Frictionless compressor in refrigeration

Abstract:-

A new compressor technology introduced in international Air-Conditioning, Heating, Refrigerating, Exposition (AHR  Expo).This technology is designed and optimized take full advantage of magnetic bearing technology,the compressor was awarded the first AHR  Expo innovation award in energy category.traditional centrifugal compressors use roller bearings and hydrodynamic bearings,both of which consume power and require oil and a lubrication system.By using this system we can prevent the lubrication of the bearings and the maintenance cost and pollution decreases.

Main components of refrigeration:-

¢ Compressor 

¢ Condenser

¢ Expander

¢ Evaporator

What is frictionless compressor?

¢ The frictionless compressor technology  is the compressor with which the application of the magnetic bearings & permanent magnet synchronous motor.

¢ In the frictionless compressor instead of the roller bearings & hydrodynamic bearings, magnetic bearings will be use.

Frictionless compressor technology

Magnetic bearing technology is significantly different. A digitally controlled magnetic-bearing system, consisting of both permanent magnets and electro-magnets, replaces conventional lubricated bearings .

Working

¢ When the magnetic bearings are energized, the motor and impellers, which are keyed directly to the magnetic shaft, levitate(Floating).

¢ Permanent-magnetic bearings do the primary work, while digitally controlled electromagnets provide the fine positioning.

As the levitated assembly moves from the center point, the electromagnets’ intensity is adjusted to correct the position

SHUTDOWNS AND POWER FAILURES

¢ When the compressor is not running, the shaft assembly rests on graphite-lined, radially located touchdown bearings.

¢ The magnetic bearings normally position the rotor in the proper location, preventing contact between the rotor and other metallic surfaces.

¢ If the magnetic bearings fail, the touchdown bearings (also known as backup bearings) are used to prevent a compressor failure.

¢ The compressor uses capacitors to smooth ripples in the DC  link in the motor  drive.

¢ Instantaneously  after a power failure, the motor becomes a “generator,” using its angular momentum to create electricity (sometimes known as back EMF) and keeping the capacitors charged during the brief coastdown period.

Advantages

¢ COP of system increases

¢ Lubrication is not required

¢ Avoiding oil-management systems means avoiding the capital cost of oil pumps, sumps, heaters, coolers, and oil separators, as well as the labor and time required to perform oil- related services.

¢ Maintenance costs have been cut by more than 50%

Disadvantages

¢ cleaning of electronic boards .

¢  changing of capacitors every 5 years

conclusion

¢ Now I conclude that a conventional bearing will take 10000W of power then a magnetic bearing will take only 180W of power

¢ This amounts up to 500times less friction loss

¢ So we can increase the use of magnetic bearings instead of conventional bearings  

References

¢ HPAC Engineering article.