Experimental Investigation of the Transient Pool Boiling Heat Transfer On the Quenching of Vertical Rodlet in Water

Abstract Quenching is an important phenomenon in the evaluation of an emergency core cooling system following a hypothetical loss of coolant accident (LOCA) in a nuclear reactor. In the present study, an experimental apparatus is designed and constructed with the purpose of conducting high-temperature transient pool boiling quenching experiments for zirconium (Zr-4) cylindrical test samples. Three thermocouples are inserted in the test sample to investigate the effect of axial distance on the minimum film boiling temperature. The Zr-4 rodlet is heated up to a temperature well above the minimum film boiling temperature (up to 600?), and then plunged vertically in a quiescent pool of subcooled water. A data acquisition system is used to record the temperature of the embedded thermocouples with time. Data reduction is performed by an inverse heat conduction code to calculate the surface temperature and corresponding surface heat flux. A visualization study with a high-speed camera is conducted to record the quenching behavior on the test sample. It is found that the minimum film boiling temperature decreases with the axial distance, while the CHF temperature is relatively insensitive to the axial distance. The film boiling heat transfer coefficient decreases with surface temperature, and seems to be independent of axial distance. The quench front is observed to originate from the bottom and move upwards. It is found that the quench front velocity remains nearly constant in the lower region of the test sample, and significantly increases in the upper region.

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Experimental Investigation of the Transient Pool Boiling Heat Transfer on the Quenching of Vertical Rodlet in Water

Volume 3: Student Paper Competition; Thermal-Hydraulics; Verification and Validation ◽

10.1115/icone2020-16709 ◽

2020 ◽

Author(s):

Zefeng Wang ◽

Jian Deng ◽

Libo Qian ◽

Rong Cai ◽

Jinbiao Xiong ◽

...

Keyword(s):

Heat Transfer ◽

Surface Temperature ◽

Boiling Heat Transfer ◽

Cooling System ◽

Pool Boiling ◽

Test Sample ◽

Boiling Temperature ◽

Film Boiling ◽

Axial Distance ◽

Experimental Apparatus

Abstract Quenching is an important phenomenon in the evaluation of an emergency core cooling system following a hypothetical loss of coolant accident (LOCA) in a nuclear reactor. In the present study, an experimental apparatus is designed and constructed with the purpose of conducting high-temperature transient pool boiling quenching experiments for zirconium (Zr-4) cylindrical test samples. Three thermocouples are inserted in the test sample to investigate the effect of axial distance on the minimum film boiling temperature. The Zr-4 rodlet is heated up to a temperature well above the minimum film boiling temperature (up to 600°C), and then plunged vertically in a quiescent pool of subcooled water. A data acquisition system is used to record the temperature of the embedded thermocouples with time. Data reduction is performed by an inverse heat conduction code to calculate the surface temperature and corresponding surface heat flux. A visualization study with a high-speed camera is conducted to record the quenching behavior on the test sample. It is found that the minimum film boiling temperature decreases with the axial distance, while the CHF temperature is relatively insensitive to the axial distance. The film boiling heat transfer coefficient decreases with surface temperature, and seems to be independent of axial distance. The quench front is observed to originate from the bottom and move upwards. It is found that the quench front velocity remains nearly constant in the lower region of the test sample, and significantly increases in the upper region.

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Effects of Coolant Flow Characteristics and Channel Surface Temperature on Nucleate Boiling Heat Transfer in IC Engine Cooling System

International Journal of Automotive Engineering ◽

10.20485/jsaeijae.11.4_143 ◽

2020 ◽

Vol 11 (4) ◽

pp. 143-150

Author(s):

Haoyu Chen ◽

Emir Yilmaz ◽

Koki Asano ◽

Ryota Shindo ◽

Ayumi Homma ◽

...

Keyword(s):

Heat Transfer ◽

Surface Temperature ◽

Boiling Heat Transfer ◽

Cooling System ◽

Flow Characteristics ◽

Nucleate Boiling ◽

Ic Engine ◽

Engine Cooling ◽

Channel Surface ◽

Nucleate Boiling Heat Transfer

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Pool Boiling Heat Transfer of Highly Wetting Fluids on Smooth Metallic Surfaces

ASME/JSME 2011 8th Thermal Engineering Joint Conference ◽

10.1115/ajtec2011-44045 ◽

2011 ◽

Author(s):

Bradley Bon ◽

James Klausner

Keyword(s):

Heat Transfer ◽

Single Crystal ◽

Boiling Heat Transfer ◽

Metal Surfaces ◽

Pool Boiling ◽

Silicon Surfaces ◽

Film Boiling ◽

Metallic Surfaces ◽

Pool Boiling Heat Transfer ◽

Wetting Fluids

The nucleate pool boiling heat transfer characteristics of smooth metallic surfaces were investigated using two highly wetting fluids. Perfluoro-n-hexane and n-hexane were chosen as the test fluids. Two single crystal metal surfaces (Copper and Aluminum) of two different crystal plane orientations in addition to two polycrystalline metal surfaces (Nickel and Titanium) were studied. Three different orientations of a non-metal surface (Silicon) were also studied. Heat transfer is seen to increase with increasing thermal conductivity for both single crystal and polycrystalline surfaces. For the single crystal metal surfaces, heat transfer slightly increases with decreasing planar density. For the silicon surfaces heat transfer increases with increasing planar density. Film boiling at incipience was observed for some of the surfaces. A plausible criterion for predicting the onset of film boiling at incipience is discussed.

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

Volume 8B: Heat Transfer and Thermal Engineering ◽

10.1115/imece2014-37448 ◽

2014 ◽

Cited By ~ 1

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.

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