Abstract
Objectives. Mathematical modeling of heat transfer in flat channels with turbulators symmetrically located on both its sides, depending on the cross section of the turbulators.Methods. The calculation was carried out on the basis of a theoretical method based on solving the Reynolds equations factorized by the finite-volume finite-volume method, closed using the Menter shear stress transfer model, and the energy equation on multi-scale intersecting structured grids (FCOM), which was successfully tested in [23].Results. The article results of calculating the intensified heat exchange in flat channels with double turbulators of different cross sections (square, rectangular, semicircular, triangular) depending on the determining parameters were quite satisfactorily consistent with the existing experimental material, but having an indisputable advantage over the latter, since the assumptions made in their derivation cover a much wider range of defining parameters than the limitations found in the experiments (Pr=0.7÷100, Re=103÷106, h/dE =0.005÷0.2, t/h=1÷200).Conclusion. According to the results of calculations on the basis of the developed model, it is possible to optimize heat transfer intensification in flat channels with double turbulators of different cross sections, as well as control the heat transfer intensification process. As shown by the calculated data, with the intensification of heat transfer in the flat channels, symmetrical protrusions of square, rectangular and triangular cross sections, i.e. relatively sharp outlines, in the vortices up to the protrusions and behind them the production of turbulence is comparable to energy dissipation, which leads to increased hydraulic losses; for flat channels with protrusions of a semicircular cross section, i.e. relatively smooth outlines, the energy dissipation is much smaller, therefore, the hydraulic resistance in such channels is less. A detailed analysis of the structure of the vortex zones (main, angular, secondary, etc.) between periodic surface flow turbulators of square, semicircular, triangular and rectangular cross sections depending on the geometric and regime parameters of the coolant flow was carried out, the effect of the above vortex zones heat transfer and hydraulic resistance of the channel; additionally confirmed the optimality of application to abrutized turbulators, where hydraulic losses are much smaller than for sharp turbulators, which is directly or indirectly verified by existing experimental material [1—6].
Highlights
The calculation was carried out on the basis of a theoretical method based on solving the Reynolds equations factorized by the finite-volume finite-volume method, closed using the Menter shear stress transfer model, and the energy equation on multi-scale intersecting structured grids (FCOM), which was successfully tested in [23]
The article results of calculating the intensified heat exchange in flat channels with double turbulators of different cross sections depending on the determining parameters were quite satisfactorily consistent with the existing experimental material, but having an indisputable advantage over the latter, since the assumptions made in their derivation cover a much wider range of defining parameters than the limitations found in the experiments (Pr=0.7÷100, Re=103÷106, h/dE =0.005÷0.2, t/h=1÷200)
As shown by the calculated data, with the intensification of heat transfer in the flat channels, symmetrical protrusions of square, rectangular and triangular cross sections, i.e. relatively sharp outlines, in the vortices up to the protrusions and behind them the production of turbulence is comparable to energy dissipation, which leads to increased hydraulic losses; for flat channels with protrusions of a semicircular cross section, i.e. relatively smooth outlines, the energy dissipation is much smaller, the hydraulic resistance in such channels is less
Summary
При применении турбулизаторов треугольного поперечного сечения основные вихри за ними более всего выходят в ядро потока, даже по сравнению с квадратными и прямоугольными турбулизаторами, что обусловливает увеличение теплообмена и, особенно, гидравлического сопротивления для треугольных турбулизаторов; данная тенденция будет сохраняться вплоть до достижения относительно больших чисел Рейнольдса, при которых будет иметь место генерация вторичных вихрей над квадратными и прямоугольными турбулизаторами, что обусловит вытеснение основного вихря в ядро потока. Гидравлическое сопротивление, а также в меньшей степени, теплообмен в трубах с турбулизаторами полукруглого поперечного сечения меньше, при прочих равных условиях, чем в трубах с турбулизаторами других поперечных сечений — квадратного, прямоугольного, треугольного, — что обусловливает более рациональное соотношение между интенсифицированными теплообменом и гидравлическим сопротивлением в плоских каналах с двойными симметрично расположенными поверхностными турбулизаторами потока.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Herald of Dagestan State Technical University. Technical Sciences
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
