Heat transfer deterioration mechanism for water at supercritical pressure

El-Morshedy, Salah El-Din; Ibrahim, Said M.A.; Alyan, Adel; Abdelmaksoud, Abdelfatah

doi:10.1016/j.ijft.2020.100020

Cited by 5 publications

(1 citation statement)

References 16 publications

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“…This deterioration may be the result of a significant density variation near the critical point that deforms the velocity profile, flagging the turbulence [5], or even due to the thickening of the viscous underlayer depending on the fluid flow rate [40]. Many research works, mainly performed numerically, have been published on this phenomenon, known as heat transfer deterioration (HTD) [41][42][43][44][45][46][47]. Recently, Wang et al [48] obtained, by simulation, that semicircular heating decreased the degree of HTD due to the greater turbulence produced by the greater density difference between the heating side and the adiabatic side.…”

Section: Heat Transfer Deterioration In Scwg Experimentsmentioning

confidence: 99%

Heat Transfer Limitations in Supercritical Water Gasification

et al. 2021

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Supercritical water gasification (SCWG) is a promising technology for the valorization of wet biomass with a high-water content, which has attracted increasing interest. Many experimental studies have been carried out using conventional heating equipment at lab scale, where researchers try to obtain insight into the process. However, heat transfer from the energy source to the fluid stream entering the reactor may be ineffective, so slow heating occurs that produces a series of undesirable reactions, especially char formation and tar formation. This paper reviews the limitations due to different factors affecting heat transfer, such as low Reynolds numbers or laminar flow regimes, unknown real fluid temperature as this is usually measured on the tubing surface, the strong change in physical properties of water from subcritical to supercritical that boosts a deterioration in heat transfer, and the insufficient mixing, among others. In addition, some troubleshooting and new perspectives in the design of efficient and effective devices are described and proposed to enhance heat transfer, which is an essential aspect in the experimental studies of SCWG to move it forward to a larger scale.

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