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7SCIENTIFIC PROGRESS VOLUME 4 I ISSUE 1 I 2023 _ISSN: 2181-1601
Scientific Journal Impact Factor (SJIF 2022=5.016) Passport: http://sjifactor.com/passport.php?id=22257
ISSIQLIK ALMASHINISHDA ISSIQLIK AGENTI TEZLIGI VA MAHALLIY QARSHILIK KOEFFITSIENTLARINI TAJRIBAVIY TADQIQ ETISH
Gulmira Ikromalievna Madaminova
Farg'ona politexnika instituti gmadaminova_87@mail.ru
ANNOTATSIYA
Maqolada mineral o'g'itlarni qurituvchi barabanli quritgichda issiqlik almashinish jarayonidagi issiqlik agenti tezligi va mahalliy qarshilik koeffitsientlari tajribaviy tadqiq qilingan va issiqlik almashinishning yuqori intensivligini belgilovchi parametrlarini aniqlash maqsadida eksperimental tadqiqotlar dasturi amalga oshirilgan.[1]
Kalit so'zlar: Issiqlik almashinish, barabanli quritgich, quritish, U simon nasadka, kalorifer, kirish tezligi, chiqish tezligi, qarshilik koeffitsienti.
KIRISH
Jahon kimyo sanoatida mineral o'g'itlarni yuqori samarali turlarini ishlab chiqarish, sifatli va energiyatejamkor texnologiya asosida quritishni ta'minlash bo'yicha ilmiy izlanishlar olib borilmoqda.[15] Bu borada quritish apparatlari va rejimlarini tahlil qilish, muammolarni aniqlash; mahsulotning granulometrik tarkibini optimallashtirish orqali mahsulotni yirik qismini qayta quritishni bartaraf etish; quritish apparatining ichki nasadkalari konstruksiyasi va joylashtirish usulini mahsulotning harakat yo'nalishi va issiqlik aerodinamikasiga ta'sirini eksperimental usulda tadqiq etishga alohida e'tibor qaratilmoqda.[18]
Shu bilan birga hozirda oziq-ovqat, kimyo, paxtani qayta ishlash va turdosh sanoatlar uchun mo'ljallangan ixcham, arzon va eksportga mo'ljallangan mineral o'g'itlarni quritish texnologiyalari va mashinalarini takomillashtirish bo'yicha ilmiy-tadqiqot ishlari olib borilmoqda. [22]
ADABIYOTLAR TAHLILI VA METODOLOGIYA
O'tkazilgan nazariy tadqiqotlar natijalarini tekshirish hamda barbanli quritgichga ikki qismli U simon nasadkani qo'llab kam energiya sarfida issiqlik almashinishning yuqori intensivligini belgilovchi parametrlarini aniqlash maqsadida eksperimental tadqiqotlar dasturiga quyidagi tadbirlar kiritildi:
-eksperimental tadqiqotlarni o'tkazish uchun laboratoriya qurilmasini ishlab chiqish va yasash;
-nasadka turlariga bog'liq xolda material haroratiga ta'sirini tadqiq etish; - barabanli quritgichda issiqlik agenti tezligi va mahalliy qarshilik koeffitsientlarini tajribaviy tadqiq etish;
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- ikki qismli U simon nasadka bilan jihozlangan barabaninng gidravlik qarshiligini tadqiq etish;
-issiqlik agenti tezligining material haroratiga ta'sirini tadqiq etish;
-material xarorati o'zgarishining baraban aylanishlar soniga bog'liqligini tadqiq
etish;
-material namligi o'zgarishining baraban aylanishlar soniga va ish unumdorligiga bog'liqligini tadqiq etish.[25] NATIJALAR
Tadqiqotlarni o'tkazish uchun o'zgaruvchi omillarning quyidagi chegaralari, nasadkaning materialni to'kish qismining qiyaligi R=15;30 va 45o, issiqlik almashinish zonalari soni 5 ta, bitta qatordagi nasadkalar soni 10 ta (nasadkalar zonalar bo'yicha shaxmat qator tartibida joylashtirilgan), kaloriferdan chiqayotgan issiqlik agentining (havo) tezligi u= 1,4^14,2 m/s, qurilmaning ish unumdorligi Qunm =0,18^0,46 kg/s, quritgich barabanining tekislikka nisbatan qiyalik burchagi a=2,24gradus (texnologik reglament bo'yicha),[7] Quritgich barabanining aylanishlar chastotasi n=4 ayl/min belgilandi.[9],[6]
Yuqoridagi o'zgaruvchan omillar ketma-ketlikda o'zgartirib borildi va isiqlik agentining barabanga kirishdagi va chiqishdagi tezligi qiymatlari hamda sarf tajribaviy aniqlandi. [24]Har bir o'tkazilgan tajribalar 5 marotabadan takrorlangan holda olib borildi va o'rta arifmetik qiymatlar tanlandi. Tajriba natijalari 1.1; 1.2 va 1.3-jadvallarda keltirilgan.[27]
1-jadval
Nasadkaning materialni to'kish qismidagi qiyaligi R=15o bo'lganda
№ Kalorifer shiberi gradusi Kirish tezligi Chiqish tezligi Qarshilik koeffitsienti
Mahsulotni to'ldirish koeffitsienti 0,18 kg/s
1 90o 14,2 4.23 3.35
2 75o 10.55 3.16 3.33
3 60o 7.15 2.12 3.37
4 45o 5.62 1.72 3.29
5 30o 2.60 0.77 3.35
6 15o 1.40 0.41 3.36
O'rtacha 3.34
Mahsulotni to'ldirish koeffitsienti 0,32 kg/s
1 90o 14,2 4.04 3.51
2 75o 10.55 3.02 3.49
3 60o 7.15 2.01 3.56
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4 45o 5.62 1.59 3.52
5 30o 2.60 0.73 3.54
6 15o 1.40 0.39 3.53
O'rtacha 3.52
Mahsulotni to'ldirish koeffitsienti 0,46 kg/s
1 90o 14,2 3.78) 3.75
2 75o 10.55 2.83 3.72
3 60o 7.15 1.91 3.74
4 45o 5.62 1.51 3.75
5 30o 2.60 0.69 3.73
6 15o 1.40 0.37 3.76
O'rtacha 3.74
2-jadval
Nasadkaning materialni to'kish qismidagi qiyaligi R=30o bo'lganda
№ Kalorifer shiberi gradusi Kirish tezligi Chiqish tezligi Qarshilik koeffitsienti
Mahsulotni to'ldirish koeffitsienti 0,18 kg/s
1 90o 14,2 3.03 4.68
2 75o 10.55 2.26 4.66
3 60o 7.15 1.52 4.70
4 45o 5.62 1.21 4.62
5 30o 2.60 0.55 4.68
6 15o 1.40 0.30 4.67
O'rtacha 4.66
Mahsulotni to'ldirish koeffitsienti 0,32 kg/s
1 90o 14,2 2.93 4.84
2 75o 10.55 2.18 4.82
3 60o 7.15 1.46 4.89
4 45o 5.62 1.15 4.85
5 30o 2.60 0.53 4.87
6 15o 1.40 0.28 4.86
O'rtacha 4.81
Mahsulotni to'ldirish koeffitsienti 0,46 kg/s
1 90o 14,2 2.79 5.08
2 75o 10.55 2.08 5.05
3 60o 7.15 1.41 5.07
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4 45o 5.62 1.10 5.09
5 30o 2.60 0.51 5.06
6 15o 1.40 0.27 5.08
O'rtacha 5.07
3-jadval
Nasadkaning materialni to'kish qismidagi qiyaligi R=45o bo'lganda
№ Kalorifer shiberi gradusi Kirish tezligi Chiqish tezligi Qarshilik koeffitsienti
Ma] isulotni to'ldirish koeffitsienti 0,18 kg/s
1 90o 14,2 2.39 5.92
2 75o 10.55 1.78 5.90
3 60o 7.15 1.20 5.94
4 45o 5.62 0.95 5.86
5 30o 2.60 0.43 5.92
6 15o 1.40 0.23 5.93
O'rtacha 5.91
Ma] isulotni to'ldirish koeffitsienti 0,32 kg/s
1 90o 14,2 2.33 6.08
2 75o 10.55 1.74 6.06
3 60o 7.15 1.16 6.13
4 45o 5.62 0.92 6.09
5 30o 2.60 0.42 6.11
6 15o 1.40 0.22 6.10
O'rtacha 6.09
Ma] hsulotni to'ldirish koeffitsienti 0,46 kg/s
1 90o 14,2 2.24 6.32
2 75o 10.55 1.67 6.29
3 60o 7.15 1.13 6.31
4 45o 5.62 0.88 6.32
5 30o 2.60 0.41 6.30
6 15o 1.40 0.22 6.33
O'rtacha 6.31
O'tkazilgan tajribalarning to'g'riligini tekshirish maqsadida qarshilik koeffitsientining ish umdorligiga bog'liqlik grafigi qurildi (2-rasm).[8]
SCIENTIFIC PROGRESS
VOLUME 4 I ISSUE 1 I 2023 ISSN: 2181-1601
Scientific Journal Impact Factor (SJIF 2022=5.016) Passport: http://sjifactor.com/passport.php?id=222ff7
<f
0,1
0,2
1 _O- --A
2
3
/ _■
0,3
0,4
0,5
0.\<y, kt/C
1-ish unumdorligi 0,18 kg/s; 2-ish unumdorligi 0,32 kg/s; 3-ish unumdorligi 0,46 kg/s; 2-rasm. Qarshilik koeffitsientining ish unumdorligiga bog'liqligi.
MUHOKAMA
O'tkazilgan tajribalarga eng kichik kvadratlar usulini qo'llab, quyidagi regression tenglamalar olindi va grafik bog'lanishlarning xar bir nuqtasi uchun alohida alohida yechib ko'rildi va korrellyatsiya (R) xatoliklari belgilandi.[3],[14] Olingan qiymatlardan ko'rinadiki, tajriba xatoligi 5% dan oshmadi.[29]
1-ish unumdorligi 0,18 kg/s;
y = 1,4286x + 5,6462 (R2 = 0,9967) (1)
2-ish unumdorligi 0,32 kg/s;
y = 1,4643x + 4,3781 (R2 = 0,9766) (2)
3-ish unumdorligi 0,46 kg/s;
y = 1,4286x + 3,0762 (R2 = 0,9967) (3)
Berilgan grafikdan ko'rinadiki, barabanga mahsulotni to'ldirish koeffitsientining ortib borishi apparatdagi qarshilik koeffitsientining ko'tarilishiga olib kelar ekan[22]. Bundan tashqari ikki qismli U simon nasadkaning mahsulotni to'kish qiyalik burchagining 15^45o ko'tarilishi ham barabanning ko'ndalang kesim yuzasida material pardasi koeffitsientining ortishiga va bu esa o'z navbatida qarshilik koeffitsientining yanada ko'tarilishiga sabab bo'ladi.[15],[27]
XULOSA
Demak, apparatdagi gidravlik qarshiliklarni aniqlashda ushbu omillarni e'tiborga olish, issiqlik agentidan samarali foydalanishni belgilovchi parametr sifatida hisoblanishi mumkin.[31],[19]
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ADABIYOTLAR RO'YXATI
1.Rasuljon, T., Sulaymanov, A., Madaminova, G., & Agzamov, S. U. (2022). GRINDING OF MATERIALS: MAIN CHARACTERISTICS. International Journal of Advance Scientific Research, 2(11), 25-34.
2.Alizafarov, B., Madaminova, G., & Abdulazizov, A. (2022). Based on acceptable parameters of cleaning efficiency of a rotor-filter device equipped with a surface contact element. Journal of Integrated Education and Research, 1(2), 36-48.
3.Gulmiraxon, M., Muhammadqodir, Y., Ravshanbek, M., & Nikita, L. (2022). Analysis of the dispersion composition of dust particles. Yosh Tadqiqotchi Jurnali, 1(6), 70-79.
4.Ikromaliyevnab, M. G. (2022). NEW DESIGN OF WET METHOD WET CLEANING BLADE-DRUM DEVICE. American Journal Of Applied Science And Technology, 2(05), 106-113.
5.Мадаминова, Г. И. (2022). ЭКСПЕРИМЕНТАЛЬНЫЕ ИССЛЕДОВАНИЯ ПО ОПРЕДЕЛЕНИЮ КОЭФФИЦИЕНТОВ СОПРОТИВЛЕНИЯ БАРАБАННОГО АППАРАТА МОКРОЙ ПЫЛЕОЧИСТКИ. Universum: технические науки, (10-4 (103)), 46-52.
6.Мадаминова, Г. И. (2022). Исследования по определению контактных поверхностей пыли. Universum: технические науки, (5-7 (98)), 63-67.
7.Karimov, I., Tojiyev, R., Madaminova, G., Ibroximov, Q., & Xamdamov, O. T. (2021). WET METHOD DUST REMOVER BLACK DRUM DEVICE. BARQARORLIK VA YETAKCHI TADQIQOTLAR ONLAYN ILMIY JURNALI, 1(5), 57-63.
8.Karimov, I., Tojiyev, R., Madaminova, G., Ibroximov, Q., & Xamdamov, O. T. (2021). HYDRODYNAMICS OF WET DUSH POWDER BLACK DRUM EQUIPMENT. BARQARORLIK VA YETAKCHI TADQIQOTLAR ONLAYN ILMIY JURNALI, 1(5), 49-56.
9.Isomidinov, A., Madaminova, G., Qodirov, D., & Ahmadaliyeva, M. (2021). Studying the Effect of Interior Scrubber Hydraulic Resistance on Cleaning Efficiency. International Journal of Innovative Analyses and Emerging Technology, 1(5), 87-93. 10.Isomidinov, A., Madaminova, G., & Zokirova, M. (2021). ANALYSIS OF MODERN INDUSTRIAL DUST GAS CLEANING DEVICES. Scientific progress, 2(8), 137-144.
11.Isomidinov, A., Madaminova, G., & Zokirova, M. (2021). RATIONALE OF APPROPRIATE PARAMETERS OF CLEANING EFFICIENCY OF ROTOR-FILTER DEVICE EQUIPPED WITH FACE CONTACT ELEMENT. Scientific progress, 2(8), 126-136.
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12.Домуладжанов, И. Х., & Мадаминова, Г. И. (2021). Вредные вещества после сухой очистки в циклонах и фильтрах. Universum: технические науки, (6-1 (87)), 5-10.
13.Мадаминова, Г. И., Тожиев, Р. Ж., & Каримов, И. Т. (2021). Барабанное устройство для мокрой очистки запыленного газа и воздуха. Universum: технические науки, (5-4 (86)), 45-49.
14. Gulmiraxon, M., Ismoiljon, X., Abduraxmon, S., Bekzod, A., & Muhammadbobur, X. (2022). CRUSHING AND APPETITE OF THE PROCESS EFFICIENCY INCREASE. Conferencea, 22-27.
15. Gulmiraxon, M., Abduraxmon, S., Ismoiljon, X., Bekzod, A., & Muhammadbobur, X. (2022). ROLLER GRATE WITH INCREASING COVERAGE GROUND SURVEY WORK CORNER. Conferencea, 17-22.
16. Abduraxmon, S., Gulmiraxon, M., Ismoiljon, X., Bekzod, A., & Muhammadbobur, X. (2022). THE KLINKER CEMENT IN THE PRODUCTION OF GAS FUEL FROM USE SPARINGLY. Conferencea, 23-28.
17. Abduraxmon, S., Gulmiraxon, M., Ismoiljon, X., Bekzod, A., & Muhammadbobur, X. (2022). THE KLINKER CEMENT IN THE PRODUCTION OF GAS FUEL FROM USE SPARINGLY. Conferencea, 23-28.
18. Abduraxmon, S., Gulmiraxon, M., Ismoiljon, X., Bekzod, A., & Muhammadbobur, X. (2022). CALCULATION OF THE ROTATION SPEED OF THE CLINKER CRUSHING MILL. Conferencea, 12-19.
19. Abduraxmon, S., Gulmiraxon, M., Ismoiljon, X., Bekzod, A., & Muhammadbobur, X. (2022). CALCULATION OF THE ROTATION SPEED OF THE CLINKER CRUSHING MILL. Conferencea, 12-19.
20. Abduraxmon, S., Gulmiraxon, M., Ismoiljon, X., Bekzod, A., & Muhammadbobur, X. (2022). ECOLOGICAL DRYING OF FINE MATERIALS. Conferencea, 4-11.
21. Ахунбаев, А. А., & Ражабова, Н. Р. (2021). Высушивание дисперсных материалов в аппарате с быстро вращающимся ротором. Universum: технические науки, (7-1 (88)), 49-52.
22. Ахунбаев, А., Ражабова, Н., & Сиддиков, М. (2021). Математическая модель сушки дисперсных материалов с учётом температуры материала. Збгрник наукових праць SCIENTIA.
23. Tojiyev, R., & Rajabova, N. (2021). EXPERIMENTAL STUDY OF THE SOIL CRUST DESTRUCTION MECHANISM. Scientific progress, 2(8), 153-163.
24. Rajabova, N. R., & Qodirov, A. B. (2022). Drying tonkodisperse materials in an unsuccessed rotary-druming machine. International Journal of Advance Scientific Research, 2(06), 35-39.
SCIENTIFIC PROGRESS VOLUME 4 I ISSUE 1 I 2023 _ISSN: 2181-1601
Scientific Journal Impact Factor (SJIF 2022=5.016) Passport: http://sjifactor.com/passport.php?id=222ff7
25. Jumaboevich, T. R., & Rakhmonalievna, R. N. (2022). INSTALLATION FOR DRYING MATERIALS IN A FLUIDIZED BED. Innovative Technologica: Methodical Research Journal, 3(11), 28-36.
26. Rasuljon, T., & Nargizaxon, R. (2022). IMPACT ON THE INTERNAL STRUCTURE OF MATERIALS TO DRYING PROCESS. Universum: технические науки, (10-6 (103)), 10-18.
27. Tojiyev, R., & Rajabova, N. (2022). IMPACT ON THE INTERNAL STRUCTURE OF MATERIALS TO DRYING PROCESS. Главный редактор: Ахметов Сайранбек Махсутович, д-р техн. наук; Заместитель главного редактора: Ахмеднабиев Расул Магомедович, канд. техн. наук; Члены редакционной коллегии, 10.
28. Akhunbaev, A. A., Rajabova, N. R., & Honkeldiev, M. (2022, November). DRYING OF CRYSTAL AND GRAIN MATERIALS IN A DRUM DRYER. In INTERNATIONAL CONFERENCE DEDICATED TO THE ROLE AND IMPORTANCE OF INNOVATIVE EDUCATION IN THE 21ST CENTURY (Vol. 1, No. 7, pp. 27-35).
29. Akhunbayev, A. A., & Rajabova, N. R. (2022). DRYING OF RAW MATERIALS OF CEMENT PRODUCTION IN THE DRUM DRYER. International Journal of Advance Scientific Research, 2(11), 50-59.
30 Akhunbaev, A. A., Rajabova, N. R., & Madaminova, G. I. (2022, November). DRYING OF SPRAYED DISPERSED MATERIALS. In INTERNATIONAL CONFERENCE DEDICATED TO THE ROLE AND IMPORTANCE OF INNOVATIVE EDUCATION IN THE 21ST CENTURY (Vol. 1, No. 7, pp. 184-191).
31. Ражабова, Н. Р., Агзамов, С. У., & Ёкубжонов, А. Т. (2022). ИЗВЛЕЧЕНИИ РЕДКИХ МЕТАЛЛОВ В БАРБОТАЖНОМ ЭКСТРАКТОРЕ. Eurasian Journal of Academic Research, 2(5), 893-895.
32. Тожиев, Р. Ж., Миршарипов, Р. Х., & Ражабова, Н. Р. (2022). Гидродинамические Режимы В Процессе Сушки Минеральных Удобрений. CENTRAL ASIAN JOURNAL OF THEORETICAL & APPLIED SCIENCES, 3(5), 352-357.
33. Ахунбaев, А., Ражабова, Н., & Вохидова, Н. (2021). Механизм движения дисперсного материала при сушке тонкодисперсных материалов. Збгрник наукових працъ SCIENTIA.
34. Tojiyev, R., Erkaboyev, X., Rajabova, N., & Odilov, D. (2021). MATHEMATICAL ANALYSIS APPLICATION OF THE GAS-DYNAMIC PRINCIPLE FOR DEEP COOLING OF THE UNDERWAY SOIL LAYER. Scientific progress, 2(7), 694-698.
35. Ахунбаев, А. А., Ражабова, Н. Р., & Вохидова, Н. Х. (2020). Исследование гидродинамики роторной сушилки с быстровращающимся ротором. Экономика и социум, (12-1), 392-396.
SCIENTIFIC PROGRESS VOLUME 4 I ISSUE 1 I 2023 _ISSN: 2181-1601
Scientific Journal Impact Factor (SJIF 2022=5.016) Passport: http://sjifactor.com/passport.php?id=22257
36. Тожиев, Р. Д., Ахунбаев, А. А., & Миршарипов, Р. X. Ражабова Н. Р. (2021). ИССЛЕДОВАНИЕ ГИДРОДИНАМИЧЕСКИХ ПРОЦЕССОВ ПРИ СУШКЕ МИНЕРАЛЬНЫХ УДОБРЕНИЙ В БАРАБАННЫХ СУШИЛКАХ. Научнотехнический журнал, 4(4).
37. Axunboev, A., Rajabova, N., Nishonov, A., & Ulmasov, I. (2021). HYDRODYNAMICS OF THE ROTOR DRYER. BARQARORLIK VA YETAKCHI TADQIQOTLAR ONLAYNILMIY JURNALI, 7(5), 144-148.
.38. Тожиев, Р. Ж., Садуллаев, Х. М., Миршарипов, Р. Х., & Ражабова, Н. Р. Суюкланма материалнинг кристалланиши ва куритиш жараёнларининг узига хослиги. ФарПИИТЖ (STJFerPI),-2019,-24 №, 1, 46-58.
39. Xakimov, A., Voxidova, N., Rajabova, N., & Mullajonova, M. (2021). The diligence of drying coal powder in the process of coal bricket manufacturing. Барцарорлик ва Етакчи Тадцицотлар онлайн илмий журнали, 1(5), 64-71.
40. Xakimov, A., Voxidova, N., & Rajabov, B. (2021). Analysis of collection of coal brickets to remove toxic gas. BARQARORLIK VA YETAKCHI TADQIQOTLAR ONLAYN ILMIY JURNALI, 1(5), 85-90.
41. Xakimov, A., Voxidova, N., Rustamov, N., & Madaminov, U. (2021). Analysis of coal bricket strength dependence on humidity. BARQARORLIK VA YETAKCHI TADQIQOTLAR ONLAYN ILMIY JURNALI, 1(5), 79-84.
42. Xakimov, A., Voxidova, N., Rajabova, N., & Mullajonova, M. (2021). The diligence of drying coal powder in the process of coal bricket manufacturing. Баркарорлик ва Етакчи Тадкикотлар онлайн илмий журнали, 1(5), 64-71.
43. Xakimov, A., Voxidova, N., & Xujaxonov, Z. (2021). Analysis of main indicators of agricultural press in the process of coal powder bricketing. BARQARORLIK VA YETAKCHI TADQIQOTLAR ONLAYN ILMIY JURNALI, 1(5), 72-78.
44. Akhmedovich, K. A. (2021). The Diligence of Drying the Coal Dust in the Process of Obtainig the Coal Brickets. International Journal of Innovative Analyses and Emerging Technology, 1(5), 111-115.
45. Xakimov, A., & Vohidova, N. (2021). RELEVANCE OF THE CHOICE OF BINDERS FOR COAL BRIQUETTES. Scientific progress, 2(8), 181-188.
