Physical properties and conveying characteristics of corn and barley seeds using a suction-type pneumatic conveying system (original) (raw)
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The paper presents theoretical studies and laboratory experiments regarding pneumatic equipment for sowing small seeds in cups, highlighting the advantages of this type of equipment with superior parameters obtained from the considered crops. Equipment can be used in narrower spaces, being easily to handle and use, of driving the vacuum generator can be done electrically or thermically. By using this equipment, the productivity is increased, the space of establishing the seedlings is reduced, and the seeds norm is diminished. The germinating, rising and development space of plants is assured, equipment can be automated and built by minimum costs. Studies and experimental tests relating to the production index, consumption standard, the emerging degree and the plants percentage obtained will be continued.
Applied Engineering in Agriculture, 2001
Experiments on horizontal pneumatic conveying of rough rice, milled rice, and soybean indicated that the total pressure drop gradient is a function of air velocity, solid-to-air ratio, and particle and pipe diameter. Total pressure drop gradients were analyzed by summing the contributions of individual components for pressure drop due to air and solids separately. Fanning's equation was used to estimate the pressure drop due to air in all experiments. An equation analogous to Fanning's equation involving a solid friction factor, dispersed solids density, and solid velocity was assumed to represent the pressure drop due to solids. A generalized equation comprising of selected dimensionless parameters-velocity ratio (V t /V s); particle to pipe diameter ratio (d p /D); Froud's number based on terminal velocity (V t 2 /gD) as well as air velocity (V a 2 /gD); solid-to-air ratio; and particle Reynold's number (r a V slip d p /m a)-was developed for estimating the solid friction factor. Applicability of the developed equation was verified for horizontal pneumatic conveying of corn and mungbean. Experimental and estimated values were found to be in good agreement showing the average absolute variation within 2 to 12% thus validating the developed correlations and the approach for estimating the pressure drop gradients for general use for particles ranging in size from approximately 2 to 7 mm.
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INMATEH-Agricultural Engineering, 2014
Taking into account the complexity of wide width air-seeders, they remain less studied. The chief point for air-seeder designers is conception of the pneumatic conveying system. It must be precise in terms of uniformity so that that the agro-technical goals should be achieved. It must also ensure high rates without causing damages to seeds. This paper provides a theoretical analysis of pneumatic conveying designing applied to air-seeders. It shows that the conveying of particles (seeds, fertilizers or their mixture) in a given pipe depends on two interconnected parameters: flow concentration and air velocity. The knowledge of these two parameters is a necessity for the design of conveying systems but they are not defined in the case of agricultural machinery. This paper proposes a method to measure the flow concentration and the air velocity values which must be used to optimize an existing seeder (relatively to machine's outflow) or to design a new pneumatic seeder. In this cas...
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A study was made of drag coefficients in vertical pneumatic conveying of agricultural grains. From experiments conducted on rough rice and milled rice, it was found that the values of drag coefficient computed using the basic relationship for slip velocity of a single particle in an air stream were closely related to the solid flow rate per unit cross-sectional area of the conveying pipe and solid-to-air ratio. Generalized equations were developed for estimation of drag coefficient in terms of particle equivalent diameter, solid flow rate per unit cross-sectional area of pipe, and solid-to-air ratio. The equations were also verified for another agricultural grain, namely corn. The closeness between experimental and predicted values validated the equations for general use for grain particles ranging in size approximately from 3-to 7-mm mean diameter.
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A pneumatic harvesting, separating, and cleaning machine was designed and constructed to collect Jojoba seeds from the soil surface using cyclonic separation process. Jojoba seeds do not mature at once, whenever part of seeds reach maturation they fall naturally to the ground. So, more than one harvesting in the season may be necessary, depending upon weather conditions and grower preferences. To design the machine successfully, some of the physical and aerodynamic characteristics of Jojoba seeds and other undesired materials mix with the seeds were measured. The pneumatic harvesting machine was constructed at the workshop of Agricultural and Biosystems Engineering Department, Alexandria University, Egypt. The performance of the harvesting machine was investigated under different operation conditions such as suction air velocity, machine forward speed, length of the suction hose, clearance of the suction hose inlet above the soil surface, and the different ratios of materials other than Jojoba seeds (MOS). It was found that the best-operating conditions are when the suction air velocity is 30 m. s À 1 , hose length is 2.5 m, suction hose clearance from the soil surface is 5 cm, machine forward speed is 1.2 km .h À 1 , and the ratio of seeds to material other than seeds is 0.1. The research is atrial to produce a harvesting machine and then evaluated its performance under simulated field conditions. Although the performance of the harvester was considered satisfactory, it requires additional modifications and parts to make it commercial applicable.
Analysis and Experimental of Seeding Process of Pneumatic Split Seeder for Cotton
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In order to study the working mechanism and sowing effect of seed delivery pipes and their associated cavity seeders, the factors affecting the sowing test were first derived through pressure loss theory and force analysis of cotton seed particles in the gas-solid coupling field. Secondly, Ansys fluent was used to simulate the flow field of seed delivery pipe joints to study the effect of seed delivery pipe joints on the overall pressure loss and uniformity of air pressure distribution and to determine the optimal structure of seed delivery pipe joints. Then, the EDEM was simulated for the overall seed delivery pipe and its associated cavity seeders in the absence of positive pressure to analyze the transport pattern of each cotton seed. Finally, CFD-DEM gas-solid coupling simulation experiments were conducted on the center of two rows of seed delivery pipes and their connected cavity seeders to analyze the trajectory of cotton seeds under different rotational speeds of cavity seede...
Solid Velocity Estimation in Vertical Pneumatic Conveying of Agricultural Grains
Applied Engineering in Agriculture, 2001
An indirect method has been developed to estimate solid velocity in the vertical pneumatic conveying of agricultural grains. Experiments on vertical pneumatic conveying of rough rice, milled rice, and soybean indicated that solid velocity is a function of air velocity, solid flow rate, solid-to-air ratio, and grain equivalent diameter. An empirical equation has been developed to predict dispersed solids density, i.e. concentration of solids in pneumatic conveying. Knowing the solid flow rate and dispersed solids density, solid velocity was calculated. The method used for determining the solid velocity was validated based on the hypothesis that the average solid velocity is equal to zero when the limiting value of the air velocity is equal to the terminal velocity of the grains. The applicability of the developed relationships for estimating the solid velocity was verified for other agricultural grains like corn and mungbean.