Recently,our research group proposed the phase separation condenser tube,in which a mesh cylinder was inserted to form the flow structure of‘‘gas near the tube wall and liquid in the tube core’’,significantly enha...Recently,our research group proposed the phase separation condenser tube,in which a mesh cylinder was inserted to form the flow structure of‘‘gas near the tube wall and liquid in the tube core’’,significantly enhance the condensation heat transfer.But the bubble leakage towards the core region may worsen the heat transfer enhancement.In order to prevent the bubble leakage,the critical criterion was proposed based on the Young–Laplace equation,considering the inertia force,viscous force and pulsating flow.It was found that the critical criterion depends on the dimensionless parameter G*,the We number and a coefficient C.The numerical model was developed in terms of the volume of fluid method to predict the two-phase laminar flow in the phase separation condenser tube.The results show that the bubble leakage takes place at the bubble tip,which is agreed with the experimental observations.The critical curve distinguishing the non-bubble-breaking and bubble-breaking was obtained by comparing the bubble dynamics at different G*and We.The coefficient C was determined.The critical criterion for the bubble leakage is given as G We0:22We0:99349 G4:7 103 We0:00651t196:39We0:006514cosa DHW,providing the design and operation guidance for the phase separation condenser tube.展开更多
In order to overcome the inconvenience of manual bubble counting, a bubble counter based on photoelectric technique aiming for automatically detecting and measuring minute gas leakage of cryogenic valves is proposed. ...In order to overcome the inconvenience of manual bubble counting, a bubble counter based on photoelectric technique aiming for automatically detecting and measuring minute gas leakage of cryogenic valves is proposed. Experiments have been conducted on a self-built apparatus, testing the performance with different gas inlet strategies (bottom gas-inlet strategy and side gas-inlet strategy) and the influence of gas pipe length (0, 1, 2, 4, 6, 8, 10 m) and leakage rate (around 10, 20, 30, 40 bubbles/min) on first bubble time and bubble rate. A buffer of 110 cm3 is inserted between leakage source and gas pipe to simulate the down- stream cavum adjacent to the valve clack. Based on analyzing the experimental data, experiential parameters have also been summarized to guide leakage detection and measurement for engineering applications. A practical system has already been suc- cessfully applied in a cryogenic testing apparatus for cryogenic valves.展开更多
Exploring a rapid, reliable, and practical means to detect blockages and leakages in liquid pipelines and accurately locate their positions is of great importance in practical engineering applications. Here, we report...Exploring a rapid, reliable, and practical means to detect blockages and leakages in liquid pipelines and accurately locate their positions is of great importance in practical engineering applications. Here, we report a bubble motion-based triboelectric sensor(BM-TES) for detecting and locating the blockages and leaks inside a plastic tube. This simple-designed, environment-friendly,non-damaging sensor is composed of several ring-shaped Cu electrodes distributed on a polytetrafluoroethylene tube. The selfpowered movement of the bubble under the action of buoyancy makes the inner wall of the tube change from the original solidliquid phase to the gas-solid-liquid phase, which results in a short-term contact and separation between the liquid and the wall.Based on the fractional triboelectric effect of the liquid-solid contact, an obvious real-time stable voltage peak will be generated where the detection bubble passes. The obvious peaks of the open-circuit voltage with respect to time correspond with the electrode distribution. Then, the peaks can be utilized as a robust and sensitive indicator for detecting blockage and leakage, as the number of obvious peaks of the open-circuit voltage is directly related to the blockage and leakage location. The blockage and leakage in a fluid tube were successfully detected using the BM-TES with an accuracy of 10 cm. In addition, the BE-TES was able to detect the water flow velocity in the pipe. The experimental results showed that BM-TES can provide a new strategy and method for liquid tube monitoring and has great potential application value in related fields.展开更多
目的:应用前房注入无菌空气治疗白内障手术结束时出现前房不稳定的情况,观察手术效果、并发症,评估安全性。方法:回顾性分析白内障手术结束时前房不稳定的病例,将其分成两组,注气组31眼为前房注气组,注液组27眼为注液(平衡盐溶液,BSS)组...目的:应用前房注入无菌空气治疗白内障手术结束时出现前房不稳定的情况,观察手术效果、并发症,评估安全性。方法:回顾性分析白内障手术结束时前房不稳定的病例,将其分成两组,注气组31眼为前房注气组,注液组27眼为注液(平衡盐溶液,BSS)组,观察前房气泡吸收情况及前房稳定性,对角膜内皮细胞、视力、眼压的影响,有无其它并发症如眼内炎症、黄斑囊样水肿。结果:两组术前眼压对比、术后眼压对比差异均无统计学意义(P>0.05),注气组术前眼压(15.29±0.53)mm Hg与术后1d眼压(14.58±0.63)mm Hg对比差异无统计学意义(P>0.05)。两组术前角膜内皮细胞密度对比(2435.71±194.80 vs 2 430.74±191.95个/mm2),术后角膜内皮细胞密度对比(2400.74±194.00 vs 2398.22±193.36个/mm2)差异均无统计学意义(P>0.05)。两组术后均未出现浅前房、眼内炎症。术中单次操作前房恢复稳定率注气组94%,注液组33%,两组对比差异具有统计学意义(P<0.05)。结论:应用前房注气治疗白内障术毕出现前房恢复不稳定情况,安全有效,简单快速。展开更多
基金supported by the National Natural Science Foundation of China of International Cooperation Project (51210011)the National Basic Research Program of China (2011CB710703)+1 种基金the Young Scientists Fund of the National Natural Science Foundation of China (51106049)the Fundamental Research Funds for the Central Universities (JB2013144)
文摘Recently,our research group proposed the phase separation condenser tube,in which a mesh cylinder was inserted to form the flow structure of‘‘gas near the tube wall and liquid in the tube core’’,significantly enhance the condensation heat transfer.But the bubble leakage towards the core region may worsen the heat transfer enhancement.In order to prevent the bubble leakage,the critical criterion was proposed based on the Young–Laplace equation,considering the inertia force,viscous force and pulsating flow.It was found that the critical criterion depends on the dimensionless parameter G*,the We number and a coefficient C.The numerical model was developed in terms of the volume of fluid method to predict the two-phase laminar flow in the phase separation condenser tube.The results show that the bubble leakage takes place at the bubble tip,which is agreed with the experimental observations.The critical curve distinguishing the non-bubble-breaking and bubble-breaking was obtained by comparing the bubble dynamics at different G*and We.The coefficient C was determined.The critical criterion for the bubble leakage is given as G We0:22We0:99349 G4:7 103 We0:00651t196:39We0:006514cosa DHW,providing the design and operation guidance for the phase separation condenser tube.
基金Project (Nos. 50776075 and 50536040) supported by the National Natural Science Foundation of China
文摘In order to overcome the inconvenience of manual bubble counting, a bubble counter based on photoelectric technique aiming for automatically detecting and measuring minute gas leakage of cryogenic valves is proposed. Experiments have been conducted on a self-built apparatus, testing the performance with different gas inlet strategies (bottom gas-inlet strategy and side gas-inlet strategy) and the influence of gas pipe length (0, 1, 2, 4, 6, 8, 10 m) and leakage rate (around 10, 20, 30, 40 bubbles/min) on first bubble time and bubble rate. A buffer of 110 cm3 is inserted between leakage source and gas pipe to simulate the down- stream cavum adjacent to the valve clack. Based on analyzing the experimental data, experiential parameters have also been summarized to guide leakage detection and measurement for engineering applications. A practical system has already been suc- cessfully applied in a cryogenic testing apparatus for cryogenic valves.
基金supported by the Program for Taishan Scholars of Shandong Province(Grant No.ts20190965)the National Key Research and Development Program of China(Grant No.2020YFF0304600)+4 种基金the National Natural Science Foundation of China(Grant No.51905518)the Innovation Leading Talents Program of Qingdao(Grant No.19-3-2-23-zhc)the Tribology Science Fund of State Key Laboratory of Solid Lubrication(Grant Nos.LSL-1903,and LSL-1909)the Open Research Fund of Hubei Key Laboratory of Hydroelectric Machinery Design&Maintenance(Grant Nos.2019KJX09,and 2019KJX07)the Research Fund for Excellent Dissertation of China Three Gorges University(Grant No.2021SSPY038)。
文摘Exploring a rapid, reliable, and practical means to detect blockages and leakages in liquid pipelines and accurately locate their positions is of great importance in practical engineering applications. Here, we report a bubble motion-based triboelectric sensor(BM-TES) for detecting and locating the blockages and leaks inside a plastic tube. This simple-designed, environment-friendly,non-damaging sensor is composed of several ring-shaped Cu electrodes distributed on a polytetrafluoroethylene tube. The selfpowered movement of the bubble under the action of buoyancy makes the inner wall of the tube change from the original solidliquid phase to the gas-solid-liquid phase, which results in a short-term contact and separation between the liquid and the wall.Based on the fractional triboelectric effect of the liquid-solid contact, an obvious real-time stable voltage peak will be generated where the detection bubble passes. The obvious peaks of the open-circuit voltage with respect to time correspond with the electrode distribution. Then, the peaks can be utilized as a robust and sensitive indicator for detecting blockage and leakage, as the number of obvious peaks of the open-circuit voltage is directly related to the blockage and leakage location. The blockage and leakage in a fluid tube were successfully detected using the BM-TES with an accuracy of 10 cm. In addition, the BE-TES was able to detect the water flow velocity in the pipe. The experimental results showed that BM-TES can provide a new strategy and method for liquid tube monitoring and has great potential application value in related fields.
文摘目的:应用前房注入无菌空气治疗白内障手术结束时出现前房不稳定的情况,观察手术效果、并发症,评估安全性。方法:回顾性分析白内障手术结束时前房不稳定的病例,将其分成两组,注气组31眼为前房注气组,注液组27眼为注液(平衡盐溶液,BSS)组,观察前房气泡吸收情况及前房稳定性,对角膜内皮细胞、视力、眼压的影响,有无其它并发症如眼内炎症、黄斑囊样水肿。结果:两组术前眼压对比、术后眼压对比差异均无统计学意义(P>0.05),注气组术前眼压(15.29±0.53)mm Hg与术后1d眼压(14.58±0.63)mm Hg对比差异无统计学意义(P>0.05)。两组术前角膜内皮细胞密度对比(2435.71±194.80 vs 2 430.74±191.95个/mm2),术后角膜内皮细胞密度对比(2400.74±194.00 vs 2398.22±193.36个/mm2)差异均无统计学意义(P>0.05)。两组术后均未出现浅前房、眼内炎症。术中单次操作前房恢复稳定率注气组94%,注液组33%,两组对比差异具有统计学意义(P<0.05)。结论:应用前房注气治疗白内障术毕出现前房恢复不稳定情况,安全有效,简单快速。
