Research on shell-side heat and mass transfer with multi-component in LNG spiral-wound heat exchanger under sloshing conditions

The spiral-wound heat exchanger(SWHE) is the primary low-temperature heat exchanger for large-scale LNG plants due to its high-pressure resistance, compact structure, and high heat exchange efficiency. This paper studied the shell-side heat and mass transfer characteristics of vapor-liquid two-phase mixed refrigerants in an SWHE by combining a multi-component model in FLUENT software with a customized multicomponent mass transfer model. Besides, the mathematical model under the sloshing condition was obtained through mathematical derivation, and the corresponding UDF code was loaded into FLUENT as the momentum source term. The results under the sloshing conditions were compared with the relevant parameters under the steady-state condition. The shell-side heat and mass transfer characteristics of the SWHE were investigated by adjusting the component ratio and other working conditions. It was found that the sloshing conditions enhance the heat transfer performance and sometimes have insignificant effects. The sloshing condition is beneficial to reduce the flow resistance. The comprehensive performance of multi-component refrigerants has been improved and the improvement is more significant under sloshing conditions, considering both the heat transfer and pressure drop.These results will provide theoretical support for the research and design of multi-component heat and mass transfer enhancement of LNG SWHE under ocean sloshing conditions.

Living experience and care needs of Chinese empty-nest elderly people in urban communities in Beijing,China:A qualitative study

Background:Empty-nest elders have considerable needs for daily living,health care,and social support in China.The growing need for care of an aging population requires to be met through adequate policy decision making by government.Aim:To explore care needs of Chinese empty-nest elderly people and to provide reference information for relevant authorities in making care-supporting policies.Method:A descriptive qualitative study design was adopted.Twenty-five senior citizens in urban communities who were not living with their children were recruited from three communities in different districts of Beijing.In-depth interviews with a semi-structured questionnaire were used to collect data.A qualitative content analysis method was used to analyze data.Results:A major care need by the empty-nest elderly was home-based care.In view of their physical condition,need of support and their own security problems,they would like to have aging-in-place,home-based care by housemaid employment,or have institutionalized care in the future.However,they had some concerns about institutionalized care.Conclusions:A combination of home-based and community-based care is a suitable mode of care for the empty-nest elderly,and institutionalized care is an expected supplementary form of care.

Epidemiology of Sepsis-3 in a sub-district of Beijing: secondary analysis of a population-based database

Background: With the publication of Sepsis-3 definition, epidemiological data based on Sepsis-3 definition from middle-income countries including China are scarce, which prohibits understanding of the disease burden of this newly defined syndrome in these settings. The purpose of this study was to describe incidence and outcome of Sepsis-3 in Yuetan sub-district of Beijing and to estimate the incidence rate of Sepsis-3 in China. Methods: The medical records of all adult residents hospitalized from July 1, 2012 to June 30, 2014 in Yuetan sub-district of Beijing were reviewed. Patients with sepsis-3 and severe sepsis/septic shock were identified. The incidence rates and mortality rate of sepsis-3 and sepsis/septic shock were calculated, incidence rates and in-hospital mortality rates were normalized to the population distribution in the 2010 National Census. Population incidence rate and case fatality rate between sexes were compared with the Z test, as the data conformed to Poisson distribution. Results: Of the 21,191 hospitalized patients, 935 patients were diagnosed with Sepsis-3, and 498 cases met severe sepsis/septic shock criteria. The crude annual incidence rate of Sepsis-3 in Yuetan sub-district was 363 cases per 100,000 population, corresponding to standardized incidence rates of 236 cases per 100,000 population per year, respectively. The overall case fatality rate of Sepsis-3 was 32.0%, the crude population mortality rates of Sepsis-3 was 116 cases per 100,000 population per year, the standardized mortality rate was 67 cases per 100,000 population per year, corresponding to a speculative extrapolation of 700,437 deaths in China. The incidence rate and mortality rate of Sepsis-3 were significantly higher in males, elderly people, and patients with more comorbidities. The 62.1% of patients with Sepsis-3 had community-acquired infections, compared with 75.3% of infected patients without Sepsis-3 (P < 0.001). The most common infection in patients with Sepsis-3 was lower respiratory tract infection. When compared with patients with Sepsis-3, patients diagnosed as severe sepsis/septic shock were more likely to have higher case fatality rate (53.4% vs. 32.0%, P < 0.001) Conclusions: This study found the standardized incidence rate of 236 cases per 100,000 person-year for Sepsis-3, which was more common in males and elderly population. This corresponded to about 2.5 million new cases of Sepsis-3 per year, resulting in more than 700,000 deaths in China.