Numerical and experimental evaluation of heat transfer in helically corrugated tubes

Cauwenberge, David J. Van; Dedeyne, Jens; Marin, Guy; Floré, Jens

doi:10.1002/aic.16038

Cited by 21 publications

(18 citation statements)

References 46 publications

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“…The focus of this work is not on 3D reactor technologies or feed additives. For the former, many recent developments − have limited the negative impact of the resulting pressure drop increase, while for the latter, mostly dimethyl disulfide (DMDS) is used. The reactor material is thus one of the most important factors, maybe the most important factor, that determines coke formation.…”

Section: Introductionmentioning

confidence: 99%

State-of-the-art of Coke Formation during Steam Cracking: Anti-Coking Surface Technologies

Symoens

Olahová

Gandarillas³

et al. 2018

Ind. Eng. Chem. Res.

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Although steam cracking is a mature technology, mitigation of coke formation remains one of the main challenges in the petrochemical industry. To increase the olefin output of existing plants, coil materials that can withstand higher temperatures are desired. This work reviews material technologies that were developed and tested in the past three decades to minimize the rate of coke deposition and extend the furnace run length. The material not only determines the mechanical properties of the coil but also affects the coking rate substantially. In some cases, differences in coking rates by more than a factor 10 have been observed. SiC materials could be operated at significantly higher temperatures, and this leads to higher olefin selectivity if one includes acetylene hydrogenation; however, the mechanical joints make it currently impossible to take advantage of their superior temperature resistance. On the industrial scale, operational improvements have been reported with advanced reactor surface technologies such as high-performance alloys and coatings during the past decade. Catalytic coatings go a step further than barrier coatings by actively removing coke that is deposited on the coils. Another trend is to add aluminum to the coil material, which forms a protective aluminum oxide layer on the reactor wall during operation and results in reduced carburization. To optimize the coking mitigation capabilities of the coils, the state-of-the-art materials and/or coatings should be combined with 3D reactor technologies, which is not always possible for all materials because of the advanced machining that is needed.

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Section: Introductionmentioning

confidence: 99%

State-of-the-art of Coke Formation during Steam Cracking: Anti-Coking Surface Technologies

Symoens

Olahová

Gandarillas³

et al. 2018

Ind. Eng. Chem. Res.

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“…This shows that the ribs are closely spaced in comparison to the geometry in Campet et al 16 and Cauwenberge. 13 It should be noted that the pitch-to-ration ratio is 11.9 times smaller than for the structure used in this article. With measurements of mass flow rates and inlet and outlet temperatures, the overall heat transfer coefficient can be obtained.…”

Section: Numerical Methodology and Geometrymentioning

confidence: 85%

“…The results of his study demonstrate that the performance of the helically corrugated pipe is superior to the transverse corrugated pipe. In the work by Campet et al 16 LES have been performed at the same geometry investigated by Cauwenberg et al 13 The results were validated using measurement results including velocity profiles and wall temperatures by Mayo et al 17 The comparison shows that the simulations agree well with the measurements for both velocity and temperature. The authors observed that the heat transfer is 2.3 times higher than in a smooth pipe.…”

Section: Introductionmentioning

confidence: 78%

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Investigation of heat transfer and pressure drop for a multiple‐started ribbed pipe using large‐eddy simulation

et al. 2022

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Turbulent heat transport phenomena in multiple‐started helically ribbed pipes are investigated. Such structures are applied to enhance heat transfer in various technical systems. A large‐eddy simulation (LES) approach is used to model the turbulent flow field. The simulation results for heat transfer and pressure loss are in good agreement with available experimental data and the simulation model is successfully validated for complex surface geometries. For a better understanding of the impact of the wall structures on the turbulent transport processes, local profiles of the relevant flow variables values are investigated. Thus, the specific mechanism of the heat transfer enhancement can be explained and a knowledge‐based optimization of innovative structures is possible.

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“…A number of passive heat transfer enhancement techniques have been developed with different insert designs which enhance convective heat transfer due to the generation of the swirling effect or diffusion . Heat transfer enhancement has successfully been demonstrated due to swirl, but the problem of dead zones has not yet been completely overcome for compact designs. , The proposed threaded design does not exhibit any dead zones and thereby can ensure a minimum spatial variation of temperature (on a plane normal to the axis of the mixer) as is observed within the dead zones. A detailed computational study has been carried out over different designs of inserts for evaluating their heat transfer capabilities and has been compared with straight pipe and unthreaded inserts.…”

Section: Resultsmentioning

confidence: 99%

Passive Mixer cum Reactor Using Threaded Inserts: Investigations of Flow, Mixing, and Heat Transfer Characteristics

Khalde

Ramanan

Sangwai

et al. 2019

Ind. Eng. Chem. Res.

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Significant efforts have been and are being spent on developing intensified tubular reactors for continuous manufacturing of fine and specialty chemicals. In this work, we have proposed a new design of passive mixer-cum-reactor for process intensification and development of continuous processes. The mixer/reactor consists of threaded inserts with cone-shaped ends, placed concentrically in the tube such that fluid flows through the annular region between the inserts and the tube. The proposed design is easy to fabricate, maintain, and overcomes the limitations of scale up/scale down compared to most of the commercial passive mixers. The split and recombine of flow around inserts, the swirling effect generated by threads, change in the swirl direction due to change in the direction of screw threads, and pinching effect/expansion at the cone-cone shaped ends realize desired enhancements in mixing and heat transfer. A detailed computational study has been carried out on the mixer-cum-reactor to characterize flow, mixing and heat transfer at different operating conditions using a verified and validated CFD model. Various designs and configurations of threaded inserts were considered: 5-channel, 7-channel and 9-channel, smooth surface (no threading) and smooth surface-extended rear end inserts. The flow, mixing and heat transfer were characterized over the Reynolds number range of 100 to 1600. Structure of the generated swirling flow, effect of pinching/expansion, direction reversal of flow, tracer fraction, temperature and path lines were investigated systematically to gain new insights. Threaded inserts could achieve excellent mixing (>99 % of mixing intensity) and heat transfer (7 times smooth inserts and 20 times without inserts). The presented results will provide a sound basis for selecting appropriate threaded inserts for intensifying mixing and heat transfer in tubular reactors. The work also provides a useful starting point for further work on multiphase flows in a tubular reactor with threaded inserts.

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Numerical and experimental evaluation of heat transfer in helically corrugated tubes

Cited by 21 publications

References 46 publications

State-of-the-art of Coke Formation during Steam Cracking: Anti-Coking Surface Technologies

State-of-the-art of Coke Formation during Steam Cracking: Anti-Coking Surface Technologies

Investigation of heat transfer and pressure drop for a multiple‐started ribbed pipe using large‐eddy simulation

Passive Mixer cum Reactor Using Threaded Inserts: Investigations of Flow, Mixing, and Heat Transfer Characteristics

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