The relationship between machine and soil
M. Naderi-Boldaji; H. Azimi-Nejadian; M. Bahrami
Abstract
Machinery traffic is associated with the application of stress onto the soil surface and is the main reason for agricultural soil compaction. Currently, probes are used for studying the stress propagation in soil and measuring soil stress. However, because of the physical presence of a probe, the measured ...
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Machinery traffic is associated with the application of stress onto the soil surface and is the main reason for agricultural soil compaction. Currently, probes are used for studying the stress propagation in soil and measuring soil stress. However, because of the physical presence of a probe, the measured stress may differ from the actual stress, i.e. the stress induced in the soil under machinery traffic in the absence of a probe. Hence, we need to model the soil-stress probe interaction to study the difference in stress caused by the probe under varying loading geometries, loading time, depth, and soil properties to find correction factors for probe-measured stress. This study aims to simulate the soil-stress probe interaction under a moving rigid wheel using finite element method (FEM) to investigate the agreement between the simulated with-probe stress and the experimental measurements and to compare the resulting ratio of with/without probe stress with previous studies. The soil was modeled as an elastic-perfectly plastic material whose properties were calibrated with the simulation of cone penetration and wheel sinkage into the soil. The results showed an average 28% overestimation of FEM-simulated probe stress as compared to the experimental stress measured under the wheel loadings of 600 and 1,200 N. The average simulated ratio of with/without probe stress was found to be 1.22 for the two tests which is significantly smaller than that of plate sinkage loading (1.9). The simulation of wheel speed on soil stress showed a minor increase in stress. The stress over-estimation ratio (i.e. the ratio of with/without probe stress) noticeably increased with depth but increased slightly with speed for depths below 0.2 m.
B. Souri Damirchi Sofla; S. H. Karparvarfard; A. Ranjbar Karim Abadi; H. Azimi-Nejadian; A. Moazni Kalat
Abstract
IntroductionTillage is one of the most important field operations to improve soil structure and physical conditions and provide the proper plant site. Conservation tillage is one of the methods of tillage that reduces tillage costs. The blade is one of the most important consumed components of tillage ...
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IntroductionTillage is one of the most important field operations to improve soil structure and physical conditions and provide the proper plant site. Conservation tillage is one of the methods of tillage that reduces tillage costs. The blade is one of the most important consumed components of tillage tools in the conservation tillage, which is very important for how it is adjusted and its effect on the quality of tillage and energy required of tillage tools. According to the research conducted on the importance of optimizing tillage implements, the aim of this study was oriented to determine the optimum rake angle of a narrow-modified winged and non-winged blade in the field soil.Materials and MethodsThe tests were conducted in the 22nd part of farms in Agriculture School (Bajgah zone) of Shiraz University. Three levels of blade rake angles (20, 25, and 30 degrees), two levels of tillage depth (15 and 20 cm), and two levels of forward speed (2 and 3 km h-1) were the treatments of this study. Draft, fuel consumption, slippage, soil disturbance area, soil upheaving area, and specific draft were the measured parameters and they were measured for each combination of the treatments. The RNAM test code was then used to measure the draft force. In order to measure fuel consumption, two flow meters were used in the round way as a closed-loop. The encoder and the fifth wheel were also employed to measure the slippage. The profilometer and laser meter were applied to measure the soil upheaving and disturbance areas. The split-split plot on randomized complete block design was used to do the field experiments in three replication and the data analysis was performed by SAS software (9.4 edition). Multivariate linear regression was used to determine the optimum values of the mentioned parameters. For this purpose, the lowest value of draft, fuel consumption, specific draft, tractor driver wheel slip, and the highest soil disturbance and upheaving areas was considered.Results and DiscusionThe results showed that the magnitude of draft increased with rake angle, therefore, the minimum draft was obtained in the rake angle of 20°. As the blade rake angle increased, the amount of soil disturbance area was increased and the maximum soil disturbance was obtained in the rake angle of 30°. The mean slip values of the tractor driver wheels when using non-winged blade were not significant for three levels of blade rake angles and it was significant for two velocity levels. With increasing in rake angle from 20 to 25°, the mean values of specific draft were increased, but with changeing the rake angle from 25 to 30°, there was not significant difference between specific draft values. The difference between the magnitude of tractor driver wheels slip for three levels of rake angle was not significant. Increasing the rake angle had a significant effect on tractor fuel consomption, such that it increased by increasing the rake angle values.ConclusionThe optimum rake angle for the non-winged blade mode was 20° with R2 of 0.73 and for the winged blade mode was 30° with R2 of 0.90. The optimum depth for the non-winged blade was 19.98 cm with R2 of 0.99 and for the winged blade was 20 cm with R2 of 0.97. Also, the optimum forward speed values for the non-winged blade was 2.21 km h-1 with R2 of 0.43 and for the winged blade was 2.03 km h-1 with R2 of 0.84.
M. Moradi; J. Ghasemi; H. Azimi-Nejadian
Abstract
IntroductionSome unit operations of food process engineering such as drying consumes a high amount of energy. Therefore, analysis of energy and exergy can be a suitable method to manage the energy consumption of the drying. Hence, in the present research, analysis of energy and exergy for the drying ...
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IntroductionSome unit operations of food process engineering such as drying consumes a high amount of energy. Therefore, analysis of energy and exergy can be a suitable method to manage the energy consumption of the drying. Hence, in the present research, analysis of energy and exergy for the drying process of lemon verbena leaves was performed.Materials and MethodsA cabinet solar dryer was employed to investigate the energy consumption of thin layer drying of lemon verbena leaves. The dryer had a galvanized solar plate collector which had a surface area of 0.75 m2 and to absorb the maximum solar energy, the collector painted with the black color. The collector was set at an angle of 45 degrees relative to the horizon and an electric blower was installed in the bottom of the collector to blow the ambient air through the solar collector and hence, hot air entered the drying chamber to dry the lemon verbena leaves. In order to record the air temperature and humidity in different locations of the dryer, an Arduino board with 8 smart sensors (AM2301, with temperature accuracy of 0.5°C and humidity accuracy of 3%) were used. To obtain the initial moisture content of the leaves, they inserted in an electrical oven for 16 hours at a temperature of 70°C. In order to measure the moisture content of the leaves during drying, they weighted at different times using a digital balance (A & D, Japan with accuracy of 0.001 g).Energy consumption rate of the drying was calculated by Equation (1):Where, Ein: energy consumption rate (kW), : mass flow rate of drying air (kg s-1), cp: specific heat of drying air (kJ kg-1 °C-1), Δt: temperature difference between the ambient air and drying air (°C).Also, the specific energy consumption of drying (SEC) was calculated by Equation (2):Where; SEC: Specific energy consumption (MJ kg-1 of removed water) t: drying time (s), and M: mass of removed water from the drying material (kg).Also, useful power can be calculated from Equation (3):Where; Eout: useful power (kW), ms: Evaporation rate (kg s-1), lg: latent heat of vaporization (kJ kg-1 of water)In order to calculate energy efficiency, Equation (4) was used: Also inlet and outlet exergy were calculated by equations (5) and (6), respectively: Where; T1: Inlet air temperature into the drying chamber (°C), T2: Outlet air temperature from the drying chamber (°C), T0: Ambient air temperature (°C).Also, Equations (7) and (8) were used to calculate exergy efficiency and loss, respectively:Results and DiscussionThe results of energy analysis showed specific energy consumption (SEC) increased with increasing of drying temperature and decreasing of air velocity. Accordingly, in the air velocity of 2 m s-1 and the temperatures of 30, 40, and 50 ˚C, SEC were 276.3, 694.7, and 708.0 MJ kg-1 of removed water, respectively. While SEC for an air velocity of 2.5 m s-1 and air temperatures of 30, 40, and 50 ˚C were 266.9, 469.8, and 638.0 MJ kg-1 of removed water, respectively, the corresponded values for air velocity of 3 m s-1 were as 217.0, 391.3, and 501.8 MJ kg-1 of removed water, respectively. Also, the results revealed that with an increase of temperature and a reduction of velocity, energy efficiency reduced, so that the maximum value of energy efficiency observed in an experiment with temperature of 30˚C and velocity of 3 m s-1. Also, the highest value of exergy efficiency obtained in temperature of 50˚C and velocity of 3 m s-1.ConclusionA hot air solar dryer was used for drying lemon verbena leaves. Results of specific energy consumption of drying showed a high amount of fossil fuels can be saved by using this dryer. Also, from the aspect of energy and exergy efficiency, using of the dryer in the lower temperature and higher air velocity is recommended.
H. Balanian; S. H. Karparvarfard; A. Mousavi Khanghah; M. H. Raoufat; H. Azimi-Nejadian
Abstract
In this study, a model was developed for predicting the seeding rate of corn seeds of a typical row-crop planter equipped with a multi-slot feeding device. To this, nine multi-slot rotors (with 4, 5 and 6 slots in three angles of mouth including 23°, 25° and 27°) were designed and manufactured. ...
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In this study, a model was developed for predicting the seeding rate of corn seeds of a typical row-crop planter equipped with a multi-slot feeding device. To this, nine multi-slot rotors (with 4, 5 and 6 slots in three angles of mouth including 23°, 25° and 27°) were designed and manufactured. Tests were carried out at four levels of angular velocity of 40, 52, 62 and 78 rpm on grease belt moving at constant speed of 3.5 km h-1. Tests were completed in three replications. Discharge flow rate was measured and recorded for each treatment. The data were used to develop a model which can be used for predicting the seeding rate under various numbers of slot, mouth angle and rotor angular velocity. According to the results, angle mouth of slots, number of slots, angular velocity and the dual interaction between them showed increasing effects on weight flow rate of seeds (P-value<0.01). In the next step, raw data were used to develop the two desired models: based on the dimensional analysis technique and response surface methodology (RSM). The models outputs were compared to experimental data. The standard error of estimate for flow rate for dimensional analysis and response surface methodology (RSM) were 68.13 mm3 s-1 and 475.59 mm3 s-1, respectively. The dimensional analysis model was closer to experimental data rather than the RSM method. Thus, to predict the volume flow rate of seed, the dimensional analysis model is recommended.
