Tandem compressors with economized operation

Abstract

A refrigerant cycle includes economized tandem compressors. The refrigerant cycle is also provided with a common economizer circuit for all tandem compressors. Common manifolds communicate discharge, suction and economizer return flows within the refrigerant cycle to each of the tandem compressors. Also, an optional unloader function is provided for each of the compressors. Various arrangements allow enhanced operation control, improved system reliability and reduced equipment life-cycle cost.

Description

BACKGROUND OF THE INVENTION [0001] This invention relates to a refrigerant cycle having tandem compressors, wherein the tandem compressors are each provided with an economizer port and can operate within an economizer cycle. [0002] Tandem compressor refrigerant cycles are known, and have two or more compressors compressing refrigerant and delivering it to a common discharge manifold. Similarly, these compressors are drawing refrigerant from a common suction manifold. In some arrangements, oil equalization lines connecting oil sumps of tandem compressors for oil management, and suction pressure equalization lines connecting shells of the tandem compressors are employed. The tandem compressors provide flexibility to a refrigerant cycle designer, such as allowing additional levels of capacity control by turning off some of the compressors. Moreover, in some applications that would otherwise require a very large single compressor, the tandem compressors provide design options, availabil...

AI Technical Summary

Benefits of technology

[0005] In an alternative embodiment, it may be that only one of the two economizer return lines is provided with a shutoff valve, and a main economizer shutoff valve is placed on the common economizer manifold. In this embodiment, one of the two tandem compressors is selected to be initially moved out of economizer operation in a preferential manner. This would be the compressor with the shutoff valve on its individual economizer return line. In a lower cost alternative, only the economizer manifold includes the shutoff valve.

[0006] Further, in a lower cost embodiment, a single unloader valve may communicate each of the economizer lines back to suction or pressure equalization line. By connecting the unloader line to the economizer line, refrigerant can be effectively tapped from the intermediate compression chambers back to suction when the economizer shutoff valves are closed.

Problems solved by technology

Although economizer circuits provide additional benefits to a refrigerant cycle as described above, they have not been incorporated into refrigerant cycles having tandem compressors.

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