Effects of geometrical and operational parameters on heat transfer and fluid flow of three various water based nanofluids in a shell and coil tube heat exchanger

Zaboli, Mohammad; Ajarostaghi, Seyed Soheil Mousavi; Noorbakhsh, Mehdi; Delavar, Mojtaba Aghajani

doi:10.1007/s42452-019-1431-2

Cited by 37 publications

(9 citation statements)

References 37 publications

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“…The stress tensor

τ = μ true[(\nabla \overset{v}{true} + \nabla {\vec{v}}^{T} - \frac{2}{3} \nabla \times \overset{v}{true} I) true],

where μ is the molecular viscosity, I is the second‐term tensor on the right of the volume change effect. The effectiveness is defined as follows 32‐43 :

η = true(\frac{Nu}{N u_{0}} true) {(\frac{f_{0}}{f})}^{\frac{1}{3}},

Nu = \frac{h_{normalm} d}{k},

f = \frac{2 d Δ P}{ρ u^{2} L} .

…”

Section: Methodsmentioning

confidence: 99%

Influence of a curved conical turbulator on heat transfer augmentation in a helical double‐pipe heat exchanger

Ajarostaghi

2020

Heat Trans

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The rate of heat transfer in helical pipes is much more than straight pipes. In the present study, heat transfer and fluid flow in a double‐coil heat exchanger with an innovative swirl generator with a curved structure in the inner channel (hot side) are studied, numerically. The proposed turbulator has a curved structure and 12 blades to produce swirl flows. Also, two holes are considered at the semi‐conical part of the turbulator. The effects of geometrical parameters of the proposed turbulator including the inner radius of the turbulator and the radius of the turbulator's holes are evaluated. Results indicate that the maximum effectiveness belongs to the case with inner diameter of the turbulator and radius of turbulator' holes equal to 19 and 3.6 mm, respectively, at ṁ=0.008 normalknormalgnormal/normals. Also, the generated swirl flows by the turbulator has a significant influence on heat transfer augmentation. Furthermore, a high inner radius of the turbulator leads to an increase in heat transfer rate and effectiveness, consequently. As a result, by increasing the inner radius of turbulator by 26.7%, the effectiveness rises by 80% (maximum at trueṁ = 0.008 kg/s). Increasing the radius of turbulator's hole by 133.34% leads to an growth in effectiveness of about 50% (maximum at trueṁ = 0.058 kg/s).

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“…The stress tensor

τ = μ true[(\nabla \overset{v}{true} + \nabla {\vec{v}}^{T} - \frac{2}{3} \nabla \times \overset{v}{true} I) true],

where μ is the molecular viscosity, I is the second‐term tensor on the right of the volume change effect. The effectiveness is defined as follows 32‐43 :

η = true(\frac{Nu}{N u_{0}} true) {(\frac{f_{0}}{f})}^{\frac{1}{3}},

Nu = \frac{h_{normalm} d}{k},

f = \frac{2 d Δ P}{ρ u^{2} L} .

…”

Section: Methodsmentioning

confidence: 99%

Influence of a curved conical turbulator on heat transfer augmentation in a helical double‐pipe heat exchanger

Ajarostaghi

2020

Heat Trans

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“…They reported the need for fractional condensation by using multi-stage condenser for improved quality of bio-oil. The geometrical parameters of the shell and coil type condenser desing have a significant effect on effective heat trahnsfer [16].…”

Section: Condenser For Bio-oil Productionmentioning

confidence: 99%

Design improvement and experimental study on shell and tube condenser for bio-oil recovery from fast pyrolysis of wheat straw biomass

et al. 2021

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In this study, the design improvement was done in a shell and tube condenser for improved heat transfer and condensation of bio-oil vapour. The developed condenser has split shell and segmental baffles, which divide the shell in various zones and condensate collection points. The fast pyrolysis of wheat straw was done and the bio-oil vapour condensate collected from various outlets located at bottom of condenser shell. From experimental results it was found that production of bio-oil increased from 10.2 to 20.8% with increase in cooling water flow rate from 1000 to 2500 L/h; but, further increasing it beyond 2500 L/h provide marginal effects on production of bio-oil. The production of bio-oil increased from 15.2 to 20.7% as sweep gas flow rate was increased from 20 to 40 L/min at 2500 L/h of cooling water flow rate. But, further increase in sweep gas flow rate beyond 40 L/min resulted in to decrease in production of bio-oil. The novelty of this work is development of improved condenser with segmental baffles, which help in fractional condensation of bio-oil vapour, split shell for cleaning of outer surface of the cooling water tubes and compact design of condenser for optimal condensation of bio-oil.

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“…To examine the heat transfer and the pressure drop of the internal coil simultaneously, the coefficient of performance is used as follows [28][29][30][31][32][33][34][35][36][37][38][39][40][41] :…”

Section: Thermal Efficiency Equationmentioning

confidence: 99%

“…To examine the heat transfer and the pressure drop of the internal coil simultaneously, the coefficient of performance is used as follows 28‐41 :

η = true(\frac{Nu}{N u_{0}} true) {(\frac{f_{0}}{f})}^{\frac{1}{3}},

where Nu is the Nusselt number and f is the friction coefficient, which is defined as follows 28‐41 :

Nu = \frac{h_{normalm} d_{normalh}}{k},

f = \frac{2 d_{normalh} Δ P}{ρ u^{2} L} .

…”

Section: Governing Equationsmentioning

confidence: 99%

Numerical evaluation and the effects of geometrical and operational parameters on thermal performance of the shell and double coil tube heat exchanger

et al. 2020

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Heat exchangers are extensively used in various industries. In this study, the impact of geometric and flow parameters on the performance of a shell and double helical coil heat exchanger is studied numerically. The investigated geometric parameters include external coil pitch, internal coil pitch, internal coil diameter, and coil diameter. The influences of considered geometrical parameters are analyzed on the output temperature of the hot and cold fluid, convective heat transfer coefficient, pressure drop, and average Nusselt number. Water is considered as working fluid in both shell and tube. As an innovation, double helical coils are used instead of one in the heat exchanger. To compare the obtained results accurately, in each section, the heat transfer area (coil outer surface) is kept constant in all models. The results show that the geometrical parameters of double helical coils significantly affect the heat transfer rate.

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Effects of geometrical and operational parameters on heat transfer and fluid flow of three various water based nanofluids in a shell and coil tube heat exchanger

Cited by 37 publications

References 37 publications

Influence of a curved conical turbulator on heat transfer augmentation in a helical double‐pipe heat exchanger

Influence of a curved conical turbulator on heat transfer augmentation in a helical double‐pipe heat exchanger

Design improvement and experimental study on shell and tube condenser for bio-oil recovery from fast pyrolysis of wheat straw biomass

Numerical evaluation and the effects of geometrical and operational parameters on thermal performance of the shell and double coil tube heat exchanger

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