RESUMO
This study introduces a numerical model to assess the thermal and frictional properties of LBE crossflow over tube bundles on the shell side of a Helical-coiled Once-Through Steam Generator (H-OTSG) considering different arrangements, including inline, obliquely staggered, triangular, and rotated square configurations. The k-ω SST turbulence model combined with Kays turbulent Prandtl number model is utilized to develop the numerical model. The simulation results have been validated against experimental data and empirical correlations. The layouts of the tube bundles significantly influence the generation of transverse flow, vortical structures and rate of heat transfer in the flow domain. The maximum Nusselt number of 8.2 is observed for the triangular layout as significant crossflow is induced, which is a 10% increase compared to the inline arrangement where the Nusselt number is 7.45. Triangle layouts also exhibit a higher friction factor of 0.45, marking a 20% increase compared to the 0.45 friction factor observed in the inline arrangement. Increasing the oblique angle usually reduces the heat transfer rate and friction factor. Yet, at a 45-degree layout, higher turbulence intensity results in a Nu of 7.05, surpassing 6.93 observed at 30° but falling short of 7.15 at 15°. Nu decreases for rotated square arrangements, but a friction factor greater than the inline arrangement is observed at higher diagonal pitches. The Thermal Enhancement Factor (THEF) is employed to assess the thermal effectiveness of the different tube bundle layouts, and the maximum THEF of 1.1 is observed for the layout with an oblique angle of 45°. Favorable THEF values of 1.06 and 1.05 are recorded for the triangular layout and 30-degree oblique angle, respectively. This numerical study will assist the design and development of LBE H-OTSG.
RESUMO
This research paper investigates the optimization of radiation performance of a plasma-based bioconvective nanofluid integrated Magneto-hydrodynamic (MHD) micropump for radiative oncology. It addresses a literature gap by analysing the radiative impact of blood-based hybrid nanofluids in MHD micropumps. Three blood-based bio-convective radiating hybrid nanofluids-blood-Pt, blood-Au and blood-MWCNT are studied to understand their radiation behaviour in MHD pump while being employed as transportation medium. The investigation employs two non-dimensional parameters, namely Rd (Radiation number) and Ha (Hartmann number), to examine the fluid dynamics, magnetic characteristics, and electrical properties of the MHD micropump. The temperature gradient, velocity distribution, and pressure drop along the flow channel are examined within the specified range of Rd and Ha. Magnetic flux density (MFD) and electric flux intensity (EFI) are evaluated to understand nanoparticle behaviour during drug delivery and blood transportation. Findings highlight that MWCNT and Pt are the most efficient bioconvective nanoparticles for plasma transportation under high radiative conditions. MWCNT-based blood flow exhibits desirable characteristics, including sufficient intake pressure of 4.5 kPa and minimal relative pressure drop of 34%. Coherence between radiation flux and electromagnetic flux reduces pumping power and ensures uniform heat dissipation for improved drug delivery. Au nanoparticles provide moderate magnetic flux density with least fluctuation within the range of Ha and Rd number (2.57 T to 4.39 T), even in highly radiative environments (such as-Rd = 4, Rd = 5), making them suitable for applications like embedded chemotherapy or cell treatment. Au nanoparticles maintain moderate electrical flux intensity with a minimal drop of 16nA, particularly at higher radiative environments influenced by the Radiation number (Rd = 4 to Rd = 5) while Ha values from Ha = 2 to Ha = 4. Conclusively, it has been identified that MWCNT and Au are superior nanofluids for advanced radiative oncological treatments. These nanofluids have the potential to enhance plasma transportation, thermal regulation, and aetilogical disease management. The present study provides significant findings on enhancing the radiation performance in MHD micropumps through utilization of blood-based hybrid nanofluids, thereby offering potential advantages to the domain of biomedical engineering.
RESUMO
The mechanical behavior of aluminum hexagonal honeycombs subjected to out-of-plane dynamic indentation and compression loads has been investigated numerically using ANSYS/LS-DYNA in this paper. The finite element (FE) models have been verified by previous experimental results in terms of deformation pattern, stress-strain curve, and energy dissipation. The verified FE models have then been used in comprehensive numerical analysis of different aluminum honeycombs. Plateau stress, σpl, and dissipated energy (EI for indentation and EC for compression) have been calculated at different strain rates ranging from 10² to 104 s-1. The effects of strain rate and t/l ratio on the plateau stress, dissipated energy, and tearing energy have been discussed. An empirical formula is proposed to describe the relationship between the tearing energy per unit fracture area, relative density, and strain rate for honeycombs. Moreover, it has been found that a generic formula can be used to describe the relationship between tearing energy per unit fracture area and relative density for both aluminum honeycombs and foams.
