Measuring Picking Force of Sunflower Seeds and Prediction of Reasonable Range of Air-Jet Parameters to Remove Sunflower Seeds from the Head

To design a new machine which removes the seeds of sunflowers based on air-jet impingement, picking force of five varieties of sunflower seeds was measured. Effects of the loading rate, sunflower head’s diameter, the location of the seeds on the head and the number of the days after harvesting on picking force of seeds were studied. The tests were conducted 1, 2, 3 and 4 days after harvesting. Also theoretical air-jet impingement forces for four levels of nozzle diameter, four levels of jet temperature and eight levels of pressure of reservoir to which the jet were calculated. With the increase of the sunflower heads’ diameter and the loading rate from 50 to 150 g min-1, the values of the picking force increased. With the increase of the distance between the location of the seeds and the center of the head, the values of the picking force decreased. Comparison between the experimental results and the theoretical calculations indicated that removing the sunflower seeds using nozzles with 2 mm is not possible. Also when the supply pressure is less than 5 bar, nozzles with a 4 mm diameter cannot be used to remove the sunflower seeds from the heads. The results indicate that using a nozzle with a diameter of 6 to 8 mm and pressure of 6 to 8 bar seems to be suitable for separating the seeds from SH, though more studies are required

Effect of air-jet impingement parameters on the removing of sunflower seeds from the heads in static conditions

Due to the success of air-jet in food and agricultural sciences, in order to eliminate a number of problems in mechanical methods of removing sunflower seeds from the head, a new method was invented based on impingement jets.  In fact, the aim of presenting the air-jet impingement method was not to design this simple machine.  But when we started designing the final machine, we realized that we need to take a step back and study the jet parameters in simple and static state.  The effect of the seeds’ location on sunflower head, reservoir pressure, the angle of impingement, nozzle diameter and the distance between the nozzle outlet and the surface of the sunflower head on the removed area of sunflower head in static conditions were examined.  The regions removed by the impingement of the air-jet were photographed and the area of the removed regions was calculated. Response surface methodology was used for designing experiments for all three regions of sunflower head of “Dorsefid” variety.  Based on the obtained results of two varieties, on side, middle and central regions, removing seeds using 30°, 60° and 90° angle of impingement is advised respectively.  The results indicated that the area of the removed regions was increased with the increase of the nozzle diameter and reservoir pressure. Also the removed area increased with the increase of the distance between the nozzle outlet and the surface of the SH at first, but then decreased. The optimal distance between the nozzle outlet and the surface of the SH ranges between 24 to 28 mm

Measuring some physical properties of sunflower (helianthus annus l.) head and modeling dimensions

For 100 sunflower head, maximum and minimum diameters, thickness, height of the ground, and mass of all seeds on sunflower head (SH) for five conventional varieties were measured.  To examine the correlation between maximum SH diameter and minimum SH diameter, SH thickness, SH height from the ground and SH seeds mass, linear regression method was used.  Also SH diameter and SH thickness of four sunflower hybrids varieties were measured.  Log-normal, Weibull and Generalized extreme value (G.E.V) distribution were used in order to model SH diameter and SH thickness distributions of all varieties and hybrids; also, Kolmogorov-Smirnov methods were used for comparison of all probability density.  Results indicated that value of average of dimensions, geometric and arithmetic mean diameter, head height from the ground, and mass of the seeds on each head of Dorsefid and Sirena varieties were more and less than the other varieties, respectively.  For all varieties, there was linear correlation between maximum SH diameter and minimum SH diameters, SH thickness and mass of seeds; while there wasn’t any correlation between SH height and maximum SH diameter.  Results showed that whenever skewness and kurtosis had positive values, Log-normal and G.E.V distribution had good performance and whenever skewness and kurtosis had negative values, Weibull and G.E.V distribution had good performance based on Kolomogrov-Smirnov methods

Physical properties and modeling for sunflower seeds

For designing the dehulling, separating, threshing, sizing and planting machines for sunflower, physical and mechanical properties of sunflower seeds should be known.  In this work some physical properties of three varieties of sunflower seeds, distance between the adjacent seeds on the sunflower head (SH), length, width, thickness, mass of the individual seeds,  1000- seeds mass, and changing these parameters with location of seeds on SH were measured.  Then shape properties, including geometric mean diameter, sphericity, surface area, projected area and volume of the seeds were calculated.  Variations of the shape properties of the seeds on the SH were studied.  Statistical indices for dimensional and shape parameters were calculated.  For Mikhi, Sirena, and Songhori varieties, true and bulk densities, porosity, angle of repose on wood and galvanized surfaces were calculated by using standard methods in the moisture of 9.15, 5.26 and 5.62% (w.b.), respectively.  The distribution of distance between adjacent seeds on SH was modeled by using three continuous statistical distributions namely Normal, two-parameter Log-normal and two-parameter Weibull distribution.  Size and mass of seeds were modeled with two-parameter Weibull distribution.  The parameters of the probability density functions (PDF) were estimated, then evaluated, and the predictive performances of the models were compared.  Log likelihood goodness of fit test was used to test how well different PDFs work for prediction of the distance between seeds on sunflower head, size and mass of seeds.   The results for three varieties showed that when the distance between locations of the seed from center of the sunflower head increased, size, shape properties and mass of seed, increased, too.  The values of true and bulk density, porosity and angle of repose on wood and galvanized surfaces for Mikhi variety were 497.500 kg/m3, 331.027 kg/m3, 33.46% , 25.08° and 22.23°, for Sirena were 580.368 kg/m3, 422.015 kg/m3, 27.28%, 26.80° and 23.86°, and for Songhori were 471.746 kg/m3, 319.346 kg/m3, 32.30%, 24.39° and 21.70° respectively.  Modeling result for the distance between adjacent seeds on SH showed that, Log-normal distribution model fits the empirical probability density well and two-parameter Weibull distribution had worst performance for prediction.  Also modeling result for the distance between adjacent seeds on showed that whenever Skewness and Kurtosis had negative value, Weibull distribution was best fit.  Statistical analyses for dimensional properties and mass showed that in most cases, both Skewness and Kurtosis had negative values.  Therefor for modeling dimensional properties and mass, Weibull distribution was used. Keywords: sunflower seed, normal modeling, two-parameter log-normal modeling, two-parameter Weibull distribution modeling, physical properties

Design, construction and evaluation of preliminarily machine for removing sunflower seeds from the head using air-jet impingement

To design a sunflower machine for removing seeds from sunflower head (SH) based on air-jet impingement, preliminarily model of such machine was designed, constructed and evaluated.  Effects of the seed location, angle of impingement, distance between nozzle outlet and sunflower head, and rotational velocity of sunflower head on percentage of extracted seeds were examined.  In order to examine the effects of air-jet parameters on percentage of removed seeds in different locations of seed on sunflower head, sunflower heads were divided into three regions, namely central region, middle region and side region.  Results indicated that in all three regions, with increasing rotational velocity from 10 to 30 rev/min, percentages of removed seeds from the SH decreased.  Results also indicated that in all three regions, with increasing distance between nozzle outlet and SH surface from 10 to 20 mm and decreasing distance between nozzle outlet and SH surface from 40 to 20 mm, percentage of removed seeds from the SH by air-jet increased.  Results indicated that in side region, with decreasing angle of impingement from 90% to 30%, of removed seeds from the SH by air-jet increased and in middle and central regions, with increasing angle of impingement from 30º to 60º and decreasing angle of impingement from 90º to 60º, percentages of removed seeds from the SH by air-jet increased.  Also in all tests, no seed damaged due to air-jet impinging was observed.   Keywords: preliminarily model; angle of impingement; nozzle; rotational velocity; sunflower head; seed locatio

Mathematical modeling of thin layer solar drying of tomato slices

Thin layer drying of tomato slices was evaluated using a laboratory solar dryer.  The experimental moisture ratios of the samples were fitted to nine drying models.  The drying experiments were carried out on tomato slices with thicknesses of 3, 5 and 7 mm at the air velocities of 0.5 and 1 m s-1.  The effect of drying thickness and air velocity on the drying time was evaluated.  The mathematical models were tested with the drying behavior of tomato slices in the laboratory solar dryer.  The coefficients of the models were determined by multiple regression method in three spaces (solar dryer, shadow, open sun drying) to find out the most suitable moisture ratio model.  The Page model was found as the best model based on statistical parameters of R2, RMSE and χ2.  The Page model is applicable to predict moisture content of tomato slices during solar drying of tomato slices.   Keywords: pedal operated thresher, thresher, thresher drive linkage, physiological workloa

Some physical properties of almond nut and kernel and modeling dimensional properties

Three main dimensions of nut and kernel of almonds were measured.  Then some dimensional properties of nut and kernel were calculated.  Effect of the moisture content on bulk density, true density, porosity and coefficient of friction of kernels and nuts were studied.  Angle of repose on iron, plywood and galvanized sheet were measured.  Also in order to examine the correlation between two dimensions of kernels and nuts and correlation between one dimension of nuts and similar dimension of kernels, linear and quadratic regression were used.  Length, width and thickness distributions of nuts and kernels were modeled using normal, log normal, Weibull and Generalized Extreme Value distributions.  For modeling other dimensional properties, only Generalized Extreme Value was used.  The estimated parameters of the PDF for three main dimensions of nuts and kernels indicated that G.E.V was best fit.  With increasing moisture content of the kernels from 4.20% to 29.64% (w.b.), true density and porosity were increased from 939.629 to 1,077.428 kg m-3 and 37.704% to 57.088%, respectively; and bulk density was decreased from 585.350 kg m-3 to 462.343 kg m-3.  When the moisture content of the nuts increased from 4.03% to 28.13% (w.b.), true density and porosity were increased from 1,025.124 kg m-3 to 1,149.700 kg m-3 and 38.562% to 56.55%, respectively, and bulk density was decreased from 629.81 kg m-3 to 499.532 kg m-3.  Values of coefficient of friction on all surfaces were increased with increasing moisture content.   Keywords: gravimetric properties, regression, log likelihood, normal distribution, Weibull distribution,generalized extreme value distribution, almond nu

Determination of some physical properties of virgin olive fruits

Information on physical properties of virgin olive fruit, especially those grown in Iran,arenot available in literatures. Some physical properties of Mari variety of virgin olive fruits,namely: dimensional properties (length, width, thickness, arithmetic mean diameter, geometric mean diameter, sphericity, volume of the fruit, surface area and projected area), gravimetric properties(unit mass of fruit, 1,000 fruit mass, bulk density, true density and porosity), frictional properties (angle of repose and coefficient of friction), modeling dimensional properties and mass (using normal distribution) were studied. Also sphericity, volume, surface area and projected area were calculated using different theoretical equations. Length, width and thickness of fruits ranged from 18.46 mmto 27.63 mm, 15.80 mmto 21.99 mm and 14.77 mm to 20.33 mm, respectively. Bulk density of fruits increasedfrom 590.78 kgm-3 to 646.51kgm-3 as the volume container increased from 500 ml to 2,000 ml and true density of 1,059.14kgm-3were obtained. The highest value forangle of repose and coefficient of friction amongplywood, rubber, iron and galvanized surfaceswererecorded for iron surface and the lowest value was recorded for galvanized surface.   Keywords: normal distribution, dimensional properties, gravimetric properties, frictional properties, modelin

Development and performance evaluation of a combined infrared and hot air dryer

In this study, a laboratory scale infrared and hot air dryer was developed in which some parameters such as the temperature of drying chamber, input air temperature, air flow rate and distance from the infrared source was adjustable by operator. Drying of tomato thin layers was performed under various combinations of these parameters. Experimental results showed that drying time for temperatures of 60, 70 and 80 °C was 60, 75 and 116 minutes, respectively. Drying is directly related to the amount of operational infrared power. Moreover, drying time for two air velocities of 0.6 and 1.1 m s-1 was 109 and 95 minutes, respectively. Increasing the drying air velocity leaded to reduction of drying time because of an increasing in evaporation rate of moisture from the surface of the product at low speeds. Results showed that by increasing the distance of drying chamber from the infrared source, drying time will increase due to reduction of heat that transferred to the product. Minimum and maximum drying times were belonging to the temperatures of 80 and 60 °C, respectively. Also, the drying rate was directly related to the velocity and temperature of input air