Experimental study on thermo‐hydraulic performance of nanofluids upward flowing through helical tubes of heat exchanger system based on thermal efficiency

Abstract

Convective heat transfer and resistance coefficient of nanofluids upward flowing through helical tubes are experimentally researched in this paper.The effects of three factors (thread pitches [s = 10, 12.5, and 15 cm], inclination angles [β = 0°, 45°, and 90°], and nanoparticle mass fractions [ω = 0.0, 0.1, 0.3, and 0.5 wt.%]) on the heat transfer and flow characteristics are discussed. A thermal efficiency evaluation plot is applied to evaluate the thermo-hydraulic performance of nanofluids. Results show that Nusselt number and resistance coefficient increase with the increasing nanoparticle mass fraction and the decreasing thread pitches. It is also found that helical tube with inclination angle β = 45°shows the best heat transfer performance and that with inclination angle β = 90°shows the worst heat transfer performance. In addition, it is found from the thermal efficiency evaluation plot that the experimental data almost locate in Regions I and II and nanofluids in helical tubes can improve the heat transfer under the same pressure drop. The helical tube with s = 10 cm and β = 45°at the range of Reynolds number (Re > 8,000) shows the largest thermal efficiency.

Influence of rotation angle of a triangular tube with a built‐in twisted tape on the thermal‐exergy efficiency and entropy generation of nanofluids in the heat exchange system

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“…Forced convection of different nanofluids in heat exchanger has been widely studied by scholars. The types of nanoparticles include metals, 25 metal oxides, [26][27][28] nanocarbon, [29][30][31] and so on. Nakhjavani et al 32 synthesized silver nanoparticles with better stability from green tea.…”

Regulation of natural convection heat transfer for SiO2–solar salt nanofluids by optimizing rectangular vessels design

“…Excellent outcomes have been obtained after decades of research. However, there still exist some unsolved issues with regard to heat transfer, especially for nanofluids, due to complex interphase and interparticle interactions …”

“…However, there still exist some unsolved issues with regard to heat transfer, especially for nanofluids, due to complex interphase and interparticle interactions. [11][12][13][14] Molten salts are widely used in solar power stations and the nuclear industry. However, some undesirable properties set a limitation on further applications of molten salts.…”

Thermal and exergy efficiency of magnetohydrodynamic Fe3O4‐H2O nanofluids flowing through a built‐in twisted turbulator corrugated tube under magnetic field

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