Numerical investigation of heat transfer intensification in shell and helically coiled finned tube heat exchangers and design optimization

Alimoradi, Ashkan; Olfati, Mohammad; Maghareh, Meysam

doi:10.1016/j.cep.2017.08.005

Cited by 71 publications

(14 citation statements)

References 27 publications

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“…The coiled tubes heat exchangers and steam generators have many applications in different industries, including air conditioning 1 , 2 , chemical processes 3 – 5 , refrigeration 6 , nuclear 7 , 8 , and others. The main reason for using this type of heat exchanger is to improve the heat transfer coefficient due to the effects of centrifugal forces without additional energy sources.…”

Section: Introductionmentioning

confidence: 99%

Robust and universal predictive models for frictional pressure drop during two-phase flow in smooth helically coiled tube heat exchangers

Moradkhani

Hosseini

Mansouri

et al. 2021

Sci Rep

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There is a lack of well-verified models in the literature for the prediction of the frictional pressure drop (FPD) in the helically coiled tubes at different conditions/orientations. In this study, the robust and universal models for estimating two-phase FPD in smooth coiled tubes with different orientations were developed using several intelligent approaches. For this reason, a databank comprising 1267 experimental data samples was collected from 12 independent studies, which covers a broad range of fluids, tube diameters, coil diameters, coil axis inclinations, mass fluxes, saturation temperatures, and vapor qualities. The earlier models for straight and coiled tubes were examined using the collected database, which showed absolute average relative error (AARE) higher than 21%. The most relevant dimensionless groups were used as models’ inputs, and the neural network approach of multilayer perceptron and radial basis functions (RBF) were developed based on the homogenous equilibrium method. Although both intelligent models exhibited excellent accuracy, the RBF model predicted the best results with AARE 4.73% for the testing process. In addition, an explicit FPD model was developed by the genetic programming (GP), which showed the AARE of 14.97% for all data points. Capabilities of the proposed models under different conditions were described and, the sensitivity analyses were performed.

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Section: Introductionmentioning

confidence: 99%

Robust and universal predictive models for frictional pressure drop during two-phase flow in smooth helically coiled tube heat exchangers

Moradkhani

Hosseini

Mansouri

et al. 2021

Sci Rep

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show abstract

“…The numerical analysis was carried out 3D at steady state with solving the governing equations include continuity, momentum, and energy equations [18]. The section provides these equations: Continuity equation:…”

Section: Governing Equations Boundary Condition and Assumptionsmentioning

confidence: 99%

Evaluation Analysis of Double Coil Heat Exchanger for Heat Transfer Enhancement

Ali

Jumaah

Khadom

2021

DJES

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In order to maximize the thermal efficiency of shell and coil heat exchangers, substantial research has been done and geometrical modification is one way to improve the exchange of thermal energy between two or more fluids. One of the peculiar features of coiled geometry is that the temperature distribution is highly variable along the circumferential section due to the centrifugal force induced in the fluid. Moreover, most researchers are concentrated on using a shell and single helical coil heat exchanger to enhance the heat transfer rate and thermal efficiency at different operating parameters. Therefore, the aim of this study is to investigate temperature variation ((T-1, T-2, T-3 and T-4) across a shell and single/double coil heat exchanger at different coil pitches, hot water flow rate, and cold-water flow rate along the outer surface of the coil using experimental and numerical analysis. For single and double coil heat exchangers, Computational Fluid Dynamics (CFD) is carried out using pure water with a hot water flow rate ranging between 1-2 l/min for the coil side heat exchanger. For single coil heat exchangers, the numerical analysis findings showed a good agreement with experimental four-temperature measurement results (T-1, T-2, T-3 and T-4) with an error rate of 1.80%, 3.05%, 5.34% and 2.17% respectively. Moreover, in the current double coil analysis, the hot outlet temperature decreased by 3.07% compared to a single coil (baseline case) at a 2.5L/min hot water flow rate. In addition, increasing the coil pitch will increase the contact between the hot fluid and the coil at a constant hot water flow rate and thereby decrease the hot fluid outlet temperature. Finally, a computational analysis was carried out to examine the flow structure inside single and double coil heat exchangers, and the findings indicated that the effect of centrifugal forces in double coil heat exchangers at various coil pitches caused the secondary flow to be substantially reduced.

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“…Also, their results showed that the thermal performance decreases with the rise of coil pitch, while the coil pitch has a small effect on the Nusselt number. In another numerical approach, Alimoradei et al 34 investigated the turbulent fluid flow and heat transfer inside the shell with helically coiled tube. To do so, they used an annular fin on the coiled tube to enhance the heat transfer.…”

Section: Introductionmentioning

confidence: 99%

A numerical study of flow behavior in the shell and helical finned‐tube heat exchanger

et al. 2021

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Extended surfaces mostly aim to improve the heat transfer upon increasing the area of heat transfer. In this paper, the influence of using fins on flow behaviors and the heat transfer of the shell and tube heat exchanger has been investigated. In this regard, the present results are verified with available experimental data in the literature for a helical tube without fins. The effects of fin density (fin per inch), its height, and material have been studied on the heat transfer rate. In addition, the effects of radial pitch and the number of coil loops are studied. The results indicate that implementing extended surfaces significantly increases the heat transfer rate. The increase of fin density from 8 to 12 and the height from 11.5 to 13.5 mm enhances heat transfer up to 48% and 43% depending on Dean number, respectively. The rise of coil pitch augments the overall heat transfer, and it is more efficient at lower Dean numbers. The predicted results also show that the fin material does not have any significant effect on heat transfer.

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Numerical investigation of heat transfer intensification in shell and helically coiled finned tube heat exchangers and design optimization

Cited by 71 publications

References 27 publications

Robust and universal predictive models for frictional pressure drop during two-phase flow in smooth helically coiled tube heat exchangers

Robust and universal predictive models for frictional pressure drop during two-phase flow in smooth helically coiled tube heat exchangers

Evaluation Analysis of Double Coil Heat Exchanger for Heat Transfer Enhancement

A numerical study of flow behavior in the shell and helical finned‐tube heat exchanger

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