Refrigerating system and control method thereof

Abstract

The invention relates to a refrigerating system and a control method thereof. The refrigerating system comprises a refrigerating unit, a heat exchange unit, a first pressure detection unit and a control unit. The refrigeration unit comprises a compressor, a condenser, an expansion valve, an evaporator and a circulation pipeline. The heat exchange unit comprises a heat exchange pipeline, and the heat exchange pipeline communicates to the target area and communicates with the evaporator. And the heat exchange pipeline is used for leading out the near-freezing-point liquid-state fluid and enabling the near-freezing-point liquid-state fluid to enter the evaporator to exchange heat with the refrigerant and then return to a target area. The first pressure detection unit is used for detecting inlet and outlet side pressure of the refrigerant. The control unit is electrically connected with the first pressure detection unit, the compressor and the expansion valve and used for controlling the output power of the compressor or the opening degree of the expansion valve according to the inlet and outlet side pressure of the refrigerant so as to control the evaporation temperature of the refrigerant to be within the preset range. According to the refrigerating system, the temperature of the liquid fluid close to the freezing point can be kept close to the freezing point, and direct freezing caused by too low evaporation temperature can be avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of refrigeration equipment, in particular to a refrigeration system and a control method thereof. BACKGROUND

[0002] Generally, to obtain water temperature of 0℃-4℃, an antifreeze can be added to reduce the freezing point. To maintain the target temperature of the medium near the freezing point, the antifreeze is generally used for secondary heat exchange. However, the secondary heat exchange has low efficiency.

[0003] A more traditional way is to put ice blocks into the target area to obtain a water temperature environment of 0℃ by using the balance of coexistence of liquid water and solid ice at 0℃. The main disadvantages of this method are: more and more ice blocks are put in or more and more water is caused, resulting in waste of cold energy. If the medium is like salt water, the concentration and temperature are difficult to control, and it is necessary to ensure that the concentration of the ice blocks put in is consistent with the target water area. If there are living bodies in the water environment, the addition of ice blocks will change the water quality and environment.

[0004] Therefore, there is an urgent need for a refrigeration system with high refrigeration efficiency and avoiding affecting the water quality and environment of the target area. SUMMARY

[0005] An object of the present application is to solve the problems in the prior art and provide a refrigeration system. To solve the above technical problems, the present application adopts the following technical solutions: A refrigeration system for maintaining the temperature of a near-freezing liquid in a target area at a target temperature, comprising: a refrigeration unit comprising a compressor, a condenser, an expansion valve and an evaporator, and a circulation pipeline connecting the compressor, the condenser, the expansion valve and the evaporator, the circulation pipeline being filled with a refrigerant, the refrigerant releasing heat in the condenser and absorbing heat in the evaporator; a heat exchange unit comprising a heat exchange pipeline, the heat exchange pipeline being connected to the target area and being in communication with the evaporator, the heat exchange pipeline being used to lead out the near-freezing liquid and return the near-freezing liquid to the target area after heat exchange with the refrigerant in the evaporator; a first pressure detection unit connected to the inlet and outlet of the refrigerant of the evaporator and used to detect the inlet and outlet pressure of the refrigerant; a control unit electrically connected to the first pressure detection unit, the compressor and the expansion valve, the control unit being used to control the output power of the compressor or the opening degree of the expansion valve according to the inlet and outlet pressure of the refrigerant, so as to control the evaporation temperature of the refrigerant to be within a preset range.

[0006] In one embodiment, the control unit can control the evaporation temperature of the refrigerant to be 2℃-4℃ lower than the target temperature.

[0007] In one embodiment, the refrigerant used is Freon.

[0008] In one embodiment, the refrigerant is an azeotropic Freon.

[0009] In one embodiment, the refrigeration system includes a temperature detector disposed on the near-freezing point liquid fluid outlet side of the evaporator, the temperature detector being used to detect the real-time temperature of the near-freezing point liquid fluid output by the evaporator; The temperature detector is electrically connected to the control unit, which can control the compressor to start and stop based on the real-time temperature.

[0010] In one embodiment, the refrigeration system includes a second pressure detection unit, which is connected to the near-freezing point liquid fluid inlet and outlet of the evaporator, respectively, to detect the inlet and outlet pressures of the near-freezing point liquid fluid. The heat exchange unit also includes a drive pump, which is installed on the heat exchange pipeline and is used to drive the flow of near-freezing liquid fluid; The control unit is electrically connected to the second pressure detection unit and the drive pump respectively. The control unit can control the output power of the drive pump based on the inlet and outlet pressures of the near-freezing liquid fluid.

[0011] In one embodiment, the refrigeration system includes a flow detector disposed on the near-freezing point liquid fluid outlet side of the evaporator, the flow detector being used to detect the flow rate of the near-freezing point liquid fluid output by the evaporator; The flow detector is electrically connected to the control unit, which can control the output power of the pump based on the flow rate.

[0012] In one embodiment, the first pressure detection unit includes a differential pressure detector, which is connected to the refrigerant inlet and refrigerant outlet of the evaporator, respectively.

[0013] In one embodiment, the target area is the interior of the storage tank, and the heat exchange piping is connected to both the evaporator and the interior of the tank; or The target area is the interior of the refrigerator compartment of the refrigeration unit, with heat exchange pipes connected to both the evaporator and the interior of the refrigerator compartment; or The target area is the inside of the aquaculture tank, and the heat exchange pipes are connected to the evaporator and the inside of the tank respectively.

[0014] Another object of the present invention is to provide a control method for a refrigeration system as described in any of the preceding claims, comprising: Obtain the inlet and outlet pressures of the refrigerant in the evaporator; Adjust the compressor's output power or the expansion valve opening according to the inlet and outlet pressures to control the refrigerant evaporation temperature in the evaporator to be 2°C to 4°C lower than the target temperature of the near-freezing liquid fluid.

[0015] In one embodiment, the control method includes: acquiring the inlet and outlet pressures of the near-freezing liquid fluid of the evaporator; and controlling the output power of the drive pump based on the inlet and outlet pressures of the near-freezing liquid fluid.

[0016] As can be seen from the above technical solution, the present invention has at least the following advantages and positive effects: In this invention, the refrigeration system includes a refrigeration unit, a heat exchange unit, a first pressure detection unit, and a control unit. The refrigeration unit includes a compressor, a condenser, an expansion valve, an evaporator, and a circulation pipeline. The heat exchange unit includes a heat exchange pipeline connected to a target area and the evaporator. The heat exchange pipeline is used to draw out a near-freezing-point liquid fluid, which then enters the evaporator to exchange heat with the refrigerant before returning to the target area. The first pressure detection unit is used to detect the inlet and outlet pressures of the refrigerant. The control unit is electrically connected to the first pressure detection unit, the compressor, and the expansion valve, and is used to control the output power of the compressor or the opening degree of the expansion valve according to the inlet and outlet pressures of the refrigerant, so as to control the evaporation temperature of the refrigerant within a preset range.

[0017] In this refrigeration system, the refrigerant in the refrigeration unit exchanges heat with the external environment, and then exchanges heat with a near-freezing-point liquid fluid in the heat exchange pipeline, transferring the cooling capacity to the near-freezing-point liquid fluid. Because it directly uses the near-freezing-point liquid fluid in the target area as the refrigerant, it reduces heat exchange losses, significantly improves the heat exchange efficiency of the refrigeration system, and avoids problems such as increased water volume, wasted cooling capacity, changes in water quality (e.g., affecting the survival of living organisms), and difficulty in controlling the concentration of the medium (e.g., brine) caused by ice-based temperature control. It is suitable for environmentally sensitive application scenarios.

[0018] Furthermore, by controlling the compressor's output power or the expansion valve opening based on the refrigerant's inlet and outlet pressures, the evaporation pressure can be stabilized, and the evaporation temperature can be precisely controlled within a preset range. This allows for precise control of the temperature of the near-freezing liquid fluid output by the evaporator, ensuring that the near-freezing liquid fluid in the target area remains at a near-freezing temperature. It also effectively prevents direct freezing due to excessively low evaporation temperatures, fundamentally solving the ice blockage problem and ensuring the reliability of the refrigeration system. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of a refrigeration system according to an embodiment of the present invention.

[0020] Figure 2 This is a schematic diagram of the control principle of a refrigeration system according to an embodiment of the present invention.

[0021] Figure 3 This is a flowchart illustrating the control method of a refrigeration system according to an embodiment of the present invention.

[0022] The annotations in the attached figures are explained as follows: 10-Compressor; 20-Condenser; 30-Expansion valve; 40-Evaporator; 50-Circulation piping; 60 - Heat exchanger piping; 61 - Temperature detector; 62 - Second pressure detection unit; 63 - Flow detector; 70 - First pressure detection unit; 80 - Control unit; 90 - Drive pump. Detailed Implementation

[0023] Typical embodiments embodying the features and advantages of the present invention will be described in detail in the following description. It should be understood that the present invention can have various variations in different embodiments without departing from the scope of the present invention, and the descriptions and illustrations herein are for illustrative purposes only and not intended to limit the present invention.

[0024] In the description of this application, it should be understood that, in the embodiments shown in the accompanying drawings, the indications of direction or positional relationships (such as up, down, left, right, front, and back, etc.) are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. These descriptions are appropriate when these elements are in the positions shown in the accompanying drawings. If the description of the positions of these elements changes, these directional indications also change accordingly.

[0025] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0026] The refrigeration system of this invention is used to maintain the temperature of a near-freezing-point liquid fluid within a target area at a target temperature. Here, a near-freezing-point liquid fluid refers to a fluid whose temperature is close to 0°C (the freezing point of water) but remains liquid. The refrigeration system can be used to cool the near-freezing-point liquid fluid in the target area, maintaining its temperature at a target temperature close to 0°C, for example, the target temperature can be 0°C to 4°C, and is suitable for various low-temperature and refrigeration applications.

[0027] For example, the refrigeration system of this invention can be applied to a variety of scenarios, such as cold storage transportation of food, low-temperature seawater fish farming, and cold storage of food processing.

[0028] For example, the target area can be the storage area inside a storage tank, where the liquid fluid can be dairy products, beverages, or liquid condiments stored inside the tank. A refrigeration system can be used to maintain the liquid fluid inside the tank at a near-freezing temperature during storage and transportation, preserving its freshness and preventing deterioration.

[0029] Alternatively, the target area can be the interior of an aquaculture tank, in which case the liquid fluid can be aquaculture freshwater or aquaculture seawater. Or, the target area can be a food processing refrigeration area, such as the interior of a refrigerator, in which case the liquid fluid can be dairy products or liquid condiments requiring refrigeration. Or, the target area can be the water tank area of ​​a water dispenser, in which case the liquid fluid is drinking water.

[0030] See Figure 1 and Figure 2 As shown, the refrigeration system includes a refrigeration unit, a heat exchange unit, a first pressure detection unit 70, and a control unit 80. The refrigeration unit includes a compressor 10, a condenser 20, an expansion valve 30, and an evaporator 40, as well as a circulation pipe 50 connecting the compressor 10, condenser 20, expansion valve 30, and evaporator 40. The circulation pipe 50 is filled with refrigerant, which releases heat in the condenser 20 and absorbs heat in the evaporator 40. The heat exchange unit includes a heat exchange pipe 60, which connects to the target area and is also connected to the evaporator 40. The heat exchange pipe 60 is used to draw out near-freezing-point liquid fluid and allow it to enter the evaporator 40 to exchange heat with the refrigerant before returning to the target area.

[0031] The first pressure detection unit 70 is connected to the refrigerant inlet and outlet of the evaporator 40 respectively, and is used to detect the inlet and outlet pressures of the refrigerant. The control unit 80 is electrically connected to the first pressure detection unit 70, the compressor 10 and the expansion valve 30 respectively. The control unit 80 is used to control the output power of the compressor 10 or the opening degree of the expansion valve 30 according to the inlet and outlet pressures of the refrigerant, so as to control the evaporation temperature of the refrigerant within a preset range.

[0032] In this invention, the refrigerant in the refrigeration unit exchanges heat with the external environment, and then exchanges heat with the near-freezing-point liquid fluid in the heat exchange pipe 60, transferring the cooling capacity to the near-freezing-point liquid fluid. Because the near-freezing-point liquid fluid in the target area is used directly as the refrigerant, the heat exchange losses are reduced, the heat exchange efficiency of the refrigeration system is significantly improved, and problems such as increased water volume, waste of cooling capacity, changes in water quality (such as affecting the survival of living organisms), and difficulty in controlling the concentration of the medium (such as brine) caused by ice addition for temperature control are avoided, making it suitable for environmentally sensitive application scenarios.

[0033] Furthermore, by controlling the output power of the compressor 10 or the opening degree of the expansion valve 30 according to the inlet and outlet pressure of the refrigerant, the evaporation pressure can be stabilized and the evaporation temperature can be precisely controlled within a preset range. This allows for precise control of the temperature of the near-freezing liquid fluid output by the evaporator 40, ensuring that the near-freezing liquid fluid in the target area can maintain a target temperature close to the freezing point. It also effectively prevents direct freezing due to excessively low evaporation temperature, fundamentally solving the ice blockage problem and ensuring the operational reliability of the refrigeration system.

[0034] like Figure 1 As shown, the refrigeration unit includes a compressor 10, a condenser 20, an expansion valve 30, and an evaporator 40, as well as a circulation pipeline 50 filled with refrigerant. The refrigeration unit operates roughly as follows: The compressor 10 draws in low-temperature, low-pressure refrigerant gas and compresses it into a high-temperature, high-pressure gas. The high-temperature, high-pressure refrigerant gas enters the condenser 20, where it exchanges heat with the external environment (air or water), releasing heat and condensing into a high-pressure liquid. The high-pressure liquid refrigerant is then throttled and depressurized by the expansion valve 30, becoming a low-temperature, low-pressure liquid refrigerant. This low-temperature, low-pressure liquid refrigerant absorbs heat from a near-freezing-point liquid fluid in the evaporator 40, evaporating into gas. This gas is then drawn into the compressor 10, beginning a new cycle.

[0035] Optionally, the refrigerant is an azeotropic Freon. Alternatively, in other embodiments, the refrigerant may be Freon.

[0036] like Figure 1 As shown, the heat exchange unit includes a heat exchange pipe 60, which connects to the target area and the evaporator 40. Thus, near-freezing liquid fluid in the target area can enter the evaporator 40 through the heat exchange pipe 60, exchange heat with the refrigerant, and then return to the target area.

[0037] See Figure 1 In one embodiment, the heat exchange unit further includes a drive pump 90 disposed on the heat exchange pipeline 60, which is used to drive the flow of near-freezing liquid fluid. By providing the drive pump 90, the smooth circulation of near-freezing liquid fluid in the heat exchange pipeline 60 can be ensured, thus ensuring the reliable operation of the refrigeration system.

[0038] like Figure 1As shown, the first pressure detection unit 70 is used to detect the inlet and outlet pressures of the refrigerant. Optionally, the first pressure detection unit 70 includes a differential pressure detector, which is connected to the refrigerant inlet and refrigerant outlet of the evaporator 40, respectively. By setting the differential pressure detector, the detector can detect the pressure difference between the inlet and outlet sides of the refrigerant and send it to the control unit 80, so that the control unit 80 can control the output power of the compressor 10 or the opening degree of the expansion valve 30 according to the pressure difference, thereby controlling the evaporation temperature of the refrigerant within a preset range.

[0039] Alternatively, in other embodiments, the first pressure detection unit 70 may include two pressure detectors, which are respectively located at the refrigerant inlet and refrigerant outlet of the evaporator 40 and are electrically connected to the control unit 80.

[0040] refer to Figure 2 As shown, the control unit 80 is electrically connected to the first pressure detection unit 70, the compressor 10 and the expansion valve 30 respectively.

[0041] In an embodiment of the present invention, the first pressure detection unit 70 can send the inlet and outlet pressure of the refrigerant to the control unit 80. The control unit 80 can calculate the output power of the compressor 10 or the opening degree of the expansion valve 30 based on the difference between the inlet and outlet pressure of the refrigerant and the preset value, and control the compressor 10 to work at the output power or control the expansion valve 30 to work at the opening degree, thereby achieving the same inlet and outlet pressure of the refrigerant as the preset value, thereby controlling the evaporation temperature of the refrigerant to be within the preset range.

[0042] Optionally, the control unit can control the refrigerant evaporation temperature to be 2°C to 4°C lower than the target temperature. That is, the preset range can be a temperature range 2°C to 4°C lower than the target temperature, which is beneficial for maintaining the near-freezing liquid fluid at a target temperature close to the freezing point.

[0043] For example, assuming the target temperature is 0℃, the control unit can control the refrigerant evaporation temperature between -4℃ and -2℃ to help maintain the temperature of the near-freezing liquid fluid in the target area at around 0℃. Similarly, assuming the target temperature is 2℃, the control unit can control the refrigerant evaporation temperature between -2℃ and 0℃ to help maintain the temperature of the near-freezing liquid fluid in the target area at around 2℃. And again, assuming the target temperature is 3℃, the control unit can control the refrigerant evaporation temperature between -1℃ and 1℃ to help maintain the temperature of the near-freezing liquid fluid in the target area at around 3℃.

[0044] In this embodiment of the invention, utilizing the one-to-one correspondence between refrigerant (Freon) temperature and pressure, the evaporation temperature can be controlled by adjusting the Freon evaporation pressure. Thus, when a near-freezing-point liquid fluid enters the evaporator 40 and exchanges heat with the Freon, the near-freezing-point liquid fluid releases corresponding heat, ensuring that the near-freezing-point liquid fluid output from the evaporator 40 maintains a target temperature close to the freezing point. Therefore, the refrigeration system of this invention, by adjusting the refrigerant evaporation pressure, can fix the refrigerant evaporation temperature. This not only facilitates precise and rapid temperature control of the near-freezing-point liquid fluid but also fundamentally reduces the occurrence of ice blockage, preventing direct freezing due to excessively low evaporation temperatures.

[0045] See Figure 1 In one embodiment, the refrigeration system includes a temperature detector 61, which is disposed on the near-freezing point liquid fluid outlet side of the evaporator 40. The temperature detector 61 may be a temperature probe. The temperature detector 61 is primarily used to detect the real-time temperature of the near-freezing point liquid fluid output from the evaporator 40.

[0046] Temperature detector 61 is electrically connected to control unit 80 and can send the real-time temperature of the near-freezing liquid fluid to control unit 80. Control unit 80 can control the start and stop of compressor 10 based on this real-time temperature. By detecting the real-time temperature of the near-freezing liquid fluid output by evaporator 40 and controlling the start and stop of compressor 10 accordingly, the temperature control accuracy of the refrigeration system can be further guaranteed, meeting the temperature control requirements of various application scenarios.

[0047] See Figure 1 In one embodiment, the refrigeration system includes a second pressure detection unit 62, which is connected to the near-freezing point liquid fluid inlet and outlet of the evaporator 40 to detect the inlet and outlet pressures of the near-freezing point liquid fluid. A control unit 80 is electrically connected to the second pressure detection unit 62 and the drive pump 90, respectively, and the control unit 80 can control the output power of the drive pump 90 based on the inlet and outlet pressures of the near-freezing point liquid fluid.

[0048] Optionally, the second pressure detection unit 62 can be a differential pressure detector, which is connected to the near-freezing liquid fluid inlet and outlet of the evaporator 40 respectively to detect the pressure difference between the inlet and outlet of the near-freezing liquid fluid. The control unit 80 is electrically connected to the differential pressure detector and the drive pump 90 respectively, and the control unit 80 can control the output power of the drive pump 90 according to the pressure difference.

[0049] It is understood that in other embodiments, the differential pressure detector may also replace the two pressure sensors located at the near-freezing point liquid fluid inlet and outlet of the evaporator 40, which are used to detect the inlet pressure and outlet pressure of the near-freezing point liquid fluid, respectively, and are electrically connected to the control device.

[0050] In this embodiment, a second pressure detection unit 62 is provided. This unit can detect the inlet and outlet pressures of the near-freezing-point liquid fluid in the evaporator 40 and send these pressures to the control unit 80. The control unit 80 can calculate the output power of the drive pump 90 based on the difference between the near-freezing-point liquid fluid inlet and outlet pressures and a preset value, and control the drive pump 90 to operate at this output power. This ensures that the near-freezing-point liquid fluid inlet and outlet pressures are the same as the preset value, thereby maintaining a constant pressure difference between the near-freezing-point liquid fluid inlet and outlet of the evaporator 40 and preventing gradual ice blockage inside the evaporator 40.

[0051] In this embodiment, by adjusting the output power of the drive pump 90 according to the near-freezing point liquid fluid inlet and outlet pressure of the evaporator 40, a constant pressure difference is maintained, avoiding the gradual formation of ice blockage inside the evaporator 40 due to changes in water flow rate and accumulation of impurities, thus eliminating the risk of ice blockage at the process level.

[0052] See Figure 1 In one embodiment, the refrigeration system includes a flow detector 63, which is disposed on the near-freezing point liquid fluid outlet side of the evaporator 40. The flow detector 63 is used to detect the flow rate of the near-freezing point liquid fluid output from the evaporator 40. The flow detector 63 is electrically connected to the control unit 80, and can send the flow rate of the near-freezing point liquid fluid to the control unit 80, which can control the output power of the drive pump 90 based on the flow rate.

[0053] In this embodiment, by setting a flow detector 63, the flow rate of the near-freezing point liquid fluid in the evaporator 40 can be monitored in real time, and used as a basis for controlling the operation of the drive pump 90, thereby helping to ensure the reliable operation of the refrigeration system.

[0054] In this embodiment of the invention, when the refrigeration system is used in food storage and transportation tanks, the heat exchange pipelines can be connected to the evaporator and the inside of the storage and transportation tank, respectively. In this case, the refrigeration system can directly control the temperature of the transported medium inside the tank, maintain the medium's near-freezing temperature, and effectively solve the problem of zero-point freezing of the transported medium in the tank.

[0055] Of course, it is understood that the refrigeration system of the present invention can also be used in other applications. For example, when the refrigeration system is applied to water temperature control in aquaculture, the heat exchange pipes can be connected to the evaporator and the interior of the aquaculture tank, respectively. In this case, the refrigeration system can stably maintain the near-freezing water temperature in the aquaculture tank without changing the water quality or affecting the survival of the organisms, ensuring the survival rate and quality of the aquaculture, and solving the problem of environmental damage caused by traditional ice / antifreeze methods.

[0056] For example, when refrigeration systems are used in food processing (such as rapid cooling and refrigeration of milk), the heat exchange pipes can be connected to the evaporator and the interior of the refrigerator compartment of the refrigeration unit, respectively. In this case, the refrigeration system can directly and efficiently control the temperature of the liquid stored inside the refrigerator compartment, avoiding the loss of cold energy caused by secondary heat exchange, improving rapid cooling efficiency, ensuring food freshness, and reducing the company's energy costs.

[0057] Alternatively, the refrigeration system can be applied to other scenarios, such as laboratories and special cooling fields that require near-freezing temperature control, adapting to the "no buffering, high precision" requirements and filling the gaps in traditional technologies.

[0058] See Figure 3 An embodiment of the present invention also provides a control method for a refrigeration system as described in any of the above embodiments, comprising: S10, acquire the inlet and outlet pressures of the refrigerant in the evaporator 40. For example, the pressure difference between the inlet and outlet sides of the refrigerant in the evaporator 40 can be detected by a differential pressure detector. The differential pressure detector can send the detected pressure difference between the inlet and outlet sides of the refrigerant to the control unit 80.

[0059] S20 adjusts the output power of compressor 10 or the opening of expansion valve 30 according to the inlet and outlet pressures to control the evaporation temperature of refrigerant in evaporator 40 to be 2°C to 4°C lower than the target temperature of near-freezing liquid fluid.

[0060] For example, the control unit 80 can receive the pressure difference between the inlet and outlet sides of the refrigerant detected by the differential pressure detector, and can control the output power of the compressor 10 or the opening degree of the expansion valve 30 according to the pressure difference, so as to control the evaporation temperature of the refrigerant within a preset range. For example, the preset range can be a temperature range that is 2°C to 4°C lower than the target temperature of the near-freezing liquid fluid. This not only helps to ensure that the near-freezing liquid fluid output by the evaporator 40 can maintain a temperature close to the freezing point, but also fundamentally reduces the occurrence of ice blockage and avoids direct freezing due to excessively low evaporation temperature.

[0061] Optionally, the control method further includes S30, obtaining the inlet and outlet pressures of the near-freezing liquid fluid of the evaporator 40, and controlling the output power of the drive pump 90 based on the inlet and outlet pressures of the near-freezing liquid fluid.

[0062] For example, a differential pressure detector can be used to detect the pressure difference between the inlet and outlet of the near-freezing liquid fluid in the evaporator 40. The differential pressure detector can send the detected pressure difference between the inlet and outlet of the near-freezing liquid fluid to the control unit 80. The control unit 80 can then control the output power of the drive pump 90, thereby helping to maintain a constant pressure difference between the inlet and outlet of the near-freezing liquid fluid in the evaporator 40 and preventing gradual ice blockage inside the evaporator 40.

[0063] In the refrigeration system of this invention, the refrigerant in the refrigeration unit exchanges heat with the external environment, and then exchanges heat with a near-freezing-point liquid fluid in the heat exchange pipeline, transferring the cooling capacity to the near-freezing-point liquid fluid. Because the near-freezing-point liquid fluid in the target area is used directly as the refrigerant, heat exchange losses are reduced, significantly improving the heat exchange efficiency of the refrigeration system. This avoids problems such as increased water volume, wasted cooling capacity, changes in water quality (e.g., affecting the survival of living organisms), and difficulty in controlling the concentration of the medium (e.g., brine) caused by ice-based temperature control, making it suitable for environmentally sensitive application scenarios.

[0064] Furthermore, by controlling the compressor's output power or the expansion valve opening based on the refrigerant's inlet and outlet pressures, the evaporation pressure can be stabilized, and the evaporation temperature can be precisely controlled within a preset range. This allows for precise control of the temperature of the near-freezing liquid fluid output by the evaporator, ensuring that the near-freezing liquid fluid in the target area remains at a near-freezing temperature. It also effectively prevents direct freezing due to excessively low evaporation temperatures, fundamentally solving the ice blockage problem and ensuring the reliability of the refrigeration system.

[0065] The refrigeration system of this invention uses a near-freezing-point liquid fluid in the target area as the refrigerant, eliminating the need for a secondary heat exchange stage, improving heat exchange efficiency, and reducing heat exchange losses. It also effectively avoids equipment downtime and maintenance caused by ice blockage, reducing maintenance costs and production interruption losses.

[0066] The refrigeration system of this invention achieves high-precision control of near-freezing water temperature from 0℃ to 4℃, specifically for scenarios with "no secondary heat exchange / cold storage buffer and harsh evaporation conditions" (such as low-temperature seawater fish farming, rapid milk cooling, and refrigerated liquid transportation). By detecting the refrigerant inlet and outlet pressures and the near-freezing liquid fluid inlet and outlet pressures of the evaporator, automated and precise temperature control is achieved using dual-pressure closed-loop control. This eliminates the need for frequent manual adjustments to antifreeze concentration or ice addition, reducing labor costs and minimizing the risk of operational errors.

[0067] The refrigeration system of this invention, as a dedicated temperature control solution for "near freezing point, no buffer, and deteriorating operating conditions", fills the gap in the industry for "efficient anti-ice blockage" technology and has significant performance advantages compared with traditional methods such as ice injection and antifreeze heat exchange.

[0068] The above embodiments are merely illustrative examples of structures. The structures in each embodiment are not fixed combinations. In the absence of structural conflicts, the structures in multiple embodiments can be arbitrarily combined and used.

[0069] Although the invention has been described with reference to several typical embodiments, it should be understood that the terminology used is illustrative and exemplary, and not restrictive. Since the invention can be embodied in many forms without departing from the spirit or essence of the invention, it should be understood that the above embodiments are not limited to any of the foregoing details, but should be interpreted broadly within the spirit and scope defined by the appended claims. Therefore, all variations and modifications falling within the scope of the claims or their equivalents should be covered by the appended claims.

Claims

1. A refrigeration system for maintaining the temperature of a near-freezing-point liquid fluid within a target area at a target temperature, characterized in that, include: A refrigeration unit includes a compressor, a condenser, an expansion valve, and an evaporator, as well as a circulation pipeline connecting the compressor, the condenser, the expansion valve, and the evaporator. The circulation pipeline is filled with refrigerant, which releases heat in the condenser and absorbs heat in the evaporator. A heat exchange unit includes a heat exchange pipeline connected to the target area and the evaporator. The heat exchange pipeline is used to draw out the near-freezing point liquid fluid and allow the near-freezing point liquid fluid to enter the evaporator to exchange heat with the refrigerant before returning to the target area. The first pressure detection unit is connected to the refrigerant inlet and outlet of the evaporator respectively, and is used to detect the inlet and outlet pressure of the refrigerant; The control unit is electrically connected to the first pressure detection unit, the compressor, and the expansion valve respectively. The control unit is used to control the output power of the compressor or the opening degree of the expansion valve according to the inlet and outlet pressure of the refrigerant, so as to control the evaporation temperature of the refrigerant within a preset range.

2. The refrigeration system according to claim 1, characterized in that, The control unit can control the evaporation temperature of the refrigerant to be 2°C to 4°C lower than the target temperature.

3. The refrigeration system according to claim 1, characterized in that, The refrigerant used is Freon.

4. The refrigeration system according to claim 1, characterized in that, The refrigerant used is azeotropic Freon.

5. The refrigeration system according to claim 1, characterized in that, Includes a temperature detector, which is disposed on the near-freezing point liquid fluid outlet side of the evaporator, and the temperature detector is used to detect the real-time temperature of the near-freezing point liquid fluid output by the evaporator; The temperature detector is electrically connected to the control unit, which can control the start and stop of the compressor based on the real-time temperature.

6. The refrigeration system according to claim 1, characterized in that, It includes a second pressure detection unit, which is connected to the near-freezing point liquid fluid inlet and outlet of the evaporator respectively, to detect the inlet and outlet pressure of the near-freezing point liquid fluid; The heat exchange unit also includes a drive pump, which is disposed on the heat exchange pipeline and is used to drive the flow of the near-freezing liquid fluid; The control unit is electrically connected to the second pressure detection unit and the drive pump respectively. The control unit can control the output power of the drive pump according to the inlet and outlet pressure of the near-freezing liquid fluid.

7. The refrigeration system according to claim 6, characterized in that, Includes a flow detector, which is disposed on the near-freezing point liquid fluid outlet side of the evaporator, and the flow detector is used to detect the flow rate of the near-freezing point liquid fluid output by the evaporator; The flow detector is electrically connected to the control unit, and the control unit can control the output power of the drive pump based on the flow rate.

8. The refrigeration system according to claim 1, characterized in that, The first pressure detection unit includes a differential pressure detector, which is connected to the refrigerant inlet and refrigerant outlet of the evaporator, respectively.

9. The refrigeration system according to claim 1, characterized in that, The target area is the interior of the storage tank, and the heat exchange pipelines are connected to both the evaporator and the interior of the tank; or The target area is the interior of the refrigerator compartment of the refrigeration unit, and the heat exchange pipes are connected to the evaporator and the interior of the refrigerator compartment, respectively; or The target area is the inside of the aquaculture tank, and the heat exchange pipeline is connected to the evaporator and the inside of the tank, respectively.

10. A control method for a refrigeration system as described in any one of claims 1-9, characterized in that, include: Obtain the inlet and outlet pressures of the refrigerant in the evaporator; Adjust the compressor's output power or the expansion valve opening according to the inlet and outlet pressures to control the refrigerant evaporation temperature in the evaporator to be 2°C to 4°C lower than the target temperature of the near-freezing liquid fluid.

11. The control method according to claim 10, characterized in that, include: Obtain the inlet and outlet pressures of the near-freezing liquid fluid in the evaporator; The output power of the drive pump is controlled based on the inlet and outlet pressures of the near-freezing liquid fluid.

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