H. Rahmanian- Koushkaki; S. H. Karparvarfard
Abstract
Introduction Pneumatic conveying is a continuous and flexible material handling method which uses positive or negative air pressure to convey materials in pipe. This conveying system is generally divided into two groups of dilute and dense phase. The purpose of this research was to create spiral grooves ...
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Introduction Pneumatic conveying is a continuous and flexible material handling method which uses positive or negative air pressure to convey materials in pipe. This conveying system is generally divided into two groups of dilute and dense phase. The purpose of this research was to create spiral grooves inside horizontal pipes which transfer granular materials under dense phase. Also, the performance of these pipes was compared with control pipes. Finally, friction factors obtained in this research were compared to the previous study. Materials and Methods To create spiral grooves inside the pipes, a broaching machine was designed and developed. Then, by connecting the broached pipes to a pneumatic conveying test- rig of granular materials, the performance of these pipes was compared with control pipes. The specifications of the broaching machine and test-rig were as follow. Broaching machine: The machine included chassis, an electromotor with one hp power, a reduction gearbox, a ball screw for converting rotational motion to linear motion, a spiral shaft, a guide with three bolls, broaches and inverter. Cutting operations and creating grooves inside the pipes were done using broaches. These broaches had two angles, attack angle of 15 degrees and a clearance angle of 10 degrees. The spiral angle of broaches was 30 degrees, the spiral pitch was 260 mm, the width of each groove was 1.5 mm, and a number of teeth were 20. Test- rig: The main components of the test- rig were the air compressor, blow tank, conveying pipes, solid discharge control valve (SDCV), receiving hopper, orifice plate flow meter, pressure transducers, and single point load cell. The compressor was a piston- type, the air flow rate was 405 L min-1 and maximum pressure was 12 bar. For a continuous flow of air and material mixture into conveying pipes, a blow tank was used. To transfer material from blow tank to pipes, a 90-degree bend with a radius of 250 mm and an inner diameter of 40 mm was used. The inner diameter of pips was 40 mm, the thickness was 5 mm and was selected from ABS. In order to measure static pressure of air along the pipes, 10 holes of one mm diameter were drilled on the surroundings of the pipes at intervals of one meter. Then, on each of these holes, a polyethylene bushing was placed. Pressure transducers were threaded on the top of these bushings. A solid discharge control valve was placed at the end of the flow line to control the flow of materials in a dense and continuous phase and to prevent material acceleration. The materials were introduced into the receiving hopper after leaving the valve. To measure the volume flow rate of air, an orifice plate with D and D/2 tapping was used. The pressure transducers were Hogller. For measuring the mass of the materials entering the receiving hopper, a single point load cell (Zemic L6G) was installed under the hopper. A data acquisition system based on ARM microcontroller was used to record output signals from transducers. The treatments were four levels of groove depth (0, 0.35, 0.55 and 0.9 mm), three levels of air pressure (1, 2 and 3 bar) and three levels of pipe length (3, 6 and 9 m). The transferred material was considered as mung bean. Results and Discussion The results of ANOVA showed that the main effects of groove depth, pipe length, and air pressure were significant on the mass flow rate of transmitted mung bean and solid friction factor at 1% probability level. The results indicated that the maximum mass flow rate and minimum friction factor were observed at a pipe length of 3 m, the groove depth of 0.90 mm and air pressure of 3 bar. Minimum mass flow rate and maximum friction factor were observed at pipe length of 9 m, the groove depth of 0 mm (smooth pipe) and air pressure of 1 bar. Conclusion The results showed that the existence of spiral grooves within horizontal conveying pipes would increase the mass flow rate of the mung bean and reduce the solid friction factor of the mung bean and inner wall of pipes.
R. Karmulla Chaab; S. H. Karparvarfard; M. Edalat; H. Rahmanian- Koushkaki
Abstract
Introduction One of the problems which considered in recent years for grain harvesting is loss of wheat during production until consumption and tenders the offers for prevention of its especially in harvesting times by combine harvesting machine. Grain harvesting combines are good examples of an operation ...
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Introduction One of the problems which considered in recent years for grain harvesting is loss of wheat during production until consumption and tenders the offers for prevention of its especially in harvesting times by combine harvesting machine. Grain harvesting combines are good examples of an operation where a compromise must be made. One would expect increased costs because of natural loss before harvesting, because of cutter bar loss, because of threshing loss, because of greater losses over the sieve and because of the reduced forward speed necessary to permit the through put material to feed passed the cylinder. The ability to recognize and evaluate compromise solutions and be able to predict the loosed grain is a valuable trait of the harvesting machine manager. By understanding the detailed operation of machines, be able to check their performance, and then arrive at adjustments or operating producers which produce the greatest economic return. Voicu et al. (2007) predicted the grain loss in cleaning part of the combine harvester by using the laboratory simulator based on dimensional analysis method. The obtained model was capable to predict the grain loss perfectly. Soleimani and Kasraei (2012) designed and developed a header simulator to optimize the combine header in rapeseed harvesting. Parameters of interest were: forward speed, cutter bar speed and reel index. The results showed that all the factors were significant in 5% probability. Also in the case of forward speed was 2 km h-1, cutter bar speed was 1400 rpm and reel index was 1.5, the grain loss had minimum quantity. The main purpose of this research was to develop an equation for predicting grain loss in combine header simulator. Modeling of the header grain loss was conducted using dimensional analysis approach. Effective factors on grain loss in combine header unit were: forward speed, reel speed and cutter bar height. Materials and Methods For studying the effective parameters on head loss in grain combine harvester, a header simulator with the following components was built in Biosystems Engineering Department of Shiraz University. Reel unit The reel size was 120 cm length and 100 cm diameter. This reel was removed from an old combine header and installed on a fixed bed. For changing the rotational speed of the reel, an electrical inverter (N50-007SF, Korea) was used. Cutter bar unit The cutter bar length was 120 cm. Knifes were installed on this section. Reciprocating motion was transmitted to the cutter bar through a slider crank attached to a variable speed electric motor (1.5kw, 1400 rpm, Poland). The motor was fixed on the bed. Feeder unit This section was consisted of a rail and a virtual ground. This ground was a tray that the wheat stems were staying on it manually. The rail was the path of virtual ground. Treatments consisted of three levels of rotational speed of reel (21, 25 and 30 rpm), three levels of forward speed of virtual ground (2, 3 and 4 km h-1), three levels of cutter bar height (15, 25 and 35 cm) and three replications. In other words, 81 tests were done. The basis of choosing levels of treatments was combine harvester manuals and driver’s experiences. The dependent variable (H.L) was calculated as below: (1) Where L.G is the mass of loss grains and H.G is the mass of harvested grains. Results and Discussion Generally results of ANOVA test showed that the cutter bar height, rotational speed of reel and forward speed had significant effect on head loss. Also interaction of rotational speed and forward speed, cutter bar height and forward speed had significant effect on head loss. These findings were based on Soleimani and Kasraei (2012) research. Therefore, the cutter bar height, rotational speed of reel and forward speed were three independent parameters on head loss as a dependent parameter. By results of laboratory data, the equation for predicting grain loss by header simulator was obtained. Conclusion The statistical results of F- test in 5% probability showed that there were no significant difference between measured and predicted amounts for laboratory data.
Design and Construction
S. Dehghani; S. H. Karparvarfard; H. Rahmanian- Koushkaki
Abstract
Introduction: Automatic guidance of tractors in the mechanized farming practice has taken the attention of agricultural engineers in the last two decades. For this to be truly practical on the farm, it should be economical, simple to operate and entirely contained on the vehicle. Different types of steering ...
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Introduction: Automatic guidance of tractors in the mechanized farming practice has taken the attention of agricultural engineers in the last two decades. For this to be truly practical on the farm, it should be economical, simple to operate and entirely contained on the vehicle. Different types of steering systems such as leader- cable, laser- controlled, radio- operated and contactor- type have been developed for automatic guidance. The automatic leveling system is used on hillside machines to keep the separator level when operating on hillsides. This system has three parts: fluid level system, electrical system and hydraulic system. The fluid level system consists of fluid reservoir and a leveling control switch box. The fluid level system actuates the electrical system of the leveling unit. The electrical system which actuated by the fluid system consist of four micro switches in the leveling control switch box, two micro switches in the limit control box, a solenoid in the hydraulic control level, manual leveling control switch, and a leveling limit warning light. The hydraulic system maintains the level of the separator when the machine is operating on a hillside. The present study was aimed to develop a reliable, versatile and easy to maintain system to fit our economy and low technology level of farmers for hillside- range development or fallow farming. The automatic guidance system has been implemented successfully on agricultural vehicles on the basis of three components, i.e. sensors, processors and actuator elements. The study site (N, latitude; E, longitude; and 1810 m above sea level) was located at the Agricultural Research Center, Shiraz University, 15 km northwest of Shiraz, Fars Province, Iran. MF-399 agricultural tractor manufactured by ITMCO, Tabriz, Iran was used for doing the experiments.Materials and Methods:The Level Sensing System: The biaxial tilt industrial sensor (ZCT245AL- China) with digital output can be connected to the computer and received angular position in x and y coordinates. An assumed degree could be considered as basis degree and the measured frequency was adjustable. The tilt sensor located along the axial length of tractor and leads the angles which are created by longitudinal axle transverse axle of the tractor in related to horizontal level. It was used for contour lines detecting. The potentiometer located on the steering wheel of the tractor and pressure sensor which used with goniometer sensor used keeping uniformly of leveling points in tractor motion. The pressure sensor (SN-SCP1000- South Korea) which is used in leveling system can detect the elevation changes. In this way, by defining a limitation of altitude for system, it would be able to stop steering turning motor which was coupled to tractor steering rod automatically. By resetting, the tractor could be able to live in a new level position. To avoid excessive left and right steering wheels deviation and interfering with other lines of travel, potentiometer was used. The deviation degree for steering rod from center to left or right was selected 120 degrees. Accordingly, the wheels would not be able to move more than 10 degrees to each direction. The Processing System: The electrical circuit graphically designed and simulated by software (Altium Designer, 2009) and installed on the tractor. The components of this circuit are as follows: Electrical board, two relays which control the electrical pathway in both directions, a battery with 12 volts of electric potential as electrical power supply, ATmeGA32 microcontroller which was made by Atmel company as main core for information processing, RS232 protocol was used for making correlation between serial port (COM) and the microcontroller and two capacitors for reducing noises. The Actuator System: The output signals from the a processing system, were lead in the actuator system would order and indicative of left- turn or right- turn command, were introduced to actuator- units include an electric- gearbox motor that stimulate the steering wheel shaft of the tractor by chain and sprocket and conduct the tractor in leveling traces at the desired speed. Before hitching any implements such as row planter behind the tractor, the system was successfully tested on average slopes of 14.5% using a tracing powder. Results and Discussion: A plot of the average elevation of each 12 lines traced for a length of about 50 meters, H0, versus the actual elevation of 12 to 16 equally spaced points of each trace, H, produced the following relationship: H0= 0.142+ 0.990 H Indicating a reasonably acceptable performance with standard error and R2 0.048 and 99.3% respectively. Conclusions:The row planting in various slopes coincided with the contour lines of ground (Duncan’s Multiple Range Test p ≤ 0.05). Also, no significant difference was observed among the slopes and index of length and dry weight of root and shoot. The percentage of the emergence index in the high slopes (18-21%) showed significant differences. Hence by increasing slopes, the percentage of seed emergence was decreased.
