Design and Construction
M. Rezaei; J. Khodaei; B. Astinchap
Abstract
IntroductionDue to the increasing need for agricultural products, protection of products against pathogens and preventing them from being wasted is important. Studies on droplet charging systems result in the reduction of chemical usage and an increase in the deposition of droplets on the target. Conventional ...
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IntroductionDue to the increasing need for agricultural products, protection of products against pathogens and preventing them from being wasted is important. Studies on droplet charging systems result in the reduction of chemical usage and an increase in the deposition of droplets on the target. Conventional sprayers used in Iran have numerous disadvantages such as drift, environmental pollution, lack of complete and homogeneous coverage of the spraying surface, phytotoxicity, and crop losses. Therefore, evaluation of new spraying methods and using a variety of electrical sprayers as alternatives to conventional spraying is essential. This study aims to design, construct, and optimize the performance of the electrodynamic head of an atomizer motorized knapsack sprayer, and study the effects of the angle of the target position, spraying distance, and wind speed on the performance of the electrodynamic sprayer.Materials and MethodsExperiments were performed in an agricultural machinery workshop at The Department of Biosystems Engineering, the University of Kurdistan, Iran, with an atomizer motorized knapsack sprayer equipped with an electrodynamic head. The effect of some factors including wind speed, spraying angle, and spraying distance on deposition, coverage percentage, and uniformity of spraying were investigated. These effects were investigated to determine the uniformity coefficient of total spraying. Design Expert 8.0.6 Trial software was used to design the experiments based on central composite design and to analyze the data. The investigated factors and levels were: the distance of nozzles from the target (at three levels of 2, 4, and 6 m), the angle of the target position (at three levels of 0, 45, and 90 degrees), and wind speed (at three levels of 2.5, 3, and 3.5 m s-1). Water-sensitive paper cards were used to evaluate the quality of the spraying. The cards were scanned and magnified with an Olympus SZX12 Stereo Microscope equipped with an objective lens of X1 and a total magnification of 7X. The characteristics of droplet size were determined using Mountains Map Trial and Deposit Scan software.Results and DiscussionThe maximum value of the total spraying uniformity coefficient was equal to 1.95 for the spraying angle of 0 degrees, the distance of 6 meters, and the speed of 3.5 meters per second. Meanwhile, the lowest value of the spray uniformity coefficient of 1.18 was obtained for the test conditions of 90 degrees, distance of 2 m, and speed of 2.5 m s-1, respectively. Based on analysis of variance for the two-factor interactions model (P-value less than 0.0001, explanation coefficient 0.9383, absolute explanation coefficient 0.910, standard deviation 0.0590, and coefficient of variation 3.790%). It can be stated that this model is highly accurate in predicting the uniformity of the total spraying, and the linear components of spraying angle and spraying distance, as well as the interaction of spraying angle × spraying distance and spraying distance × wind speed, significantly affect the uniformity of the total spraying (p<0.05). Nevertheless, the linear component of wind speed and the interaction between wind speed and spraying angle had no significant effect on the changes in the uniformity coefficient of the total spray. According to the variance analysis table (F-values), spraying distance has a far greater effect on the spraying uniformity coefficient than the spraying angle.It has been observed that the spraying uniformity coefficient will increase by increasing the spraying distance and decreasing the spraying angle. It can also be stated that the linear components of spraying angle and spraying distance, the interaction component of spraying angle × spraying distance, and the square power of the components of spraying distance and wind speed have a significant effect on surface coverage. The values of R2, Adj-R2, CV, and PRESS for the model adapted to the test data of leaf surface coverage percentage were obtained as 0.9929, 0.9865, 4.87%, and 188.61, respectively.Among the three input variables, the spraying distance has the greatest effect on the coverage of water-sensitive papers. At larger spraying angles, especially 90 degrees, the coverage decreased with the increasing distance. At spray angle of 90 degrees, by increasing the distance from 2 to 4 m, the spray uniformity coefficient increased from 1.18 at a wind speed of 2.5 m s-1 to 1.84 at a wind speed of 3.5 m s-1. However, at smaller spraying angles (for example zero-degree angle), at first, the spraying coverage increases with the increase of the spraying distance from 2 to 3 m and then sharply decreases afterward. According to the contours of spray coverage, in the spray distance range of 4 to 6 m and regardless of wind speed, the spray coverage does not vary with the increase of the spraying angle (p< 0.05). Meanwhile, in the spray distance range of 2 to 4 m, with the increase of the spraying angle, the spraying coverage increases significantly (p<0.05). Overall, increasing the distance between the sprayer and the target decreased the surface coverage on the target, and in electrodynamic spraying, the uniformity of particle deposition on the underside of the target was relatively the same as on the upper side.ConclusionTo improve the performance of the atomizer motorized knapsack sprayer, an electrodynamic spraying head was designed and built, and its performance was optimized using the response surface method (RSM) with a central composite design. During the research process, the influence of the independent parameters such as the distance between the nozzle and the target, the angle of the target position, and the wind speed on the variables including spraying uniformity, the percentage of the spraying coverage, and the percentage of changes in the total spraying coefficient were discussed and investigated. The results of the research led to the determination of the 3.5 m s-1 wind speed, 2.5 m sprayer distance, and 90 degrees spraying angle with 0.792 desirability, which were considered as the optimal performance conditions of the electrodynamic spraying head. The results of laboratory validation for optimal conditions show that the uniformity of total spraying indicated by the total relative span factor (RSFT) and the percentage of spraying coverage (Cov) are equal to 1.65 and 28.27%, respectively.
A. Omidi; R. Alimardani; M. Khanali
Abstract
Introduction Geographical location and climatic conditions are the important factors affecting the wind energy potential of each region. Iran is a vast country with different climates and the exploitation of its wind energy needs to study and research on the meteorological data. In the study area during ...
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Introduction Geographical location and climatic conditions are the important factors affecting the wind energy potential of each region. Iran is a vast country with different climates and the exploitation of its wind energy needs to study and research on the meteorological data. In the study area during the warm season and the hottest hours of the day, coinciding with peak electricity consumption in the region and the country, wind blowing continuously carried out. The surpassed consumption over production of electricity in summer and vice versa in winter is considered as one of the country's problems. The aim of this study was to investigate the parameters of the wind energy and the feasibility of wind potential (in study area) in the warm season in particular and other seasons to supply the needed electrical power of area, avoid of unwanted blackouts, development of wind energy as an important renewable energy, attraction of investors, and policymakers to build wind farms in the study area. Materials and Methods This study was conducted in the Dehloran city, located in the southern part of Ilam province. The region has a temperate winter and very hot and dry summer. The important criteria for construction of wind power plants and using of its energy are wind power density and the annual wind speed average. For this reason and analysis, and statistical analyzes, wind data includes three-hour direction and speed were obtained from the meteorological organization and during 2004 to 2013. The average of annual, monthly and daily wind speed and their standard deviation were calculated. Based on the commercial turbines in the country, and the rotor blades are at altitudes up to about 80 meters, the wind speed at altitudes of 40, 60 and 80 meters was calculated. To evaluate the potential of wind speed the Rayleigh and Weibull distribution functions were used and their parameters were calculated. The wind energy potential using the available data and the Weibull and Rayleigh functions were calculated. Results and Discussion Based on the results of the ten-year data, average of wind speed had relatively slight variation, with the highest and the lowest value of 3.6 and 3.25 m s-1 in 2007 and 2010, respectively. The annual average was about 6 m s-1 in height of 50 meters that seems appropriate. The highest and the lowest monthly average values were 4.62 m s-1 and 2.24 m s-1 in June 2005 and November 2006, respectively. Generally, the warm months had significantly higher wind speed than that of cold months. The Weibull distribution function parameters, k and c were calculated. Minimum and maximum amount of k were 1 and 1.828, in December 2006 and May 2011, respectively. The minimum and maximum amount of c was 2.37 and 5.69 in November 2004 and June 2013, respectively. The highest value of wind power density was 312 w m-2 in June. The lowest power density was observed in November. Therefore, we can say that the wind energy potential of the region has coincident with peak electricity consumption in the warm months. The most frequent and the least frequent wind direction were the southeast and northeast, respectively. Conclusion Daily evaluation of wind speed during different months, seasons and years showed a significant change during the day that represented the high value of the wind speed in noon and afternoon. The highest value of monthly wind energy density was for the warm season. The lowest and highest power density was in November and June, respectively. Therefore, we can say that the peak of wind energy potential of the region has a coincident with the country's peak power consumption in warm months. With considering that the study area has a warm climate and high consumption of energy in the hot days of a year and the probability of unwanted blackout of electricity in warm months, and the long hours of the wind blowing in the mentioned times, construction of wind farm in these areas can be reasonable.
M. Jalalvand; H. Bakhoda; M. Almassi
Abstract
In order to restrain the potential of wind energy, the first step is to determine the wind energy potential. In this study the wind data was used from the three-hour frequency recording of 10-year period (2002-2011). To predict the occurrence probability of each wind speed, the two-parameter Weibull ...
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In order to restrain the potential of wind energy, the first step is to determine the wind energy potential. In this study the wind data was used from the three-hour frequency recording of 10-year period (2002-2011). To predict the occurrence probability of each wind speed, the two-parameter Weibull function was used. The goodness of fit test by Chi-Square test showed that the wind speed distribution is not represented by the typical two- parameter Weibull function for all the months. Weibull probability density function has a good fit for eleven months, but for the 9th month of the year (September), it is not fitted. Thus, four-parameter Weibull probability function has been developed to analyze the wind speed frequency distribution in that region for the mentioned months. The electrical energy consumption of agricultural water wells in the region was also calculated for the desired periods of the year. Energy demand and energy supply were matched. Data analysis was performed using SPSS 18.0.0, MATLAB 7.13.0.564 and WIDOGRAPHER 3.0.2. The results show that in Broujerd, to exploit the wind energy at all times of the year, it is necessary to have at least 39 turbines of 2300 kW with 99 meters tower. If the desired turbines are used, there will be extra energy and also, agriculture will be continued towards sustainable development.
