A refrigeration system

Abstract

A refrigeration system has a compressor unit, a condenser unit, an evaporator unit in series, the evaporator unit having a first evaporator branch and a second evaporator branch; further having a first reversing valve, a second reversing valve and an inter-valve branch; the first reversing valve has a first mode of connecting the output of the condenser unit to the first evaporator branch and connecting the input of the second evaporator branch to the inter-valve branch, and a second mode of connecting the output of the condenser unit to the second evaporator branch and connecting the input of the first evaporator branch to the inter-valve branch; the second reversing valve has a third mode of connecting the output of the first evaporator branch to the inter-valve branch and connecting the output of the second evaporator branch to the input of the compressor unit, and a fourth mode of connecting the output of the first evaporator branch to the input of the compressor unit and connecting the output of the second evaporator branch to the inter-valve branch. Thus, the evaporator can be defrosted and the temperature and humidity fluctuations can be reduced.

Description

Technical Field

[0001] This application relates to a refrigeration system capable of defrosting the evaporator and reducing temperature and humidity fluctuations. Background Technology

[0002] Refrigerated boxes are widely used in production and daily life. For example, in the medical field, medical refrigerators are used to store medicines, reagents and other medical products. The temperature inside the box is generally set between 2-8℃ and the humidity is maintained within a certain range to ensure the activity of the medicines. Compared with other food products, the requirements for refrigeration conditions are higher.

[0003] Medical refrigerators generally use a vapor compression refrigeration cycle with an internal air-cooled design, regulating the internal temperature by controlling the start and stop of the compressor. The internal temperature decreases and increases with the start and stop of the compressor, but this can easily lead to large temperature fluctuations within the refrigerator.

[0004] To address the issue of temperature fluctuations inside the refrigerator caused by compressor start-up and shutdown, this can be mitigated by extending the compressor's operating time and shortening its shutdown cycle. However, prolonged compressor operation keeps the evaporator in a cooling state for extended periods, making it highly susceptible to frost buildup. Evaporator frost severely impacts system heat transfer performance, increases energy consumption, and causes excessively high temperature and humidity inside the refrigerator, affecting the activity of medicines and reagents and leading to greater losses. Therefore, defrosting is essential for refrigerators, but defrosting the evaporator can also affect temperature fluctuations inside the refrigerator.

[0005] Most medical refrigerators employ either natural defrosting upon shutdown or electric heating element defrosting. Natural defrosting involves the frost layer melting naturally through air circulation within the refrigerator when the compressor stops. Electric heating element defrosting transfers heat from near the heating wire to the evaporator, but most of the heat is absorbed by the fins and the air inside the refrigerator, with only a small portion used to melt the frost. Both methods suffer from uneven and incomplete defrosting, leading to frost buildup and making it easy for the temperature and humidity inside the refrigerator to exceed safe limits.

[0006] Currently, a small number of medical refrigerators also use hot gas defrosting, where the high-temperature, high-pressure refrigerant compressed by the compressor directly enters the evaporator to release heat and defrost. Although hot gas bypass defrosting is highly efficient and thorough, the high-temperature, high-pressure refrigerant releases heat in the evaporator, causing the frost layer to melt rapidly. This poses a risk of temperature and humidity fluctuations inside the refrigerator. Furthermore, during defrosting, the high-temperature, high-pressure refrigerant directly enters the evaporator, where it releases heat and typically becomes a two-phase gas-liquid mixture. When this mixture enters the compressor, it results in higher compressor suction temperatures and a heavier load, potentially causing liquid slugging in the compressor and affecting its lifespan.

[0007] Therefore, in the existing technology, reducing the fluctuation of temperature and humidity inside the chamber while efficiently defrosting the evaporator has become a technical challenge. Summary of the Invention

[0008] The purpose of this application is to provide a refrigeration system capable of defrosting the evaporator and reducing temperature and humidity fluctuations. To achieve the above objectives, one aspect of this application is a refrigeration system comprising a compressor unit, a condenser unit, and an evaporator unit connected in series, wherein the refrigerant flows in the order of compressor unit → condenser unit → evaporator unit → compressor unit. The compressor unit compresses the refrigerant and includes a compressor and a gas-liquid separator. The gas-liquid separator separates the refrigerant output from the evaporator unit into gas and liquid components. The condenser unit cools the refrigerant output from the compressor and includes a first condenser branch and a second condenser branch connected in parallel. In the first condenser branch, a condenser and a first shut-off valve for controlling the on / off state of the first condenser branch are arranged in series. In the second condenser branch, a second shut-off valve for controlling the on / off state of the second condenser branch is provided. The evaporator unit exchanges heat with the outside environment through the refrigerant and includes: a first evaporator branch with a first evaporator; a second evaporator branch with a second evaporator; and a first reversing valve connected to the output terminal of the condenser unit. The system comprises: an input terminal of the first evaporator branch and an input terminal of the second evaporator branch; a second reversing valve connected to the input terminal of the compressor unit, the output terminal of the first evaporator branch, and the output terminal of the second evaporator branch; and an intervalve branch connecting the first reversing valve and the second reversing valve. The first reversing valve has a first mode in which the output terminal of the condenser unit is connected to the input terminal of the first evaporator branch and the input terminal of the second evaporator branch is connected to the intervalve branch; and a second mode in which the output terminal of the condenser unit is connected to the input terminal of the second evaporator branch and the input terminal of the first evaporator branch is connected to the intervalve branch. The second reversing valve has a third mode in which the output terminal of the first evaporator branch is connected to the intervalve branch and the output terminal of the second evaporator branch is connected to the input terminal of the compressor unit; and a fourth mode in which the output terminal of the first evaporator branch is connected to the input terminal of the compressor unit and the output terminal of the second evaporator branch is connected to the intervalve branch.

[0009] According to the aforementioned technical solution, by adjusting the control valve group, the high-temperature and high-pressure refrigerant output by the compressor can bypass the condenser and directly enter the evaporator to be defrosted. While the refrigerant releases heat and cools down, it defrosts the outer surface of the evaporator. At the same time, another evaporator operates normally to maintain the cooling effect on the refrigerator and reduce the fluctuation of temperature and humidity inside the refrigerator.

[0010] In a preferred embodiment, in the first evaporator branch, a first pressure regulating branch and a second pressure regulating branch are provided in parallel on the upstream side of the first evaporator. The first pressure regulating branch includes a first pressure regulating device (first capillary tube) and a third shut-off valve for controlling the on / off state of the first pressure regulating branch. The second pressure regulating branch includes a fourth shut-off valve for controlling the on / off state of the second pressure regulating branch. In the second evaporator branch, a third pressure regulating branch and a fourth pressure regulating branch are provided in parallel on the upstream side of the second evaporator. The third pressure regulating branch includes a second pressure regulating device (second capillary tube) and a fifth shut-off valve for controlling the on / off state of the third pressure regulating branch. The fourth pressure regulating branch includes a sixth shut-off valve for controlling the on / off state of the fourth pressure regulating branch.

[0011] According to the aforementioned technical solution, the refrigerant about to enter the evaporator can be throttled and depressurized through the capillary tube, and the pressure regulating branch where the capillary tube is located can be short-circuited by adjusting the shut-off valve, so that the refrigerant bypasses the capillary tube and enters the evaporator directly.

[0012] In a preferred embodiment, the device further includes a first fan corresponding to the first evaporator and a second fan corresponding to the second evaporator.

[0013] According to the aforementioned technical solution, the fan draws air over the surface of the evaporator and then into the space inside the refrigerator, resulting in a better cooling effect.

[0014] In a preferred embodiment, the following features are provided:

[0015] In the first cooling mode, the first shut-off valve is turned on, the second shut-off valve is turned off, the first reversing valve is in the first mode, the second reversing valve is in the fourth mode, and the first fan is turned on and the second fan is turned off.

[0016] In the second cooling mode, the first shut-off valve is turned on, the second shut-off valve is turned off, the first reversing valve is in the second mode, the second reversing valve is in the third mode, and the first fan stops working while the second fan starts working.

[0017] In the first defrosting mode, the first shut-off valve is closed, the second shut-off valve is opened, the first directional valve is in the first mode, the second directional valve is in the third mode, and the first fan stops operating while the second fan operates; and

[0018] In the second defrosting mode, the first shut-off valve is closed, the second shut-off valve is opened, the first reversing valve is in the second mode, the second reversing valve is in the fourth mode, the first fan is activated, and the second fan is deactivated.

[0019] According to the aforementioned technical solution, both the first and second cooling modes alternate between the two evaporators, meaning only one evaporator is used for cooling, reducing system power consumption and temperature fluctuations. The first and second defrost modes respectively defrost the first and second evaporators. In other words, the cooling and defrosting of different evaporators are controlled by switching the control valve assembly.

[0020] In a preferred embodiment, when the temperature of the first evaporator reaches a preset defrost temperature Th, or the cumulative operating time of the evaporator reaches a preset cumulative operating time th, the first reversing valve and the second reversing valve are switched to enter the first defrost mode; when the temperature of the second evaporator reaches the preset defrost temperature Th, or the cumulative operating time of the evaporator reaches the preset cumulative operating time th, the first reversing valve and the second reversing valve are switched to enter the second defrost mode.

[0021] According to the aforementioned technical solution, by presetting relevant parameters, the refrigeration system can be automatically controlled to enter the first defrost mode and the second defrost mode.

[0022] In a preferred embodiment, it also has the following features:

[0023] In the first dripping mode, after the first defrosting mode ends, the first shut-off valve is turned on, the second shut-off valve is turned off, the first reversing valve is in the second mode, the second reversing valve is in the third mode, and the first fan stops working and the second fan starts working.

[0024] In the second dripping mode, after the second defrosting mode ends, the first shut-off valve is turned on, the second shut-off valve is turned off, the first reversing valve is in the first mode, the second reversing valve is in the fourth mode, the first fan is turned on, and the second fan is turned off.

[0025] In a preferred embodiment, when the temperature in the first evaporator reaches the temperature Tf required to exit the defrost mode, or the defrost time reaches the preset defrost time tf, the first reversing valve is switched to enter the first dripping mode; when the temperature in the second evaporator reaches the temperature Tf required to exit the defrost mode, or the defrost time reaches the preset defrost time tf, the second reversing valve is switched to enter the second dripping mode.

[0026] According to the aforementioned technical solution, after a single evaporator finishes defrosting, it should be stopped for a period of time to allow the water droplets generated during defrosting to drip off fully, thus preventing re-frost formation during subsequent operation and reducing fluctuations in humidity inside the chamber.

[0027] In a preferred embodiment, the first fan is delayed in starting when the first evaporator exits the first dripping mode and enters the first cooling mode for the first time; the second fan is delayed in starting when the second evaporator exits the second dripping mode and enters the second cooling mode for the first time.

[0028] According to the aforementioned technical solution, delaying the start of the fan can prevent the moisture generated during defrosting from being blown into the internal space of the chamber, thereby reducing humidity fluctuations.

[0029] In a preferred embodiment, a water-receiving element is provided below the first evaporator and the second evaporator in the plumb direction to receive water droplets dripping from the first evaporator and the second evaporator; the horizontal projection of the first evaporator and the second evaporator falls within the horizontal projection range of the water-receiving element.

[0030] In a preferred embodiment, the output end of the compressor is connected to an evaporating element, and the refrigerant output from the compressor enters the condenser unit via the evaporating element; wherein the evaporating element is located inside or adjacent to the water receiving element, for accelerating the evaporation of moisture in the water receiving element.

[0031] According to the aforementioned technical solution, it is able to catch water droplets dripping from the surface of the evaporator and use high-temperature and high-pressure refrigerant to accelerate the evaporation of the water droplets. Attached Figure Description

[0032] To more clearly illustrate this application, the accompanying drawings will be described and explained below. Obviously, the drawings described below only illustrate certain aspects of some exemplary embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0033] Figure 1 This is a schematic diagram illustrating the first type of series operation of dual evaporators.

[0034] Figure 2 This is a schematic diagram illustrating the second type of series operation of dual evaporators.

[0035] Figure 3 This is a schematic diagram illustrating only the operation of the first evaporator 3.

[0036] Figure 4 This is a schematic diagram illustrating only the operation of the second evaporator 4.

[0037] Figure 5 This is a schematic diagram illustrating the first defrosting mode.

[0038] Figure 6 This is a schematic diagram illustrating the second defrosting mode.

[0039] Figure 7 This is a flowchart illustrating the defrosting control method.

[0040] Attached image caption:

[0041] 100 compressor unit

[0042] 200 condenser unit

[0043] 300 Evaporator Unit

[0044] 301 First Evaporator Branch

[0045] 302 Second Evaporator Branch

[0046] 1 compressor

[0047] 13 Gas-Liquid Separator

[0048] 2 Condensers

[0049] 21 First condenser branch

[0050] 22 Second condenser branch

[0051] 23 First shut-off valve

[0052] 24 Second shut-off valve

[0053] 3 First Evaporator

[0054] 31 First voltage regulating branch

[0055] 32 Second voltage regulating branch

[0056] 33 First capillary

[0057] 34 First Filter

[0058] 35 Third shut-off valve

[0059] 37 Fourth shut-off valve

[0060] 38 First Wind Turbine

[0061] 4 Second Evaporator

[0062] 40 Fourth voltage regulating branch

[0063] 41 Third voltage regulating branch

[0064] 43 Second capillary

[0065] 44 Second Filter

[0066] 45 Fifth shut-off valve

[0067] 46 Sixth shut-off valve

[0068] 48 Second wind turbine

[0069] 50 valve branch

[0070] 51 First reversing valve

[0071] 52 Second directional valve

[0072] 61 Evaporator

[0073] 62 Evaporating dish Detailed Implementation

[0074] Various exemplary embodiments of this disclosure are described in detail below with reference to the accompanying drawings. The descriptions of the exemplary embodiments are merely illustrative and are in no way intended to limit this disclosure or its application or use. This disclosure may be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided so that this disclosure will be thorough and complete, and will fully express the scope of this disclosure to those skilled in the art. It should be noted that, unless otherwise stated, the relative arrangement of components and steps, numerical expressions, and values ​​set forth in these embodiments should be interpreted as merely exemplary and not as limiting.

[0075] As used in this disclosure, the words “including” or “contains” or similar terms mean that the element preceding the word covers the element listed after the word, and do not exclude the possibility that it may also cover other elements.

[0076] All terms used in this disclosure (including technical or scientific terms) have the same meaning as understood by one of ordinary skill in the art to which this disclosure pertains, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries should be interpreted as having meanings consistent with their meanings in the context of the relevant art, and not as being interpreted with idealized or highly formalized meanings, unless expressly defined herein.

[0077] For components, specific model numbers and other parameters of components not described in detail in this section, the interrelationships between components and control circuits, these may be considered as techniques, methods and devices known to those skilled in the art, but where appropriate, such techniques, methods and devices should be considered part of the specification.

[0078] (Refrigeration system)

[0079] Next, taking the dual evaporator of a refrigerator as an example, refer to... Figure 1 and Figure 2 The composition of the refrigeration system of this application is described. Figure 1 This is a schematic diagram of the first type of series operation of dual evaporators. Figure 2 This is a schematic diagram of the second type of series operation of dual evaporators.

[0080] like Figure 1 As shown, the refrigeration system includes a compressor unit 100, a condenser unit 200, and an evaporator unit 300. The refrigerant flows in the order of compressor unit 100 → condenser unit 200 → evaporator unit 300 → compressor unit 100.

[0081] The compressor unit 100 compresses the refrigerant and includes a compressor 1 and a gas-liquid separator 13, which is used to separate the refrigerant output from the evaporator unit 300 into gas and liquid components.

[0082] The condenser unit 200 cools the refrigerant output by the compressor 1. It has a first condenser branch 21 and a second condenser branch 22 connected in parallel. In the first condenser branch 21, a condenser 2 and a first shut-off valve 23 for controlling the on and off of the first condenser branch 21 are arranged in series. In the second condenser branch 22, a second shut-off valve 24 for controlling the on and off of the second condenser branch 22 is arranged.

[0083] The evaporator unit 300 exchanges heat with the outside through refrigerant and includes: a first evaporator branch 301, which is equipped with a first evaporator 3; and a second evaporator branch 302, which is equipped with a second evaporator 4.

[0084] The refrigeration system also includes a first reversing valve 51, which is connected to the output terminal of the condenser unit 200, the input terminal of the first evaporator branch 301, and the input terminal of the second evaporator branch 302. A second reversing valve 52 is connected to the input terminal of the compressor unit 100, the output terminal of the first evaporator branch 301, and the output terminal of the second evaporator branch 302; and an inter-valve branch 50 connects the first reversing valve 51 and the second reversing valve 52.

[0085] The first reversing valve 51 has a first mode in which the output end of the condenser unit 200 is connected to the input end of the first evaporator branch 301 and the input end of the second evaporator branch 302 is connected to the inter-valve branch 50, and a second mode in which the output end of the condenser unit 200 is connected to the input end of the second evaporator branch 302 and the input end of the first evaporator branch 301 is connected to the inter-valve branch 50. Figure 1 , Figure 2 As shown, the first mode of the first reversing valve 51 is that ports 1A and 1B are connected, and ports 1C and 1D are connected; the second mode is that ports 1A and 1D are connected, and ports 1B and 1C are connected.

[0086] The second reversing valve 52 has a third mode in which the output end of the first evaporator branch 301 is connected to the inter-valve branch 50 and the output end of the second evaporator branch 302 is connected to the input end of the compressor unit 100, and a fourth mode in which the output end of the first evaporator branch 301 is connected to the input end of the compressor unit 100 and the output end of the second evaporator branch 302 is connected to the inter-valve branch 50. Figure 1 , Figure 2 As shown, the third mode of the second reversing valve 52 is that ports 2A and 2B are connected, and ports 2C and 2D are connected; the second mode is that ports 2A and 2D are connected, and ports 2B and 2C are connected.

[0087] (Evaporator branch)

[0088] Continue reading Figure 1 , Figure 2 In the first evaporator branch 301, a first pressure regulating branch 31 and a second pressure regulating branch 32 are connected in parallel on the upstream side of the first evaporator 3. The first pressure regulating branch 31 includes a first capillary tube 33 as a first pressure regulating device and a third shut-off valve 35 for controlling the on / off state of the first pressure regulating branch 31. The second pressure regulating branch 32 includes a fourth shut-off valve 37 for controlling the on / off state of the second pressure regulating branch 32. In addition, the first pressure regulating branch is usually connected in series with a first filter 34 for filtering moisture, dirt and other impurities in the refrigerant.

[0089] In the second evaporator branch 302, a third pressure regulating branch 41 and a fourth pressure regulating branch 42 are connected in parallel on the upstream side of the second evaporator 4. The third pressure regulating branch 41 includes a second capillary tube 43 as a second pressure regulating device and a fifth shut-off valve 45 for controlling the on / off state of the third pressure regulating branch 41. The fourth pressure regulating branch 42 includes a sixth shut-off valve 46 for controlling the on / off state of the fourth pressure regulating branch 42. In addition, the third pressure regulating branch is usually connected in series with a second filter 44 for filtering moisture, dirt and other impurities in the refrigerant.

[0090] Meanwhile, the refrigeration system also has a first fan 38 corresponding to the first evaporator 3 and a second fan 48 corresponding to the second evaporator 4.

[0091] Preferably, a compressor 1 is further provided at its output end. Figure 1 The evaporator tube 61 shown is an evaporation element located within or adjacent to the evaporating dish 62, which serves as a water-receiving element. The evaporating dish 62 collects condensate dripping from the outer surfaces of the first evaporator 3 and the second evaporator 4. The horizontal projections of the first evaporator 3 and the second evaporator 4 fall within the horizontal projection range of the evaporating dish 62. When the high-temperature, high-pressure refrigerant output from the compressor 1 flows through the evaporator tube 61, it heats the condensate in the evaporating dish 62, thereby accelerating its evaporation.

[0092] (Serial operation)

[0093] Next, continue to refer to Figure 1 , Figure 2 A detailed explanation of the operation of dual evaporators in series is provided.

[0094] When rapid cooling is required, the first reversing valve 51 can be switched to the first mode, i.e. Figure 1 Connecting ports 1A and 1B, and ports 1C and 1D, switches the second directional valve 52 to the third mode, i.e. Figure 1 Ports 2A and 2B are connected, and ports 2C and 2D are connected.

[0095] At this time, the first shut-off valve 23 is open and the second shut-off valve 24 is closed. The refrigerant flows from the compressor 1 into the condenser 2 and enters the first evaporator branch 301 through the first reversing valve 51. At this time, the fourth shut-off valve 37 is closed and the third shut-off valve 35 is open. The refrigerant enters the first evaporator 3 after passing through the first filter 34 and the first capillary tube 33. After absorbing heat and rising in temperature in the first evaporator 3, it flows out from the output end of the first evaporator branch 301, enters the intervalve branch 50 through the second reversing valve 52, and then enters the second evaporator branch 302 through the first reversing valve 51.

[0096] Since the refrigerant has already been dried and filtered by the first filter 34 and throttled and depressurized by the first capillary tube 33 before entering the first evaporator 3, it is preferable to close the fifth shut-off valve 45 and open the sixth shut-off valve 46. The refrigerant enters the second evaporator 4 directly through the fourth pressure regulating branch 42. After absorbing heat and rising in temperature in the second evaporator 4, it flows out from the second evaporator branch 302 and flows through the second reversing valve 52 to the compressor 1 for compression.

[0097] At this time, the first evaporator 3 is used as the main evaporator, and the second evaporator 4 is used as the auxiliary evaporator. Because the refrigerant absorbs heat and rises in temperature in the main evaporator before entering the auxiliary evaporator, the temperature of the refrigerant when it enters the main evaporator is lower than the temperature when it enters the auxiliary evaporator. Therefore, the refrigerant is more likely to absorb more heat in the main evaporator, meaning that the cooling effect of the main evaporator is more obvious than that of the auxiliary evaporator.

[0098] In summary, when the first reversing valve 51 is switched to the first mode and the second reversing valve 52 is switched to the third mode, the refrigerant flows sequentially from the compressor 1 into the condenser 2, the first filter 34, the first capillary tube 33, the first evaporator 3, and the second evaporator 4, and finally flows back to the compressor 1. That is, the first evaporator 3 and the second evaporator 4 work in series, which can accelerate the cooling speed and improve the utilization efficiency of the refrigerant's cooling capacity.

[0099] Similarly, such as Figure 2As shown, the first reversing valve 51 can also be switched to the second mode, i.e., ports 1A and 1D are connected, and ports 1B and 1C are connected, and the second reversing valve 52 can be switched to the fourth mode, i.e., ports 2A and 2D are connected, and ports 2B and 2C are connected.

[0100] At this time, the first shut-off valve 23 is open and the second shut-off valve 24 is closed. The refrigerant flows from the compressor 1 into the condenser 2 and enters the second evaporator branch 302 through the first reversing valve 51. At this time, the fifth shut-off valve 45 is open and the sixth shut-off valve 46 is closed. The refrigerant enters the second evaporator 4 after passing through the second filter 44 and the second capillary tube 43. After absorbing heat and rising in temperature in the second evaporator 4, it flows out from the second evaporator branch 302, enters the intervalve branch 50 through the second reversing valve 52, and then enters the first evaporator branch 301 through the first reversing valve 51.

[0101] Since the refrigerant has already undergone drying and filtration by the second filter 44 and throttling and pressure reduction by the second capillary tube 43 before entering the second evaporator 4, it is preferable to close the third shut-off valve 35 and open the fourth shut-off valve 37. The refrigerant then directly enters the first evaporator 3 via the second pressure regulating branch 32. After absorbing heat and heating up in the first evaporator 3, it flows out from the first evaporator branch 301 and enters the compressor 1 via the second reversing valve 52. At this time, the second evaporator 4 is used as the main evaporator, and the first evaporator 3 is used as the auxiliary evaporator.

[0102] In summary, when the first reversing valve 51 is switched to the second mode and the second reversing valve 52 is switched to the fourth mode, the refrigerant flows sequentially from the compressor 1 into the condenser 2, the second filter 44, the second capillary tube 43, the second evaporator 4, and the first evaporator 3, and finally flows back to the compressor 1. That is, the second evaporator 4 and the first evaporator 3 are also in a series operation state, which can accelerate the cooling speed and improve the utilization efficiency of the refrigerant's cooling capacity.

[0103] (Alternating operation)

[0104] Next, refer to Figure 3 , Figure 4 A detailed explanation of the alternating operation of the dual evaporators is provided. Figure 3 This is a schematic diagram showing only the first evaporator 3 in operation. Figure 4 This is a schematic diagram showing only the second evaporator 4 in operation.

[0105] Once the temperature inside the refrigerator reaches near the target value, only one evaporator needs to operate. At this point, the first reversing valve 51 can be switched to the first mode, i.e. Figure 3 Connecting ports 1A and 1B, and ports 1C and 1D, switches the second directional valve 52 to the fourth mode, i.e. Figure 3 Ports 2A and 2D are connected, and ports 2B and 2C are connected.

[0106] Therefore, after the refrigerant enters the condenser 2 from the compressor 1 and is cooled, it flows through the first evaporator branch 301 via the first reversing valve 5. At this time, the fourth shut-off valve 37 is closed and the third shut-off valve 35 is open. The refrigerant enters the first evaporator 3 through the first filter 34 and the first capillary tube 33, absorbs heat and rises in temperature, then flows out from the first evaporator branch 301 and directly enters the compressor 1 via the second reversing valve 52. Under these conditions, the refrigerant output from the compressor 1 no longer flows into the second evaporator 4, that is, the second evaporator 4 stops working, and the corresponding second fan 48 also stops working.

[0107] In addition, see Figure 4 Alternatively, the first reversing valve 51 can be switched to the second mode, i.e., ports 1A and 1D are connected, and ports 1B and 1C are connected, and the second reversing valve 52 can be switched to the third mode, i.e., ports 2A and 2B are connected, and ports 2C and 2D are connected.

[0108] Therefore, after the refrigerant enters the condenser 2 from the compressor 1 and is cooled, it then enters the second evaporator branch 302 via the first reversing valve 51. At this time, the fifth shut-off valve 45 is open and the sixth shut-off valve 46 is closed. The refrigerant enters the second evaporator 4 through the second filter 44 and the second capillary tube 43, absorbs heat and rises in temperature, then flows out from the second evaporator branch 302 and enters the compressor 1 via the second reversing valve 52. Under these conditions, the refrigerant output from the compressor 1 no longer flows into the first evaporator 3, that is, the first evaporator 3 stops working, and the corresponding first fan 38 also stops working.

[0109] Compared to the simultaneous operation of two evaporators, the alternating operation mode can reduce power consumption, reduce the rate of temperature change inside the refrigerator, help maintain the stability of the temperature inside the refrigerator, and reduce the number of times the compressor 1 starts and stops and the temperature fluctuation inside the refrigerator.

[0110] In summary, when the dual evaporators are running alternately, the refrigeration system has a first refrigeration mode, which is to open the first shut-off valve 23, close the second shut-off valve 24, put the first reversing valve 51 in the first mode, put the second reversing valve 52 in the fourth mode, and make the first fan 38 work and the second fan 48 stop working.

[0111] It also has a second cooling mode, which opens the first shut-off valve 23, closes the second shut-off valve 24, puts the first reversing valve 51 in the second mode, puts the second reversing valve 52 in the third mode, and stops the first fan 38 and puts the second fan 48 into operation.

[0112] (Defrosting)

[0113] Next, combined Figure 5 , Figure 6 The defrosting principle will be explained in detail. Figure 5 This is a diagram of the first defrosting mode. Figure 6This is a schematic diagram of the second defrosting mode.

[0114] During the defrosting process, the evaporator that is defrosting replaces condenser 2 to cool the refrigerant, while the other evaporator that is not defrosting operates normally to cool the refrigerator.

[0115] See Figure 5 When the first evaporator 3 needs defrosting, the first shut-off valve 23 is closed and the second shut-off valve 24 is opened. The refrigerant output from the compressor 1 directly enters the first reversing valve 51 via the second condenser branch 22. The first reversing valve 51 switches to the first mode, i.e., ports 1A and 1B are connected, and ports 1C and 1D are connected. The refrigerant enters the first evaporator branch 301 via ports 1A and 1B.

[0116] At this point, the fourth shut-off valve 37 is opened and the third shut-off valve 35 is closed, allowing the refrigerant to directly enter the first evaporator 3 via the second pressure regulating branch 32. In other words, the high-temperature, high-pressure refrigerant output from the compressor 1 enters the first evaporator 3 directly, without being cooled by the condenser 2 or throttled and depressurized by the first capillary tube 33. Subsequently, the high-temperature, high-pressure refrigerant exchanges heat with the frost layer on the outer surface of the first evaporator 3. The frost layer absorbs heat and gradually melts, while the refrigerant inside the first evaporator 3 releases heat and cools down. In other words, the first evaporator 3 replaces the condenser 2 in performing the function of cooling the refrigerant.

[0117] At the same time, preferably, the first fan 38 also stops operating to prevent the fan from blowing the heat released by the refrigerant and the moisture from the melting frost into other spaces inside the refrigerator, thereby reducing fluctuations in temperature and humidity inside the refrigerator.

[0118] After releasing heat and cooling down, the refrigerant enters the second reversing valve 52 from the first evaporator branch 301. At this time, the second reversing valve 52 switches to the third mode, that is, ports 2A and 2B are connected, and ports 2C and 2D are connected. The refrigerant enters the intervalve branch 50 through ports 2A and 2B, and then enters the second evaporator branch 302 from the intervalve branch 50 through ports 1C and 1D of the first reversing valve 51.

[0119] At this point, the refrigerant has not yet undergone filtration and throttling. The fifth shut-off valve 45 is opened, and the sixth shut-off valve 46 is closed. The refrigerant enters the second evaporator 4 through the second filter 44 and the second capillary tube 43. After absorbing heat and heating up in the second evaporator 4, it flows out from the second evaporator branch 302 and enters the compressor 1 through ports 2C and 2D of the second reversing valve 52. During this process, the second evaporator 4 operates normally, performing its refrigeration function.

[0120] Similarly, see Figure 6When the second evaporator 4 needs to be defrosted, first close the first shut-off valve 23 and open the second shut-off valve 24. Then switch the first reversing valve 51 to the second mode, that is, 1A port and 1D port are connected, and 1B port and 1C port are connected; switch the second reversing valve 52 to the fourth mode, that is, 2A port and 2D port are connected, and 2B port and 2C port are connected.

[0121] The high-temperature, high-pressure refrigerant output from compressor 1 directly enters the second evaporator branch 302 via the second condenser branch 22 and ports 1A and 1D of the first reversing valve 51. At this time, the fifth shut-off valve 45 is closed and the sixth shut-off valve 46 is opened, allowing the high-temperature, high-pressure refrigerant to directly enter the second evaporator 4 and exchange heat with the frost layer on the outer surface of the second evaporator 4. The frost layer absorbs heat and melts, while the refrigerant releases heat and cools down.

[0122] Meanwhile, preferably, the second fan 48 is stopped to prevent the fan from blowing the heat released by the refrigerant and the moisture from the melting frost into other spaces inside the refrigerator, thereby reducing fluctuations in temperature and humidity inside the refrigerator.

[0123] The cooled refrigerant flows out from the second evaporator branch 302, enters the intervalve branch 50 through the 2A and 2D ports of the second reversing valve 52, and then enters the first evaporator branch 301 from the intervalve branch 50 through the 1B and 1C ports of the first reversing valve 51.

[0124] At this point, the refrigerant has not yet undergone filtration and throttling. The third shut-off valve 35 is opened, and the fourth shut-off valve 37 is closed. The refrigerant enters the first evaporator 3 through the first filter 34 and the first capillary tube 33. After absorbing heat and heating up in the first evaporator 3, it flows out from the first evaporator branch 302 and enters the compressor 1 through ports 2B and 2C of the second reversing valve 52. During this process, the first evaporator 3 operates normally, performing its refrigeration function.

[0125] In summary, this refrigeration system has Figure 5 The first defrosting mode shown is such that even if the first shut-off valve 23 is closed and the second shut-off valve 24 is open, the first reversing valve 51 is in the first mode, the second reversing valve 52 is in the third mode, and the first fan 38 stops working while the second fan 48 works.

[0126] It also has Figure 6 The second defrosting mode shown closes the first shut-off valve 23, opens the second shut-off valve 24, puts the first reversing valve 51 in the second mode, puts the second reversing valve 52 in the fourth mode, and makes the first fan 38 work and the second fan 48 stop working.

[0127] In other words, during defrosting, the first shut-off valve 23 is closed and the second shut-off valve 24 is opened, thus blocking the condenser 2. Then, by switching the first reversing valve 51 and the second reversing valve 52, the refrigerant output from the compressor 1, which has not been cooled by the condenser 2, enters the evaporator that needs to be defrosted directly through the second condenser branch 22 to exchange heat with the frost layer. At this time, the fan corresponding to the evaporator stops running. The refrigerant, after releasing heat and cooling, then enters the undefrosted evaporator to perform its refrigeration function and is finally input into the compressor 1.

[0128] It should be noted that the refrigerant flowing from the second condenser branch 22 directly enters the evaporator that needs defrosting, without passing through the capillary tube for throttling and pressure reduction. This is primarily due to three considerations: First, to avoid the refrigerant's final pressure being too low due to both the first capillary tube 33 and the second capillary tube 43 being operational, resulting in an excessively high compressor pressure ratio and increased energy consumption. Second, to avoid refrigerant temperature loss, as the refrigerant temperature will also decrease after pressure reduction through the capillary tube, weakening the heat-releasing defrosting effect. Third, high-pressure refrigerant is more conducive to heat release, accelerating the defrosting speed.

[0129] Compared to traditional automatic defrosting and electric heating element defrosting methods, this application injects high-temperature, high-pressure refrigerant directly into the frosted evaporator, resulting in faster, more efficient, and more thorough defrosting. Traditional hot-gas defrosting methods, where high-temperature, high-pressure refrigerant is directly introduced into the evaporator, result in the following: Firstly, the refrigerant releases heat within the evaporator, causing a rapid rise in the internal temperature. Secondly, the melting of the frost layer absorbs heat, leading to increased moisture on the evaporator's surface and higher humidity levels inside the refrigerator, causing significant temperature and humidity fluctuations. Furthermore, in traditional hot-gas defrosting, the high-temperature, high-pressure refrigerant output from compressor 1 is typically gaseous. After releasing heat directly into the evaporator, the gaseous refrigerant usually becomes a two-phase mixture (gas and liquid). This two-phase refrigerant then enters compressor 1, resulting in higher suction temperatures, heavier loads, and potential liquid slugging, thus affecting its lifespan.

[0130] In contrast, on the one hand, this application maintains the normal operation and refrigeration function of other evaporators while defrosting the evaporator, preventing the temperature and humidity inside the refrigerator from rising too quickly and reducing fluctuations in temperature and humidity. On the other hand, the high-temperature and high-pressure refrigerant output by the compressor 1 of this application directly enters the defrosted evaporator to release heat and then flows out, where it is cooled and depressurized through a capillary tube before entering the undefrosted evaporator to absorb heat and vaporize, thus avoiding the problems of excessively high compressor suction temperature and liquid slugging.

[0131] Understandably, since condenser 2 stops working, the refrigeration system uses the frost layer on the outer surface of the defrosted evaporator as a cold source to cool the high-temperature, high-pressure refrigerant output from compressor 1. The cooled refrigerant is then introduced into the undefrosted evaporator to cool the refrigerator compartment. In other words, the excessive cooling previously caused frost to form on the evaporator surface; in defrost mode, this frost layer is used as a cold source to cool the refrigerator compartment, achieving a reuse of cooling capacity and saving system power to some extent.

[0132] (Defrosting control methods)

[0133] Next, combined Figure 7 The defrosting control method for evaporators is explained in detail. Figure 7 This is a flowchart of the defrosting control method.

[0134] First, select the dual-evaporator operating mode. For example... Figure 7 As shown, the temperature difference ΔT between the actual temperature T1 inside the chamber and the set temperature Ts inside the chamber, as well as the ambient temperature T0 outside the chamber, are measured. The operating mode of the dual evaporators is selected based on the temperature difference ΔT and the ambient temperature T0. As a preferred option, the relationship between the dual evaporators operating in series or alternately and the temperature difference ΔT and the ambient temperature T0 is shown in Table 1.

[0135] As shown in Table 1, when the temperature difference ΔT is between 0 and 2℃, the two evaporators operate alternately regardless of the external ambient temperature T0, because the actual internal temperature T1 is relatively close to the set internal temperature Ts, and there is no need for both evaporators to provide excessive cooling capacity simultaneously. When the temperature difference ΔT is between 8 and 36℃, the two evaporators operate in series regardless of the external ambient temperature T0, because the difference between the actual internal temperature T1 and the set internal temperature Ts is relatively large, requiring a faster cooling rate.

[0136] When the temperature difference ΔT is between 2-5℃ or 5-8℃, it is necessary to make a comprehensive judgment based on the magnitude of the ambient temperature T0 outside the chamber. If the ambient temperature T0 is too high, the series operation mode should be adopted; otherwise, the alternating operation mode should be adopted.

[0137] When two evaporators are connected in series, the first evaporator 3 is usually selected as the main evaporator and the second evaporator 4 as the auxiliary evaporator. Preferably, the compressor 1 is controlled to run at its maximum speed. When the temperature inside the chamber drops to the required level, the control valve group, which includes multiple control valves such as shut-off valves (23, 24, 37, 35, 45, 46) and reversing valves (51, 52), is switched to allow the two evaporators to enter an alternating operation state.

[0138] Table 1 Dual Evaporator Operation Control Table

[0139]

[0140] Next, the speed of compressor 1 is controlled. After the dual evaporators enter alternating operation, the speed of compressor 1 is adjusted according to the temperature difference ΔT and the ambient temperature T0 outside the chamber to shorten the downtime of compressor 1 and ensure the uniformity of temperature inside the chamber. As a preferred scheme, the speed control of compressor 1 during the alternating operation of the dual evaporators is shown in Table 2.

[0141] As shown in Table 2, when the temperature difference ΔT is between 0 and 0.3℃, the speed of compressor 1 varies within the range of 8% to 15% of its maximum speed, depending on the ambient temperature T0 outside the chamber. This is because the actual temperature T1 inside the chamber is close to the set temperature Ts inside the chamber, which allows for a reduction in the speed of compressor 1 to save energy, reduce cooling capacity, and avoid excessive cooling in a short period of time, thus shutting down compressor 1.

[0142] Similarly, when the temperature difference ΔT is between 0.3 and 0.8℃, the compressor 1 operates at 12%-20% of its maximum speed, depending on the ambient temperature T0. When the temperature difference ΔT is between 0.8 and 2℃, the compressor 1 operates at 20%-32% of its maximum speed, again depending on the ambient temperature T0. When the temperature difference ΔT is between 2 and 5℃, the compressor 1 operates at half its maximum speed, and when the temperature difference ΔT is between 5 and 8℃, the compressor 1 operates at its maximum speed to accelerate the cooling rate.

[0143] Table 2 Compressor Speed ​​Control Table During Alternating Operation of Dual Evaporators

[0144]

[0145] Next, it is determined whether defrosting should be performed. Taking the first evaporator 3 as an example, preferably, when its outer surface temperature reaches the preset defrost temperature Th, or its cumulative operating time reaches the preset cumulative operating time th, the control valve group switches to the aforementioned first defrost mode. In the first defrost mode, the condenser 2 does not work, and the high-temperature, high-pressure refrigerant output by the compressor 1 passes through... Figure 5 The second condenser branch 22, the first reversing valve 51, and the second pressure regulating branch 32 shown directly enter the first evaporator 1 to exchange heat with the frost layer. The refrigerant, after releasing heat and cooling, then enters the second evaporator 4 to cool the refrigerator. At this time, the first fan 38 stops running. Defrosting the second evaporator 4 is done in the same way, which will not be described in detail here.

[0146] Preferably, defrosting is performed in a state where the two evaporators operate alternately. For example, during alternating operation, assuming the first evaporator 3 is cooling while the second evaporator 4 is not working, the first defrost mode for defrosting the first evaporator 3 is activated. Since the second evaporator 4 was previously stopped and no refrigerant flowed in for cooling, it has a relatively high temperature. Therefore, when the first defrost mode is activated, the refrigerant flowing from the first evaporator 3 enters the second evaporator 4, absorbs more heat, and after being compressed by the compressor 1, it enters the first evaporator 3, thus having a higher temperature, thereby accelerating the defrosting speed and effect of the first evaporator 3.

[0147] Next, it is determined whether to stop defrosting. Taking the first evaporator 3 as an example, preferably, when the temperature of the outer surface of the first evaporator 3 reaches the defrost mode exit temperature Tf, or the defrost time reaches the preset defrost time tf, the control valve group switches to stop defrosting. Further, it is preferable to switch the control valve group to enter the first dripping mode. If defrosting the second evaporator 4, then after stopping defrosting, the second dripping mode is entered.

[0148] The principle of the first evaporator 3 entering the first dripping mode after defrosting is as follows: Figure 4 When the first shut-off valve 23 is open and the second shut-off valve 24 is closed, the condenser 2 starts to work; the first reversing valve 51 is in the second mode and the second reversing valve 52 is in the third mode. The undefrosted second evaporator 4 and the corresponding second fan 48 continue to run. The defrosted first evaporator 3 and the first fan 38 stop working to allow more time for the water generated by the melting frost to drip more fully, reducing the humidity on the outer surface of the first evaporator 3, reducing the risk of the first evaporator 3 frosting again during subsequent cooling, and also preventing the first fan 38 from blowing moisture into other spaces inside the box and increasing the humidity fluctuation inside the box.

[0149] The principle of the second evaporator 4 entering the second dripping mode after defrosting is as follows: Figure 3 When the first shut-off valve 23 is open and the second shut-off valve 24 is closed, the condenser 2 starts to work; the first reversing valve 51 is in the first mode and the second reversing valve 52 is in the fourth mode. The first evaporator 3 that has not been defrosted and the corresponding first fan 38 continue to run. The second evaporator 4 that has been defrosted and the second fan 48 stop working to allow more time for the water generated by the melting of the frost to drip more fully, reduce the humidity on the outer surface of the second evaporator 4, reduce the risk of the second evaporator 4 frosting again when it cools down, and also prevent the second fan 48 from blowing moisture into other spaces inside the box and increasing the humidity fluctuation inside the box.

[0150] Next, after the first / second dripping mode ends, the system continues to operate in alternating dual-evaporator mode. As a preferred option, during the first run of the evaporator after defrosting, due to the significant amount of moisture on its outer surface after defrosting, the fan corresponding to that evaporator is delayed in starting for a period of time to ensure that the humidity inside the refrigerator does not exceed the standard. This delayed fan operation is cancelled at the start of the next alternating dual-evaporator cycle.

[0151] It should be noted that when users open the door to retrieve or store medicine, the temperature difference ΔT changes, causing a change in the operation mode of the dual evaporators. For example, when switching from alternating operation to series operation, the evaporator with the lower temperature is preferred as the main evaporator. For instance, if the second evaporator 4 has a lower temperature than the first evaporator 3, then... Figure 2 As shown, the first reversing valve 51 is switched to the second mode and the second reversing valve 52 is switched to the fourth mode. This allows the refrigerant output from the condenser 2 to flow through the first reversing valve 51, the second evaporator branch 302, the second filter 44, and the second capillary tube 43 into the second evaporator 4. The refrigerant then flows out from the second evaporator branch 302, through the second reversing valve 52, the inter-valve branch 50, and the second pressure regulating branch 32, before entering the first evaporator 3. Evaporators with lower temperatures have a higher risk of frosting. Using this as the main evaporator allows for timely defrosting, avoiding frequent switching to defrosting during temperature increases, which would affect the cooling rate.

[0152] Furthermore, when defrosting is detected during evaporator operation, as the control valve group switches to defrosting mode, the compressor 1 preferably operates at the predetermined speed of the previous operation and changes accordingly with the temperature difference ΔT.

[0153] In summary, by switching the control valve group, multiple evaporators can be switched between different states such as series operation, alternating operation, and cooling, defrosting, and dripping. Series operation can quickly cool down, while alternating operation can save power, reduce the number of times compressor 1 starts and stops, and maintain a stable temperature inside the refrigerator. When switching to the first defrost mode / second defrost mode, condenser 2 stops working, and high-temperature, high-pressure refrigerant is directly input to the defrosting evaporator to release heat and defrost. The fan corresponding to the evaporator also stops running, while the evaporators that are not defrosted continue to work normally to maintain the cooling function, reducing the fluctuations in temperature and humidity inside the refrigerator caused by heat release defrosting.

[0154] It should be understood that the specific embodiments described above are only used to explain this application, and the scope of protection of this application is not limited thereto. Any changes, substitutions, or combinations made by those skilled in the art within the scope of the technology disclosed in this application, based on the technical solution and inventive concept of this application, should be covered within the scope of protection of this application.

Claims

1. A refrigeration system comprising a compressor unit, a condenser unit, and an evaporator unit connected in series, wherein a refrigerant flows in the order of compressor unit → condenser unit → evaporator unit → compressor unit. The compressor unit compresses the refrigerant and includes a compressor and a gas-liquid separator. The gas-liquid separator is used to separate the refrigerant output from the evaporator unit into gas and liquid components. The refrigeration system is characterized in that, The condenser unit cools the refrigerant output from the compressor. It has a first condenser branch and a second condenser branch connected in parallel. In the first condenser branch, a condenser and a first shut-off valve for controlling the on / off state of the first condenser branch are arranged in series. In the second condenser branch, a second shut-off valve for controlling the on / off state of the second condenser branch is provided. The evaporator unit exchanges heat with the outside environment through refrigerant and has the following features: The first evaporator branch is equipped with a first evaporator; The second evaporator branch is equipped with a second evaporator; The first reversing valve is connected to the output terminal of the condenser unit, the input terminal of the first evaporator branch, and the input terminal of the second evaporator branch, respectively. The second reversing valve is connected to the input terminal of the compressor unit, the output terminal of the first evaporator branch, and the output terminal of the second evaporator branch, respectively; and The valve branch connects the first directional control valve and the second directional control valve. The first reversing valve has a first mode in which the output terminal of the condenser unit is connected to the input terminal of the first evaporator branch and the input terminal of the second evaporator branch is connected to the inter-valve branch, and a second mode in which the output terminal of the condenser unit is connected to the input terminal of the second evaporator branch and the input terminal of the first evaporator branch is connected to the inter-valve branch. The second reversing valve has a third mode in which the output end of the first evaporator branch is connected to the intervalve branch and the output end of the second evaporator branch is connected to the input end of the compressor unit, and a fourth mode in which the output end of the first evaporator branch is connected to the input end of the compressor unit and the output end of the second evaporator branch is connected to the intervalve branch. In the first evaporator branch, a first pressure regulating branch and a second pressure regulating branch are provided in parallel on the upstream side of the first evaporator. The first pressure regulating branch includes a first pressure regulating device and a third shut-off valve for controlling the on / off state of the first pressure regulating branch. The second pressure regulating branch includes a fourth shut-off valve for controlling the on / off state of the second pressure regulating branch. In the second evaporator branch, a third pressure regulating branch and a fourth pressure regulating branch are provided in parallel on the upstream side of the second evaporator. The third pressure regulating branch includes a second pressure regulating device and a fifth shut-off valve for controlling the on / off state of the third pressure regulating branch. The fourth pressure regulating branch includes a sixth shut-off valve for controlling the on / off state of the fourth pressure regulating branch.

2. The refrigeration system according to claim 1, characterized in that: It also has a first fan corresponding to the first evaporator and a second fan corresponding to the second evaporator.

3. The refrigeration system according to claim 2, characterized in that, have: In the first cooling mode, the first shut-off valve is turned on, the second shut-off valve is turned off, the first reversing valve is in the first mode, the second reversing valve is in the fourth mode, and the first fan is turned on and the second fan is turned off. In the second cooling mode, the first shut-off valve is turned on, the second shut-off valve is turned off, the first reversing valve is in the second mode, the second reversing valve is in the third mode, and the first fan stops working while the second fan starts working. In the first defrosting mode, the first shut-off valve is closed, the second shut-off valve is opened, the first reversing valve is in the first mode, the second reversing valve is in the third mode, and the first fan stops working while the second fan starts working. as well as In the second defrosting mode, the first shut-off valve is closed, the second shut-off valve is opened, the first reversing valve is in the second mode, the second reversing valve is in the fourth mode, the first fan is activated, and the second fan is deactivated.

4. The refrigeration system according to claim 3, characterized in that: When the temperature of the first evaporator reaches the preset defrost temperature Th, or the cumulative running time of the evaporator reaches the preset cumulative running time th, the first reversing valve and the second reversing valve are switched to enter the first defrost mode. When the temperature of the second evaporator reaches the preset defrost temperature Th, or the cumulative operating time of the evaporator reaches the preset cumulative operating time th, the first reversing valve and the second reversing valve are switched to enter the second defrost mode.

5. The refrigeration system according to claim 3, characterized in that, have: In the first dripping mode, after the first defrosting mode ends, the first shut-off valve is turned on, the second shut-off valve is turned off, the first reversing valve is in the second mode, the second reversing valve is in the third mode, and the first fan stops working and the second fan starts working. In the second dripping mode, after the second defrosting mode ends, the first shut-off valve is turned on, the second shut-off valve is turned off, the first reversing valve is in the first mode, the second reversing valve is in the fourth mode, the first fan is turned on, and the second fan is turned off.

6. The refrigeration system according to claim 5, characterized in that: When the temperature in the first evaporator reaches the temperature Tf required to exit the defrost mode, or when the defrost time reaches the preset defrost time tf, the first reversing valve is switched to enter the first dripping mode. When the temperature in the second evaporator reaches the temperature Tf required to exit the defrost mode, or when the defrost time reaches the preset defrost time tf, the second reversing valve is switched to enter the second dripping mode.

7. The refrigeration system according to claim 6, characterized in that: The first fan starts with a delay when the first evaporator exits the first dripping mode and enters the first cooling mode for the first time. The second fan starts with a delay when the second evaporator exits the second dripping mode and enters the second cooling mode for the first time.

8. The refrigeration system according to claim 1, characterized in that: A water-receiving element is provided below the first evaporator and the second evaporator in the vertical direction to receive water droplets dripping from the first evaporator and the second evaporator; the horizontal projection of the first evaporator and the second evaporator falls within the horizontal projection range of the water-receiving element.

9. The refrigeration system according to claim 8, characterized in that: The compressor output is connected to an evaporator element, and the refrigerant output from the compressor enters the condenser unit via the evaporator element; The evaporation element is located inside or adjacent to the water receiving element, and is used to accelerate the evaporation of water in the water receiving element.

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