Author: F. DemirayPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Heat Transfer from a Single Bubble Nucleation Site During Saturated Pool Boiling of FC-72 Using an Array of 100 Micron Heaters
Author: F. DemirayLiquid-Vapor Phase-Change Phenomena
Author: Van P. CareyPublisher: CRC Press
ISBN: 1498716636
Category : Science
Languages : en
Pages : 731
Book Description
Since the second edition of Liquid-Vapor Phase-Change Phenomena was written, research has substantially enhanced the understanding of the effects of nanostructured surfaces, effects of microchannel and nanochannel geometries, and effects of extreme wetting on liquid-vapor phase-change processes. To cover advances in these areas, the new third edition includes significant new coverage of microchannels and nanostructures, and numerous other updates. More worked examples and numerous new problems have been added, and a complete solution manual and electronic figures for classroom projection will be available for qualified adopting professors.
Proceedings of the 2003 ASME Summer Heat Transfer Conference
Author: Space Technology and Applications International Forum - STAIF 2004
Author: American Institute of PhysicsPublisher: American Institute of Physics
ISBN:
Category : Science
Languages : en
Pages : 1292
Book Description
Albuquerque, New Mexico, 8-11 February 2004
Pool Boiling Heat Transfer from Porous-coated Surfaces in FC-72, the Effects of Subcooling and Non-boiling Immersion Time
Author: Kuiyan XuPublisher:
ISBN:
Category : Ebullition
Languages : en
Pages : 188
Book Description
Microelectromechanical Systems
Author: Publisher:
ISBN:
Category : Electromechanical devices
Languages : en
Pages : 766
Book Description
Fundamental Study of FC-72 Pool Boiling Surface Temperature Fluctuations and Bubble Behavior
Author: Alison R. GriffinPublisher:
ISBN:
Category : Nucleate boiling
Languages : en
Pages : 117
Book Description
A heater designed to monitor surface temperature fluctuations during pool boiling experiments while the bubbles were simultaneously being observed has been fabricated and tested. The heat source was a transparent indium tin oxide (ITO) layer commercially deposited on a fused quartz substrate. Four copper-nickel thin film thermocouples (TFTCs) on the heater surface measured the surface temperature, while a thin layer of sapphire or fused silica provided electrical insulation between the TFTCs and the ITO. The TFTCs were micro-fabricated using the liftoff process to deposit the nickel and copper metal films. The TFTC elements were 50 [micrometers] wide and overlapped to form a 25 [micrometers] by 25 [micrometers] junction. TFTC voltages were recorded by a DAQ at a sampling rate of 50 kHz. A high-speed CCD camera recorded bubble images from below the heater at 2000 frames/second. A trigger sent to the camera by the DAQ synchronized the bubble images and the surface temperature data. As the bubbles and their contact rings grew over the TFTC junction, correlations between bubble behavior and surface temperature changes were demonstrated. On the heaters with fused silica insulation layers, 1-2° C temperature drops on the order of 1 ms occurred as the contact ring moved over the TFTC junction during bubble growth and as the contact ring moved back over the TFTC junction during bubble departure. These temperature drops during bubble growth and departure were due to microlayer evaporation and liquid rewetting the heated surface, respectively. Microlayer evaporation was not distinguished as the primary method of heat removal from the surface. Heaters with sapphire insulation layers did not display the measurable temperature drops observed with the fused silica heaters. The large thermal diffusivity of the sapphire compared to the fused silica was determined as the reason for the absence of these temperature drops. These findings were confirmed by a comparison of temperature drops in a 2-D simulation of a bubble growing over the TFTC junction on both the sapphire and fused silica heater surfaces. When the fused silica heater produced a temperature drop of 1.4° C, the sapphire heater produced a drop of only 0.04° C under the same conditions. These results verified that the lack of temperature drops present in the sapphire data was due to the thermal properties of the sapphire layer. By observing the bubble departure frequency and site density on the heater, as well as the bubble departure diameter, the contribution of nucleate boiling to the overall heat removal from the surface could be calculated. These results showed that bubble vapor generation contributed to approximately 10% at 1 W/cm2, 23% at 1.75 W/cm2, and 35% at 2.9 W/cm2 of the heat removed from a fused silica heater. Bubble growth and contact ring growth were observed and measured from images obtained with the high-speed camera. Bubble data recorded on a fused silica heater at 3 W/cm2, 4 W/cm2, and 5 W/cm2 showed that bubble departure diameter and lifetime were negligibly affected by the increase in heat flux. Bubble and contact ring growth rates demonstrated significant differences when compared on the fused silica and sapphire heaters at 3 W/cm2. The bubble departure diameters were smaller, the bubble lifetimes were longer, and the bubble departure frequency was larger on the sapphire heater, while microlayer evaporation was faster on the fused silica heater. Additional considerations revealed that these differences may be due to surface conditions as well as differing thermal properties. Nucleate boiling curves were recorded on the fused silica and sapphire heaters by adjusting the heat flux input and monitoring the local surface temperature with the TFTCs. The resulting curves showed a temperature drop at the onset of nucleate boiling due to the increase in heat transfer coefficient associated with bubble nucleation. One of the TFTC locations on the sapphire heater frequently experienced a second temperature drop at a higher heat flux. When the heat flux was started from 1 W/cm2 instead of zero or returned to zero only momentarily, the temperature overshoot did not occur. In these cases sufficient vapor remained in the cavities to initiate boiling at a lower superheat.
The Heat Transfer Mechanisms During Saturated Pool Boiling of FC-72
Author: Fatih DemirayHydrodynamic Aspects of Boiling Heat Transfer
Author: N. ZuberExperiments on the Mechanism of Saturated Nucleate Pool Boiling Heat Transfer
Author: Bruce David MarcusPublisher:
ISBN:
Category : Heat
Languages : en
Pages : 444
Book Description