A refrigeration unit, a refrigeration device and a defrosting control method thereof

Abstract

The present invention discloses a refrigeration unit, a refrigeration device and a defrosting control method thereof, which relate to the field of refrigeration devices, and solve the problems in the prior art that defrosting is still carried out in the case of no frost during the defrosting control process of the refrigeration unit, resulting in an increase in the temperature of the storage, an increase in the energy consumption of the unit, and difficulty in accurately matching the most difficult defrosting position. The refrigeration unit includes a compressor, a four-way reversing valve, a condenser, an evaporator and a defrosting pipe. The defrosting pipe is located at the bottom of the evaporator, and both ends of the defrosting pipe are respectively connected to the four-way reversing valve and the evaporator. The exhaust port of the compressor, the four-way reversing valve, the condenser, the evaporator, the defrosting pipe, the four-way reversing valve and the suction port of the compressor are connected in sequence to form a first refrigerant circuit; the exhaust port of the compressor, the four-way reversing valve, the defrosting pipe, the evaporator, the condenser, the four-way reversing valve and the suction port of the compressor are connected in sequence to form a second refrigerant circuit. The refrigeration unit can improve the uniformity of defrosting of the entire evaporator, increase the defrosting speed and reduce the defrosting energy consumption.

Description

Technical Field

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

[0002] The temperature in a low-temperature cold storage is generally maintained at about -18°C. At such a low temperature, the refrigeration unit is always in a frosting condition. The frosting and defrosting process is an essential process for the refrigeration unit. Therefore, the reliability of frosting and defrosting of the refrigeration unit must be ensured. However, currently, the temperature inside a low-temperature cold storage is usually about -18°C. When the unit operates for a long time and the humidity inside the cold storage is high, the evaporator frosts severely and the frost layer is thick. When the refrigeration unit starts hot gas defrosting, the high-temperature refrigerant in the hot gas defrosting pipe is used to defrost the evaporator, which has the advantage of fast defrosting speed. However, the frost layer and defrosting water on the upper part of the evaporator will accumulate at the bottom of the evaporator under the action of gravity, resulting in the upper part of the evaporator completing defrosting first and the lower part completing defrosting later.

[0003] Currently, there are two conventional ways to exit defrosting: one is to judge whether to exit the defrosting process according to the defrosting duration. Specifically, the unit judges whether to exit defrosting according to the longest defrosting time measured actually. Although this defrosting exit condition can ensure that the evaporator is defrosted cleanly, it often causes the unit to defrost even when there is no frost, resulting in an increase in the cold storage temperature and the energy consumption of the unit. The other is to judge whether to exit the defrosting process according to the temperature of the first temperature sensor. Specifically, this method generally arranges the first temperature sensor at the most difficult position to defrost the evaporator. When the temperature of the temperature sensor at this position reaches the preset temperature, the unit exits defrosting. Although this defrosting exit method can defrost when there is frost and not defrost when there is no frost, it is necessary to accurately match the most difficult defrosting position. If the most difficult defrosting position is not accurately matched, it is very easy to cause the situation that the evaporator is not defrosted cleanly.

[0004] Therefore, it is urgent to improve the low-temperature hot gas unit and its defrosting control method in the prior art. Summary of the Invention

[0005] One of the purposes of the present invention is to propose a refrigeration unit, which solves the technical problems in the prior art that the refrigeration unit still defrosts when there is no frost during the defrosting control process, resulting in an increase in the cold storage temperature and the energy consumption of the unit, and it is difficult to accurately match the most difficult defrosting position. Many technical effects that can be produced by the preferred technical solution of the present invention are described in detail below.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The refrigeration unit of the present invention includes a compressor, a four-way reversing valve, a condenser, an evaporator, and a defrosting pipe. The defrosting pipe is located at the bottom of the evaporator, and both ends of the defrosting pipe are respectively connected to the four-way reversing valve and the evaporator. When the refrigeration unit is in the refrigeration mode, the exhaust port of the compressor, the four-way reversing valve, the condenser, the evaporator, the defrosting pipe, the four-way reversing valve, and the suction port of the compressor are sequentially connected to form a first refrigerant circuit; when the refrigeration unit is in the defrosting mode, the exhaust port of the compressor, the four-way reversing valve, the defrosting pipe, the evaporator, the condenser, the four-way reversing valve, and the suction port of the compressor are sequentially connected to form a second refrigerant circuit.

[0008] According to a preferred embodiment, the number of the defrosting pipes is multiple, the multiple defrosting pipes are arranged in parallel, and the defrosting pipes cover the bottom of the evaporator.

[0009] According to a preferred embodiment, the refrigeration unit further includes a suction filter and a suction pipe. The suction filter and the suction pipe are located between the four-way reversing valve and the defrosting pipe, and the cross-sectional area of the suction pipe is the same as the sum of the cross-sectional areas of the multiple defrosting pipes.

[0010] According to a preferred embodiment, the refrigeration unit further includes a first temperature sensor. The first temperature sensor is located at the evaporator, and the first temperature sensor is used to detect the temperature of the surface of the evaporator.

[0011] According to a preferred embodiment, the refrigeration unit further includes a second temperature sensor. The second temperature sensor is located at the evaporator, and the second temperature sensor is used to detect the temperature inside the cold storage.

[0012] According to a preferred embodiment, the refrigeration unit further includes an electronic expansion valve. The electronic expansion valve is arranged between the condenser and the evaporator, and the electronic expansion valve is used to throttle the refrigerant flowing through.

[0013] According to a preferred embodiment, the refrigeration unit further includes a third temperature sensor, a pressure sensor, and a fourth temperature sensor. Among them, the third temperature sensor is located between the evaporator and the defrosting pipe, and the third temperature sensor is used to detect the temperature at the outlet of the evaporator; the pressure sensor and the fourth temperature sensor are located at the suction port of the compressor, and the pressure sensor and the fourth temperature sensor are respectively used to detect the refrigerant pressure and temperature at the suction port of the compressor.

[0014] The refrigeration unit provided by the present invention has at least the following beneficial technical effects:

[0015] The refrigeration unit of the present invention includes a compressor, a four-way reversing valve, a condenser, an evaporator and a defrosting pipe. The defrosting pipe is located at the bottom of the evaporator, and both ends of the defrosting pipe are respectively connected to the four-way reversing valve and the evaporator. When the refrigeration unit is in the defrosting mode, the high-temperature refrigerant ejected by the compressor first enters the defrosting pipe at the bottom of the evaporator to defrost the bottom of the evaporator, and then enters the evaporator for defrosting, thereby improving the uniformity of defrosting of the entire evaporator, increasing the defrosting speed and reducing the defrosting energy consumption. It can avoid the problem that the evaporator still defrosts when there is no frost, resulting in an increase in the temperature of the storage and an increase in the energy consumption of the unit, and can also avoid the problem that the most difficult defrosting position of the evaporator is not accurately matched, resulting in incomplete defrosting of the evaporator. That is, the refrigeration unit of the present invention solves the technical problems in the prior art that in the defrosting control process of the refrigeration unit, defrosting still occurs when there is no frost, resulting in an increase in the temperature of the storage, an increase in the energy consumption of the unit, and difficulty in accurately matching the most difficult defrosting position.

[0016] The second object of the present invention is to propose a refrigeration device.

[0017] The refrigeration device of the present invention includes the refrigeration unit described in any one of the technical solutions of the present invention.

[0018] The refrigeration device provided by the present invention has at least the following beneficial technical effects:

[0019] The refrigeration device of the present invention, since it includes the refrigeration unit of any one of the technical solutions of the present invention, has the advantages of uniform defrosting of the evaporator, increased defrosting speed and reduced energy consumption when the refrigeration device of the present invention defrosts.

[0020] The third object of the present invention is to propose a defrosting control method for a refrigeration device.

[0021] The defrosting control method for the refrigeration device of any one of the technical solutions of the present invention includes the following steps:

[0022] Obtain the temperature of the cold storage.

[0023] Compare the obtained temperature of the cold storage with the preset value of the cold storage temperature.

[0024] When the obtained temperature of the cold storage is less than the preset value of the cold storage temperature, the refrigeration device starts the defrosting mode.

[0025] According to a preferred embodiment, before the refrigeration device enters the defrosting mode, it further includes the following steps:

[0026] Obtain the temperature of the evaporator surface.

[0027] Compare the obtained temperature of the evaporator surface with the preset value of the evaporator surface temperature.

[0028] When the temperature of the evaporator surface obtained within the preset time range is less than the preset value of the evaporator surface temperature, the refrigeration equipment starts the defrosting mode.

[0029] According to a preferred embodiment, before the refrigeration equipment enters the defrosting mode, the following steps are further included:

[0030] Obtain the evaporation temperature of the refrigerant in the evaporator;

[0031] Compare the obtained evaporation temperature of the refrigerant in the evaporator with the temperature of the cold storage;

[0032] When the difference between the obtained evaporation temperature of the refrigerant in the evaporator and the cold storage temperature is within the preset range, the refrigeration equipment starts the defrosting mode.

[0033] According to a preferred embodiment, when T 库温 ≥T 第一预设库温 , and T 蒸发 ≤(T 库温 -T 化霜进入温差1 ), the refrigeration equipment starts the defrosting mode;

[0034] When T 第二预设库温 ≤T 库温 <T 第一预设库温 , and T 蒸发 ≤(T 库温 -T 化霜进入温差2 ), the refrigeration equipment starts the defrosting mode;

[0035] When T 库温 <T 第二预设库温 , and T 蒸发 ≤(T 库温 -T 化霜进入温差3 ), the refrigeration equipment starts the defrosting mode;

[0036] Wherein, T 库温 is the temperature of the cold storage, T 第一预设库温 is the first preset cold storage temperature, T 第二预设库温 is the second preset cold storage temperature, T 蒸发 is the evaporation temperature of the refrigerant in the evaporator; T 化霜进入温差1 is the first defrosting entry temperature difference, T 化霜进入温差2 is the second defrosting entry temperature difference, T 化霜进入温差3 is the third defrosting entry temperature difference.

[0037] According to a preferred embodiment, the defrosting control method of the refrigeration equipment further includes the following steps:

[0038] Obtain the defrosting duration of the refrigeration equipment;

[0039] Compare the obtained defrosting duration of the refrigeration equipment with the preset value of the defrosting duration;

[0040] Determine the time for the refrigeration device to enter the defrost mode next time based on the comparison result between the obtained defrost duration of the refrigeration device and the preset value of the defrost duration.

[0041] According to a preferred embodiment, when t 化霜 ≤t 预设 -t, the time for the refrigeration device to enter the defrost mode next time is extended by 10 min;

[0042] t 预设 -t < t 化霜 ≤t 预设 , the time for the refrigeration device to enter the defrost mode next time is extended by 5 min;

[0043] t 预设 <t 化霜 ≤t 预设 +2t, the time for the refrigeration device to enter the defrost mode next time remains unchanged;

[0044] t 预设 +2t < t 化霜 ≤t 预设 +4t, the time for the refrigeration device to enter the defrost mode next time is shortened by 2 min;

[0045] t 预设 +4t < t 化霜 ≤t 预设 +6t, the time for the refrigeration device to enter the defrost mode next time is shortened by 4 min;

[0046] t 预设 +6t < t 化霜 , the time for the refrigeration device to enter the defrost mode next time is shortened by 6 min;

[0047] Wherein, t 化霜 is the defrost duration of the refrigeration device, t 预设 is the preset value of the defrost duration, and t is the deviation value.

[0048] According to a preferred embodiment, the defrost control method for the refrigeration device further includes the following steps:

[0049] Calculate the superheat degree of the evaporator based on the difference between the temperature at the outlet of the evaporator and the saturation temperature corresponding to the suction pressure at the suction port of the compressor;

[0050] Adjust the superheat degree set value of the refrigeration device and make the refrigerant a saturated gas state at the outlet of the evaporator.

[0051] The defrost control method for the refrigeration device provided by the present invention has at least the following beneficial technical effects:

[0052] The defrost control method of the refrigeration equipment according to any one of the technical solutions of the present invention includes obtaining the temperature of the cold storage, comparing the obtained temperature of the cold storage with the preset temperature value of the cold storage, and when the obtained temperature of the cold storage is less than the preset temperature value of the cold storage, starting the defrost mode of the refrigeration equipment, which can realize the defrosting treatment of the evaporator; further, the defrost control method of the refrigeration equipment according to any one of the technical solutions of the present invention also has the advantages of uniform defrosting of the evaporator, increased defrost speed and reduced energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0054] Figure 1 is a schematic diagram of a preferred embodiment of the refrigeration unit of the present invention;

[0055] Figure 2 is a flowchart of a preferred embodiment of the defrost control method of the refrigeration equipment of the present invention.

[0056] In the figure: 1. Compressor; 2. Four-way reversing valve; 3. Condenser; 4. Evaporator; 5. Defrosting pipe; 6. Suction filter; 7. Suction pipe; 8. First temperature sensor; 9. Second temperature sensor; 10. Electronic expansion valve; 11. Third temperature sensor; 12. Pressure sensor; 13. Fourth temperature sensor; 14. Gas-liquid separator; 15. Dry filter. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0057] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art without creative efforts based on the embodiments of the present invention belong to the scope protected by the present invention.

[0058] The following combines the specification Figure 1 and 2 and Embodiments 1 to 3 to describe the refrigeration unit, refrigeration equipment and their defrost control methods of the present invention in detail.

[0059] Embodiment 1

[0060] This embodiment describes the refrigeration unit of the present invention in detail.

[0061] The refrigeration unit of this embodiment includes a compressor 1, a four-way reversing valve 2, a condenser 3, an evaporator 4, and a defrosting pipe 5. The defrosting pipe 5 is located at the bottom of the evaporator 4, and both ends of the defrosting pipe 5 are respectively connected to the four-way reversing valve 2 and the evaporator 4, as Figure 1 shown. When the refrigeration unit is in the refrigeration mode, the exhaust port of the compressor 1, the four-way reversing valve 2, the condenser 3, the evaporator 4, the defrosting pipe 5, the four-way reversing valve 2, and the suction port of the compressor 1 are sequentially connected to form a first refrigerant circuit; when the refrigeration unit is in the defrosting mode, the exhaust port of the compressor 1, the four-way reversing valve 2, the defrosting pipe 5, the evaporator 4, the condenser 3, the four-way reversing valve 2, and the suction port of the compressor 1 are sequentially connected to form a second refrigerant circuit.

[0062] The refrigeration unit of this embodiment includes a compressor 1, a four-way reversing valve 2, a condenser 3, an evaporator 4, and a defrosting pipe 5. The defrosting pipe 5 is located at the bottom of the evaporator 4, and both ends of the defrosting pipe 5 are respectively connected to the four-way reversing valve 2 and the evaporator 4. When the refrigeration unit is in the defrosting mode, the high-temperature refrigerant ejected by the compressor 1 first enters the defrosting pipe 5 at the bottom of the evaporator 4 to defrost the bottom of the evaporator 4, and then enters the evaporator 4 for defrosting, thereby improving the uniformity of defrosting of the entire evaporator 4, increasing the defrosting speed, and reducing the defrosting energy consumption. It can avoid the problem that the evaporator 4 still defrosts when there is no frost, resulting in an increase in the storage temperature and an increase in the energy consumption of the unit, and can also avoid the problem that the most difficult defrosting position of the evaporator 4 is not accurately matched, resulting in incomplete defrosting of the evaporator 4. That is, the refrigeration unit of this embodiment solves the technical problems in the prior art that during the defrosting control process of the refrigeration unit, defrosting still occurs when there is no frost, resulting in an increase in the storage temperature, an increase in the energy consumption of the unit, and difficulty in accurately matching the most difficult defrosting position.

[0063] According to a preferred embodiment, the number of defrosting pipes 5 is multiple, and the multiple defrosting pipes 5 are arranged in parallel and cover the bottom of the evaporator 4. Preferably, the number of defrosting pipes 5 is comprehensively determined based on the bottom area of the evaporator 4 and the distance between adjacent two defrosting pipes 5. For example, the number of defrosting pipes 5 is 4 to 10. In the refrigeration unit of the preferred technical solution of this embodiment, the defrosting pipes 5 cover the bottom of the evaporator 4, which can defrost the bottom of the evaporator 4 evenly.

[0064] According to a preferred embodiment, the refrigeration unit further includes a suction filter 6 and a suction pipe 7. The suction filter 6 and the suction pipe 7 are located between the four-way reversing valve 2 and the defrosting pipe 5, and the cross-sectional area of the suction pipe 7 is the same as the sum of the cross-sectional areas of the multiple defrosting pipes 5, as Figure 1 shown. In the refrigeration unit of the preferred technical solution of this embodiment, the cross-sectional area of the suction pipe 7 is the same as the sum of the cross-sectional areas of the multiple defrosting pipes 5, which can ensure the uniformity of defrosting between the bottom of the evaporator 4 and the rest of the part.

[0065] According to a preferred embodiment, the refrigeration unit further includes a first temperature sensing bulb 8, which is located at the evaporator 4, and the first temperature sensing bulb 8 is used to detect the temperature on the surface of the evaporator 4, as Figure 1 shown. In the refrigeration unit of the preferred technical solution of this embodiment, the first temperature sensing bulb 8 is provided at the evaporator 4, and the temperature on the surface of the evaporator 4 is detected by the first temperature sensing bulb 8, so as to judge whether the evaporator 4 needs to be defrosted, so as to provide a basis for the refrigeration unit to start the defrosting mode.

[0066] According to a preferred embodiment, the refrigeration unit further includes a second temperature sensing bulb 9, which is located at the evaporator 4, and the second temperature sensing bulb 9 is used to detect the temperature inside the cold storage, as Figure 1 shown. The refrigeration unit of the preferred technical solution of this embodiment further includes a second temperature sensing bulb 9. By detecting the temperature inside the cold storage by the second temperature sensing bulb 9 and combining with the evaporation temperature of the refrigerant at the evaporator 4, it can be further judged whether the evaporator 4 needs to be defrosted, so as to provide a basis for the refrigeration unit to start the defrosting mode.

[0067] According to a preferred embodiment, the refrigeration unit further includes an electronic expansion valve 10, which is arranged between the condenser 3 and the evaporator 4, and the electronic expansion valve 10 is used to throttle the flowing refrigerant, as Figure 1 shown. Preferably, the refrigeration unit further includes a third temperature sensing bulb 11, a pressure sensor 12 and a fourth temperature sensing bulb 13. Among them, the third temperature sensing bulb 11 is located between the evaporator 4 and the defrosting pipe 5, and the third temperature sensing bulb 11 is used to detect the temperature at the outlet of the evaporator 4; the pressure sensor 12 and the fourth temperature sensing bulb 13 are located at the suction port of the compressor 1, and the pressure sensor 12 and the fourth temperature sensing bulb 13 are respectively used to detect the refrigerant pressure and temperature at the suction port of the compressor 1, as Figure 1 shown. In the refrigeration unit of the preferred technical solution of this embodiment, the temperature at the outlet of the evaporator 4, the refrigerant pressure and temperature at the suction port of the compressor 1 respectively detected by the third temperature sensing bulb 11, the pressure sensor 12 and the fourth temperature sensing bulb 13 can be used to adjust the superheat degree of the refrigeration unit to ensure the refrigeration effect of the evaporator 4.

[0068] As Figure 1 shown, the refrigeration unit further includes a gas-liquid separator 14 and a dryer filter 15.

[0069] When the refrigeration unit is in the refrigeration mode, the four-way reversing valve 2 is in the power-off state, the DC interfaces of the four-way reversing valve 2 are connected, and the ES interfaces are connected. The high-temperature and high-pressure gas discharged from the compressor 1 enters the condenser 3 through the C pipe of the four-way reversing valve 2 for condensation. The high-temperature and high-pressure liquid passes through the electronic expansion valve 10 for throttling into a low-temperature and low-pressure two-phase gas-liquid mixture, exchanges heat through the evaporator 4, becomes low-pressure superheated gas, and then further exchanges heat through the defrosting pipe 5 at the bottom of the evaporator 4. The gas enters the four-way reversing valve 2, enters the gas-liquid separator through the S pipe of the four-way reversing valve 2, and then enters the compressor 1 to complete the refrigeration cycle.

[0070] When the refrigeration unit is in the defrosting mode, the four-way reversing valve 2 is in the powered-on state, the DE interfaces of the four-way reversing valve 2 are connected, and the SC interfaces are connected. The high-temperature and high-pressure gas discharged from the compressor 1 enters the defrosting pipe 5 at the bottom of the evaporator 4 through the E pipe of the four-way reversing valve 2, and then enters the evaporator 4 for defrosting. The defrosted liquid passes through the electronic expansion valve for throttling, and the low-temperature and low-pressure two-phase refrigerant enters the condenser 3 for evaporation, and then enters the gas-liquid separator through the SC interface of the four-way reversing valve 2 and then enters the compressor 1 to complete the defrosting cycle.

[0071] Embodiment 2

[0072] This embodiment details the refrigeration equipment of the present invention.

[0073] The refrigeration equipment of this embodiment includes the refrigeration unit of any one of the technical solutions in Embodiment 1.

[0074] Since the refrigeration equipment of this embodiment includes the refrigeration unit of any one of the technical solutions in Embodiment 1, when the refrigeration equipment of this embodiment defrosts, it has the advantages of uniform defrosting of the evaporator, increased defrosting speed, and reduced energy consumption.

[0075] Embodiment 3

[0076] This embodiment details the defrosting control method of the refrigeration equipment of the present invention.

[0077] Figure 2 The flowchart showing the preferred implementation of the defrosting control method of the refrigeration equipment of this embodiment is as follows. Figure 2 As shown, the defrosting control method of the refrigeration equipment of any one of the technical solutions in Embodiment 2 includes the following steps:

[0078] Step 1: Obtain the temperature of the cold storage.

[0079] Step 2: Compare the obtained temperature of the cold storage with the preset value of the cold storage temperature.

[0080] Step 3: When the obtained temperature of the cold storage is less than the preset value of the cold storage temperature, the refrigeration equipment starts the defrosting mode.

[0081] Specifically, the preset value of the warehouse temperature is, for example, 0°C. When the obtained warehouse temperature of the cold storage is greater than the preset value of the warehouse temperature, there is no frosting problem with the evaporator 4, so there is no need to start the defrosting mode; when the obtained warehouse temperature of the cold storage is less than the preset value of the warehouse temperature, there may be a frosting problem with the evaporator 4. After the unit runs for a long time, the defrosting mode needs to be started.

[0082] The defrosting control method of the refrigeration equipment according to any one of the technical solutions in Embodiment 2 includes obtaining the warehouse temperature of the cold storage, comparing the obtained warehouse temperature of the cold storage with the preset value of the warehouse temperature, and when the obtained warehouse temperature of the cold storage is less than the preset value of the warehouse temperature, the step of starting the defrosting mode of the refrigeration equipment, which can realize the defrosting treatment of the evaporator 4; further, the defrosting control method of the refrigeration equipment according to any one of the technical solutions in this embodiment also has the advantages of uniform defrosting of the evaporator 4, increased defrosting speed, and reduced energy consumption.

[0083] According to a preferred embodiment, before the refrigeration equipment enters the defrosting mode, the following steps are further included:

[0084] Obtain the temperature on the surface of the evaporator 4;

[0085] Compare the obtained temperature on the surface of the evaporator 4 with the preset value of the temperature on the surface of the evaporator 4;

[0086] When the obtained temperature on the surface of the evaporator 4 is less than the preset value of the temperature on the surface of the evaporator 4 within the preset time range, the refrigeration equipment starts the defrosting mode. Preferably, the preset time is 10S. The preset value of the temperature on the surface of the evaporator 4 is the temperature at which the surface of the evaporator 4 just frosts as tested.

[0087] The defrosting control method of the refrigeration equipment in the preferred technical solution of this embodiment determines whether to start the defrosting mode based on the comparison result of the obtained temperature on the surface of the evaporator 4 and the preset value of the temperature on the surface of the evaporator 4, which can improve the accuracy of defrosting judgment and avoid entering the defrosting mode in a frost-free state with a high temperature on the surface of the evaporator 4.

[0088] According to a preferred embodiment, before the refrigeration equipment enters the defrosting mode, the following steps are further included:

[0089] Obtain the evaporation temperature of the refrigerant in the evaporator 4;

[0090] Compare the obtained evaporation temperature of the refrigerant in the evaporator 4 with the warehouse temperature of the cold storage;

[0091] When the difference between the obtained evaporation temperature of the refrigerant in the evaporator 4 and the warehouse temperature is within the preset range, the refrigeration equipment starts the defrosting mode.

[0092] Preferably, when T 库温 ≥T 第一预设库温 , and T 蒸发 ≤T 库温 -T化霜进入温差1 When the temperature is at a certain value, the refrigeration equipment starts the defrosting mode; when T 第二预设库温 ≤T 库温 <T 第一预设库温 , and T 蒸发 ≤T 库温 -T 化霜进入温差2 When the temperature is at a certain value, the refrigeration equipment starts the defrosting mode; when T 库温 <T 第二预设库温 , and T 蒸发 ≤T 库温 -T 化霜进入温差3 When the temperature is at a certain value, the refrigeration equipment starts the defrosting mode; where T 库温 is the temperature of the cold storage, T 第一预设库温 is the first preset temperature of the cold storage, T 第二预设库温 is the second preset temperature of the cold storage, T 蒸发 is the evaporation temperature of the refrigerant in the evaporator 4; T 化霜进入温差1 is the first defrosting entry temperature difference, T 化霜进入温差2 is the second defrosting entry temperature difference, T 化霜进入温差3 is the third defrosting entry temperature difference. More preferably, T 第一预设库温 is 15°C, T 第二预设库温 is -15°C, T 化霜进入温差1 is 22°C, T 化霜进入温差2 is 16°C, T 化霜进入温差2 is 12°C.

[0093] In the preferred technical solution of this embodiment, the defrosting control method of the refrigeration equipment determines whether to start the defrosting mode based on the comparison result of the evaporation temperature of the refrigerant in the evaporator 4 and the temperature of the cold storage, which can further improve the accuracy of defrosting judgment. Specifically, when the temperature of the cold storage is constant, the temperature difference between the evaporation temperature and the cold storage temperature is constant. When the evaporator 4 is frosted, the evaporation temperature corresponding to the evaporation pressure will decrease, the refrigeration capacity will decrease, and the temperature difference between the evaporation temperature and the cold storage temperature will increase. As the amount of frost increases, the temperature difference becomes larger. In view of this characteristic, for different cold storage temperatures, the temperature difference between the evaporation temperature and the cold storage temperature is preset. When the preset conditions are met, the unit enters defrosting, thereby improving the accuracy of defrosting judgment.

[0094] According to a preferred embodiment, the defrosting control method of the refrigeration equipment further includes the following steps:

[0095] Obtain the defrosting duration of the refrigeration equipment;

[0096] Compare the obtained defrosting duration of the refrigeration equipment with the preset value of the defrosting duration;

[0097] Based on the comparison result of the obtained defrosting duration of the refrigeration equipment and the preset value of the defrosting duration, determine the time for the refrigeration equipment to enter the defrosting mode next time.

[0098] Preferably, when t 化霜 ≤t预设 -t, the time for the refrigeration equipment to enter the defrost mode next time is extended by 10 min;

[0099] t 预设 -t < t 化霜 ≤ t 预设 , the time for the refrigeration equipment to enter the defrost mode next time is extended by 5 min;

[0100] t 预设 <t 化霜 ≤ t 预设 +2t, the time for the refrigeration equipment to enter the defrost mode next time remains unchanged;

[0101] t 预设 +2t < t 化霜 ≤ t 预设 +4t, the time for the refrigeration equipment to enter the defrost mode next time is shortened by 2 min;

[0102] t 预设 +4t < t 化霜 ≤ t 预设 +6t, the time for the refrigeration equipment to enter the defrost mode next time is shortened by 4 min;

[0103] t 预设 +6t < t 化霜 , the time for the refrigeration equipment to enter the defrost mode next time is shortened by 6 min;

[0104] Where, t 化霜 is the defrost duration of the refrigeration equipment, t 预设 is the preset value of the defrost duration, and t is the deviation value. More preferably, t is 10% of t 预设 .

[0105] The defrost control method of the refrigeration equipment in the preferred technical solution of this embodiment can optimize the time for the refrigeration equipment to enter the defrost mode next time based on the comparison result of the obtained defrost duration of the refrigeration equipment and the preset value of the defrost duration, and can avoid the problem of serious frosting on the evaporator 4. Specifically, when the current defrost time is short, it means that the frosting amount of the unit is small, and the time interval for the unit to enter the defrost next time can be extended; when the current defrost time is long, it means that the frosting amount of the unit is large, and the time interval for the unit to enter the defrost next time can be shortened.

[0106] According to a preferred embodiment, the defrost control method of the refrigeration equipment further includes the following steps: calculating the superheat of the evaporator 4 based on the difference between the temperature at the outlet of the evaporator 4 and the saturation temperature corresponding to the suction pressure at the suction port of the compressor 1; adjusting the superheat set value of the refrigeration equipment and making the refrigerant a saturated gas state at the outlet of the evaporator 4. In the preferred technical solution of this embodiment, the defrost control method of the refrigeration equipment adjusts the superheat set value of the refrigeration equipment and makes the refrigerant a saturated gas state at the outlet of the evaporator 4, which can ensure the refrigeration effect of the evaporator 4.

[0107] Due to the addition of the defrost pipe 5 at the bottom of the evaporator 4, when the refrigeration unit is in the refrigeration mode, the superheat section of the refrigerant during the evaporation process in the evaporator 4 is lengthened. During the refrigeration process, if the electronic expansion valve 10 is adjusted according to the original superheat control, it will cause a decrease in the latent heat exchange amount of the refrigerant inside the evaporator 4 and an increase in the sensible heat superheat section, resulting in a reduction in the refrigeration capacity of the evaporator 4. As Figure 1 shown, a third temperature sensing package 11 is added between the evaporator 4 and the defrost pipe 5. During the refrigeration process, the electronic expansion valve 10 calculates the superheat of the evaporator 4 based on the difference between the temperature at the outlet of the evaporator 4 and the saturation temperature corresponding to the suction pressure at the suction port of the compressor 1, and adjusts the superheat of the unit through PID, adjusts the superheat set value of the refrigeration equipment, and makes the refrigerant a saturated gas state at the outlet of the evaporator 4. The refrigerant passes through the evaporator 4 and the defrost pipe 5 and is further superheated and then returns to the compressor 1 to ensure the refrigeration effect of the evaporator. The specific control is as follows:

[0108] The suction superheat SH = the temperature at the outlet of the evaporator 4 - the saturation temperature corresponding to the suction pressure at the suction port of the compressor 1;

[0109] The superheat deviation ek = the measured value of the suction superheat - the superheat set value, where ek is the superheat deviation at the kth sampling period.

[0110] The electronic expansion valve 10 is adjusted once every superheat sampling period of T seconds. The controller detects the superheat of the system every 1 second, calculates the average value of the superheat of each system within the previous 5 seconds, and the measured values used for subsequent calculations are all average values. At the kth sampling period, the change amount of the opening of the electronic expansion valve is (unit: %):

[0111]

[0112] where, Kp is the proportionality coefficient, Ti is the integral time constant, Td is the differential time constant, and T is the sampling period.

[0113] In the description of the present invention, it should be noted that unless otherwise specified, the meaning of "plural" is two or more; the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0114] In the description of the present invention, it should also be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0115] The above is only the specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A refrigeration unit, characterized in that: The system comprises a compressor (1), a four-way reversing valve (2), a condenser (3), an evaporator (4) and a defrost pipe (5), wherein the defrost pipe (5) is located at the bottom of the evaporator (4), and both ends of the defrost pipe (5) are respectively connected to the four-way reversing valve (2) and the evaporator (4). When the refrigeration unit is in refrigeration mode, the exhaust port of the compressor (1), the four-way reversing valve (2), the condenser (3), the evaporator (4), the defrost pipe (5), the four-way reversing valve (2) and the return air port of the compressor (1) are connected in sequence to form a first refrigerant circuit; When the refrigeration unit is in defrost mode, the exhaust port of the compressor (1), the four-way reversing valve (2), the defrost pipe (5), the evaporator (4), the condenser (3), the four-way reversing valve (2) and the return air port of the compressor (1) are connected in sequence to form a second refrigerant circuit; There are multiple defrost tubes (5), and the multiple defrost tubes (5) are arranged in parallel, and the defrost tubes (5) cover the bottom of the evaporator (4); It also includes an air intake filter (6) and an air intake pipe (7), wherein the air intake filter (6) and the air intake pipe (7) are located between the four-way reversing valve (2) and the defrost pipe (5), and the cross-sectional area of the air intake pipe (7) is the same as the sum of the cross-sectional areas of the plurality of defrost pipes (5).

2. The refrigeration unit according to claim 1, characterized in that: It also includes a first temperature sensing package (8), which is located at the evaporator (4) and is used to detect the temperature of the surface of the evaporator (4).

3. The refrigeration unit according to claim 2, characterized in that: It also includes a second temperature sensing package (9), which is located at the evaporator (4) and is used to detect the temperature in the cold storage.

4. The refrigeration unit according to claim 1, characterized in that: It also includes an electronic expansion valve (10), which is arranged between the condenser (3) and the evaporator (4), and is used to throttle the refrigerant flowing through.

5. The refrigeration unit according to claim 4, characterized in that: It also includes a third temperature-sensing package (11), a pressure sensor (12) and a fourth temperature-sensing package (13), wherein: The third temperature sensing package (11) is located between the evaporator (4) and the defrost pipe (5), and the third temperature sensing package (11) is used to detect the temperature at the outlet of the evaporator (4); The pressure sensor (12) and the fourth temperature sensing package (13) are located at the air intake of the compressor (1), and the pressure sensor (12) and the fourth temperature sensing package (13) are used to detect the refrigerant pressure and temperature at the air intake of the compressor (1), respectively.

6. A refrigeration device, characterized in that: A refrigeration unit comprising the refrigeration unit according to any one of claims 1 to 5.

7. A defrost control method for refrigeration equipment according to claim 6, characterized in that: The steps include: Get the cold storage temperature; Compare the obtained cold storage temperature with the preset temperature value; When the obtained cold storage temperature is lower than the preset storage temperature value, the refrigeration equipment starts the defrost mode.

8. The defrost control method for refrigeration equipment according to claim 7, characterized in that: Before the refrigeration equipment enters the defrost mode, the following steps are also included: Obtaining the temperature of the surface of the evaporator (4); Comparing the acquired surface temperature of the evaporator (4) with a preset surface temperature value of the evaporator (4); When the temperature of the surface of the evaporator (4) obtained is less than the preset value of the surface temperature of the evaporator (4) within the preset time range, the refrigeration device starts the defrost mode.

9. The defrost control method for refrigeration equipment according to claim 8, characterized in that: Before the refrigeration equipment enters the defrost mode, the following steps are also included: Obtaining the evaporation temperature of the refrigerant in the evaporator (4); Comparing the obtained evaporation temperature of the refrigerant in the evaporator (4) with the storage temperature of the cold storage; When the difference between the evaporation temperature of the refrigerant in the evaporator (4) and the storage temperature is within a preset range, the refrigeration equipment starts the defrost mode.

10. The defrost control method for refrigeration equipment according to claim 9, characterized in that: When T 库温 ≥T 第一预设库温 , and T 蒸发 ≤(T 库温 -T 化霜进入温差1 ) when the refrigeration equipment starts the defrost mode; When T 第二预设库温 ≤T 库温 <T 第一预设库温 , and T 蒸发 ≤(T 库温 -T 化霜进入温差2 ) when the refrigeration equipment starts the defrost mode; When T 库温 <T 第二预设库温 , and T 蒸发 ≤(T 库温 -T 化霜进入温差3 ) when the refrigeration equipment starts the defrost mode; Among them, T 库温 is the temperature of the cold storage, T 第一预设库温 is the first preset temperature of the cold storage, T 第二预设库温 The second preset temperature of the cold storage, T 蒸发 is the evaporation temperature of the refrigerant in the evaporator (4); T 化霜进入温差1 The first defrost temperature difference, T 化霜进入温差2 The temperature difference when entering the second defrost, T 化霜进入温差3 Enter the temperature difference for the third defrost.

11. The defrost control method for refrigeration equipment according to any one of claims 7 to 10, characterized in that: The following steps are also included: Get the defrost time of the refrigeration equipment; Compare the obtained defrost time of the refrigeration equipment with the preset defrost time; Based on a comparison result of the acquired defrost time of the refrigeration device and a preset defrost time, a time when the refrigeration device enters the defrost mode next time is determined.

12. The defrost control method for refrigeration equipment according to claim 11, characterized in that: When t 化霜 ≤t 预设 -t, the time for the refrigeration equipment to enter the defrost mode next time is extended by 10 minutes; t 预设 -t<t 化霜 ≤t 预设 , the time for the refrigeration equipment to enter the defrost mode next time is extended by 5 minutes; t 预设 <t 化霜 ≤t 预设 +2t, the time for the refrigeration equipment to enter the defrost mode next time remains unchanged; t 预设 +2t<t 化霜 ≤t 预设 +4t, the time for the refrigeration equipment to enter the defrost mode next time is shortened by 2 minutes; t 预设 +4t<t 化霜 ≤t 预设 +6t, the time for the refrigeration equipment to enter the defrost mode next time is shortened by 4 minutes; t 预设 +6t<t 化霜 , the time for the refrigeration equipment to enter the defrost mode next time is shortened by 6 minutes; Among them, t 化霜 is the defrost time of the refrigeration equipment, t 预设 is the preset value of defrost time, and t is the deviation value.

13. The defrost control method for refrigeration equipment according to any one of claims 7 to 10, characterized in that: The following steps are also included: Calculating the superheat of the evaporator (4) based on the difference between the temperature at the outlet of the evaporator (4) and the saturation temperature corresponding to the suction pressure of the suction port of the compressor (1); The superheat setting value of the refrigeration equipment is adjusted so that the refrigerant is in a saturated gas state at the outlet of the evaporator (4).

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