Entropy generation analysis for laminar thermal augmentation with conical strip inserts in horizontal circular tubes

You, Yonghua; Fan, Aiwu; Liu, Yuming; Jin, Shiping; Liu, Wei; Dai, Fangqin

doi:10.1016/j.ijthermalsci.2014.10.003

Cited by 27 publications

(4 citation statements)

References 31 publications

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“…Ko and Wu [32] used numerical techniques to study the generation of entropy inside a curving rectangular channel under heating. In another study, You et al [33] studied the heat transfer increase in horizontal circuitous pipes with conical strip inserts from the view of minimal entropy production. Mwesigye et al [34] researched the application of twisted tapes to promote heat transmission combined with generating entropy in parabolic trough receivers.…”

Section: Introductionmentioning

confidence: 99%

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

Khfagi

Hunt

Paul

et al. 2022

J Therm Anal Calorim

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This work investigates heat transfer and entropy generation of a turbulent flow of an Al2O3–Cu/water hybrid nanofluid in a plain tube (PT) with classical (TPT) and elliptical‑cut twisted tape (TECT) inserts. The heat transfer and pressure drop are investigated numerically at Re (7000–15,000), mass concentration (1–4%), and the inlet temperature of the fluid (300 K). Further, the total entropy generation and Bejan number are examined at Re = 7000 and a mass concentration of 4%. The obtained results indicate that heat transfer can be intensified when inserting classical and elliptical‑cut twisted tape. In addition, an increase in the thermal conductivity of the fluid may cause a slight increase in the heat transfer coefficient. Moreover, heat transfer and thermal performance factors increase when the mass concentration of nanoparticles increases. The Nusselt numbers for TECT and TPT are 1.7 and 1.57 times higher than those for PT, respectively. The Nusselt number and thermal performance factor of hybrid nanofluid are greatest at roughly 195 and 1.9, respectively, showing 3.9% and 7.73% improvement compared to CuO/water nanofluid at Re = 7000. The analysis of the generation of entropy is expressed as a function of thermal and frictional contributions. The results indicate the existence of a minimum entropy generation for each type of tubes for Al2O3–Cu/water hybrid nanofluid. Total entropy generation analysis demonstrates that thermal entropy generation dominates at high heat flux. Moreover, increasing the nanoparticles decreases the generation of total entropy, which is ascribed to the thermal conductivity increment. In addition, the rate of total entropy generation declines as the vortex flow increases.

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Section: Introductionmentioning

confidence: 99%

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

Khfagi

Hunt

Paul

et al. 2022

J Therm Anal Calorim

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“…Considering the influence of temperature on metal properties, fatigue life data of bolted joints are obtained under different temperatures, 40 as shown in Table 7.…”

Section: Fatigue Life Analysis Of Plane Bolted Jointsmentioning

confidence: 99%

Numerical method for fatigue life of plane bolted joints under thermal load

You

Fang

Liu

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part G:

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In fatigue test, the fatigue life of metal components is affected by many factors, such as test temperature, stress ratio and loading frequency. In order to study the influence of temperature on fatigue life of bolted joints, thermal stress and fast coefficient are introduced. A numerical method of fatigue crack initiation life is proposed based on Manson-Coffin strain fatigue formula. The crack initiation life of 2024 aluminum alloy at different temperatures can be obtained by this method, which provides a theoretical basis for the fatigue life prediction of metals. Then, the stress severity factor SSF is introduced to calculate fatigue life of plane bolted joints. The data obtained from the model show that the crack initiation life of aluminum alloy specimen decreases significantly with test temperature rises, the same as the fatigue life of bolted joints.

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“…During the magnetic refrigeration cycle, the solid MCMs were subjected to a magnetic field of varied intensity. With the consideration of the effect of the magnetic power, the refrigeration process could be expressed by the following fluid and solid energy conservation equations [ 26 , 27 , 35 ]:

where T and t refer to the temperature and time, respectively, while the subscripts f and s represent the fluid and the solid, respectively.

represents the viscous stress tensor and:

.…”

Section: Numerical Model and Computation Schemementioning

confidence: 99%

“…As is well known, entropy generation takes place in an irreversible process [ 32 ], and the minimal entropy generation principle can be applied for the optimal design of various thermal equipment [ 33 , 34 , 35 ]. With the assumption of trivial fluid thermal capacity, Rowe and Barclay proposed an expression of temperature for optimal magneto-caloric effects, from the aspect of entropy generation minimization [ 36 ].…”

Section: Introductionmentioning

confidence: 99%

Refrigeration Performance and Entropy Generation Analysis for Reciprocating Magnetic Refrigerator with Gd Plates

You

Yang

et al. 2018

Entropy

Self Cite

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In the current work, a novel 2D numerical model of stationary grids was developed for reciprocating magnetic refrigerators, with Gd plates, in which the magneto-caloric properties, derived from the Weiss molecular field theory, were adopted for the built-in energy source of the magneto-caloric effect. The numerical simulation was conducted under the conditions of different structural and operational parameters, and the effects of the relative fluid displacement (φ) on the specific refrigeration capacity (qref) and the Coefficient of Performance (COP) were obtained. Besides the variations of entropy, the generation rate and number were studied and the contours of the local entropy generation rate are presented for discussion. From the current work, it is found that with an increase in φ, both the qref and COP followed the convex variation trend, while the entropy generation number (Ns) varied concavely. As for the current cases, the maximal qref and COP were equal to 151.2 kW/m 3 and 9.11, respectively, while the lowest Ns was the value of 2.4 × 10 −4 K −1 . However, the optimal φ for the largest qref and COP, and for the lowest Ns, were inconsistent, thus, some compromises need be made in the optimization of magnetic refrigerators.

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Entropy generation analysis for laminar thermal augmentation with conical strip inserts in horizontal circular tubes

Cited by 27 publications

References 31 publications

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

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

Numerical method for fatigue life of plane bolted joints under thermal load

Refrigeration Performance and Entropy Generation Analysis for Reciprocating Magnetic Refrigerator with Gd Plates

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