Spiral-wound heat exchanger (SWHE) is important equipment for industry, and it is suitable for floating production storage off-loading (FPSO). However, two-phase mixture maldistribution always ...restricts the heat transfer capacity of SWHE in FPSO. Few studies have focused on the maldistribution of SWHE. According to this, an experimental device was fabricated to evaluate the maldistribution of a novel distributor on the sloshing platform. The effects of vapor qualities and mass flow rates were analyzed at the range of 0.106–0.702 and 608.5–1491.6 kg h
−1
, respectively. The following conclusions are drawn: With the augmentation of vapor quality, the gas–liquid uniformity deteriorates after optimizing under steady and sloshing conditions. Heave condition improves gas and liquid flow uniformity by 2.9–11.0% and 1.7–3.7% separately, and pitch condition improves the gas flow uniformity by 0.5–3.7%, and roll condition lowers the liquid flow uniformity by 2.0–7.2% in the variation of vapor quality. It is also proved that the flow uniformity achieves better performance with the increasing mass flow rate under steady, heave and pitch conditions. Heave condition improves the distribution characteristic by 4.4–8.7% for the gas phase and 2.0–9.5% for the liquid phase, and pitch condition elevates the gas flow uniformity by 3.1–7.7%. Under the roll condition, the distribution performance of the experimental model changes worse after better and obtains the best performance at the mass flow rate of 1183.8 kg/h. At large mass flow rates, gas entering into liquid space under roll condition can bring the structural problem. Increasing the tube diameter and making the upper baffle tilt from shell to center barrel are beneficial to keep the distributor structure safe.
Spiral wound tube heat exchanger (SWHE) was confirmed as the core equipment of natural gas liquefaction (LNG). However, there was rare experimental research on large-scale SWHE for LNG, and the ...theory of heat transfer is not perfect. To investigate the tube-side flow and heat transfer characteristics in spiral tubes, an experimental system was proposed. To ensure the accuracy of the experimental data, the heat transfer coefficients of liquid propane under different conditions were measured, and the data acquired through the experiment were compared with two classical heat transfer correlation (Dittus–Boelter and Geielinski) under the identical working conditions. The applicability of the existing correlation was analyzed using the experimental data, and a novel heat transfer correlation was developed. As indicated by the results, the deviation between the experimental system and the classical correlation under the identical working condition was lower than ±10%. Furthermore, the error comparison between the novel correlation prediction value and the experimental data was less than ±15%.
This study aims to investigate the safety of Shu-Xue-Ning injection (SXNI) in real-world clinical applications.
A prospective, multi-center, large-sample intensive monitoring method was used to ...monitor the use of SXNI in several medical institutions across China while collecting patients' dosing and adverse event information. Patients who suspected as adverse reactions made comparisons with patients who did not report adverse reactions to calculate the correlation between relevant risk factors and suspected adverse reactions. Statistical analysis software SAS 9.1 was used for data analysis.
A total of 48 hospitals participated in this intensive monitoring study of SXNI, and 30,122 patients were monitored from July 2015 to December 2018. A total of 1,908 adverse events were reported during the use of SXNI, with an adverse event rate of 6.33% and a 95% confidence interval (CI) of 6.06%-6.61%. Association assessment showed that 54 cases presented with SXNI-related adverse reactions with an incidence of 0.18% and a 95% CI of 0.13%-0.23%, thereby indicating that the incidence of SXNI-related adverse reactions was occasional. SXNI-related adverse reactions involved 9 systems-organs with 20 clinical manifestations, and the most common adverse reactions were rash, pruritus, and other damages of skin and its appendages. No serious adverse reactions were observed; 27.78% of the adverse reactions occurred within 30 min of drug administration and more than half of them occurred within 2 h of drug administration; 96.3% of the adverse reactions were cured or improved. Causal analysis showed that women, long dispensing time, and slow dripping speed rate were considered as risk factors.
The incidence of SXNI-related adverse reactions in real-world clinical applications is occasional and in a reasonable range with a good prognosis.
The maldistribution of working medium restricts the heat transfer performance of the spiral-wound heat exchangers (SWHEs), especially when the heat exchangers are applied in floating production ...storage and offloading platform. Therefore, the maldistribution in the SWHEs needs to be studied under sloshing conditions. In the investigation, a novel distributor named “disc distributor” is designed and its distribution characteristic is analysed under sloshing conditions experimentally. The impacts of sloshing amplitude, sloshing periods, mass flow rate and structural parameters on flow uniformity are discussed. The results show that based on steady condition the augmentation of the sloshing amplitude makes the liquid uniformity deteriorate by 14.2–56.0%, and the enlargement of the sloshing period improves the liquid flow uniformity by 12.8–28.3%. The elevation of the mass flow rate promotes the flow uniformity by 23.8–27.0% and 13.9–32.4% under steady and sloshing conditions, respectively. The variation of hole diameter exacerbates distribution performance of the distributor by 5.3–18.4% and 2.5–22.3% under steady and sloshing conditions separately. Heave condition always has less influence on the flow uniformity of the distributor than other sloshing conditions.
The utilization of the spiral tube heat exchanger (SHE) has become increasingly prevalent in large-scale liquefaction processes. However, the flow pattern and frictional pressure drop of two-phase ...flow in the spiral tube have been scarcely studied, particularly under offshore sloshing conditions. An experimental system had been developed to explore the flow pattern and frictional pressure drop characteristics of mixed hydrocarbon fluid in a spiral tube. Moreover, these have been developed in order to examine the effects of sloshing style (roll, pitch, heave), sloshing period (5–15 s), sloshing amplitude (5–15° or 50–150 mm), mass flux (200–800 kg/(m2·s)), vapor quality (0–1), and saturation pressure (2–4 MPa) on the frictional pressure drop of methane/ethane mixture in the spiral tube. The results indicated that sloshing conditions reduce the frictional pressure drop, thereby enhancing fluid flow. A correlation was established to predict the sloshing factor of frictional pressure drop, and the MARD under verification conditions was 6.04%. Furthermore, three flow pattern boundaries were proposed based on We* as an indicator.
The non-uniformity of gas–liquid mixture is a critical issue which leads to the heat transfer deterioration of spiral-wound heat exchangers (SWHEs). Two-phase mass flow rate and the content of gas ...are important parameters as well as structural parameters which have prominent influences on flow distribution uniformity of SWHE shell side. In order to investigate the influences of these parameters, an experimental test system was built using water and air as mediums and a novel distributor named “tubes distributor” was designed. The effects of mass flow rate and the content of gas on two-phase distribution performance were analyzed, where the mass flow rate ranged from 28.4 to 171.9 kg·h−1 and the content of gas changed from 0.2 to 0.8, respectively. The results showed that the mixture mass flow rate considerably influenced the liquid distribution than that of gas phase and the larger mass flow rate exhibited the better distribution uniformity of two-phase flow. It was also found that the tubes distributor had the better two-phase uniformity when the content of gas was around 0.4. Tube diameter played an important role in the distribution of gas phase and slit width was more significant for the uniformity of liquid phase.
Since its outbreak in December 2019, a series of clinical trials on coronavirus disease 2019 (COVID-19) have been registered or carried out. However, the significant heterogeneity and less critical ...outcomes of such trials may be leading to a waste of research resources. This study aimed to develop a core outcome set (COS) for clinical trials on COVID-19 in order to tackle the outcome issues. The study was conducted according to the Core Outcome Measures in Effectiveness Trials (COMET) Handbook: Version 1.0, a guideline for COS development. A research group was set up that included experts in respiratory and critical medicine, traditional Chinese medicine (TCM), evidence-based medicine, clinical pharmacology, and statistics, in addition to medical journal editors. Clinical trial registry websites (www.chictr.org.cn and clinicaltrials.gov) were searched to retrieve clinical trial protocols and outcomes in order to form an outcome pool. A total of 78 clinical trial protocols on COVID-19 were included and 259 outcomes were collected. After standardization, 132 outcomes were identified within seven different categories, of which 58 were selected to develop a preliminary outcome list for further consensus. After two rounds of Delphi survey and one consensus meeting, the most important outcomes for the different clinical classifications of COVID-19 were identified and determined to constitute the COS for clinical trials on COVID-19 (COS-COVID). The COS-COVID includes one outcome for the mild type (time to 2019 novel coronavirus (2019-nCoV) reverse transcription-polymerase chain reaction (RT-PCR) negativity), four outcomes for the ordinary type (length of hospital stay, composite events, score of clinical symptoms, and time to 2019-nCoV RT-PCR negativity), five outcomes for the severe type (composite events, length of hospital stay, arterial oxygen partial pressure (PaO2)/fraction of inspired oxygen (FiO2), duration of mechanical ventilation, and time to 2019-nCoV RT-PCR negativity), one outcome for critical type (all-cause mortality), and one outcome for rehabilitation period (pulmonary function). The COS-COVID is currently the most valuable and practical clinical outcome set for the evaluation of intervention effect, and is useful for evidence assessment and decision-making. With a deepening understanding of COVID-19 and application feedback, the COS-COVID should be continuously updated.
IntroductionChronic heart failure (CHF) is a serious and advanced stage of various cardiovascular diseases and portends poor prognosis. An increase in clinical studies has reported the effectiveness ...of traditional Chinese medicine (TCM). For example, intravenous Chinese medicine can significantly improve cardiac function and biomarkers in patients with CHF. However, there exists inconsistency, lack of practicality and unclear reporting of outcomes in these clinical trials causing difficulty in the comparison of results across similar studies during data synthesis. A core outcome set (COS) can help in the standardisation of outcomes reported across studies from the same healthcare area. The aim of this study is to develop a COS on TCM for CHF (COS-TCM-CHF) to reduce heterogeneity in reporting and improve quality assessment in clinical trials to support data synthesis in addressing the effectiveness of TCM treatment.Methods and analysisThis study will include constructing an outcome pool which will identify potential outcomes through systematic reviews of TCM randomised clinical trials, two clinical registry databases, semi-structured interviews of patients and the clinicians’ questionnaire. According to the characteristics of TCM and a taxonomy recommended by the Core Outcome Measures in Effectiveness Trials (COMET) initiative, all outcomes in the outcome pool will be classified into different domains. A preliminary list of outcomes which will then be used in the Delphi survey is generated using a certain criteria based on the length of the pool. The Delphi survey will include two rounds with seven key stakeholder groups to select candidate items for a consensus meeting. A final COS-TCM-CHF will be developed at a face-to-face consensus meeting involving representatives from the different stakeholders.Ethics and disseminationEthical approval of this study has been granted by Evidence-based Medicine Centre of Tianjin University of Traditional Chinese Medicine Research Ethics Committee (TJUTCMEC201200002). We will disseminate our research findings of the final COS on the website of Chinese Clinical Trials for Core Outcome Set, with open access publications and present at international conferences to reach a wide range of knowledge users.Trial registration numberhttp://www.comet-initiative.org/studies/details/1486.
Background As a bioactive metabolite preparation widely used in acute ischemic stroke (AIS), the efficacy and safety of Panax notoginseng saponins injections (PNSI) in patients with AIS after ...intravenous thrombolysis remain to be evaluated. Methods This study included randomized controlled trials published before 26 April 2024 in 8 databases. AIS patients who received intravenous thrombolysis were included. The control group receiving conventional treatment and the treatment group receiving additional PNSI. Primary outcomes were selected as mortality, disability, and adverse events. Secondary outcomes were selected as all-cause mortality, improvement of neurological deficit, quality of life, and cerebral injury indicators. The revised Cochrane Risk of Bias tool was used to assess risk of bias. Risk ratio (RR) and mean differences (MD) were calculated for binary variables and continuous variables, respectively, based on a 95% confidence interval (CI). Results A total of 20 trials involving 1,856 participants were included. None of them reported mortality or disability. There was no significant difference in the adverse events RR: 1.04; 95% CI: 0.60 to 1.81 and hemorrhagic transformation RR: 0.99; 95% CI: 0.36 to 2.70 between the two groups. Compared to the control group, the treatment group had a better effect in neurological improvement assessed by National Institutes of Health Stroke Scale MD: −2.91; 95% CI: −4.76 to −1.06, a better effect in activities of daily living changes in Barthel Index MD: 9.37; 95% CI: 1.86 to 16.88, and a lower serum neuron-specific enolase level MD: −2.08; 95% CI: −2.67 to −1.49. Conclusion For AIS patients undergoing intravenous thrombolysis, the use of PNSI improved neurological deficits and enhanced activity of daily living in the short term without increasing the occurrence rate of adverse events. However, due to the moderate to very low certainty of evidence, it is advisable to conduct high-quality clinical trials to validate the findings of this study. Systematic Review Registration https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=466851 , Identifier CRD42023466851
Data centers undertake transfer, calculation, and store of important information, whose suitable thermal environment is necessary for the safe and reliable operation of information technology (IT) ...equipment. However, in case of the emergency failure or power outage of the air-conditioning system, the inappropriate thermal environment cannot keep the proper operation of IT equipment. Therefore, a novel cooling system is proposed to maintain the thermal environment of server rooms, in which the liquid nitrogen as refrigerant flows into the spiral finned tube heat exchanger (FTHE) by phase changing to take away indoor heat. The effect of horizontal spacings and heights of the FTHE on the thermal environment are investigated numerically. The results display that the indoor air temperature is divided by FTHE. When the height of FTHE is 2.6~2.9m, the higher the FTHE, the more uniform the indoor temperature distribution. When the FTHE is higher than 3.2 m, the maximum temperature of the heat source is more than 62.6°C, exceeding the temperature tolerance limit. In addition, if space permits, the dislocation layout and the fixed layout can be selected, which perform well in both temperature uniformity and heat source cooling. This investigation provides support for the arrangement of the novel cooling system.
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