Inhibiting the agglomeration of molten aluminum particles packed in the binder network is a promising scheme to achieve efficient combustion of solid propellants.In this investigation,the hydroxyl-terminated structure...Inhibiting the agglomeration of molten aluminum particles packed in the binder network is a promising scheme to achieve efficient combustion of solid propellants.In this investigation,the hydroxyl-terminated structured fluorinated alcohol compound(PFD)was introduced to modify the traditional polyethylene glycol/polytetrahydrofuran block copolymerization(HTPE)binder;that is,a unique fluorinated polyether(FTPE)binder was synthesized by embedding fluorinated organic segments into the HTPE binder via crosslinking curing.The FTPE was applied in aluminum-based propellants for the first time.Due to the complete release of fluorinated organic active segments in the range of 300℃to 400℃,the burning rate of FTPEbased propellant increased from 4.07(0%PFD)to 6.36 mm/s(5%PFD),increased by 56.27%under 1 MPa.The reaction heat of FTPE propellants increased from 5.95(0%PFD)to 7.18 MJ/kg(5%PFD)under 3.0 MPa,indicating that HTPE binder modified with PFD would be conducive to inhibiting the D90 of condensed combustion products(CCPs)dropped by 81.84%from 75.46(0%PFD)to 13.71μm(5%PFD)under 3.0 MPa,in consistent with the significant reduction of aluminum agglomerates observed on the quenched burning surface of the propellants.Those results demonstrated that a novel FTPE binder with PFD can release fluorinated organic active segments,which motivate preignition reaction with the alumina shell in the early stage of aluminum combustion,and then enhance the melting diffusion effect of aluminum to inhibit the agglomeration.展开更多
Airports are the primary venues for aircraft operations during the Landing and Take-off(LTO)phase and constitute a major component of aviation's overall carbon emissions.By combining the International Civil Aviati...Airports are the primary venues for aircraft operations during the Landing and Take-off(LTO)phase and constitute a major component of aviation's overall carbon emissions.By combining the International Civil Aviation Organization(ICAO)standard emission model with an emission inventory compiled according to the proportion of aircraft takeoff and landing operations at airports,this study calculates a long-term series of carbon emissions for all operating airports in China(excluding Hong Kong,Macao,and Taiwan of China)from 2005 to 2022.Using the Kernel Density Analysis tool,the study identifies the agglomeration characteristics and evolutionary trends of airport carbon emissions within the jurisdictions of China's seven air traffic control regions.Furthermore,by integrating the Stochastic Impacts by regression on Population,Affluence,and Technology model with a spatial panel regression model,the influencing factors and spatial effects of airport carbon emissions in China are examined.The findings are as follows.1)From 2005 to 2022,carbon emissions from China's civil aviation airports generally showed a trend of steady growth followed by fluctuating decline;specifically,it increased at an average annual rate of 9.01%from 2005 to 2019 and decreased at an average annual rate of 11.27%from 2020 to 2022.Among China's seven air traffic control regions,the growth rate of airport carbon emissions was more significant in the Southwest Region,Xinjiang Region,Northwest Region,and Northeast Region,while the growth was relatively slow in the three traditional hub airport-concentrated regions(Northern Region,Eastern Region,and Central and Southern Region).2)With 2020 as the dividing line,the proportion of LevelⅠand LevelⅡairports in terms of carbon emissions among the seven air traffic control regions first decreased and then increased,while the proportion of LevelⅢ,LevelⅣ,and LevelⅤairports first increased and then decreased.3)The number of medium-high-density core areas of airport carbon emissions in China increased from 8 to 14,with a relatively stable agglomeration trend.These core areas are mainly distributed east and south of the Hu Huanyong Line.4)Six indicators exert a positive impact on airport carbon emissions in a region,namely urban population density,air passenger traffic by region,per capita Gross Domestic Product(GDP),per capita social consumer goods retail sales,per capita disposable income,and regional international tourism income.In contrast,five indicators exert a negative impact,including the unemployment rate,regional general public budget expenditure,regional general science and technology budget expenditure,Research and Development(R&D)expenditure,and number of patent applications.This study breaks through the limitation of solely using the ICAO model for research,comprehensively presents the trends and spatiotemporal heterogeneity of China's airport carbon emissions over a medium and long time period,and conducts a comparative analysis of the differences before and after the epidemic.It has theoretical guiding significance for comprehensively grasping the overall trend of aviation carbon emissions and positive practical significance for promoting the green development of the civil aviation industry.展开更多
基金Fundamental Research Funds for the Central Universities,Grant/Award Number:3052017010。
文摘Inhibiting the agglomeration of molten aluminum particles packed in the binder network is a promising scheme to achieve efficient combustion of solid propellants.In this investigation,the hydroxyl-terminated structured fluorinated alcohol compound(PFD)was introduced to modify the traditional polyethylene glycol/polytetrahydrofuran block copolymerization(HTPE)binder;that is,a unique fluorinated polyether(FTPE)binder was synthesized by embedding fluorinated organic segments into the HTPE binder via crosslinking curing.The FTPE was applied in aluminum-based propellants for the first time.Due to the complete release of fluorinated organic active segments in the range of 300℃to 400℃,the burning rate of FTPEbased propellant increased from 4.07(0%PFD)to 6.36 mm/s(5%PFD),increased by 56.27%under 1 MPa.The reaction heat of FTPE propellants increased from 5.95(0%PFD)to 7.18 MJ/kg(5%PFD)under 3.0 MPa,indicating that HTPE binder modified with PFD would be conducive to inhibiting the D90 of condensed combustion products(CCPs)dropped by 81.84%from 75.46(0%PFD)to 13.71μm(5%PFD)under 3.0 MPa,in consistent with the significant reduction of aluminum agglomerates observed on the quenched burning surface of the propellants.Those results demonstrated that a novel FTPE binder with PFD can release fluorinated organic active segments,which motivate preignition reaction with the alumina shell in the early stage of aluminum combustion,and then enhance the melting diffusion effect of aluminum to inhibit the agglomeration.
基金Under the auspices of the National Natural Science Foundation of China(No.42071266)the Third Batch of Hebei Youth Top Talent Project,Hebei Natural Science Foundation(No.D2021205013)。
文摘Airports are the primary venues for aircraft operations during the Landing and Take-off(LTO)phase and constitute a major component of aviation's overall carbon emissions.By combining the International Civil Aviation Organization(ICAO)standard emission model with an emission inventory compiled according to the proportion of aircraft takeoff and landing operations at airports,this study calculates a long-term series of carbon emissions for all operating airports in China(excluding Hong Kong,Macao,and Taiwan of China)from 2005 to 2022.Using the Kernel Density Analysis tool,the study identifies the agglomeration characteristics and evolutionary trends of airport carbon emissions within the jurisdictions of China's seven air traffic control regions.Furthermore,by integrating the Stochastic Impacts by regression on Population,Affluence,and Technology model with a spatial panel regression model,the influencing factors and spatial effects of airport carbon emissions in China are examined.The findings are as follows.1)From 2005 to 2022,carbon emissions from China's civil aviation airports generally showed a trend of steady growth followed by fluctuating decline;specifically,it increased at an average annual rate of 9.01%from 2005 to 2019 and decreased at an average annual rate of 11.27%from 2020 to 2022.Among China's seven air traffic control regions,the growth rate of airport carbon emissions was more significant in the Southwest Region,Xinjiang Region,Northwest Region,and Northeast Region,while the growth was relatively slow in the three traditional hub airport-concentrated regions(Northern Region,Eastern Region,and Central and Southern Region).2)With 2020 as the dividing line,the proportion of LevelⅠand LevelⅡairports in terms of carbon emissions among the seven air traffic control regions first decreased and then increased,while the proportion of LevelⅢ,LevelⅣ,and LevelⅤairports first increased and then decreased.3)The number of medium-high-density core areas of airport carbon emissions in China increased from 8 to 14,with a relatively stable agglomeration trend.These core areas are mainly distributed east and south of the Hu Huanyong Line.4)Six indicators exert a positive impact on airport carbon emissions in a region,namely urban population density,air passenger traffic by region,per capita Gross Domestic Product(GDP),per capita social consumer goods retail sales,per capita disposable income,and regional international tourism income.In contrast,five indicators exert a negative impact,including the unemployment rate,regional general public budget expenditure,regional general science and technology budget expenditure,Research and Development(R&D)expenditure,and number of patent applications.This study breaks through the limitation of solely using the ICAO model for research,comprehensively presents the trends and spatiotemporal heterogeneity of China's airport carbon emissions over a medium and long time period,and conducts a comparative analysis of the differences before and after the epidemic.It has theoretical guiding significance for comprehensively grasping the overall trend of aviation carbon emissions and positive practical significance for promoting the green development of the civil aviation industry.
