CC BY
0SUBSTANTIATION OF SCHEMES AND PARAMETERS OF AN ELECTRIC TRACTOR FOR SMALL FARMS IN THE COTTON-
GROWING ZONE
1Matyakubov Sh.K., 2Abdazimov A.D.
1,2Tashkent State Technical University https://doi.org/10.5281/zenodo.13120796
Abstract. The article discusses the substantiation of the schemes and parameters of an electric tractor intendedfor use in small farms of the cotton-growing zone. Based on the analysis of the purpose function, agrotechnical requirements and technical characteristics, rational layout schemes of an electric tractor with recharging of traction batteries from solar panels, taking into account the specifics of field work in cotton-growing conditions, are proposed with technical characteristics that ensure high efficiency and economy of electric tractor operation. Particular attention is paid to energy consumption, autonomy and environmental friendliness of equipment. The results of the study can serve as a basis for further development and implementation of electric tractors in farms, which significantly reduce operating costs, and especially the negative impact on the environment.
Keywords: electric tractor, cotton growing, small farms, energy consumption, tractor class, environmental friendliness, layout diagrams, recharging, batteries, solar panels.
1. Introduction
Modern agriculture is faced with the need to increase productivity and efficiency in the use of machinery, while striving to minimize the negative impact on the environment. This task is especially relevant in the cotton-growing zone, where the intensive use of agricultural machinery has a significant impact on the ecosystem. In this context, electric tractors represent a promising direction that can meet both the economic and environmental requirements of modern agricultural enterprises[1].
Electric tractors equipped with solar recharging systems offer a number of advantages over traditional diesel and gasoline counterparts. They eliminate emissions of carbon dioxide and other harmful substances and reduce operating costs due to the possibility of using renewable energy sources. The electric drive of high-power tractors requires more powerful traction batteries (TAB) or diesel generators, which leads to a significant increase in the weight and energy capacity of the tractor and the unit as a whole, and there may be problems with the specific pressure of the propellers on the soil[2].
Therefore, agricultural electric tractors of small and medium power with a tractive force on the hook of 0.6 ... 0.9 kN, which are economically beneficial for small farms with small contours of agricultural land, and especially in regions with large sunny days, in particular in cotton-growing zones, where it is possible to use solar energy to recharge TAB by installing solar panels on the tractor. These tractors in a unit with 4-row (with a working width of up to 4 m.) machines and tools can be used to carry out technological operations with small energy consumption, such as sowing, cultivation (cultivation, application of mineral fertilizers, chemical protection, sprinkling, etc.) of cotton and other crops, including in orchards and vineyards, harvesting fodder crops - mowing grasses, alfalfa, etc.
Currently, there are more than 160 thousand farms in the agro-industrial complex of the Republic of Uzbekistan, which have irrigated and rainfed land areas within 40... 500 hectares, of which more than 75 thousand are multidisciplinary, the number of which has increased by 45 percent over the past two years[3,8]. The peculiarity of farms in Uzbekistan, as mentioned above, is multi-profile, the size of plots - small-contour - fields with an area of up to 6 hectares - make up about 40% of the total land, and fields with an area of up to 10 hectares about 60% (Table 1) [ 4].
Table. 1. Size of cultivated agricultural land by regions of the Republic of Uzbekistan
Area Stake. contours Environments. Outline size. Rasp. Pin. along ha
0-0,5 11,3 3,1-6 6,110
Tashkent 3160 13,1 - 13,8 14,7 17,4
Syr Darya 1735 25,8 - 2,7 6,6 9,9
Fergana 3988 6,7 5,3 22,2 19,8 19,9
Namangan 781 10,5 - 10 22,8 25,5
Andijan 1497 8,0 3,5 24,3 24,5 16,6
Samarkand 835 13,5 - 10,7 16,1 21,6
Bukhara 409 5,0 - 36,9 32 12
Kashkadarya 1835 16,4 - 7,4 10,4 17
Surkhandarya 611 8,2 1,5 28,6 27,7 9,7
Khorezm 1101 8,6 - 18,1 26,2 22,9
Total 17540 12,9 1,6 15,7 17,1 17,5
2. Methods and materials
To substantiate the schemes and parameters of an electric tractor of class 0.9 with recharging from solar panels, designed for the cotton-growing zone in the conditions of Uzbekistan, a set of calculations and analyzes was carried out. First of all, agrotechnical requirements and operating conditions in the region, which is characterized by a hot climate and a significant length of the sunny day, were taken into account. These factors make the use of solar panels particularly efficient. Cotton cultivation in Uzbekistan requires high productivity and reliability of equipment in conditions of high temperatures and dusty operating conditions.
The average solar insolation in Uzbekistan is about 5.5 kWh/m2 per day [5]. For the calculations, the area of solar panels on an electric tractor of 10 m2 was used, which gives a daily energy generation of 55 kWh. The average power of an electric tractor of class 0.9 for field work is 30 kW with a working day of 8 hours. The daily energy consumption is therefore 240 kWh, which means that a battery with a capacity of at least 240 kWh is required to ensure autonomous operation. Taking into account the efficiency of batteries and charging and unloading control systems, the energy reserve should be 20% above the design capacity, which increases the required battery capacity to 288 kWh [5,9].
An economic analysis showed that the cost of installing solar panels with an area of 10 m2 is $2000, and the cost of a 288 kWh battery is about $50000. With the average cost of diesel fuel in Uzbekistan being $0.7 per liter and the consumption of a diesel tractor of 20 liters per hour, the daily fuel costs are $112, which on an annualized basis (with an average of 200 working days)
gives $22,400. Thus, switching to a class 0.9 electric tractor with solar panels allows you to significantly save on fuel.
Environmental analysis has shown that the use of an electric tractor with solar recharging can reduce carbon dioxide emissions by 48 tons per year, based on the calculation that 1 liter of diesel fuel emits about 2.68 kg of CO during combustion [6,11].
As materials for solar photovoltaic generators, experts recommend using high-efficiency monocrystalline solar panels with an efficiency of 20% [7], lithium-ion batteries with high energy density and long service life, as well as AC motors with high efficiency and reliability for operation in harsh conditions [12].
The use of these methods and materials makes it possible to justify the schemes and parameters of the 0.9 class electric tractor for cotton growing in Uzbekistan, ensuring the efficient and environmentally friendly operation of agricultural machinery.
The following calculations were used to determine the traction on the hook of an electric tractor of class 0.9. The average power of the tractor is 30 kW, which is equivalent to 40.23 horsepower. The total average efficiency of the electric motor and transmission can be assumed to be 0.85. The maximum traction force on the hook is calculated according to the formula:
F=px^/v
where F is the traction force on the hook (N), P is the power of the tractor (W), n is the efficiency, v is the working speed (m/s).
At an average working speed of 2 m/s, the traction force on the hook will be:
F=30000 (W)x0.85/2 (m/s)=12750 N.
These calculations made it possible to choose a conceptual general view of the electric tractor cl.0.9 for small farms in the cotton-growing zone (Fig.1), to compile and carry out a comparative analysis of the layout diagrams of the electric tractor with 2x2 and 4x4 wheel schemes (Fig. 2... 5).
Электродвигатель (мотор-колесо)
Fig.1. Conceptual general view of the electric tractor cl.0.9 for small farms in the cotton-
growing zone
3. Results and discussions
In the figure 2... 5, there are given four layout diagrams of electric tractors of class 0.9 for the cotton-growing zone of Uzbekistan. The designation of composite blocks and assemblies in all
diagrams is the same as in Figure 2. Each scheme takes into account different approaches to the placement of traction motors (TED) and TAB units that affect the characteristics and efficiency indicators of the tractor.
Fig. 2. Layout diagram with the location of the TED directly next to the main gear: 1 - TAB unit; 2 - control unit; 3 - drive control unit; 4-TED; 5-cardan transmission; 6 - main gear;
7-Solar Panel
The layout of an electric tractor with the location of the TED directly near the main gear (see Fig. 2) has advantages compared to those in the form of simplicity of design and unification of basic diesel tractors of a similar class, which makes it possible to use their components and equipment and thereby reduce the cost of developing the frame, transmission and chassis, as well as improve stability due to the uniform distribution of weight over the wheels. The disadvantages of this arrangement are limited space for additional components and the need for additional elements to transmit power.
The layout scheme with the location of the TED near the main gear and with separated TAB blocks (see Fig. 3) allows you to symmetrically place the batteries to evenly distribute the weight of the tractor over the wheels, which improves the controllability and stability of its movement, but at the same time complicates the design, increases production and maintenance costs, and also requires additional fasteners and connecting elements.
Fig.3. Layout diagram with the location of the TED near the main gear and with separated
TAB blocks
The layout with the placement of the TED directly on the drive wheels (hub motor) (see Fig. 4) on a tractor with a 4x2 wheel arrangement has a simple design and a reduction in the number of mechanical components, which reduces the likelihood of breakdowns and maintenance costs, but the uneven distribution of the weight of the tractor over the wheels can worsen the controllability and stability of movement and limit the possibilities for modernization.
The layout of an electric tractor with a 4x4 wheel arrangement with the installation of a TED on all four wheels (see Fig. 5) assumes high cross-country ability and stability, a more uniform distribution of weight over the wheels and improved traction characteristics, but the complexity of the design, the high cost of production and maintenance, as well as the need for complex control systems make it less attractive.
Fig.4. Layout scheme with the location of the TED on the drive wheels (hub motor) of a
tractor with a 4x2 wheel arrangement
Fig.5. Layout diagram with installation
TED on all wheels on a tractor with a 4x4 wheel arrangement
Taking into account all the pros and cons of the considered layout diagrams, the scheme of an electric tractor with the location of the TED directly in front of the main gear has the advantages listed above, the main of which is the simplicity of design and the unification of components and systems of diesel tractors of a similar class. These factors can significantly reduce the time and cost of developing and introducing a new tractor into production. In addition, the uniform distribution of weight in this scheme improves the traction characteristics, stability and maneuverability of the tractor, which is especially important for working in small contour fields. The disadvantages of this layout in the form of limited space for additional components can be eliminated in the future in the process of modernization.
Thus, the selected layout scheme (see Fig.2) provides an optimal combination of environmental friendliness, economy, simplicity of design and productivity. It allows to reduce operating costs, increase the reliability and durability of the tractor, as well as simplify its maintenance and repair. These factors make it the most rational and profitable solution for implementation on small farms in Uzbekistan.
Traction calculations showed that the 0.9 class electric tractor is capable of developing a traction force on the hook of up to 12750 N, which provides sufficient power to perform the main technological operations for the cultivation of cotton and other crops.
The introduction of electric tractors with recharging from solar panels also requires the solution of a number of technical and infrastructural issues, such as the provision of sufficient infrastructure for charging the TAB, maintenance of components and assemblies of the electric tractor and the electric tractor itself as a whole, taking into account seasonal fluctuations in insolation.
4. Conclusion
The analysis of the four proposed layout schemes showed that each of them has its own features and advantages, which make it possible to choose the optimal design depending on the operating conditions. The results of the analysis confirmed the economic and environmental benefits of using an electric tractor with solar panels, reducing operating costs and carbon dioxide emissions taking into account infrastructure and seasonal fluctuations in insolation.
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