Editing Compressor (section)

===Dynamic===
====Air bubble compressor====
Also known as a [[trompe]]. A mixture of air and water generated through turbulence is allowed to fall into a subterranean chamber where the air separates from the water. The weight of falling water compresses the air in the top of the chamber. A submerged outlet from the chamber allows water to flow to the surface at a lower height than the intake. An outlet in the roof of the chamber supplies the compressed air to the surface. A facility on this principle was built on the [[Montreal River (Timiskaming District)|Montreal River]] at Ragged Shutes near [[Cobalt, Ontario]] in 1910 and supplied 5,000 horsepower to nearby mines.<ref>{{cite journal|last=Maynard|first=Frank|date=November 1910|title=Five thousand horsepower from air bubbles|journal=Popular Mechanics|page=633|url=https://books.google.com/books?id=-N0DAAAAMBAJ|url-status=live|archive-url=https://web.archive.org/web/20170326071901/https://books.google.com/books?id=-N0DAAAAMBAJ&printsec=frontcover|archive-date=2017-03-26}}</ref>

====Centrifugal compressors====
[[File:CentrifugalCompressor.jpg|thumb|right|A single stage centrifugal compressor]]
[[File:Fan, before 1945.jpg|thumb|right|A single stage centrifugal compressor, early 1900s, G. Schiele & Co., Frankfurt am Main]]
{{main|Centrifugal compressor}}
'''Centrifugal compressors''' use a rotating disk or [[impeller]] in a shaped housing to force the gas to the rim of the impeller, increasing the velocity of the gas. A diffuser (divergent duct) section converts the velocity energy to pressure energy. They are primarily used for continuous, stationary service in industries such as [[oil refinery|oil refineries]], [[chemical plant|chemical]] and [[petrochemical]] plants and [[natural gas processing]] plants.<ref name=Perry >{{cite book
  |editor1=Perry, R.H. 
  |editor2=Green, D.W. 
  |title=[[Perry's Chemical Engineers' Handbook]]
  |edition=8th|publisher=McGraw Hill
  |year=2007
  |isbn=978-0-07-142294-9
}}</ref><ref>{{cite book|author=Dixon S.L.
  |title=Fluid Mechanics, Thermodynamics of Turbomachinery
  |edition=Third
  |publisher=Pergamon Press
  |year=1978|isbn=0-08-022722-8
}}</ref><ref>{{cite book
  |author=Aungier, Ronald H.
  |title=Centrifugal Compressors A Strategy for Aerodynamic design and Analysis
  |publisher=[[ASME]] Press
  |year=2000
  |isbn=0-7918-0093-8
}}</ref> Their application can be from {{convert|100|hp|kW}} to thousands of horsepower. With multiple staging, they can achieve high output pressures greater than {{convert|1000|psi|MPa|abbr=on}}.

This type of compressor, along with screw compressors, are extensively used in large refrigeration and air conditioning systems. Magnetic bearing (magnetically levitated) and air bearing centrifugal compressors exist.

Many large [[snowmaking]] operations (like [[ski resorts]]) use this type of compressor. They are also used in internal combustion engines as [[supercharger]]s and [[turbocharger]]s. Centrifugal compressors are used in small [[gas turbine]] [[engine]]s or as the final compression stage of medium-sized gas turbines.

Centrifugal compressors are the largest available compressors, offer higher efficiencies under partial loads, may be oil-free when using air or magnetic bearings which increases the heat transfer coefficient in evaporators and condensers, weigh up to 90% less and occupy 50% less space than reciprocating compressors, are reliable and cost less to maintain since less components are exposed to wear, and only generate minimal vibration. But, their initial cost is higher, require highly precise [[CNC]] machining, the impeller needs to rotate at high speeds making small compressors impractical, and surging becomes more likely.<ref name=autogenerated1 /> Surging is gas flow reversal, meaning that the gas goes from the discharge to the suction side, which can cause serious damage, specially in the compressor bearings and its drive shaft. It is caused by a pressure on the discharge side that is higher than the output pressure of the compressor. This can cause gases to flow back and forth between the compressor and whatever is connected to its discharge line, causing oscillations.<ref name="autogenerated1"/>

====Diagonal or mixed-flow compressors====
'''Diagonal''' or '''[[mixed-flow compressor]]s''' are similar to centrifugal compressors, but have a radial and axial velocity component at the exit from the rotor. The diffuser is often used to turn diagonal flow to an axial rather than radial direction.<ref>{{Cite book|url=https://books.google.com/books?id=WQcEDAAAQBAJ&q=diffuser+turns+diagonal+flow+to+axial+flow&pg=PT251|title=Pollution Control Handbook for Oil and Gas Engineering|last=Cheremisinoff|first=Nicholas P.|date=2016-04-20|publisher=John Wiley & Sons|isbn=9781119117889|language=en|url-status=live|archive-url=https://web.archive.org/web/20171224222642/https://books.google.com/books?id=WQcEDAAAQBAJ&pg=PT251&lpg=PT251&dq=diffuser+turns+diagonal+flow+to+axial+flow&source=bl&ots=rkZptfuirh&sig=RgvJpyW13dPTS677R4UWIOCaQtU&hl=en&sa=X&ved=0ahUKEwjbvIKZ9NnVAhXD6YMKHWfvCuwQ6AEINzAG#v=onepage&q=diffuser%20turns%20diagonal%20flo&f=false|archive-date=2017-12-24}}</ref> Comparative to the conventional centrifugal compressor (of the same stage pressure ratio), the value of the speed of the mixed flow compressor is 1.5 times larger.<ref>{{cite web|url=http://turbolab.tamu.edu/proc/turboproc/T13/T13139-147.pdf|title=Development of High Specific Speed Mixed Flow Compressors|last=Kano|first=Fumikata|website=Texas A&M University|archive-url=https://web.archive.org/web/20140811093700/http://turbolab.tamu.edu/proc/turboproc/T13/T13139%2D147.pdf|archive-date=2014-08-11|url-status=dead|access-date=2017-08-16}}</ref>

====Axial compressors====
[[File:Axial compressor.gif|thumb|right|An animation of an axial compressor.]]
{{main|Axial compressor}}
'''Axial compressors''' are dynamic rotating compressors that use arrays of fan-like [[airfoil]]s to progressively compress a fluid. They are used where high flow rates or a compact design are required.

The arrays of airfoils are set in rows, usually as pairs: one rotating and one stationary. The rotating airfoils, also known as blades or ''rotors'', accelerate the fluid. The stationary airfoils, also known as ''stators'' or vanes, decelerate and redirect the flow direction of the fluid, preparing it for the rotor blades of the next stage.<ref name=Perry /> Axial compressors are almost always multi-staged, with the cross-sectional area of the gas passage diminishing along the compressor to maintain an optimum axial [[Mach number]]. Beyond about 5 stages or a 4:1 design pressure ratio a compressor will not function unless fitted with features such as stationary vanes with variable angles (known as variable inlet guide vanes and variable stators), the ability to allow some air to escape part-way along the compressor (known as interstage bleed) and being split into more than one rotating assembly (known as twin spools, for example).

Axial compressors can have high efficiencies; around 90% [[polytropic]] at their design conditions. However, they are relatively expensive, requiring a large number of components, tight tolerances and high quality materials. Axial compressors are used in medium to large [[gas turbine]] engines, natural gas pumping stations, and some chemical plants.