Effect of rotating twisted tape on thermo-hydraulic performances of nanofluids in heat-exchanger systems

Qi, Cong; Wang, Guiqing; Yan, Yuying; Mei, Siyuan; Luo, Tao

doi:10.1016/j.enconman.2018.04.086

Cited by 89 publications

(38 citation statements)

References 44 publications

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“…The results demonstrated that the low-to-high PR twisted tape yielded an increasing trend of η as Re increased. However, the maximum η value of the low-to-high twisted tape was lower than those of other modifications, such as RGPR and rotation of the twisted tape [23]. This is due to differences in terms of other parameters that influenced the system's performance.…”

Section: Introductionmentioning

confidence: 85%

Numerical and Experimental Analysis of the Thermal Performances of SiC/Water and Al2O3/Water Nanofluid Inside a Circular Tube with Constant-Increased-PR Twisted Tape

2020

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The simultaneous use of two passive methods (twisted tape and a nanofluid) in a heat transfer system will increase the average Nusselt number (Nu) of the system. However, the presence of inserts and nanoparticles inside the tube will create higher pressure drop (ΔP) in the system, which can eventually affect the overall enhancement ratio (η), especially at higher Reynolds numbers (Re). Several modifications of twisted tapes have been made to reduce ΔP, but most showed a decreasing trend of η as Re increased. The objective of this study is to design a new geometry of twisted tape that yields a larger value of Nu and a smaller value of ΔP, which can result in a larger value of η especially at higher Re. A simulation and experimental analysis are conducted in which Re ranges from 4000–16,000 with two types of nanofluids (SiC/Water and Al2O3/Water) at various values of the volume fraction, (φ) (1–3%). ANSYS FLUENT software with the RNG k-ɛ turbulent model is adopted for the simulation analysis. Three types of twisted tape are used in the analysis: classic twisted tape with a pitch ratio of 2 (TT PR2), constant-increasing-pitch-ratio twisted tape (TT IPR) and constant-decreasing-pitch-ratio twisted tape (TT DPR). The use of TT IPR generates a stronger swirling flow at the inlet of the tube and smaller ∆P, especially near the outlet region. The highest value of η is obtained for 3% SiC/Water nanofluid that is flowing through a smooth circular tube with TT IPR inserts at Re of 10,000.

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Section: Introductionmentioning

confidence: 85%

Numerical and Experimental Analysis of the Thermal Performances of SiC/Water and Al2O3/Water Nanofluid Inside a Circular Tube with Constant-Increased-PR Twisted Tape

2020

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“…This compelled the researcher to do a comprehensive thermo‐hydraulic performance analysis of the problem and to achieve an optimal working condition of the problem. A comprehensive performance index of the problem was formulated by using thermal and exergy efficiency theories . The best‐suited condition for the problem was identified from the formulated equation of comprehensive performance index, to get the maximum HT and least increase in Δ p of the working fluid.…”

Section: Challenges With Nanofluidsmentioning

confidence: 99%

Performance enhancement of photovoltaic modules by nanofluid cooling: A comprehensive review

2020

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Summary Only 15‐20% of solar radiation incident on the photovoltaic (PV) cells is utilized which further reduces due to the rise in the temperature of the PV module and it also degrades the lifespan of the PV module. Therefore, numerous attempts were made to reduce this rising temperature of the PV module and different cooling techniques were employed. Nanofluid cooling is one of the potential cooling techniques for lowering the temperature of the PV module and augmenting the heat transfer by increasing the thermal conductivity of the nanofluid relative to the base fluid (BF). The experimental and numerical studies related to the cooling of PV cells with nanofluids have been reviewed. It was found that the heat transfer from the back of the PV module is enhanced with the augmentation in the concentration of nanoparticle in BF; however, some studies also demonstrate that the enhancement in the heat transfer also depends upon other factors such as the geometry at the rear of the PV module, nanoparticle material, nanoparticle size, BF, ambient conditions, etc. This review article also demonstrates the various issues with nanofluids such as instability, technological difficulties, high system costs, and the impossibility of finding a viable operational design which creates a barrier in the commercialization of the nanofluid cooling technique for PV modules.

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“…A parameter (exergy efficiency) describing the "quality" of energy is proposed to guide this work. The equation of exergy efficiency is presented 55 :…”

Section: Theoretical Calculationmentioning

confidence: 99%

Effects of metal foam on exergy and entropy of nanofluids in a heat sink applied for thermal management of electronic components

Chen

et al. 2020

Int J Energy Res

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To solve the high heat dissipation of the heat sink, a set of experimental device for the flow and heat transfer of the nanofluids through a heat sink filled with metal foam was established in this paper. The impacts of metal foam with diverse pore densities (PPI = 20, 30, 40), nanoparticle mass fractions (from β = 0.0 wt% to β = 0.5 wt%) and Reynolds numbers (Re = 414-1119) on the flow and heat transfer characteristics were investigated. In addition, the thermal and hydraulic properties were evaluated by the exergy efficiency and entropy generation. The conclusions displayed that the metal foam with a pore density (PPI = 40) is instrumental in strengthening the heat transfer under a certain porosity, and the heat sink under the working condition (β = 0.3 wt% and PPI = 40) possesses the best capacity of thermal performance. Nanofluids and metal foam (PPI = 40) can improve Nusselt number by 6.13% and 3.2% at most compared with water and metal foam (PPI = 20 and PPI = 30), respectively. Nanofluids with β = 0.3 wt% exhibit the highest exergy efficiency, and the metal foam with PPI = 40 shows the smallest entropy generation.

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Effect of rotating twisted tape on thermo-hydraulic performances of nanofluids in heat-exchanger systems

Cited by 89 publications

References 44 publications

Numerical and Experimental Analysis of the Thermal Performances of SiC/Water and Al2O3/Water Nanofluid Inside a Circular Tube with Constant-Increased-PR Twisted Tape

Numerical and Experimental Analysis of the Thermal Performances of SiC/Water and Al2O3/Water Nanofluid Inside a Circular Tube with Constant-Increased-PR Twisted Tape

Performance enhancement of photovoltaic modules by nanofluid cooling: A comprehensive review

Effects of metal foam on exergy and entropy of nanofluids in a heat sink applied for thermal management of electronic components

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