Refrigeration system

Abstract

The refrigeration system comprises: a main flow path comprising a compressor, a condenser, a throttling device and an evaporator, wherein the compressor comprises at least a first compression stage and a second compression stage; and the refrigeration system further comprises: an ejector configured to eject low-pressure refrigerant from the evaporator by means of high-pressure refrigerant from the condenser and to mix them into medium-pressure gas-liquid two-phase refrigerant; and a separator configured to separate the medium-pressure gas-liquid two-phase refrigerant from the ejector into gas-phase refrigerant and liquid-phase refrigerant, to deliver the gas-phase refrigerant separated to a gas supply port between a fluid outlet of the first compression stage and a fluid inlet of the second compression stage in the compressor, and to deliver the liquid-phase refrigerant separated to a motor housing of the compressor for cooling a rotor and a stator in the motor housing by flash evaporation.

What is claimed is: 
     
         1 . A refrigeration system, comprising:
 a main flow path comprising a compressor, a condenser, a throttling device and an evaporator, wherein the compressor comprises at least a first compression stage and a second compression stage;   which is characterized in that the refrigeration system further comprising:   an ejector configured to eject low-pressure refrigerant from the evaporator by means of high-pressure refrigerant from the condenser and to mix them into medium-pressure gas-liquid two-phase refrigerant; and   a separator configured to separate the medium-pressure gas-liquid two-phase refrigerant from the ejector into gas-phase refrigerant and liquid-phase refrigerant, to deliver the gas-phase refrigerant separated to a gas supply port between a fluid outlet of the first compression stage and a fluid inlet of the second compression stage in the compressor, and to deliver the liquid-phase refrigerant separated to a motor housing of the compressor for cooling a rotor and a stator in the motor housing by flash evaporation.   
     
     
         2 . The refrigeration system according to  claim 1 , wherein a plurality of ejectors are provided and are arranged in parallel, wherein high-pressure fluid inlets of the plurality of ejectors are connected near bottom of the condenser and fluid suction inlets of the plurality of ejectors are connected near internal liquid level of the evaporator. 
     
     
         3 . The refrigeration system according to  claim 1 , wherein the compressor is an oil-free two-stage centrifugal compressor. 
     
     
         4 . The refrigeration system according to  claim 3 , wherein the compressor comprises an electromagnetic bearing, a gas bearing or a refrigerant-lubricated bearing. 
     
     
         5 . A refrigeration system, comprising:
 a main flow path comprising a compressor, a condenser, a throttling device and an evaporator,   wherein, the compressor comprises at least a first compression stage and a second compression stage;   which is characterized in that the refrigeration system further comprising:   an ejector configured to eject low-pressure refrigerant from an oil-rich layer of the evaporator by means of high-pressure refrigerant from the condenser and to mix them into medium-pressure gas-liquid two-phase refrigerant;   a separator configured to separate the medium-pressure gas-liquid two-phase refrigerant from the ejector into gas-phase refrigerant and liquid-phase refrigerant, to deliver the gas-phase refrigerant separated to a gas supply port between a fluid outlet of the first compression stage and a fluid inlet of the second compression stage in the compressor, and to deliver the liquid-phase refrigerant separated to a motor housing of the compressor for cooling a rotor and a stator in the motor housing by flash evaporation; and   an oil tank arranged downstream of the separator for filtering oil from the liquid-phase refrigerant and delivering the oil to a compressor bearing chamber.   
     
     
         6 . The refrigeration system according to  claim 5 , wherein an oil pump is provided in the oil tank for delivering oil in the oil tank to the compressor bearing chamber. 
     
     
         7 . The refrigeration system according to  claim 6 , wherein a heater for heating up oil is provided in the oil tank. 
     
     
         8 . The refrigeration system according to  claim 5 , wherein a plurality of ejectors are provided and are arranged in parallel, wherein high-pressure fluid inlets of the plurality of ejectors are connected near bottom of the condenser and fluid suction inlets of the plurality of ejectors are connected near internal liquid level of the evaporator. 
     
     
         9 . The refrigeration system according to  claim 5 , wherein the oil tank is a container, and an inlet port of the oil tank is connected to a range from near the internal liquid level of the separator to the bottom of the separator. 
     
     
         10 . The refrigeration system according to  claim 5 , wherein the compressor is an oil-lubricated two-stage centrifugal compressor.