Carbon dioxide auxiliary supercooling system utilizing shallow well water

Abstract

The utility model discloses a carbon dioxide auxiliary supercooling system utilizing shallow well water, which comprises a main circulation refrigerating system and a shallow well water supercooling system, the main circulation refrigerating system is connected with the shallow well water supercooling system through an auxiliary supercooler, and the shallow well water supercooling system passes through the auxiliary supercooler. Further, the main cycle refrigerating system comprises a low-pressure-stage CO2 compressor, the low-pressure-stage CO2 compressor is sequentially connected with a high-pressure-stage CO2 compressor, an auxiliary subcooler, a first throttling valve, a gas-liquid separator and an evaporator, and the gas-liquid separator and the low-pressure-stage CO2 compressor are connected in parallel and then connected with the high-pressure-stage CO2 compressor in series. A two-stage compression system is adopted, the compression ratio of each stage is reduced, the performance coefficient of the system is improved, and meanwhile the process requirement for high CO2 pressure can be met. Supercooling is conducted through shallow well water, the water temperature change is small all the year round, and the system can be accurately controlled; meanwhile, the variable-frequency water pump is adopted, so that the system is more energy-saving.

Description

Technical Field

[0001] The utility model relates to the technical field of refrigeration systems, in particular to a carbon dioxide-assisted supercooling system utilizing shallow well water. Background Art

[0002] With the continuous development of my country's economy and the improvement of people's living standards, people have begun to study new technologies that are more environmentally friendly and energy-saving. Traditional cold storage systems generally use ammonia as a refrigerant, because ammonia refrigeration systems have a large cooling capacity, but ammonia is toxic and flammable. It is urgent to find a suitable refrigerant to replace existing HCFCs, HFCs and other refrigerants.

[0003] At present, environmentally friendly refrigerants are also being developed and researched. Natural refrigerants such as carbon dioxide, ammonia, water, and air have returned to people's horizons, and natural refrigerants have become the best choice to replace traditional refrigerants. Among all natural refrigerants, CO2 is a very promising refrigerant with an ozone depletion index (ODP) of 0 and a global warming potential (GWP) of 1. It is non-toxic and non-flammable, making it a popular choice for alternative refrigerants.

[0004] However, carbon dioxide has a low critical temperature in the refrigeration system, a high pressure as a refrigerant, and is greatly affected by the ambient temperature, resulting in poor system performance. If CO2 is not cooled more efficiently, the dryness of the refrigerant will increase after direct throttling, and the refrigeration performance coefficient will be too low. In order to deal with this problem, the most direct way is to establish a lower temperature heat sink environment to effectively supercool CO2.

[0005] Patent CN 106839485 A discloses a carbon dioxide transcritical refrigeration cycle system based on solar-driven auxiliary supercooling. The utility model converts solar energy into electrical energy through a solar power generation system to supercool the refrigerant, thereby increasing the refrigeration capacity, reducing the fuel consumption of the driving compressor, and improving the performance of the refrigeration system. However, the technical solution uses components such as a compressor in the auxiliary supercooling system, which makes the system form more complicated and also increases the economic cost.

[0006] Patent CN 107621093 A discloses a CO2 refrigeration system based on evaporative cooler supercooling with residual pressure recovery. The utility model supercools the CO2 fluid at the outlet of the CO2 gas cooler through an evaporative cooler auxiliary system, reduces the irreversible loss in the CO2 throttling process, and improves the COP of the refrigeration system. However, the technical solution cannot flexibly switch the supercooling mode. When the ambient temperature is lower than the cooling water temperature, the system cannot operate normally, and the cooling water temperature cannot be well controlled. Utility Model Content

[0007] The utility model aims at solving the problems existing in the prior art and provides a carbon dioxide-assisted supercooling system utilizing shallow well water.

[0008] In order to achieve the above objectives, the present invention is implemented through the following technical solutions:

[0009] A carbon dioxide-assisted supercooling system using shallow well water comprises a main circulation refrigeration system and a shallow well water supercooling system. The main circulation refrigeration system is connected to the shallow well water supercooling system via an auxiliary supercooler, and the shallow well water supercooling system supercools the main circulation refrigeration system via the auxiliary supercooler.

[0010] Furthermore, the main circulation refrigeration system includes a low-pressure CO2 compressor, which is connected in sequence to a high-pressure CO2 compressor, an auxiliary subcooler, a throttle valve one, a gas-liquid separator, a throttle valve two, and an evaporator. The gas-liquid separator and the low-pressure CO2 compressor are connected in parallel through a bypass valve and then connected in series with the high-pressure CO2 compressor.

[0011] Furthermore, the auxiliary subcooler includes a water-cooled subcooler, one end of the water-cooled subcooler is connected to a throttle valve, and the other end is connected in sequence to a gas cooler and a heat exchanger, and the heat exchanger is connected to a high-pressure CO2 compressor.

[0012] Furthermore, a three-way control valve is provided between the water-cooled subcooler and the gas cooler, and the three-way control valve controls whether the CO2 refrigerant in the gas cooler flows through the water-cooled subcooler.

[0013] Furthermore, the shallow well water supercooling system includes a shallow water well, which is sequentially connected to a water pump, a water-cooled supercooler, and a heat exchanger. The water pump draws water from the shallow water well and sends it to the water-cooled supercooler and the heat exchanger in sequence.

[0014] Furthermore, the heat exchanger is also connected to a water reservoir, which is connected to a hot water pump, a filter, a water flow regulating valve, and a user end in sequence. The heat exchanger discharges the shallow well water after heat exchange into the water reservoir, and the hot water pump extracts it and sends it to the user end after passing through the filter and the water flow regulating valve in sequence.

[0015] Furthermore, the water pump is connected to a mixed water supply system, which includes at least one water supply pipe. A water cooling pipe is provided on the outer wall of each water supply pipe, and a temperature detector is provided on the upper part. Multiple water supply pipes are connected through a multi-way control valve. The water cooling pipe circulates and draws shallow well water to cool the water supply pipe. The temperature detector detects the water temperature in the water supply pipe. The multi-way control valve mixes the shallow well water in the water supply pipe with the lowest temperature.

[0016] Furthermore, the water cooling pipe is an inverted M-shaped pipe, one end of which is connected to the water pump and the other end is suspended above the well water.

[0017] Beneficial effects of the utility model:

[0018] (1) A two-stage compression system is used to reduce the compression ratio of each stage, improve the system performance coefficient, and also meet the process requirements of high CO2 pressure.

[0019] (2) Shallow well water is used for supercooling, and the water temperature changes little throughout the year, which enables precise control of the system; at the same time, the use of variable frequency water pumps can make the system more energy-efficient.

[0020] (3) It can control the start and stop of the water-cooled subcooling system according to the ambient temperature, and control the subcooling degree by adjusting the water flow rate according to system requirements.

[0021] (4) Shallow well water is used to supercool the system. The supercooled well water can be used to reduce the exhaust temperature of the high-pressure CO2 compressor, which can reduce the temperature of the refrigerant entering the gas cooler, thereby reducing the carrying load of the gas cooler, while also making full use of the shallow well water in the system.

[0022] (5) The COP of the CO2 refrigeration system in subtropical regions can be improved by cooling CO2 to below the ambient temperature through an auxiliary subcooling system.

[0023] (6) The system is supercooled using natural working fluids such as air and water, which are cheap and easy to obtain. The temperature of the supercooled well water is relatively high and can be collected in a reservoir for supply to the user end. Compared with the traditional mechanical supercooling system, it has obvious environmental advantages.

[0024] (7) The mixed water supply system can provide shallow well water with lower temperature to the shallow well water supercooling system, thereby improving the efficiency of heat exchange and allowing the temperature of the cold storage to drop rapidly. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a functional block diagram of the carbon dioxide assisted supercooling system of the utility model;

[0026] Figure 2 This is a structural schematic diagram of the carbon dioxide assisted supercooling system of the utility model;

[0027] Figure 3 This is a schematic diagram of the structure of the main circulation refrigeration system of the utility model;

[0028] Figure 4 This is a schematic diagram of the structure of the shallow well water supercooling system of the utility model;

[0029] Figure 5 It is a structural schematic diagram of the hybrid water supply system of the utility model.

[0030] In the figure: 1-user end, 2-water flow regulating valve 1, 3-filter 1, 4-hot water pump, 5-water reservoir, 6-low-pressure CO2 compressor, 7-high-pressure CO2 compressor, 8-heat exchanger, 9-gas cooler, 10-temperature monitor, 11-three-way control valve, 12-water-cooled subcooler, 13-throttle valve 1, 14-gas-liquid separator, 15-bypass valve, 16-throttle valve 2, 17-evaporator, 18-thermometer, 19-differential pressure gauge, 20-water flow regulating valve 2, 21-filter 2, 22-water pump, 23-shallow water well, 24-water supply pipeline, 25-water cooling pipeline, 26-temperature detector, 27-multi-way control valve, 28-water pump. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0032] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0033] Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0034] The purpose of the utility model is to provide a carbon dioxide assisted supercooling system suitable for subtropical areas, which supercools the supercooler in the system through shallow well water cooling and air cooling, thereby improving the supercooling degree of the refrigeration system and thus improving the performance of the entire system; and uses natural working fluid CO2 to ensure that the refrigeration system is environmentally friendly.

[0035] Please refer to Figure 1 The utility model provides a carbon dioxide assisted supercooling system using shallow well water, including a main circulation refrigeration system and a shallow well water supercooling system. The main circulation refrigeration system is connected to the shallow well water supercooling system through an auxiliary supercooler, and the shallow well water supercooling system assists the supercooler for refrigeration.

[0036] The main circulation refrigeration system refrigerates, so that the auxiliary subcooler has cold energy, and the auxiliary subcooler releases the cold energy to the cold storage environment to reduce the temperature of the cold storage environment. When the refrigeration effect of the main circulation refrigeration system cannot achieve the predetermined refrigeration effect, the shallow well water subcooling system is started. The shallow well water subcooling system uses the temperature difference to exchange heat with the auxiliary subcooler to reduce the temperature of the auxiliary subcooler, thereby assisting in improving the refrigeration effect of the system, thereby achieving the required temperature of the cold storage.

[0037] Please refer to Figure 2 and Figure 3 The main circulation refrigeration system includes a low-pressure CO2 compressor 6, which is connected to the evaporator 17 to absorb the low-pressure CO2 gas after absorbing heat in the evaporator 17 and perform initial compression on the low-pressure CO2 gas.

[0038] The low-pressure CO2 compressor 6 is connected to the high-pressure CO2 compressor 7. The CO2 gas compressed by the low-pressure CO2 compressor 6 enters the high-pressure CO2 compressor 7. The high-pressure CO2 compressor 7 performs secondary compression on the CO2 gas, so that the CO2 gas forms a supercritical fluid.

[0039] The high-pressure CO2 compressor 7 is connected to the auxiliary supercooler, which cools the supercritical CO2 fluid so that the supercritical CO2 fluid in a high-pressure state has cold energy. The auxiliary supercooler further cools the supercritical CO2 fluid at the outlet of the gas cooler by using cold water with a lower temperature in shallow well water, thereby improving the refrigeration effect of the system.

[0040] The auxiliary subcooler is connected to a throttle valve 13, which is used to control the low-temperature and high-pressure CO2 fluid cooled by the auxiliary subcooler. The throttle valve 13 is connected to a gas-liquid separator 14, which is connected to an evaporator 17 via a throttle valve 16, and is connected to the outlet of a low-pressure CO2 compressor 6. The throttle valve 16 is used to deliver the low-temperature and low-pressure CO2 fluid into the evaporator 17.

[0041] The gas-liquid separator 14 is connected in parallel with the low-pressure CO2 compressor 6 through the bypass valve 15. The gas-liquid separator 14 separates the liquid CO2 refrigerant in the low-temperature and low-pressure gas-liquid two-phase fluid state and sends it to the evaporator 17 through the throttle valve 16. The gaseous CO2 refrigerant is separated and mixed with the gaseous CO2 refrigerant at the outlet of the low-pressure CO2 compressor 6 after hot gas bypass through the bypass valve 15. The mixed gaseous CO2 refrigerant is compressed by the high-pressure CO2 compressor. The evaporator 17 absorbs the heat in the cold storage to cool the cold storage. The CO2 liquid that absorbs the heat of the cold storage and heats up enters the low-pressure CO2 compressor for compression to complete the refrigeration cycle.

[0042] Please refer to Figure 3The auxiliary subcooler includes a water-cooled subcooler 12, one end of the water-cooled subcooler 12 is connected to a throttle valve 13, and the other end is connected to a gas cooler 9 and a heat exchanger 8 in sequence, and the heat exchanger 8 is connected to a high-pressure CO2 compressor 7. The water of the shallow water well 23 passes through the water-cooled subcooler 12 and the heat exchanger 8 in sequence to assist in cooling the CO2 refrigerant at the outlet of the gas cooler 9 and the outlet of the high-pressure CO2 compressor 7, respectively. The well water in the gas cooler 9 exchanges temperature with the cold storage environment to cool down the cold storage environment. The water-cooled subcooler 12 and the gas cooler 9 are connected by a three-way control valve 11, and the three-way control valve 11 is used to control the flow direction of the CO2 refrigerant. By opening and closing the three-way control valve 11, the auxiliary subcooler can be controlled to stop running, and the main circulation refrigeration system can run alone. The three-way control valve 11 is also connected to a temperature monitor 10, which detects the ambient temperature and sends the detection result to the main control unit. The main control unit controls the opening and closing of the three-way control valve 11 according to the detection result to start or close the auxiliary supercooler. The main control unit is the control center of the entire refrigeration system and is a microcontroller used in existing cold storage refrigeration systems. This application does not describe it in detail.

[0043] Please refer to Figure 2 and Figure 4 The shallow well water supercooling system includes a shallow water well 23, which is connected to a water pump 22. The water pump 22 is a variable frequency water pump, and its model can be selected according to actual needs. The water pump 22 is used to extract well water from the shallow water well 23. The well water temperature is relatively low and can be used for system supercooling.

[0044] The water pump 22 is connected in turn with a filter 21, which is used to filter the shallow well water extracted by the water pump 22 to ensure that clean shallow well water enters the circulation system. The filter 21 is connected to the water volume regulating valve 20, which is used to adjust the amount of well water entering the supercooling system. The water volume regulating valve 20 is connected to the water-cooled supercooler 12. The shallow well water enters the water-cooled supercooler 12 to cool the CO2 refrigerant in the water-cooled supercooler 12, and then enters the heat exchanger 8 to cool the CO2 refrigerant in the heat exchanger 8. The water-cooled supercooler 12 is also provided with a thermometer 18 and a differential pressure gauge 19 on both sides.

[0045] The heat exchanger 8 is also connected to a water reservoir 5, which stores shallow well water with a certain amount of heat after heat exchange. A hot water pump 4 is provided in the water reservoir 5, which extracts hot water stored in the water reservoir 5, and then passes through a filter 3 and a water volume regulating valve 2 to reach the user end 1. The user end 1 can utilize the heat of the shallow well water to improve the utilization rate of energy.

[0046] Please refer to Figure 5The water pump 22 is connected to a mixed water supply system, which is used to provide shallow well water with lower temperature for the shallow well water supercooling system. The mixed water supply system includes at least one water supply pipeline 24. In this embodiment, three water supply pipelines 24 are taken as an example. The three water supply pipelines 24 are provided with a temperature detector 26 at the upper part of each water supply pipeline 24. The temperature detector 26 is used to detect the water temperature in the water supply pipeline 24 and send the water temperature information to the main control unit. The multiple water supply pipelines 24 are connected by a multi-way control valve 27, and the multi-way control valve 27 controls the water in any two or several water supply pipelines 24 with lower temperature to mix.

[0047] A water cooling pipe 25 is disposed on the outer wall of each water supply pipe 24. The water cooling pipe 25 circulates and extracts shallow well water to cool the water supply pipe 24. The water cooling pipe 25 is an inverted M-shaped pipe, one end of which is connected to the water pump 28, and the other end is suspended above the well water. The inner wall of the inverted M-shaped pipe is in close contact with the outer wall of the water supply pipe 24, which can well cool the water supply pipe 24.

[0048] Working principle:

[0049] When in use, the main circulation refrigeration system can cool alone. When the main circulation refrigeration system alone cannot reach the required temperature of the cold storage, the shallow well water supercooling system is started for auxiliary cooling. The mixed water supply system draws water from the shallow well water, and mixes the shallow well water in any two or more water supply pipes 24 with lower temperatures and sends them to the water pump 22. The water pump 22 sends the low-temperature shallow well water to the water-cooled supercooler 12 and the heat exchanger 8 in turn to cool the CO2 refrigerant of the main circulation refrigeration system to achieve auxiliary cooling. Finally, the well water after heat exchange is sent to the water reservoir 5 for use by the user end 1.

[0050] The above contents are further detailed descriptions of the present invention in combination with specific preferred implementations, and the specific implementation of the present invention cannot be considered to be limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A carbon dioxide-assisted supercooling system using shallow well water, characterized in that: It comprises a main circulation refrigeration system and a shallow well water supercooling system. The main circulation refrigeration system is connected with the shallow well water supercooling system through an auxiliary supercooler, and the shallow well water supercooling system supercools the main circulation refrigeration system through the auxiliary supercooler.

2. The carbon dioxide-assisted supercooling system using shallow well water according to claim 1, characterized in that: The main circulation refrigeration system comprises a low-pressure CO2 compressor (6), which is connected in sequence to a high-pressure CO2 compressor (7), an auxiliary subcooler, a throttle valve 1 (13), a gas-liquid separator (14), a throttle valve 2 (16), and an evaporator (17). The gas-liquid separator (14) and the low-pressure CO2 compressor (6) are connected in parallel via a bypass valve (15) and then connected in series with the high-pressure CO2 compressor (7).

3. The carbon dioxide-assisted supercooling system using shallow well water according to claim 2, characterized in that: The auxiliary subcooler comprises a water-cooled subcooler (12), one end of which is connected to a throttle valve (13), and the other end of which is connected in sequence to a gas cooler (9), a heat exchanger (8), a heat exchanger (8) and a high-pressure CO2 compressor (7).

4. The carbon dioxide-assisted supercooling system using shallow well water according to claim 3 is characterized in that: A three-way control valve (11) is provided between the water-cooled subcooler (12) and the gas cooler (9), and the three-way control valve (11) controls whether the CO2 refrigerant in the gas cooler (9) flows through the water-cooled subcooler (12).

5. The carbon dioxide-assisted supercooling system using shallow well water according to claim 1, characterized in that: The shallow well water supercooling system comprises a shallow water well (23), the shallow water well (23) is connected in sequence to a water pump (22), a water-cooled supercooler (12), and a heat exchanger (8), and the water pump (22) extracts water from the shallow water well (23) and sends the water to the water-cooled supercooler (12) and the heat exchanger (8) in sequence.

6. The carbon dioxide-assisted supercooling system using shallow well water according to claim 5, characterized in that: The heat exchanger (8) is also connected to a water reservoir (5), which is in turn connected to a hot water pump (4), a filter (3), a water volume regulating valve (2), and a user end (1). The heat exchanger (8) discharges shallow well water after heat exchange into the water reservoir (5), and the hot water pump (4) extracts the water, passes through the filter (3), the water volume regulating valve (2), and then delivers the water to the user end (1).

7. The carbon dioxide-assisted supercooling system using shallow well water according to claim 5, characterized in that: The water pump (22) is connected to a mixed water supply system, which includes at least one water supply pipe (24). A water cooling pipe (25) is provided on the outer wall of each water supply pipe (24), and a temperature detector (26) is provided on the upper part. The multiple water supply pipes (24) are connected through a multi-way control valve (27). The water cooling pipe (25) circulates and extracts shallow well water to cool the water supply pipe (24). The temperature detector (26) detects the water temperature in the water supply pipe (24). The multi-way control valve (27) mixes the shallow well water in the water supply pipe (24) with the lowest temperature.

8. The carbon dioxide-assisted supercooling system using shallow well water according to claim 7, characterized in that: The water cooling pipe (25) is an inverted M-shaped pipe, one end of which is connected to the water pump (28) and the other end is suspended above the well water.

Images