Refrigerating system and refrigeration house

Abstract

The refrigerating system comprises a refrigerating circulation loop and a switching assembly, the refrigerating circulation loop comprises a compressor, a condenser and an evaporation assembly which are sequentially connected in series, and the evaporation assembly comprises at least two evaporation branches which are connected in parallel; each evaporation branch comprises a throttling element, an evaporator and an air return unit which are sequentially connected in series, and each air return unit comprises an air return valve and a bypass valve which are connected in parallel; the switching assembly is connected with the refrigeration circulation loop and has a closed state and an open state; in the process that the refrigerating system is switched from the defrosting mode to the refrigerating mode, the air return valve and the bypass valve of the original target evaporation branch are firstly opened, and then the bypass valve of the original target evaporation branch is closed. In the process that defrosting of a part of the evaporators is finished and the flowing path of the refrigerant is switched, the risk that the compressor of the refrigerating system is damaged is low.

Description

Technical Field

[0001] The present invention relates to the field of refrigeration technology, and in particular to a refrigeration system, a cold storage, and a control method for the refrigeration system. Background Art

[0002] The refrigeration systems of cold storage facilities or some low-temperature equipment require extended cooling cycles, and the evaporator temperature often remains below 0°C, causing moisture in the air to form frost on the evaporator surface. Frost on the evaporator surface interferes with heat exchange between the refrigerant inside the evaporator and the air outside, thus affecting cooling efficiency. Therefore, defrosting the evaporator after frost has formed is necessary. A common defrosting method involves changing the refrigerant's flow path within the refrigeration system, allowing high-temperature, high-pressure refrigerant to enter the evaporator. The heat released by the high-temperature, high-pressure refrigerant melts the frost on the evaporator's outer surface.

[0003] To minimize the impact on cooling efficiency during defrosting, some existing technologies defrost a portion of the evaporators while maintaining cooling on other evaporators, rather than defrosting all evaporators simultaneously. After defrosting a portion of the evaporators, the refrigerant flow path within the refrigeration system needs to be rerouted, for example by switching the system from defrost mode back to cooling mode or by switching the evaporator to defrost. However, during the process of defrosting a portion of the evaporators and switching the refrigerant flow path, the compressor is susceptible to damage. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a refrigeration system in which the risk of damage to the compressor of the refrigeration system is low during the process of defrosting a portion of the evaporators and switching the flow path of the refrigerant.

[0005] The present invention also provides a cold storage comprising the above refrigeration system.

[0006] According to the first aspect of the present invention, the refrigeration system includes: a refrigeration cycle circuit, including a compressor, a condenser and an evaporation component connected in series in sequence, the evaporation component includes at least two evaporation branches connected in parallel, each of the evaporation branches includes a throttling element, an evaporator and a return air unit connected in series in sequence, and the return air unit includes a return air valve and a bypass valve connected in parallel; a switching component, the switching component is connected to the refrigeration cycle circuit, and the switching component has a closed state and an open state; when the refrigeration system is in a refrigeration mode, the switching component is in a closed state, the return air valve is opened, and the bypass valve is closed, the compressor drives the refrigerant to circulate along the refrigeration cycle circuit, and makes the refrigerant flow through the compressor, the condenser, and each of the evaporation branches in sequence; when the refrigeration system is in a defrost mode, the switching component is in an open state, the target evaporation branch The return valve and the bypass valve are closed, the return valve of the non-target evaporation branch is opened, and the bypass valve of the non-target evaporation branch is closed. The compressor drives the refrigerant to flow in a cycle, and makes the refrigerant flow through the compressor, the target evaporator and the non-target evaporation branch in sequence. The refrigerant condenses in the target evaporator and evaporates in the non-target evaporator; wherein, the target evaporator is the evaporator that currently needs to be defrosted, and the remaining evaporators except the target evaporator are non-target evaporators, the evaporation branch where the target evaporator is located is the target evaporation branch, and the remaining evaporation branches except the target evaporation branch are non-target evaporation branches; in the process of the refrigeration system switching from the defrost mode to the refrigeration mode, the return valve and the bypass valve of the original target evaporation branch are opened first, and then the bypass valve of the original target evaporation branch is closed.

[0007] The refrigeration system of the embodiment of the present invention has at least the following beneficial effects: in the process of switching to the refrigeration mode, the return valve and the bypass valve of the original target evaporation branch are first opened at the same time. At this time, part of the high-pressure refrigerant will flow through the return valve, and the other part of the refrigerant will be diverted to the pipeline where the bypass valve is located. Since the refrigerant is diverted to the two valves, the pressure of the refrigerant flowing through the return valve and the refrigerant flowing through the bypass valve is relatively low. In addition, when the fluid flows through the return unit, it will first be diverted to the return valve and the bypass valve, and then merge. In the process of diversion and merging, the fluid will produce pressure loss. Therefore, the pressure of the refrigerant that finally merges and flows to the compressor is relatively low, which helps to reduce the risk of damage to the compressor. In the process of switching from the defrost mode to the refrigeration mode, this embodiment helps to reduce the pressure of the refrigerant flowing to the compressor, thereby reducing the risk of damage to the compressor.

[0008] According to some embodiments of the present invention, during the process of the refrigeration system switching from the defrost mode to the refrigeration mode, when the bypass valve of the original target evaporation branch is opened for a first preset time, the bypass valve of the original target evaporation branch is closed; or, each of the evaporation branches further includes a pressure sensor, which is located downstream of the return air unit, and the pressure sensor is used to detect the pressure of the refrigerant; during the process of the refrigeration system switching from the defrost mode to the refrigeration mode, when the pressure detected by the pressure sensor of the original target evaporation branch is less than or equal to the first preset pressure, the bypass valve of the original target evaporation branch is closed.

[0009] According to some embodiments of the present invention, the switching component includes: a first main pipe, the inlet end of the first main pipe is connected to the refrigeration cycle circuit and is located between the outlet of the compressor and the inlet of the condenser; a plurality of first branch pipes, the inlet end of the first branch pipe is connected to the outlet end of the first main pipe, the outlet end of the first branch pipe is connected to the evaporation branch, and the first branch pipes are connected to the evaporation branch in a one-to-one correspondence, for one first branch pipe and one evaporation branch connected to each other, the outlet end of the first branch pipe is located between the evaporator and the return air unit; a plurality of first valves, each first branch pipe is equipped with a first valve; when the switching component is in the closed state, all the first valves are closed closed; when the switching component is in the open state, the first valve corresponding to the target evaporation branch is opened, and the other first valves are closed; a second main pipe, the outlet end of the second main pipe is connected to the refrigeration cycle circuit and is located between the outlet of the condenser and the evaporation component; a plurality of second branches, the outlet end of the second branch pipe is connected to the inlet end of the second main pipe, the inlet end of the second branch pipe is connected to the evaporation branch, and the second branch pipe is connected to the evaporation branch one by one, for a second branch pipe and an evaporation branch connected to each other, the inlet end of the second branch pipe is located between the throttling element and the evaporator; a plurality of second valves, each second branch pipe is equipped with a second valve.

[0010] According to some embodiments of the present invention, the refrigeration cycle further includes a valve unit, which is located between the inlet end of the first main pipe and the inlet of the condenser, and the valve unit is configured as follows: when the refrigeration system is in the refrigeration mode, the refrigerant can pass through the valve unit and flow from the compressor to the condenser; when the refrigeration system is in the defrost mode, the valve unit blocks the refrigerant from flowing between the inlet end of the first main pipe and the inlet of the condenser; when the refrigeration system is in the shutdown mode, the compressor is turned off, and the valve unit blocks the refrigerant from flowing back from the condenser to the compressor.

[0011] According to some embodiments of the present invention, the valve unit includes: a main pressure differential valve, including a first inlet, a first outlet, and a main pressure feedback port, the opening of the main pressure differential valve changes according to the change of the refrigerant pressure at the main pressure feedback port, the first inlet is connected to the outlet of the compressor, and the first outlet is connected to the inlet of the condenser; a main solenoid valve, including a second inlet and a second outlet; a secondary pressure differential valve, including a third inlet, a third outlet and a secondary pressure feedback port, the opening of the secondary pressure differential valve changes according to the change of the refrigerant pressure at the secondary pressure feedback port; the first inlet, the second inlet and the third inlet are connected to each other, the main pressure feedback port, the third outlet and the second outlet are connected to each other, and the secondary pressure feedback port is connected to the first outlet; when the refrigeration system is in the refrigeration mode, the main solenoid valve is opened; when the refrigeration system is in the defrost mode, the main solenoid valve is closed; when the refrigeration system is in the shutdown state, the main solenoid valve is closed.

[0012] According to some embodiments of the present invention, each of the evaporation branches further includes an evaporation fan, the evaporation fan being adjacent to the evaporator and configured to generate an airflow passing through a surface of the evaporator.

[0013] According to some embodiments of the present invention, when the refrigeration system is in refrigeration mode, the power of the compressor is P1; when the refrigeration system is in defrost mode and the number of the target evaporation branches is equal to the number of the non-target evaporation branches, the power of the compressor is P2, P2=0.5P1.

[0014] According to some embodiments of the present invention, a refrigeration system includes: a refrigeration cycle circuit, including a compressor, a condenser and an evaporator component connected in series in sequence, the evaporator component includes at least two evaporator branches connected in parallel, each of the evaporator branches includes a throttling element, an evaporator and an air return unit connected in series in sequence, the air return unit includes an air return valve and a bypass valve connected in parallel with each other; a switching component, the switching component is connected to the refrigeration cycle circuit, the switching component has a closed state and an open state; when the refrigeration system is in a refrigeration mode, the switching component is in a closed state, the air return valve is opened, the bypass valve is closed, the compressor drives the refrigerant to flow cyclically along the refrigeration cycle circuit, and makes the refrigerant flow through the compressor, the condenser and each of the evaporator branches in sequence; when the refrigeration system is in a defrost mode, the switching component is in an open state, the target evaporator The return air valve and the bypass valve of the branch are closed, the return air valve of the non-target evaporation branch is opened, and the bypass valve of the non-target evaporation branch is closed. The compressor drives the refrigerant to flow in a cycle, and makes the refrigerant flow through the compressor, the target evaporator and the non-target evaporation branch in sequence. The refrigerant condenses in the target evaporator and evaporates in the non-target evaporator; wherein, the target evaporator is the evaporator that currently needs to be defrosted, and the remaining evaporators except the target evaporation are non-target evaporators, the evaporation branch where the target evaporator is located is the target evaporation branch, and the remaining evaporation branches except the target evaporation branch are non-target evaporation branches; during the switching process of the target evaporator, the return air valve and the bypass valve of the original target evaporation branch are opened first, and then the bypass valve of the original target evaporation branch is closed.

[0015] The refrigeration system of the embodiment of the present invention has at least the following beneficial effects: in the process of switching to the refrigeration mode, the return valve and the bypass valve of the original target evaporation branch are first opened at the same time. At this time, part of the high-pressure refrigerant will flow through the return valve, and the other part of the refrigerant will be diverted to the pipeline where the bypass valve is located. Since the refrigerant is diverted to the two valves, the pressure of the refrigerant flowing through the return valve and the refrigerant flowing through the bypass valve is relatively low. In addition, when the fluid flows through the return unit, it will first be diverted to the return valve and the bypass valve, and then merge. During the process of diversion and merging, the fluid will produce pressure loss. Therefore, the pressure of the refrigerant that finally merges and flows to the compressor is relatively low, which helps to reduce the risk of damage to the compressor.

[0016] According to some embodiments of the present invention, during the switching process of the target evaporator, after the bypass valve of the original target evaporation branch is opened for a second preset time, the bypass valve of the original target evaporation branch is closed; or, each of the evaporation branches further includes a pressure sensor, which is located downstream of the return air unit, and the pressure sensor is used to detect the pressure of the refrigerant. During the switching process of the target evaporator, when the pressure detected by the pressure sensor of the original target evaporation branch is less than or equal to the second preset pressure, the bypass valve of the original target evaporation branch is closed.

[0017] A cold storage according to an embodiment of the second aspect of the present invention includes the refrigeration system as described in the embodiment of the first aspect.

[0018] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0020] Figure 1 is a schematic diagram of a refrigeration system according to a first embodiment of the present invention;

[0021] Figure 2 is a schematic diagram of the refrigeration system of the first embodiment in the cooling mode;

[0022] Figure 3 This is a schematic diagram of the refrigeration system of the first embodiment when the first evaporator is defrosting;

[0023] Figure 4 This is a schematic diagram of the refrigeration system of the first embodiment when defrosting the second evaporator;

[0024] Figure 5 is a schematic diagram of the refrigeration system of the first embodiment in a first transition mode;

[0025] Figure 6 is a schematic diagram of the refrigeration system of the first embodiment in the second transition mode;

[0026] Figure 7 is a schematic diagram of a valve unit according to a first embodiment;

[0027] Figure 8 is a schematic diagram of a refrigeration system according to a second embodiment of the present invention;

[0028] Figure 9 FIG. 4 is a schematic diagram of a refrigeration system according to a third embodiment of the present invention.

[0029] Reference numerals: 101 - refrigeration system, 102 - compressor, 103 - valve unit, 104 - condenser, 105 - condensing fan, 106 - evaporation branch, 107 - first evaporation branch, 108 - second evaporation branch, 109 - evaporator, 110 - first evaporator, 111 - second evaporator, 112 - control valve, 113 - throttling element, 114 - evaporating fan, 115 - return air unit, 116 - return air valve, 117 - bypass valve, 118 - first main pipe, 119 - first branch pipe, 120 - first valve , 121-second main pipe, 122-second branch pipe, 123-second valve, 124-pressure sensor, 125-gas-liquid separator, 126-oil separator, 127-liquid storage tank, 128-filter, 129-sight glass, 130-main differential pressure valve, 131-first inlet, 132-first outlet, 133-main pressure feedback port, 134-main solenoid valve, 135-second inlet, 136-second outlet, 137-secondary differential pressure valve, 138-third inlet, 139-third outlet, 140-secondary pressure feedback port. DETAILED DESCRIPTION

[0030] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0031] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the modules or components referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0032] In the description of the present invention, "several" means more than one, "plurality" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The use of "first" and "second" in the description is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0033] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0034] Figure 1A refrigeration system 101 according to an embodiment of the present invention is shown. The refrigeration system 101 includes a refrigeration cycle and a switching component.

[0035] like Figure 1 As shown, the refrigeration cycle includes a compressor 102, a condenser 104 and an evaporation component connected in series. The series connection can be specifically connected through a pipeline, and the refrigerant can flow in the pipeline. It should be noted that "sequentially" is based on the flow path of the refrigerant in the refrigeration mode. If the refrigerant flows through the compressor 102, the condenser 104 and the evaporation component in turn, the compressor 102, the condenser 104 and the evaporation component are connected in series in sequence. The meaning of the series connection below is similar to this. The piping part of the refrigeration cycle is as follows Figure 2 Indicated by the bold line segment.

[0036] like Figure 1 As shown, the evaporation assembly includes two evaporation branches 106 connected in parallel. Each evaporation branch 106 includes a throttling element 113, an evaporator 109, and a return air unit 115 connected in series. In this embodiment, the throttling element 113 is an electronic expansion valve. In other embodiments not shown, the throttling element 113 can also be a capillary tube or a thermal expansion valve. The return air unit 115 includes a return air valve 116 and a bypass valve 117 connected in parallel. Both valves can be solenoid valves. The evaporator 109 and the condenser 104 can be finned heat exchangers or other types of heat exchangers. In this embodiment, the evaporation assembly includes two evaporation branches 106 connected in parallel, namely a first evaporation branch 107 and a second evaporation branch 108.

[0037] like Figure 1 As shown, the evaporation assembly further includes a control valve 112, which can be a solenoid valve and is located upstream of the throttling element 113. It should be noted that if the throttling element 113 is an electronic expansion valve, the control valve 112 can be omitted, as the electronic expansion valve can also be completely closed, thereby obstructing the flow of refrigerant. If the throttling element 113 is a capillary tube, the evaporation branch 106 must be equipped with the control valve 112 to control the flow path of the refrigerant.

[0038] The switching assembly is connected to the refrigeration cycle and has a closed state and an open state. In this embodiment, the switching assembly includes a first main pipe 118, a second main pipe 121, two first branch pipes 119, two first valves 120, two second branch pipes 122 and two second valves 123.

[0039] like Figure 1As shown, the inlet of first main pipe 118 is connected to the refrigeration cycle and is located between the outlet of compressor 102 and the inlet of condenser 104. The inlet of first branch pipe 119 is connected to the outlet of first main pipe 118, and the outlet of first branch pipe 119 is connected to evaporation branch 106, with each first branch pipe 119 connected to each evaporation branch 106 in a one-to-one correspondence. For each interconnected first branch pipe 119 and evaporation branch 106, the outlet of first branch pipe 119 is located between evaporator 109 and return air unit 115. Each first branch pipe 119 is equipped with a first valve 120, which can be a two-way solenoid valve.

[0040] like Figure 1 As shown, the outlet end of second main pipe 121 is connected to the refrigeration cycle and is located between the outlet of condenser 104 and the evaporation assembly. The outlet end of second branch pipe 122 is connected to the inlet end of second main pipe 121, and the inlet end of second branch pipe 122 is connected to evaporation branch 106, with each second branch pipe 122 connected to the evaporation branch 106 in a one-to-one correspondence. For each second branch pipe 122 and evaporation branch 106 connected to each other, the inlet end of second branch pipe 122 is located between throttling element 113 and evaporator 109. Each second branch pipe 122 is equipped with a second valve 123, which is a one-way valve that allows refrigerant to flow from the inlet end of second branch pipe 122 to the outlet end of second branch pipe 122.

[0041] In other embodiments not shown in the figure, the second valve 123 can also be set as a two-way solenoid valve. The switching component is not limited to the forms listed above. The pipeline direction, valve form, etc. of the switching component can also be adjusted separately, which will not be given in detail here. The switching component of this embodiment does not use a three-way valve or a four-way reversing valve, but only uses a two-way valve, so the cost of the refrigeration system 101 is relatively low. In addition, in other embodiments not shown in the figure, the number of evaporation branches 106 included in the evaporation component can also be greater than two. For example, the number of evaporation branches 106 can be three, four, five, etc. Correspondingly, the number of the first valve 120, the first branch pipe 119, the second valve 123, and the second branch pipe 122 are all the same as the number of evaporation branches 106.

[0042] When the refrigeration system 101 is in cooling mode, the switching component is in a closed state; at this time, all first valves 120 are closed. When the refrigeration system 101 is in defrosting mode, the switching component is in an open state; at this time, the first valve 120 corresponding to the target evaporation branch is opened, and the other first valves 120 are closed.

[0043] To facilitate the introduction of the operating mode of the refrigeration system 101 , the meanings of the target evaporator, the non-target evaporator, the target evaporation branch, and the non-target evaporation branch are first introduced below.

[0044] The evaporator 109 that currently needs to be defrosted is the target evaporator, and the remaining evaporators 109 are non-target evaporators. For example, after the refrigeration system 101 has been running for a period of time, the first evaporator 110 is frosted. Therefore, the first evaporator 110 needs to be defrosted. The first evaporator 110 is the target evaporator, and the second evaporator 111 is the non-target evaporator.

[0045] For another example, after refrigeration system 101 has been operating for a period of time, frost forms on both first evaporator 110 and second evaporator 111. Therefore, both first evaporator 110 and second evaporator 111 need to be defrosted. However, first evaporator 110 is defrosted first, followed by second evaporator 111. During the defrosting process of first evaporator 110, first evaporator 110 is the target evaporator; during the defrosting process of second evaporator 111, second evaporator 111 is the target evaporator.

[0046] The evaporation branch 106 where the target evaporator is located is the target evaporation branch, and all other evaporation branches except the target evaporation branch are non-target evaporation branches. For example, when the first evaporator 110 is defrosting, the first evaporation branch 107 where the first evaporator 110 is located is the target evaporation branch, and the second evaporation branch 108 where the second evaporator 111 is located is the non-target evaporation branch. When the second evaporator 111 is defrosting, the second evaporation branch 108 is the target evaporation branch, and the first evaporation branch 107 is the non-target evaporation branch.

[0047] The following describes the operation modes of the refrigeration system 101. The refrigeration system 101 has a refrigeration mode and a defrost mode.

[0048] like Figure 2 As shown, when the refrigeration system 101 is in cooling mode, the switching assembly is in a closed state (for example, all first valves 120 are closed), the return valve 116 is open, and the bypass valve 117 is closed. The compressor 102 drives the refrigerant to flow cyclically along the refrigeration cycle, and causes the refrigerant to flow through the compressor 102, the condenser 104, and each evaporation branch 106 in sequence. When the refrigerant flows through the evaporation branch 106, the refrigerant flows through the throttling element 113 of the evaporation branch 106, the evaporator 109, and the return valve 116 in sequence. The gaseous refrigerant compressed by the compressor 102 condenses in the condenser 104. The pressure of the condensed refrigerant decreases after passing through the throttling element 113. The refrigerant then enters the evaporator 109 for evaporation. The evaporated refrigerant returns to the compressor 102 and enters the next cycle.

[0049] When the refrigeration system 101 is in the defrost mode, the switching component is in the open state, the return air valve 116 and the bypass valve 117 of the target evaporation branch are closed, the return air valve 116 of the non-target evaporation branch is opened, and the bypass valve 117 of the non-target evaporation branch is closed. As described above, the switching component is in the open state in which the first valve 120 corresponding to the target evaporation branch is opened, and the remaining first valves 120 are closed. At this time, the compressor 102 drives the refrigerant to flow cyclically, and the refrigerant flows through the compressor 102, the target evaporator and the non-target evaporation branch in sequence. The refrigerant condenses in the target evaporator, and the heat released by the condensation of the refrigerant can melt the frost on the surface of the target evaporator. The refrigerant evaporates and absorbs heat in the non-target evaporator, so that the refrigeration system 101 still has a certain refrigeration effect.

[0050] For example, Figure 3 As shown, when the refrigeration system 101 is in defrost mode, the first evaporator 110 is the target evaporator, the first evaporation branch 107 is the target evaporation branch, the second evaporator 111 is the non-target evaporator, and the second evaporation branch 108 is the non-target evaporation branch. After the compressed refrigerant leaves the compressor 102, it first flows through the first main pipe 118 and the first valve 120 corresponding to the first evaporation branch 107 (i.e. Figure 3 The refrigerant then flows sequentially through the second valve 123 corresponding to the first evaporation branch 107, the second main pipe 121, and the second evaporation branch 108. While flowing through the second evaporation branch 108 (the non-target evaporation branch), the refrigerant sequentially passes through the throttling element 113 of the second evaporation branch 108, the second evaporator 111 (the non-target evaporator), and the return valve 116. After leaving the second evaporation branch 108, the refrigerant returns to the compressor 102 and enters the next cycle.

[0051] For example, Figure 4 As shown, when the refrigeration system 101 is in defrost mode, the second evaporator 111 is the target evaporator, the second evaporation branch 108 is the target evaporation branch, the first evaporator 110 is the non-target evaporator, and the first evaporation branch 107 is the non-target evaporation branch. After the compressed refrigerant leaves the compressor 102, it first flows through the first main pipe 118 and the first valve 120 corresponding to the second evaporation branch 108 (i.e. Figure 3 Subsequently, the refrigerant flows through the second valve 123 corresponding to the second evaporation branch 108, the second trunk pipe 121, and the first evaporation branch 107 in sequence.

[0052] Since the refrigerant can evaporate in the non-target evaporator in the defrost mode, the non-target evaporator can still provide cooling to the object or environment that needs to be cooled. The refrigeration system 101 still has a certain cooling capacity during the defrosting process of a portion of the evaporators 109. Therefore, the refrigeration system 101 of this embodiment overcomes the problem that the refrigeration system 101 cannot provide cooling during the defrosting process, and also overcomes the problem that defrosting causes the temperature of the object or environment that needs to be cooled to rise. In addition, in the defrost mode, although a portion of the refrigerant will accumulate in the condenser 104, a large amount of refrigerant will not pass through the condenser 104. The refrigerant mainly condenses in the target evaporator, and the latent heat of the refrigerant can be fully used to defrost the target evaporator, thereby improving the defrosting efficiency.

[0053] When the refrigeration system 101 switches from the defrost mode to the refrigeration mode, the return air valve 116 and the bypass valve 117 of the original target evaporation branch are first opened (or opened simultaneously), and then the bypass valve 117 of the original target evaporation branch is closed. This configuration helps prevent high-pressure refrigerant from impacting the compressor 102, thereby reducing the risk of damage to the compressor 102.

[0054] The following examples illustrate the benefits of the above-mentioned mode switching method. Figure 3 The defrost mode shown is switched to Figure 2 The cooling mode shown in FIG, then the above mode switching method is equivalent to: the cooling system 101 first switches from Figure 3 The status shown switches to Figure 5 The status shown, then from Figure 5 The status shown switches to Figure 2 The status shown. Figure 5 The status shown is the same as Figure 2 The difference between the states shown is that Figure 5 The bypass valve 117 of the first evaporation branch 107 is open, and Figure 2 In the case of refrigeration system 101, the bypass valve 117 is closed. Figure 5 In the state shown, the refrigeration system 101 is in the first transition mode. The refrigeration system 101 first switches from the defrost mode to the first transition mode, and then switches from the first transition mode to the refrigeration mode.

[0055] Please refer to Figure 3 Point A in the figure is located between the outlet of the compressor 102 and the first evaporator 110. The refrigerant at point A is compressed by the compressor 102 and then needs to be condensed in the first evaporator 110. Therefore, the pressure of the refrigerant at point A is relatively high. Figure 3 The status shown switches to Figure 2In the state shown, immediately after the refrigeration system completes the switch, the refrigerant that originally flowed to the right at point A changes to flow to the left, passes through the return air valve 116 of the original target evaporation branch (the first evaporation branch 107), and then flows to the compressor 102. This portion of high-pressure refrigerant flowing to the compressor 102 is likely to cause an impact on the compressor 102, thereby shortening the life of the compressor 102 and even causing damage to the compressor 102.

[0056] In the process of switching to the cooling mode, the present embodiment opens the return air valve 116 and the bypass valve 117 of the original target evaporation branch at the same time. At this time, part of the refrigerant flowing to the right from point A will flow through the return air valve 116, and the other part of the refrigerant will be diverted to the pipeline where the bypass valve 117 is located (see also Figure 3 and Figure 5 ). Since the refrigerant is diverted to two valves, the pressure of the refrigerant flowing through the return valve 116 and the refrigerant flowing through the bypass valve 117 is relatively low. In addition, when the fluid flows through the return unit 115, it will first be diverted to the return valve 116 and the bypass valve 117, and then merge. In the process of diversion and merging, the fluid will produce pressure loss. For example, during the merging process, the flow speed and direction of different streams of fluid may be different, and the confluence of multiple streams of fluid will produce impact and mixing, thereby generating pressure loss. Therefore, the pressure of the refrigerant that finally merges and flows to the compressor 102 is relatively low, which helps to reduce the risk of damage to the compressor 102.

[0057] It should be noted that if Figure 3 As shown in FIG. 1 , at point B, the refrigerant flows to the non-target evaporator (the second evaporator 111) instead of the second valve 123 corresponding to the non-target evaporator because the one-way valve also needs to be driven by a pressure difference. The refrigerant at point C has just completed condensation and its pressure is higher, while the refrigerant at point B is the refrigerant throttled by the throttling element 113 and its pressure is lower. Therefore, the refrigerant pressure at point B is lower than the refrigerant pressure at point C, and the refrigerant at point B will not flow to the second valve 123 corresponding to the non-target evaporator (i.e., Figure 3 Therefore, when the second valve 123 is a one-way valve, the refrigeration system 101 or the user does not need to specifically control the opening and closing of the second valve 123, which can simplify the operation control logic of the refrigeration system 101.

[0058] The refrigeration system 101 typically operates in the cooling mode for a long period of time. Therefore, during the operation of the refrigeration system 101, the refrigerant passes through the return valve 116 most of the time. Accordingly, in some embodiments, the diameter of the pipeline where the return valve 116 is located can be larger than the diameter of the pipeline where the bypass valve 117 is located, so that the return valve 116 can allow a large amount of refrigerant to pass through.

[0059] In some embodiments, when the refrigeration system 101 switches from the defrost mode to the cooling mode, when the bypass valve 117 of the original target evaporation branch has been open for a first preset time, the bypass valve 117 of the original target evaporation branch is closed. After the bypass valve 117 of the target evaporation branch has been open for a period of time, the refrigerant pressure gradually decreases and stabilizes, and the impact of the refrigerant on the compressor 102 is reduced. Subsequently, the bypass valve 117 can be closed, and the refrigeration system 101 enters the stable cooling mode.

[0060] In other embodiments, Figure 8 As shown, each evaporation branch 106 also includes a pressure sensor 124, located downstream of the return air unit 115. Pressure sensor 124 is used to detect refrigerant pressure. "Pressure sensor 124 located downstream of the return air unit 115" means that in cooling mode, refrigerant first flows through the return air unit 115 and then through pressure sensor 124. During the process of switching the refrigeration system 101 from defrost mode to cooling mode, if the pressure detected by pressure sensor 124 of the original target evaporation branch is less than or equal to a first preset pressure, the bypass valve 117 of the original target evaporation branch closes. When the pressure detected by pressure sensor 124 is less than or equal to the first preset pressure, the refrigerant pressure has decreased, reducing the impact of the refrigerant on compressor 102. Subsequently, bypass valve 117 can be closed, and refrigeration system 101 enters a stable cooling mode. By detecting the refrigerant pressure, the timing for closing bypass valve 117 can be more accurately determined, ensuring that the refrigerant pressure after closing bypass valve 117 does not significantly impact compressor 102.

[0061] The refrigeration system 101 may further include a controller (not shown), and the opening and closing of each valve in the refrigeration system 101 and the operation of the compressor 102 may be controlled by the controller.

[0062] like Figure 1 As shown, each evaporation branch 106 includes an evaporation fan 114, which is adjacent to the evaporator 109 and is used to generate an airflow passing through the surface of the evaporator 109. The airflow flowing through the surface of the evaporator 109 and the refrigerant in the evaporator 109 can generate convection heat exchange, thereby improving the heat exchange efficiency between the refrigerant in the evaporator 109 and the outside air. In addition, the airflow flowing through the surface of the evaporator 109 can subsequently be blown to the cooled object or indoor environment (such as the warehouse environment of a cold storage), thereby cooling the object or environment. Similarly, as Figure 1As shown, the refrigeration system 101 further includes a condensing fan 105, which is adjacent to the condenser 104 and is used to generate airflow passing through the surface of the condenser 104, thereby improving the heat exchange efficiency between the refrigerant in the condenser 104 and the outside air. It should be noted that if the refrigeration system 101 is used in a cold storage, the airflow passing through the surface of the condenser 104 will not subsequently enter the storage room, but will be discharged to the outdoor environment.

[0063] like Figure 3 As shown, when the refrigeration system 101 is in defrost mode and the number of target evaporation branches is the same as the number of non-target evaporation branches; for example, the number of both is 1. When the refrigeration system 101 is in refrigeration mode, the power of the compressor 102 is P1, and when the refrigeration system 101 is in defrost mode, the power of the compressor 102 is P2, P2=0.5P1. This setting is suitable for the refrigeration system 101 in which all target evaporators have the same specifications. As mentioned above, in defrost mode, the refrigerant condenses in the target evaporator, and the target evaporator actually acts as a condenser. Since the number of target evaporation branches is the same as the number of non-target evaporation branches, in defrost mode, the heat released by the refrigerant at the target evaporator matches the heat absorbed at the non-target evaporator, and the refrigeration system 101 can operate well. Moreover, since the target evaporator acts as a condenser in the defrost mode, and the condensed refrigerant passes through the throttling element 113 of the non-target evaporation branch and is throttled, the throttled refrigerant only evaporates in the non-target evaporator. Therefore, compared with the refrigeration mode, the power of the compressor 102 in the defrost mode can be halved.

[0064] like Figure 1 As shown, in some embodiments, the refrigeration cycle further includes a valve unit 103, which is located between the inlet end of the first main pipe 118 and the inlet of the condenser 104. When the refrigeration system 101 is in cooling mode, refrigerant can pass through the valve unit 103 and flow from the compressor 102 to the condenser 104. When the refrigeration system 101 is in defrost mode, the valve unit 103 blocks the flow of refrigerant between the inlet end of the first main pipe 118 and the inlet of the condenser 104, ensuring that all refrigerant leaving the compressor 102 flows to the target evaporator, thereby improving the defrosting efficiency of the target evaporator. When the refrigeration system 101 is in shutdown mode, the compressor 102 is shut down, and the valve unit 103 blocks the backflow of refrigerant from the condenser 104 to the compressor 102, preventing liquid refrigerant from entering the compressor 102. This prevents liquid hammer when the compressor 102 is next started, thereby reducing the risk of damage to the compressor 102.

[0065] like Figure 7As shown, the valve unit 103 may include a main differential pressure valve 130, a main solenoid valve 134, and a secondary differential pressure valve 137. The main differential pressure valve 130 includes a first inlet 131, a first outlet 132, and a main pressure feedback port 133. When the main solenoid valve 134 is not powered, the opening of the main differential pressure valve 130 changes according to the pressure at the main pressure feedback port 133. The greater the pressure at the main pressure feedback port 133, the greater the opening of the main differential pressure valve 130; the lower the pressure at the main pressure feedback port 133, the smaller the opening of the main differential pressure valve 130. The first inlet 131 is connected to the outlet of the compressor 102, and the first outlet 132 is connected to the inlet of the condenser 104. The main solenoid valve 134 includes a second inlet 135 and a second outlet 136. The secondary differential pressure valve 137 includes a third inlet 138, a third outlet 139, and a secondary pressure feedback port 140. The opening of the secondary differential pressure valve 137 changes according to the refrigerant pressure at the secondary pressure feedback port 140. The higher the pressure at the secondary pressure feedback port 140, the greater the pressure signal transmitted by the secondary differential pressure valve 137 to the primary differential pressure valve 130, causing the primary differential pressure valve 130 to open. The lower the pressure at the secondary pressure feedback port 140, the smaller the pressure signal transmitted by the secondary differential pressure valve 137 to the primary differential pressure valve 130, causing the primary differential pressure valve 130 to open, or not open at all. The first inlet 131, the second inlet 135, and the third inlet 138 are interconnected. The primary pressure feedback port 133, the second outlet 136, and the third outlet 139 are interconnected. The secondary pressure feedback port 140 is connected to the first outlet 132.

[0066] When refrigeration system 101 is in cooling mode, main solenoid valve 134 is open, allowing refrigerant to flow from point D to point E through the main pressure differential valve. Valve unit 103 is not pressure-controlled. Point D is located at the inlet of first trunk line 118 and is connected to the outlet of compressor 102. Point E is located at the inlet of condenser 104.

[0067] When the refrigeration system 101 is in defrost mode, the main solenoid valve 134 is closed, and the refrigerant flow is primarily controlled by the main differential pressure valve 130 and the secondary differential pressure valve 137. When the pressure at point D is greater than that at point E and exceeds the set differential pressure, the pressure at the secondary pressure feedback port 140 is low, and the pressure fed back from the secondary differential pressure valve 137 to the main differential pressure valve 130 is low, allowing only a small amount of refrigerant to pass from point D through the main differential pressure valve 130 to point E. When the pressure difference between points D and E does not exceed the set differential pressure, the pressure at the main pressure feedback port 133 is low, insufficient to open the main differential pressure valve 130. At this point, the main differential pressure valve 130 closes, and refrigerant cannot flow from point D to point E.

[0068] In other embodiments not shown, the valve unit 103 may also be configured in other ways. For example, to simplify the structure, the valve unit 103 may only include the main solenoid valve 134. In this case, the opening of the main solenoid valve 134 can be adjusted by the controller to adjust the refrigerant flow rate of the refrigeration system 101.

[0069] The above describes the process of switching the refrigeration system 101 from the defrost mode to the refrigeration mode. The following describes the process of switching the target evaporator of the refrigeration system 101.

[0070] "Switching the target evaporator" refers to changing the evaporator 109 to be defrosted, and can also be understood as changing the evaporator 109 to which the target evaporator actually refers. For example, after defrosting the first evaporator 110, the second evaporator 111 needs to be defrosted. In this case, the target evaporator changes from the first evaporator 110 to the second evaporator 111, and the target evaporator is switched; the first evaporator 110 becomes the original target evaporator, the first evaporation branch 107 becomes the original target evaporation branch, the second evaporator 111 becomes the new target evaporator, and the second evaporation branch 108 becomes the new target evaporator.

[0071] like Figure 4 As shown, when the second evaporator 111 is defrosting (ie, the second evaporator 111 is used as the target evaporator), the flow path of the refrigerant in the refrigeration system 101 is as follows: Figure 4 After leaving the compressor 102, the refrigerant flows through the first valve 120 corresponding to the second evaporator 111, the second evaporator 111, the second valve 123 corresponding to the second evaporator 111, the first evaporation branch 107, and then returns to the compressor 102. Figure 3 and Figure 4 ( Figure 3 Schematic diagram of the first evaporator 110 during defrosting), assuming that the refrigeration system 101 is directly Figure 3 The status shown switches to Figure 4 In the state shown, immediately after the switch is completed, the refrigerant that originally flowed to the right at point A changes to flow to the left and passes through the return air valve 116 of the original target evaporation branch 107, and then flows to the compressor 102. This portion of high-pressure refrigerant flowing to the compressor 102 is likely to cause an impact on the compressor 102, thereby shortening the life of the compressor 102 and even causing damage to the compressor 102.

[0072] To reduce the risk of damage to compressor 102, in some embodiments, during the target evaporator switching process, the return air valve 116 and bypass valve 117 of the original target evaporation branch are first opened, followed by the closing of bypass valve 117 of the original target evaporation branch. Since the refrigerant can be diverted within the return air unit 115 of the original target evaporation branch after switching the target evaporator, the refrigerant is decompressed before flowing to compressor 102, thereby reducing the risk of damage to compressor 102. The principle of pressure relief when bypass valve 117 is opened can be found in the description above and is not elaborated here.

[0073] For example, when the refrigeration system 101 is Figure 3 Switch to Figure 6 In the state shown, the original target evaporation branch is the first evaporation branch 107, and the new target evaporation branch is the second evaporation branch 108. The bypass valve 117 and the return air valve 116 on the first evaporation branch 107 are opened at the same time. Subsequently, the bypass valve 117 on the first evaporation branch 107 is closed, and the refrigeration system 101 is turned off again. Figure 6 Switch to Figure 4 The status shown.

[0074] It should be noted that no matter the refrigeration system 101 is Figure 3 、 Figure 4 still Figure 6 In the state shown, the refrigeration system 101 is actually in the defrost mode, because no matter in which state there is at least one evaporator 109 in the defrost mode. It can also be understood that the defrost mode includes multiple sub-modes. Figure 3 In the state shown, the refrigeration system 101 is in the first sub-mode; the refrigeration system 101 is in Figure 4 In the state shown, the refrigeration system 101 is in the second sub-mode; the refrigeration system 101 is in Figure 6 In the state shown, the refrigeration system 101 is in the second transition mode.

[0075] In some embodiments, during the switching process of the target evaporator, after the bypass valve 117 of the original target evaporation branch is opened for a second preset time, the bypass valve 117 of the original target evaporation branch is closed. After the bypass valve 117 of the original target evaporation branch is opened for a period of time, the refrigerant pressure gradually decreases and stabilizes, and the impact of the refrigerant on the compressor 102 is reduced. Subsequently, the bypass valve 117 can be closed, and the refrigeration system 101 enters a stable cooling mode.

[0076] Alternatively, in other embodiments, during the switching process of the target evaporator, if the pressure detected by the pressure sensor 124 of the original target evaporation branch is less than or equal to the second preset pressure, the bypass valve 117 of the original target evaporation branch is closed. When the pressure detected by the pressure sensor 124 is less than or equal to the second preset pressure, the refrigerant pressure has decreased, and the impact of the refrigerant on the compressor 102 has been reduced. Subsequently, the bypass valve 117 can be closed, and the refrigeration system 101 enters a stable refrigeration mode. By detecting the refrigerant pressure, it is possible to more accurately determine whether it is currently appropriate to close the bypass valve 117, thereby ensuring that the refrigerant pressure after closing the bypass valve 117 will not impact the compressor 102.

[0077] The first preset time and the second preset time may be the same or different, and the first preset pressure and the second preset pressure may be the same or different.

[0078] like Figure 9 As shown, in some embodiments, the refrigeration system 101 may further include a gas-liquid separator 125, an oil separator 126, a storage tank, a filter 128, and a sight glass 129. The gas-liquid separator 125 is located downstream of the evaporator assembly and upstream of the compressor 102. In cooling mode, the refrigerant may not completely evaporate in the evaporator 109, and the refrigerant leaving the evaporator assembly may be a two-phase refrigerant. The gas-liquid separator 125 can separate the gas-liquid refrigerant and allow the gaseous refrigerant to enter the compressor 102 to prevent the liquid refrigerant from entering the compressor 102 and causing damage to the compressor 102 due to liquid hammer. The oil separator 126 is located downstream of the compressor 102 and upstream of the valve unit 103. The oil separator 126 can separate the lubricating oil mixed in the refrigerant and return it to the compressor 102. Liquid storage tank 127 is located downstream of condenser 104 and upstream of the evaporator assembly. It is used to store refrigerant and can reduce pressure fluctuations in refrigeration system 101. Filter 128 is used to filter impurities from the refrigerant. Maintenance personnel of refrigeration system 101 can observe the amount of refrigerant in the system through sight glass 129 to determine whether refrigeration system 101 is short of refrigerant.

[0079] In the description of the present invention, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the exemplary expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Claims

1. Refrigeration system, characterized in that, include: A refrigeration cycle circuit includes a compressor, a condenser, and an evaporation assembly connected in series, the evaporation assembly includes at least two evaporation branches connected in parallel, each of the evaporation branches includes a throttling element, an evaporator, and an air return unit connected in series, the air return unit includes an air return valve and a bypass valve connected in parallel; A switching component, the switching component is connected to the refrigeration cycle circuit, and the switching component has an off state and an on state; When the refrigeration system is in cooling mode, the switching assembly is in a closed state, the return air valve is open, the bypass valve is closed, and the compressor drives the refrigerant to circulate along the refrigeration cycle and causes the refrigerant to flow through the compressor, the condenser, and each of the evaporation branches in sequence; When the refrigeration system is in the defrost mode, the switching component is in the open state, the return valve and the bypass valve of the target evaporation branch are closed, the return valve of the non-target evaporation branch is opened, and the bypass valve of the non-target evaporation branch is closed, and the compressor drives the refrigerant to flow cyclically, and makes the refrigerant flow through the compressor, the target evaporator and the non-target evaporation branch in sequence, and the refrigerant condenses in the target evaporator and evaporates in the non-target evaporator; wherein, the target evaporator is the evaporator that currently needs to be defrosted, and the remaining evaporators except the target evaporator are non-target evaporators, the evaporation branch where the target evaporator is located is the target evaporation branch, and the remaining evaporation branches except the target evaporation branch are non-target evaporation branches; During the process of the refrigeration system switching from the defrost mode to the refrigeration mode, the return air valve and the bypass valve of the original target evaporation branch are first opened, and then the bypass valve of the original target evaporation branch is closed.

2. The refrigeration system according to claim 1, characterized in that During the process of the refrigeration system switching from the defrost mode to the refrigeration mode, when the bypass valve of the original target evaporation branch is opened for a first preset time, the bypass valve of the original target evaporation branch is closed; Alternatively, each of the evaporation branches further includes a pressure sensor, which is located downstream of the return air unit and is used to detect the pressure of the refrigerant; during the process of the refrigeration system switching from the defrost mode to the refrigeration mode, when the pressure detected by the pressure sensor of the original target evaporation branch is less than or equal to the first preset pressure, the bypass valve of the original target evaporation branch is closed.

3. The refrigeration system according to claim 1, wherein: The switching component includes: a first trunk pipe, wherein an inlet end of the first trunk pipe is connected to the refrigeration cycle and is located between the outlet of the compressor and the inlet of the condenser; a plurality of first branch pipes, wherein the inlet ends of the first branch pipes are connected to the outlet ends of the first main pipes, the outlet ends of the first branch pipes are connected to the evaporation branches, and the first branch pipes are connected to the evaporation branches in a one-to-one correspondence, and for each of the first branch pipes and the evaporation branches that are connected to each other, the outlet ends of the first branch pipes are located between the evaporator and the return air unit; a plurality of first valves, each of the first branches being equipped with a first valve; when the switching component is in the closed state, all the first valves are closed; when the switching component is in the open state, the first valve corresponding to the target evaporation branch is opened, and the remaining first valves are closed; a second trunk pipe, wherein an outlet end of the second trunk pipe is connected to the refrigeration cycle and is located between the outlet of the condenser and the evaporation assembly; a plurality of second branch pipes, wherein the outlet ends of the second branch pipes are connected to the inlet ends of the second main pipes, the inlet ends of the second branch pipes are connected to the evaporation branches, and the second branch pipes are connected to the evaporation branches in a one-to-one correspondence, and for each second branch pipe and each evaporation branch that are connected to each other, the inlet ends of the second branch pipes are located between the throttling element and the evaporator; A plurality of second valves are provided, and each of the second branch pipes is provided with a second valve.

4. The refrigeration system according to claim 3, characterized in that The refrigeration cycle further includes a valve unit, which is located between the inlet end of the first main pipe and the inlet of the condenser, and is configured as follows: When the refrigeration system is in a cooling mode, the refrigerant can pass through the valve unit and flow from the compressor to the condenser; When the refrigeration system is in a defrost mode, the valve unit blocks the refrigerant from flowing between the inlet end of the first main pipe and the inlet of the condenser; When the refrigeration system is in a shutdown mode, the compressor is turned off, and the valve unit prevents the refrigerant from flowing back from the condenser to the compressor.

5. The refrigeration system according to claim 4, characterized in that The valve unit comprises: a main pressure differential valve, comprising a first inlet, a first outlet, and a main pressure feedback port, wherein the opening of the main pressure differential valve varies according to the change of the refrigerant pressure at the main pressure feedback port, the first inlet being connected to the outlet of the compressor, and the first outlet being connected to the inlet of the condenser; A main solenoid valve including a second inlet and a second outlet; a secondary pressure differential valve, comprising a third inlet, a third outlet, and a secondary pressure feedback port, wherein the opening of the secondary pressure differential valve varies according to changes in the refrigerant pressure at the secondary pressure feedback port; the first inlet, the second inlet, and the third inlet are interconnected, the primary pressure feedback port, the third outlet, and the second outlet are interconnected, and the secondary pressure feedback port is connected to the first outlet; When the refrigeration system is in the refrigeration mode, the main solenoid valve is opened; when the refrigeration system is in the defrost mode, the main solenoid valve is closed; when the refrigeration system is in the shutdown state, the main solenoid valve is closed.

6. The refrigeration system according to claim 1, wherein: Each of the evaporation branches further includes an evaporation fan, which is adjacent to the evaporator and is configured to generate an airflow passing through a surface of the evaporator.

7. The refrigeration system according to claim 1, wherein: When the refrigeration system is in cooling mode, the power of the compressor is P1; when the refrigeration system is in defrosting mode and the number of the target evaporation branches is equal to the number of the non-target evaporation branches, the power of the compressor is P2, P2=0.5P1.

8. Refrigeration system, characterized in that, include: A refrigeration cycle circuit includes a compressor, a condenser, and an evaporation assembly connected in series, the evaporation assembly includes at least two evaporation branches connected in parallel, each of the evaporation branches includes a throttling element, an evaporator, and an air return unit connected in series, the air return unit includes an air return valve and a bypass valve connected in parallel; A switching component, the switching component is connected to the refrigeration cycle circuit, and the switching component has an off state and an on state; When the refrigeration system is in cooling mode, the switching assembly is in a closed state, the return air valve is open, the bypass valve is closed, and the compressor drives the refrigerant to flow cyclically along the refrigeration cycle, and causes the refrigerant to flow through the compressor, the condenser, and each of the evaporation branches in sequence; When the refrigeration system is in the defrost mode, the switching component is in the open state, the return valve and the bypass valve of the target evaporation branch are closed, the return valve of the non-target evaporation branch is opened, and the bypass valve of the non-target evaporation branch is closed, and the compressor drives the refrigerant to flow cyclically, and makes the refrigerant flow through the compressor, the target evaporator and the non-target evaporation branch in sequence, and the refrigerant condenses in the target evaporator and evaporates in the non-target evaporator; wherein, the target evaporator is the evaporator that currently needs to be defrosted, and the remaining evaporators except the target evaporator are non-target evaporators, the evaporation branch where the target evaporator is located is the target evaporation branch, and the remaining evaporation branches except the target evaporation branch are non-target evaporation branches; During the switching process of the target evaporator, the return air valve and the bypass valve of the original target evaporation branch are first opened, and then the bypass valve of the original target evaporation branch is closed.

9. The refrigeration system according to claim 8, characterized in that During the switching process of the target evaporator, after the bypass valve of the original target evaporation branch is opened for a second preset time, the bypass valve of the original target evaporation branch is closed; Alternatively, each of the evaporation branches further includes a pressure sensor, which is located downstream of the return air unit. The pressure sensor is used to detect the pressure of the refrigerant. During the switching process of the target evaporator, when the pressure detected by the pressure sensor of the original target evaporation branch is less than or equal to the second preset pressure, the bypass valve of the original target evaporation branch is closed.

10. Cold storage, characterized in that, Comprising a refrigeration system according to any one of claims 1 to 9.

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