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 device is provided comprising an expansion machine for generating mechanical energy by expanding vapor of a working medium; a generator connected to a shaft of the expansion machine and used for generating electric energy from mechanical energy of the expansion machine; wherein the expansion machine and the generator form a structural unit with an exhaust vapor chamber between the expansion machine and the generator, and wherein, when the expansion machine is in operation, working medium expanded into the exhaust vapor chamber contacts the generator; and means for feeding, in particular injecting, a liquid working medium into the exhaust vapor chamber. Also provided is an ORC device comprising the device and a method for operating the device.

Disclosed is a cooling system comprising a refrigerant cycle for cycling refrigerant from at least a compressor unit for com-pressing gaseous refrigerant to a condenser unit for condensing gaseous refrigerant to liquid refrigerant, from the condenser unit to an evaporator unit for evaporating the liquid refrigerant to gaseous refrigerant, and from the evaporating unit back to the compressor unit, and a lubrication cycle having at least one lubricating refrigerant supply line for providing refrigerant as lubricant to a bearing assembly, wherein the at least one lubricating refrigerant supply line branches off from the refrigerant cycle at the condenser unit for providing refrigerant to the bearing assembly, and re-unites with the refrigerant cycle at the evaporator unit, for feeding back refrigerant from the bearing assembly to the refrigerant cycle.

In a refrigeration cycle apparatus, refrigerant circulates successively through a compressor, a condenser, an expansion valve, and an evaporator. The refrigeration cycle apparatus includes a detection unit, a heating unit, and a controller. The detection unit is configured to detect a temperature of refrigeration oil in the compressor. The heating unit is configured to heat the refrigeration oil. The controller is configured to operate the heating unit when the temperature detected by the detection unit is lower than a pour point of the refrigeration oil, and to stop the heating by the heating unit when the temperature detected by the detection unit reaches the pour point. Preferably, the heating unit includes a heater provided on an outer side of a compressor casing and at a lower portion of a motor unit.

In a refrigeration and air-conditioning apparatus, an inner diameter of an upward-flow pipe is defined as an inner pipe diameter, where a spherical droplet of refrigerating machine oil with a diameter equal to the inner pipe diameter is defined as a spherical refrigerating machine oil droplet, and where a force received by the spherical refrigerating machine oil droplet from refrigerant in liquid form flowing upward through the upward-flow pipe is defined as a fluid force, the refrigerant in liquid form flows upward through the upward-flow pipe at such a speed that the fluid force is greater than a gravitational force applied to the spherical refrigerating machine oil droplet.

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 compressor return air dryness detection method includes: obtaining an exhaust air pressure, a return air pressure, a working frequency, an exhaust air temperature, and a return air temperature of a compressor; determining a return air saturation temperature corresponding to the return air pressure; calculating a temperature difference value based on the return air temperature and the return air saturation temperature; and in accordance with a determination that the temperature difference value is smaller than a predetermined threshold value, calculating a return air dryness of the compressor based on the exhaust air pressure, the return air pressure, the working frequency, and the exhaust air temperature.

A fresh-air air conditioning system comprises: a first electromagnetic valve connected to a first interior heat exchanger, and the first electromagnetic valve is connected via a first accumulator to a compressor and a third electromagnetic valve; the third electromagnetic valve is connected via a second accumulator to the compressor and a second electromagnetic valve; and the second electromagnetic valve is connected to a second interior heat exchanger. When the first interior heat exchanger or the second interior heat exchanger is closed, the third electromagnetic valve opens so that the first accumulator and the second accumulator simultaneously communicate with the open one of the first interior heat exchanger or the second interior heat exchanger, avoiding poor oil return as a result of prolonged single-cylinder operation of the compressor, and ensuring the reliability of the compressor as well as interior comfort.

A compressor arrangement includes two or more compressors (16a, 16b) arranged in a fluidly parallel configuration and a lubricant sump (38) containing a volume of lubricant operably connected to the two or more compressors. A lubricant sump pressure (P) is greater than a lubricant cavity pressure of each compressor (Pa, Pb, Pc) of the two or more compressors at all operating conditions of the two or more compressors. An equilibrium lubricant line (40) connects the lubricant sump to the two or more compressors to convey lubricant from the lubricant sump to a lubricant cavity (42) of each compressor of the two or more compressors.

A method includes receiving, by a processing device and from a variable frequency drive coupled to one or more compressors, operation information of the one or more compressors. The method also includes comparing the operation information of the one or more compressors to an operation threshold and determining that the operation information satisfies the operation threshold. The method also includes changing, based on the determination that the operation information of the one or more compressors satisfies the operation threshold, an operation parameter of a component of the refrigeration system. Changing the operation parameter increases at least one of: (i) a velocity of a working fluid in a piping assembly fluidly coupled to the one or more compressors, or (ii) a flow rate of an oil in the piping assembly flowing into the one or more compressors.