جستجوی مقالات مرتبط با کلیدواژه "performance" در نشریات گروه "مکانیزاسیون کشاورزی"

Potato )Solanum tuberosum (is one of the strategic products which is cultivated in most of the regions in Iran. Peeling is one of the primary processes of this product and plays an important role in other processing steps. In this research, a combination of mechanical and chemical potato peelers was designed and manufactured. The peeler consists of a chasse, a motor, a power transfer system, and a drum equipped with three types of blades. Various experiments were carried out to determine the amount of losses and performance evaluation. The experiment was performed at three levels of blade type (knife, brush and carborundum type), four levels of feed rate (1, 2, 3 and 4 kg) and four levels of concentration of the chemical solution (0, 1, 2 and 3%, w/w). The experiment was factorial based on a completely randomized design with three replications. The results of the experiments showed that the effects of blade type, feed rate, and concentration of the chemical solution on the amount of losses and performance evaluation were significant (p>0.01). Maximum rate of peeling was achieved by applying the brush-type blade with a 1 kg feed rate and the 3% concentration of the chemical solution. The results showed that in all three types of blades and at each feed rate, the percentage of peeling increases with the increase in the concentration of sodium hydroxide chemical solution. Also, it was found that the combined chemical and mechanical peeling increases peeling, reduce the peeling losses, and improves the performance of the device.

The nut sunflower is usually cultivated in small farms and is harvested with a low capacity of harvester at high moisture content. For the rigid threshing components, impact and knead force are so large as it leads to crushing of the grain or inner stress. This reduces marketability and the germination rate of seeds. The mechanical damage degree of sunflower grain is influenced by the material of the threshing beaters, the velocity of impact, moisture contents, etc. Traditional manual methods, that separate grain from the sunflower head, take a lot of time, require large manpower, have high grain damage, and low efficiency. The objective of the present work was to develop and optimize a threshing unit for nutty sunflower that would combine safe impact velocities with appropriate adjusting of its variable to maximize threshing efficiency whilst minimizing grain damage resulting from shearing, cracking, or crushing.

The nutty Sunflower heads were procured from the Experimental Orchard of University of Tabriz, Iran at the moisture content of harvesting. Axial threshing units using kinematic equation and properties of the grain, designed and constructed that the variables of its components are adjustable. The beater of the thresher is flexible, which the deformation and vibration undergoing the overall rotation and impact process becomes larger with increasing speed and prevents grain damage. The power required for threshing and separation grain from heads was calculated at about 4.5 kW. Diameter and rotational drum speed value estimated using relation (V=  and study of other researches as considering critical impact velocity of sunflower grain. The length of the thresher was 1.2 m that estimated by determining the capacity and the number of beaters. Threshing efficiency (%), separation efficiency (%), and grain damage (%) were parameters of performance for study. The experimental design by the Response Surface Methodology in Design Expert software 11 with central composite experiment design developed and the affecting parameters on accuracy analyzed and optimized. The threshing unit was evaluated against three threshing drum speeds of 380, 280, and 180 (rpm), feed rates 4000, 3000, and 2000 (kg (head)h-1), moisture content of 60%, 45%, and 30 (%w.b).

The results showed that the models and effect of variables were statistically significant at the 95% confidence level. The moisture content on threshing efficiency and grain damage had the greatest effect followed by drum speed and feed rate. While for separation efficiency, the feed rate had the most influence. With reducing feed rate and moisture content the threshing efficiency increased, although the decrease in drum speed reduced it. This might be due to sunflower grains adhering loosely to the head at the low moisture contents. The maximum (99.81) and minimum (96.12) percentage of threshed heads was at the moisture content of 30 and 60, respectively. The separation efficiency increased with reducing of feed rate and moisture content. Though, drum speed had insignificant efficacy statistically. The sunflower heads with high moisture content are fragile and brittle, also at high feed rates, the number of impact forces and collisions of heads rises in the condition of threshing. Therefore, the extra MOG is produced and passed from the separator grille. The feed rate of 2000 kg h-1 and moisture content of 30% was the maximum point of separation efficiency that obtained 69.82%. The grain damage decreased significantly with reducing drum speed (380 to 180) and moisture content (60 to 30). This result may be due to the reasons that at higher moisture content the husk of grains becomes soft. The goal of optimization is maximizing threshing and separation efficiency and minimizing grain damage that the optimized values of variables were determined 292.134 rpm for drum speed, 2000 kg h-1 for feed rate, and 30.7406% (w.b) for moisture content.

A threshing unit of sunflower, using properties of grains and kinematic equation, was designed and constructed. The models and effect of the variable were statistically significant on performances. The moisture content had a greater effect than other factors on threshing efficiency (%) and grain damage (%). Also, the feed rate of crops in thresher had the most influence on separation efficiency (%). With decreasing the moisture content, threshing and separation efficiency increased and grain damage reduced. The threshing efficiency (%), separation efficiency (%), and grain damage (%) were reported in the range of 96.12 to 99.81, 57.34 to 68.55, and 0.49 to 1.25, respectively. The optimized points were determined at the drum speed of 292.134 m s-1, feed rate of 2000 kg h-1, and moisture content of 30.7406% (w.b).

Cooling systems such as refrigeration and air conditioning are considered as basics of everyday life. In these years, the demand for both energy/associated services to address economic and social along with ameliorate human comfort and health is continuously increasing. Since approximately 1850, the global use of fossil fuels (coal, oil and gas) has dramatically raised to dominate energy supply. However, the required energy for the above-mentioned applications is mainly generated by non-renewable electricity. Due to the depletion of fossil fuels as a source of electricity, the development of renewable energies for such systems is necessary. Considering all these issues, as cooling needs, most of the time coincides with the solar radiation availability; therefore, exploring solar energy seems an exciting idea. A number of investigations were performed to design/develop new cooling techniques using solar energy. A solar cooling system is capable of considerably reducing the environmental effects of traditional refrigerating machines while allowing significant energy saving. The present work searches for the best choice of configuration/design factors of food refrigeration systems combined with solar-powered absorption chillers unit in Ahvaz city as a case study.

 In the present study, a linear parabolic collector with specific dimensions, was made, so that first, the initial design of the collector with longitudinal dimensions of 1 and a width of 0.6 meters was selected by Katia software, and then using related relations and calculations of other structural parameters based on which the collector was built, the collector simulation was performed using NASA radiation data for the place and time of the experiments and by using the Transient Simulation Software and its performance in the days of the month July, August and September 2019 were reviewed and evaluated. According to the results, the average energy obtained for the collector in the three months of July, August, and September was about 216.054 w-h/m2. Finally, the area of the collector was calculated, the results showed that the required surface of the collector was found to be 584.687 m2. Also, the necessary calculations were performed on the results of performance tests by Excel software, and diagrams of changes in the radiant energy absorbed by the collector and the efficiency of the radiated energy absorbed were drawn from 10:00 AM to 6:00 PM. Using the diagrams obtained from the system simulation in TRNSYS (Transient System Simulation Tool) software, it is concluded that the built-in collector has the ability to produce a fluid with a temperature above 98 degrees Celsius required for the absorption chiller in July, August, and September.

 According to the evaluations of the collector's performance in the three months of July, August, and September from 10 AM to 6 PM showed that collector energy and efficiency reached their maximum values in July with 318.240 w-h/m2 and 63.05 %, respectively. While in August, the amount of energy and efficiency was found to be 299.311 w-h/m2 and 61.94%, respectively. According to the results, the average energy obtained for the collector in the three months of July, August, and September was about 216.054 w-h/m2. Finally, the area of the collector was calculated, the results showed that the required surface of the collector was found to be 584.687 m2.The minimum value of the parameters were recorded as 283.379 w-h/m2 and 61% in September, respectively. The potential analysis conducted showed an excellent saving potential in terms of energy obtained. According to the results, the useful collector energy was achieved to be 227.664 w-h/m2, 217.006 w-h/m2, and 210.406 w-h/m2 in July, August, and September, respectively. According to the obtained results, the maximum refrigeration load needed for the studied cold storage was about 126324 w. According to the results, the average energy obtained for the collector in the three months of July, August, and September was about 216.054 w-h/m2. Finally, the area of the collector was calculated, the results showed that the required surface of the collector was found to be 584.687 m2.

 The development of renewable energies for such systems is necessary. Solar cooling system for food products cold storage in Ahvaz city is a promising and innovative alternative to decline the peak energy consumption generated by the combustion of fossil fuels, especially during the summer months.

The declining global oil resources and increasing environmental problems are exacerbating the need to use other fuel sources to replace diesel and gasoline. Biodiesel is a fuel from vegetable oils or animal fats. Biodiesel is a fuel from vegetable oils or animal fats. The aim of this study was to evaluate the application of diesetrol fuel on the performance and pollution of the Massey Ferguson (MF-399) tractor engine. To evaluate the performance and pollution of the MF-399 tractor engine, distrol fuel was used in this study. Disterol is a mixture of diesel fuel and methyl ester of vegetable oil called biodiesel. Independent variables include the percentage of biodiesel, the percentage of ethanol and the PTO speed, and the dependent variables include torque, SFC, HC, NOx, CO, and CO2. For this purpose, biodiesel fuel was produced from castor oil using a trans-esterification reaction and its important features were matched with the ASTM D6751-09 standard. The performance of the tractor engine emissions using 5 to 15% of biodiesel fuel compounds, 2 to 6% of ethanol and diesel fuel were tested and evaluated. The results showed that the distance had a significant effect on all dependent variables, and the percentage of ethanol was effective only on the production of torque, and the percentage of biodiesel was effective on specific fuel consumption and production of carbon monoxide and carbon dioxide. NOx produced by the engine for the PTO speed and percentage of biodiesel (950 rmp, 15%) and (1000 rmp, 5%) were 2490 and 1198 ppm, respectively, which showed a decrease of 51%.

Today, maximizing the efficiency of fuels and increasing the output power of diesel engines is considered inevitable due to the increasing need for energy resources, the reduction of fossil fuel resources, the need to maintain the environment, reduce air pollution, and limit the electricity supply and fuel supply. In the large cities of Iran, the problem of vehicle pollution is one of the main problems. The lack of proper fuel, soot filters, and absence of requirement for a technical inspection of diesel vehicles have led to an increase in mortality and the growth of lung cancer due to pollution. All of studies indicate that fossil fuels, despite the low cost of production, will increase the cost of both living and environment. A solution for this crisis is to reduce the sources of pollutant-producing sources from the source of these pollutants. In the internal combustion engines, the compression ratio and alternative fuels are two important factors affecting engine performance and exhaust emission.

In this research, a one-dimensional computational fluid dynamics solution with GT-Power software was used to simulate a six-cylinder diesel engine to study the performance and exhaust emissions with different compression ratios and alternative fuels. The compression ratio was chosen to be 15:1 to 19:1 with an interval at unity. Alternative fuels such as (as base diesel), methanol, ethanol, diesel and ethanol, biodiesel and decane were selected. To modeling engine, first, all parts of the engine were introduced as a real six-cylinder engine, and then the required data were entered according to the actual engine conditions at the atmospheric pressure of one atmosphere. Before this investigation was carried out, a validation model for evaluation was done by experimental and simulation data. The validation results showed that software model error is acceptable and the model has a good capability of fitting and predicting.

The engine performance was evaluated in terms of engine power, engine torque, and specific fuel consumption at different engine compression ratio and fuel. The results showed that with increasing the compression ratio, brake power and brake torque increased. Among the fuels used in this engine, the maximum brake power and brake torque in the compression ratio of 19 with the decane fuel were 3.86% higher than that the base fuel and the lowest value was awarded in the compression ratio of 15, with methanol fuel and it was equal with 56.04%. The results indicated that by increasing compression ratio, the brake specific fuel consumption was reduced due to more power than the fuel consumed in the engine. A fuel with lower heating value should be injected more mass to the engine. This will increase the brake specific fuel consumption. In this research, the decane fuel with a compression ratio of 19 with a reduction of 3.72% had the lowest brake specific fuel consumption among other fuels. The CO emission from the engine largely depended on the fuel's properties, the availability of oxygen, the fuel mix with air, temperature, and turbulence inside the combustion chamber. The results highlighted that by increasing compression ratio, CO emission increased and CO emission in biodiesel fuel, with a compression ratio of 15, was decreased by 82.37% compared to the base. CO2 emissions are not too harmful to humans, but they increase the potential for ozone depletion and global warming. With increasing compression ratio, CO2 and HC emissions increased for all fuels, CO2 emissions have risen up the base. The fuel heating mechanism, combustion temperature, oxygen content, and gas fuel availability are the most important factors in the formation of NOx. With increasing the compression ratio, the amount of NOX increases, which is due to the high temperature in the cylinder at a higher compression ratio. The viscosity and density of fuels have an effect on NOX emission, and because of the larger droplets of the fuel, it released NOX. The highest NOx emissions from biodiesel fuel are due to the high oxygen content of this fuel and the lowest NOx emissions from decane fuel, due to the low density of the fuel compared to other fuels.

The results of this study showed that the decane fuel with a compression ratio of 19 in total had the best functional and pollutant characteristics among the six fuel used in this study. Therefore, this fuel can be the best alternative for diesel fuel.

The present research examined the study of the laboratory the effects of dew formation and humidity on the parameters mono crystalline and polycrystalline silicon solar panel. To create statuses dew formation equipped test lab device performance solar panel systems to environmental monitoring temperature and relative humidity. were evaluated this study dew formation of air relative humidity of 45, 60 and 75 percent at 25 degrees Celsius temperature on the surface the panel. The results showed that dew formation on the surface of the solar panel increases the performance parameters relative to humid weather conditions. The effects of the type of silicon panel and the relative humidity of ambient were very significant (p

Depletion of fossil fuels and environmental degradation are two major problems faced by the world. Today fossil fuels take up to 80% of the primary energy consumed in the world, of which 58% is consumed by the transport sector alone (Mard et al., 2012). The combustion products cause global warming, which is caused of emissions like carbon monoxide (CO), sulfur dioxide (SO2) and nitrogen oxides (NOX). Thus it is essential that low emission alternative fuels to be developed for useing in diesel engines. Many researchers have concluded that biodiesel holds promise as an alternative fuel for diesel engines. Biodiesel is oxygenated, biodegradable, non-toxic, and environmentally friendly (Qi et al., 2010).
In this study transesterification method was used to produce biodiesel, because of its simplicity in biodiesel production process and holding the highest conversion efficiency.
Transesterification of poultry fat oil and the properties of the fuels: Fatty acid methyl ester of poultry fat oil was prepared by transesterification of oil with methanol in the presence of KOH as catalyst. The fuel properties of poultry fat oil methyl ester and diesel fuel were determined. These properties are presented in Table 1.
Tests of engine performance and emissions: After securing the qualitative characteristics of produced biodiesel, different biodiesel fuels of 5%, 10%, 15%, and 20% blended with diesel fuel were prepared. A schematic diagram of the engine setup is shown in Fig.1. The MF-399 tractor engine was used in the tests. The basic specifications of the engine are shown in Table 3. The engine was loaded with an electromagnetic dynamometer. The Σ5 model dynamometer manufactured by NJ-FROMENT was used to measure the power and the torque of the tractor engine. The speed range and capacity of this device are shown in Table 2. A FTO Flow Meter, manufactured by American FLOWTECH Company, was used to measure the fuel consumption (Fig.3). Its measuring range is 37-1537 ml min-1.
The engine performance was evaluated in terms of engine power, engine torque and specific fuel consumption at different engine speeds. The variation of engine torques with B5, B10, B15, B20 and diesel fuel are presented in Fig. 4. The engine torque for biodiesel blends was more than that by diesel fuel only. The mean engine torques for B5, B10, B15 and B20 were 2.5%, 2.8%, 3%, and 3.5% higher than that by only diesel, respectively. This is due to the better combustion of biodiesel compared to diesel fuel. The variation of engine powers with B5, B10, B15, B20 and diesel fuel are presented in Fig. 5. The engine powers for biodiesel blends were more than that by diesel fuel. The mean engine powers for B5, B10, B15 and B20 were higher than that by diesel by 2.5%, 3%, 3.5%, and 4%, respectively. This is because of good combustion of biodiesel resulted from higher oxygen content. The mean specific fuel consumptions for B5, B10, B15 and B20 were higher than diesel fuel about 4.1%, 7%, 8.8%, and 2%, respectively (Fig. 8). The density of biodiesel was higher than that of diesel fuel, which means the same fuel consumption on volume basis results in higher specific fuel consumption in case of biodiesel.
The values of viscosity, density and flash point of poultry fat oil biodiesel were found to be closely matched with ASTM D-6751 standard specifications. Viscosity and density of biodiesel were found more than those for diesel. The calorific value of biodiesel was found to be lower than that of diesel. Poultry fat oil biodiesel cannot be used as a neat diesel fuel in cold weather conditions due to its relatively low cloud point. Preheating and lowering freezing point is required to eliminate this problem. The engine performance with poultry fat oil biodiesel and its blends are comparable with those of pure diesel fuel. Results indicated that B20 blend had the best performance and the lowest specific fuel consumption.

The quality of human life is directly affected by water resources planning and management. Major portion of this resources used for agricultural purposes. Irrigation networks that are built to provide water needed for agriculture, have significant role in efficient use of water resources. Many years have passed since the construction of the irrigation networks, most of them have shown low performance; Therefore, improvement of existing irrigation networks to improve their performance is essential. Involvement of so many components in irrigation networks rehabilitation and their complex interactive relation on system performance, requires a long term, integrated and systemic. Recently, system dynamics approach have been used for irrigation networks rehabilitation studies. Considering the importance of farmr's participation and management improvement on performance of irrigation networks, in this paper, the system dynamics model of Qazvin irrigation network was completed with regard to these issues. In addition to physical aspects of irrigation networks, managerial and social issues through various policies for the improvement of irrigation networks are considered. The results showed that with the current trend continues, performance of Qazvin irrigation network will be worse in the future and will be declined about 10% by the year 1399. Various policies such as physical and managerial improvement or increasing farmers participation has different impacts of performance improvement. Physical and managerial policies have improved the performance about 5% and 3% by the year 1399. Farmers participation showed highest impact on performance improvement which is about 14% by the year 1399.

Cooperation system is one of the most modern production systems in agriculture and natural resources sectors. Recent threats and challenges in natural resources management are main reasons for considering integration of cooperation in natural resources management. Furthermore, due to the vast area of rangelands the active participation of local people is necessary in conservation and renovation of rangelands. Experiences indicated that cooperation system as a popular system could help country rangeland trustees to conserve and renovate ranges. This study examined the performance of range management cooperatives in conservation and renovation of Golestan province’s ranges. Survey research was used via filling 386 questionnaires from some ordinary or Board of Directors members in 28 cooperatives. Results showed that performance of cooperatives can be evaluated as medium quality. Results also showed that respondents evaluated performance of range management cooperatives in conservation and renovation of rangelands better and more proper than its other activities such as employment, water and forage supply for livestock. Altogether members of board of director scored the performance of cooperatives more than ordinary members. Based on the findings of this research more activities of range management cooperatives is suggested to provide its members with banking facilities, supplying proper water and trough for livestock in rangelands and precipitation storage activities.