Gas-liquid separator capable of controlling lubricating oil circulation volume and control method thereof

Abstract

The invention discloses a gas-liquid separator capable of controlling the lubricating oil circulation volume. The gas-liquid separator comprises a tank, a three-phase fluid pipe extending into the tank, a gas outlet formed in the upper portion of the tank, a liquid outlet and an oil outlet, wherein the liquid outlet and the oil outlet are formed in the lower portion of the tank. The gas outlet is connected with a gas outlet pipe. The gas outlet pipe comprises an oil return section not higher than the oil outlet in the vertical direction. The oil return section and the oil outlet are communicated through an oil conveying pipe. The oil conveying pipe is provided with an adjusting valve used for controlling flow. The liquid outlet is higher than the oil outlet in the vertical direction. The invention further discloses a lubricating oil circulation volume control method of the gas-liquid separator. The gas-liquid separator is simple in structure, the lubricating oil circulation volume can be conveniently and effectively controlled through the gas-liquid separator and the control method, and stability and heat exchange efficiency of a refrigerating and heating pump system using the gas-liquid separator are improved.

Description

technical field [0001] The invention relates to the technical field of refrigeration and heat pumps, in particular to a gas-liquid separator capable of controlling the circulation amount of lubricating oil and a control method. Background technique [0002] In the field of carbon dioxide refrigeration / heat pump, the gas-liquid separator can store the refrigerant in the internal part of the system, prevent the compressor from decompressing, expand the system capacity, and adjust the system pressure. A common carbon dioxide gas-liquid separator is mainly composed of a tank, a two-phase fluid inlet, an exhaust pipe, and a liquid outlet. The two-phase fluid inlet is located in the middle of the tank, and the liquid outlet is located at the bottom of the tank. The air inlet of the exhaust pipe is located inside the tank body, one end is located on the upper part of the tank body as the gas outlet in the tank, and the other end is connected to the tank body. There is a small hole...

AI Technical Summary

Problems solved by technology

[0003] In compressed carbon dioxide refrigeration / heat pump systems, due to good compatibility, PAG is often used as compressor lubricating oil, and PAG lubricating oil and carbon dioxide cannot be completely miscible in the system

During operation, the insoluble lubricating oil will circulate in the system along with carbon dioxide. Too much lubricating oil will lead to a decrease in the heat exchange efficiency of the heat exchanger, which will have a serious negative impact on the system COP, while insufficient lubricating oil will cause The compressor exhaust temperature rises, the compressor efficiency drops and other adverse effects, and even damages the compressor in severe cases

[0004] However, when the existing carbon dioxide refrigeration / heat pump system is running, due to the high density, the insoluble lubricating oil will accumulate at the bottom of the gas-liquid separator. The ordinary gas-liquid separator makes the lubricating oil Go back to the compressor to maintain the steady state operation of the system, but it does not have the control function of the oil circuit, and the oil circulation of the system is related to the mass flow rate of carbon dioxide, which will change with the change of working conditions, especially when using variable frequency compression When the machine is running, the oil circulation volume will change with the frequency of the compressor. When the oil circulation volume increases and the system operates in a steady state, the accumulation of lubricating oil at the bottom of the gas-liquid separator will also increase, which will cause a large amount of lubricating oil to The liquid enters the evaporator, which reduces the heat transfer efficiency of the evaporator; similarly, when the oil circulation decreases, the lubricating oil accumulation at the bottom of the gas-liquid separator decreases, resulting in excess carbon dioxide liquid passing through the oil outlet of the exhaust pipe, and the carbon dioxide gas into the compressor, causing the compressor inlet to be filled with liquid

Images