Study on Nucleate Boiling Heat Transfer by Measuring Instantaneous Surface Temperature Distribution by Infrared Radiation Camera

2014 ◽  
Author(s):  
Yasuo Koizumi ◽  
Kazuki Takahashi
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Surface Temperature ◽  
Infrared Radiation ◽  
Boiling Heat Transfer ◽  
Nucleate Boiling ◽  
Surface Temperature Distribution ◽  
Nucleate Boiling Heat Transfer

Study on Nucleate Boiling Heat Transfer by Measuring Detailed Surface Temperature Distribution and Variation With Infrared Radiation Camera

2014 ◽  
Author(s):  
Kazuki Takahashi ◽  
Yasuo Koizumi
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Temperature Distribution ◽  
Surface Temperature ◽  
Infrared Radiation ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Heat Transfer Surface ◽  
Bubble Generation ◽  
Test Vessel

Pool boiling heat transfer experiments were performed for water at 101 kPa to examine elementary process of nucleate pool boiling. The heat transfer surface was made from a copper printed circuit board. The size of the heat transfer surface was 10 mm × 10 mm. Direct current was supplied to the heat transfer surface to heat it up. The Bakelite plate of the backside of the copper layer was taken off at the center portion of the heat transfer surface. The test vessel was a closed 200-mm cube container made of duralumin. It has transparent view windows on opposing side walls made of a Polycarbonate plate to observe a boiling state. Heat transfer surface was placed at the bottom of the test vessel. Distilled water was used for the experiments. The instantaneous variation of the backside temperature of the heat transfer surface was measured with an infrared radiation camera. Bubble behavior was recorded with a high speed video camera. The time and the space resolution of the infrared radiation cameras used in present experiments were 60 Hz and 0.1 mm × 0.1 mm, and 120 Hz and 0.315 mm × 0.315 mm, respectively. When the heat flux was increased, the instantaneous surface temperature variation explain the pattern. In the isolated bubble region, surface temperature was uniform during waiting time. When boiling bubble generation started, a large dip in the surface temperature was formed under the bubble. After the bubble left from the heat transfer surface, the surface temperature returned to former uniform temperature distribution. Surface temperature was not affected by the bubble generation beyond 1.8 mm from the center of the bubble. In the intermediate and high heat flux region, the variation of surface temperature and heat flux were small. Rather the heat flux variation range was close to that at the isolated boiling region.

Study on Nucleate Boiling Heat Transfer by Measuring Spatially Instantaneous Local Surface Temperature and Observing Instantaneous Bubble/Liquid Fluid Behavior

2013 ◽  
Author(s):  
Yasuo Koizumi ◽  
Kenta Hayashi
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Surface Temperature ◽  
Critical Heat Flux ◽  
Boiling Heat Transfer ◽  
Nucleate Boiling ◽  
Heat Transfer Surface ◽  
Bubble Generation ◽  
Three Phase ◽  
Nucleate Boiling Heat Transfer

Pool nucleate boiling heat transfer experiments were performed for water at 0.101 MPa to examine the elementary process of the nucleate boiling. Heat transfer surface was made from a copper printed circuit board. Direct current was supplied to heat it up. The Bakelite plate of the backside of a copper layer was taken off at the center portion of the heat transfer surface. The instantaneous variation of the backside temperature of the heat transfer surface was measured with an infrared radiation camera. Bubble behavior was recorded with a high speed video camera. In the isolated bubble region, surface temperature was uniform during waiting time. When boiling bubble generation started, a large dip in the surface temperature was formed under the bubble. After the bubble left from the heat transfer surface, the surface temperature returned to former uniform temperature distribution. Surface temperature was not affected by the bubble generation beyond 1.6 mm from the center of the bubble. In the isolated bubble region, a convection term was approximately 80 % in total heat transfer rate. The importance of the three-phase interface line in the heat transfer should be checked carefully. In the intermediate and high heat flux region, the variation of surface temperature and heat flux were small. Rather those were close to their average values even at critical heat flux condition. It seemed that the large part of the heat transfer surface was covered with water even at the critical heat flux condition. The heat flux at the area that appeared to be the three-phase contact line was not so high and close to the average heat flux.

Pool Nucleate Boiling on Heat Transfer Surface With Deposited Sea Salts

2016 ◽  
Author(s):  
Shinichiro Uesawa ◽  
Yasuo Koizumi ◽  
Mitsuhiko Shibata ◽  
Hiroyuki Yoshida
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Surface Temperature ◽  
Boiling Heat Transfer ◽  
Nucleate Boiling ◽  
Heat Transfer Surface ◽  
Artificial Seawater ◽  
Distilled Water ◽  
Nacl Solution ◽  
Nucleate Boiling Heat Transfer

Pool nucleate boiling heat transfer experiments of the 3.5 - 10wt% NaCl solution, the real seawater and the 3.5 - 10wt% artificial seawater solution as well as distilled water for the basis of comparison were performed to examine the effect of salts on boiling heat transfer. Seawater was injected into the reactor cores in the accident at the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Company. This study intended to provide base data to consider reactor core cooling by seawater. Boiling curves of the 3.5 - 10wt% NaCl solution, the real seawater and the 3.5 - 10wt% artificial seawater solutions as well as distilled water were well predicted with the Rohsenow pool nucleate boiling heat transfer correlation although the curves were a little shifted to the higher wall superheat region. The formation of secondary coalescent large bubble was suppressed in the experiments of the NaCl solutions, real seawater and the artificial seawater solutions, and small primary bubbles detached directly from the heat transfer surface. Sea salt deposition was observed only in the experiments of the 7.0wt% and 10wt% artificial seawater solutions. The deposited salt was calcium sulfate. Slow heat transfer surface temperature excursion occurred in the experiments of the 7.0wt% and 10wt% artificial seawater solutions after the heat flux was raised to 600 kW/m2 and 120 kW/m2, respectively. The critical heat flux of the 7.0wt% and 10wt% artificial seawater solutions were 600 kW/m2 and 120 kW/m2, respectively if the occurrence of the slow heat transfer surface temperature excursion was defined as the critical heat flux condition. The heat transfer surface temperature excursion might be caused by the growth of the deposited salt layer.

Nucleate Boiling Heat Transfer Under Liquid Jet Impingement

2007 ◽  
Author(s):  
Ahmed M. T. Omar ◽  
M. S. Hamed ◽  
M. Shoukri
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Surface Temperature ◽  
Boiling Heat Transfer ◽  
Jet Impingement ◽  
Nucleate Boiling ◽  
Coolant Temperature ◽  
Liquid Jet ◽  
Planar Jet ◽  
Nucleate Boiling Heat Transfer

Liquid jet impingement is a very effective way of cooling of simple and complicated geometry objects. The attainable cooling rate is radically enhanced when using liquids as coolant due to the possibility of having boiling to occur during the impingement process. Bubble activity on the surface and the resulted mixing with the fluid bulk produces an additional factor of enhancement which at some levels of surface temperature dominates other convective mechanism due to the coolant flow perpendicular or parallel to the surface. The efficient nucleate boiling heat transfer regime can be divided into: partial nucleate boiling and fully developed nucleate boiling. The heat transfer capacity of each and the range of surface temperature over which each of these two boiling regimes up to the critical heat flux (CHF) are experimentally investigated in this research for different coolant temperature and velocity. For this purpose, single planar jet is used to provide the cooling medium of a flat surface that is being heated steadily. The boiling surface temperature was thus controlled by a feed back computer program to allow for steady state operation. So, at each level of boiling surface temperature observation of boiling mode and heat transfer mechanisms was elongated and verified. The experiments were conducted using degassed water jet velocity range between 0.75 and 1.7 m/s and degree of sub-cooling range from 10 to 28 °C at atmospheric pressure. The variation of the heat flux with those factors at different surface superheat up to the CHF point is presented. A physical interpretation is introduced to explain the effects of the input parameters on the heat transfer changes in these regimes.

An Overview: Analysis of Heat and Mass Transfer in Fractal Media by Fractal Geometry and Technique

2010 ◽  
Author(s):  
Boming Yu
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Porous Media ◽  
Heat And Mass Transfer ◽  
Oil Recovery ◽  
Fractal Geometry ◽  
Boiling Heat Transfer ◽  
Nucleate Boiling ◽  
Fractal Media ◽  
Nucleate Boiling Heat Transfer

In the past three decades, fractal geometry and technique have received considerable attention due to its wide applications in sciences and technologies such as in physics, mathematics, geophysics, oil recovery, material science and engineering, flow and heat and mass transfer in porous media etc. The fractal geometry and technique may become particularly powerful when they are applied to deal with random and disordered media such as porous media, nanofluids, nucleate boiling heat transfer. In this paper, a summary of recent advances is presented in the areas of heat and mass transfer in fractal media by fractal geometry technique. The present overview includes a brief summary of the fractal geometry technique applied in the areas of heat and mass transfer; thermal conductivities of porous media and nanofluids; nucleate boiling heat transfer. A few comments are made with respect to the theoretical studies that should be made in the future.

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