Search results for: drying shrinkage

Authors: Vijay R. Khawale, Shashank B. Thakare

Abstract:

The experiment was carried out to study the performance of solar crop dryer coupled with reversed absorber type solar air heater (SD2). Excel software is used to analyse the raw data obtained from the drying experiment to develop a model. An attempt is made in this paper to correlate the collector efficiency, dryer efficiency and pick-up efficiency. All these efficiencies are dependent on the parameters such as solar flux, ambient temperature, collector outlet temperature and moisture content. The simulation equation was developed to predict the values of collector efficiency. The parameters a, n and drying constant k were determined from a plot of curve using a drying models. Experimental data of drying red chili in conventional solar dryer and solar dryer coupled with reversed absorber solar air heater was compared by fitting with three drying models. The moisture content will be rapidly reduced in solar dryer with reversed absorber due to higher drying temperatures. The best fit model was selected to describe the drying behavior of red chili. For SD2 the values of the coefficient of determination (R²=0.997), mean bias error (MBE=0.00026) and root mean square error (RMSE=0.016) were used to determine the goodness or the quality of the fit. Pages model showed a better fit to drying red chili among Newton model and Henderson & Pabis model.

Keywords: Solar dryer, red chili, reversed absorber, reflector, Buckingham pi theorem, drying model.

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Authors: Fang Yao, Minglei Chen

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City shrinkage is one of the thorny problems that many European cities have to face with nowadays. It is mainly expressed as the decrease of population in these cities. Eastern Germany is one of the pioneers of European shrinking cities with long shrinking history. The paper selects one representative shrinking city Halle (Saale) in eastern Germany as research objective, collecting and investigating nearly 20 years (1993-2010) municipal data after the reunification of Germany. These data based on five dimensions, which are demographic, economic, social, spatial and environmental and total 16 eligible variables. Factor Analysis is used to deal with these variables in order to assess the most important factors affecting shrinking Halle. The results show that there are three main factors determine the shrinkage of Halle, respectively named “demographical and economical factor”, “social stability factor”, and “city vitality factor”. The three factors act at different time period of Halle’s shrinkage: from 1993 to 1997 the demographical and economical factor played an important role; from 1997 to 2004 the social stability factor is significant to city shrinkage; since 2005 city vitality factor determines the shrinkage of Halle. In recent years, the shrinkage in Halle mitigates that shows the sign of growing population. Thus the city Halle should focus on attaching more importance on the city vitality factor to prevent the city from shrinkage. Meanwhile, the city should possess a positive perspective to shift the growth-oriented development to tap the potential of shrinking cities. This method is expected to apply to further research and other shrinking cities

Keywords: Demography, Factor analysis, Halle, Shrinking cities.

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Authors: M. Eckert, M. Oliveira

Abstract:

The intensive use of natural aggregates, near cities and towns, associated to the increase of the global population, leads to its depletion and increases the transport distances. The uncontrolled deposition of construction and demolition waste in landfills and city outskirts, causes pollution and takes up space. The use of recycled aggregates in concrete preparation would contribute to mitigate the problem. However, it arises the problem that the high water absorption of recycled aggregate decreases the bleeding rate of concrete, and when this gets lower than the evaporation rate, plastic shrinkage cracking occurs. This phenomenon can be particularly problematic in hot and windy curing environments. Cracking facilitates the flow of liquid and gas into concrete which attacks the reinforcement and degrades the concrete. These factors reduce the durability of concrete structures and consequently the lifetime of buildings. A ring test was used, cured in a wind tunnel, to evaluate the plastic shrinkage cracking sensitivity of recycled aggregate concrete, in order to implement preventive means to control this phenomenon. The role of several aggregate properties on the concrete segregation and cracking mechanisms were also discussed.

Keywords: Recycled Aggregate, Plastic Shrinkage Cracking; Wind Tunnel, Durability.

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Authors: L.Wiset, N. Poomsa-ad, V. Srilaong

Abstract:

The peel of dragon fruit is a byproduct left over after consuming. Normally, the use of plants as antioxidant source must be dried before further process. Therefore, the aim of this study is interesting to dry the peel by heat pump dryer (45 ºC) and fluidized bed dryer (110 º C) compared with the sun drying method. The sample with initial moisture content of about 85-91% wet basis was dried down to about 10% wet basis where it took 620 and 25 min for heat pump dryer and fluidized bed dryer, respectively. However, the sun drying took about 900 min to dry the peel. After that, sample was evaluated antioxidant activity, -carotene and betalains contents. The results found that the antioxidant activity and betalains contents of dried peel obtained from heat pump and fluidized bed dryings were significantly higher than that sun drying (p 0.05). Moreover, the drying by heat pump provided the highest -carotene content.

Keywords: Pitaya, betalains, β-carotene, antioxidant.

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Authors: Marco Soares dos Santos, Camila Nicola Boeri, Jorge Augusto Ferreira, Fernando Neto da Silva

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The highly nonlinear characteristics of drying processes have prompted researchers to seek new nonlinear control solutions. However, the relation between the implementation complexity, on-line processing complexity, reliability control structure and controller-s performance is not well established. The present paper proposes high performance nonlinear fuzzy controllers for a real-time operation of a drying machine, being developed under a consistent match between those issues. A PCI-6025E data acquisition device from National Instruments® was used, and the control system was fully designed with MATLAB® / SIMULINK language. Drying parameters, namely relative humidity and temperature, were controlled through MIMOs Hybrid Bang-bang+PI (BPI) and Four-dimensional Fuzzy Logic (FLC) real-time-based controllers to perform drying tests on biological materials. The performance of the drying strategies was compared through several criteria, which are reported without controllers- retuning. Controllers- performance analysis has showed much better performance of FLC than BPI controller. The absolute errors were lower than 8,85 % for Fuzzy Logic Controller, about three times lower than the experimental results with BPI control.

Keywords: Drying control, Fuzzy logic control, Intelligent temperature-humidity control.

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Authors: M. O. Oke, T. S. Workneh

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Drying behavior of blanched sweet potato in a cabinet dryer using different five air temperatures (40-80°C) and ten sweet potato varieties sliced to 5mm thickness were investigated. The drying data were fitted to eight models. The Modified Henderson and Pabis model gave the best fit to the experimental moisture ratio data obtained during the drying of all the varieties while Newton (Lewis) and Wang and Singh models gave the least fit. The values of Deff obtained for Bophelo variety (1.27 x 10-9 to 1.77 x 10-9 m2/s) was the least while that of S191 (1.93 x 10-9 to 2.47 x 10-9 m2/s) was the highest which indicates that moisture diffusivity in sweet potato is affected by the genetic factor. Activation energy values ranged from 0.27-6.54 kJ/mol. The lower activation energy indicates that drying of sweet potato slices requires less energy and is hence a cost and energy saving method. The drying behavior of blanched sweet potato was investigated in a cabinet dryer. Drying time decreased considerably with increase in hot air temperature. Out of the eight models fitted, the Modified Henderson and Pabis model gave the best fit to the experimental moisture ratio data on all the varieties while Newton, Wang and Singh models gave the least. The lower activation energy (0.27 - 6.54 kJ/mol) obtained indicates that drying of sweet potato slices requires less energy and is hence a cost and energy saving method.

Keywords: Sweet Potato Slice, Drying Models, Moisture Ratio, Moisture Diffusivity, Activation Energy.

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Authors: D. S. C. Soares, D. G. Costa, J. T. S., A. K. S. Abud, T. P. Nunes, A. M. Oliveira Júnior

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Mathematical models of drying are used for the purpose of understanding the drying process in order to determine important parameters for design and operation of the dryer. The jackfruit is a fruit with high consumption in the Northeast and perishability. It is necessary to apply techniques to improve their conservation for longer in order to diffuse it by regions with low consumption. This study aimed to analyze several mathematical models (Page, Lewis, and Midilli) to indicate one that best fits the conditions of convective drying process using performance indicators associated with each model: accuracy (Af) and noise factors (Bf), mean square error (RMSE) and standard error of prediction (% SEP). Jackfruit drying was carried out in convective type tray dryer at a temperature of 50°C for 9 hours. It is observed that the model Midili was more accurate with Af: 1.39, Bf: 1.33, RMSE: 0.01%, and SEP: 5.34. However, the use of the Model Midilli is not appropriate for purposes of control process due to need four tuning parameters. With the performance indicators used in this paper, the Page model showed similar results with only two parameters. It is concluded that the best correlation between the experimental and estimated data is given by the Page’s model.

Keywords: Drying, models, jackfruit.

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Authors: Azza A. Abou-Arab, Ferial M. Abu-Salem

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The influence of microwave drying methods on the nutritional and anti-nutritional composition and physical characteristics of banana peels was investigated. Banana peels were assessed for physical properties such as yield, pH value, bulk density, water holding capacity (WHC) and oil holding capacity (OHC). The results showed that, the yield of banana peels and pH value was significantly (P < 0.05) decreased by microwave drying (11.20% and pH 5.08, respectively) compared with control. Bulk density was increased by microwave drying and recorded 62.03 g/100 ml. The banana peels flour demonstrated that the highest WHC was 8.65 g water/g dry sample and OHC was 6.73 g oil/g dry sample compared to control. The results observed a significant decrease (P < 0.05) in moisture, fiber and total carbohydrates content of banana peels; whereas, the rates of ash, protein and fat content were increased after drying by microwave compared with control. The lignin content of banana peels was significantly increased (P < 0.05) by microwave drying and the recorded value was 8.31% dw. The results also revealed that the ascorbic acid content was significantly decreased by microwave drying and recorded 18.32 mg/100 g dw vis. 23.51 mg/100 g dw for control. With regarding the anti-nutrients, phytates, alkaloids, oxalates and hydrogen cyanides levels in banana peels, it was in the threshold value mentioned as safety restrict. These results demonstrated that the levels of phytates, alkaloids, oxalates and hydrogen cyanides were decreased by microwave drying methods which recorded 4.07%, 5.45%, 0.85% and 32.15%, respectively.

Keywords: Banana peels, microwave drying, physical characteristics, nutritional composition, anti-nutritional composition.

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Authors: Kenia Martínez, Geniel Talavera, Juan Alonso

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Moringa oleifera is a plant containing many nutrients that are mostly concentrated within the leaves. Commonly, the separation process of these nutrients involves solid-liquid extraction followed by evaporation and drying to obtain a concentrated extract, which is rich in proteins, vitamins, carbohydrates, and other essential nutrients that can be used in the food industry. In this work, three drying methods were used, which involved very different temperature and pressure conditions, to evaluate the effect of each method on the vitamin C content and the antioxidant efficiency of the extracts. Solid-liquid extractions of Moringa leaf (LE) were carried out by employing an ethanol solution (35% v/v) at 50 °C for 2 hours. The resulting extracts were then dried i) in a convective oven (CO) at 100 °C and at an atmospheric pressure of 750 mbar for 8 hours, ii) in a vacuum evaporator (VE) at 50 °C and at 300 mbar for 2 hours, and iii) in a freeze-drier (FD) at -40 °C and at 0.050 mbar for 36 hours. The antioxidant capacity (EC₅₀, mg solids/g DPPH) of the dry solids was calculated by the free radical inhibition method employing DPPH˙ at 517 nm, resulting in a value of 2902.5 ± 14.8 for LE, 3433.1 ± 85.2 for FD, 3980.1 ± 37.2 for VE, and 8123.5 ± 263.3 for CO. The calculated antioxidant efficiency (AE, g DPPH/(mg solids·min)) was 2.920 × 10^-5 for LE, 2.884 × 10^-5 for FD, 2.512 × 10^-5 for VE, and 1.009 × 10^-5 for CO. Further, the content of vitamin C (mg/L) determined by HPLC was 59.0 ± 0.3 for LE, 49.7 ± 0.6 for FD, 45.0 ± 0.4 for VE, and 23.6 ± 0.7 for CO. The results indicate that the convective drying preserves vitamin C and antioxidant efficiency to 40% and 34% of the initial value, respectively, while vacuum drying to 76% and 86%, and freeze-drying to 84% and 98%, respectively.

Keywords: Antioxidant efficiency, convective drying, freeze-drying, Moringa oleifera, vacuum drying, vitamin C content.

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Authors: Avdhesh K. Sharma

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Formulation for drying and pyrolysis process in packed beds at slow heating rates is presented. Drying of biomass particles bed is described by mass diffusion equation and local moisture-vapour-equilibrium relations. In gasifiers, volatilization rate during pyrolysis of biomass is modeled by using apparent kinetic rate expression, while product compositions at slow heating rates is modeled using empirical fitted mass ratios (i.e., CO/CO₂, ME/CO₂, H₂O/CO₂) in terms of pyrolysis temperature. The drying module is validated fairly with available chemical kinetics scheme and found that the testing zone in gasifier bed constituted of relatively smaller particles having high airflow with high isothermal temperature expedite the drying process. Further, volatile releases more quickly within the shorter zone height at high temperatures (isothermal). Both, moisture loss and volatile release profiles are found to be sensitive to temperature, although the influence of initial moisture content on volatile release profile is not so sensitive.

Keywords: Modeling downdraft gasifier, drying, pyrolysis, moist woody biomass.

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Authors: Azza A. Abou-Arab, Marwa H. Mahmoud, Ferial M. Abu-Salem

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The present investigation studied the content of bioactive compounds as ascorbic acid, β-carotene, and flavonoids, and the effect of drying methods (microwave, solar, and air oven drying) on its level in citrus peel. These levels were decreased significantly (p <0.05) due to the dried methods. The percentage of ascorbic acid content loss of orange C. Valencia were 46.64, 52.95 and 68.83% with microwave, solar and air oven methods, respectively comparing to fresh samples. Also, the percentages of β- carotene loss of orange C. Valencia were 38.89, 52.42 and 87.14% with microwave, solar and air oven methods, respectively. Total flavonoid content recorded 453.33, 396.67 and 327.50 mg QE/100g dw, with dried by microwave, solar and oven methods, respectively compared with control in orange, C. valencia. These results revealed that microwave drying procedure was the most effective method which maintained citrus bioactive compounds content (ascorbic acid, β-carotene and flavonoid) followed by solar. On the other hand, air oven drying came in the last order due to direct heat treatment.

Keywords: Ascorbic acid, β-carotene, flavonoids, microwave, solar, air oven drying.

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Authors: D. Zare, H. Naderi, A. A. Jafari

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Drying characteristics of rough rice (variety of lenjan) with an initial moisture content of 25% dry basis (db) was studied in a hot air dryer assisted by infrared heating. Three arrival air temperatures (30, 40 and 500C) and four infrared radiation intensities (0, 0.2 , 0.4 and 0.6 W/cm2) and three arrival air speeds (0.1, 0.15 and 0.2 m.s-1) were studied. Bending strength of brown rice kernel, percentage of cracked kernels and time of drying were measured and evaluated. The results showed that increasing the drying arrival air temperature and radiation intensity of infrared resulted decrease in drying time. High bending strength and low percentage of cracked kernel was obtained when paddy was dried by hot air assisted infrared dryer. Between this factors and their interactive effect were a significant difference (p<0.01). An intensity level of 0.2 W/cm2 was found to be optimum for radiation drying. Furthermore, in the present study, the application of Artificial Neural Network (ANN) for predicting the moisture content during drying (output parameter for ANN modeling) was investigated. Infrared Radiation intensity, drying air temperature, arrival air speed and drying time were considered as input parameters for the model. An ANN model with two hidden layers with 8 and 14 neurons were selected for studying the influence of transfer functions and training algorithms. The results revealed that a network with the Tansig (hyperbolic tangent sigmoid) transfer function and trainlm (Levenberg-Marquardt) back propagation algorithm made the most accurate predictions for the paddy drying system. Mean square error (MSE) was calculated and found that the random errors were within and acceptable range of ±5% with coefficient of determination (R2) of 99%.

Keywords: Rough rice, Infrared-hot air, Artificial Neural Network

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Authors: Nickson Kipng’etich Lang’at, Thomas Thoruwa, John Abraham, John Wanyoko

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Green tea is made from the top two leaves and buds of a shrub, Camellia sinensis, of the family Theaceae and the order Theales. The green tea leaves are picked and immediately sent to be dried or steamed to prevent fermentation. Fluid bed drying technique is a common drying method used in drying green tea because of its ease in design and construction and fluidization of fine tea particles. Major problems in this method are significant loss of chemical content of the leaf and green appearance of tea, retention of high moisture content in the leaves and bed channeling and defluidization. The energy associated with the drying technology has been shown to be a vital factor in determining the quality of green tea. As part of the implementation, prototype dryer was built that facilitated sequence of operations involving steaming, cooling, pre-drying and final drying. The major findings of the project were in terms of quality characteristics of tea leaves and energy consumption during processing. The optimal design achieved a moisture content of 4.2 ± 0.84%. With the optimum drying temperature of 100 ºC, the specific energy consumption was 1697.8 kj.Kg^-1 and evaporation rate of 4.272 x 10^-4 Kg.m^-2.s^-1. The energy consumption in a fluidized system can be further reduced by focusing on energy saving designs.

Keywords: Evaporation rate, fluid bed dryer, maceration, specific energy consumption.

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Authors: Sky Chou, Joseph C. Chen

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This paper focuses on using six sigma methodologies to reach the desired shrinkage of a manufactured high-density polyurethane (HDPE) part produced by the injection molding machine. It presents a case study where the correct shrinkage is required to reduce or eliminate defects and to improve the process capability index Cp and Cpk for an injection molding process. To improve this process and keep the product within specifications, the six sigma methodology, design, measure, analyze, improve, and control (DMAIC) approach, was implemented in this study. The six sigma approach was paired with the Taguchi methodology to identify the optimized processing parameters that keep the shrinkage rate within the specifications by our customer. An L9 orthogonal array was applied in the Taguchi experimental design, with four controllable factors and one non-controllable/noise factor. The four controllable factors identified consist of the cooling time, melt temperature, holding time, and metering stroke. The noise factor is the difference between material brand 1 and material brand 2. After the confirmation run was completed, measurements verify that the new parameter settings are optimal. With the new settings, the process capability index has improved dramatically. The purpose of this study is to show that the six sigma and Taguchi methodology can be efficiently used to determine important factors that will improve the process capability index of the injection molding process.

Keywords: Injection molding, shrinkage, six sigma, Taguchi parameter design.

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Authors: Fatima Setti, Ezziane Karim, Setti Bakhti, Negadi Kheira

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The objective of this study is to present and to analyze the feasibility of using steel fibers as reinforcement in the cementations matrix to minimize the effect of free shrinkage which is a major cause of cracks that have can observe on concrete structures, also to improve the mechanical resistances of this concrete reinforced. The experimental study was performed on specimens with geometric characteristics adapted to the testing. The tests of shrinkage apply on prismatic specimens, equipped with rods fixed to the ends with different dosages of fibers, it should be noted that the fibers used are hooked end of 50mm length and 67 slenderness. The results show that the compressive strength and flexural strength increases as the degree of incorporation of fibbers increases. And the shrinkage deformations are generally less important for fibers-reinforced concrete to those appearing in the concrete without fibers.

Keywords: Concrete, Steel fibers, Compression, Flexural, Deformation.

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Authors: Jafar Hashemi, Reza Tabatabaekoloor, Toshinori Kimura

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The study of interaction among the grain, moisture, and the surrounding space (air) is key to understanding the graindrying process. In Iran, rice (mostly Indica type) is dried by flat bed type dryer until the final MC reaches to 6 to 8%. The experiments were conducted to examine the effect of application of discharge fan with different heights of paddy on the drying efficiency. Experiments were designed based on two different configurations of the drying methods; with and without discharge fan with three different heights of paddy including; 5, 10, and 15 cm. The humid heated air will be going out immediately by the suction of discharge fan. The drying time is established upon the average final MC to achieve about 8%. To save energy and reduce the drying time, the distribution of temperature between layers should be fast and uniform with minimum difference; otherwise the difference of MC gradient between layers will be high and will induce grain breakage. The difference of final MC between layers in the two methods was 48-73%. The steady state of temperature between the two methods has saved time in the range of 10-20%, and the efficiency of temperature distribution increased 17-26% by the use of discharge fan.

Keywords: FBT Dryer, Final MC, Discharge Fan.

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Authors: Boris Golman, Wittaya Julklang

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The heat and mass transfer was investigated during the falling rate period of spray drying of a slurry droplet. The effect of the porosity of crust layer formed from primary particles during liquid evaporation was studied numerically using the developed mathematical model which takes into account the heat and mass transfer in the core and crust regions, the movement of the evaporation interface, and the external heat and mass transfer between the drying air and the droplet surface. It was confirmed that the heat transfer through the crust layer was more intense in the case of the dense droplet than the loose one due to the enhanced thermal conduction resulting in the higher average droplet temperature. The mass transfer was facilitated in the crust layer of loose droplet owing to the large pore space available for diffusion of water vapor from the evaporation interface to the outer droplet surface. The longer drying time is required for the droplet of high porosity to reach the final moisture content than that for the dense one due to the larger amount of water to be evaporated during the falling rate.

Keywords: Spray Drying, Slurry Droplet, Heat and Mass Transfer, Crust Layer Porosity, Mathematical Modeling.

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Authors: A. I. M. Ismail, N. Ryden

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This paper is concerned with the study of mineralogy and engineering characteristics of soil materials derived from the eastern part of Nile Delta. The clay minerals of the studied soil by using X- ray diffraction are mainly illite (average 72.6 %) and kaolinite (average 2.6 %), expandable portion in illite-smectite mixed layer (average 7 %). Smectite is more abundant in fluviatile clays, whereas kaolinite is more abundant in lagoonal clays. On the other hand, illite and illite-smectite are more abundant in marine clays. The geotechnical results show that the soil under study consists mainly of about 0.3 % gravel, 5 % sand, 51.5 % silt and 42.2 % clay in average. The average shrinkage limit attains 11 % whereas the average value of the plasticity index is 23.4 %. The free swelling ranges from 40 % to 75 % and has a value of 55 % giving an indication about the inadequacy of such soil under foundations. From a construction point of view, the soil under investigation poses many problems even under light foundations due to the swelling and shrinkage. Such swelling and shrinkage is due to the high content of soil materials in the expandable clay minerals of illite and smectite. Based on the results of the present and earlier studies, trial application of soil stabilisation is recommended.

Keywords: Engineering Geological Investigations, Nile Delta, Swelling, Shrinkage

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Authors: Rajendra K. Ray, Kim Dan Nguyen

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An unstructured finite volume numerical model is presented here for simulating shallow-water flows with wetting and drying fronts. The model is based on the Green-s theorem in combination with Chorin-s projection method. A 2nd-order upwind scheme coupled with a Least Square technique is used to handle convection terms. An Wetting and drying treatment is used in the present model to ensures the total mass conservation. To test it-s capacity and reliability, the present model is used to solve the Parabolic Bowl problem. We compare our numerical solutions with the corresponding analytical and existing standard numerical results. Excellent agreements are found in all the cases.

Keywords: Finite volume method, Projection method, Shallow water, Unstructured grid, wetting/drying fronts.

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Authors: Keshav Pujeri, Pranesh Jain, Krutibas Panda

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Significant changes in oil and gas drilling have emphasized the need to verify the integrity and reliability of drill stem components. Defects are inevitable in cast components, regardless of application; but if these defects go undetected, any severe defect could cause down-hole failure. One such defect is shrinkage porosity. Castings with lower level shrinkage porosity (CB levels 1 and 2) have scattered pores and do not occupy large volumes; so pressure testing and helium leak testing (HLT) are sufficient for qualifying the castings. However, castings with shrinkage porosity of CB level 3 and higher, behave erratically under pressure testing and HLT making these techniques insufficient for evaluating the castings- integrity. This paper presents a case study to highlight how the radiography technique is much more effective than pressure testing and HLT.

Keywords: Casting Defects, Interconnects, Leak Check, Pressure Test, Radiography.

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Authors: Rawichar Chaipojjana, Suttipong Phosuksirikul, Arunsri Leejeerajumnean

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The objective of the study was to select the survival of probiotic strains when exposed to acidic and bile salts condition. Four probiotic strains Lactobacillus casei subsp. rhamnosus TISTR 047, Lactobacillus casei TISTR 1500, Lactobacillus acidophilus TISTR 1338 and Lactobacillus plantarum TISTR 1465 were cultured in MRS broth and incubated at 35ºC for 15 hours before being inoculated into acidic condition 5 M HCl, pH 2 for 2 hours and bile salt 0.3%, pH 5.8 for 8 hour. The survived probiotics were counted in MRS agar. Among four stains, Lactobacillus casei subsp. rhamnosus TISTR 047 was the highest tolerance specie. Lactobacillus casei subsp. rhamnosus TISTR 047 reduced 6.74±0.07 log CFU/ml after growing in acid and 5.52±0.05 log CFU/ml after growing in bile salt. Then, double emulsion of microorganisms was chosen to encapsulate before spray drying. Spray drying was done with the inlet temperature 170ºC and outlet temperature 80ºC. The results showed that the survival of encapsulated Lactobacillus casei subsp. rhamnosus TISTR 047 after spray drying decreased from 9.63 ± 0.32 to 8.31 ± 0.11 log CFU/ml comparing with non-encapsulated, 9.63 ± 0.32 to 4.06 ± 0.08 log CFU/ml. Therefore, Lactobacillus casei subsp. rhamnosus TISTR 047 would be able to survive in gastrointestinal and spray drying condition.

Keywords: Probiotic, acid, bile salt, spray drying.

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Authors: R. Aminzadeh, M. Abarzani, J. Sargolzaei

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In this study, the kinetics of osmotic dehydration of melons (Tille variety) in a ternary system followed by air-drying for preserving melons in the summer to be used in the winter were investigated. The effect of different osmotic solution concentrations 30, 40 and 50% (w/w) of sucrose with 10% NaCl salt and fruit to solution ratios 1:4, 1:5 and 1:6 on the mass transfer kinetics during osmotic dehydration of melon in ternary solution namely sucrosesalt- water followed by air-drying were studied. The diffusivity of water during air-drying was enhanced after the fruit samples were immersed in the osmotic solution after 60 min. Samples non-treated and pre-treated during one hour in osmotic solutions with 60% (w/w) of sucrose with 10% NaCl salt and fruit to solution ratio of 1:4 were dried in a hot air-dryer at 60oC (2 m/s) until equilibrium was achieved.

Keywords: Air drying, Effective diffusion coefficient, Mass transfer kinetic, Melon, Osmotic dehydration.

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Authors: Yulu Zhang, Atushi Teramoto, Taka-Aki Ohkubo

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In this study, the effect of expansive additives on autogenous shrinkage and delayed expansion of ultra-high strength mortar was explored. The specimens made for the study were composed of ultra-high strength mortar, which was mixed with ettringite-lime composite type expansive additive. Two series of experiments were conducted with the specimens. The experimental results confirmed that the autogenous shrinkage of specimens was effectively decreased by increasing the proportion of the expansive additive. On the other hand, for the specimens, which had 7% expansive additive, and were cured for seven days at a constant temperature of 20°C, and then cured for a long time in either in an underwater, moist (Relative humidity: 100%) or dry air (Relative humidity: 60%) environment, excessively large expansion strain occurred. Specifically, typical turtle shell-like swelling expansion cracks were confirmed in the specimens that underwent long-term curing in an underwater and moist environment. According to the result of hydration analysis, the formation of expansive substances, calcium hydroxide and alumina, ferric oxide, tri-sulfate contribute to the occurrence of delayed expansion.

Keywords: Ultra-high strength mortar, expansive additive, autogenous shrinkage, delayed expansion.

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Authors: Amirali Ebrahimi, T. A. G. Langrish

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The effect of various humidities on process yields and degrees of crystallinity for spray-dried powders from spray drying of lactose with humid air in a straight-through system have been studied. It has been suggested by Williams–Landel–Ferry kinetics (WLF) that a higher particle temperature and lower glass-transition temperature would increase the crystallization rate of the particles during the spray-drying process. Freshly humidified air produced by a Buchi-B290 spray dryer as a humidifier attached to the main spray dryer decreased the particle glass-transition temperature (Tg), while allowing the particle temperature (Tp) to reach higher values by using an insulated drying chamber. Differential scanning calorimetry (DSC) and moisture sorption analysis were used to measure the degree of crystallinity for the spray-dried lactose powders. The results showed that higher Tp-Tg, as a result of applying humid air, improved the process yield from 21 ± 4 to 26 ± 2% and crystallinity of the particles by decreasing the latent heat of crystallization from 43 ± 1 to 30 ± 11 J/g and the sorption peak height from 7.3 ± 0.7% to 6 ± 0.7%.

Keywords: Lactose, crystallization, spray drying, humid air.

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Authors: R. Oonsivilai, N. Chaijareonudomroung, Y. Huantanom, A. Oonsivilai

Abstract:

The optimal extraction condition of dried Echinocactus grusonii powder was studied. The three independent variables are raw material drying temperature, extraction temperature, and extraction time. The dependent variables are both yield percentage of crude extract and total phenolic quantification as gallic acid equivalent in crude extract. The experimental design was based on central composite design. Highest yield percentage of crude extract could get from extraction condition at raw material drying temperature at 60°C, extraction temperature at 15°C, and extraction time for 25 min °C. Moreover, the crude extract with highest phenolic occurred by extraction condition of raw material drying temperature at 60°C, extraction temperature at 35 °C, and extraction lasting 25 min.

Keywords: Drying temperature, Extraction temperature, Optimal condition, Total phenolic

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Authors: B.S. Al-Tulaian, M. J. Al-Shannag, A.M. Al-Hozaimy

Abstract:

The development of new construction materials using  recycled plastic is important to both the construction and the plastic  recycling industries. Manufacturing of fibers from industrial or  postconsumer plastic waste is an attractive approach with such  benefits as concrete performance enhancement, and reduced needs  for land filling. The main objective of this study is to investigate the  effect of Plastic fibers obtained locally from recycled waste on plastic  shrinkage cracking of ordinary cement based mortar. Parameters  investigated include: fiber length ranging from 20 to 50mm, and fiber  volume fraction ranging from 0% to 1.5% by volume. The test results  showed significant improvement in crack arresting mechanism and  substantial reduction in the surface area of cracks for the mortar  reinforced with recycled plastic fibers compared to plain mortar.  Furthermore, test results indicated that there was a slight decrease in  compressive strength of mortar reinforced with different lengths and  contents of recycled fibers compared to plain mortar. This study  suggests that adding more than 1% of RP fibers to mortar, can be  used effectively for controlling plastic shrinkage cracking of cement  based mortar, and thus results in waste reduction and resources  conservation.

 

Keywords: Mortar, plastic, shrinkage cracking, compressive strength, RF recycled fibers.

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Authors: Mario Mastriani, Alberto E. Giraldez

Abstract:

In this paper, a new probability density function (pdf) is proposed to model the statistics of wavelet coefficients, and a simple Kalman-s filter is derived from the new pdf using Bayesian estimation theory. Specifically, we decompose the speckled image into wavelet subbands, we apply the Kalman-s filter to the high subbands, and reconstruct a despeckled image from the modified detail coefficients. Experimental results demonstrate that our method compares favorably to several other despeckling methods on test synthetic aperture radar (SAR) images.

Keywords: Kalman's filter, shrinkage, speckle, wavelets.

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Authors: D. E. Omomo, R. M. Sunday, I. Kareem

Abstract:

This study was carried out to evaluate the nutritional composition of the African River Prawn (Macrobrachium vollenhovenii) in relation to Chokor (traditional) and Altona (improved traditional) drying techniques used in the preservation and processing of prawns by carrying out proximate composition analysis. The value obtained for the proximate analysis of Chokor and Altona smoke dried prawns were; Moisture (14.90% and 15.15%), Dry matter (85.10% and 84.85%), Protein (55.80% and 58.87%), Crude fat (1.95% and 1.98%), Crude fibre (21.40% and 13.11%), Carbohydrate (0.54% and 0.54%) and Ash (19.76% and 15.86%) respectively. The proximate mineral composition of Chokor and Altona smoke dried prawns were; Calcium (5.66% and 4.20%) and Phosphorus (9. 22% and 6.34%) respectively. Result shows there was no loss of nutritional value with respect to Chokor and Altona drying techniques used in the processing of prawns.

Keywords: Altona, Chokor, Macrobrachium vollenhovenii, Proximate composition, Smoke drying.

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Authors: Samy M. El-Behery, W. A. El-Askary, K. A. Ibrahim, Mofreh H. Hamed

Abstract:

A steady two-phase flow model has been developed to simulate the drying process of porous particle in a pneumatic conveying dryer. The model takes into account the momentum, heat and mass transfer between the continuous phase and the dispersed phase. A single particle model was employed to calculate the evaporation rate. In this model the pore structure is simplified to allow the dominant evaporation mechanism to be readily identified at all points within the duct. The predominant mechanism at any time depends upon the pressure, temperature and the diameter of pore from which evaporating is occurring. The model was validated against experimental studies of pneumatic transport at low and high speeds as well as pneumatic drying. The effects of operating conditions on the dryer parameters are studied numerically. The present results show that the drying rate is enhanced as the inlet gas temperature and the gas flow rate increase and as the solid mass flow rate deceases. The present results also demonstrate the necessity of measuring the inlet gas velocity or the solid concentration in any experimental analysis.

Keywords: Two-phase, gas-solid, pneumatic drying, pneumatic conveying, heat and mass transfer

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Authors: S. Ismail, Z. Yaacob

Abstract:

The main aim of this research is to study the possible use of recycled fine aggregate made from waste rubble wall to substitute partially for the natural sand used in the production of cement and sand bricks. The bricks specimens were prepared by using 100% natural sand; they were then replaced by recycled fine aggregate at 25, 50, 75, and 100% by weight of natural sand. A series of tests was carried out to study the effect of using recycled aggregate on the physical and mechanical properties of bricks, such as density, drying shrinkage, water absorption characteristic, compressive and flexural strength. Test results indicate that it is possible to manufacture bricks containing recycled fine aggregate with good characteristics that are similar in physical and mechanical properties to those of bricks with natural aggregate, provided that the percentage of recycled fine aggregates is limited up to 50-75%.

Keywords: Bricks, cement, recycled aggregate, sand

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