Effect of surface radiation heat transfer on the optimal distribution of discrete heat sources under natural convection
TL;DR: In this article, an empirical correlation has been proposed between the non-dimensional steady state temperature (θ) and λ, by taking into account the effect of surface radiation heat transfer.
Abstract: Experiments have been conducted for natural convection heat transfer from protruding discrete heat sources, mounted at different positions on a substrate, to determine the optimal configuration, and to study the effect of surface radiation on them, which reduces their temperature upto 12 %. The optimal configuration has been determined by a non-dimensional geometric distance parameter (λ). An empirical correlation has been proposed between the non-dimensional steady state temperature (θ) and λ, by taking into account the effect of surface radiation heat transfer.
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TL;DR: In this article, a two-dimensional numerical analysis of combined heat transfer (transient natural convection, surface thermal radiation and conduction) in an air-filled square enclosure having heat-conducting solid walls of finite thickness and a local heat source in conditions of convective heat exchange with an environment has been carried out.
78 citations
TL;DR: In this article, an optimal configuration for the heat sources has been defined based on a geometric parameter λ, taken from literature, and the effect of substrate conduction on heat transfer is studied numerically considering board materials of different thermal conductivities.
45 citations
TL;DR: In this paper, a heuristic non-dimensional geometric parameter, λ, is defined for the purpose of identifying the optimal configuration for which the maximum temperature excess among the five heat sources of a configuration is the minimum, among all possible configurations.
Abstract: Experiments have been conducted from five protruding rectangular discrete heat sources (aluminum) of non-identical sizes arranged at different positions on a substrate board (Bakelite), under natural convection, to determine their optimal configuration. A substrate board is designed for conducting experiments on multiple configurations of heat sources using the same board. A heuristic non-dimensional geometric parameter, λ, is defined for the purpose of identifying the optimal configuration for which the maximum temperature excess among the five heat sources of a configuration is the minimum, among all possible configurations. The maximum temperature excess is found to decrease with λ, so the configuration with highest λ is deemed to be the optimal one. The effect of surface radiation on the heat transfer rate from the heat sources is studied by painting their surfaces with black paint of high emissivity, which reduces their temperature by as much as 15%. An empirical correlation is developed for the non-...
24 citations
TL;DR: In this paper, the authors investigated the use of dummy components along with heat sources on a substrate board to find the optimal distribution of seven heat sources with dummy components to minimize the substrate temperature.
22 citations
TL;DR: In this article, the authors conducted steady state experiments in a low speed horizontal wind tunnel under mixed convection for five discrete heat sources (aluminum) of nonidentical sizes arranged at different positions on a substrate board (bakelite) to determine the optimal configuration.
Abstract: Steady state experiments are conducted in a low speed horizontal wind tunnel under mixed convection for five discrete heat sources (aluminum) of nonidentical sizes arranged at different positions on a substrate board (bakelite) to determine the optimal configuration. The optimal configuration is one for which the maximum temperature excess (difference between the maximum temperature among the heat sources of that configuration, and the ambient temperature) is the lowest among all the other possible configurations and is determined by a heuristic nondimensional geometric parameter λ. The maximum temperature excess is found to decrease with λ, signifying an increase in heat transfer coefficient. In view of this, the configuration with highest λ is deemed to be the optimal one. The effect of surface radiation on the heat transfer characteristic of heat sources is also studied by painting their surface with black, which reduces their temperature by as much as 12%. An empirical correlation is developed for the nondimensional maximum temperature excess (θ) in terms of λ, by taking into account the effect of surface radiation. The correlation when applied for highest λ of the configuration returns the minimum value of θ at the optimal condition, which is a key engineering quantity that is sought in problems of this class.
20 citations
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TL;DR: In this article, the results of an experimental and numerical study of free convective heat transfer in a square enclosure characterized by a discrete heater located on the lower wall and cooled from the lateral walls were analyzed.
265 citations
"Effect of surface radiation heat tr..." refers background in this paper
...[3] have studied experimentally, and numerically, the effect of free convective heat transfer in a square enclosure, with a discrete heater, heated from below, and found that, for high Rayleigh number, an increase of the heat source dimension results in increase of heat transfer....
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TL;DR: In this article, the authors apply the constructal method to the discovery of the optimal distribution of discrete heat sources cooled by laminar natural convection, where the global objective is to maximize the global conductance between the wall and the fluid or to minimize the hot-spot temperatures when the total heat generation rate and global system dimensions are specified.
163 citations
"Effect of surface radiation heat tr..." refers background in this paper
...[7] have done numerical studies for the optimal dis-...
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TL;DR: In this paper, the authors investigated the heat transfer in a discretely heated enclosure for single and multiple heater configurations and found that the heat source location corresponding to maximum heat transfer is a function of Grashof number.
90 citations
"Effect of surface radiation heat tr..." refers background in this paper
...[4] have studied numerically, the effect of natural convection heat transfer in a discretely heated enclosure, and found that, for a single heat source configuration, heater locations closer to the bottom of the enclosure, yield highest rate of heat transfer in the high Grashof number range....
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TL;DR: In this paper, a general combined temperature scale method was implemented to identify the discrete heat sources (DHSs) of both external and internal types, and an associated concept of thermal strength was introduced in terms of the unified heat transfer characteristics of DHSs.
73 citations
"Effect of surface radiation heat tr..." refers background in this paper
...[8] have studied numerically, the steady state natural convection heat transfer, induced by multiple discrete heat sources, in 2D horizontal enclosures....
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TL;DR: In this article, a computational analysis of the heat transfer due to an array of distributed heat sources on the bottom wall of a horizontal enclosure is presented, where the heat sources are modeled as flush-mounted sources with prescribed heat flux boundary conditions.
Abstract: Presented in this article is a computational analysis of the heat transfer due to an array of distributed heat sources on the bottom wall of a horizontal enclosure. The heat sources are modeled as flush-mounted sources with prescribed heat flux boundary conditions. Optimum heat transfer rates and the onset of thermal instability triggering various regimes are found to be governed by the length and spacing of the sources and the width-to-height aspect ratio of the enclosure. With respect to source spacing, we found that spacing equal to that of the source length provides effective convective heat transfer, and increasing the source spacing further does not result in significant improvements. The transition from a conduction-dominated regime to a convection-dominated regime is found to be characterized by a range of Rayleigh numbers, in contrast to the classical bottom wall heating problem. The range of Rayleigh numbers at which transition takes place decreases as the source length increases. At th...
72 citations
"Effect of surface radiation heat tr..." refers background in this paper
...[1] have performed, the numerical analysis of convection patterns associated with distributed heat sources in an enclosure, and found that, the spacing equal to that of source length of heat sources provide an effective convective heat transfer....
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