UDC: 538.9        https://doi.org/10.62965/tnu.sns.2024.1.8

Nizomov Z., Turakhasanov I.T., Saidzoda R.Kh.

Tajik National University

Tajik Technical University named after M.S. Osimi

The influence of the diameter of cylindrical samples from various grades of technical aluminum (A0, A5, A6), aviation AB98 and high-purity aluminum A5N on their characteristic cooling times and rates, as well as on heat transfer processes in a wide temperature range, was studied. It was revealed that cooling of the samples occurs due to convective heat transfer and radiation, which have characteristic times.

An assessment of the magnitude of characteristic cooling times due to convective heat transfer and radiation has been carried out. It is shown that the characteristic cooling time due to radiation is less than the characteristic cooling time due to convection. Using experimental data on the cooling rate of the studied samples and theoretically calculated values of their heat capacity according to the Neumann-Kopp rule, heat transfer coefficients for the processes of convective heat transfer and radiation depending on temperature were determined. It has been established that with increasing temperature, the contribution of radiation to the total heat transfer coefficient increases, and the coefficient of convective heat transfer with increasing temperature first increases, then after passing a maximum it decreases. The contribution to the overall heat transfer coefficient from radiation is noticeable at high temperatures. It was revealed that the characteristic cooling times due to radiation and convection increase nonlinearly with increasing sample diameter (V/S). This dependence is explained by a decrease in the heat transfer coefficient with increasing sample diameter. Compared with the patterns of influence of sample size on the thermophysical properties of spherical samples. It was revealed that spherical samples cool faster than cylindrical samples of the same mass, and the heat transfer coefficients are higher.

Key words: aluminum of various grades, cooling, convection, thermal radiation, size effect, temperature dependence.

Information about the authors

Nizomov Ziyovuddin - Tajik National University,

Candidate of Physical and Mathematical Sciences, Associate Professor, Leading Researcher of the Research Institute.

Address: 734025, Dushanbe, Republic of Tajikistan, Rudaki Street 17.

Phone: (+992) 933 00 20 15. E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it..

Turahasanov Isfandiyor Turahasanovich– Tajik Technical University named after M.S. Osimi,

Senior lecturer of the Department of theoretical foundations of radio and electrical ingineering.

Address: 734042, Dushanbe, Republic of Tajikistan, academician Rajabovs street 10.

Phone: (+992) 93 528 10 01. E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it..

Saidzoda Rahim Hamro - Tajik Technical University named after Academician M.S. Osimi,

Doctor of Technical Sciences, Professor.

Address:  734042, Dushanbe, Republic of Tajikistan, academician Rajabovs street 10.

Phone (+992) 981010072. E-mail: rahsai @mail.ru

REVIEWER: Abdulloev H.M., Doctor physical and mathematical sciences, Professor

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Article received 28.08.2023

Approved after review 11.10.2023

Accepted for publication 25.12.2023