As a critical facility,spiral-wound heat exchanger was(SWHE)has the been widely used in many industrial applications.boundary A computational fluid dynamics(CFD)model employed with smallest periodic element results an...As a critical facility,spiral-wound heat exchanger was(SWHE)has the been widely used in many industrial applications.boundary A computational fluid dynamics(CFD)model employed with smallest periodic element results and periodic conditions to examine around the the characteristics tube of the shell side of SWHE.Numerical simulation show that the heat transfer coefficients and initially mean increase absolute and subsequently decrease simulated 5%with heat radial angle because of the influence measured of backflow turbulent separation.nitrogen The deviation between is transfer coefficients and values for methane,drop,ethane,and are a mixture(methane/ethane)within when mean Reynolds number is over is 30000.For the pressure the simulated results values smaller than the measured values,and the absolute on deviation within 9%.Numerical simulation also tubes indicate that the pressure drop the and heat of transfer coefficients angle the shell side and of SWHE heat decrease as the winding the angle of the increases.Nusselt Considering effect winding on pressure drops transfer coefficients,modified correlations of_=0.308Re^(0.64)Pr^(0.36)(1+sin)^(1.38 )and friction factor f_=0.435Re^(-0.133)(sin)^(-0.36),are proposed.Comparing Nu number with the experimental data,the maximum deviations for heat transfer coefficients and pressure drops are less than 5%and11%respectively.展开更多
Purpose： To explore the impact of subtropical maritime monsoon climate on the frequency of ambulance use for trauma patients in a coastal region in China. Method： Statistical analysis of data on ambulance use from t...Purpose： To explore the impact of subtropical maritime monsoon climate on the frequency of ambulance use for trauma patients in a coastal region in China. Method： Statistical analysis of data on ambulance use from the 120 Emergency Command Center in Shantou City, Guangdong Province, from January to December 2012 as well as daily meteorological data from a Shantou observatory was performed to determine how climatic factors （seasons, time, and weather） affect the frequency of ambulance use for trauma patients. Results： The daily ambulance use for trauma patients differed between spring and summer or autumn （p 〈 0.05）, between sunny and rainy days （p 〈 0.05）, and between cloudy and lightly or moderately rainy days （p 〈 0.05）. We found a linear correlation between daily maximum temperature and daily ambulance use for trauma patients （R^2 0.103, p 〈 0.05）. In addition, there was significant difference in ambulance use between good and bad weather （p 〈 0.05）. Conclusion： Frequency of ambulance use for trauma patients is affected by the subtropical maritime monsoon climate in the coastal region. Better weather contributes to increased daily frequency of ambulance use, which is the highest in autumn and lowest in spring.展开更多
基金supported by Beijing Natural Science Foundation(Grant No.3171002)
文摘As a critical facility,spiral-wound heat exchanger was(SWHE)has the been widely used in many industrial applications.boundary A computational fluid dynamics(CFD)model employed with smallest periodic element results and periodic conditions to examine around the the characteristics tube of the shell side of SWHE.Numerical simulation show that the heat transfer coefficients and initially mean increase absolute and subsequently decrease simulated 5%with heat radial angle because of the influence measured of backflow turbulent separation.nitrogen The deviation between is transfer coefficients and values for methane,drop,ethane,and are a mixture(methane/ethane)within when mean Reynolds number is over is 30000.For the pressure the simulated results values smaller than the measured values,and the absolute on deviation within 9%.Numerical simulation also tubes indicate that the pressure drop the and heat of transfer coefficients angle the shell side and of SWHE heat decrease as the winding the angle of the increases.Nusselt Considering effect winding on pressure drops transfer coefficients,modified correlations of_=0.308Re^(0.64)Pr^(0.36)(1+sin)^(1.38 )and friction factor f_=0.435Re^(-0.133)(sin)^(-0.36),are proposed.Comparing Nu number with the experimental data,the maximum deviations for heat transfer coefficients and pressure drops are less than 5%and11%respectively.
基金This study was supported by a grant from National Natural Science Foundation of China （NO. 81372084）.Acknowledgments The authors are grateful to the Shantou Observatory and the 120 Emergency Command Center of Shantou City for providing related data.
文摘Purpose： To explore the impact of subtropical maritime monsoon climate on the frequency of ambulance use for trauma patients in a coastal region in China. Method： Statistical analysis of data on ambulance use from the 120 Emergency Command Center in Shantou City, Guangdong Province, from January to December 2012 as well as daily meteorological data from a Shantou observatory was performed to determine how climatic factors （seasons, time, and weather） affect the frequency of ambulance use for trauma patients. Results： The daily ambulance use for trauma patients differed between spring and summer or autumn （p 〈 0.05）, between sunny and rainy days （p 〈 0.05）, and between cloudy and lightly or moderately rainy days （p 〈 0.05）. We found a linear correlation between daily maximum temperature and daily ambulance use for trauma patients （R^2 0.103, p 〈 0.05）. In addition, there was significant difference in ambulance use between good and bad weather （p 〈 0.05）. Conclusion： Frequency of ambulance use for trauma patients is affected by the subtropical maritime monsoon climate in the coastal region. Better weather contributes to increased daily frequency of ambulance use, which is the highest in autumn and lowest in spring.
