Refrigeration defrosting unit and control method thereof

Abstract

The application provides a refrigeration and defrosting unit and a control method thereof. The refrigeration and defrosting unit comprises a refrigeration unit, a defrosting unit, a first compressor, a condenser and an evaporator. The defrosting unit comprises a second compressor. The defrosting unit has a refrigeration state and a refrigeration and defrosting state. The second compressor has a first air inlet end and a first air outlet end arranged oppositely. The first air inlet end is communicated with an outlet of the evaporator. The defrosting unit further has a refrigeration pipeline and a defrosting pipeline. The refrigeration pipeline and the defrosting pipeline are communicated with the first air outlet end. The refrigeration pipeline is communicated with an inlet of the condenser. The defrosting pipeline is communicated with an inlet of the evaporator. The defrosting pipeline is used for heating and defrosting the evaporator. When the defrosting unit is in the refrigeration state, the refrigeration pipeline is communicated with the condenser, and the defrosting pipeline is disconnected with the evaporator. When the defrosting unit is in the refrigeration and defrosting state, the refrigeration pipeline is disconnected with the condenser, and the defrosting pipeline is communicated with the evaporator.

Description

TECHNICAL FIELD

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

[0002] Large cold storage refrigeration systems usually include freon systems and carbon dioxide cascade systems. For the freon system, the exhaust of the compressor can be directly used for hot gas defrosting. However, for the carbon dioxide cascade system, in order to make the overall energy efficiency of the cascade system optimal, there is an optimal carbon dioxide condensing temperature, which is usually lower than 0℃. Therefore, for the carbon dioxide cascade system that needs to use hot gas defrosting, the condensing pressure and condensing temperature required for refrigeration and defrosting are different, and a separate defrosting unit is usually configured for hot gas defrosting. In general, the separately configured defrosting unit is only used during defrosting. With such an arrangement, there are problems such as high equipment investment cost, low utilization rate, and increased machine room floor area, which increase the cost of the refrigeration system. SUMMARY

[0003] The present application provides a refrigeration defrosting unit and a control method thereof to solve the problem of high cost of the refrigeration system in the prior art.

[0004] According to one aspect of the present application, a refrigeration defrosting unit is provided, which comprises a refrigeration unit and a defrosting unit. The refrigeration unit comprises a first compressor, a condenser and an evaporator connected in sequence. The defrosting unit comprises a second compressor. The defrosting unit has a refrigeration state and a refrigeration defrosting state. The second compressor has a first inlet and a first outlet arranged oppositely. The first inlet is connected to the outlet of the evaporator. The defrosting unit further has a refrigeration pipeline and a defrosting pipeline. Both the refrigeration pipeline and the defrosting pipeline are connected to the first outlet. The refrigeration pipeline is connected to the inlet of the condenser, and the defrosting pipeline is connected to the inlet of the evaporator. The defrosting pipeline is used to input high-temperature refrigerant to the evaporator to heat and defrost the evaporator. When the defrosting unit is in the refrigeration state, the refrigeration pipeline is connected to the condenser, and the defrosting pipeline is disconnected from the evaporator. When the defrosting unit is in the refrigeration defrosting state, the refrigeration pipeline is disconnected from the condenser, and the defrosting pipeline is connected to the evaporator.

[0005] The technical scheme of the present application can determine whether defrosting of the evaporator is needed during refrigeration of the refrigeration unit, and switch the defrosting unit between the refrigeration state and the refrigeration-defrosting state according to the specific condition. Specifically, when defrosting of the evaporator is needed, the defrosting pipeline is connected to the inlet of the evaporator, and the evaporator is defrosted by high-temperature refrigerant in the defrosting pipeline, while the refrigeration pipeline is disconnected from the condenser. When defrosting of the evaporator is not needed, the connection between the defrosting pipeline and the evaporator is disconnected, and the refrigeration pipeline is connected to the condenser. In the conventional technical scheme, a separate defrosting unit is needed to defrost the evaporator, and when defrosting of the evaporator is not needed, the compressor of the defrosting unit is idle, which increases the cost of the refrigeration system. The present application can make the defrosting unit select the working state according to the need during operation of the refrigeration unit, improve the utilization rate of the second compressor, reduce the cost of the refrigeration system, and reduce the floor area occupied by the equipment.

[0006] Further, the refrigeration unit further comprises a first oil separator, and the defrosting unit further comprises a second oil separator. The first oil separator has a first mixed inlet, a first gas outlet and a first oil return port. The first oil separator is located between the first compressor and the condenser. The gas outlet of the first compressor is connected to the first mixed inlet. The first gas outlet is connected to the inlet of the condenser. The first oil return port is connected to the oil inlet of the first compressor. The second oil separator has a second mixed inlet, a second gas outlet and a second oil return port. The gas outlet of the second compressor is connected to the second mixed inlet of the second oil separator. The refrigeration pipeline and the defrosting pipeline are both connected to the second gas outlet of the second oil separator. The second oil return port is connected to the oil inlet of the second compressor. The first oil return port is connected to the second oil return port. The above arrangement can ensure that the defrosting unit can be switched between the refrigeration state and the refrigeration-defrosting state during operation of the refrigeration unit, and can improve the utilization rate of oil.

[0007] Further, the refrigeration-defrosting unit further comprises an oil return main pipe, a first branch pipe, a second branch pipe and a first electromagnetic valve. The two ends of the oil return main pipe are connected to the first oil return port and the second oil return port respectively. One end of the first branch pipe is connected to the oil return main pipe. The other end of the first branch pipe is connected to the oil inlet of the first compressor. One end of the second branch pipe is connected to the oil return main pipe. The other end of the second branch pipe is connected to the oil inlet of the second compressor. The first electromagnetic valve is arranged on the oil return main pipe and located between the first branch pipe and the second branch pipe. Such arrangement has simple structure and can ensure compactness of the entire refrigeration-defrosting unit.

[0008] Further, the refrigeration and defrosting unit further comprises a second electromagnetic valve and a third electromagnetic valve, the second electromagnetic valve is arranged on the first branch pipe, and the third electromagnetic valve is arranged on the second branch pipe. The arrangement of the second electromagnetic valve and the third electromagnetic valve can timely adjust the amount of oil flowing into the first compressor and the second compressor, and ensure the smoothness of the operation of the refrigeration and defrosting unit.

[0009] Further, the refrigeration and defrosting unit further comprises a first oil level observation part and a second oil level observation part, the first oil level observation part and the second oil level observation part are arranged on the oil return main pipe, the first oil level observation part is located between the connection between the first branch pipe and the oil return main pipe and the first oil return port, and the second oil level observation part is located between the connection between the second branch pipe and the oil return main pipe and the second oil return port. The arrangement of the first oil level observation part and the second oil level observation part can observe the oil level of the first oil separator and the second oil separator in real time, so that the staff can timely adjust the oil level of the first oil separator and the oil level of the second oil separator, and ensure the smoothness of the operation of the refrigeration and defrosting unit.

[0010] Further, the refrigeration and defrosting unit further comprises a first oil level observation part and a second oil level observation part, the first oil level observation part and the second oil level observation part are arranged on the oil return main pipe, the first oil level observation part is located between the connection between the first branch pipe and the oil return main pipe and the first oil return port, and the second oil level observation part is located between the connection between the second branch pipe and the oil return main pipe and the second oil return port. The arrangement of the first oil level observation part and the second oil level observation part can observe the oil level of the first oil separator and the second oil separator in real time, so that the staff can timely adjust the oil level of the first oil separator and the oil level of the second oil separator, and ensure the smoothness of the operation of the refrigeration and defrosting unit.

[0011] Further, the refrigeration unit comprises a plurality of first compressors arranged in parallel with each other; and / or the defrosting unit comprises a plurality of second compressors arranged in parallel with each other. In this way, the adaptability of the refrigeration and defrosting unit can be improved.

[0012] Further, the refrigeration and defrosting unit further comprises a fourth electromagnetic valve and a fifth electromagnetic valve, the fourth electromagnetic valve is arranged on the refrigeration pipeline, and the fifth electromagnetic valve is arranged on the defrosting pipeline. The arrangement of the fourth electromagnetic valve and the fifth electromagnetic valve can enable the defrosting unit to automatically switch between the refrigeration state and the refrigeration and defrosting state, and improve the smoothness of the operation of the refrigeration and defrosting unit.

[0013] Further, the defrosting unit further comprises a first filter part, the first filter part is arranged between the evaporator and the first compressor, and the first filter part is used for filtering the vapor entering the first compressor; and / or the refrigeration unit further comprises a second filter part, the second filter part is arranged between the evaporator and the second compressor, and the second filter part is used for filtering the vapor entering the second compressor. In this way, the cleanliness of the vapor flowing into the first compressor and the second compressor can be ensured, and the smoothness of the operation of the first compressor and the second compressor can be ensured.

[0014] According to another aspect of the present application, there is provided a control method of a refrigeration defrosting unit, the refrigeration defrosting unit being the refrigeration defrosting unit in the above description, when the refrigeration defrosting unit is in a refrigeration defrosting state, the control method comprising the following steps:

[0015] Step 1: starting and obtaining the operating parameter of the second compressor of the refrigeration defrosting unit, when the operating parameter of the second compressor meets a first preset condition, loading the second compressor of the refrigeration defrosting unit, obtaining the operating parameter of the evaporator of the refrigeration defrosting unit, when the operating parameter of the second compressor meets a second preset condition, stopping loading the second compressor;

[0016] Step 2: starting and obtaining the operating parameter of the first compressor of the refrigeration defrosting unit, when the operating parameter of the first compressor meets a third preset condition, loading the first compressor, until the operating parameter of the first compressor meets a fourth preset condition, stopping loading the first compressor. Through the above two steps, the smoothness of the operation of the refrigeration defrosting unit can be ensured.

[0017] Further, the operating parameter of the second compressor includes the actual discharge pressure PT1 of the second compressor, the first preset condition includes the target defrosting pressure P1 and the first time T1 of the second compressor, and the second compressor meeting the first preset condition specifically includes: PT1≤P1, and lasting for T1 time; the second preset condition includes: PT1=P1. In this way, the situation of too long defrosting time or unable to defrost can be avoided or reduced.

[0018] Further, the operating parameter of the first compressor includes the actual suction pressure PT2 of the first compressor, the third preset condition includes the target suction pressure P2, the loading pressure difference ΔP1 and the second time T2 of the first compressor, when the first compressor meets the third preset condition specifically includes: PT2≥P2+ΔP1, and lasting for T2 time; the operating parameter of the first compressor meeting the fourth preset condition specifically includes: P2≤PT2≤P2+ΔP1.

[0019] Further, the control method of the refrigeration defrosting unit further comprises: when PT1﹥P1, and lasting for T3 time, unloading the second compressor. In this way, the stability of the unloading of the second compressor can be ensured. When PT2﹤P2, and lasting for T4 time, unloading the first compressor. In this way, the stability of the unloading of the first compressor can be ensured.

[0020] Further, the control method of the refrigeration defrosting unit further comprises: when the operation of the first compressor and the second compressor is stopped, first unloading the first compressor, and then unloading the second compressor. In this way, the service life of the first compressor and the second compressor can be ensured.

[0021] Further, when the number of the second compressors is multiple, the second compressors are unloaded according to the starting sequence of the multiple second compressors; when the number of the first compressors is multiple, the first compressors are unloaded according to the starting sequence of the multiple first compressors. In this way, the wear of the multiple first compressors and the multiple second compressors can be kept as consistent as possible, and the service life of the multiple first compressors and the multiple second compressors can be guaranteed. BRIEF DESCRIPTION OF DRAWINGS

[0022] The accompanying drawings, which form a part of the specification, are included to provide a further understanding of the application and are incorporated herein in conjunction with the description of the application. The drawings are as follows:

[0023] Figure 1 A structure schematic diagram of the refrigeration defrosting unit provided by the application is shown.

[0024] In the above drawings, the following reference signs are used:

[0025] 10, first compressor;

[0026] 20, second compressor;

[0027] 31, refrigeration pipeline; 311, fourth electromagnetic valve; 32, defrosting pipeline; 321, fifth electromagnetic valve;

[0028] 41, first oil separator; 411, first mixed inlet; 412, first gas outlet; 413, first oil return port;

[0029] 42, second oil separator; 421, second mixed inlet; 422, second gas outlet; 423, second oil return port;

[0030] 50, oil return main pipe; 501, first electromagnetic valve;

[0031] 51, first branch pipe; 511, second electromagnetic valve;

[0032] 52, second branch pipe; 521, third electromagnetic valve;

[0033] 61, first oil level observation part; 62, second oil level observation part;

[0034] 71, first dry filter part; 72, second dry filter part;

[0035] 81, first filter part; 82, second filter part. DETAILED DESCRIPTION

[0036] Clearly, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The description of the at least one example embodiment is actually only illustrative, and is by no means intended to limit the present application and its application or use in any way. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of the present application.

[0037] As shown in Figure 1 The present application provides a refrigeration defrosting unit, which comprises a refrigeration unit and a defrosting unit. The refrigeration unit comprises a first compressor 10, a condenser and an evaporator connected in sequence. The defrosting unit comprises a second compressor 20. The defrosting unit has a refrigeration state and a refrigeration defrosting state. The second compressor 20 has a first air inlet end and a first air outlet end arranged oppositely. The first air inlet end is communicated with the outlet of the evaporator. The defrosting unit further has a refrigeration pipeline 31 and a defrosting pipeline 32. Both the refrigeration pipeline 31 and the defrosting pipeline 32 are communicated with the first air outlet end. The refrigeration pipeline 31 is communicated with the inlet of the condenser. The defrosting pipeline 32 is communicated with the inlet of the evaporator. The defrosting pipeline 32 is used for inputting high-temperature refrigerant to the evaporator to heat and defrost the evaporator. When the defrosting unit is in the refrigeration state, the refrigeration pipeline 31 is communicated with the condenser, and the defrosting pipeline 32 is disconnected with the evaporator. When the defrosting unit is in the refrigeration defrosting state, the refrigeration pipeline 31 is disconnected with the condenser, and the defrosting pipeline 32 is communicated with the evaporator. The arrow direction in the figure is the direction of fluid flow.

[0038] In the process of refrigeration of the refrigeration unit, whether the evaporator needs to be defrosted is determined, and the defrosting unit is switched between the refrigeration state and the refrigeration defrosting state according to the specific condition. Specifically, when the evaporator needs to be defrosted, the defrosting pipeline 32 is communicated with the inlet of the evaporator, and the evaporator is heated and defrosted by the high-temperature refrigerant in the defrosting pipeline 32, while ensuring that the refrigeration pipeline 31 is disconnected with the condenser. When the evaporator does not need to be defrosted, the connection between the defrosting pipeline 32 and the evaporator is disconnected, and the refrigeration pipeline 31 is communicated with the condenser. In the conventional technical solution, a separate defrosting unit needs to be configured to defrost the evaporator, and when the evaporator does not need to be defrosted, the compressor of the defrosting unit is idle, which increases the cost of the refrigeration system. The present application can select the working state of the defrosting unit according to the need during the operation of the refrigeration unit, improve the utilization rate of the second compressor 20, reduce the cost of the refrigeration system, and reduce the floor area of the equipment. In addition, in the conventional technology, the freezer is prone to frosting, and needs to be defrosted constantly, and then needs to be turned on or off constantly, which reduces the service life of the compressor. In the present application, the second compressor 20 can always be in working state, and does not need to be turned on or off repeatedly, which ensures the service life of the second compressor 20.

[0039] As shown in Figure 1 The refrigeration unit further comprises a first oil separator 41, and the defrosting unit further comprises a second oil separator 42. The first oil separator 41 has a first mixed inlet 411, a first gas outlet 412 and a first oil return port 413. The first oil separator 41 is located between the first compressor 10 and the condenser. The gas outlet of the first compressor 10 is communicated with the first mixed inlet 411. The first gas outlet 412 is communicated with the inlet of the condenser. The first oil return port 413 is communicated with the oil inlet of the first compressor 10. The second oil separator 42 has a second mixed inlet 421, a second gas outlet 422 and a second oil return port 423. The gas outlet of the second compressor 20 is communicated with the second mixed inlet 421 of the second oil separator 42. The refrigeration pipeline 31 and the defrosting pipeline 32 are both communicated with the second gas outlet 422 of the second oil separator 42. The second oil return port 423 is communicated with the oil inlet of the second compressor 20. The first oil return port 413 is communicated with the second oil return port 423.

[0040] By adopting the above technical scheme, when the refrigerating unit is refrigerating, low-temperature and low-pressure steam evaporated through the evaporator enters the first compressor 10, and the low-temperature and low-pressure steam is compressed by the first compressor 10 into high-temperature and high-pressure superheated steam. The superheated steam enters the first oil separator 41 through the first mixing inlet 411 to separate oil and gas, and the high-temperature and high-pressure refrigerant gas after separation enters the condenser through the first gas outlet 412 to condense. The oil liquid entering the first oil separator 41 with the superheated steam flows into the first compressor 10 through the first oil return port 413. When the defrosting unit is in a refrigeration state, low-temperature and low-pressure steam evaporated through the evaporator enters the second compressor 20, and the low-temperature and low-pressure steam is compressed by the second compressor 20 into high-temperature and high-pressure superheated steam. The superheated steam enters the second oil separator 42 through the second mixing inlet 421 to separate oil and gas, and the high-temperature and high-pressure refrigerant gas after separation enters the condenser through the second gas outlet 422 to condense. The oil liquid entering the second oil separator 42 with the superheated steam flows into the second compressor 20 through the second oil return port 423. When the defrosting unit is in a refrigeration and defrosting state, low-temperature and low-pressure steam evaporated through the evaporator enters the second compressor 20, and the low-temperature and low-pressure steam is compressed by the second compressor 20 into high-temperature and high-pressure superheated steam. The superheated steam enters the second oil separator 42 through the second mixing inlet 421 to separate oil and gas, and the high-temperature and high-pressure refrigerant gas after separation enters the evaporator through the second gas outlet 422 to heat and defrost the evaporator. The oil liquid entering the second oil separator 42 with the superheated steam flows into the second compressor 20 through the second oil return port 423. The first oil separator 41 is communicated with the first compressor 10, and the second oil separator 42 is communicated with the second compressor 20, which can ensure that the defrosting unit switches between the refrigeration state and the refrigeration and defrosting state during the working process of the refrigerating unit, thereby ensuring the smoothness of the refrigeration and defrosting unit. Moreover, the oil liquid separated by the first oil separator 41 can flow back into the first compressor 10, and the oil liquid separated by the second oil separator 42 can flow back into the second compressor 20, so that the utilization rate of the oil liquid can be improved.

[0041] Further, the first oil return port 413 and the second oil return port 423 have a communication state and a blocking state. When the defrosting unit is in a refrigeration defrosting state, the first oil return port 413 and the second oil return port 423 are in the blocking state. Specifically, during normal refrigeration, the CO2 condensing temperature is usually between -5°C and -7°C, and the condensing pressure is between 29.45 Bar and 27.81 Bar. During defrosting, the CO2 condensing temperature is usually 7°C, and the corresponding condensing pressure is 40.75 Bar. Therefore, during the refrigeration defrosting state, the exhaust pressure of the first oil separator 41 and the exhaust pressure of the second oil separator 42 are different. If the first oil return port 413 and the second oil return port 423 are in the communication state during the refrigeration defrosting state, the cold oil in the second oil separator 42 will enter the first oil separator 41, and the refrigeration defrosting unit will run in this mode for a long time. The second oil separator 42 will have an oil level protection phenomenon, which will affect the service life of the first oil separator 41 and the second oil separator 42. In addition, there may be a problem of discharge pressure and pressure, which will cause the discharge pressure of the refrigeration unit to rise and the discharge pressure of the defrosting unit to decrease, affecting the service life of the refrigeration defrosting unit. Therefore, the design of the present scheme can ensure the service life of the refrigeration defrosting unit and improve the smoothness of the defrosting unit.

[0042] When the defrosting unit is in a refrigeration state, the first oil return port 413 and the second oil return port 423 are in a communication state. During refrigeration, the running time of the first compressor 10 and the second compressor 20 may be different. If the first oil return port 413 and the second oil return port 423 are in the blocking state during refrigeration, the oil level of the first oil separator 41 and the second oil separator 42 may be unbalanced, and the refrigeration defrosting unit may run in this mode for a long time. Therefore, the design of the present scheme can ensure the service life of the defrosting unit and ensure the smoothness of the refrigeration defrosting unit.

[0043] Specifically, the refrigeration and defrosting unit further comprises an oil return main pipe 50, a first branch pipe 51, a second branch pipe 52 and a first electromagnetic valve 501, two ends of the oil return main pipe 50 are communicated with the first oil return port 413 and the second oil return port 423 respectively, one end of the first branch pipe 51 is communicated with the oil return main pipe 50, the other end of the first branch pipe 51 is communicated with the oil inlet of the first compressor 10, one end of the second branch pipe 52 is communicated with the oil return main pipe 50, the other end of the second branch pipe 52 is communicated with the oil inlet of the second compressor 20, the first electromagnetic valve 501 is arranged on the oil return main pipe 50 and located between the first branch pipe 51 and the second branch pipe 52. Specifically, the position where the first branch pipe 51 is communicated with the oil return main pipe 50 is a first position, the position where the second branch pipe 52 is communicated with the oil return main pipe is a second position, and the first electromagnetic valve 501 is located between the first position and the second position. When the refrigeration and defrosting unit is in a refrigeration and defrosting state, the oil in the first oil separator 41 enters the first compressor 10 through the first branch pipe 51, and the oil in the second oil separator 42 enters the second compressor 20 through the second branch pipe 52. The above-mentioned structure is simple and can ensure the compactness of the refrigeration and defrosting unit.

[0044] Further, the refrigeration and defrosting unit further comprises a second electromagnetic valve 511 and a third electromagnetic valve 521, the second electromagnetic valve 511 is arranged on the first branch pipe 51, and the third electromagnetic valve 521 is arranged on the second branch pipe 52. By arranging the second electromagnetic valve 511, the amount of oil flowing into the first compressor 10 can be adjusted in time, and by arranging the third electromagnetic valve 521, the amount of oil flowing into the second compressor 20 can be adjusted in time, thereby ensuring the smoothness of the operation of the entire refrigeration and defrosting unit.

[0045] Further, the refrigeration and defrosting unit further comprises a first oil level observation part 61 and a second oil level observation part 62, the first oil level observation part 61 and the second oil level observation part 62 are both arranged on the oil return main pipe 50, and the first oil level observation part 61 is located between the connection between the first branch pipe 51 and the oil return main pipe 50 and the first oil return port 413, and the second oil level observation part 62 is located between the connection between the second branch pipe 52 and the oil return main pipe 50 and the second oil return port 423. The oil level of the first oil separator 41 is observed through the first oil level observation part 61, and the oil level of the second oil separator 42 is observed through the second oil level observation part 62, so as to facilitate the staff to adjust the oil pressure of the first oil separator 41 and the second oil separator 42 in time, thereby ensuring the smoothness of the operation of the first oil separator 41 and the second oil separator 42. In the embodiment, the first oil level observation part 61 is a first liquid observation mirror, and the second oil level observation part 62 is a second liquid observation mirror.

[0046] Further, the refrigeration and defrosting unit further comprises a first dry filter part 71 and a second dry filter part 72, both of which are arranged on the oil return main pipe 50, the first dry filter part 71 is located between the connection of the first branch pipe 51 and the oil return main pipe 50 and the first oil return port 413, and the second dry filter part 72 is located between the connection of the second branch pipe 52 and the oil return main pipe 50 and the second oil return port 423. The first dry filter part 71 can dry and filter the oil flowing in the oil return main pipe 50, ensure the purity of the oil flowing into the first compressor 10, and further ensure the smooth operation of the first compressor 10. The second dry filter part 72 can dry and filter the oil flowing in the oil return main pipe 50, ensure the purity of the oil flowing into the second compressor 20, and further ensure the smooth operation of the second compressor 20.

[0047] Further, in the embodiment, the first dry filter part 71 and the first liquid mirror are distributed along the flow direction of the oil. In this way, the adhesion of contaminants on the first liquid mirror can be reduced, and the convenience of observing the first liquid mirror can be improved. The second dry filter part 72 and the second liquid mirror are distributed along the flow direction of the oil, and in this way, the adhesion of contaminants on the second liquid mirror can be reduced, and the convenience of observing the second liquid mirror can be ensured.

[0048] Further, the refrigeration unit comprises a plurality of first compressors 10 arranged in parallel with each other. The specific number of first compressors 10 is not limited by the present scheme, which can be one or multiple. In the embodiment, two first compressors 10 are arranged in parallel. In this way, the convenience of assembling the refrigeration and defrosting unit can be ensured, and the adaptability of the refrigeration and defrosting unit can be improved.

[0049] Alternatively, the defrosting unit can comprise a plurality of second compressors 20 arranged in parallel with each other. The number of second compressors 20 is not limited by the present scheme, which can be one or multiple. In the embodiment, one second compressor 20 is arranged.

[0050] Further, the refrigeration and defrosting unit further comprises a fourth electromagnetic valve 311 and a fifth electromagnetic valve 321, the fourth electromagnetic valve 311 is arranged on the refrigeration pipeline 31, and the fifth electromagnetic valve 321 is arranged on the defrosting pipeline 32. The arrangement of the fourth electromagnetic valve 311 and the fifth electromagnetic valve 321 can improve the convenience of switching the defrosting unit between the refrigeration state and the refrigeration and defrosting state.

[0051] Further, the defrosting unit further comprises a first filter part 81, which is arranged between the evaporator and the first compressor 10, and is used for filtering the vapor entering the first compressor 10.

[0052] The refrigeration unit further comprises a second filter part 82, which is arranged between the evaporator and the second compressor 20, and is used for filtering the vapor entering the second compressor 20. The arrangement of the first filter part 81 and the second filter part 82 can ensure the cleanliness of the vapor flowing into the first compressor 10 and the second compressor 20, and ensure the smooth operation of the first compressor 10 and the second compressor 20.

[0053] Embodiment two of the present application provides a control method of a refrigeration defrosting unit, the refrigeration defrosting unit being the refrigeration defrosting unit in the above description. When the refrigeration defrosting unit is in a refrigeration defrosting state, the control method comprises the following steps:

[0054] Step 1: start and acquire the operation parameter of the second compressor 20 of the refrigeration defrosting unit. When the operation parameter of the second compressor 20 meets the first preset condition, load the second compressor 20 of the refrigeration defrosting unit. When the operation parameter of the second compressor 20 meets the second preset condition, stop loading the second compressor 20.

[0055] Step 2: start and acquire the operation parameter of the first compressor 10 of the refrigeration defrosting unit. When the operation parameter of the first compressor 10 meets the third preset condition, load the first compressor 10. When the operation parameter of the first compressor 10 meets the fourth preset condition, stop loading the first compressor 10.

[0056] The present scheme first loads the second compressor 20, and then loads the first compressor 10. When the first compressor 10 is first loaded, the second compressor 20 may not be able to be loaded when the load is small, thereby causing the refrigeration defrosting unit to be unable to defrost. Therefore, the above arrangement can ensure the smoothness of defrosting of the refrigeration defrosting unit.

[0057] Specifically, the present scheme does not limit the number of the first compressor 10 and the second compressor 20. When the second compressor 20 is multiple, the multiple second compressors 20 are started in turn according to the total working time of the second compressors 20, and the second compressor 20 with the shortest total working time is started first. When the first compressor 10 is multiple, the multiple first compressors 10 are started in turn according to the total working time of the first compressors 10, and the first compressor 10 with the shortest total working time is started first. In this way, the wear of the first compressor 10 and the second compressor 20 can be balanced, thereby ensuring the service life of the first compressor 10 and the second compressor 20. Moreover, the first compressor 10 and the second compressor 20 are loaded in a one-by-one loading manner, which can avoid or reduce the problems of overloading and excessive energy consumption.

[0058] Specifically, the operation parameter of the second compressor 20 includes an actual discharge pressure PT1 of the second compressor 20, the first preset condition includes a target defrosting pressure P1 and a first time T1 of the second compressor 20, and the second compressor 20 satisfying the first preset condition specifically includes PT1≤P1 and lasting T1. In this way, the second compressor 20 can be started in a delayed manner, and when the above condition is met, it can be ensured that the collected operation parameter of the second compressor 20 is stable enough, thereby ensuring the smoothness of the start of the second compressor 20. In the present scheme, T1 can be set to 5s, 10s or 20s, and in the present embodiment, T1 is 10s.

[0059] Specifically, the second preset condition is PT1=P1. In this way, the problem of increased refrigeration energy consumption due to too long defrosting time can be avoided.

[0060] Further, the operation parameter of the first compressor 10 includes an actual suction pressure PT2 of the first compressor 10, the third preset condition includes a target suction pressure P2, a load pressure difference ΔP1 and a second time T2 of the first compressor 10, and the first compressor 10 satisfying the third preset condition specifically includes PT2≥P2+ΔP1 and lasting T2. In this way, the smoothness of the start of the first compressor 10 can be ensured. In the present scheme, T2 can be set to 5s, 10s or 20s, and in the present embodiment, T2 is 10s.

[0061] Specifically, the operation parameter of the first compressor 10 satisfying the fourth preset condition specifically includes P2≤PT2≤P2+ΔP1. In this way, the smoothness of the operation of the refrigeration defrosting unit can be ensured.

[0062] Further, when the operation of the first compressor 10 and the second compressor 20 is stopped, the first compressor 10 is first unloaded, and then the second compressor 20 is unloaded. In this way, the smoothness of the unloading process can be ensured.

[0063] Further, the control method of the refrigeration defrosting unit further includes: when PT1>P1 and lasting T3, the second compressor 20 is unloaded. When the number of the second compressors 20 is multiple, the second compressors 20 are unloaded according to the start order of the multiple second compressors 20, that is, the second compressor 20 with a longer running time is preferentially unloaded. In this way, the service life of the multiple second compressors 20 can be ensured. In the present scheme, T3 can be set to 5s, 10s or 20s, and in the present embodiment, T3 is 10s.

[0064] Further, the control method of the refrigeration defrosting unit further comprises: when PT2

[0065] A control method of a refrigeration defrosting unit, the refrigeration defrosting unit being the refrigeration defrosting unit in the above description, when the refrigeration defrosting unit is in a refrigeration state, the control method comprises:

[0066] Step 1: obtaining the suction pressure value PT3 of the compressor, the suction pressure value PT3 of the compressor satisfies: PT3≥P3+ΔP2, and lasts for T2 time, starting to load the compressor;

[0067] Step 2: when the suction pressure value PT3 of the compressor satisfies: P3≤PT3≤P3+ΔP2, stop loading the compressor;

[0068] Step 3: when the suction pressure value PT3 of the compressor satisfies: when PT3≤P3, and lasts for T5 time, start to unload the compressor. In the present scheme, T5 can be set to 5s, 10s or 20s, and in the present embodiment, T5 is 10s.

[0069] Wherein, the compressor comprises a first compressor 10 and a second compressor 20, P3 is a target suction pressure, and ΔP2 is a loading differential pressure.

[0070] Further, in order to increase the service life of the compressor, the loading sequence of the compressor is loaded according to the total running time of each compressor from short to long, and the unloading sequence of the compressor is unloaded according to the starting sequence of the compressor or unloaded according to the total running time of each compressor from long to short.

[0071] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used in this description, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising", when used in this specification, specify the presence of stated features, steps, operations, devices, components and / or combinations thereof, but do not preclude the presence or addition of one or more other features, steps, operations, devices, components and / or combinations thereof.

[0072] The foregoing is considered as illustrative only of the principles of the application. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the application to the exact construction and practice described. Accordingly, all such variations are intended to be included within the scope of the present application as defined in the following claims, along with full equivalents thereof.

[0073] In the description of the present application, it is to be understood that the orientation or positional relationships indicated by terms such as "front", "back", "up", "down", "left", "right", "lateral", "vertical", "horizontal", "top", "bottom", and the like are generally based on the orientation or positional relationships shown in the drawings, and are merely intended to facilitate the description of the present application and simplify the description, and do not indicate or imply that the device or element must have a particular orientation or be constructed and operated in a particular orientation, and therefore should not be construed as limiting the scope of protection of the present application. The orientation terms "inner", "outer" refer to the inner and outer relative to the contour of the components themselves.

[0074] For the convenience of description, spatial relative terms such as "above", "upper", "top", "up", and the like can be used herein to describe the spatial relationship of one device or feature to another device or feature as shown in the drawings. It should be understood that the spatial relative terms are intended to include different orientations of the device in use or operation in addition to the orientation of the device described in the drawings. For example, if the device in the drawings is inverted, the device described as "above" or "on" the other device or structure will be positioned "below" or "under" the other device or structure. Thus, the exemplary term "above" can include both the "above" and "below" orientations. The device can also be positioned in other different ways (rotated 90 degrees or in other orientations) and the spatial relative descriptions used herein will be interpreted accordingly.

[0075] In addition, it should be noted that the use of the terms "first", "second", and the like do not have a special meaning, and therefore should not be construed as limiting the scope of protection of the present application, unless otherwise stated.

[0076] The above merely provides the preferred embodiments of the present application, and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the principles and technical scope of the present application shall fall into the scope of the present application.

Claims

1. A control method for a refrigeration defrosting unit, characterized in that, The refrigeration and defrosting unit includes: The refrigeration unit includes a first compressor (10), a condenser and an evaporator connected in sequence; The defrosting unit includes a second compressor (20), which has a refrigeration state and a refrigeration defrosting state. The second compressor (20) has a first inlet end and a first outlet end arranged opposite to each other. The first inlet end is connected to the outlet of the evaporator. The defrosting unit also has a refrigeration pipe (31) and a defrosting pipe (32). The refrigeration pipe (31) and the defrosting pipe (32) are both connected to the first outlet end. The refrigeration pipe (31) is connected to the inlet of the condenser. The defrosting pipe (32) is connected to the inlet of the evaporator. The defrosting pipe (32) is used to input high-temperature refrigerant into the evaporator to heat and defrost the evaporator. When the defrosting unit is in the refrigeration state, the refrigeration pipe (31) is connected to the condenser, and the defrosting pipe (32) is disconnected from the evaporator; when the defrosting unit is in the refrigeration defrosting state, the refrigeration pipe (31) is disconnected from the condenser, and the defrosting pipe (32) is connected to the evaporator. When the refrigeration defrosting unit is in the refrigeration defrosting state, the control method includes the following steps: Step 1: Start and obtain the operating parameters of the second compressor (20) of the refrigeration defrosting unit. When the operating parameters of the second compressor (20) meet the first preset condition, load the second compressor (20) of the refrigeration defrosting unit. When the operating parameters of the second compressor (20) meet the second preset condition, stop loading the second compressor (20). Step 2: Start and obtain the operating parameters of the first compressor (10) of the refrigeration defrosting unit. When the operating parameters of the first compressor (10) meet the third preset condition, load the first compressor (10) until the operating parameters of the first compressor (10) meet the fourth preset condition, then stop loading the first compressor (10). The operating parameters of the second compressor (20) include the actual discharge pressure PT1 of the second compressor (20), the first preset condition includes the target defrosting pressure P1 of the second compressor (20) and the first time T1, the second compressor (20) satisfies the first preset condition specifically including: PT1≤P1, and lasts for T1 time; the second preset condition specifically includes: PT1=P1; The operating parameters of the first compressor (10) include the actual suction pressure PT2 of the first compressor (10), and the third preset condition includes the target suction pressure P2 of the first compressor, the loading pressure difference ΔP1 and the second time T2. When the first compressor (10) meets the third preset condition, it specifically includes: PT2≥P2+ΔP1 and lasts for T2 time. The operating parameters of the first compressor (10) satisfy the fourth preset condition, specifically including: P2≤PT2≤P2+ΔP1; The control method for the refrigeration defrosting unit also includes: When stopping the operation of the first compressor (10) and the second compressor (20), the first compressor (10) is unloaded first, and then the second compressor (20) is unloaded.

2. The control method for the refrigeration defrosting unit according to claim 1, characterized in that, The control method for the refrigeration defrosting unit also includes: When PT1 > P1 and this condition persists for time T3, the second compressor (20) is unloaded. When PT2 < P2 and the duration is T4, the first compressor (10) is unloaded.

3. The control method for the refrigeration defrosting unit according to claim 1, characterized in that, When there are multiple second compressors (20), the second compressors (20) are unloaded according to the starting sequence of the multiple second compressors (20); when there are multiple first compressors (10), the first compressors (10) are unloaded according to the starting sequence of the multiple first compressors (10).

4. The control method for the refrigeration defrosting unit according to claim 1, characterized in that, The refrigeration unit also includes a first oil separator (41), and the defrosting unit also includes a second oil separator (42). The first oil separator (41) has a first mixing inlet (411), a first air outlet (412) and a first oil return outlet (413). The first oil separator (41) is located between the first compressor (10) and the condenser. The air outlet of the first compressor (10) is connected to the first mixing inlet (411), the first air outlet (412) is connected to the inlet of the condenser, and the first oil return outlet (413) is connected to the oil inlet of the first compressor (10). The second oil separator (42) has a second mixing inlet (421), a second air outlet (422), and a second oil return outlet (423). The air outlet of the second compressor (20) is connected to the second mixing inlet (421) of the second oil separator (42). The refrigeration pipeline (31) and the defrosting pipeline (32) are both connected to the second air outlet (422) of the second oil separator (42). The second oil return outlet (423) is connected to the oil inlet of the second compressor (20). The first oil return outlet (413) is connected to the second oil return outlet (423).

5. The control method for the refrigeration defrosting unit according to claim 4, characterized in that, The refrigeration defrosting unit also includes a main oil return pipe (50), a first branch pipe (51), a second branch pipe (52), and a first solenoid valve (501). The two ends of the main oil return pipe (50) are connected to the first oil return port (413) and the second oil return port (423) respectively. One end of the first branch pipe (51) is connected to the main oil return pipe (50), and the other end of the first branch pipe (51) is connected to the oil inlet of the first compressor (10). One end of the second branch pipe (52) is connected to the main oil return pipe (50), and the other end of the second branch pipe (52) is connected to the oil inlet of the second compressor (20). The first solenoid valve (501) is installed on the main oil return pipe (50) and is located between the first branch pipe (51) and the second branch pipe (52).

6. The control method for the refrigeration defrosting unit according to claim 5, characterized in that, The refrigeration defrosting unit also includes a second solenoid valve (511) and a third solenoid valve (521). The second solenoid valve (511) is installed on the first branch pipe (51), and the third solenoid valve (521) is installed on the second branch pipe (52).

7. The control method for the refrigeration defrosting unit according to claim 5, characterized in that, The refrigeration defrosting unit also includes a first oil level observation section (61) and a second oil level observation section (62). The first oil level observation section (61) and the second oil level observation section (62) are both provided on the return oil main pipe (50). The first oil level observation section (61) is located between the connection between the first branch pipe (51) and the return oil main pipe (50) and the first return oil port (413). The second oil level observation section (62) is located between the connection between the second branch pipe (52) and the return oil main pipe (50) and the second return oil port (423).

8. The control method for the refrigeration defrosting unit according to claim 5, characterized in that, The refrigeration defrosting unit also includes a first drying filter section (71) and a second drying filter section (72). The first drying filter section (71) and the second drying filter section (72) are both disposed on the oil return main pipe (50). The first drying filter section (71) is located between the connection between the first branch pipe (51) and the oil return main pipe (50) and the first oil return port (413). The second drying filter section (72) is located between the connection between the second branch pipe (52) and the oil return main pipe (50) and the second oil return port (423).

9. The control method for the refrigeration defrosting unit according to claim 1, characterized in that, The refrigeration unit includes multiple first compressors (10) connected in parallel; and / or The defrosting unit includes multiple second compressors (20) connected in parallel.

10. The control method for the refrigeration defrosting unit according to claim 1, characterized in that, The refrigeration defrosting unit also includes a fourth solenoid valve (311) and a fifth solenoid valve (321). The fourth solenoid valve (311) is installed on the refrigeration pipeline (31), and the fifth solenoid valve (321) is installed on the defrosting pipeline (32).

11. The control method for the refrigeration defrosting unit according to claim 1, characterized in that, The defrosting unit further includes a first filter section (81), which is disposed between the evaporator and the first compressor (10). The first filter section (81) is used to filter the vapor entering the first compressor (10); and / or, The refrigeration unit also includes a second filter section (82), which is disposed between the evaporator and the second compressor (20). The second filter section (82) is used to filter the vapor entering the second compressor (20).

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