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

In the present study, two various passive methods for heat transfer enhancement, including conical ring and wire coil are placed in a tube as turbulators. Four conical rings with four side holes are utilized with the same distance. The wire coil is employed at the center of the tube. The considered Reynolds numbers are between 4000 and 10,000. The studied geometrical parameters contain the pitch and diameter of a wire coil. Four different pitches of wire coil, including 10, 12, 14, and 16 mm, are evaluated. Furthermore, four values of wire coil diameter such as 2, 4, 6, and 8 mm are certain. The obtained numerical results displayed that by declining the pitch of a wire coil (37.5%), the average Nusselt number increases by about 143%. Also, augmentation in wire coil diameter by 300% leads to a growth in average Nusselt number by about 131%. Moreover, owing to utilizing two various turbulators, the pressure drop is significantly high in comparison with the bare tube. At Re = 10,000, growth in the inner diameter of the wire coil by 300% leads to an increase in thermal performance by about 36.12%. Moreover, as the pitch of the wire coil rises by 60%, the thermal performance declines by about 35.71%.

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“…The thermal efficiency parameter is defined as follows 58–62 :

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

f = \frac{2 d_{h} normalΔ P}{ρ u^{2} L} .

…”

Section: Methodsmentioning

confidence: 99%

Heat transfer improvement in a tube by inserting perforated conical ring and wire coil as turbulators

et al. 2021

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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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“…So optimum design is required to reduce the pumping power and high cost. 51 Kumar et al 52 studied on thermal analysis of SHCTHX. They found that the average heat transfer rate was approximately 13% higher for the shell and wire coil heat exchanger in comparison with shell without wire coil inserted in HCTHE.…”

Section: Review On Heat Transfer Enhancement Techniquesmentioning

confidence: 99%

A recent state of art review on heat transfer enhanced characteristics and material selection of SCTHX

Debnath

Pradhan

2022

Proceedings of the Institution of Mechanical Engineers, Part E:

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The shell and coil tube heat exchangers (SCTHX) are widely used to transfer heat energy from one medium to another effecting medium, such as refrigeration and air conditioning system, chemical reactor, solar heater and steam power plant. The helical tubes are one of the passive heat transfer enhancement technique in heat exchanger, which are adopted in industries due to higher rate of heat transfer and simplicity in manufacturing. It has been widely employed that heat transfer coefficient in helical coils are higher compare to straight pipe by several researchers. The reason is behind that the formation of secondary flow of nano fluid. It is leading by dean vortex which is imposed to primary flow. Furthermore research on segmental and helical baffle geometry can improve the heat transfer rate in helical coil tube heat exchanger. This study is concerned with the enhancement of convective heat transfer interaction between fluid and solid surface of helical coil. The detailed descriptions of material selection, nano fluid flow physics and heat transfer enhancement inside helical coil tube are very less in open literature. A state of art review indicates that further research work can be carried out by modifying the geometry of SCTHX and enhance factors of fluid property. The heat transfer can also be enhanced by polymer additives added in nano fluids, effect of super hydrophobic surfaces and fluid bubbles generation from roughened heating surface. Finally new ideas are presented in this paper to improve the heat transfer rate and material selection for low cost manufacturing with minimum size.

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

Cited by 25 publications

References 39 publications

Heat transfer improvement in a tube by inserting perforated conical ring and wire coil as turbulators

Heat transfer improvement in a tube by inserting perforated conical ring and wire coil as turbulators

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

A recent state of art review on heat transfer enhanced characteristics and material selection of SCTHX

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