Numerical study of flow and heat transfer in a single-row bundle of horizontal finned tubes under conditions of air thermogravitational convection

Marina A. Zasimova^a, Alexey G. Abramov^a, Aleksei A. Pozhilov^a, Anastasiya V. Filatova^a, Galina S. Marshalova<sup>bc

a</sup> Peter the Great St. Petersburg Polytechnic University, St. Petersburg, Russian Federation
^b Belarusian State Technological University, Minsk, Republic of Belarus
^c Institute of Heat and Mass Transfer named, after A. V. Lykov of the NAS of Belarus, Minsk, Republic of Belarus

Abstract: The results of numerical modeling of airflow and heat transfer in a horizontally oriented single-row bundle consisting of six finned heated tubes under thermogravitational conditions are presented. The study is performed for the bundles with a compact tube arrangement and varying fin pitch. The cases without and with the rectangular exhaust shafts of different heights installed above the bundle have been investigated. For the most compact bundle configuration in the absence of a shaft in the considered range of moderate values of the Grashof number (up to $5.5 \times $$10^5$), a good agreement was obtained between the calculated integral Nusselt number at the tube surface and experimental data taken from the literature. The combination of the fin pitch (spatial arrangement on the tubes) and the shaft height determined in computations allowed to obtain the optimal bundle design with the highest intensity of heat removal.

Keywords: air-cooling, heat exchangers, tube bundles, finned tubes, fin pitch, exhaust shaft, thermogravitational convection, numerical simulation.

UDC: 532.517

Received: 10.07.2025
Received in revised form: 26.08.2025
Accepted: 27.10.2025

Language: English