A Novel Vapor Injection Structure on the Blade for Rotary Compressor

Rotary compressors have been extensively used in room air conditioners and household refrigerators for their advantages, including high efficiency, strong adaptability, and low cost. However, when air source heat pumps with rotary compressors are applied in cold regions, a series of problems appear. The gas injection has been proved an effective technology to enhance both the heating capacity and COP of scroll, screw, and rotary compressors. In the one-cylinder rotary compressor with gas injection, the compressor injection port is often opened on the cylinder wall. In order to extend the injection time for injecting more refrigerant, the injection port is settled as close as possible to the discharge port. However, the limited area of the injection port and the unavoidable back-flowing of the injection refrigerant into the suction tube diminish the merits of gas injection on the one-cylinder rotary compressor. A novel vapor injection structure on the blade for the rotary compressor has been proposed in this paper to overcome the back-flowing drawback of the traditional cylinder injection structure and increase the injection area. Based on a verified numerical model, the performance of a rotary compressor with the blade injection structure has been investigated. The results indicate that: the proposed vapor injection structure can eliminate the back-flowing of the injected refrigerant; compared to the traditional injection structure, the new structure can enhance the volumetric efficiency and mass flow-rate by 1.8~2.7% and 26.6~57.2%, respectively; and compared to the traditional injection structure, the new structure can increase the heating capacity and COP by 23.1~48.9% and 3.2~8.0%, respectively

Comparative Research on Air Conditioner with Gas-injected Rotary Compressor through Injection Port on Blade

Rotary compressors are widely utilized in air conditionders and heat pumps. However, when rotary compressors were applied in room air conditioners, VRFs and domestic water heaters, the systems will experience heavily degradation of the heating capacity and COP as the ambient temperature goes low. Aimed at these problems, considerable research has been carried out to raise a series of solutions, such as economizer technology, cascade-type vapor compression heat pump system and two stage coupling heat pump system. At present, economizer technology has become a critical method to improve the performance of air source heat pumps with rotary compressors in low ambient temperature. A novel vapor injection structure on a blade for a rotary compressor has been proposed in previous paper to overcome the drawback of the traditional cylinder injection structure. Based on a verified numerical model, the performance of air source heat pumps with rotary compressors with different economizer technology including a two-stage rotary compressor, a single-stage rotary compressor with traditional injection structure and a single rotary compressor with the novel injection structure has been investigated. The results indicate that: compared to rotary compressors with traditional injection structure, air source heat pump with a rotary compressor with proposed injection structure can enhance the heating capacity and COP by 13%~15% and 4.8%~9.6%, respectively; and compared to the twin-cylinder rotary compressor, the performance of air source heat pump with a rotary compressor with proposed injection structure is almost the same, so the rotary compressor with the novel injection structure could be considered to replace the two-stage rotary compressor

Development and evaluation of a Planktonic Integrity Index (PII) for Jingpo Lake, China

A Planktonic Integrity Index (PII) for the China’s largest alpine barrier lake (Jingpo Lake) was developed to assess the water quality of Jingpo Lake by using phytoplankton and zooplankton metrics. Phytoplankton and zooplankton assemblages were sampled at 26 sites in Jingpo Lake. A total of 140 species of phytoplankton and 92 species of zooplankton were obtained in the investigations. We used a stepwise process to evaluate properties of candidate metrics and selected five for the PII: Algal cell abundance, Species richness of algae, Trophic diatom index, Zooplankton Shannon index, and Zooplankton Margalef index. Evaluation of the PII showed that it discriminated well between reference and impaired sites and the discriminatory biocriteria of the PII were suitable for the assessment of the water quality of Jingpo Lake. The further scoring results from the 26 sites showed that the water quality of Jingpo Lake was fair to good. The results of analyses between PII and major environmental factors indicated that water temperature (WT), transparency (SD), dissolved oxygen (DO), potassium permanganate (CODMn) and total nitrogen (TN) were the main factors influencing on the composition and distribution of phytoplankton and zooplankton. Additionally, more metrics belonging to habitat, hydrology, physics and chemistry should be considered for the PII, so as to establish comprehensive assessment system which can reflect the community structure of aquatic organisms, physical and chemical characteristics of water environment, human activities, etc

Exploring the regional pollution characteristics and meteorological formation mechanism of PM2.5 in North China during 2013–2017

In the last decade, North China (NC) has been one of the most populated and polluted regions in the world. The regional air pollution has had a serious impact on people's health; thus, all levels of government have implemented various pollution prevention measures since 2013. Based on multi-city in situ environmental and meteorological data, as well as the meteorological reanalysis dataset from 2013 to 2017, regional pollution characteristics and meteorological formation mechanisms were analyzed to provide a more comprehensive understanding of the evolution of PM2.5 in NC. The domain-averaged PM2.5 was 79 +/- 17 mu g m(-3) from 2013 to 2017, with a decreasing rate of 10 mu g m(-3) yr(-1). Two automatic computer algorithms were established to identify 6 daily regional pollution types (DRPTs) and 48 persistent regional pollution events (PRPEs) over NC during 2014-2017. The average PM2.5 concentration for the Large-Region-Pollution type (including the Large-Moderate-Region-Pollution and Large-Severe-Region-Pollution types) was 113 +/- 40 mu g m(-3), and more than half of Large-Region-Pollution days and PRPEs occurred in winter. The PRPEs in NC mainly developed from the area south of Hebei. The number of Large-Region-Pollution days decreased notably from 2014 to 2017, the annual number of days varying between 194 and 97 days, whereas a slight decline was observed in winter. In addition, the averaged PM2.5 concentrations and the numbers and durations of the PRPEs decreased. Lamb-Jenkinson weather typing was used to reveal the impact of synoptic circulations on PM2.5 across NC. Generally, the contributions of the variations in circulation to the reduction in PM2.5 levels over NC between 2013 and 2017 were 64% and 45% in summer and winter, respectively. The three most highly polluted weather types were types C, S and E, with an average PM2.5 concentration of 137 +/- 40 mu g m(-3) in winter. Furthermore, three typical circulation dynamics were categorized in the peak stage of the PRPEs, namely, the southerly airflow pattern, the northerly airflow pattern and anticyclone pattern; the averaged relative humidity, recirculation index, wind speed and boundary layer height were 63%, 0.33, 2.0 m s(-1) and 493 m, respectively. Our results imply that additional emission reduction measures should be implemented under unfavorable meteorological situations to attain ambient air quality standards in the future.Peer reviewe

Experimental Study on Reducing CO2–Oil Minimum Miscibility Pressure with Hydrocarbon Agents

CO2 flooding is an important method for improving oil recovery for reservoirs with low permeability. Even though CO2 could be miscible with oil in regions nearby injection wells, the miscibility could be lost in deep reservoirs because of low pressure and the dispersion effect. Reducing the CO2–oil miscibility pressure can enlarge the miscible zone, particularly when the reservoir pressure is less than the needed minimum miscible pressure (MMP). Furthermore, adding intermediate hydrocarbons in the CO2–oil system can also lower the interfacial tension (IFT). In this study, we used dead crude oil from the H Block in the X oilfield to study the IFT and the MMP changes with different hydrocarbon agents. The hydrocarbon agents, including alkanes, alcohols, oil-soluble surfactants, and petroleum ethers, were mixed with the crude oil samples from the H Block, and their performances on reducing CO2–oil IFT and CO2–oil MMP were determined. Experimental results show that the CO2–oil MMP could be reduced by 6.19 MPa or 12.17% with petroleum ether in the boiling range of 30–60 °C. The effects of mass concentration of hydrocarbon agents on CO2–oil IFT and crude oil viscosity indicate that the petroleum ether in the boiling range of 30–60 °C with a mass concentration of 0.5% would be the best hydrocarbon agent for implementing CO2 miscible flooding in the H Block

Incidence and risk factors of urinary tract infection in hospitalized patients with spinal cord injury in a hospital of China

Abstract Urinary tract infection (UTI) caused by spinal cord injury (SCI) can have significant morbidity. There is currently a lack of relevant data in China. This study explores incidence and risk factors of UTI in hospitalized patients with SCI in China, and will help healthcare professionals to make informed clinical decisions to reduce the incidence of UTI. This retrospective study analyzed the medical records of patients with SCI who were hospitalized at three campuses of a hospital in central China between August 2014 and August 2023. The files of patients with SCI were reviewed for demographics and clinical characteristics. Logistic regression analysis was performed to identify risk factors associated with UTI. A total of 538 patients were included in this study. The incidence of UTI was 49.8%. Sex, hypoproteinemia, urinary incontinence, bladder irrigation, timing of rehabilitation, duration of indwelling urinary catheter were risk factors of UTI. The implementation of specific preventive measures is anticipated to result in a decrease in the occurrence of UTI among individuals with SCI, consequently enhancing their overall quality of life and prognosis

Study on the Fingerprint and Atmospheric Activity of Volatile Organic Compounds from Typical Industrial Emissions

China is prone to severe surface ozone pollution in summer, so it is very important to understand the source of volatile organic compounds (VOCs) to control ozone formation. In this work, the emission characteristics of 91 VOC components from the plastic products industry, packaging and printing industries, printing ink industry, furniture manufacturing and vehicle manufacturing industries were studied. The results show that there are significant differences between these sources, and for the plastic products industry, alkanes (48%) are the most abundant VOCs. The main emission species in the packaging and printing industry are OVOCs (36%) and alkanes (34%). The proportion of OVOCs in the printing ink (73%) and furniture manufacturing industries (49%) is dominated by VOC emissions; aromatic hydrocarbons (33%), alkanes (33%), and OVOCs (17%) are the main emission species in the vehicle manufacturing industry. At the same time, the ozone generation potential (OFP) and secondary organic aerosol formation potential (SOA) of anthropogenic VOC emissions were evaluated, and the top 10 contributors to OFP and SOA were identified. Toluene, o-xylene, and m-xylene had a significant tendency to form OFP or SOA. Then, a health risk assessment of VOC components was carried out. These data can supplement the existing VOC emission characteristics of anthropogenic emissions, thus enriching the research progress of VOC emission sources

Experimental Evaluation of the Transport Mechanisms of PoIFN-α in Caco-2 Cells

For the development of an efficient intestinal delivery system for Porcine interferon-α (PoIFN-α), the understanding of transport mechanisms of which in the intestinal cell is essential. In this study, we investigated the absorption mechanisms of PoIFN-α in intestine cells. Caco-2 cells and fluorescein isothiocyanate-labeled (FITC)-PoIFN-α were used to explore the whole transport process, including endocytosis, intracellular trafficking, exocytosis, and transcytosis. Via various techniques, the transport pathways of PoIFN-α in Caco-2 cells and the mechanisms were clarified. Firstly, the endocytosis of PoIFN-α by Caco-2 cells was time, concentration and temperature dependence. And the lipid raft/caveolae endocytosis was the most likely endocytic pathway for PoIFN-α. Secondly, both Golgi apparatus and lysosome were involved in the intracellular trafficking of PoIFN-α. Thirdly, the treatment of indomethacin resulted in a significant decrease of exocytosis of PoIFN-α, indicating the participation of cyclooxygenase. Finally, to evaluate the efficiency of PoIFN-α transport, the transepithelial electrical resistance (TEER) value was measured to investigate the tight junctional integrity of the cell monolayers. The fluorescence microscope results revealed that the transport of PoIFN-α across the Caco-2 cell monolayers was restricted. In conclusion, this study depicts a probable picture of PoIFN-α transport in Caco-2 cells characterized by non-specificity, partial energy-dependency and low transcytosis