China 
Africa 
Explore chapters and articles related to this topic
Compressors and Pumps
Published in Leslie R. Rudnick, Synthetics, Mineral Oils, and Bio-Based Lubricants, 2020
The term “screw compressor” most often references the double-helical, also called twin-screw, compressor. This type of compressor is used in a wide variety of applications including air, refrigeration, hydrocarbon, and chemical processes. Another type of screw compressor is the single screw, which was originally used for air applications but later found success in refrigeration applications as an alternative to piston and sliding-vane compressors [1].
Compressor Lubrication
Published in W. S. Robertson, Lubrication in Practice, 2019
Screw compressors are manufactured in an oil-free and oil-injected form. The single-stage oil-injected type of screw compressor is the most important for compressing air and many are used in portable applications. Oil flooding permits the rotors to run together, has a cooling and sealing effect and eliminates metal-to-metal contact. The oil used is recirculated and an efficient separator keeps the oil content of the discharge air to about 30/35 ppm.
Multi-objective optimization of the centrifugal compressor impeller in 130 kW PEMFC through coupling SVM with NSGA -III algorithms
Published in International Journal of Green Energy, 2021
Chongbin Ma, Zirong Yang, Kui Jiao, Zhi Liu, Qing Du
According the operation mode, the air compressors applied to the air supply system of PEMFC can be classified as positive displacement compressors and aerodynamic compressors. The former compresses air by displacement of a mechanical linkage, which includes screw compressor (Wang et al. 2020a), scroll compressor (Qin et al. 2017), piston compressor (Deng et al. 2019), and roots compressor. Screw compressors have two interlocking helical rotors contained in a housing, but their applications are limited by their large volume. Scroll compressors have two main components, including the stationary scroll and moving scroll. However, scroll compressors suffer from the shortage of small pressure ratio. Piston compressors are reciprocating-type positive-displacement devices, which use pistons driven by a crankshaft for air compression. But the utilization of oil-lubrication in piston compressors will pollute fuel cells. Roots compressors are rotary-type positive-displacement devices. It works through a pair of meshing lobes with a set of stretched gears, but roots compressor has high rotational inertia. Comparing with the above compressors, the centrifugal compressor is a typical aerodynamic compressor, and contains four components: inlet, impeller, diffuser, and collector. It achieves the pressure increment by adding kinetic energy to continuum fluid through the impeller. The kinetic energy is subsequently converted to potential energy through the diffuser. Centrifugal compressor can perform better than other compressors in the aspects of high input power, high system efficiency, low weight, and low volume. Meanwhile, centrifugal compressors are also considered as the most promising, making it the focus of recent reported papers (Junbo et al. 2020).