Thermal-aerodynamic characteristics of staggered mixed tubes bundle composed of circular and drop-shaped tubes

The purpose of this study is to clarify heat transfer and fluid flow behavior across six-row mixed tubes bundles. The tubes bundle is consisting of circular and drop-shaped cross-sections in a staggered arrangement. The Reynolds number Re for the flow is varied from 1.78x103 to 18.72x103. Six cases of the mixed tubes bundle are considered. The results of the mixed tubes bundles are compared with those of the circular (case I) and drop-shaped ones (case II). ANSYS Fluent software package is utilized to predict the flow pattern over the tubes bundles. The results of the numerical simulation showed that the cross-sectional shape of the tubes and their location in the bundle significantly affect the heat transfer and pressure drop in the bundle. Case IV (circular tubes in the 1st,3rd,5th rows, and drop-shaped tubes in the 2nd, 4th, 6th rows) increases the average Nusselt number (Nu) ̅ by about 1.11–8.10% and 47.86–49.04% compared to that of the circular and drop-shaped tubes bundle, respectively. Case VII (drop-shaped tubes in the 1st, 2nd, 4th, 6th rows, and circular tubes in the 3rd, 4th rows) has the lowest friction factor f compared to the other cases of circular and mixed tubes bundles. Moreover, the maximum values of the thermal-hydraulic performance ε are achieved in the case IV at Re =1.78x103 and the case VII at Re>1.78x103, which were about 14.55% and (2.08 – 4.49)%, respectively, higher than those obtained for the drop-shaped tubes bundle. Generalized correlations for (Nu) ̅, f, and ε for the studied mixed tubes bundles were predicted.

drop-shaped tube, circular tube, mixed tubes, heat transfer, friction factor, Nusselt number, friction factor, effectiveness, efficiency, thermal – hydraulic performance, heat exchanger, CFD, Fluent.

Volume 23, issue 2, 2022 year

Теплоаэродинамические характеристики шахматного смешанного пучка круглых и каплевидных труб

Настоящая работа была проведена с целью исследования характеристик теплообмена пучка труб, состоящего из круглого и каплевидного сечений, расположенных в шахматной компоновке. Число Рейнольдса Re варьируется от 1,78x103 до 18,72x103. Рассмотрены шесть случаев смешанного пучка труб. Теплогидродинамические характеристики смешанных пучков труб сравниваются с круглыми (случай I) и каплевидными (случай II). Программный пакет ANSYS Fluent используется для прогнозирования линии тока в пучках труб. Результаты численного моделирования показали, что форма поперечного сечения труб и их расположение в пучке существенно влияют на теплообмен и перепад давления в пучке. Случай IV (круглые трубы в 1-м, 3-м, 5-м рядах и каплевидные трубы во 2-м, 4-м, 6-м рядах) среднее число Нуссельта Nuср увеличивается примерно на 1,11–8,10% и 47,86–49,04% по сравнению с круглым и каплевидным пучком труб, соответственно. Случай VII (каплевидные трубы в 1-м, 2-м, 4-м, 6-м рядах и круглые трубы в 3-м, 4-м рядах) имеет наименьший коэффициент гидродинамического сопротивления f по сравнению с другими случаями круглых и смешанных пучков труб. При этом максимальные значения теплогидрадинамической эффективности ε достигаются в случае IV при Re =1,78x103 и в случае VII при Re>1,78x103, которые были на 14,55 % и (2,08‒4,49) % соответственно выше, чем у пучка каплевидных труб. Предложены зависимости, позволяющие определить Nuср, f и ε для исследованных смешанных пучков труб.

каплевидная труба, круглая труба, смешанные трубы, теплообмен, теплообменник, число Нуссельта, коэффициент гидродинамического сопротивления, эффективность, численное исследование, CFD, Fluent.

Volume 23, issue 2, 2022 year

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