Thermodynamic characteristics are of great importance for the performance of a high-temperature flow-rate control valve,as high-temperature environment may bring problems,such as blocking of spool and increasing of le...Thermodynamic characteristics are of great importance for the performance of a high-temperature flow-rate control valve,as high-temperature environment may bring problems,such as blocking of spool and increasing of leakage,to the valve.In this paper,a high-temperature flow-rate control valve,pilot-controlled by a pneumatic servo system is developed to control the fuel supply for scramjet engines.After introducing the construction and working principle,the thermodynamic mathematical models of the valve are built based on the heat transfer methods inside the valve.By using different boundary conditions,different methods of simulations are carried out and compared.The steady-state and transient temperature field distribution inside the valve body are predicted and temperatures at five interested points are measured.By comparing the simulation and experimental results,a reasonable 3D finite element analysis method is suggested to predict the thermodynamic characteristics of the high-temperature flow-rate control valve.展开更多
Regulators are important components in pneumatic system, and their flow-rate characteristics are the key parameters for designers. According to the correlatively international standard and national standard of China, ...Regulators are important components in pneumatic system, and their flow-rate characteristics are the key parameters for designers. According to the correlatively international standard and national standard of China, which describe the flow-rate characteristics measurement method of pneumatic regulators, the pressure and the flow are measured point by point, and then the flow-rate characteristics curve is plotted point to point. This method has some disadvantages, such as equipment complexity, much air consumption, and low efficiency. To settle the problems presented above, this paper puts forward a new high efficient and energy saving flow-rate characteristics measurement method of regulators, which is based on the pressure response when charging and discharging to an isothermal tank without any flow meters. The measurement principle, the system and the steps are introduced. And the tracking differentiator is used for the data processing of the pressure difference. Two typical kinds of regulators were experimentally investigated, and their flow-rate characteristics curves were obtained with the new and the conventional method, respectively. Comparatively, it＇s proved that this new method is feasible because it is not only able to meet the demand of the measurement precision, but also to save energy and improve efficiency. Compared to the conventional method, the new method takes only about 1/10 amount of time and consumes about only 1/30 amount of air. Hopefully it will be able to serve as an international standard of flow-rate characteristics measurement method of regulators.展开更多
Lithium ion battery cathode material LiNi0.8Co0.1Mn0.1O2(NCM811)was synthe-sized via a spray drying method.The effect of different spray drying flow-rates(200,250,300,and 400 mL·min^-1)on the structural and elect...Lithium ion battery cathode material LiNi0.8Co0.1Mn0.1O2(NCM811)was synthe-sized via a spray drying method.The effect of different spray drying flow-rates(200,250,300,and 400 mL·min^-1)on the structural and electrochemical properties of NCM811 are investigated.We find that the contents of Ni,Co,and Mn in the NCM811 cathode materials do not change significantly with the changing flow-rate,but the lattice parameter and morphology of the materials are significantly affected.Under the optimal spray drying flow-rate(250 mL·min^-1),the obtained NCM811 cathode(250NCM811)exhibits the best crystallinity,with the highest ratio of I(003)/I(104)in the XRD pattern.SEM images reveal the spherical morphology of 250NCM811 and the average diameter of about 5 mm.The results of electrochemical test show that the reversible capacity of 250NCM811 reaches 210 mA·g^-1 at 0.2 C(1 C=280 mA·g^-1).After 100 charge-discharge cycles at 1 C,the battery retains more than 94%of its initial capacity.Overall,spray drying flow-rate demonstrates great effect on the electrochemical properties of NCM811.展开更多
文摘Thermodynamic characteristics are of great importance for the performance of a high-temperature flow-rate control valve,as high-temperature environment may bring problems,such as blocking of spool and increasing of leakage,to the valve.In this paper,a high-temperature flow-rate control valve,pilot-controlled by a pneumatic servo system is developed to control the fuel supply for scramjet engines.After introducing the construction and working principle,the thermodynamic mathematical models of the valve are built based on the heat transfer methods inside the valve.By using different boundary conditions,different methods of simulations are carried out and compared.The steady-state and transient temperature field distribution inside the valve body are predicted and temperatures at five interested points are measured.By comparing the simulation and experimental results,a reasonable 3D finite element analysis method is suggested to predict the thermodynamic characteristics of the high-temperature flow-rate control valve.
文摘Regulators are important components in pneumatic system, and their flow-rate characteristics are the key parameters for designers. According to the correlatively international standard and national standard of China, which describe the flow-rate characteristics measurement method of pneumatic regulators, the pressure and the flow are measured point by point, and then the flow-rate characteristics curve is plotted point to point. This method has some disadvantages, such as equipment complexity, much air consumption, and low efficiency. To settle the problems presented above, this paper puts forward a new high efficient and energy saving flow-rate characteristics measurement method of regulators, which is based on the pressure response when charging and discharging to an isothermal tank without any flow meters. The measurement principle, the system and the steps are introduced. And the tracking differentiator is used for the data processing of the pressure difference. Two typical kinds of regulators were experimentally investigated, and their flow-rate characteristics curves were obtained with the new and the conventional method, respectively. Comparatively, it＇s proved that this new method is feasible because it is not only able to meet the demand of the measurement precision, but also to save energy and improve efficiency. Compared to the conventional method, the new method takes only about 1/10 amount of time and consumes about only 1/30 amount of air. Hopefully it will be able to serve as an international standard of flow-rate characteristics measurement method of regulators.
基金Supported by the National Natural Science Foundation of China(No.51602310)Fujian Provincial Department of Science and Technology(2019T3017)the DNL Cooperation Fund,CAS(DNL180308)。
文摘Lithium ion battery cathode material LiNi0.8Co0.1Mn0.1O2(NCM811)was synthe-sized via a spray drying method.The effect of different spray drying flow-rates(200,250,300,and 400 mL·min^-1)on the structural and electrochemical properties of NCM811 are investigated.We find that the contents of Ni,Co,and Mn in the NCM811 cathode materials do not change significantly with the changing flow-rate,but the lattice parameter and morphology of the materials are significantly affected.Under the optimal spray drying flow-rate(250 mL·min^-1),the obtained NCM811 cathode(250NCM811)exhibits the best crystallinity,with the highest ratio of I(003)/I(104)in the XRD pattern.SEM images reveal the spherical morphology of 250NCM811 and the average diameter of about 5 mm.The results of electrochemical test show that the reversible capacity of 250NCM811 reaches 210 mA·g^-1 at 0.2 C(1 C=280 mA·g^-1).After 100 charge-discharge cycles at 1 C,the battery retains more than 94%of its initial capacity.Overall,spray drying flow-rate demonstrates great effect on the electrochemical properties of NCM811.
