Investigation on Characteristics of Experiment About Single-Beam Measurements of Supercritical Fluid

2012 ◽  
Author(s):  
Yu Zhao ◽  
Qincheng Bi ◽  
Richa Hu ◽  
Huixiong Li
Keyword(s):  
Physical Characteristics ◽  
Supercritical Pressure ◽  
Upward Flow ◽  
Measuring Time ◽  
Single Beam ◽  
Mass Fluxes ◽  
Pressure Water ◽  
Gamma Densitometer ◽  
Supercritical Pressure Water ◽  
Pseudocritical Point

An experiment has recently been completed at Xi’an Jiaotong University (XJTU) to obtain thermo-physical characteristics of supercritical pressure water at supercritical pressures with upward flow of water inside a vertically-upward bare tube. The thermo-physical characteristics of supercritical pressure water were investigated experimentally by means of a non-intrusive measurement method, using a single-beam gamma densitometer generated from the radioactive sources (Cs-137). The purpose of this experiment is to investigate accurately the changes drastic thermo-physical characteristics process of supercritical pressure water at pseudocritical point, comparing and analyzing in-depth the experiment results at different pressures and mass fluxes. Several factors influencing the performance of the gamma densitometer are examined, including the distance between the source and the detector, the distance between the source and the test section, the measuring time, the intensity of source, and the ambient temperature.

Experimental Study on the Density Wave Oscillations of Supercritical Water in Vertical Upward Tubes

2017 ◽  
Author(s):  
Xiangfei Kong ◽  
Xin Liu ◽  
Kaikai Guo ◽  
Yuan Feng ◽  
Huixiong Li
Keyword(s):  
Thermal Power ◽  
Density Wave ◽  
Supercritical Pressure ◽  
Heat Fluxes ◽  
Internal Diameter ◽  
Wave Oscillation ◽  
Mass Fluxes ◽  
Pressure Water ◽  
Density Wave Oscillations ◽  
Supercritical Pressure Water

Supercritical and ultra-supercritical pressure boilers have been widely used in China because of its advantages of high capability, high thermal efficiency and low pollutants emission. In view of the high working parameters and complicated working conditions of such boilers, safe and stable operations of these boilers have become the focus of attention of related researchers and engineers for many years. As one of the most important phenomena that may occur in thermal power plants, flow instabilities of water in boilers’ water-cooled wall may result in heat transfer deterioration, thermal fatigue of pipes and even breakdown of the supercritical units, and have thus attracted much attention of developers and researchers of the boilers. However, due to difficulties in carrying out experiments on the density wave oscillation of water under supercritical pressures, the related experimental data is very rare, and moreover, the characteristics of density wave oscillations of water under supercritical pressures has not been well understood. A series of experiments have been conducted on the density wave oscillation of water flowing at supercritical pressures in a 6-m long vertical upward tube with 20.0-mm internal diameter. The experimental parameters cover the pressures from 23 to 27 MPa, the mass fluxes from 300 to 600 kg·m−2·s−1, and the heat fluxes from 225 to 500 kW·m−2. Three types of density wave oscillation were found in the present study: 1) stable periodic density wave oscillation, 2) attenuated density wave oscillation, 3) divergent density wave oscillation. Effects of pressures, mass fluxes and heat fluxes on the density wave oscillation were analyzed. With the increase in pressures and mass fluxes, the density wave oscillation of supercritical pressure water can be postponed, and is difficult to occur. And the density wave oscillation will be triggered and enhanced by increasing the heating flux. The mechanism of density wave oscillation of supercritical pressure water in tubes was also analyzed, and a dataset was established for the verification of related numerical calculations and modeling.

Study on the Minimum Drag Coefficient Phenomenon of Supercritical Pressure Water in the Pseudocritical Region

2012 ◽  
Author(s):  
Xianliang Lei ◽  
Huixiong Li ◽  
Shuiqing Yu ◽  
Yifan Zhang ◽  
Tingkuan Chen
Keyword(s):  
Experimental Data ◽  
Pressure Drop ◽  
Drag Coefficient ◽  
Supercritical Pressure ◽  
Pressure Drops ◽  
Minimum Drag ◽  
Wide Range ◽  
Pressure Water ◽  
Isothermal Flows ◽  
Supercritical Pressure Water

With the development of supercritical (and even ultra-supercritical) pressure boilers (SCBs) with high capacities, and at the same time, with the consideration of supercritical pressure water-cooled reactors (SCWRs) as one of the six most promising reactor concepts accepted in the Generation IV International Forum (GIF), flow and heat transfer of supercritical water becomes more and more important for both the design and operation safety of the related facilities. Thermo-hydraulic characteristics are among the issues, which are of special significance for the SCBs and SCWRs. It has been found that at supercritical pressures, the hydraulic resistance of water exhibits special characteristics in regions near its pseudo-critical point, which is hereafter called the minimum drag coefficient phenomenon. Experimental investigation was carried out in the present study to investigate further the characteristics of drag coefficient of supercritical pressure water under different conditions. The total pressure drop characteristic of water flowing in smooth tube and internally ribbed tube under the supercritical pressures was measured in experiments with a wide range of operational parameters, such as the system pressures ranging from 23 to 28 MPa, the average heat fluxes varied from 100 kW/m2 to 500kW/m2, and the mass fluxes of water in a range of 600 ∼ 1050 kg/m2s. The experimental data were compared with prediction results calculated by existing common correlations for single phase pressure drops, and large discrepancies were observed between the experimental data and the prediction results. Furthermore, the pressure drops characteristics of supercritical pressure water in cases with different tube arrangement and test conditions were compared with each other, such as that in horizontal tubes and vertical tubes, and that in isothermal flows and in non-isothermal flows. Additionally, this phenomenon observed in the present studies was also analyzed by using computational fluid dynamics technology, and the mechanism of pressure drop variation was reasonably explained. It was found that the deviation appeared between the previously proposed drag coefficient correlations and the present experimental data was mainly owning to ignoring the variation of an existence of the minimum drag coefficient in the pseudo critical region in previous studies, and based on the data obtained in this study, a new correlation for drag coefficient for supercritical pressure water was presented.

Pseudoboiling Heat Transfer to Supercritical Pressure Water in Smooth and Ribbed Tubes

1970 ◽  
Vol 92 (3) ◽  
pp. 490-497 ◽  
Author(s):  
J. W. Ackerman
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Heated Surface ◽  
Supercritical Pressure ◽  
Heat Fluxes ◽  
Film Boiling ◽  
Fluid Temperature ◽  
Bulk Fluid ◽  
Pressure Water ◽  
Supercritical Pressure Water

Investigations of heat transfer to supercritical pressure fluids have been going on for some time, and correlations have been developed for both free and forced-convection conditions. In these investigations, unpredictable heat transfer performance has sometimes been observed when the pseudocritical temperature of the fluid is between the temperature of the bulk fluid and that of the heated surface. The unusual performance has been attributed to many causes, but one for which more evidence is being collected is that of a pseudofilm-boiling process similar to film boiling which occurs at subcritical pressures. This paper, which is an extension of work reported earlier on forced-convection heat transfer to supercritical pressure water, presents experimental evidence which suggests that a pseudofilm-boiling phenomenon can occur in smooth-bore tubes. During the period from 1963–1966, tubes with ID’s from 0.37 to 0.96 in. were tested at pressures from 3300–6000 psia and at heat fluxes and mass velocities in the range of interest in steam-generator design. The effects of heat flux, mass velocity, tube diameter, pressure, and bulk fluid temperature on both the occurrence and characteristics of pseudofilm boiling are discussed. Results of a second series of tests conducted in 1967, which show that ribbed tubes suppress pseudofilm boiling at supercritical pressure much like they do film boiling at subcritical pressures, are also discussed.

A New Correlation for Heat Transfer Coefficient Prediction of Supercritical Pressure Water Flowing in Vertical Upward Tubes

2016 ◽  
Author(s):  
Xiangfei Kong ◽  
Huixiong Li ◽  
Changjiang Liao ◽  
Xianliang Lei ◽  
Qian Zhang
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Supercritical Pressure ◽  
Good Prediction ◽  
Empirical Correlations ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
New Correlation ◽  
Pressure Water ◽  
Supercritical Pressure Water

Supercritical pressure water has been widely used in many industrial fields, such as fossil-fired power plants and nuclear reactors because mainly of its high thermal efficiencies. Although many empirical correlations for heat transfer coefficients of supercritical pressure water have been proposed by different authors based on different experimental data base, there exist remarkable discrepancies between the predicted heat transfer coefficients of different correlations under even the same condition. Heat transfer correlations with good prediction performance are of considerable significance for developing supercritical (ultra-supercritical) pressure boilers and SCWRs. In this paper, the experimental data (about 7389 experimental data points) and 30 existing empirical correlations for heat transfer of supercritical pressure water (SCW) flowing in vertical upward tubes are collected from the open literatures. Evaluations of the prediction performance of the existing correlations are conducted based on the collected experimental data, and a detailed multi-collinearity analysis has been made on different correction factors involved in the existing correlations, and then based on the collected experimental data, a new heat transfer correlation is developed for the supercritical pressure water flowing in vertical upward tubes under normal and enhanced heat transfer mode. Compared with the existing correlations, the new correlation exhibits good prediction accuracy, with a mean absolute deviation (MAD) of 9.63%.

scholarly journals RESEARCH ACTIVITIES ON A SUPERCRITICAL PRESSURE WATER REACTOR IN KOREA

2007 ◽  
Vol 39 (4) ◽  
pp. 273-286 ◽  
Author(s):  
Yoon-Yeong Bae ◽  
Jin-Sung Jang ◽  
Hwan-Yeol Kim ◽  
Han-Young Yoon ◽  
Han-Ok Kang ◽  
...  
Keyword(s):  
Supercritical Pressure ◽  
Water Reactor ◽  
Research Activities ◽  
Pressure Water ◽  
Supercritical Pressure Water
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