CO2 Heat Pump System or CO2 Refrigeration System Comprising an Ejector Assembly and Method for Controlling an Ejector Assembly of a CO2 Heat Pump System or a CO2 Refrigeration System

Abstract

A CO 2 based system, such as a heat pump system or a refrigeration system, is disclosed. The system comprises a plurality of ejectors arranged in parallel. Each of the ejectors comprises a motive port and a suction port. Each of the ejectors has a fixed geometry. A first actuated ball valve is arranged in front of the motive port. A second actuated ball valve is arranged in front of the suction port. The system comprises a control unit arranged and configured to control the activity of the ball valves on the basis of one or more predefined criteria.

What is claimed is: 
     
         1 . A CO 2  based system comprising:
 one or more ejectors each having a motive port, a suction port, and a fixed geometry wherein a first actuated ball valve is arranged in front of the motive port and a second actuated ball valve is arranged in front of the suction port; and   a control unit arranged and configured to control the activity of the first actuated ball valve and the second actuated ball valve on the basis of one or more predefined criteria.   
     
     
         2 . The system according to  claim 1 , further comprising two or more ejectors arranged in parallel. 
     
     
         3 . The system according to  claim 1 , wherein the CO 2  based system is a heat pump system or a refrigeration system. 
     
     
         4 . The system according to  claim 1 , further comprising:
 a liquid-gas separator having an inlet port, a gas outlet port and a liquid outlet port;   a gas cooler having an inlet port and an outlet port;   a high pressure valve arranged between the outlet port of the gas cooler and the inlet port of the liquid-gas separator;   a temperature sensor arranged to detect a temperature of fluid leaving the gas cooler;   a pressure sensor arranged to detect a pressure of the fluid leaving the gas cooler;   an evaporator having an inlet port and an outlet port, wherein the suction ports of the ejectors are in fluid communication with the evaporator, wherein the inlet port of the evaporator is in fluid communication with the liquid outlet port of the liquid-gas separator;   a gas-bypass valve arranged between the gas outlet port of the liquid-gas separator and the evaporator;   an intermediate temperature compressor arranged between the gas outlet port of the liquid-gas separator and the inlet port of the gas cooler; and   a medium temperature compressor arranged between the gas outlet port of the liquid-gas separator and the inlet port of the gas cooler.   
     
     
         5 . The system according to  claim 4 , wherein the control unit is configured to detect an opening degree of the high-pressure valve and to open one or more of the first actuated ball valves arranged in front of the motive ports of the ejectors if:
 the control unit is in operation state; and   the opening degree of the high pressure valve is equal to or higher than a predefined level.   
     
     
         6 . The system according to  claim 5 , wherein the control unit is configured to determine an opening degree of the gas-bypass valve and to open the second actuated ball valves arranged in front of the suction ports of one or more of the ejectors if:
 the motive ports of the one or more of the ejectors are open;   the temperature of the fluid at the outlet port of the gas cooler is within a predefined temperature range;   the suction pressure at the intermediate temperature compressor is within a predefined range;   the opening degree of the gas-bypass valve is below a predefined level;   a number of actively operated ejectors corresponds to a predefined number based on a number of actively operated medium temperature compressors; and   a capacity of the intermediate temperature compressors is below 100%.   
     
     
         7 . The system according to  claim 5 , wherein the control unit is configured to close one or more of the first actuated ball valves arranged in front of the motive ports of the ejectors if:
 the opening degree of the high pressure valve is equal to or less than a predefined level;   the pressure at the outlet port of the gas-cooler is equal to or less than a predefined setpoint pressure; and   the suction ports for the respective ejectors are closed.   
     
     
         8 . The system according to  claim 7 , wherein the control unit is configured to determine an opening degree of the gas-bypass valve and to open the second actuated ball valves arranged in front of the suction ports of one or more of the ejectors if:
 the motive ports of the one or more of the ejectors are open;   the temperature of the fluid at the outlet port of the gas cooler is within a predefined temperature range;   the suction pressure at the intermediate temperature compressor is within a predefined range;   the opening degree of the gas-bypass valve is below a predefined level;   a number of actively operated ejectors corresponds to a predefined number based on a number of actively operated medium temperature compressors; and   a capacity of the intermediate temperature compressors is below 100%.   
     
     
         9 . The system according to  claim 8 , wherein the control unit is configured to close the second actuated ball valves arranged in front of the suction ports of one or more of the ejectors if any of following constraints is met:
 a temperature of the fluid leaving the gas cooler is outside the predefined temperature range;   the opening degree of the gas-bypass valve exceeds the predefined level;   the number of actively operated ejectors exceeds the predefined number that is based on the number of actively operated medium temperature compressors.   
     
     
         10 . A method for controlling a CO 2  based system having one or more ejectors having a motive port, a suction port, and a fixed geometry wherein a first actuated ball valve is arranged in front of the motive port and a second actuated ball valve is arranged in front of the suction port, the method comprising:
 controlling the activity of the first actuated ball valve and the second actuated ball valve on the basis of one or more predefined criteria.   
     
     
         11 . The method according to  claim 10 , further comprising two or more ejectors arranged in parallel. 
     
     
         12 . The method according to  claim 10 , wherein the CO 2  based system is a heat pump system or a refrigeration system. 
     
     
         13 . The method according to  claim 10 , wherein the CO 2  based system comprises:
 a liquid-gas separator having an inlet port, a gas outlet port and a liquid outlet port;   a gas cooler having an inlet port and an outlet port;   a high pressure valve arranged between the outlet port of the gas cooler and the inlet port of the liquid-gas separator;   a temperature sensor arranged to detect a temperature of fluid leaving the gas cooler;   a pressure sensor arranged to detect a pressure of the fluid leaving the gas cooler;   an evaporator having an inlet port and an outlet port, wherein the suction ports of the ejectors are in fluid communication with the evaporator, wherein the inlet port of the evaporator is in fluid communication with the liquid outlet port of the liquid-gas separator;   a gas-bypass valve arranged between the gas outlet port of the liquid-gas separator and the evaporator;   an intermediate temperature compressor arranged between the gas outlet port of the liquid-gas separator and the inlet port of the gas cooler; and   a medium temperature compressor arranged between the gas outlet port of the liquid-gas separator and the inlet port of the gas cooler.   
     
     
         14 . The method according to  claim 13 , further comprising:
 detecting an opening degree of the high-pressure valve;   opening one or more of the first actuated ball valves arranged in front of the motive ports of the ejectors if:   a) the control unit is in operation state; and   b) the opening degree of the high pressure valve is equal to or higher than a predefined level.   
     
     
         15 . The method according to  claim 14 , wherein one or more of the first actuated ball valves arranged in front of the motive ports of the ejectors are closed if:
 the opening degree of the high pressure valve is equal to or less than a predefined level;   the pressure at the outlet port of the gas-cooler is equal to or less than a predefined setpoint pressure; and   the suction ports for the respective ejectors are closed.   
     
     
         16 . The method according to  claim 14 , further comprising:
 detecting an opening degree of the gas-bypass valve, wherein the second actuated ball valves arranged in front of the suction ports of one or more of the ejectors are opened if:   the motive ports of the one or more of the ejectors are open;   the temperature of the fluid at the outlet port of the gas cooler is within a predefined temperature range;   the suction pressure at the intermediate temperature compressor is within a predefined range;   the opening degree of the gas-bypass valve is below a predefined level;   a number of actively operated ejectors corresponds to a predefined number based on a number of actively operated medium temperature compressors; and   a capacity of the intermediate temperature compressors is below 100%.   
     
     
         17 . The method according to  claim 16 , further comprising:
 closing the second actuated ball valves arranged in front of the suction ports of one or more of the ejectors if any of following constraints is met:   the temperature of the fluid leaving the gas cooler is outside the predefined temperature range;   the opening degree of the gas-bypass valve exceeds the predefined level;   the number of actively operated ejectors exceeds the predefined number that is based on the number of actively operated medium temperature compressors.