Design and Construction
J. Soleimani; M. H. Kianmehr; S. R. Hassan Beigi Bidgoli; S. M. Shariatmadari; K. Rezapoor
Abstract
Introduction The annually production of cattle manure is estimated around six million tons in Iran. Manure transportation with high moisture and low density recognized as crucial issue. The densification of dry or wet manure is the profound method for decreasing the manure volume which reduces the cost ...
Read More
Introduction The annually production of cattle manure is estimated around six million tons in Iran. Manure transportation with high moisture and low density recognized as crucial issue. The densification of dry or wet manure is the profound method for decreasing the manure volume which reduces the cost of handling and storage. Besides, the particle size is one of the important factors in the pellet production. Ball mills, vibratory mills, hammer mills, knife mills, two roll mills, colloid mills, attrition mills, or extruders can be used for size reduction of biomass. Specific energy consumption for size reduction of biomass highly depends on moisture content, bulk and particle densities, feed rate of the material, particle size distribution (initial/final particle size) and machine variables. The present study is conducted for wet cattle manure size reduction machine. Furthermore, the relationship between moisture content (35, 40 and 45 %w.b) and drum of special size reduction machine in rotational speed (150, 200 and 250 rpm) considering geometric mean diameter of particle and size distribution of wet cattle manure were investigated. A factorial experiment under randomized complete design method was employed with three replications. Materials and Methods The main parts of machine include drum, concave, spring and adjusting screw. The main function of this thresher machine is to combine crushing and cutting in order to conduct the size reduction methods, i.e., to apply compressive and shear forces to the cattle manure particles. The drum is also equipped with several rows of sharp-edged milling segments. The spring constants were determined by evaluating the slope of the force vs. deflection curves. The rotational speed of drum was changed in the range of 100-700 rpm during these experiments. In the test of the machine physical properties of grinds such as geometric mean diameter of grind particles and particle size distribution were determined. One kg of cattle manure was grinded in each test and the particle size distribution of grinded cattle manure was determined according to ASAE standard S319.3. The moisture content of cattle manure was obtained according to ASAE standard S358.3. Results and Discussion The initial and final particle size of the materials are 20 millimeters and less than 5 millimeters, respectively and the angle of nip is 30 degrees (according to the installation space limitations), the diameter of the drum is 310 millimeters. The spring constant was equal to 24.371 N mm-1 and on the basis of the experiments a drum speed in the range of 150–250 rpm is considered to be optimal settings for the milling for cattle manure disintegration. The results of Table 4 show that for wet cattle manure with 35% (w.b) moisture content at 250 rpm rotational speed of drum (P > 0.05; Skewness = -0.056; Kurtosis = -2.15), 40% (w.b) moisture content at 250 rpm rotational speed of drum (P > 0.05; Skewness = 0.076; Kurtosis = -1.77), 45% (w.b) moisture content at 200 rpm rotational speed of drum (P > 0.05; Skewness = 0.095; Kurtosis = -1.72), in grinds that would potentially produce better compacts. The geometric mean particle size and standard deviation for each test are shown in Table 2. According to Table 2, the lowest geometric mean of particle size is related to rotational speed of 200 rpm and a moisture content of 45% (w.b), and the highest at rotational speed of 250 rpm and a moisture content of 45% (w.b) can be observed. Conclusion The use of cattle manure of thresher machine reduces the specific energy consumption of cattle manure by 92% compared to the conventional method (using drying and hammer mill) in the pellet production. The lowest geometric mean diameter of wet cattle manure was 1.02 millimeter for drum rotational speed of 200 rpm at 45% (w.b) moisture content and the highest was 1.38 at rotational speed of 250 rpm and a moisture content of 45% (w.b%). The best particle size distribution was observed for milling of wet cattle manure with 35% (w.b) moisture content at 250 rpm rotational speed of drum (P> 0.05; Skewness = -0.056; Kurtosis = -2.15), 40% (w.b) moisture content at 250 rpm rotational speed of drum (P> 0.05; Skewness = 0.076; Kurtosis = -1.77), 45% (w.b) moisture content at 200 rpm rotational speed of drum (P> 0.05; Skewness = 0.095; Kurtosis = -1.72)
F. Ranjbar; M. H. Kianmehr
Abstract
Introduction Today, hybrid seeds are expensive because the company that produces them spends a lot of money on research and development that often takes years to accomplish. So precise planting of seeds in order to create the best growing condition for all seeds is important. Modified size and shape ...
Read More
Introduction Today, hybrid seeds are expensive because the company that produces them spends a lot of money on research and development that often takes years to accomplish. So precise planting of seeds in order to create the best growing condition for all seeds is important. Modified size and shape of seeds for precision planting, providing macro and micro nutrients since the start of seed germination and control pests and diseases are goals that are possible by coating seeds. The overall process of seed coating or seed pelleting comprises a number of important stages: 1- Droplet formation 2- Droplet travel 3- Impingement 4- Wetting 5- Spreading 6- Coalescence. Seed coating was largely borrowed from the confectionery industry which had developed this technique over the ages and is still widely used today. The seed industry concentrated on using the rotary drum or pan. This type of pan or drum was used for batches of up to 150–200 kg. Some rotary drum coater were developed subsequently which improved handling, particularly in the way the drying air was introduced and extracted. The pan of drum rotary coater is placed at the end of a tilted rotating shaft that is turned at a constant speed about 15- 20 rpm. Then a nozzle is spraying proper amount of coating solution on the seeds. The aim of this study was to evaluate technology and determine the factors affecting its quality coverage. Materials and MethodsThis experiment lay out in factorial experiment based on random complete block design with three replications. The first factor was vertically distance nozzle from seed bed in two levels 150 and 300 mm, second factor was the nozzle installed location in two levels installed in 1/4 diameter upper center and in center of cylinder, and third factor was concentration of binder polyvinylpyrrolidone (PVP) in three levels 50, 75 and 100 g kg-1 kaolin. In order to measure the pellet error percent, first 100 pellets were selected and broken. No seed or multi-seed pellets were counted. For measuring physical strength of pellets, instron machine were implemented in physical properties laboratory in Aborihan department of Tehran University. Its load cell capacity was 490 N. Forward speed of the instron was 5 mm per minute. Germination test were performed in the laboratory in dryland agricultural substitute Sararood, Kermanshah. Results and DiscussionThe results showed that the nozzle distance from the seed bed had a significant effect on all measured traits (1% level). With increasing distance from the seed bed, the physical strength of pellet and the percentage of pellet error decreased but germination increased. In fact, with increasing nozzle distance from 150 mm to 300 mm, the physical strength of pellet decreased from 22.8 N to 21.4 N, the pellet error decreased from 4.1% to 2.1% but germination increased from 71.3 to 73.4 percent. The used binder quantity had a significant effect on all measured traits (1% level). By increasing of using binder, the physical strength of pellet and the percentage of pellet error increased but germination strongly decreased. In the other word, with increasing used binder from 50g to 100g per one kilogram kaolin, the physical strength of pellet increased from 13.9N to 29.1N, the pellet error increased from.2.01 to 4.18 percent but germination decreased from 90.42 to 53.17 percent. The nozzle installed location had a significant effect only on the pellet error (1% level). In the other word, the nozzle installed on the cylindrical center is better than nozzle installed in 1/4 diameter upper center. There was negative significant correlation (r=-0.96) between physical strength shell characteristics and germination. So increasing the physical strength of the shell is reduced germination. There was a significant correlation (r= 0.621) between physical strength and pellet error percentage. So with increasing physical shell strength, pellet error was increased.
H. Bagheri; M. Rasekh; M. H. Kianmehr
Abstract
Introduction Lentil (Lens culinaris medic) is an important and highly nutritious crop belonging to the family of legumes. Lentil is cultivated worldwide but competition with weeds is a problem affecting production and can reduce yield by more than 80%. The study on the separation of impurities in bulk ...
Read More
Introduction Lentil (Lens culinaris medic) is an important and highly nutritious crop belonging to the family of legumes. Lentil is cultivated worldwide but competition with weeds is a problem affecting production and can reduce yield by more than 80%. The study on the separation of impurities in bulk lentils (Euphorbia helioscopia weed, Wild oat weed and etc.) by a gravity separator has an extreme importance. Since no study has been done to date, in this study, the effects of different parameters of a gravity separator (longitudinal and latitudinal slopes, oscillation frequency and amplitude) on the separation of foreign matters in lentil seeds were evaluated. A dimensionless number (v/aω) which shows ration of air current velocity blown to lentil to the maximum velocity of table oscillation, was considered in ratio of separation. Materials and Methods In this research, lentil samples were taken from farms in Ardebil Province (Bileh-Savar cultivar). A gravity separator apparatus was also used for separating impurities from lentil seeds. A Laboratory Gravity Separator Type LA-K (Westrup A/S Denmark) was used to separate impurities from bulk lentils. In this machine, table settings were as follows; longitudinal slope parameters (1°,1.5°, 1.75°, 2° and 2.5°), latitudinal slope (0.5°, 1°, and 1.5°), frequency of oscillation (380, 400, 420 and 450 cycles min-1), and amplitude of oscillation (5 and 7 mm), these settings were all adjustable. Similarly, the instrument had 5 boxes whereby, through proper adjustment, the heavier material was transferred toward the right side of the table and lighter material moved toward the left side. Through proper adjustment of the main parameters of the instrument, the impurities were separated from bulk lentils. Then using an electronic seed counter, five groups of seed which each group containing 100 seeds were counted and selected. Results and Discussion The results of variance analysis of the factorial design with three factors of table settings; (longitudinal slope at 5 levels, latitudinal slope at 3 levels, and frequency of oscillation of the table at 4 levels) are demonstrated in Table 1. It showed the main effect of table settings. Oscillation of frequency, latitudinal slope, and longitudinal slope, the mutual binary effect of latitudinal and longitudinal slope, the mutual binary effect of the latitudinal slope and the frequency of oscillation, the mutual binary effect of the longitudinal slope and the frequency of oscillation and the mutual triple effect of oscillation frequency, longitudinal slope, and latitudinal slope, were significant at the probability level of 1% and the mutual binary effect of the latitudinal slope and frequency of oscillation significant at the probability level of 5%. The results showed that increase of latitudinal slope of table and increase of longitudinal slope from 1 to 2 degrees will increase the separation percentage of impurities from lentil seeds. Moreover, the separation percentage of impurities from lentil seeds to longitudinal slope, under the various latitudinal slope and dimensionless number of (v/aω) and amplitude of oscillation of 5 mm and 7 mm, were investigated. Results showed that in all conditions with increasing of the longitudinal slope from 2^°-〖2.5〗^°, separation percentage of impurities from bulk lentils will decrease. This was due to the fact that under the stated conditions, distribution of seeds on the surface of the table was more homogenous. Note that at the amplitude of oscillation of 7 mm, transference of materials towards the right side of the table output edge was halted and the surface of the table was not fully covered by the fed materials, and separation decreased. The results of the experiment showed that the maximum separation of impurities from bulk lentils was 90.2 percent (v/aω=171). Conclusion 1- Increased latitudinal slope of the table from 0.5° to 1° and longitudinal slope of table from 1° to 2° were resulted in increased separation percentage of impurities from bulk lentils. 2- The results demonstrated that at settings of longitudinal slope of 2°, latitudinal slope of 1°, and frequency of oscillation of 400 cycles min-1, air velocity of 5.7 m s-1 and amplitude of oscillation of 5 mm (v/aω=171), the maximum separation will be 90.2%. In this case, the output lentil seeds contained the least amount of impurities here.
H. Samimi Akhijahani; A. Arabhosseini; M. H. Kianmehr
Abstract
Introduction
Drying is one of the most common methods for storing food and agricultural products. During drying process, free water that causes the growth of microorganisms and spoilage of products is removed from the product. There are several methods for drying of agricultural products. one of the ...
Read More
Introduction
Drying is one of the most common methods for storing food and agricultural products. During drying process, free water that causes the growth of microorganisms and spoilage of products is removed from the product. There are several methods for drying of agricultural products. one of the most important methods of investment is drying by using sunlight. Iran is situated at 25- 43oE longitude and mean solar radiation is about 4.9 kwh.m-2.d-1. Because of the proper solar radiations in 95% of the agricultural areas in Iran, solar drying is widely used for drying of fruits and vegetables. The use of solar dryer causes saving in energy consumption and processing costs for drying of products in farms and gardens. Several researchers investigated heat transfer and heat flow in dryers. Selection of appropriate method was carried out for drying of agricultural products using heat pump. Experiments were done and mathematical relationships were estimated to obtain correlation parameters between Reynolds number and Nusselt number for the three cases of solar dryer (cabinet, indirect and combination).The best working conditions were determined for three types of solar collectors (flat, finned and corrugated). In this study, the process of heat transfer and heat transfer coefficient of a solar dryer with and without rotation of absorber plate was compared.
Materials and Methods
The experiments were conducted in Azarshahr, East Azarbayjan province, Iran in September 2014. Newton's law of thermodynamic was used to analyze the working condition of solar absorber. For this purpose the absorber plate was divided into four equal parts. According to the thermal equations and related boundary conditions as well as the relationship between heat transfer coefficient and the temperature gradient, equation 1 for the Nusselet number obtained:
1
Beside the relationship between Nusselt number and heat transfer coefficient is defined as equation 2:
2
Finally variation of total heat flow over the time at different surfaces of the collector is determined by using equation 3:
3
Two cases (solar panel with rotation and without rotation) were considered for testing. Data measuring was carried out for 9 hours from 8 to 17. The fluid flow rate was 0.0185m3.s-1. The dryer was installed in an environment with air temperature of 31.6 oC and 31.8 oC, with the air velocity of 0.58 m.s-1 and 0.54 m.s-1 and with the relative air humidity of about 21%and 21.5% at the first and second days, respectively. The dryer had an automatic temperature controller to fix the air temperature with an accuracy of ±0.1 oC. An anemometer Yk-2005AM model was used to regulate the required air velocity. The output data of the thermocouples was recorded by a digital thermometer (DL-9601A, Lutron) that was connected to a computer using RS232 cable and recorded the temperature at required point every an hour. The relative humidity of the ambient was measured every hour with a digital hygrometer (HT.3600, Taiwan), accuracy of 3%. By assembling controlling system with a DC motor, a precious photocell and a proper mechanism, the frame would rotate by the sun and followed solar radiation, therefore more solar energy produced in solar panel.
Results and Discussion
The results of the experiments showed that the heat transfer process increased in both cases from the early morning and reached to its maximum value around 12 to 14 o’clock. The trend was more homogeneous in the dryer by absorber plate without rotation due to the decline of the heat accumulation. The mean temperature rise in the solar dryer without rotation was 37oC and in the solar dryer with rotation was 54oC. Because of the rotation of solar plate, variations of solar radiation were low. Therefore, by rotation of the solar dryer panel the temperature rise was 27oC. The values of heat transfer coefficient in the solar dryer with rotation were decreased by the time. This reduction in the hours before noon is more than after noon. This is due to the reduction of the temperature gradient in the solar absorber plate. Also the results showed that heat transfer coefficient in the lower levels (S1 and S2) is more than higher levels (S3 and S4). Variations of the heat flow for the solar dryer with rotation is more than the other. Because in the first one, the absorber plate was followed the solar radiation and generated heat in the plate increases and the fan does not have the ability to discharge the generated heat. The total amount of heat transfer in absorber plate with rotation was 36.1% higher than the absorber plate without rotation. To increase the heat transfer from the dryer, design of the system to change air flow rate by increasing temperature, can increase the efficiency of the dryer.
Conclusions
In this study the performance of the absorber plate in a solar dryer in two cases with rotation and without rotation were compared. The results showed that by rotation of the solar absorber plate the output temperature of the collector rises about 27oC. Thermal fluctuation in the rotation solar plate is lower than the solar plate without rotation.
Y. Ghasemi; M. H. Kianmehr; B. Azadegan
Abstract
Nowadays compost fertilizers are suitable alternative to chemical fertilizers, due to the threats for human health and agriculture products. The most important problems for applying the compost fertilizer in the farm are: transportation (high volume), high moisture content, spreading problem, impurity ...
Read More
Nowadays compost fertilizers are suitable alternative to chemical fertilizers, due to the threats for human health and agriculture products. The most important problems for applying the compost fertilizer in the farm are: transportation (high volume), high moisture content, spreading problem, impurity such as dust and storage. To solve the problems mentioned, pressing process such as converting the compost to pellets and granules are suggested. In this research the effects of some granulation parameters on the percent of useful granules in a laboratory scale rotating drum was evaluated. The percentage of useful granules decreased by increasing the granulation time and increased by increasing the percentage of drum filling. The optimal conditions for granules production was achieved at drum rotational speed of 40.38 rpm, granulation time of 15 min, drum filling of 10% and molasse percentage of 40.97. According to these conditions, the response for useful granule was estimated as 81.6% with R2 of 0.924.
H. Bagheri; A. Arabhosseini; M. H. Kianmehr
Abstract
In this research, solar drying of a thin layer of tomato slices was evaluated. The experiments were carried out at the air velocities of 0.5 and 1.0 m s-1 and thicknesses of 3, 5 and 7 mm. In order to find the most suitable form of thin layer drying model, nine different mathematical drying models were ...
Read More
In this research, solar drying of a thin layer of tomato slices was evaluated. The experiments were carried out at the air velocities of 0.5 and 1.0 m s-1 and thicknesses of 3, 5 and 7 mm. In order to find the most suitable form of thin layer drying model, nine different mathematical drying models were fitted to the experimental data to determine the pertinent coefficients of each model. The goodness of the fit was determined by calculating and comparing the values of the correlation coefficient (R^2 ) Root mean square error (RMSE) and chi-square (χ^2) for all models. The Page model with R^2=0.9974 ,χ^2=0.01351 , RMSE=0.002 showed the best fit.
