Download or read book An Experimental Study of the Enhancement to Nucleate Boiling by Foam Applied Liquid Film written by Guy A. Rupp and published by . This book was released on 1990 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Experimental Study of Nucleate Boiling in a Thin Liquid Film on a Horizontal Surface written by Amnuay Udomboresuwan and published by . This book was released on 1985 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Experimental Study of Nucleate Boiling of Water in Thin Liquid Films on a Inclined Surface written by Felix H. Rojas M. and published by . This book was released on 1976 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Analytical and Experimental Study of the Thermal Boundary Layer and Ebullition Cycle in Nucleate Boiling written by Yih-Yun Hsu and published by . This book was released on 1961 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ebullition cycle of nucleate pool boiling from a heating strip was studied through the use of high-speed motion pictures of schlieren and shadowgraph images. The effects of bubble agitation on thermal layer and neighboring bubbles were observed. An over-all model of ebullition based upon experimental observation was proposed that included an analytical method for predicting bubble growth rate and an analysis of the factors that influence the magnitude of the waiting period (time interval between bubbles at a particular site). Thermal-layer thickness, cavity size, and area of influence of a growing bubble are considered. A film supplement is made available. (Author).

Download or read book Survey of the Literature Pertaining to the Phenomena of Nucleate Boiling written by R. A. Rockow and published by . This book was released on 1959 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experimental Investigation of Nucleate Boiling and Thin film Evaporation on Enhanced Silicon Surfaces written by Shailesh Malla and published by . This book was released on 2014 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present work consists of two major studies. The first study investigates the effects of surface energy or wettability on nucleate pool boiling and the second study investigates the thin-film evaporative cooling for near junction thermal management. For the first study, effects of surface energy or wettability on critical heat flux (CHF) and boiling heat transfer (BHT) of smooth heated surfaces was studied in saturated pool boiling of water at 1 atm. For this purpose hydrophilic and hydrophobic surfaces were created on one side of 1cm x 1cm double-side polished silicon substrates. A resistive heating layer was applied on the opposite side of each substrate. The surface energies of the created surfaces were characterized by measuring the static contact angles of water sessile drops. To provide a wide range of surface energies, surfaces were made of Teflon (hydrophobic), bare silicon (hydrophilic) and aluminum oxide (most hydrophilic). The measured contact angles on these surfaces were ~108, ~57 and ~13 degrees respectively. The results of pool boiling tests on these surfaces clearly illustrate the connection between surface energy and CHF. CHF was shown to linearly decrease with contact angle increase, from ~125 W/cm2 on aluminum oxide (most hydrophilic) to nearly one tenth of this value on Teflon (hydrophobic). The most hydrophilic surface also produced increasingly better BHT than plain silicon and Teflon as heat flux increased. However, below ~5 W/cm2 the hydrophobic surface demonstrated better heat transfer due to earlier onset of nucleate boiling, reducing surface superheats by up to ~5 degrees relative to the other two surfaces. Above ~5 W/cm2 the BHT of the hydrophobic surface rapidly deteriorated as superheat increased towards the value at CHF. To further understand the effect of surface energy on pool boiling performance, the growth and departure of bubbles from single nucleating sites on each surface were analyzed from high-speed video recordings. A distinct bubble behavior was observed in the hydrophobic surface where bubble growth and departure period was extremely long compared to plain silicon and aluminum oxide surfaces. This study also investigated the performance of thin-film evaporative cooling for near-junction thermal management. A liquid delivery system capable of delivering water in small volumes ranging 20~75 nl at frequencies of up to 600 Hz was established. On one side of the silicon chip, a resistive heating layer of 2 mm x 2 mm was fabricated to emulate the high heat flux hot-spot, and on the other side a superhydrophilic nanoporous coating (SHNC) was applied over an area of 1 cm x 1 cm. With the aid of the nanoporous coating, delivered droplets spread into thin films of thicknesses less than 10[mu]m. With this system, evaporative tests were conducted in ambient in an effort to maximize dryout heat flux and evaporative heat transfer coefficient. During the tests, heat flux at the hot spot was varied to values above 1000 W/cm2. Water was delivered at either given constant frequency (constant mass flow rate) or at programmed variations of frequency (variable mass flow rate), for a given nanoliter dose volume. Heat flux and hot spot surface temperatures were recorded upon reaching steady state at each applied heat flux increment. Relative to bare silicon surface, dryout heat flux of the SHNC surface was found to increase by ~5 times at 500~600 Hz. Tests were also conducted at various system pressures and temperatures in a micro-gap to emulate the actual embedded thermal management system. The micro-gap was made by positioning a top cover plate 500 [mu]m above the test surface. System temperature did not influence the hotspot temperature. This was due to the formation of near saturation temperature inside the micro-gap for all cases as a result of vapor accumulation. Increase in system pressure increased the hotspot temperature. At 1500 W/cm2, hotspot temperature increased by 6 C and 24 C by increasing the system pressure by 7.32 and 14.7 psi respectively. This was due to increase in saturation point as a result of increase in pressure. On the SHNC surface a mixed mode of heat transfer comprising of thin-film boiling and thin-film evaporation was observed particularly at moderate heat flux (~700 W/cm2). To further enhance the heat transfer coefficient, aluminum microporous coating was developed that increased the number of nucleation sites for thin-film boiling and also maintained the wettability for thin-film evaporation at higher heat fluxes. Test results showed a marginal improvement in dry-out heat flux compared to SHNC, however, significant reduction was achieved in hot-spot temperature at all heat flux levels. A net reduction of ~ 58oC was obtained at ~1600 W/cm2 by using aluminum based microporous coating.

Download or read book Experimental Study of Nucleate Boiling Bubble Dynamics and Heat Transfer Enhancement on Printed Bi functional Surfaces written by Michele David and published by . This book was released on 2016 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: Boiling heat transfer is studied for its ability to dissipate high fluxes and achieve heat transfer coefficients two orders of magnitude greater than single-phase heat transfer systems. Heater surface enhancement with increased surface area, varied geometry, wettability contrast and micro/nano-structures can further enhance boiling heat transfer performance through bubble nucleation augmentation. Bubble nucleation control, growth and departure dynamics is important in understanding boiling phenomena and enhancing nucleate boiling heat transfer performance. Bi-functional surfaces for enhanced boiling heat transfer were fabricated and studied through investigation of bubble dynamics and pool boiling experiments. For the fabrication of the surface, hydrophobic polymer dot arrays are first printed on a substrate, followed by hydrophilic ZnO nanostructure deposition via microreactor-assisted nanomaterial deposition (MAND) processing. Wettability contrast between the hydrophobic polymer dot arrays and aqueous ZnO solution allows for the fabrication of surfaces with distinct wettability regions. Bi-functional surfaces with various configurations were fabricated and their bubble dynamics were examined at elevated heat flux, revealing various nucleate boiling phenomena. In particular, aligned and patterned bubbles with a tunable departure frequency and diameter were demonstrated in a boiling experiment for the first time. A pool boiling experimental facility has been designed and built to investigate nucleate pool boiling in water at atmospheric pressure. Resulting boiling curves of enhanced surfaces showed up to 3X enhancement in heat transfer coefficients at the same surface superheat using bi-functional surfaces, compared to a bare stainless steel surface. The surfaces show promising results for energy savings in two-phase change applications.

Download or read book The Nature of Liquid Film Evaporation During Nucleate Boiling written by Robert R. Sharp and published by . This book was released on 1964 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Experimental Study of Nucleate Boiling in Saturated Liquid Oxygen and Nitrogen Between Subatmospheric and Thee Critical Pressures written by Philip George Kosky and published by . This book was released on 1963 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Masters Theses in the Pure and Applied Sciences written by W. H. Shafer and published by Plenum Publishing Corporation. This book was released on 1992 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt: Masters Theses Listed by Discipline: Aerospace Engineering. Agricultural Economics, Sciences and Engineering. Architechtural Engineering and Urban Planning. Astronomy. Astrophysics. Ceramic Engineering. Communications Engineering and Computer Science. Cryogenic Engineering. Electrical Engineering. Engineering Mechanics. Engineering Physics. Engineering Science. Fuels, Combustion, and Air Pollution. General and Environmental Engineering. Geochemistry and Soil Science. Geological Sciences and Geophysical Engineering. Geology and Earth Science. Geophysics. Industrial Engineering. Marine and Ocean Engineering. Materials Science and Engineering. Mechanical Engineering and Bioengineering. Metallurgy. Meteorology and Atmospheric Science. 17 additional disciplines. Index.

Download or read book An Experimental Investigation Nucleate Boiling in Thin Liquid Films written by Almon Duncan Rivers and published by . This book was released on 1974 with total page 61 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental data was taken to determine the heat transfer coefficient during boiling of Freon 113 in thin liquid films from a horizontal, rectangular foil .025 mm thick. Heat flux was held constant at 8, 12, 16 and 32 thousand watts/sgm as liquid level was lowered from 18mm to 0.2mm below which dryout usually occurred. Surface temperature of the foil was qualitatively mapped with Cholesteric Liquid Crystals. This mapping was recorded and is presented by color photographs. There is an increase in heat transfer coefficient as liquid level is lowered below 2.0 mm for Freon 113. Liquid Crystals are a practical means of mapping the nucleation sites on the surface of a thin foil boiling test section. The heating surface under the bubbles forming on the surface is cooler than under the undisturbed liquid. As heat flux increases the number of active nucleation sites also increases. (Modified author abstract).

Download or read book Experimental Investigation of Nucleate Boiling Bubble Dynamics in Normal and Zero Gravities written by Thomas H. Cochran and published by . This book was released on 1968 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Advances in Heat Transfer written by and published by Academic Press. This book was released on 1998-05-18 with total page 467 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in Heat Transfer

Download or read book Master s Theses Directories written by and published by . This book was released on 1991 with total page 560 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Experimental Study of Nucleate Boiling Under Vacuum Conditions written by Charles Walter Frost and published by . This book was released on 1970 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Heat Transfer in Aerospace Applications written by Bengt Sundén and published by Academic Press. This book was released on 2016-10-19 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt: Heat Transfer in Aerospace Applications is the first book to provide an overall description of various heat transfer issues of relevance for aerospace applications. The book contains chapters relating to convection cooling, heat pipes, ablation, heat transfer at high velocity, low pressure and microgravity, aircraft heat exchangers, fuel cells, and cryogenic cooling systems. Chapters specific to low density heat transfer (4) and microgravity heat transfer (9) are newer subjects which have not been previously covered. The book takes a basic engineering approach by including correlations and examples that an engineer needs during the initial phases of vehicle design or to quickly analyze and solve a specific problem. Designed for mechanical, chemical, and aerospace engineers in research institutes, companies, and consulting firms, this book is an invaluable resource for the latest on aerospace heat transfer engineering and research. Provides an overall description of heat transfer issues of relevance for aerospace applications Discusses why thermal problems arise and introduces the various heat transfer modes Helps solve the problem of selecting and calculating the cooling system, the heat exchanger, and heat protection Features a collection of problems in which the methods presented in the book can be used to solve these problems

Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1989 with total page 410 pages. Available in PDF, EPUB and Kindle. Book excerpt: