An Experimental Investigation of Natural Convection Heat Transfer from Vertical Flat Plates in Mercury PDF Download
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Author: Donald Henry White Publisher: ISBN: Category : Heat Languages : en Pages : 400
Book Description
Heat transfer from a vertical flat plate in an infinite pool of mercury was investigated. Velocity profiles were measured with a hot-film anemometer and simultaneous temperature profiles measured with thermocouples in this low Prandtl number liquid metal. Constant heat flux plates at Grashof numbers of 9 x 108 and 4 x 107 were investigated. Pseudo-constant temperature plates at Grashof numbers of 8 x 107 and 2 x 107 were investigated. The velocity profiles, the first known natural convection experimental profiles reported for liquid metals, were found to be a function of both plate position and Grashof number. This relationship was predicted by available perturbation solutions for the flat plate in an infinite, low Prandtl number fluid, but not by the similarity or integral solutions. Indications are that the best analytical solutions do a poor job of predicting profiles and that natural convection heat transfer rates in liquid metals are higher than originally believed. The use of a hot-film anemometer to measure low velocities in mercury is possible, but the existence of a thermo-barrier film causes serious experimental problems which have been only partially solved.
Author: Donald Henry White Publisher: ISBN: Category : Heat Languages : en Pages : 400
Book Description
Heat transfer from a vertical flat plate in an infinite pool of mercury was investigated. Velocity profiles were measured with a hot-film anemometer and simultaneous temperature profiles measured with thermocouples in this low Prandtl number liquid metal. Constant heat flux plates at Grashof numbers of 9 x 108 and 4 x 107 were investigated. Pseudo-constant temperature plates at Grashof numbers of 8 x 107 and 2 x 107 were investigated. The velocity profiles, the first known natural convection experimental profiles reported for liquid metals, were found to be a function of both plate position and Grashof number. This relationship was predicted by available perturbation solutions for the flat plate in an infinite, low Prandtl number fluid, but not by the similarity or integral solutions. Indications are that the best analytical solutions do a poor job of predicting profiles and that natural convection heat transfer rates in liquid metals are higher than originally believed. The use of a hot-film anemometer to measure low velocities in mercury is possible, but the existence of a thermo-barrier film causes serious experimental problems which have been only partially solved.
Author: Robert G. Colwell Publisher: ISBN: Category : Heat Languages : en Pages : 386
Book Description
An experimental investigation was conducted to determine characteristics of natural convection of mercury in a vertical channel, which was open at both ends. Two cases were investigated separately: 1) both walls uniformly and symmetrically heated, and 2) one wall heated with the other insulated. Heat transfer correlations in laminar flow were obtained for several aspect ratios (channel height/width ratio), using streamwise distance from the leading edge as the characteristic dimension. These were generalized into one correlation which contains aspect ratio, parametrically, for each set of boundary conditions. The influence of flow in from the open sides of the channel was investigated by installing insulating plates along the vertical edges. It was observed that the average velocity of a low Prandtl number fluid in buoyant flow increases as the channel width is reduced. This results in a reduction of average wall temperature until the channel is sufficiently narrow that viscous forces begin to play an important role in the integral momentum balance across the channel. The channel was thus observed to be more thermally efficient than a single heated plate for aspect ratios less than 20. Velocity profiles were obtained in the region of laminar flow for each set of boundary conditions and several channel aspect ratios. Integration of the profiles gave mass flux predictions for various conditions. A hot film anemometer was used, and has proven to be very accurate for velocity measurement in the 5-100 in/min range. The documentation of laminar instability in buoyant channel flow was also an integral facet of this experiment. The criterion used was Grashof modulus based on the streamwise coordinate where the first "observable" velocity disturbance waves were determined. Channel width decrease initially had a destabilizing influence on the flow. The transition criterion displayed a minimum value at a particular aspect ratio. It was also observed that, in narrow channel cases at the highest heat flux used, flow underwent transition then relaminarized as the boundary layers met and fully-developed conditions were established. The thesis also discusses the apparatus and unique aspects of the experimental program. Data reduction methods, property determination and some anomalies of hot film anemometry in a liquid metal are also discussed.
Author: Jonathan Craig Dutton Publisher: ISBN: Category : Heat Languages : en Pages : 358
Book Description
An experimental investigation was conducted for natural convection heat transfer in an array of uniformly heated vertical cylinders in mercury. The test section consisted of seven electrically heated cylinders of 1.365 inch diameter and 3.825 inch heated length arranged in an equilateral triangular pattern. In order to preclude side flow effects, each seven pin bundle was surrounded by an enclosure tube with unheated half cylinders attached to the tube. Temperatures were measured with a stretched wire thermocouple probe which was designed to minimize flow disturbance effects. Four geometries were studied: the single vertical cylinder (P/D = ", and three bundle spacings, P/D = 1.5, 1.3, and 1.1, where P/D is the pitch-to-diameter ratio. The heat transfer results are presented in terms of the local Nusselt number and local modified Grashof number with the range on the Grashof number being 105
Author: Deing Wang Publisher: ISBN: Category : Heat Languages : en Pages : 140
Book Description
An experimental investigation was conducted to better understand the heat transfer process with natural convection from an array of uniformly heated horizontal cylinders to mercury. Five assembly geometries were studied, these being the single horizontal cylinder, two cylinders with spacing ratios S/D = 2,3 and 4, (S represents the center-to-center spacing between cylinders of diameter, D), and three cylinders with a single spacing ratio of S/D = 2. All cylinders were arranged in the same vertical plane. A scale analysis was employed to predict the relationship between the average Nusselt number and the Boussinesq number. In the case of the single cylinder good agreement was achieved between scale analysis and experimental results. The Nusselt number is a function of Boussinesq number only in the single cylinder case. These findings were extended to cases with two and three cylinders. Correlations of Nusselt number with different Boussinesq numbers, various ratios of spacing and diameters of cylinders have been established for these multiple cylinder cases.
Author: Donald Henry White
Author: Donald Henry White
Author: Robert G. Colwell
Author: Jonathan Craig Dutton
Author: E. R. G. Eckert
Author: Allan R. Lazarus
Author: William Warren Humphreys
Author: Richard Cecil Hill
Author: Donald Victor Julian
Author: Deing Wang
Author: Ashok Kumar Verma