Refrigerating unit and control method thereof, refrigeration house refrigeration equipment and storage medium

Abstract

The invention discloses a refrigerating unit and a control method thereof, refrigeration house refrigerating equipment and a storage medium. The refrigerating unit comprises a main evaporator, a compressor, an oil separator, a condenser and an auxiliary evaporator which are connected, and the auxiliary evaporator is arranged on a pipeline between an air suction port of the compressor and an air return port of the main evaporator. The first end of the branch is arranged on the pipeline between the auxiliary evaporator and the main evaporator, and the second end of the branch is arranged on the pipeline between the condenser and the evaporator; the first electromagnetic valve is arranged on the branch; and the second electromagnetic valve is arranged on a pipeline between the second end of the branch and the evaporator. According to the refrigerating unit, the auxiliary evaporator is additionally arranged, return air of the main evaporator can be heated when a refrigeration house is cooled normally, and the suction superheat degree of the main evaporator is reduced; and when the load of the compressor is close to the minimum load, the main evaporator liquid supply valve is closed. An auxiliary evaporator control valve is opened to exchange heat with outdoor air, and long-term operation of the compressor is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of refrigeration units, and in particular to a refrigeration unit and a control method thereof, cold storage refrigeration equipment, and a storage medium. Background Art

[0002] The heat load of the cold storage includes four parts: wall heat transfer, cargo heat, motor heat and operating heat. The design and selection are configured according to this load. However, when the cold storage is not stocked and there are no operators, the heat load of the cold storage becomes smaller. When the load is very small, the unit will quickly unload and shut down. If the insulation effect of the cold storage is not good and the temperature returns quickly, the unit will start again. Frequent start and stop of the unit will increase the power consumption of the unit and even cause reliability problems such as oil leakage. The cold storage evaporator adopts a dry evaporator, and the evaporator liquid supply electronic expansion valve adopts superheat control. In order to ensure that the suction does not carry liquid, the evaporator outlet requires a certain superheat, and the cold storage evaporator cannot fully exchange heat. This will result in limited low-load adjustment capacity of the refrigeration unit and inability to operate at low load for a long time.

[0003] With regard to the problem of limited low-load regulation capability of refrigeration units in the prior art, no effective solution has been proposed yet. Summary of the invention

[0004] The embodiments of the present invention provide a refrigeration unit and a control method thereof, a cold storage refrigeration device, and a storage medium to solve the problem of limited low-load regulation capability of the refrigeration unit in the prior art.

[0005] To solve the above technical problems, the present invention provides a refrigeration unit, wherein the refrigeration unit includes: a main evaporator, a compressor, an oil separator and a condenser connected to each other, and an electronic expansion valve is arranged on the pipeline between the condenser and the evaporator; the refrigeration unit also includes: an auxiliary evaporator, which is arranged on the pipeline between the air intake port of the compressor and the air return port of the main evaporator; a branch, a first end of which is arranged on the pipeline between the auxiliary evaporator and the main evaporator, and a second end of which is arranged on the pipeline between the condenser and the evaporator; a first solenoid valve, which is arranged on the branch; and a second solenoid valve, which is arranged on the pipeline between the second end of the branch and the evaporator.

[0006] Furthermore, the refrigeration unit further comprises: a thermal expansion valve, which is arranged on the pipeline between the auxiliary evaporator and the first end of the branch.

[0007] The present invention provides a cold storage refrigeration equipment, characterized in that the cold storage refrigeration equipment comprises: the above-mentioned refrigeration unit.

[0008] The present invention provides a control method for a refrigeration unit, which is applied to the above-mentioned refrigeration unit, wherein the method includes: determining a minimum load current according to an evaporation temperature and a condensation temperature of the unit; comparing the actual operating current of the compressor with the magnitude of the minimum load current; and controlling the opening and closing of a first solenoid valve and a second solenoid valve of the refrigeration unit according to the comparison result.

[0009] Furthermore, the minimum load current is determined according to the evaporation temperature and the condensation temperature of the unit, including: determining the minimum load current corresponding to the evaporation temperature and the condensation temperature according to a preset mapping relationship.

[0010] Further, controlling the opening and closing of the first solenoid valve and the second solenoid valve of the refrigeration unit according to the comparison result includes:

[0011] If the actual operating current of the compressor is greater than or equal to the minimum load current, the first solenoid valve is controlled to be closed and the second solenoid valve is controlled to be opened;

[0012] If 0≤the actual operating current of the compressor<the minimum load current, the first solenoid valve is controlled to be opened and the second solenoid valve is controlled to be closed.

[0013] Furthermore, if the actual operating current of the compressor is ≥ the minimum load current, the first solenoid valve is controlled to be closed and the second solenoid valve is opened. The method also includes: determining the suction superheat of the unit; and adjusting the opening of the electronic expansion valve according to the suction superheat.

[0014] Further, determining the suction superheat of the unit includes: detecting the suction temperature of the suction port of the compressor, detecting the evaporation temperature of the suction port of the evaporator; calculating the suction superheat according to the following formula: the suction superheat = the suction temperature - the evaporation temperature.

[0015] Further, adjusting the opening of the electronic expansion valve according to the suction superheat comprises:

[0016] Calculate the opening change ΔUk according to the following formula;

[0017] ΔUk=K p (e k -e k-1 )+K i e k +K d (e k -2e k-1 +e k-2 );

[0018] Among them, K p is the proportional coefficient, Ki is the integral time constant, Kd is the differential time constant, k is the sampling period, e k is the suction superheat of the current sampling period, ek-1 is the suction superheat of the previous sampling cycle, e k-2 is the suction superheat of the first two sampling cycles;

[0019] The opening degree of the electronic expansion valve is adjusted according to the opening degree change.

[0020] The present invention provides a computer-readable storage medium having a computer program stored thereon, wherein the program implements the above method when executed by a processor.

[0021] The present invention provides an electronic device, which includes: one or more processors; a storage device for storing one or more programs, when the one or more programs are executed by the one or more processors, the one or more processors implement the method as described above.

[0022] The technical solution of the present invention is applied, and the evaporator of the refrigeration unit is connected in series, and an auxiliary evaporator is added. The auxiliary evaporator is located between the main evaporator and the air intake of the compressor. The auxiliary evaporator can play two roles: when the cold storage is cooled down normally, the return air of the main evaporator is heated to reduce the suction superheat of the main evaporator; when the compressor load is close to the minimum load, the main evaporator liquid supply valve is closed. The auxiliary evaporator control valve is opened to exchange heat with the outdoor air to ensure the long-term operation of the compressor. It can solve the problem that the low-load regulation capacity of the refrigeration unit is limited and it cannot operate at a small load for a long time. It can also solve the problem that the dry evaporator of the cold storage needs to ensure the superheat and cannot fully exchange heat, making the unit more energy-efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic structural diagram of a refrigeration unit according to an embodiment of the present invention;

[0024] Figure 2 is a flow chart of a control method for a refrigeration unit according to an embodiment of the present invention;

[0025] Figure 3 It is a flow chart of cold storage refrigeration control according to an embodiment of the present invention. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "said" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings, and "multiple" generally includes at least two.

[0028] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0029] It should be understood that although the terms first and second may be used to describe the solenoid valve in the embodiments of the present invention, these should not be limited to these terms. These terms are only used to distinguish the solenoid valves. For example, without departing from the scope of the embodiments of the present invention, the first solenoid valve may also be referred to as the second solenoid valve, and similarly, the second solenoid valve may also be referred to as the first solenoid valve.

[0030] As used herein, the words "if" and "if" may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to determining" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)", depending on the context.

[0031] It should also be noted that the term "includes", "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, so that a commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprising a ..." do not exclude the existence of other identical elements in the commodity or device including the elements.

[0032] The optional embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0033] Example 1

[0034] This embodiment adopts the cold storage evaporator series connection mode, and adds an auxiliary evaporator, which is located between the main evaporator of the unit and the air intake of the compressor. The auxiliary evaporator can play two roles: first, when the refrigeration unit of the cold storage is cooled normally, the return air of the main evaporator is heated to reduce the suction superheat of the main evaporator; second, when the compressor load is close to the minimum load, the liquid supply valve of the main evaporator is closed, and the auxiliary evaporator control valve is opened to exchange heat with the outdoor air to ensure the long-term operation of the compressor. The structure of the refrigeration unit is introduced in detail below.

[0035] Figure 1 is a schematic diagram of the structure of a refrigeration unit according to an embodiment of the present invention. Figure 1 As shown, the refrigeration unit includes: a main evaporator, a compressor, an oil separator and a condenser connected to each other, and an electronic expansion valve is arranged on the pipeline between the condenser and the evaporator. The refrigeration unit also includes: an auxiliary evaporator, which is arranged on the pipeline between the air intake of the compressor and the air return port of the main evaporator. In this embodiment, on the basis of the auxiliary evaporator connected in series, a branch is also arranged, the first end of the branch is arranged on the pipeline between the auxiliary evaporator and the main evaporator, and the second end of the branch is arranged on the pipeline between the condenser and the evaporator. The first solenoid valve (solenoid valve 1) is arranged on the above-mentioned branch; the second solenoid valve (solenoid valve 2) is arranged on the pipeline between the second end of the above-mentioned branch and the evaporator. The thermal expansion valve is arranged on the pipeline between the auxiliary evaporator and the first end of the branch. A pressure sensor and a temperature sensor are arranged at the air intake of the compressor.

[0036] Compared with the refrigeration unit of the conventional cold storage, an auxiliary evaporator, a thermal expansion valve, and a first solenoid valve are newly added. The return air port of the evaporator is directly connected to the air intake port of the compressor. The opening of the main electronic expansion valve is controlled by the suction superheat detected and calculated by the temperature sensor and pressure sensor set at the air intake port of the compressor. The refrigeration unit provided in this embodiment can solve the technical problem that the low-load regulation capacity of the refrigeration unit is limited and it cannot operate at a small load for a long time. It can also solve the problem that the dry evaporator of the cold storage needs to ensure the superheat and cannot fully exchange heat, making the unit more energy-efficient.

[0037] This embodiment also provides a cold storage refrigeration equipment, which includes the refrigeration unit introduced above.

[0038] Example 2

[0039] According to an embodiment of the present invention, an embodiment of a control method for a refrigeration unit is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0040] Figure 2 is a flow chart of a control method for a refrigeration unit according to an embodiment of the present invention. Figure 2 As shown, the method comprises the following steps:

[0041] Step S201, determining the minimum load current according to the evaporation temperature and condensation temperature of the unit;

[0042] Step S202, comparing the actual operating current of the compressor with the minimum load current;

[0043] Step S203, controlling the opening and closing of the first solenoid valve and the second solenoid valve of the refrigeration unit according to the comparison result.

[0044] This embodiment adopts the refrigeration unit evaporator series connection mode, and adds an auxiliary evaporator, which is located between the main evaporator and the suction port of the compressor. The auxiliary evaporator can play two roles: when the cold storage is cooled down normally, the return air of the main evaporator is heated to reduce the suction superheat of the main evaporator; when the compressor load is close to the minimum load, the main evaporator liquid supply valve is closed. The auxiliary evaporator control valve is opened to exchange heat with the outdoor air to ensure the long-term operation of the compressor. It can solve the problem that the low-load regulation capacity of the refrigeration unit is limited and it cannot operate at a small load for a long time. It can also solve the problem that the dry evaporator in the cold storage needs to ensure the superheat and cannot fully exchange heat, making the unit more energy-efficient.

[0045] After detecting the evaporation temperature and condensation temperature of the unit, this embodiment determines the minimum load current according to the evaporation temperature and condensation temperature of the unit. Specifically, the preset mapping relationship between the evaporation temperature, condensation temperature and minimum load current can be set according to the historical operation data or the different requirements of the unit. For example, when the evaporation temperature is -28°C and the condensation temperature is 35°C, the current value of the minimum load of the unit is 33A; when the evaporation temperature is -28°C and the condensation temperature is 30°C, the current value of the minimum load of the unit is 31A. Based on this, a reasonable preset mapping relationship can be set, and the minimum load current corresponding to the evaporation temperature and the condensation temperature can be determined according to the preset mapping relationship. Based on this, a more reasonable minimum load current can be determined according to the current working condition of the unit, which serves as the basis for the subsequent control of the refrigerant flow path of the refrigeration unit.

[0046] After determining the minimum load current corresponding to the current working condition, the actual operating current of the compressor and the minimum load current are compared, and the opening and closing of the first solenoid valve and the second solenoid valve of the refrigeration unit are controlled according to the comparison result. Specifically, it can be achieved through the following preferred implementations:

[0047] (1) If the actual operating current of the compressor is ≥ the minimum load current, the first solenoid valve is controlled to close and the second solenoid valve is controlled to open.

[0048] Based on the above control operation, the refrigeration process of the unit is as follows: the refrigerant vapor enters the condenser from the compressor exhaust, the liquid condensed by the condenser enters the evaporator after throttling by the main electronic expansion valve, absorbs the heat of the air outside the tube and evaporates in the evaporator, the formed gas-liquid mixture enters the thermal expansion valve, and enters the auxiliary evaporator after further throttling, the refrigerant liquid in the auxiliary evaporator exchanges heat with the air outside the tube, and the refrigerant gas after absorbing heat enters the compressor suction port to enter the next refrigeration cycle.

[0049] On the basis of the above control operation, the opening of the electronic expansion valve of the unit is further adaptively adjusted. Specifically, the suction superheat of the unit is determined; and the opening of the electronic expansion valve is adjusted according to the suction superheat.

[0050] When determining the suction superheat of the unit, the suction temperature of the suction port of the compressor is detected, the evaporation temperature of the suction port of the evaporator is detected, and the suction superheat is calculated according to the following formula: suction superheat = suction temperature - evaporation temperature. Based on this, a more accurate suction superheat can be obtained, thereby realizing accurate control of the electronic expansion valve based on the current refrigerant flow path.

[0051] When adjusting the opening of the electronic expansion valve according to the suction superheat, the opening change ΔUk is calculated according to the following formula, in %, for example: regulating valve opening ΔUk=35%. Then the opening of the electronic expansion valve is adjusted according to the opening change.

[0052] ΔUk=K p (e k -e k-1 )+K i e k +K d (e k -2e k-1 +e k-2 );

[0053] Among them, K p is the proportional coefficient, Ki is the integral time constant, Kd is the differential time constant, k is the sampling period, e k is the suction superheat of the current sampling period, e k-1 is the suction superheat of the previous sampling cycle, e k-2 It is the suction superheat of the first two sampling cycles.

[0054] (2) If 0≤actual operating current of the compressor<minimum load current, the first solenoid valve is controlled to open and the second solenoid valve is controlled to close.

[0055] Based on the above control operation, the refrigeration process of the unit is as follows: the refrigerant vapor enters the condenser from the exhaust gas, and the condensed liquid enters the auxiliary evaporator after being throttled by the thermal expansion valve, and in the auxiliary evaporator, it absorbs the heat of the air outside the tube and evaporates to form refrigerant vapor, which enters the compressor suction port and enters the next refrigeration cycle.

[0056] Example 3

[0057] Figure 3 is a cold storage refrigeration control flow chart according to an embodiment of the present invention, such as Figure 3 As shown, the process includes the following steps:

[0058] Step 1: The minimum load current value A of the computer group at different evaporating temperatures and condensing temperatures is the smallest. For example, when the evaporating temperature is -28°C and the condensing temperature is 35°C, the current value of the minimum load of the unit is 33A; when the evaporating temperature is -28°C and the condensing temperature is 30°C, the minimum load current is 31A.

[0059] Step 2: When the compressor is actually running, the average current detected is A.

[0060] When it is detected that the actual operating current A of the compressor is greater than or equal to the minimum load current value, that is:

[0061] A≤A 最小 ;

[0062] Component action: Solenoid valve 1 is closed, solenoid valve 2 is opened;

[0063] Refrigeration process: Refrigerant vapor enters the condenser from the exhaust gas of the compressor. The liquid condensed by the condenser enters the evaporator after throttling by the main electronic expansion valve. In the evaporator, it absorbs the heat of the air outside the tube and evaporates. The formed gas-liquid mixture enters the thermal expansion valve and enters the auxiliary evaporator after further throttling. The refrigerant liquid in the auxiliary evaporator exchanges heat with the air outside the tube. The refrigerant gas after absorbing heat enters the suction port of the compressor and enters the next refrigeration cycle.

[0064] At this time, the opening of the electronic expansion valve is controlled as follows:

[0065] The unit's suction superheat is measured according to the suction port pressure sensor and temperature sensor. Suction superheat SH = suction temperature - evaporation temperature.

[0066] When adjusting the opening of the electronic expansion valve according to the suction superheat, the opening change ΔUk is calculated according to the following formula, in %, for example: regulating valve opening ΔUk=35%. Then the opening of the electronic expansion valve is adjusted according to the opening change.

[0067] ΔUk=K p (e k -e k-1)+K i e k +K d (e k -2e k-1 +e k-2 );

[0068] Among them, K p is the proportional coefficient, Ki is the integral time constant, Kd is the differential time constant, k is the sampling period, e k is the suction superheat of the current sampling period, e k-1 is the suction superheat of the previous sampling cycle, e k-2 It is the suction superheat of the first two sampling cycles.

[0069] Step 3: When it is detected that the actual operating current A of the compressor is less than the minimum load current value, that is, 0≤A<A 最小 ;

[0070] Component action: Solenoid valve 1 opens, solenoid valve 2 closes.

[0071] Refrigeration process: At this time, the refrigerant vapor enters the condenser from the exhaust gas, and the condensed liquid enters the auxiliary evaporator after being throttled by the thermal expansion valve. In the auxiliary evaporator, the heat of the air outside the absorption tube evaporates to form refrigerant vapor, which enters the compressor suction port and enters the next refrigeration cycle.

[0072] Example 4

[0073] This embodiment provides an electronic device, which is used in a control method for a refrigeration unit. The electronic device includes: at least one processor; and a memory connected to the at least one processor in communication; wherein:

[0074] The memory stores instructions that can be executed by the one processor, and the instructions are executed by the at least one processor so that the at least one processor can: determine the minimum load current based on the evaporation temperature and condensation temperature of the unit; compare the actual operating current of the compressor and the minimum load current; and control the opening and closing of the first solenoid valve and the second solenoid valve of the refrigeration unit based on the comparison result.

[0075] Example 5

[0076] The embodiment of the present invention provides a software, which is used to execute the technical solutions described in the above embodiment and preferred implementation manner.

[0077] An embodiment of the present invention provides a non-volatile computer storage medium, wherein the computer storage medium stores computer executable instructions, and the computer executable instructions can execute the control method of the refrigeration unit in any of the above method embodiments.

[0078] The above-mentioned software is stored in the above-mentioned storage medium, which includes but is not limited to: a CD, a floppy disk, a hard disk, an erasable memory, etc.

[0079] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0080] In the above embodiments of the present invention, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0081] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the device embodiments described above are only schematic. For example, the division of the units can be a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, which can be electrical or other forms.

[0082] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple units. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0083] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0084] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), mobile hard disk, magnetic disk or optical disk and other media that can store program codes.

[0085] The above product can execute the method provided by the embodiment of the present invention, and has the functional modules and beneficial effects corresponding to the execution method. For technical details not described in detail in this embodiment, please refer to the method provided by the embodiment of the present invention.

[0086] The electronic devices of the embodiments of the present invention exist in various forms, including but not limited to:

[0087] (1) Mobile communication devices: These devices are characterized by their mobile communication functions and their main purpose is to provide voice and data communications. These terminals include: smart phones (such as iPhone), multimedia phones, functional phones, and low-end phones.

[0088] (2) Ultra-mobile personal computer devices: These devices fall into the category of personal computers, have computing and processing capabilities, and generally also have mobile Internet access features. These terminals include: PDA, MID and UMPC devices, such as iPad.

[0089] (3) Portable entertainment devices: These devices can display and play multimedia content. They include audio and video players (such as iPods), handheld game consoles, e-books, as well as smart toys and portable car navigation devices.

[0090] (4) Server: A device that provides computing services. The server consists of a processor, hard disk, memory, device bus, etc. The server is similar to the general computer architecture, but because it needs to provide highly reliable services, it has higher requirements in terms of processing power, stability, reliability, security, scalability, manageability, etc.

[0091] (5) Other electronic devices with data interaction functions, such as televisions, large-screen cars, etc.

[0092] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A refrigeration unit, characterized in that: The refrigeration unit comprises: a main evaporator, a compressor, an oil separator and a condenser connected to each other, and an electronic expansion valve is arranged on the pipeline between the condenser and the evaporator; the refrigeration unit also comprises: An auxiliary evaporator is arranged on a pipeline between the air intake port of the compressor and the air return port of the main evaporator; a branch, a first end of which is arranged on the pipeline between the auxiliary evaporator and the main evaporator, and a second end of which is arranged on the pipeline between the condenser and the evaporator; A first solenoid valve is arranged on the branch line; A second solenoid valve is arranged on the pipeline between the second end of the branch and the evaporator.

2. The refrigeration unit according to claim 1, characterized in that: The refrigeration unit also includes: A thermal expansion valve is arranged on the pipeline between the auxiliary evaporator and the first end of the branch.

3. A cold storage refrigeration equipment, characterized in that: The cold storage refrigeration equipment comprises: the refrigeration unit according to claim 1 or 2.

4. A control method for a refrigeration unit, applied to the refrigeration unit according to claim 1 or 2, characterized in that: The method comprises: Determine the minimum load current based on the evaporation temperature and condensation temperature of the unit; Comparing the actual operating current of the compressor with the minimum load current; The opening and closing of the first solenoid valve and the second solenoid valve of the refrigeration unit are controlled according to the comparison result.

5. The refrigeration unit according to claim 4, characterized in that: Determine the minimum load current based on the unit's evaporation temperature and condensation temperature, including: According to the preset mapping relationship, the minimum load current corresponding to the evaporation temperature and the condensation temperature is determined.

6. The refrigeration unit according to claim 4, characterized in that: Controlling the opening and closing of the first solenoid valve and the second solenoid valve of the refrigeration unit according to the comparison result includes: If the actual operating current of the compressor is greater than or equal to the minimum load current, the first solenoid valve is controlled to be closed and the second solenoid valve is controlled to be opened; If 0≤the actual operating current of the compressor<the minimum load current, the first solenoid valve is controlled to be opened and the second solenoid valve is controlled to be closed.

7. The refrigeration unit according to claim 6, characterized in that: If the actual operating current of the compressor is greater than or equal to the minimum load current, the first solenoid valve is controlled to be closed and the second solenoid valve is controlled to be opened, and the method further comprises: Determine the unit's suction superheat; The opening degree of the electronic expansion valve is adjusted according to the suction air superheat.

8. The refrigeration unit according to claim 7, characterized in that: Determine the unit's suction superheat, including: Detect the suction temperature of the compressor suction port and the evaporation temperature of the evaporator suction port; The suction gas superheat is calculated according to the following formula: the suction gas superheat=the suction gas temperature-the evaporation temperature.

9. The refrigeration unit according to claim 7, characterized in that: Adjusting the opening of the electronic expansion valve according to the suction superheat includes: Calculate the opening change ΔUk according to the following formula; ΔUk=K p (is k -is k-1 )+K i is k +K d (is k 2e k-1 +e k-2 ): Among them, K p is the proportional coefficient, Ki is the integral time constant, Kd is the differential time constant, k is the sampling period, e k is the suction superheat of the current sampling period, e k-1 is the suction superheat of the previous sampling cycle, e k-2 is the suction superheat of the first two sampling cycles; The opening degree of the electronic expansion valve is adjusted according to the opening degree change.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the method according to any one of claims 4 to 9 is implemented.

11. An electronic device, characterized in that: include: one or more processors; A storage device for storing one or more programs, which, when executed by the one or more processors, enables the one or more processors to implement the method as claimed in any one of claims 4 to 9.

Images