Frictonless compressor technology Essay Example

with both permanent magnets and electromagnets. In this frictionless compressor setup (as shown in Figure 1), the only moving part is the compressor shaft, which rotates on a levitated magnetic cushion.

To hold the shaft in place, two radial and one axial magnetic bearings are utilized (as shown in Figure 2). When energized, these magnetic bearings cause the motor and impellers connected to the magnetic shaft to levitate. The primary work is performed by permanent-magnetic bearings while digitally controlled electromagnets ensure precise positioning.

To maintain assembly tolerance at an impressive level of 0.00002 inches, four positioning signals per bearing are used. These signals allow adjustments to be made at an astounding rate of 6 million times per minute as the assembly moves away from its center point.
The software automatically compensates for imbalances in the levitated assembly. The positioning sensors include Y-axis, X-axis, Z-axis, front position ring radial bearing, motor sensor ring, and rear radial axial bearing sensors (see FIGURE 2).

A digitally controlled magnetic-bearing system consists of two radial bearings and touchdown bearings to prevent compressor failure. Capacitors smooth ripples in the motor drive's DC link. During a power failure, the motor acts as a generator and uses its angular momentum to generate electricity (also known as back NEFF) to keep the capacitors charged during coastland.

The capacitors maintain levitation when the compressor is not running during coastland and allow the shaft assembly to rest on graphite-lined touchdown bearings. The compressor's power magnetic bearings ensure proper rotor positioning to avoid contact with metallic surfaces during a normal shutdown. This eliminates extensive oil management in compressor bearings. Only a small amount of oil may be needed for lubricating other system

components or sometimes even none at all.By eliminating the use of oil-management systems, the cost and effort associated with various components such as oil pumps, sumps, heaters, coolers, and separators can be avoided. In many installations, electromagnetic cushions continuously adjust their field strength to keep the rotor shaft centrally positioned. This has resulted in a reduction of tenant costs by more than 50%.

Many air-cooled products like chillers, rooftop units, and condensing units utilize DXL evaporators. These systems allow for oil to flow through the refrigeration circuit and back to the compressor oil sump. It is important to carefully design these systems to ensure proper oil return, especially at partial loads when refrigerant flow may be decreased.

Water-cooled chillers often employ flooded evaporators. However, even small amounts of oil in a flooded evaporator can decrease chiller performance and require an oil-recovery system. Magnetic bearings eliminate the need for such systems and simplify oil management. The compressor only requires regular maintenance such as tightening terminal screws quarterly, cleaning boards annually, and changing capacitors every five years.

The manufacturer offers complete service agreements and extended maintenance contracts for convenience.

Most hermetic compressors use induction motors that are cooled by either liquid or suction-gas refrigerant. These motors have bulky copper windings that generate magnetic fields when alternating current passes through them.These windings increase the size and weight of the compressor. Two-pole, 60Hz induction motors typically operate at around 3,600 RPM, but higher speeds can be achieved by increasing the frequency. Compressors that require higher shaft speeds usually use gears.

While gears are effective, they generate noise and vibration, need lubrication, and consume power. On the other hand, magnet-bearing compressors have a

synchronous permanent-magnet brushes DC motor with an integrated variable-frequency drive (VFD). The traditional induction motors have their stator windings replaced with a permanent-magnet rotor. The armature windings are powered by alternating current from the inverter. By switching the stator (excitation) and rotor (armature), commutate brushes are no longer necessary. Electrical cooling is essential for both the motor and key electronics in the VFD.

By using permanent magnets instead of rotor windings, the motor's size and weight are reduced compared to induction motors. Magnetic-bearing technology allows for a much lighter 75-ton compressor weighing only 265 lb. A variable-speed drive (VS.) is required for the motor to operate effectively, enabling a compressor speed range from 18,000 to 48,000 RPM by adjusting the frequency between 300 and 800 Hz's.This eliminates the need for a gear set.The VS.is integrated into the compressor housing which results in shorter leads and enables refrigerant-cooling of crucial electronic components.In addition,the VSThe text describes a new compressor with a soft starter, resulting in a low startup in-rush current. The integration of the motor, VS., and magnetic-bearing system allows the capacitors to serve as a backup power source for the bearings during power outages or emergency shutdowns. This technology is being implemented in .NET projects to improve efficiency for both water-cooled and air-cooled duties with varying capacities. Capacity and efficiency are important factors influencing performance, with plans to extend the compressor's capacity range by 2004. The new compressor functions like a computer, providing diagnostic and performance information through Modus. This information can be communicated to the building automation system via Modus, Loanwords, or Backed. Collaborations between the compressor manufacturer and a chiller manufacturer have resulted in

AIR-certified water-cooled chillers expected to be released in January 2004.The combination of flooded-evaporator technology and an oil-free system enables close approaches and improved performance. The integrated BFD (backflow damper) aids in achieving excellent part-load performance with reduced power consumption, depending on the head relief, which decreases proportionally with the cube root of the shaft speed. The compressor features water-cooled wheels in a dual-compressor format, enhancing its performance at less than full capacity. It has been tested according to AIR standard 550/590-98 for water chilling packages utilizing the vapor compression cycle. A chiller with a nominal capacity of 150 tons exhibits an upload performance of 0.29 K per ton (5.6 COP) and a Pill value (Performance Index based on Load & Part-load Conditions) of 0.375 K per ton (9.4 COP). All Pills are weighted to consider standard operating conditions and time spent at those conditions. Figure 3 presents specific operating points for a chiller with a nominal capacity of 150 tons.Magnetic-bearing compressors offer economic, energy, and environmental advantages like increased energy efficiency, elimination of oil, and reduced noise and vibration levels.In terms of efficiency within the compressor itself,isentropic efficiency(the efficiency of the wheels),the motor,and bearings play crucial roles.Traditional induction motors in this size range typically have around 92 percent efficiency.However,this compressor utilizes permanent-magnet motor technology with an efficiency ranging from96 to97 percentThe use of magnetic bearings, as opposed to traditional oiled bearings, enhances efficiency by reducing friction between moving parts. Whereas conventional bearings can consume up to 10,000 watts, magnetic bearings only need 180 watts, resulting in a remarkable decrease in friction losses – about 500 times less. Furthermore, there is currently no presence of structure-borne

vibration.