A brief review on frictional pressure drop reduction studies for laminar and turbulent flow in helically coiled tubes

Fsadni, Andrew; Whitty, Justin; Stables, M. A.

doi:10.1016/j.applthermaleng.2016.08.068

Cited by 28 publications

(7 citation statements)

References 42 publications

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“…In the knowledge of the Authors, no published research is available that investigates the effect of micro‐bubble size on DR in curved pipes. There is therefore need for more research to enhance understanding of any possible effect of micro‐bubble size on DR 132 . In the application of micro‐bubbles as DRAs for straight channel flow, conflicting reports exist on its effect on DR.…”

Section: Effect Of Polymer and Surfactant Drag‐reducing Agents On Sinmentioning

confidence: 99%

A review of drag reduction by additives in curved pipes for single‐phase liquid and two‐phase flows

Ayegba

Edomwonyi‐Otu

Yusuf

et al. 2020

Engineering Reports

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The effect of drag‐reducing agents (DRAs) on fluid flows in straight pipes has been well documented. Key among these is the effect of DRAs on turbulence statistics (Reynolds shear stress, turbulence intensity, streamwise and wall‐normal velocity fluctuation among others). These primary effects result in secondary effects such as modification of mean velocity profile and reduction in frictional losses (drag reduction, DR). Interestingly, in curved pipe flows, the characteristic of flow is more complex due to secondary flow, wake effects and under‐developed flow characteristics. Therefore, a review of investigations on the effect of DRAs in curved pipe flows is presented in this paper. The paper highlights the difference between DR in straight and curved conduits as well as the interaction between DRAs and flow characteristics of curved pipe flows. Proposed mechanisms of DR, and factors that influence their effectiveness also received attention. It was shown that significant DR can be achieved in curved pipes. A review of various experimental results revealed that DR by additives in curved pipes is generally lower than in straight pipes but with certain similarities. It decreases with increase in curvature ratio and is more pronounced in the transition and turbulent flow regimes. Maximum DR asymptote differed between straight and curved pipes and between polymer and surfactant. Due to the limited studies in the area of DR for gas‐liquid flow in curved pipes, no definite conclusion could be drawn on the effect of DRAs on such flows. A number of questions remain such as physical interaction between molecules of DRA and flow features such as secondary flow streamlines and wakes. Hence, some research gaps have been identified with recommendations for areas of future researches.

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Section: Effect Of Polymer and Surfactant Drag‐reducing Agents On Sinmentioning

confidence: 99%

A review of drag reduction by additives in curved pipes for single‐phase liquid and two‐phase flows

Ayegba

Edomwonyi‐Otu

Yusuf

et al. 2020

Engineering Reports

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“…Helically coiled tubes are used in numerous industries and processes due to their superior flow mixing characteristics and compact design (Fsadni et al , 2016). Fluid flow through a helical tube is three dimensional as opposed to two-dimensional flow in straight tubes, thus enhancing flow mixing (Patankar and Pratap, 1974).…”

Section: Receiver Designmentioning

confidence: 99%

Numerical analysis of a hybrid tubular and cavity air receiver for solar thermal applications

Sasidharan

Dutta

2020

HFF

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Purpose This paper aims to deal with characterisation of the thermal performance of a hybrid tubular and cavity solar thermal receiver. Design/methodology/approach The coupled optical-flow-thermal analysis is carried out on the proposed receiver design. Modelling is performed in two and three dimensions for estimating heat loss by natural convection for an upward-facing cavity. Heat loss obtained in two dimensions by solving coupled continuity, momentum and energy equation inside the cavity domain is compared with the loss obtained using an established Nusselt number correlation for realistic receiver performance prediction. Findings It is found that radiation emission from a heated cavity wall to the ambient is the dominant mode of heat loss from the receiver. The findings recommend that fluid flow path must be designed adjacent to the surface exposed to irradiation of concentrated flux to limit conduction heat loss. Research limitations/implications On-sun experimental tests need to be performed to validate the numerical study. Practical implications Numerical analysis of receivers provides guidelines for effective and efficient solar thermal receiver design. Social implications Pressurised air receivers designed from this method can be integrated with Brayton cycles using air or supercritical carbon-dioxide to run a turbine generating electricity using a solar heat source. Originality/value The present paper proposes a novel method for coupling the flux map from ray-tracing analysis and using it as a heat flux boundary condition for performing coupled flow and heat transfer analysis. This is achieved using affine transformation implemented using extrusion coupling tool from COMSOL Multiphysics software package. Cavity surface natural convection heat transfer coefficient is obtained locally based on the surface temperature distribution.

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“…Therefore, an attempt to gain deep insight into DR in curved pipes to improve the economics of pipeline design and operation cannot be overemphasized. Beside a brief study of pressure drop reduction in helical coils carried out by [28], we are not aware of any other reviews pertaining to drag reduction in curved pipes. Hence this work is devoted to the review of existing research on single and two-phase drag reduction for flows through curved pipes.…”

Section: Dr(%) =mentioning

confidence: 99%

“…Based on the knowledge of the authors, no published research is available that investigates the effect of micro-bubble size on DR in curved pipes. There is therefore need for more research to enhance understanding of any possible effect of micro-bubble size on DR [28]. In the application of micro-bubbles as drag-reducing agents for straight channel flow, conflicting reports exist on its effect on DR.…”

Section: Effect Of Micro-bubble Sizementioning

confidence: 99%

Drag Reduction by Additives in Curved Pipes for Single-Phase Liquid and Two-Phase Flows: A Review

Ayegba¹,

Edomwonyi‐Otu²,

Abubakar³

et al. 2020

Preprint

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A review of influence of drag-reducing agents on curved pipe flows is presented in this work. In addition, this review outlined proposed mechanism, friction factor and fluid flux models for drag-reducing agents in curved pipe flows. Our finding reveals that drag reduction by additives in curved pipes is quite significant but generally lower than the corresponding drag reduction in straight pipes. It decreases with increase in curvature ratio and more pronounced in the transition and turbulent flow regimes. Drag reduction strongly depends on the polymers and surfactants' concentrations as well as the bubble fraction of micro-bubbles. It is also reported that drag reduction in curved pipes depends on temperature and existence of dissolved salts in the fluids. Maximum drag reduction asymptote differed between straight and curved pipes and between polymer and surfactant. No definite conclusion could be drawn as regards drag reduction for two-phase flow in curved pipes due to the limited studies in this area. Many questions such as the mechanism of drag reduction in curved pipes and how drag-reducing agents interact with secondary flows still remained unanswered. Hence, some research gaps have been identified with recommendations for areas of future researches.

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A brief review on frictional pressure drop reduction studies for laminar and turbulent flow in helically coiled tubes

Cited by 28 publications

References 42 publications

A review of drag reduction by additives in curved pipes for single‐phase liquid and two‐phase flows

A review of drag reduction by additives in curved pipes for single‐phase liquid and two‐phase flows

Numerical analysis of a hybrid tubular and cavity air receiver for solar thermal applications

Drag Reduction by Additives in Curved Pipes for Single-Phase Liquid and Two-Phase Flows: A Review

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