A Review and Correlations for Convection Heat Transfer and Pressure Losses in Toroidal and Helically Coiled Tubes

El‐Genk, Mohamed S.; Schriener, Timothy M.

doi:10.1080/01457632.2016.1194693

Cited by 51 publications

(11 citation statements)

References 48 publications

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“…Results vary significantly. Values obtained using the correlation from Mandal and Nigam [59] are considerably higher than the results for helically coiled tubes provided by Kumar et al [60], Guo et al [61], Roger and Mayhew [62] as well as El-Genk and Schriener [55]. Mandal and Nigam explain this with baffles that are inserted into the outer tube of their tube-in-tube heat exchanger.…”

Section: Outer Tube Nusselt Numbersmentioning

confidence: 45%

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Stop Smoking—Tube-In-Tube Helical System for Flameless Calcination of Minerals

2017

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Mineral calcination worldwide accounts for some 5-10% of all anthropogenic carbon dioxide (CO 2 ) emissions per year. Roughly half of the CO 2 released results from burning fossil fuels for heat generation, while the other half is a product of the calcination reaction itself. Traditionally, the fuel combustion process and the calcination reaction take place together to enhance heat transfer. Systems have been proposed that separate fuel combustion and calcination to allow for the sequestration of pure CO 2 from the calcination reaction for later storage/use and capture of the combustion gases. This work presents a new tube-in-tube helical system for the calcination of minerals that can use different heat transfer fluids (HTFs), employed or foreseen in concentrated solar power (CSP) plants. The system is labeled 'flameless' since the HTF can be heated by other means than burning fossil fuels. If CSP or high-temperature nuclear reactors are used, direct CO 2 emissions can be divided in half. The technical feasibility of the system has been accessed with a brief parametric study here. The results suggest that the introduced system is technically feasible given the parameters (total heat transfer coefficients, mass-and volume flows, outer tube friction factors, and -Nusselt numbers) that are examined. Further experimental work will be required to better understand the performance of the tube-in-tube helical system for the flameless calcination of minerals.

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Section: Outer Tube Nusselt Numbersmentioning

confidence: 45%

“…The outer tube Nusselt numbers were determined using the correlations provided by Mandal and Nigam [59], Kumar et al [60], Guo et al [61], Rogers, and Mayhew [62], as well as El-Genk and Schriener [55]. The used correlations are provided in Table 3.…”

Section: Outer Tube Friction Factorsmentioning

confidence: 99%

Stop Smoking—Tube-In-Tube Helical System for Flameless Calcination of Minerals

2017

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“…Passive enhancements are achieved through combinations of surface and/or geometrical modifications, aiming to extend/enhance the heat transfer surface area, increase the flow swirling, and strengthen the secondary flow (e.g., changing surface roughness/coatings, extending surfaces/fins, inserting twisted-tape, bending, and twisting). Taking advantage of compact structure, manufacturing convenience, and superior fluid mixing that promotes heat transport, the helically coiled channels are widely applied for HX in various applications, including steam generators (El-Genk et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

“…1. Helically coiled tube HXs have been proven to be more efficient and compact (e.g., large heat transfer area per unit volume) when compared to most traditional HXs (El-Genk andSchiener, 2017, Farnam et al, 2021;Seara et al, 2014). However, there is still a strong need to enhance the heat transfer performance and increase the compactness of the helical tube HX technology beyond the existing capabilities.…”

Section: Introductionmentioning

confidence: 99%

Laminar Flow Heat Transfer in Helical Oval-Twisted Tube for Heat Exchanger Applications

Almasi‐Hashiani¹,

Wahlquist²,

Yoon³

et al. 2022

Frontiers in Heat and Mass Transfer

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The heat transfer performance of a novel tube configuration that combines the swirling velocity induced by oval-twisting and secondary flow generated by a helical geometrical flow path is presented. The Nusselt number (𝑁𝑢) and friction factor (𝑓) are compared for the laminar flow regime (𝑅𝑒 = 250-2000) under isothermal wall conditions. Under the same flow and boundary conditions, the oval-twisted helical tube increased the 𝑁𝑢 and slightly increased the 𝑓 over the circular helical tube. The best performance with the highest 𝑁𝑢 and lowest 𝑓 occurs at the coil curvature ratio (𝑑 ! /𝐷) of 0.17. The quantified enhancement performance factor (h) shows a 46 -56% increase for the oval-twisted helical tube over the circular helical tube with 𝑑 ! /𝐷 = 0.17. Correlations for the 𝑁𝑢 and 𝑓 are developed and agreed with the numerical results: ± 6% and ± 5% for the 𝑁𝑢 and 𝑓, respectively.

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“…The passive approach is widely investigated and utilized, because there is no need to add extra additives and energy. Various kinds of passively enhanced heat transfer tubes are developed to improve the heat transfer performance and limit the increase of pressure drop, for example, finned tube [1], coiled tube [2], corrugated tube [3], tube with insert [4]. Among the corrugated surface tube, the spirally corrugated tube (SCT) has received more attention, due to the streamlined surface and drag reduction effect by the spiral flow [5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Entropy Study on the Enhanced Heat Transfer Mechanism of the Coupling of Detached and Spiral Vortex Fields in Spirally Corrugated Tubes

Wang

Zhang

et al. 2020

Heat Transfer Engineering

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The present work numerically studied the enhanced heat transfer mechanism of the coupled fields of detached and spiral vortices in symmetrical and asymmetrical spirally corrugated tubes. The heat transfer and viscous dissipation were analyzed by evaluating the entropy combined with the flow patterns, and the global entropy generation rate was analyzed by considering the local Nusselt number and friction factor. The results indicated that, both the leeside and windward corrugation angles had obvious effects on the strength of detached vortex and spiral flow, and also the location of the vortex. The maximum values of the heat transfer entropy were located at the boundary layers, and the heat transfer entropy of the secondary flow region was more distinguished than in other parts of the main flow region. The maximum values of friction entropy generation were located at both the boundary layers and the core of detached vortex. The performance evaluation criterion (PEC) presents nearly the same values for the four cases, when the Reynolds number (Re) is less than 6,300. In addition, the PEC of symmetrical spirally corrugated tube with corrugation angle equal to 25 showed the best performance, when Re is greater than 6,300. To keep the PEC above 1, Re should not exceed 33,000.

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A Review and Correlations for Convection Heat Transfer and Pressure Losses in Toroidal and Helically Coiled Tubes

Cited by 51 publications

References 48 publications

Stop Smoking—Tube-In-Tube Helical System for Flameless Calcination of Minerals

Stop Smoking—Tube-In-Tube Helical System for Flameless Calcination of Minerals

Laminar Flow Heat Transfer in Helical Oval-Twisted Tube for Heat Exchanger Applications

Entropy Study on the Enhanced Heat Transfer Mechanism of the Coupling of Detached and Spiral Vortex Fields in Spirally Corrugated Tubes

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