Experimental study on natural convective heat transfer in a closed cavity

Zhan, N.Y.; Liu, Ding; Chai, Yimin; Wu, Junting; Xu, Yue

doi:10.1016/j.tsep.2018.11.009

Cited by 14 publications

(6 citation statements)

References 3 publications

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“…It also underlines that Nusselt-number functional forms according to von Karman analogy are neither accurate if the studied data points include high Prandlt numbers. Deviations beyond Pr= 10 were attributed to the assumption of a fixed boundary between this model sublayers, independent of Reynolds and Prandtl numbers [6][7][8]36].…”

Section: Variablesmentioning

confidence: 99%

“…In 1874 he related the heat and momentum transfer for turbulent flows in straight round pipes. Chilton and Colburn improved his postulates in 1934, by extending its applicability to fluids with Prandtl and Schmidt numbers different from the unity ≠ 1 and ≠ 1 [8,9]. This empirical adjustment to the original approach is often referenced as the Reynolds-Colburn analogy, which resulted in correlations with the mathematical structure of Eq.…”

Section: Introductionmentioning

confidence: 99%

“…The usage of a three-region model made the turbulent heat and mass transfer theory closer to the realistic flow conditions [13]. However, von Karman's analogy becomes progressively inaccurate as Pr and Sc increase beyond 30 [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

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Application of the ‘Nusselt-Equation Simulated Evolution Method’ in Forced Convective Heat Transfer Modeling

Sánchez-Escalona¹,

Camaraza-Medina²,

Retirado-Mediaceja³

et al. 2021

IJDNE

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Reliability of heat exchangers thermal analysis strongly depends on the equations selected to determine local convective heat transfer coefficients. Chosen analogy among momentum, heat and mass transfer also plays a remarkable role. Within this context, the aim of the study was to validate a novel approach to obtain mean forced convective film coefficients under single-phase non-laminar fluid flow conditions, inside tubes. It relied on a comprehensive Nusselt-number equation that is able to evolve into different functional forms according to Reynolds-Colburn, Prandtl and von Karman analogies. Parameters estimation was carried out through Genetic Algorithms. Applied experimental database was numerically obtained by Taler by solving the energy conservation equation for fully developed turbulent flow in tubes with constant wall heat flux. Application of the method provided a new correlation, valid for 0.1 ≤ ≤ 10 3 and 3 × 10 3 ≤ ≤ 10 6 . Besides attaining a better fit to the experimental data as compared to benchmark expressions, it correlated very well with the results of reference models (Skupinski, Seban & Shimazaki, Gnielinski, Camaraza-Medina, Petukhov, and Sandall). The first assessment provided mean and maximum relative errors of 2.41% and 19.45%, respectively, while the second comparison resulted in deviations over the Nusselt number up to 20% in 92.59% of the data points. The implemented solution overcomes the drawbacks of non-linear and symbolic regression methods by allowing evolution of the regression function within a controlled mathematical environment. Future model improvements should investigate different fitting-intervals along with higher turbulence regions.

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Section: Variablesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Application of the ‘Nusselt-Equation Simulated Evolution Method’ in Forced Convective Heat Transfer Modeling

Sánchez-Escalona¹,

Camaraza-Medina²,

Retirado-Mediaceja³

et al. 2021

IJDNE

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“…Authors observed the development of flow structures within the cavity with a growth of the cavity inclination angle (0 ≤ γ ≤ π/2) and the Rayleigh number (10 4 ≤ Ra ≤ 10 5 ). Another interesting experimental study (Zhan et al , 2019) was devoted to natural convection inside a chamber with local heaters.…”

Section: Introductionmentioning

confidence: 99%

Natural convection in differentially heated enclosures subjected to variable temperature boundaries

Mohamad

Sheremet

Taler

et al. 2019

HFF

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Purpose Natural convection in differentially heated enclosures has been extensively investigated due to its importance in many industrial applications and has been used as a benchmark solution for testing numerical schemes. However, most of the published works considered uniform heating and cooling of the vertical boundaries. This paper aims to examine non-uniform heating and cooling of the mentioned boundaries. The mentioned case is very common in many electronic cooling devices, thermal storage systems, energy managements in buildings, material processing, etc. Design/methodology/approach Four cases are considered, the left-hand wall’s temperature linearly decreases along the wall, while the right-hand wall’s temperature is kept at a constant, cold temperature. In the second case, the left-hand wall’s temperature linearly increases along the wall, while the right-hand wall’s temperature is kept a constant, cold temperature. The third case, the left-hand wall’s temperature linearly decreases along the wall, while the right-hand wall’s temperature linearly increases along the wall. In the fourth case, the left-hand and the right-hand walls’ temperatures decrease along the wall, symmetry condition. Hence, four scenarios of natural convection in enclosures were covered. Findings It has been found that the average Nusselt number of the mentioned cases is less than the average Nusselt number of the uniformly heated and cooled enclosure, which reflects the physics of the problem. The work quantifies the deficiency in the rate of the heat transfer. Interestingly one of the mentioned cases showed two counter-rotating horizontal circulations. Such a flow structure can be considered for passively, highly controlled mechanism for species mixing processes application. Originality/value Previous works assumed that the vertical boundary is subjected to a constant temperature or to a sinusoidal varying temperature. The subject of the work is to examine the effect of non-uniformly heating and/or cooling vertical boundaries on the rate of heat transfer and flow structure for natural convection in a square enclosure. The temperature either linearly increases or decreases along the vertical coordinate at the boundary. Four scenarios are explored.

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“…Thus, the study of the behavior of different fluids in the latter has been the center of many experimental, theoretical or numerical investigations. Therefore, the wide application domains of natural convection heat transfer and the absence of analytical solutions to the equations that model this phenomenon require a good knowledge of numerical resolution processes [5]. In order to better understand the physical phenomena that come into play, many geometry models or fluid types have been used in previous research [6] [7] [8] [9] [10].…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of the Natural Convection in a Tunnel Whose Floor Has a Variable Sinusoid with a Roof Opening

Drame¹,

Mbow²,

Bode³

2019

OJFD

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A two-dimensional numerical study of natural convection in a tunnel whose plane is sinusoidal with an opening on the horizontal ceiling is presented. In this work, we study the thermoconvective instabilities of air in a tunnel closed at both ends and heated by the floor. The study was carried out for different cases of geometry by varying the thickness of the sinusoid and the height of the tunnel. In order to create a transverse movement of the air, we heated the floor to the temperature f T and kept the horizontal ceiling at the temperature g T such that g f T T < . This work has a lot of scope of application ranging from geothermal flow to the civil engineering like ventilation in the case of tunnels and thermal comfort of buildings. The Navier Stokes equations that model this problem have been solved using the numerical method with simplifying assumptions such as the Boussinesq hypothesis. And finally an interpretation of the results of the simulations has been made taking into account the variation of the form factors such as the amplitude of the sinusoid for Rayleigh number 4 6 2 10 7 10 a R × ≤ ≤ × and Prendtl number P r = 0.71.

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Experimental study on natural convective heat transfer in a closed cavity

Cited by 14 publications

References 3 publications

Application of the ‘Nusselt-Equation Simulated Evolution Method’ in Forced Convective Heat Transfer Modeling

Application of the ‘Nusselt-Equation Simulated Evolution Method’ in Forced Convective Heat Transfer Modeling

Natural convection in differentially heated enclosures subjected to variable temperature boundaries

Numerical Simulation of the Natural Convection in a Tunnel Whose Floor Has a Variable Sinusoid with a Roof Opening

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