Interaction effects between laminar natural convection and surface radiation in tilted square and shallow enclosures

Vivek, V.; Sharma, Anil Kumar; Balaji, C.

doi:10.1016/j.ijthermalsci.2012.04.021

Cited by 62 publications

(26 citation statements)

References 30 publications

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“…This is particularly restrictive when studying microclimates with natural convection, because such transport mechanism may result in complex flow and temperature patterns, leading to marked oscillation in the local transport rates (e.g. heat fluxes) across the microclimates (Corcione 2003;Vivek et al 2012;Mayor et al 2014a). By not capturing these local effects, the mentioned techniques skip important information to allow a better understanding of the local transport processes in clothing microclimates.…”

Section: Introductionmentioning

confidence: 99%

Advanced modelling of the transport phenomena across horizontal clothing microclimates with natural convection

et al. 2015

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The ability of clothing to provide protection against external environments is critical for wearer's safety and thermal comfort. It is a function of several factors, such as external environmental conditions, clothing properties and activity level. These factors determine the characteristics of the different microclimates existing inside the clothing which, ultimately, have a key role in the transport processes occurring across clothing. As an effort to understand the effect of transport phenomena in clothing microclimates on the overall heat transport across clothing structures, a numerical approach was used to study the buoyancy-driven heat transfer across horizontal air layers trapped inside air impermeable clothing. The study included both the internal flow occurring inside the microclimate and the external flow occurring outside the clothing layer, in order to analyze the interdependency of these flows in the way heat is transported to/from the body. Two-dimensional simulations were conducted considering different values of microclimate thickness (8, 25 and 52 mm), external air temperature (10, 20 and 30 °C), external air velocity (0.5, 1 and 3 m s(-1)) and emissivity of the clothing inner surface (0.05 and 0.95), which implied Rayleigh numbers in the microclimate spanning 4 orders of magnitude (9 × 10(2)-3 × 10(5)). The convective heat transfer coefficients obtained along the clothing were found to strongly depend on the transport phenomena in the microclimate, in particular when natural convection is the most important transport mechanism. In such scenario, convective coefficients were found to vary in wavy-like manner, depending on the position of the flow vortices in the microclimate. These observations clearly differ from data in the literature for the case of air flow over flat-heated surfaces with constant temperature (which shows monotonic variations of the convective heat transfer coefficients, along the length of the surface). The flow patterns and temperature fields in the microclimates were found to strongly depend on the characteristics of the external boundary layer forming along the clothing and on the distribution of temperature in the clothing. The local heat transfer rates obtained in the microclimate are in marked contrast with those found in the literature for enclosures with constant-temperature active walls. These results stress the importance of coupling the calculation of the internal and the external flows and of the heat transfer convective and radiative components, when analyzing the way heat is transported to/from the body.

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Section: Introductionmentioning

confidence: 99%

Advanced modelling of the transport phenomena across horizontal clothing microclimates with natural convection

et al. 2015

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“…In view of a variety of shapes and thermal conditions of these devices the obstructions are considered in the form of partitions, partial baffles and discrete bodies and are assumed to be either isothermal or iso-flux or heat generating. Among the various known cooling techniques used in such applications, natural convection cooling using air as the medium is the most widely used one as it is simple to design, cheap, noise free and highly reliable [1][2][3][4][5][6][7][8][9][10][11][12][13]. For example, Sharma et al [9] studied the interaction of turbulent natural convection and surface thermal radiation in inclined square enclosures.…”

Section: Introductionmentioning

confidence: 99%

“…In another investigation Vivek et al [13] studied the interaction effects between laminar natural convection and surface radiation in shallow enclosures. They found that these interaction effects are very strong in shallow enclosures compared to square enclosures.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of a Corrugated Heat Source Cavity: A Full Convection-Conduction-Radiation Coupling

Sadripour¹

2017

AJAE

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Abstract:In present study a numerical analysis of complex heat transfer (turbulent natural convection, conduction and surface thermal radiation) in a rectangular enclosure with a heat source has been carried out. The finite volume method based on SIMPLEC algorithm has been utilized. The effects of Rayleigh number in a range from 10 8 to 10 11 , internal surface emissivity 0≤ε˂1 on the fluid flow and heat transfer have been extensively explored. Detailed results including temperature fields, flow profiles, and average Nusselt numbers have been presented. In this investigation it has been tried to study the shape of heat source influence on heat transfer and fluid field in the considered domain. According to results in low emissivity values usage of circular obstacles is recommended. Although in high emissivity values using rectangular obstacles lead to more efficiency.

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“…Thus, for instance, the processes of free convection and thermal conductivity in the rectangular regions without the local sources of the heat emission and heat sink into the walls [1,2], with the local heat emission sources [3][4][5], in the conjugate formulation [6][7][8], with radiation heat transfer [9,10], different position of the heat sources [11][12][13], different boundary conditions on the solid walls [14], the radiation source of heating transparent air medium inside the closed cavity [15], cooling the microelectronics devices [16], turbulent regimes [17] of natural convection are investigated. The enumerated solutions compose only small part of the large number of publications according to the class of problems.…”

Section: Introductionmentioning

confidence: 99%

Conjugate Heat Transfer in a Closed Volume with the Local Heat Sources and Non-Uniform Heat Dissipation on the Boundaries of Heat Conducting Walls

Maksimov

Nagornova

Glazyrin

2016

EPJ Web of Conferences

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Abstract. Is solved the problem of heat transfer in the closed volume, limited by heatconducting walls, with the local source of heat emission and the heterogeneous conditions of heat sink on the outer boundaries of solution area. The problem of convective heat transfer is solved with using a system of differential Navier-Stokes equations in the Boussinesq approximation. The simulation of turbulent flow conditions of heated air is carried out within the framework to k-H model. On the basis the analysis of the obtained temperature field and the contour lines of stream functions is made conclusion about the essential transiency of the process in question. The obtained values of temperatures and speeds in different sections of region illustrate turbulence of the process. Are investigated laws governing the formation of temperature fields in closed areas with a local heat emission source under the conditions of intensive local heat sink into environment and accumulation of heat in the enclosing constructions.

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Interaction effects between laminar natural convection and surface radiation in tilted square and shallow enclosures

Cited by 62 publications

References 30 publications

Advanced modelling of the transport phenomena across horizontal clothing microclimates with natural convection

Advanced modelling of the transport phenomena across horizontal clothing microclimates with natural convection

Numerical Investigation of a Corrugated Heat Source Cavity: A Full Convection-Conduction-Radiation Coupling

Conjugate Heat Transfer in a Closed Volume with the Local Heat Sources and Non-Uniform Heat Dissipation on the Boundaries of Heat Conducting Walls

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