Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Nucleate Pool Boiling Characteristics from a Horizontal Microheater Array
Author: Study of Nucleate Pool Boiling of FC-72 Using Microscale Heater Arrays in Microgravity and Earth Gravity Environments
Author: Nagaraja Kumar YaddanapudiPublisher:
ISBN:
Category :
Languages : en
Pages : 260
Book Description
Dissertation Abstracts International
Author: Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 884
Book Description
Microheater Array Boiling Experiment
Author: Nucleate Pool Boiling Characteristics of Gewa-T Finned Surfaces in Freon-113
Author: R. J. PulidoPublisher:
ISBN:
Category :
Languages : en
Pages : 101
Book Description
Pool boiling heat-transfer measurements were made using seven Gewa-T copper tubes in R-113. The first tube (18-mm OD x 0.75 fins/mm x 0.25 mm gap) was tested under three conditions: (a) plain, (b) with four shrouds and (c) with up to 5 wires (0.13 mm diameter) wrapped in the inter-fin trough area. Verifying prior data, the shroud with longitudinal openings of 60 deg at the top and 8.5 deg at at the bottom gave the best performance among the four shrouds tested. This shroud increased the boiling heat-transfer coefficient by 253 percent (over the smooth tube case) at a heat flux of 10,000 W/sq m while it showed only a 18 percent increase at 100,000 W/sq m. When wire wraps were provided, in all cases, the heat-transfer coefficient was improved at all heat fluxes. The use of three wires gave the best performance with 341-percent increase in heat-transfer coefficient at 10,000 W/sq m and a 130 percent increase at 100,000 W/sq m. The next three Fewa-T tubes had dimensions of 25 mm OD x 0.75 fins/mm with fin-tip gaps of 0.15, 0.25, and 0.35 mm, respectively. The last three Gewa-T tubes had the same dimensions except that the fin density was 1.02 fins/mm. For each of these fin densities, the 0.25 mm fin-tip gap produced the best boiling performance at all heat fluxes. Originator supplied keywords include: Nucleate pool boiling; Gewa-T finned surfaces.
Nucleate Boiling Characteristics and the Critical Heat Flux Occurrence in Subcooled Axial-flow Water Systems
Author: R. J. WeatherheadPublisher:
ISBN:
Category : Cooling
Languages : en
Pages : 40
Book Description
Experimental data obtained at CISE on two-phase adiabatic flow are presented. The measured quantities are pressure drop and liquid film thickness on the inner and the outer wall of the conduit. The pressure loss and film flow rate are evaluated. The experimental data are discussed and the effects of various physical and geometrical parameters are investigated. A simple relation for the pressure loss in adiabatic dispersed regime is given.
An SEM Surface Study of Nucleate Pool Boiling Heat Transfer to Saturated Liquid Nitrogen Reduced Pressures from 0.1 to 0.9
Author: David Virgil PorcheyPublisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 284
Book Description
"This study constituted an examination of both nucleate boiling and maximum heat flux characteristics of liquid nitrogen boiling from characterized surfaces. Several textures of gold plated copper surfaces were studied in addition to silver and silver oxide surfaces. Data were taken over a wide range of reduced pressures. All surfaces were examined using a Scanning Electron Microscope (SEM). Data and micrograph comparison revealed that both surface chemistry and surface roughness affect the nucleate boiling characteristics of liquid nitrogen. These effects are separated from each other showing that nucleate boiling is a function of both surface chemistry and topography. Surface roughness was found to have a significant effect on the maximum heat flux with rougher surfaces yielding higher heat flux values. The temperature difference at burnout was found to be a function of both surface chemistry and roughness. Some existing correlations for both nucleate boiling and maximum heat fluxes were examined and shown to inadequately predict the data, primarily because of inability to account for surface roughness and/or surface-fluid interaction as affected by surface chemistry. A maximum temperature difference correlation tested predicted burnout temperature differences well. The necessity to age a surface in the fluid to be boiled was found not to be a result of adsorbed gases, but probably a result of impurities acquired on the surface that must be removed. Attempts to observe hysteresis is were unsuccessful. Hysteresis was found not to be a function of adsorbed inert gases. Data indicated that one mechanism of heat transfer by nucleate boiling will not suffice for all pressures. An existing nucleate boiling correlation was modified to allow for a mechanism change and predicted the data better than other correlations tested"--Abstract, pages ii-iii.
Author: George M. Bertsch
Author: Hsing-Sheng Liang
Author: R. F. Gaertner