In this paper, the properties and energy saving protential of a capacity control systemby varing the composition of a mixture has been analysized and experimented. The mixturesR22/142b, R32/124 and R32/134a have been ...In this paper, the properties and energy saving protential of a capacity control systemby varing the composition of a mixture has been analysized and experimented. The mixturesR22/142b, R32/124 and R32/134a have been proposed as the working fiuids to adjust thecapacity of the system with load change. The results show that if it is effective to control therefrigerant composition and capacities, the improvements for the seasonal energy efficiencyratio will be obtained.展开更多
The total emission control method based on atmospheric environmental capacity is the most effective in air pollution mitigation. The atmospheric environmental capacities of SO2 on representative days over Lanzhou are ...The total emission control method based on atmospheric environmental capacity is the most effective in air pollution mitigation. The atmospheric environmental capacities of SO2 on representative days over Lanzhou are estimated using the numerical models RAMS, HYPACT and a linear programming model, according to the national ambient air quality standard of China （NAAQSCHN）. The results show that the fields of meteorological elements and SO2 simulated by the models agree reasonably well with observations. The atmospheric environmental capacity of SO2 over Lanzhou is around 111.7 × 10^3 kg d^-1, and in order to meet the air quality level Ⅱ of the NAAQSCHN, SO2 emissions need to be reduced by 20%.展开更多
This paper presents the structure of a new system, which can efficiently separate therefrigerant mixture and vary the composition inside the circuit to adjust the capacities ofthe system with load changes. A dynamic a...This paper presents the structure of a new system, which can efficiently separate therefrigerant mixture and vary the composition inside the circuit to adjust the capacities ofthe system with load changes. A dynamic and distributed model is developed to analyzethe dynamic characteristics in the course of variation of composition. It is shown there aresome optimizing design parameters for the new system. If the system designed by optimizingparameters, it will be effective to adjust the composition in the system.展开更多
Nanofibrous media with both high particle interception efficiency and robust air permeability has broad technological applications in areas including individual protection, industrial security, and environmental gover...Nanofibrous media with both high particle interception efficiency and robust air permeability has broad technological applications in areas including individual protection, industrial security, and environmental governance. However, producing such filtration media has proven to be extremely challenging. Here we reported an approach to preparing and fabricating a polyvinylidene fluoride (PVDF) nanofiber composite filter medium composed of 2D PVDF nanofiber nets and a stable substrate via onestep electrospinning for effective air filtration. PVDF nanofibers are obtained by adjusting the electrospinning process. With the combined properties of ultrasmall diameter, high porosity, and a bonded scaffold, the resulting PVDF nanofiber composite filter medium exhibits a robust high filtration efficiency of 99.901%(equivalent to an F9 rating) for 0.4 mm particles and a long service life (a large dust holding capacity of 36 g/m^2) for ultrafine airborne particles based on the sieving principle and surface filtration behavior. The successful synthesis of PVDF nanofibers medium would not only make it a promising candidate for air filtration, but also provide new insights into the design and development of composite nanofiber structures for various applications.展开更多
文摘In this paper, the properties and energy saving protential of a capacity control systemby varing the composition of a mixture has been analysized and experimented. The mixturesR22/142b, R32/124 and R32/134a have been proposed as the working fiuids to adjust thecapacity of the system with load change. The results show that if it is effective to control therefrigerant composition and capacities, the improvements for the seasonal energy efficiencyratio will be obtained.
基金the National Natural Science Foundation of China （Grant No. 40305020）.
文摘The total emission control method based on atmospheric environmental capacity is the most effective in air pollution mitigation. The atmospheric environmental capacities of SO2 on representative days over Lanzhou are estimated using the numerical models RAMS, HYPACT and a linear programming model, according to the national ambient air quality standard of China （NAAQSCHN）. The results show that the fields of meteorological elements and SO2 simulated by the models agree reasonably well with observations. The atmospheric environmental capacity of SO2 over Lanzhou is around 111.7 × 10^3 kg d^-1, and in order to meet the air quality level Ⅱ of the NAAQSCHN, SO2 emissions need to be reduced by 20%.
文摘This paper presents the structure of a new system, which can efficiently separate therefrigerant mixture and vary the composition inside the circuit to adjust the capacities ofthe system with load changes. A dynamic and distributed model is developed to analyzethe dynamic characteristics in the course of variation of composition. It is shown there aresome optimizing design parameters for the new system. If the system designed by optimizingparameters, it will be effective to adjust the composition in the system.
基金supported by the Science and Technology Project of Chaoyang District, Beijing, China (CYGX1709)the National Key R & D Program of China (2017YFE0101500)
文摘Nanofibrous media with both high particle interception efficiency and robust air permeability has broad technological applications in areas including individual protection, industrial security, and environmental governance. However, producing such filtration media has proven to be extremely challenging. Here we reported an approach to preparing and fabricating a polyvinylidene fluoride (PVDF) nanofiber composite filter medium composed of 2D PVDF nanofiber nets and a stable substrate via onestep electrospinning for effective air filtration. PVDF nanofibers are obtained by adjusting the electrospinning process. With the combined properties of ultrasmall diameter, high porosity, and a bonded scaffold, the resulting PVDF nanofiber composite filter medium exhibits a robust high filtration efficiency of 99.901%(equivalent to an F9 rating) for 0.4 mm particles and a long service life (a large dust holding capacity of 36 g/m^2) for ultrafine airborne particles based on the sieving principle and surface filtration behavior. The successful synthesis of PVDF nanofibers medium would not only make it a promising candidate for air filtration, but also provide new insights into the design and development of composite nanofiber structures for various applications.
