A multi-type air conditioning device controls an evaporation temperature and a condensing temperature, depending on required capacity of an indoor unit. The air conditioning device compares a current evaporation temperature or condensing temperature with a reference value, of an evaporation temperature or an condensing temperature, corresponding to a lower limit flow rate, of a gaseous refrigerant, required for refrigerating machine oil not to accumulate in, but to flow through, the gas branch pipes, and calculates an amount of the refrigerating machine oil accumulated in a gas branch pipe which does not satisfy the lower limit flow rate. When the calculated amount exceeds a set amount, the air conditioning device performs oil collecting operation, and controls the oil collecting operation in view of a flow rate of a gaseous refrigerant in gas branch pipes.

A refrigeration apparatus, including a main circuit (1) for circulation of a main flow (90) of refrigerant, and a lubrication branch (20), comprising a lubrication inlet (21), configured to derive a lubrication flow (91) from the main flow (90) circulating through a supply part (16) of the main circuit; and a lubrication outlet (22), to feed the compressor (2) with the lubrication flow (91) for lubrication. According to the invention, the refrigeration apparatus further includes: a subcooling branch (40), comprising a subcooling inlet (41), connected to an evaporator (8) of the main circuit (1), so as to derive a subcooling flow (92), and a subcooling outlet (42), connected to the evaporator (8), for reintroducing the subcooling flow (92) into the main flow (90); and a subcooling heat exchanger (31).

A refrigerating machine oil containing: a lubricating base oil; and a compound represented by the following formula (1): ##STR00001## wherein R.sup.1 and R.sup.2 each independently represent a monovalent hydrocarbon group, R.sup.3 represents a divalent hydrocarbon group, and R.sup.4 represents hydrogen atom or a monovalent hydrocarbon group, and the refrigerating machine oil having a kinematic viscosity at 100° C. of 0.5 mm.sup.2/s or more and 2.5 mm.sup.2/s or less.

A heating, ventilation, air conditioning, and refrigeration (HVACR) system includes a compressor with a gas bearing supplied with compressed gas and a controller. The controller is configured to determine an inlet pressure and outlet pressure of the gas bearing, determine a maximum speed limit based on the inlet pressure and the outlet pressure, and prevent the compressor from operating at a speed that is greater than the maximum speed limit. A method of controlling a compressor includes calculating a maximum speed limit based on an inlet pressure and an outlet pressure of the gas bearing. The method also includes in response to determining that a speed setting is greater than the maximum speed limit, adjusting operation of the compressor such that a speed of the compressor is at or below the maximum speed limit.

A lubricant supply system is for a compressor that compresses a first working fluid in a heat transfer circuit. The lubricant supply system includes a lubricant tank, a lubricant pathway for supplying lubricant from the lubricant tank to one or more bearings of the compressor, and a lubricant refrigeration system with a lubricant heater and a lubricant cooler. The lubricant heater configured to heat the lubricant discharged from the one or more bearings and the lubricant cooler configured to cool the lubricant flowing through the lubricant pathway. A method of lubricating a compressor includes heating the lubricant, directing the lubricant from a lubricant tank through a lubricant pathway to one or more bearings of the compressor, and cooling the lubricant passing through the lubricant pathway.

A refrigeration system is provided and includes a common suction line, a common discharge line, first and second high-side compressors disposed in parallel to receive low-pressure refrigerant from the common suction line and to direct high-pressure refrigerant to the common discharge line, a first pipe connected to the first and second high-side compressors at vertical heights at which an oil supply is required to remain higher and a second pipe connected to the first and second high-side compressors at vertical heights sufficient to maintain gas pressure balance between the first and second high-side compressors.

A refrigerant compressor for a refrigeration system comprises a common housing, a compressor unit arranged in the common housing, a mechanical compressor drive unit for the compressor unit, arranged in a drive chamber, a lubricant bath forming in the drive chamber, an intake duct that extends in a manner separated from the drive chamber and through which the compressor unit draws in by suction refrigerant that is to be compressed. The intake duct and the drive chamber are connected by a gas equaliser duct, which allows a permanent equalisation of gas, and which has on one side an opening on the drive chamber side and on the other an opening on the intake side, and of which the duct length between the openings corresponds to at least twice an equivalent duct diameter, in particular a smallest equivalent duct diameter, of the gas equaliser duct.

A refrigeration cycle apparatus (1) is capable of performing a refrigeration cycle using a small-GWP refrigerant. The refrigeration cycle apparatus (1) includes a refrigerant circuit (10) and a refrigerant enclosed in the refrigerant circuit (10). The refrigerant circuit includes a compressor (21), a condenser (23), a decompressing section (24), and an evaporator (31). The refrigerant contains at least 1,2-difluoroethylene.

Compositions, systems, and methods for introducing lubricants, and additives, that are designed to work with environmentally friendly refrigerants into vehicle heat management systems including passenger compartment air conditioning (A/C) systems are disclosed. Methods for charging lubricants and specific additives using environmentally desirable (low GWP) refrigerant or refrigerant blend compositions into an environmentally friendly system, such as a system that uses HFO-1234yf, are also disclosed.

It is an object of the present invention to provide a fluid stirring and liquefaction promoting apparatus which enables uniform mixture of refrigerator oil with refrigerant, thereby improving the heat exchange efficiency of heat pump systems and reducing the energy consumption.

There is provided a liquefaction promoting apparatus to be disposed on a pipeline of a heat pump system for the purpose of stirring and uniformly mixing the fluid containing refrigerant and refrigerator oil circulating therein. The apparatus comprises a cylindrical casing, one or more channelizing units each composed of a pair of large-diameter disks on its outer side and a pair of small-diameter disks on its inner side disposed in axial alignment inside the cylindrical casing. Each of the large-diameter disks is on its inner surface with a honeycomb panel having polygonal cells and each of the small-diameter disks is formed on its outer surface with a honeycomb panel having polygonal cells such that the honeycomb panels of the large-diameter disks and of the small-diameter disks are arranged to face each other and each polygonal cell communicates with more than one opposing polygonal cells. The fluid containing refrigerant and refrigerator oil is circulated in the heat pump system with a pressure of 0.2 to 10 MPa.