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 cooling system drains oil from low side heat exchangers to vessels and then uses compressed refrigerant to push the oil in the vessels back towards a compressor. Generally, the cooling system operates in three different modes of operation: a normal mode, an oil drain mode, and an oil return mode. During the normal mode, a primary refrigerant is cycled to cool one or more secondary refrigerants. As the primary refrigerant is cycled, oil from a compressor may mix with the primary refrigerant and become stuck in a low side heat exchanger. During the oil drain mode, the oil in the low side heat exchanger is allowed to drain into a vessel. During the oil return mode, compressed refrigerant is directed to the vessel to push the oil in the vessel back towards a compressor.

An oil return control method for a multi-split air conditioner and a system accomplishing the same includes: calculating an average exhaust pressure within an oil return period Pd_AVG; determining whether the average exhaust pressure Pd_AVG≥the set threshold Pd.sub.threshold; if Pd_AVG≥Pd.sub.threshold, maintaining the multi-split air conditioner working in heating mode to ensure an acceptable oil return performance without affecting the air conditioning effect of indoor unit in heating mode; if Pd_AVG<Pd.sub.threshold, switching the multi-split air conditioner to cooling mode, stopping a fan within those power-on indoor units and entering into a cooling oil return process and switching the multi-split air conditioner back to heating mode until the cooling oil return process ends.

A refrigeration system includes an evaporator configured to receive a flow of refrigerant and transfer heat into the refrigerant within the evaporator to provide cooling for a temperature-controlled space, an expansion valve operable to modulate the flow of refrigerant into the evaporator, a liquid level sensor configured to measure a level of liquid accumulated within a component of the refrigeration system, and a controller configured to operate the expansion valve to increase the flow of refrigerant into the evaporator or decrease the flow of refrigerant into the evaporator based on the level of liquid measured by the liquid level sensor.

An oil supply system for a compressor according to an embodiment includes an oil separator connected to a discharge pipe of the compressor, an oil tank for receiving oil from an oil sump of the oil separator, an oil pipe disposed between the oil separator and the oil tank, a pressure reducing valve disposed on the oil pipe, an oil supply pipe for supplying the oil to an oil line for supplying the oil to the compressor from an oil sump of the oil tank, and an agitator disposed on the oil pipe.

System and methods for OCR sensing with a suction-line accumulator are provided. The accumulator may include a sensor configured to detect the level of oil. The accumulator may further include a valve which opens when oil is at a high-level and closes when oil is at a low-level. The accumulator may measure a mass flow rate of oil in the vapor compression cycle system based on an amount of time taken to fill a portion of the accumulator. The accumulator may further determine an oil circulation ratio based on the measured time taken to fill the portion of the accumulator. The smart accumulator may output the oil circulation ratio.

A liquid level detection device that is provided in a vessel and configured to detect a liquid level of fluid stored in the vessel includes a first plate formed in a plate shape, and a second plate formed in a plate shape and disposed to face the first plate. The first plate is disposed in such a manner that a surface opposite to a surface facing the second plate is orthogonal to a flow direction of fluid around the first plate in the vessel.

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.

The following invention relates to a dual loop conventional chiller plant, hereafter referred to as the enhanced air conditioning chiller. Where the first loop, primary circuit, typifies refrigeration compression closed loop containing the air conditioning companion stabilizer (“aka” stabilizer); establishing efficiency enhancements. The refrigeration loop is configured to provide refrigerant at a set point temperature amenable to the charging, ice production or freezing brine solution, contained within the ice storage tank static reservoir. The enhanced air conditioning chiller air handler(s) provides space/zones climate control via a fluid at a prescribed temperature, hereafter referred to as a hydronic solution, maintaining the air temperature to the space/zones.

The present disclosure provides a compressor with an oil equalizing pipe, a parallel compressor set, and an oil equalizing method. The compressor includes at least one oil equalizing pipe, an opening at one end of the oil equalizing pipe is formed in a target oil level of an oil sump, and the opening at the other end of the oil equalizing pipe is formed in a suction port; and when the oil level of the oil sump of the compressor is higher than the target oil level, the extra oil enters the suction port through the oil equalizing pipe. Compared with the prior art, the present disclosure has the advantages that, when the compressor is running, the gas in the suction port flows, so that the pressure at the suction port is less than the pressure on the surface of the oil sump; when the oil level of the oil sump of the compressor is higher than the target oil level, the extra oil enters the suction port through the oil equalizing pipe under the action of the above pressure difference, a part of the oil enters vortex and is discharged from the compressor via the exhaust port, and the oil discharged from the compressor returns to the other compressor lack of oil through a pipeline, thereby achieving oil balance between different compressors.