A low-temperature refrigeration system with a booster-expander integrated unit connected by a direct-drive motor

Abstract

The present invention discloses a low-temperature refrigeration system with a booster-expander connected by a direct-drive motor. The refrigeration system includes a booster-expander, a gas storage tank, a cooler, a low-temperature heat exchanger, a freezer, a refrigerator, an intelligent control valve, a pressure and temperature monitor, a pipeline, and a control system. The booster-expander is composed of a turbine expander, a centrifugal compressor, and a high-speed direct-drive motor, and is supported by a foil dynamic pressure gas bearing; the nozzle opening and speed of the booster-expander can be continuously adjusted to change the circulation pressure and flow of the system. The low-temperature refrigeration system has multiple cooling modes such as pure freezing, freezing and refrigeration, as well as multiple cooling modes such as rapid cooling mode and ultra-low temperature mode, which can meet energy-saving needs and different cooling needs; the entire system operates purely without oil and has high heat exchange efficiency; the friction loss of moving parts is small and basically requires no maintenance; the compressor is integrated on the turbine expander, the structure is very compact, and the system volume and weight are greatly reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of low-temperature refrigeration, and in particular relates to a low-temperature refrigeration system of a booster-expander integrated machine connected by a direct-drive motor. Background Art

[0002] With the development of society, the demand for low-temperature environments in many fields such as modern industry, energy, transportation, medical care and food freezing is constantly increasing. At present, the refrigeration methods that are more widely used in the field of low-temperature refrigeration are cascade refrigeration, Stirling refrigeration and reverse Brayton refrigeration. The unit structure and control system of cascade refrigeration are relatively complex, and there are great difficulties in maintenance and servicing. At the same time, the dynamic response of the unit is slow, the stable control accuracy is not high, and if the refrigerant leaks, it may cause pollution. The structure of Stirling refrigeration is simpler than cascade refrigeration, and the operating reliability is also higher. However, the cost of Stirling refrigerators is higher, the noise during operation is louder, and Stirling refrigeration does not have much advantage in the field of general refrigeration. The refrigeration efficiency during stable operation is low.

[0003] The present invention utilizes reverse Brayton refrigeration. Reverse Brayton refrigerators offer advantages such as low vibration, low noise, high efficiency, rapid cooling, and a wide cooling range. In recent years, they have been widely used in fields such as low-temperature superconductivity, gas separation and liquefaction, train air conditioning, cryogenic environment simulation, and food processing. Conventional reverse Brayton refrigerators typically require a separate compressor to supply gas to the turboexpander, making the entire system complex and bulky, limiting their miniaturization and lightweighting, while also increasing system costs.

[0004] To address some of the challenges of existing refrigeration systems, we have developed a low-temperature refrigeration system featuring a turboexpander connected to a direct-drive motor. This system includes a turboexpander, a gas storage tank, a cooler, a low-temperature heat exchanger, a freezer compartment, a refrigerator compartment, an intelligent control valve, a pressure and temperature monitor, piping, and a control system. The turboexpander utilizes foil dynamic pressure gas bearings, which offer oil-free operation, high efficiency, minimal vibration, and low noise. The moving parts experience minimal friction loss, have a long lifespan, and are virtually maintenance-free. The control system allows for continuous adjustment of the turboexpander's nozzle opening and speed, enabling precise control of the refrigeration temperature and providing a fast dynamic response for the entire system. Compared to traditional refrigeration systems, this low-temperature refrigeration system features multiple cooling modes, including pure freezing, freezing with full refrigeration, and freezing with partial refrigeration, as well as rapid cooling and ultra-low temperature modes. These modes meet energy-saving requirements and can be switched between them via the control system based on varying cooling needs. The entire system operates entirely oil-free, achieving high heat exchange efficiency. The integration of the compressor into the turboexpander results in a very compact structure, significantly reducing system size and weight. Summary of the Invention

[0005] The purpose of this application is to provide a low-temperature refrigeration system with a booster-expander connected by a direct-drive motor. This low-temperature refrigeration system can accurately and intelligently control the refrigeration temperature and refrigeration capacity through a control system. The entire low-temperature refrigeration system operates purely oil-free, is very clean, has high heat exchange efficiency, does not need to consider oil return issues, can be placed at any angle, and integrates the compressor on the turbine expander, resulting in a very compact structure and greatly reducing the system volume and weight. The technical solution of the present invention is as follows.

[0006] The present invention discloses a low-temperature refrigeration system of a booster-expander connected by a direct-drive motor; the low-temperature refrigeration system comprises a booster-expander, a gas storage tank, a cooler, a low-temperature heat exchanger, a freezer, a refrigerator, an intelligent control valve, a pressure and temperature monitor, a pipeline and a control system; the booster-expander is composed of a turbine expander, a centrifugal compressor and a high-speed direct-drive motor, the three of which are coaxially connected, the output power of the turbine expander is recovered by the centrifugal compressor, and the high-speed direct-drive motor drives the centrifugal compressor to work, thereby compensating for the operation of the centrifugal compressor; the booster-expander adopts a foil dynamic pressure gas bearing The support has the characteristics of oil-free, high efficiency, micro-vibration and low noise, small friction loss and basically no maintenance; the booster expander can continuously adjust the nozzle opening and speed through the control system, thereby changing the circulation pressure and flow of the system; an intelligent control valve is provided between the freezer, refrigerator and heat exchanger, and the opening of the intelligent control valve can be adjusted by the control system, so as to switch between different cooling modes and cooling modes; the booster expander, cooler and intelligent control valve can be comprehensively adjusted by the control system, so as to achieve accurate and intelligent regulation of the refrigeration temperature and cooling capacity.

[0007] The refrigeration system operates purely without oil, is very clean, and has high heat exchange efficiency; there is no oil filter or oil return device, so there is no need to consider the oil return problem, and the entire system can be placed at any angle.

[0008] The refrigeration system is divided into a pure freezing mode, a freezing plus full refrigeration mode, and a freezing plus partial refrigeration mode. The switching between the various modes can be achieved by adjusting the opening of the intelligent control valve through the control system; in the freezing plus full refrigeration mode, the system can switch between a reheat cycle and a no reheat cycle by adjusting the intelligent control valve. Under the reheat cycle, the system cools down slowly and the lowest refrigeration temperature is low. In this case, it is an extremely low temperature mode. Under the no reheat cycle, the system cools down quickly and the lowest refrigeration temperature is high. In this case, it is a rapid cooling mode. According to the opening of different intelligent control valves, the system can switch between different cooling modes; in the freezing plus partial refrigeration mode, the outlet temperature of the cold storage room can be monitored and compared with the temperature at different positions in the heat exchanger. Finally, the position where the gas enters the heat exchanger can be controlled by the control system, which can reduce unnecessary cooling consumption of low-temperature gas in the heat exchanger and save system energy.

[0009] The high-speed direct-drive motor is a fully enclosed motor. The low-temperature gas from the heat exchanger can cool the high-speed direct-drive motor, thereby fully utilizing the cooling capacity and effectively solving the problem of motor heating.

[0010] The refrigerant of the refrigeration system can be air, nitrogen, neon or other gases. The different physical properties of various refrigerants result in different minimum refrigeration temperatures. The refrigerant can be selected according to the required refrigeration temperature; the refrigerants in the system are all in gaseous state and do not undergo phase change process.

[0011] The cooler is cooled by air or water and adopts a microchannel condenser, which greatly saves heat exchange space. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a system flow chart of a low-temperature refrigeration system of a booster-expander connected to a direct-drive motor provided by the present invention;

[0013] Figure 2 A two-dimensional diagram of a booster-expander integrated unit of a low-temperature refrigeration system connected to a booster-expander integrated unit by a direct-drive motor provided by the present invention;

[0014] A schematic diagram of a low-temperature refrigeration system of a booster-expander connected to a direct-drive motor according to an embodiment of the present application, with reference to the accompanying figures:

[0015] 1. Booster and expander; 11. Centrifugal compressor; 111. Outlet pipe; 112. Compression impeller; 113. Compression end umbrella screw; 114. Inlet chamber; 115. Compressor volute; 116. Compression end gas bearing; 12. High-speed direct-drive motor; 121. Motor stator; 122. Motor rotor; 13. Turbine expander; 131. Expansion end umbrella screw; 132. Expansion impeller; 133. Diffuser; 134. Nozzle; 135. Expansion end gas bearing; 2. Gas storage tank; 3. Cooler; 4. Heat exchanger; 5. Freezer; 6. Refrigerator; 71. Intelligent control valve; 72. Intelligent control valve; 8. Pressure and temperature monitor; 91. Intelligent control valve; 92. Intelligent control valve; 93. Intelligent control valve; 94. Intelligent control valve; 10. Control system. DETAILED DESCRIPTION

[0016] In order to enable those skilled in the art to better understand the objectives, technical solutions and advantages of the present invention, the technical solutions in the embodiments of the present invention will be described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0017] like Figure 1As shown, the present invention provides a low-temperature refrigeration system with a booster-expanding integrated machine connected by a direct-drive motor. The booster-expanding integrated machine low-temperature refrigeration system includes a booster-expanding integrated machine 1, a gas storage tank 2, a cooler 3, a low-temperature heat exchanger 4, a freezer 5, a refrigerator 6, intelligent control valves 71, 72, a pressure and temperature monitor 8, intelligent control valves 91, 92, 93, 94, and a control system 10. The booster-expanding integrated machine 1 is composed of a centrifugal compressor 11, a high-speed direct-drive motor 12, and a turbine expander 13, which are coaxially connected. The booster-expanding integrated machine 1 is supported by a foil dynamic pressure gas bearing, which has low friction loss and basically requires no maintenance; the entire refrigeration system operates purely oil-free and can be placed at any angle. The high-speed direct-drive motor 12 is composed of a motor stator 121 and a motor rotor 122. The high-speed direct-drive motor 12 drives the centrifugal compressor 11 to work and compensates for the operation of the centrifugal compressor 11.

[0018] The centrifugal compressor 11 is driven by a high-speed direct-drive motor 12 and begins rotating. The working gas at ambient temperature and pressure is adiabatically compressed within the centrifugal compressor 11, becoming high-temperature, high-pressure gas. This gas is then stored in the gas storage tank 2. The gas then enters the cooler 3 for isobaric cooling. In this embodiment, the cooler 3 uses air cooling and a microchannel condenser, significantly reducing heat exchange space. The high-pressure, ambient-temperature gas exiting the cooler 3 enters the low-temperature heat exchanger 4 for further cooling, further reducing the inlet temperature of the turboexpander 13. The gas then adiabatically expands within the turboexpander 13, generating a significant amount of cooling capacity. The power output of the turboexpander 13 is recovered by the centrifugal compressor 11, saving system energy. The low-temperature gas exiting the turboexpander 13 enters the freezer 5, where it cools the load within the freezer 5. The flow then controls whether to enter the cold storage compartment 6 based on the cooling demand. Finally, the air, still carrying a certain amount of cooling capacity, flows into the high-speed direct-drive motor 12 to cool the high-speed motor. The gas, having cooled the motor, then flows into the centrifugal compressor 11, completing the entire cycle.

[0019] Depending on whether the user has a refrigeration demand, the refrigeration system is divided into a pure freezing mode, a freezing plus full refrigeration mode, and a freezing plus partial refrigeration mode. The control system 10 can be used to control the opening of the intelligent control valves 71 and 72 between the freezing chamber 5, the refrigeration chamber 6 and the heat exchanger 4 to complete the switching of different modes. There are three specific implementation methods below.

[0020] Implementation 1 is pure freezing mode. At this time, the intelligent control valve 72 between the freezer compartment 5 and the refrigerator compartment 6 is closed, and the intelligent control valve 71 between the freezer compartment 5 and the heat exchanger 4 is fully opened. The low-temperature gas from the freezer compartment 5 will directly enter the heat exchanger 4, further cooling the high-pressure, room-temperature gas inside the heat exchanger. The gas then flows out of the cold-side outlet of the heat exchanger. In this mode, the control system 10 can be used to adjust the speed of the booster and expander and the opening of the movable nozzle, thereby changing the system's circulation pressure and flow, achieving precise and intelligent control of the refrigeration temperature and cooling capacity.

[0021] Implementation 2 is a freezing and full refrigeration mode. In this case, intelligent control valve 71 is closed and intelligent control valve 72 is fully opened, allowing the gas to complete the refrigeration task within the refrigerated compartment. If the cold energy of the low-temperature gas is completely consumed within the refrigerated compartment 6, the gas exiting the refrigerated compartment passes through intelligent control valve 94, and the entire system is now in a non-regenerative cycle. If the cold energy of the low-temperature gas is not completely consumed within the refrigerated compartment 6, the gas exiting the refrigerated compartment 6 can enter the heat exchanger through intelligent control valve 91 to completely cool the high-pressure, room-temperature gas within the heat exchanger, or it can enter the heat exchanger through intelligent control valve 92 or intelligent control valve 93 to partially cool the high-pressure, room-temperature gas within the heat exchanger, and the system is now in a regenerative cycle. The more low-temperature gas enters the regenerative unit, the slower the cooling rate, but the lower the minimum cooling temperature. Users can select different cooling modes based on their desired cooling rate and temperature by controlling the opening of intelligent control valve 91, intelligent control valve 92, intelligent control valve 93, or intelligent control valve 94 through control system 10. When the gas passes through intelligent control valve 91, the cooling speed is slowest and the minimum cooling temperature is lowest. This is the extreme low-temperature mode. At this point, the system speed can be increased, increasing the system circulation pressure to lower the overall system cooling temperature. When the gas passes through intelligent control valve 94, the cooling speed is fastest and the minimum cooling temperature is highest. This is the rapid cooling mode. At this point, the speed can be increased and the nozzle opening can be widened to rapidly cool the entire system. Once the entire system meets the cooling requirements, if continued cooling is required, the speed and nozzle opening can be appropriately reduced through control system 10 to achieve energy savings.

[0022] Implementation method 3 is a freezing plus partial refrigeration mode. At this time, both the intelligent control valve 71 and the intelligent control valve 72 need to be opened, and the opening degree of the intelligent control valve depends on the user's demand for refrigeration. A pressure and temperature monitor 8 is provided at the outlet of the cold storage chamber 6, which can monitor the temperature of the gas coming out of the cold storage chamber 6 and compare it with the measured temperature at different positions in the heat exchanger 4. According to the temperature comparison, the gas can flow into the heat exchanger from the intelligent control valve 92 or the intelligent control valve 93, merge with the low-temperature gas in the heat exchanger, and further cool the high-pressure room-temperature gas therein; if the temperature of the gas coming out of the cold storage chamber is close to the low-temperature outlet temperature of the heat exchanger, the airflow can pass through the intelligent control valve 94 without entering the heat exchanger. By controlling the position where the gas enters the heat exchanger through the control system 10 according to different temperatures, unnecessary cooling loss of the low-temperature gas in the heat exchanger can be reduced, saving system energy.

Claims

1. A low-temperature refrigeration system with a booster and expander connected by a direct drive motor, characterized in that The low-temperature refrigeration system includes a booster-expanding machine, a gas storage tank, a cooler, a low-temperature heat exchanger, a freezer, a refrigerator, an intelligent control valve, a pressure and temperature monitor, a pipeline and a control system; the booster-expanding machine is composed of a turbine expander, a centrifugal compressor and a high-speed direct-drive motor, which are coaxially connected, the output power of the turbine expander is recovered by the centrifugal compressor, and the high-speed direct-drive motor drives the centrifugal compressor to work, thereby compensating for the operation of the centrifugal compressor; the booster-expanding machine is supported by a foil dynamic pressure gas bearing; the nozzle opening and speed of the booster-expanding machine can be continuously adjusted to change the circulation pressure and flow of the system; an intelligent control valve is provided between the freezer, refrigerator and low-temperature heat exchanger, and the opening of the intelligent control valve can be adjusted by the control system to switch between different cooling modes and cooling modes; the low-temperature refrigeration system can comprehensively adjust the booster-expanding machine, the cooler and the intelligent control valve through the control system, thereby achieving accurate and intelligent regulation of the refrigeration temperature and cooling capacity; The centrifugal compressor, gas storage tank, cooler, low-temperature heat exchanger, turbine expander, freezing chamber, cold storage chamber, and high-speed direct drive motor are connected in sequence through pipelines; The low-temperature gas from the low-temperature heat exchanger cools the high-speed direct-drive motor, and the gas after cooling the high-speed direct-drive motor flows into the centrifugal compressor to complete the entire cycle process; The refrigeration system includes a pure freezing mode, a freezing plus full refrigeration mode, and a freezing plus partial refrigeration mode. The switching between the modes can be completed by adjusting the opening of the intelligent control valve through the control system; in the freezing plus full refrigeration mode, the opening of the intelligent control valve can be adjusted so that the system can switch between a heat recovery cycle and a non-heat recovery cycle. According to different cycle types, the system has multiple cooling modes such as a rapid cooling mode and an extremely low temperature mode; in the freezing plus partial refrigeration mode, the outlet temperature of the cold storage room can be monitored, and the position of the gas entering the low-temperature heat exchanger can be controlled by the control system.

2. The low-temperature refrigeration system with a booster and expander connected by a direct drive motor according to claim 1, characterized in that: The refrigeration system operates purely oil-free.

3. The low-temperature refrigeration system with a booster and expander connected by a direct drive motor according to claim 1, characterized in that: The high-speed direct-drive motor is a fully enclosed motor.

4. The low-temperature refrigeration system with a booster and expander connected by a direct drive motor according to claim 1, characterized in that: The refrigerant of the refrigeration system is air, nitrogen or neon; the refrigerants in the system are all in gaseous state and have no phase change process.

5. The low-temperature refrigeration system with a booster and expander connected by a direct drive motor according to claim 1, characterized in that: The cooling method of the cooler is air cooling or water cooling, and a microchannel condenser is used.

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