Download or read book Single phase and Flow Boiling Heat Transfer of Jet Impingement on Smooth and Enhanced Micro Structured Surfaces written by Sidy Ndao and published by . This book was released on 2010 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Advances in Heat Transfer Enhancement written by Sujoy Kumar Saha and published by Springer. This book was released on 2016-04-23 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Brief addresses the phenomena of heat transfer enhancement. A companion edition in the SpringerBrief Subseries on Thermal Engineering and Applied Science to three other monographs including “Critical Heat Flux in Flow Boiling in Microchannels,” this volume is idea for professionals, researchers, and graduate students concerned with electronic cooling.

Download or read book Submerged Jet Impingement Boiling Thermal Management written by Ruander Cardenas and published by . This book was released on 2011 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: Technologies such as avionics and power electronics are driving the demand for thermal management schemes towards high heat fluxes and low surface temperatures. Typically, these applications require the dissipation of heat fluxes in the rage of 100-1000 W/cm2 while maintaining surface temperatures lower than about 85 °C. Phase-change heat transfer schemes such as pool boiling, flow boiling in mini/micro-channel heat sinks, and sprays and jet impingement boiling are frequently used to meet this demand. This dissertation documents global heat transfer characteristics of submerged jet impingement boiling for high heat flux, low surface temperature applications. The effect of geometrical and flow parameters on heat transfer performance are examined for a single circular jet using water and FC-72 as working fluids. Exclusive to this study is the comparison of distinct jet fluids at a fixed saturation temperature, which is achieved by comparing sub-atmospheric jet impingement boiling data of water with atmospheric FC-72 experiments. Under sub-atmospheric conditions, the liquid-to-vapor density ratio of water is within a range that has not been studied in previous jet impingement boiling experiments. Varied geometrical parameters include the surface-to-nozzle diameter ratio, surface roughness, and jet configuration. Varied fluidic parameters include pressure, jet exit Reynolds number, fluid subcooling, and fluid properties. Global experimental data collected during this study are used to document the relationship between surface temperature and surface heat flux through boiling curves. The global data are augmented by qualitative high-speed visualization. Experimental data demonstrate enhanced heat transfer capabilities beyond those of pool boiling by using a submerged impinging jet. For a fixed saturation temperature, significantly higher heat transfer rates are attainable using water in comparison to FC-72. A CHF map for submerged jet impingement boiling is developed based on experimental evidence. A general submerged jet impingement CHF correlation is developed based on a well known CHF model in literature. A novel, passive means of preventing temperature overshoot of highly-wetting fluids during submerged jet impingement boiling is introduced.

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 Journal of Heat Transfer written by and published by . This book was released on 2008 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Microjet Array Impingement Heat Transfer Crossflow Effects in Single phase and Flow Boiling written by Brian M. Werneke and published by . This book was released on 2015 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Annual IEEE Semiconductor Thermal Measurement and Management Symposium written by and published by . This book was released on 1999 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Flow Boiling in Microgap Channels written by Tamanna Alam and published by Springer Science & Business Media. This book was released on 2013-08-26 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: Flow Boiling in Microgap Channels: Experiment, Visualization and Analysis presents an up-to-date summary of the details of the confined to unconfined flow boiling transition criteria, flow boiling heat transfer and pressure drop characteristics, instability characteristics, two phase flow pattern and flow regime map and the parametric study of microgap dimension. Advantages of flow boiling in microgaps over microchannels are also highlighted. The objective of this Brief is to obtain a better fundamental understanding of the flow boiling processes, compare the performance between microgap and conventional microchannel heat sinks, and evaluate the microgap heat sink for instabilities and hotspot mitigation.

Download or read book tan n w Mim With illustrations written by and published by . This book was released on 1949 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Local Heat Transfer Rate and Bubble Dynamics During Jet Impingement Boiling written by Preeti Mani and published by . This book was released on 2012 with total page 330 pages. Available in PDF, EPUB and Kindle. Book excerpt: Characterization of local boiling trends, in addition to the typically reported area-averaged trends, is essential for the robust design and implementation of phase change technologies to sensitive heat transfer applications such as electronics cooling. Obtaining the values of heat fluxes corresponding to locally varying surface temperatures has been a challenge limiting most investigations to area-averaged results. This thesis illustrates the importance of a spatially local heat transfer analysis during boiling. Pool and submerged jet impingement boiling scenarios on a silicon surface are considered at the macroscale (27.5 mm heater with multiple nucleation sites) and microscale (1000 [micro]m heater for isolated bubble generation), by the use of two thin film serpentine heater geometries. The macroscale heater highlights the effect of spatial variations in imposed heat flux on boiling heat transfer with a circumferentially uniform but radially non-uniform heat flux distribution. The microscale heater simulates a local hot-spot for spot cooling on an electronic device. Spatial variation in boiling heat transfer and bubble dynamics with and without a jet flow are documented using thin film voltage sensors along with qualitative and quantitative high speed imaging and infra-red thermography. Unique to this study is the documentation of local boiling curves for different radial locations on the heat transfer surface and their comparison with the corresponding area-averaged representations. It is shown here that sectionally averaged representations of boiling curves over regions of like-imposed heat flux can substantially simplify the interpretation of data while retaining important information of the local variations in heat transfer. The radial influence of the convective jet flow on the bubble dynamics and boiling heat transfer is assessed for a single circular submerged jet configuration. Varied parameters include jet exit Reynolds numbers, nozzle geometry, test fluid (deionized water and FC-72), fluid subcooling and the supplied heat flux. Distinct modifications of the surface temperature distribution imposed by the impinging jet flow are highlighted by comparing radial temperature profiles during pool and jet impingement boiling. It is demonstrated that in contrast with pool boiling, thermal overshoots during jet impingement boiling for a highly wetting fluid like FC-72 are highest in regions farthest from the impingement point. The effect of jet inertia on bubble departure characteristics are compared with pool boiling under subcooled conditions for FC-72. Qualitative high speed visualization indicates the presence of two modes of bubble generation during jet impingement boiling (a) bubble departure from the surface and (b) bubble separation from the source resulting in sliding bubbles over the surface. The effect of jet flow on bubble entrainment is depicted. Quantitative results indicate that in general departure diameters for pool and jet impingement boiling increase and plateau at a maximum value with increasing power input while no notable trends were observed in the corresponding departure frequencies. The largest departure diameters for jet impingement boiling at fixed fluid subcoolings of 10°C and 20°C were found to be smaller than that for the corresponding pool boiling test by a factor of 1.6 and 2.3, respectively.

Download or read book Heat Transfer in Electronics 1989 written by R. K. Shah and published by . This book was released on 1989 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Investigation of Single Phase and Boiling Jet Impingement Heat Transfer written by Sanjeev K. Hingorani and published by . This book was released on 1996 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Boiling Heat Transfer And Two Phase Flow written by L S Tong and published by CRC Press. This book was released on 1997-02-01 with total page 582 pages. Available in PDF, EPUB and Kindle. Book excerpt: Completely updated, this graduate text describes the current state of boiling heat transfer and two-phase flow, in terms through which students can attain a consistent understanding. Prediction of real or potential boiling heat transfer behaviour, both in steady and transient states, is covered to aid engineering design of reliable and effective systems.

Download or read book Advances in Electronic Packaging written by and published by . This book was released on 1993 with total page 674 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Heat Transfer and Fluid Flow in Minichannels and Microchannels written by Satish Kandlikar and published by Elsevier. This book was released on 2006 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt: &Quot;This book explores flow through passages with hydraulic diameters from about 1 [mu]m to 3 mm, covering the range of minichannels and microchannels. Design equations along with solved examples and practice problems are also included to serve the needs of practicing engineers and students in a graduate course."--BOOK JACKET.

Download or read book Journal of Electronic Packaging written by and published by . This book was released on 1994 with total page 338 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.