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0UO'K 662.997: 664.047.373:621 DEVELOPMENT OF SIMPLIFIED DESIGNS OF INFRARED SOLAR DRYERS
R.Rakhimov, D.Mukhtorov*
Keywords: infrared, pulse, truncated pyramid, composite film, conventional film, mass, time.
Infrared dryers usually mean drying devices consisting of electric lamps. In particular, a schematic diagram of an infrared laboratory dryer [1. 2-p.] was proposed by Professor Mehdi Khojaspur Scientific School.
The advantages of infrared radiation include high heat transfer coefficients, short drying time and easy control of the temperature of the material.
Researchers of our republic B.M. In the research conducted by Jumaev [2. 3-p.], a mathematical model of infrared-convective drying, optimal parameters for dried raw materials, preliminary processing parameters, a method of optimizing the drying process of fruits, a drying method based on the dependence of humidity and temperature in order to save energy and reduce the duration of the process were developed. developed.
Based on the analysis of the literature, development of a new generation of solar dryers is one of the urgent tasks of today. To fulfill this task, special polyethylene ceramic composite for drying was created at Jizzaxplasmassa JSC production enterprise. Functional ceramics are based on the ability to store the energy of light radiation not as photons (as in lasers), but as phonons as vibrations of the crystal lattice [3. 2-p., 4. 5-p., 5. 3-p.].
Experiment method. Methods of analysis and synthesis of research results, measurement, analytical calculation and comparison of analogs were used.
Theoretical part. To increase the efficiency of drying, it is necessary to affect the slowest stages of the process. In this case, the energy penetrates into the inner layers and the solvent diffuses from the deep layers to the surface, and proposed the following scheme of the process [6. 5-p.].
If one operates with high-density pulses in a given spectral range, one would expect the penetration depth Di in the first approximation to be proportional to the pulse density. Speaking about the spectral range, it should be noted that working in the region of maximum absorption of water or products causes all energy to be pushed by the small thickness of the surface layer.
For this purpose, a polyethylene-ceramic composition was developed on the basis of polyethylene with 0.1-1% ultra-fine functional ceramic powder, produced in cooperation with Jizzakhplastmassa joint-stock company.
*Rustam Rakhimov - Institute of Materials Science of the SPA "Physics-Sun" of the Academy of Science of Uzbekistan, Dilmurod Mukhtorov - Fergana Polytechnical Institute.
Functional polyethylene ceramic composite is capable of generating IR pulses in a certain spectral range [7. 4-p.].
As a result, the thickness of the three-layer composite film was 100 p,m, and the density was 990±10 kg/m3.
Practical part. Based on the material proposed above, the following construction of the infrared solar dryer was developed.
In the radiant solar dryer, the energy supply
device Fig- 3- final Stage of obtaining a composite film
is based on the transparent coating 7 for effective exposure to solar radiation. The drying chamber is in the form of a geometric cut pyramid, which improves free convection of air. The structure of drying chamber 1 is simple and high efficiency. In the chamber, the use of solar radiation is effectively organized, and during the drying process, heat is distributed on each shelf 5 and the product is protected from overheating. The free convection Fig. 4. structure of soiar dryer. method was used to remove the steam released from
l-corps; 2-basa; 3-piUa; 4-shetf handle; 5-shelf; 6-tvheel; . . <^111 n ■ 1 1 1 /-
7-coittpositefilm; 8-air iniet; io-door; ii-door handle. the product out of the chamber. Special wheels 6 are installed on the device to easily move the solar drying device from its place, which provides additional convenience in moving the device to any point of the drying facility[8. 3-p.].
The proposed combined solar dryer works as follows: One of the fruits, vegetables and grain products grown in agriculture is placed on the product rack 5 of the drying chamber and the door of the drying chamber 10 is closed. Solar radiation receives energy in the entire spectrum of radiation through the transparent coating 7 and is converted into pulsed infrared radiation in the spectrum corresponding to a wavelength of 6-8 p,m, and affects the product placed on the shelves. The goal of changing to this wavelength of radiation is the better binding of water combined with organic matter in this particular range. As a result, the water in the product is suffocated in the impact of the pulse and is expelled from the product. This structure of the drying chamber effectively serves to rapidly move the vapor stream upward through 2 and is vented to the atmosphere.
In an experimental study, solar dryers based on truncated pyramid shaped polyethylene ceramic composite and conventional film were obtained[9. 2-p.].
Experience. Based on the requirements of comparison of the obtained results, it was ensured that the conditions of conducting experiments in polyethylene ceramic composite solar dryers and traditional film solar dryers, i.e., the geometric parameters of the devices were the same and the time of conducting experiments were parallel.
In order to critically study the capabilities of polyethylene ceramic composite sun dryers, an analysis of the results of grape drying was first conducted. The black raisin variety of grapes was taken as a sample [10. 2-p.].
The process of grape drying is divided into three stages, this article presents the third stage of drying, which is the process until the final safe moisture content.
30 28
composite traditional
а)
25 24
01 ¿J
Ol С
3
22 21 20
- composite
- traditional
b)
15
16
time, dav
24
25
time, day
26
Fig.1. Dynamics of grape drying. a-the result of the first three days in the third stage; b-three-day result at the final stage.
At the next stage of the experiment, cherries were selected from fruits ripening in May under the conditions of Uzbekistan. 900 g on the upper shelf, 1150 g on the middle shelf and 1400 g on the lower shelf are placed in the drying chamber. Taking into account that the initial water content of cherries is 80%, the mass of the final dried product was dried to 23% of the mass of the product to be dried. the final safe humidity of 19% is verified to meet the requirements of GOST 32896-2014. The building dynamics of cherries was studied depending on the cumulative solar radiation during the day.
94 92 90
SS 86 84 82 80 78
composite traditional
а)
28
26
24
22
composite traditional
b)
,14 7,34 1,67
Total solar radiation kW day/m2
6,76 7,93 8,09
Total solar radiation kW day/m2
Figure 2 below shows the comparative results of cherry drying. Fig.2. Dynamics of cherry drying.
a-three-day result in the initial stage; b-three-day result at the final stage.
Discussion. From the above drying results, it can be said that the polyethylene ceramic composite solar dryer for grape drying is significantly more efficient than the conventional polyethylene solar dryer. In particular, in the graph presented in Fig. 1a, the difference between the masses on the 16th day of drying has changed by 6%. These results showed a 4% shrinkage by day 18, of course shrinkage is a natural process in the final stage of drying.
When evaluating the drying capability of solar dryers, using the graph in figure 2b above, the drying capability of grapes to the final minimum moisture content is revealed. It can be said that it is possible to dry up to 21% of the total mass of grapes in a composite film drying chamber, and this value is higher than 23% in conventional film solar dryers.
The dynamics of drying of cherries from fruits was considered. In this case, the process was studied in relation to total solar radiation. In particular, it can be observed that the composite
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film solar dryer works partially efficiently when the total solar radiation changes from 4.14 kWday/m2 to 7.34 kWday/m2. When total solar radiation decreased from 7.34 kWday/m2 to 1.67 kWday/m2, the difference in mass change for this period increased significantly. Therefore, the composite film effectively dries cherries from fruits with minimal energy consumption compared to conventional film. And when the amount of radiation increases, the drying process slows down. In order to confirm this analysis, the results of three days were obtained from the final threshold with the highest amount of total solar radiation during the experimental period. The results showed that as the amount of solar energy increased, the traditional polythene film solar dryer was considered the most efficient device in terms of drying rate of cherries (excluding quality efficiency). This led us to the possible causes of the cherry drying anomaly. The first reason is that due to the low permeability of the skin to water vapor, the pulsed radiation that penetrates deep into the cherry fruit can concentrate sugar and some other substances. It is known that in this case, more energy is required to break water molecules from such solutions. There is a high probability that this can affect the speed of the drying process.
The part of the solar spectrum that is not absorbed by water molecules is the visible and ultraviolet rays. In this spectrum, the product is heated from the surface, therefore, if the material to be dried is highly sensitive to heat, the construction process is accelerated. Another consideration here is that when the surface of the product heats up, the density of the shell is relatively reduced and it becomes easier to release steam. Therefore, traditional film transmits well the solar spectrum that we see and partially the ultraviolet spectrum. As a result, the above procedure is followed for cherries. And in the composite film, visible and ultraviolet rays are converted into infrared spectrum. Therefore, in the initial phase, the pigment absorbs light in the required spectrum and leads to the general browning of the fruit. This speeds up the drying process.
Based on the above experimental results and discussions, the following conclusions were
drawn.
Conclusion. Adding common ceramic granules to transparent polyethylene and reducing its light transmittance leads to a decrease in drying efficiency. But this process was not triggered in the experiment. That is, it was determined that the efficiency of grape drying in the solar dryer based on functional ceramic composite is 44% higher than the efficiency of the traditional film solar dryer. A new generation of solar dryers, which can be effectively dried with minimal solar energy consumption, solar dryers with polyethylene ceramic composite based on pulse tunnel effect, was proposed and developed.
Reference:
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2. B.M. Jumaev, Acceleration of the drying process of fruit and vegetable products using an infrared convective device//Doctor of Philosophy (PhD) thesis on technical sciences. Tashkent - 2020, pp. 1-120.
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5. Рахимов, Рустам Хакимович, et al. "Возможности полиэтилен-керамического композита в сравнении с полиэтиленовой пленкой в реальных условиях эксплуатации." Computational nanotechnology 9.2 (2022): 67-72.
6. Rakhimov, Rustam, Akmal Kuchkarov, and Dilmurod Mukhtorov. "Determination of the ability of a solar dryer based on a polyethylene ceramic composite to dry vegetables of various thicknesses." BIO Web of Conferences. Vol. 84. EDP Sciences, 2024.
7. Rakhimov, Rustam Kh, and Dilmurod N. Mukhtorov. "Solar Drying of Fruit and Vegetables Using Polyethylene-Ceramic Composite." Computational nanotechnology 10.4 (2023): 103-109.
8. Мухторов, Дилмурод Нумонжонович. "Определение изменения массы продукта в композитных пленочных солнечных сушилках в зависимости от солнечной радиации." Научный форум: технические и физико-математические науки. 2023.
9. Рахимов, Рустам Хакимович, et al. "Разработка метода получения керамических нанокомпозитов с использованием элементов золь-гель-технологии для создания вкраплений аморфных фаз с составом, аналогичным целевой кристаллической керамической матрице." Computational nanotechnology 9.3 (2022): 60-67.
10. Р.Х.Рахимов, and Д.Н.Мухторов. "Оддий ва керамик композитли плёнкадан фойдаланиб куёшли куритгичларни текшириш. Ёш олимлар ахборотномаси: 6.
INFRAQIZIL QUYOSH QURITGICHLARINING SODDALASHTIRILGAN KONSTRUKSIYALARINIISHLAB CHIQISH
Ushbu maqolada infraqizil quyosh quritgichlarining yangi avlodi ishlab chiqilgan. Ya'ni ishlab chiqish va texnik xizmat ko'rsatish harajatlari hisobga olgan holda, quyosh energiyasini konvertatsiyalash xususiyatiga ega bo'lgan polietilen-keramika kompozitiga asoslangan kesik piramida shaklidagi quyosh quritgichining konstruksiyasi taklif etilgan. Shuningdek, polietilen keramika kompozitli va an'anaviy plyonkali quyosh quritgichlarining imkoniyatlari tanqidiy o'rganilgan, jumladan quyosh quritgichlarida uzum va gilosni quritish dinamikasi vaqt va quyosh radiatsiyasining o'zgarishini hisobga olgan holda massaning o'zgarishi ko'rib chiqilgan.
РАЗРАБОТКА УПРОЩЕННЫХ КОНСТРУКЦИЙ ИНФРАКРАСНЫХ СОЛНЕЧНЫХ СУШИЛОК
В этой статье было разработано новое поколение инфракрасных солнечных сушилок. То есть с учетом затрат на разработку и обслуживание предлагается конструкция солнечной сушилки усеченной пирамиды на основе полиэтилен-керамического композита со свойствами преобразования солнечной энергии. Также были критически изучены возможности полиэтиленкерамических композитных и традиционных пленочных солнечных сушилок, в том числе динамика сушки винограда и вишни в солнечных сушилках с учетом изменений массы и времени и солнечной радиации.
DEVELOPMENT OF SIMPLIFIED DESIGNS OF INFRARED SOLAR DRYERS
In this article, a new generation of infrared solar dryers has been developed. That is, taking into account the costs ofdevelopment and maintenance, a design of a truncatedpyramid-shaped solar dryer based on a polyethylene-ceramic composite with solar energy conversion properties is proposed. Also, the capabilities ofpolyethylene ceramic composite and traditional film solar dryers were critically studied, including the dynamics of grape and cherry drying in solar dryers, taking into account changes in mass and time and solar radiation.
