The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Junjie Yan - One of the best experts on this subject based on the ideXlab platform.
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experimental investigation on the condensation regime and Pressure Oscillation characteristics of vertical upward steam jet condensation with low mass flux
Experimental Thermal and Fluid Science, 2020Co-Authors: Qingchuan Yang, Daotong Chong, Binbin Qiu, Weixiong Chen, Jiping Liu, Junjie YanAbstract:Abstract An experimental study was conducted to investigate the condensation regime and Pressure Oscillation characteristics of vertical upward steam jet condensation with low mass flux. Steam mass flux and water temperature were 8.34–16.71 kg/(m2·s) and 40–85 °C, respectively. Steam bubble behavior, Pressure Oscillation amplitude and frequency were recorded and analyzed. Four typical regimes were found, namely, chugging, detached oscillatory, detached cracked and secondary bubble impinged regimes. A bubble condensation region map was developed by considering the effects of steam mass flux and water temperature. The average amplitude of Pressure Oscillation initially increased, and then decreased as water temperature increased. It reached its maximum value when water temperature was approximately 60–65 °C, which was the transition temperature range from the chugging regime to the detached oscillatory regime. Meanwhile, the frequency of Pressure Oscillation was within the range of 12–28 Hz. These values were higher than those for a vertical downward steam jet with the same steam mass flux and water temperature. A dimensionless correlation was obtained to predict the Strouhal number of Pressure Oscillation frequency. The predicted values corresponded well with the experimental data. The deviation was within the range of –9.12% to +8.30%.
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experimental investigation on the condensation patterns and Pressure Oscillation characteristics of steam submerged jet through a horizontal pipe at low steam mass flux
International Journal of Heat and Mass Transfer, 2019Co-Authors: Daotong Chong, Quanbin Zhao, Xiaoyu Yue, Lutao Wang, Junjie YanAbstract:Abstract Steam submerged jet condensation is a direct contact condensation widely used in many industries. However, this process may cause damage to related equipment due to Pressure Oscillation, especially at low steam mass flux. This study synchronously investigated the steam–water interface fluctuation of unstable condensation jet and its corresponding Pressure Oscillation through a horizontal pipe at low steam mass flux to research the condensation Oscillation mechanism. Three typical flow patterns, namely, Chugging, hemispherical bubble Oscillation (HBO), and encapsulating bubble Oscillation (EBO), were distinguished based on the dynamic behavior of steam–water interface and Oscillation Pressure characteristics. Only the dynamic Pressure in EBO region was periodic among the three flow patterns. In the EBO region, the Pressure Oscillation frequency increased with the increase of steam mass flux and decreased with the increase of water temperature. A flow pattern regime map for horizontal jet condensation related to steam mass flux and water temperature was presented based on experiments. Moreover, the influence of pipe diameters on low steam mass flux was analyzed. For the flow pattern regime map at low steam mass flux, the critical steam mass fluxes showed an inverse relationship with pipe diameter. An empirical criterion was introduced to determine the flow regime map at low steam mass flux.
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experimental investigation on the propagation characteristics of Pressure Oscillation in direct contact condensation with low mass flux steam jet
Experimental Thermal and Fluid Science, 2017Co-Authors: Binbin Qiu, Junjie Yan, Shripad T Revankar, Qingchuan YangAbstract:Abstract The propagation characteristics of Pressure Oscillation in direct contact condensation with low mass flux steam jet have been investigated experimentally. Steam is injected into subcooled water at one atmosphere Pressure with steam mass flux and water temperature range of 186–272 kg/(m 2 s) and 293–343 K. The Pressure Oscillation propagates in the form of wave with stable dominant frequency, however the wave intensity attenuates with the increasing distance from the Oscillation source. The root mean square of Pressure wave p rms attenuates rapidly with the increasing dimensionless radial distance from the nozzle exit. At about dimensionless radial distance R = 100, the p rms is attenuated by about 90%. Although the dominant frequency of the Pressure Oscillation is constant during the propagation, after R = 100, there will be not enough energy for the Pressure Oscillation to resonate with relevant equipment. A correlation equation to calculate the root mean square of Pressure Oscillation along the radial distance is given. The prediction errors are within ±30% compared with the experimental data.
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experimental investigation on the mechanism of Pressure Oscillation for steam jet in stable condensation region
Experimental Thermal and Fluid Science, 2017Co-Authors: Binbin Qiu, Daotong Chong, Junjie Yan, Shripad T RevankarAbstract:Abstract The Pressure Oscillations for steam jet in stable condensation region are investigated experimentally. Steam at Pressure 0.2–0.6 MPa is injected into subcooled water at one atmosphere Pressure with steam mass flux ranging from 298 to 865 kg/(m 2 s), with water subcooling from 70 to 40 K. The steam plume shapes have been recorded and are compared with the Pressure Oscillation. The Pressure Oscillation for steam jet in stable condensation region is caused by the Oscillation of steam plume length. When the steam plume length is the longest, the Pressure Oscillation has negative peak value and vice versa. Based on the experimental data and the change of steam plume shapes, a new phenomenological model of Pressure Oscillation is developed. The model also provides a method to obtain the steam plume length using the Pressure Oscillation. The prediction errors of the peak Pressure Oscillation are within ±30% of experimental values.
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Pressure Oscillation and a new method to calculate the heat transfer coefficient for steam jet condensation
International Journal of Heat and Mass Transfer, 2017Co-Authors: Binbin Qiu, Junjie Yan, Shripad T RevankarAbstract:Abstract The Pressure Oscillation and heat transfer are two important aspects for direct contact condensation. Both of them have been investigated within the steam mass flux 441–865 kg/(m2 s) and water temperature 293–343 K in this paper. The frequency of Pressure Oscillation decreases with the increasing steam mass flux and water temperature. While, the frequency first increases then subsequently decreases with the decreasing Pressure ratio of the nozzle. The heat transfer coefficient has the same variation regularities with the frequency of Pressure Oscillation. Two dimensionless quantity of frequency of Pressure Oscillation and heat transfer coefficient have been obtained, the dimensionless heat transfer coefficient is proportional to the dimensionless frequency of Pressure Oscillation. A new simpler method to calculate the heat transfer coefficient for steam jet condensation has been given. The errors between the predicted values and experimental data are within −30% to 25%.
Daotong Chong - One of the best experts on this subject based on the ideXlab platform.
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experimental investigation on the condensation regime and Pressure Oscillation characteristics of vertical upward steam jet condensation with low mass flux
Experimental Thermal and Fluid Science, 2020Co-Authors: Qingchuan Yang, Daotong Chong, Binbin Qiu, Weixiong Chen, Jiping Liu, Junjie YanAbstract:Abstract An experimental study was conducted to investigate the condensation regime and Pressure Oscillation characteristics of vertical upward steam jet condensation with low mass flux. Steam mass flux and water temperature were 8.34–16.71 kg/(m2·s) and 40–85 °C, respectively. Steam bubble behavior, Pressure Oscillation amplitude and frequency were recorded and analyzed. Four typical regimes were found, namely, chugging, detached oscillatory, detached cracked and secondary bubble impinged regimes. A bubble condensation region map was developed by considering the effects of steam mass flux and water temperature. The average amplitude of Pressure Oscillation initially increased, and then decreased as water temperature increased. It reached its maximum value when water temperature was approximately 60–65 °C, which was the transition temperature range from the chugging regime to the detached oscillatory regime. Meanwhile, the frequency of Pressure Oscillation was within the range of 12–28 Hz. These values were higher than those for a vertical downward steam jet with the same steam mass flux and water temperature. A dimensionless correlation was obtained to predict the Strouhal number of Pressure Oscillation frequency. The predicted values corresponded well with the experimental data. The deviation was within the range of –9.12% to +8.30%.
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experimental investigation on the condensation patterns and Pressure Oscillation characteristics of steam submerged jet through a horizontal pipe at low steam mass flux
International Journal of Heat and Mass Transfer, 2019Co-Authors: Daotong Chong, Quanbin Zhao, Xiaoyu Yue, Lutao Wang, Junjie YanAbstract:Abstract Steam submerged jet condensation is a direct contact condensation widely used in many industries. However, this process may cause damage to related equipment due to Pressure Oscillation, especially at low steam mass flux. This study synchronously investigated the steam–water interface fluctuation of unstable condensation jet and its corresponding Pressure Oscillation through a horizontal pipe at low steam mass flux to research the condensation Oscillation mechanism. Three typical flow patterns, namely, Chugging, hemispherical bubble Oscillation (HBO), and encapsulating bubble Oscillation (EBO), were distinguished based on the dynamic behavior of steam–water interface and Oscillation Pressure characteristics. Only the dynamic Pressure in EBO region was periodic among the three flow patterns. In the EBO region, the Pressure Oscillation frequency increased with the increase of steam mass flux and decreased with the increase of water temperature. A flow pattern regime map for horizontal jet condensation related to steam mass flux and water temperature was presented based on experiments. Moreover, the influence of pipe diameters on low steam mass flux was analyzed. For the flow pattern regime map at low steam mass flux, the critical steam mass fluxes showed an inverse relationship with pipe diameter. An empirical criterion was introduced to determine the flow regime map at low steam mass flux.
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experimental investigation on the mechanism of Pressure Oscillation for steam jet in stable condensation region
Experimental Thermal and Fluid Science, 2017Co-Authors: Binbin Qiu, Daotong Chong, Junjie Yan, Shripad T RevankarAbstract:Abstract The Pressure Oscillations for steam jet in stable condensation region are investigated experimentally. Steam at Pressure 0.2–0.6 MPa is injected into subcooled water at one atmosphere Pressure with steam mass flux ranging from 298 to 865 kg/(m 2 s), with water subcooling from 70 to 40 K. The steam plume shapes have been recorded and are compared with the Pressure Oscillation. The Pressure Oscillation for steam jet in stable condensation region is caused by the Oscillation of steam plume length. When the steam plume length is the longest, the Pressure Oscillation has negative peak value and vice versa. Based on the experimental data and the change of steam plume shapes, a new phenomenological model of Pressure Oscillation is developed. The model also provides a method to obtain the steam plume length using the Pressure Oscillation. The prediction errors of the peak Pressure Oscillation are within ±30% of experimental values.
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effect of non condensation gas on Pressure Oscillation of submerged steam jet condensation
Nuclear Engineering and Design, 2016Co-Authors: Quanbin Zhao, Daotong Chong, Weixiong Chen, Yingchun Wang, Yuelei Cong, Junjie YanAbstract:Abstract The effect of air with low mass fraction on the Oscillation intensity and Oscillation frequency of a submerged steam jet condensation is investigated under stable condensation region. With air mixing in steam, an obvious dynamic Pressure peak appears along the jet direction. The intensity peak increases monotonously with the rise of steam mass flux and water temperature. Peak position moves downstream with the rise of air mass fraction. Moreover, when compared with that of pure steam jet, the Oscillation intensity clearly decreases as air is mixed. However, when water temperature is lower than approximately 45 °C, Oscillation intensity increases slightly with the rise of air mass fraction, and when water temperature is higher than 55 °C, the Oscillation intensity decreases greatly with the rise of air mass fraction. Both the first and second dominant frequencies decrease with rise of air mass fraction. Finally, effect of air mass fractions on the Oscillation power of the first and second dominant frequency bands shows similar trends. Under low water temperature, the mixed air has little effect on the Oscillation power of both first and second frequency bands. However, when water temperature is high, the Oscillation power of both first and second frequency bands appears an obvious peak when air mass fraction is about 1%. With further rise of air mass fraction, the Oscillation power decreases gradually.
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Characteristic of Pressure Oscillation caused by turbulent vortexes and affected region of Pressure Oscillation
Experimental Thermal and Fluid Science, 2016Co-Authors: Weixiong Chen, Daotong Chong, Quanbin Zhao, Yingchun Wang, Palash Kumar Sen, Junjie YanAbstract:Abstract Submerged steam jet condensation is widely applied in various fields because of its high heat transfer efficiency. Condensation Oscillation is a major character of submerged steam turbulent jet, and it significantly affects the design and safe operation of industrial equipment. This study is designed to reveal the mechanism of the low-frequency Pressure Oscillation of steam turbulent jet condensation and determine its affected region. First, Pressure Oscillation signals with low frequency are discovered in the downstream flow field through Oscillation frequency spectrogram and power analysis. The Oscillation frequency is even lower than the first dominant frequency. Moreover, the critical positions, where the low-frequency Pressure Oscillation signals appear, move downstream gradually with radial distance and water temperature. However, these signals are little affected by the steam mass flux. Then, the regions with low-frequency Pressure Oscillation occurring are identified experimentally. The affected width of the low-frequency Pressure Oscillation is similar to the turbulent jet width. Turbulent jet theory and the experiment results collectively indicate that the low-frequency Pressure Oscillation is generated by turbulent jet vortexes in the jet wake region. Finally, the angular coefficients of the low-frequency affected width are obtained under different water temperatures. Angular coefficients, ranging from 0.2268 to 0.2887, decrease with water temperature under test conditions.
Liejin Guo - One of the best experts on this subject based on the ideXlab platform.
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experimental investigation on interfacial Oscillation of direct contact condensation of steam jet in water pipe flow
International Journal of Heat and Mass Transfer, 2019Co-Authors: Xiaona Chu, Weizhi Liu, Tian Yao, Liejin GuoAbstract:Abstract Interfacial Oscillation associated with direct contact condensation of steam jet in water pipe flow is of high significance for industrial processes. In this paper, experimental study is conducted to reveal the mechanisms of the interfacial Oscillation in steam jet condensation in subcooled water flow in a vertical pipe. The interfacial behavior of the jet plume is acquired by high speed camera, and the entire interface in both space and time simultaneously is quantitatively analyzed with digital image processing technology. Bubbling regime occurs at subsonic conditions, where an undulated bubble plume forms with one or more large bubbles falling off intermittently. Jetting regime happens at transonic or supersonic conditions, where a quasi-stable jet plume is observed with numerous uncondensed tiny bubbles continuously shedding off from the end of the jet plume. Distinct waveforms of the radial interface position in both space and time simultaneously are recognized for the two typical condensation regimes. The interfacial unsteadiness reaches a maximum near the sonic point and then drops in the supersonic region, which exhibits similar trend with Pressure Oscillation induced by condensing jet in a qualitative sense. The results confirm that the Pressure Oscillation is highly relevant to the motion of the jet interface and it should be induced by the interfacial Oscillation. The spatial growth rate of the interface unsteadiness along the jet decreases steadily as steam mass flux increases from subsonic to sonic point and it almost does not vary in the supersonic region. The Kelvin-Helmholtz instability mechanism is more important near the nozzle exit, while in other region the Kelvin-Helmholtz instability is of the same importance as the Rayleigh-Taylor instability.
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intelligent identification of steam jet condensation regime in water pipe flow system by wavelet multiresolution analysis of Pressure Oscillation and artificial neural network
Applied Thermal Engineering, 2019Co-Authors: Weizhi Liu, Yanshuang Chen, Qiyu Chen, Liejin GuoAbstract:Abstract On-line recognition of condensation regime of vapor jet in pipe flow systems is a promising approach for flow assurance and intellectualization of industrial processes. However, the selection of distinguishable characteristics from Pressure signals associated strongly with various condensation regimes is essential and challenging for satisfactory recognition purpose. Accordingly, an artificial neural network technique using wavelet multiresolution analysis of Pressure Oscillation signals for objective identification of jet condensation regimes is presented in this paper. The recognition procedure was carried out in two major steps. Statistical features of wavelet multiresolution analysis of Pressure signals, i.e., mean of absolute and percentage of energy of each wavelet scale, were chose first. And then artificial neural network was adopted to construct classifiers for forecasting the condensation regimes automatically. The recognition results illustrated that the proposed method is feasible and effective for identifying vapor jet condensation regime in pipe flow system. Furthermore, it is suggested that statistical features of mean of absolute and percentage of energy at least four or more particular wavelet scales, and also sample length longer than 1.5 s could guarantee a satisfactory recognition rate above 90%.
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recognition of steam jet condensation regime in water pipe flow system by statistical features of Pressure Oscillation
Applied Thermal Engineering, 2017Co-Authors: Liejin GuoAbstract:Abstract Recognition of unstable and harmful condensation regimes in liquid pipe flow system can promote a higher level of flow assurance in liquid propellant rocket engine. However, challenges are encountered in extracting distinguishable characteristics from Pressure Oscillation signals which commonly contains plentiful information strongly associated with various condensation regimes. This article attempts to set up a simple and practical approach of recognizing the steam jet condensation regime in water pipe flow system based on statistical features of Pressure Oscillation. The recognition procedure was performed in three major steps. Initially, twelve statistical features of Pressure Oscillation in time-domain (probability density function) and frequency-domain (power spectrum density) were chose. Subsequently, principal component analysis was implemented to obtain the clear interrelations between condensation regimes and statistical features of Pressure Oscillation signal, and then to extract useful features for establishing condensation regimes clusters for classification in the selected features space. Finally, least squares support vector machine was adopted to the clusters for construction of classifiers to forecast the condensation regimes automatically. The experimental results showed that the proposed approach is feasible and effective for recognizing the steam jet condensation regime in water pipe flow system by statistical features of Pressure Oscillation.
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Mechanisms of Pressure Oscillation in steam jet condensation in water flow in a vertical pipe
International Journal of Heat and Mass Transfer, 2017Co-Authors: Liejin Guo, Liang ChangAbstract:Abstract Pressure Oscillation associated with direct contact condensation of steam jet in water pipe flow is of high significance for industrial processes. In this paper, experimental study is conducted to reveal the mechanisms of the Pressure Oscillation in steam jet condensation in water flow in a vertical pipe. The interfacial characteristics of the jet plume are acquired by high speed camera, and the Pressure Oscillation due to condensing jet are captured by using high frequency Pressure transducers. Four main types, including Chugging, Oscil-I, Oscil-II and Stable condensation regimes, are identified visually based on the interfacial behavior of the jet plume, and their distribution is described in a three-dimensional condensation regime diagram based on steam mass flux, water temperature, and Reynolds number of water flow. In the Chugging regime, the high-amplitude Pressure Oscillation appears at low frequency, and the unimodal PDF demonstrates that the Pressure Oscillation is only dominated by steam mass flux. In the Oscil-I regime, the Pressure Oscillation is approximately sinusoidal and its intensity is the highest among the four condensation regimes, whereas the intensity of the Pressure Oscillation remains at a low level and varies little in the Stable regime. In both the Oscil-I and Stable regimes, with increase of water temperature and Reynolds number of water, the unimodal PDF spreads out over a wider range, and finally the bimodal and symmetrical PDF appears for the Oscil-I regime. The statistical analysis shows that both the deviation and maximum of Pressure signals could identify the four condensation regimes well, while both the skewness and kurtosis of Pressure signals could easily distinguish the Chugging and Oscil-II regimes.
Binbin Qiu - One of the best experts on this subject based on the ideXlab platform.
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experimental investigation on the condensation regime and Pressure Oscillation characteristics of vertical upward steam jet condensation with low mass flux
Experimental Thermal and Fluid Science, 2020Co-Authors: Qingchuan Yang, Daotong Chong, Binbin Qiu, Weixiong Chen, Jiping Liu, Junjie YanAbstract:Abstract An experimental study was conducted to investigate the condensation regime and Pressure Oscillation characteristics of vertical upward steam jet condensation with low mass flux. Steam mass flux and water temperature were 8.34–16.71 kg/(m2·s) and 40–85 °C, respectively. Steam bubble behavior, Pressure Oscillation amplitude and frequency were recorded and analyzed. Four typical regimes were found, namely, chugging, detached oscillatory, detached cracked and secondary bubble impinged regimes. A bubble condensation region map was developed by considering the effects of steam mass flux and water temperature. The average amplitude of Pressure Oscillation initially increased, and then decreased as water temperature increased. It reached its maximum value when water temperature was approximately 60–65 °C, which was the transition temperature range from the chugging regime to the detached oscillatory regime. Meanwhile, the frequency of Pressure Oscillation was within the range of 12–28 Hz. These values were higher than those for a vertical downward steam jet with the same steam mass flux and water temperature. A dimensionless correlation was obtained to predict the Strouhal number of Pressure Oscillation frequency. The predicted values corresponded well with the experimental data. The deviation was within the range of –9.12% to +8.30%.
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experimental investigation on the propagation characteristics of Pressure Oscillation in direct contact condensation with low mass flux steam jet
Experimental Thermal and Fluid Science, 2017Co-Authors: Binbin Qiu, Junjie Yan, Shripad T Revankar, Qingchuan YangAbstract:Abstract The propagation characteristics of Pressure Oscillation in direct contact condensation with low mass flux steam jet have been investigated experimentally. Steam is injected into subcooled water at one atmosphere Pressure with steam mass flux and water temperature range of 186–272 kg/(m 2 s) and 293–343 K. The Pressure Oscillation propagates in the form of wave with stable dominant frequency, however the wave intensity attenuates with the increasing distance from the Oscillation source. The root mean square of Pressure wave p rms attenuates rapidly with the increasing dimensionless radial distance from the nozzle exit. At about dimensionless radial distance R = 100, the p rms is attenuated by about 90%. Although the dominant frequency of the Pressure Oscillation is constant during the propagation, after R = 100, there will be not enough energy for the Pressure Oscillation to resonate with relevant equipment. A correlation equation to calculate the root mean square of Pressure Oscillation along the radial distance is given. The prediction errors are within ±30% compared with the experimental data.
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experimental investigation on the mechanism of Pressure Oscillation for steam jet in stable condensation region
Experimental Thermal and Fluid Science, 2017Co-Authors: Binbin Qiu, Daotong Chong, Junjie Yan, Shripad T RevankarAbstract:Abstract The Pressure Oscillations for steam jet in stable condensation region are investigated experimentally. Steam at Pressure 0.2–0.6 MPa is injected into subcooled water at one atmosphere Pressure with steam mass flux ranging from 298 to 865 kg/(m 2 s), with water subcooling from 70 to 40 K. The steam plume shapes have been recorded and are compared with the Pressure Oscillation. The Pressure Oscillation for steam jet in stable condensation region is caused by the Oscillation of steam plume length. When the steam plume length is the longest, the Pressure Oscillation has negative peak value and vice versa. Based on the experimental data and the change of steam plume shapes, a new phenomenological model of Pressure Oscillation is developed. The model also provides a method to obtain the steam plume length using the Pressure Oscillation. The prediction errors of the peak Pressure Oscillation are within ±30% of experimental values.
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Pressure Oscillation and a new method to calculate the heat transfer coefficient for steam jet condensation
International Journal of Heat and Mass Transfer, 2017Co-Authors: Binbin Qiu, Junjie Yan, Shripad T RevankarAbstract:Abstract The Pressure Oscillation and heat transfer are two important aspects for direct contact condensation. Both of them have been investigated within the steam mass flux 441–865 kg/(m2 s) and water temperature 293–343 K in this paper. The frequency of Pressure Oscillation decreases with the increasing steam mass flux and water temperature. While, the frequency first increases then subsequently decreases with the decreasing Pressure ratio of the nozzle. The heat transfer coefficient has the same variation regularities with the frequency of Pressure Oscillation. Two dimensionless quantity of frequency of Pressure Oscillation and heat transfer coefficient have been obtained, the dimensionless heat transfer coefficient is proportional to the dimensionless frequency of Pressure Oscillation. A new simpler method to calculate the heat transfer coefficient for steam jet condensation has been given. The errors between the predicted values and experimental data are within −30% to 25%.
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experimental investigation on Pressure Oscillation frequency for submerged sonic supersonic steam jet
Annals of Nuclear Energy, 2015Co-Authors: Binbin Qiu, Junjie Yan, Jiping Liu, Daotong ChongAbstract:Abstract Experimental investigations and analysis on the Pressure Oscillation frequency for sonic and supersonic steam injected into subcooled water have been performed. The effects of steam mass flux, water temperature and Pressure ratio on the Oscillation frequency are discussed. The penetration length increases and the frequency decreases with the increasing steam mass flux and water temperature for both sonic and supersonic steam injection. The frequency first increases and then decreases with the decreasing Pressure ratio for supersonic steam injected into subcooled water. When the flow pattern changes from under-expanded jet to over-expanded jet with the decreasing Pressure ratio, the frequency reaches a maximum and will be at the safest value. The safest Pressure ratio is about 0.2 for supersonic steam injection. The correlation reported by previous scholars cannot be directly used to predict the frequency of supersonic steam injected into subcooled water. Based on our experimental data, penetration length and expansion coefficient correlations which are appropriate for the supersonic steam injection have been given. Using the given penetration length and expansion coefficient correlations, the correlation of Hong can be used to predict the Oscillation frequency for supersonic steam injection. The predictions agree well with the present experimental data, the discrepancies are within −20% ∼ 20%.
Quanbin Zhao - One of the best experts on this subject based on the ideXlab platform.
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experimental investigation on the condensation patterns and Pressure Oscillation characteristics of steam submerged jet through a horizontal pipe at low steam mass flux
International Journal of Heat and Mass Transfer, 2019Co-Authors: Daotong Chong, Quanbin Zhao, Xiaoyu Yue, Lutao Wang, Junjie YanAbstract:Abstract Steam submerged jet condensation is a direct contact condensation widely used in many industries. However, this process may cause damage to related equipment due to Pressure Oscillation, especially at low steam mass flux. This study synchronously investigated the steam–water interface fluctuation of unstable condensation jet and its corresponding Pressure Oscillation through a horizontal pipe at low steam mass flux to research the condensation Oscillation mechanism. Three typical flow patterns, namely, Chugging, hemispherical bubble Oscillation (HBO), and encapsulating bubble Oscillation (EBO), were distinguished based on the dynamic behavior of steam–water interface and Oscillation Pressure characteristics. Only the dynamic Pressure in EBO region was periodic among the three flow patterns. In the EBO region, the Pressure Oscillation frequency increased with the increase of steam mass flux and decreased with the increase of water temperature. A flow pattern regime map for horizontal jet condensation related to steam mass flux and water temperature was presented based on experiments. Moreover, the influence of pipe diameters on low steam mass flux was analyzed. For the flow pattern regime map at low steam mass flux, the critical steam mass fluxes showed an inverse relationship with pipe diameter. An empirical criterion was introduced to determine the flow regime map at low steam mass flux.
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effect of non condensation gas on Pressure Oscillation of submerged steam jet condensation
Nuclear Engineering and Design, 2016Co-Authors: Quanbin Zhao, Daotong Chong, Weixiong Chen, Yingchun Wang, Yuelei Cong, Junjie YanAbstract:Abstract The effect of air with low mass fraction on the Oscillation intensity and Oscillation frequency of a submerged steam jet condensation is investigated under stable condensation region. With air mixing in steam, an obvious dynamic Pressure peak appears along the jet direction. The intensity peak increases monotonously with the rise of steam mass flux and water temperature. Peak position moves downstream with the rise of air mass fraction. Moreover, when compared with that of pure steam jet, the Oscillation intensity clearly decreases as air is mixed. However, when water temperature is lower than approximately 45 °C, Oscillation intensity increases slightly with the rise of air mass fraction, and when water temperature is higher than 55 °C, the Oscillation intensity decreases greatly with the rise of air mass fraction. Both the first and second dominant frequencies decrease with rise of air mass fraction. Finally, effect of air mass fractions on the Oscillation power of the first and second dominant frequency bands shows similar trends. Under low water temperature, the mixed air has little effect on the Oscillation power of both first and second frequency bands. However, when water temperature is high, the Oscillation power of both first and second frequency bands appears an obvious peak when air mass fraction is about 1%. With further rise of air mass fraction, the Oscillation power decreases gradually.
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Characteristic of Pressure Oscillation caused by turbulent vortexes and affected region of Pressure Oscillation
Experimental Thermal and Fluid Science, 2016Co-Authors: Weixiong Chen, Daotong Chong, Quanbin Zhao, Yingchun Wang, Palash Kumar Sen, Junjie YanAbstract:Abstract Submerged steam jet condensation is widely applied in various fields because of its high heat transfer efficiency. Condensation Oscillation is a major character of submerged steam turbulent jet, and it significantly affects the design and safe operation of industrial equipment. This study is designed to reveal the mechanism of the low-frequency Pressure Oscillation of steam turbulent jet condensation and determine its affected region. First, Pressure Oscillation signals with low frequency are discovered in the downstream flow field through Oscillation frequency spectrogram and power analysis. The Oscillation frequency is even lower than the first dominant frequency. Moreover, the critical positions, where the low-frequency Pressure Oscillation signals appear, move downstream gradually with radial distance and water temperature. However, these signals are little affected by the steam mass flux. Then, the regions with low-frequency Pressure Oscillation occurring are identified experimentally. The affected width of the low-frequency Pressure Oscillation is similar to the turbulent jet width. Turbulent jet theory and the experiment results collectively indicate that the low-frequency Pressure Oscillation is generated by turbulent jet vortexes in the jet wake region. Finally, the angular coefficients of the low-frequency affected width are obtained under different water temperatures. Angular coefficients, ranging from 0.2268 to 0.2887, decrease with water temperature under test conditions.
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Pressure Oscillation of submerged steam condensation in condensation Oscillation regime
International Journal of Heat and Mass Transfer, 2016Co-Authors: Fang Yuan, Daotong Chong, Quanbin Zhao, Weixiong Chen, Junjie YanAbstract:Abstract The condensation Oscillation of submerged steam was investigated theoretically and experimentally at the condensation Oscillation regime. It was found that Pressure Oscillation frequency was consistent with the bubble oscillating frequency and there was a quasi-steady stage when bubble diameters remained constant. A thermal-hydraulic model for the condensation Oscillation regime was proposed based on potential flow theory, taking into account the effects of interface condensation and translatory flow. Theoretical derivations indicated that Oscillation frequencies were mainly determined by bubble diameters and translatory velocity. A force balance model was applied to the calculation of bubble diameters at quasi-steady stage, and the Oscillation frequencies were predicted with the calculated diameters. Theoretical analysis and experimental results turned out that Oscillation frequencies at the condensation Oscillation regime decreased with the increasing steam mass flux and pool temperature. The predicted frequencies corresponded to the experimental data well with the discrepancies of ±21.7%.
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Pressure Oscillation and steam cavity during the condensation of a submerged steam jet
Annals of Nuclear Energy, 2015Co-Authors: Quanbin Zhao, Wei Wang, Daotong Chong, Weixiong Chen, Fang Yuan, Junjie YanAbstract:Abstract Steam jet condensation is important in many industrial applications. In this work, the Pressure Oscillation and steam jet patterns during submerged jet condensation in quiescent water is investigated experimentally. Firstly, it is found that even at stable condensation region, the steam cavity length varies all the time and steam bubbles separate from the steam cavity periodically. With the variation of steam cavity length and separated bubble Oscillation, condensation also undergoes Oscillation. Along the axial direction, the Pressure Oscillation intensity increases first and then decreases gradually. There is an distinct Pressure Oscillation peak, and the peak position varies over a length-to-diameter ratio range of X / D = 2 to X / D = 7. The axial position of Pressure Oscillation peak corresponds to the end of steam cavity. Moreover, Oscillation energy analysis shows that the Oscillation energy generated by separated steam bubble is much higher than that generated by the steam cavity length variation. Finally, based on the relationship between the axial distribution of Pressure Oscillation and the steam cavity, a method is proposed to determine the maximum steam cavity length by measuring the Pressure Oscillation distributions. The predicted deviation is only in range of ±16% for the test conditions.
