Evaluation of Reaeration by Convective Heat Transfer Coefficient

Gonçalves, Julio Cesar de Souza Inácio; Silveira, Alexandre; Júnior, Guilherme Barbosa Lopes; Luz, M. S. da; Giorgetti, Marcius F.

doi:10.1061/(asce)ee.1943-7870.0001308

Cited by 4 publications

(6 citation statements)

References 19 publications

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“…The water temperature throughout each single experiment has varied at most 0.5°C. In surface (long‐term) reaeration experiments, this temperature range is common 3,5 . We believe there is no need for testing at different temperatures because the relation between K L a and temperature has already been studied.…”

Section: Methodsmentioning

confidence: 99%

“…The parameters that control the oxygen mass transfer in water have been intensively investigated since the middle of the last century 1‐9 . In general, this interest is because the oxygen mass transfer (or reaeration) is the main source for the restoration of dissolved oxygen concentration in polluted water 6 .…”

Section: Introductionmentioning

confidence: 99%

“…Based on this, theoretical considerations and experimental investigations have been used to improve the K L a estimation, which resulted in the development of new measurement techniques and new theoretical and semi‐empirical equations. One of them, Gonçalves et al, 5 reported a new technique in which K L a can be estimated from the convective heat‐transfer coefficient (h), using an aluminum or copper thermal probe. The same group found a new empirical equation to predict K L a 3 .…”

Section: Introductionmentioning

confidence: 99%

“…Szeliga and Roma 40 found an empirical equation that relates K L a with the interfacial turbulence, represented by the vertical turbulent velocity. Other recent works have been performed with similar experimental setups for the study of dissolution of atmospheric gases into water in the presence of turbulence 5,6,41 …”

Section: Introductionmentioning

confidence: 99%

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Humic substances reduce the oxygen mass transfer in the air–water interface

et al. 2020

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The aim of this study was to investigate the influence of humic substances (HS) on volumetric oxygen-transfer coefficient (K L a) under different turbulence intensities at the air-water interface. The experiments were carried out in an oscillating grid tank which provided three levels of turbulence intensities (Reynolds numbers of 5,116, 10,316, and 15,433). For each turbulence level, 15 different HS concentrations were tested and the K L a was estimated. The results showed that, regardless of the turbulence level in the tank, HS reduces K L a. The maximum reduction was 17%. The barrier effect, produced by the occupation of HS molecules at the interface, was the main phenomenon responsible for the reduction in the oxygen transfer. A relationship between the oxygen transfer velocity and turbulent kinetic energy showed that in the presence of HS, the air-water interface behaves like an immobile surface, reducing the oxygen diffusion and surface renewal.gas-water interface, grid-stirred tank, humic substances, oxygen mass transfer, reaeration

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Humic substances reduce the oxygen mass transfer in the air–water interface

et al. 2020

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“…Essa técnica se baseia no fato que K L pode ser correlacionado com a velocidade de dissolução do sólido solúvel (V S ), uma vez que ambos os parâmetros são influenciados pela turbulência na superfície do escoamento. QUEIROZ; MATOS; VON SPERLING, 2015;MARADEI et al, 2015;GONÇALVES et al, 2018).…”

Section: Introductionunclassified

Estimativa do coeficiente de transferência de massa de oxigênio com o uso da técnica das sondas solúveis flutuantes: um estudo de laboratório

Ferreira

Oliveira

Urzêdo

et al. 2019

Eng. Sanit. Ambient.

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RESUMO A sonda solúvel flutuante (SSF) é considerada uma técnica de baixo custo para a estimativa do coeficiente de transferência de massa de oxigênio na interface ar-água (KL). Essa técnica se baseia no fato que KL pode ser correlacionado com a velocidade de dissolução do sólido solúvel (VS), uma vez que ambos os parâmetros são influenciados pela turbulência na superfície do escoamento. O objetivo do presente estudo consistiu em calibrar uma nova configuração da SSF. Experimentos de reaeração superficial e dissolução da sonda solúvel foram realizados em dois aparatos experimentais (tanque agitado por jatos e um canal hidráulico circular), de modo que diferentes níveis de turbulência foram produzidos. Os resultados mostraram forte correlação entre KL e VS; r = 0,953 para experimentos realizados no tanque e r = 0,895 para experimentos realizados no canal. A nova configuração da SSF forneceu razão KL.VS -1 crescente em função do número de Reynolds, indicando que a relação entre os dois parâmetros é dependente da turbulência. Conclui-se que a técnica SSF possui elevado potencial. Entretanto, para que se possa atribuir utilidade definitiva, verificações em cursos d’água naturais e em equipamentos com estrutura de turbulência diferentes das utilizadas neste estudo ainda são necessárias.

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