Experimental Study of Direct Contact Condensation in the Presence of Noncondensable Gas

2002 ◽  
Author(s):  
Yiban Xu ◽  
Shripad T. Revankar ◽  
Mamoru Ishii
Keyword(s):  
Bubble Size ◽  
Direct Contact ◽  
High Speed ◽  
Size Variation ◽  
Saturated Steam ◽  
Dimensionless Numbers ◽  
Noncondensable Gas ◽  
Digital Format ◽  
System Pressure ◽  
Contact Condensation

A series of direct contact condensation tests of mixture of saturated steam and nitrogen has been carried out in a subcooled pool of water. Nitrogen is used as the noncondensable gas. A mixture of nitrogen and steam is discharged into the subcooled water pool through a vertical nozzle. The apparatus is equipped with appropriate instruments and flow visualization. Pre-heaters and super-heaters are used to heat up nitrogen and steam before they are mixed. Tests have been preformed with variations of the liquid temperature, system pressure, nozzle size and the concentration of noncondensable gas. Images of bubble behaviors are captured with high speed video camera and downloaded into a PC in digital format. Information on bubble size variation and formation frequency is obtained from the image analysis. Detaching bubble size, surface area and frequency are correlated with the various dimensionless numbers.

Experimental Study on Chugging Condensation Regime of Steam Direct Contact Condensation in Water Flow in a Tee Junction

2017 ◽  
Author(s):  
Wang Jie ◽  
Lu Tao ◽  
Liu Bo
Keyword(s):  
Water Flow ◽  
Direct Contact ◽  
High Speed ◽  
Branch Pipe ◽  
Phase Interface ◽  
Nuclear Industry ◽  
Saturated Steam ◽  
Two Phase ◽  
Tee Junction ◽  
Contact Condensation

The phenomenon of direct contact condensation (DCC) is encountered in both the nuclear industry and conventional industry and it is intimately associated with safety operation of relevant equipment. Studies on steam jet discharged directly into a stagnant water pool have been studied extensively; however, they are sparse for direct contact condensation of steam in sub-cooled water in pipes. In this paper, the experiments were performed to study the direct contact condensation of low mass flux saturated steam discharged into sub-cooled water flow in a Tee junction. By using high-speed camera, we investigated chugging condensation characteristics including two-phase interface movements. It is can be seen from the experiment results that, for chugging, steam plume and surrounding sub-cooled water undergo the following process: steam plume grows to the maximum, then steam plume becomes smaller due to condensation, and finally, water enters the vertical branch pipe and steam ejects from the vertical branch pipe again.

Heat Transfer Study of Direct Contact Condensation in the Presence of Noncondensable Gas

2002 ◽  
Author(s):  
Yiban Xu ◽  
Shripad T. Revankar ◽  
Mamoru Ishii
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Direct Contact ◽  
Bubble Formation ◽  
Density Ratio ◽  
Size Variation ◽  
Least Square ◽  
Dimensionless Numbers ◽  
Flow Rates ◽  
Contact Condensation

Direct Contact Condensation tests have been conducted by injecting a mixture of steam and nitrogen into a subcooled water pool in a stainless steel tank through a vertical nozzle. The condensation rate, related to the heat transfer rate in the liquid side, was obtained by the difference of the gas inlet flow rates and the mass accumulation due to the bubble growth. By the measurements of steam and nitrogen flow rates and visualization of the bubble size variation, the heat transfer parameters in the liquid domain during the bubble formation, are obtained. The Nusselt number has been correlated with the dimensionless combination of fluid flow, system state and thermal properties of fluids. A least square approach has been applied to determine the exponent coefficients of dimensionless numbers in the correlations. It was found that the Nusselt number can be correlated by a function of the Jakob number, gas Peclet number, noncondensable concentration, liquid and gas density ratio and Eotvos number based on the current database.

Vapor Bubble Condensation Characteristics of Subcooled Flow Boiling in Vertical Rectangular Channel

2012 ◽  
Author(s):  
Zhi-wei Tan ◽  
Liang-ming Pan
Keyword(s):  
Bubble Size ◽  
Vapor Bubble ◽  
Large Scale ◽  
Flow Boiling ◽  
Rectangular Channel ◽  
Size Variation ◽  
Transfer Model ◽  
Bubble Deformation ◽  
Initial Diameter ◽  
System Pressure

In this study, the behavior of condensing single vapor bubble in subcooled boiling flow within two different vertical rectangular channels has been numerically investigated by using the VOF (Volume of Fluid) multiphase flow model. The mass and energy transfer model of bubble condensing process induced from the interfacial heat transfer was proposed to describe the interfacial transportation between the two phases. The results of VOF simulations showed good agreements with previous experimental data in the bubble size variation and lifetime. The bubble lifetime was almost proportional to bubble initial size and prolonged by system pressure. With the increase of subcooling, the bubble lifetime reduces significantly, and the effect of mass flux could be negligible. When bubble size increased, the bubble shape tends to be changed in a large-scale channel. The VOF simulation results of deformation have good agreement with those of Kamei’ experiment and the results of MPS (Moving Particle Semi-implicit) simulation in the large-scale channel. Furthermore, the initial bubble size, subcooling of liquid and system pressure play an important role to influence the bubble deformation behaviors significantly. The bubble could deform sharper with the increase of subcooling and initial diameter, or could breakup when the subcooling and the initial diameter reached a certain value at the last bubble stage. Whereas the trend of bubble deformation would be weaken with the increase of system pressure.

Plume Stability During Direct Contact Condensation of Steam in a Crossflow of Subcooled Water, At High Mass Flux and with a Small Nozzle Diameter

2021 ◽  
Author(s):  
Zach Alden ◽  
Gunnar Maples ◽  
Kristofer M. Dressler ◽  
Gregory Nellis ◽  
Arganthaël Berson
Keyword(s):  
Direct Contact ◽  
High Speed ◽  
Nozzle Diameter ◽  
High Mass ◽  
High Speed Imaging ◽  
Subcooled Water ◽  
Mass Fluxes ◽  
The Stability ◽  
Regime Map ◽  
Contact Condensation

Abstract The stability of a steam plume during direct-contact condensation is investigated into a crossflow of subcooled water with mass fluxes that are higher (>600 kg/m2s) and a nozzle diameter (2.4 mm) that is smaller than typically seen in the literature. The transition from a stable steam plume to an unstable plume associated with the formation and collapse of steam bubbles is characterized by high-speed imaging and high-frequency pressure measurements. Four regimes are observed: stable, condensation oscillation, transition, and unstable. A regime map and spectral signatures of the different flow regimes are provided. Results are compared with correlations from the literature, which are typically derived for lower mass fluxes, larger nozzles, and injection into stagnant pools of water.

Study on Turbulent Behavior of Water Jet in Supersonic Steam Injector

2008 ◽  
Author(s):  
Akira Fukuichi ◽  
Yutaka Abe ◽  
Akiko Fujiwara ◽  
Yujiro Kawamoto ◽  
Chikako Iwaki ◽  
...  
Keyword(s):  
Shear Stress ◽  
Turbulent Flow ◽  
Momentum Transfer ◽  
Total Pressure ◽  
Direct Contact ◽  
High Speed ◽  
Flow Behavior ◽  
Water Jet ◽  
High Efficient ◽  
Contact Condensation

One of the most interesting devices for Next-generation nuclear reactor systems aimed at simplified system, improvement of safety and credibility is a supersonic steam injector. Supersonic steam injector is a passive jet pump without rotating machine and high efficient heat exchanger because of the direct contact condensation between the supersonic steam and the subcooled water jet. It is considered that flow behavior in the supersonic steam injector is governed by the complicated turbulent flow with large shear stress induced by velocity difference between the steam and water and direct contact condensation. There are various studies about formulation of operating characteristic of the steam injector and jet structure in it [1][5]. According to these investigations, heat and momentum transfer of the steam injector are supposed to be related to the turbulent eddy diffusion. However, the studies about the turbulent flow under the large shear stress with direct contact condensation are not enough. Especially mechanisms of the momentum and the heat transfer are not clarified in detail. Objective of the present study is to investigate the turbulent behaviors of the water jet and the interface between the water and the supersonic steam that play an important role in the heat and the momentum transfer. Radial velocity distribution was measured by a special pitot tube. Fluctuation of the total pressure which doesn’t depnd on the density of the fluid is measured by the pitot measurement. It was found that the streamwise velocity increased as it approaches downstream of the injector. Fluctuation of the total pressure is large at the mixing region of the water and the steam. Visual measurement of the turbulent water jet was conducted by high speed camera in order to identify the position of unstable interface and its behavior. It was confirmed that wave propagated on the interface. And its velocity is obtained.

DIRECT CONTACT CONDENSATION OF FLOWING STEAM ONTO INJECTED WATER

1978 ◽  
Author(s):  
Shigebumi Aoki ◽  
Akira Inoue ◽  
Yoshiyuki Kozawa ◽  
H. Akimoto
Keyword(s):  
Direct Contact ◽  
Contact Condensation
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