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

Abstract

In order to investigate the thermal-exergy efficiency and entropy generation of nanofluids flowing through a triangular tube with a built-in twisted tape, a heat exchange system is designed and established. Deionized water and three mass concentration nanofluids (ω = 0.1 wt%, 0.3 wt%, and 0.5 wt%) are applied as the heat-transfer mediums flowing through three different rotation angle (α = 0 , 30 , and 60 ) triangular tubes, respectively.Thermal efficiency index (η) and entropy generation (S) are used to characterize the performance of the heat exchange system. It is proved that the increase of nanoparticles can not only effectively promote the heat transfer effect but also augment the pressure loss. Nusselt number of nanofluids is increased by 20.2% on average, whereas the flow resistance coefficient is increased by 10.1% on average. Based on the thermal efficiency index, the data demonstrate that ω = 0.5 wt% nanofluids in the triangular tube at α = 0 can make the most effective use of energy, whose value could reach 1.32 at most. Exergy efficiency of nanofluids in the heat exchange system can be evidently heightened under the same pumping power and flow rate. Entropy production of 0.1 wt% nanofluids is the smallest. K E Y W O R D Snanofluids, forced convection, exergy efficiency, entropy generation

Computational analysis of heat transfer augmentation and thermodynamic irreversibility of hybrid nanofluids in a tube fitted with classical and elliptical‑cut twisted tape inserts

“…As a result, the ellipticalcut twisted tape could greatly reduce the total entropy generation. According to [58,59], entropy generation reduces with a rise in swirl intensity. In other words, the increase in vortical flow results in a further reduction in the total entropy generated when the hybrid nanofluid is present.…”

Numerical simulation of nanofluids forced convection in a corrugated double‐pipe heat exchanger

“…[11] Nanofluids have attracted a great deal of attention because of their excellent thermophysical properties. [12,13] As a new type of working material, nanofluids have been widely applied in microchannels, [14] photothermal conversion, [15] as well as heat exchangers. [16,17] In recent years, TiO 2 nanofluids have become a research hotspot because they can efficiently enhance the thermal conductivity of fluids and have better dispersion stability than other metal oxide nanofluids.…”

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

“…Naphon et al researched the nanofluids heat exchange enhancement mechanism in the micro‐channel heat sink 39 and micro‐fin tubes 40 by experimental research and numerical simulation, and made corresponding progress. Qi et al conducted detailed studies on the forced convection heat transfer of different nanofluids, such as SiO 2 ‐H 2 O nanofluids in the triangle tube, 41 water‐based TiO 2 nanofluids in double‐pipe heat exchangers, 42 in triangular tubes, 43 in CPU cooling system 44,45 and in different helical tubes, 46 Fe 3 O 4 ‐H 2 O magnetofluids in the circular tube under vertical magnetic field 47 . These studies all reflected that nanofluids have better heat transfer characteristics and comprehensive performance in comparison with the based fluid.…”