Experimental investigation of natural convection flow in a laterally heated vertical cylindrical enclosure

Moldovan, Stefan I.; Balasoiu, Ana M.; Braun, M. J.

doi:10.1016/j.ijheatmasstransfer.2019.05.012

Cited by 5 publications

(6 citation statements)

References 14 publications

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Section: Approaches To Validationmentioning

confidence: 99%

“…Enayati et al [31] and Moldovan et al [28] presented an interesting approach of validation via the design of a geometrically and dynamically similar experimental setup that allows for particle image velocimetry-based flow visualizations and thus yields actual flow fields. Moldovan et al found the flow to be oscillatory in nature but with steady time-averaged patterns [28]. They used the standard deviation of fluid temperatures to assess the magnitude of fluctuations at different locations, and found the fluctuations to be most pronounced in the mixing region between the hot and cold sections [28].…”

Section: Approaches To Validationmentioning

confidence: 99%

“…Therefore, numerical modeling is an important tool for clarifying the actual experimental conditions such as temperature distribution and flow field inside the autoclave. A number of research groups have conducted numerical studies of temperature and flow field [25][26][27][28], partially including further aspects such as the concentration of metastable intermediates [29] and growth rates [29,30]. However, critical issues have not been studied thoroughly in the literature, and validation has been applied only to an extremely limited extent.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, the accuracy of such numerical results remains unclear, preventing simulations from delivering their full potential impact on further development and use of the ammonothermal method for bulk crystal growth. Moreover, it should be noted that natural convection in cylindrical enclosures with laterally heated walls in general is not well studied to date [28,31].…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Numerical Simulation of Ammonothermal Crystal Growth of GaN—Current State, Challenges, and Prospects

et al. 2021

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Numerical simulations are a valuable tool for the design and optimization of crystal growth processes because experimental investigations are expensive and access to internal parameters is limited. These technical limitations are particularly large for ammonothermal growth of bulk GaN, an important semiconductor material. This review presents an overview of the literature on simulations targeting ammonothermal growth of GaN. Approaches for validation are also reviewed, and an overview of available methods and data is given. Fluid flow is likely in the transitional range between laminar and turbulent; however, the time-averaged flow patterns likely tend to be stable. Thermal boundary conditions both in experimental and numerical research deserve more detailed evaluation, especially when designing numerical or physical models of the ammonothermal growth system. A key source of uncertainty for calculations is fluid properties under the specific conditions. This originates from their importance not only in numerical simulations but also in designing similar physical model systems and in guiding the selection of the flow model. Due to the various sources of uncertainty, a closer integration of numerical modeling, physical modeling, and the use of measurements under ammonothermal process conditions appear to be necessary for developing numerical models of defined accuracy.

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Section: Approaches To Validationmentioning

confidence: 99%

Section: Approaches To Validationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Numerical Simulation of Ammonothermal Crystal Growth of GaN—Current State, Challenges, and Prospects

et al. 2021

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“…Moldovan et al [11] experimentally investigated the natural convection flow in an annularly heated vertical cylinder. The work was focused on measuring the flow temperatures and velocities in a crystal grow reactor equivalent setup.…”

Section: Introductionmentioning

confidence: 99%

Transient Natural Convection in a Thermally Insulated Annular Cylinder Exposed to a High Temperature from the Inner Radius

2020

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Extensive numerical analysis was performed for the unsteady state, natural convection in the annular cylinders. The cylinder’s boundaries were thermally insulated, except the inner surface. The fluid (water) in the cylinder initially was assumed at a cold temperature while the inner surface was subjected to a high temperature. The time history for the heat transfer by diffusion and advection was studied. The time needed for fully charging the storage tank and rate of heat transfer was calculated. The predicted results were compared with the pure heat diffusion process and with a steady-state convection system. Therefore, CFD simulations were performed for natural convection in the storage tank. The main objective of this study was to establish correlations for the rate of heat transfer as a function of time and other controlling parameters. The correlation is needed in designing a thermal energy storage system for domestic and industrial heating processes. One of the drawbacks of the conventional thermal storage systems is the slow charging and discharging, where the heat transfer is mainly diffusion dominated. To overcome such a problem, a system was designed based on the natural convective heat transfer mechanism. Therefore, the heat transfer and fluid flow in a cylindrical storage tank were simulated for a range of Rayleigh numbers (104 to 108) and radius ratio. It was found that a convection-operated storage tank reduces the thermal charging process time drastically compared with the thermally diffusion charging process. The rate of reduction in the charging time mainly depends on the rate of heating and geometric parameter of the tank. To the best of the authors’ knowledge, the work is novel.

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Critical role of Prandtl number on multiple steady states during natural convection in square enclosures: Analysis of heat transfer rates, flow and thermal maps

Bhattacharya

Basak

2021

International Journal of Heat and Mass Transfer

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Experimental investigation of natural convection flow in a laterally heated vertical cylindrical enclosure

Cited by 5 publications

References 14 publications

Numerical Simulation of Ammonothermal Crystal Growth of GaN—Current State, Challenges, and Prospects

Numerical Simulation of Ammonothermal Crystal Growth of GaN—Current State, Challenges, and Prospects

Transient Natural Convection in a Thermally Insulated Annular Cylinder Exposed to a High Temperature from the Inner Radius

Critical role of Prandtl number on multiple steady states during natural convection in square enclosures: Analysis of heat transfer rates, flow and thermal maps

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