A cold storage cold storage subcooling refrigeration system and its control method

Abstract

A cold storage cold storage and subcooling refrigeration system and control method are disclosed. The refrigeration system includes a compressor, oil separator, condenser, liquid storage tank, dryer filter, cold storage unit, subcooler, evaporator, gas-liquid separator, water tank, water pump, electronic expansion valve, shut-off valve, control device, and information acquisition device. The information acquisition device collects load-related parameters in real time, calculates the real-time load of the cold storage, compares it with the design load, and determines the system operating status. The control device meets the cooling demand of the cold storage by adjusting the start-stop and operating frequency of the compressor unit and the opening degree of the electronic expansion valve. It also achieves intelligent switching between three modes: normal cooling, combined cold storage and subcooling cooling, by dynamically adjusting the shut-off valve, electronic expansion valve, and water pump. This system, through the coordinated operation of cold storage and subcooling, stores cold energy during low-load periods and releases cold energy during high-load periods to increase the subcooling degree of the refrigerant, significantly improving system energy efficiency and operational stability, and is suitable for the high-efficiency and energy-saving operation of cold storage.

Description

Technical Field

[0001] This invention relates to the field of cold storage refrigeration technology, specifically to a cold storage cold storage subcooling refrigeration system and control method. Background Technology

[0002] As a core infrastructure of cold chain logistics, cold storage costs consistently account for 20% to 40% of the operating expenses of related enterprises. To ensure reliability under extreme conditions (such as high summer temperatures, high temperatures of goods entering the warehouse, and frequent door openings), traditional cold storage units are typically designed based on maximum load, resulting in refrigeration capacity far exceeding daily needs. This excessive design redundancy causes the system to operate at low load (load rate often below 50%) for most of the normal operating time, leading to high initial investment and low operating efficiency. When the load rate decreases, the coefficient of performance (COP) of the refrigeration unit deteriorates sharply, and equipment such as compressors and condenser fans deviate from their high-efficiency operating points for extended periods, resulting in continuous "idling energy consumption" and poor system operating economy.

[0003] To address the aforementioned technical challenges, existing cold storage refrigeration technology typically employs the method of adding independent cold storage devices to store cold energy during off-peak hours and releasing it during peak hours, thus achieving "peak shaving and valley filling" to reduce operating electricity costs. A search and analysis of relevant patent technologies is as follows.

[0004] Existing Chinese patent document (CN219244023U) proposes a cold storage system using ethylene glycol solution as the medium. During off-peak electricity hours, a separate cold storage unit stores the low-temperature solution in a storage tank, and during peak electricity hours, valves switch to directly supply the cooling capacity to the cold storage coils. This method replaces Freon with a low-temperature refrigerant, solving environmental and temperature difference issues related to cold storage. However, the cold storage system and the main refrigeration cycle are only in parallel, with the cold energy supply relationship limited. The cold release process is merely a direct transfer of cold energy, failing to utilize the stored cold energy to improve the efficiency of the main refrigeration cycle itself. The overall energy efficiency improvement is limited, and its operation relies on preset valve combinations, lacking dynamic optimization strategies based on real-time load. Chinese patent document (CN111503973A) proposes a small, mobile cold storage system using cold storage balls. Phase change cold storage balls are filled into the cold storage pool to improve temperature uniformity, and an integrated intelligent control system enables automatic cooling replenishment when the temperature exceeds the limit. This technology optimizes the structure of the cold storage unit, making it suitable for mobile and flexible scenarios. However, its core remains the direct storage and retrieval of sensible / latent cold heat in an "ice-making-melting" manner. The coordination between the cold storage process and the efficient operating range of the refrigeration unit is insufficient, failing to address the fundamental issue of COP decline under partial load. Furthermore, the system is designed for small, mobile scenarios, and its structure, capacity, and control complexity are difficult to transfer to large industrial cold storage facilities. Chinese patent document (CN209181364U) proposes a solar-powered ice storage cold storage facility that uses photovoltaic DC power to directly drive the refrigeration unit for ice making and cold storage, integrating the cold storage water tank into the warehouse wall. This solution achieves green energy substitution and structural integration, but the system's power supply stability is entirely dependent on sunlight conditions, resulting in weak reliability under continuous severe weather. Its cold storage and release process still follows the traditional ice storage mode, exhibiting problems such as large water tank footprint and complex phase change process control. Moreover, its operating modes are mostly based on inherent day-night cycles, failing to finely match and regulate with the dynamic heat load of the cold storage, and cannot cope with drastic load fluctuations caused by frequent door openings and goods entering the warehouse.

[0005] Therefore, in response to the common problems of design redundancy and low efficiency under low load in existing cold storage systems, as well as the limitations of insufficient coupling and rigid operation strategies in traditional cold storage technology systems, there is an urgent need for a new technology that can deeply integrate the cold storage process with the operation of the refrigeration unit and can dynamically optimize the system according to the real-time status of the system, so as to achieve a significant improvement in the overall energy efficiency of the system and a reduction in operating costs under load fluctuation conditions. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention aims to propose a cold storage cold storage and subcooling refrigeration system and its control method. This refrigeration system introduces a cold storage accumulator and a subcooler, deeply coupled with the main refrigeration circuit. Building upon traditional refrigeration modes, it adds a mode of combined cold storage release and main unit operation. The core principle is that the cold release process is not directly used for cooling, but rather for subcooling the refrigerant at the condenser outlet, thereby simultaneously improving the cooling capacity and operational efficiency of the main refrigeration system during peak load periods. The system allows for flexible switching between multiple operating modes through valve group switching and water pump operation status switching, and performs dynamic optimization control based on the cold storage load. It aims to solve the problems of low efficiency under low load operation, insufficient capacity during high load periods, and poor coupling and coordination between traditional cold storage systems and the main unit, ultimately achieving overall system energy efficiency improvement and operating cost reduction.

[0007] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution: A cold storage subcooling refrigeration system includes a compressor, with its outlet connected to the inlet of an oil separator; a first outlet of the oil separator connected to the inlet of an air-cooled condenser, and a second outlet of the oil separator connected to the compressor's oil return port; an outlet of the air-cooled condenser connected to the inlet of a liquid storage tank; an outlet of the liquid storage tank connected to the inlet of a dryer filter; an outlet of the dryer filter splitting into two branches connected to the inlets of a first shut-off valve and a second shut-off valve respectively; an outlet of the first shut-off valve connected to the inlet of a first electronic expansion valve; an outlet of the first electronic expansion valve connected to the refrigerant-side inlet of the cold storage unit; an outlet of the cold storage unit's refrigerant-side inlet connected to the inlet of a gas-liquid separator; an outlet of the second shut-off valve connected to the refrigerant-side inlet of a subcooler; an outlet of the subcooler's refrigerant-side inlet splitting into two branches connected to the inlets of a second electronic expansion valve and a third electronic expansion valve respectively; an outlet of the second electronic expansion valve connected to the inlet of a first evaporator; and an outlet of the first evaporator connected to the gas-liquid separator. The system is connected to the following components: the inlet of the first evaporator is connected to the outlet of the third electronic expansion valve; the outlet of the second evaporator is connected to the inlet of the gas-liquid separator; the gas phase outlet of the gas-liquid separator is connected to the inlet of the compressor; the water-side outlet of the cold storage unit is connected to the first inlet of the cold storage subcooling water tank; the first outlet of the cold storage subcooling water tank is connected to the inlet of the first water pump; the outlet of the first water pump is connected to the water-side inlet of the cold storage unit; the water-side outlet of the subcooler is connected to the second inlet of the cold storage subcooling water tank; the second outlet of the cold storage subcooling water tank is connected to the inlet of the second water pump; and the outlet of the second water pump is connected to the water-side inlet of the subcooler. The cold storage subcooling module, consisting of the cold storage unit, subcooler, and cold storage subcooling water tank, is connected to the following components: the inlet of the control device is connected to the information acquisition device; and the outlet of the control device is connected to the regulating mechanisms of the compressor, the first shut-off valve, the second shut-off valve, the first electronic expansion valve, the second electronic expansion valve, the third electronic expansion valve, the first water pump, and the second water pump.

[0008] The compressor can be a single compressor or a parallel compressor unit, with fixed frequency or variable frequency, and the operating mode and capacity of the compressor can be flexibly matched according to the actual system refrigeration needs, making it suitable for cold storage of different sizes and usage scenarios.

[0009] The refrigerant is distributed using a liquid receiver tank. When the system operating flow rate decreases, the liquid receiver tank stores excess refrigerant; when the system operating flow rate increases, the liquid receiver tank replenishes refrigerant, thereby effectively regulating the pressure of the refrigeration system and ensuring that the compressor's high and low pressures and the system operating flow rate are within the design range.

[0010] The heat storage device and subcooler are plate heat exchangers or shell-and-tube heat exchangers, which can be flexibly selected according to the actual working conditions. Both can ensure efficient heat exchange during the heat storage and subcooling process, and the equipment is easy to manufacture and maintain.

[0011] The system uses a cold storage tank and a subcooler to perform cold storage and subcooling. During cold storage, the cold storage subcooling tank contains hot water, and the refrigerant side of the cold storage tank is the cold end, while the water side is the hot end. During subcooling, the cold storage subcooling tank contains cold water, and the refrigerant side of the subcooler is the hot end, while the water side is the cold end. By changing the water temperature in the cold storage subcooling tank, the system switches between cold storage and subcooling modes, making full use of the cold energy stored during low-load periods to increase the refrigerant subcooling during high-load periods.

[0012] The control method for a cold storage subcooling refrigeration system includes: the information acquisition device collecting data such as the set cold storage temperature, indoor and outdoor ambient temperature and humidity, number of indoor operators, door opening status, and ventilation status, and monitoring the cold storage load in real time. Q The system controls the compressor's start / stop and operating frequency, as well as the opening degrees of the second and third electronic expansion valves, through a control device to regulate the refrigerant flow rate and meet cooling demands. The information acquisition device will display the real-time load data. Q With design load Q A comparison of zero values ​​determines the operating mode of the refrigeration system. The operating status of the first shut-off valve, second shut-off valve, first electronic expansion valve, first water pump, and second water pump is controlled by a control device to switch the cold storage operating mode. The specific control method is as follows: 1) When the real-time load of the cold storage increases, the number of compressor units connected in parallel or the operating frequency is increased. The control device controls the opening of the second and third electronic expansion valves to increase the refrigerant flow rate and improve the cooling capacity of the refrigeration system to meet the cooling demand of the cold storage. When the real-time load of the cold storage decreases, the number of compressor units connected in parallel or the operating frequency is reduced. The control device controls the opening of the second and third electronic expansion valves to decrease the refrigerant flow rate and reduce the cooling capacity of the refrigeration system to meet the cooling demand of the cold storage. 2) When 40% Q 0≤ Q ≤85% QAt 0:00, the system's cooling load demand is moderate, and it is in normal cooling mode. The control device controls the first shut-off valve to close, the second shut-off valve to open, the first electronic expansion valve to close, the first water pump to close, and the second water pump to close. At this time, the cold storage subcooling module does not work, and the entire system is connected to the cold release subcooling path. However, the cold release subcooling path only serves as a section of pipeline and does not play a role. The refrigerant flowing out of the dryer filter enters the subcooler (without subcooling effect) after passing through the second shut-off valve. Then, it is divided into two paths and enters the second electronic expansion valve and the third electronic expansion valve for throttling. Then, it enters the first evaporator and the second evaporator for evaporation. After completing the cooling of the warehouse environment, it enters the gas-liquid separator. 3) When Q ≤40% Q At 0:00, the system's cooling load demand is low, and it operates in a combined cold storage and normal cooling mode. The control device opens the first and second shut-off valves, the first electronic expansion valve, the first water pump, and the second water pump. At this time, the cold storage subcooling module is in cold storage mode, and the entire system connects the cold storage path and the cold release subcooling path. However, the cold release subcooling path only serves as a section of pipeline and does not play a role. The refrigerant flowing out of the dryer filter is divided. One part passes through the first shut-off valve and enters the first electronic expansion valve for throttling. Then it enters the cold storage unit to exchange heat with the hot water side, and after completing cold storage, it enters the gas-liquid separator. The other part passes through the second shut-off valve and enters the subcooler (without subcooling effect). Then it is divided into two paths and enters the second and third electronic expansion valves for throttling. Then it enters the first and second evaporators for evaporation, and after completing the cooling of the warehouse environment, it enters the gas-liquid separator. The hot water in the cold storage subcooling water tank flows out from the first outlet, passes through the first water pump, enters the cold storage unit to exchange heat with the throttled refrigerant, and becomes cold water before returning to the cold storage subcooling water tank from the first inlet. 4) When Q ≥85% Q At 0:00, the system's cooling load demand is high, and it operates in a combined subcooling and normal cooling mode. The control device closes the first shut-off valve, opens the second shut-off valve, closes the first electronic expansion valve, closes the first water pump, and opens the second water pump. At this time, the cold storage subcooling module is in the cold release subcooling mode, and the entire system is connected to the cold release subcooling path. The refrigerant flowing out of the dryer filter enters the subcooler after passing through the second shut-off valve and exchanges heat with the cold water side. After subcooling, it is divided into two paths and enters the second and third electronic expansion valves for throttling. Then it enters the first and second evaporators for evaporation, and after completing the cooling of the warehouse environment, it enters the gas-liquid separator. The cold water in the cold storage subcooling water tank flows out from the second outlet, passes through the second water pump, enters the subcooler to exchange heat with the condensed refrigerant, becomes hot water, and returns to the cold storage subcooling water tank from the second inlet.

[0013] Compared with the prior art, the present invention has the following advantages: 1. With "cold release and subcooling" as the core, the system achieves simultaneous improvement in capacity and energy efficiency during high-load periods. The cold storage and subcooling module is deeply coupled with the main refrigeration circuit. During high-load or high-temperature periods, the stored cold energy is used to subcool the refrigerant at the condenser outlet (instead of directly supplying cooling), which significantly improves the system's cooling capacity and operating energy efficiency (COP). This effectively breaks through the limitation of traditional cold storage only serving as "cold energy supplementation" and alleviates the problems of increased system pressure ratio and decreased efficiency under high-temperature conditions. 2. Through multi-mode intelligent switching and dynamic control, the system achieves efficient and economical operation under all working conditions. It features three automatic switching modes: normal cooling supply, combined cooling and cold storage, and cold release / subcooling. The operating strategy can be dynamically adjusted according to real-time load. This not only solves the persistent problem of low efficiency in traditional cold storage under low load conditions but also achieves load shifting through "off-peak electricity storage and peak electricity efficiency enhancement," significantly reducing overall energy consumption and electricity costs. Simultaneously, it enhances the system's stability in response to load fluctuations and extends equipment lifespan. Attached Figure Description

[0014] Figure 1 This is a flow chart of a cold storage and subcooling refrigeration system according to the present invention.

[0015] 1. Compressor; 2. Oil separator; 3. Air-cooled condenser; 4. Liquid receiver; 5. Dryer filter; 6. Cold accumulator; 7. Subcooler; 8. Cold storage subcooling water tank; 9. First evaporator; 10. Second evaporator; 11. Gas-liquid separator; 12. Control device; 13. Information acquisition device; 101. First shut-off valve; 102. Second shut-off valve; 103. First electronic expansion valve; 104. Second electronic expansion valve; 105. Third electronic expansion valve; 106. First water pump; 107. Second water pump. Detailed Implementation

[0016] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and some embodiments. It should be understood that the embodiments described herein are only for explaining the invention and are not intended to limit the invention.

[0018] Implementation Cases like Figure 1As shown, a cold storage subcooling refrigeration system includes a compressor 1. The outlet of compressor 1 is connected to the inlet of an oil separator 2 to separate the lubricating oil from the high-temperature, high-pressure gas discharged from the compressor, preventing the lubricating oil from entering subsequent pipelines and affecting heat exchange efficiency. Simultaneously, the separated lubricating oil is returned to the compressor to ensure reliable lubrication. The first outlet of the oil separator 2 is connected to the inlet of an air-cooled condenser 3, and the second outlet of the oil separator 2 is connected to the oil return port of compressor 1. The outlet of the air-cooled condenser 3 is connected to the inlet of a liquid receiver 4, used to store and regulate the refrigerant in the system. When changes in system load cause fluctuations in refrigerant flow, the liquid receiver can absorb excess refrigerant or replenish refrigerant when it is insufficient, thereby stabilizing the system pressure and ensuring the compressor's performance. The machine operates within a safe range; the outlet of the liquid receiver 4 is connected to the inlet of the dryer filter 5 to remove moisture and impurities from the refrigerant, prevent ice blockage and dirt blockage, and protect subsequent throttling components and heat exchangers; the outlet of the dryer filter 5 is split into two paths, connected to the inlets of the first shut-off valve 101 and the second shut-off valve 102 respectively; the outlet of the first shut-off valve 101 is connected to the inlet of the first electronic expansion valve 103; the outlet of the first electronic expansion valve 103 is connected to the refrigerant-side inlet of the cold accumulator 6; the refrigerant-side outlet of the cold accumulator 6 is connected to the inlet of the gas-liquid separator 11; the outlet of the second shut-off valve 102 is connected to the refrigerant-side inlet of the subcooler 7; the refrigerant-side outlet of the subcooler 7 is split into two paths, connected to the inlets of the second electronic expansion valve 104 and the third electronic expansion valve 105 respectively. The outlet of the second electronic expansion valve 104 is connected to the inlet of the first evaporator 9; the outlet of the first evaporator 9 is connected to the inlet of the gas-liquid separator 11; the outlet of the third electronic expansion valve 105 is connected to the inlet of the second evaporator 10; the outlet of the second evaporator 10 is connected to the inlet of the gas-liquid separator 11; the gas phase outlet of the gas-liquid separator 11 is connected to the inlet of the compressor 1 to prevent the compressor 1 from sucking in liquid refrigerant, avoid liquid slugging damage to the compressor, and ensure safe operation of the system; the water-side outlet of the cold storage accumulator 6 is connected to the first inlet 121 of the cold storage subcooling water tank 8; the first outlet 123 of the cold storage subcooling water tank 8 is connected to the inlet of the first water pump 106; the outlet of the first water pump 106 is connected to the water-side inlet of the cold storage accumulator 6; the water-side outlet of the subcooler 7 is connected to the first inlet 123 of the cold storage subcooling water tank 8. The two inlets 122 are connected; the second outlet 124 of the cold storage subcooling water tank 8 is connected to the inlet of the second water pump 107; the outlet of the second water pump 107 is connected to the water-side inlet of the subcooler 7; the water tank 8 serves as a storage container for the cold storage medium (water), forming a water circulation loop with the cold storage 6 and the subcooler 7 to realize the storage and release of cold energy. The water pumps 106 and 107 drive the water circulation respectively to ensure the efficient operation of the heat exchange process; the inlet of the control device 12 is connected to the information acquisition device 13; the outlet of the control device 12 is connected to the regulating mechanism of the compressor 1, the first shut-off valve 101, the second shut-off valve 102, the first electronic expansion valve 103, the second electronic expansion valve 104, the third electronic expansion valve 105, the first water pump 106, and the second water pump 107;Control device 12, as the core control unit of the system, receives data from information acquisition device 13 and issues commands to each actuator accordingly to achieve automated and intelligent operation; information acquisition device 13 senses environmental changes and operating status inside and outside the cold storage in real time, providing a data foundation for precise control.

[0019] The present invention discloses a control method for a cold storage subcooling refrigeration system. An information acquisition device 13 collects data such as the set cold storage temperature, indoor and outdoor ambient temperature and humidity, number of operators, door opening status, and ventilation status. These parameters comprehensively reflect the actual heat load changes of the cold storage. Personnel entry and exit and door opening lead to cold loss, while ventilation introduces warm, humid air from outside. Real-time monitoring of these factors helps the system accurately calculate the current required cooling capacity, avoiding over-cooling or under-cooling, and enabling real-time monitoring of the cold storage load. Q The control device 12 controls the start-stop and operating frequency of the compressor 1, and the opening degrees of the second electronic expansion valve 104 and the third electronic expansion valve 105 to adjust the refrigerant flow rate of the system to meet cooling demand. This real-time load-based adjustment method enables the system to provide cooling on demand. Compared with traditional fixed-frequency start-stop control, it can significantly reduce energy consumption and improve temperature control accuracy. The information acquisition device 13 will display the real-time load... Q With design load Q 0 comparison, Q The 16kW setting determines the refrigeration system's operating mode. Control device 12 controls the operation of the first shut-off valve 101, the second shut-off valve 102, the first electronic expansion valve 103, the first water pump 106, and the second water pump 107, switching the cold storage operating mode. By setting a load threshold for mode switching, the system can operate under optimal conditions: storing cold energy at low loads and releasing cold energy at high loads, achieving energy time shifting and thus improving overall energy efficiency. The specific control method is as follows: 1) When the real-time load of the cold storage increases, the number of parallel units of compressor 1 increases or the operating frequency increases. The control device 12 controls the opening of the second electronic expansion valve 104 and the third electronic expansion valve 105 to increase the refrigerant flow rate and improve the cooling capacity of the refrigeration system to meet the cooling demand of the cold storage. When the real-time load of the cold storage decreases, the number of parallel units of compressor 1 decreases or the operating frequency decreases. The control device 12 controls the opening of the second electronic expansion valve 104 and the third electronic expansion valve 105 to decrease the refrigerant flow rate and reduce the cooling capacity of the refrigeration system to meet the cooling demand of the cold storage. This adjustment method can make the refrigeration output of the system accurately match the real-time load, avoid energy waste and mechanical shock caused by frequent start-stop of the compressor, and extend the equipment life. 2) When 6.4kW≤ QWhen the load is ≤13.6kW, the system's cooling load demand is moderate, and it is in normal cooling mode. Control device 12 controls the first shut-off valve 101 to close, the second shut-off valve 102 to open, the first electronic expansion valve 103 to close, the first water pump 106 to close, and the second water pump 107 to close. At this time, the cold storage and subcooling module composed of the cold storage tank 6, subcooler 7, and cold storage and subcooling water tank 8 does not work. The entire system is connected to the cold release and subcooling path, but the cold release and subcooling path only serves as a section of pipeline and does not function. The refrigerant flowing from the dryer filter 5 passes through the second... After the shut-off valve 102, the liquid enters the subcooler 7 (without subcooling function), then splits into two paths and enters the second electronic expansion valve 104 and the third electronic expansion valve 105 for throttling. After that, it enters the first evaporator 9 and the second evaporator 10 for evaporation, and after completing the cooling of the warehouse environment, it enters the gas-liquid separator 11. In this mode, due to the moderate load, the cooling demand can be efficiently met by relying solely on the main refrigeration cycle, allowing the cold storage subcooling module to be in standby mode, avoiding unnecessary energy loss and water pump operation energy consumption. The system operates in the simplest path and has high reliability. 3) When Q When the system load is ≤6.4kW, the cooling load demand is low, and it operates in a combined cold storage and normal cooling mode. Control device 12 controls the opening of the first shut-off valve 101, the second shut-off valve 102, the first electronic expansion valve 103, the first water pump 106, and the second water pump 107. At this time, the cold storage subcooling module is in cold storage mode, and the entire system connects the cold storage path and the cold release subcooling path. However, the cold release subcooling path only serves as a section of piping and does not function. The refrigerant flowing from the dryer filter 5 is split; part of it passes through the first shut-off valve 101 and then enters the first electronic expansion valve 103 for throttling, before entering the cold storage unit 6 to exchange heat with the hot water side. After completing cold storage, it enters the gas-liquid separator 11; the other part... After passing through the second shut-off valve 102, the refrigerant enters the subcooler 7 (without subcooling function), then splits into two paths, entering the second electronic expansion valve 104 and the third electronic expansion valve 105 for throttling. It then enters the first evaporator 9 and the second evaporator 10 for evaporation, completing the cooling of the warehouse environment before entering the gas-liquid separator 11. Hot water in the cold storage subcooled water tank 8 flows out from the first outlet 123, passes through the first water pump 106, and enters the cold storage tank 6 to exchange heat with the throttled refrigerant, becoming chilled water before returning to the cold storage subcooled water tank 8 from the first inlet 121. In this mode, due to the low load, the system, while meeting the current small cooling demand, utilizes excess cooling capacity to cool the water in the tank through the cold storage tank 6 to store cold energy. The advantage of this is that it takes advantage of off-peak hours when electricity prices are low or there is surplus cooling energy to store cold energy, preparing for subsequent peak loads and achieving "peak shaving and valley filling." 4) When QWhen the load is ≥13.6kW, the system has a high cooling load demand and operates in a combined subcooling and normal cooling mode. Control device 12 controls the first shut-off valve 101 to close, the second shut-off valve 102 to open, the first electronic expansion valve 103 to close, the first water pump 106 to close, and the second water pump 107 to open. At this time, the cold storage subcooling module is in a cold release subcooling mode, and the entire system is connected to the cold release subcooling path. The refrigerant flowing from the dryer filter 5 passes through the second shut-off valve 102 and enters the subcooler 7 to exchange heat with the chilled water side. After subcooling, it splits into two paths and enters the second electronic expansion valve 104 and the third electronic expansion valve 107. The refrigerant is throttled by expansion valve 105, then enters the first evaporator 9 and the second evaporator 10 for evaporation, completing the cooling of the warehouse environment before entering the gas-liquid separator 11. The chilled water in the cold storage subcooling tank 8 flows out from the second outlet 124, passes through the second water pump 107, and enters the subcooler 7 to exchange heat with the condensed refrigerant, becoming hot water before returning to the cold storage subcooling tank 8 from the second inlet 122. In this mode, due to the high load, the system activates the subcooling mode, passing the chilled water previously stored in the tank 8 into the subcooler 7 to further cool the refrigerant liquid flowing out of the condenser 3 (i.e., subcooling). Increasing the subcooling degree increases the heat absorption capacity of the refrigerant, thereby increasing the system's cooling capacity without increasing compressor power consumption, effectively coping with peak loads, while simultaneously reducing the compressor's pressure ratio and improving operational stability.

Claims

1. A cold storage subcooling refrigeration system, characterized in that, Includes a compressor (1), the outlet of which is connected to the inlet of an oil separator (2); the first outlet of the oil separator (2) is connected to the inlet of an air-cooled condenser (3), and the second outlet of the oil separator (2) is connected to the oil return hole of the compressor (1); the outlet of the air-cooled condenser (3) is connected to the inlet of a liquid storage tank (4); the outlet of the liquid storage tank (4) is connected to the inlet of a dryer filter (5); the outlet of the dryer filter (5) is split into two paths and connected to the inlets of a first shut-off valve (101) and a second shut-off valve (102) respectively; the outlet of the first shut-off valve (101) is connected to the inlet of a first electronic expansion valve (103); the first electronic expansion valve (103) is connected to the inlet of a second electronic expansion valve (103); the first electronic expansion valve (103) is connected to the inlet of a third electronic expansion valve (103). The outlet of expansion valve (103) is connected to the refrigerant side inlet of cold accumulator (6); the refrigerant side outlet of cold accumulator (6) is connected to the inlet of gas-liquid separator (11); the outlet of second shut-off valve (102) is connected to the refrigerant side inlet of subcooler (7); the refrigerant side outlet of subcooler (7) is split into two paths and connected to the inlets of second electronic expansion valve (104) and third electronic expansion valve (105) respectively; the outlet of second electronic expansion valve (104) is connected to the inlet of first evaporator (9); the outlet of first evaporator (9) is connected to the inlet of gas-liquid separator (11); the outlet of third electronic expansion valve (105) is connected to the inlet of second evaporator (104) and third electronic expansion valve (105) respectively; 10) The inlet is connected; the outlet of the second evaporator (10) is connected to the inlet of the gas-liquid separator (11); the gas phase outlet of the gas-liquid separator (11) is connected to the inlet of the compressor (1); the water-side outlet of the cold storage unit (6) is connected to the first inlet (121) of the cold storage subcooling water tank (8); the first outlet (123) of the cold storage subcooling water tank (8) is connected to the inlet of the first water pump (106); the outlet of the first water pump (106) is connected to the water-side inlet of the cold storage unit (6); the water-side outlet of the subcooler (7) is connected to the second inlet (122) of the cold storage subcooling water tank (8); the second outlet (124) of the cold storage subcooling water tank (8) is connected to the second The inlet of the water pump (107) is connected; the outlet of the second water pump (107) is connected to the water-side inlet of the subcooler (7); the cold storage subcooling module is composed of the cold storage tank (6), the subcooler (7) and the cold storage subcooling water tank (8); the inlet of the control device (12) is connected to the information acquisition device (13); the outlet of the control device (12) is connected to the regulating mechanism of the compressor (1), the first shut-off valve (101), the second shut-off valve (102), the first electronic expansion valve (103), the second electronic expansion valve (104), the third electronic expansion valve (105), the first water pump (106), and the second water pump (107).

2. The cold storage subcooling refrigeration system according to claim 1, characterized in that: The compressor (1) is a single compressor or a parallel compressor unit, with fixed frequency or variable frequency.

3. The cold storage subcooling refrigeration system according to claim 1, characterized in that: The liquid receiver (4) is used to distribute the refrigerant. When the system operating flow rate decreases, the liquid receiver (4) stores the excess refrigerant. When the system operating flow rate increases, the liquid receiver (4) replenishes the refrigerant, thereby effectively regulating the pressure of the refrigeration system and ensuring that the compressor high and low pressure and the system operating flow rate are within the design range.

4. The cold storage subcooling refrigeration system according to claim 1, characterized in that: The regenerator (6) and subcooler (7) are plate heat exchangers or shell-and-tube heat exchangers.

5. A cold storage subcooling refrigeration system according to claim 1, characterized in that: The cold storage and subcooling are accomplished by using a cold storage tank (6) and a subcooler (7). During cold storage, the cold storage subcooling water tank (8) contains hot water, the refrigerant side of the cold storage tank (6) is the cold end, and the water side is the hot end. During subcooling, the cold storage subcooling water tank (8) contains cold water, the refrigerant side of the subcooler (7) is the hot end, and the water side is the cold end.

6. A control method for a cold storage subcooling refrigeration system according to any one of claims 1 to 5, characterized in that: The information acquisition device (13) collects the set cold storage temperature, indoor and outdoor ambient temperature and humidity, number of indoor operators, door opening status, and ventilation status, and monitors the cold storage load in real time. Q The control device (12) controls the start-stop and operating frequency of the compressor (1), and the opening degree of the second electronic expansion valve (104) and the third electronic expansion valve (105) to adjust the refrigerant flow rate of the system to meet the cooling demand; the information acquisition device (13) will display the real-time load Q With design load Q 0 comparison determines the refrigeration system operation mode. The operation status of the first shut-off valve (101), the second shut-off valve (102), the first electronic expansion valve (103), the first water pump (106), and the second water pump (107) are controlled by the control device (12) to switch the cold storage operation mode. The specific control method is as follows: 1) When the real-time load of the cold storage increases, the compressor (1) increases the number of parallel units or increases the operating frequency, and the control device (12) controls the opening of the second electronic expansion valve (104) and the third electronic expansion valve (105) to increase, the refrigerant flow rate increases, and the refrigeration capacity of the refrigeration system is improved to meet the cold storage cooling demand; when the real-time load of the cold storage decreases, the compressor (1) reduces the number of parallel units or decreases the operating frequency, and the control device (12) controls the opening of the second electronic expansion valve (104) and the third electronic expansion valve (105) to decrease, the refrigerant flow rate decreases, and the refrigeration capacity of the refrigeration system is reduced to meet the cold storage cooling demand. 2) When 40% Q 0≤ Q ≤85% Q At 0 o'clock, the system's cooling load demand is moderate and it is in normal cooling mode. The control device (12) controls the first shut-off valve (101) to close, the second shut-off valve (102) to open, the first electronic expansion valve (103) to close, the first water pump (106) to close, and the second water pump (107) to close. At this time, the cold storage subcooling module does not work, and the entire system is connected to the cold release subcooling passage. However, the cold release subcooling passage is only used as a section of pipeline and does not play a role. The refrigerant flowing out from the dryer filter (5) enters the subcooler (7) without subcooling effect after passing through the second shut-off valve (102). Then it enters the second electronic expansion valve (104) and the third electronic expansion valve (105) for throttling, and then enters the first evaporator (9) and the second evaporator (10) for evaporation. After completing the cooling of the warehouse environment, it enters the gas-liquid separator (11). 3) When Q ≤40% Q At 0 o'clock, the system's cooling load demand is low, and it is in a combined operation mode of cold storage and normal cooling. The control device (12) controls the first shut-off valve (101) to open, the second shut-off valve (102) to open, the first electronic expansion valve (103) to open, the first water pump (106) to open, and the second water pump (107) to close. At this time, the cold storage subcooling module is in cold storage mode, and the entire system is connected to the cold storage passage and the cold release subcooling passage. However, the cold release subcooling passage is only used as a section of pipeline and does not play a role. The refrigerant flowing out of the dryer filter (5) is diverted. A part of it passes through the first shut-off valve (101) and enters the first electronic expansion valve (103) for throttling, and then enters the cold storage unit (6) and... The hot water undergoes heat exchange on the hot side and enters the gas-liquid separator (11) after completing the cold storage. The other part passes through the second shut-off valve (102) and enters the subcooler (7) without subcooling effect. Then it is divided into two paths and enters the second electronic expansion valve (104) and the third electronic expansion valve (105) for throttling. Then it enters the first evaporator (9) and the second evaporator (10) for evaporation. After completing the cooling of the warehouse environment, it enters the gas-liquid separator (11). The hot water in the cold storage subcooling water tank (8) flows out from the first outlet (123), passes through the first water pump (106), and enters the cold storage tank (6) to exchange heat with the throttled refrigerant. After becoming cold water, it returns to the cold storage subcooling water tank (8) from the first inlet (121). 4) When Q ≥85% Q At 0 o'clock, the system has a high cooling load demand and is in a combined subcooling and normal cooling operation mode. The control device (12) controls the first shut-off valve (101) to close, the second shut-off valve (102) to open, the first electronic expansion valve (103) to close, the first water pump (106) to close, and the second water pump (107) to open. At this time, the cold storage subcooling module is in the cold release subcooling mode, and the entire system is connected to the cold release subcooling path. The refrigerant flowing out from the dryer filter (5) enters the subcooler (7) and mixes with the cold water after passing through the second shut-off valve (102). After the side heat exchange is completed and the subcooling is completed, the water is divided into two paths and enters the second electronic expansion valve (104) and the third electronic expansion valve (105) for throttling. Then it enters the first evaporator (9) and the second evaporator (10) for evaporation. After completing the cooling of the warehouse environment, it enters the gas-liquid separator (11). The cold water in the cold storage subcooling water tank (8) flows out from the second outlet (124), passes through the second water pump (107), and enters the subcooler (7) to exchange heat with the condensed refrigerant. After becoming hot water, it returns to the cold storage subcooling water tank (8) from the second inlet (122).

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