ONB, OSV, and OFI for subcooled flow boiling through a narrow rectangular channel heated on one-side

Al-Yahia, Omar S.; Jo, Daeseong

doi:10.1016/j.ijheatmasstransfer.2017.09.011

Cited by 42 publications

(2 citation statements)

References 28 publications

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“…They found that the Nusselt number (Nu) had an effect on the OFI and correlated it. Al-Yahia and Jo [22] experimentally found that pressure affects the OFI and presented their new OFI correlation by modifying the Wang correlation and adding a pressure term. The mentioned subcooled flow-boiling OFI correlations are presented in table 2.…”

Section: Introductionmentioning

confidence: 99%

Onset of flow instability with one-side heated swirl tube for fusion reactor safety

Lim

Lee

et al. 2021

Nucl. Fusion

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In this study, the onset of flow instability (OFI) heat flux of a one-side heated swirl tube is experimentally investigated. The OFI heat flux means the minimum heat flux that can cause flow instability by the vapor generated in the flow path. An analysis of the effect of system parameters on the OFI heat flux indicates that as the pressure increases, the bubble size decreases. Therefore, the void fraction decreases and, consequently, the OFI heat flux tends to increase. Similarly, the higher the flow rate and degree of subcooling, the faster the vapor can be removed; thus, the OFI heat flux increases. In addition, the prediction performances of the existing OFI correlations developed under the subcooled flow-boiling condition are evaluated. Therefore, although the Wang correlation indicates the lowest error rate, it yields a high mean absolute error rate of 87.75%. Thus, it is difficult to predict the OFI heat flux of a one-side heated swirl tube using the existing OFI correlations. Therefore, in this study, a new correlation is developed using a Python code created by employing an artificial intelligence regression method. The developed correlation incorporates the impact of one-side heating, swirl tape, mass flow rate, subcooling, and pressure (mean absolute error = 12.17%, root mean square error = 14.99%).

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Section: Introductionmentioning

confidence: 99%

Onset of flow instability with one-side heated swirl tube for fusion reactor safety

Lim

Lee

et al. 2021

Nucl. Fusion

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show abstract

“…Subsequently, Wang et al [19] investigated the OFI in a narrow rectangular channel under one-side heating condition, and developed a modified Kennedy OFI correlation that reflected the effect of one-side heating through the ratio of P w and P h as shown in (7); here, P w and P h are the mean wetted perimeter and heated perimeter, respectively. Al-Yahia et al [20] reflected the influence of pressure on OFI, and proposed a new R factor as given by (8).…”

Section: Introductionmentioning

confidence: 99%

Experimental study of thermal limits with one-side heated smooth channel for plasma facing component safety

Lim

Park

2021

Eng. Res. Express

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In order to stably operate the equipment inside the tokamak, which is loaded with a heat flux of several MW/m2 under the one-side heating condition, it is necessary to thoroughly prepare for various thermal engineering limits that may occur under the high heat flux load condition. In this study, we have experimentally explored critical heat flux (CHF) and onset of flow instability (OFI), which are considered potential threats in a DEMO fusion power plant. Specifically, the effect of system parameters on CHF was investigated. The results indicate that with an increase in subcooling and mass flux, the CHF increased, as it induced a faster bubble condensation near the CHF. As the system pressure increased, the CHF also increased. This is because the bubble size reduction effect was dominant in the pressure range of 1–10 bar. Most of the existing CHF correlations could evaluate the CHF with reasonable accuracy of within 25%; especially, the Boscary CHF correlation yielded the highest accuracy with an average error of 12%. Similar to CHF, OFI, which is a measure of the sudden fluctuations in the system pressure caused by a large amount of vapor generated due to the high heat flux, tended to increase as the subcooling, mass flow rate, and system pressure increased. Most of the existing OFI correlations yielded large error rates (more than 135%) as these correlations were primarily developed for micro-channels. Therefore, in this study, a new OFI correlation was developed using a Python code, in combination with an artificial intelligence (AI) regression method. The developed correlation can be used in the cooling system design of tokamaks, which involve a high-heat load condition on one-side of the reactor.

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Forced Convection Subcooled Boiling

2021

Two‐Phase Heat Transfer

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ONB, OSV, and OFI for subcooled flow boiling through a narrow rectangular channel heated on one-side

Cited by 42 publications

References 28 publications

Onset of flow instability with one-side heated swirl tube for fusion reactor safety

Onset of flow instability with one-side heated swirl tube for fusion reactor safety

Experimental study of thermal limits with one-side heated smooth channel for plasma facing component safety

Forced Convection Subcooled Boiling

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