Experimental Investigation of Critical Heat Flux and Boiling-Bubble Behavior in Saturated Flow Boiling under Vibration Condition

2016 ◽  
Vol 2016.21 (0) ◽  
pp. A233
Author(s):  
Tomonobu Nara ◽  
Hiroyasu Ohtake ◽  
Koji Hasegawa ◽  
Junpei Ogawa
Keyword(s):  
Heat Flux ◽  
Experimental Investigation ◽  
Critical Heat Flux ◽  
Flow Boiling ◽  
Bubble Behavior ◽  
Saturated Flow ◽  
Vibration Condition

Development of an Experimental Facility for Investigating Critical Heat Flux of Saturated Flow Boiling of Refrigerant-123 in Microchannels

2005 ◽  
Author(s):  
Wai Keat Kuan ◽  
Satish G. Kandlikar
Keyword(s):  
Heat Flux ◽  
Critical Heat Flux ◽  
Flow Boiling ◽  
Test Facility ◽  
Uniform Heat Flux ◽  
Inlet Temperature ◽  
Experimental Facility ◽  
Copper Block ◽  
Saturated Flow ◽  
Cartridge Heater

An experimental facility is developed to investigate critical heat flux (CHF) of saturated flow boiling of Refrigerant-123 (R-123) in microchannels. Six parallel Microchannels with cross sectional area of 0.2 mm × 0.2 mm are fabricated on a copper block, and a Polyvinyl Chloride (PVC) cover is then placed on top of the copper block to serve as a transparent cover through which flow patterns and boiling phenomena could be observed. A resistive cartridge heater is used to provide a uniform heat flux to the microchannels. The experimental test facility is designed to accommodate test sections with different microchannel geometries. The mass flow rate, inlet pressure, inlet temperature of Refrigerant-123, and the electric current supplied to the resistive cartridge heater are controlled to provide quantitative information near the CHF condition in microchannels. A high-speed camera is used to observe and interpret flow characteristics of CHF condition in microchannels.

Critical heat flux enhancement on a downward face using porous honeycomb plate in saturated flow boiling

2017 ◽  
Vol 109 ◽  
pp. 454-461 ◽  
Author(s):  
Laishun Wang ◽  
Abdul R. Khan ◽  
Nejdet Erkan ◽  
Haiguang Gong ◽  
Koji Okamoto
Keyword(s):  
Heat Flux ◽  
Critical Heat Flux ◽  
Flow Boiling ◽  
Saturated Flow ◽  
Flux Enhancement

Critical heat flux prediction for saturated flow boiling of water in vertical tubes

2001 ◽  
Vol 44 (22) ◽  
pp. 4323-4331 ◽  
Author(s):  
Gian Piero Celata ◽  
Kaichiro Mishima ◽  
Giuseppe Zummo
Keyword(s):  
Heat Flux ◽  
Critical Heat Flux ◽  
Flow Boiling ◽  
Saturated Flow ◽  
Vertical Tubes

scholarly journals Pre- and Post-Critical Heat Flux Analyses in a Saturated Refrigerant Flow Boiling System

2012 ◽  
Author(s):  
TieJun Zhang ◽  
Juan Catano ◽  
Evelyn N. Wang ◽  
Michael K. Jensen
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Critical Heat Flux ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Transition Flow ◽  
Saturated Flow ◽  
Renewable Power ◽  
Boiling Hysteresis ◽  
Hot Weather

Vapor compression refrigeration (VCR) cooling has been identified as a promising solution to ensure the low-temperature sustainable operation of photonics, avionics and electronics in extreme hot weather. With the inherent benefits of saturated flow boiling in a direct VCR cooling cycle, uniform low surface temperature and low solid/liquid thermal resistances can be achieved. However, flow boiling heat transfer performance is limited by the relatively low critical heat flux (CHF) condition because the evaporator inlet flow is already a liquid/vapor mixture. Moreover, for the aforementioned applications, the dissipated heat loads are usually subject to large and transient changes, which could easily cause the evaporating flow to exceed the CHF point. Therefore, it is important to characterize boiling heat transfer in transient VCR evaporators under both pre-CHF and post-CHF conditions. Comprehensive experimental data are reported in this paper to describe the complete forced convection boiling hysteresis at the evaporator exit. Several well-known boiling heat transfer correlations and flow pattern criteria are used to help understand the physics of the hysteresis. An empirical model is developed to reveal the unstable nature of transition flow boiling dynamics. A probability distribution function model is further proposed to predict the droplet size in mist flow and vapor core of annular flow. This study provides more design and operating guidelines for the application of saturated flow boiling systems in renewable power generation and electronics/photonics/avionics cooling industries.

Study on Saturated Flow Boiling Heat Transfer Under Vibration Conditions

2012 ◽  
Author(s):  
Yoshitaro Fujiyama ◽  
Hiroyasu Ohtake
Keyword(s):  
Heat Flux ◽  
Critical Heat Flux ◽  
Test Section ◽  
Low Voltage ◽  
Flow Boiling ◽  
Heating Surface ◽  
Nucleate Boiling ◽  
Circuit Board ◽  
Vertical Position ◽  
Saturated Flow

The ability to predict void formation, void fraction and critical heat flux —CHF— in flow boiling under oscillatory flow and vibration conditions is important to the safety technology of nuclear reactor during earthquake. In the present study, the onset of nucleate boiling —ONB— and CHF on saturated flow boiling under vibration conditions were investigated experimentally. Steady state experiments were conducted using a copper thin-film and saturated and subcooled water at 0.1 MPa. The liquid velocity was 0.25, 1.38, 3.20 and 4.07 m/s, respectively; the liquid subcooling was 0 K and 20 K. A heater was made of a printed circuit board. A test section was a rectangular flow channel of 10 mm width and 10 mm height. The test heater was heated by Joule heating of d.c. current from a low-voltage high-current stabilizer. The heating rate of the heater was determined from supplied current and voltage. The temperature of the heater was obtained by referring to the measured electric resistance. The test section was arranged for horizontal position facing upward and for vertical position, respectively. For the vibration condition, the test section was set on a vibration table. The ONB was decided as an occurrence of the first boiling bubble. The critical heat flux was determined as that immediately before the heating surface physically burned-out. The CHF on saturated flow boiling under vibration conditions were investigated experimentally.

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