Modeling
Z. Zibahoosh; J. Khodaei; S. Zareei
Abstract
IntroductionThe most costly part of poultry breeding is feeding. Due to the noticeable developments in animal husbandry and agricultural sectors, it is necessary to use the mechanized methods to reduce the casualties, increase the productivity as well as reduce the time and cost in each of these sectors. ...
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IntroductionThe most costly part of poultry breeding is feeding. Due to the noticeable developments in animal husbandry and agricultural sectors, it is necessary to use the mechanized methods to reduce the casualties, increase the productivity as well as reduce the time and cost in each of these sectors. Reducing the particle size is one of the ways to process cereals which improves the mixing and also the nutritional value of the feed and the quality of the pellet feed. Optimizing the performance of hammer mill with the aim of reducing the size of different materials for poultry feed, would be very beneficial for obtaining the minimum cost of food, maximum quality and capacity. The main objective of this research was to optimize the operational variables, including sieve size, grain moisture content, feed rate and the number of hammers, each of them at three levels, on a hammer mill during the process of poultry food production from wheat, corn, barley and soybean grains. Materials and MethodsThe seeds used in experiments were wheat (Azar2 variety), corn (Brazilian variety), soybean (Danpars variety) and barley (Aras variety). A laboratory hammer mill was used to perform experiments. The treatments including sieve diameter (2, 2.3and 4.4 mm), grain moisture content (10, 14 and 18%), seed input rate to milling compartments (one-third, two-thirds and fully openness of tank gate) and the number of hammer (12, 18 and 24) were investigated. In order to measure the working capacity of the hammer mill, the required time for milling was recorded. The amount of final milled crop in each experiment was weighed and divided into the needed time for milling. Sieve analysis was used to determine the distribution and dispersion of the milled material which works according to the standard of ASTM E-11-70 Part 41 (Anonymous, 2004). In this study, the effects of input variables were investigated using the response surface method focusing on the central composite design approach to optimize the fineness degree and working capacity of the mill. The Design Expert 8.0.6 software was applied for statistical analysis, modeling and optimization. Results and DiscussionThe results indicated that sieve size and the number of hammers have been affected by the fineness degree of wheat grains, significantly. In addition, all four factors and interaction effects between sieve size and moisture content and also moisture content and number of hammers influential working capacity at the significant level of 1%. In the case of corn, the influence of moisture content and its interaction with sieve size on grain fineness, and the effect of sieve size, moisture content, feed rate and interactions between sieve size and moisture content and moisture content and feed rate of working capacity were significant at the level of 1%. For barley, moisture content at the level of 1% and interaction between sieve size and moisture content at the probability level of 5% were effective on barley fineness degree. Meanwhile, the moisture content at the level of 1% and sieve size and its interaction with moisture content at the level of 5% influenced working capacity, significantly. Soybeans were not able to respond the required moisture level for the experiments due to their soft and brittle texture, whereas unreliable results were obtained by changing its moisture levels. The best size of sieve holes, grain moisture content, feed rate and the number of hammers were determined to minimize the fineness degree and maximize the working capacity of the hammer mill. ConclusionIn this research, the response surface method considering a central composite design was used to optimize the operational variables of a hammer mill, including sieve hole size, grain moisture, feed rate and the number of hammer to produce poultry feed with the aim of achieving a minimum fineness degree (more grain crushing) and maximum milling capacity. The results of variance analysis were presented for wheat, corn, barley and soybean. Regression models could represent the relationship between the independent variables and the outputs with high confidence coefficient, and the best values of input variables were determined to optimize grinding operation.
Modeling
M. Mehrijani; J. Khodaei; S. Zareei
Abstract
Introduction Tillage as a preliminary step for agricultural production consumes large amounts of energy. Regarding the energy crisis and the greenhouse gas emissions caused by the indiscriminate use of fossil fuels, many efforts have been done to reduce energy consumption as much as possible. About half ...
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Introduction Tillage as a preliminary step for agricultural production consumes large amounts of energy. Regarding the energy crisis and the greenhouse gas emissions caused by the indiscriminate use of fossil fuels, many efforts have been done to reduce energy consumption as much as possible. About half of the energy used in the crop production has been dedicated to tillage operations; hence the optimization of tillage tools performance can lead to decrease the energy loss. Tillage operation in most regions of Iran is carried out by moldboard plow. The ability of this plow in turning the soil has made it impressively different from the other plows. The energy used in tillage operations depends on various factors such as soil type and its conditions (soil moisture and texture), plow depth and forward speed. The aim of this study is to investigate the effect of forward speed, plow depth and soil moisture on fuel consumption and required tensile force during tillage operation with a moldboard plow which uses three plows in clay soil. Materials and Methods The current study was carried out to optimize the tillage operation with a moldboard plow in the clay soil. Tillage experiments were performed to evaluate the effect of forward speed, plow depth and soil moisture content on the required tensile force and tractor fuel consumption. A moldboard plow with three single-sided plows was used to conduct experiments. Two tractors (MF285 and U650) and a dynamometer were used to measure the required tensile force. To measure the fuel consumption of the tractor during operation, the fuel level was measured in a separate tank system installed on the tractor's fuel system. Experiments were carried out using response surface method and central composite design (CCD) by taking three levels of forward speed (4, 5 and 6 kmh-1), three plow depth (20, 25 and 30 cm) and three levels of soil moisture content (12, 16 and 20%). Design Expert 8.0.6 software was used to analyze the experimental data. Results and Discussion The result of the analysis of variance showed that the effects of plow depth, forward speed and soil moisture, as well as the interaction between forward speed and moisture content on the fuel consumption during tillage operations with moldboard plow are significant. The results also indicated that the increase in forward speed decreased the fuel consumption. Also, fuel consumption decreased with increasing in moisture content at first, but then increased. The reason for this was probably because of the increased strength of soil particles due to the reduced moisture content (the stronger coherence force between the particles), which required more energy to shear the soil. According to the results of analysis of variance, it can be concluded that all three factors of forward speed, plow depth and soil moisture had a significant effect on the required tensile force of moldboard plow at %1 probability level. With increasing the plow depth and forward speed, required tensile force increased significantly. The dependent variables were modeled as second order regression equations and optimal values of independent variables were determined. Optimum performance with maximum desirability was determined at forward speed of 5.08 kmh-1, plow depth of 20 cm and soil moisture content of 16.41%. Conclusion With increasing plow depth, tensile force and fuel consumption increased. Also, tensile force increased with increasing forward speed, but this increase was not severely affected by the plow depth and reduced the fuel consumption. The quadratic regression models can well predict the required tensile force and fuel consumption. Using response surface method, optimum performance was determined at forward speed of 5.08 kmh-1, plow depth of 20 cm and soil moisture content of 16.41%.
H. Javadikia; Y. Nosrati; M. Mostafaei; L. Naderloo; M. Tabatabaei
Abstract
Introduction Biofuels are considered as one of the largest sources of renewable fuels or replacement of fossil fuels. Combustion of plant-based fuels is the indirect use of solar energy. Biofuels significantly have less pollution than other fossil fuels and can easily generate from residual plant material. ...
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Introduction Biofuels are considered as one of the largest sources of renewable fuels or replacement of fossil fuels. Combustion of plant-based fuels is the indirect use of solar energy. Biofuels significantly have less pollution than other fossil fuels and can easily generate from residual plant material. Waste and residues of foods and wastewater can also be a good source for biofuel production. Transesterification method (one of biodiesel production methods) is the most common forms to produce mono-alkyl esters from vegetable oil and animal fats. The procedure aims are reduction the oil viscosity during the reaction between triglycerides and alcohol in the presence of a catalyst or without it. In this study, the method of transesterification with alkaline catalysts is used that it is the most common and most commercial biodiesel production method. In this study, configurations of made hydrodynamic cavitation reactor were studied to measure biodiesel fuel quality and enhanced device performance with optimum condition. The Design Expert software and response surface methodology were used to get this purpose. Materials and Methods Transesterification method was used in this study. The procedure aims were reduction of the oil viscosity during the reaction between triglycerides and alcohol in the presence of a catalyst or without it. Materials needed in the production of biodiesel transesterification method include: vegetable oil, alcohol and catalysts. The used oil in the production of biodiesel was sunflower oil, which was used 0.6 liters per each test in the production process base on titration method. Methanol with purity of 99.8 percent and the molar ratio of 6:1 to oil was used based on titration equation and according to the results of other researchers. The used catalyst in continuous production process was high-purity sodium hydroxide (99%) that it is one of alkaline catalysts. Weight of hydroxide was 1% of the used oil weight in the reaction. Response surface methodology: Three important settings of reactor were considered to optimize reactor performance, which include: inlet flow to reactor, reactor rotational speed and the fluid cycle time in the system. Each set was considered at three levels. The factorial design was used to the analysis without any repeat, there will be 27 situations that because of the cost of analysis per sample by GC, practically not possible to do it. Therefore, response surface methodology was used by Design Expert software. In the other words, after defining the number of variables and their boundaries, software determined the number of necessary tests and the value of the relevant variables. Results and Discussion Three parameters include the inlet flow to reactor, reactor rotational speed and the fluid cycle time in the system were considered as input variables and performance of reactor as outcome in analyzing of extracted data from the reactor and GC by Design Expert software. The results of tests and optimization by software indicated that in 3.51 minutes as retention time of the raw material of biodiesel fuel in the system, the method of transesterification reaction had more than 88% Methyl ester and this represents an improvement in reaction time of biodiesel production. This method has very low retention time rather than biodiesel fuel production in conventional batch reactors that it takes 20 minutes to more than one hour. Conclusion According to the researches, efficiency of biodiesel fuel production in hydrodynamic cavitation reactors is higher than ultrasonic reactors so in this study, the settings of hydrodynamic reactor were investigated so that the settings were optimized in production of biodiesel fuel. Sunflower oil was used in this research. The molar ratio of Methanol to oil was 6 to 1 and sodium hydroxide as a catalyst was used. Three important settings of reactor were considered which include: inlet flow to reactor, reactor rotational speed and the fluid cycle time in the system. The results were analyzed by gas chromatography. The results showed that at 8447 rpm of reactor speed, inlet flow of reactor at 0.86 liters per minute and 1.02 minute of circulation time, the best performance of reactor were created. The flash point, kinematic viscosity and density of biodiesel in this study were 172 °C, 2.4 square millimeters per second and 861 kg per cubic meter, respectively. Maximum and minimum performances of hydrodynamic cavitation reactor in biodiesel production were 6.19 and 1.13 mg kJ-1, respectively.
B. Hosseinzdeh Samani; E. Fayyazi; B. Ghobadian; S. Rostami
Abstract
Introduction
Biodiesel is a promising renewable substitute source of fuel produced from tree born oils, vegetable based oils, fats of animals and even waste cooking oil, has been identified as one of the key solutions for the alarming global twin problems of fossil fuel depletion and environmental degradation. ...
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Introduction
Biodiesel is a promising renewable substitute source of fuel produced from tree born oils, vegetable based oils, fats of animals and even waste cooking oil, has been identified as one of the key solutions for the alarming global twin problems of fossil fuel depletion and environmental degradation. One of the sources for biodiesel production is mastic which is often grown in mountains. Its kernel contains 55% oil which makes it as a valuable renewable resource for biodiesel production. The objective of this research was to study of the feasibility of biodiesel production from Atlas mastic oil using ultrasonic system and optimization of the process using Response surface methodology.
Materials and Methods
In order to supply the required oil for the biodiesel production process, the oil should be prepared before the reaction. Hence, the purified oil was methylated using Metcalf et al (1996) method, and the prepared sample was injected into Gas Chromatography device to determine fatty acids profile and molecular weight of the used oil. An ultrasonic processor (Hielscher Model UP400S, USA.) was used to perform the transesterification reaction.
All the experiments were replicated three times to determine the variability of the results and to assess the experimental errors. The reported values are the average of the individual runs. The different operating parameters used in the present work, to optimize the extent of conversion of Atlas pistache oil, include methanol to oil molar ratio (4:1, 5:1 ,6:1), amplitude (24.1, 62.5 100%), pulse (24.1, 62.5 100%), reaction time (3, 6, 9 min).
Results and Discussion
Results of analyses showed that the independent variables, namely molar ratio, vibration amplitude, pulse and reaction time had significant effects on the amount of produced methyl ester.
By increasing the amplitude and pulse, the methyl ester content increased. Increase in amplitude and pulse cause to increase the mixing effect and physical interface. Increasing the ratio of ultrasonic working time to its idling time caused to an increase in the conversion percent. Because the treating time of the samples by ultrasound in limit time durations is increased, while this increase becomes lower at higher ratios. This is due to the fact that the initial vibrative shock acted on the samples after ultrasonic restarting, finds an identical effect with uniform wave. However, the idling phase of ultrasound caused a decrease in the amount of consumed energy. Similar results have been reported by Chand et al. (2010) for the effect of pulse on conversion percent of methyl ester. Trend of reaction time and molar ratio were different with trend of amplitude and molar ratio on methyl ester content so that they were divided to two sections. It should be mentioned that the increase in biodiesel yield because of molar ratio has some limitations. If the ratio is increased more than a certain extent, biodiesel conversion percent will decrease. The main reason for this result can be related to the amount of methanol increase in the mixture, which leads to more dissolution of glycerin and alcohol in biodiesel which considerably influences its purity.
Optimization was carried out based on Response Surface Methodology (RSM) using Design Experts software. The obtained results from optimization were as follow: 5.45 molar ratio, 0.89 amplitude, 0.71 pulse and 5.99 minutes of time. The conversion percentage obtained as 94.96. It is worthy to note that the experiment was iterated at suggested point by the optimization software and the conversion percent was 94.02. As well as 34792.37 J at the obtained point to be acceptable (1%) difference from the model.
Conclusions
The increase in the ultrasound amplitude resulted in an increase in the conversion percentage which tends to ascend. Also, the increase of reaction time by 5 to 7 minutes increased the conversion percentage, following which is the descend trend. The obtained results from optimization were as follow: 5.45 molar ratio, 0.89 amplitude, 0.71 pulse and 5.99 minutes of time. The conversion percentage and consumed energy obtained as 94.96 and 32421.5 J, respectively. It is worthy to note that the experiment was iterated at suggested point by the optimization software and the conversion percent was 94.02.
