Design and Evaluation of Agricultural Machines
mehdi kakaei; Hossein Haji Agha Alizadeh
Abstract
Introduction: In developing countries, since most farmers have small plots of land, they are unable to afford expensive machinery for cultivating vegetables, so they use the manual method. In this method, on average, each worker works for about 8 to 9 hours a day. This activity causes physical fatigue, ...
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Introduction: In developing countries, since most farmers have small plots of land, they are unable to afford expensive machinery for cultivating vegetables, so they use the manual method. In this method, on average, each worker works for about 8 to 9 hours a day. This activity causes physical fatigue, reduces work accuracy, and uneven distribution of seedlings across the field. On the other hand, during peak work, due to the high demand for human resources, there is usually a shortage of human resources. This shortage of manpower during the planting season affects the right time and the final yield of the cropTransplanting machine is used to increase productivity, uniform distribution, precision in planting, save time, and timely planting. A review of the resources of the last few years in the special planting of seedlings has given automatic feeding with determinate pot seedlings, reducing manpower, increasing the final yield and increasing the carrying capacity at the same time, and as a result, it also helps to improve the performance of semi-auto games better and also helps to improve the performance of semi-autos, reducing human intervention, and on the other hand, seedlings grown in paper pots, to mechanize the transplanting operation by improving the quality of the pot in the soil and helping to meet the conditions. Growth and organic matter in the soil are a better option. Therefore, this research aimed to develop, design and evaluate a smart seedling planting device in small farms to identify the speed of the advance operation using seedlings grown in paper pots.Materials and Methods: In this study, the physical and mechanical properties of two biodegradable pot models, an incomplete cone and a square pyramid, were evaluated for use in a transplanter in a pressure test device. According to the field data of tomato planting methods, a model with suitable dimensions for small farms was first designed using SolidWorks engineering software. Then, to build the transplanter, its frame was first built. Considering the dimensions of the device, a potting tractor model with a nominal power of 45 horsepower was used to provide driving forces due to its appropriate maneuverability in a small space and greenhouse. In this device, a furrow opener with adjustable height for working at different depths was installed at the beginning of the device. A finger covering system, soil leveler, and two-disc coverings were used to properly position the pot in the created furrow. To transfer the pots in this device to the drop tube, a turntable with a stepper motor was used to transport them at different rotational speeds, an electronic circuit to control its rotational speed, and two infrared sensors to detect and count the pots. Then, for its field evaluation, two factors, the advancing speed at three levels (0.7, 1.5, and 2.5) and the type of seedling at two levels (4 and 6 leaves) were studied in a completely randomized factorial design with three replications. The aim of designing this transplanting device is to use biodegradable pots to develop sustainable agriculture and reduce physical damage to roots during planting.Results and Discussion: The results of this study showed that the most suitable incomplete cone pot that withstands the highest force in the pressure test was used as the most suitable pot for use in the transplanter. Then, to eliminate lateral forces on the movement of the pot in the drop tube, a diagonal position in the opposite direction of movement was used. The results of the analysis of the measured data showed that the effect of the forward speed on the parameters of the percentage of uniformity of the distribution of seedlings, the percentage of changes in the planting depth, the percentage of plant deviation from the row and the percentage of physical damage was significant at the 1% level, and its effect on the parameters of the percentage of multiple planting and non-planting, acceptable and unacceptable planting was significant at the 5% level. Also, the effect of the seedling type factor on the parameters of the percentage of seedling mortality after planting and plant deviation from the row were significant at the 1% and 5% levels, respectively. The interaction effect of the factors was not significant on any of the measured parameters. Comparison of the average effects of the measured factors at the three levels of forward speed and two types of seedlings showed that all factors had equal effects at the two speed levels of 0.75 and 1.5 km/h, except for the factor of the percentage of uniformity of seedling distribution (with an average of 89.36%) at the speed of 1.5 km/h and the mortality of seedlings after planting at four leaves (with an average of 22.33%).Conclusion: Considering the physical characteristics of the biodegradable pot, the incomplete cone model was selected for use in the device. The best performance of the transplanter device at three levels of forward speed and two types of transplanting was achieved at a forward speed of 1.5 km/h and 6 leaves with the lowest percentage of plant deviation from the row, physical damage, multiple planting and non-planting, percentage of unacceptable planting, percentage of depth changes, and with the highest percentage of acceptable planting and uniform distribution.
Design and Evaluation of Agricultural Machines
sara saki; Mohamad Esmail Khorasani Ferdavani; Seied Mohamad safieddin Ardebili; Amir Soltani Mohammadi
Abstract
Introduction: Compressed air is a versatile energy source used in various applications. However, pumping water with compressed air requires specific designs. Various designs have been proposed for pumping water using compressed air. Some of these designs include Air jet pumps, air-lift pumps, diaphragm ...
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Introduction: Compressed air is a versatile energy source used in various applications. However, pumping water with compressed air requires specific designs. Various designs have been proposed for pumping water using compressed air. Some of these designs include Air jet pumps, air-lift pumps, diaphragm pumps, and hydro-pneumatic pumps (discrete flow). The hydro-pneumatic pump is composed of a chamber with two unidirectional valves for intake and discharge, separated by a well. Additionally, it includes an internal tube connected from the top to the outlet unidirectional valve. As compressed air enters the chamber, it applies pressure on the water surface within the chamber, resulting in the closure of the intake valve and the opening of the outlet valve, facilitating the upward pumping of water through the internal tube. Studies have been carried out in the field of jet pumps and air-lift pumps. However, the notion of enhancing flow rate and efficiency by integrating the pumping mechanisms of these pumps gave rise to the original idea of developing a hybrid water pump with a compressed air driver. The primary goal was to approach the efficiency of a hydro-pneumatic pump and simplify the design, allowing water pumping without the need for sensors or control systems. Materials and Methods: To assess the compressed air water pump and compare its performance with a hydro-pneumatic pump, a prototype with similar dimensions was constructed. By turning on or off and combining three compressed air nozzles within the pump structure, it was possible to operate the Combinatorial compressed air pump in four different modes. During field experiments, the performance, which included measuring input air pressure, flow rate, and water pumping height, was measured. Additionally, the efficiency of the Combinatorial compressed air pump was calculated under experimental conditions. Field experiments was conducted using a factorial design in randomized blocks. Treated variables included immersion depth (4 levels), inlet air pressure (6 levels), pump types and their working modes (5 levels). Discharge flow rates and water pumping height were measured across four replicates. at post processing, pumping efficiency calculated. Analysis of variance and post-hoc tests were conducted to analyze the significant effects of treatment variables and their interactions. to identify the best level for each treatment across different levels of other treatments, interaction slicing was employed. result was presented in charts and tables.Results and Discussion: The variance analysis revealed a significant difference at the 1% confidence level among pump types, Immersion depth, input air pressure, and their interactions on water pump flow rate. Increasing submergence depth led to higher flow rates in the hydro-pneumatic pump, Combinatorial pneumatic pump, Bubble pump, Bubble & Airlift combined pump, and air-lift pump. Additionally, raising input air flow resulted in increased water pumping rates for all types of pumps.The hydro-pneumatic pump exhibited higher flow rates compared to other pumps, attributed to its positive displacement structure. The flow rate in all pumps increased with higher input air pressure due to the increase in air flow.The variance analysis on pump efficiency showed significant differences at the 1% confidence level in input air pressure levels, Immersion depth, pump type, and their interactions. With increased Immersion depth, pump efficiency rose in the following order: Combinatorial pneumatic pump, hydro-pneumatic pump, Bubble pump, Bubble & Airlift combined pump and air-lift pump, and air-lift pump. The Combinatorial pneumatic pump showed the most positive impact of Immersion depth on efficiency.Immersion depth, inlet air pressure, and pump type significantly impacted discharge rate and pump efficiency. With increased immersion depth and air pressure, discharge and efficiency rose for all pump models and operating modes. The hydro-Pneumatic pump achieved higher efficiency and discharge due to its different structure. At 2m immersion depth, the best performance among all pump models and modes was observed: Airlift pump (10.3% efficiency), Bubble pump (20.8%), Bubble & Airlift Combined pump (19.3%), Pneumatic Combined Pump (27.1%), and Hydro-Pneumatic pump (25.2%). Discussion: While the hydro-Pneumatic pump offered superior performance, the compressed air pump's simpler structure and lack of electronic control circuitry present advantages. Future research could explore optimizing the compressed air pump design for improved efficiency while maintaining its structural simplicity. Due to structural differences, the hydro-pneumatic pump exhibits significantly higher efficiency (approximately 54%). It was expected that this efficiency would be maintained with increasing pressure, but due to the limited immersion depth in the experiments and dimensional mismatch of the pump with high input air pressure, we observed a decrease in efficiency at higher pressures. This indicates that for each submergence depth and pump head, there is an optimal pressure that the pump dimensions should be designed to suit.
Design and Evaluation of Agricultural Machines
Davood Kalantari
Abstract
Introduction Tillage is a main operation for seedbed preparation and is one of the major items of energy and cost expenditure in crop production. In the conventional rotary tillers, using the L-shape blades has numerous problems such as severe vibrational problems, weeds wrapping around the blades, ...
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Introduction Tillage is a main operation for seedbed preparation and is one of the major items of energy and cost expenditure in crop production. In the conventional rotary tillers, using the L-shape blades has numerous problems such as severe vibrational problems, weeds wrapping around the blades, and lower performance due to the limited power of such small tillers. Therefore in order to overcome the addressed problems, design, fabrication and evaluation of a new rototiller adapted for small farms and gardens were considered in this research. Materials and Methods To start the design, the power requirement was estimated using a semi-theoretical model for the given working depth, working width, forward and rotational speed of the machine. Then a suitable engine was chosen based on the estimated power. The estimated power was 3.4 kW (4.5 hp); therefore, according to the available engines in the market for single cylinder gasoline engines, a Kato engine with 5.5 hp power and maximum speed of 3600 rpm was chosen. By reducing the rotational speed of the engine in three stages, rotational speed of the rotor was obtained in the range of 140-260 rpm. To transmit the power from the engine to the rotary axis, first, a pulley and belt mechanism (two V-shaped belt, type B) and then two chain mechanisms (roller chains 40 and 60) were used. Rotary axis with the diameter of 2.5 cm was made from steel E295. The fabricated rototiller has a working width of 60 cm, working depth of 7 cm, rotational speed between 140-260 rpm, forward speed equal to the operator’s translational speed, and maximum power equal to 5.5 hp. The maximum force exerted on each of the blades was calculated equal to 84.10 kgf (824.73 N) using the theoretical approach proposed by Bernacki (1972). In the next step, numerical simulation of blades, flanges and rotating shaft for stress and strain analysis was performed using the Ansys software. Farm experiments were carried out as split plots in citrus gardens based on randomized complete block design with three replications. The soil moisture content as the main plot varied in two levels (13.5-21.9 and 21.9-30.3 percent based on dry weight) and the rotational speed of blades as subplots varied in three levels (140-170, 170-200 and 200-230 rpm). The measured parameters consisted of clod mean weight diameter, soil relent percentage, soil bulk density and specific fuel consumption. To determine the diameter of aggregates, a set of standard sieves with the diameter ranging from 0.5 to 8 mm were used. Then a laboratory shaker was used to sift the samples. Each sample was shaken for 30 sec. To determine the fuel consumption during the experiments, the filled fuel tank method was used. Data analyses including analysis of variance (Anova), mean comparisons and interaction between the parameters were performed using the SPSS 16 software. Results and Discussion The numerical stress analysis of the flange showed that the maximum van - Mises stress occurred in the position of the blade-flange connections, with a magnitude of 52.98 MPa for the given working conditions, including soil engineering properties, working depth and other important parameters. The experimental results obtained in this study indicated that influence of soil moisture and rotational speed of blades on the clod mean weight diameter, soil relent percentage and specific fuel consumption were significant (p < 0.01). The clod mean weight diameter was measured equal to 8 mm at high rotational speed (200-230 rpm) and high soil moisture content (21.9%-30.3%) and equal to 15 mm at low rotational speed (140-170 rpm) and low soil moisture content (13.5%- 21.9%). The maximum soil relent percentage was obtained equal to 97% at high rotational speed (200-230 rpm) and high soil moisture content (21.9%-30.3%). Regarding the results obtained in this study, the specific fuel consumption increased first in a light slop, then in a steep rise with increasing the blades rotational speed. The reason can be the higher relent percent of the soil at higher rotational speeds and higher moisture contents, albeit at the examined range of 21.9-30.3. The specific fuel consumption was maximum at higher soil moisture content, i.e., 30 %. The results indicated that the blades rotational speed and soil moisture content had no significant effect on the field efficiency of the examined rototiller. Reduction of the rotational speed of the rototiller from high-to-moderate speeds yields decreasing the fuel consumption of 17 liter/ha, which could be significant in a wide scale soil tillage operations. As a general result, reduction of the rotational speed has some considerable advantages such as reducing the power requirements, reducing the blade wearing and maintaining the soil structure. Conclusion The stress analysis of the fabricated machine together with the experimental and field measurements indicated that the new proposed and fabricated blades were a suitable choice for construction of small rototillers. The fabricated machine with the new blades showed some additional advantages including less specific energy consumption, less weeds wrapping around the blades, and less vibrational problems.
