Linear compressor
{{Short description|Gas compressor where the piston is driven by a linear actuator}}
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A linear compressor is a gas compressor where the piston moves along a linear track to minimize friction and reduce energy loss during conversion of motion. This technology has been successfully used in cryogenic applications which must be oil-less. The suspension spring can be flexure type or coil type. An oil-free valved linear compressor enables the design of compact heat exchangers.{{cite journal |doi=10.1016/j.ijrefrig.2017.08.015 |title=A review of linear compressors for refrigeration |journal=International Journal of Refrigeration |volume=84 |pages=253–273 |year=2017 |last1=Liang |first1=Kun |url=http://sro.sussex.ac.uk/id/eprint/69918/1/Linear%20Compressor%20Review%20Accepted%20Version.pdf }} Linear compressors work similarly to a solenoid: by using a spring-loaded piston with an electromagnet connected to AC through a diode. The spring-loaded piston is the only moving part, and it is placed in the center of the electromagnet. During the positive cycle of the AC, the diode allows energy to pass through the electromagnet, generating a magnetic field that moves the piston backwards, compressing the spring, and generating suction. During the negative cycle of the AC, the diode blocks current flow to the electromagnet, letting the spring uncompress, moving the piston forward, and compressing the refrigerant. The compressed refrigerant is then released by a valve.
History
A number of patents for linear compressors powered by free-piston engines were issued in the 20th century, including:
- To Brown, Boveri & Cie, GB191215963, published 1913-10-08{{cite web|url=http://worldwide.espacenet.com/publicationDetails/originalDocument?CC=GB&NR=191215963A&KC=A&FT=D&ND=3&date=19131008&DB=EPODOC&locale=en_EP|title=Espacenet : Original document|website=Worldwide.espacenet.com|accessdate=5 November 2017}}
- To Hugo Junkers, CA245708, published 1924-12-30
- To Raúl Pateras Pescara, US1615133, published 1927-01-18
The first market introduction of a linear compressor to compress refrigerant in a refrigerator was in 2001.{{cite web|url=http://www.ohio.edu/mechanical/thermo/Intro/Chapt.1_6/refrigerator/refrig_problems.html|title=Problems 4.7 - A Home Refrigerator (updated 3/15/13)|website=Ohio.edu|accessdate=5 November 2017}}
Valved linear compressor
The single piston linear compressor uses dynamic counterbalancing, where an auxiliary movable mass is flexibly attached to a movable piston assembly and to the stationary compressor casing using auxiliary mechanical springs with zero vibration export at minimum electrical power and current consumed by the motor.{{cite journal |doi=10.1016/j.cryogenics.2005.03.007 |title=Development of a valved linear compressor for a satellite borne J–T cryocooler |journal=Cryogenics |volume=45 |issue=7 |pages=496–500 |year=2005 |last1=Reed |first1=Jaime |last2=Dadd |first2=Mike |last3=Bailey |first3=Paul |last4=Petach |first4=Michael |last5=Raab |first5=Jeff |bibcode=2005Cryo...45..496R }} It is used in cryogenics. Linear compressors are used as they have fewer mechanical losses.{{cite web | url=https://patents.google.com/patent/US8496453B2/en | title=Linear compressor }}
Linear compressors are made by LG and used in LG and Kenmore refrigerators. Linear compressors were also announced by Embraco.{{cite web |date=2014-03-20 |title=Oil-less linear compressor launched |url=https://www.coolingpost.com/world-news/oil-less-linear-compressor-launched/ |access-date=2024-02-28 |website=Cooling Post}}{{cite web | url=https://www.acr-news.com/embraco-claims-oil-less-compressor-breakthrough | title=Embraco claims oil-less compressor breakthrough }} Compressors of this type have less noise, and are more energy efficient than conventional refrigerator compressors. The Embraco linear compressors are also claimed to be oil-free. In the 2010s and 2020s, multiple lawsuits in the United States alleged that the LG compressors had a high rate of failure or lack of expected cooling. As of 2024, there were settlements{{Cite web |last=Wroclawski |first=Daniel |date=2020-09-17 |title=LG Settles Class-Action Lawsuit Over Refrigerator Compressors |url=https://www.consumerreports.org/lawsuits-settlements/lg-settles-class-action-lawsuit-over-refrigerator-compressors/ |access-date=2024-02-28 |website=Consumer Reports}} and ongoing cases.{{Cite web |last=Roher |first=Christine |last2=Johnson |first2=Carolyn |date=2023-12-19 |title=People say pricey refrigerator compressors are conking out within a few years, sometimes just months |url=https://www.nbclosangeles.com/investigations/lg-refrigerator-compressor-lawsuit-appliances/3293828/ |access-date=2024-02-28 |website=NBC Los Angeles |language=en-US}}
See also
- {{annotated link|Booster pump}}
- {{annotated link|Hydrogen compressor}}
- {{annotated link|Liquid hydrogen}}
- {{annotated link|Timeline of low-temperature technology}}
- {{annotated link|Timeline of hydrogen technologies}}
- Scroll compressor
References
{{Reflist}}
External links
- {{Cite web|last=Blain|first=Loz|date=2021-11-03|title=Super-efficient linear compressor could vastly reduce air con power use|url=https://newatlas.com/energy/magtor-efficient-compressor-energy-efficient/|access-date=2021-11-04|website=New Atlas|language=en-US}}
{{HVAC}}