalimentaire (LCOA), Faculte des Sciences Semlalia, Marrakech (Morocco); Kouhila, M.; Idlimam, A.; Jamali, A. [Ecole Normale Superieure, Marrakech (Morocco). Lab. d' Energie Solaire et Plantes Aromatiques et Medicinales

    2004-02-01

    This paper presents the thin layer convective solar drying and mathematical modeling of prickly pear peel. For these purposes, an indirect forced convection solar dryer consisting of a solar air collector, an auxiliary heater, a circulation fan and a drying cabinet is used for drying experiments. Moreover, the prickly pear peel is sufficiently dried in the ranges of 32 to 36 {sup o} C of ambient air temperature, 50 to 60 {sup o}C of drying air temperature, 23 to 34% of relative humidity, 0.0277 to 0.0833 m{sup 3}/s of drying air flow rate and 200 to 950 W/m{sup 2} of daily solar radiation. The experimental drying curves show only a falling drying rate period. The main factor in controlling the drying rate was found to be the drying air temperature. The drying rate equation is determined empirically from the characteristic drying curve. Also, the experimental drying curves obtained were fitted to a number of mathematical models. The Midilli-Kucuk drying model was found to satisfactorily describe the solar drying curves of prickly pear peel with a correlation coefficient (r) of 0.9998 and chi-square ({chi}{sup 2}) of 4.6572 10{sup -5}. (Author)

  4. Geometry for web microwave heating or drying to a desired profile in a waveguide

    Science.gov (United States)

    Habeger, Jr., Charles C.; Patterson, Timothy F.; Ahrens, Frederick W.

    2005-11-15

    A microwave heater and/or dryer has a nonlinear or curvilinear relative slot profile geometry. In one embodiment, the microwave dryer has at least one adjustable field modifier making it possible to change the geometry of the heater or dryer when drying different webs. In another embodiment, the microwave dryer provides more uniform drying of a web when the field modifier is adjusted in response to a sensed condition of the web. Finally, a method of microwave heating and/or drying a web achieves a uniform heating and/or drying profile.

  5. Determination of drying kinetics and convective heat transfer coefficients of ginger slices

    Science.gov (United States)

    Akpinar, Ebru Kavak; Toraman, Seda

    2016-10-01

    In the present work, the effects of some parametric values on convective heat transfer coefficients and the thin layer drying process of ginger slices were investigated. Drying was done in the laboratory by using cyclone type convective dryer. The drying air temperature was varied as 40, 50, 60 and 70 °C and the air velocity is 0.8, 1.5 and 3 m/s. All drying experiments had only falling rate period. The drying data were fitted to the twelve mathematical models and performance of these models was investigated by comparing the determination of coefficient ( R 2), reduced Chi-square ( χ 2) and root mean square error between the observed and predicted moisture ratios. The effective moisture diffusivity and activation energy were calculated using an infinite series solution of Fick's diffusion equation. The average effective moisture diffusivity values and activation energy values varied from 2.807 × 10-10 to 6.977 × 10-10 m2/s and 19.313-22.722 kJ/mol over the drying air temperature and velocity range, respectively. Experimental data was used to evaluate the values of constants in Nusselt number expression by using linear regression analysis and consequently, convective heat transfer coefficients were determined in forced convection mode. Convective heat transfer coefficient of ginger slices showed changes in ranges 0.33-2.11 W/m2 °C.

  6. Ultrasound-assisted osmotic dehydration and convective drying of apples: Process kinetics and quality issues

    Directory of Open Access Journals (Sweden)

    Mierzwa Dominik

    2016-09-01

    Full Text Available The aim of the present theme issue was to study the influence of ultrasound enhancement on the kinetics of osmotic dehydration and the effect of convective drying from the point of view of drying time and quality of dried products. Apple fruit was used as the experimental material. The kinetics of osmotic dehydration with (UAOD and without (OD ultrasound enhancement were examined for 40% fructose and sorbitol solutions. The effective dehydration time of osmotic process was determined. Preliminary dehydrated samples with OD and UAOD were next dried convectively with (CVUS and without (CV ultrasound assistance. The influence of OD and UAOD on the kinetics of CV and CVUS drying was analysed. The parameters of water activity and colour change were measured for the assessment of product quality after drying process.

  7. Comparison of microwave and conduction-convection heating autohydrolysis pretreatment for bioethanol production.

    Science.gov (United States)

    Aguilar-Reynosa, Alejandra; Romaní, Aloia; Rodríguez-Jasso, Rosa M; Aguilar, Cristóbal N; Garrote, Gil; Ruiz, Héctor A

    2017-06-20

    This work describes the application of two forms of heating for autohydrolysis pretreatment on isothermal regimen: conduction-convection heating and microwave heating processing using corn stover as raw material for bioethanol production. Pretreatments were performed using different operational conditions: residence time (10-50 min) and temperature (160-200°C) for both pretreatments. Subsequently, the susceptibility of pretreated solids was studied using low enzyme loads, and high substrate loads. The highest conversion was 95.1% for microwave pretreated solids. Also solids pretreated by microwave heating processing showed better ethanol conversion in simultaneous saccharification and fermentation process (92% corresponding to 33.8g/L). Therefore, microwave heating processing is a promising technology in the pretreatment of lignocellulosic materials. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Effect of Selected Factors on Drying Process of Tomato in Forced Convection Solar Energy Dryer

    OpenAIRE

    U.S. Muhammed; A.M.I. El-Okene; Isiaka, M

    2012-01-01

    The effect of air velocity, slice thickness and grazing materials in drying process of tomato in forced convection solar energy dryer was evaluated. The result is to serve as an input for solar energy development for drying of vegetable and fruit products in North West Ecological zone of Nigeria. In order to evaluate the effects of the above factors in drying operation, a split-split-plot experimental design was used. Differences among the treatments and their interactions were tested with or...

  9. Ultrasound-assisted osmotic dehydration and convective drying of apples: Process kinetics and quality issues

    OpenAIRE

    Mierzwa Dominik; Kowalski Stefan J.

    2016-01-01

    The aim of the present theme issue was to study the influence of ultrasound enhancement on the kinetics of osmotic dehydration and the effect of convective drying from the point of view of drying time and quality of dried products. Apple fruit was used as the experimental material. The kinetics of osmotic dehydration with (UAOD) and without (OD) ultrasound enhancement were examined for 40% fructose and sorbitol solutions. The effective dehydration time of osmotic process was determined. Preli...

  10. Computer-Controlled Microwave Drying of Potentially Difficult Organic and Inorganic Soils

    Science.gov (United States)

    1990-12-01

    known to have a saturated, surface dry water content of about 3 percent and then subjecting the material to microwave drying. The gravels were...surface dry water content) of some coarse aggregate of chert, limestone, basalt, and quartz. Clay, at the other extreme, can exist at water contents...excluding such oversize particles from microwave water content specimens. c. The saturated surface dry water content of many rock or gravel particles has an

  11. The roles of convection, extratropical mixing, and in-situ freeze-drying in the Tropical Tropopause Layer

    Directory of Open Access Journals (Sweden)

    W. G. Read

    2008-10-01

    Full Text Available Mechanisms for transporting and dehydrating air across the tropical tropopause layer (TTL are investigated with a conceptual two dimensional (2-D model. The 2-D TTL model combines the Holton and Gettelman cold trap dehydration mechanism (Holton and Gettelman, 2001 with the two column convection model of Folkins and Martin (2005. We investigate 3 possible transport scenarios through the TTL: 1 slow uniform ascent across the level of zero radiative heating without direct convective mixing, 2 convective mixing of H2O vapor at 100% relative humidity with respect to ice (RHi with no ice retention, and 3 convective mixing of extremely subsaturated air (100% RHi following the moist adiabatic temperature above the level of neutral buoyancy with sufficient ice retention such that total H2O is 100%RHi. The three mechanisms produce similar seasonal cycles for H2O that are in good quantitative agreement with the Aura Microwave Limb Sounder (MLS measurements. We use Aura MLS measurement of CO and Atmospheric Chemistry Experiment-Fourier Transform Spectrometer measurement of HDO to distinguish among the transport mechanisms. Model comparisons with the observations support the view that H2O is predominantly controlled by regions having the lowest cold point tropopause temperature but the trace species CO and HDO support the convective mixing of dry air and lofted ice. The model provides some insight into the processes affecting the long term trends observed in stratospheric H2O.

  12. Solar drying of whole mint plant under natural and forced convection

    Directory of Open Access Journals (Sweden)

    Y.I. Sallam

    2015-03-01

    Full Text Available Two identical prototype solar dryers (direct and indirect having the same dimensions were used to dry whole mint. Both prototypes were operated under natural and forced convection modes. In the case of the later one the ambient air was entered the dryer with the velocity of 4.2 m s−1. The effect of flow mode and the type of solar dryers on the drying kinetics of whole mint were investigated. Ten empirical models were used to fit the drying curves; nine of them represented well the solar drying behavior of mint. The results indicated that drying of mint under different operating conditions occurred in the falling rate period, where no constant rate period of drying was observed. Also, the obtained data revealed that the drying rate of mint under forced convection was higher than that of mint under natural convection, especially during first hours of drying (first day. The values of the effective diffusivity coefficient for the mint drying ranged between 1.2 × 10−11 and 1.33 × 10−11 m2 s−1.

  13. Solar drying of whole mint plant under natural and forced convection.

    Science.gov (United States)

    Sallam, Y I; Aly, M H; Nassar, A F; Mohamed, E A

    2015-03-01

    Two identical prototype solar dryers (direct and indirect) having the same dimensions were used to dry whole mint. Both prototypes were operated under natural and forced convection modes. In the case of the later one the ambient air was entered the dryer with the velocity of 4.2 m s(-1). The effect of flow mode and the type of solar dryers on the drying kinetics of whole mint were investigated. Ten empirical models were used to fit the drying curves; nine of them represented well the solar drying behavior of mint. The results indicated that drying of mint under different operating conditions occurred in the falling rate period, where no constant rate period of drying was observed. Also, the obtained data revealed that the drying rate of mint under forced convection was higher than that of mint under natural convection, especially during first hours of drying (first day). The values of the effective diffusivity coefficient for the mint drying ranged between 1.2 × 10(-11) and 1.33 × 10(-11) m(2) s(-1).

  14. Drying characteristics of pumpkin ( Cucurbita moschata) slices in convective and freeze dryer

    Science.gov (United States)

    Caliskan, Gulsah; Dirim, Safiye Nur

    2017-06-01

    This study was intended to determine the drying and rehydration kinetics of convective and freeze dried pumpkin slices (0.5 × 3.5 × 0.5 cm). A pilot scale tray drier (at 80 ± 2 °C inlet temperature, 1 m s-1 air velocity) and freeze drier (13.33 kPa absolute pressure, condenser temperature of -48 ± 2 °C) were used for the drying experiments. Drying curves were fitted to six well-known thin layer drying models. Nonlinear regression analysis was used to evaluate the parameters of the selected models by using statistical software SPSS 16.0 (SPSS Inc., USA). For the convective and freeze drying processes of pumpkin slices, the highest R2 values, and the lowest RMSE as well as χ2 values were obtained from Page model. The effective moisture diffusivity (Deff) of the convective and freeze dried pumpkin slices were obtained from the Fick's diffusion model, and they were found to be 2.233 × 10-7 and 3.040 × 10-9 m2s-1, respectively. Specific moisture extraction rate, moisture extraction rate, and specific energy consumption values were almost twice in freeze drying process. Depending on the results, moisture contents and water activity values of pumpkin slices were in acceptable limits for safe storage of products. The rehydration behaviour of [at 18 ± 2 and 100 ± 2 °C for 1:25, 1:50, 1:75, 1:100, and 1:125 solid:liquid ratios (w:w)] dried pumpkin slices was determined by Peleg's model with the highest R2. The highest total soluble solid loss of pumpkin slices was observed for the rehydration experiment which performed at 1:25 solid: liquid ratio (w:w). Rehydration ratio of freeze dried slices was found 2-3 times higher than convective dried slices.

  15. Drying characteristics of pumpkin (Cucurbita moschata) slices in convective and freeze dryer

    Science.gov (United States)

    Caliskan, Gulsah; Dirim, Safiye Nur

    2017-01-01

    This study was intended to determine the drying and rehydration kinetics of convective and freeze dried pumpkin slices (0.5 × 3.5 × 0.5 cm). A pilot scale tray drier (at 80 ± 2 °C inlet temperature, 1 m s-1 air velocity) and freeze drier (13.33 kPa absolute pressure, condenser temperature of -48 ± 2 °C) were used for the drying experiments. Drying curves were fitted to six well-known thin layer drying models. Nonlinear regression analysis was used to evaluate the parameters of the selected models by using statistical software SPSS 16.0 (SPSS Inc., USA). For the convective and freeze drying processes of pumpkin slices, the highest R2 values, and the lowest RMSE as well as χ2 values were obtained from Page model. The effective moisture diffusivity (Deff) of the convective and freeze dried pumpkin slices were obtained from the Fick's diffusion model, and they were found to be 2.233 × 10-7 and 3.040 × 10-9 m2s-1, respectively. Specific moisture extraction rate, moisture extraction rate, and specific energy consumption values were almost twice in freeze drying process. Depending on the results, moisture contents and water activity values of pumpkin slices were in acceptable limits for safe storage of products. The rehydration behaviour of [at 18 ± 2 and 100 ± 2 °C for 1:25, 1:50, 1:75, 1:100, and 1:125 solid:liquid ratios (w:w)] dried pumpkin slices was determined by Peleg's model with the highest R2. The highest total soluble solid loss of pumpkin slices was observed for the rehydration experiment which performed at 1:25 solid: liquid ratio (w:w). Rehydration ratio of freeze dried slices was found 2-3 times higher than convective dried slices.

  16. Numerical simulation of forced convection in a duct subjected to microwave heating

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, J.; Kuznetsov, A.V. [North Carolina State University, Department of Mechanical and Aerospace Engineering, Campus Box 7910, Raleigh, NC (United States); Sandeep, K.P. [North Carolina State University, Department of Food Science, Raleigh, NC (United States)

    2007-01-15

    In this paper, forced convection in a rectangular duct subjected to microwave heating is investigated. Three types of non-Newtonian liquids flowing through the duct are considered, specifically, apple sauce, skim milk, and tomato sauce. A finite difference time domain method is used to solve Maxwell's equations simulating the electromagnetic field. The three-dimensional temperature field is determined by solving the coupled momentum, energy, and Maxwell's equations. Numerical results show that the heating pattern strongly depends on the dielectric properties of the fluid in the duct and the geometry of the microwave heating system. (orig.)

  17. STATISTIC MODELING OF DRYING KINETHIC OF SPINACH LEAVES USING MICROWAVE AND HOT AIR METHODS

    Directory of Open Access Journals (Sweden)

    Mojtaba Nouri

    2015-06-01

    Full Text Available The target of this study was to model of spinach leaves drying using microwave and hot air dryer. This test performed in combination treatment of temperatures (50°C, 60°C, and 70°C and microwave (90, 180, 360, 600 and 900w in 3 replications. Sample moisture measured within drying. All the results were fitted and analyzed with 8 mathematical models base on 3 parameters including determination (R2, Chi square(X2, root mean square errors(RSME. Results also revealed that temperature and microwave power effectively reduce the drying time when increase. Drying occurs in degrading stage; moreover the comparison of results exhibited that Page and Two sentences models were fitted appropriately to estimate moisture changing and drying description. Regarding all the results, it is cleared that microwave method is an appropriate method in spinach drying as a result of reducing drying temperature and its high efficiency.

  18. Dimensionless formulation of convective heat transfer in fry-drying of sewage sludge

    Energy Technology Data Exchange (ETDEWEB)

    Romdhana, M.H.; Lecomte, D.; Ladevie, B. [Ecole des Mines d' Albi-Carmaux, Centre RAPSODEE, Albi (France)

    2011-11-15

    Fry-drying is an alternative for heat and mass transfer intensification. The process reuses waste oil as a heating medium for drying by contact with the wet sludge. At the end of the process, a stable derived fuel is obtained, a granular solid composed of the dried indigenous sewage solid and the impregnated oil. The fry-dried sludge is storable and transportable without any pathogen elements. Knowledge about heat and mass transfer rates during the frying process is essential in order to assess the quality of the final product such as calorific value, oil uptake, porosity changes, etc. The heat transfer properties including transfer by free convection between the solid and the frying oil are fundamental for the process design and manufacturing of the fry-dried product. The convective heat coefficient by temperature measurement and overall energy balance calculation is determined. The heat flux is calculated from the fry-drying kinetics including moisture loss and oil intake kinetics. Various hydrodynamic regimes for convective heat transfer during the frying process are discussed (non-boiling, boiling, and low-boiling regime). A dimensionless formulation for estimating the convective transfer is proposed. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. OPTIMIZATION OF MICROWAVE AND AIR DRYING CONDITIONS OF QUINCE (CYDONIA OBLONGA, MILLER USING RESPONSE SURFACE METHODOLOGY

    Directory of Open Access Journals (Sweden)

    Cem Baltacioglu

    2015-03-01

    Full Text Available Effects of slice thickness of quince (Cydonia oblonga Miller , microwave incident power and air drying temperature on antioxidant activity and total phenolic content of quince were investigated during drying in microwave and air drying. Optimum conditions were found to be: i for microwave drying, 285 W and 4.14 mm thick (maximum antioxidant activity and 285 W and 6.85 mm thick (maximum total phenolic content, and ii for air drying, 75 ºC and 1.2 mm thick (both maximum antioxidant activity and total phenolic content. Drying conditions were optimized by using the response surface methodology. 13 experiments were carried out considering incident microwave powers from 285 to 795 W, air temperature from 46 to 74 ºC and slice thickness from 1.2 to 6.8 mm.

  20. Estimation of cauliflower mass transfer parameters during convective drying

    Science.gov (United States)

    Sahin, Medine; Doymaz, İbrahim

    2016-05-01

    The study was conducted to evaluate the effect of pre-treatments such as citric acid and hot water blanching and air temperature on drying and rehydration characteristics of cauliflower slices. Experiments were carried out at four different drying air temperatures of 50, 60, 70 and 80 °C with the air velocity of 2.0 m/s. It was observed that drying and rehydration characteristics of cauliflower slices were greatly influenced by air temperature and pre-treatment. Six commonly used mathematical models were evaluated to predict the drying kinetics of cauliflower slices. The Midilli et al. model described the drying behaviour of cauliflower slices at all temperatures better than other models. The values of effective moisture diffusivities (D eff ) were determined using Fick's law of diffusion and were between 4.09 × 10-9 and 1.88 × 10-8 m2/s. Activation energy was estimated by an Arrhenius type equation and was 23.40, 29.09 and 26.39 kJ/mol for citric acid, blanch and control samples, respectively.

  1. Estimation of cauliflower mass transfer parameters during convective drying

    Science.gov (United States)

    Sahin, Medine; Doymaz, İbrahim

    2017-02-01

    The study was conducted to evaluate the effect of pre-treatments such as citric acid and hot water blanching and air temperature on drying and rehydration characteristics of cauliflower slices. Experiments were carried out at four different drying air temperatures of 50, 60, 70 and 80 °C with the air velocity of 2.0 m/s. It was observed that drying and rehydration characteristics of cauliflower slices were greatly influenced by air temperature and pre-treatment. Six commonly used mathematical models were evaluated to predict the drying kinetics of cauliflower slices. The Midilli et al. model described the drying behaviour of cauliflower slices at all temperatures better than other models. The values of effective moisture diffusivities ( D eff ) were determined using Fick's law of diffusion and were between 4.09 × 10-9 and 1.88 × 10-8 m2/s. Activation energy was estimated by an Arrhenius type equation and was 23.40, 29.09 and 26.39 kJ/mol for citric acid, blanch and control samples, respectively.

  2. Quality Characteristics of Microwave-Vacuum Dried Button Mushrooms (Agaricus Bisporus

    Directory of Open Access Journals (Sweden)

    S.K.Giri & Suresh Prasad

    2013-05-01

    Full Text Available Button mushroom (Agaricus bisporus slices as well as whole mushrooms were dried by microwave-vacuum drying technique to a moisture content of around 6 %(d.b.. The dehydrated mushrooms were compared with hot-air dried products on the basis of different quality attributes such as colour, texture, rehydration ratio and sensory score. Statistical analysis of data revealed significant difference among the drying methods for all the attributes at p ≤ 0.05. Microwave-vacuum dried mushrooms had significantly higher rehydration potential, lower density, better colour and softer texture than those obtained by air drying. The microwave-vacuum dried mushrooms were rated much better than air dried products by a sensory panel in terms of appearance, color and overall acceptability.

  3. Process Parameter Study on Microwave-assisted Foam-mat Drying Properties of Corn Soaking Water

    Institute of Scientific and Technical Information of China (English)

    Zheng Xian-zhe

    2016-01-01

    In order to study the microwave-assisted foam-mat drying properties of corn soaking water and optimize process parameters, a quadratic regression orthogonal rotary method was used to analyze the influence of microwave power, material weight, material thickness and drying time on moisture content (dry basis), color value and protein content. Results showed that the primary and secondary sequence of parameters with regard to moisture content (d. b.) was drying time, microwave power, material weight and material thickness; the primary and secondary sequence of parameters with regard to color value was material weight, drying time, microwave power and material thickness; the primary and secondary sequence of parameters with regard to protein content was drying time, material weight, microwave power and material thickness. Optimum conditions were obtained as microwave power of 560 W, material weight of 46.88 g, material thickness of 6.20 mm and drying time of 8.01 min. The results might provide the theoretical basis and technical support for the microwave-assisted foam-mat drying of corn soaking water to produce yeast protein power.

  4. The influence of microwave-assisted drying techniques on the rehydration behavior of blueberries (Vaccinium corymbosum L.).

    Science.gov (United States)

    Zielinska, Magdalena; Markowski, Marek

    2016-04-01

    The aim of this study was to determine the effect of: (a) different drying methods, (b) hot air temperature in a convection oven, and (c) the moisture content of fruits dehydrated by multi-stage drying which involves a transition between different stages of drying, on the rehydration kinetics of dry blueberries. Models describing rehydration kinetics were also studied. Blueberries dehydrated by multi-stage microwave-assisted drying, which involved a hot air pre-drying step at 80 °C until the achievement of a moisture content of 1.95 kg H2O kg(-1)DM, were characterized by significantly higher rates of initial and successive rehydration as well as smaller initial loss of soluble solids in comparison with the samples dried by other methods. The highest initial rehydration rate and the smallest loss of soluble solids after 30 min of soaking were determined at 0.46 min(-1) and 0.29 kg DM kg(-1)DM, respectively. The Peleg model and the first-order-kinetic model fit the experimental data well.

  5. Potential negative effects of groundwater dynamics on dry season convection in the Amazon River basin

    Science.gov (United States)

    Lin, Yen-Heng; Lo, Min-Hui; Chou, Chia

    2016-02-01

    Adding a groundwater component to land surface models affects modeled precipitation. The additional water supply from the subsurface contributes to increased water vapor in the atmosphere, resulting in modifications of atmospheric convection. This study focuses on how groundwater dynamics affect atmospheric convection in the Amazon River basin (ARB) during July, typically the driest month. Coupled groundwater-land-atmosphere model simulations show that groundwater storage increases evapotranspiration rates (latent heat fluxes) and lowers surface temperatures, which increases the surface pressure gradient and thus, anomalous surface divergence. Therefore, the convection over the Southern Hemispheric ARB during the dry season becomes weaker when groundwater dynamics are included in the model. Additionally, the changes in atmospheric vertical water vapor advection are associated with decreases in precipitation that results from downwelling transport anomalies. The results of this study highlight the importance of subsurface hydrological processes in the Amazon climate system, with implications for precipitation changes during the dry season, observed in most current climate models.

  6. Potential Negative Effects of Groundwater Dynamics on Dry Season Convection in the Amazon River Basin

    Science.gov (United States)

    Lin, Y. H.; Lo, M. H.; Chou, C.

    2014-12-01

    Adding a groundwater component to land surface models affects modeled precipitation because the additional water supply from the subsurface contributes to increased water vapor in the atmosphere, resulting in modifications of atmospheric convection. This study focused on how groundwater dynamics affect atmospheric convection in the Amazon River Basin (ARB) during July, typically the driest month. Coupled groundwater-land-atmosphere model simulations show that groundwater storage increases evapotranspiration rates (latent heat fluxes) and lowers surface temperatures, which increases the surface pressure gradient and thus, anomalous surface divergence. Therefore, the convection over the Southern Hemispheric ARB during the dry season becomes weaker when groundwater dynamics are included in the model. In addition, the changes in atmospheric vertical water vapor advection are associated with decreases in precipitation resulting from downward transport anomalies. The results of this study highlight the importance of subsurface hydrological processes in the Amazon climate system, which have implications for precipitation changes during the dry season observed in most current climate models.

  7. Evaluation of total carotenoids and ascorbic acid in osmotic pretreated guavas during convective drying

    NARCIS (Netherlands)

    Sanjinez-Argandona, EJ; Cunha, RL; Menegalli, FC; Hubinger, MD

    2005-01-01

    Degradation of ascorbic acid and carotenoid content in osmotic pretreated and convective dried guavas was investigated. The osmotic dehydration was performed in a semi-continuous flow osmotic contactor at 40 degrees C for two hours with sucrose solution at 60% (w/ w). Pretreated guava sticks were dr

  8. Microwave drying of granules containing a moisture-sensitive drug: a promising alternative to fluid bed and hot air oven drying.

    Science.gov (United States)

    Chee, Sze Nam; Johansen, Anne Lene; Gu, Li; Karlsen, Jan; Heng, Paul Wan Sia

    2005-07-01

    The impact of microwave drying and binders (copolyvidone and povidone) on the degradation of acetylsalicylic acid (ASA) and physical properties of granules were compared with conventional drying methods. Moist granules containing ASA were prepared using a high shear granulator and dried with hot air oven, fluid bed or microwave (static or dynamic bed) dryers. Percent ASA degradation, size and size distribution, friability and flow properties of the granules were determined. Granules dried with the dynamic bed microwave dryer showed the least amount of ASA degradation, followed by fluid bed dryer, static bed microwave oven and hot air oven. The use of microwave drying with a static granular bed adversely affected ASA degradation and drying capability. Dynamic bed microwave dryer had the highest drying capability followed by fluid bed, static bed microwave dryer and conventional hot air oven. The intensity of microwave did not affect ASA degradation, size distribution, friability and flow properties of the granules. Mixing/agitating of granules during drying affected the granular physical properties studied. Copolyvidone resulted in lower amount of granular residual moisture content and ASA degradation on storage than povidone, especially for static bed microwave drying. In conclusion, microwave drying technology has been shown to be a promising alternative for drying granules containing a moisture-sensitive drug.

  9. Effect of microwave-vacuum drying (MVD) method on quality properties of agro-products

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Microwave-vacuum drying is an accepted drying method for agro-products, which is nonetheless still relatively unknown to some. This paper attempted to give an overview of the most important aspects of microwaves-vacuum drying (MVD) and their relevance to agro-products processing. Some advantages on microwave-vacuum drying properties were discussed to provide a better insight into the reasons for the use of microwaves. Also the effects of the MVD on the quality of several agro-products and reasonable processing parameters were given, which develop the guidance to the application of MVD on the agro-products dehydration. As a potential drying technology, MVD will be broadly utilized for the other agro-products processing.

  10. Microwave blanching and drying characteristics of Centella asiatica (L.) urban leaves using tray and heat pump-assisted dehumidified drying.

    Science.gov (United States)

    Trirattanapikul, W; Phoungchandang, S

    2014-12-01

    The appropriate stage of maturity of Centella asiatica (L.) Urban leaves was investigated. Mature leaves with large diameter contained high total phenolics and % inhibition. Microwave blanching for 30 s retained the highest total phenolics and the microwave blanching for 30 s and 45 s retained the highest % inhibition. Modified Henderson and Modified Chung-Pfost models showed the best fit to both fresh and blanched leaves for equilibrium moisture content, Xe = f(RHe, T) and equilibrium relative humidity, RHe = f(Xe, T), respectively. The Modified Page model was the most effective model in describing the leaf drying. All drying was in the falling rate period. The drying constant was related to drying air temperature using the Arrhenius model. Effective moisture diffusivities increased with increasing temperature and blanching treatments as well as dehumidification by heat pump-assisted dehumidified dryer. The heat pump-assited dehumidified drying incorporated by the microwave blanching could reduce the drying time at 40 °C by 31.2 % and increase % inhibition by 6.1 %. Quality evaluation by total phenolics, % inhibition and rehydration ratio showed the best quality for C. asiatica leaves pretreated by microwave blanching and dried at 40 °C in heat pump-assisted dehumidified dryer.

  11. Development of a Microwave System for Highly-Efficient Drying of Fish

    Directory of Open Access Journals (Sweden)

    Yuttapong PIANROJ

    2006-06-01

    Full Text Available Dried fish is an important product of Nakhon Si Thammarat province, located in southern Thailand. Fish are conventionally dried using heat from the sun or heat from burning wood as energy sources. These drying methods have problems such as low efficiency and environmental problems. Exploiting the strong electric dipole of the water molecules in the fish, which allows the fish to absorb microwave energy effectively, we have developed a novel microwave heating system for the efficient drying of fish. The system utilizes a high-voltage power supply so that the magnetron can generate a microwave field continuously, and its output power can be adjusted from 0 - 200 W making it very different to commercial microwave oven. The waveguide is designed for effective transmission of microwave fields into the multi-mode heating cavity. The experimental results reveal that heat produced by the microwave system causes evaporation of moisture from the fish making it possible to produce high quality dried fish. The drying process also shows a dependence of fish surface temperature and moisture content on the radiation time and microwave power.

  12. Comparison of microwave oven and convection oven for acid hydrolysis of dietary fiber polysaccharides.

    Science.gov (United States)

    Li, B W

    1998-01-01

    Hydrolysis of dietary fiber polysaccharides (DFP) is an integral part of any enzymatic-chemical method for dietary fiber analysis. Residues obtained after enzyme treatments of fiber-containing foods are usually suspended in 12 M sulfuric acid and kept at or slightly above ambient temperature for at least 1 h, and then the mixtures are diluted with deionized water to a final concentration of 1 M or 2 M acid, followed by heating at 100 degrees C in a water bath or convection oven for 1 or 2 h. Under these hydrolytic conditions, some degradation of the released monosaccharides generally takes place over the duration of hydrolysis. We investigated the feasibility of using microwave energy as a heat source to reduce time and minimize degradation. Preliminary tests were done on the well-characterized soy polysaccharide Fibrim. With a microwave digestion system equipped with temperature and pressure monitors and control lines, optimum settings of power (5%, 75%), time (up to 3 min and 30 s), temperature (35 degrees-55 degrees C), and pressure (45-65 psi) were determined for different foods depending on the residue weight and volume of acid. Results were comparable for microwave oven and convection oven hydrolysis of DFP from 5 foods with good correlations for neutral sugar values; r2 = 0.997 for arabinose, 0.925 for galactose, 0.981 for glucose, 0.969 for mannose, and 0.990 for xylose.

  13. Study on microwave-induced thin-layer drying of municipal sludge for fuel reclamation

    Institute of Scientific and Technical Information of China (English)

    HUANG He-xun; CHEN Han-pin; HU Zhi-feng; MA Xiao-qian

    2012-01-01

    Since the adverse factors such as deficient penetration and long reaction time have restricted the complete microwave-used drying of municipal sludge,the microwave-induced drying is considered,which has advantages in such aspects.The investigation of the microwave-induced drying to uncover the mechanism bears great meaning for its development and utilization.The effects of temperature and microwave cracking in municipal sewage sludge drying characteristics are studied through municipal sewage sludge drying experiment.Experiments shows that higher drying temperature would lead to a more acutely changing drying rate (DR).The DR had increased from 0.005 g/(g·min) to 0.060 g/(g·min),which was 12 times enlarged,while the temperature rose from 70 ℃ to 160 ℃.The higher the temperature was,the earlier the peak value of DR appeared.The experiments indicated that the temperature was the decisive factor affecting the DR.The microwave-induced sludge reached the highest DR at the moisture rate (MR) of 40%,with a 20% grade promotion compared with that of the original one.The molecular fracture caused by microwave radiation had obviously accelerated the drying process and the DR was rising in proportion to the microwave radiation dose.The diffusion coefficient had been calculated according to Fick's law.In comparison to that of the original one,the diffusion coefficient of microwave-induced sludge was obviously enlarged more than two times.By fit examinations,Model Weibull was proven to be the most fit one for thermal thin-layer drying of municipal sludge.By means of Arrhenius equation,the obtained average activation energy of municipal sludge was 37.1 kJ/(mol·K).

  14. Solar energy dryer kinetics using flat-plate finned collector and forced convection for potato drying

    Science.gov (United States)

    Batubara, Fatimah; Misran, Erni; Dina, Sari Farah; Heppy

    2017-06-01

    Research on potato drying using the indirect solar dryer with flat-plate finned collector and forced convection has been done. The research was conducted at the outdoor field of Laboratory of Institute for Research and Standardization of Industry on June 14th-23rd, 2016 from 9:00 am to 4:00 pm. This research aims to obtain the drying kinetics model of potato (Solanumtuberosum L.) using an indirect solar dryer's (ISD) with flat plate-finned collector and forced convection. The result will be compared to the open sun drying (OSD) method. Weather conditions during the drying process took place as follows; surrounding air temperature was in the range 27 to 34.7 °C, relative humidity (RH) 29.5 to 61.0% and the intensity of solar radiation 105.6 to 863.1 Watt/m2. The dried potato thicknesses were 1.0 cm, 1.5 cm and 2.0 cm, with the average initial water content of 76.46%. The average temperature in the collector chamber ranged from 42.2 to 57.4 °C and the drying chamber was at 46.2 °C. The best drying result was obtained from a sample size of 1 cm thickness using the IDS method with an average drying rate of 0.018 kg H2O per kg dry-weight.hour and the water content was constant at 5.02% in 21 hours of drying time. The most suitable kinetics model is Page model, equation MR = exp (-0.049 t1,336) for 1.0 cm thickness, exp (-0.066 t1,222) for 1.5 cm thickness and exp (-0.049 t1,221) for 2.0 cm thickness. The quality of potato drying using ISD method is better than using OSD which can be seen from the color produced.

  15. Analysis Variation of Drying Parameters of Corn Seeds Processed in Microwave Field. Thermal Field Analysis.

    OpenAIRE

    Darie SOPRONI; VICAS Simina; Carmen MOLNAR; ARION Mircea; HATHAZI Francisc Ioan

    2012-01-01

    The present research has the objective to analyze the drying characteristics of the corn seeds in the microwave field. During the experiment is being followed the germination of the seeds and thedistribution of temperature in the dielectric.

  16. Analysis of ginger drying inside a natural convection indirect solar dryer: An experimental study

    Directory of Open Access Journals (Sweden)

    S. K. Sansaniwal

    2015-12-01

    Full Text Available In this paper, a natural convection indirect solar cabinet dryer has been fabricated to study the drying behaviour of ginger rhizomes in terms of its convective heat transfer coefficient and moisture removing rate (% db. Various experiments were conducted during the months of March and April 2014 at Guru Jambheshwar University of Science and Technology, Hisar (29o5’5’’N, 75o45’55’’E, India. Experimental data obtained were used to evaluate the Nusselt number constants using linear regression method. Considering these constants, the average value of convective heat transfer coefficient was obtained and observed to decrease with increase in mass of ginger samples and progression of drying days with variation from 0.59 to 5.42 W/m2˚C for different mass of ginger samples. The moisture removing rate was reported to increase with increase in mass of ginger samples and decreases significantly with the progression of drying days. The average collector efficiency was also observed to vary from 14.97 to 16.14% under increasing and decreasing trends of solar radiations from morning to noon and noon to evening respectively. Modified page model was reported best for describing the drying behaviour of different mass of ginger samples. The experimental error in terms of percent uncertainty ranged from 29.19 to 46.25%.

  17. 双孢菇微波冷冻干燥特性及干燥品质%Drying characteristics and quality of button mushrooms during microwave freeze drying

    Institute of Scientific and Technical Information of China (English)

    段续; 刘文超; 任广跃; 庞玉琪; 刘云宏

    2016-01-01

    Button mushroom is the most widely cultivated and consumed mushroom throughout the world and it contributes about 40% of the total world production of mushroom. Button mushrooms are extremely perishable and their shelf life is only about 24 h in ambient conditions. Various physiological and morphological changes occur after harvest, which make these mushrooms unacceptable for consumption. Hence, they should be consumed or processed promptly after harvest and for this reason the mushrooms are traded mostly in dried form in the world market. The convective drying method is the most commonly used to dry mushrooms. Nevertheless, due to long drying time and high drying temperature at industrial scale, the problems of darkening in color, shrinkage, loss in flavor and decrease in rehydration ability easily occur. In recent years, microwave freeze drying (MFD) has been investigated as a potential method for obtaining high quality dried food products with low energy consumption. Thus, to achieve faster drying rate with high product quality, MFD was applied to dry button mushrooms. The drying curves, effective moisture diffusivity, rehydration ratio, shrinkage ratio, vitamin C retention ratio, energy consumption and the sensory evaluation based on the fuzzy reasoning were investigated, which were considered to reflect the drying and quality characteristics of button mushrooms under different microwave loading levels (0.25, 1.0 and 0.75 W/g) and system pressure (50, 100 and 150 Pa). The drying models were obtained by the nonlinear fitting of drying curves. The weighted comprehensive evaluation of button mushroom MFD processes were also carried out based on energy consumption, drying time, rehydration ratio, whiteness index and vitamin C retention ratio. Results showed that, when changing the microwave loading level, the reduction ratio of the minimum value to the maximum value of drying time, effective moisture diffusion coefficient, whiteness index, rehydration ratio and

  18. Performance Evaluation of a Forced Convection Solar Drier with Evacuated Tube Collector for Drying Amla

    Directory of Open Access Journals (Sweden)

    AR. Umayal Sundari

    2013-06-01

    Full Text Available A forced convection solar drier is designed with evacuated tube collector and a blower. The performance of the designed drier is evaluated by carrying drying experiments at Thanjavur District, Tamilnadu, India with amla. Solar drying of amla is carried at different air velocity flow rates – 4m/s, 4.25m/s and 4.5m/s and is compared with natural sun drying. The temperature of the dryingchamber ranges from 53ºC to 82ºC while the ambient temperature ranges from 29ºC to 32ºC. The efficiency of the designed drier varies from 38.61% to 43.7% where as the efficiency of sun drying varies from 12.5% to 14.15%. It is observed that the efficiency of the drier increases with increase in air velocity flow rates. Initial moisture content of amla ranges between 83.6% and 84.3% and the equilibrium moisture content ranges between 0.1% and 0.6%. Solar drying takes 5 to 7 hours to reach safe moisture content where as sun drying takes 13 to15 hours. Also the quality of solar dried amla is better in terms of colour, odour, flavour and appearance than the sun dried amla. The observed result of the present work shows that the proposed solar drier is good for drying amla in this region.

  19. A surprising method for green extraction of essential oil from dry spices: Microwave dry-diffusion and gravity.

    Science.gov (United States)

    Farhat, Asma; Fabiano-Tixier, Anne-Sylvie; Visinoni, Franco; Romdhane, Mehrez; Chemat, Farid

    2010-11-19

    Without adding any solvent or water, we proposed a novel and green approach for the extraction of secondary metabolites from dried plant materials. This "solvent, water and vapor free" approach based on a simple principle involves the application of microwave irradiation and earth gravity to extract the essential oil from dried caraway seeds. Microwave dry-diffusion and gravity (MDG) has been compared with a conventional technique, hydrodistillation (HD), for the extraction of essential oil from dried caraway seeds. Essential oils isolated by MDG were quantitatively (yield) and qualitatively (aromatic profile) similar to those obtained by HD, but MDG was better than HD in terms of rapidity (45min versus 300min), energy saving, and cleanliness. The present apparatus permits fast and efficient extraction, reduces waste, avoids water and solvent consumption, and allows substantial energy savings.

  20. Effectiveness of convective drying to conserve indigenous yeasts with high volatile profile isolated from algerian fermented raw bovine milk (Rayeb

    Directory of Open Access Journals (Sweden)

    Latifa HAMOUDI-BELARBI

    2016-01-01

    Full Text Available Abstract Yeasts Candida tropicalis, Yarrowia lipolytica, Wickerhamomyces anomalus, Issatchenkia orientalis, Kluyveromyces marxianus, Saprochaete suaveolens and Trichosporon coremiiforme were isolated and identified by physiological, biochemical tests with API 20C AUX system and molecular methods by restriction fragment analysis of PCR-amplified 28S-rRNA from Algerian fermented raw bovine milk (Rayeb. Selected yeasts S. suaveolens, I. orientalis, K. marxianus and W. anomalus produced esters and higher esters which can exert a pertinent influence on the sensory characteristics of Rayeb. Viability of S. suaveolens and W. anomalus using three methods of drying (freeze-drying, convective drying, and spray-drying and during 4 months of storage at 4 °C and 25 °C in the darkness was studied. Immediately after each drying method, high survival was obtained using freeze-drying followed by convective drying in rice cakes and spray-drying respectively. During storage at 4 °C, convective drying provided better survival of yeast cultures of S. suaveolens and W. anomalus than freeze-drying. At 25 °C of storage, convective and freeze-dried yeast cultures showed no significant loss of viable cells up to 2 months of storage. Spray-dried yeast cultures had the greatest loss of viable count during the 3 months of storage at 25 °C.

  1. Measurement of hygroscopic strain in deodar wood during convective drying using lensless Fourier transform digial holography

    Science.gov (United States)

    Kumar, Manoj; Shakher, Chandra

    2016-04-01

    In this paper, moisture induced deformation and shrinkage behaviour of deodar wood during convective drying is experimentally investigated by using digital holographic interferometry. There induces dimensional changes in wood due to the moisture absorption and desorption. Lensless Fourier transform digital holographic interferometry (LLFTDH) is used to study the moisture induced deformation and strain distribution in deodar wood. The proposed technique having high sensitivity and enables the observation of deformation and strain distribution during the variations of moisture content in the deodar wood.

  2. Using a multiwavelength suite of microwave instruments to investigate the microphysical structure of deep convective cores

    Science.gov (United States)

    Battaglia, A.; Mroz, K.; Lang, Tim; Tridon, F.; Tanelli, S.; Tian, Lin; Heymsfield, Gerald M.

    2016-08-01

    Due to the large natural variability of its microphysical properties, the characterization of solid precipitation is a longstanding problem. Since in situ observations are unavailable in severe convective systems, innovative remote sensing retrievals are needed to extend our understanding of such systems. This study presents a novel technique able to retrieve the density, mass, and effective diameter of graupel and hail in severe convection through the combination of airborne microwave remote sensing instruments. The retrieval is applied to measure solid precipitation properties within two convective cells observed on 23-24 May 2014 over North Carolina during the IPHEx campaign by the NASA ER-2 instrument suite. Between 30 and 40 degrees of freedom of signal are associated with the measurements, which is insufficient to provide full microphysics profiling. The measurements have the largest impact on the retrieval of ice particle sizes, followed by ice water contents. Ice densities are mainly driven by a priori assumptions, though low relative errors in ice densities suggest that in extensive regions of the convective system, only particles with densities larger than 0.4 g/cm3 are compatible with the observations. This is in agreement with reports of large hail on the ground and with hydrometeor classification derived from ground-based polarimetric radars observations. This work confirms that multiple scattering generated by large ice hydrometeors in deep convection is relevant for airborne radar systems already at Ku band. A fortiori, multiple scattering will play a pivotal role in such conditions also for Ku band spaceborne radars (e.g., the GPM Dual Precipitation Radar).

  3. Heat and mass transfer analysis of convective drying of chickpea (Cicer arietinum)

    Science.gov (United States)

    López, R.; Vaca, M.; Terres, H.; Lizardi, A.; Morales, J.; Flores, J.; Chávez, S.

    2015-01-01

    The objective of this article is to describe the modelling and simulation of the dehydration of chickpea in a complex drying system process, using COMSOL Multiphysics Program. A model, based on mass and energy balances, was developed for the simulation of unsteady convective drying with air (3.0 m/s and 60 °C). The program predicted an 8 hours-dehydration time, with an effective moisture diffusivity of 3.1 *10- 10 which was experimentally obtained. The empirical model that best represented the process was the exponential one.

  4. Convective drying of hawthorn fruit (Crataegus spp.): Effect of experimental parameters on drying kinetics, color, shrinkage, and rehydration capacity.

    Science.gov (United States)

    Aral, Serdar; Beşe, Ayşe Vildan

    2016-11-01

    Thin layer drying characteristics and physicochemical properties of hawthorn fruit (Crataegus spp.) were investigated using a convective dryer at air temperatures 50, 60 and 70°C and air velocities of 0.5, 0.9 and 1.3m/s. The drying process of hawthorn took place in the falling rate period, and the drying time decreased with increasing air temperature and velocity. The experimental data obtained during the drying process were fitted to eleven different mathematical models. The Midilli et al.'s model was found to be the best appropriate model for explaining the drying behavior of hawthorn fruit. Effective moisture diffusion coefficients (Deff) were calculated by Fick's diffusion model and their values varied from 2.34×10(-10)m(2)/s to 2.09×10(-9)m(2)/s. An Arrhenius-type equation was applied to determine the activation energies. While the shrinkage decreased, the rehydration ratio increased with increasing air temperature and air velocity. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Single layer solar drying behaviour of Citrus aurantium leaves under forced convection

    Energy Technology Data Exchange (ETDEWEB)

    Ait Mohamed, L.; Lahsasni, S. [Ecole Normale Superieure, Marrakech (Morocco). Laboratoire d' Energie Solaire et des Plantes Aromatiques et Medicinales; Unite de Chimie Agroalimentaire, Marrakech (Morocco). Faculte des Sciences Semlalia; Kouhila, M.; Jamali, A. [Ecole Normale Superieure, Marrakech (Morocco). Laboratoire d' Energie Solaire et des Plantes Aromatiques et Medicinales; Kechaou, N. [Ecole Nationale d' Ingenieurs de Sfax (Tunisia); Mahrouz, M. [Unite de Chimie Agroalimentaire, Marrakech (Morocco). Faculte des Sciences Semlalia

    2005-06-01

    Convective solar drying experiments in thin layers of Citrus aurantium leaves grown in Marrakech, morocco, were conducted. An indirect forced convection solar dryer consisting of a solar air collector, an auxiliary heater, a circulation fan and a drying cabinet is used for the experiments. The air temperature was varied from 50 to 60{sup o}C; the relative humidity from 41% to 53%; and the drying air flow rate from 0.0277 to 0.0833 m{sup 3}/s. Thirteen statistical models, which are semi-theoretical and/or empirical, were tested for fitting the experimental data. A nonlinear regression analysis using a statistical computer program was used to evaluate the constants of the models. The Midilli-Kucuk drying model was found to be the most suitable for describing the solar drying curves of Citrus aurantium leaves with a correlation coefficient (r) of 0.99998, chi-square ({chi}{sup 2}) of 4.664 x 10{sup -6} and MBE of 4.8381 x 10{sup -4}. (author)

  6. Enhancing Oxidative Stability of Sunflower Oil during Convective and Microwave Heating Using Grape Seed Extract

    Directory of Open Access Journals (Sweden)

    Mariana-Atena Poiana

    2012-07-01

    Full Text Available This study was performed to investigate the effectiveness of grape seed extract (GSE compared to butylated hydroxytoluene (BHT on retarding lipid oxidation of sunflower oil subjected to convection and microwave heating up to 240 min under simulated frying conditions. The progress of lipid oxidation was assessed in terms of peroxide value (PV, p-anisidine value (p-AV, conjugated dienes and trienes (CD, CT, inhibition of oil oxidation (IO and TOTOX value. In addition, total phenolic content (TP was evaluated in samples before and after heating in order to assess the changes in these compounds relative to the extent of lipid oxidation. The results of this study highlight that GSE showed a significantly inhibitory effect on lipid oxidation during both treatments, although to a different extent. This ability was dose-dependent; therefore, the extent of lipid oxidation was inversely related to GSE level. Convective heating, respective microwave exposure for 240 min of samples supplemented by GSE to a level of 1000 ppm, resulted in significant decreases of investigated indices relative to the control values as follows: PV (48%; 30%, p-AV (29%; 40%, CD (45%; 30%, CT (41%; 36%, TOTOX (35%; 37%. GSE to a level of 600–800 ppm inhibited the lipid oxidation in a similar manner to BHT. These results suggested that GSE can be used as a potential natural extract for improving oxidative stability of sunflower oil during thermal applications.

  7. Enhancing oxidative stability of sunflower oil during convective and microwave heating using grape seed extract.

    Science.gov (United States)

    Poiana, Mariana-Atena

    2012-01-01

    This study was performed to investigate the effectiveness of grape seed extract (GSE) compared to butylated hydroxytoluene (BHT) on retarding lipid oxidation of sunflower oil subjected to convection and microwave heating up to 240 min under simulated frying conditions. The progress of lipid oxidation was assessed in terms of peroxide value (PV), p-anisidine value (p-AV), conjugated dienes and trienes (CD, CT), inhibition of oil oxidation (IO) and TOTOX value. In addition, total phenolic content (TP) was evaluated in samples before and after heating in order to assess the changes in these compounds relative to the extent of lipid oxidation. The results of this study highlight that GSE showed a significantly inhibitory effect on lipid oxidation during both treatments, although to a different extent. This ability was dose-dependent; therefore, the extent of lipid oxidation was inversely related to GSE level. Convective heating, respective microwave exposure for 240 min of samples supplemented by GSE to a level of 1000 ppm, resulted in significant decreases of investigated indices relative to the control values as follows: PV (48%; 30%), p-AV (29%; 40%), CD (45%; 30%), CT (41%; 36%), TOTOX (35%; 37%). GSE to a level of 600-800 ppm inhibited the lipid oxidation in a similar manner to BHT. These results suggested that GSE can be used as a potential natural extract for improving oxidative stability of sunflower oil during thermal applications.

  8. Modeling of convective drying kinetics of Pistachio kernels in a fixed bed drying system

    Directory of Open Access Journals (Sweden)

    Balbay Asım

    2013-01-01

    Full Text Available Drying kinetics of Pistachio kernels (PKs with initial moisture content of 32.4% (w.b was investigated as a function of drying conditions in a fixed bed drying system. The drying experiments were carried out at different temperatures of drying air (40, 60 and 80°C and air velocities (0.05, 0.075 and 0.1 m/s. Several experiments were performed in terms of mass of PKs (15g and 30g using a constant air velocity of 0.075 m/s. The fit quality of models was evaluated using the determination coefficient (R2, sum square error (SSE and root mean square error (RMSE. Among the selected models, the Midilli et al model was found to be the best models for describing the drying behavior of PKs. The activation energies were calculated as 29.2 kJ/mol and effective diffusivity values were calculated between 1.38 and 4.94x10-10 m2/s depending on air temperatures.

  9. Mediterranean hurricanes: large-scale environment and convective and precipitating areas from satellite microwave observations

    Directory of Open Access Journals (Sweden)

    C. Claud

    2010-10-01

    Full Text Available Subsynoptic scale vortices that have been likened to tropical cyclones or polar lows (medicanes are occasionally observed over the Mediterranean Sea. Generated over the sea, they are usually associated with strong winds and heavy precipitation and thus can be highly destructive in islands and costal areas. Only an accurate forecasting of such systems could mitigate these effects. However, at the moment, the predictability of these systems remains limited.

    Due to the scarcity of conventional observations, use is made of NOAA/MetOp satellite observations, for which advantage can be taken of the time coverage differences between the platforms that carry it, to give a very complete temporal description of the disturbances. A combination of AMSU-B (Advanced Microwave Sounding Unit-B/MHS (Microwave Humidity Sounder observations permit to investigate precipitation associated with these systems while coincident AMSU-A (Advanced Microwave Sounding Unit-A observations give insights into the larger synoptic-scale environment in which they occur.

    Three different cases (in terms of intensity, location, trajectory, duration, and periods of the year – May, September and December, respectively were investigated. Throughout these time periods, AMSU-A observations show that the persisting deep outflow of cold air over the sea together with an upper-level trough upstream constituted a favourable environment for the development of medicanes. AMSU-B/MHS based diagnostics show that convection and precipitation areas are large in the early stage of the low, but significantly reduced afterwards. Convection is maximum just after the upper-level trough, located upstream of cold mid-tropospheric air, reached its maximum intensity and acquired a cyclonic orientation.

  10. Microwave and blanch-assisted drying of white yam (Dioscorea rotundata).

    Science.gov (United States)

    Abano, Ernest Ekow; Amoah, Robert Sarpong

    2015-11-01

    The effect of microwave and blanch pretreatments on the drying kinetics and quality of white yam (Dioscorea rotundata) was investigated. Yam cubes destined for hot air drying at temperatures 70-90°C were predried in a domestic microwave or blanched in hot water for 1-5 min. Microwave pretreatment time had a positive significant effect on drying rate but both pretreatments had a negative influence on the ascorbic acid content and the nonenzymatic browning. The optimum drying conditions were a microwave pretreatment time of 5 min and a temperature of 70°C and a blanching time of 1 min at a temperature of 80°C. Among the models fitted, the Midilli et al. and the Page models gave the best fits for yam cubes predried with microwave and blanch, respectively. The effective moisture diffusivity for microwave-assisted drying increased from 1.05 × 10(-8 )m(2 )s(-1) to 2.00 × 10(-8) m(2 )s(-1) while the hot water blanched samples decreased from 1.53 × 10(-8) to 8.81 × 10(-9 )m(2 )s(-1) with time. The study demonstrates that microwave-assisted drying could be used to enhance heat and mass transfer processes to produce better quality dried yam products.

  11. Studies on the Prevention of Over Heating on Microwave Heated Drying of Foods

    OpenAIRE

    1992-01-01

    In previous papers (KUBOTA et al., 1990; Lu et al, 1990B), we have studied a convenient microwave heated drying instrument, and studied the simple drying-rate equations of potato and so on by using some shapes of samples. The browning according the temperature rises increased by increasing size of potato samples, and the browning location depended on the shape of samples. And then, we have studied the relationships between the size andlor shape and the browning on microwave heated drying of p...

  12. Thin Layer Modeling of the Convective Drying of Barberry Fruit (Berberis vulgaris

    Directory of Open Access Journals (Sweden)

    Akram Sharifi

    2013-04-01

    Full Text Available In this study, the drying kinetics of seedless barberry fruit was studied at 55, 65 and 75˚C air temperatures and 1±0.2 m/s air velocity in a laboratory thin layer dryer with forced convection. Samples were subjected to two different pretreatments (citric acid and vapor. The drying of seedless barberry fruit took place in the falling rate drying period. Ten thin layer-drying models were fitted to the experimental moisture ratio. Compared with other models the Midilli et al. (2002 drying model was found to satisfactorily describe the drying curves of barberry with highest amounts of coefficient of determination (r2 and lowest amounts of reduced chi-square(x2, Mean Bias Error (MBE and Root Mean Square Error (RMSE. The effective moisture diffusivity (Deff of barberry increased as the drying air temperature increased. An Arrhenius relation with activation energy values of 45.577 kJ/mol (citric acid pretreatment expressed the effect of temperature on the diffusivity.

  13. Drying kinetics of apricot halves in a microwave-hot air hybrid oven

    Science.gov (United States)

    Horuz, Erhan; Bozkurt, Hüseyin; Karataş, Haluk; Maskan, Medeni

    2017-01-01

    Drying behavior and kinetics of apricot halves were investigated in a microwave-hot air domestic hybrid oven at 120, 150 and 180 W microwave power and 50, 60 and 70 °C air temperature. Drying operation was finished when the moisture content reached to 25% (wet basis) from 77% (w.b). Increase in microwave power and air temperature increased drying rates and reduced drying time. Only falling rate period was observed in drying of apricot halves in hybrid oven. Eleven mathematical models were used for describing the drying kinetics of apricots. Modified logistic model gave the best fitting to the experimental data. The model has never been used to explain drying behavior of any kind of food materials up to now. Fick's second law was used for determination of both effective moisture diffusivity and thermal diffusivity values. Activation energy values of dried apricots were calculated from Arrhenius equation. Those that obtained from effective moisture diffusivity, thermal diffusivity and drying rate constant values ranged from 31.10 to 39.4 kJ/mol, 29.56 to 35.19 kJ/mol, and 26.02 to 32.36 kJ/mol, respectively.

  14. Drying kinetics of apricot halves in a microwave-hot air hybrid oven

    Science.gov (United States)

    Horuz, Erhan; Bozkurt, Hüseyin; Karataş, Haluk; Maskan, Medeni

    2017-06-01

    Drying behavior and kinetics of apricot halves were investigated in a microwave-hot air domestic hybrid oven at 120, 150 and 180 W microwave power and 50, 60 and 70 °C air temperature. Drying operation was finished when the moisture content reached to 25% (wet basis) from 77% (w.b). Increase in microwave power and air temperature increased drying rates and reduced drying time. Only falling rate period was observed in drying of apricot halves in hybrid oven. Eleven mathematical models were used for describing the drying kinetics of apricots. Modified logistic model gave the best fitting to the experimental data. The model has never been used to explain drying behavior of any kind of food materials up to now. Fick's second law was used for determination of both effective moisture diffusivity and thermal diffusivity values. Activation energy values of dried apricots were calculated from Arrhenius equation. Those that obtained from effective moisture diffusivity, thermal diffusivity and drying rate constant values ranged from 31.10 to 39.4 kJ/mol, 29.56 to 35.19 kJ/mol, and 26.02 to 32.36 kJ/mol, respectively.

  15. Non-polar Solvent Microwave-Assisted Extraction of Volatile Constituents from Dried Zingiber Officinale Rosc.

    Institute of Scientific and Technical Information of China (English)

    YU Yong; WANG Zi-Ming; WANG Yu-Tang; LI Tie-Chun; CHENG Jian-Hua; LIU Zhong-Ying; ZHANG Han-Qi

    2007-01-01

    A new method, non-polar solvent microwave-assisted extraction (NPSMAE), was applied to the extraction of essential oil from Zingiber officinale Rosc. in closed-vessel system. By adding microwave absorption mediumcarbonyl iron powders (CIP) into extraction system, the essential oil was extracted by the non-polar solvent (ether)which can be heated by CIP. The constituents of essential oil obtained by NPSMAE were comparable with those obtained by hydrodistillation (HD) by GC-MS analysis, which indicates that NPSMAE is a feasible way to extract essential oil from dried plant materials. The NPSMAE took much less extraction time (5 min) than HD (180 min),and its extraction efficiency was much higher than that of conventional polar solvent microwave-assisted extraction (PSMAE) and mixed solvent microwave-assisted extraction (MSMAE). It can be a good alternative for the extraction of volatile constituents from dried plant samples.

  16. Comparative study of denaturation of whey protein isolate (WPI) in convective air drying and isothermal heat treatment processes.

    Science.gov (United States)

    Haque, M Amdadul; Aldred, Peter; Chen, Jie; Barrow, Colin J; Adhikari, Benu

    2013-11-15

    The extent and nature of denaturation of whey protein isolate (WPI) in convective air drying environments was measured and analysed using single droplet drying. A custom-built, single droplet drying instrument was used for this purpose. Single droplets having 5±0.1μl volume (initial droplet diameter 1.5±0.1mm) containing 10% (w/v) WPI were dried at air temperatures of 45, 65 and 80°C for 600s at constant air velocity of 0.5m/s. The extent and nature of denaturation of WPI in isothermal heat treatment processes was measured at 65 and 80°C for 600s and compared with those obtained from convective air drying. The extent of denaturation of WPI in a high hydrostatic pressure environment (600MPa for 600s) was also determined. The results showed that at the end of 600s of convective drying at 65°C the denaturation of WPI was 68.3%, while it was only 10.8% during isothermal heat treatment at the same medium temperature. When the medium temperature was maintained at 80°C, the denaturation loss of WPI was 90.0% and 68.7% during isothermal heat treatment and convective drying, respectively. The bovine serum albumin (BSA) fraction of WPI was found to be more stable in the convective drying conditions than β-lactoglobulin and α-lactalbumin, especially at longer drying times. The extent of denaturation of WPI in convective air drying (65 and 80°C) and isotheral heat treatment (80°C) for 600s was found to be higher than its denaturation in a high hydrostatic pressure environment at ambient temperature (600MPa for 600s).

  17. Enhancement of convective drying by application of airborne ultrasound - a response surface approach.

    Science.gov (United States)

    Beck, Svenja M; Sabarez, Henry; Gaukel, Volker; Knoerzer, Kai

    2014-11-01

    Drying is one of the oldest and most commonly used processes in the food manufacturing industry. The conventional way of drying is by forced convection at elevated temperatures. However, this process step often requires a very long treatment time, is highly energy consuming and detrimental to the product quality. Therefore, an investigation of whether the drying time and temperature can be reduced with the assistance of an airborne ultrasound intervention is of interest. Previous studies have shown that contact ultrasound can accelerate the drying process. It is assumed that mechanical vibrations, creating micro channels in the food matrix or keeping these channels from collapsing upon drying, are responsible for the faster water removal. In food samples, due to their natural origin, drying is also influenced by fluctuations in tissue structure, varying between different trials. For this reason, a model food system with thermo-physical properties and composition (water, cellulose, starch, fructose) similar to those of plant-based foods has been used in this study. The main objective was, therefore, to investigate the influence of airborne ultrasound conditions on the drying behaviour of the model food. The impact of airborne ultrasound at various power levels, drying temperature, relative humidity of the drying air, and the air speed was analysed. To examine possible interactions between these parameters, the experiments were designed with a Response Surface Method using Minitab 16 Statistical Software (Minitab Inc., State College, PA, USA). In addition, a first attempt at improving the process conditions and performance for better suitability and applicability in industrial scale processing was undertaken by non-continuous/intermittent sonication.

  18. Transitional dispersive scenarios driven by mesoscale flows on complex terrain under strong dry convective conditions

    Directory of Open Access Journals (Sweden)

    J. L. Palau

    2009-01-01

    Full Text Available By experimentation and modelling, this paper analyses the atmospheric dispersion of the SO2 emissions from a power plant on complex terrain under strong convective conditions, describing the main dispersion features as an ensemble of "stationary dispersive scenarios" and reformulating some "classical" dispersive concepts to deal with the systematically monitored summer dispersive scenarios in inland Spain. The results and discussions presented arise from a statistically representative study of the physical processes associated with the multimodal distribution of pollutants aloft and around a 343-m-tall chimney under strong dry convective conditions in the Iberian Peninsula. This paper analyses the importance of the identification and physical implications of transitional periods for air quality applications. The indetermination of a transversal plume to the preferred transport direction during these transitional periods implies a small (or null physical significance of the classical definition of horizontal standard deviation of the concentration distribution.

  19. Simultaneous Heat and Mass Transfer Model for Convective Drying of Building Material

    Science.gov (United States)

    Upadhyay, Ashwani; Chandramohan, V. P.

    2016-06-01

    A mathematical model of simultaneous heat and moisture transfer is developed for convective drying of building material. A rectangular brick is considered for sample object. Finite-difference method with semi-implicit scheme is used for solving the transient governing heat and mass transfer equation. Convective boundary condition is used, as the product is exposed in hot air. The heat and mass transfer equations are coupled through diffusion coefficient which is assumed as the function of temperature of the product. Set of algebraic equations are generated through space and time discretization. The discretized algebraic equations are solved by Gauss-Siedel method via iteration. Grid and time independent studies are performed for finding the optimum number of nodal points and time steps respectively. A MATLAB computer code is developed to solve the heat and mass transfer equations simultaneously. Transient heat and mass transfer simulations are performed to find the temperature and moisture distribution inside the brick.

  20. Thin layer convective air drying of wild edible plant (Allium roseum) leaves: experimental kinetics, modeling and quality.

    Science.gov (United States)

    Ben Haj Said, Leila; Najjaa, Hanen; Farhat, Abdelhamid; Neffati, Mohamed; Bellagha, Sihem

    2015-06-01

    The present study deals with the valorization of an edible spontaneous plant of the Tunisian arid areas: Allium roseum. This plant is traditionally used for therapeutic and culinary uses. Thin-layer drying behavior of Allium roseum leaves was investigated at 40, 50 and 60 °C drying air temperatures and 1 and l.5 m/s air velocity, in a convective dryer. The increase in air temperature significantly affected the moisture loss and reduced the drying time while air velocity was an insignificant factor during drying of Allium roseum leaves. Five models selected from the literature were found to satisfactorily describe drying kinetics of Allium roseum leaves for all tested drying conditions. Drying data were analyzed to obtain moisture diffusivity values. During the falling rate-drying period, moisture transfer from Allium roseum leaves was described by applying the Fick's diffusion model. Moisture diffusivity varied from 2.55 × 10(-12) to 8.83 × 10(-12) m(2)/s and increased with air temperature. Activation energy during convective drying was calculated using an exponential expression based on Arrhenius equation and ranged between 46.80 and 52.68 kJ/mol. All sulfur compounds detected in the fresh leaves were detected in the dried leaves. Convective air drying preserved the sulfur compounds potential formation.

  1. Computational analysis of heat and mass transfer during microwave drying of timber

    Directory of Open Access Journals (Sweden)

    Kadem S.

    2016-01-01

    Full Text Available The need for improvement in engineering design and process optimization for microwave drying of wood has stimulated the development of computer simulation techniques to predict temperature and moisture history and distribution wood sample. A three-dimensional comprehensive heat and mass transfer model was developed to simulate the free liquid, vapor, and bound water movement including consideration of internal heat generation in microwave drying of yellow poplar specimens. The model was solved using the finite element analysis with FEMLsoftware. The model predictions compared favorably with predicted and experimental solutions. The effect of changes of the most important parameters on the predictions of the model is also presented. The results showed that the variations of irradiation time, microwave power level and sample thickness played an important role in overall drying kinetics.

  2. Performance of a Forced-Convection Greenhouse Dryer for Fish Drying

    Directory of Open Access Journals (Sweden)

    Martunis Martunis

    2013-04-01

    Full Text Available ABSTRACT. This research present experimental performance of a forced convection greenhouse dryer for drying of fish. The greenhouse dryer was installed at Aceh province, Indonesia. It has a concrete floor with the area of 6×4 m2. The roof of dryer is built in semi-cylindrical shape and covered with transparent polycarbonate sheets. Two axial flow fans powered by a 50-watt solar cell module was used to generate forced convection for ventilating the dryer.To investigate its performance, the dryer was used to dry two batches of fish. The Results showed that to dry 50 kg fish with initial moisture 68 % required 11 hours. Incontrast, to dry the same amount of fish using sun drying take a time about 2 days. The air temperature inside greenhouse dryer at noon in the clear day was 45-55°C. Kinerja Pengering Rumah Kaca Dengan Metode Konveksi Paksa Untuk Pengeringan Ikan ABSTRAK. Penelitian ini memperlihatkan hasil percobaan terhadap kinerja pengering rumah kaca dengan metode konveksi udara secara paksa pada pengeringan ikan. Penelitian pengering rumah kaca ini dilakukan di Propinsi Aceh, Indonesia. Pengering ini berlantaikan beton dengan luas sebesar 6x4 m2. .Atapnya dibuat berbentuk semi-selinder dan ditutup dengan lembaran plastik transparan berbahan polikarbonat. Dua buah kipas dengan aliran udara secara aksial dipasang dengan sumber daya berasal dari panel surya sebesar 50 Watt dan dipakai untuk menghasilkan konveksi udara paksa pada ventilasi pengering. Untuk menginvestigasi kinerja rumah kaca ini, pengering ini digunakan untuk mengeringkan dua tumpukan ikan. Hasilnya menunjukkan bahwa untuk mengeringkan sebanyak 50 kg ikan dengan kadar air awalnya sebesar 68% membutuhkan waktu selama 11 jam. Sebaliknya, dengan menggunakan sinar matahari secara langsung, untuk mengeringkan ikan dengan jumlah yang sama, maka waktu yang dibutuhkan lebih lama yaitu sekitar 2 hari. Suhu udara di dalam rumah pengering tepat pada siang hari yang cerah berkisar antara 45

  3. 1D-Var temperature retrievals from microwave radiometer and convective scale model

    Directory of Open Access Journals (Sweden)

    Pauline Martinet

    2015-12-01

    Full Text Available This paper studies the potential of ground-based microwave radiometers (MWR for providing accurate temperature retrievals by combining convective scale numerical models and brightness temperatures (BTs. A one-dimensional variational (1D-Var retrieval technique has been tested to optimally combine MWR and 3-h forecasts from the French convective scale model AROME. A microwave profiler HATPRO (Humidity and Temperature PROfiler was operated during 6 months at the meteorological station of Bordeaux (Météo France. MWR BTs were monitored against simulations from the Atmospheric Radiative Transfer Simulator 2 radiative transfer model. An overall good agreement was found between observations and simulations for opaque V-band channels but large errors were observed for channels the most affected by liquid water and water vapour emissions (51.26 and 52.28 GHz. 1D-Var temperature retrievals are performed in clear-sky and cloudy conditions using a screening procedure based on cloud base height retrieval from ceilometer observations, infrared radiometer temperature and liquid water path derived from the MWR observations. The 1D-Var retrievals were found to improve the AROME forecasts up to 2 km with a maximum gain of approximately 50 % in root-mean-square-errors (RMSE below 500 m. They were also found to outperform neural network retrievals. A static bias correction was proposed to account for systematic instrumental errors. This correction was found to have a negligible impact on the 1D-Var retrievals. The use of low elevation angles improves the retrievals up to 12 % in RMSE in cloudy-sky in the first layers. The present implementation achieved a RMSE with respect to radiosondes within 1 K in clear-sky and 1.3 K in cloudy-sky conditions for temperature.

  4. A MATHEMATICAL MODEL OF THE PROCESS OF RADIATION-CONVECTIVE DRYING FRUIT AND VEGETA- BLE CHIPS WITH PULSED ENERGY SUPPLY

    Directory of Open Access Journals (Sweden)

    A. N. Ostrikov

    2013-01-01

    Full Text Available A mathematical model of combined radiation and convection drying of fruit and vegetable chips with pulsed energy supply is developed, the model describes the change in temperature and moisture content during the period of constant and periods of decreasing drying rate.

  5. Numerical analysis of convective drying of a moist object with combined internal and external heat and mass transfer

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Donghyun; Son, Gihun [Sogang University, Seoul (Korea, Republic of); Kim, Sungil [Korea Institute of Energy Research, Daejeon (Korea, Republic of)

    2016-02-15

    A numerical approach is developed for computing convective drying of a moist object. The conservation equations of mass, momentum, energy and moisture in the internal and external regions of an object are solved with the coupled heat and mass transfer conditions on the object surface, including the effect of evaporation. A numerical approach is applied to predict the internal and external temperature and moisture distributions during the convective drying with variations in the initial moisture content and the water activity. The numerical results show that the water activity is an important parameter for determining the drying rate pattern and the analogy between the heat and mass transfer on the object surface.

  6. Modeling and numerical analysis of an atypical convective coal drying process

    Energy Technology Data Exchange (ETDEWEB)

    Stakic, M.; Tsotsas, E. [Otto von Guericke University, Magdeburg (Germany)

    2004-07-01

    This work presents modeling and numerical simulation of batch convective coal drying in a deep packed bed after a high-pressure steam treatment (a part of the Fleissner coal drying process). The process is atypical, because ambient air is used to dry, and cool hot particles, while usually, e.g., in the deep packed bed drying of biomaterials, hot air is contacting cold particles. Product-specific data (intraparticle mass transfer, gas-solids moisture equilibrium) for coal (here lignite) are taken from the literature. Available data on coal drying in packed beds of medium height are used for model validation. Then, the model is applied to the considered industrial process. The design point of the process is critically reviewed, and alternatives are developed by systematically simulating the influence of inlet air conditions (temperature, humidity, flow-rate) and coal particle size. This type of analysis is necessary for efficiently scheduling plant dryers, since coal particle size may change, and air inlet temperature and humidity are changing with the ambient conditions.

  7. 2-D hydro-viscoelastic model for convective drying of deformable and unsaturated porous material

    Science.gov (United States)

    Hassini, Lamine; Raja, Lamloumi; Lecompte-Nana, Gisèle Laure; Elcafsi, Mohamed Afif

    2017-04-01

    The aim of this work was to simulate in two dimensions the spatio-temporal evolution of the moisture content, the temperature, the solid (dry matter) concentration, the dry product total porosity, the gas porosity, and the mechanical stress within a deformable and unsaturated product during convective drying. The material under study was an elongated cellulose-clay composite sample with a square section placed in hot air flow. Currently, this innovative composite is used in the processing of boxes devoted to the preservation of heritage and precious objects against fire damage and other degradation (moisture, insects, etc.). A comprehensive and rigorous hydrothermal model had been merged with a dynamic linear viscoelasticity model based on Bishop's effective stress theory, assuming that the stress tensor is the sum of solid, liquid, and gas stresses. The material viscoelastic properties were measured by means of stress relaxation tests for different water contents. The viscoelastic behaviour was described by a generalized Maxwell model whose parameters were correlated to the water content. The equations of our model were solved by means of the 'COMSOL Multiphysics' software. The hydrothermal part of the model was validated by comparison with experimental drying curves obtained in a laboratory hot-air dryer. The simulations of the spatio-temporal distributions of mechanical stress were performed and interpreted in terms of material potential damage. The sample shape was also predicted all over the drying process.

  8. Effect of Selected Factors on Drying Process of Tomato in Forced Convection Solar Energy Dryer

    Directory of Open Access Journals (Sweden)

    U.S. Muhammed

    2012-09-01

    Full Text Available The effect of air velocity, slice thickness and grazing materials in drying process of tomato in forced convection solar energy dryer was evaluated. The result is to serve as an input for solar energy development for drying of vegetable and fruit products in North West Ecological zone of Nigeria. In order to evaluate the effects of the above factors in drying operation, a split-split-plot experimental design was used. Differences among the treatments and their interactions were tested with orthogonal contrast test to access their significance while further analysis were done to compare all possible pairs of treatment means using Duncan’s Multiple Range Test (DMRT. The results showed that there is no significant difference, at 95% probability level, between the means of the three glazing materials used. However, the variations in mean slice thickness and in mean air flow rate are highly significant at 99% probability level. The results further revealed that drying rate increasing with decrease in slice thickness and increase in air flow rate. Drying of 15, 20 and 25 mm slice thickness of tomato was achieved in time range of 21-24, 27-29 and 30-50 h, respectively.

  9. Effect of Thermophysical Properties on Coupled Heat and Mass Transfer in Porous Material during Forced Convective Drying

    Directory of Open Access Journals (Sweden)

    Wei Cai

    2014-06-01

    Full Text Available The convective drying kinetics of porous medium was investigated numerically. A mathematical model for forced convective drying was established to estimate the evolution of moisture content and temperature inside multilayered porous medium. The set of coupled partial differential equations with the specified boundary and initial conditions were solved numerically using a MATLAB code. An experimental setup of convective drying had been constructed and validated the theoretical model. The temperature and moisture content of the potato samples were dynamically measured and recorded during the drying process. Results indicate that thermal diffusion coefficient has significant positive impact on temperature distribution and mass diffusion coefficient might directly affect the moisture content distribution. Soret effect has a significant impact on heat flux and temperature distribution in the presence of large temperature gradient.

  10. Optimization of microwave vacuum drying of lotus (Nelumbo nucifera Gaertn.) seeds by response surface methodology.

    Science.gov (United States)

    Tian, Yuting; Zhang, Yi; Zeng, Shaoxiao; Zheng, Yafeng; Chen, Feng; Guo, Zhebin; Lin, Yufei; Zheng, Baodong

    2012-10-01

    Drying is the main process used to treat lotus seeds for storage. In this study, response surface methodology was used to optimize processing methods for microwave vacuum (MWV) drying of lotus seeds and to create a desirable product. A central composite design with three important factors: microwave output power (2.0-4.0 kW), vacuum degree (-0.070 to -0.090 MPa) and on/off ratio (68/52 s to 99/21 s) was used to study the response variables of drying time, shrinkage ratio, rehydration ratio and whiteness index. The optimum conditions for MWV drying of lotus seeds were determined to obtain a minimal drying time, minimal shrinkage ratio, maximum rehydration ratio and maximum whiteness index. The optimum drying conditions were found to be: microwave output power 3.2 kW, vacuum degree -0.083 MPa and on/off ratio 94/26 s. Under these optimal conditions, drying time, shrinkage ratio, rehydration ratio and whiteness index were found to be 10 min, 37.66%, 157.1% and 68.83, respectively.

  11. Tensile strength of type IV dental stones dried in a microwave oven.

    Science.gov (United States)

    Hersek, Nur; Canay, Senay; Akça, Kivanç; Ciftçi, Yalçin

    2002-05-01

    It is known that drying dental stones in a microwave oven can save time, but the strength of the material may be affected by different drying methods. This study evaluated the diametral tensile strength (DTS) of 5 type IV gypsum products at different time intervals using microwave and air-drying methods. . A total of 300 cylinder specimens were prepared from 5 type IV dental stones (Moldano, Amberok, Herastone, Shera-Sockel, and Fujirock; n = 60 per stone) in accordance with the manufacturers' recommendations. Half of the specimens of each stone (n = 30) were dried in open air within a temperature range of 20 +/- 2 degrees C; the other half (n = 30) underwent initial setting in a silicone rubber mold in open air for 10 minutes and then were dried in a microwave oven for 10 minutes. Within these groups, 10 specimens were tested under diametral compression at each of the following time periods: 30, 60, and 120 minutes after drying. Three-way analysis of variance and Scheffe's post hoc test were performed for statistical comparisons at a significance level of Pmicrowave oven (mean 2.99 MPa) were significantly higher (Pmicrowave oven drying had a positive effect on the diametral tensile strength of 5 type IV dental stones.

  12. Comparison of Mathematical Equation and Neural Network Modeling for Drying Kinetic of Mendong in Microwave Oven

    Science.gov (United States)

    Maulidah, Rifa'atul; Purqon, Acep

    2016-08-01

    Mendong (Fimbristylis globulosa) has a potentially industrial application. We investigate a predictive model for heat and mass transfer in drying kinetics during drying a Mendong. We experimentally dry the Mendong by using a microwave oven. In this study, we analyze three mathematical equations and feed forward neural network (FNN) with back propagation to describe the drying behavior of Mendong. Our results show that the experimental data and the artificial neural network model has a good agreement and better than a mathematical equation approach. The best FNN for the prediction is 3-20-1-1 structure with Levenberg- Marquardt training function. This drying kinetics modeling is potentially applied to determine the optimal parameters during mendong drying and to estimate and control of drying process.

  13. Fast Determination of Essential Oil from Dried Menthol Mint and Orange Peel by Solvent Free Microwave Extraction Using Carbonyl Iron Powder as the Microwave Absorption Medium

    Institute of Scientific and Technical Information of China (English)

    WANG Zi-Ming; DING Lan; WANG Lu; FENG Jin; LI Tie-Chun; ZHOU Xin; ZHANG Han-Qi

    2006-01-01

    An improved solvent free microwave extraction, in which a kind of microwave absorption medium (carbonyl iron powder) was used, was applied to the extraction of essential oil from dried menthol mint and orange peel without addition of any solvent and pretreatment. It took much less time of extraction (30 min) than microwave-assisted hydrodistillation (90 min) and conventional hydrodistillation (180 min). The kinds of chemical compositions in essential oil extracted by different methods were almost the same and such improved solvent free microwave extraction can be a feasible way in extraction of essential oil from dried plant materials.

  14. Evidence of Convective Redistribution of Carbon Monoxide in Aura Tropospheric Emission Sounder (TES) and Microwave Limb Sounder (MLS) Observations

    Science.gov (United States)

    Manyin, Michael; Douglass, Anne; Schoeberl, Mark

    2010-01-01

    Vertical convective transport is a key element of the tropospheric circulation. Convection lofts air from the boundary layer into the free troposphere, allowing surface emissions to travel much further, and altering the rate of chemical processes such as ozone production. This study uses satellite observations to focus on the convective transport of CO from the boundary layer to the mid and upper troposphere. Our hypothesis is that strong convection associated with high rain rate regions leads to a correlation between mid level and upper level CO amounts. We first test this hypothesis using the Global Modeling Initiative (GMI) chemistry and transport model. We find the correlation is robust and increases as the precipitation rate (the strength of convection) increases. We next examine three years of CO profiles from the Tropospheric Emission Sounder (TES) and Microwave Limb Sounder (MLS) instruments aboard EOS Aura. Rain rates are taken from the Tropical Rainfall Measuring Mission (TRMM) 3B-42 multi-satellite product. Again we find a correlation between mid-level and upper tropospheric CO, which increases with rain rate. Our result shows the critical importance of tropical convection in coupling vertical levels of the troposphere in the transport of trace gases. The effect is seen most clearly in strong convective regions such as the Inter-tropical Convergence Zone.

  15. Mathematical modeling of the drying of orange bagasse associating the convective method and infrared radiation

    Directory of Open Access Journals (Sweden)

    Carolina M. Sánchez-Sáenz

    2015-12-01

    Full Text Available ABSTRACT Mathematical modeling enables dimensioning of dryers, optimization of drying conditions and the evaluation of process performance. The aim of this research was to describe the behavior of orange bagasse drying using Page's and Fick's second law models, and to assess activation energy (using Arrhenius equation, moisture content, water activity and bulk density of product at the end of the process. The drying experimental assays were performed in 2011 with convective air temperature between 36 and 64 ºC and infrared radiation application time in the range from 23 to 277 s in accordance with the experimental central composite rotatable design. Analysis of variance and F-test were applied to results. At the end of the drying process, moisture content was about 0.09 to 0.87 db and water activity was between 0.25 and 0.87. Bulk density did not vary under studied conditions. Empirical Page's model demonstrated better representation of experimental data than the Fick's model for spheres. Activation energy values were about 18.491; 14.975 and 11.421 kJ mol-1 for infrared application times of 60; 150 e 244 s, respectively.

  16. Kinetics modeling of the drying of sunflower stem (Helianthus annuus L.) in a forced convection tunnel

    Science.gov (United States)

    López, R.; Vaca, M.; Terres, H.; Lizardi, A.; Morales, J.; Flores, J.; Chávez, S.

    2015-01-01

    The sunflower is an annual plant native to the Americas. It possesses a large inflorescence (flowering head), and its name is derived from the flower's shape and image, which is often used to capture the sun. The plant has a rough, broad, hairy stem, coarsely toothed, with rough leaves, and circular flower heads. The sunflower seeds are appreciated for their oil, which has become a widespread cooking ingredient. Leaves of the sunflower can be used as cattle feed, while the stems contain a fiber that may be used in paper production. Recently this flower has been used in phytoremediation of soils, contaminated with heavy metals. Sunflower has been probed as an efficient phytoextractor of chromium, lead, aluminum, zinc, cadmium from soil. In this work we present the experimental results of the drying of the sunflower stem, cut in 100 mm longitudinal sections, with diameters in the range of 11-18 mm. The aim was to obtain a dry and easy-to-handle final product, since these plants were originally cultivated in order to extract heavy metals from a polluted soil. The dried stems could then be easily confined or sent to recycle premises to concentrate the metals. The drying process was done in forced convection within a hot air tunnel. The used temperature was 60 °C, the velocity of air was 3 m/s and the required times were 8 hours. The initial average wet mass was 28 g and the final value was 5 g, resulting in the aimed product.

  17. Preservation of mouse sperm by convective drying and storing in 3-O-methyl-D-glucose.

    Directory of Open Access Journals (Sweden)

    Jie Liu

    Full Text Available With the fast advancement in the genetics and bio-medical fields, the vast number of valuable transgenic and rare genetic mouse models need to be preserved. Preservation of mouse sperm by convective drying and subsequent storing at above freezing temperatures could dramatically reduce the cost and facilitate shipping. Mouse sperm were convectively dried under nitrogen gas in the Na-EGTA solution containing 100 mmol/L 3-O-methyl-D-glucose and stored in LiCl sorption jars (Relative Humidity, RH, 12% at 4°C and 22°C for up to one year. The functionality of these sperm samples after storage was tested by intracytoplasmic injection into mouse oocytes. The percentages of blastocysts produced from sperm stored at 4°C for 1, 2, 3, 6, and 12 months were 62.6%, 53.4%, 39.6%, 33.3%, and 30.4%, respectively, while those stored at 22°C for 1, 2, and 3 months were 28.8%, 26.6%, and 12.2%, respectively. Transfer of 38 two- to four-cell embryos from sperm stored at 4°C for 1 year produced two live pups while 59 two- to four-cell embryos from sperm stored at 22°C for 3 months also produced two live pups. Although all the pups looked healthy at 3 weeks of age, normality of offspring produced using convectively dried sperm needs further investigation. The percentages of blastocyst from sperm stored in the higher relative humidity conditions of NaBr and MgCl(2 jars and driest condition of P(2O(5 jars at 4°C and 22°C were all lower. A simple method of mouse sperm preservation is demonstrated. Three-O-methyl-D-glucose, a metabolically inactive derivative of glucose, offers significant protection for dried mouse sperm at above freezing temperatures without the need for poration of cell membrane.

  18. Microwave assisted air drying of osmotically treated pineapple with variable power programmes

    CSIR Research Space (South Africa)

    Botha, GE

    2012-01-01

    Full Text Available Variable power programmes for microwave assisted air drying of pineapple were studied. The pineapple pieces were pre-treated by osmotic dehydration in a 55º Brix sucrose solution at 40ºC for 90 minutes. Variable power output programmes were designed...

  19. Evaluation of energy consumption in different drying methods

    Energy Technology Data Exchange (ETDEWEB)

    Motevali, Ali; Minaei, Saeid; Khoshtagaza, Mohammad Hadi [Department of Agricultural Machinery Engineering, Agricultural Faculty, Tarbiat Modares University, Tehran 14115-111 (Iran, Islamic Republic of)

    2011-02-15

    This study was conducted to evaluate energy consumption in various drying systems including hot-air convection, use of microwave pretreatment with convection dryer, microwave drying, vacuum drying and infrared drying. Tests were conducted using pomegranate arils under various experimental conditions as follows. In convection dryer at six temperature levels (45, 50, 55, 60, 65 and 70 C) and three air velocity levels (0.5, 1 and 1.5 m/s) at three pretreatments of control, 100 W microwave pretreatment for 20 min and 200 W microwave pretreatment for 10 min. Experiments in the microwave dryer were done at three power levels of 100, 200 and 300 W and in vacuum dryer at five temperature levels (50, 60, 70, 80, and 90 C) under 250 kPa pressure. For infrared drying, there were four air velocity levels (0.3, 0.5, 0.7 and 1 m/s) and three illumination levels (0.22, 0.31 and 0.49 W/cm{sup 2}). Experimental results showed that minimum and maximum energy consumption in pomegranate drying were associated with microwave and vacuum dryers, respectively. The use of microwave pretreatment in drying pomegranate arils in hot air dryer decreased drying time and energy consumption in comparison with pure convection drying. In infrared drying, it was found that drying time increased with air velocity which resulted in increased energy consumption. (author)

  20. Optimization of Drying Technique of Lentinus Edodes (Berk. Sing with Microwave Vacuum Equipment via Response Surface Analysis

    Directory of Open Access Journals (Sweden)

    Yi Zhang

    2012-12-01

    Full Text Available In this study, microwave vacuum equipment was employed to dry lentinus edodes (Berk. Sing. Response Surface Methodology was used to determine the optimal drying conditions. The significant levels were obtained by the equations. The optimal conditions for drying lentinus edodes (Berk. Sing with microwave vacuum equipment were obtained as following: microwave power 2650W, lentinus edodes load 171 g. Under these optimum conditions, lentinus edodes sensory evaluation, lentinan content and drying time were 80, 4.33% and 11 min, respectively.

  1. Stereological characterization of dry alpine snow for microwave remote sensing

    Science.gov (United States)

    Davis, Robert E.; Dozier, Jeff

    1989-01-01

    A persistent problem in investigations of electromagnetic properties of snow, from reflectance at visible wavelengths to emission and backscattering in the microwave, has been the proper characterization of the snow's physical properties. It is suggested that the granular and laminar structure of snow can be measured in its aggregated state by stereology performed on sections prepared from snow specimens, and that these kinds of measurements can be incorporated into models of the electromagnetic properties. With careful sampling, anisotropy in the snow microstructure at various scales can be quantified. It is shown how stereological parameters can be averaged over orientation and optical depth for radiative transfer modeling.

  2. Microwave extraction of essential oils from dried fruits of Illicium verum Hook. f. and Cuminum cyminum L. using ionic liquid as the microwave absorption medium.

    Science.gov (United States)

    Zhai, Yujuan; Sun, Shuo; Wang, Ziming; Cheng, Jianhua; Sun, Yantao; Wang, Lu; Zhang, Yupu; Zhang, Hanqi; Yu, Aimin

    2009-10-01

    Ionic liquid was used as microwave absorption medium and applied to the extraction of essential oils from dried fruits of the Illicium verum Hook. f. and Cuminum cyminum L. by microwave-assisted extraction. The extraction time is less than 15 min at the microwave power of 440 W. The constituents of essential oils obtained by the proposed method were compared with those obtained by hydrodistillation. There is no obvious difference in the constituents of essential oils obtained by the two methods.

  3. Applications of Microwave in Organic Synthesis: An Improved One-step Synthesis of Metallophthalocyanines and a New Modified Microwave Oven for Dry Reactions

    Directory of Open Access Journals (Sweden)

    Nathalie Bar

    2001-10-01

    Full Text Available Metallophthalocyanine complexes are obtained quickly and efficiently by the reaction of phthalodinitrile with hydrated metallic salts without solvent and under microwave irradiation. The use of a modified commercial microwave oven to perform this type of reactions under dry conditions is described. Metallophthalocyanines and metallododecachlorophthalocyanines of some divalent metals can be also obtained from phthalic or tetrachlorophthalic anhydrides with hydrated metallic salt and urea under microwave irradiation and without solvent.

  4. Microwave-vacuum drying of sour cherry: comparison of mathematical models and artificial neural networks.

    Science.gov (United States)

    Motavali, Ali; Najafi, Gholam Hassan; Abbasi, Solayman; Minaei, Saeid; Ghaderi, Abdurrahman

    2013-08-01

    Drying characteristics of sour cherries were determined using microwave vacuum drier at various microwave powers (360, 600, 840, 1200 W) and absolute pressures (200, 400, 600, 800 mbars). In addition, using the artificial neural networks (ANN), trained by standard Back-Propagation algorithm, the effects of microwave power, pressure and drying time on moisture ratio (MR) and drying rate (DR) were investigated Based on the evaluation of experimental data fitting with semi-theoretical and empirical models, the Midilli et al. model was selected as the most appropriate one. Furthermore, the ANN model was able to predict the moisture ratio and drying rate quite well with determination coefficients (R(2)) of 0.9996, 0.9961 and 0.9958 for training, validation and testing, respectively. The prediction Mean Square Error of ANN was about 0.0003, 0.0071 and 0.0053 for training, validation and testing, respectively. This parameter signifies the difference between the desired outputs (as measured values) and the simulated values by the model. The good agreement between the experimental data and ANN model leads to the conclusion that the model adequately describes the drying behavior of sour cherries, in the range of operating conditions tested.

  5. Optimization of microwave drying conditions of two banana varieties using response surface methodology

    Directory of Open Access Journals (Sweden)

    Adewale Olusegun Omolola

    2015-09-01

    Full Text Available AbstractOptimization of microwave drying conditions of Luvhele and Mabonde banana varieties were studied using response surface methodology. The drying was performed using a central composite rotatable design for two variables: microwave power level (100, 200 and 300 W and drying time (40, 26, and 12 min. for Luvhele; (100, 200 and 300 W and (42, 27, and 12 min for Mabonde. The colour and texture (hardness data were analyzed using ANOVA and regression analysis. The fitness of the models obtained was good as the lack of fit for each of the models was not significant. The coefficient of determination R2 of the models was relatively high, hence the models obtained for the responses were adequate and acceptable. Drying conditions of 178.76 W, 12 min. drying time were found optimum for product quality at a desirability of 0.91 for Luvhele; while 127.67 W, 12 min. with a desirability of 0.86 was predicted for Mabonde. The result of this study could be used as a standard for microwave processing of Luvhele and Mabondebanana varieties.

  6. Applications of Microwave in Organic Synthesis: An Improved One-step Synthesis of Metallophthalocyanines and a New Modified Microwave Oven for Dry Reactions

    OpenAIRE

    Nathalie Bar; Messaoud Hachemi; Mohamed Hammadi; Didier Villemin

    2001-01-01

    Metallophthalocyanine complexes are obtained quickly and efficiently by the reaction of phthalodinitrile with hydrated metallic salts without solvent and under microwave irradiation. The use of a modified commercial microwave oven to perform this type of reactions under dry conditions is described. Metallophthalocyanines and metallododecachlorophthalocyanines of some divalent metals can be also obtained from phthalic or tetrachlorophthalic anhydrides with hydrated metallic salt and urea under...

  7. Microwave Drying of Textile Materials and Optimization of a Resonant Applicator

    Directory of Open Access Journals (Sweden)

    M. Pourová

    2006-01-01

    Full Text Available The principal aim of this work was to design and optimize the applicator for microwave drying. Our applicator is derived from the Fabry-Perrot resonator, which is an open type resonator.The whole system works at frequency 2.45 GHz and the magnetron that we used delivers power 800 W. This machine is intended for use in drying in factory production of fabrics. After identifying of the basic arrangement of the microwave drying machine, the next step in the design was the use of the electromagnetic field simulator. We determined the position of the magnetron and found the distribution of the electric field strength in drying textiles in this way. In parallel, we analyzed the drying system with analytical calculations. We created a diagram of the EM waves inside this structure and reached the resulting expression for use in calculating the strenght of the electric field in the plane of the drying textile. This quantity depends on the electrical characteristics of wet textiles, e.g. the permittivity and the loss factor. Measurements of these dielectric properties for the coburg is complicated, and this method makes it possible to solve our problem with dielectric parameters. We have SAR distribution results (by simulation and also by measurement, results of measurements of the moisture content in the dried textile with respect to time. These results are important for subsequent optimization of the efficiency of the whole machine. 

  8. Experimental and numerical studies on the treatment of wet astronaut trash by forced-convection drying

    Science.gov (United States)

    Arquiza, J. M. R. Apollo; Morrow, Robert; Remiker, Ross; Hunter, Jean B.

    2017-09-01

    During long-term space missions, astronauts generate wet trash, including food containers with uneaten portions, moist hygiene wipes and wet paper towels. This waste produces two problems: the loss of water and the generation of odors and health hazards by microbial growth. These problems are solved by a closed-loop, forced-convection, heat-pump drying system which stops microbial activity by both pasteurization and desiccation, and recovers water in a gravity-independent porous media condensing heat exchanger. A transient, pseudo-homogeneous continuum model for the drying of wet ersatz trash was formulated for this system. The model is based on the conservation equations for energy and moisture applied to the air and solid phases and includes the unique trash characteristic of having both dry and wet solids. Experimentally determined heat and mass transfer coefficients, together with the moisture sorption equilibrium relationship for the wet material are used in the model. The resulting system of differential equations is solved by the finite-volume method as implemented by the commercial software COMSOL. Model simulations agreed well with experimental data under certain conditions. The validated model will be used in the optimization of the entire closed-loop system consisting of fan, air heater, dryer vessel, heat-pump condenser, and heat-recovery modules.

  9. Efficacy of Microwave Disinfection on Moist and Dry Dental Stone Casts with Different Irradiation Times

    Directory of Open Access Journals (Sweden)

    Mahmood Robati Anaraki

    2015-07-01

    Full Text Available Objectives: Dental practice contains the use of instruments and multiuse items that should be sterilized or disinfected properly. The aim of the current study was to investigate the effect of microwave irradiation on dental stone cast disinfection in moist and dry condition. Materials and Methods: In this in vitro study, 76 stone casts were prepared by a sterile method. The casts were contaminated by Pseudomonas aeruginosa (ATCC 9027, Staphylococcus aureus (ATCC 6538, Enterococcus faecalis (ATCC 29212 as well as Candida albicans (ATCC 10231. Half the samples were dried for two hours and the other half was studied while still moist. The samples were irradiated by a household microwave at 600 W for 3, 5 and 7 minutes. The microorganisms on the samples were extracted by immersion in tryptic soy broth and .001 ml of that was cultured in nutrient agar media, incubated overnight and counted and recorded as colony forming unit per milliliter (CFU/mL. Results: The findings showed that microorganisms reduced to 4.87 logarithm of CFU/mL value on dental cast within seven minutes in comparison with positive control. Although microbial count reduction was observed as a result of exposure time increase, comparison between moist and dried samples showed no significant difference. Conclusions: Seven-minute microwave irradiation at 600 W can effectively reduce the microbial load of dental stone casts. Wetting the casts does not seem to alter the efficacy of irradiation.   Keywords: Microwave Disinfection; Dental Stone Casts; Irradiation Times

  10. The lightning activity associated with the dry and moist convections in the Himalayan Regions

    Science.gov (United States)

    Penki, R. K.; Kamra, A. K.

    2013-06-01

    Lightning activity in the dry environment of northwest India and Pakistan (NW) and in the moist environment of northeast India (NE) has been examined from the Optical Transient Detector and Lightning Imaging Sensor data obtained from the Tropical Rainfall Measuring Mission satellite during 1995-2010. In the NW region, seasonal variation of flash rate is annual with a maximum in July but is semi-annual with a primary maximum in April and a secondary maximum in September, in the NE region. On diurnal scale, flash rate is the maximum in the afternoons, in both the NE and NW regions. The correlation of flash rate with convective parameters, viz. surface temperature, convective available potential energy (CAPE) and outgoing long-wave radiation is better with convective activity in the NW than in the NE region. Mean value of aerosol optical depth at 550 nm is ~ 26% higher and is highly correlated with flash rate in NW as compared to that in NE. Results indicate that CAPE is ~ 120 times more efficient in NW than in the NE region for production of lightning. The empirical orthogonal function analysis of flash rate, surface temperature, and CAPE shows that variance of lightning activity in these regions cannot be fully explained by the variance in the surface temperature and CAPE alone, and that some other factors, such as orographic lifting, precipitation, topography, etc., may also contribute to this variance in these mountainous regions. Further, the increase in CAPE due to orographic lifting in the Himalayan foothills in the NE region may contribute to ~ 7.5% increase in lightning activity. Relative roles of the thermally induced and moisture-induced changes in CAPE are examined in these regions. This study merely raises the questions, and that additional research is required for explaining the fundamental reasons for the reported observations here.

  11. Intensified Springtime Deep Convection over the South China Sea and the Philippine Sea Dries Southern China.

    Science.gov (United States)

    Li, Zhenning; Yang, Song; He, Bian; Hu, Chundi

    2016-07-27

    Springtime rainfall, accounting for 25-40% of the annual rainfall in southern China, exerts great agricultural and socioeconomic impacts on the region. In the recent decades, southern China has experienced a significant declining trend of precipitation in boreal spring. Meanwhile, precipitation has increased over the South China Sea and the Philippine Sea (SCS-PhS). This paper presents observational and modeling evidences suggesting that the intensified latent heating released by the convection over SCS-PhS leads to suppressed springtime rainfall over southern China. Moisture budget analysis indicates that the drying trend over southern China is due mainly to weakened convergence of moisture flux, which is controlled by a heat-induced anomalous overturning circulation reinforced by the convection over SCS-PhS. Further idealized simulations support the feature that the heat-induced overturning circulation and its corresponding anomalous cyclone can be well established in several days under the spring mean flow condition. Thus, this rapid dynamic process is associated with both the intraseasonal-to-interannual variations and the long-term change of the springtime rainfall over southern China.

  12. Intensified Springtime Deep Convection over the South China Sea and the Philippine Sea Dries Southern China

    Science.gov (United States)

    Li, Zhenning; Yang, Song; He, Bian; Hu, Chundi

    2016-07-01

    Springtime rainfall, accounting for 25-40% of the annual rainfall in southern China, exerts great agricultural and socioeconomic impacts on the region. In the recent decades, southern China has experienced a significant declining trend of precipitation in boreal spring. Meanwhile, precipitation has increased over the South China Sea and the Philippine Sea (SCS-PhS). This paper presents observational and modeling evidences suggesting that the intensified latent heating released by the convection over SCS-PhS leads to suppressed springtime rainfall over southern China. Moisture budget analysis indicates that the drying trend over southern China is due mainly to weakened convergence of moisture flux, which is controlled by a heat-induced anomalous overturning circulation reinforced by the convection over SCS-PhS. Further idealized simulations support the feature that the heat-induced overturning circulation and its corresponding anomalous cyclone can be well established in several days under the spring mean flow condition. Thus, this rapid dynamic process is associated with both the intraseasonal-to-interannual variations and the long-term change of the springtime rainfall over southern China.

  13. Outer scale and Monin-Obukhov flux relationships of atmospheric turbulence under dry convective conditions

    Science.gov (United States)

    De Bruin, Henk; Hartogensis, Oscar

    2015-04-01

    In this study we will investigate the assumption that in the atmospheric surface layer the outer scale (L0) is proportional to the height above the surface, under dry convective conditions. For this purpose we analyzed raw sonic anemometers data collected at 3.5 m and at 9 m in a field campaign at the Santa Cruz Flats (32040.3190'N, 111032.641'W, 526 m of elevation) near Eloy, Arizona. For simplicity, we define the L0 as that separation distance at which the spatial correlation coefficient of air temperature at two points in the surface layer is 0.5. Then, according to the 2/3-Kolmogorov scaling law in the inertial sub-range, L0 is determined by the variance and the structure parameter of T . It is found that L0 does not scale with height. Possible reasons for this negative result will be discussed, by considering the methodology to determine structure parameters, Taylor's frozen turbulence hypothesis, effects of intermittency and Monin-Obukhov flux relationships for variance and structure parameter for T . The question is asked whether the concept of surface constant flux layer still holds under strong convective condition.

  14. Ultrasonic Spray Drying vs High Vacuum and Microwaves Technology for Blueberries

    Science.gov (United States)

    Candia-Muñoz, N.; Ramirez-Bunster, M.; Vargas-Hernández, Y.; Gaete-Garretón, L.

    Interest in high quality foods: good taste and a high content of nutrients with healthy beneficial effects are increasing. Fruits have good properties but, they are lost because the oxidation process, additionally, for different reasons a 40% of harvested fruit are lost. To conserve the fruit properties an ultrasonic assisted spray dryer was developed and tested, comparing its results with microwave-vacuum drying technology. Results did shown taste, color, smell, particle shape and size distribution better than the conventional one. The antioxidants conservation were quite good except in the anthocyanins, in which the microwave and vacuum technology shown best results.

  15. PERFORMANCE OF A FORCED CONVECTION SOLAR DRIER INTEGRATED WITH GRAVEL AS HEAT STORAGE MATERIAL FOR CHILI DRYING

    Directory of Open Access Journals (Sweden)

    M. MOHANRAJ

    2009-09-01

    Full Text Available An indirect forced convection solar drier integrated with different sensible heat storage maternal has been developed and tested its performance for drying chili under the metrological conditions of Pollachi, India. The system consists of a flat plate solar air heater with heat storage unit, a drying chamber and a centrifugal blower. Drying experiments have been performed at an air flow rate of 0.25 kg/s. Drying of chili in a forced convection solar drier reduces the moisture content from around 72.8% (wet basis to the final moisture content about 9.1% in 24 h. Average drier efficiency was estimated to be about 21%. The specific moisture extraction rate was estimated to be about 0.87 kg/kWh.

  16. New model for colour kinetics of plum under infrared vacuum condition and microwave drying

    Directory of Open Access Journals (Sweden)

    Reza Amiri Chayjan

    2016-06-01

    Full Text Available Background. Quality of dried foods is affected by the drying method and physiochemical changes in tissue. The drying method affects properties such as colour. The colour of processed food is one of the most impor- tant quality indices and plays a determinant role in consumer acceptability of food materials and the process- ing method. The colour of food materials can be used as an indirect factor to determine changes in quality, since it is simpler and faster than chemical methods. Material and methods. The study focused on the kinetics of colour changes of plum slices, under infrared vacuum and microwave conditions. Drying the samples was implemented at the absolute pressures of 20 and 60 kPa, drying temperatures of 50 and 60°C and microwave power of 90, 270, 450 and 630 W. Colour changes were quantified by the tri-stimulus L* (whiteness/darkness, a* (redness/greenness and b* (yellow- ness/blueness model, which is an international standard for color measurement developed by the Commis- sion Internationale d’Eclairage (CIE. These values were also used to calculate total colour change (∆E, chroma, hue angle, and browning index (BI. A new model was used for mathematical modelling of colour change kinetics. Results. The drying process changed the colour parameters of L*, a*, and b*, causing a colour shift toward the darker region. The values of L* and hue angle decreased, whereas the values of a*, b*, ∆E, chroma and browning index increased during exposure to infrared vacuum conditions and microwave drying. Comparing the results obtained using the new model with two conventional models of zero-order and first-order kinet- ics indicated that the new model presented more compatibility with the data of colour kinetics for all colour parameters and drying conditions. Conclusion. All kinetic changes in colour parameters can be explained by the new model presented in this study. The hybrid drying system included infrared vacuum conditions and

  17. Effect of microwave and air drying of parboiled rice on stabilization of rice bran oil

    Directory of Open Access Journals (Sweden)

    Rizk, Laila F.

    1995-06-01

    Full Text Available Two rice varieties, Giza 175 (short grain and Giza 181 (long grain were partDoiled by soaking the grains at room temperature for 20 hours and steaming for 15 min then dried either at room temperature or by microwave. The results indicated that air and microwave drying significantly increased oil extraction in both rice bran varieties. Parboiling followed by air or microwave drying produced a slight change on protein, fiber and ash content of rice bran and reduced the development of free fatty acids (F.F.A. In oil bran. Microwave samples have less F.F.A. content than the corresponding samples air dried. Oils from the cold stored rice bran presented lower F.F.A. than the corresponding oil bran stored at room temperature. The ratio between total unsaturated fatty acids and total saturated ones (Tu/Ts decreased after air and microwave drying. Results also show that air drying increased the ratio of total hydrocarbons and total sterols (Tu/Ts in both varieties while microwave decreased it.

    Dos variedades de arroz, Giza 175 (grano corto y Giza 181 (grano largo se precocieron mediante la puesta en remojo de los granos a temperatura ambiente durante 20 horas y cocimiento al vapor durante 15 minutos, luego se secaron a temperatura ambiente o por microondas. Los resultados indicaron que el secado al aire y en microondas aumentó significativamente la extracción del aceite en ambas variedades de salvado de arroz. El precocido seguido del secado al aire o en microondas produjo un cambio pequeño en el contenido en proteína, fibra y ceniza y redujo el desarrollo de ácidos grasos libres (F.F.A. en el aceite de salvado. Las muestras secadas en microondas tuvieron un menor contenido en F.F.A. que las muestras correspondientes al secado en aire. Aceites de salvado de arroz almacenado en frió presentaron menor F.F.A. que los almacenados a temperatura ambiente. La relación entre ácidos grasos insaturados totales y los saturados totales (Tu/Ts disminuy

  18. Optimization of Microwave-Osmotic Pretreatment of Apples with Subsequent Air-Drying for Preparing High-Quality Dried Product

    Directory of Open Access Journals (Sweden)

    Elham Azarpazhooh

    2011-01-01

    Full Text Available Prepared apple (Red Gala cylinders were subjected to microwave-osmotic dehydration treatment under continuous flow medium spray (MWODS conditions and then air-dried to a final 20% moisture content. The dried samples were evaluated for color and textural properties, and rehydration capacity. The MWODS pretreatments were based on a central composite rotatable design and a response surface methodology using five levels of sucrose concentration, temperature, and contact time at a constant flow rate of 2800 mL/min. The air-drying was carried out at 60°C, 15±1% relative humidity, and 0.64±0.02 m/s air velocity. The results were compared to untreated air-dried (AD (worst-case scenario and freeze-dried (FD (best-case scenario apples without the MWODS treatment. Color properties were affected regardless of the type of treatment. Conventional AD apples were darker in color, whereas MWODS-treated samples were lighter with higher L∗ and b∗ values, higher Hue and Chroma values but lower a∗ value and ΔE. Further the color parameters of MWODS-treated samples were closer or equal to the FD apples. The texture properties were also affected by the osmotic variables with MWODS treatment resulting in softer and chewier products. The AD samples were hard, and FD apples were brittle.

  19. Microwave Sintering of W-15Cu Ultrafine Composite Powder Prepared by Spray Drying & Calcining-continuous Reduction Technology

    Institute of Scientific and Technical Information of China (English)

    SHU Jingping; SHI Xiaoliang; WANG Shuwei; YANG Xingyong; ZHANG Qiaoxin; WANG Yufu

    2011-01-01

    The effects of microwave sintering and conventional H2 sintering on the microstructure and properties of W-l5Cu alloy using ultrafine W-15Cu composite powder fabricated by spray drying & calcining-continuous reduction technology were investigated. In comparison to the conventional H2 sintering processing, microwave sintefing to W-15Cu can be achieved at lower sintefing temperature and shorter sintering time. Furthermore, higher performances in microwave sintered compacts were obtained, but high microwave sintering temperature or long microwave sintering time could result in coarser microstructures.

  20. Influence of combined pretreatments on color parameters during convective drying of Mirabelle plum (Prunus domestica subsp. syriaca)

    Science.gov (United States)

    Dehghannya, Jalal; Gorbani, Rasoul; Ghanbarzadeh, Babak

    2017-02-01

    Discoloration and browning are caused primarily by various reactions, including Maillard condensation of hexoses and amino components, phenol polymerization and pigment destruction. Convective drying can be combined with various pretreatments to help reduce undesired color changes and improve color parameters of dried products. In this study, effects of ultrasound-assisted osmotic dehydration as a pretreatment before convective drying on color parameters of Mirabelle plum were investigated. Variations of L* (lightness), a* (redness/greenness), b* (yellowness/blueness), total color change (ΔE), chroma, hue angle and browning index values were presented versus drying time during convective drying of control and pretreated Mirabelle plums as influenced by ultrasonication time, osmotic solution concentration and immersion time in osmotic solution. Samples pretreated with ultrasound for 30 min and osmotic solution concentration of 70% had a more desirable color among all other pretreated samples, with the closest L*, a* and b* values to the fresh one, showing that ultrasound and osmotic dehydration are beneficial to the color of final products after drying.

  1. Evaluating weather research and forecasting (WRF) model predictions of turbulent flow parameters in a dry convective boundary layer

    NARCIS (Netherlands)

    Gibbs, J.A.; Fedorovich, E.; Eijk, A.M.J. van

    2011-01-01

    Weather Research and Forecasting (WRF) model predictions using different boundary layer schemes and horizontal grid spacings were compared with observational and numerical large-eddy simulation data for conditions corresponding to a dry atmospheric convective boundary layer (CBL) over the southern

  2. Optimization of microwave vacuum drying parameters for germinated lentils based on starch digestibility, antioxidant activity and total phenolic content

    Directory of Open Access Journals (Sweden)

    Robbarts Nongmaithem

    2017-04-01

    Full Text Available The aim of this study was to optimize the processing parameters of pulse mode microwave-vacuum drying of germinated green and red lentils (CDC Greenland and CDC Maxim and investigate the changes in their total phenolic content (TPC, total antioxidant activity (TAA and in-vitro starch digestibility (SD. The lentils were germinated for 5 days and dried by a pulse mode microwave-vacuum method, using 2 s to 8 s out of 10 s pulsed mode at 2000W microwave power and varying the vacuum pressure level between 15 and 45 kPa. In-vitro starch digestibility increased significantly with increased microwave power level. The TPC and TAA appeared to vary distinctively in the two varieties of selected lentils. Vacuum pressure levels did not significantly (p>0.05 affect any responses. Green lentils could be dried at 8 s microwave power and 45 kPa vacuum pressure and red lentils could be dried at 5.5 s microwave power and 42.19 kPa vacuum pressure. The microwave-vacuum drying showed great potential for the drying of germinated lentils.

  3. INVESTIGATION OF THE KINETICS OF DRYING SEEDS THISTLE IN VORTEX CHAMBER WITH MICROWAVE ENERGY SUPPLY

    Directory of Open Access Journals (Sweden)

    D. A. Kazartsev

    2015-01-01

    Full Text Available In the study of the current state of the theory, techniques and technologies for processing of milk thistle showed up a number of problems. One of those moments - the need to promptly provide quality and efficient process for drying seeds, but Russia has not produced special equipment for postharvest processing of seeds of milk thistle, and used for drying grain domestic appliances, represented mainly by mining and drum dryers, it is not suitable for thistle. This is due to the fact that, firstly, in the dewatering process is necessary to provide a relatively low final moisture drying product (5-6 %, and, secondly, to keep their beneficial substance in full, which imposes additional restrictions on the conditions of drying. One way of creating a new drying technology development and implementation in the industry of high-intensive devices with active hydrodynamic regimes with microwave energy supply, providing in many cases, higher technical and economic indicators. Therefore, the use of devices with swirling flow of heat-carrier for the intensification of the process of drying of dispersed materials is both theoretical interest and practical value. Microwave drying is based on the fact that the dielectric properties of water and dry food substances are different: the wet material is heated much faster than dry. During the microwave drying temperature wetter internal layers higher than the exterior more dehydrated (which creates a "right" - from the inner to the outer layers of the product - the gradient of moisture mass transfer is not realizable in any of the other known methods of drying. Milk thistle seeds have a unique composition: 25-32 % fatty oil, 15-17 % protein, 26 % fat, in the-soluble (B group and fat-soluble (A, D, E, K, F vitamins, mono- and disaccharides, macro- and trace elements (copper, zinc, selenium, dietary fiber and enzymes, mucus, up to 5 % (glucose, etc., phenolic compounds including flaviolignans 2-3% (silibinin

  4. Oil content and fatty acid composition of eggs cooked in drying oven, microwave and pan.

    Science.gov (United States)

    Juhaimi, Fahad Al; Uslu, Nurhan; Özcan, Mehmet Musa

    2017-01-01

    In this study, the effect of heating on the oil yield and fatty acid composition of eggs cooked in drying oven, microwave oven, pan and boiled were determined, and compared. The highest oil content (15.22%) was observed for egg cooked in drying oven, while the lowest oil (5.195%) in egg cooked in pan. The cooking in microwave oven caused a decrease in oleic acid content (46.201%) and an increase in the amount of palmitic acid content (26.862%). In addition, the maximum oleic acid (65.837%) and minimum palmitic acid (14.015%) contents were observed in egg oil cooked in pan. Results showed that fatty acids were significantly affected by cooking method. This study confirms that the cooking processing influences the fatty acid composition of egg oils.

  5. Total phenolics, antioxidant capacity, colour and drying characteristics of date fruit dried with different methods

    Directory of Open Access Journals (Sweden)

    Gökçen İZLİ

    2016-01-01

    Full Text Available Abstract Date slices were dried with the three drying methods convective (60, 70 and 80 °C, microwave (120 W and freeze drying to determine drying characteristics and to compare the dried fruit quality. All colour parameters changed depending on the drying method and colours closest to the fresh sample were obtained with freeze drying. It is interesting to note that the total phenolic content and antioxidant capacity in each sample rose when looked at in relation to the fresh sample. In particular, microwave-dried samples were recorded as having the highest total phenolic content and the highest antioxidant capacity. To explain the drying kinetics of the date slices, nine thin-layer drying models were also attempted. Based on statistical tests, the model developed by Midilli et al. model was found to be the best model for convective and microwave drying, but the Two Term model was the best for freeze drying. This study shows that microwave drying can produce high quality date slices with the additional advantage of reduced drying times compared to convective and freeze drying.

  6. Effect of Microwave on Fluidized Bed Drying of Beetroot (Beta vulgaris L.

    Directory of Open Access Journals (Sweden)

    Yashwant Kumar

    2016-07-01

    Full Text Available In the present work, an attempt has been made to study the effect of inlet air temperature and velocity on the drying characteristics of beetroot’s (Beta vulgaris L. pieces in microwave assisted fluidized bed drying (MAFBD system. The results were compared with samples of beetroot dried in a fluidized bed dryer (FBD at the same combination of temperatures and air velocities. The selected inlet air temperatures and inlet air velocities were 60°C, 67.50°C and 75°C and 9 m/s, 10.50 m/s and 12 m/s, respectively. Moisture content and outlet air humidity was measured at 5 minutes interval. The MAFBD method offered two to three times reduction in drying time as compared to the FBD method. It was also observed that the beetroot samples obtained from the MAFBD system had lower final moisture content than those obtained from the FBD system.

  7. Changes in non-volatile taste components of button mushroom (Agaricus bisporus) during different stages of freeze drying and freeze drying combined with microwave vacuum drying.

    Science.gov (United States)

    Pei, Fei; Shi, Ying; Gao, Xingyang; Wu, Fangning; Mariga, Alfred Mugambi; Yang, Wenjian; Zhao, Liyan; An, Xinxin; Xin, Zhihong; Yang, Fangmei; Hu, Qiuhui

    2014-12-15

    Button mushroom slices were dehydrated using freeze drying (FD) or FD combined with microwave vacuum drying (FMVD), and the non-volatile component profiles were studied. The results showed that the level of non-volatile components in button mushroom firstly increased during sublimation of FD/FMVD process and then fell during desorption in FD process and MVD in FMVD process. Compared to FD products, the contents of soluble sugars and polyols in FMVD products were relatively low, whereas the contents of total free amino acids were significantly higher, close to the level of fresh mushroom. However, there was no significant difference in the contents of 5'-nucleotides and organic acids between FD and FMVD products. The equivalent umami concentration (EUC) values for FD and FMVD products did not differ from fresh, indicating that both drying methods could effectively preserve MSG (monosodium glutamate)-like components in button mushroom. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. New type of dry substances content meter using microwaves for application in biogas plants.

    Science.gov (United States)

    Nacke, Thomas; Brückner, Kathleen; Göller, Arndt; Kaufhold, Sebastian; Nakos, Xenia; Noack, Stephan; Stöber, Heinrich; Beckmann, Dieter

    2005-11-01

    Dry substances (DS) are an important index for monitoring and controlling anaerobic co-digestion in biogas plants. We have developed and tested an online meter that measures suspended solids by means of the reflection coefficient of an exiting microwave signal, which is dependent on the dielectric properties of the suspensions. Intelligent models based on partial least squares regression (PLSR) and artificial neural network (ANN) for calibration allow exact and reproducible measurements under different circumstances. This measuring method is appropriate for contactless and online measurements of dry substance contents in biogas plants in a large range from 2-14%.

  9. Empirical modeling of drying kinetics and microwave assisted extraction of bioactive compounds from Adathoda vasica

    Directory of Open Access Journals (Sweden)

    Prithvi Simha

    2016-03-01

    Full Text Available To highlight the shortcomings in conventional methods of extraction, this study investigates the efficacy of Microwave Assisted Extraction (MAE toward bioactive compound recovery from pharmaceutically-significant medicinal plants, Adathoda vasica and Cymbopogon citratus. Initially, the microwave (MW drying behavior of the plant leaves was investigated at different sample loadings, MW power and drying time. Kinetics was analyzed through empirical modeling of drying data against 10 conventional thin-layer drying equations that were further improvised through the incorporation of Arrhenius, exponential and linear-type expressions. 81 semi-empirical Midilli equations were derived and subjected to non-linear regression to arrive at the characteristic drying equations. Bioactive compounds recovery from the leaves was examined under various parameters through a comparative approach that studied MAE against Soxhlet extraction. MAE of A. vasica reported similar yields although drastic reduction in extraction time (210 s as against the average time of 10 h in the Soxhlet apparatus. Extract yield for MAE of C. citratus was higher than the conventional process with optimal parameters determined to be 20 g sample load, 1:20 sample/solvent ratio, extraction time of 150 s and 300 W output power. Scanning Electron Microscopy and Fourier Transform Infrared Spectroscopy were performed to depict changes in internal leaf morphology.

  10. Dry matter genotypes of Cynodon by microwave and conventional oven methods

    Directory of Open Access Journals (Sweden)

    Euclides Reuter de Oliveira

    2013-02-01

    Full Text Available The aimed of this work was to comparing the drying process in a microwave oven and forced air ventilation, as well as their effects on the chemical composition of different genotypes of the genus Cynodon (Tifton 85, Jiggs, Russell, Tifton 68 and Vaquero collected at different ages cutting (28, 48, 63 and 79 days. The experimental design was a randomized block in a split-plot design, with 4 replicates. There was no difference (P>0.05 between the methods analyzed on the chemical composition of the genotypes studied. Increasing age cutoff negatively influenced (P<0.05 the crude protein content of the different plant parts. A significant increase (P<0.05 of dry matter, neutral detergent fiber, acid detergent fiber and dry matter production was observed with increasing age cut. The use of the microwave oven is a quick and precise method obtain the dry matter content of the fodder showing efficiency similar to the method of drying in an oven with forced air circulation. The genotypes showed better chemical composition results when handled at age 28 days.

  11. Dry and moist convection in the boundary layer over the Black Forest - a combined analysis of in situ and remote sensing data

    Directory of Open Access Journals (Sweden)

    Norbert Kalthoff

    2013-08-01

    Full Text Available During the COPS experiment performed in south-western Germany and eastern France in 2007, several insitu and remote sensing systems were operated at Hornisgrinde - the highest summit of the northern Black Forest mountains. For this case study, data from a surface flux station, radiosondes, cloud camera, cloud radar, wind lidar, water vapour differential absorption lidar, and microwave profiler were used to investigate turbulence characteristics in cloud-free and cloud-topped convective boundary layers (CBLs. Short time intervals were analysed, during which dry and moist convective cells occurred, in order to obtain insight of the processes that determine the turbulent characteristic in the CBL. The frequently-used aerosol concentration was used to calculate the CBL height, zi . It was found that active CBL clouds penetrated deeper into the free troposphere than dry convective cells. In the cloud-free CBL the normalised variance of the vertical velocity, ?w 2, decreased to zero approximately at zi , while ?w 2 was nearly constant between 0.5 and 1 z/zi in the cloud-topped CBL. The higher normalised ?w 2 values in the cloud layer could be attributed to the additional elevated heat source due to condensation. In the cloud-free CBL the latent heat flux showed a strong decrease between 0.7 and 1.1 z/zi , i.e., it considerably moistened the upper part of the CBL and entrainment zone. In the cloud-topped CBL the latent heat flux decreased significantly above the CBL top only and became zero at about 1.4 z/zi . CBL height calculations, which took measures of the turbulence into account, resulted in normalised ?w 2 and E profiles, which became zero at the CBL top and appeared more appropriate for CBL height scaling over complex terrain. The case studies demonstrated that only the combined use of different monitoring systems allowed for the recording of the entire structure of the convective cells and that synergetic measurements in cloud-topped CBLs were

  12. Application of a Device for Uniform Web Drying and Preheating Using Microwave Energy

    Energy Technology Data Exchange (ETDEWEB)

    Frederick W. Ahrens; C. Habeger; J. Loughran; T. Patterson

    2003-10-02

    The project summarized in this report dealt with an evaluation of new microwave applicator ideas for paper preheating and drying. The technical basis for success in this project is the fact that Industrial Microwave Systems has recently identified certain previously unrecognized wave guide ''design variables'' and hardware implementation concepts that can be employed to greatly improve the uniformity of microwave energy distribution for continuous flow processes. Two applicator concepts were ultimately evaluated, a Cross-Machine Direction (CD) oriented applicator and a Machine Direction (MD) oriented applicator. The economic basis for success is the result of several factors. Since 1985, the capital expenditure required for an industrial microwave applicator system has decreased by a factor of four. The maintenance costs have decreased by a factor of 10 and the life expectancy of the magnetron has increased by more than a factor of four to in excess of 8,000 hours (nearly one year at 24 hours/day operation).

  13. The effect of microwave power and heating time pretreatment on biogas production from fresh and dried water hyacinth (Eichhornia crassipes)

    Science.gov (United States)

    Sumardiono, Siswo; Budiyono, Mardiani, Dini Tri

    2015-12-01

    The objective of this research was to study the effect of microwave pretreatment of fresh and dried water hyacinth on biogas production. The variations of microwave power levels are 240; 400; 560 and 800 W. The variations of microwave heating time are 5; 7 and 9 min. The unpretreated fresh and dried water hyacinth are used as control. The result of research showed that almost all pretreated water hyacinth produced biogas were higher compare tounpretreated water hyacinth. The maximum of biogas production from fresh and dried water hyacinthwere obtained at 560 W for 7 min and 400 W for 7 min of microwave pretreatment. In this condition, pretreated fresh and dried water hyacinth resulted biogas production of 75,12 and 53,06 mL/g TS, respectively. The unpretreated fresh and dried water hyacinth produced biogas of 37,56 and 33,56 mL/g TS, respectively. The microwave pretreatment of water hyacinth improved biogas production. Microwave pretreatment had a positive impact on anaerobic biodegradability of water hyacinth.

  14. Drying characteristics of zucchini slices under periodic infrared-microwave vacuum conditions

    Science.gov (United States)

    Chayjan, Reza Amiri; Dibagar, Nesa; Alaei, Behnam

    2017-06-01

    The purpose of the presented study was to describe the effects of various drying conditions on the drying behavior of zucchini slices as well as specifications of diffusivity, activation energy, shrinkage, and color. Zucchini samples, as the richest fount of macronutrient and micronutrient, were subjected to periodic microwave vacuum drying (at 450 W) at three levels of temperature (40, 50 and 60 °C), absolute pressure (20, 40 and 60 kPa) and exposure time (20-3, 30-4.5 and 40-6 s-min). An increase in the drying temperature and exposure time along with a decrease in absolute pressure caused a reduction in total drying time, however, greater heat damages and adversely texture and color effects were observed in this case. The effective moisture diffusivity of zucchini varied between 5.41×10-10 and 1.75×10-9, indicating that under circumstances of high temperature, long exposure time and low absolute pressure water was able to rapidly diffuse out of the tissue in the experimental domain. Lowering the absolute pressure of vacuum flask and increasing the exposure time led to the reduction in the activation energy of samples. The shrinkage coefficient was within the range of 79.91 to 84.92%. As such, the greatest total color difference was calculated between the color of raw and dried samples for those experiments with the largest increase in temperature, exposure time and a decrease in absolute pressure.

  15. Mathematic modeling of the kinetics of heat-and-humidity state of capillary-porous bodies under convection drying

    Science.gov (United States)

    Kovalnogov, Vladislav N.; Karpukhina, Tamara V.; Korotkov, Evgeny A.

    2016-06-01

    The work suggests a mathematical model and a technique for numerical research of the kinetics of a heat-and-humidity state of a capillary-porous body built on a simultaneous equations solution of heat conductivity and moisture transfer. Experimental data on a liquid diffusion coefficient in capillary-porous space of a ceramic brick are obtained. Results of numerical research of a heat-and-humidity state of a ceramic brick in the process of convective drying are presented.

  16. Forced and natural convective drying of trehalose/water thin films: implication in the desiccation preservation of Mammalian cells.

    Science.gov (United States)

    Chen, Bingyan; Fowler, Alex; Bhowmick, Sankha

    2006-06-01

    Trehalose is believed to offer desiccation protection to mammalian cells by forming stable glassy matrices. The goal of the current study was to explore the desiccation kinetics of thin films of trehalose-water solution under forced and natural convective conditions and to investigate the thermophysical state of mammalian cells at the bottom of the thin film. We developed a finite difference model based on the mass and energy conservation equations coupled to the water transport model from the cells. The boundary conditions were obtained from correlations or experimental measurements and the Gordon-Taylor equation was used to predict the glass transition temperature at every location. Results indicated that there are three distinct regimes for drying for both forced and natural convection, characterized by the slope of the moisture content plot as a function of time. Our results also indicate that the surface of the solution reached the glassy state in less than 10 min for the Reynolds (forced) numbers explored and approximately 30 min for some Rayleigh (natural convective) numbers; however, significant water was trapped at this instant. Larger drying force hastened quicker glass formation but trapped more water. The numerical model was capable of predicting the drying kinetics for the dilute region accurately, but deviated while predicting the other regimes. Based on these experimental validations of the model, the osmotic response of different cells located at the bottom of the solution with orders of magnitude difference in their membrane permeability (Lp) was predicted. The results suggested that extracellular glass formed around cells at the bottom of a trehalose-water solution by the propagation of glass into the solution; however it takes more than an order of magnitude time (approximately 7 min to >100 min for forced convective drying) to remove sufficient water to form glass around cells from the time when the first surface glass is formed. This is

  17. The impact of convective drying on the color, phenolic content and antioxidant capacity of noni (Morinda citrifolia L.

    Directory of Open Access Journals (Sweden)

    Ana Isabel MIRELES-ARRIAGA

    Full Text Available Abstract The effect of thin-layer drying temperature on color, phenolic content and antioxidant capacity of noni slices was investigated. Noni slices were air-dried at 50, 60 and 70 °C under natural convection conditions. Drying curves were fitted to thin-layer drying models in order to evaluate the drying characteristics of the product. In addition, an unsteady-state diffusion equation was numerically solved considering both product shrinkage and a variable mass Biot number in boundary condition to accurately estimate water diffusivity in a process with external resistance to mass transfer. Results revealed that the Aghbashlo model accurately reproduced the experimental behavior. As expected, water diffusivities, corrected for shrinkage, increased with the use of higher drying temperatures, with values in the range of 1.80-3.19 to ×10-9 m2/s. On the other hand, while drying caused a reduction in product lightness (24-31% and total phenolic content (20-28%, the antioxidant capacity of dried noni was high (82-93% DPPH inhibition, which is advantageous for the further storage or processing of this fruit.

  18. Production of concentrated “Ya Pak King” drink by vacuum microwave drying

    OpenAIRE

    Wanprakeaw, P.; Kankrengwong, J.; Jirasant, S.; Suntornsuk, W.

    2005-01-01

    Ya Pak King juice is currently popular among Thai consumers. However, some people do not like to drink it because of its pungent smell and flavor. The objectives of this investigation were to improve consumer perception of ready-to-drink Ya Pak King juice and to produce the concentrated drink by vacuum microwave drying. The herbal juice from Ya Pak King was prepared and formulated with lemon juice and honey by the Mixture Design. The drink flavor and taste were then modified by the addition o...

  19. Overall Quality of Fruits and Vegetables Products Affected by the Drying Processes with the Assistance of Vacuum-Microwaves.

    Science.gov (United States)

    Figiel, Adam; Michalska, Anna

    2016-12-30

    The seasonality of fruits and vegetables makes it impossible to consume and use them throughout the year, thus numerous processing efforts have been made to offer an alternative to their fresh consumption and application. To prolong their availability on the market, drying has received special attention as currently this method is considered one of the most common ways for obtaining food and pharmaceutical products from natural sources. This paper demonstrates the weakness of common drying methods applied for fruits and vegetables and the possible ways to improve the quality using different drying techniques or their combination with an emphasis on the microwave energy. Particular attention has been drawn to the combined drying with the assistance of vacuum-microwaves. The quality of the dried products was ascribed by chemical properties including the content of polyphenols, antioxidant capacity and volatiles as well as physical parameters such as color, shrinkage, porosity and texture. Both these fields of quality classification were considered taking into account sensory attributes and energy aspects in the perspective of possible industrial applications. In conclusion, the most promising way for improving the quality of dried fruit and vegetable products is hybrid drying consisting of osmotic dehydration in concentrated fruit juices followed by heat pump drying and vacuum-microwave finish drying.

  20. Overall Quality of Fruits and Vegetables Products Affected by the Drying Processes with the Assistance of Vacuum-Microwaves

    Directory of Open Access Journals (Sweden)

    Adam Figiel

    2016-12-01

    Full Text Available The seasonality of fruits and vegetables makes it impossible to consume and use them throughout the year, thus numerous processing efforts have been made to offer an alternative to their fresh consumption and application. To prolong their availability on the market, drying has received special attention as currently this method is considered one of the most common ways for obtaining food and pharmaceutical products from natural sources. This paper demonstrates the weakness of common drying methods applied for fruits and vegetables and the possible ways to improve the quality using different drying techniques or their combination with an emphasis on the microwave energy. Particular attention has been drawn to the combined drying with the assistance of vacuum-microwaves. The quality of the dried products was ascribed by chemical properties including the content of polyphenols, antioxidant capacity and volatiles as well as physical parameters such as color, shrinkage, porosity and texture. Both these fields of quality classification were considered taking into account sensory attributes and energy aspects in the perspective of possible industrial applications. In conclusion, the most promising way for improving the quality of dried fruit and vegetable products is hybrid drying consisting of osmotic dehydration in concentrated fruit juices followed by heat pump drying and vacuum-microwave finish drying.

  1. Simultaneous application of microwave energy and hot air to whole drying process of apple slices: drying kinetics, modeling, temperature profile and energy aspect

    Science.gov (United States)

    Horuz, Erhan; Bozkurt, Hüseyin; Karataş, Haluk; Maskan, Medeni

    2017-09-01

    Drying kinetics, modeling, temperature profile and energy indices were investigated in apple slices during drying by a specially designed microwave-hot air domestic hybrid oven at the following conditions: 120, 150 and 180 W microwave powers coupled with 50, 60 and 70 °C air temperatures. Both sources of energy were applied simultaneously during the whole drying processes. The drying process continued until the moisture content of apple slices reached to 20% from 86.3% (wet basis, w.b). Drying times ranged from 330 to 800 min and decreased with increasing microwave power and air temperatures. The constant rate period was only observed at low microwave powers and air temperatures. Two falling rate periods were observed. Temperature of apple slices sharply increased within the first 60 min, then reached equilibrium with drying medium and finally increased at the end of the drying process. In order to describe drying behavior of apple slices nine empirical models were applied. The Modified Logistic Model fitted the best our experimental data (R 2 = 0.9955-0.9998; χ 2 = 3.46 × 10-5-7.85 × 10-4 and RMSE = 0.0052-0.0221). The effective moisture and thermal diffusivities were calculated by Fick's second law and ranged from 1.42 × 10-9 to 3.31 × 10-9 m2/s and 7.70 × 10-9 to 12.54 × 10-9 m2/s, respectively. The activation energy (Ea) values were calculated from effective moisture diffusivity (Deff), thermal diffusivity (α) and the rate constant of the best model (k). The Ea values found from these three terms were similar and varied from 13.04 to 33.52 kJ/mol. Energy consumption and specific energy requirement of the hybrid drying of apple slices decreased and energy efficiency of the drying system increased with increasing microwave power and air temperature. Apples can be dried rapidly and effectively by use of the hybrid technique.

  2. Optimization of microwave-assisted transesterification of dry algal biomass using response surface methodology.

    Science.gov (United States)

    Patil, Prafulla D; Gude, Veera Gnaneswar; Mannarswamy, Aravind; Cooke, Peter; Munson-McGee, Stuart; Nirmalakhandan, Nagamany; Lammers, Peter; Deng, Shuguang

    2011-01-01

    The effect of microwave irradiation on the simultaneous extraction and transesterification (in situ transesterification) of dry algal biomass to biodiesel was investigated. A high degree of oil/lipid extraction from dry algal biomass and an efficient conversion of the oils/lipids to biodiesel were demonstrated in a set of well-designed experimental runs. A response surface methodology (RSM) was used to analyze the influence of the process variables (dry algae to methanol (wt/vol) ratio, catalyst concentration, and reaction time) on the fatty acid methyl ester conversion. Based on the experimental results and RSM analysis, the optimal conditions for this process were determined as: dry algae to methanol (wt/vol) ratio of around 1:12, catalyst concentration about 2 wt.%, and reaction time of 4 min. The algal biodiesel samples were analyzed with GC-MS and thin layer chromatography (TLC) methods. Transmission electron microscopy (TEM) images of the algal biomass samples before and after the extraction/transesterification reaction are also presented.

  3. Heat and Mass Transfer Modeling of Rough Rice Under Convective and Infrared Drying

    Science.gov (United States)

    Infrared drying of rice can reduce drying time, perform disinfestations and reduce rice fissuring compared to traditional hot air drying method. Fissures in the rice kernels are caused by high moisture content gradients within the kernels. To understand the moisture distributions within a rice ker...

  4. The Earth's mantle in a microwave oven: thermal convection driven by a heterogeneous distribution of heat sources

    Science.gov (United States)

    Fourel, Loïc; Limare, Angela; Jaupart, Claude; Surducan, Emanoil; Farnetani, Cinzia G.; Kaminski, Edouard C.; Neamtu, Camelia; Surducan, Vasile

    2017-08-01

    Convective motions in silicate planets are largely driven by internal heat sources and secular cooling. The exact amount and distribution of heat sources in the Earth are poorly constrained and the latter is likely to change with time due to mixing and to the deformation of boundaries that separate different reservoirs. To improve our understanding of planetary-scale convection in these conditions, we have designed a new laboratory setup allowing a large range of heat source distributions. We illustrate the potential of our new technique with a study of an initially stratified fluid involving two layers with different physical properties and internal heat production rates. A modified microwave oven is used to generate a uniform radiation propagating through the fluids. Experimental fluids are solutions of hydroxyethyl cellulose and salt in water, such that salt increases both the density and the volumetric heating rate. We determine temperature and composition fields in 3D with non-invasive techniques. Two fluorescent dyes are used to determine temperature. A Nd:YAG planar laser beam excites fluorescence, and an optical system, involving a beam splitter and a set of colour filters, captures the fluorescence intensity distribution on two separate spectral bands. The ratio between the two intensities provides an instantaneous determination of temperature with an uncertainty of 5% (typically 1K). We quantify mixing processes by precisely tracking the interfaces separating the two fluids. These novel techniques allow new insights on the generation, morphology and evolution of large-scale heterogeneities in the Earth's lower mantle.

  5. Improved solvent-free microwave extraction of essential oil from dried Cuminum cyminum L. and Zanthoxylum bungeanum Maxim.

    Science.gov (United States)

    Wang, Ziming; Ding, Lan; Li, Tiechun; Zhou, Xin; Wang, Lu; Zhang, Hanqi; Liu, Li; Li, Ying; Liu, Zhihong; Wang, Hongju; Zeng, Hong; He, Hui

    2006-01-13

    Solvent-free microwave extraction (SFME) is a recently developed green technique which is performed in atmospheric conditions without adding any solvent or water. SFME has already been applied to extraction of essential oil from fresh plant materials or dried materials prior moistened. The essential oil is evaporated by the in situ water in the plant materials. In this paper, it was observed that an improved SFME, in which a kind of microwave absorption solid medium, such as carbonyl iron powders (CIP), was added and mixed with the sample, can be applied to extraction of essential oil from the dried plant materials without any pretreatment. Because the microwave absorption capacity of CIP is much better than that of water, the extraction time while using the improved SFME is no more than 30 min using a microwave power of 85 W. Compared to the conventional SFME, the advantages of improved SFME were to speed up the extraction rate and need no pretreatment. Improved SFME has been compared with conventional SFME, microwave-assisted hydrodistillation (MAHD) and conventional hydrodistillation (HD) for the extraction of essential oil from dried Cuminum cyminum L. and Zanthoxylum bungeanum Maxim. By using GC-MS system the compositions of essential oil extracted by applying four kinds of extraction methods were identified. There was no obvious difference in the quality of essential oils obtained by the four kinds of extraction methods.

  6. Experimental Analysis of Open, Simple and Modified Greenhouse Dryers for Drying Potato Flakes Under Forced Convection

    Directory of Open Access Journals (Sweden)

    Tanuj Kumar Sahu

    2016-07-01

    Full Text Available Drying using burning of fossil fuels and open sun drying are traditional way to dry crops, fruits, vegetables etc. But there are some disadvantages associated with them such as crops are affected by dirt and other impurities. To overcome the problems associated with open sun drying and drying using burning of fossil fuels, solar greenhouse drying is found out to be the best alternative. In present work the performance of simple and modified greenhouse dryer is evaluated and effort is made to increase the drying rate of greenhouse dryer which has been achieved in modified greenhouse dryer with inclined roof. Total weight of potato flakes was reduced by 80.1 % in modified greenhouse dryer in just 5 hours whereas it took 6 hours in simple greenhouse dryer for achieving nearly same values.

  7. Development of macroporous calcium phosphate scaffold processed via microwave rapid drying

    Energy Technology Data Exchange (ETDEWEB)

    Jamuna-Thevi, K., E-mail: jamuna@sirim.my [Advanced Materials Research Centre (AMREC), SIRIM Berhad, Lot 34, Jalan Hi-Tech 2/3, Kulim Hi-Tech Park, 09000 Kulim, Kedah (Malaysia); Zakaria, F.A. [Advanced Materials Research Centre (AMREC), SIRIM Berhad, Lot 34, Jalan Hi-Tech 2/3, Kulim Hi-Tech Park, 09000 Kulim, Kedah (Malaysia); Othman, R. [Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia, Seri Ampangan, 14300 Nibong Tebal, Penang (Malaysia); Muhamad, S. [Bioassay Unit, Herbal Medicine Research Centre (HMRC), Institute for Medical Research (IMR), Jalan Pahang, 50588 Kuala Lumpur (Malaysia)

    2009-06-01

    Porous hydroxyapatite (HA) scaffold has great potential in bone tissue engineering applications. A new method to fabricate macroporous calcium phosphate (CP) scaffold via microwave irradiation, followed by conventional sintering to form HA scaffold was developed. Incorporation of trisodium citrate dihydrate and citric acid in the CP mixture gave macroporous scaffolds upon microwave rapid drying. In this work, a mixture of {beta}-tricalcium phosphate ({beta}-TCP), calcium carbonate (CaCO{sub 3}), trisodium citrate dihydrate, citric acid and double distilled de-ionised water (DDI) was exposed to microwave radiation to form a macroporous structure. Based on gross eye examinations, addition of trisodium citrate at 30 and 40 wt.% in the CP mixture ({beta}-TCP and CaCO{sub 3}) without citric acid indicates increasing order of pore volume where the highest porosity yield was observed at 40 wt.% of trisodium citrate addition and the pore size was detected at several millimeters. Therefore, optimization of pore size was performed by adding 3-7 wt.% of citric acid in the CP mixture which was separately mixed with 30 and 40 wt.% of trisodium citrate for comparison purposes. Fabricated scaffolds were calcined at 600 deg. C and washed with DDI water to remove the sodium hydroxycarbonate and sintered at 1250 deg. C to form HA phase as confirmed in the X-ray diffraction (XRD) results. Based on Archimedes method, HA scaffolds prepared from 40 wt.% of trisodium citrate with 3-7 wt.% of citric acid added CP mixture have an open and interconnected porous structure ranging from 51 to 53 vol.% and observation using Scanning electron microscope (SEM) showed the pore size distribution between 100 and 500 {mu}m. The cytotoxicity tests revealed that the porous HA scaffolds have no cytotoxic potential on MG63 osteoblast-like cells which might allow for their use as biomaterials.

  8. Production of concentrated “Ya Pak King” drink by vacuum microwave drying

    Directory of Open Access Journals (Sweden)

    Wanprakeaw, P.

    2005-05-01

    Full Text Available Ya Pak King juice is currently popular among Thai consumers. However, some people do not like to drink it because of its pungent smell and flavor. The objectives of this investigation were to improve consumer perception of ready-to-drink Ya Pak King juice and to produce the concentrated drink by vacuum microwave drying. The herbal juice from Ya Pak King was prepared and formulated with lemon juice and honey by the Mixture Design. The drink flavor and taste were then modified by the addition of sugar and citric acid and the drink was, finally, concentrated by a vacuum microwave oven. The results showed that the ratio of the herbal juice: honey: lemon juice at 30:55:15 gave the highest acceptance score from panelists. In addition, the drink modified to achieve 20 0Brix total soluble solid and 0.45% acidity was the most acceptable. After testing the Ya Pak King beverage diluted from the concentrated drink and the drink before concentration, no significant difference in characteristics of the two products was found.

  9. Microwave-Assisted Extraction Studies of Target Analyte Artemisinin from Dried Leaves of Artemisia annua L.

    Directory of Open Access Journals (Sweden)

    Himanshu Misra

    2013-01-01

    Full Text Available Artemisia annua L. (Asteraceae is an annual herb native of Asia. This plant has been used for many centuries in traditional Chinese medicine for the treatment of fever and malaria. Conventional methods for the extraction of artemisinin from A. annua including solvent extraction, Soxhlet extraction, and heat reflux extraction are characterized by long extraction times and the consumption of large volume of solvents. A simple, rapid, and precise microwave-assisted extraction process was optimized for fast sample preparation for the faster quantitative determination of artemisinin, potential new generation antimalarial drug, from dried leaves of Artemisia annua L. A simple experiment was designed for the optimization of the appropriate solvent under same extraction conditions. The selected appropriate solvent was then standardized for various different extraction variables. The major parameters studied showed effects on extraction efficiency including processing time, strength of microwave, moisture content, volume and nature of the solvent. The most favorable conditions were obtained by using plant material of 25 mesh (particle size extracted with acetone for 120 seconds at 160 W (i.e., 20% of total power. Quantitative analysis was performed using thin-layer chromatography coupled with a densitometer (TLC densitometry. The results showed that MAE can be used as an efficient and rapid method for the extraction of the active components from plants.

  10. Experimental Analysis and Simultaneous Heat and Moisture Transfer with Coupled CFD Model for Convective Drying of Moist Object

    Science.gov (United States)

    Chandramohan, V. P.

    2016-01-01

    Convective drying of rectangular-shaped moist object has been analyzed both experimentally and numerically. Transient mass of the potato sample is measured experimentally. Moisture content, diffusivity, and density of the object are calculated at different drying air temperatures from 40°C to 70°C with an air velocity of 2 m/s. A three-dimensional (3D) finite volume method (FVM) based numerical model is developed to predict the temperature and moisture distribution. A computational fluid dynamics (CFD) code is used for predicting heat and mass transfer coefficients required in the boundary conditions of the heat and mass transfer model. The experimental and numerical data are compared and good agreement is observed.

  11. High Temperature Convective Drying of a Packed Bed with Humid Air at Different Humidities

    Directory of Open Access Journals (Sweden)

    J. Sghaier

    2009-01-01

    Full Text Available Problem statement: Drying a packed bed of porous particle at high temperature with varying humidity of hot air is an attractive process. Despite, many researches on experimental and simulation on a fixed bed drying at low and average temperature are proposed. Few studies showed drying at high temperature with humid air or using superheated steam. The latest is compared to dry air. Approach: In this study, we show an experimental and numerical study of humid air drying of a fixed bed of moist porous alumina particles. The air velocity, the air temperature and the vapor pressure were varied from 1.7-2.3 m.sec-1, 120-160°C and 0.1-0.65 bar, respectively and the experiments were performed at atmospheric pressure. Then a mathematical describing heat and mass transfer during drying is developed. This model is based on the averaging volume approach using two scale changes. Results: From the experimental works, the solid temperature and the bed moisture content have been presented at different drying conditions. The previous results show that an increase in humidity leads to an increase of the wet bulb temperature and a decrease in the drying time. At the same drying temperature, the variation in the gas velocity affects also the drying time. In addition, we note that the drying time increases if the bed depth increases. The predicted results deduced from the developed model were compared with the experiment. Conclusion: The experimental and predicted results obtained from this study describing drying of a packed bed illustrate clearly the effect of the air humidity on the drying kinetics.

  12. Regimes of dry convection above wildfires: Idealized numerical simulations and dimensional analysis

    Science.gov (United States)

    Michael T. Kiefer; Matthew D. Parker; Joseph J. Charney

    2009-01-01

    Wildfires are capable of inducing atmospheric circulations that result predominantly from large temperature anomalies produced by the fire. The fundamental dynamics through which a forest fire and the atmosphere interact to yield different convective regimes is still not well understood. This study uses the Advanced Regional Prediction System (ARPS) model to...

  13. Analysis of the application of an open-cycle absorption heat pump in industrial convection drying

    Energy Technology Data Exchange (ETDEWEB)

    Lazzarin, R.M.; Gasparella, A.; Longo, G.A. [Dipt. di Tecnica e Gestione dei Sistemi Industriali, Univ. degli Studi di Padova, Vicenza (Italy)

    1999-07-01

    Heat recovery in convection driers has been investigated comparing different solutions (regenerative heat exchanger, vapour compression heat pump, sorption dehumidification heat pump) in a specific application of food industry. Systems based on chemical dehumidification show the best performance allowing a primary energy saving higher than 40% with respect to traditional plants. (orig.)

  14. Performance of solar dryer chamber used for convective drying of sponge-cotton

    Directory of Open Access Journals (Sweden)

    Aissa Walid

    2014-01-01

    Full Text Available Solar dryer chamber is designed and operated for five days of July 2008. Drying experiments are conducted for sponge-cotton; as a reference drying material in the ranges between 35.0 to 49.5°C of ambient air temperature, 35.2 to 69.8 °C drying air temperature, 30 to 1258 W/m2 solar radiation and 0.016 to 0.08 kg/s drying air flow rate. For each experiment, the mass flow rate of the air remained constant throughout the day. The variation of moisture ratio, drying rate, overall dryer efficiency, and temperature distribution along the dryer chamber for various drying air temperatures and air flow rates are discussed. The results indicated that drying air temperature is the main factor in controlling the drying process and that air mass flow rate has remarkable influence on overall drying performance. For the period of operation, the dryer attained an average temperature of 53.68°C with a standard deviation of 8.49°C within a 12-h period from 7:00 h to 19:00 h. The results of this study indicated that the present drying system has overall efficiency between 1.85 and 18.6 % during drying experiments. Empirical correlations of temperature lapse and moisture ratio in the dryer chamber are found to satisfactorily describe the drying curves of sponge-cotton material which may form the basis for the development of solar dryer design charts.

  15. Drying characteristics of garlic ( Allium sativum L) slices in a convective hot air dryer

    Science.gov (United States)

    Demiray, Engin; Tulek, Yahya

    2014-06-01

    The effects of drying temperatures on the drying kinetics of garlic slices were investigated using a cabinet-type dryer. The experimental drying data were fitted best to the Page and Modified Page models apart from other theoretical models to predict the drying kinetics. The effective moisture diffusivities varied from 4.214 × 10-10 to 2.221 × 10-10 m2 s-1 over the temperature range studied, and activation energy was 30.582 kJ mol-1.

  16. Convective drying of regular mint leaves: analysis based on fitting empirical correlations, response surface methodology and neural networks

    Directory of Open Access Journals (Sweden)

    Ariany Binda Silva Costa

    2014-04-01

    Full Text Available In the present work, an analysis of drying of peppermint (Menta x villosa H. leaves has been made using empirical correlations, response surface models and a neural network model. The main goal was to apply different modeling approaches to predict moisture content and drying rates in the drying of leaves, and obtaining an overview on the subject. Experiments were carried out in a convective horizontal flow dryer in which samples were placed parallel to the air stream under operating conditions of air temperatures from 36 to 64°C, air velocities from 1.0 to 2.0 m s-1 and sample loads from 18 to 42 g, corresponding to sample heights of 1.4, 1.7 and 3.5 cm respectively. A complete 33 experimental design was used. Results have shown that the three methodologies employed in this work were complementary in the sense that they simultaneously provided a better understanding of leaves drying.

  17. Patterns of Precipitation and Convection Occurrence over the Mediterranean Basin Derived from a Decade of Microwave Satellite Observations

    Directory of Open Access Journals (Sweden)

    Bahjat Alhammoud

    2014-05-01

    Full Text Available The Mediterranean region is characterized by its vulnerability to changes in the water cycle, with the impact of global warming on the water resources being one of the major concerns in social, economical and scientific ambits. Even if precipitation is the best-known term of the Mediterranean water budget, large uncertainties remain due to the lack of suitable offshore observational data. In this study, we use the data provided by the Advanced Microwave Sounding Unit-B (AMSU-B on board NOAA satellites to detect and analyze precipitating and convective events over the last decade at spatial resolution of 0.2° latitude × 0.2° longitude. AMSU-B observation shows that rain occurrence is widespread over the Mediterranean in wintertime while reduced in the eastern part of the basin in summer. Both precipitation and convection occurrences display a weak diurnal cycle over sea. In addition, convection occurrences, which are essentially located over land during summertime, shift to mostly over the sea during autumn with maxima in the Ionian sub-basin and the Adriatic Sea. Precipitation occurrence is also inferred over the sea from two other widely used climatological datasets, HOAPS (Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite Data and the European Centre for Medium-Range Weather Forecasts (ECMWF reanalysis interim (ERA-Interim. There is generally a rather fair agreement between these climatologies for describing the large-scale patterns such as the strong latitudinal gradient of rain and eastward rain signal propagation. Furthermore, the higher spatial resolution of AMSU-B measurements (16 km at nadir gives access to mesoscale details in the region (e.g., coastal areas. AMSU-B measurements show less rain occurrences than HOAPS during wintertime, thereby suggesting that some of the thresholds used in our method might be too stringent during this season. We also observed that convection occurrences in ERA-Interim are systematically

  18. Mathematical modeling of drying of potato slices in a forced convective dryer based on important parameters.

    Science.gov (United States)

    Naderinezhad, Samira; Etesami, Nasrin; Poormalek Najafabady, Arefe; Ghasemi Falavarjani, Majid

    2016-01-01

    The effect of air temperature, air velocity, and sample shapes (circle and square with the same cross-sectional area) on kinetic drying of potato slices in a tunnel dryer was investigated experimentally and a suitable drying model was developed. The experiments of drying of potato slices were conducted at an air temperature of 45-70°C with an air velocity 1.60 and 1.81 m sec(-1). Results showed that drying temperature was the most effective parameter in the drying rate. The influence of air velocity was more profound in low temperature. The time for drying square slices was lower compared to the circle ones. Furthermore, drying data were fitted to different empirical models. Among the models, Midilli-Kucuk was the best to explain the single layer drying of potato slices. The parameters of this model were determined as functions of air velocity and temperature by multiple regression analysis for circle and square slices. Various statistical parameters were examined for evaluating the model.

  19. Mass transfer characteristics of bisporus mushroom ( Agaricus bisporus) slices during convective hot air drying

    Science.gov (United States)

    Ghanbarian, Davoud; Baraani Dastjerdi, Mojtaba; Torki-Harchegani, Mehdi

    2016-05-01

    An accurate understanding of moisture transfer parameters, including moisture diffusivity and moisture transfer coefficient, is essential for efficient mass transfer analysis and to design new dryers or improve existing drying equipments. The main objective of the present study was to carry out an experimental and theoretical investigation of mushroom slices drying and determine the mass transfer characteristics of the samples dried under different conditions. The mushroom slices with two thicknesses of 3 and 5 mm were dried at air temperatures of 40, 50 and 60 °C and air flow rates of 1 and 1.5 m s-1. The Dincer and Dost model was used to determine the moisture transfer parameters and predict the drying curves. It was observed that the entire drying process took place in the falling drying rate period. The obtained lag factor and Biot number indicated that the moisture transfer in the samples was controlled by both internal and external resistance. The effective moisture diffusivity and the moisture transfer coefficient increased with increasing air temperature, air flow rate and samples thickness and varied in the ranges of 6.5175 × 10-10 to 1.6726 × 10-9 m2 s-1 and 2.7715 × 10-7 to 3.5512 × 10-7 m s-1, respectively. The validation of the Dincer and Dost model indicated a good capability of the model to describe the drying curves of the mushroom slices.

  20. Experimental study of water desorption isotherms and thin-layer convective drying kinetics of bay laurel leaves

    Science.gov (United States)

    Ghnimi, Thouraya; Hassini, Lamine; Bagane, Mohamed

    2016-02-01

    The aim of this work is to determine the desorption isotherms and the drying kinetics of bay laurel leaves (Laurus Nobilis L.). The desorption isotherms were performed at three temperature levels: 50, 60 and 70 °C and at water activity ranging from 0.057 to 0.88 using the statistic gravimetric method. Five sorption models were used to fit desorption experimental isotherm data. It was found that Kuhn model offers the best fitting of experimental moisture isotherms in the mentioned investigated ranges of temperature and water activity. The Net isosteric heat of water desorption was evaluated using The Clausius-Clapeyron equation and was then best correlated to equilibrium moisture content by the empirical Tsami's equation. Thin layer convective drying curves of bay laurel leaves were obtained for temperatures of 45, 50, 60 and 70 °C, relative humidity of 5, 15, 30 and 45 % and air velocities of 1, 1.5 and 2 m/s. A non linear regression procedure of Levenberg-Marquardt was used to fit drying curves with five semi empirical mathematical models available in the literature, The R2 and χ2 were used to evaluate the goodness of fit of models to data. Based on the experimental drying curves the drying characteristic curve (DCC) has been established and fitted with a third degree polynomial function. It was found that the Midilli Kucuk model was the best semi-empirical model describing thin layer drying kinetics of bay laurel leaves. The bay laurel leaves effective moisture diffusivity and activation energy were also identified.

  1. Experimental study of water desorption isotherms and thin-layer convective drying kinetics of bay laurel leaves

    Science.gov (United States)

    Ghnimi, Thouraya; Hassini, Lamine; Bagane, Mohamed

    2016-12-01

    The aim of this work is to determine the desorption isotherms and the drying kinetics of bay laurel leaves ( Laurus Nobilis L.). The desorption isotherms were performed at three temperature levels: 50, 60 and 70 °C and at water activity ranging from 0.057 to 0.88 using the statistic gravimetric method. Five sorption models were used to fit desorption experimental isotherm data. It was found that Kuhn model offers the best fitting of experimental moisture isotherms in the mentioned investigated ranges of temperature and water activity. The Net isosteric heat of water desorption was evaluated using The Clausius-Clapeyron equation and was then best correlated to equilibrium moisture content by the empirical Tsami's equation. Thin layer convective drying curves of bay laurel leaves were obtained for temperatures of 45, 50, 60 and 70 °C, relative humidity of 5, 15, 30 and 45 % and air velocities of 1, 1.5 and 2 m/s. A non linear regression procedure of Levenberg-Marquardt was used to fit drying curves with five semi empirical mathematical models available in the literature, The R2 and χ2 were used to evaluate the goodness of fit of models to data. Based on the experimental drying curves the drying characteristic curve (DCC) has been established and fitted with a third degree polynomial function. It was found that the Midilli Kucuk model was the best semi-empirical model describing thin layer drying kinetics of bay laurel leaves. The bay laurel leaves effective moisture diffusivity and activation energy were also identified.

  2. Mathematical modeling of convective air drying of quinoa-supplemented feed for laboratory rats

    Directory of Open Access Journals (Sweden)

    Antonio Vega-Gálvez

    2011-02-01

    Full Text Available Drying kinetics of quinoa-supplemented feed for laboratory rats during processing at 50, 60, 70, 80 and 90ºC was studied and modeled in this work. Desorption isotherm was obtained at 60ºC giving a monolayer moisture content of 0.04 g water/g d.m. The experimental drying curves showed that drying process took place only in the falling rate period. Several thin-layer drying equations available in the literature were evaluated based on determination coefficient (r², sum squared errors (SSE and Chi-square (χ2 statisticals. In comparison to the experimental moisture values, the values estimated with the Logarithmic model gave the best fit quality (r² >0.994, SSE < 0.00015 and χ2 < 0.00018, showing this equation could predict very accurately the drying time of rat feed under the operative conditions applied.

  3. The analysis of the drying process on unsteady forced convection in thin films of ink

    Energy Technology Data Exchange (ETDEWEB)

    Avci, Atakan; Can, Muhiddin [Uludag Univ., Dept. of Mechanical Engineering, Bursa (Turkey)

    1999-06-01

    High velocity impinging air jets are commonly used to accelerate the evaporative ink drying process due to the high heat and mass transfer rates which are developed in the impingement region. Comparative heat transfer studies are given to establish the optimum variables such as nozzle shapes, size and pitch, nozzle distance from surface, to minimize the capital and running costs of the drying plant. At the present, when energy costs are high, designs which require large quantities of high air jet velocity and high air temperature are unattractive. In order to provide data for designers of industrial dryers, a program of research has been implemented to study the analogy between the heat and mass transfer processes which constitute the ink drying process. Different fuels for ink drying are compared on a common energy available basis. The most economical case for fan power and heating power was found to be natural gas as fuel. (Author)

  4. Effects of convective and microwave roasting on the physicochemical properties of cocoa beans and cocoa butter extracted from this material

    Directory of Open Access Journals (Sweden)

    Krysiak, W.

    2011-12-01

    Full Text Available The cocoa beans of the Ivory Coast variety were convectively and microwave roasted. The effects of roasting conditions on the principal physicochemical attributes (water and fat contents, total and volatile acidity of roasted cocoa beans and the properties of fat extracted from this material (acidity, saponification index, iodine index, peroxide value, light refraction coefficient, polar fraction content, and Fatty Acid profile, absorbancy of 1 and 10% solution in hexane were examined. The characteristics of roasted and raw cocoa beans and their lipid fractions were compared. Results of analyses showed that convective roasting for 35 min at 135°C, air flow rate 1.0mxs-1 and relative humidity RH of 0.45% caused the least advanced changes in fat quality while microwave roasting promoted oxidation of lipids although the quality of roasted cocoa beans was the best.

    Granos de cacao de la variedad Costa de Marfil se han sometido a tostado mediante convección y microondas. Se ha estudiado el efecto de las condiciones de tostado sobre los atributos físico-químicos principales (contenido de agua y grasa, acidez total y volátil del cacao en grano tostado y las propiedades de la grasa extraída de este material (Acidez, índice de saponificación, índice de peróxidos, índice de yodo, índice de refracción, contenido de fracción polar, perfil de ácidos grasos, absorbancia de una solución al 10% en hexano. Se han comparado las características de los granos de cacao tostados y crudos y sus fracciones lipídicas. Los resultados de los análisis mostraron que el tostado mediante convección durante 35 minutos a 135°C, con un caudal de aire de 1,0 m s-1 y HR de 0,45 causó los menores cambios en la calidad de grasa mientras que el tostado mediante microondas promovió en mayor medida la oxidación de los lípidos aunque la calidad de los granos de cacao tostado fue mejor.

  5. Validation Experiments for Spent- Fuel Dry-Cask In-Basket Convection

    Energy Technology Data Exchange (ETDEWEB)

    Smith, barton [Utah State Univ., Logan, UT (United States)

    2016-08-16

    This work consisted of the following major efforts; 1. Literature survey on validation of external natural convection; 2. Design the experiment; 3. Build the experiment; 4. Run the experiment; 5. Collect results; 6. Disseminate results; and 7. Perform a CFD validation study using the results. We note that while all tasks are complete, some deviations from the original plan were made. Specifically, geometrical changes in the parameter space were skipped in favor of flow condition changes, which were found to be much more practical to implement. Changing the geometry required new as-built measurements, which proved extremely costly and impractical given the time and funds available

  6. Validation Experiments for Spent-Fuel Dry-Cask In-Basket Convection

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Barton L. [Utah State Univ., Logan, UT (United States). Dept. of Mechanical and Aerospace Engineering

    2016-08-16

    This work consisted of the following major efforts; 1. Literature survey on validation of external natural convection; 2. Design the experiment; 3. Build the experiment; 4. Run the experiment; 5. Collect results; 6. Disseminate results; and 7. Perform a CFD validation study using the results. We note that while all tasks are complete, some deviations from the original plan were made. Specifically, geometrical changes in the parameter space were skipped in favor of flow condition changes, which were found to be much more practical to implement. Changing the geometry required new as-built measurements, which proved extremely costly and impractical given the time and funds available

  7. Drying of prickly pear cactus cladodes (Opuntia ficus indica) in a forced convection tunnel

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, R.; de Ita, A.; Vaca, M. [Universidad Autonoma Metropolitana-Azcapotzalco, DePt. de Energia, Area de Termofluidos, Av. San Pablo 180, Col. Reynosa Tamaulipas, Del. Azcapotzalco, C.P. 02200, Mexico D.F. (Mexico)

    2009-09-15

    In this work we evaluated the kinetics of drying of Opuntia's cladodes observing two conditions: complete cladode with the protective cuticle of the intact product and with reduced cuticle (partially removed), using a drying tunnel with forced flow. The temperature of the air was set at 35, 45, and 60 C with velocities of 1.5 and 3.0 m/s. The conditions of the environment were controlled and maintained at 22 C and 30% of relative humidity. The results show that the drying time was considerably reduced when approximately 30% of the cuticle that protects the product was removed. Additionally, the temperature had greater influence than the velocity of the air. The numerical model that best describes the behavior of the drying process is the double logarithmic one, with the imposed restrictions of r close to the unit, the lowest possible {chi}{sup 2} and the RSEM tending to zero. The characteristic drying function of the product resulted in a third-grade exponential curve, where r and SD were the corresponding selection criteria. (author)

  8. Ultra-fast dry microwave preparation of SnSb used as negative electrode material for Li-ion batteries

    Science.gov (United States)

    Antitomaso, P.; Fraisse, B.; Sougrati, M. T.; Morato-Lallemand, F.; Biscaglia, S.; Aymé-Perrot, D.; Girard, P.; Monconduit, L.

    2016-09-01

    Tin antimonide alloy was obtained for the first time using a very simple dry microwave route. Up to 1 g of well crystallized SnSb can be easily prepared in 90 s under air in an open crucible. A full characterization by X-ray diffraction and 119Sn Mössbauer spectroscopy demonstrated the benefit of carbon as susceptor, which avoid any oxide contamination. The microwave-prepared SnSb was tested as negative electrode material in Li batteries. Interesting results in terms of capacity and rate capability were obtained with up to 700 mAh/g sustained after 50 cycles at variable current. These results pave the way for the introduction of microwave synthesis as realistic route for a rapid, low cost and up-scalable production of electrode material for Li batteries or other large scale application types.

  9. Experimental investigation of convective drying kinetics of kiwi under different conditions

    Science.gov (United States)

    Darıcı, Selçuk; Şen, Soner

    2015-08-01

    The effects of air temperature, velocity and humidity on drying characteristics of kiwi are experimentally investigated for the temperatures in the range of 50-80 °C, of the velocities 0.5-2.0 m/s, of the relative humidity values of 5-20 % and for two slice thicknesses. It is observed that there is a very close agreement between the model of Midilli et al. (Dry Technol 20:1503-1513, 2002) and the present study with coefficients of correlation R2 of 0.9949-0.9996.

  10. Drying and moistening by deep sub-tropical and tropical convection in large-eddy simulations of CRYSTAL-FACE and CEPEX field measurements

    Science.gov (United States)

    Ackerman, A. S.; Fridlind, F. M.; Jensen, E. J.; Stevens, D. E.; Miloshevich, L. M.; Baumgardner, D.; Lawson, P.

    2003-12-01

    Deep convection has been proposed to be a leading mechanism controlling the moisture in the lower stratosphere. We evaluate this hypothesis with large-eddy simulations that resolve the size distributions of aerosols and cloud particles over 100-km square square domain using pre-convective Miami and PARSL soundings, initiating convection with enough of a surface heat source to match the observed anvil altitudes. Differencing the moisture field after the anvils decay with the initial state, we find that convection predominantly moistens the transitional tropopause layer (TTL), although some drying is predicted in localized layers. Beyond the sub-tropical convection of Florida we also use frostpoint hygrometer soundings obtained during the CEPEX mission in the tropical western Pacific, which show repeated evidence of supersaturated layers within the TTL. In such cases we find that deep convection dries out the supersaturated layers while moistening the air above and below. We also analyze the environmental and temporal dependence of the time constants of sedimentation, evaporation, and mixing of water.

  11. Optimization of microwave-assisted drying of Jerusalem artichokes (Helianthus tuberosus L. by response surface methodology and genetic algorithm

    Directory of Open Access Journals (Sweden)

    E. KARACABEY

    2016-03-01

    Full Text Available The objective of the present study was to investigate microwave-assisted drying of Jerusalem artichoke tubers to determine the effects of the processing conditions. Drying time (DT and effectivemoisture diffusivity (EMD were determined to evaluate the drying process in terms of dehydration performance, whereas the rehydration ratio (RhR was considered as a significant quality index. A pretreatment of soaking in a NaCl solution was applied before all trials. The output power of the microwave oven, slice thickness and NaCl concentration of the pretreatment solution werethe three investigated parameters. The drying process was accelerated by altering the conditions while obtaining a higher quality product. For optimization of the drying process, response surface methodology (RSM and genetic algorithms (GA were used. Model adequacy was evaluated for each corresponding mathematical expression developed for interested responses by RSM. The residual of the model obtained by GA was compared to that of the RSM model. The GA was successful in high-performance prediction and produced results similar to those of RSM. The analysis and results of the present study show that both RSM and GA models can be used in cohesion to gain insight into the bioprocessing system.

  12. 微波及辐射真空干燥过程中的干燥动力学及能量消耗%Drying Kinetics and Energy Consumption in Vacuum Drying Process with Microwave and Radiant Heating

    Institute of Scientific and Technical Information of China (English)

    M. Kamel; J.I. Lombra(n)a; C. de Elvira; R. Rodr(i)guez

    2004-01-01

    The general objective of this work is to analyze energy input in a vacuum process with the incorporation of microwave heating. Thus, necessary criteria for designing an efficient freeze-drying operation are considered through the analysis of strategies based on the combination of different intensities of radiant and microwave heating.The other aim of this research topic is to study the kinetics of drying in relation to mass transfer parameters.Five freeze-drying strategies using both heating systems were used. Consequently, energy input could be related to diffusivity coefficients, temperature and pressure profiles during dehydration of the product and analyzed in comparison to a conventional freeze-drying process.

  13. Effect of Surface Omniphobicity on Drying by Forced Convection (Briefing Charts)

    Science.gov (United States)

    2015-08-01

    Guenthner 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION...unlimited. AFRL Public Affairs Clearance # Background • I am from Bangladesh . • Education: The City College of New York • Major: Chemistry; Minor: Education...implemented to explore the optimum conditions for a fast drying low energy surface. The use of DOE and the results of this experiment are merged into a

  14. Quality assessment of microwave-vacuum dried material with the use of computer image analysis and neural model

    Science.gov (United States)

    Koszela, K.; OtrzÄ sek, J.; Zaborowicz, M.; Boniecki, P.; Mueller, W.; Raba, B.; Lewicki, A.; Przybył, K.

    2014-04-01

    The farming area for vegetables in Poland is constantly changed and modified. Each year the cultivation structure of particular vegetables is different. However, it is the cultivation of carrots that plays a significant role among vegetables. According to the Main Statistical Office (GUS), in 2012 carrot held second position among the cultivated root vegetables, and it was estimated at 835 thousand tons. In the world we are perceived as the leading producer of carrot, due to the fourth place in the ranking of global producers. Poland is the largest producer of this vegetable in the EU [1]. It is also noteworthy, that the demand for dried vegetables is still increasing. This tendency affects the development of drying industry in our country, contributing to utilization of the product surplus. Dried vegetables are used increasingly often in various sectors of food products industry, due to high nutrition value, as well as to changing alimentary preferences of consumers [2-3]. Dried carrot plays a crucial role among dried vegetables, because of its wide scope of use and high nutrition value. It contains a lot of carotene and sugar present in the form of crystals. Carrot also undergoes many different drying processes, which makes it difficult to perform a reliable quality assessment and classification of this dried material. One of many qualitative properties of dried carrot, having important influence on a positive or negative result of the quality assessment, is color and shape. The aim of the research project was to develop a method for the analysis of microwave-vacuum dried carrot images, and its application for the classification of individual fractions in the sample studied for quality assessment. During the research digital photographs of dried carrot were taken, which constituted the basis for assessment performed by a dedicated computer programme developed as a part of the research. Consequently, using a neural model, the dried material was classified [4-6].

  15. DEVELOPMENT OF MATHEMATICAL MODEL OF PROCESS OF BLACK CURRANT BERRIES DRYING IN VACUUMDEVICE WITH THE MICROWAVE POWER SUPPLY

    Directory of Open Access Journals (Sweden)

    S. T. Antipov

    2014-01-01

    Full Text Available Summary. The mathematical model allowed to reproduce and study at qualitative level the change of berries form and the structure of the berries layer in the course of drying. The separate berry in the course of drying loses gradually its elasticity, decreases in volume, the peel gathers in folds, there appear internal emptiness. In the course of drying the berries layer decreases in thickness, contacting berries stick strongly with each other due to the coordinated folds of peel appearing, the layer is condensed due to penetration of the berries which have lost elasticity into emptiness between them. The model with high specification describes black currant drying process and therefore has a large number of the parameters available to change. Among them three most important technological parameters, influencing productivity and the drying quality are chosen: the power of microwave radiation P, thickness of the berries layer h, environmental pressure p. From output indicators of the model the most important are three functions from time: dependence of average humidity of the layer on time Wcp (t, dependence of the speed of change of average humidity on time dWcp (t/dt, dependence of the layer average temperature on time Tср (t. On the standard models classification the offered model is algorithmic, but not analytical. It means that output characteristics of model are calculated with the entrance ones, not by analytical transformations (it is impossible principally for the modeled process, but by means of spatial and temporary sampling and the corresponding calculation algorithm. Detailed research of the microwave drying process by means of the model allows to allocate the following stages: fast heating, the fast dehydration, the slowed-down dehydration, consolidation of a layer of a product, final drying, heating after dehydration.

  16. Effect of microwave drying and oven drying on the water activity, color, phenolic compounds content and antioxidant activity of coconut husk (Cocos nucifera L.).

    Science.gov (United States)

    Valadez-Carmona, Lourdes; Cortez-García, Rosa María; Plazola-Jacinto, Carla Patricia; Necoechea-Mondragón, Hugo; Ortiz-Moreno, Alicia

    2016-09-01

    The coconut (Cocos nucifera L.) husk is basically composed by fiber and pith material and remained under-utilized. This is an important source of phenolic compounds that could be used as functional ingredients. The aim of this study was to determine the effect of: oven-drying (OD) and microwave drying (MD), on the water activity, color, phenolic compound content and antioxidant activity of coconut husk. The OD was performed at 60 °C for 12 h and MD was performed at 900 W for 10 min. The total phenolic content (TPC) in fresh coconut husk was 64.2 mg GAE/g dry wt and significant higher than observed after OD and MD of 35.8 and 45.5 mg GAE/g dry wt, respectively. Ten phenols were identified in fresh and dehydrated coconut husks. The husk MD showed an increase in the content of gallic, 4-hydroxybenzoic, ferulic and syringic acids and epicatechin compared with the fresh; while coconut husk OD and MD, showed a decrease in the content of vanillic acid, vanillin, catequin and kaempferol. The antioxidant activity decreased after both OD and MD. However, MD resulted in a better antioxidant activity in husk than OD. MD of husk resulted into better retention of preserved color, TPC and TFC than OD.

  17. The effect of variety and maturity on the quality of freeze-dried carrots. The effect of microwave blanching on the nutritional and textural quality of freeze-dried spinach

    Science.gov (United States)

    1979-01-01

    Using carrots, the quality of freeze-dried products was studied to determine the optimum varieties and maturation stages for quality attributes such as appearance, flavor, texture, and nutritive value. The quality of freeze-dried carrots is discussed in terms of Gardner color, alcohol insoluble solids, viscosity, and core/cortex ratio. Also, microwave blanching of freeze-dried spinach was studied to determine vitamin interrelationships, anatomical changes, and oxidative deteriorations in terms of preprocessing microwave treatments. Statistical methods were employed in the gathering of data and interpretation of results in both studies.

  18. Connecting Surface Emissions, Convective Uplifting, and Long-Range Transport of Carbon Monoxide in the Upper Troposphere: New Observations from the Aura Microwave Limb Sounder

    Science.gov (United States)

    Jiang, Jonathan H.; Livesey, Nathaniel J.; Su, Hui; Neary, Lori; McConnell, John C.; Richards, Nigel A. D.

    2007-01-01

    Two years of observations of upper tropospheric (UT) carbon monoxide (CO) from the Aura Microwave Limb Sounder are analyzed; in combination with the CO surface emission climatology and data from the NCEP analyses. It is shown that spatial distribution, temporal variation and long-range transport of UT CO are closely related to the surface emissions, deep-convection and horizontal winds. Over the Asian monsoon region, surface emission of CO peaks in boreal spring due to high biomass burning in addition to anthropogenic emission. However, the UT CO peaks in summer when convection is strongest and surface emission of CO is dominated by anthropogenic source. The long-range transport of CO from Southeast Asia across the Pacific to North America, which occurs most frequently during boreal summer, is thus a clear imprint of Asian anthropogenic pollution influencing global air quality.

  19. Self-adaptive PID controller of microwave drying rotary device tuning on-line by genetic algorithms

    Institute of Scientific and Technical Information of China (English)

    杨彪; 梁贵安; 彭金辉; 郭胜惠; 李玮; 张世敏; 李英伟; 白松

    2013-01-01

    The control design, based on self-adaptive PID with genetic algorithms(GA) tuning on-line was investigated, for the temperature control of industrial microwave drying rotary device with the multi-layer(IMDRDWM) and with multivariable nonlinear interaction of microwave and materials. The conventional PID control strategy incorporated with optimization GA was put forward to maintain the optimum drying temperature in order to keep the moisture content below 1%, whose adaptation ability included the cost function of optimization GA according to the output change. Simulations on five different industrial process models and practical temperature process control system for selenium-enriched slag drying intensively by using IMDRDWM were carried out systematically, indicating the reliability and effectiveness of control design. The parameters of proposed control design are all on-line implemented without iterative predictive calculations, and the closed-loop system stability is guaranteed, which makes the developed scheme simpler in its synthesis and application, providing the practical guidelines for the control implementation and the parameter design.

  20. Linear dimensional change, compressive strength and detail reproduction in type IV dental stone dried at room temperature and in a microwave oven.

    Science.gov (United States)

    Silva, Marcos Aurélio Bomfim da; Vitti, Rafael Pino; Consani, Simonides; Sinhoreti, Mário Alexandre Coelho; Mesquita, Marcelo Ferraz; Consani, Rafael Leonardo Xediek

    2012-01-01

    The type IV dental stone is widely used for the fabrication of dyes and master casts for fixed and removable partial prostheses. It is typically normal to wait at least 24 hours for the casts to dry prior to beginning the laboratory procedures. The waiting time has been shown to be greatly reduced by using microwave drying. This study evaluated the influence of drying techniques at room temperature and microwave oven on the linear dimensional change, compressive strength and detail reproduction in type IV dental stones. Three type IV dental stone brands were selected; elite Rock, Shera Premium and Durone IV. Two different drying protocols were tested in 4 groups (n=10); G-room temperature (25±4 ºC) dried for 2 hours; G2--room temperature dried for 24 hours; G3-room temperature dried for 7 days and G4--microwave oven dried at 800 W for 5 minutes and after 2 hours at room temperature. After drying, the samples were assayed for dimensional charges. The sample surface was submitted to the ImageTool 3.0 software for compressive strength in a universal testing machine with a cell load of 50 KN at a crosshead speed of 0.5 mm/minutes and the detail reproduction was analyzed with a stereomicroscope at 25x magnification. The statistical analysis of the linear dimensional change and compressive strength data were conducted by the ANOVA test followed by the Tukey test (pmicrowave oven drying showed a linear dimensional change similar to after room temperature drying for 24 hours and 7 days. The compressive strength of the stone dried in the microwave oven was similar to those dried at room temperature for 24 hours, with the exception of Shera Premium, which had similar results for microwave and room temperature drying for 7 days. For the microwave drying method the detail reproduction levels for samples dried at room temperature for 24 hours and 7 days were similar, except for the Durone IV.

  1. Potential of microwave observations for the evaluation of rainfall and convection in a regional climate model in the frame of HyMeX and MED-CORDEX

    Science.gov (United States)

    Rysman, Jean-François; Berthou, Ségolène; Claud, Chantal; Drobinski, Philippe; Chaboureau, Jean-Pierre; Delanoë, Julien

    2016-06-01

    This study evaluates the potential of spaceborne passive microwave observations for assessing decadal simulations of precipitation from a regional climate model through a model-to-satellite approach. A simulation from the Weather and Research Forecasting model is evaluated against 2002-2012 observations from the Advanced Microwave Sounding Unit and the Microwave Humidity Sounder over the Mediterranean region using the radiative transfer code Radiative Transfer for Tiros Operational Vertical Sounder. It is first shown that simulated and observed brightness temperatures are consistently correlated for both water vapour and window channels. Yet, although the average simulated and observed brightness temperatures are similar, the range of brightness temperatures is larger in the observations. The difference is presumably due to the too low content of frozen particles in the simulation. To assess this hypothesis, density and altitude of simulated frozen hydrometeors are compared with observations from an airborne cloud radar. Results show that simulated frozen hydrometeors are found at lower median altitude than observed frozen hydrometeors, with an average content at least 5 times inferior. Spatial distributions of observed and simulated precipitation match reasonably well. However, when using simulated brightness temperatures to diagnose rainfall, the simulation performs very poorly. These results highlight the need of providing more realistic frozen hydrometeors content, which will increase the interest of using passive microwave observations for the long-term evaluation of regional models. In particular, significant improvements are expected from the archiving of convective fluxes of precipitating hydrometeors in future regional model simulation programs.

  2. Impact of different drying parameters on color, β-carotene, antioxidant activity and minerals of apricot (Prunus armeniacaL.

    Directory of Open Access Journals (Sweden)

    Bige İNCEDAYI

    2016-03-01

    Full Text Available Abstract Apricot is one of the fruits dried by using different methods, such as sun, convective or microwave drying. The effects of drying methods on the components of this fruit differ depending upon the temperature or time parameters. In this research, the impacts of convective, microwave and microwave–convective drying techniques on color, β-carotene, minerals and antioxidant activity of apricots were investigated. The color values (L*, b*,ΔEab, h° and C*ab of dried fruit were decreased, while the a* values increased. Compared with a fresh sample, the dried apricots showed a 1.4-3.9-fold proportional increase in β-carotene based on the increment of dry matter. The samples dried at high temperature and microwave levels, at 75 °C+90 watt and 75 °C+160 watt, showed lower antioxidant activity. Of the different drying treatments, the microwave-convective method (50 °C+160 watt obtained a higher β-carotene content while maintaining antioxidant activity with a short drying time.

  3. Application of Microwave in Organic Synthesis. Dry Synthesis of 2-Arylmethylene-3(2-naphthofuranones

    Directory of Open Access Journals (Sweden)

    Nathalie Bar

    1998-03-01

    Full Text Available 3(2-Naphthofuranone (1 was condensed in the presence of Al2O3-KF with aromatic aldehydes (4 to give arylidenenaphthofuranones (5a-f without solvent under focused microwave irradiation.

  4. Microwave drying for safe storage and improved nutritional quality of green gram seed (Vigna radiata).

    Science.gov (United States)

    Pande, Ranjana; Mishra, H N; Singh, M N

    2012-04-11

    The present study describes the effect of the microwave-heating method on disinfestations and physico characteristics, viz., grain size, grain hardness, and nutritional quality, of the stored green gram seed. It has been observed that the use of the microwave-heating method not only prolongs the storage duration of the green gram seed but also enhances its nutritional quality. The effect of independent parameters, viz., microwave power level and time of exposure, on the moisture content, insect mortality, color, and antinutrient factor (phyic acid) was optimized using response surface methodology (RSM), with the optimized value for power of 808 W and time at 80 s. The optimally treated green gram seed has 8.9% moisture, 99.5% insect mortality, 2.22 Δa* (green color of seed), and 591.79 mg/100 g of antinutrient factor (phytic acid). The grain size (geometric mean diameter, D(m)) of the control (untreated) sample was 3.75 mm, and that of the microwave-treated sample using optimum conditions was 3.99 mm. The grain hardness of the control sample was 3.31 kg, and that of the microwave-treated sample using optimum conditions was 1.305 kg. In vitro protein digestibility (IVPD) of the control (untreated) sample was 83 ± 0.289%, and that of the microwave-treated sample using optimum conditions was 85 ± 0.296%. These values are significantly difference (p microwave treatment resulted in a non-significant (p microwave heating not only increases the insect mortality but also reduces the moisture content and antinutritional factor (phytic acid), while the natural green color of the seed is not affected much. This study provides a novel and environmentally safe technique and increase in the nutritive quality.

  5. Investigation of some pretreatments on energy and specific energy consumption drying of black mulberry

    Directory of Open Access Journals (Sweden)

    Adabi Esmaeili Mohammad

    2013-01-01

    Full Text Available Massive consumption of energy in drying industry makes it a matter of challenge regarding economical aspects and limited recourses. Several methods for drying including hot air convection, vacuum, infrared and hot air convection-infrared technologies were applied in order to estimate the consumed energy during the drying of mulberry fruit. Moreover, microwave heating, chemical (ethyl oleate and potassium, mechanical (ultrasonic and blanching (hot water pretreatments were compared. According to the Results, maximum energy consumption was recorded when no pretreatment was performed. Microwave heating in the hot air convection-infrared dryer resulted in the lowest consumption of energy. Total energy requirement decreased with the temperature in the convection dryer res. Conversely, energy increased with air velocity. The vacuum dryer consumed the highest amount of energy which was measured to be 46.95 kWh while the lowest energy was recorded with using infrared-convective dryers. Also Experimental results showed that minimum and maximum specific energy consumption in the drying of black mulberry were associated with microwave pretreatment in IR-hot air dryer and control treatment in vacuum dryer, respectively. The minimum color change (ΔE for drying of black mulberry was found in microwave pretreated samples dried with the vacuum dryer, yet maximum ΔE was observed in hot air dryer when no pretreatment was applied.

  6. 牡蛎微波干燥特性及动力学研究%Characteristics and Kinetics of Microwave Drying for Oyster

    Institute of Scientific and Technical Information of China (English)

    余炼; 颜栋美; 侯金东

    2012-01-01

    Water content and dehydration rate of oyster subjected to microwave drying at various microwave intensifies were determined. The effect of microwave intensity on rehydration rate, shrinkage rate and surface color of dried oyster were explored. The results showed that dehydration rate was improved and drying time was shortened with increasing microwave intensity. The time required for microwave drying of oyster was in the range of 3.5-30 min. Microwave dried oyster at middle intensity level such as 5 W/g or 8 Wig revealed better quality. A microwave drying kinetic model was established by the Page equation with excellent fitting degree.%测定不同微波强度下牡蛎干燥水分曲线及失水速率曲线,考察不同微波强度对牡蛎干制品的复水增重率、收缩率、色差等品质方面的影响。结果表明:增大微波干燥强度可提高干燥速率,缩短干燥时间。在实验条件下,采用中等强度的微波干燥(如5、8W/g),牡蛎微波干燥时间在3.5~30min范围内。牡蛎品质较好。用Page方程建立的牡蛎微波干燥模型,与实验测定值的拟合度较高。

  7. Study on the Volatility of Cesium in Dry Ashing Pretreatment and Dissolution of Ash by Microwave Digestion System - 13331

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Kwang-Soon; Lee, Chang Heon; Ahn, Hong-Joo; Park, Yong Joon; Song, Kyuseok [Nuclear Chemistry Research Division, Korea Atomic Energy Research Institute, Daedeok-daero 989-111, Yuseong-gu, Daejeon, 305-353 (Korea, Republic of)

    2013-07-01

    Based on the regulation of the activity concentration of Cs-137, Co-58, Co-60, Fe-55, Ni-59, Ni-63, Sr-90, Nb-94, and Tc-99, and the total alpha from the radioactive waste acceptance criteria, the measurement of the activity concentration of these nuclides in low and intermediate levels of radioactive waste such as in paper, cotton, vinyl and plastic samples was investigated. A dry ashing method was applied to obtain a concentration effect of the samples. Owing to the temperature dependence of the volatility for cesium, the temperature of 300 to 650 deg. C was examined. It was found that 450 deg. C is the optimum dry ashing temperature. After dry ashing, the produced ash was dissolved with HNO{sub 3}, HCl, and HF by a high-performance microwave digestion system. The ash sample, for the most part, was completely dissolved with 10 mL of HNO{sub 3}, 4 mL of HCl, and 0.25 mL of HF by a high-performance microwave digestion system using a nova high temperature rotor at 250 deg. C for 90 min until reaching 0.2 g. To confirm the reliability of cesium loss after the performance of the dry ashing procedure, a cesium standard solution for AAS and a Cs-137 standard solution for gamma spectrometry were added to a paper towel or a planchet of stainless steel, respectively. Cesium was measured by AAS, ICP-MS, and gamma spectrometry. The volatility of cesium did not occur until 450 deg. C ashing. (authors)

  8. Hydrodistillation and in situ microwave-generated hydrodistillation of fresh and dried mint leaves: a comparison study.

    Science.gov (United States)

    Orio, Laura; Cravotto, Giancarlo; Binello, Arianna; Pignata, Giuseppe; Nicola, Silvana; Chemat, Farid

    2012-12-01

    Hydrodistillation (HD) has been used since ancient times for the extraction of essential oils (EO). Despite the intrinsic limitations of this technique, it remains the most common method both in the laboratory and on an industrial scale. The main drawbacks are the long extraction time involved and the risk of thermal degradation. Over the last decade, microwave-assisted extraction (MAE) and in situ microwave-generated hydrodistillation (MGH) have been shown to be the most promising techniques in improving plant extraction and hydrodistillation. In this study we compare HD with MGH in the extraction of several mint species cultivated in Piedmont: Mentha spicata L. var. rubra, Mentha spicata L. var. viridis and Mentha piperita L. MGH requires either fresh plant or rehydrated material, it is extremely fast and allows a reduction in energy consumption and overall cost. All the EO have been analyzed by gas chromatography-mass spectrometry. A mechanism of microwave-generated essential oil extraction has been proposed to explain the differences in the composition of the oil obtained from this environmentally friendly technique. The yields and composition percentages of the EO obtained by HD and in situ MGH of fresh and dried mint leaves lie in a relatively narrow range, although MGH is faster. MW polarization effects and the water solubility of the components influence extract composition. Copyright © 2012 Society of Chemical Industry.

  9. Gas chromatography-mass spectrometry following microwave distillation and headspace solid-phase microextraction for fast analysis of essential oil in dry traditional Chinese medicine.

    Science.gov (United States)

    Li, Ning; Deng, Chunhui; Li, Yan; Ye, Hao; Zhang, Xiangmin

    2006-11-10

    In this paper, a novel method based on gas chromatography-mass spectrometry (GC-MS) following microwave distillation-headspace solid-phase microextraction (MD-HS-SPME) was developed for the determination of essential oil in dry traditional Chinese medicine (TCM). TCM is dried before being preserved and used, there is too little water to absorb microwave energy and heat the TCM samples. In the work, carbonyl iron powders (CIP) was added and mixed with the dried TCM sample, which was used as microwave absorption solid medium for dry distillation of the TCM. At the same time, SPME was used for the extraction and concentration of essential oil after MD. The dry rhizomes of Atractylodes lancea DC was used as the model TCM, and used in the study. The MD-HS-SPME parameters including fiber coating, microwave power, irradiation time, and the amount of added CIP, were studied. To demonstrate the method feasibility, the conventional HS-SPME method was also used for the analysis of essential oil in the TCM. Experimental results show that more compounds were isolated and identified by MD-HS-SPME than those by HS-SPME. Compared to conventional HS-SPME, the advantages of the proposed method are: short extraction time and high extraction efficiency. All experimental results show that the proposed method is an alternative tool for fast analysis of essential oils in dry TCMs.

  10. 微波干燥技术在浓缩丸生产中的应用%Application of Microwave Drying Technology in Production of Concentrated Pill

    Institute of Scientific and Technical Information of China (English)

    李慧; 周里欣

    2011-01-01

    目的:考察微波干燥技术在浓缩丸生产中的效果.方法:用微波干燥工艺对3个浓缩丸品种进行试验,对比烘箱干燥工艺数据.结果:产品的性状、溶散时限、水分、微生物限度等质量指标均符合标准规定,微波干燥效果更明显.结论:微波干燥具有加热均匀、干燥时间短、提高药品质量的特点,在浓缩丸生产中可以广泛使用.%Objective;To investigate effect of microwave drying technology in the production of concentrated pill. Method; Three varieties pills were tested by microwave drying process, compared technology data with oven drying. Result; The character of products, time-limit of dissolve, moisture, the limit of microorganism were all accord with the regulation of standard. Microwave drying was more effective. Conclusion; Microwave drying had characteristics of uniform heating, drying time was short, improved drug quality and so on. It can be widely used in the production of concentrated pill.

  11. 微波真空冷冻干燥对芒果干制品品质特性的影响%Effect of Microwave Vacuum Freeze Drying on the Quality of Dried Mango

    Institute of Scientific and Technical Information of China (English)

    姜唯唯; 刘刚; 张晓喻; 范辉建; 张宏

    2012-01-01

    为获得较优的芒果干燥方法,以复水性、感官为评价指标,比较微波真空冷冻干燥、热板真空冷冻干燥和热风干燥3种不同干燥方法对芒果干制品品质的影响。结果表明:真空冷冻干燥法的产品各项指标均优于热风干燥法。微波真空冷冻干燥的产品复水性最好,25℃与100℃最大复水比分别为3.363、3.674;其次为热板真空冷冻干燥,两温度条件下与微波真空冷冻干燥产品复水比相差较小;热风干燥产品复水性最差,分别为2.140、3.028。感官指标中色泽、香气和口味3方面均为:微波真空冷冻干燥〉热板真空冷冻干燥〉热风干燥。%In order to obtain a better drying method for mango products, the effects of microwave vacuum freeze drying, hot- plate vacuum freeze drying and hot air drying on the rehydration rate and sensory quality of dried mango were comparatively analyzed. The results indicated that vacuum freeze drying could provide better indices of dried products when compared with hot-air drying. Microwave vacuum freeze dried mango exhibited the best rehydration performance with rehydration rates of 3.363 and 3.674 at 25 ~C and 100 ~C, respectively, followed by hot-plate vacuum freeze dried mango with rehydration rates comparable to those of microwave vacuum freeze dried mango at 25 ℃ and 100 ℃; the worst rehydration properties were obtained when mango was dried by hot air drying with rehydration rates of 2.140 and 3.028 at 25 ~C and 100 ~C, respectively. Similarly, microwave vaccum freeze drying resulted in the best color, aroma and taste in dried mango, followed by hot-plate vacuum freeze drying; hot air dried mango showed the worst color, aroma and taste.

  12. 氯化钠的吸波特性及微波干燥工艺研究%STUDY ON MICROWAVE ABSORPTION PROPERTY AND MICROWAVE DRYING PROCESS OF SODIUM CHLORIDE

    Institute of Scientific and Technical Information of China (English)

    刘晨辉; 张利波; 彭金辉; 刘秉国; 夏洪应; 黄卡玛; 顾晓春; 史谊峰

    2012-01-01

    The open-ended coaxial sensor reflection method is adopted to measure the coefficient of wet sodium chloride with moisture from 0% to 5% , the influence of microwave frequency, water content and temperature on microwave absorbing ability and microwave drying technology of wet sodium chloride are studied. The results show that: the microwave frequency which is between 2. 3 ~2. 6 GHz almost has no effect on the microwave absorption property, the increase of water content in the sample can dramatically increase in the microwave absorption property, and the microwave absorption property of the sample has a linear relationship with water content, temperature increasing leads to significant increase in microwave absorption property of wet sodium chloride. Microwave drying technolo- gy of sodium chloride is studied thus the optimized microwave drying process parameters for sodium chloride are obtained as follows: drying temperature 60 ~70 ℃ , drying time 70~90 s with sample thickness 35 -45 mm.%采用终端开路同轴探头反射法测量了含水率0%~5%的氯化钠反射系数,研究了微波频率、含水率和温度对氯化钠含水物料吸波性能的影响,并对氯化钠的微波干燥工艺进行分析.结果表明:微波频率在2.3~2.6 GHz对物料的吸波性能影响不大,含水率的增加能显著提高物料的吸波能力和微波能的耗散,氯化钠的吸波性能与含水率之间存在线性关系,温度升高也会引起物料吸波性能显著提升;通过对物料微波干燥工艺研究得到较好的微波干燥工艺条件:干燥温度60~70℃、干燥时间70 ~90s、物料厚度35 ~45 mm.

  13. Drying Characteristics and Product Quality of Cowpeas in the Convective Tunnel Drying Process%长豇豆隧道式热风干燥特性及品质变化

    Institute of Scientific and Technical Information of China (English)

    师建芳; 吴辉煌; 刘清; 吴中华

    2013-01-01

    应用自制隧道式干燥实验台对95,℃漂烫2,min 后的长豇豆进行热风干燥实验,分析了在不同热风温度、热风速度、料层厚度条件下豇豆的干燥特性及干产品品质.结果表明:长豇豆干燥过程中干燥第1阶段表现明显,热风温度对干燥速率及品质的影响最大;经漂烫后的长豇豆在热风温度60,℃、热风速度0.3,m/s、料层厚度6,mm条件下干燥时所得产品Vc含量最高.研究结果可为长豇豆隧道式热风干燥生产实践提供参考依据.%Convective air drying of fresh cowpeas was done in a lab-scale tunnel dryer,and parametric studies were con-ducted to understand the effect of drying air temperature,velocity and material layer thickness on the drying characteristics of cowpeas and the quality of the dried product. Experimental results show that the first stage drying dominates the cowpea drying process and the drying air temperature has an important effect on the drying rate and product quality. The optimized drying conditions with the highest content of Vc were obtained for the fresh cowpeas:the drying temperature was 60,℃,air velocity was 0.3,m/s and the material layer thickness was 6,mm. The study can provide some useful technical data for the tunnel drying of cowpeas.

  14. Impact of Pretreatment and Drying Methods on Quality Attributes of Onion Shreds

    Directory of Open Access Journals (Sweden)

    Nihar R. Sahoo

    2015-01-01

    Full Text Available Experiments were conducted on dry untreated onion shreds (2 mm thickness or treated with salt (5 % solution and potassium metabisulphite (0.5 % solution in convective drier at 50 °C ((46±4 % relative humidity (RH, 55 °C ((35±4 % RH, 60 °C ((28±4 % RH and 65 °C ((20±4 % RH, heat pump-assisted convective drier at 35 °C ((32±2 % RH, 40 °C ((26±2 % RH, 45 °C ((19±2 % RH and 50 °C ((15±2 % RH and microwave-assisted convective drier at four microwave power levels, i.e. 120, 240, 360 and 480 W. The quality parameters of the dried onion shreds, namely rehydration ratio, colour diff erence, pyruvic and ascorbic acid contents and sensory scores were evaluated. The quality of dehydrated onion shreds was observed to be comparatively better when treated in heat pump drier at 50 °C, followed by that in microwave-assisted convective drier at 240 W and 50 °C, and last in convective drier at 60 °C. The onion shreds pretreated with potassium metabisulphite retained better colour of the dried product irrespective of drying methods. Therefore, heat pump drying may be recommended as one of the best drying methods for onion shreds, because it maintains the fi nal product quality, which has practical importance for the food industry.

  15. Mixtures of Steel-Making Slag and Carbons as Catalyst for Microwave-Assisted Dry Reforming of CH4

    Institute of Scientific and Technical Information of China (English)

    Jose M. BERMUDEZ; Beatriz FIDALGO; Ana ARENILLAS; J. Angel MENENDEZ

    2012-01-01

    The use of steel-making slag as catalysts for microwave-assisted dry reforming of CH4 was studied.Two carbon materials (an activated carbon and a metallurgical coke),mixtures of the carbon materials and Fe-rich slag,and mixtures of the carbon materials and Ni/Al2O3 were tested as catalysts.The mixtures of slag with carbons gave rise to higher and steadier conversions than those achieved over the carbon materials alone.In addition,the use of the metallurgical coke mixed with metal-rich catalysts gave rise to remarkable results.Thus,no CH4 and CO2 conversions were achieved when coke was used alone,whereas high conversions were obtained when it was mixed with the metal-rich catalysts.

  16. Influence of microwave vacuum drying on glass transition temperature, gelatinization temperature, physical and chemical qualities of lotus seeds.

    Science.gov (United States)

    Zhao, Yingting; Jiang, Yajun; Zheng, Baodong; Zhuang, Weijing; Zheng, Yafeng; Tian, Yuting

    2017-08-01

    This study investigated the effects of microwave power density on effective moisture diffusion coefficient (Deff), glass transition temperature (Tg), gelatinization temperature (TP), physical and chemical qualities of lotus seeds during microwave vacuum drying. Deff increased by 42% and 127% at 15W/g and 20W/g, respectively, when compared with 10W/g. TP was negatively correlated with the relaxation times of T21 and T22, while Tg was negatively correlated with the relative areas A22. The rates of change of color were observed to be divided roughly into two periods, consisting of a rapid change caused by enzymatic browning and a slow change caused by non-enzymatic browning. An equation is provided to illustrate the relationship of k1 and k2 of Peleg's model depending on power density during rehydration kinetics. The samples at 20W/g exhibited the higher content of amino acid (540.19mg/100gd.b.) while lower starch (17.53g/100gd.b.).

  17. DEVELOPMENT OF MATHEMATICAL MODEL OF BLACK CURRANT BERRIES DRYING PROCESS IN VACUUM DEVICE WITH THE MICROWAVE POWER SUPPLY

    Directory of Open Access Journals (Sweden)

    S. T. Antipov

    2014-01-01

    Full Text Available Summary. The mathematical model of black currant berries drying process in vacuum device with the microwave power supply, differing in high space and temporary specification is developed, the structure of separate berries and a layer of berries is considered, heat- and physical parameters depend on coordinate and time as well as in the accounting of berries form change and a berries layer structure in the dehydration process. We used the particles dynamics method for modeling of mechanical behavior of berries which is increasingly being used now in different branches of science and technology. To give the model the high space specification the modeled berries layer consists of 20–50 separate berries, each berry depending on diameter being broken into approximately 100 separate elements. Berries elements are divided into 3 types depending on the physical properties (peel, pulp, seeds. Therefore, in general, from the point of space detail, a layer of berries consists of 2000- 5000 elements. Modeling is carried out in two-dimensional Cartesian space X–Z. The condition of each element of circle is set by four variables: Cartesian coordinates of its center and two components of speed. Mechanical interaction of elements among themselves is accepted to be viscous and elastic that allows to consider the main mechanical properties of berries – the elasticity module, internal friction index. Within the developed model it is considered that between the neighbor elements there can be pushing away forces (at the introduction of elements into each other, or attractions (at a distance of the linked elements from each other. The description of the processes of warm and moisture exchange between the elements as well as between the elements and environment is based upon the standard equations of drying. In model it is considered that the microwave power brought is redistributed in the heated volume in proportion to elements moisture.

  18. Numerical Simulation of Temperature Profiles during Convective Drying of Potato%土豆对流干燥过程中温度场的数值模拟

    Institute of Scientific and Technical Information of China (English)

    缪丽华; 范小平; 胡晓露; 向红; 周家华

    2013-01-01

    根据土豆切样在对流干燥过程中发生的物理变化,基于费克第二扩散定律和傅立叶定律,建立了对流干燥系统传质传热过程的数学模型以及几何物理模型,并利用有限元数值模拟方法对干燥过程中土豆切样内部的瞬态温度场及其影响因素进行了仿真预测.最后,设计并采用对流干燥实验对数值模拟得到的代表性结果进行了验证,结果表明实验值与模拟值在趋势上表现了较好的一致性.%According to the physical changes of potato sample occurred in the process of convective drying, on the base of Fick's second law and Fourier's equation, mathematical model and geometric physical model were set up in the process of heat and mass transfer during convective drying. Transient temperature profiles and influencing factors of internal potato were calculated by utilising the finite element numerical simulation method. At last, comparison of experimental data against numerical simulation representative results designed in convective drying has shown a very good agreement, implying that the model can be used to predict transient temperature profiles in potato.

  19. Microwave and micronization treatments affect dehulling characteristics and bioactive contents of dry beans (Phaseolus vulgaris L.).

    Science.gov (United States)

    Oomah, B Dave; Kotzeva, Lily; Allen, Meghan; Bassinello, Priscila Zaczuk

    2014-05-01

    Heat pretreatment is considered the first step in grain milling. This study therefore evaluated microwave and micronization heat treatments in improving the dehulling characteristics, phenolic composition and antioxidant and α-amylase activities of bean cultivars from three market classes. Heat treatments improved dehulling characteristics (hull yield, rate coefficient and reduced abrasive hardness index) depending on bean cultivar, whereas treatment effects increased with dehulling time. Micronization increased minor phenolic components (tartaric esters, flavonols and anthocyanins) of all beans but had variable effects on total phenolic content depending on market class. Microwave treatment increased α-amylase inhibitor concentration, activity and potency, which were strongly correlated (r²  = 0.71, P < 0.0001) with the flavonol content of beans. Heat treatment had variable effects on the phenolic composition of bean hulls obtained by abrasive dehulling without significantly altering the antioxidant activity of black and pinto bean hulls. Principal component analysis on 22 constituents analyzed in this study demonstrated the differences in dehulling characteristics and phenolic components of beans and hulls as major factors in segregating the beneficial heat treatment effects. Heat treatment may be useful in developing novel dietary fibers from beans with variable composition and bioactivity with a considerable range of applications as functional food ingredients. © 2013 Society of Chemical Industry.

  20. Assessing the utility of microwave kernel moisture sensing in peanut drying

    Science.gov (United States)

    Presently, in the peanut industry, peanut pods (unshelled peanuts) have to be shelled for kernel moisture content determination with the official moisture meter. This makes kernel moisture content determination laborious and limits efficiency during peanut drying. For field testing during the 2013 a...

  1. Optimality in Microwave-Assisted Drying of Aloe Vera (Aloe barbadensis Miller) Gel using Response Surface Methodology and Artificial Neural Network Modeling

    Science.gov (United States)

    Das, Chandan; Das, Arijit; Kumar Golder, Animes

    2016-07-01

    The present work illustrates the Microwave-Assisted Drying (MWAD) characteristic of aloe vera gel combined with process optimization and artificial neural network modeling. The influence of microwave power (160-480 W), gel quantity (4-8 g) and drying time (1-9 min) on the moisture ratio was investigated. The drying of aloe gel exhibited typical diffusion-controlled characteristics with a predominant interaction between input power and drying time. Falling rate period was observed for the entire MWAD of aloe gel. Face-centered Central Composite Design (FCCD) developed a regression model to evaluate their effects on moisture ratio. The optimal MWAD conditions were established as microwave power of 227.9 W, sample amount of 4.47 g and 5.78 min drying time corresponding to the moisture ratio of 0.15. A computer-stimulated Artificial Neural Network (ANN) model was generated for mapping between process variables and the desired response. `Levenberg-Marquardt Back Propagation' algorithm with 3-5-1 architect gave the best prediction, and it showed a clear superiority over FCCD.

  2. Optimality in Microwave-Assisted Drying of Aloe Vera ( Aloe barbadensis Miller) Gel using Response Surface Methodology and Artificial Neural Network Modeling

    Science.gov (United States)

    Das, Chandan; Das, Arijit; Kumar Golder, Animes

    2016-10-01

    The present work illustrates the Microwave-Assisted Drying (MWAD) characteristic of aloe vera gel combined with process optimization and artificial neural network modeling. The influence of microwave power (160-480 W), gel quantity (4-8 g) and drying time (1-9 min) on the moisture ratio was investigated. The drying of aloe gel exhibited typical diffusion-controlled characteristics with a predominant interaction between input power and drying time. Falling rate period was observed for the entire MWAD of aloe gel. Face-centered Central Composite Design (FCCD) developed a regression model to evaluate their effects on moisture ratio. The optimal MWAD conditions were established as microwave power of 227.9 W, sample amount of 4.47 g and 5.78 min drying time corresponding to the moisture ratio of 0.15. A computer-stimulated Artificial Neural Network (ANN) model was generated for mapping between process variables and the desired response. `Levenberg-Marquardt Back Propagation' algorithm with 3-5-1 architect gave the best prediction, and it showed a clear superiority over FCCD.

  3. Microwave drying of biomass and its effect on pyrolysis characteristics%生物质微波干燥及其对热解的影响

    Institute of Scientific and Technical Information of China (English)

    王贤华; 陈汉平; 张世红; 朱波; 杨海平

    2011-01-01

    通过与常规热风干燥方式比较,研究生物质微波干燥过程及其对热解的影响,以探索在生物质快速热解液化工艺中采用微波干燥技术进行原料预处理的可行性.干燥实验表明,微波炉的干燥速率明显大于烘箱(5倍以上),同时在微波快速干燥过程中,原料内部的孔隙结构得到了改善.热天平上干燥样品的热解表明,微波干燥处理有利于生物质的热解,特别是纤维素和半纤维素的热解,并且能在一定程度上抑制生物油蒸汽的二次裂解反应,从而使实际流化床热解液化装置中的生物油产率有所提高.研究表明,将微波干燥技术用于生物质热解液化的原料预处理过程在技术上和经济上均具有可行性.%The influence of microwave drying on the pyrolysis of biomass was investigated compared with conventional air drying. The aim of this work is to seek the feasibility of using microwave drying technique in fast pyrolysis of biomass during pretreatment of the feedstock. The drying tests show that the drying rate of microwave oven is far faster than that of electrical oven. The inner pore characteristics of dried biomass are improved at higher drying rate. The thermogravimetric and kinetic analysis indicate that the microwave drying treatment promote the decomposition of biomass, especially cellulose and hemicellulose, and prevent the secondary reactions of primary vapor to a certain extent at the same time. As a result, the yield of bio-oil from biomass pyrolysis in a fluidized-bed reactor increases slightly. Thus microwave drying is a technically and economically feasible pretreatment method for fast pyrolysis of biomass and more in-depth works are needed to be carried out next step.

  4. Anti-nutritional Factors and Ruminal Dry Matter and Crude Protein Degradability of Gamma and Microwave Irradiated Native Rapeseed

    Directory of Open Access Journals (Sweden)

    sayyed roohollah ebrahimimahmoudabad

    2016-08-01

    Full Text Available Introduction Native rapeseed (NRS is planted in some parts of Iran because of climatic condition. The consumption of NRS in animal nutrition is limited by anti-nutritional such as phytic acid and glucosinolate. Moreover, the protein of NRS is highly degraded by rumen microorganisms. Several processing methods have been used to enhance the nutritive value of whole oilseeds, including extrusion, roasting, toasting and Jet-Sploding. However, most heat processing methods adversely affect protein digestibility in the small intestine. Recently, other processing methods such as processing by gamma and microwave irradiation have been noticed. Therefore, this research was carried out to evaluate the effects of gamma irradiation (15, 30 and 45 kGy and microwave irradiation (800 W for 2, 4 and 6 min on ruminal dry matter (DM and crude protein (CP degradability, in vitro CP digestibility, anti-nutritional factors (glucosinolate and phytic acid and chemical composition of NRS. Materials and Methods Chemical composition (DM, CP, EE and Ash of untreated and irradiated NRS was determined by AOAC methods. Then, sufficient water was added to the sample to increase the moisture content to 250 g/kg. Gamma irradiation was completed by using a cobalt-60 irradiator at 20 ºC. The dose rate determined by Fricke dosimetry was 0.36 Gy/s. Another three samples (500 g each were subjected to microwave irradiation at a power of 800 W for 2, 4 and 6 min. Phytic acid and glucosinolate contents of untreated and irradiated samples were determined by standard methods. Degradation kinetics of DM or CP were determined according to in situ procedure. Six grams of untreated or irradiated NRS were incubated in the rumen of three ruminally fistulated Taleshi bulls for 0, 2, 4, 8, 16, 24 and 48 h. Bags were placed in the rumen just before the bulls were offered their first meal. After retrieval from the rumen, bags were thoroughly washed with tap water until the rinsing water was clear

  5. Drying kinetics and colour change of lemon slices

    Science.gov (United States)

    Darvishi, Hosain; Khoshtaghaza, Mohammad H.; Minaei, Saeid

    2014-03-01

    The effect of microwave-convective heating on drying characteristics and colour change of lemon slices was investigated. The drying experiments were carried out at 180, 360, 540 and 720Wand at 22°C, with air velocity of 1ms-1. The values of effective moisture diffusivity were found to be in the range between 1.87 10-8 and 3.95 10-8 m2 s-1, and the activation energy was estimated to be 10.91 Wg-1. The drying data were fitted with ten mathematical models available in the literature. The model describing drying kinetics of lemon slices in the best way was found. The colour change of the dried lemon slices was analysed and considered as a quality index affecting the drying quality of the product. The values of lightness/darkness, yellowness/blueness and hue angle increased, while the value of redness/greenness decreased with increasing microwave power.

  6. Mathematical Modeling of Drying Kinetics of Bird’s Eye Chilies in a Convective Hot-Air Dryer

    Directory of Open Access Journals (Sweden)

    Kongdej LIMPAIBOON

    2013-12-01

    Full Text Available The drying kinetics of red bird’s eye chilies and the color of the product were investigated in a laboratory scale hot-air dryer under 3 air temperatures of 55, 60 and 65 °C. The 6 mathematical models (Lewis model; Page model; Henderson and Pabis model; Logarithmic model; Modified Page model; and Wang and Singh model were used to fit the experimental data obtained in order to estimate the moisture ratio as the function of drying time. The results showed that operating temperature enhanced the kinetics of the drying of chilies; the drying times of chilies at 55, 60 and 65 °C were 510, 360 and 330 min, respectively. The experimental drying curves obtained at all operating conditions took place in the falling rate period. Comparing the dried products, it was observed that the red bird’s eye chilies dried at a lower temperature had higher Hunter L (lightness, a* (redness and b* (yellowness values. The experimental data were fitted to different drying models. The performance of these models was investigated by comparing the determination of coefficient (R2 and root mean square error (RMSE between the observed and predicted moisture ratios. Among the 6 mathematical models, the Wang and Singh model satisfactorily described the drying kinetics of chilies.

  7. Macroscopic modeling of heat and water vapor transfer with phase change in dry snow based on an upscaling method: Influence of air convection

    Science.gov (United States)

    Calonne, N.; Geindreau, C.; Flin, F.

    2015-12-01

    At the microscopic scale, i.e., pore scale, dry snow metamorphism is mainly driven by the heat and water vapor transfer and the sublimation-deposition process at the ice-air interface. Up to now, the description of these phenomena at the macroscopic scale, i.e., snow layer scale, in the snowpack models has been proposed in a phenomenological way. Here we used an upscaling method, namely, the homogenization of multiple-scale expansions, to derive theoretically the macroscopic equivalent modeling of heat and vapor transfer through a snow layer from the physics at the pore scale. The physical phenomena under consideration are steady state air flow, heat transfer by conduction and convection, water vapor transfer by diffusion and convection, and phase change (sublimation and deposition). We derived three different macroscopic models depending on the intensity of the air flow considered at the pore scale, i.e., on the order of magnitude of the pore Reynolds number and the Péclet numbers: (A) pure diffusion, (B) diffusion and moderate convection (Darcy's law), and (C) strong convection (nonlinear flow). The formulation of the models includes the exact expression of the macroscopic properties (effective thermal conductivity, effective vapor diffusion coefficient, and intrinsic permeability) and of the macroscopic source terms of heat and vapor arising from the phase change at the pore scale. Such definitions can be used to compute macroscopic snow properties from 3-D descriptions of snow microstructures. Finally, we illustrated the precision and the robustness of the proposed macroscopic models through 2-D numerical simulations.

  8. The Microwave Drying and Disinfection Treatment of Waterishlogged Books%水浸书籍的微波干燥与消毒处理

    Institute of Scientific and Technical Information of China (English)

    李婧

    2016-01-01

    For the drying and treatment of waterishlogged books, the traditional methods usually adopted in China are the vacuum freeze drying technique and hot air drying technique. This paper introduces a new kind of patent technique adopted by Czech National Archives, microwave drying and sterilization technique, which can greatly shorten the cycle of books' drying treatment, process of books, and has a better application prospect.%对于水浸书籍的干燥与处理,国内一般采用的方法是传统的真空冷冻干燥与热风干燥技术.介绍了捷克国家档案馆采用的一种新型专利技术——微波干燥消毒技术,该工艺可大大缩短书籍干燥处理周期,具有较好的推广应用前景.

  9. 连续式微波干燥活性米设备的研究%Research on the Continuous Microwave Drying Equipment of Activity Meter

    Institute of Scientific and Technical Information of China (English)

    王磊; 张艳哲; 于洁; 王彦宇; 刘成海; 郑先哲

    2016-01-01

    为了提高活性米干燥效率及干后品质,基于现有隧道式微波干燥机,设计了一种新型的微波干燥设备.该设备以微波作为干燥热源,由定量进料装置、微波干燥装置、缓苏装置及控制装置等部分组成,实现了微波干燥的连续性;通过分粮板、铺料刷等装置将物料以规则薄层铺放到输送带上,提高了干燥的均匀性;在连续干燥过程中加入缓苏装置,并通过控制系统精确控制干燥的目标含水率;分析确定了搅龙、输送装置、干燥仓、缓苏仓等关键部件的结构参数及具体尺寸. 试验结果表明:该设备工作效率约为1 t/h,爆腰率20%以下,适用于连续式活性米干燥,提高了微波干燥效率,且干燥品质良好,高度保持了活性米的色香味及热敏性营养成分.%In order to enhance the activity of rice drying efficiency and quality of dry products , based on the existing tun-nel microwave drying machine , we designed a new type of microwave drying equipment , which as a microwave drying heat source , the quantitative feeding apparatus , microwave drying equipment , tempering part of the device , the control device , to achieve a continuous microwave drying , through the sub-grain boards , decking and other means to brush a thin layer of material to the rules laid onto the conveyor belt , to improve the uniformity of drying , continuous drying process Join tempering equipment , and precise control of the drying of the target moisture content by the control system . Analysis identified auger conveyor means , dry container , slow structural parameters and specific dimensions and other key components of the Soviet positions .Experimental results show that the efficiency of the device is about 1 t /h, fis-suring rate of 20%or less,suitable for continuous drying activity meters to improve the efficiency of microwave drying ,drying and good quality , highly maintained active meter color , flavor and heat-sensitive vitamins

  10. Effective diffusivity and convective mass transfer coefficient during the drying of bananas Difusividade efetiva e coeficiente de transferência convectivo de massa durante a secagem de bananas

    Directory of Open Access Journals (Sweden)

    Cleide M. D. P. da S. e Silva

    2012-04-01

    Full Text Available In this article, a methodology is used for the simultaneous determination of the effective diffusivity and the convective mass transfer coefficient in porous solids, which can be considered as an infinite cylinder during drying. Two models are used for optimization and drying simulation: model 1 (constant volume and diffusivity, with equilibrium boundary condition, and model 2 (constant volume and diffusivity with convective boundary condition. Optimization algorithms based on the inverse method were coupled to the analytical solutions, and these solutions can be adjusted to experimental data of the drying kinetics. An application of optimization methodology was made to describe the drying kinetics of whole bananas, using experimental data available in the literature. The statistical indicators enable to affirm that the solution of diffusion equation with convective boundary condition generates results superior than those with the equilibrium boundary condition.Neste artigo, é usada uma metodologia para a determinação simultânea da difusividade efetiva e do coeficiente de transferência convectivo de massa em sólidos porosos que possam ser considerados como um cilindro infinito, durante sua secagem. Dois modelos são utilizados para a otimização e a simulação do processo de secagem: o modelo 1 (volume e difusividade constantes, com condição de contorno de equilíbrio; e o modelo 2 (volume e difusividade constantes, com condição de contorno convectiva. Algoritmos de otimização por varredura, baseados no método inverso, foram acoplados às soluções analíticas referentes aos dois modelos utilizados, possibilitando ajustar tais soluções aos dados experimentais da cinética de secagem em camada fina de produtos com a forma cilíndrica. Foi feita uma aplicação da metodologia de otimização na descrição da cinética de secagem de bananas inteiras, usando dados experimentais disponíveis na literatura. Os indicadores estat

  11. Study on drying characteristics and quality of germinated brown rice ;under microwave drying conditions%活性米微波干燥特性及品质研究

    Institute of Scientific and Technical Information of China (English)

    郑先哲; 于洁; 张艳哲; 王磊; 王彦宇; 刘成海

    2015-01-01

    In order to improve the drying efficient and quality of germinated brown rice in a continuous microwave dryer, drying power, drying time, wind speed and tempering ratio were selected as influencing factors, and moisture content, fissure rate,γ-aminobutyric acid content and chrominance of dehydrated germinated brown rice were considered as objective factors. Both single factor test and Box-Benhken central composite method were employed to investigate the effects of microwave drying parameters on the drying characteristics and quality of germinated brown rice and optimize microwave drying process parameters. The results showed that moisture remove of germinated brown rice occur at the constant rate stage under microwave drying, and microwave drying parameters present significant effects on the quality of the germinated brown rice. Process optimization parameters were obtained as drying power of 3.00 W·g-1, drying time of 4.00 min, wind speed of 2.00 m·s-1, tempering ratio of 1��4. Under the optimal microwave drying conditions, dried germinated brown rice was processed with moisture content of 14.35% germinated brown rice, fissure rate of 43.0%, γ-aminobutyric acid content of 16.10 mg·100 g-1, chrominance of L*value 57.98, chrominance of a*value-1 288.77 chrominance of b* value 22.09. The research results present the technical basis for the industrial yield of germinated brown rice with high efficient and quality.%为提高活性米干燥效率和品质,应用连续式微波干燥装置,以干燥功率、干燥时间、风速及缓苏比为试验因素,以含水率、爆腰率、γ-氨基丁酸含量和色度为评价指标,采用单因素试验与Box-Benhken中心组合试验相结合方法,研究微波干燥条件对活性米微波干燥特性及品质影响规律,优化活性米微波干燥工艺参数。结果表明,活性米微波干燥去水主要发生在恒速干燥阶段,干燥条件对活性米品质有显著影响;工艺优化

  12. Drying characteristics of preserved prunes (Ganshimei) under solar drying (natural convection)%太阳能干燥对干湿梅品质的影响

    Institute of Scientific and Technical Information of China (English)

    申晓曦; 李汴生; 刘伟涛

    2011-01-01

    以干湿梅为样品,利用小型太阳能连续干燥设备,研究了干湿梅的干燥特性,分析了产品的理化性质和感官品质.结果表明,干燥过程中干燥介质的温湿度与外界环境相比有明显差异,干燥室白天日照时温度会高于环境温度,干燥时间明显缩短,高效且避免了缓苏产品色泽口感品质的不利影响;干燥过程是内部水分扩散控制的降速干燥过程,达到目标湿基湿含量(58%~60%)和盐含量(28%~32%)时,自然日晒干燥约需50h,而太阳能自然对流干燥只需14h;水分扩散速率和理化指标随样品在干燥室中所处位置不同而异,环境温度的上升使其在干燥7~10b中有较高的干燥速率;干燥过程中样品的色泽会逐渐变深、体积略有收缩、果肉硬度增加,实验表明在干燥室第二层的样品感官分值为4.40±0.03,整体感官品质优于自然日晒干燥产品.%The candied prunes were dried by a small-scale solar dryer. The drying characteristics, sensory quality,physical and chemical qualities of preserved prunes(Ganshimei)were investigated. The result showed that the air temperature and humidity were significantly different between the ambience and the drying room ,which made the drying time much more shorter and avoided the adverse effects from tempering. The solar drying processes of preserved prunes were controlled by internal moisture diffusion with a falling drying rate. To reach the target water content and salt content,it took about 50h while the solar drying just needed 14h. The water diffusion rate and the physical and chemical quality had a little difference because the samples were dried in different places, and the conclusion was obtained that it had higher drying rate during 7~10h. The sample darkened,shrunk and hardened a little during solar drying. The sensory score of the 2nd layer drying was 4.40 ±0.03 ,so it can conclude that the whole sensory quality was very good.

  13. Povacoat affecting solid-state polymorphic changes of indomethacin after co-evaporation from different types of solvents via conventional and microwave drying techniques

    Directory of Open Access Journals (Sweden)

    Shan-Yang Lin

    2016-06-01

    Full Text Available The effect of Povacoat on the solid state characteristics and polymorphic transformation of γ-form of indomethacin (γ-IMC after solvent co-evaporation via two drying methods was investigated by thermoanalytical and FTIR spectroscopic studies. The types of solvents (water, ethanol, and water:ethanol (1:9 ~ 2:8, v/v, weight ratios of Povacoat:IMC (4:1 ~ 4:10, w/w, and drying methods (air-drying and microwave-drying were selected as variables in this study. A physical mixture of Povacoat and γ-IMC was also carried out by neat grinding process. The results indicate that there was no interaction between Povacoat and γ-IMC or no polymorphic change of γ-IMC after the neat co-grinding process. Since Povacoat was only soluble in water or <30% ethanol aqueous solution but γ-IMC was only soluble in organic solvents, different solvents and drying methods might significantly influence the solid-state characteristics of IMC formed in the presence of Povacoat. It was found that the amorphous IMC was formed in the Povacoat/IMC evaporates after dissolving both Povacoat and γ-IMC in water:ethanol (mixed ratio=1:9 and 2:8, v/v and co-evaporation via microwave-drying, whereas the α-IMC was formed in the Povacoat/IMC evaporates via the air-drying method. In addition, the predominate α-IMC formation was only found in all the Povacoat/IMC evaporates with different weight ratios prepared by previously dissolving in water:ethanol (1:9, v/v and co-evaporation via air-drying, but the amorphous IMC formation after co-evaporation via microwave-drying was obtained except the 4:10 (w/w weight ratio. The thermal effect of microwave irradiation and the presence of Povacoat might be responsible for the amorphous IMC formation in the Povacoat/IMC evaporates.

  14. Interrelated variations of O3, CO and deep convection in the tropical/subtropical upper troposphere observed by the Aura Microwave Limb Sounder (MLS during 2004–2011

    Directory of Open Access Journals (Sweden)

    L. Froidevaux

    2012-07-01

    Full Text Available The interrelated geographical and temporal variability seen in more than seven years of tropical and subtropical upper tropospheric (215 hPa ozone, carbon monoxide and cloud ice water content (IWC observations by the Aura Microwave Limb Sounder (MLS are presented. Observed ozone abundances and their variability (geographical and temporal agree to within 10–15 ppbv with records from sonde observations. MLS complements these (and other observations with global coverage and simultaneous measurements of related parameters. Previously-reported phenomena such as the ozone "wave one" feature are clearly seen in the MLS observations, as is a double peak in ozone abundance over tropical East Africa, with enhanced abundances in both May to June and September to November. While repeatable seasonal cycles are seen in many regions, they are often accompanied by significant interannual variability. Ozone seasonal cycles in the southern tropics and subtropics tend to be more distinct (i.e., annually repeatable than in the northern. By contrast, carbon monoxide shows distinct seasonal cycles in many northern subtropical regions, notably from India to the Eastern Pacific. Deep convection (as indicated by large values of IWC is typically associated with reductions in upper tropospheric ozone. Convection over polluted regions is seen to significantly enhance upper tropospheric carbon monoxide. While some regions show statistically significant correlations among ozone, carbon monoxide and IWC, simple correlations fall well short of accounting for the observed variability. The observed interrelated variations and metrics of annual and interannual variability described here represent a new resource for validation of atmospheric chemistry models.

  15. Interrelated variations of O3, CO and deep convection in the tropical/subtropical upper troposphere observed by the Aura Microwave Limb Sounder (MLS during 2004–2011

    Directory of Open Access Journals (Sweden)

    L. Froidevaux

    2013-01-01

    Full Text Available The interrelated geographic and temporal variability seen in more than seven years of tropical and subtropical upper tropospheric (215 hPa ozone, carbon monoxide and cloud ice water content (IWC observations by the Aura Microwave Limb Sounder (MLS are presented. Observed ozone abundances and their variability (geographic and temporal agree to within 10–15 ppbv with records from sonde observations. MLS complements these (and other observations with global coverage and simultaneous measurements of related parameters. Previously-reported phenomena such as the ozone "wave one" feature are clearly seen in the MLS observations, as is a double peak in ozone abundance over tropical East Africa, with enhanced abundances in both May to June and September to November. While repeatable seasonal cycles are seen in many regions, they are often accompanied by significant interannual variability. Ozone seasonal cycles in the southern tropics and subtropics tend to be more distinct (i.e., annually repeatable than in the northern. By contrast, carbon monoxide shows distinct seasonal cycles in many northern subtropical regions, notably from India to the Eastern Pacific. Deep convection (as indicated by large values of IWC is typically associated with reductions in upper tropospheric ozone. Convection over polluted regions is seen to significantly enhance upper tropospheric carbon monoxide. While some regions show statistically significant correlations among ozone, carbon monoxide and IWC, simple correlations fall well short of accounting for the observed variability. The observed interrelated variations and metrics of annual and interannual variability described here represent a new resource for validation of atmospheric chemistry models.

  16. 南瓜脆片微波干燥工艺研究%Study on the Microwave Drying Technique of Pumpkin Crisp Chip

    Institute of Scientific and Technical Information of China (English)

    熊涛; 龙娇

    2011-01-01

    [目的]研究南瓜脆片微波干燥的方法.[方法]对微波功率、切片厚度、处理时间和预处理后南瓜片初始含水率等因素对膨化干燥南瓜脆片的影响进行研究和比较.[结果]在微波功率为中高火,南瓜片的切片厚度为3mm,预处理后南瓜片初始含水率为18%左右的条件下,可得到高品质的南瓜脆片,干燥390 s时膨化率高达220%.[结论]微波干燥很适合南瓜脆片的制作.%[Objective] To study the microwave drying method of pumpkin crisp chip. [ Method ] The effects of microwave power, slice thick ness, treatment time and water content in pumpkin chip after pretreatment on the puffed drying of pumpkin crisp chip were studied and compared. [ Result] High-quality pumpkin crisp chip could be produced by setting the microwave power at medium-high heat, the slice thickness at 3mm and the water content in pumpkin chip after pretreatment at 18% , the puffing rate could reach as high as 220% after 390 s drying. [Conclusion] Microwave drying was a good technique to produce pumpkin crisp chip.

  17. The microwave vacuum drying of instant Ersi%方便饵丝的微波真空干燥研究

    Institute of Scientific and Technical Information of China (English)

    施继红; 黄铭; 朱书灯

    2012-01-01

    干燥是方便食品加工过程中最重要的环节。通过传统热风干燥和微波真空干燥方法对云南风味食品饵丝进行了干燥对比试验,结果表明:微波真空干燥方法可以不使用添加剂生产出外观、口感、韧性和复水性能优良的方便饵丝,并且能有效降低能耗,缩短干燥时间。%Drying is the most important process in food manufacture. In this paper, the traditional hot air drying and microwave vacuum drying methods on the Ersi, which is typical Yunnan food, are compared. The experiment results show that the microwave vacuum drying method can produce excellent Ersi with nice appearance, texture, toughness and rehydration but not use additives, as well as can effectively reduce energy consumption and reduce the drying time.

  18. A Study of the Shrinkage Changes and Mathematical Modeling of Garlic (Allium sativumL. During Convective Drying

    Directory of Open Access Journals (Sweden)

    M Rasouli

    2012-05-01

    Full Text Available Garlic (Allium sativumL. is one of the most important Allium spice. From an economic point of view, the dried garlic slices are valuable products. In this research, garlic slices as a thin layer were dried in a laboratory scale hot-air dryer, under air flow of 1.5 m/s, air temperatures of 50, 60 and 70˚C and slice thicknesses of 2, 3 and 4 mm. The mean values of shrinkage of garlic slices obtained 69.8%. In addition, the effects of the drying variables on the shrinkage of dried garlic were evaluated. The ANOVA results indicated that the air temperature and slice thickness had no significant effect on final shrinkage of dried garlic slices. In order to derive and select the appropriate shrinkage model, four mathematical models were fitted to the experimental data. According to the statistical criteria (R2, SSE & RMSE the best model was found to describe the shrinkage behavior of garlic slice.

  19. Large-scale vertical velocity, diabatic heating and drying profiles associated with seasonal and diurnal variations of convective systems observed in the GoAmazon2014/5 experiment

    Science.gov (United States)

    Tang, Shuaiqi; Xie, Shaocheng; Zhang, Yunyan; Zhang, Minghua; Schumacher, Courtney; Upton, Hannah; Jensen, Michael P.; Johnson, Karen L.; Wang, Meng; Ahlgrimm, Maike; Feng, Zhe; Minnis, Patrick; Thieman, Mandana

    2016-11-01

    This study describes the characteristics of large-scale vertical velocity, apparent heating source (Q1) and apparent moisture sink (Q2) profiles associated with seasonal and diurnal variations of convective systems observed during the two intensive operational periods (IOPs) that were conducted from 15 February to 26 March 2014 (wet season) and from 1 September to 10 October 2014 (dry season) near Manaus, Brazil, during the Green Ocean Amazon (GoAmazon2014/5) experiment. The derived large-scale fields have large diurnal variations according to convective activity in the GoAmazon region and the morning profiles show distinct differences between the dry and wet seasons. In the wet season, propagating convective systems originating far from the GoAmazon region are often seen in the early morning, while in the dry season they are rarely observed. Afternoon convective systems due to solar heating are frequently seen in both seasons. Accordingly, in the morning, there is strong upward motion and associated heating and drying throughout the entire troposphere in the wet season, which is limited to lower levels in the dry season. In the afternoon, both seasons exhibit weak heating and strong moistening in the boundary layer related to the vertical convergence of eddy fluxes. A set of case studies of three typical types of convective systems occurring in Amazonia - i.e., locally occurring systems, coastal-occurring systems and basin-occurring systems - is also conducted to investigate the variability of the large-scale environment with different types of convective systems.

  20. THE CONTROL ALGORITHM OF THE DRYING PROCESS PARTICULATE MATERIALS IN THE APPARATUS WITH THE SWIRLING FLOW OF COOLANT AND MICROWAVE ENERGY SUPPLY

    Directory of Open Access Journals (Sweden)

    S. T. Antipov

    2015-01-01

    Full Text Available The technical task of the process is to improve the drying quality of the final product, increasing the precision and reliability of control, the reduction of specific energy consumption. One of the ways to improve the process is complex and i ts local automation. This paper deals with the problems of development and creation of a new control algorithm drying process of the particulate material. Identified a number of shortcomings of the existing methods of automatic control of the process. As a result, the authors proposed a method for drying particulate materials in the device with swirling flow and the microwave energy supply and its automatic control algorithm. The description of the operating principle of the drying apparatus consists in that the particulate material is wet by using a tangential flow of coolant supplied to the cylinder-drying apparatus which also serves the axial coolant flow, whereby the heat transfer fluid with the particulate material begins to undergo a complex circular movement along the circumference apparatus, thereby increasing its speed and its operation control algorithm. The work of this scheme is carried out at three levels of regulation on the basis of determining the coefficient of efficiency of the dryer, which makes it possible to determine the optimal value of the power equipment and to forecast the cost of electricity. All of the above allows you to get ready for a high quality product while minimizing thermal energy and material costs by optimizing the operating parameters of the drying of the particulate material in the dryer with a combined microwave energy supply and ensure the rational use of heat energy by varying their quantity depending on the characteristics to be dried particulate material and the course of the process.

  1. Effect of different drying methods on moisture ratio and rehydration of pumpkin slices.

    Science.gov (United States)

    Seremet Ceclu, Liliana; Botez, Elisabeta; Nistor, Oana-Viorela; Andronoiu, Doina Georgeta; Mocanu, Gabriel-Danut

    2016-03-15

    This study was carried to determine the influence of hot air drying process and combined methods on physicochemical properties of pumpkin (Cucurbita moschata) samples. The experiments in hot air chamber were lead at 50, 60 and 70 °C. The combined method consists of a triple combination of the main drying techniques. Thus, in first stage the samples were dried in hot air convection at 60 °C followed by hot air ventilation at 40 °C simultaneous with microwave. The time required to reduce the moisture content to any given level was highly dependent on the drying conditions. So, the highest value of drying time in hot air has been 540 min at 50 °C, while the lowest time has been 189 min in hot air combined by microwave at 40 °C and a power of 315 W. The samples dried by hot air shows a higher rehydration capacity than samples dried by combined method.

  2. Combined drying technology of tilapia fillets using heat pump and microwave%罗非鱼片热泵-微波联合干燥工艺

    Institute of Scientific and Technical Information of China (English)

    关志强; 郑立静; 李敏; 郭胜兰

    2012-01-01

    采用响应面分析法优化罗非鱼片热泵-微波联合干燥工艺参数.分别以干燥能耗和产品复水率为试验指标,以熟泵干燥温度、转换点含水率、微波功率3因素为自变量,设计3因素3水平组合响应面分析试验,得出干燥能耗和产品复水率随热泵干燥温度、联合干燥转换点含水率和微波干燥功率变化的回归模型.三组验证试验的试验值与相应模型预测值的误差绝对值均小于5%.基于能耗最小的优化参数为:热泵干燥温度为34.34℃,转换点含水率为42.12%,微波功率为131.69 W;基于复水率最大的优化参数为:热泵干燥温度为33.87℃,转换点含水率为30%,微波功率为201.43 W.以热泵-微波联合干燥工艺参数组合(干燥温度为35℃,转换点含水率为39%,微波干燥功率取微波炉功率档252 W)进行试验,并与相同工况(温度和风速)热泵干燥试验值进行比较,结果表明,热泵-微波联合干燥时间比热泵干燥时间缩短了2/3;热泵-微波联合干燥罗非鱼片复水40 min,复水率达到57.40%,比热泵干燥的复水率(39.16%)增加46.5%.该文为热泵-微波联合干燥罗非鱼提供参考.%The technology of heat pump combined with microwave for drying Tilapia fillets was optimized by response surface method. Taking drying energy consumption and rehydration rate as dependent variable, the models were obtained by using response surface analysis of the three factors of temperature of heat pump drying, water content rate and power of microwave drying at three levels. The results of test and verification showed that all of the error between the value of models and the value of experiments was less than 5%. Base on the minimum of energy consumption, the optimized technology parameters were that the temperature of heat pump drying was 34.34°C, the water content rate at transformation point was 42.12% and the power of microwave drying was 131.69 W, respectively. Base on the

  3. Dry Etching of GaAs to Fabricate Via-Hole Grounds in Monolithic Microwave Integrated Circuits

    Directory of Open Access Journals (Sweden)

    D.S. Rawal

    2009-07-01

    Full Text Available This study investigates the dry etching of 60 mm dia, 200 mm deep holes for fabrication of through substrate via holes for grounding monolithic microwave integrated circuits (MMICs, on 3-inch dia semiinsulating GaAs wafer using RIE and ICP processes with CFC and non-CFC gas chemistry, respectively. The effect of various process parameters on GaAs etch rate and resultant etch profile was investigated. Two kinds of masks, photoresist and Ni, were used to etch GaAs and performance was compared by investigating effect on etch rate, etch depth, etch profile, and surface morphology. The etch profile, etch depth, and surface morphology of as-etched samples were characterised by scanning electron microscopy. The desired 200 mm deep strawberry profile was obtained at 40 mTorr for both RIE and ICP processes with an etch rate of ~1.3 mm/min and ~4 mm/min respectively. Ni metal mask was used for RIE process due to poor photoresist selectivity, whereas ICP process utilised photoresist as mask. The vias were then metallised by depositing a thin seed layer of Ti/Au (1000 Å using radio frequency sputtering and Au (~5 mm electroplated to connect the frontside pad and back side ground plane. The typical parasitic inductance offered by these via for RIE and ICP processes was ~76 pH and 83 pH respectively, which is well within the acceptable limits. The developed process was finally integrated to in-house MMIC production line.Defence Science Journal, 2009, 59(4, pp.363-370, DOI:http://dx.doi.org/10.14429/dsj.59.1535

  4. Comparison of different drying methods on Chinese ginger (Zingiber officinale Roscoe): Changes in volatiles, chemical profile, antioxidant properties, and microstructure.

    Science.gov (United States)

    An, Kejing; Zhao, Dandan; Wang, Zhengfu; Wu, Jijun; Xu, Yujuan; Xiao, Gengsheng

    2016-04-15

    Nowadays, food industry is facing challenges in preserving better quality of fruit and vegetable products after processing. Recently, many attentions have been drawn to ginger rhizome processing due to its numerous health promoting properties. In our study, ginger rhizome slices were subjected to air-drying (AD), freeze drying (FD), infrared drying (IR), microwave drying (MD) and intermittent microwave & convective drying (IM&CD). Quality attributes of the dried samples were compared in terms of volatile compounds, 6, 8, 10-gingerols, 6-shogaol, antioxidant activities and microstructure. Results showed that AD and IR were good drying methods to preserve volatiles. FD, IR and IM&CD led to higher retention of gingerols, TPC, TFC and better antioxidant activities. However, FD and IR had relative high energy consumption and drying time. Therefore, considering about the quality retention and energy consumption, IM&CD would be very promising for thermo sensitive material.

  5. Microwave vacuum drying process of sea cucumber%仿刺参微波真空干燥工艺的研究

    Institute of Scientific and Technical Information of China (English)

    张国琛; 母刚; 王隽冬; 张倩

    2012-01-01

    The effect of microwave power density( 1.0,1.5,2.0,2.5, and 3.0 W/g) , degree of vacuum(0.087, 0.090,0.093 Mpa) and initial salinity of cooking water (80,160,240 g/L) on drying rate, physical properties and sensory characteristics of products was studied in sea cucumber Apostichopus japonicus by a method of microwave -vacuum drying. The results showed that microwave power density had significant effect on drying rate and quality of dry product,the drying time being reduced by 22.5 minutes if there was an increasement of 0.5 W/g in microwave power density. The degree of vacuum and initial salinity of cooking water also showed an effect on drying rate, and the initial salinity had a significant impact on product's appearance. The optimal drying of sea cucumber was observed at microwave power density of 2 W/g, degree of vacuum of 0. 090 Mpa, and initial salinity of 80 g/L of cooking water. Under the above-mentioned optimal conditions, the colour and shape of dried sea cucumber was found to be quite well, with low shrinkage rate (32.20% ), high rehydration rate (266.32% ) , and only 110 minute drying time.%采用微波真空方法干燥仿刺参,研究了不同微波功率密度(1.0、1.5、2.0、2.5、3.0 W/g)、真空度(0.087、0.090、0.093 MPa)和预煮水盐度(80、160、240 g/L)对仿刺参Apostichopus japonicus的干燥速度、产品的物理性质及感官特性的影响.结果表明:微波功率密度对仿刺参的干燥速度和干品品质影响明显,在该微波功率密度下,功率密度平均每增加0.5 W/g,干燥时间缩短22.5 min;真空度和预煮水盐度对仿刺参的干燥速度有一定影响,预煮水盐度对仿刺参干品的外观影响较大.试验表明,用微波真空干燥海参的最佳工艺参数为:微波功率密度2 W/g、真空度0.090 MPa、预煮水盐度80 g/L.在此工艺下干燥的海参色泽和形状保持完好,收缩率较低(32.20%),复水率较高(266.32%),且干燥时间仅为110 min.

  6. 食品微波冻干技术及装备研究进展%Research progress on technology and equipment for freeze - drying food by microwave

    Institute of Scientific and Technical Information of China (English)

    王玉川; 张慜

    2016-01-01

    Freeze - drying technology used in food drying can maximize the retention of nutrients in food. The foods dried by freeze - drying are mainly exported at present since long drying period,large energy consumption and high cost. Microwave has the characteristics of inner heat source. Microwave freeze -drying technology is developed by the combination of microwave heating technology and traditional freeze- drying technology,which has been widely concerned by foreign scholars and business community since the middle of the last century. But the key technical problem has been restricting its commercial applica-tion because of the phenomenon of very obvious uneven and low - pressure gas discharge. In recent years,microwave freeze drying technology and the theory has been continuously improved due to the rapid development of science and technology and the interdisciplinary intersection and mutual penetration, which provide technical and economic support for research of the key technologies,equipment develop-ment and commercial application. The research progress of microwave drying technology at home and a-broad in high efficiency,energy saving,uniform and equipment is summarized.%冻干技术能够最大限度地保留食品的营养成分,在我国食品干燥行业得到了一定的应用。由于冻干技术存在干燥周期长、能耗大、成本高等缺点,目前我国冻干食品以出口为主。微波具有内热源特性,采用微波高效加热技术与传统冻干技术相结合而发展的微波冻干技术从上世纪中期已受到国外学者与企业界广泛关注。但是,微波冻干存在非常明显的不均匀与低压气体放电现象,这一关键技术问题一直以来制约其商业化应用。近些年来,由于科学技术的迅猛发展和学科领域的交叉、相互渗透,为微波冻干关键技术的研究、装备开发及商业化应用提供了技术及经济支撑,微波冻干技术、理论得到不断完善。综

  7. 微波真空冷冻干燥蜂蛹工艺的研究%Study on microwave vacuum freeze-drying process of Honeybee Pupae

    Institute of Scientific and Technical Information of China (English)

    平丽娟; 方晟; 毛建卫; 蔡成岗; 陈文斌

    2013-01-01

    Drying process of Honeybee Pupae by microwave vacuum freeze-drying and Optical fiber/infrared temperature measurement and control system were studied.The microwave intensities were set at 0.20,0.24,0.28, 0.32W/g and the results showed that the optimal dried product were got at 0.28W/g microwave intensity and the highest set temperature of 30℃,after drying 420min,the water content of the dried Honeybee Pupae was 2.84% , the final product was uniform with the original color and good taste flavor,and the electron micrograph showed that the product had sponge porous shape section,The dried Honeybee Pupae rehydrated 1.9 times of water in 20℃ water for Is,rehydrated effect was good,the SOD activity of the dried product slightly increased firstly and then decreased with level of 36.9U/mg protein after dried 420min,and the water content of the product was of 2.84%, Microwave vacuum freeze-drying decreased the drying time for 65% and tow viable microorganisms compared with the traditional vacuum freeze-drying method,while the SOD activity was almost at the same level,%采用微波真空冷冻干燥及光纤/红外温度测试控制等技术集成进行蜂蛹冻干中试工艺研究,用0.20、0.24、0.28、0.32W/g四个微波强度进行工艺优化,获得优化工艺参数为微波强度0.28W/g、最高解析温度30℃,微波冻干时间420min,最终产品水分含量为2.84%,产品品质好,无干瘪变形,保持蜂蛹原有色泽,电镜观察显示切面呈海绵多孔状,口味鲜美,于20℃水中复水1s,复水率达1.9倍,复水效果好,解析干燥过程中蜂蛹超氧化物歧化酶(SOD)活力呈现先略有增加后有所降低的趋势,蜂蛹冻于至水分含量为2.84%时,SOD活性为36.9U/mg prot,与真空冷冻干燥对比,所需干燥时间减少65%以上,并使存活微生物菌落数显著降低,SOD酶活力相近.

  8. Secagem de café cereja descascado por ar quente e microondas Drying pulped coffee cherry beans by means of hot air ond microwaves

    Directory of Open Access Journals (Sweden)

    M.L. Cunha

    2003-12-01

    Full Text Available Este trabalho objetivou estudar a viabilidade de produzir café cereja descascado seco pela aplicação de microondas para assistir a secagem convencional a ar quente, a fim de reduzir o tempo de processo, com o aumento do rendimento industrial e da qualidade do produto perante os métodos tradicionais de secagem. Dois ciclos de secagem foram testados: a processo em secador rotativo convencional a ar quente, com umidade do produto reduzida de 45-50 a 11-13% b.u.; b processo subdividido em uma primeira etapa de pré-secagem convencional a ar quente de 45-50 a 30% b.u., seguida de etapa de secagem final por ar quente e microondas, com redução de 30 a 11-13% b.u. de umidade do produto. O tempo global do primeiro para o segundo ciclo de secagem foi reduzido de 15 a 37,5 para pouco mais de 10 horas, respectivamente. A qualidade sensorial do produto foi avaliada pela "prova da xícara", complementada por análises de microscopia eletrônica de varredura (MEV, com resultados satisfatórios. Um estudo preliminar dos aspectos econômicos envolvidos na ampliação de escala para uma linha industrial de processamento de café com a inclusão de um sistema a microondas foi também delineado.This research concerns a process development study focussing the application of microwaves to pulped coffee cherries production, in order to reduce the drying time and increase the industrial yield and product quality when compared to conventional drying processes. Two drying cycles were tested: a a hot air drying process using a conventional batch rotary dryer from 45-50 to 11-13% w.b. product moisture; b a two stage process, whereby the product was pre dried with hot air from 45-50 to 30% w.b., followed by a final microwave and hot air drying stage, to reduce product moisture from 30 to 11-13% w.b. The overall drying time was reduced from 15 to 37.5 hours to about 10 hours, respectively. The sensory quality of the product was evaluated by the "cup test", complemented

  9. 红糖生姜果脯微波干燥工艺研究%Microwave Drying Technology Research on Brown Sugar Ginger Preserved Fruits

    Institute of Scientific and Technical Information of China (English)

    傅锋; 刘绍军; 许高升; 王晶晶

    2013-01-01

    对红糖生姜果脯的微波干燥工艺参数进行了初步研究,为生姜制品的开发、产品营养保健价值的充分保持和生姜产品的丰富以及微波技术工业化的应用提供参考。试验通过单因素及正交试验探讨了不同干燥处理条件对红糖生姜果脯的脱水率、感官品质等的影响,得到了红糖生姜果脯微波干燥的最优工艺参数即干燥方式间歇式干燥、微波功率320 W、装载量90 g、干燥时间6 min,此时所得产品试样感官质量较好,呈半透明状、膨化轻微、不焦化,色泽均匀、有光泽,组织饱满、有韧性,口感纯正、姜的辣味和红糖的香味适中。%Brown sugar, ginger preserved fruits is new products. The microwave drying process parameters of brown sugar, ginger preserved fruits have been studied. For the ginger products development, products nutrition health care value fully maintained and ginger products rich and even microwave technology industrialization to provide the reference. The influences of different microwave drying condition to dehydrated ratio of brown sugar, ginger preserved fruits,sensory quality were discussed through single factor and orthogonal experiments and the optimal processing condition was obtained.That is to say drying method of intermittent drying, microwave power 320 W load of 90 g, the drying time of 6 min, better sensory quality of products was obtained. Sample Was translucent, slightly puffed, not coking, uniform color, glossy, full organization, toughness, pure taste and ginger spice and brown sugar flavor moderate.

  10. The effect of preparation under vacuum and microwave drying on the mechanical properties of porcelain ceramic foam via polymeric sponge method

    Science.gov (United States)

    Shahatha, S. H.; Mohammed, M. A.

    2016-04-01

    In this paper was demonstrated the effect of preparation condition under vacuum and microwave drying on the mechanical properties of porcelain ceramic foam. The study was based on five different polymeric foam templates with thickness ranging from 0.5 to 4 cm. The templates were impregnated in ceramic slurry with solid loading ranging from 35 to 55 wt. % under vacuum pressure 10-1 Torr and then sintered to 1250°C. Effects of polymeric foam template thickness and solid loading quantity were evaluated based on porosity, density and mechanical properties (compressive and flexural strengths) of the ceramic foam.

  11. Chemical composition, antioxidant capacity, and sensory quality of dried jujube fruits as affected by cultivar and drying method.

    Science.gov (United States)

    Wojdyło, Aneta; Figiel, Adam; Legua, Pilar; Lech, Krzysztof; Carbonell-Barrachina, Ángel A; Hernández, Francisca

    2016-09-15

    The aim of this study was to determine the effect of different dying methods, such as convective drying (CD: 50, 60, 70 °C), vacuum-microwave drying (VMD: 120, 480, 480-120 W), a combination of convective pre-drying and vacuum-microwave finish drying [(CPD (60 °C)-VMFD (480-120 W)], and freeze-drying (FD) on key quality parameters of dried jujube fruits (cv. "GAL", "MSI", and "PSI"). The parameters studied included bioactive compounds (flavan-3-ols and flavonols, identified by LC-PDA-MS, and vitamin C), antioxidant capacity (ABTS and FRAP), and sensory attributes (e.g. hardness, jujube-ID, and sweetness). The best quality of the dried product (high contents of bioactive compounds and high intensity of key sensory attributes) was found in fruits treated by FD and VMD 480-120 W. The best cultivars were "PSI" and "GAL" from the point of view of bioactive content and sensory quality, respectively.

  12. The Annular Microwave Dryer Design and Study on Honeysuckle

    Directory of Open Access Journals (Sweden)

    Geng Yuefeng

    2014-03-01

    Full Text Available In order to dry fresh honeysuckle, microwave drying process were studied on fresh honeysuckle; and microwave drying apparatus on fresh honeysuckle is designed according to the drying process. The designed microwave dryer contains microwave generator, microwave dryer, dehumidifying systems, control system, transmission systems, microwave leakage inhibited mechanism and other components. The drying experiment is carried by the designed dryer, from the setting-to-work test, the design was success.

  13. 响应面分析法优化热风微波耦合干燥油茶籽工艺%Optimizing of coupled hot-air and microwave drying of tea camellia seeds by response surface analysis

    Institute of Scientific and Technical Information of China (English)

    陈桂芬; 宋春芳; 崔政伟

    2012-01-01

    为了优化油茶籽干燥,分别研究了油茶籽的热风和热风微波耦合干燥工艺。热风微波耦合干燥利用Box-Benhnken中心组合实验设计和响应面分析法,以过氧化值(POV)和干燥时间为响应值,优化了不同热风温度、热风速度和微波功率密度时油茶籽的热风微波耦合干燥工艺。经响应面分析得油茶籽的干燥工艺为:在热风温度为58.9℃、热风速度为1.262m/s、微波功率密度为1.972W/g、干燥时间为306min时,油脂的过氧化值为1.0472nmol/kg。热风微波耦合干燥时间比热风干燥节约近3倍,过氧化值减小了7.46%。%Drying of tea camellia seeds were conducted by hot-air,coupled hot-air and microwave drying in order to optimize its drying technology.Coupled hot-air microwave drying was done at different temperatures,air velocities and microwave power densities.The Box-Benhnken design and the response surface analysis were adopted,and both peroxide values of unsaturated fatty acids and drying time were taken as evaluation indexs to optimize the drying parameters.The analysis of response values of peroxide value and drying time showed that the optimum coupled hot-air and microwave drying parameters were:hot-air temperature of 58.9℃,microwave density 1.972W/g,drying time 306min and peroxide value 1.0472nmol/kg when drying was conducted in above parameters.Comparing to hot-air drying,coupled hot-air microwave drying save drying time nearly three times while the peroxide value reduced 7.46%.

  14. Simulación físico-matemática del secado de la zeolita con microondas. // Physical-mathematical simulation of the zeolite drying with microwaves.

    Directory of Open Access Journals (Sweden)

    G. Quesada Ramos

    2004-01-01

    Full Text Available Se realiza una simulación físico-matemática del secado de la zeolita sometida a radiaciones de microondas utilizando la leyde Lambert. Las ecuaciones se expresan en un esquema implícito unidimensional, y se emplea el método numérico dediferencias finitas. La solución del sistema de ecuaciones se realiza por medio del método iterativo de Gauss-Seidel. Losresultados teóricos se comparan con los obtenidos experimentalmente.Palabras claves: Simulación, secado, zeolita, microondas._______________________________________________________________________________AbstractA physical-mathematical simulation of the zeolite drying with microwaves using the Lambert`s law is made. The equationsare expressed in an unidimensional implicit scheme, and the finite differences numeric method is used. The solution of theequations system is carried out by using the Gauss-Seidel´s iterativ method. The theoretical results are compared with thoseexperimentally obtained.Key words: Physical-mathematical simulation, drying, zeolite, microwaves.

  15. Large-scale vertical velocity, diabatic heating and drying profiles associated with seasonal and diurnal variations of convective systems observed in the GoAmazon2014/5 experiment

    OpenAIRE

    Tang, Shuaiqi; Xie, Shaocheng; Zhang, Yunyan; Zhang, Minghua; Schumacher, Courtney; Upton, Hannah; Jensen, Michael P.; Johnson, Karen L.; Wang, Meng; Ahlgrimm, Maike; Feng, Zhe; Minnis, Patrick; Thieman, Mandana

    2016-01-01

    This study describes the characteristics of large-scale vertical velocity, apparent heating source (Q1) and apparent moisture sink (Q2) profiles associated with seasonal and diurnal variations of convective systems observed during the two intensive operational periods (IOPs) that were conducted from 15 February to 26 March 2014 (wet season) and from 1 September to 10 October 2014 (dry season) near Manaus, Brazil, during the Green Ocean Amazon (GoAmazon2014/5) experiment. The...

  16. Quality optimisation of combined osmotic dehydration and microwave assisted air drying of pineapple using constant power emission

    CSIR Research Space (South Africa)

    Botha, GE

    2012-04-01

    Full Text Available , Puebla M?xico. Prothon, F., Ahrne, L.M., Funebo, T., Kidman, S., Langton, M., Sjoholm, I., 2001. Effects of combined osmotic and microwave dehydration of apple on texture, microstructure and rehydration characteristics. Lebensmittel-Wissenschaft und...

  17. Overview of new techniques for drying biological materials with emphasis on energy aspects

    Directory of Open Access Journals (Sweden)

    G.S.V. Raghavan

    2005-06-01

    Full Text Available With increasing concern about environmental degradation, it is desirable to decrease energy consumption in all sectors. Drying has been reported to account for anywhere from 12 to 20% of the energy consumption in the industrial sector. Drying processes are one of the most energy intensive unit operations. There are a number of approaches to reduce energy consumption in dryers. This paper reviews some novel strategies used to decrease energy consumption in drying operations. Drying conditions can be modified or the drying equipments can be modified to increase overall efficiencies. Hybrid drying techniques can also be used, such as combining vacuum or convective drying with electro-technologies (microwave, radio frequency, infrared heating. There is much debate on how to define drying and energy efficiencies. Some techniques to determine these efficiencies can be misleading when the goal is to take a holistic approach to determining energy consumption.

  18. Natural color keeping of pueraria lobate ohwi root in drying process of microwave%葛根微波干燥中的护色工艺研究

    Institute of Scientific and Technical Information of China (English)

    周伟伟

    2011-01-01

    Utilize microwave which have high efficiency and uniform quality to dry pueraria lobate ohwi root quickly.Considering Pueraria Lobate Ohwi Root is easily browning when it is in Drying Process of Microwave, natural color keeping of Pueraria Lobate Ohwi Root in drying process of microwave was studied in this paper.Before dried in microwave, the economical and safety compound solution (sodium chloride, citric acid, calcium chloride) was used for protecting the original color of pueraria lobate ohwi.The treatment was dipped in compound solution for a few minutes, followed in running water, finally drained by centrifuge.This method can keep the dried merchandise with natural white color.Initially, the optimum level limit of sodium chloride, citric acid, calcium chloride, prime - heating time, the ratio of heating watt and sample gram was confirmed with single factor experiment.We can use perpendicularity experiment to find the best value namely 1.0% sodium chloride, 1.00% citric acid, 0.60% calcium chloride, prime - heating time was 8 minutes, the ratio of heating watt and sample gram was 2.%利用微波干燥的高效、均匀性对葛根进行快速干燥.针对葛根微波干燥过程中易出现褐变现象,影响产品感官品质,本文特对葛根微波干燥加工中的护色工艺进行探究.在干制前,采用经济和无残留的氯化钠、柠檬酸、氯化钙复合护色液对切分成型的半成品进行预处理后,再经清水漂洗、离心脱水后,然后进行微波干燥,可使干制品维持其原有组织的洁白色泽.试验前期,先通过单因素试验对氯化钠浓度、柠檬酸浓度、氯化钙浓度、前期加热功率与装载量比值、前期加热时间五个因素进行初步探索,甄选出护色效果显著的各因素最佳水平范围.最后再通过正交试验筛选出最佳值,即:氯化钠浓度1.0%、柠檬酸浓度1.00%、氯化钙浓度0.60%、前期加热功率与装载量比值(W/g)为2

  19. 微波干燥在乌梅人丹生产中的应用研究%Study on the application of microwave-drying in the production of Wumei Rendan

    Institute of Scientific and Technical Information of China (English)

    杜子荣; 张正滢; 邹敏

    2014-01-01

    目的:比较乌梅人丹用烘箱干燥和微波干燥的效果。方法:以溶散时限、水分、薄荷脑含量、甘草酸含量为指标,比较其效果。结果与结论:微波干燥可提高产品质量、提高生产能力、降低能耗,优于烘箱干燥。。%Objective: To compare the effects of two different methods (oven drying vs microwave drying ) on the dryness of Wumei Rendan. Methods:Their efifcacy was compared by taking the time limit of dissolution, moisture, and the contents of menthol and glycyrrhizic acid as indicators. Results&Conclusion:Microwave-drying can improve product quality, increase production capacity and reduce energy consumption and is superior to oven drying.

  20. Temperature and Moisture Distribution Model of Microwave Drying Germinated Brown Rice%微波干燥活性米的温度和水分的分布模型

    Institute of Scientific and Technical Information of China (English)

    孙婧; 朱广浩; 郑先哲

    2017-01-01

    The study obtained the distribution of temperature and moisture content in the microwave drying machine , by modeling a qualitative heat transfer model of the process of continuous microwave drying germinated brown rice .In order to determine the correctness of the model , experiments were conducted to verify the model of temperature and moisture at the microwave intensity as follows:1.16,2.75,4.34W/g.The results of the simulation and experiments show that in the continuous microwave dryer drying terminal , when the temperature rises slowly , microwave power should be controled to reduce the energy consumption of microwave drying;after the drying period entry into the tempering stage can make tem-perature reach a balance both inside and outside the material , it can also uniform drying effect and guarantee the quality of drying process at the same time .The study has guiding significance in the heating process and control of microwave dr-ying germinated brown rice .%通过建立连续微波干燥活性米过程的质热传递模型,获得活性米微波干燥机内的温度和含水率分布,并在微波强度为1.16、2.75、4.34W/g 的条件下,进行活性米温度和水分模型的实验验证,确定传热传质模型的正确性。模拟与实测结果表明:在连续式微波干燥机的干燥末段,温度上升较慢时相应控制微波功率,减少微波干燥的能耗;在干燥段后进入缓苏阶段,使活性米物料内外温度达到平衡,干燥效果更为均匀,又可以保证干燥品质。该研究对活性米的微波加热工艺及控制方面具有指导意义。

  1. Microwave-assisted on-spot derivatization for gas chromatography-mass spectrometry based determination of polar low molecular weight compounds in dried blood spots.

    Science.gov (United States)

    Sadones, Nele; Van Bever, Elien; Archer, John R H; Wood, David M; Dargan, Paul I; Van Bortel, Luc; Lambert, Willy E; Stove, Christophe P

    2016-09-23

    Dried blood spot (DBS) sampling and analysis is increasingly being applied in bioanalysis. Although the use of DBS has many advantages, it is also associated with some challenges. E.g. given the limited amount of available material, highly sensitive detection techniques are often required to attain sufficient sensitivity. In gas chromatography coupled to mass spectrometry (GC-MS), derivatization can be helpful to achieve adequate sensitivity. Because this additional sample preparation step is considered as time-consuming, we introduce a new derivatization procedure, i.e. "microwave-assisted on-spot derivatization", to minimize sample preparation of DBS. In this approach the derivatization reagents are directly applied onto the DBS and derivatization takes place in a microwave instead of via conventional heating. In this manuscript we evaluated the applicability of this new concept of derivatization for the determination of two polar low molecular weight molecules, gamma-hydroxybutyric acid (GHB) and gabapentin, in DBS using a standard GC-MS configuration. The method was successfully validated for both compounds, with imprecision and bias values within acceptance criteria (<20% at LLOQ, <15% at 3 other QC levels). Calibration lines were linear over the 10-100μg/mL and 1-30μg/mL range for GHB and gabapentin, respectively. Stability studies revealed no significant decrease of gabapentin and GHB in DBS upon storage at room temperature for at least 84 days. Furthermore, DBS-specific parameters, including hematocrit and volume spotted, were evaluated. As demonstrated by the analysis of GHB and gabapentin positive samples, "microwave-assisted on-spot derivatization" proved to be reliable, fast and applicable in routine toxicology. Moreover, other polar low molecular weight compounds of interest in clinical and/or forensic toxicology, including vigabatrin, beta-hydroxybutyric acid, propylene glycol, diethylene glycol, 1,4-butanediol and 1,2-butanediol, can also be

  2. Application of Microwave Determination of Calcium Sulphate in Dry Phosphorus Gypsum%微波测定干料磷石膏中硫酸钙的应用

    Institute of Scientific and Technical Information of China (English)

    彭桦; 周琼波; 杨稳权; 何宾宾; 韩增辉; 赵智波

    2016-01-01

    Dry phosphogypsum used specific digestion solution with microwave digestion to produce barium sulfate, the precipitation used glass sand core crucible vacuum filtering and reoccupy microwave constant for heavy precipitation. Obtained the experimental data, glass sand core crucible was low cost, using biodegradable poly epoxy succinic acid PESA ( salt) for soaking and washing, the recycling of glass sand core crucible was realized, the method was simple, analysis cycle was short, with energy saving and easy to operate, cheap instrument repairing, it was easy to promote.%干料磷石膏用特定的消解液微波消解,生成硫酸钡沉淀用玻璃砂芯坩埚负压抽滤,再用微波恒重沉淀,得出实验数据,玻璃砂芯坩埚用成本低、可降解的聚环氧琥珀酸PESA (盐)浸泡洗涤,实现了玻璃砂芯坩埚的再生利用,方法简便、分析周期短、节能易操作,仪器廉价易修,便于推广。

  3. Combining ground-based microwave radiometer and the AROME convective scale model through 1DVAR retrievals in complex terrain: an Alpine valley case study

    Directory of Open Access Journals (Sweden)

    P. Martinet

    2017-09-01

    Full Text Available A RPG-HATPRO ground-based microwave radiometer (MWR was operated in a deep Alpine valley during the Passy-2015 field campaign. This experiment aims to investigate how stable boundary layers during wintertime conditions drive the accumulation of pollutants. In order to understand the atmospheric processes in the valley, MWRs continuously provide vertical profiles of temperature and humidity at a high time frequency, providing valuable information to follow the evolution of the boundary layer. A one-dimensional variational (1DVAR retrieval technique has been implemented during the field campaign to optimally combine an MWR and 1 h forecasts from the French convective scale model AROME. Retrievals were compared to radiosonde data launched at least every 3 h during two intensive observation periods (IOPs. An analysis of the AROME forecast errors during the IOPs has shown a large underestimation of the surface cooling during the strongest stable episode. MWR brightness temperatures were monitored against simulations from the radiative transfer model ARTS2 (Atmospheric Radiative Transfer Simulator and radiosonde launched during the field campaign. Large errors were observed for most transparent channels (i.e., 51–52 GHz affected by absorption model and calibration uncertainties while a good agreement was found for opaque channels (i.e., 54–58 GHz. Based on this monitoring, a bias correction of raw brightness temperature measurements was applied before the 1DVAR retrievals. 1DVAR retrievals were found to significantly improve the AROME forecasts up to 3 km but mainly below 1 km and to outperform usual statistical regressions above 1 km. With the present implementation, a root-mean-square error (RMSE of 1 K through all the atmospheric profile was obtained with values within 0.5 K below 500 m in clear-sky conditions. The use of lower elevation angles (up to 5° in the MWR scanning and the bias correction were found to improve the

  4. Combining ground-based microwave radiometer and the AROME convective scale model through 1DVAR retrievals in complex terrain: an Alpine valley case study

    Science.gov (United States)

    Martinet, Pauline; Cimini, Domenico; De Angelis, Francesco; Canut, Guylaine; Unger, Vinciane; Guillot, Remi; Tzanos, Diane; Paci, Alexandre

    2017-09-01

    A RPG-HATPRO ground-based microwave radiometer (MWR) was operated in a deep Alpine valley during the Passy-2015 field campaign. This experiment aims to investigate how stable boundary layers during wintertime conditions drive the accumulation of pollutants. In order to understand the atmospheric processes in the valley, MWRs continuously provide vertical profiles of temperature and humidity at a high time frequency, providing valuable information to follow the evolution of the boundary layer. A one-dimensional variational (1DVAR) retrieval technique has been implemented during the field campaign to optimally combine an MWR and 1 h forecasts from the French convective scale model AROME. Retrievals were compared to radiosonde data launched at least every 3 h during two intensive observation periods (IOPs). An analysis of the AROME forecast errors during the IOPs has shown a large underestimation of the surface cooling during the strongest stable episode. MWR brightness temperatures were monitored against simulations from the radiative transfer model ARTS2 (Atmospheric Radiative Transfer Simulator) and radiosonde launched during the field campaign. Large errors were observed for most transparent channels (i.e., 51-52 GHz) affected by absorption model and calibration uncertainties while a good agreement was found for opaque channels (i.e., 54-58 GHz). Based on this monitoring, a bias correction of raw brightness temperature measurements was applied before the 1DVAR retrievals. 1DVAR retrievals were found to significantly improve the AROME forecasts up to 3 km but mainly below 1 km and to outperform usual statistical regressions above 1 km. With the present implementation, a root-mean-square error (RMSE) of 1 K through all the atmospheric profile was obtained with values within 0.5 K below 500 m in clear-sky conditions. The use of lower elevation angles (up to 5°) in the MWR scanning and the bias correction were found to improve the retrievals below 1000 m. MWR

  5. Rapid analysis of the essential oil components of dried Zanthoxylum bungeanum Maxim by Fe2O3-magnetic-microsphere-assisted microwave distillation and simultaneous headspace single-drop microextraction followed by GC-MS.

    Science.gov (United States)

    Ye, Qing

    2013-06-01

    In this work, microwave distillation assisted by Fe2 O3 magnetic microspheres (FMMS) and headspace single-drop microextraction were combined, and developed for determination of essential oil compounds in dried Zanthoxylum bungeanum Maxim (ZBM). The FMMS were used as microwave absorption solid medium for dry distillation of dried ZBM. Using the proposed method, isolation, extraction, and concentration of essential oil compounds can be carried out in a single step. The experimental parameters including extraction solvent, solvent volume, microwave power, irradiation time, and the amount of added FMMS, were studied. The optimal analytical conditions were: 2.0 μL decane as the extraction solvent, microwave power of 300 W, irradiation time of 2 min, and the addition of 0.1 g FMMS to ZBM. The method precision was from 4 to 10%. A total of 52 compounds were identified by the proposed method. The conventional steam distillation method was also used for the analysis of essential oil in dried ZBM and only 31 compounds were identified by steam distillation method. It was found that the proposed method is a simple, rapid, reliable, and solvent-free technique for the determination of volatile compounds in Chinese herbs. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Physicochemical properties of whole fruit plum powders obtained using different drying technologies.

    Science.gov (United States)

    Michalska, Anna; Wojdyło, Aneta; Lech, Krzysztof; Łysiak, Grzegorz P; Figiel, Adam

    2016-09-15

    Physicochemical quality parameters of plum powders obtained by applying conventional drying methods and their combination devised to process plums were evaluated. The effect of freeze-drying (FD), vacuum drying (VD), convective drying (CD), microwave-vacuum drying (MVD) and combination of convective pre-drying and microwave finish-drying (CPD-MVFD) affected physical (bulk density, porosity, colour, solubility) and chemical (polyphenolic compounds determined by UPLC and antioxidant capacity by TEAC ABTS and FRAP methods) properties of plum powders. The MVD at 1.2 W g(-1) and a novel combination for plum powders production - CPD-MVFD at 70 °C/1.2 W g(-1) allowed the best preservation of phenolic compounds and increased the efficiency of production. Results obtained support the use of MVD and its combination for better quality of dried plum products. The study proved that the determination of the browning index and HMF level (formed via Maillard reaction) might be good tool for monitoring the thermal processing of plum powders.

  7. 真空微波干燥重组鱼丸的研究%The Study of Vacuum Microwave Drying Re-Structured Fish Balls

    Institute of Scientific and Technical Information of China (English)

    陈凤杰; 张慜

    2012-01-01

    with the flesh of fish as main raw materialthe crisp dehydrated re-structured fish balls was prepared by the vacuum microwave puffing technology in this study. The effects of differetn kinds of auxiliary materials and cooking time on the expansion ratio and organoleptic quality of the re-structured fish balls were studied by single factor experiments, furthermore, the effect of microwave power and vacuum degree on the drying rate, expansion ratio and organoleptic quality of the re-structured fish ball were also determined and listed as follows: flesh of fish(after pretreatment) 100 g, glutinous .rice flour 10 g, pig fat 4 g, salt 2 g, white sugar 6 g, chives, ginger and, garlic seasoning 0. 6 g, cooking time 6 min, the vacuum degree-0. 095 MPa and microwave power 180 W, drying time 15 min. Under the optimum conditions, the products from this process demonstrated that a uniform faint yellow, the flavour of raw materials, and taste exquisite and crisp.%以鱼肉为主要原料,采用真空微波膨化技术制作松脆脱水重组鱼丸.通过大量单因素实验,研究了各种辅料和蒸煮时间对重组鱼丸膨化率和感官品质的影响;进一步采用真空微波膨化技术,研究了微波功率、真空度对重组鱼丸干燥速率、膨化率和感官品质的影响.结果表明,重组鱼丸的适宜配方和工艺条件为:鱼肉(经过预处理)100 g,糯米粉10 g,猪肥膘4 g,食盐2 g,白砂糖6 g,葱姜蒜粉0.6g;蒸煮时间为6 min,真空微波炉的真空度和微波功率分别为-0.095MPa和180W,干燥时间为15 min,得到的成品表面呈现均匀的淡黄色,有鲜美的鱼肉味,口感细腻、松脆.

  8. 77 FR 33106 - Energy Conservation Program: Test Procedure for Microwave Ovens

    Science.gov (United States)

    2012-06-05

    ... on a review of the cooking manuals and recipe books supplied with convection microwave ovens that a... books supplied with convection microwave ovens, DOE noted that a majority of the recipes that used... contained in the cooking manuals and recipe books supplied with convection microwave ovens. Based...

  9. Observing Convective Aggregation

    Science.gov (United States)

    Holloway, Christopher E.; Wing, Allison A.; Bony, Sandrine; Muller, Caroline; Masunaga, Hirohiko; L'Ecuyer, Tristan S.; Turner, David D.; Zuidema, Paquita

    2017-06-01

    Convective self-aggregation, the spontaneous organization of initially scattered convection into isolated convective clusters despite spatially homogeneous boundary conditions and forcing, was first recognized and studied in idealized numerical simulations. While there is a rich history of observational work on convective clustering and organization, there have been only a few studies that have analyzed observations to look specifically for processes related to self-aggregation in models. Here we review observational work in both of these categories and motivate the need for more of this work. We acknowledge that self-aggregation may appear to be far-removed from observed convective organization in terms of time scales, initial conditions, initiation processes, and mean state extremes, but we argue that these differences vary greatly across the diverse range of model simulations in the literature and that these comparisons are already offering important insights into real tropical phenomena. Some preliminary new findings are presented, including results showing that a self-aggregation simulation with square geometry has too broad distribution of humidity and is too dry in the driest regions when compared with radiosonde records from Nauru, while an elongated channel simulation has realistic representations of atmospheric humidity and its variability. We discuss recent work increasing our understanding of how organized convection and climate change may interact, and how model discrepancies related to this question are prompting interest in observational comparisons. We also propose possible future directions for observational work related to convective aggregation, including novel satellite approaches and a ground-based observational network.

  10. 微波与真空冷冻组合干燥加工佛手的工艺研究%Research on Processing Bergamot by Microwave Combined with Vacuum Freeze-Drying

    Institute of Scientific and Technical Information of China (English)

    章斌; 侯小桢; 饶强; 王泽彬

    2011-01-01

    [目的]探讨微波-真空冷冻组合干燥方式对佛手片加工的影响.[方法]以真空冷冻干燥总时间和成品复水率为主要指标,采用微波-真空冷冻组合干燥方式加工佛手片,并采用L9(33)正交试验优化工艺参数;同时,以成品Vc含量和精油含量为指标,对比不同干燥方法对佛手片品质的影响.[结果]相比单一的真空冷冻干燥,微波-真空冷冻组合干燥方法可明显缩短冻干总时间和提高成品复水率,该组合干燥的最优工艺参数为微波功率560 W,微波干燥时间2.5 min,物料厚度7mm,此条件下的冻干总时间为9.8h.[结论]微波-真空冷冻组合干燥相比微波干燥和真空冷冻干燥更能保证产品品质.%[Objective] To explore the effects of combined drying methods on processing of bergamot slices. [ Method ] Taking vacuum freeze-dr-ying time and rehydration rate as main indexes, processing bergamot slices by drying method of microwave combined with vacuum freeze-drying and optimum of parameters through L9(33) orthogonal experiments was studied; meanwhile, taking Vc content and essential oil content of bergamot product as indexes, the effect of quality by different drying methods was explored in this paper. [ Results ] Compared with vacuum freeze-drying, combined drying method can shorten freeze-drying time and improve rehydration rate significantly, under conditions of microwave 560 W, microwave processing time 2.5 min and material thickness 7 mm, the whole freeze-drying time is 9.8 h. [Conclusion] Combined drying method can improve products qualities better than microwave drying and vacuum freeze-drying.

  11. Determination of drying characteristics and quality properties of eggplant in different drying conditions

    Directory of Open Access Journals (Sweden)

    Gözde Bayraktaroglu Urun

    2015-12-01

    Full Text Available Drying is the most traditional process used for preserving eggplant a long time. The aim of this study was to determining drying characteristics and quality properties of eggplant dried by sun drying, hot air convective drying and infrared assisted convective drying. Convective drying and infrared assisted convective were carried out in a convective dryer at three different temperatures(40°, 50°, 60°C and air velocity at 5 m/s.The increasing of temperatures during the drying of eggplant led to a significant reduction of the drying time. However loss of nutrition was observed in eggplant samples dried at higher temperature.The biggest change in colour parameters was observed in samples dried with sun drying.So it was thought that sun drying had a negative effect on quality properties of eggplant samples.

  12. 微波辐射下固相反应合成二苯基甲基醚%Synthesis of Bis(diphenyl methyl)ether by Dry Reaction under Microwave Irradiation

    Institute of Scientific and Technical Information of China (English)

    路建美; 纪顺俊; 朱秀林; 程振平

    2000-01-01

    Bis(diphenyl methyl)ether was synthesized under microwave irradiation by dryreaction at ambient pressure. The rate of reaction was dramatically accelerated and high yield was obtained, comparing with that of methods using organic solvent as medium or using dry reaction by conventional heating. Keywords Diphenyl ketone, Bis (diphenyl methyl) ether, Microwave irradiation, Solid state.%在常压下用微波辐射固相反应的方法合成了二苯基甲基醚,与用有机溶剂为介质及传统的热固相反应方法相比,其反应速率快,产率高.

  13. Application of Microwave Drying in Two - Component Waterborne Polyurethane Wood Coatings%微波干燥应用于双组分水性聚氨酯木器漆的干燥过程

    Institute of Scientific and Technical Information of China (English)

    吴海生; 黄卫; 施国萍; 高建东

    2011-01-01

    Drying problem is a long - standing choke point for the industrialized application of two - component waterborne polyurethane.In this paper, microwave drying was adopted in the drying process of two component waterborne polyurethane coatings.This broke through the traditional viewpoint that the microwave drying could only be used in the drying process of one - component waterborne polyurethane coatings.The results showed that the film performance of the two - component waterborne polyurethane coating dried by the microwave was slightly better than that dried at room temperature, which was comparable to the benchmark - traditional solventborne polyurethane coating.In addition, the dosage of the curing agent was decreased.%干燥问题是长期以来制约水性双组分聚氨酯木器涂料工业化应用的瓶颈.将微波干燥应用于水性双组分聚氨酯木器涂料的干燥过程,打破了微波干燥只能应用于水性单组分涂料的传统观念,实验结果表明:水性双组分聚氨酯木器涂料经微波干燥形成的漆膜性能略高于常温干燥形成的漆膜,可与溶剂型双组聚氨酯木器涂料相媲美,且固化剂用量减少.

  14. 褐煤干燥过程对流传热特性的数值模拟%Numerical simulation of convective heat transfer characteristics during lignite drying process

    Institute of Scientific and Technical Information of China (English)

    钟晓晖; 靳振欢; 赵斌; 刘超

    2014-01-01

    以干燥器内对流传热问题为研究对象,建立了褐煤干燥过程气-固对流传热模型。通过流-固界面传热耦合,利用CFD仿真技术进行模拟,对褐煤在不同粒径、风速及温度下的干燥过程进行了数值模拟,得到不同工况下的温度场分布及对流传热系数。根据模拟结果拟合得到气-固传热关联式,结果表明该关联式与褐煤干燥过程较吻合,可为工程实践提供理论指导。%A gas-solid coupling convective heat transfer model was proposed for a dryer using CFD technique.The lignite drying process of different sizes,wind speeds and temperatures were simulated and temperature distribution and convective heat transfer coefficient were derived.The numerically fitted correlation of gas-solid heat transfer is in good agreement with the lignite drying process and can be used as a technical guidance.

  15. Secagem de fatias de abóboras (Cucurbita moschata, L. por convecção natural e forçada Drying of pumpkin (Cucurbita moschata, L. slices by natural and forced convection

    Directory of Open Access Journals (Sweden)

    Soraia Vilela Borges

    2008-12-01

    Full Text Available A abóbora (Cucurbita moschata, L. é uma importante fonte de provitamina A, de baixo custo, e sob a forma desidratada oferece diferentes opções de utilização e consumo. Secagens por convecção natural e forçada foram comparadas quanto ao grau de secagem atingido e encolhimento, em função da temperatura, velocidade de ar e dimensões do produto. Os resultados obtidos mostraram que o uso de fatias com volume de 6,25 cm³ em secador por convecção forçada a 50 °C e à velocidade de 5,5 x 10-4 ms-1 resultaram em produtos de menor encolhimento, sendo recomendadas estas condições.Besides its low price, Pumpkin (Cucurbita moschata, L. is an important source of provitamin-A, and when dehydrated it offers different options of utilizations and consumption. Natural and forced convection drying were compared according to the drying degree shrinkage as a function of temperature, and air velocity and product dimensions. The obtained results showed that slices with the volume of 6.25 cm³ in forced convection oven at 50 °C and at the velocity of 5.5 x 10-4 ms-1 resulted in a lower shrinkage products, so these conditions were recommended.

  16. Investigation of the processes of impregnation and drying of granular silica gel

    Science.gov (United States)

    Fedorov, A. V.; Zhilin, A. A.; Korobeinikov, Yu. G.

    2011-09-01

    The process of capillary impregnation and drying of silica gel grains in the acousto-convective drier of the ITPM of the Siberian branch of the Russian Academy of Sciences has been investigated experimentally. Two methods for humidifying a material with developed surface and internal structures have been considered. A comparison of these methods has been made and the influence of the impregnation rate on the geometry of silica gel grains has been analyzed. Silica gel grains were dried by three methods: microwave, convective, and acousto-convective. The dependence of the drying rate and the quality of the dried material on the chosen drying method has been shown. To describe the moisture extraction, we propose a mathematical model based on a two-dimensional diffusion equation written in the cylindrical system of coordinates. The moisture distribution in cylindrical samples consisting of silica gel grains has been obtained numerically for various values of the initial moisture content with the use of certain diffusion coefficients and the dependence of the moisture transfer coefficient on the frequency of acousto-convective action.

  17. Determination of volatile components in fresh, frozen, and freeze-dried Padrón-type peppers by gas chromatography-mass spectrometry using dynamic headspace sampling and microwave desorption.

    Science.gov (United States)

    Oruña-Concha, M J; López-Hernández, J; Simal-Lozano, J A; Simal-Gándara, J; González-Castro, M J; de la Cruz García, C

    1998-12-01

    "Padrón-type" peppers are a small variety of Capsicum annuum cultivated mainly in Galicia, Spain. To compare the effects of freezing and freeze-drying on the volatile components of Padrón-type peppers, preserved samples are analyzed by means of dynamic headspace sampling on an adsorbent followed by microwave desorption into a gas chromatograph equipped with a mass spectrometric detector. Sixty-five compounds are identified, including hydrocarbons, terpenes, alcohols, phenols, ethers, aldehydes, ketones, esters, pyrroles, pyrazines, and sulfurous compounds. Fresh whole, homogenized, and freeze-dried peppers have characteristic volatile-component profiles, whereas frozen peppers have a highly variable volatile-component profile.

  18. Ice Crystal Sizes and Their Impact on Microwave Assisted Freeze Drying%冰晶尺寸及其对微波辅助冷冻干燥的影响

    Institute of Scientific and Technical Information of China (English)

    吴宏伟; 陶治; 高平; 陈国华

    2004-01-01

    Freeze drying of an aqueous solution would result in the non-uniform distribution of solute concentration.Because ice is almost transparent to microwave, therefore such a non-uniform distribution may affect the microwave assisted freeze drying. The direct observation of the ice crystals formed under microscope reveals that the ice crystal sizes formed from de-ionized water depend on the cooling rate with fast cooling rate giving smaller ice crystals as expected. Once there is a sufficient amount of solute mixed with the de-ionized water, for example the reactive red,the size and its distribution are not very much dependent on either cooling rate or the final temperature provided there is sufficient time of cooling and the final temperature is not too low. The size of ice crystals formed within the solution of reactive red is usually below 100μm with a freezing rate of 1℃·min-1 for a droplet of the size of less than 1 mm. A simplified simulation indicates that such a small ice crystal would not cause a significant non-uniform distribution of temperature for microwave assisted freeze drying. When the ice crystal size is larger than 5 mm, heat conduction from the solute concentrated region to the ice region may need to be considered.

  19. Effect of Microwave Drying on Quality and Volatile Profiles of Rapeseeds%微波干燥对油菜籽品质及气味成分的影响

    Institute of Scientific and Technical Information of China (English)

    和珊; 丁超; 杨国峰; 朱江明; 赵娟

    2013-01-01

    利用不同的微波功率将菜籽干燥至安全水分8%,测定干燥后菜籽发芽势、发芽率、油的酸值和过氧化值,并使用固相微萃取-气质联用仪分析菜籽挥发性成分.结果表明:微波功率越高,干燥速率越大;高功率的微波对菜籽的生命力有显著的破坏作用;在110~1 480 W微波功率范围内,菜籽油的酸值变化在合理范围之内,过氧化值在1 170W功率干燥后呈显著上升趋势;微波功率的增加会导致硫甙分解有害产物的相对含量增加.菜籽的挥发性气体成分中含有硫甙分解生成物、烃类、醛类、酯类、醇类、杂环类、酮类等,其相对含量依次降低.%The rapeseeds were dried to final moisture content of 8% (wet basis)with different microwave power levels. Then the germinating capacity of seeds, acid value and peroxide value of rapeseed oil were determined. Volatile profiles of rapeseeds were analyzed by using SPME/GC -MS method. The results were as follows:The higher the microwave power level was, the faster the drying rate was; high microwave power could distinctively destroy germinating capacity; the acid value of rapeseed oil remained in a reasonable range within 110~1 480 W microwave power levels; peroxide value of rapeseed oil rise distinctively above 1 170 W microwave power level; content of glucosinolate decomposition products increased with higher microwave power level. After microwave drying, the volatile profiles of rapeseeds consisted of glucosinolate decomposition products, hydrocarbons, aldehydes, esters, alcohols, heterocycles, ketones,etc. The relative content decreased successively.

  20. Extraction of Artemisinin, an Active Antimalarial Phytopharmaceutical from Dried Leaves of Artemisia annua L., Using Microwaves and a Validated HPTLC-Visible Method for Its Quantitative Determination

    Directory of Open Access Journals (Sweden)

    Himanshu Misra

    2014-01-01

    Full Text Available A simple, rapid, precise, and accurate high-performance thin-layer chromatographic method coupled with visible densitometric detection of artemisinin is developed and validated. Samples of the dried Artemisia annua leaves were extracted via microwaves using different solvents. This method shows the advantage of shorter extraction time of artemisinin from leaves under the influence of electromagnetic radiations. Results obtained from microwave-assisted extraction (MAE were compared with hot soxhlet extraction. Chromatographic separation of artemisinin from plant extract was performed over silica gel 60 F254 HPTLC plate using n-hexane : ethyl acetate as mobile phase in the ratio of 75 : 25, v/v. The plate was developed at room temperature 25 ± 2.0°C. Artemisinin separation over thin-layer plate was visualized after postchromatographic derivatization with anisaldehyde-sulphuric acid reagent. HPTLC plate was scanned in a CAMAG’s TLC scanner 3 at 540 nm. Artemisinin responses were found to be linear over a range of 400–2800 ng spot−1 with a correlation coefficient 0.99754. Limits of detection and quantification were 40 and 80 ng spot−1, respectively. The HPTLC method was validated in terms of system suitability, precision, accuracy, sensitivity (LOD and LOQ, and robustness. Additionally, calculation of plate efficiency and flow constant were included as components of validation. Extracts prepared from different parts of the plant (leaves, branches, main stem, and roots were analyzed for artemisinin content, in which, artemisinin content was found higher in the leaf extract with respect to branches and main stem extracts; however, no artemisinin was detected in root extract. The developed HPTLC-visible method of artemisinin determination will be very useful for pharmaceutical industries, which are involved in monitoring of artemisinin content during different growth stages (in vitro and in vivo of A. annua for qualitative

  1. The Pilot Study on Microwave Drying Technology for Waste Resin from Nuclear Power Plant%核电站废离子交换树脂微波干燥可行性研究

    Institute of Scientific and Technical Information of China (English)

    高超; 安鸿翔; 梁栋; 贾梅兰; 杨卫兵; 闫小俊; 柳兆峰

    2012-01-01

    目前,核电站产生的废树脂,大多数采用暂存或水泥固化方法,但水泥固化增容比达4.8~5.2。桶内干燥工艺以其工艺简单,减容比大等优点,已在国外核电站得到应用。微波干燥具有由内向外的干燥特点。据报道,微波干燥废树脂的减容比可达5。用微波作为热源,在桶内干燥条件下对核电厂产生的废树脂开展了可行性研究。研究表明,在试验条件下,初始含水率50%左右的树脂,干燥后的含水率均小于10%,减容比为1.5~2。试验结果表明微波干燥废树脂是可行的。%At present, the waste resin produced by nuclear power plants are temporary stored or making into concretes, but the cement compatible ratio is 4.8 to 5.2. Barrel drying process has the advantages of simple process and reduces the capacity. It has been applied in foreign nuclear power plants. Microwave drying dries from the inside. According to reports, the microwave drying of waste resin can achieve a volume reduction ratio of up to 5. With microwave as the heat source, this paper studied the feasibihty of drying the waste resin generated from nuclear power plants in the barrel. The results show that under the experimental conditions, the water content of resin with initial moisture content of about 50% dropped to less than 10% after the drying, achieving volume reduction ratio of 1.5 to 2. The results showed that the microwave drying of waste resin is feasible.

  2. Migration of mineral hydrocarbons into foods. 4. Waxed paper for packaging dry goods including bread, confectionery and for domestic use including microwave cooking.

    Science.gov (United States)

    Castle, L; Nichol, J; Gilbert, J

    1994-01-01

    Retail samples of dry goods (bread, biscuits and breakfast cereals) packaged in waxed paper were examined for the presence of mineral hydrocarbon wax. Bread loaves contained up to 50 mg/kg of the wax (associated with the outer surfaces) and crackers up to 185 mg/kg. Mineral oil was found in bread samples, at up to 550 mg/kg and was dispersed throughout indicating its use in food processing machinery as the likely source. Retail confectionery products wrapped in waxed paper (containing 12-44% w/w) gave rise to levels of 12-1300 mg/kg mineral hydrocarbon in the individually wrapped sweets. Migration into boiled sweets was lowest at 10-130 mg/kg, whilst soft chews and toffee products contained 110-1300 mg/kg. The distribution of wax hydrocarbons (principally n-alkanes) in the confectionery coincided exactly with that for the paper wrapping, with a range of C23 to C33 (95% material) centred around C26. This indicated that the transfer to the food occurred largely by adhesion rather than by diffusion since the latter would be expected to favour preferential migration of the low molecular weight components. In simulated home-use experiments with waxed bags sold in the United States for domestic use, migration into sandwiches and cake amounted to 40 mg/kg (1% transfer of wax). Use of these waxed bags in the microwave oven (as recommended) gave rise to contamination of foods from 210 to 1650 mg/kg (up to 60% transfer of wax).

  3. The effects of layers in dry snow on its passive microwave emissions using dense media radiative transfer theory based on the quasicrystalline approximation (QCA/DMRT)

    Science.gov (United States)

    Liang, D.; Xu, X.; Tsang, L.; Andreadis, K.M.; Josberger, E.G.

    2008-01-01

    A model for the microwave emissions of multilayer dry snowpacks, based on dense media radiative transfer (DMRT) theory with the quasicrystalline approximation (QCA), provides more accurate results when compared to emissions determined by a homogeneous snowpack and other scattering models. The DMRT model accounts for adhesive aggregate effects, which leads to dense media Mie scattering by using a sticky particle model. With the multilayer model, we examined both the frequency and polarization dependence of brightness temperatures (Tb's) from representative snowpacks and compared them to results from a single-layer model and found that the multilayer model predicts higher polarization differences, twice as much, and weaker frequency dependence. We also studied the temporal evolution of Tb from multilayer snowpacks. The difference between Tb's at 18.7 and 36.5 GHz can be S K lower than the single-layer model prediction in this paper. By using the snowpack observations from the Cold Land Processes Field Experiment as input for both multi- and single-layer models, it shows that the multilayer Tb's are in better agreement with the data than the single-layer model. With one set of physical parameters, the multilayer QCA/DMRT model matched all four channels of Tb observations simultaneously, whereas the single-layer model could only reproduce vertically polarized Tb's. Also, the polarization difference and frequency dependence were accurately matched by the multilayer model using the same set of physical parameters. Hence, algorithms for the retrieval of snowpack depth or water equivalent should be based on multilayer scattering models to achieve greater accuracy. ?? 2008 IEEE.

  4. On the nature of rainfall in dry climate: Space-time patterns of convective rain cells over the Dead Sea region and their relations with synoptic state and flash flood generation

    Science.gov (United States)

    Belachsen, Idit; Marra, Francesco; Peleg, Nadav; Morin, Efrat

    2017-04-01

    Space-time patterns of rainfall are important climatic characteristics that influence runoff generation and flash flood magnitude. Their derivation requires high-resolution measurements to adequately represent the rainfall distribution, and is best provided by remote sensing tools. This need is further emphasized in dry climate regions, where rainfall is scarce and, often, local and highly variable. Our research is focused on understanding the nature of rainfall events in the dry Dead Sea region (Eastern Mediterranean) by identifying and characterizing the spatial structure and the dynamics of convective storm cores (known as rain cells). To do so, we take advantage of 25 years of corrected and gauge-adjusted weather radar data. A statistical analysis of convective rain-cells spatial and temporal characteristics was performed with respect to synoptic pattern, geographical location, and flash flood generation. Rain cells were extracted from radar data using a cell segmentation method and a tracking algorithm and were divided into rain events. A total of 10,500 rain cells, 2650 cell tracks and 424 rain events were elicited. Rain cell properties, such as mean areal and maximal rain intensity, area, life span, direction and speed, were derived. Rain events were clustered, according to several ERA-Interim atmospheric parameters, and associated with three main synoptic patterns: Cyprus Low, Low to the East of the study region and Active Red Sea Trough. The first two originate from the Mediterranean Sea, while the third is an extension of the African monsoon. On average, the convective rain cells in the region are 90 km2 in size, moving from West to East in 13 ms-1 and living 18 minutes. Several significant differences between rain cells of the various synoptic types were observed. In particular, Active Red Sea Trough rain cells are characterized by higher rain intensities and lower speeds, suggesting a higher flooding potential for small catchments. The north

  5. Secagem de bananas prata e d'água por convecção forçada Drying of banana prata and banana d'água by forced convection

    Directory of Open Access Journals (Sweden)

    Soraia Vilela Borges

    2010-09-01

    Full Text Available Estudou-se a influência de variáveis como cultivar, formato (cilindro e disco, branqueamento e condições do ar aquecido (temperatura: 50 e 70 ºC e velocidade: 0,14 e 0,42 m/s sobre o comportamento de secagem convectiva de bananas com uso de modelagem matemática. As bananas foram desidratadas em secador de bandejas e pesada em intervalos pré-determinados. O modelo exponencial foi bem ajustado às curvas de secagem (R²: 0,98-0,99, mostrando que os fatores mais influentes sobre a taxa de secagem foram a temperatura, a velocidade do ar e o branqueamento. De acordo com as constantes cinéticas apresentadas pelo modelo recomenda-se a secagem de banana, em qualquer dos formatos estudados, nas seguintes condições: para banana-prata, uso de branqueamento e secagem a 50 ºC/0,42 m/s; e para banana-d'água, sem uso de branqueamento e secagem a 70 ºC/0,42 m/s.The influence of variables such as cultivar, shape (cylinder and disc, blanching, and heated air conditions (temperatures of 50 and 70 ºC and velocities of 0.14 and 0.42 m/s on convective drying behavior of bananas using mathematical modeling. The bananas were dehydrated in a tray dryer and were weighed in predetermined periods of time. The exponential model showed good agreement with the drying curves (R²: 0.98-0.99 indicating that the factors that influenced the drying rate the most were temperature, air velocity, and blanching. According to the kinetics constants obtained with the model, the drying of bananas is recommended, including all shapes investigated under the following conditions: banana prata, blanching and drying at 50 ºC/0.42 m/s; and banana d'água, no blanching and drying at 70 ºC/0.42 m/s.

  6. 微波热风两段式干燥法生产婴幼儿保健糯米粉%Production of infant health glutinous rice powder by two stages method of microwave and hot air drying

    Institute of Scientific and Technical Information of China (English)

    李凤霞; 蒋欣欣; 陈守江; 于雷; 江铃

    2012-01-01

    In order to prevent the taste cold empty and abdominal distension diarrhea of infants,the edible traditional Chinese medicine poria cocos,dioscorea opposita thunb,lotus seed,and jujube were added into glutinous rice powder,and then the health glutinous rice powder was developed for infants.The curves of hot air and microwave drying were drawn based on a single factor experiment,and the best drying parameters were determined according to the orthogonal test under two dry optimal conditions,the best proportion of raw materials was determined by other orthogonal experiments.The results showed that the best parameters of dying were microwave 300W,1.5min,and then hot air drying 70℃,2h.The best ratio of raw material was 14g poria cocos and jujube,10g dioscorea opposita thunb,8g lotus seed were added into 100g glutinous rice,and 24% xylitol was added after being smashed.The combination drying method of hot-air drying with microwave drying could effectively keep raw natural composition and good sensory properties when health care glutinous rice powder was produced.%以糯米粉为基料,添加药食同源的中药茯苓、淮山药、莲子、红枣,开发一种能调理婴幼儿脾胃虚寒、腹胀腹泻的即食型糯米粉。依据单因素实验绘制热风和微波干燥曲线,并根据两种干燥的最适条件进行正交实验,确定最佳干燥参数;然后用正交实验对原辅料进行最佳配比实验。结果表明:原辅料最佳配比为100g基料中添加茯苓和红枣各14g,淮山药10g,莲子8g;先用300W微波干燥1.5min,后70℃热风干燥2h;粉碎后添加24%的木糖醇。采用微波热风联合干燥法生产即食型保健糯米粉可有效保持原料固有成分,且具有良好的感官性状。

  7. The Design of Microwave Heat Pump Drying Machine and Experimental Research%微波热泵联合干燥机的设计与试验研究

    Institute of Scientific and Technical Information of China (English)

    王教领; 宋卫东; 王明友; 吴今姬

    2016-01-01

    In order to solve the high energy consumption and poor quality problem of the agricultural products in the process of drying , The structure , working principle and key components of the machine are introduced .and take mush-room as raw material to explore the best dry process of microwave heat pump drying machine . The experiment results show that the microwave power 16kW, hot blast temperature 65℃, the conveyor belt speed 0.6 m/s, the moisture con-tent of dried lily flowers 12.37, rehydration ration 3.124, color 81.8, meeting the needs of dry request and is superior to the other combination , the paper for the development of microwave heat pump drying machine and needle mushroom dry to provide the reference .%为了解决农产品干燥过程中能耗高、品质差等问题,研制了一种微波热泵联合干燥机,对该机的整机结构、工作原理和关键部件做了介绍分析,并以金针菇为原料进行了微波热泵联合干燥机的最佳干燥工艺探究试验。试验表明:在微波功率13.3kW、热风温度65℃、传送带转速0.6m/s 时,干燥后的金针菇含水率12.37、复水比3.124、色差81.8,满足干燥要求且优于其他组合。该研究可为微波热泵联合干燥机的研制及金针菇的干燥提供参考。

  8. Effect of air flow rate on the polyphenols content and antioxidant capacity of convective dried cactus pear cladodes (Opuntia ficus indica).

    Science.gov (United States)

    Gallegos-Infante, José-Alberto; Rocha-Guzman, Nuria-Elizabeth; González-Laredo, Ruben-Francisco; Reynoso-Camacho, Rosalia; Medina-Torres, Luis; Cervantes-Cardozo, Veronica

    2009-01-01

    The interest in nopal has encouraged the use of dehydration; there are few studies about the effect of process parameters on the nopal polyphenol content and antioxidant activity. The objective of the present work was to evaluate the effect of air-drying flow rates on the amount and antioxidant capacity of extracts of Opuntia ficus indica cladodes. Nopal was dried at 45 degrees C and air flow rates of 3 and 5 m/sec. Samples were analyzed for moisture, total polyphenol, flavonoid, and flavonol contents, chain-breaking activity, inhibition of low-density lipoprotein and deoxyribose oxidation. Nopal drying at an air flow rate of 3 m/sec showed higher values of phenols, flavonoids and flavonols. The best value of low-density lipoprotein inhibition and deoxyribose was found at 1,000 microg/ml. The air flow rate affected the amount of polyphenols and the OH( . ) radical scavenging, but did not modify the chain-breaking activity and the low-density lipoprotein inhibition activity.

  9. 柱状胡萝卜样品热风微波耦合干燥数学模型%Mathematical modeling of microwave assisted air drying of cylindrical carrot samples

    Institute of Scientific and Technical Information of China (English)

    孙帅; 崔政伟

    2013-01-01

    利用热风微波耦合干燥装置研究了柱状胡萝卜样品的干燥特性,一个实验室规模的热风微波耦合干燥装置用来实现此实验目的.基于干燥过程中同时具有传热传质现象,建立了一个数学模型以此来预测干燥过程中样品内温度和含水量的分布.考虑到柱状样品的半径和微波的穿透深度,假定微波中的电场强度在样品内均匀分布.由于表面水分的蒸发而造成的热损失被考虑在内并将其作为模型的一个边界条件,利用数值方法中的隐式有限差分法对模型进行求解.通过干燥尺寸不同的柱状胡萝卜样品得到的实验值和模型的预测值进行比较来对模型进行验证,探讨了微波功率密度和热风温度的影响作用.%Drying behavior of cylindrical samples of carrot was investigated in a microwave assisted air drying.A pilot-scale microwave assisted air dryer was set up for this purpose.Based on the simultaneous heat and mass transfer,a mathematical model was proposed for predicting the temperature and moisture distribution in the drying sample.Considering the carrot radiuses and the penetration depth of the electromagnetic waves,a uniform electric field strength distribution within the drying material was assumed in the proposed model.The heat loss due to surface evaporative cooling was also considered at the external boundaries.A numerical solution was developed for the proposed model using an implicit finite difference method.The model was validated by comparing the predicted data with the experimental data,obtained from different cylindrical carrot samples during drying.The effects of microwave power density and also drying air temperature on the moisture and temperature profiles were investigated.

  10. 茭白片热风对流干燥模型与传质性能%The Model and Mass Transfer Performance of Convective Hot Air Drying of Water-Oat Slices

    Institute of Scientific and Technical Information of China (English)

    诸爱士

    2012-01-01

    In order to investigate the transfer characteristics of the water-oat drying process, a laboratory convective hot air dryer was applied to study the influences of drying temperature and thickness of water-oat slice on the drying process. The experimental data of moisture ratio of water-oat slices were used to fit the mathematical models, and the diffusion coefficients under different drying temperatures were calculated, the relative relations between the diffusion coefficient and drying temperature were also related. The results show that the drying temperature influences the drying process significantly, and the thinner slice benefits the moisture diffusion. Among several familiar numerical moisture ratio models, Page model of moisture ratio was found to be the most satisfactory one for the description of the kinetics of the hot air drying water-oat slices process. It was also found that, when the thickness of water-oat slice is 0.003 m, with the increase of temperature from 55℃ to 75℃, the water diffusion coefficient varies from 3.440×10-9 m2·s-1 to 6.357×10-9 m2·s-1; and it fits the Arrhenius equation, the activation energy is 27.86 kJ·mol-1. Under the same temperature, the experiments show that the thickness of the drying material has almost no influence on the water diffusion coefficient%为了探讨茭白干燥的传递特性,在对流热风干燥实验装置中进行了茭白片薄层干燥实验,研究了干燥温度、片的厚度对干燥过程的影响,将试验的水分比与数学模型进行了拟合,计算了不同温度下的水分扩散系数,并关联了其与干燥温度的关系.结果表明:干燥温度对干燥过程影响显著,薄片有利于水分扩散:用Page模型来描述茭白片热风干燥动力学令人满意;茭白片厚度为0.003m时,随风温升高,水分扩散系数从3.440×10-9 m2·s-1增大到6.357×10-9m2·s-1,并符合阿累尼乌斯方程,活化能为27.86 kj·mol-1.相同温度下,物料中水分的扩散系数基本不受厚度影响.

  11. Drying kinetics of bananas by natural convection: Influence of temperature, shape, blanching and cultivar Cinética de secagem de bananas por convecção natural: Influência da temperatura, formato, branqueamento e cultivar

    Directory of Open Access Journals (Sweden)

    Soraia Vilela Borges

    2011-04-01

    Full Text Available The influence of variables as temperature, solid shape, temperature, branching and cultivar on drying of bananas were studied. Bananas from cv. Prata and D'água, on disk and cylindrical shape, blanched or not, were dehydrated in a tray dryer in natural convection at 40 and 70ºC. Drying behavior was analyzed by using a mathematical model. The exponential model showed good agreement to experimental data (r² 0.93 - 0.99 and standard error: 0.01- 0.05. Temperature presented positive influence on drying rate in all the tested conditions. With respect to the sample shape, the disk shape carried out to significantly higher drying rates only for D'água cultivar without blanching. Blanching was significantly influent, with positive influence, on drying rate of banana cv. Prata at 40º C. The influence of the cultivar did not present a defined tendency.No presente trabalho, estudou-se a influência de variáveis como temperatura, formato do sólido, branqueamento e cultivar na secagem de bananas. Bananas cultivares Prata e D'água, nos formatos disco e cilindro, branqueadas ou não, foram desidratadas em secador de bandejas com convecção natural nas temperaturas de 40 e 70ºC. O comportamento da secagem foi analisado utilizandose modelagem matemática. O modelo exponencial mostrou bom ajuste aos resultados experimentais (r²: 0,93 - 0,99 e erro de estimativa padrão: 0,01 - 0,04. A temperatura apresentou influência positiva na taxa de secagem em todas as condições testadas. Com relação ao formato das amostras, o formato disco conduziu a taxas de secagem significativamente maiores somente para o cultivar D'água e sem branqueamento. O branqueamento se mostrou significativamente influente, com influência positiva na taxa de secagem da banana Prata a 40º C. A influência da cultivar não apresentou uma tendência definida.

  12. Determination of free amino acids and 18 elements in freeze-dried strawberry and blueberry fruit using an Amino Acid Analyzer and ICP-MS with micro-wave digestion.

    Science.gov (United States)

    Zhang, Hua; Wang, Zhen-Yu; Yang, Xin; Zhao, Hai-Tian; Zhang, Ying-Chun; Dong, Ai-Jun; Jing, Jing; Wang, Jing

    2014-03-15

    The objective of this study was to investigate the level of 18 trace elements of two freeze-dried samples from the Blueberry (Vaccinium corymbosum) and the Strawberry (Fragaria × Ananassa). The total free amino acid composition in the blueberry and strawberry was determined by an Amino Acid Analyzer. Eleven free amino acids were found in both berries. The trace elements in each dried fruit sample were determined by ICP-MS with microwave digestion. The linearity range of the standard curves was 0-1250.0 μg L(-1) (Mg, P, K, Ca),while in all cases, except for B, Na, Al, Cr, Mn, Fe, Ni, Cu, Zn, Se, Cd, Pb, Ge and As, which was 125.0 μg mL(-1), all related coefficients were above 0.9999; recovery was in the range of 79.0-106.8%. Minor concentrations of nutritional elements were found in each freeze-dried berry. In sum, the toxic trace element analysis found the content of toxic trace elements in each freeze-dried berry sample was safe for human consumption and that the overall quality of the blueberry surpassed that of the strawberry. The results certify that the two freeze-dried berries have potential for human consumption in value-added products and have a certain theoretical and practical significance.

  13. Advanced Drying Process for Lower Manufacturing Cost of Electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Iftikhar [Lambda Technologies, Inc., Morrisville, NC (United States); Zhang, Pu [Lambda Technologies, Inc., Morrisville, NC (United States)

    2016-11-30

    For this Vehicle Technologies Incubator/Energy Storage R&D topic, Lambda Technologies teamed with Navitas Systems and proposed a new advanced drying process that promised a 5X reduction in electrode drying time and significant reduction in the cost of large format lithium batteries used in PEV's. The operating principle of the proposed process was to use penetrating radiant energy source Variable Frequency Microwaves (VFM), that are selectively absorbed by the polar water or solvent molecules instantly in the entire volume of the electrode. The solvent molecules are thus driven out of the electrode thickness making the process more efficient and much faster than convective drying method. To evaluate the Advanced Drying Process (ADP) a hybrid prototype system utilizing VFM and hot air flow was designed and fabricated. While VFM drives the solvent out of the electrode thickness, the hot air flow exhausts the solvent vapors out of the chamber. The drying results from this prototype were very encouraging. For water based anodes there is a 5X drying advantage (time & length of oven) in using ADP over standard drying system and for the NMP based cathodes the reduction in drying time has 3X benefit. For energy savings the power consumption measurements were performed to ADP prototype and compared with the convection standard drying oven. The data collected demonstrated over 40% saving in power consumption with ADP as compared to the convection drying systems. The energy savings are one of the operational cost benefits possible with ADP. To further speed up the drying process, the ADP prototype was explored as a booster module before the convection oven and for the electrode material being evaluated it was possible to increase the drying speed by a factor of 4, which could not be accomplished with the standard dryer without surface defects and cracks. The instantaneous penetration of microwave in the entire slurry thickness showed a major advantage in rapid drying of

  14. Mass Transfer Simulation of Sigillate Walnut (Juglans sigillata Dode)During Convection Drying%云南核桃(Juglans sigillata Dode)对流干燥传质模拟

    Institute of Scientific and Technical Information of China (English)

    杨薇; 姜苗; 郭徽; 陈朝银

    2015-01-01

    在菲克定律与质量守恒定律的基础上建立了模拟云南核桃干燥过程的一维非稳态传质数学模型.通过边界条件的处理,结合云南核桃热风干燥试验,对其干燥过程中内部各层水分分布进行了模拟预测.将含水率的预测值与试验值对比可知该模型与试验数据吻合得很好,试验条件下云南核桃的有效水分扩散系数变化范围为1.14×10-9~1.73×10-9 m2/s.干燥初期云南核桃表层的含水率下降速度比内层快得多,之后内层含水率下降速度比表层要快,最终各层含水率稳步下降;从表层到中心,湿度梯度随着干燥时间的增加逐渐减小.分析表明在核桃的干燥过程中,外壳是影响水分扩散的主要阻力之一.该模型有助于云南核桃干燥过程传热传质耦合的研究以及复杂模型的建立.%Based on Fick's law and mass conservation law,a numerical model is developed to simulate the un-steady one -dimensional mass transfer during the convection drying process of sigillate walnut in this work. Through boundary condition treatment of diffusion model and combination of experimental drying curves,the ef-fective moisture diffusion coefficients are calculated and the moisture distribution as function of both position and drying time inside sigillate walnut is predicted using numerical calculation.Comparison between the predicted and experimental moisture content shows that the numerical model agrees well with the experimental data.The effec-tive moisture diffusion coefficients vary from 1.14 ×10 -9 to 1.73 ×10 -9 m2/s in the conditions studied.During the drying process,moisture content of the surface of sigillate walnut falls much faster than that of internal in the early period,while then the situation is just the reverse,finally the moisture content of each location decreases steadily.The moisture gradients from the surface to the centre decrease as the drying time increase

  15. 枇杷果脯真空渗糖和微波真空干燥工艺参数优化%Optimization of Vacuuming Sugar Infusion and Microwave Vacuum Drying Processing Parameters for Preserved Fruit of Eriobotrya japonica

    Institute of Scientific and Technical Information of China (English)

    谭红军; 杨勇; 吴振; 师萱; 陈岗

    2013-01-01

    [目的]提高枇杷果实的附加值.[方法]通过试验优化详细探讨了枇杷果脯的真空渗糖和微波真空干燥工艺参数,确定枇杷果脯的最佳制作工艺.[结果]试验表明,枇杷果脯最佳真空渗糖工艺参数为糖液浓度40%、柠檬酸用量0.25%、渗糖温度40℃、渗糖时间90 min;最佳微波真空干燥工艺参数为真空度0.07 MPa、微波强度5.06 W/g、微波干燥时间16.4 min;按此条件进行验证试验,枇杷果脯质量最佳.[结论]研究建立了枇杷果脯的真空渗糖和微波真空干燥工艺参数,可为枇杷果实的精深加工提供参考依据.%[Objective] To improve addictive value of Eriobotrya japonica fruits. [Method] Through experiment optimization, the vacuuming sugar infusion and microwave vacuum drying processing technological conditions were discussed in detail, the optimum processing technique was obtained. [Result] As indicated by the results, the optimum technique parameters are the density of vacuum sugar infiltration 40% , the content of citric acid 0.25% , the temperature 40 ℃, the time 90 min; the degree of vacuum 0.07 MPa, microwave power 5.06 W/g and microwave vacuum drying time 16.4 min. Under the optimum conditions, the high quality of preserved fruit of Eriobotrya japonica was formulated. [Conclusion] The vacuuming sugar infusion and microwave vacuum drying processing technological conditions of Eriobotrya japonica preserved fruit were established, which can provide reference basis for deep processing of Eriobotrya japonica fruits.

  16. Evaluation of drying methods with respect to drying kinetics, mineral content and colour characteristics of rosemary leaves

    Energy Technology Data Exchange (ETDEWEB)

    Arslan, Derya [Selcuk University, Faculty of Agriculture, Department of Food Engineering, Konya (Turkey); Musa Ozcan, M. [Selcuk University, Faculty of Agriculture, Department of Food Engineering, Konya (Turkey)], E-mail: mozcan@selcuk.edu.tr

    2008-05-15

    Rosemary leaves (Rosmarinus officinalis L., Lamiaceae) were dried by using sun, oven (50 deg. C) and microwave oven (700 W, 2450 MHz) drying methods. Microwave oven drying shortened the drying time more than 99% when compared to the sun and oven drying methods. K, Ca, Na, Mg and P were the most abundant elements in the rosemary samples. The mineral content of oven dried rosemary leaves was higher than that of the sun and microwave dried samples. The logarithmic and Midilli and Kuecuek models were shown to give a good fit to the sun and oven drying. The Page, Modified Page and Midilli and Kuecuek models have shown a better fit to the experimental microwave oven drying data of rosemary leaves. Microwave oven drying revealed optimum colour values. Oven drying resulted in a considerable decrease in the colour quality of the rosemary leaves.

  17. Process Research on Microwave Sterilization and Vacuum Packaging of Fragrant Dried Bean Curd%五香豆干微波杀菌真空包装加工工艺研究

    Institute of Scientific and Technical Information of China (English)

    武杰; 朱飞; 赵颖

    2011-01-01

    Fragrant dried bean curd is nutritious while hard to keep fresh. Microwave sterilization and vacuum packaging technology were adopted to extend the shelf life of fragrant dried bean curd. Firstly,Packed the fragrant dried bean curd, with water content about 65 percent, using high-temperature tolerant cooking bags. Then sterilized at 2450 MHz microwave for 120-180 s at room temperature. After cultured at (36 ± 1)°C incubator for 7 days, the bacteria quantity was not higher than GB2711 -2003 requirements and the sensory score was higher than control group. The processed products could be stored for 90 days at 1-l0°C conditions,60 days at room temperature(201). Results suggest that microwave sterilization and vacuum packing can effectively extend products shelf-life of fragrant dried bean curd.%五香豆于是营养丰富又极难防腐保鲜的食品,进行了利用微波杀菌真空包装技术延长五香豆干货架期的研究.将五香豆干采用耐高温蒸煮袋包装,含水量控制在65%左右,在室内常温条件下采用的频率为2450 MHz微波杀菌120~180 s,在(36±1)℃温箱培养7d后,其含菌量不高于GB2711-2003要求,感官评分远远高于对照组.在1~10℃条件下可以贮藏90d,在常温(20℃左右)条件下可以贮藏60d,微生物指标符合标准.结果表明采用微波杀菌真空包装技术可以有效地延长五香豆干的货架期.

  18. Numerical Simulation on Freeze Drying with Dielectric Material Assisted Microwave Heating%介电材料辅助的微波冷冻干燥的数值模拟

    Institute of Scientific and Technical Information of China (English)

    王维; 许英梅; 马鸿信; 陈国华

    2012-01-01

    The effects of the dielectric material on the microwave freeze-drying process were theoretically studied by mathematically solving the heat and mass transfer model considering the hygroscopic effect with a moving boundary in the porous media. Sintered silicon carbide (SiC) was used as the dielectric material, and the mannitol, a typical pharmaceutical excipient, was selected as the solute in aqueous solution. Simulation results show that the dielectric material can significantly enhance the microwave freeze drying rate under the experimental operating conditions, especially when the solid content in the freeze dried solution is very low or the solid product has a very small dielectric loss factor. Comparisons of the drying curves display good agreements between experimental measurements and model predictions. Based on the profiles of ice saturation and temperature, mechanisms of heat and mass transfer inside the material were analyzed, and the drying rate-controlling factor was discussed.%通过数值求解一个考虑吸湿效应的带有移动升华界面的多孔介质热、质传递耦合模型,理论考察介电材料对微波加热冷冻干燥过程的影响.介电材料用烧结的碳化硅(SiC).甘露醇,一种典型的药物赋形剂被选为待干溶液中的溶质.模拟结果表明在微波冷冻干燥过程中使用介电材料可以加快冷冻干燥速率,特别是在待干溶液的固含量很低或者固体产品的介电损耗因子很小的情况下尤为有效.模型预测和实验测定的干燥曲线相比较显示了良好的一致性.通过考察冰饱和度和温度的分布侧形,研究分析了物料内部的质热传递机理,并讨论了干燥速率的控制因素.

  19. Microwave engineering

    CERN Document Server

    Pozar, David M

    2012-01-01

    The 4th edition of this classic text provides a thorough coverage of RF and microwave engineering concepts, starting from fundamental principles of electrical engineering, with applications to microwave circuits and devices of practical importance.  Coverage includes microwave network analysis, impedance matching, directional couplers and hybrids, microwave filters, ferrite devices, noise, nonlinear effects, and the design of microwave oscillators, amplifiers, and mixers. Material on microwave and RF systems includes wireless communications, radar, radiometry, and radiation hazards. A large

  20. Evaluation of drying methods with respect to drying parameters, some nutritional and colour characteristics of peppermint (Mentha x piperita L.)

    Energy Technology Data Exchange (ETDEWEB)

    Arslan, Derya; Oezcan, M. Musa [Selcuk University, Faculty of Agriculture, Department of Food Engineering, Konya (Turkey); Menges, Hakan Okyay [Selcuk University, Faculty of Agriculture, Department of Farm Machinery, Konya (Turkey)

    2010-12-15

    Peppermint leaves (Mentha x piperita L.) were dried by using sun, oven (50 C) and microwave oven (700 W) drying methods. Page, Modified page, Midilli and Kuecuek models adequately described the oven, sun and microwave oven drying behaviours of peppermint leaves. The drying process was explicated through the diffusional model in order to obtain effective diffusivity values, which were determined as 3.10 x 10{sup -12}, 2.68 x 10{sup -12} and 4.09 x 10{sup -10} for the sun, oven and microwave oven drying process, respectively. Fresh and dried herbs had high amounts of K, Ca, P, Mg, Fe and Al minerals. Microwave oven drying method leaded to the lowest increase in Ag, Al, B, Na, Mn, Mg and Zn values than the other drying methods. Microwave oven drying shortened the drying time, revealed the highest phenolic content and optimum colour values. (author)

  1. Modeling multi-layer effects in passive microwave remote sensing of dry snow using Dense Media Radiative Transfer Theory (DMRT) based on quasicrystalline approximation

    Science.gov (United States)

    Liang, D.; Xu, X.; Tsang, L.; Andreadis, K.M.; Josberger, E.G.

    2008-01-01

    The Dense Media Radiative Transfer theory (DMRT) of Quasicrystalline Approximation of Mie scattering by sticky particles is used to study the multiple scattering effects in layered snow in microwave remote sensing. Results are illustrated for various snow profile characteristics. Polarization differences and frequency dependences of multilayer snow model are significantly different from that of the single-layer snow model. Comparisons are also made with CLPX data using snow parameters as given by the VIC model. ?? 2007 IEEE.

  2. Modeling of heat and mass transfer for timber during radio-frequency and convective drying%锯材高频-对流联合加热干燥传热传质数学模型

    Institute of Scientific and Technical Information of China (English)

    贾潇然; 赵景尧; 蔡英春

    2014-01-01

    The research based on the theory of porous medium heat and mass transfer,com-bined with the mechanism and characteristics of heat mass transfer in radio-frequency and con-vective drying,establish the mathematical model and give the definite condition through mass momentum and energy conservation equations. Each independent and dependent variable has in-dependent control equation. Use the finite volume method to establish difference equation for to decouple the coupled partial differential equations,so that each independent variable can be solved independently when programming in Matlab or FORTRAN .%本文以多孔介质传热传质理论为基础,结合高频-对流联合加热干燥过程中热质传递的机理及特性,通过质量、动量、能量守恒方程等建立了高频-对流联合加热干燥过程中锯材热质传递数学模型并给出相应定解条件。模型中每个自变量及因变量都有独立的控制方程,利用控制容积法建立相应控制方程的差分格式,将耦合偏微分方程按步骤解耦,以便于利用Matlab或FORTRAN等编程求解时,达到每个自变量均可以独立求解的目的。

  3. Kinetic Model for Rapid Convective Drying of Cut Strips Based on Shrinkage Property Analysis%基于收缩特性分析的叶丝快速对流干燥动力学模型

    Institute of Scientific and Technical Information of China (English)

    许冰洋; 朱文魁; 潘广乐; 申玉军; 李斌; 于川芳

    2015-01-01

    为准确表征叶丝脱水过程中的干燥动力学特性,分析了烤烟和白肋烟两种叶丝在下行床快速对流干燥中的孔隙结构变化特征,对叶丝干燥收缩过程进行了数学模型拟合,建立了考虑收缩形变的叶丝干燥过程水分扩散模型,并对模型进行了验证.结果表明:①随着干燥过程中两种叶丝内孔容积的减小,叶丝中孔径大于0.5μm的孔容比例呈降低趋势,而孔径小于0.05μm的孔容比例呈升高趋势;在不同干燥阶段两种叶丝孔径分布的分形维数介于2.45~2.71之间,表明其孔隙结构具有分形特征;②线性叠加式收缩模型能够较好地描述叶丝干燥过程中的收缩现象,烤烟叶丝和白肋烟叶丝体积比V/V0和含水率比X/X0的线性相关系数均大于0.99,采用该收缩模型对基于Fick第二定律的水分扩散模型进行修正,实验数据的拟合精度从修正前的0.906 9提升到修正后的0.958 0;③采用修正的水分扩散模型描述叶丝快速干燥动力学发现,考虑了干燥过程中的叶丝收缩现象后,得到的叶丝水分有效扩散系数降低,表明叶丝干燥过程中的体积收缩不利于传质过程.%In order to accurately characterize the kinetic characteristics of cut strips in the process of dehydration, the variation of pore structure in cut strips of flue-cured and burley tobaccos during rapid convective drying in a downflow bed was analyzed. The process of cut tobacco drying and shrinking was fitted by a mathematic model, and the model for moisture diffusion during drying taking into account the shrinking deformation was developed and verified. The results showed that: 1) With the decrease of pore volume of cut strips of flue-cured and burley tobaccos during drying, the proportion of volume of pores of > 0.5 μm in size decreased, while that of < 0.05 μm increased. The fractal dimension of the two tobaccos ranged from 2.45 to 2.71 at different drying stages, which indicated that

  4. Microwave Ovens

    Science.gov (United States)

    ... ovens heat food using microwaves, a form of electromagnetic radiation similar to radio waves. Microwaves have three characteristics ... that their microwave oven products meet the strict radiation safety standard ... if your microwave oven has damage to its door hinges, latches, or seals, or ...

  5. Dynamic absorption efficiency of sodium chloride in microwave drying%氯化钠在微波干燥中的动态吸波效率研究

    Institute of Scientific and Technical Information of China (English)

    尚小标; 陈君若; 张伟峰; 彭金辉; 陈华; 郭胜惠; 陈菓

    2014-01-01

    The concept of reflection loss was introduced to study the dynamic absorption efficiency of materials.The microwave reflection loss (RL)of sodium chloride was calculated in the moisture content ranged from 1%to 5%at 20 ℃ and sodium chloride (moisture content 4%)at 20-100 ℃ and 2.45 GHz.The calculated reflection losses show that the maximum microwave absorption with RL of -68 dB can be obtained for sodium chloride (moisture content 4%)with a thickness of 0.014 m at 60 ℃.With increasing thickness,the RL of sodium chloride appears microwave absorption peak following the order of the moisture content from high to low in turn.The results demonstrate that higher microwave absorption throughout the heating process can only be achieved in sodium chloride with a small thickness in which a slight absorption peak shift (less than one-eighth wavelength in sodium chloride)occurs.%为了研究物料在微波干燥过程中的动态吸波效率,文中将反射损耗理论引入其中,计算了2.45 GHz微波频率下,20℃时含水率为1%-5%以及含水率为4%的氯化钠在20-100℃的反射损耗系数。计算结果显示,厚度为0.014 m含水率4%的氯化钠在60℃取得最大的微波吸收效率,达到-68 dB;不同含水率的氯化钠反射损耗系数随着厚度的增加,会按照含水率由高到低的顺序依次出现吸波峰。研究结果表明,只有在对应小于1/8波长的吸收峰偏移的较小厚度下,氯化钠才能在整个微波干燥过程中一直取得较高的吸波效率。

  6. Microwave imaging

    CERN Document Server

    Pastorino, Matteo

    2010-01-01

    An introduction to the most relevant theoretical and algorithmic aspects of modern microwave imaging approaches Microwave imaging-a technique used in sensing a given scene by means of interrogating microwaves-has recently proven its usefulness in providing excellent diagnostic capabilities in several areas, including civil and industrial engineering, nondestructive testing and evaluation, geophysical prospecting, and biomedical engineering. Microwave Imaging offers comprehensive descriptions of the most important techniques so far proposed for short-range microwave imaging-in

  7. National Convective Weather Diagnostic

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current convective hazards identified by the National Convective Weather Detection algorithm. The National Convective Weather Diagnostic (NCWD) is an automatically...

  8. A comparison of solute migration in a test granulation dried by fluidization and other methods.

    Science.gov (United States)

    Travers, D N

    1975-07-01

    The intragranular migration of sodium chloride in granules made by the wet massing of heavy kaolin B.P. with salt solution has been studied in batches dried by fluidization and a vacuum tumbling method. The larger granules from the fluidized batch exhibited considerable intragranular variation with the outer crust containing over twice the average salt concentration. Solute loss from this layer by abrasion on prolonged fluidization was slight but the dust eluted from the dryer had a salt content above average. Analysis of sieved fractions of the dust showed that this enrichment was concentrated in the fine material passing a 53 mum mesh. The vacuum dried granules had less migration and were less resistant to crushing than those dried by fluidization. The dust produced had a salt content only slightly greater than the average composition and the overall solute content of the sized fractions were all close to this average. The same system was used to study intergranular migration in a fixed bed when the granules were dried by infrared radiation, by microwave radiation, by convection from air and in a vacuum. The greatest migration occurred in samples dried by infrared radiation and the maximum solute concentration was near the middle of the bed. The air dried granules had less migration and the maximum concentration was in the surface layer. The granules dried in a vacuum and by microwave radiation were fairly uniform in composition throughout the bed. The above results are explained on the basis of the capillary theory of drying together with the modifying influence of the drying method on the probable heat and mass transfer rates.

  9. Microwave Pretreatment Technology for the Vaccum Freeze Drying of Bergamot Based on the Optimization of Orthogonal Experiment%正交试验法优化真空冷冻干燥佛手的微波预处理工艺

    Institute of Scientific and Technical Information of China (English)

    章斌; 侯小桢; 王泽彬

    2011-01-01

    [目的]探讨微波预干燥处理时真空冷冻干燥佛手(FRUCTUS CITRI SARCOKACTYHS)的影响.[方法]以真空冷冻干燥总时间和成品复水率为主要指标,采用微波技术对佛手进行预干燥处理,并采用L3(33)正交试验对预处理条件进行优化.[结果]微波预干燥处理佛手的最优工艺条件为:微波功率420 W,物料厚度7 mm,物料转换点含水量40%,该条件下的真空冷冻干燥总时间为9.4 h.[结论]微波预处理可明显缩短冻干总时间,提高成品复水率.%[ Objective ] The aim was to discuss the effect of microwave pretreatment on vaccum freeze-drying of bergamot slices. [ Method ] Taking vacuum freeze-drying time and rehydration rate as main indexes, pre-drying processing on bergamot was carried out based on microwave technology and through L9 (33) orthogonal experiments, the optimum pre-processing parameters was optimized. [ Result] The optimal conditions of microwave pre-processing were as follows: microwave power was 420 W, material thickness was 7 mm and conversion moisture content of material was 40%. Under these conditions, the whole vaccum freeze-drying time was 9.4 h. [Conclusion] Microwave pre-proceasing can shortened the vaccum freeze-drying time and improved rehydration rate of finished products significantly.

  10. 超低密度植物纤维材料干燥特性和动力学模型%Drying characteristics and kinetic models for plant fibre-based ultra-low density mats

    Institute of Scientific and Technical Information of China (English)

    刘景宏; 杨文斌; 谢拥群; 魏微

    2012-01-01

    Drying is the most energy and time consuming step in the manufacture of ultra-low density plant fibre-based foaming mat (ULD mat) because of its high initial moisture content (MC). The drying characteristics of the ULD mat was examined under 6 drying conditions; convective hot-air drying at 3 temperatures (95, 100 and 105 ℃ ) and microwave drying under 3 microwave powers (80, 160 and 240 Watt). Three drying models, including diffusion model. Page model and the forth-order polynomial equation, were fitted to describe the moisture ratio (moisture at given time to initial moisture) in relation to drying time. The results indicated that the time needed for drying the mat from 600% to 10% ( dry base) decreased by 24% and 60% with increasing temperature from 95 to 105 ℃ for the convective hot-air drying and power from 80 to 240 Watt for the microwave drying, respectively. The microwave drying had an even drying rate, while the convective hot-air drying showed3 distinctive stages; fast drying stage from 600% to 250% MC, slowing-down stage from 250% to 100% MC and slow drying stage from 100% to 10% MC. The forth-order polynomial model fitted the data better than did the diffusion and Page models in terms of R2, while the coefficients in the forth-order polynomial model can be expressed as the second-order polynomial equation of drying parameters, i. e. , temperature for the convective hot-air drying and power for the microwave drying. The results should provide data and basis for the design of industrial manufacture line.%根据干燥动力学理论,分别设定95、100、105℃为热风对流干燥参数和80、160、240 W为微波干燥参数,对植物纤维发泡材料的热风对流和微波干燥的干燥特性进行了研究,并对干燥动力学特性进行数学模型拟合.研究表明,当绝对含水率≤100%,植物纤维发泡材料的热风对流干燥出现传热传质困难,干燥效率降低.而微波干燥速率稳定,干燥曲线呈近似直线线

  11. Single droplet drying for optimal spray drying of enzymes and probiotics

    NARCIS (Netherlands)

    Schutyser, M.A.I.; Perdana, J.A.; Boom, R.M.

    2012-01-01

    Spray drying is a mild and cost-effective convective drying method. It can be applied to stabilise heat sensitive ingredients, such as enzymes and probiotic bacteria, albeit in industrial practice for example freeze drying or freezing are often preferred. The reason is that optimum drying conditions

  12. Convection of Moist Saturated Air: Analytical Study

    Directory of Open Access Journals (Sweden)

    Robert Zakinyan

    2016-01-01

    Full Text Available In the present work, the steady-state stationary thermal convection of moist saturated air in a lower atmosphere has been studied theoretically. Thermal convection was considered without accounting for the Coriolis force, and with only the vertical temperature gradient. The analytical solution of geophysical fluid dynamics equations, which generalizes the formulation of the moist convection problem, is obtained in the two-dimensional case. The stream function is derived in the Boussinesq approximation with velocity divergence taken as zero. It has been shown that the stream function is asymmetrical in vertical direction contrary to the dry and moist unsaturated air convection. It has been demonstrated that the convection in moist atmosphere strongly depends on the vapor mass fraction gradient.

  13. 响应面法优化紫薯片的微波干制工艺%Optimize of microwave drying technology of purple sweet potato slices by response surface methodology

    Institute of Scientific and Technical Information of China (English)

    黄艳斌; 李星琪; 陈厚荣

    2015-01-01

    The fresh purple sweet potato was used as raw material and the characteristics of microwave drying and Optimizing of the drying were studied.The thickness and weight of slice, as well as the power of microwave on the influence of moisture content and drying rate and energy consumption were investigated by single factor experiment to get reasonable scope of various factors.On the basis of single factor experiment, water loss rate, energy consumption and the color value were chosen as the evaluation indexes.Optimal technological conditions were studied by the regression model established by three factors and three levels of response surface analysis.The results show that the weight and the dry power were the main factors affecting the rate of water loss and power consumption and the color difference value.Taking the greatest value of water loss, and smallest value of energy consumption and the color difference as factors, using the Design-Expert analysis software, the optimized conditions were: 2 mm thickness chips, weight 55.36g, microwave power 650 W, the water loss rate 17.215 8%/min, the power consumption 2.548 5 (kW · h)/ min, and the color difference 32.837 6.Under the same conditions, the validated experiments showed: water loss 17.103 8%/min,the power consumption 2.832 9 (kW · h)/min, the color difference 32.837 6.The experimental value is very close to the predicted value.%以新鲜紫薯为原料,研究其微波干燥特性并优化其干燥工艺参数.在单因素试验中,研究了切片厚度、载重量、微波功率对含水率、能耗及干燥速率的影响,得出各因素的合理范围.在单因素试验基础上,以失水速率、能耗、色差值为评价指标,利用三因素三水平的响应面分析法,优化了微波干燥工艺条件并建立了回归模型.结果表明:载重量、干燥功率是影响失水速率、耗电率、色差值的主要因素.通过对失水速率取极大值、能耗及色差取极小值,用Design

  14. Piroxicam loaded alginate beads obtained by prilling/microwave tandem technique: morphology and drug release.

    Science.gov (United States)

    Aquino, Rita P; Auriemma, Giulia; d'Amore, Matteo; D'Ursi, Anna Maria; Mencherini, Teresa; Del Gaudio, Pasquale

    2012-07-01

    This paper presents a tandem technique, based on the combination of prilling and microwave (MW) assisted treatments, to produce biodegradable alginate carriers of piroxicam with different drug controlled release behaviours. Results showed that alginate/piroxicam beads demonstrated high encapsulation efficiency and very narrow dimensional distribution. Beads dried by MW retained shape and size distribution of the hydrated particles while drying rate was strongly increased compared to convective drying processes. Moreover, different MW irradiation regimes promoted interactions between the drug and alginate matrix, affected drug polymorphism as well as inner and surface matrix structure leading to different piroxicam release profiles. High level MW irradiation led to beads with highly porous and swellable matrix able to release piroxicam in few minutes in the intestine while convective drying produced gastro-resistant beads that exhibit sustained piroxicam release (total release in 5.5h) in intestinal environment. On these results the tandem technique prilling/MW irradiation appears to be promising to obtain alginate carrier with tailored NSAIDs release depending on drug characteristics and MW irradiation.

  15. Impact of geographic variations of the convective and dehydration center on stratospheric water vapor over the Asian monsoon region

    Science.gov (United States)

    Zhang, Kai; Fu, Rong; Wang, Tao; Liu, Yimin

    2016-06-01

    The Asian monsoon region is the most prominent moisture center of water vapor in the lower stratosphere (LS) during boreal summer. Previous studies have suggested that the transport of water vapor to the Asian monsoon LS is controlled by dehydration temperatures and convection mainly over the Bay of Bengal and Southeast Asia. However, there is a clear geographic variation of convection associated with the seasonal and intra-seasonal variations of the Asian monsoon circulation, and the relative influence of such a geographic variation of convection vs. the variation of local dehydration temperatures on water vapor transport is still not clear. Using satellite observations from the Aura Microwave Limb Sounder (MLS) and a domain-filling forward trajectory model, we show that almost half of the seasonal water vapor increase in the Asian monsoon LS are attributable to geographic variations of convection and resultant variations of the dehydration center, of which the influence is comparable to the influence of the local dehydration temperature increase. In particular, dehydration temperatures are coldest over the southeast and warmest over the northwest Asian monsoon region. Although the convective center is located over Southeast Asia, an anomalous increase of convection over the northwest Asia monsoon region increases local diabatic heating in the tropopause layer and air masses entering the LS are dehydrated at relatively warmer temperatures. Due to warmer dehydration temperatures, anomalously moist air enters the LS and moves eastward along the northern flank of the monsoon anticyclonic flow, leading to wet anomalies in the LS over the Asian monsoon region. Likewise, when convection increases over the Southeast Asia monsoon region, dry anomalies appear in the LS. On a seasonal scale, this feature is associated with the monsoon circulation, convection and diabatic heating marching towards the northwest Asia monsoon region from June to August. The march of convection

  16. Dry Eye

    Science.gov (United States)

    ... Eye > Facts About Dry Eye Facts About Dry Eye This information was developed by the National Eye ... the best person to answer specific questions. Dry Eye Defined What is dry eye? Dry eye occurs ...

  17. Effects of Osmotic Conditions on the Osmosis-Vacuum Microwave Drying of Tilapia Meat%渗透条件对罗非鱼肉渗透-真空微波干燥的影响

    Institute of Scientific and Technical Information of China (English)

    刘兵; 段振华; 于群; 刘艳; 胡冰洋

    2016-01-01

    In order to obtain the optimum conditions for osmotic pretreatment before microwave drying of tilapia fillets, the effects of osmotic solution composition, osmosis time, temperature and slice size on the water content, water activity and qualities (shrinkage rate, rehydration rate and chromatic aberration) of dried tilapia fillets were studied. The results showed that higher osmotic dehydration efficiency for fish fillets was obtained with higher concentrations of sugar solutions, but under this condition dried product quality was unsatisfactory. The water content of tilapia fillets decreased with increasing osmosis time up to 2 h; however, no significant improvement in osmosis efficiency was observed when osmosis was prolonged beyond 2 h. Moreover, osmosis at elevated temperature led to improved dehydration efficiency but was hampered due to the destruction of the texture and microstructure of fillets at excessively high temperatures. Larger fillets had higher water content but poorer quality after being dried. The optimum conditions for osmotic dehydration before vacuum microwave drying of tilapia fillets were determined as osmosis of 500 mm² slices at 30℃ for 2 h in aqueous solution of 20% salt and 10% white granulated sugar.%为获得罗非鱼片渗透-真空微波干燥前最佳的渗透条件,研究渗透液组成、渗透时间、渗透温度和切片大小对鱼片渗透-真空微波干燥后的含水率、水分活度及品质(收缩率、复水率、色差)的影响。结果表明:鱼片在糖浓度较高的渗透液中,渗透脱水效果较好,但品质不理想;在2 h内鱼片含水率随渗透时间的延长而减少,2 h后渗透效果不明显;渗透温度升高脱水效率增加,但温度过高会破坏组织结构,不利于渗透的进行;切片越大,干燥后含水率越高但品质较差。结论:罗非鱼片渗透-真空微波干燥渗透最佳条件是渗透液组成为20%食盐+10%白砂糖,渗透时间2 h

  18. Microwave Photonics

    OpenAIRE

    Seeds, A.J.; Liu, C. P.; T. Ismail; Fice, M. J.; Pozzi, F; Steed, R. J.; Rouvalis, E.; Renaud, C.C.

    2010-01-01

    Microwave photonics is the use of photonic techniques for the generation, transmission, processing and reception of signals having spectral components at microwave frequencies. This tutorial reviews the technologies used and gives applications examples.

  19. 利用土壤干燥箱主动干燥-微波消解-原子吸收分光光度法测定土壤中的重金属%Determination of Heavy Metal in Soil through Active Drying of Soil Drying Oven,Microwave Digestion and Atomic Absorption Spectrophotometry

    Institute of Scientific and Technical Information of China (English)

    张健美; 吴春妍; 许卫娟

    2012-01-01

    The heavy metal in a large amount of soil sample could be determined in a short time by drying the soil with M280685 soil drying oven,microwave digestion and atomic absorption spectrophotometry.The qualified rate of the parallel double-sample testing by this method and the quality-controlled samples can both reach the requirements of Technical Specification for Soil Environmental Monitoring(HJ/T166-2004).%利用M280685土壤干燥箱干燥土壤、微波消解、原子吸收分光光度法,在短时间内完成大量土壤样品中重金属的测定。利用该法测定土壤中的重金属平行双样测定合格率,质控样品均能达到土壤环境监测技术规范(HJ/T166-2004)相应的要求。

  20. The Tropical Convective Spectrum. 1; Archetypal Vertical Structures

    Science.gov (United States)

    Boccippio, Dennis J.; Petersen, Walter A.; Cecil, Daniel J.

    2004-01-01

    A taxonomy of tropical convective vertical structures is constructed through cluster analysis of three years of Tropical Rainfall Measuring Mission [TRMM] Precipitation Radar [PR] vertical profiles, their surface rainfall and associated radar-based classifiers (convective/stratiform and bright band existence). archetypal profile types are identified. These include nine convective types, divided into warm, "just cold", midlevel, deep and deep/wet-growth categories, seven stratiform types, divided into warm, "just cold", midlevel and deep categories, three "mixed" types (deep profiles with low reflectivity aloft), and six fragment types (non-precipitating anvils and sheared deep convective profiles). The taxonomy allows for description of any storm or local Convective spectrum by the nine primary convective and stratiform types, a significant reduction over full three-dimensional radar data which nonetheless retains vertical structure information. The analysis provides a quasi-independent corroboration of the TRMM 2A23 convective/stratiform classification. The global frequency of occurrence and contribution to rainfall for the profile types is presented, demonstrating primary rainfall contribution by midlevel glaciated convection and similar depth decaying/stratiform stages. Close correspondence is found between deep convective profile frequency and annualized lightning production. Passive microwave and lightning properties associated with the profiles are reported, and cases presented illustrating known nonuniqueness problems with 85 and 37 GHz brightness temperature pairs (the same pairs corresponding to both convective and stratiform profiles), and how supplementary lightning information might be used to mitigate these problems.

  1. Secagem de fatias de abacaxi in natura e pré-desidratadas por imersão-impregnação: cinética e avaliação de modelos Assessment of convective drying models for fresh and osmo-dehydrated pineapple rings

    Directory of Open Access Journals (Sweden)

    Rafael Gomes Dionello

    2009-03-01

    Full Text Available O presente estudo teve como objetivos investigar o efeito da impregnação de sacarose e de açúcar invertido na taxa de secagem por convecção de abacaxi e avaliar a adequação de nove modelos matemáticos na descrição das curvas de secagem. Os testes experimentais foram feitos empregando-se coroas circulares de abacaxi in natura e pré-desidratadas por imersão-impregnação em soluções de sacarose (0,40, 0,44 e 0,47 g.mL-1 e em xarope de açúcar invertido. A pré-desidratação osmótica foi realizada a 40 e 50 ºC, por 2 horas, sob agitação de 60 min-1. A secagem por convecção foi feita em secador do tipo gabinete com bandejas, a 60 ºC e 1,25 m.s-1. O grau de ajuste dos modelos foi avaliado por meio do coeficiente de determinação, da raiz do erro quadrático médio, do erro percentual absoluto médio e por análise de dispersão de resíduos. As maiores taxas de secagem foram obtidas para amostras in natura; naquelas pré-desidratadas osmoticamente, o aumento da concentração da solução ocasionou a diminuição da taxa de secagem. O modelo de Wang e Singh foi o que melhor descreveu a secagem por convecção de coroas circulares de abacaxi.The effect of glucose and invert sugar impregnation on the convective drying rate of pineapple and the suitability of nine mathematical models to describe the drying curves were investigated. Tests were conducted using fresh pineapple rings and samples which were pre-treated by osmotic dehydration in sucrose solutions (0.40, 0.44, and 0.47 g mL-1 and in invert sugar syrup. Osmotic pre-treatments were performed at 40 and 50 ºC for 2 hours at 60 min-1. The convective drying was performed in a tray cabinet dryer using heated ambient air at 60 ºC and 1.25 m.s-1. The adjustment levels of the models were based on the correlation coefficient, the root mean square error, mean absolute percentage error, and residual plot analysis. The highest rates of convective drying were obtained for the fresh

  2. ESTABILIDADE OXIDATIVA DE AMÊNDOAS DE NOZ MACADÂMIA SECAS POR MICRO-ONDAS COM AR QUENTE OXIDATIVE STABILITY OF MACADAMIA NUTS DRYED WITH HOT AIR MICROWAVES

    Directory of Open Access Journals (Sweden)

    Maria Ássima Bittar Gonçalves

    2011-04-01

    Full Text Available

    A nogueira macadâmia (Macadamia integrifolia Maiden & Betche produz amêndoas de alto valor comercial, que se destacam pelo fino sabor e qualidade de seu óleo. O objetivo deste trabalho foi estudar a estabilidade oxidativa de amêndoas secas, com aplicação de energia de micro-ondas com ar quente, em comparação ao processo de secagem convencional. As análises, realizadas no início (tempo zero, com 90 dias e 180 dias de armazenamento, avaliaram ácidos graxos livres, índice de peróxido, período de indução, composição em ácidos graxos e teor de tocoferol/tocotrienol. O teor de ácidos graxos livres (% das amêndoas de noz macadâmia variou de 0,095 (MW1 a 0,124 (MW3 e de 0,123 a 0,148 (CVL; os índices de peróxidos (meq O2 kg-1 de óleo entre 0,77 (MW2  e 2,57 (MW1 e de 1,52 a 3,29 (CVL; o período de indução (h de 16,7 (MW2 a 13,6 (MW4 e entre 11,9 e 10,6 (CVL; o teor de ?-Tocotrienol (mg 100 g-1 de 1,75 a 2,19 (MW1 e de 2,14 a 2,19 (CVL, respectivamente, para a secagem com micro-ondas e convencional. Os valores da composição em ácidos graxos não se alteraram durante o armazenamento, com os processos de secagem utilizados. O método de secagem com micro-ondas mostrou-se mais eficiente, em relação à estabilidade oxidativa das amêndoas de noz macadâmia, quando comparado ao processo de secagem convencional.

     

    The macadamia tree (Macadamia integrifolia Maiden & Betche produces a nut of highly commercial value, distinguishable from other nuts by its delicate flavour and oil quality. This study aimed to compare the oxidative stability of dried nuts, with the application of hot air microwave energy, in relation to conventional drying. The analyses were performed at the

  3. Estimating the gross moist stability in shallow and deep convection

    Science.gov (United States)

    Chen, C. A.; Jong, B. T.; Chou, C.

    2015-12-01

    Gross moist stability has been used to study the link between tropical deep convection and large scale circulation in a moist static energy (MSE) budget. Here we aim to calculate the gross moist stability from more realistic profiles of vertical velocity and extend it beyond deep convection, adding shallow convection. Based on a principal component analysis, we were able to decompose the vertical velocity into two leading modes, which are dominated by deep and shallow convection, respectively. According to the deep and shallow modes, we calculate the gross moist stability for these two modes and discuss the roles of deep and shallow convection in the MSE budget. The gross moist stability of deep convection tends to be positive in the tropics, while that of shallow convection is negative over most areas of the tropics. This implies that deep convection exports MSE to stabilize the atmosphere and shallow convection imports MSE to enhance deep convection and destabilize the atmosphere. Based on the spatial distribution, moisture tends to reduce the gross moist stability of deep convection, while dry static energy has little impact. Deeper deep convection tends to have greater gross moist stability. For shallow convection, on the other hand, the gross moist stability is affected not only by low-level moisture but also mid-level moisture. Both moister low-level and drier mid-level moisture reduce the gross moist stability of shallow convection. Greater low-level dry static energy, which is associated with warmer sea surface temperature, also tends to reduce gross moist stability.

  4. THE LINE FOR PRODUCTION OF DRIED APPLES, PEARS, CARROTS, PUMPKIN AND CHIPS

    Directory of Open Access Journals (Sweden)

    G. V. Kalashnikov

    2015-01-01

    Full Text Available The line is intended for processing of fruit and vegetable raw materials and receiving dried apples, pears, carrots, pumpkins and the fruit-and-vegetable of chips. The line solves problems of improvement of quality of a ready-made product and thermal production efficiency due to more rational alternation of the technological modes of a moisture increment and dehumidification with high extent of use of an energy potential of the heat carrier, use of the inert heat carrier (steam identical by the form for technological thermal processes, decrease in specific energy consumption and metal consumption, and also an intensification of moisture evaporation and creation of the compact multipurpose technological line for production of fruit and vegetable products with the expanded range. The technological production line of dried apples, pears, carrots, pumpkin and fruit and vegetable chips contains the jet washer, the inspection conveyor, the size grader, the car for removal of a seed nest and the device are sharp fruits and vegetables on plates, the sulfiter, the dryer and the packing automatic packing machine. Thus the line contains the combined toroidal device for heatmoisture of handling continuous action divided into sections: section of heating of raw materials, section of convective drying, section of preliminary hydration, which is located between microwave drying sections, and the section of cooling of the dried-up product intended for bringing a product to final readiness. The equipment complex from the drum car with the washing block and multipurpose installation with crushing of raw materials and office of sunflower seeds taking into account raw materials type is provided in lines. Are used recirculation a contour, the heating of the initial raw material fulfilled after drying of pairs and a condensate in the closed contour for creation energy-saving of the "know-how" of a ready product. The line represents modular blocks and is recustomized

  5. Continuous microwave regeneration apparatus for absorption media

    Science.gov (United States)

    Smith, Douglas D.

    1999-01-01

    A method and apparatus for continuously drying and regenerating ceramic beads for use in process gas moisture drying operations such as glove boxes. A microwave energy source is coupled to a process chamber to internally heat the ceramic beads and vaporize moisture contained therein. In a preferred embodiment, the moisture laden ceramic beads are conveyed toward the microwave source by a screw mechanism. The regenerated beads flow down outside of the screw mechanism and are available to absorb additional moisture.

  6. Study on Vacuum Microwave Drying and Preservation of Fish Taste Crisp%鱼味脆粒的真空微波干燥及保藏

    Institute of Scientific and Technical Information of China (English)

    池金颖; 张慜; 陈凤杰

    2013-01-01

    以海产小杂鱼为主要原料,通过真空微波干燥制作鱼味脆粒.产品配方研究以色泽、膨化率和感官评定为指标,找出了鱼肉与淀粉的最佳配比,同时研究了食盐、白糖、调味料等辅料添加量对产品品质的影响.在单因素的基础上进行正交实验,确定了最佳的淀粉、食盐和白糖的比例.产品保藏研究采用厚铝箔袋和薄PE袋分别作真空和不抽真空处理,在37℃培养箱进行产品保温试验,以色差、水分活度、水分含量、脆度及脂肪氧化值为指标,确定最佳保藏方法.实验结果表明,最佳的鱼味脆粒配方为:鱼肉(经过预处理)100 g,马铃薯淀粉13 g,食盐1.75 g,白砂糖2 g,葱姜蒜粉0.8 g.在此配方下,产品的色泽金黄、味道鲜美、口感酥脆以及膨化效果佳;最佳保藏方法为厚铝箔袋抽真空包装.以上述配方和保藏方法生产出的产品,具有表面均匀光滑及可长期保藏的特点.%The vacuum microwave puffing technology was used to manufacture fish taste crisp, taking the low-value marine fish as main raw material. The best formulation is determined by several single factor experiments with different proportion of fish, starch, salt, sugar, and other flavorings,and the orthogonal experiment which shows the best volume of salt,sugar and starch. The indicators include color,puffed rate and sensory index. Products were packaged with thick aluminum bag and thin PE bag,by vacuum processing and not respectively and then placed in 37 ℃ for quality testing. According to the color,water activity,moisture content and fat oxidation value determines the best preservation method. The best formula of fish taste crisp is 100 g sea fish, 14g potato starch, 1.75 g salt,2 g sugar and 0.8 g chives,ginger and garlic seasoning. The best preservation method is using thick aluminum bag and taking vaccum processing. The products obtained can show a smooth surface,crunch taste,uniform expansion rate and

  7. National Convective Weather Forecast

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NCWF is an automatically generated depiction of: (1) current convection and (2) extrapolated signficant current convection. It is a supplement to, but does NOT...

  8. A continuous and prognostic convection scheme based on buoyancy, PCMT

    Science.gov (United States)

    Guérémy, Jean-François; Piriou, Jean-Marcel

    2016-04-01

    A new and consistent convection scheme (PCMT: Prognostic Condensates Microphysics and Transport), providing a continuous and prognostic treatment of this atmospheric process, is described. The main concept ensuring the consistency of the whole system is the buoyancy, key element of any vertical motion. The buoyancy constitutes the forcing term of the convective vertical velocity, which is then used to define the triggering condition, the mass flux, and the rates of entrainment-detrainment. The buoyancy is also used in its vertically integrated form (CAPE) to determine the closure condition. The continuous treatment of convection, from dry thermals to deep precipitating convection, is achieved with the help of a continuous formulation of the entrainment-detrainment rates (depending on the convective vertical velocity) and of the CAPE relaxation time (depending on the convective over-turning time). The convective tendencies are directly expressed in terms of condensation and transport. Finally, the convective vertical velocity and condensates are fully prognostic, the latter being treated using the same microphysics scheme as for the resolved condensates but considering the convective environment. A Single Column Model (SCM) validation of this scheme is shown, allowing detailed comparisons with observed and explicitly simulated data. Four cases covering the convective spectrum are considered: over ocean, sensitivity to environmental moisture (S. Derbyshire) non precipitating shallow convection to deep precipitating convection, trade wind shallow convection (BOMEX) and strato-cumulus (FIRE), together with an entire continental diurnal cycle of convection (ARM). The emphasis is put on the characteristics of the scheme which enable a continuous treatment of convection. Then, a 3D LAM validation is presented considering an AMMA case with both observations and a CRM simulation using the same initial and lateral conditions as for the parameterized one. Finally, global

  9. Microwave Microscope

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Makes ultra-high-resolution field measurements. The Microwave Microscope (MWM) has been used in support of several NRL experimental programs involving sea...

  10. Multicloud convective parametrizations with crude vertical structure

    Energy Technology Data Exchange (ETDEWEB)

    Khouider, Boualem [University of Victoria, Mathematics and Statistics, PO BOX 3045 STN CSC, Victoria, BC (Canada); Majda, Andrew J. [New York University, Department of Mathematics and Center for Atmosphere/Ocean Sciences, Courant Institute, New York, NY (United States)

    2006-11-15

    Recent observational analysis reveals the central role of three multi-cloud types, congestus, stratiform, and deep convective cumulus clouds, in the dynamics of large scale convectively coupled Kelvin waves, westward propagating two-day waves, and the Madden-Julian oscillation. The authors have recently developed a systematic model convective parametrization highlighting the dynamic role of the three cloud types through two baroclinic modes of vertical structure: a deep convective heating mode and a second mode with low level heating and cooling corresponding respectively to congestus and stratiform clouds. The model includes a systematic moisture equation where the lower troposphere moisture increases through detrainment of shallow cumulus clouds, evaporation of stratiform rain, and moisture convergence and decreases through deep convective precipitation and a nonlinear switch which favors either deep or congestus convection depending on whether the troposphere is moist or dry. Here several new facets of these multi-cloud models are discussed including all the relevant time scales in the models and the links with simpler parametrizations involving only a single baroclinic mode in various limiting regimes. One of the new phenomena in the multi-cloud models is the existence of suitable unstable radiative convective equilibria (RCE) involving a larger fraction of congestus clouds and a smaller fraction of deep convective clouds. Novel aspects of the linear and nonlinear stability of such unstable RCE's are studied here. They include new modes of linear instability including mesoscale second baroclinic moist gravity waves, slow moving mesoscale modes resembling squall lines, and large scale standing modes. The nonlinear instability of unstable RCE's to homogeneous perturbations is studied with three different types of nonlinear dynamics occurring which involve adjustment to a steady deep convective RCE, periodic oscillation, and even heteroclinic chaos in

  11. Modification of a Microwave Oven for Laboratory Use.

    Science.gov (United States)

    Andrews, Judith; Atkinson, George F.

    1984-01-01

    Discusses use of a domestic microwave oven for drying analytical samples with time savings compared to conventional ovens, providing a solution to the problem of loss of load as samples dry. Presents a system for examining emitted gases from drying process and reports results of several test dryings. (JM)

  12. Modification of a Microwave Oven for Laboratory Use.

    Science.gov (United States)

    Andrews, Judith; Atkinson, George F.

    1984-01-01

    Discusses use of a domestic microwave oven for drying analytical samples with time savings compared to conventional ovens, providing a solution to the problem of loss of load as samples dry. Presents a system for examining emitted gases from drying process and reports results of several test dryings. (JM)

  13. Toward a unified theory of atmospheric convective instability

    Science.gov (United States)

    Shirer, H. N.

    1982-01-01

    A nonlinear three-dimensional truncated spectral model of shallow and moist Boussinesq convection indicates that parallel instability and thermal forcing are linked, in view of the fact that only one convective mode exists in which either or both mechanisms are operating to generate convection in the planetary boundary layer. It is also established that the wind field causes two-dimensional roll convection formation, an alignment of the convection with the wind in a preferred manner, and a propagation speed that is related to the wind component perpendicular to the roll axis. Latent heating is responsible for the decrease of the critical value of the environmental lapse rate in accordance with the slice method stability criterion. When only the upper part of the upward branch is moist and all of the downward branch is dry, latent heating also causes a finite-amplitude convective solution for Rayleigh number values lower than the critical value of linear analysis.

  14. Effects of different drying methods on the product quality and volatile compounds of whole shiitake mushrooms.

    Science.gov (United States)

    Tian, Yuting; Zhao, Yingting; Huang, Jijun; Zeng, Hongliang; Zheng, Baodong

    2016-04-15

    Various drying methods play important roles in the preservation of foods. However, how the different drying methods affect the quality of some foods is not clear. This paper evaluates the effects of hot air, vacuum, microwave, and microwave vacuum drying techniques on important qualities and volatile compounds of whole shiitake (Lentinus edodes) mushrooms. These four drying methods resulted in a significantly (pdried products. Microwave vacuum drying helped to maintain larger amounts of taste-active amino acids, and improved nutrient retention and color attributes. Furthermore, the uniform honeycomb network created by microwave vacuum drying along with a less collapsed structure of dried samples can be used to explain the observed high rehydration ratio. Therefore, microwave vacuum drying should be a potential method for obtaining high-quality dried mushrooms.

  15. A diffusion model for drying of a heat sensitive solid under multiple heat input modes.

    Science.gov (United States)

    Sun, Lan; Islam, Md Raisul; Ho, J C; Mujumdar, A S

    2005-09-01

    To obtain optimal drying kinetics as well as quality of the dried product in a batch dryer, the energy required may be supplied by combining different modes of heat transfer. In this work, using potato slice as a model heat sensitive drying object, experimental studies were conducted using a batch heat pump dryer designed to permit simultaneous application of conduction and radiation heat. Four heat input schemes were compared: pure convection, radiation-coupled convection, conduction-coupled convection and radiation-conduction-coupled convection. A two-dimensional drying model was developed assuming the drying rate to be controlled by liquid water diffusion. Both drying rates and temperatures within the slab during drying under all these four heat input schemes showed good accord with measurements. Radiation-coupled convection is the recommended heat transfer scheme from the viewpoint of high drying rate and low energy consumption.

  16. Effects of Drying Processes on the Antioxidant Properties in Sweet Potatoes

    Institute of Scientific and Technical Information of China (English)

    YANG Jing; CHEN Jin-feng; ZHAO Yu-ying; MAO Lin-chun

    2010-01-01

    The effects of different drying methods (hot-air drying, microwave drying and vacuum-freeze drying) on the antioxidant activity and antioxidants in sweet potato (Ipomoea batatas L. Lam.) tubers were investigated to determine the potential drying process. Sweet potato tubers were cut into 5 mm thick slices, steamed at 100~C for 10 rain, then dried in either hot-air, microwave, or vacuum-freeze. The dried sweet potatoes in microwave possessed the highest antioxidant activity,while the lowest activity was observed in hot-air dried samples. The phenolic contents were positively correlated with scavenging activity and reducing power of DPPH+. The microwave drying retains the highest antioxidant activity with the highest content of phenolic compounds in dried sweet potatoes. β-carotene and ascorbic acid showed minor contribution to the antioxidant activity in dried sweet potatoes.

  17. The Tropical Convective Spectrum. Part 1; Archetypal Vertical Structures

    Science.gov (United States)

    Boccippio, Dennis J.; Petersen, Walter A.; Cecil, Daniel J.

    2005-01-01

    A taxonomy of tropical convective and stratiform vertical structures is constructed through cluster analysis of 3 yr of Tropical Rainfall Measuring Mission (TRMM) "warm-season" (surface temperature greater than 10 C) precipitation radar (PR) vertical profiles, their surface rainfall, and associated radar-based classifiers (convective/ stratiform and brightband existence). Twenty-five archetypal profile types are identified, including nine convective types, eight stratiform types, two mixed types, and six anvil/fragment types (nonprecipitating anvils and sheared deep convective profiles). These profile types are then hierarchically clustered into 10 similar families, which can be further combined, providing an objective and physical reduction of the highly multivariate PR data space that retains vertical structure information. The taxonomy allows for description of any storm or local convective spectrum by the profile types or families. The analysis provides a quasi-independent corroboration of the TRMM 2A23 convective/ stratiform classification. The global frequency of occurrence and contribution to rainfall for the profile types are presented, demonstrating primary rainfall contribution by midlevel glaciated convection (27%) and similar depth decaying/stratiform stages (28%-31%). Profiles of these types exhibit similar 37- and 85-GHz passive microwave brightness temperatures but differ greatly in their frequency of occurrence and mean rain rates, underscoring the importance to passive microwave rain retrieval of convective/stratiform discrimination by other means, such as polarization or texture techniques, or incorporation of lightning observations. Close correspondence is found between deep convective profile frequency and annualized lightning production, and pixel-level lightning occurrence likelihood directly tracks the estimated mean ice water path within profile types.

  18. Combination microwave ovens: an innovative design strategy.

    Science.gov (United States)

    Tinga, Wayne R; Eke, Ken

    2012-01-01

    Reducing the sensitivity of microwave oven heating and cooking performance to load volume, load placement and load properties has been a long-standing challenge for microwave and microwave-convection oven designers. Conventional design problem and solution methods are reviewed to provide greater insight into the challenge and optimum operation of a microwave oven after which a new strategy is introduced. In this methodology, a special load isolating and energy modulating device called a transducer-exciter is used containing an iris, a launch box, a phase, amplitude and frequency modulator and a coupling plate designed to provide spatially distributed coupling to the oven. This system, when applied to a combined microwave-convection oven, gives astounding performance improvements to all kinds of baked and roasted foods including sensitive items such as cakes and pastries, with the only compromise being a reasonable reduction in the maximum available microwave power. Large and small metal utensils can be used in the oven with minimal or no performance penalty on energy uniformity and cooking results. Cooking times are greatly reduced from those in conventional ovens while maintaining excellent cooking performance.

  19. Microwave processing of ceramic oxide filaments

    Energy Technology Data Exchange (ETDEWEB)

    Vogt, G.J.; Katz, J.D. [Los Alamos National Laboratory, NM (United States)

    1995-05-01

    The objective of the microwave filament processing project is to develop microwave techniques at 2.45 GHZ to manufacture continuous ceramic oxide filaments. Microwave processing uses the volumetric absorption of microwave power in oxide filament tows to drive off process solvents, to burn out organic binders, and to sinter the dried fibers to produce flexible, high-strength ceramic filaments. The technical goal is to advance filament processing technology by microwave heating more rapidly with less energy and at a lower cost than conventional processing, but with the same quality as conventional processing. The manufacturing goal is to collaborate with the 3M Company, a US manufacturer of ceramic oxide filaments, to evaluate the technology using a prototype filament system and to transfer the microwave technology to the 3M Company.

  20. Microwave Measurements

    CERN Document Server

    Skinner, A D

    2007-01-01

    The IET has organised training courses on microwave measurements since 1983, at which experts have lectured on modern developments. Their lecture notes were first published in book form in 1985 and then again in 1989, and they have proved popular for many years with a readership beyond those who attended the courses. The purpose of this third edition of the lecture notes is to bring the latest techniques in microwave measurements to this wider audience. The book begins with a survey of the theory of current microwave circuits and continues with a description of the techniques for the measureme

  1. Microwave photonics

    CERN Document Server

    Lee, Chi H

    2006-01-01

    Wireless, optical, and electronic networks continue to converge, prompting heavy research into the interface between microwave electronics, ultrafast optics, and photonic technologies. New developments arrive nearly as fast as the photons under investigation, and their commercial impact depends on the ability to stay abreast of new findings, techniques, and technologies. Presenting a broad yet in-depth survey, Microwave Photonics examines the major advances that are affecting new applications in this rapidly expanding field.This book reviews important achievements made in microwave photonics o

  2. A new conceptual model of convection

    Energy Technology Data Exchange (ETDEWEB)

    Walcek, C. [State Univ. of New York, Albany, NY (United States)

    1995-09-01

    Classical cumulus parameterizations assume that cumulus clouds are entraining plumes of hot air rising through the atmosphere. However, ample evidence shows that clouds cannot be simulated using this approach. Dr. Walcek suggests that cumulus clouds can be reasonably simulated by assuming that buoyant plumes detrain mass as they rise through the atmosphere. Walcek successfully simulates measurements of tropical convection using this detraining model of cumulus convection. Comparisons with measurements suggest that buoyant plumes encounter resistance to upward movement as they pass through dry layers in the atmosphere. This probably results from turbulent mixing and evaporation of cloud water, which generates negatively buoyant mixtures which detrain from the upward moving plume. This mass flux model of detraining plumes is considerably simpler than existing mass flux models, yet reproduces many of the measured effects associated with convective activity. 1 fig.

  3. Microwave generator

    Science.gov (United States)

    Kwan, T.J.T.; Snell, C.M.

    1987-03-31

    A microwave generator is provided for generating microwaves substantially from virtual cathode oscillation. Electrons are emitted from a cathode and accelerated to an anode which is spaced apart from the cathode. The anode has an annular slit there through effective to form the virtual cathode. The anode is at least one range thickness relative to electrons reflecting from the virtual cathode. A magnet is provided to produce an optimum magnetic field having the field strength effective to form an annular beam from the emitted electrons in substantial alignment with the annular anode slit. The magnetic field, however, does permit the reflected electrons to axially diverge from the annular beam. The reflected electrons are absorbed by the anode in returning to the real cathode, such that substantially no reflexing electrons occur. The resulting microwaves are produced with a single dominant mode and are substantially monochromatic relative to conventional virtual cathode microwave generators. 6 figs.

  4. Microwave photonics

    CERN Document Server

    Lee, Chi H

    2013-01-01

    Microwave photonics continues to see rapid growth. The integration of optical fiber and wireless networks has become a commercial reality and is becoming increasingly pervasive. Such hybrid technology will lead to many innovative applications, including backhaul solutions for mobile networks and ultrabroadband wireless networks that can provide users with very high bandwidth services. Microwave Photonics, Second Edition systematically introduces important technologies and applications in this emerging field. It also reviews recent advances in micro- and millimeter-wavelength and terahertz-freq

  5. Effect of drying method to antioxidants capacity of Limnophila aromatica

    Science.gov (United States)

    Yen, Tran Thi Ngoc; Vu, Nguyen Hoang

    2017-09-01

    Limnophila aromatica is widely used in South East Asian countries to make spices in food and medicine in traditional medicine. The use value of vegetables is known because some of the lesser constituents in plants are called antioxidants. These active ingredients have not been fully researched and their pharmacological effects are underestimated. In this study, the drying temperature at 40 °C was showed that the antioxidant activity decreased the most. The drying temperature of 50 °C is suitable for convection drying method and drying temperature of 60 °C suitable for vacuum drying, as it retains the most antioxidant properties. Regarding the drying method, freeze drying proved to be effective when retaining high antioxidant capacity. Using The convection drying at 50 °C and the vacuum drying at 60 °C, the antioxidant activity of Limnophila aromatica was not different. Over 6 weeks of preservation, the dried product has deterioration in antioxidant properties.

  6. The Impact of Upper Tropospheric Humidity from Microwave Limb Sounder on the Midlatitude Greenhouse Effect

    Science.gov (United States)

    Hu, Hua; Liu, W. Timothy

    1998-01-01

    This paper presents an analysis of upper tropospheric humidity, as measured by the Microwave Limb Sounder, and the impact of the humidity on the greenhouse effect in the midlatitudes. Enhanced upper tropospheric humidity and an enhanced greenhouse effect occur over the storm tracks in the North Pacific and North Atlantic. In these areas, strong baroclinic activity and the large number of deep convective clouds transport more water vapor to the upper troposphere, and hence increase greenhouse trapping. The greenhouse effect increases with upper tropospheric humidity in areas with a moist upper troposphere (such as areas over storm tracks), but it is not sensitive to changes in upper tropospheric humidity in regions with a dry upper troposphere, clearly demonstrating that there are different mechanisms controlling the geographical distribution of the greenhouse effect in the midlatitudes.

  7. Stochastic Convection Parameterizations

    Science.gov (United States)

    Teixeira, Joao; Reynolds, Carolyn; Suselj, Kay; Matheou, Georgios

    2012-01-01

    computational fluid dynamics, radiation, clouds, turbulence, convection, gravity waves, surface interaction, radiation interaction, cloud and aerosol microphysics, complexity (vegetation, biogeochemistry, radiation versus turbulence/convection stochastic approach, non-linearities, Monte Carlo, high resolutions, large-Eddy Simulations, cloud structure, plumes, saturation in tropics, forecasting, parameterizations, stochastic, radiation-clod interaction, hurricane forecasts

  8. Convection and oscillations

    CERN Document Server

    Houdek, G

    2010-01-01

    In this short review on stellar convection dynamics I address the following, currently very topical, issues: (1) the surface effects of the Reynolds stresses and nonadiabaticity on solar-like pulsation frequencies, and (2) oscillation mode lifetimes of stochastically excited oscillations in red giants computed with different time-dependent convection formulations.

  9. Avaliação nutricional e sensorial de caqui cv Fuyu submetido à desidratação osmótica e secagem por convecção Nutritional and sensory evaluation of osmo-convective dried Fuyu persimmons

    Directory of Open Access Journals (Sweden)

    Nathalia de Felice Elias

    2008-06-01

    Full Text Available A crescente preocupação com a saúde humana tem promovido o aumento da demanda pelo consumo de frutas, tanto in natura como processadas. Neste trabalho, foram realizadas as avaliações nutricional e sensorial de caqui Fuyu submetido à desidratação osmótica e secagem por convecção. Cilindros de caqui com diâmetro de 15 mm e altura de 40 mm foram imersos por 2 horas em solução com concentração de sacarose de 0,47 g.mL-1, a 40 ºC, utilizando-se relação fruta/xarope de 1:10 e grau de agitação de 60 min-1. A redução do teor de água até 17% b.u. foi realizada a 60 ºC, empregando-se velocidade do ar de 1,25 m/s. Após a secagem, foram realizadas as seguintes análises físico-químicas: acidez, pH, ºBrix, carboidratos, proteínas, lipídios, vitamina C, cinzas, fibras insolúveis e análise sensorial. Os resultados mostraram incremento em todas as características físico-químicas avaliadas para o caqui desidratado em comparaç��o ao caqui in natura. A análise sensorial evidenciou que o produto obteve elevado índice de aceitação, correspondendo ao segundo e terceiro níveis da escala hedônica (gostei muito e gostei regularmente. A característica que influenciou predominantemente a aceitação do produto foi a textura (88%, seguida do sabor (84%. A aparência foi o atributo que menos influenciou a aceitação (80%.The increasing trend towards a healthier lifestyle has prompted a renewed interest in fruit consumption, either fresh or dried. The objectives of the present work were to assess the nutritional quality and conduct consumer sensory evaluation testing of osmo-convective dried Fuyu persimmons. Persimmon cylinders of 15 mm diameter and 40 mm length were partially dehydrated by impregnation soaking, at 40 ºC, in a 0.47 g.mL-1 sucrose solution, with a fruit to syrup ratio of 1:10. Samples were dehydrated in a shaker under a constant agitation level, 60 min-1 for 2 hours. The water content of the product was

  10. Recent Improvements in Estimating Convective and Stratiform Rainfall in Amazonia

    Science.gov (United States)

    Negri, Andrew J.

    1999-01-01

    In this paper we present results from the application of a satellite infrared (IR) technique for estimating rainfall over northern South America. Our main objectives are to examine the diurnal variability of rainfall and to investigate the relative contributions from the convective and stratiform components. We apply the technique of Anagnostou et al (1999). In simple functional form, the estimated rain area A(sub rain) may be expressed as: A(sub rain) = f(A(sub mode),T(sub mode)), where T(sub mode) is the mode temperature of a cloud defined by 253 K, and A(sub mode) is the area encompassed by T(sub mode). The technique was trained by a regression between coincident microwave estimates from the Goddard Profiling (GPROF) algorithm (Kummerow et al, 1996) applied to SSM/I data and GOES IR (11 microns) observations. The apportionment of the rainfall into convective and stratiform components is based on the microwave technique described by Anagnostou and Kummerow (1997). The convective area from this technique was regressed against an IR structure parameter (the Convective Index) defined by Anagnostou et al (1999). Finally, rainrates are assigned to the Am.de proportional to (253-temperature), with different rates for the convective and stratiform

  11. Pulsation driving and convection

    Science.gov (United States)

    Antoci, Victoria

    2015-08-01

    Convection in stellar envelopes affects not only the stellar structure, but has a strong impact on different astrophysical processes, such as dynamo-generated magnetic fields, stellar activity and transport of angular momentum. Solar and stellar observations from ground and space have shown that the turbulent convective motion can also drive global oscillations in many type of stars, allowing to study stellar interiors at different evolutionary stages. In this talk I will concentrate on the influence of convection on the driving of stochastic and coherent pulsations across the Hertzsprung-Russell diagram and give an overview of recent studies.

  12. Performance of a convective, infrared and combined infrared- convective heated conveyor-belt dryer.

    Science.gov (United States)

    El-Mesery, Hany S; Mwithiga, Gikuru

    2015-05-01

    A conveyor-belt dryer was developed using a combined infrared and hot air heating system that can be used in the drying of fruits and vegetables. The drying system having two chambers was fitted with infrared radiation heaters and through-flow hot air was provided from a convective heating system. The system was designed to operate under either infrared radiation and cold air (IR-CA) settings of 2000 W/m(2) with forced ambient air at 30 °C and air flow of 0.6 m/s or combined infrared and hot air convection (IR-HA) dryer setting with infrared intensity set at 2000 W/m(2) and hot at 60 °C being blown through the dryer at a velocity of 0.6 m/s or hot air convection (HA) at an air temperature of 60 °C and air flow velocity 0.6 m/s but without infrared heating. Apple slices dried under the different dryer settings were evaluated for quality and energy requirements. It was found that drying of apple (Golden Delicious) slices took place in the falling rate drying period and no constant rate period of drying was observed under any of the test conditions. The IR-HA setting was 57.5 and 39.1 % faster than IR-CA and HA setting, respectively. Specific energy consumption was lower and thermal efficiency was higher for the IR-HA setting when compared to both IR-CA and HA settings. The rehydration ratio, shrinkage and colour properties of apples dried under IR-HA conditions were better than for either IR-CA or HA.

  13. Efeito do pré-tratamento osmótico com sacarose e cloreto de sódio sobre a secagem convectiva de abóbora Effect of osmotic pre-treatment with sucrose and sodium chloride on convective drying of pumpkin

    Directory of Open Access Journals (Sweden)

    Isabella Borin

    2008-03-01

    slices during air-drying. The effective water diffusivities of pre-treated and non-treated samples were similar when average thickness was used. Drying rates of the treated samples were higher than those of the non-treated samples, showing that the pre-treatments enhanced the efficiency of convective drying. The color and the general appearance of the dried pumpkin were improved by the previous treatments in comparison to the non-treated samples.

  14. Convective heat transfer

    CERN Document Server

    Kakac, Sadik; Pramuanjaroenkij, Anchasa

    2014-01-01

    Intended for readers who have taken a basic heat transfer course and have a basic knowledge of thermodynamics, heat transfer, fluid mechanics, and differential equations, Convective Heat Transfer, Third Edition provides an overview of phenomenological convective heat transfer. This book combines applications of engineering with the basic concepts of convection. It offers a clear and balanced presentation of essential topics using both traditional and numerical methods. The text addresses emerging science and technology matters, and highlights biomedical applications and energy technologies. What’s New in the Third Edition: Includes updated chapters and two new chapters on heat transfer in microchannels and heat transfer with nanofluids Expands problem sets and introduces new correlations and solved examples Provides more coverage of numerical/computer methods The third edition details the new research areas of heat transfer in microchannels and the enhancement of convective heat transfer with nanofluids....

  15. Kinetic Study of Convective Drying of Blueberry Variety O’neil (Vaccinium corymbosum L. Estudio de la Cinética del Secado Convectivo de Arándano Variedad O’Neil (Vaccinium corymbosum L.

    Directory of Open Access Journals (Sweden)

    A Vega-Gálvez

    2009-06-01

    Full Text Available The aim of this research was to study and to model the drying kinetics of the blueberry Vaccinium corymbosum L. at three temperatures (60, 70 and 80 ºC with an airflow of 2.0 ± 0.2 m s-1. Modeling of the desorption isotherm was carried out with the GAB (Guggenheim, Anderson and de Boer equation, showing a good fit to experimental moisture data, giving as a result a monolayer moisture level of 0.084 g water g-1 dm. Newton, Henderson-Pabis, Page, Modified Page and Logarithmic mathematical models were applied in the study and in the modeling of the drying kinetics of this fruit. Kinetic parameters k of each model showed dependence on temperature, and were evaluated by an Arrhenius-type equation, with an activation energy of between 36.2 and 54.5 kJ mol-1. Logarithmic and Modified Page models gave the best fits for each drying curve, based on the statistical test determination coefficient, sum square error, root mean sum errors and Chi-square. In consequence, both models are excellent tools for estimating the drying time of this product.El objetivo de esta investigación fue estudiar y modelar la cinética de secado del arándano ( Vaccinium corymbosum L. a tres temperaturas (60, 70 y 80 ºC con un flujo de aire de 2,0 ± 0,2 m s-1. El modelado de la isoterma de desorción se llevó a cabo con la ecuación de GAB (Guggenheim, Anderson y de Boer, mostrando un buen ajuste sobre los datos experimentales de humedad, dando como resultado una humedad de la monocapa de 0,084 g de agua g-1 ms. Se aplicaron los modelos matemáticos de Newton, Henderson-Pabis, Page, Page modificado y Logarítmico para el modelado de la cinética de secado de esta fruta. Los parámetros cinéticos k de cada modelo presentaron dependencia con la temperatura, evaluadas por una ecuación de tipo Arrhenius, con una energía de activación entre 36,2-54,5 kJ mol-1. Los modelos Logarítmico y Page modificado obtuvieron el mejor ajuste para cada curva de secado, basado en las

  16. [Effect on quality of Scrophulariae Radix with modern drying technology].

    Science.gov (United States)

    Li, Hui-wei; Liu, Pei; Qian, Da-wei; Lu, Xue-jun; Guo, Sheng; Zhu, Zhen-hua; Duan, Jin-ao

    2015-11-01

    Modern drying technology was used to explore suitable drying process to provide scientific basis for improving drying processing methods of Scrophulariae Radix. Controlled temperature and humidity drying, vacuum drying apparatus, microwave vacuum drying apparatus, short infrared drying device were used to gain samples for analyzing. The character appearance, concentration of main components and power consumption indicators were chosen for preliminary judging. Six major components, including iridoids and phenylpropanoids were analyzed by UPLC-MS/MS method. The contents of polysaccharides were determined by UV-visible spectrophotometry. The character appearance with controlled temperature and humidity drying and short infrared drying meet the pharmacopoeia standard (Ch. p, edition 2015), while samples with vacuum and microwave vacuum drying apparatus didn't. Compared to fresh sample, concentrations of harpagide, harpagoside, aucubin and catalpol were lower in the dried samples. Angoroside-C showed no significant change before and after drying. Concentration of acteoside increased after drying. Samples with controlled temperature (70 degrees C) and humidity (15% - 10%) drying had high content and short drying time. The better drying process of Scrophulariae Radix was controlled temperature and humidity drying. The method will provide the reference for the drying technology standard of roots medicine.

  17. Transparent electric convection heater

    OpenAIRE

    Khalid, A.; Luck, J.L.

    2001-01-01

    An optically transparent electrically heated convection heater for use as a space heater in homes, offices, shops. Typically, said convection heater consists of a transparent layer 1 upon which is deposited a layer of a transparent electrically conductive material 2 such as indium-tin-oxide, electrodes 3 and 3a are formed on opposite edges of the transparent electrically conductive layer 2 and electrical wires 4 and 4a are connected to the electrodes. The transparent electrically conductive l...

  18. Evaluation of convective heat transfer coefficient of various crops in cyclone type dryer

    Energy Technology Data Exchange (ETDEWEB)

    Akpinar, E. Kavak [Mechanical Engineering Department, Firat University, 23279 Elazig (Turkey)]. E-mail: eakpinar@firat.edu.tr

    2005-09-15

    In this paper, an attempt was made to evaluate the convective heat transfer coefficient during drying of various crops and to investigate the influences of drying air velocity and temperature on the convective heat transfer coefficient. Drying was conducted in a convective cyclone type dryer at drying air temperatures of 60, 70 and 80 deg. C and velocities of 1 and 1.5 m/s using rectangle shaped potato and apple slices (12.5 x 12.5 x 25 mm) and cylindrical shaped pumpkin slices (35 x 5 mm). The temperature changes of the dried crops and the temperature of the drying air were measured during the drying process. It was found that the values of convective heat transfer coefficient varied from crop to crop with a range 30.21406 and 20.65470 W/m{sup 2} C for the crops studied, and it was observed that the convective heat transfer coefficient increased in large amounts with the increase of the drying air velocity but increased in small amounts with the rise of the drying air temperature.

  19. Finite element based model of parchment coffee drying

    OpenAIRE

    Preeda Prakotmak

    2015-01-01

    Heat and mass transfer in the parchment coffee during convective drying represents a complicated phenomena since it is important to consider not only the transport phenomena during drying but also the various changes of the drying materials. In order to describe drying of biomaterials adequately, a suitable mathematical model is needed. The aim of the present study was to develop a 3-D finite element model to simulate the transport of heat and mass within parchment coffee during the thin laye...

  20. Effects of drying methods on the tasty compounds of Pleurotus eryngii.

    Science.gov (United States)

    Li, Xiaobei; Feng, Tao; Zhou, Feng; Zhou, Shuai; Liu, Yanfang; Li, Wen; Ye, Ran; Yang, Yan

    2015-01-01

    The aim of this research was to study effects of drying methods on the tasty compounds of Pleurotus eryngii, a common commercial edible fungus. In order to maximally maintain the taste of P. eryngii, several different drying methods, including hot air, vacuum, microwave, freeze drying and naturally air-drying, were compared. Results showed that freeze drying and hot air were capable of the conservation of the taste compounds maximally in P. eryngii, followed by natural air drying and vacuum, while microwave drying was not suitable for P. eryngii due to the loss of taste compounds. Moreover, concentrations of free amino acids in freeze drying were significantly reduced, so as to 5'-nucleotides in hot air drying. In addition, the umami concentration of the sample using hot air dry was significantly (p<0.05) higher than that using microwave.

  1. Anomalously Weak Solar Convection

    Science.gov (United States)

    Hanasoge, Shravan M.; Duvall, Thomas L.; Sreenivasan, Katepalli R.

    2012-01-01

    Convection in the solar interior is thought to comprise structures on a spectrum of scales. This conclusion emerges from phenomenological studies and numerical simulations, though neither covers the proper range of dynamical parameters of solar convection. Here, we analyze observations of the wavefield in the solar photosphere using techniques of time-distance helioseismology to image flows in the solar interior. We downsample and synthesize 900 billion wavefield observations to produce 3 billion cross-correlations, which we average and fit, measuring 5 million wave travel times. Using these travel times, we deduce the underlying flow systems and study their statistics to bound convective velocity magnitudes in the solar interior, as a function of depth and spherical- harmonic degree l..Within the wavenumber band l convective velocities are 20-100 times weaker than current theoretical estimates. This constraint suggests the prevalence of a different paradigm of turbulence from that predicted by existing models, prompting the question: what mechanism transports the heat flux of a solar luminosity outwards? Advection is dominated by Coriolis forces for wavenumbers l convection may be quasi-geostrophic. The fact that isorotation contours in the Sun are not coaligned with the axis of rotation suggests the presence of a latitudinal entropy gradient.

  2. Simulating deep convection with a shallow convection scheme

    Directory of Open Access Journals (Sweden)

    C. Hohenegger

    2011-10-01

    Full Text Available Convective processes profoundly affect the global water and energy balance of our planet but remain a challenge for global climate modeling. Here we develop and investigate the suitability of a unified convection scheme, capable of handling both shallow and deep convection, to simulate cases of tropical oceanic convection, mid-latitude continental convection, and maritime shallow convection. To that aim, we employ large-eddy simulations (LES as a benchmark to test and refine a unified convection scheme implemented in the Single-column Community Atmosphere Model (SCAM. Our approach is motivated by previous cloud-resolving modeling studies, which have documented the gradual transition between shallow and deep convection and its possible importance for the simulated precipitation diurnal cycle.

    Analysis of the LES reveals that differences between shallow and deep convection, regarding cloud-base properties as well as entrainment/detrainment rates, can be related to the evaporation of precipitation. Parameterizing such effects and accordingly modifying the University of Washington shallow convection scheme, it is found that the new unified scheme can represent both shallow and deep convection as well as tropical and mid-latitude continental convection. Compared to the default SCAM version, the new scheme especially improves relative humidity, cloud cover and mass flux profiles. The new unified scheme also removes the well-known too early onset and peak of convective precipitation over mid-latitude continental areas.

  3. Microwave power engineering applications

    CERN Document Server

    Okress, Ernest C

    2013-01-01

    Microwave Power Engineering, Volume 2: Applications introduces the electronics technology of microwave power and its applications. This technology emphasizes microwave electronics for direct power utilization and transmission purposes. This volume presents the accomplishments with respect to components, systems, and applications and their prevailing limitations in the light of knowledge of the microwave power technology. The applications discussed include the microwave heating and other processes of materials, which utilize the magnetron predominantly. Other applications include microwave ioni

  4. Advances in microwaves 8

    CERN Document Server

    Young, Leo

    2013-01-01

    Advances in Microwaves, Volume 8 covers the developments in the study of microwaves. The book discusses the circuit forms for microwave integrated circuits; the analysis of microstrip transmission lines; and the use of lumped elements in microwave integrated circuits. The text also describes the microwave properties of ferrimagnetic materials, as well as their interaction with electromagnetic waves propagating in bounded waveguiding structures. The integration techniques useful at high frequencies; material technology for microwave integrated circuits; specific requirements on technology for d

  5. Dry Etching

    DEFF Research Database (Denmark)

    Stamate, Eugen; Yeom, Geun Young

    2016-01-01

    Production of large-area flat panel displays (FPDs) involves several pattern transfer and device fabrication steps that can be performed with dry etching technologies. Even though the dry etching using capacitively coupled plasma is generally used to maintain high etch uniformity, due to the need...... for the higher processing rates in FPDs, high-density plasma processing tools that can handle larger-area substrate uniformly are more intensively studied especially for the dry etching of polysilicon thin films. In the case of FPD processing, the current substrate size ranges from 730 × 920 mm (fourth...... generation) to 2,200 × 2,500 mm (eighth generation), and the substrate size is expected to increase further within a few years. This chapter aims to present relevant details on dry etching including the phenomenology, materials to be etched with the different recipes, plasma sources fulfilling the dry...

  6. An Analytic Radiative-Convective Model for Planetary Atmospheres

    CERN Document Server

    Robinson, Tyler D; 10.1088/0004-637X/757/1/104

    2012-01-01

    We present an analytic 1-D radiative-convective model of the thermal structure of planetary atmospheres. Our model assumes that thermal radiative transfer is gray and can be represented by the two-stream approximation. Model atmospheres are assumed to be in hydrostatic equilibrium, with a power law scaling between the atmospheric pressure and the gray thermal optical depth. The convective portions of our models are taken to follow adiabats that account for condensation of volatiles through a scaling parameter to the dry adiabat. By combining these assumptions, we produce simple, analytic expressions that allow calculations of the atmospheric pressure-temperature profile, as well as expressions for the profiles of thermal radiative flux and convective flux. We explore the general behaviors of our model. These investigations encompass (1) worlds where atmospheric attenuation of sunlight is weak, which we show tend to have relatively high radiative-convective boundaries, (2) worlds with some attenuation of sunli...

  7. Convective formation of pileus cloud near the tropopause

    Directory of Open Access Journals (Sweden)

    T. J. Garrett

    2006-01-01

    Full Text Available Pileus clouds form where humid, vertically stratified air is mechanically displaced ahead of rising convection. This paper describes convective formation of pileus cloud in the tropopause transition layer (TTL, and explores a possible link to the formation of long-lasting cirrus at cold temperatures. The study examines in detail in-situ measurements from off the coast of Honduras during the July 2002 CRYSTAL-FACE experiment that showed an example of TTL cirrus associated with, and penetrated by, deep convection. The TTL cirrus was enriched with total water compared to its surroundings, but was composed of extremely small ice crystals with effective radii between 2 and 4 μm. Through gravity wave analysis, and intercomparison of measured and simulated cloud microphysics, it is argued that the TTL cirrus originated neither from convectively-forced gravity wave motions nor environmental mixing alone. Rather, it is hypothesized that a combination of these two processes was involved in which, first, a pulse of convection forced pileus cloud to form from TTL air; second, the pileus layer was punctured by the convective pulse and received larger ice crystals through interfacial mixing; third, the addition of this condensate inhibited evaporation of the original pileus ice crystals where a convectively forced gravity wave entered its warm phase; fourth, through successive pulses of convection, a sheet of TTL cirrus formed. While the general incidence and longevity of pileus cloud remains unknown, in-situ measurements, and satellite-based Microwave Limb Sounder retrievals, suggest that much of the tropical TTL is sufficiently humid to be susceptible to its formation. Where these clouds form and persist, there is potential for an irreversible repartition from water vapor to ice at cold temperatures.

  8. Active control of convection

    Energy Technology Data Exchange (ETDEWEB)

    Bau, H.H. [Univ. of Pennsylvania, Philadelphia, PA (United States)

    1995-12-31

    Using stability theory, numerical simulations, and in some instances experiments, it is demonstrated that the critical Rayleigh number for the bifurcation (1) from the no-motion (conduction) state to the motion state and (2) from time-independent convection to time-dependent, oscillatory convection in the thermal convection loop and Rayleigh-Benard problems can be significantly increased or decreased. This is accomplished through the use of a feedback controller effectuating small perturbations in the boundary data. The controller consists of sensors which detect deviations in the fluid`s temperature from the motionless, conductive values and then direct actuators to respond to these deviations in such a way as to suppress the naturally occurring flow instabilities. Actuators which modify the boundary`s temperature/heat flux are considered. The feedback controller can also be used to control flow patterns and generate complex dynamic behavior at relatively low Rayleigh numbers.

  9. Convective boundary layers driven by nonstationary surface heat fluxes

    NARCIS (Netherlands)

    Van Driel, R.; Jonker, H.J.J.

    2011-01-01

    In this study the response of dry convective boundary layers to nonstationary surface heat fluxes is systematically investigated. This is relevant not only during sunset and sunrise but also, for example, when clouds modulate incoming solar radiation. Because the time scale of the associated change

  10. Regulation of the climate in coupled convection-permitting simulations

    Science.gov (United States)

    Hohenegger, Cathy; Stevens, Bjorn

    2017-04-01

    The question of the regulation of the climate, in particular the existence of a stable climatic state and its basic characteristics, is investigated in this study. In contrast to previous studies, we use a convection-permitting simulation with an explicit representation of convection and of cloud cover. The grid spacing amounts to 3 km. The simulation is coupled to a slab ocean and is integrated in an idealized set-up of radiative convective equilibrium without rotation, without continent and with spatially uniform insolation. It is found that the system equilibrates at a sea surface temperature near the one of the present-day tropics. The equilibration results from the self-aggregation of convection that generates the dry and clear subtropics needed to radiate the excess heat from the system. When artificially preventing the self-aggregation, the existence of a runaway greenhouse cannot be ruled out. This is very different from what happens when performing a similar simulation at low resolution (T63) with a General Circulation Model (GCM) and parameterized cloud and convective processes. In that case, the atmosphere cools through an increase in planetary albedo arising from clouds. The total cloud radiative effect is 2.5 times larger than in the convection-permitting simulation. Perturbing the system by increasing the solar insolation also reveals a different behavior of the two simulations, with a larger warming in the convection-permitting simulation than in the GCM due to their distinct cloud feedbacks.

  11. Design and Fabrication of a Direct Natural Convection Solar Dryer for Tapioca

    OpenAIRE

    Diemuodeke E. OGHENERUONA; Momoh O.L. YUSUF

    2011-01-01

    Based on preliminary investigations under controlled conditions of drying experiments, a direct natural convection solar dryer was designed and fabricated to dry tapioca in the rural area. This paper describes the design considerations followed and presents the results of MS excel computed results of the design parameters. A minimum of 7.56 m2 solar collector area is required to dry a batch of 100 kg tapioca in 20 hours (two days drying period). The initial and final moisture content consider...

  12. Mathematical models of convection

    CERN Document Server

    Andreev, Victor K; Goncharova, Olga N; Pukhnachev, Vladislav V

    2012-01-01

    Phenomena of convection are abundant in nature as well as in industry. This volume addresses the subject of convection from the point of view of both, theory and application. While the first three chapters provide a refresher on fluid dynamics and heat transfer theory, the rest of the book describes the modern developments in theory. Thus it brings the reader to the ""front"" of the modern research. This monograph provides the theoretical foundation on a topic relevant to metallurgy, ecology, meteorology, geo-and astrophysics, aerospace industry, chemistry, crystal physics, and many other fiel

  13. Parameterizing convective organization

    Directory of Open Access Journals (Sweden)

    Brian Earle Mapes

    2011-06-01

    Full Text Available Lateral mixing parameters in buoyancy-driven deep convection schemes are among the most sensitive and important unknowns in atmosphere models. Unfortunately, there is not a true optimum value for plume mixing rate, but rather a dilemma or tradeoff: Excessive dilution of updrafts leads to unstable stratification bias in the mean state, while inadequate dilution allows deep convection to occur too easily, causing poor space and time distributions and variability. In this too-small parameter space, compromises are made based on competing metrics of model performance. We attempt to escape this “entrainment dilemma” by making bulk plume parameters (chiefly entrainment rate depend on a new prognostic variable (“organization,” org meant to reflect the rectified effects of subgrid-scale structure in meteorological fields. We test an org scheme in the Community Atmosphere Model (CAM5 with a new unified shallow-deep convection scheme (UW-ens, a 2-plume version of the University of Washington scheme. Since buoyant ascent involves natural selection, subgrid structure makes convection systematically deeper and stronger than the pure unorganized case: plumes of average (or randomly sampled air rising in the average environment. To reflect this, org is nonnegative, but we leave it dimensionless. A time scale characterizes its behavior (here ∼3 h for a 2o model. Currently its source is rain evaporation, but other sources can be added easily. We also let org be horizontally transported by advection, as a mass-weighted mean over the convecting layer. Linear coefficients link org to a plume ensemble, which it assists via: 1 plume base warmth above the mean temperature 2 plume radius enhancement (reduced mixing, and 3 increased probability of overlap in a multi-plume scheme, where interactions benefit later generations (this part has only been implemented in an offline toy column model. Since rain evaporation is a source for org, it functions as a time

  14. CDM Convective Forecast Planning guidance

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The CDM Convective Forecast Planning (CCFP) guidance product provides a foreast of en-route aviation convective hazards. The forecasts are updated every 2 hours and...

  15. The Gravimetric Analysis of Nickel Using a Microwave Oven

    Science.gov (United States)

    Carmosini, Nadia; Ghoreshy, Sanaz; Koether, Marina C.

    1997-08-01

    The procedure for the gravimetric quantitative analysis of the percent of nickel in steel has been modified to include the use of a microwave oven. Experiments performed with the microwave oven gave an average recovery of 99.9+0.3% whereas the conventional method gave a value of 99.5+0.6%. The Ni(DMG)2 samples, which were digested and dried in the microwave oven, showed no physical difference indicating that there was no chemical modification of the precipitate due to the microwave radiation. The microwave oven proved to be very useful for time efficiency, not only for the digestion and heating of the steel ore, but also for the drying of the ore, the crucibles, and the Ni(DMG)2 precipitate. The most significant advantages occur with the cooling time. However, it is not suggested that the entire experiment be performed with the microwave since constant attention, which is required with the microwave drying method, is not necessary for the conventional oven method. Therefore, in order to be more time effective, thought should be given as to which part of the method should be performed with the microwave and which should be performed with the conventional oven.

  16. Internal Wave Generation by Convection

    OpenAIRE

    Lecoanet, Daniel

    2016-01-01

    In nature, it is not unusual to find stably stratified fluid adjacent to convectively unstable fluid. This can occur in the Earth's atmosphere, where the troposphere is convective and the stratosphere is stably stratified; in lakes, where surface solar heating can drive convection above stably stratified fresh water; in the oceans, where geothermal heating can drive convection near the ocean floor, but the water above is stably stratified due to salinity gradients; possible in the Earth's liq...

  17. Drying of healthy foods : from mechanism to optimization

    NARCIS (Netherlands)

    Jin, X.

    2013-01-01

    Convective drying is an effective post-harvest method to the extend shelf life of vegetables and to reduce the mass for transportation. The heat load during drying, however, affects the quality attributes negatively. Today, consumers in the industrialized world pay a raised attention on food

  18. Drying of healthy foods : from mechanism to optimization

    NARCIS (Netherlands)

    Jin, X.

    2013-01-01

    Convective drying is an effective post-harvest method to the extend shelf life of vegetables and to reduce the mass for transportation. The heat load during drying, however, affects the quality attributes negatively. Today, consumers in the industrialized world pay a raised attention on food quality

  19. An analytical method for determining the temperature dependent moisture diffusivities of pumpkin seeds during drying process

    Energy Technology Data Exchange (ETDEWEB)

    Can, Ahmet [Department of Mechanical Engineering, University of Trakya, 22030 Edirne (Turkey)

    2007-02-15

    This paper presents an analytical method, which determines the moisture diffusion coefficients for the natural and forced convection hot air drying of pumpkin seeds and their temperature dependence. In order to obtain scientific data, the pumpkin seed drying process was investigated under both natural and forced hot air convection regimes. This paper presents the experimental results in which the drying air was heated by solar energy. (author)

  20. century drying

    Science.gov (United States)

    Cook, Benjamin I.; Smerdon, Jason E.; Seager, Richard; Coats, Sloan

    2014-11-01

    Global warming is expected to increase the frequency and intensity of droughts in the twenty-first century, but the relative contributions from changes in moisture supply (precipitation) versus evaporative demand (potential evapotranspiration; PET) have not been comprehensively assessed. Using output from a suite of general circulation model (GCM) simulations from phase 5 of the Coupled Model Intercomparison Project, projected twenty-first century drying and wetting trends are investigated using two offline indices of surface moisture balance: the Palmer Drought Severity Index (PDSI) and the Standardized Precipitation Evapotranspiration Index (SPEI). PDSI and SPEI projections using precipitation and Penman-Monteith based PET changes from the GCMs generally agree, showing robust cross-model drying in western North America, Central America, the Mediterranean, southern Africa, and the Amazon and robust wetting occurring in the Northern Hemisphere high latitudes and east Africa (PDSI only). The SPEI is more sensitive to PET changes than the PDSI, especially in arid regions such as the Sahara and Middle East. Regional drying and wetting patterns largely mirror the spatially heterogeneous response of precipitation in the models, although drying in the PDSI and SPEI calculations extends beyond the regions of reduced precipitation. This expansion of drying areas is attributed to globally widespread increases in PET, caused by increases in surface net radiation and the vapor pressure deficit. Increased PET not only intensifies drying in areas where precipitation is already reduced, it also drives areas into drought that would otherwise experience little drying or even wetting from precipitation trends alone. This PET amplification effect is largest in the Northern Hemisphere mid-latitudes, and is especially pronounced in western North America, Europe, and southeast China. Compared to PDSI projections using precipitation changes only, the projections incorporating both

  1. Optimization of resistant starch formation from high amylose corn starch by microwave irradiation treatments and characterization of starch preparations.

    Science.gov (United States)

    Mutlu, Selime; Kahraman, Kevser; Öztürk, Serpil

    2017-02-01

    The effects of microwave irradiation on resistant starch (RS) formation and functional properties in high-amylose corn starch, Hylon VII, by applying microwave-storing cycles and drying processes were investigated. The Response Surface Methodology (RSM) was used to optimize the reaction conditions, microwave time (2-4min) and power (20-100%), for RS formation. The starch:water (1:10) mixtures were cooked and autoclaved and then different microwave-storing cycles and drying (oven or freeze drying) processes were applied. The RS contents of the samples increased with increasing microwave-storing cycle. The highest RS (43.4%) was obtained by oven drying after 3 cycles of microwave treatment at 20% power for 2min. The F, p (oven-dried samples applied by 1 and 3 cycles of microwave with regression coefficients of 0.65 and 0.62, respectively. Quadratic equation was obtained for freeze-dried samples applied by 3 cycles of microwave with a regression coefficient of 0.83. The solubility, water binding capacity (WBC) and RVA viscosity values of the microwave applied samples were higher than those of native Hylon VII. The WBC and viscosity values of the freeze-dried samples were higher than those of the oven-dried ones.

  2. Effect on the load size on the efficiency of microwave heating under stop flow and continuous flow conditions

    NARCIS (Netherlands)

    Patil, N.G.; Rebrov, E.V.; Esveld, D.C.; Eränen, K.; Benaskar, F.; Meuldijk, Jan; Mikkola, J.P.; Hessel, V.; Hulshof, L.A.; Murzin, D.Y.; Schouten, J.C.

    2012-01-01

    A novel heating efficiency analysis of the microwave heated stop-flow (i.e. stagnant
    liquid) and continuous-flow reactors has been presented. The thermal losses to the surrounding
    air by natural convection have been taken into account for heating efficiency calculation of
    the microwave

  3. Effect on the load size on the efficiency of microwave heating under stop flow and continuous flow conditions

    NARCIS (Netherlands)

    Patil, N.G.; Rebrov, E.V.; Esveld, D.C.; Eränen, K.; Benaskar, F.; Meuldijk, Jan; Mikkola, J.P.; Hessel, V.; Hulshof, L.A.; Murzin, D.Y.; Schouten, J.C.

    2012-01-01

    A novel heating efficiency analysis of the microwave heated stop-flow (i.e. stagnant
    liquid) and continuous-flow reactors has been presented. The thermal losses to the surrounding
    air by natural convection have been taken into account for heating efficiency calculation of
    the microwave h

  4. Thin layer modelling of Gelidium sesquipedale solar drying process

    Energy Technology Data Exchange (ETDEWEB)

    Ait Mohamed, L. [Laboratoire d' Energie Solaire et des Plantes Aromatiques et Medicinales, Ecole Normale Superieure, BP 2400, Marrakech (Morocco); Faculte des Sciences Semlalia, BP 2390, Marrakech (Morocco); Ethmane Kane, C.S. [Faculte des Sciences de Tetouan, BP 2121, Tetouan (Morocco); Kouhila, M.; Jamali, A. [Laboratoire d' Energie Solaire et des Plantes Aromatiques et Medicinales, Ecole Normale Superieure, BP 2400, Marrakech (Morocco); Mahrouz, M. [Faculte des Sciences Semlalia, BP 2390, Marrakech (Morocco); Kechaou, N. [Ecole Nationale d' Ingenieurs de Sfax, BPW 3038 (Tunisia)

    2008-05-15

    The effect of air temperature and air flow rate on the drying kinetics of Gelidium sesquipedale was investigated in convective solar drying. Drying was conducted at 40, 50 and 60 C. The relative humidity was varied from 50% to 57%, and the drying air flow rate was varied from 0.0277 to 0.0833 m{sup 3}/s. The expression for the drying rate equation is determined empirically from the characteristic drying curve. Thirteen mathematical models of thin layer drying are selected in order to estimate the suitable model for describing the drying curves. The two term model gives the best prediction of the drying curves and satisfactorily describes the drying characteristics of G. sesquipedale with a correlation coefficient R of 0.9999 and chi-square ({chi}{sup 2}) of 3.381 x 10{sup -6}. (author)

  5. Coupling between lower-tropospheric convective mixing and low-level clouds: Physical mechanisms and dependence on convection scheme.

    Science.gov (United States)

    Vial, Jessica; Bony, Sandrine; Dufresne, Jean-Louis; Roehrig, Romain

    2016-12-01

    Several studies have pointed out the dependence of low-cloud feedbacks on the strength of the lower-tropospheric convective mixing. By analyzing a series of single-column model experiments run by a climate model using two different convective parametrizations, this study elucidates the physical mechanisms through which marine boundary-layer clouds depend on this mixing in the present-day climate and under surface warming. An increased lower-tropospheric convective mixing leads to a reduction of low-cloud fraction. However, the rate of decrease strongly depends on how the surface latent heat flux couples to the convective mixing and to boundary-layer cloud radiative effects: (i) on the one hand, the latent heat flux is enhanced by the lower-tropospheric drying induced by the convective mixing, which damps the reduction of the low-cloud fraction, (ii) on the other hand, the latent heat flux is reduced as the lower troposphere stabilizes under the effect of reduced low-cloud radiative cooling, which enhances the reduction of the low-cloud fraction. The relative importance of these two different processes depends on the closure of the convective parameterization. The convective scheme that favors the coupling between latent heat flux and low-cloud radiative cooling exhibits a stronger sensitivity of low-clouds to convective mixing in the present-day climate, and a stronger low-cloud feedback in response to surface warming. In this model, the low-cloud feedback is stronger when the present-day convective mixing is weaker and when present-day clouds are shallower and more radiatively active. The implications of these insights for constraining the strength of low-cloud feedbacks observationally is discussed.

  6. Practical microwave electron devices

    CERN Document Server

    Meurant, Gerard

    2013-01-01

    Practical Microwave Electron Devices provides an understanding of microwave electron devices and their applications. All areas of microwave electron devices are covered. These include microwave solid-state devices, including popular microwave transistors and both passive and active diodes; quantum electron devices; thermionic devices (including relativistic thermionic devices); and ferrimagnetic electron devices. The design of each of these devices is discussed as well as their applications, including oscillation, amplification, switching, modulation, demodulation, and parametric interactions.

  7. Use of microwave in processing of drug delivery systems.

    Science.gov (United States)

    Wong, T W

    2008-04-01

    Microwave has received a widespread application in pharmaceuticals and food processing, microbial sterilization, biomedical therapy, scientific and biomedical analysis, as well as, drug synthesis. This paper reviews the basis of application of microwave to prepare pharmaceutical dosage forms such as agglomerates, gel beads, microspheres, nanomatrix, solid dispersion, tablets and film coat. The microwave could induce drying, polymeric crosslinkages as well as drug-polymer interaction, and modify the structure of drug crystallites via its effects of heating and/or electromagnetic field on the dosage forms. The use of microwave opens a new approach to control the physicochemical properties and drug delivery profiles of pharmaceutical dosage forms without the need for excessive heat, lengthy process or toxic reactants. Alternatively, the microwave can be utilized to process excipients prior to their use in the formulation of drug delivery systems. The intended release characteristics of drugs in dosage forms can be met through modifying the physicochemical properties of excipients using the microwave.

  8. Rapid and Decentralized Human Waste Treatment by Microwave Radiation.

    Science.gov (United States)

    Nguyen, Tu Anh; Babel, Sandhya; Boonyarattanakalin, Siwarutt; Koottatep, Thammarat

    2016-09-07

    This study evaluates the technical feasibility of using microwave radiation for the rapid treatment of human feces. Human feces of 1000 g were radiated with a commercially available household microwave oven (with rotation) at different exposure time lengths (30, 50, 60, 70, and 75 minutes) and powers (600, 800, and 1000 W). Volume reduction over 90% occurred after 1000 W microwave radiation for 75 minutes. Pathogen eradiation performances of six log units or more at a high range of microwave powers were achieved. Treatments with the same energy input of 1000 Wh, but at lower powers with prolonged exposure times, significantly enhanced moisture removal and volume reduction. Microwave radiation caused carbonization and resulted in a more stable end product. The energy content of the samples after microwave treatment at 1000 W and 75 minutes is 3517 ± 8.85 calories/g of dried sample, and the product can also be used as compost.

  9. Dry cell battery poisoning

    Science.gov (United States)

    Batteries - dry cell ... Acidic dry cell batteries contain: Manganese dioxide Ammonium chloride Alkaline dry cell batteries contain: Sodium hydroxide Potassium hydroxide Lithium dioxide dry cell batteries ...

  10. A Convective Vorticity Vector Associated With Tropical Convection: A 2D Cloud-Resolving Modeling Study

    Science.gov (United States)

    Gao, Shou-Ting; Ping, Fan; Li, Xiao-Fan; Tao, Wei-Kuo

    2004-01-01

    Although dry/moist potential vorticity is a useful physical quantity for meteorological analysis, it cannot be applied to the analysis of 2D simulations. A convective vorticity vector (CVV) is introduced in this study to analyze 2D cloud-resolving simulation data associated with 2D tropical convection. The cloud model is forced by the vertical velocity, zonal wind, horizontal advection, and sea surface temperature obtained from the TOGA COARE, and is integrated for a selected 10-day period. The CVV has zonal and vertical components in the 2D x-z frame. Analysis of zonally-averaged and mass-integrated quantities shows that the correlation coefficient between the vertical component of the CVV and the sum of the cloud hydrometeor mixing ratios is 0.81, whereas the correlation coefficient between the zonal component and the sum of the mixing ratios is only 0.18. This indicates that the vertical component of the CVV is closely associated with tropical convection. The tendency equation for the vertical component of the CVV is derived and the zonally-averaged and mass-integrated tendency budgets are analyzed. The tendency of the vertical component of the CVV is determined by the interaction between the vorticity and the zonal gradient of cloud heating. The results demonstrate that the vertical component of the CVV is a cloud-linked parameter and can be used to study tropical convection.

  11. Physical properties of sunflower grains after drying

    Directory of Open Access Journals (Sweden)

    Paulo Carteri Coradi

    2015-12-01

    Full Text Available The knowledge of the physical properties of the grains is important for the optimization of post-harvest operations. This study aimed to evaluate the effects of convective drying with different air temperatures (45, 55, 65 and 75 °C the physical properties of sunflower seeds. The drying sunflower grains was performed in convection oven with forced air. In natural conditions, samples of 5 kg of pellets were used for each repetition drying. During the drying process, the grains samples were weighed periodically until they reach 10% (wet basis, w.b., then were subjected to evaluations of physical properties. According to the results it was observed that the porosity, apparent density, thousand kernel weight to the drag coefficient, roundness, sphericity and width of sunflower seed did not change with increasing temperature drying air. It was concluded that the drying air temperatures of 45 °C and 55 retained the initial physical characteristics of sunflower seeds. The temperature of the drying air of 75 °C had greater influence on changes in volumetric shrinkage of the grains.

  12. Natural convection heat transfer within horizontal spent nuclear fuel assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Canaan, R.E.

    1995-12-01

    Natural convection heat transfer is experimentally investigated in an enclosed horizontal rod bundle, which characterizes a spent nuclear fuel assembly during dry storage and/or transport conditions. The basic test section consists of a square array of sixty-four stainless steel tubular heaters enclosed within a water-cooled rectangular copper heat exchanger. The heaters are supplied with a uniform power generation per unit length while the surrounding enclosure is maintained at a uniform temperature. The test section resides within a vacuum/pressure chamber in order to subject the assembly to a range of pressure statepoints and various backfill gases. The objective of this experimental study is to obtain convection correlations which can be used in order to easily incorporate convective effects into analytical models of horizontal spent fuel systems, and also to investigate the physical nature of natural convection in enclosed horizontal rod bundles in general. The resulting data consist of: (1) measured temperatures within the assembly as a function of power, pressure, and backfill gas; (2) the relative radiative contribution for the range of observed temperatures; (3) correlations of convective Nusselt number and Rayleigh number for the rod bundle as a whole; and (4) correlations of convective Nusselt number as a function of Rayleigh number for individual rods within the array.

  13. Convection heat transfer

    CERN Document Server

    Bejan, Adrian

    2013-01-01

    Written by an internationally recognized authority on heat transfer and thermodynamics, this second edition of Convection Heat Transfer contains new and updated problems and examples reflecting real-world research and applications, including heat exchanger design. Teaching not only structure but also technique, the book begins with the simplest problem solving method (scale analysis), and moves on to progressively more advanced and exact methods (integral method, self similarity, asymptotic behavior). A solutions manual is available for all problems and exercises.

  14. Relationships between evaprorative fraction and remotely sensed vegetation index and microwave brightness temperature for semiarid rangelands

    Science.gov (United States)

    Kustas, W. P.; Schimugge, T. J.; Humes, K. S.; Jackson, T. J.; Parry, R.; Weltz, M. A.; Moran, M. S.

    1993-01-01

    Measurements of the microwave brightness temperature (TB) with the Pushbroom Microwave Radiometer (PBMR) over the Walnut Gulch Experiment Watershed were made on selected days during the MONSOON 90 field campaign. The PBMR is an L-band instrument (21-cm wavelength) that can provide estimates of near-surface soil moisture over a variety of surfaces. Aircraft observations in the visible and near-infrared wavelengths collected on selected days also were used to compute a vegetation index. Continuous micrometeorological measurements and daily soil moisture samples were obtained at eight locations during experimental period. Two sites were instrumented with time domain reflectometry probes to monitor the soil moisture profile. The fraction of available energy used for evapotranspiration was computed by taking the ratio of latent heat flux (LE) to the sum of net radiation (Rn) and soil heat flux (G). This ratio is commonly called the evaporative fraction (EF) and normally varies between 0 and 1 under daytime convective conditions with minimal advection. A wide range of environmental conditions existed during the field campaign, resulting in average EF values for the study area varying from 0.4 to 0.8 and values of TB ranging from 220 to 280 K. Comparison between measured TB and EF for the eight locations showed an inverse relationship. Other days were included in the analysis by estimating TB with the soil moisture data. Because transpiration from the vegetation is more strongly coupled to root zone soil moisture, significant scatter in this relationship existed at high values of TB or dry near-surface soil moisture conditions. The variation in EF under dry near-surface soil moisture conditions was correlated to the amount of vegetation cover estimated with a remotely sensed vegetation index. These findings indicate that information obtained from optical and microwave data can be used for quantifying the energy balance of semiarid areas. The microwave data can indicate

  15. Relationships between Evaporative Fraction and Remotely Sensed Vegetation Index and Microwave Brightness Temperature for Semiarid Rangelands.

    Science.gov (United States)

    Kustas, W. P.; Schmugge, T. J.; Humes, K. S.; Jackson, T. J.; Parry, R.; Weltz, M. A.; Moran, M. S.

    1993-12-01

    Measurements of the microwave brightness temperature (TB) with the Pushbroom Microwave Radiometer (PBMR) over the Walnut Gulch Experimental Watershed were made on selected days during the MONSOON 90 field campaign. The PBMR is an L-band instrument (21-cm wavelength) that can provide estimates of near-surface soil moisture over a variety of surfaces. Aircraft observations in the visible and near-infrared wavelengths collected on selected days also were used to compute a vegetation index. Continuous micrometeorological measurements and daily soil moisture samples were obtained at eight locations during the experimental period. Two sites were instrumented with time domain reflectometry probes to monitor the soil moisture profile. The fraction of available energy used for evapotranspiration was computed by taking the ratio of latent heat flux (LE) to the sum of net radiation (Rn) and soil heat flux (G). This ratio is commonly called the evaporative fraction (EF) and normally varies between 0 and 1 under daytime convective conditions with minimal advection. A wide range of environmental conditions existed during the field campaign, resulting in average EF values for the study area varying from 0.4 to 0.8 and values of TB ranging from 220 to 280 K. Comparison between measured TB and EF for the eight locations showed an inverse relationship with a significant correlation (r2 = 0.69). Other days were included in the analysis by estimating TB with the soil moisture data. Because transpiration from the vegetation is more strongly coupled to root zone soil moisture, significant scatter in this relationship existed at high values of TB or dry near-surface soil moisture conditions. It caused a substantial reduction in the correlation with r2 = 0.40 or only 40% of the variation in EF being explained by TB. The variation in EF under dry near-surface soil moisture conditions was correlated to the amount of vegetation cover estimated with a remotely sensed vegetation index. These

  16. The Solar Convection Spectrum

    Science.gov (United States)

    Bachmann, Kurt T.

    2000-01-01

    I helped to complete a research project with NASA scientists Dr. David Hathaway (my mentor), Rick Bogart, and John Beck from the SOHO/SOI collaboration. Our published paper in 'Solar Physics' was titled 'The Solar Convection Spectrum' (April 2000). Two of my undergraduate students were named on the paper--Gavrav Khutri and Josh Petitto. Gavrav also wrote a short paper for the National Conference of Undergraduate Research Proceedings in 1998 using a preliminary result. Our main result was that we show no evidence of a scale of convection named 'mesogranulation'. Instead, we see only direct evidence for the well-known scales of convection known as graduation and supergranulation. We are also completing work on vertical versus horizontal flow fluxes at the solar surface. I continue to work on phase relationships of solar activity indicators, but I have not yet written a paper with my students on this topic. Along with my research results, I have developed and augmented undergraduate courses at Birmingham-Southern College by myself and with other faculty. We have included new labs and observations, speakers from NASA and elsewhere, new subject material related to NASA and space science. I have done a great deal of work in outreach, mostly as President and other offices in the Birmingham Astronomical Society. My work includes speaking, attracting speakers, giving workshops, and governing.

  17. Thermal Vibrational Convection

    Science.gov (United States)

    Gershuni, G. Z.; Lyubimov, D. V.

    1998-08-01

    Recent increasing awareness of the ways in which vibrational effects can affect low-gravity experiments have renewed interest in the study of thermal vibrational convection across a wide range of fields. For example, in applications where vibrational effects are used to provide active control of heat and mass transfer, such as in heat exchangers, stirrers, mineral separators and crystal growth, a sound understanding of the fundamental theory is required. In Thermal Vibrational Convection, the authors present the theory of vibrational effects caused by a static gravity field, and of fluid flows which appear under vibration in fluid-filled cavities. The first part of the book discusses fluid-filled cavities where the fluid motion only appears in the presence of temperature non-uniformities, while the second considers those situations where the vibrational effects are caused by a non-uniform field. Throughout, the authors concentrate on consideration of high frequency vibrations, where averaging methods can be successfully applied in the study of the phenomena. Written by two of the pioneers in this field, Thermal Vibrational Convection will be of great interest to scientists and engineers working in the many areas that are concerned with vibration, and its effect on heat and mass transfer. These include hydrodynamics, hydro-mechanics, low gravity physics and mechanics, and geophysics. The rigorous approach adopted in presenting the theory of this fascinating and highly topical area will facilitate a greater understanding of the phenomena involved, and will lead to the development of more and better-designed experiments.

  18. Lightning-based propagation of convective rain fields

    Directory of Open Access Journals (Sweden)

    S. Dietrich

    2011-05-01

    Full Text Available This paper describes a new multi-sensor approach for continuously monitoring convective rain cells. It exploits lightning data from surface networks to propagate rain fields estimated from multi-frequency brightness temperature measurements taken by the AMSU/MHS microwave radiometers onboard NOAA/EUMETSAT low Earth orbiting operational satellites. Specifically, the method allows inferring the development (movement, morphology and intensity of convective rain cells from the spatial and temporal distribution of lightning strokes following any observation by a satellite-borne microwave radiometer. Obviously, this is particularly attractive for real-time operational purposes, due to the sporadic nature of the low Earth orbiting satellite measurements and the continuous availability of ground-based lightning measurements – as is the case in most of the Mediterranean region. A preliminary assessment of the lightning-based rainfall propagation algorithm has been successfully made by using two pairs of consecutive AMSU observations, in conjunction with lightning measurements from the ZEUS network, for two convective events. Specifically, we show that the evolving rain fields, which are estimated by applying the algorithm to the satellite-based rainfall estimates for the first AMSU overpass, show an overall agreement with the satellite-based rainfall estimates for the second AMSU overpass.

  19. A Numerical Investigation of a Slow-Moving Convective Line in a Weakly Sheared Environment

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    A series of three-dimensional, cloud-resolving numerical simulations are performed to examine a slowpropagating, quasi-two-dimensional convective system in a weakly sheared environment during the Tropical Rainfall Measuring Mission Large-Scale Biosphere-Atmosphere (TRMM-LBA) field campaign. The focus is on the kinematics and thermodynamics, organization mechanisms, and dynamical effects of low-level shear, ice microphysics and tropospheric humidity. The control simulation, which is initialized with the observed sounding and includes full microphysics, successfully replicates many observed features of the convective system, such as the linear structure, spatial orientation, life cycle, and sluggish translation.The system at the mature stage displays a line-normal structure similar to that associated with squalltype convective systems, but the corresponding mesoscale circulation and thermodynamic modification are much weaker. Ice-phase microphysical processes are not necessary to the formation of the convective system, but they play a non-trivial role in the late evolution stage. In contrast, the low-level shear, albeit shallow and weak, is critical to the realistic realization of the convective line. The tropospheric moisture above the planetary boundary layer has an important impact on the behavior of convective organization.In particular, a dry layer in the lower troposphere significantly suppresses convective development and inhibits the generation of organized convection even though the convective available potential energy is substantial. The free-atmosphere humidity has received little attention in previous studies of organized convection and warrants further investigation.

  20. Dry Mouth

    Science.gov (United States)

    ... Use a fluoride rinse or brush-on fluoride gel before bedtime. See your dentist at least twice yearly to have your teeth examined and plaque removed, to help prevent tooth decay. Several herbal remedies have been used historically to treat dry ...

  1. Antioxidant capacity of frozen pleurotus ostreatus during convective drying

    OpenAIRE

    2016-01-01

    Se estudió la influencia de las condiciones de deshidratación sobre el poder antirradi-calario, fenoles totales, flavonoides, y color superficial de basidiocarpos congelados de Pleurotus ostreatus. El secado se efectuó en equipo experimental, con una velocidad de aire de 2 m/s, 5% de humedad relativa, y distintas temperaturas (50 C, 60 C, 70 C). La determinación del contenido de fenoles totales se realizó de acuerdo al método de Folin-Ciocalteau, flavonoides por la formación de complejo con A...

  2. Experimental investigation on the comparison of fenugreek drying in an indirect solar dryer and under open sun

    Science.gov (United States)

    Shrivastava, Vipin; Kumar, Anil

    2016-09-01

    The convective heat transfer coefficient is an essential parameter for designing of any solar drying system. In this paper heat transfer modeling in term of convective heat transfer coefficient is performed and compared with open sun drying. The data obtained from experimentation under open sun and indirect solar drying conditions have been used to find values of the experimental constant `C' and exponent `n' by regression analysis and, consequently, convective heat transfer coefficient. From this study it is concluded that the convective heat transfer coefficient is decreasing with drying time it is due to decrease in moisture content. Results also showed that convective heat transfer coefficients are more in indirect solar dryer system than under open sun drying.

  3. Numerical study on hygroscopic material drying in packed bed

    Directory of Open Access Journals (Sweden)

    M. Stakić

    2011-06-01

    Full Text Available The paper addresses numerical simulation for the case of convective drying of hygroscopic material in a packed bed, analyzing agreement between the simulated and the corresponding experimental results. In the simulation model of unsteady simultaneous one-dimensional heat and mass transfer between gas phase and dried material, it is assumed that the gas-solid interface is at thermodynamic equilibrium, while the drying rate of the specific product is calculated by applying the concept of a "drying coefficient". Model validation was done on the basis of the experimental data obtained with potato cubes. The obtained drying kinetics, both experimental and numerical, show that higher gas (drying agent velocities (flow-rates, as well as lower equivalent grain diameters, induce faster drying. This effect is more pronounced for deeper beds, because of the larger amount of wet material to be dried using the same drying agent capacity.

  4. Thin-Layer Drying Characteristics and Modeling of Chinese Jujubes

    Directory of Open Access Journals (Sweden)

    Xiao-Kang Yi

    2012-01-01

    Full Text Available A mathematical modeling of thin-layer drying of jujubes in a convective dryer was established under controlled conditions of temperature and velocity. The drying process took place both in the accelerating rate and falling rate period. We observed that higher temperature reduced the drying time, indicating higher drying rates of jujubes. The experimental drying data of jujubes were used to fit ten different thin-layer models, then drying rate constants and coefficients of models tested were determined by nonlinear regression analysis using the Statistical Computer Program. As for all the drying models, the Weibull distribution model was superior and best predicted the experimental values. Therefore, this model can be used to facilitate dryer design and promote efficient dryer operation by simulation and optimization of the drying processes. The volumetric shrinkable coefficient of jujubes decreased as the drying air temperature increased.

  5. Development of Solar Drying Model for Selected Cambodian Fish Species

    OpenAIRE

    Anna Hubackova; Iva Kucerova; Rithy Chrun; Petra Chaloupkova; Jan Banout

    2014-01-01

    A solar drying was investigated as one of perspective techniques for fish processing in Cambodia. The solar drying was compared to conventional drying in electric oven. Five typical Cambodian fish species were selected for this study. Mean solar drying temperature and drying air relative humidity were 55.6°C and 19.9%, respectively. The overall solar dryer efficiency was 12.37%, which is typical for natural convection solar dryers. An average evaporative capacity of solar dryer was 0.049 kg·h...

  6. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Causes of Dry Eye Dry Eye Treatment What Is Dry Eye? Written By: Kierstan Boyd Reviewed By: ... your eyes do not produce enough tears, it is called dry eye. Dry eye is also when ...

  7. Emerging Trends in Microwave Processing of Spices and Herbs.

    Science.gov (United States)

    Rahath Kubra, Ismail; Kumar, Devender; Jagan Mohan Rao, Lingamallu

    2016-10-02

    Today, spices are integral part of our food as they provide sensory attributes such as aroma, color, flavour and taste to food. Further their antimicrobial, antioxidant, pharmaceutical and nutritional properties are also well known. Since spices are seasonal so their availability can be extended year round by adopting different preservation techniques. Drying and extraction are most important methods for preservation and value addition to spices. There are different techniques for drying of spices with their own advantages and limitations. A novel, non-conventional technique for drying of spices is use of microwave radiation. This technique proved to be very rapid, and also provide a good quality product. Similarly, there are a number of non-conventional extraction methods in use that are all, in principle, solid-liquid extractions but which introduce some form of additional energy to the process in order to facilitate the transfer of analytes from sample to solvent. This paper reviews latest advances in the use of microwave energy for drying of spices and herbs. Also, the review describes the potential application of microwave energy for extraction of essential oil/bioactive components from spices and herbs and the advantages of microwave-assisted process over the other extraction processes generally employed for extraction. It also showcases some recent research results on microwave drying/extraction from spices and herbs.

  8. Improvement of water transport mechanisms during potato drying by applying ultrasound.

    Science.gov (United States)

    Ozuna, César; Cárcel, Juan A; García-Pérez, José V; Mulet, Antonio

    2011-11-01

    The drying rate of vegetables is limited by internal moisture diffusion and convective transport mechanisms. The increase of drying air temperature leads to faster water mobility; however, it provokes quality loss in the product and presents a higher energy demand. Therefore, the search for new strategies to improve water mobility during convective drying constitutes a topic of relevant research. The aim of this work was to evaluate the use of power ultrasound to improve convective drying of potato and quantify the influence of the applied power in the water transport mechanisms. Drying kinetics of potato cubes were increased by the ultrasonic application. The influence of power ultrasound was dependent on the ultrasonic power (from 0 to 37 kW m(-3) ), the higher the applied power, the faster the drying kinetic. The diffusion model considering external resistance to mass transfer provided a good fit of drying kinetics. From modelling, it was observed a proportional and significant (P diffusivity and mass transfer coefficient. The ultrasonic application during drying represents an interesting alternative to traditional convective drying by shortening drying time, which may involve an energy saving concerning industrial applications. In addition, the ultrasonic effect in the water transport is based on mechanical phenomena with a low heating capacity, which is highly relevant for drying heat sensitive materials and also for obtaining high-quality dry products. Copyright © 2011 Society of Chemical Industry.

  9. Effects of Drying Methods on the Drying Kinetics and the Essential Oil of Lippia multiflora Moldenke Leaves

    Directory of Open Access Journals (Sweden)

    Raymond G. Elenga

    2011-10-01

    Full Text Available Lippia multiflora is widespread in Africa and America. Its leaves are consumed as tea and have various medicinal properties. To preserve the flavour and properties, the farmers dry the leaves in shade for six to ten days. The aim of this work on one hand, is to check the soundness of this traditional drying method by comparing its effects with those of the forced convective drying at 40, 45, 50, 55 and 60ºC on the drying kinetics, the composition and content of the Essential Oil (EO of dried leaves. On the other hand, to test the agreement of drying curves with the Page model, the Peleg model and the diffusional model. The drying duration passes from 7 days for shade-drying to 3 h for convective drying at 60ºC, while the composition and the content of EO do not vary significantly. The three models simulate well the drying kinetics nevertheless the Page one is the best. Analysed in the framework of Avrami law, its constant values are in agreement with the unidirectional diffusion. The activation energy obtained from the Peleg model (47.8 kJ/mol is almost equal to that deducted from the diffusional model (46.3 kJ/mol. The drying of lippia leaves between 45 and 55ºC reduces significantly the drying length without degrading the EO. The results obtained from the three models turn out coherent.

  10. Titan Balloon Convection Model Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This innovative research effort is directed at determining, quantitatively, the convective heat transfer coefficients applicable to a Montgolfiere balloon operating...

  11. Bidispersive-inclined convection

    Science.gov (United States)

    Mulone, Giuseppe; Straughan, Brian

    2016-01-01

    A model is presented for thermal convection in an inclined layer of porous material when the medium has a bidispersive structure. Thus, there are the usual macropores which are full of a fluid, but there are also a system of micropores full of the same fluid. The model we employ is a modification of the one proposed by Nield & Kuznetsov (2006 Int. J. Heat Mass Transf. 49, 3068–3074. (doi:10.1016/j.ijheatmasstransfer.2006.02.008)), although we consider a single temperature field only. PMID:27616934

  12. Zoned mantle convection.

    Science.gov (United States)

    Albarède, Francis; Van Der Hilst, Rob D

    2002-11-15

    We review the present state of our understanding of mantle convection with respect to geochemical and geophysical evidence and we suggest a model for mantle convection and its evolution over the Earth's history that can reconcile this evidence. Whole-mantle convection, even with material segregated within the D" region just above the core-mantle boundary, is incompatible with the budget of argon and helium and with the inventory of heat sources required by the thermal evolution of the Earth. We show that the deep-mantle composition in lithophilic incompatible elements is inconsistent with the storage of old plates of ordinary oceanic lithosphere, i.e. with the concept of a plate graveyard. Isotopic inventories indicate that the deep-mantle composition is not correctly accounted for by continental debris, primitive material or subducted slabs containing normal oceanic crust. Seismological observations have begun to hint at compositional heterogeneity in the bottom 1000 km or so of the mantle, but there is no compelling evidence in support of an interface between deep and shallow mantle at mid-depth. We suggest that in a system of thermochemical convection, lithospheric plates subduct to a depth that depends - in a complicated fashion - on their composition and thermal structure. The thermal structure of the sinking plates is primarily determined by the direction and rate of convergence, the age of the lithosphere at the trench, the sinking rate and the variation of these parameters over time (i.e. plate-tectonic history) and is not the same for all subduction systems. The sinking rate in the mantle is determined by a combination of thermal (negative) and compositional buoyancy and as regards the latter we consider in particular the effect of the loading of plates with basaltic plateaux produced by plume heads. Barren oceanic plates are relatively buoyant and may be recycled preferentially in the shallow mantle. Oceanic plateau-laden plates have a more pronounced

  13. Microwave Breast Imaging Techniques

    DEFF Research Database (Denmark)

    Zhurbenko, Vitaliy; Rubæk, Tonny

    2010-01-01

    This paper outlines the applicability of microwave radiation for breast cancer detection. Microwave imaging systems are categorized based on their hardware architecture. The advantages and disadvantages of various imaging techniques are discussed. The fundamental tradeoffs are indicated between v...

  14. Microwave Breast Imaging Techniques

    DEFF Research Database (Denmark)

    Zhurbenko, Vitaliy; Rubæk, Tonny

    2010-01-01

    This paper outlines the applicability of microwave radiation for breast cancer detection. Microwave imaging systems are categorized based on their hardware architecture. The advantages and disadvantages of various imaging techniques are discussed. The fundamental tradeoffs are indicated between...

  15. Application of microwave energy in the manufacture of enhanced-quality green tea.

    Science.gov (United States)

    Gulati, Ashu; Rawat, Renu; Singh, Brajinder; Ravindranath, S D

    2003-07-30

    Green tea manufacture was standardized with respect to the inactivation of polyphenol oxidase (PPO), rolling, and drying for quality manufacture. Inactivation of PPO by parching, steaming, microwave heating, and oven heating was monitored in tea shoots. The inactivated shoots were rolled under regimens of high and low pressures and dried by microwave heating, oven heating, or sun-drying; total phenols and catechins were estimated. Parched and sun-dried teas contained the lowest levels of total phenols and catechins, and their infusions were dull in color with a slightly burnt odor. Microwave-inactivated and-dried teas showed the highest levels of total phenols and catechins, and their infusions were bright in color and sweet in taste with a subtle pleasant odor. In steam-inactivated and oven/microwave-dried teas, total phenol and catechin contents were intermediate between parched and sun-dried teas and microwave-inactivated and microwave-dried teas, and their infusions were bright with a umami taste.

  16. Advances in microwaves 7

    CERN Document Server

    Young, Leo

    2013-01-01

    Advances in Microwaves, Volume 7 covers the developments in the study of microwaves. The book discusses the effect of surface roughness on the propagation of the TEM mode, as well as the voltage breakdown of microwave antennas. The text also describes the theory and design considerations of single slotted-waveguide linear arrays and the techniques and theories that led to the achievement of wide bandwidths and ultralow noise temperatures for communication applications. The book will prove invaluable to microwave engineers.

  17. The Effects of Drying Methods, Packaging Atmosphere and Storage Time on Dried Pomegranate Aril Quality

    OpenAIRE

    GÖLÜKCÜ, Muharrem

    2015-01-01

    The aim of this work was to evaluate the effects of drying methods, packaging atmosphere, and storage time in preserving the quality of dried pomegranate aril on total phenolic matter, total anthocyanin, antioxidant activity, and CIE L, a*, b*, C, h colour values. The highest contents of phenolic matter (5580 mg kg-1), anthocyanin (679.76 mg kg-1), antioxidant capacity (IC50, 26.16 mg g-1) and CIE a* colour value (10.73) were observed in freeze dried sample, followed by vacuum, convective, an...

  18. Microwave Radiometer (MWR) Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Morris, VR

    2006-08-01

    The Microwave Radiometer (MWR) provides time-series measurements of column-integrated amounts of water vapor and liquid water. The instrument itself is essentially a sensitive microwave receiver. That is, it is tuned to measure the microwave emissions of the vapor and liquid water molecules in the atmosphere at specific frequencies.

  19. Nonlinearities in Microwave Superconductivity

    OpenAIRE

    Ledenyov, Dimitri O.; Ledenyov, Viktor O.

    2012-01-01

    The research is focused on the modeling of nonlinear properties of High Temperature Superconducting (HTS) thin films, using Bardeen, Cooper, Schrieffer and Lumped Element Circuit theories, with purpose to enhance microwave power handling capabilities of microwave filters and optimize design of microwave circuits in micro- and nano- electronics.

  20. Long-Wavelength Rupturing Instability in Surface-Tension-Driven Benard Convection

    Science.gov (United States)

    Swift, J. B.; Hook, Stephen J. Van; Becerril, Ricardo; McCormick, W. D.; Swinney, H. L.; Schatz, Michael F.

    1999-01-01

    A liquid layer with a free upper surface and heated from below is subject to thermocapillary-induced convective instabilities. We use very thin liquid layers (0.01 cm) to significantly reduce buoyancy effects and simulate Marangoni convection in microgravity. We observe thermocapillary-driven convection in two qualitatively different modes, short-wavelength Benard hexagonal convection cells and a long-wavelength interfacial rupturing mode. We focus on the long-wavelength mode and present experimental observations and theoretical analyses of the long-wavelength instability. Depending on the depths and thermal conductivities of the liquid and the gas above it, the interface can rupture downwards and form a dry spot or rupture upwards and form a high spot. Linear stability theory gives good agreement to the experimental measurements of onset as long as sidewall effects are taken into account. Nonlinear theory correctly predicts the subcritical nature of the bifurcation and the selection between the dry spot and high spots.

  1. Color sensing under microwaves

    Science.gov (United States)

    Choudhury, Debesh

    2013-09-01

    Inspired by recent results of artificial color due to Caulfield, we carry out intuitive experimental investigations on color sensing under microwave illumination. Experiemnts have been carried out using a Gunn diode as the microwave source and a microwave diode as a detector. More precise experimental studies have also been carried out utilizing a vector network analyzer. Preliminary results of the experiments validate the feasibility of sensing and discriminating otherwise visual colors under microwave illumination. Caulfield's presumption possibly paves the way for artificial color perception using microwaves.

  2. Recent developments in drying of food products

    Science.gov (United States)

    Valarmathi, T. N.; Sekar, S.; Purushothaman, M.; Sekar, S. D.; Rama Sharath Reddy, Maddela; Reddy, Kancham Reddy Naveen Kumar

    2017-05-01

    Drying is a dehydration process to preserve agricultural products for long period usage. The most common and cheapest method is open sun drying in which the products are simply laid on ground, road, mats, roof, etc. But the open sun drying has some disadvantages like dependent on good weather, contamination by dust, birds and animals consume a considerable quantity, slow drying rate and damages due to strong winds and rain. To overcome these difficulties solar dryers are developed with closed environment for drying agricultural products effectively. To obtain good quality food with reduced energy consumption, selection of appropriate drying process and proper input parameters is essential. In recent years several researchers across the world have developed new drying systems for improving the product quality, increasing the drying rate, decreasing the energy consumption, etc. Some of the new systems are fluidized bed, vibrated fluidized bed, desiccant, microwave, vacuum, freeze, infrared, intermittent, electro hydrodynamic and hybrid dryers. In this review the most recent progress in the field of drying of agricultural food products such as new methods, new products and modeling and optimization techniques has been presented. Challenges and future directions are also highlighted. The review will be useful for new researchers entering into this ever needed and ever growing field of engineering.

  3. Bioethanol production from Ficus religiosa leaves using microwave irradiation.

    Science.gov (United States)

    Klein, Miri; Griess, Ofir; Pulidindi, Indra Neel; Perkas, Nina; Gedanken, Aharon

    2016-07-15

    A microwave assisted feasible process for the production of bioethanol from Ficus religiosa leaves was developed. Under the process conditions (8 min. microwave irradiation, 1 M HCl), 10.1 wt% glucose yield was obtained from the leaves. Microwave based hydrolysis process yielded higher glucose content (10.1 wt%) compared to the conventional hydrothermal process (4.1 wt%). Upon fermentation of the hydrolysate using Baker's yeast, 3 wt% (dry wt. basis) of bioethanol was produced.

  4. MACHYDRO-90 - The microwave aircraft experiment for hydrology

    Science.gov (United States)

    Engman, Edwin T.

    1991-01-01

    MACHYDRO-90 is a multisensor aircraft campaign (MAC) that was held in central Pennsylvania over an eleven day period in July 1990. The emphasis of the campaign was on the microwave measurements of soil moisture, although other aspects of hydrology and microwave-target interactions were also studied. A description is given of the experiment, its organization, and the meteorological conditions during the eleven days. Preliminary results are also presented from PBMR (Push-Broom Microwave Radiometer) and SAR (synthetic aperture radar) measurements of soil moisture. These results are portrayed in the context of the hydrology, which, during this experiment, exhibited dry and wet extremes.

  5. High brightness microwave lamp

    Science.gov (United States)

    Kirkpatrick, Douglas A.; Dolan, James T.; MacLennan, Donald A.; Turner, Brian P.; Simpson, James E.

    2003-09-09

    An electrodeless microwave discharge lamp includes a source of microwave energy, a microwave cavity, a structure configured to transmit the microwave energy from the source to the microwave cavity, a bulb disposed within the microwave cavity, the bulb including a discharge forming fill which emits light when excited by the microwave energy, and a reflector disposed within the microwave cavity, wherein the reflector defines a reflective cavity which encompasses the bulb within its volume and has an inside surface area which is sufficiently less than an inside surface area of the microwave cavity. A portion of the reflector may define a light emitting aperture which extends from a position closely spaced to the bulb to a light transmissive end of the microwave cavity. Preferably, at least a portion of the reflector is spaced from a wall of the microwave cavity. The lamp may be substantially sealed from environmental contamination. The cavity may include a dielectric material is a sufficient amount to require a reduction in the size of the cavity to support the desired resonant mode.

  6. Convection in porous media

    CERN Document Server

    Nield, Donald A

    1992-01-01

    This book provides a user-friendly introduction to the topic of convection in porous media The authors as- sume that the reader is familiar with the basic elements of fluid mechanics and heat transfer, but otherwise the book is self-contained The book will be useful both as a review (for reference) and as a tutorial work, suitable as a textbook in a graduate course or seminar The book brings into perspective the voluminous research that has been performed during the last two decades The field has recently exploded because of worldwide concern with issues such as energy self-sufficiency and pollution of the environment Areas of application include the insulation of buildings and equipment, energy storage and recovery, geothermal reservoirs, nuclear waste disposal, chemical reactor engineering, and the storage of heat-generating materials such as grain and coal Geophysical applications range from the flow of groundwater around hot intrusions to the stability of snow against avalanches

  7. Convection in Porous Media

    CERN Document Server

    Nield, Donald A

    2013-01-01

    Convection in Porous Media, 4th Edition, provides a user-friendly introduction to the subject, covering a wide range of topics, such as fibrous insulation, geological strata, and catalytic reactors. The presentation is self-contained, requiring only routine mathematics and the basic elements of fluid mechanics and heat transfer. The book will be of use not only to researchers and practicing engineers as a review and reference, but also to graduate students and others entering the field. The new edition features approximately 1,750 new references and covers current research in nanofluids, cellular porous materials, strong heterogeneity, pulsating flow, and more. Recognized as the standard reference in the field Includes a comprehensive, 250-page reference list Cited over 2300 times to date in its various editions Serves as an introduction for those entering the field and as a comprehensive reference for experienced researchers Features new sections on nanofluids, carbon dioxide sequestration, and applications...

  8. MATHEMATICAL MODELING OF ORANGE SEED DRYING KINETICS

    Directory of Open Access Journals (Sweden)

    Daniele Penteado Rosa

    2015-06-01

    Full Text Available Drying of orange seeds representing waste products from juice processing was studied in the temperatures of 40, 50, 60 and 70 °C and drying velocities of 0.6, 1.0 and 1.4 m/s. Experimental drying kinetics of orange seeds were obtained using a convective air forced dryer. Three thin-layer models: Page model, Lewis model, and the Henderson-Pabis model and the diffusive model were used to predict the drying curves. The Henderson-Pabis and the diffusive models show the best fitting performance and statistical evaluations. Moreover, the temperature dependence on the effective diffusivity followed an Arrhenius relationship, and the activation energies ranging from 16.174 to 16.842 kJ/mol

  9. One-Dimensional Simulation of Clay Drying

    Directory of Open Access Journals (Sweden)

    Siljan Siljan

    2002-04-01

    Full Text Available Drying of clay is simulated by a one-dimensional model. The background of the work is to form a better basis for investigation of the drying process in production of clay-based building materials. A model of one-dimensional heat and mass transfer in porous material is used and modified to simulate drying of clay particles. The convective terms are discretized by first-order upwinding, and the diffusive terms are discretized by central differencing. DASSL was used to solve the set of algebraic and differential equations. The different simulations show the effect of permeability, initial moisture content and different boundary conditions. Both drying of a flat plate and a spherical particle are modelled.

  10. Convection Fingerprints on the Vertical Profiles of Q1 and Q2

    Science.gov (United States)

    Chang, C.; Lin, H.; Chou, C.

    2013-12-01

    Different types of tropical convection left their fingerprints on vertical structures of apparent heat source (Q1) and apparent moisture sink (Q2). Profile of deep convection on condensation heating and drying has been well-documented, yet direct assessment of shallow convection remains to be explored. Shallow convection prevails over subtropical ocean, where large-scale subsidence is primarily balanced by radiative cooling and moistening due to surface evaporation instead of moist convection. In this study a united framework is designed to investigate the vertical structures of tropical marine convections in three reanalysis data, including ERA-Interim, MERRA, and CFSR. It starts by sorting and binning data from the lightest to the heaviest rain. Then the differences between two neighboring bins are used to examine the direct effects for precipitation change, in light of the fact that non-convective processes would change slowly from bin to bin. It is shown that all three reanalyses reveal the shallow convective processes in light rain bins, featured by re-evaporating and detraining at the top of boundary layer and lower free troposphere. For heavy rain bins, three reanalyses mainly differ in their numbers and altitudes of heating and drying peaks, implying no universal agreement has been reached on partitioning of cloud populations. Coherent variations in temperature, moisture, and vertical motion are also discussed. This approach permits a systematical survey and comparison of tropical convection in GCM-type models, and preliminary studies of three reanalyses suggest certain degree of inconsistency in simulated convective feedback to large-scale heat and moisture budgets.

  11. Effective moisture diffusivity and activation energy of rambutan seed under different drying methods to promote storage stability

    Science.gov (United States)

    Ahmad, So'bah; Shamsul Anuar, Mohd; Saleena Taip, Farah; Shamsudin, Rosnah; M, Siti Roha A.

    2017-05-01

    The effects of two drying methods, oven and microwave drying on the effective moisture diffusivity and activation energy of rambutan seed were studied. Effective moisture diffusivity and activation energy are the main indicators used for moisture movement within the material. Hence, it is beneficial to determine an appropriate drying method to attain a final moisture content of rambutan seed that potentially could be used as secondary sources in the industry. An appropriate final moisture content will provide better storage stability that can extend the lifespan of the rambutan seed. The rambutan seeds were dried with two drying methods (oven and microwave) at two level of the process variables (oven temperature; 40°C and 60°C and microwave power; 250W and 1000W) at constant initial moisture contents. The result showed that a higher value of effective moisture diffusivity and less activation energy were observed in microwave drying compared to oven drying. This finding portrays microwave drying expedites the moisture removal to achieve the required final moisture content and the most appropriate drying method for longer storage stability for rambutan seed. With respect to the process variables; higher oven temperatures and lower microwave powers also exhibit similar trends. Hopefully, this study would provide a baseline data to determine an appropriate drying method for longer storage period for turning waste to by-products.

  12. The Shallow-to-Deep Transition in Convective Clouds During GoAmazon 2014/5

    Science.gov (United States)

    Jensen, M. P.; Gostic, C.; Giangrande, S. E.; Mechem, D. B.; Ghate, V. P.; Toto, T.

    2016-12-01

    Nearly two years of observations from the ARM Mobile Facility (AMF) deployed at Manacapuru, Brazil during the GOAmazon 2014/5 campaign are analyzed to investigate the environmental conditions controlling the transition from shallow to deep convective clouds. The Active Remote Sensing of Clouds (ARSCL) product, which combines radar and lidar observations to produce best estimates of cloud locations in the vertical column is used to qualitatively define four subsets of convective cloud conditions: 1,2) Transition cases (wet season, dry season), where a period of shallow convective clouds is followed by a period of deep convective clouds and 2) Non-transition cases (wet season, dry season), where shallow convective clouds persist without any subsequent development. For these subsets, observations of the time varying thermodynamic properties of the atmosphere, including the surface heat and radiative fluxes, the profiles of atmospheric state variables, and the ECMWF-derived large-scale advective tendencies, are composited to define averaged properties for each transition state. Initial analysis indicates that the transition state strongly depends on the pre-dawn free-tropospheric humidity, the convective inhibition and surface temperature and humidity with little dependence on the convective available potential energy and surface heat fluxes. The composited environmental thermodynamics are then used to force large-eddy simulations for the four transition states to further evaluate the sensitivity of the transition to the composite thermodynamics versus the importance of larger-scale forcing.

  13. The role of radiation in organizing convection in weak temperature gradient simulations

    Science.gov (United States)

    Sessions, Sharon L.; Sentić, Stipo; Herman, Michael J.

    2016-03-01

    Using a cloud system resolving model with the large scale parameterized by the weak temperature gradient approximation, we investigated the influence of interactive versus noninteractive radiation on the characteristics of convection and convective organization. The characteristics of convecting environments are insensitive to whether radiation is interactive compared to when it is not. This is not the case for nonconvecting environments; interactive radiative cooling profiles show strong cooling at the top of the boundary layer which induces a boundary layer circulation that ultimately exports moist entropy (or analogously moist static energy) from dry domains. This upgradient transport is associated with a negative gross moist stability, and it is analogous to boundary layer circulations in radiative convective equilibrium simulations of convective self-aggregation. This only occurs when radiation cools interactively. Whether radiation is static or interactive also affects the existence of multiple equilibria-steady states which either support precipitating convection or which remain completely dry depending on the initial moisture profile. Interactive radiation drastically increases the range of parameters which permit multiple equilibria compared to static radiation; this is consistent with the observation that self-aggregation in radiative-convective equilibrium simulations is more readily attained with interactive radiation. However, the existence of multiple equilibria in absence of interactive radiation suggests that other mechanisms may result in organization.

  14. Effect of different drying methods on the composition of steviol glycosides in Stevia rebaudiana Bertoni leaves

    Science.gov (United States)

    Aranda-González, Irma; Betancur-Ancona, David; Chel-Guerrero, Luis; Moguel-Ordóñez, Yolanda

    2017-01-01

    Drying techniques can modify the composition of certain plant compounds. Therefore, the aim of the study was to assess the effect of different drying methods on steviol glycosides in Stevia rebaudiana Bertoni leaves. Four different drying methods were applied to Stevia rebaudiana Bertoni leaves, which were then subjected to aqueous extraction. Radiation or convection drying was performed in stoves at 60°C, whereas shade or sun drying methods were applied at 29.7°C and 70% of relative humidity. Stevioside, rebaudioside A, rebaudioside B, rebaudioside C, rebaudioside D, dulcoside A, and steviolbioside were quantified by a validated HPLC method. Among steviol glycosides, the content (g 100 g-1 dry basis) of stevioside, rebaudioside A, rebaudioside B, and rebaudioside C varied according to the drying method. The total glycoside content was higher in sun-dried samples, with no significant differences compared to shade or convection drying, whereas radiation drying adversely affected the content of rebaudioside A and rebaudioside C (p <0.01) and was therefore a method lowering total glycoside content. The effect of the different drying methods was also reflected in the proportion of the sweetener profile. Convection drying could be suitable for modern food processing industries while shadow or sun drying may be a low-cost alternative for farmers.

  15. Microwave-Assisted Synthesis of Some 3,5-Arylated 2-Pyrazolines

    Directory of Open Access Journals (Sweden)

    Hassan Ghasemnejad

    2003-07-01

    Full Text Available Condensation of 2-acetylnaphthalene with benzaldehydes under microwave irradiation affords chalcones which undergo facile and clean cyclizations with hydrazines RNHNH2 (R= H, Ph, Ac to afford 3,5-arylated 2-pyrazolines in quantitative yields, also under microwave irradiation and in the presence of dry AcOH as cyclizing agent. The results obtained indicate that, unlike classical heating, microwave irradiation results in higher yields, shorter reaction times (2-12 min. and cleaner reactions.

  16. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Eye Symptoms Causes of Dry Eye Dry Eye Treatment What Is Dry Eye? Written By: Kierstan Boyd ... your vision. Privacy Policy Related New Dry Eye Treatment is a Tear-Jerker Jul 21, 2017 Three ...

  17. Determination of temperature dependent drying parameters for potato cylinders and slices during solar drying

    Energy Technology Data Exchange (ETDEWEB)

    Tripathy, P.P.; Kumar, Subodh [Centre for Energy Studies, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110 016 (India)

    2008-11-15

    In the present work, a methodology for the determination of temperature dependent drying parameters namely drying constant and lag factor from the experimental drying kinetic curves of food product is proposed. A laboratory scale mixed-mode solar dryer consisting of an inclined flat plate solar collector connected in series to a drying chamber glazed at the top was used to perform natural convection drying experiments with potato cylinders of length 0.05 m and diameter 0.01 m and slices of diameter 0.05 m and thickness 0.01 m. The thin-layer drying equation describing the drying behavior of food products is derived from Fick's law of diffusion. The present analysis reveals that both drying constant and lag factor increase with sample temperature, as expected. Linear and exponential correlations for these parameters are proposed to represent their variation as a function of sample temperature. Results of statistical error analysis indicate that the proposed linear correlation can better represent the experimental drying kinetic curves for both cylinders and slices. Comparison of experimental dimensionless moisture contents with those calculated with variable (temperature dependent) and constant values of drying parameters demonstrates that the predicted results from variable parameters can better simulate the experiments. (author)

  18. Thin layer drying of tomato slices.

    Science.gov (United States)

    Das Purkayastha, Manashi; Nath, Amit; Deka, Bidyut Chandra; Mahanta, Charu Lata

    2013-08-01

    The hot air convective drying characteristics of blanched tomato (Lycopersicon esculantum L.) slices have been investigated. Drying experiments were carried out at four different temperatures (50, 60, 65 and 70 °C). The effect of drying temperatures on the drying behavior of the tomato slices was evaluated. All drying experiments had only falling rate period. The average effective diffusivity values varied from 0.5453 × 10(-9) to 2.3871 × 10(-9) m(2)/s over the temperature range studied and the activation energy was estimated to be 61.004 kJ/mol. In order to select a suitable form of the drying curve, six different thin layer drying models (Henderson-Pabis, Page, Diamante et al., Wang and Singh, Logarithmic and Newton models) were fitted to the experimental data. The goodness of fit tests indicated that the Logarithmic model gave the best fit to experimental results, which was closely followed by the Henderson-Pabis model. The influence of varied drying temperatures on quality attributes of the tomato slices viz. Hunter color parameters, ascorbic acid, lycopene, titratable acidity, total sugars, reducing sugars and sugar/acid ratio of dried slices was also studied. Slices dried at 50 and 60 °C had high amount of total sugars, lycopene, sugar/acid ratio, Hunter L- and a-values. Drying of slices at 50 °C revealed optimum retention of ascorbic acid, sugar/acid ratio and red hue, whereas, drying at higher temperature (65 and 70 °C) resulted in a considerable decrease in nutrients and colour quality of the slices.

  19. Conjugate Problems in Convective Heat Transfer: Review

    Directory of Open Access Journals (Sweden)

    Abram Dorfman

    2009-01-01

    Full Text Available A review of conjugate convective heat transfer problems solved during the early and current time of development of this modern approach is presented. The discussion is based on analytical solutions of selected typical relatively simple conjugate problems including steady-state and transient processes, thermal material treatment, and heat and mass transfer in drying. This brief survey is accompanied by the list of almost two hundred publications considering application of different more and less complex analytical and numerical conjugate models for simulating technology processes and industrial devices from aerospace systems to food production. The references are combined in the groups of works studying similar problems so that each of the groups corresponds to one of selected analytical solutions considered in detail. Such structure of review gives the reader the understanding of early and current situation in conjugate convective heat transfer modeling and makes possible to use the information presented as an introduction to this area on the one hand, and to find more complicated publications of interest on the other hand.

  20. Convection in Type 2 supernovae

    Energy Technology Data Exchange (ETDEWEB)

    Miller, D.S.

    1993-10-15

    Results are presented here from several two dimensional numerical calculations of events in Type II supernovae. A new 2-D hydrodynamics and neutrino transport code has been used to compute the effect on the supernova explosion mechanism of convection between the neutrinosphere and the shock. This convection is referred to as exterior convection to distinguish it from convection beneath the neutrinosphere. The model equations and initial and boundary conditions are presented along with the simulation results. The 2-D code was used to compute an exterior convective velocity to compare with the convective model of the Mayle and Wilson 1-D code. Results are presented from several runs with varying sizes of initial perturbation, as well as a case with no initial perturbation but including the effects of rotation. The M&W code does not produce an explosion using the 2-D convective velocity. Exterior convection enhances the outward propagation of the shock, but not enough to ensure a successful explosion. Analytic estimates of the growth rate of the neutron finger instability axe presented. It is shown that this instability can occur beneath the neutrinosphere of the proto-neutron star in a supernova explosion with a growth time of {approximately} 3 microseconds. The behavior of the high entropy bubble that forms between the shock and the neutrinosphere in one dimensional calculations of supernova is investigated. It has been speculated that this bubble is a site for {gamma}-process generation of heavy elements. Two dimensional calculations are presented of the time evolution of the hot bubble and the surrounding stellar material. Unlike one dimensional calculations, the 2D code fails to achieve high entropies in the bubble. When run in a spherically symmetric mode the 2-D code reaches entropies of {approximately} 200. When convection is allowed, the bubble reaches {approximately} 60 then the bubble begins to move upward into the cooler, denser material above it.

  1. Convection in Type 2 supernovae

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Douglas Scott [Univ. of California, Davis, CA (United States)

    1993-10-15

    Results are presented here from several two dimensional numerical calculations of events in Type II supernovae. A new 2-D hydrodynamics and neutrino transport code has been used to compute the effect on the supernova explosion mechanism of convection between the neutrinosphere and the shock. This convection is referred to as exterior convection to distinguish it from convection beneath the neutrinosphere. The model equations and initial and boundary conditions are presented along with the simulation results. The 2-D code was used to compute an exterior convective velocity to compare with the convective model of the Mayle and Wilson 1-D code. Results are presented from several runs with varying sizes of initial perturbation, as well as a case with no initial perturbation but including the effects of rotation. The M&W code does not produce an explosion using the 2-D convective velocity. Exterior convection enhances the outward propagation of the shock, but not enough to ensure a successful explosion. Analytic estimates of the growth rate of the neutron finger instability axe presented. It is shown that this instability can occur beneath the neutrinosphere of the proto-neutron star in a supernova explosion with a growth time of ~ 3 microseconds. The behavior of the high entropy bubble that forms between the shock and the neutrinosphere in one dimensional calculations of supernova is investigated. It has been speculated that this bubble is a site for γ-process generation of heavy elements. Two dimensional calculations are presented of the time evolution of the hot bubble and the surrounding stellar material. Unlike one dimensional calculations, the 2D code fails to achieve high entropies in the bubble. When run in a spherically symmetric mode the 2-D code reaches entropies of ~ 200. When convection is allowed, the bubble reaches ~60 then the bubble begins to move upward into the cooler, denser material above it.

  2. Comparative Study of Microwave Induced and Conventional Synthesis of Acetylated Sugar Isothiocyanates and Related Thiocarbamides

    Directory of Open Access Journals (Sweden)

    Atul V. Yadgire

    2011-01-01

    Full Text Available The synthesis of several acetylated sugar isothiocyanates have been carried out under microwave irradiation in excellent yields of products by using related bromides and lead thiocyanate in sodium dried xylene. Several acetylated sugar thiocarbamides have been synthesized by the interaction of respective acetylated sugar isothiocyanates with appropriate aryl amines under microwave irradiation.

  3. Internally heated convection and Rayleigh-Bénard convection

    CERN Document Server

    Goluskin, David

    2016-01-01

    This Brief describes six basic models of buoyancy-driven convection in a fluid layer: three configurations of internally heated convection and three configurations of Rayleigh-Bénard convection. The author discusses the main quantities that characterize heat transport in each model, along with the constraints on these quantities. This presentation is the first to place the various models in a unified framework, and similarities and differences between the cases are highlighted. Necessary and sufficient conditions for convective motion are given. For the internally heated cases only, parameter-dependent lower bounds on the mean fluid temperature are proven, and results of past simulations and laboratory experiments are summarized and reanalyzed. The author poses several open questions for future study.

  4. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Español Eye Health / Eye Health A-Z Dry Eye Sections What Is Dry Eye? Dry Eye Symptoms ... Dry Eye Dry Eye Treatment What Is Dry Eye? Written By: Kierstan Boyd Reviewed By: Brenda Pagan- ...

  5. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Español Eye Health / Eye Health A-Z Dry Eye Sections What Is Dry Eye? Dry Eye Symptoms ... Dry Eye Dry Eye Treatment What Is Dry Eye? Leer en Español: ¿Qué Es el Ojo Seco? ...

  6. Using your microwave oven. Lesson 6, Microwave oven management

    OpenAIRE

    Woodard, Janice Emelie, 1929-

    1984-01-01

    Discusses cooking and reheating foods in microwave ovens, and adapting conventional recipes for the microwave. Revised Includes the publication: Adapting conventional recipes to microwave cooking : fact sheet 84 by Janice Woodard, Rebecca Lovingood, R.H. Trice.

  7. Using your microwave oven. Lesson 6, Microwave oven management

    OpenAIRE

    Woodard, Janice Emelie, 1929-

    1984-01-01

    Discusses cooking and reheating foods in microwave ovens, and adapting conventional recipes for the microwave. Revised Includes the publication: Adapting conventional recipes to microwave cooking : fact sheet 84 by Janice Woodard, Rebecca Lovingood, R.H. Trice.

  8. Energetic and exergetic performance analysis and modeling of drying kinetics of kiwi slices

    National Research Council Canada - National Science Library

    Darvishi, Hosain; Zarein, Mohammad; Farhudi, Zanyar

    2016-01-01

    This work focused on the effects of the moisture content, slices thickness and microwave power on aspects of energy and exergy, drying kinetics, moisture diffusivity, activation energy, and modeling...

  9. Assessment of forecast indices over Sriharikota using ground-based microwave radiometer

    Science.gov (United States)

    Pushpa Saroja, R.; Rajasekhar, M.; Papa Rao, G.; Rajeevan, M.; Bharathi, G.

    2016-05-01

    Continuous measurements of vertical profiles of thermodynamic variables are important for severe weather nowcasting & forecasting over a region instead of radiosonde observations which are available once or twice daily. Microwave Radiometer (MWR) provides high quality of thermodynamic (temperature, water vapor, and cloud liquid) soundings up to an altitude of 10 Kms in the clear and cloudy weather conditions except during heavy rainfall. Retrievals of MWR profiles are based on the intensity of the atmospheric radiation at selected frequencies (22-30 GHz) & (51-59 GHz) with high temporal and vertical resolution in the troposphere. The MWR used in the present study is TP/WVP-3166A, measures the intensity of radiation at 8 water vapor channels and 14 oxygen channels which is installed at Sriharikota in June. In this paper we analyzed the thermodynamic indices derived from MWR profiles during severe convective thunderstorms for Sriharikota region. MWR derived thermodynamic profiles are compared with radiosonde observations during rainy & non rainy days. MWR temperature profiles and vapor density profiles are well correlated with the observations with a cold bias of 1.5°C & 2.5°C and with a dry bias of 0.37 g/m3 & 0.04 g/m3respectively. For this we considered 10 thunderstorm cases from June to November 2014 analysed with indices K index, MDPI, CAPE, Windex, KO index, L index, S index, Showalter index, Total totals index, Vertical totals along with integrated liquid water and vapour density. MDPI, CAP index, Windex, Kindex, Lindex and convective temperature were best performed indices two hours prior to thunderstorm over SHAR region.

  10. The Development of Geostationary Microwave Observation in China

    Science.gov (United States)

    LU, Naimeng; GUO, Yang; GU, Songyan; WU, Xuebao; LI, Xiaoqing

    2015-04-01

    Great achievements have been made in the regime of microwave observation from polar orbiting meteorological satellites and their microwave data have been successfully used in the retrieval of precipitation and temperature/humidity profile, as well as data assimilation. But right now, there is no microwave observation in GEO due to its technical difficulty even through some plans such as GEM, GOMAS were proposed. The plan to develop microwave instruments for geostationary meteorological satellites have been approved by Chinese government and this presentation will introduce the status of its development, including the requirement consideration, microwave forward model simulation, the retrieval of precipitation, instrument specification, potential data application.. The followings are concluded in this presentation, •Microwave observation on GEO will greatly improve the capacity of current meteorological satellites •The 54GHz and 183GHz bands are on the top of the priority for temperature and humidity profiling, followed by 118, 425 and 325,380 GHz respectively. •Combined the 54 and 183 band together, better precipitation retrieval results could be expected •Regarding the strong convective precipitation retrieval, the 54GHz and 183GHz bands can provide basic information for precipitation retrieval and the improvement with additional window channels is not very significant. •The satisfied resolution for precipitation estimation is 5 to 10 Km and the tolerant value is 50km.

  11. Organization of tropical deep convection in low vertical wind shears: The role of boundary conditions

    Science.gov (United States)

    Gezahegn Semie, Addisu; Tompkins, Adrian Mark

    2015-04-01

    Previous Experiments with convection-permitting models have documented the various roles of water vapor, cold pools, and radiative feedbacks in the self-organization of tropical deep convection. Most of these simulations were conducted using idealized conditions with fixed and spatially homogeneous sea surface temperatures (SST), and over large enough domains the feedback mechanisms lead to strongly organized convection. In its equilibrium state the convection occurs in a single organised cluster or band, depending on the system mean wind state, surrounded by regions that are extremely dry and free of deep convection. . We hypothesize that radiative feedbacks involving the surface may provide a strong negative feedback to counter the organisation of convection. For example, the enhanced downwelling short-wave radiation in suppressed area should lead to enhanced SST (sometime termed SST hotspots). Which will ultimately lead to convection if the atmosphere moistens sufficiently to permit it. Similar feedback may occur over land. We therefore extend the numerical idealized experiment framework by including the effect of an interactive lower boundary sea and land conditions such as ocean and land with a range of soil moisture contents. To ascertain how this affects the self-organization of convection we construct a simple set of diagnostics to classify which mechanisms are operating, their relative importance and spacial scales.

  12. Evidence for Tropopause Layer Moistening by Convection During CRYSTAL-FACE

    Science.gov (United States)

    Ackerman, A.; Fridlind, A.; Jensen, E.; Miloshevich, L.; Heymsfield, G.; McGill, M.

    2003-01-01

    Measurements and analysis of the impact of deep convection on tropopause layer moisture are easily confounded by difficulties making precise observations with sufficient spatial coverage before and after convective events and difficulties distinguishing between changes due to local convection versus large-scale advection. The interactions between cloud microphysics and dynamics in the convective transport of moisture into the tropopause layer also result in a sufficiently complex and poorly characterized system to allow for considerable freedom in theoretical models of stratosphere-troposphere exchange. In this work we perform detailed large-eddy simulations with an explicit cloud microphysics model to study the impact of deep convection on tropopause layer moisture profiles observed over southern Florida during CRYSTALFACE. For four days during the campaign (July 11, 16, 28, and 29) we initialize a 100-km square domain with temperature and moisture profiles measured prior to convection at the PARSL ground site, and initiate convection with a warm bubble that produces an anvil at peak elevations in agreement with lidar and radar observations on that day. Comparing the moisture field after the anvils decay with the initial state, we find that convection predominantly moistens the tropopause layer (as defined by minimum temperature and minimum potential temperature lapse rate), although some drying is also predicted in localized layers. We will also present results of sensitivity tests designed to separate the roles of cloud microphysics and dynamics.

  13. Plumes in stellar convection zones

    CERN Document Server

    Zahn, J P

    1999-01-01

    All numerical simulations of compressible convection reveal the presence of strong downwards directed flows. Thanks to helioseismology, such plumes have now been detected also at the top of the solar convection zone, on super- granular scales. Their properties may be crudely described by adopting Taylor's turbulent entrainment hypothesis, whose validity is well established under various conditions. Using this model, one finds that the strong density stratification does not prevent the plumes from traversing the whole convection zone, and that they carry upwards a net energy flux (Rieutord & Zahn 1995). They penetrate to some extent in the adjacent stable region, where they establish a nearly adiabatic stratification. These plumes have a strong impact on the dynamics of stellar convection zones, and they play probably a key role in the dynamo mechanism.

  14. An efficient empirical model for microwave-induced average temperature of liquid cylindrical reactants.

    Science.gov (United States)

    Yang, Chuqiao; Yakovlev, Vadim V

    2013-01-01

    Microwave-assisted chemical reactions have become very popular in preparative chemistry due to many advantages such as accelerated reaction rate, higher chemical yield and lower energy use. In dedicated equipment, however, the microwave units operate as "black boxes" keeping the role of the thermal effects in microwave-assisted chemical processes somewhat obscure. To address this issue, in this paper, we propose a simple mathematical model for computing microwave-induced temperature in a three-media cylindrical structure representing a core element of a typical microwave reactor with the reactant assumed to be stirred by convection flows. The model determines the average temperature of the reactant for the known absorbed microwave power and heating time. To illustrate its functionality, the model is used to compute time-temperature characteristics of water, ethanol, and methanol heated in the batch reactor MiniFlow 200SS. The curve calculated for water appears to be in an excellent agreement with an experiment. This confirms the hypothesis on temperature homogenization in liquid reactants in batch reactors due to convection and suggests that modeling can be helpful in clarifying and quantifying the details of microwave-assisted chemical processes.

  15. Microwave and RF engineering

    CERN Document Server

    Sorrentino, Roberto

    2010-01-01

    An essential text for both students and professionals, combining detailed theory with clear practical guidance This outstanding book explores a large spectrum of topics within microwave and radio frequency (RF) engineering, encompassing electromagnetic theory, microwave circuits and components. It provides thorough descriptions of the most common microwave test instruments and advises on semiconductor device modelling. With examples taken from the authors' own experience, this book also covers:network and signal theory;electronic technology with guided electromagnetic pr

  16. Convective cooling of photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Hodge, E.; Gibbons, C. [Energy Engineering Group, Mechanical Engineering Department, Cork Institute of Technology, Bishopstown, Cork (Ireland)

    2004-07-01

    Most solar cells presently on the market are based on silicon wafers, the so-called first generation technology. As this technology has matured costs have become increasingly dominated by material costs. In the last ten years, continuous work has brought the efficiency of standard cells to the 25% region. A switch to second generation or thin film technology cells now seems imminent. Thin film technology eliminates the silicon wafer and offer the prospect of reducing material and manufacturing costs, but they exhibit lower efficiencies of around 10% for a commercial device. Third generation or tandem cells are currently at a 'proof of concept' research level, with a theoretical conversion rate of 86.8% being asserted Whatever the material construction and manufacturing method of cells, the thermal effect of overheating will prevail in the semiconductor and it is accepted that a lowered temperature will bring about an increase in conversion efficiency. The aim of this project is to improve the efficiency of PV electrical output, by convectively cooling the cells through perforations in them. As the cells heat up they lose efficiency. As the panel heats up a loss in efficiency of 0.5% per C increase in temperature has been recorded. (orig.)

  17. Development of Solar Drying Model for Selected Cambodian Fish Species

    Directory of Open Access Journals (Sweden)

    Anna Hubackova

    2014-01-01

    Full Text Available A solar drying was investigated as one of perspective techniques for fish processing in Cambodia. The solar drying was compared to conventional drying in electric oven. Five typical Cambodian fish species were selected for this study. Mean solar drying temperature and drying air relative humidity were 55.6°C and 19.9%, respectively. The overall solar dryer efficiency was 12.37%, which is typical for natural convection solar dryers. An average evaporative capacity of solar dryer was 0.049 kg·h−1. Based on coefficient of determination (R2, chi-square (χ2 test, and root-mean-square error (RMSE, the most suitable models describing natural convection solar drying kinetics were Logarithmic model, Diffusion approximate model, and Two-term model for climbing perch and Nile tilapia, swamp eel and walking catfish and Channa fish, respectively. In case of electric oven drying, the Modified Page 1 model shows the best results for all investigated fish species except Channa fish where the two-term model is the best one. Sensory evaluation shows that most preferable fish is climbing perch, followed by Nile tilapia and walking catfish. This study brings new knowledge about drying kinetics of fresh water fish species in Cambodia and confirms the solar drying as acceptable technology for fish processing.

  18. Development of solar drying model for selected Cambodian fish species.

    Science.gov (United States)

    Hubackova, Anna; Kucerova, Iva; Chrun, Rithy; Chaloupkova, Petra; Banout, Jan

    2014-01-01

    A solar drying was investigated as one of perspective techniques for fish processing in Cambodia. The solar drying was compared to conventional drying in electric oven. Five typical Cambodian fish species were selected for this study. Mean solar drying temperature and drying air relative humidity were 55.6 °C and 19.9%, respectively. The overall solar dryer efficiency was 12.37%, which is typical for natural convection solar dryers. An average evaporative capacity of solar dryer was 0.049 kg · h(-1). Based on coefficient of determination (R(2)), chi-square (χ(2)) test, and root-mean-square error (RMSE), the most suitable models describing natural convection solar drying kinetics were Logarithmic model, Diffusion approximate model, and Two-term model for climbing perch and Nile tilapia, swamp eel and walking catfish and Channa fish, respectively. In case of electric oven drying, the Modified Page 1 model shows the best results for all investigated fish species except Channa fish where the two-term model is the best one. Sensory evaluation shows that most preferable fish is climbing perch, followed by Nile tilapia and walking catfish. This study brings new knowledge about drying kinetics of fresh water fish species in Cambodia and confirms the solar drying as acceptable technology for fish processing.

  19. Improved shelf life of dried Beauveria bassiana blastospores using convective drying and active packaging processes

    Science.gov (United States)

    The yeast form (blastospore) of the dimorphic insect-pathogenic fungus Beauveria bassiana can be rapidly produced using liquid fermentation methods but is generally unable to survive rapid dehydration processes or storage under non-refrigerated conditions. In this study, we evaluated the influence o...

  20. Advanced microwave processing concepts

    Energy Technology Data Exchange (ETDEWEB)

    Lauf, R.J.; McMillan, A.D.; Paulauskas, F.L. [Oak Ridge National Lab., TN (United States)

    1997-04-01

    The purpose of this work is to explore the feasibility of several advanced microwave processing concepts to develop new energy-efficient materials and processes. The project includes two tasks: (1) commercialization of the variable-frequency microwave furnace; and (2) microwave curing of polymeric materials. The variable frequency microwave furnace, whose initial conception and design was funded by the AIM Materials Program, allows the authors, for the first time, to conduct microwave processing studies over a wide frequency range. This novel design uses a high-power traveling wave tube (TWT) originally developed for electronic warfare. By using this microwave source, one can not only select individual microwave frequencies for particular experiments, but also achieve uniform power densities over a large area by the superposition of many different frequencies. Microwave curing of various thermoset resins will be studied because it holds the potential of in-situ curing of continuous-fiber composites for strong, lightweight components or in-situ curing of adhesives, including metal-to-metal. Microwave heating can shorten curing times, provided issues of scaleup, uniformity, and thermal management can be adequately addressed.

  1. Advanced microwave processing concepts

    Energy Technology Data Exchange (ETDEWEB)

    Lauf, R.J.; McMillan, A.D.; Paulauskas, F.L. [Oak Ridge National Laboratory, TN (United States)

    1995-05-01

    The purpose of this work is to explore the feasibility of several advanced microwave processing concepts to develop new energy-efficient materials and processes. The project includes two tasks: (1) commercialization of the variable-frequency microwave furnace; and (2) microwave curing of polymer composites. The variable frequency microwave furnace, whose initial conception and design was funded by the AIC Materials Program, will allow us, for the first time, to conduct microwave processing studies over a wide frequency range. This novel design uses a high-power traveling wave tube (TWT) originally developed for electronic warfare. By using this microwave source, one can not only select individual microwave frequencies for particular experiments, but also achieve uniform power densities over a large area by the superposition of many different frequencies. Microwave curing of thermoset resins will be studied because it hold the potential of in-situ curing of continuous-fiber composites for strong, lightweight components. Microwave heating can shorten curing times, provided issues of scaleup, uniformity, and thermal management can be adequately addressed.

  2. Advances in microwaves 3

    CERN Document Server

    Young, Leo

    2013-01-01

    Advances in Microwaves, Volume 3 covers the advances and applications of microwave signal transmission and Gunn devices. This volume contains six chapters and begins with descriptions of ground-station antennas for space communications. The succeeding chapters deal with beam waveguides, which offer interesting possibilities for transmitting microwave energy, as well as with parallel or tubular beams from antenna apertures. A chapter discusses the electron transfer mechanism and the velocity-field characteristics, with a particular emphasis on the microwave properties of Gunn oscillators. The l

  3. Influence of microwave heating on biogas production from Sida hermaphrodita silage.

    Science.gov (United States)

    Zieliński, Marcin; Dębowski, Marcin; Rusanowska, Paulina

    2017-09-01

    This study compared the effects on biogas production of suspended sludge versus a combination of suspended sludge and immobilized biomass, and microwave versus convection heating. Biogas production was the highest in the hybrid bioreactor heated by microwaves (385L/kg VS) and also the most stable, as shown by the FOS/TAC ratio and pH. Regardless of the type of heating, biogas production was 8% higher with immobilized biomass than without. Although the lag phase of biogas production was shorter with microwave heating than without, the log phase was longer, and biogas production in the microwave heated bioreactors took about twice as long (ca. 40days) to plateau as in the conventionally heated bioreactors. These differences in the profile of biogas production are likely due to the athermal effects of microwave irradiation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Artificial color perception using microwaves

    CERN Document Server

    Choudhury, Debesh

    2013-01-01

    We report the feasibility of artificial color perception under microwave illumination using a standard microwave source and an antenna. We have sensed transmitted microwave power through color objects and have distinguished the colors by analyzing the sensed transmitted power. Experiments are carried out using a Gunn diode as the microwave source, some colored liquids as the objects and a microwave diode as the detector. Results are presented which open up an unusual but new way of perceiving colors using microwaves.

  5. Observation of deep convection initiation from shallow convection environment

    Science.gov (United States)

    Lothon, Marie; Couvreux, Fleur; Guichard, Françoise; Campistron, Bernard; Chong, Michel; Rio, Catherine; Williams, Earle

    2010-05-01

    In the afternoon of 10 July 2006, deep convective cells initiated right in the field of view of the Massachusetts Institute Technology (MIT) C-band Doppler radar. This radar, with its 3D exploration at 10 min temporal resolution and 250 m radial resolution, allows us to track the deep convective cells and also provides clear air observations of the boundary layer structure prior to deep convection initiation. Several other observational platforms were operating then which allow us to thoroughly analyse this case: Vertically pointing aerosol lidar, W-band radar and ceilometer from the ARM Mobile Facility, along with radiosoundings and surface measurements enable us to describe the environment, from before their initiation to after the propagation of of one propagating cell that generated a circular gust front very nicely caught by the MIT radar. The systems considered here differ from the mesoscale convective systems which are often associated with African Easterly Waves, increasing CAPE and decreasing CIN. The former have smaller size, and initiate more locally, but there are numerous and still play a large role in the atmospheric circulation and scalar transport. Though, they remain a challenge to model. (See the presentation by Guichard et al. in the same session, for a model set up based on the same case, with joint single-column model and Large Eddy Simulation, which aims at better understanding and improving the parametrisation of deep convection initiation.) Based on the analysis of the observations mentioned above, we consider here the possible sources of deep convection initiation that day, which showed a typical boundary-layer growth in semi-arid environment, with isolated deep convective events.

  6. Surface effects on the microwave backscatter and emission of snow

    Science.gov (United States)

    Fung, A. K.; Stiles, W. H.; Ulaby, F. T.

    1980-01-01

    Measurements were performed with active and passive microwave sensors for both dry and wet snow conditions. A layer of Rayleigh scatterers with irregular surface boundaries is found to be a reasonable model for interpreting passive and active measurements in X- and Ku-bands. It was found that roughness had a significant effect on both backscatter and emission from wet snow; however, only a small effect was noted for dry snow.

  7. Microwave milk pasteurization without food safety risk

    Directory of Open Access Journals (Sweden)

    Gábor Géczi

    2013-02-01

    Full Text Available 96 Normal 0 false false false CS JA X-NONE According to nutrition science, milk and milk products are essential food for humans. The primary processing of milk includes its storage, separation, homogenization and the pasteurization process as well. The latter is a kind of heat treatment, which has been used to extend the storage life of food since the late 18th century. Although heat treatment of milk can be achieved through the use of microwave technology, the inhomogeneity of electromagnetic fields leads to an uneven distribution of temperature in the food products, therefore precluding their use in industry. The pasteurization operation is very often Critical Controll Point (CCP according of food safety systems. In recent years our research team has developed continuously operating heat treatment pilot-plant equipment, capable of measuring and contrasting the effects of different heat treatment methods, such as thermostat-controlled water baths and microwave energy, on liquid food products. We examined and compared protein, fat and bacterial content in samples of fresh cow milk with heat-treated cow milk samples. In addition, storage experiments were carried out under a microscope and recordings made of fat globules. Our results so far show that the microwave heat treatment is equivalent to the convection manner pasteurization technology, as we found no difference between the heat-treated products.doi:10.5219/260

  8. NOVEL MICROWAVE FILTER DESIGN TECHNIQUES.

    Science.gov (United States)

    ELECTROMAGNETIC WAVE FILTERS, MICROWAVE FREQUENCY, PHASE SHIFT CIRCUITS, BANDPASS FILTERS, TUNED CIRCUITS, NETWORKS, IMPEDANCE MATCHING , LOW PASS FILTERS, MULTIPLEXING, MICROWAVE EQUIPMENT, WAVEGUIDE FILTERS, WAVEGUIDE COUPLERS.

  9. Characteristics of the microwave pyrolysis and microwave CO2-assisted gasification of dewatered sewage sludge.

    Science.gov (United States)

    Chun, Young Nam; Jeong, Byeo Ri

    2017-07-28

    Microwave drying-pyrolysis or drying-gasification characteristics were examined to convert sewage sludge into energy and resources. The gasification was carried out with carbon dioxide as a gasifying agent. The examination results were compared with those of the conventional heating-type electric furnace to compare both product characteristics. Through the pyrolysis or gasification, gas, tar, and char were generated as products. The produced gas was the largest component of each process, followed by the sludge char and the tar. During the pyrolysis process, the main components of the produced gas were hydrogen and carbon monoxide, with a small amount of hydrocarbons such as methane and ethylene. In the gasification process, however, the amount of carbon monoxide was greater than the amount of hydrogen. In microwave gasification, a large amount of heavy tar was produced. The largest amount of benzene in light tar was generated from the pyrolysis or gasification. Ammonia and hydrogen cyanide, which are precursors of NOx, were also generated. In the microwave heating method, the sludge char produced by pyrolysis and gasification had pores in the mesopore range. This could be explained that the gas obtained from the microwave pyrolysis or gasification of the wet sewage sludge can be used as an alternative fuel, but the tar and NOx precursors in the produced gas should be treated. Sludge char can be used as a biomass solid fuel or as a tar removal adsorbent if necessary.

  10. The Cosmic Microwave Background

    OpenAIRE

    Silk, Joseph

    2002-01-01

    This set of lectures provides an overview of the basic theory and phenomenology of the cosmic microwave background. Topics include a brief historical review; the physics of temperature and polarization fluctuations; acoustic oscillations of the primordial plasma; the space of inflationary cosmological models; current and potential constraints on these models from the microwave background; and constraints on inflation.

  11. Microwave Enhanced Reactive Distillation

    NARCIS (Netherlands)

    Altman, E.

    2011-01-01

    The application of electromagnetic irradiation in form of microwaves (MW) has gathered the attention of the scientific community in recent years. MW used as an alternative energy source for chemical syntheses (microwave chemistry) can provide clear advantages over conventional heating methods in ter

  12. Drying: a key-step of your industrial process; Le sechage: une etape cle de votre process industriel

    Energy Technology Data Exchange (ETDEWEB)

    Steinmetz, D. [Ecole Nationale Superieure d' Ingenieurs en Arts Chimiques et Technologiques, ENSIACET, 31 - Toulouse (France); Leconte, J.M. [NEU Sechage Industriel, 59 - Templemars (France); Gayot, A. [Faculte de Pharmacie de Lille, 59 (France)] [and others

    2001-03-01

    This document brings together 13 testimonies of experts about the drying techniques used in industrial processes. The following points are approached: understanding and mastering of drying parameters: characterization of the products do be dried, affinity between product and solvent, humidity retaking, energy transfer..; domains of applications of the main drying techniques: conduction drying, atomization process, fluidized bed drying, microwave drying; which help drying engineering can provide to industrial processes (optimization and operation); industrial applications and case studies in pharmacy, chemistry and agriculture and food industry. (J.S.)

  13. The Influence of Different Drying Methods on Constituents and Antioxidant Activity of Saffron from China

    Directory of Open Access Journals (Sweden)

    Yingpeng Tong

    2015-01-01

    Full Text Available More and more saffron has been cultivated in China because of the increasing saffron demand, but no paper has studied the influence of drying methods on the quality of Chinese saffron. In this paper, three different dehydration treatments applied in actual production were evaluated: dehydration with electric oven, vacuum oven, and microwave. We determined that the highest quality of saffron will be obtained when fresh saffron is treated at higher temperatures (no more than 70°C for a long time by electric oven drying and vacuum oven drying. In microwave drying, treatments at lower microwave power and longer time benefit the quality of saffron. In addition, the influence of the drying method on antioxidants in saffron is discussed. The correlation between individual saffron profiles and the antioxidant value was estimated by spectrum-effect relationships analysis.

  14. Microwave energy for post-calcination treatment of high-level nuclear wastes

    Energy Technology Data Exchange (ETDEWEB)

    Gombert, D.; Priebe, S.J.; Berreth, J.R.

    1980-01-01

    High-level radioactive wastes generated from nuclear fuel reprocessing require treatment for effective long-term storage. Heating by microwave energy is explored in processing of two possible waste forms: (1) drying of a pelleted form of calcined waste; and (2) vitrification of calcined waste. It is shown that residence times for these processes can be greatly reduced when using microwave energy rather than conventional heating sources, without affecting product properties. Compounds in the waste and in the glass frit additives couple very well with the 2.45 GHz microwave field so that no special microwave absorbers are necessary.

  15. Headspace single drop microextraction coupled with microwave extraction of essential oil from plant materials.

    Science.gov (United States)

    Zhai, Yujuan; Sun, Shuo; Wang, Ziming; Zhang, Yupu; Liu, He; Sun, Ye; Zhang, Hanqi; Yu, Aimin

    2011-05-01

    Headspace single drop microextraction (HS-SDME) coupled with microwave extraction (ME) was developed and applied to the extraction of the essential oil from dried Syzygium aromaticum (L.) Merr. et Perry and Cuminum cyminum L. The operational parameters, such as microdrop volume, microwave absorption medium (MAM), extraction time, and microwave power were optimized. Ten microliters of decane was used as the microextraction solvent. Ionic liquid and carbonyl iron powder were used as MAM. The extraction time was less than 7 min at the microwave power of 440 W. The proposed method was compared with hydrodistillatio