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    A NUMERICAL STUDY FOR SOLID AND SERRATED ANNULAR FINNED TUBE BUNDLES
    (Vinca Inst Nuclear Sci, 2022) Tacgun, Ekrem; Aksoy, I. Gokhan
    Annular finned tube bundles are commonly used for heat recovery systems. Nowadays, heat recovery systems are important in the energy economy. Cross-flow heat exchangers, one of the heat exchanger types are suitable for waste heat recovery systems. Annular fins are utilized in cross-flow heat exchangers for a long time. In this study, two types of annular fin geometry, namely solid and serrated fins, were studied numerically in the cross-flow heat exchangers. All numerical analyses are performed in ANSYA-FLUENT program and the fin geometries are designed in 3-D geometry. Numerical results obtained for two different geometry fins are validated separately with the literature. It is seen that analysis results are found to be compatible with the literature. In numerical analyses, five different Reynolds Numbers and six different geometric parameters are studied. Effects of these parameters are investigated to determine the flow and thermal performance. According to analysis results, the thermal performance of the serrated annular fin geometry is about 8.2% higher than the solid fin geometry, while the flow performance decreases by 7.5%.
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    THERMAL AND FLOW ANALYSES OF PERFORATED SERRATED ANNULAR FINNED-TUBE BUNDLES IN A CROSS-FLOW HEAT EXCHANGER
    (Begell House Inc, 2023) Tacgun, Ekrem; Aksoy, I. Gokhan
    The thermal and flow analysis of a cross-flow heat exchanger is numerically investigated by experimental validation in this study. The cross-flow heat exchanger consists of a tube bundle with perforated serrated annular fins. Numerical analysis is performed in three dimensions by using the ANSYS Fluent program. Numerical studies are validated separately for thermal and flow characteristics. For the validation study, experiments are performed on a cross-flow heat exchanger experimental setup at five different Re numbers. The numerical results are found to be in agreement with these experiments using the appropriate turbulence model. Perforated serrated annular finned-tube bundles are compared with the existing tube bundles in the literature such as annular solid and serrated finned-tube bundles in terms of heat transfer and flow friction. As a result of the numerical analyses, heat transfer of the perforated serrated finned-tube bundle is 14.2% and 5.2% higher than that of solid and serrated finned-tube bundles, respectively. At the same time flow friction of the perforated serrated finned-tube bundle is also higher than that of solid and serrated finned-tube bundles. In addition, the segment height ratio is determined as a variable geometric parameter. This geometric parameter is examined for five Re numbers. The effects of this parameter on heat transfer and flow friction are investigated separately. As a result, it has been observed that drilling of circular holes on the segment section of the annular serrated finned-tube bundles increases heat transfer and flow friction.