Abstract: The design of a common high-speed (20000r.min-1) motor-driven fuel cell vehicle than the low-speed
dell 8N544 battery centrifugal compressor. Summed up the characteristics of the compressor design and the use of three-dimensional numerical simulation (CFD) preliminary technical study of the compressor impeller flow field, has been corresponding with the characteristics of the main parameters of air distribution. According to the numerical simulation analysis of the fuel cell vehicle designed for low-speed centrifugal compressor with high efficiency and a more broad and flat work features in the design of the impeller speed up to 83% in the most efficient, high-pressure than the most up to 1.6, Flow in the range of 0.05 ~ 0.20kg.s-1. The design of low-speed centrifugal compressor, to meet the on-board fuel cell system for the air compressor requirements, while avoiding the high-speed centrifugal compressor needed to bring the ultra-high-speed motor.
Key words: fuel cells; centrifugal compressor; low speed
Fuel cell vehicles have zero emissions, high
hp F4809A battery ,
hp F4812A battery ,
hp Pavilion ZV5000 battery efficiency, rapid response, etc., is the world's countries and all major car company to study the hot spots; the core of which is fuel cell technology. Pressurized air for the fuel cell system is essential, and its performance has a direct link. Pressurized fuel cell system than the low-pressure fuel cell systems have higher power density and efficiency, but also to improve the water balance.
Fuel cell air pressurization system to the specific requirements are: compact size, quality, lightweight, non-oil and gas supply air pollution, low noise, the maintenance of low-cost
hp 371786-001 battery ,
hp 371785-001 battery ,
hp 361742-001 battery , low-cost and high efficiency. At present, positive displacement compressor in the fuel cell system widely used in the air, is the most typical screw compressor; but it is difficult to match with the turbine, not exhaust energy recovery, so that further lowering energy consumption. Exhaust energy recovery, only through the turbine and centrifugal compressor to achieve the match. Centrifugal compressor was also quick to respond with a long life, high efficiency advantages, the future is considered to be the most promising way of one of the booster.
At present, exhaust system, fuel cell energy enough to drive turbine-driven compressor, an auxiliary power source is therefore essential. Ultra-high-speed (about 60000r.min-1) can be used as an effective electrical auxiliary power source of choice. Honeywell is developing an ultra high-speed motor-driven auxiliary high-speed centrifugal turbochargers
hp HSTNN-UB02 battery . This makes the application of high-pressure compressor fuel cell more compact air pressure system, speed up the response. But the application of ultra-high-speed motor, there are many problems, such as the cost is too high, the maintenance of the complex, poor stability of the need for special measures to cool, and so on, and there is a high-speed rotating shaft to deal with complex issues such as load balance, hindering the commercialization of fuel cell engine, which So that the promotion of fuel cell vehicles become a problem
Ordinary high-speed (about 20000r.min-1) motor is a super-high-speed motor to avoid the above-mentioned shortcomings. But if the centrifugal compressor is still using conventional high-speed design, compression ratio can reach 1.1 to 1.2, unable to meet the fuel cell system booster
hp DP390A battery ,
hp 346970-001 battery . It is therefore necessary to develop a new design of centrifugal compressor to the same speed and traffic conditions, the substantial increase in compression ratio, that is designed to develop a low-speed centrifugal compressor. In low-speed conditions, the design of high-efficiency, wide range of centrifugal compressor is a great challenge, little information at home and abroad for reference.
By using design software for the design of Concept fuel cell vehicle than the low-speed centrifugal compressor, and computational fluid dynamics software for Numeca flow analysis, design performance has been better than the low-speed centrifugal compressor.
1 compressor design
According to the design requirements of the
Apple battery program , on-board fuel cell than the low-speed compressor of the main design parameters are: the design speed 20000r.min-1, the design pressure ratio of 1.5, the flow 0.1kg.s-1, and must meet certain Surge Margin. In the ordinary high-speed motor rated speed 20000r.min-1 conditions, the compression ratio has to be as high as 1.5, its nature and design of conventional centrifugal compressor design is quite different.
1.1 lower than the speed of design
Compressor speed (a dimensionless) is defined as
Where: ω for speed, Q for the volume of traffic, Δh for the enthalpy-entropy, and so on by. Speed can be reflected as the compressor acting ability. Similarly, under the conditions of speed, lower than the speed can reach higher than the
hp HSTNN-LB31 pressure. Orders are usually designed for high-speed than the speed in the 0.7 to 1.0, access to higher efficiency. Low-speed compressor against high-pressure gradient, the proportion of secondary flow, must be a profound understanding of the inherent characteristics of the flow in order to design high-performance low-speed centrifugal compressor.
1.2 One-dimensional impeller design
1) flow characteristics of the
ibm 08K8197 battery design. Impeller entrance of the smaller radius of curvature-line, and zero angle of attack designed to better meet the fuel-cell low-flow condition. A more narrow leaves and small to meet the low-speed flow of high pressure over there. Due to the low-speed characteristics of the design of an appropriate export widen the width of impeller, the impeller in order to reduce the relative speed, so as to reduce the effect of stratification.
2) No short Vaneless design. Centrifugal compressor diffuser need to exit the impeller to kinetic energy as much as possible into a static pressure can be. The on-board centrifugal compressor, often without the use Vaneless, its internal fluid on the approximate number of mobile curve. For low-speed centrifugal compressor impeller, its exports impeller Department of tangential velocity u high, but the relative wind speed and w leaves along the radial velocity is relatively low, leading to its c is the speed and direction of radial A great angle α, see Figure 2. In the absence of fluid Vaneless section of the week to a long process, a sharp increase in friction losses, but also easy to produce the phenomenon of return. In order to reduce or even avoid such losses, improve the efficiency of the gas pressure,
sony VGP-BPS5 battery use of shorter-free Vaneless.
3) scroll design features. Of air Impeller in exports due to the radial velocity is very small, and little traffic, so the design of low-speed centrifugal compressor uses a smaller diameter spiral case.
1.3 impeller three-dimensional design
Concept of using software modules Axcent three-dimensional modeling. As the long and narrow leaves and a greater curvature, in order to reduce the leaves per unit area on the load increases to take leaves of the packet method Kok, at the same time reduce the face with the blade on the back of the relative speed of poor control of the jet wake of the formation of structure to improve The leaves between the state of flow, to reduce the spread of the
sony PCGA-BP2NY battery loss. Using streaming leaves in order to reduce the flow obstruction. Impeller axial length as short as possible in order to reduce the volume. After the adoption of 40 ° curved design to improve efficiency and broaden the scope of work and stability.
2 flow analysis
Centrifugal compressor impeller three-dimensional flow field simulation software used NUMECA. Reynolds equations for an average of three-dimensional Navier-Stokes equation. Turbulence model used Spalart-Allmaras model. To save computing workload, the impeller along the circumference get 1 / 10, includes a diversion in the middle leaves
dell 75UYF battery , optional nearly 300,000 nodes. The total imports of a given temperature, pressure, velocity, static pressure extrapolation; export to Flow; along a given week to the periodic boundary conditions.
Numerical simulation of the impeller at the speed of 20000r.min-1 (design speed), 18000r.min-1, 16000r.min-1 of the flow curve shown in Figure 3. Can be seen in the design speed, maximum efficiency of the impeller up to 83%, the most high-pressure ratio up to 1.6. The design of centrifugal compressor with a broad and relatively flat operating characteristics(
toshiba PA2487UR battery ,
toshiba PA3107U-1BRS battery ,
toshiba PA3285U-1BRS battery ,
toshiba PA3356U-1BRS battery ,
toshiba PA3384U-1BRS battery ,
toshiba PA3383U-1BRS ), fuel cell car to meet the wide-flow condition.
3 Conclusion
The design of a fuel cell system for on-board low-speed centrifugal compressor, the compressor can be an ordinary high-speed motor-driven, low cost, easy to manufacture, long life and more suitable for low-flow condition.
Numerical simulation show that the design of low-speed centrifugal compressor, in the general design of high-speed motor rated speed 20000r.min-1, the impeller pressure ratio reached 1.6, 83% efficiency,
laptop battery fuel cells to meet the requirements of the compressor.
Thanks to be the work of this paper, high-diesel pressurized Technology Key Laboratory of National Defense Science and Technology Xing Weidong, Zhang Yue, Zhang Jizhong, Hong-researchers, such as the strong support and are gratefu
