Experimental investigation of heat transfer by unsteady natural convection at a vertical flat plate

Schaub, Michael; Kriegel, Martin; Brandt, Stefan

doi:10.1016/j.ijheatmasstransfer.2019.03.089

Cited by 17 publications

(6 citation statements)

References 32 publications

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“…Similar experimental study on natural convection has been conducted for copper and steel plates, which concludes that there is no significant dependence of the Nusselt number (Nu) with respect to aspect ratio of the plate [10]. Schaub et al [11] perform experimental investigation of unsteady natural convection at a vertical flat plate. Subsequently, the experimental results have been used to develop an analytical model that can predict unsteady natural convection at vertical flat plate [12].…”

Section: Introductionmentioning

confidence: 76%

Investigation of the effect of different materials on convective heat transfer

Ibrahim¹,

Chong²,

Rajasekharan³

et al. 2020

JMES

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Conventionally, the study of convection heat transfer merely focuses on the behavior of air flow without considering the conductive effect of the horizontal flat plate. However, it is expected that the conductive effect of the horizontal plate somewhat affects the air flow temperature across the flat plate. Therefore, it is motivated to study the variation of air flow temperature across different materials of flat plate in various time frame. The materials used in this study are aluminium, stainless steel and cast iron. Infrared camera and FloEFD simulation software are used to measure the upper surface temperature of the flat plate. For forced convection, the study is carried out within the range of 103 £ Re £ 104 and within the range of 1 × 107 £ Ra < 2.2 × 107 for natural convection. Flow velocity of 2.3 m/s, 4.1 m/s and 5.2 m/s are used for the forced convection. The results showed that aluminium plate cools down faster than the other two metal plates used in all scenarios. Stainless steel’s temperature goes down faster compared to cast iron. These results were supported by the fact that aluminium has higher heat transfer rate of other metals. For forced convection, the discrepancies of temperatures between experimental and simulation studies are below 10%, which demonstrates that the results are reasonably acceptable. For natural convection, even though the discrepancies between simulation and experimental results on temperature variations are relatively large, the temperatures varied in similar pattern. This indicates that the results are reliable.

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Section: Introductionmentioning

confidence: 76%

Investigation of the effect of different materials on convective heat transfer

Ibrahim¹,

Chong²,

Rajasekharan³

et al. 2020

JMES

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“…10 6 -8 . 10 8 ), (40) This dependence is 5.8% less than (20), but because it was obtained as a result of experimental studies carried out in a similar way and on the same heating plate, we decided to use it to validate the correctness of the solution. Detailed calculations of this validation can be found in the study [78].…”

Section: The Study Of Radiative-convective Heat Transfer In Airmentioning

confidence: 99%

“…In order to eliminate the effects of radiation in experimental convection studies, some researchers took various approaches, performing experiments in water [10][11][12][13], glycerine [14][15][16] or other liquids like ethylene glycol [17], in which radiation does occur but is much smaller than convection in water (assumption QR=0). Others used polished copper or aluminium plates [18][19][20][21] assuming that when ε=0, QR is also equal to 0. The remainder calculated the radiative flux from the Stefan-Boltzmann equation for given values of ε and subtracted it from the heating power of the tested surfaces.…”

Section: Introductionmentioning

confidence: 99%

Empirical Relationship Describing Total Convective and Radiative Heat Loss in Buildings

Ryms¹,

Kwiatkowski²,

Lewandowski³

2023

IJHT

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On the basis of theoretical considerations of convective-radiative heat transfer, a relationship was developed enabling the total convective and radiative heat flux QC+R emitted from any object at tw and its surroundings at t∞ to be calculated from known values of the surface temperature of such an object, i.e., the known temperature difference Δt=tw -t∞ and average air temperature Tav. This relationship is applied to thermal imaging cameras with the aim of developing appropriate software to enhance their measurement capabilities. They can then be used not only for monitoring and measuring temperature, local overheating, heat losses through insulation materials, thermal bridges, constructional defects, moisture, etc., but also for measuring the heat losses from any object, such walls and buildings. This empirical relationship includes constants relating to the object itself, such as its characteristic dimension l, surface area A, emissivity ε and temperature parameters, which depend on tw, t∞, Δt and Tav and on the physical properties of air. Experimental validation of the proposed relationship, performed for two values of the surface emissivity ε, showing the discrepancies ΔQC+R=1.75% (for ε=0.884) and 4.85% (for ε=0.932), has confirmed its correctness and its practicability.

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“…depending on the type of flow and the fluid properties the coefficients in the nu-Ra formula can differ significantly. shaub et al [13] have performed experiments on the copper plate 2 m tall heated to a maximum temperature of 90°C. The plate was polished to minimize emissivity.…”

Section: Introductionmentioning

confidence: 99%

“…The results have been compared to the Churchill and Chu model valid for laminar and turbulent flows characterized by the Ra number ranging from 10 -1 to 10 12 [14]. The experiments performed by shaub et al [13] have shown a mean absolute deviation of 8.1% to the Churchill and Chu model for the isothermal case. For the unsteady experiments, an increase of 22% in the heat transfer was observed in comparison to the quasi-stationary approach.…”

Section: Introductionmentioning

confidence: 99%

Archives of Metallurgy and Materials

Hadała

Malinowski

Gołdasz

et al. 2021

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Inverse solutIon to the vertIcal Plate coolIng by radIatIon and convectIon In aIrThe inverse solution to the heat flux identification during the vertical plate cooling in air has been presented. The developed solution allowed to separate the energy absorbed by the chamber due to radiation from the convection heat losses to air. The uncertainty tests were carried out and the accuracy of the solution has been estimated at a level of 1%-5% depending on the boundary condition model. The inverse solution was obtained for the temperature measurements in the vertical plate. The stainless-steel plate was heated to 950°C and then cooled in the chamber in air only to about 30°C. The identified heat transfer coefficient was compared with the Churchill and Chu model. The solution has allowed to separate the radiation heat losses and to determine the nusselt number values that stay in good agreement with the Churchill and Chu model for a nearly steady-state air flow for the plate temperature below 100°C.

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Experimental investigation of heat transfer by unsteady natural convection at a vertical flat plate

Cited by 17 publications

References 32 publications

Investigation of the effect of different materials on convective heat transfer

Investigation of the effect of different materials on convective heat transfer

Empirical Relationship Describing Total Convective and Radiative Heat Loss in Buildings

Archives of Metallurgy and Materials

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