Download or read book Critical Heat Flux for Flow Boiling of Water at Low Pressure on Smooth and Micro Structured Zircaloy Tube Surfaces KIT Scientific Reports 7627 written by Christoph Haas and published by KIT Scientific Publishing. This book was released on 2012 with total page 186 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Critical Heat Flux in Flow Boiling in Microchannels written by Sujoy Kumar Saha and published by Springer. This book was released on 2015-06-04 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Brief concerns the important problem of critical heat flux in flow boiling in microchannels. A companion edition in the SpringerBrief Subseries on Thermal Engineering and Applied Science to “Heat Transfer and Pressure Drop in Flow Boiling in Microchannels,” by the same author team, this volume is idea for professionals, researchers, and graduate students concerned with electronic cooling.
Download or read book An Empirical Correlation of Critical Boiling Heat Flux in Forced Flow Upward Through Uniformly Heated Tubes written by U. Von Glahn and published by . This book was released on 1962 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Flow Boiling in Expanding Microchannels written by Tamanna Alam and published by Springer. This book was released on 2017-05-24 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Brief presents an up to date summary of details of the flow boiling heat transfer, pressure drop and instability characteristics; two phase flow patterns of expanding microchannels. Results obtained from the different expanding microscale geometries are presented for comparison and addition to that, comparison with literatures is also performed. Finally, parametric studies are performed and presented in the brief. The findings from this study could help in understanding the complex microscale flow boiling behavior and aid in the design and implementation of reliable compact heat sinks for practical applications.
Download or read book Hydrodynamic Aspects of Boiling Heat Transfer written by N. Zuber and published by . This book was released on 1959 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Enhanced Flow Boiling Heat Transfer in Microchannels with Structured Surfaces at Varied Mass Flow Rates written by David Wei Bian and published by . This book was released on 2015 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis investigates the role of mass flux on flow boiling heat transfer in microchannels with surface micropillar arrays. The motivation for this investigation was to determine the general trends of the optimal micropillar array geometry in terms of its heat transfer capabilities. The experiment was conducted with three microchannels: a flat surface microchannel, a sample called the 5-15 (height h = 25 [mu]m, diameter d = 5 [mu]m, and pitch l = 15 [mu]m) and a sample called the 10-40 (height h = 25 [mu]m, diameter d = 10 [mu]m, and pitch l = 40 [mu]m). The structured surface microchannels, due to their capillary pressure-induced wicking capabilities, exhibited less temperature rise and pressure drop fluctuations at high heat fluxes. Furthermore, it was verified that the critical heat flux value of all microchannels increased with mass flux. In addition, it was concluded that at lower mass fluxes, the relative percentage heat transfer enhancement of the structured surface microchannels over the flat surface microchannel was greater. The trend observed suggests that denser samples are better at lower mass fluxes. However, if a sample is too dense, there may be too much viscous drag. Thus, an optimal balance between capillary force and viscous drag must be found in order to determine the optimum micropillar array geometry and density for maximizing the critical heat flux value. Finally, for a given mass flux, the pressure drop across every microchannel was approximately equal at all heat fluxes. This implies that no additional power consumption is required to pump a particular mass flux through a structured surface microchannel than a flat surface microchannel, though there is certainly additional power required to increase the mass flux. This work provides insights into the roles of both the micropillar array surface structures and the mass fluxes on the heat transfer performance of flow boiling in microchannels. The results and observations of this experiment may prove helpful in guiding future work in an attempt to optimize microchannels for heat transfer applications in electronics.
Download or read book Heat Transfer Flow Instability and Critical Heat Flux for Water in a Small Tube at 200 Psia written by R. J. Weatherhead and published by . This book was released on 1963 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: Heat transfer data from a vertical Type 304 stainless steel tube operating at 200 psia in forced-convection heating and subcooled nucleate boiling is compared with and agrees with two equations.
Download or read book Analysis of Heat Transfer Burnout Pressure Drop and Density Data for High pressure Water written by W. H. Jens and published by . This book was released on 1955 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Cross Flow Boiling in Tube Bundles written by S. C. Yao and published by . This book was released on 1982 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt: The research on boiling in confined spaces has been completed. This problem is of great importance to the boiling induced corrosion in the steam generator crevices between the tube and the support structures. In the report of 1981, analysis of single phase flow, two phase flow, and dryout in crevices have been presented. Experimental results of boiling and dryout in vertical crevices with closed bottom were also reported. In the report of 1982, the results of forced convective boiling heat transfer and critical heat flux in crevices are shown. In this report, the boiling heat transfer and critical heat flux in horizontal crevices are reported. The research on cross flow boiling in tube bundles proceeds smoothly. In this report, the analysis of single phase flow pressure drop and convective heat transfer in tube bundles at cross flow of very low or very high Reynolds numbers are presented. The experimental setup has been completed and data are taken presently.
Download or read book The Evaluation of the Critical Heat Flux for Water Flowing in Annular Channels During Forced Convection Boiling written by Glenn Joel Kangas and published by . This book was released on 1964 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Investigation of Flow Boiling Phenomena in Small scale Complex Geometries written by Amir Hooshang Raeisi Dehkordi and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This study concerns measurement and prediction of single-phase and flow boiling heat transfer coefficients and pressure drops in mini multi-channel geometries with and without interconnecting passages, including plate channel; parallel channel; in-line pin-fin and in-line off-set pin-fin surfaces. Experiments were performed with refrigerant R113 and deionised water at atmospheric pressure. Single-phase and flow boiling heat transfer coefficients and pressure drops were obtained over a range of effective heat fluxes and mass fluxes. For the plate and parallel channel surfaces, the results obtained have been compared with several published macro- and micro-channels correlations. For the in-line and in-line off-set pin fin surfaces, as the geometries have some similarities with tube bundles, the results obtained have been predicted using the standard correlations for tube bundles. The results also have been compared with several existing correlations developed based on macro-scale tube bundles and micro-pin-fin surfaces data. The saturated flow boiling heat transfer coefficients for the parallel channel and pin-fin surfaces were similar to within the experimental uncertainty, and considerably higher than the plate channel values, all dependent on heat flux and reasonably independent of mass flux and vapour mass fraction. This indicated that the dominant heat-transfer mechanism in the saturated boiling flow regime was nucleate boiling for all surfaces. The parallel channel, in-line and off-set pin-fin surfaces improved heat transfer by increasing the surface area and the heat transfer coefficient in comparison with the plate channel surface. The two-phase pressure drops in the parallel channel and pin-fin surfaces were considerably larger than that for the plate channel surface. Thus, the reduction in wall temperature is achieved by a significant pressure drop penalty. For the pin-fin surfaces, at low vapour qualities the heat transfer coefficients were in reasonable agreement with the conventional scale tube bundles correlations however as the vapour quality increases, the correlations were not able to predict the heat transfer coefficient as unlike the conventionally-sized tube bundles, the convective enhancement does not happen in the mini-pin-fin surfaces tested. The nucleate pool boiling correlation of Cooper (1984) provided a good agreement with the data for all surfaces tests with R113 and deionised water. The measured two-phase pressure drops for both pin-fin surfaces tests with R113 and deionised water were in a good agreement with the predicted values obtained from standard correlations for tube bundles, indicating pressure drop methods maybe transferable.
Download or read book Critical Heat Flux and Flow Pattern Characteristics of High Pressure Boiling Water in Forced Convection written by Frank Eugene Tippets and published by . This book was released on 1962 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Study of the Critical Heat Flux in an Accelerating Pool Boiling System written by Jim Mills Adams and published by . This book was released on 1962 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Boiling Heat Transfer and Two phase Flow written by Long-sun Tong and published by . This book was released on 1965 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modeling of Critical Heat Flux for Subcooled and Low quality Flow Boiling written by C. H. Lee and published by . This book was released on 1989 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Critical Heat Flux in Subcooled Flow Boiling of Water written by Yuzhou Chen and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Critical Heat Flux in Subcooled Flow Boiling of Water.
Download or read book Roles Played by Heater Size Contact Angle Surrounding Vessel Size and Surface Structure During Pool Boiling on Horizontal Surfaces written by Zhenyu She and published by . This book was released on 2021 with total page 186 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nucleate boiling is ubiquitous from daily lives to engineering applications, and the increasing demand for efficient heat transfer in the industry requires further understanding of it, especially on small scales where the knowledge on conventional scales may no longer apply. This study investigated the effects of heater size, contact angle, surrounding vessel size, and surface structure on nucleate boiling heat transfer occurring on horizontal flat surfaces where the heater size is comparable to the two-dimensional ''most dangerous'' Taylor wavelength, aiming to comprehend the parametric effects on nucleate boiling heat flux and critical heat flux (CHF) and revisit the hydrodynamic theory near critical condition. Saturated water at one-atmosphere pressure was boiled on horizontal flat copper discs of diameters 1.0, 1.5, and 2.0 cm, respectively. The contact angle was varied from about 10 to 80 deg by controlling thermal oxidation of the discs, while the surrounding vessel size was changed by placing glass tubes of different inner diameters around the discs. The surface structure in the form of microgrooves was fabricated by sanding the disc top surface. Boiling heat transfer data were obtained up to CHF. Boiling curves and CHFs measured under different experimental configurations were compared in terms of each parameter. Rohsenow's correlation was employed to assess the parametric effects on nucleate boiling heat flux quantitatively. Vapor removal patterns were photographed in nucleate boiling regime and near CHF. Vapor jet diameter and the dominant wavelength at water-steam interface were measured from the photographs for the well wetted discs and used to predict the corresponding CHF based on the hydrodynamic theory. For well wetted surfaces, the boiling curve was insensitive to the heater size, but the CHF increased when the heater size was reduced from 2.0 to 1.0 cm. Improving the wettability delayed the onset of nucleate boiling and shifted the boiling curve to the right while enhancing the CHF substantially. Enlarging the liquid-holding vessel hardly affected the boiling curve at low heat fluxes but improved the CHF slightly. The structured surface featured higher nucleate boiling heat flux resulting from more active nucleation sites but showed no advantage in CHF over the plain surface of similar size and contact angle. In this study, the highest measured CHFs for plain and structured surfaces are close and both about 2.1 times Zuber's CHF prediction for infinite horizontal flat plates. They were obtained on well wetted 1.0-cm-diameter discs surrounded by large vessels.
