A method of mitigating liquid-refrigerant migration includes comparing a requested compressor speed of a variable-speed compressor to a pre-defined threshold and, responsive to a determination that the requested compressor speed is greater than the pre-defined threshold, operating the variable-speed compressor at a first compressor speed that is less than the requested compressor speed.

A cooling system uses P-traps to address the oil return issues that result from a vertical separation between the compressor and the high side heat exchanger. Generally, the vertical piping that carries the refrigerant from the compressor to the high side heat exchanger includes P-traps installed at various heights to capture oil in the refrigerant and to prevent that oil from flowing back to the compressor. As oil collects in the P-traps, the refrigerant begins to push the oil upwards until the oil reaches the high side heat exchanger. Multiple piping of different sizes may be used depending on a discharge pressure of the compressor. When the discharge pressure is higher, a larger piping may be used direct the oil and refrigerant to the high side heat exchanger.

A HVAC system refrigeration circuit is configured to balance the oil carryover between multiple compressors using a single refrigeration circuit. Embodiments of the HVAC system allow for the use of one or more inverter compressors and one or more fixed speed compressors. Embodiments of the HVAC system utilize capillary tubes or other flow control methods to balance the oil carryover between multiple compressors.

A refrigerant replacement method for a refrigeration apparatus is intended to replace a first refrigerant charged into a refrigerant circuit of the refrigeration apparatus with a second refrigerant. The second refrigerant is used together with a refrigerating machine oil having a higher additive content by percentage than another refrigerating machine oil to be used together with the first refrigerant. The method includes: a refrigerant recovery step of recovering the first refrigerant from the refrigerant circuit; an oil charging step of additionally charging a refrigerating machine oil having a predetermined additive content by percentage into the refrigerant circuit; and a refrigerant charging step of charging the second refrigerant into the refrigerant circuit. The predetermined additive content by percentage is higher than the additive content by percentage of the refrigerating machine oil to be used together with the second refrigerant.

A porous gas bearing is disclosed. The porous gas bearing includes a housing having a fluid inlet and an aperture. A porous surface layer is disposed within the housing surrounding the aperture in a circumferential direction. The porous surface layer is in fluid communication with the fluid inlet. A damping system includes a damping system including a biasing member, the biasing member being disposed in a passageway that extends along the longitudinal direction of the aperture and circumferentially about the aperture, wherein the biasing member is arranged radially outward from the porous surface layer.

Provided is grease capable of suppressing a decrease in a function as a lubricant even when used in a device installed in a refrigerant circuit in which a refrigerant containing a chlorine atom and an olefin bond in a molecule flows, and a refrigeration cycle apparatus using the grease as a lubricant. Grease that is used in a device installed in a refrigerant circuit in which a refrigerant containing a chlorine atom and an olefin bond in a molecule flows contains fluorine as a component. In a chiller apparatus, the grease is used as a lubricant for at least one of a first radial touchdown bearing and a second radial touchdown bearing of a compressor, a drive portion of an inlet guide vane of the compressor, and a drive portion of an expansion valve.

A compressor including a housing, a shaft configured to be rotated relative to the housing to compress a refrigerant, a motor configured to drive the shaft, a lubrication system configured to supply lubricant to the compressor, and a bearing configured to support the shaft. The shaft includes a wear-resistant sleeve-like treatment on at least a portion of an outer surface of the shaft adjacent the bearing. The lubricant is POE oil or a lubricant blend composition that includes two or more lubricants, the two or more lubricants including a first lubricant and a second lubricant.

A cooling system and methods of employing the same includes a refrigerant cycle for cycling refrigerant from a compressor to a condenser and from the condenser an evaporator unit, and a lubrication cycle having at least one lubricating refrigerant supply line for providing refrigerant as lubricant to a bearing assembly.

An oil separator has a filter portion in a differential pressure generation mechanism configured to collect, by a differential pressure, lubricating oil that is in a form of mist included in high-pressure refrigerant that flows in a first pipe that is connected to a discharge port of a compressor and allows the collected lubricating oil to move downstream along an internal wall of the first pipe.

This refrigeration apparatus (1) comprises a main refrigerant circuit (2) including a positive displacement compressor (4), a condenser (6), an expansion valve (8), an evaporator (10), through which a refrigerant circulates successively in a closed loop circulation, and a lubrication refrigerant line (18) in fluid connection with the main refrigerant circuit (2) and connected to the compressor (4) for lubrication of said compressor (4) with the refrigerant. The refrigeration apparatus (1) comprises a refrigerant container (20) connected between the condenser (6) and the expansion valve (8), said refrigerant container (20) being configured to retain a quantity of refrigerant, the lubrication refrigerant line (18) being connected to said refrigerant container (20). The refrigeration apparatus (1) further comprises heating means (28) for heating the refrigerant contained in the refrigerant container (20).