Heat dissipation of parallel plates by free convection
TL;DR: In this article, the warmeabgabe bei freier Konvektion in Luft von vertikalen quadratischen parallelen Platten of h × h cm2 im gegenseitigen Abstand b wird gemessen.
About: This article is published in Physica D: Nonlinear Phenomena.The article was published on 1942-01-01. It has received 535 citations till now.
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TL;DR: In this paper, the complex nature of the natural convection phenomena in enclosures is discussed and the boundary value problem is formulated, assuming that the motion is 2D and steady, the fluid is incompressible and frictional heating is negligible, and the difference between the hot wall and cold wall temperatures is small relative to the absolute temperatures of the cold wall.
Abstract: Publisher Summary This chapter discusses the complex nature of the natural convection phenomena in enclosures It discusses the two basic configurations of natural convection— that is, a rectangular cavity and a horizontal circular cylinder In rectangular cavities, consideration is given to the two-dimensional convective motion generated by the buoyancy force on the fluid in a rectangle and to the associated heat transfer The two long sides are vertical boundaries held at different temperatures and the short sides can either be heat conducting or insulated Particular attention is given to the different flow regimes that can occur and the heat transfer across the fluid space between the two plane parallel vertical boundaries Although heat transfer by radiation may not be negligible it is independent of the other types of heat transfer and can be fairly accurately calculated separately To formulate the boundary value problem that describes this phenomena it is assumed that: (a) the motion is two-dimensional and steady, (b) the fluid is incompressible and frictional heating is negligible, and (c) the difference between the hot wall and cold wall temperatures is small relative to the absolute temperatures of the cold wall In horizontal circular cylinder, consideration is given to the large Rayleigh number flow with the Prandtl number large and the Grashof number of unit order of the magnitude
973 citations
TL;DR: In this article, the complex nature of the natural convection phenomena in enclosures is discussed and the boundary value problem is formulated, assuming that the motion is two-dimensional and steady, the fluid is incompressible and frictional heating is negligible.
Abstract: Publisher Summary This chapter discusses the complex nature of the natural convection phenomena in enclosures. It discusses the two basic configurations of natural convection— that is, a rectangular cavity and a horizontal circular cylinder. In rectangular cavities, consideration is given to the two-dimensional convective motion generated by the buoyancy force on the fluid in a rectangle and to the associated heat transfer. The two long sides are vertical boundaries held at different temperatures and the short sides can either be heat conducting or insulated. Particular attention is given to the different flow regimes that can occur and the heat transfer across the fluid space between the two plane parallel vertical boundaries. Although heat transfer by radiation may not be negligible it is independent of the other types of heat transfer and can be fairly accurately calculated separately. To formulate the boundary value problem that describes this phenomena it is assumed that: (a) the motion is two-dimensional and steady, (b) the fluid is incompressible and frictional heating is negligible, and (c) the difference between the hot wall and cold wall temperatures is small relative to the absolute temperatures of the cold wall. In horizontal circular cylinder, consideration is given to the large Rayleigh number flow with the Prandtl number large and the Grashof number of unit order of the magnitude.
382 citations
TL;DR: In this paper, a numerical and experimental investigation of the developing laminar free convection heat transfer in vertical parallel plate channels with asymmetric heating is presented, where the Nusselt number characterizing the total heat transfer to the fluid is found to be related to the Rayleigh number very nearly by a universal curve for all ratios of wall temperature differences.
330 citations
TL;DR: In this paper, the authors focus on determining equations for the local and mean rate of laminar heat transfer, which are approximately valid for different geometries by use of these equations, several new correlations are obtained for various heat transfer problems, and the results compared with experiments.
Abstract: Publisher Summary The first part of the chapter focuses on determining equations for the local and mean rate of laminar heat transfer, which are approximately valid for different geometries By use of these equations, several new correlations are obtained for various laminar heat transfer problems, and the results compared with experiments The problems considered involve heat transfer (1) from a cylinder, (2) from a sphere, (3) between concentric cylinders, (4) between concentric and eccentric spheres, (5) between vertical plates, and (6) from a nonisothermal vertical plate Attention is then turned to turbulent free convection heat transfer where the heat transfer from inclined plates and between differentially heated plates is considered A method of solving problems involving both laminar and turbulent convection is then outlined The criterion developed for the regions of applicability of the laminar and turbulent equations is shown to accurately predict the experimentally determined onset of instability of the laminar flow for free convection from an isolated plate A recommendation is then made for correlating heat transfer results in a clearer and more convenient way
302 citations
TL;DR: The chapter summarizes analytical, numerical, and experimental work in literature, in order to facilitate the improvement of existing schemes and provide a basis for the development of new ones on the thermal control of semiconductor devices, modules, and total systems.
Abstract: Publisher Summary Thermal control of electronic components has one principal objective, to maintain relatively constant component temperature equal to or below the manufacturer's maximum specified service temperature, typically between 85 and 100°C. It is noted that even a single component operating 10°C beyond this temperature can reduce the reliability of certain systems by as much as 50%. Therefore, it is important for the new thermal control schemes to be capable of eliminating hot spots within the electronic devices, removing heat from these devices and dissipating this heat to the surrounding environment. Several strategies have developed over the years for controlling and removing the heat generated in multichip modules, which include advanced air-cooling schemes, direct cooling, and miniature thermosyphons or free-falling liquid films. The chapter summarizes analytical, numerical, and experimental work in literature, in order to facilitate the improvement of existing schemes and provide a basis for the development of new ones. The chapter focuses on investigations performed over the past decade and includes information on the thermal control of semiconductor devices, modules, and total systems.
285 citations
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TL;DR: In this article, the theory of the energy loss by heat conduction for filaments of different diameters in a gas, given by Langmuir, is combined with the hydrodynamical one, in particular with the theory given by Nuszelt.
6 citations