Cascade compression refrigeration system, refrigeration device and control method thereof

Abstract

The application provides a cascade compression refrigeration system, a refrigeration device and a control method. The refrigeration system comprises a high-temperature stage and a low-temperature stage refrigeration cycle circuit. The high-temperature stage refrigeration cycle circuit comprises a high-temperature stage compressor, a switching valve, a parallel branch, a high-temperature stage evaporator and a high-temperature stage gas return pipe arranged in series. The parallel branch comprises a first cold supply branch and a second cold supply branch arranged in parallel. The first cold supply branch comprises a first throttling device. The second cold supply branch comprises a second throttling device and an evaporation part. First refrigerants flowing through the first and second throttling devices exchange heat with a first refrigerant flowing through the high-temperature stage gas return pipe. The low-temperature stage refrigeration cycle circuit comprises a low-temperature stage compressor and a condensation part. A second refrigerant flowing through the condensation part exchanges heat with the first refrigerant flowing through the evaporation part. The high-temperature stage compressor and the low-temperature stage compressor are both variable frequency compressors. The application can solve the problem that the existing refrigeration system cannot meet the classification storage of different food materials.

Description

Technical Field

[0001] This invention relates to the field of refrigeration equipment technology, and in particular to a cascade compression refrigeration system, a refrigeration device having the same, and a control method for the refrigeration device. Background Technology

[0002] As people's living standards continue to improve and their concept of healthy living becomes more comprehensive, people not only pursue balanced nutrition, but also have an increasing demand for and reserves of high-end and precious ingredients. However, different ingredients have different requirements for preservation and storage. For example, under normal storage conditions, high-end and precious ingredients are prone to spoilage. How to improve the storage effect of high-end and precious ingredients while taking into account the preservation and storage of normal ingredients is an urgent problem to be solved.

[0003] Therefore, multiple compartments with different temperature zones are needed in refrigeration equipment to meet the needs of categorizing and storing different ingredients. However, existing refrigeration equipment only has storage compartments with a single temperature zone, which cannot meet the needs of categorizing and storing different ingredients. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention aims to provide a cascade compression refrigeration system, a refrigeration device having the same, and a control method for the refrigeration device, in order to solve the problem that existing refrigeration systems cannot meet the requirements for the classified storage of different food ingredients.

[0005] To achieve one of the above-mentioned objectives, one embodiment of the present invention provides a cascade compression refrigeration system, comprising:

[0006] A high-temperature refrigeration cycle includes a high-temperature compressor, a switching valve, parallel branches, a high-temperature evaporator, and a high-temperature return pipe connected in series. A first refrigerant flows through the high-temperature refrigeration cycle. The parallel branches include a first cooling branch and a second cooling branch connected in parallel. The first cooling branch includes a first throttling device, and the second cooling branch includes a second throttling device and an evaporator connected in series. The switching valve can be selectively connected to at least one of the first cooling branch and the second cooling branch. The first refrigerant flowing through the first throttling device and the first refrigerant flowing through the second throttling device exchange heat with the first refrigerant flowing through the high-temperature return pipe.

[0007] A low-temperature stage refrigeration cycle circuit includes a low-temperature stage compressor and a condenser section. A second refrigerant flows through the low-temperature stage refrigeration cycle circuit, and the second refrigerant flowing through the condenser section exchanges heat with the first refrigerant flowing through the evaporator section.

[0008] Both the high-temperature stage compressor and the low-temperature stage compressor are variable frequency compressors.

[0009] To achieve one of the above-mentioned objectives, one embodiment of the present invention also provides a refrigeration device, including a housing and a cascade compression refrigeration system as described above. The housing has a first storage chamber and a second storage chamber. The high-temperature stage refrigeration cycle circuit supplies cooling to the first storage chamber, and the low-temperature stage refrigeration cycle circuit supplies cooling to the second storage chamber.

[0010] As a further improvement to one embodiment of the present invention, the refrigeration device further includes a controller, which is connected to the switching valve and is used for,

[0011] When the switching valve is only connected to the second cooling branch, and both the high-temperature compressor and the low-temperature compressor are running, determine whether the temperature T1 inside the first storage room is greater than its preset start-up temperature T. 1开 ;

[0012] If so, then the speed of the high-temperature stage compressor is increased, or the speed of the low-temperature stage compressor is decreased, or the speed of the high-temperature stage compressor is increased and the speed of the low-temperature stage compressor is decreased.

[0013] If not, then control the speed of the high-temperature stage compressor to decrease, or control the speed of the low-temperature stage compressor to increase, or control the speed of the high-temperature stage compressor to decrease and control the speed of the low-temperature stage compressor to increase.

[0014] As a further improvement to one embodiment of the present invention, the controller is also used for,

[0015] If the switching valve is only connected to the second cooling branch, and both the high-temperature compressor and the low-temperature compressor are running, then the duration of the switching valve being in the state of only being connected to the second cooling branch is timed. After a preset time t1, if the temperature T2 in the second storage room has not dropped to its preset shutdown temperature T, then... 2关 If the temperature T1 inside the first storage room is lower than its preset start-up temperature T, then determine whether the temperature T1 inside the first storage room is lower than its preset start-up temperature T. 1开 ;

[0016] If so, the duration of the switching valve being in a state of being connected only to the second cooling branch is re-timed;

[0017] If not, then determine whether T1 and T2 meet the first preset condition, which is: T1 < the preset temperature T of the first storage room. 10 And T2 < the preset temperature T of the first storage room 20 ;

[0018] If T1 and T2 meet the first preset condition, then the switching valve is controlled to switch to be connected to both the first cooling branch and the second cooling branch simultaneously, and the speed of the high-temperature stage compressor is controlled to increase, or the speed of the low-temperature stage compressor is controlled to decrease, or the speed of the high-temperature stage compressor is controlled to increase and the speed of the low-temperature stage compressor is controlled to decrease.

[0019] As a further improvement to one embodiment of the present invention, the controller is also used for,

[0020] If T1 and T2 do not meet the first preset conditions, the cryogenic compressor is controlled to stop, and the switching valve is controlled to switch to only connect with the first cooling branch.

[0021] As a further improvement to one embodiment of the present invention, the controller is also used for,

[0022] If the switching valve is only connected to the second cooling branch, and both the high-temperature compressor and the low-temperature compressor are running, then the duration of the switching valve being in the state of only being connected to the second cooling branch is timed. Within a preset time t1, if the temperature T2 in the second storage room drops to its preset shutdown temperature T... 2关 If so, the low-temperature stage compressor is stopped, and it is determined whether the temperature T1 inside the first storage room meets the second preset condition;

[0023] If so, control the switching valve to switch to only connect to the first cooling branch;

[0024] If not, then control the high-temperature stage compressor to shut down;

[0025] The second preset condition is: at this moment T1 ≥ the preset start-up temperature T of the first storage room. 1开 Alternatively, the preset shutdown temperature T of the first storage compartment. 1关 <T1<T 1开 And before that moment, T1 is always greater than T. 1关 .

[0026] To achieve one of the above-mentioned objectives, one embodiment of the present invention also provides a control method for a refrigeration device, the control method comprising:

[0027] When the switching valve is only connected to the second cooling branch, and both the high-temperature compressor and the low-temperature compressor are running, determine whether the temperature T1 inside the first storage room is greater than its preset start-up temperature T. 1开 ;

[0028] If so, then the speed of the high-temperature stage compressor is increased, or the speed of the low-temperature stage compressor is decreased, or the speed of the high-temperature stage compressor is increased and the speed of the low-temperature stage compressor is decreased.

[0029] If not, then control the speed of the high-temperature stage compressor to decrease, or control the speed of the low-temperature stage compressor to increase, or control the speed of the high-temperature stage compressor to decrease and control the speed of the low-temperature stage compressor to increase.

[0030] As a further improvement to one embodiment of the present invention, the control method further includes,

[0031] If the switching valve is only connected to the second cooling branch, and both the high-temperature compressor and the low-temperature compressor are running, then the duration of the switching valve being in the state of only being connected to the second cooling branch is timed. After a preset time t1, if the temperature T2 in the second storage room has not dropped to its preset shutdown temperature T, then... 2关 If the temperature T1 inside the first storage room is lower than its preset start-up temperature T, then determine whether the temperature T1 inside the first storage room is lower than its preset start-up temperature T. 1开 ;

[0032] If so, the duration of the switching valve being in a state of being connected only to the second cooling branch is re-timed;

[0033] If not, then determine whether T1 and T2 meet the first preset condition, which is: T1 < the preset temperature T of the first storage room. 10 And T2 < the preset temperature T of the first storage room 20 ;

[0034] If T1 and T2 meet the first preset condition, then the switching valve is controlled to switch to simultaneously connect with the first cooling branch and the second cooling branch, and the speed of the high-temperature stage compressor is controlled to increase, or the speed of the low-temperature stage compressor is controlled to decrease, or the speed of the high-temperature stage compressor is controlled to increase and the speed of the low-temperature stage compressor is controlled to decrease.

[0035] As a further improvement to one embodiment of the present invention, the control method further includes,

[0036] If T1 and T2 do not meet the first preset conditions, the cryogenic compressor is controlled to stop, and the switching valve is controlled to switch to only connect with the first cooling branch.

[0037] As a further improvement to one embodiment of the present invention, the control method further includes,

[0038] If the switching valve is only connected to the second cooling branch, and both the high-temperature compressor and the low-temperature compressor are running, then the duration of the switching valve being in the state of only being connected to the second cooling branch is timed. Within a preset time t1, if the temperature T2 in the second storage room drops to its preset shutdown temperature T... 2关 If so, the low-temperature stage compressor is stopped, and it is determined whether the temperature T1 inside the first storage room meets the second preset condition;

[0039] If so, control the switching valve to switch to only connect to the first cooling branch;

[0040] If not, then control the high-temperature stage compressor to shut down;

[0041] The second preset condition is: at this moment T1 ≥ the preset start-up temperature T of the first storage room. 1开 Alternatively, the preset shutdown temperature T of the first storage compartment. 1关 <T1<T 1开 And before that moment, T1 is always greater than T. 1关 .

[0042] Compared with the prior art, the present invention has the following beneficial effects: In the cascade compression refrigeration system, the refrigeration device having the same, and the control method of the refrigeration device of the present invention, when the first refrigerant flows in the first cooling branch, the high-temperature evaporator cools the first storage compartment; when the first refrigerant flows in the second cooling branch, the first refrigerant flows out from the second throttling device to the evaporation section in the high-temperature refrigeration cycle loop. Through the heat exchange between the second refrigerant flowing through the condensation section and the first refrigerant flowing through the evaporation section, the first refrigerant in the evaporation section can absorb the heat of the second refrigerant flowing through the condensation section, thereby further reducing the temperature of the second refrigerant in the condensation section, pre-cooling the low-temperature refrigeration cycle loop, thereby enabling the low-temperature refrigeration cycle loop to achieve a lower temperature. In addition, the first refrigerant flowing out of the evaporation section flows into the high-temperature evaporator. It can also provide cooling capacity to the first storage compartment. Simultaneously, since the first refrigerant flowing through the first throttling device and the first refrigerant flowing through the second throttling device exchange heat with the first refrigerant flowing through the high-temperature stage return pipe, the first refrigerant in the high-temperature stage return pipe can be used to cool the first refrigerant in the first and second throttling devices, increasing the cooling capacity. This also raises the suction temperature of the high-temperature stage compressor to approximately the ambient temperature, improving the cooling efficiency of the high-temperature stage compressor and the working efficiency of the high-temperature stage refrigeration cycle loop. Furthermore, the operating frequency of the high-temperature stage compressor and the low-temperature stage compressor can be adjusted according to the different temperatures of the various storage compartments, so that the high-temperature stage refrigeration cycle loop and the low-temperature stage refrigeration cycle loop generate the cooling capacity required by their respective storage compartments, thus preventing excessive operating pressure in the refrigeration system. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of a cascade compression refrigeration system according to an embodiment of the present invention. Detailed Implementation

[0044] The present invention will now be described in detail with reference to the specific embodiments shown in the accompanying drawings.

[0045] In the various illustrations of this invention, for ease of illustration, certain dimensions of structures or parts may be enlarged relative to other structures or parts; therefore, only the basic structure of the subject matter of this invention is used to illustrate the invention.

[0046] It should be understood that although the terms first, second, etc., may be used in this document to describe various elements or structures, the objects being described should not be limited by these terms. These terms are only used to distinguish these objects from one another.

[0047] A refrigeration device provided in one embodiment of the present invention includes a cabinet and a door. The cabinet has a storage compartment, and the door is used to open or close the storage compartment. The refrigeration device also includes a refrigeration system disposed in the cabinet and supplying cooling to the storage compartment. Specifically, the refrigeration device can be configured as a freezer, refrigerator, etc., to meet the needs of different users and different application scenarios.

[0048] In this embodiment, the cabinet has a first storage compartment and a second storage compartment. The first storage compartment can be a refrigerator compartment or a freezer compartment, and the second storage compartment can be a variable temperature compartment or a cryogenic compartment. The refrigeration system adopts a cascade compression refrigeration system 100, specifically including a high-temperature stage refrigeration cycle loop 1 and a low-temperature stage refrigeration cycle loop 2.

[0049] For ease of description, this embodiment uses the example of a high-temperature refrigeration cycle loop 1 cooling the first storage compartment and a low-temperature refrigeration cycle loop 2 cooling the second storage compartment. Of course, the two can be interchanged.

[0050] Of course, in other embodiments, other storage rooms besides the first and second storage rooms can be provided according to actual needs.

[0051] See Figure 1The high-temperature refrigeration cycle loop 1 includes a high-temperature compressor 11, a switching valve 17, parallel branches, and a high-temperature return pipe 13 connecting a high-temperature evaporator 15 and a high-temperature compressor 11, all connected in series. A first refrigerant flows through the high-temperature refrigeration cycle loop 1. The parallel branches include a first cooling branch and a second cooling branch connected in parallel. The first cooling branch includes a first throttling device 161, and the second cooling branch includes a second throttling device 162 and an evaporator 12 connected in series. The switching valve 17 can be selectively connected to at least one of the first cooling branch and the second cooling branch. The first refrigerant flowing through the first throttling device 161 and the first refrigerant flowing through the second throttling device 162 exchange heat with the first refrigerant flowing through the high-temperature return pipe 13. The switching valve 17, located at the inlet of the parallel branch, can be selectively connected to at least one of the first cooling branch and the second cooling branch, thereby selectively controlling the flow direction of the first refrigerant as needed to achieve different functions and cooling effects. In this way, the first storage compartment can achieve a temperature range of -30 to 10°C.

[0052] The low-temperature stage refrigeration cycle loop 2 includes a low-temperature stage compressor 22 and a condenser section 21. A second refrigerant flows through the low-temperature stage refrigeration cycle loop 2, and the second refrigerant flowing through the condenser section 21 exchanges heat with the first refrigerant flowing through the evaporator section 12.

[0053] In this embodiment, both the high-temperature stage compressor 11 and the low-temperature stage compressor 22 are variable frequency compressors, which can adjust the operating frequency of the high-temperature stage compressor 11 and the low-temperature stage compressor 22 according to the different temperatures of different storage compartments, so that the high-temperature stage refrigeration cycle loop 1 and the low-temperature stage refrigeration cycle loop 2 can generate the cooling capacity required by their corresponding storage compartments, so as to avoid excessive operating pressure of the refrigeration system.

[0054] Thus, when the first refrigerant flows in the first cooling branch, the high-temperature evaporator 15 cools the first storage compartment; when the first refrigerant flows in the second cooling branch, it flows out from the second throttling device 162 to the evaporator 12 in the high-temperature refrigeration cycle 1. Through heat exchange between the second refrigerant flowing through the condenser 21 and the first refrigerant flowing through the evaporator 12, the first refrigerant in the evaporator 12 can absorb the heat from the second refrigerant flowing through the condenser 21, thereby further reducing the temperature of the second refrigerant in the condenser 21, pre-cooling the low-temperature refrigeration cycle 2, thus enabling the low-temperature refrigeration cycle 2 to achieve an even lower temperature. Furthermore, after evaporation... The first refrigerant flowing out of the evaporator 12 flows into the high-temperature stage evaporator 15, which can also provide cooling for the first storage compartment. At the same time, since the first refrigerant flowing through the first throttling device 161 and the first refrigerant flowing through the second throttling device 162 exchange heat with the first refrigerant flowing through the high-temperature stage return pipe 13, the first refrigerant in the high-temperature stage return pipe 13 can be used to cool down the first refrigerant in the first throttling device 161 and the second throttling device 162, thereby increasing the cooling capacity and raising the suction temperature of the high-temperature stage compressor 11 to about the ambient temperature, thus improving the cooling efficiency of the high-temperature stage compressor 11 and the working efficiency of the high-temperature stage refrigeration cycle loop 1.

[0055] Preferably, both the first throttling device 161 and the second throttling device 162 are capillary tubes.

[0056] The first throttling device 161 and the second throttling device 162 are thermally connected to the high-temperature stage return gas pipe 13 by means of mutual sleeve or close contact, which is conducive to improving the heat exchange efficiency of the second refrigerant flowing in the two and improving the energy utilization rate.

[0057] Furthermore, the high-temperature refrigeration cycle loop 1 also includes a high-temperature drying filter 18 disposed between the high-temperature condenser 14 and the parallel branch, and a liquid storage tank 19 disposed between the high-temperature evaporator 15 and the high-temperature return gas pipe 13.

[0058] The low-temperature refrigeration cycle loop 2 also includes a low-temperature throttling device 23, a low-temperature evaporator 24 and a first return gas pipe section 25 arranged in series, and the condenser section 21 is located between the low-temperature compressor 22 and the low-temperature throttling device 23.

[0059] Furthermore, the second refrigerant flowing through the first return gas pipe section 25 exchanges heat with the second refrigerant flowing through the low-temperature stage throttling device 23. This allows the second refrigerant flowing through the first return gas pipe section 25 to absorb the heat from the second refrigerant flowing through the low-temperature stage throttling device 23, increasing the temperature of the second refrigerant flowing towards the suction inlet of the low-temperature stage compressor 22. This, in turn, increases the suction temperature of the low-temperature stage compressor 22, improves the energy utilization rate of the low-temperature stage refrigeration cycle loop 2, and enhances the overall energy efficiency of the refrigeration system.

[0060] Preferably, the low-temperature stage throttling device 23 is a capillary tube, and the first return gas pipe section 25 is connected to or attached to the low-temperature stage throttling device 23 to facilitate the heat exchange efficiency of the second refrigerant flowing between them and improve energy utilization.

[0061] Furthermore, the low-temperature refrigeration cycle 2 also includes a second return gas pipe section 26 and a heat release pipe section 27. The second return gas pipe section 26 is located between the low-temperature evaporator 24 and the low-temperature compressor 22, and the heat release pipe section 27 is located between the low-temperature compressor 22 and the condenser section 21. The second refrigerant flowing through the second return gas pipe section 26 exchanges heat with the second refrigerant flowing through the heat release pipe section 27. This allows the second refrigerant flowing through the second return gas pipe section 26 to absorb the heat of the second refrigerant flowing through the heat release pipe section 27, increasing the suction temperature of the low-temperature compressor 22 and reducing the amount of cooling energy of the second refrigerant flowing from the heat release pipe section 27 to the condenser section 21. This enables the low-temperature refrigeration cycle 2 to achieve a lower temperature, allowing the second storage compartment to be temperature-adjustable within the range of -60 to -20°C. It also improves the energy utilization rate of the low-temperature refrigeration cycle 2 and enhances the overall energy efficiency of the refrigeration system.

[0062] Preferably, the second return gas pipe section 26 is located between the first return gas pipe section 25 and the low-temperature stage compressor 22, which can maximize the energy utilization rate of the low-temperature stage refrigeration cycle loop 2.

[0063] The second return gas pipe section 26 and the heat release pipe section 27 are connected or attached to each other to facilitate heat exchange of the second refrigerant flowing in the two and improve energy utilization.

[0064] Furthermore, the low-temperature refrigeration cycle 2 also includes a low-temperature heat dissipation pipe 28 disposed between the low-temperature compressor 22 and the heat dissipation tube section 27, and a low-temperature dryer filter 29 disposed between the condenser section 21 and the low-temperature throttling device 23. The low-temperature heat dissipation pipe 28 dissipates heat from the second refrigerant flowing out of the low-temperature compressor 22, thereby enabling the low-temperature refrigeration cycle 2 to achieve a lower temperature; the low-temperature dryer filter 29 dries and filters the second refrigerant flowing out of the condenser section 21.

[0065] The first and second refrigerants can be the same refrigerant or different refrigerants.

[0066] In addition, "high temperature" and "low temperature" in "high temperature refrigeration cycle loop 1" and "low temperature refrigeration cycle loop 2" are relative terms. Relatively speaking, the evaporation temperature of the first refrigerant flowing through the high temperature refrigeration cycle loop 1 is higher than the evaporation temperature of the second refrigerant flowing through the low temperature refrigeration cycle loop 2.

[0067] Furthermore, the refrigeration device also includes a controller connected to the switching valve 17, and is used to control the connection status of the switching valve 17 with the first cooling branch and the second cooling branch, as well as the operating status and operating frequency of the high-temperature compressor 11 and the low-temperature compressor 22, according to the temperatures of the first storage compartment and the second storage compartment.

[0068] Specifically, the controller is used for,

[0069] When the switching valve 17 is only connected to the second cooling branch, and both the high-temperature compressor 11 and the low-temperature compressor 22 are running, determine whether the temperature T1 inside the first storage room is greater than its preset start-up temperature T. 1开 ;

[0070] If so, the speed of the high-temperature stage compressor 11 is increased, or the speed of the low-temperature stage compressor 22 is decreased, or the speed of the high-temperature stage compressor 11 is increased and the speed of the low-temperature stage compressor 22 is decreased.

[0071] If not, then the speed of the high-temperature stage compressor 11 is reduced, or the speed of the low-temperature stage compressor 22 is increased, or the speed of the high-temperature stage compressor 11 is reduced and the speed of the low-temperature stage compressor 22 is increased.

[0072] In this way, by adjusting the speed of the high-temperature stage compressor 11 and the low-temperature stage compressor 22, the cooling capacity and refrigeration efficiency of the high-temperature stage evaporator 15 and the low-temperature stage evaporator 24 can be adjusted, thereby simultaneously cooling the first storage compartment and the second storage compartment, while avoiding excessive operating pressure of the refrigeration system.

[0073] Specifically, the controller is also used for,

[0074] If the switching valve 17 is only connected to the second cooling branch, and both the high-temperature compressor 11 and the low-temperature compressor 22 are running, then the duration of the switching valve 17 being in the state of only being connected to the second cooling branch is timed. After a preset time t1, if the temperature T2 in the second storage room has not dropped to its preset shutdown temperature T, then... 2关If the temperature T1 inside the first storage room is lower than its preset start-up temperature T, then determine whether the temperature T1 inside the first storage room is lower than its preset start-up temperature T. 1开 ;

[0075] If so, the duration of the switching valve 17 being in a state of being connected only to the second cooling branch is restarted;

[0076] If not, then determine whether T1 and T2 meet the first preset condition, which is: T1 < the preset temperature T of the first storage room. 10 And T2 < the preset temperature T of the first storage room 20 ;

[0077] If T1 and T2 meet the first preset condition, then control the switching valve 17 to switch to be connected to both the first cooling branch and the second cooling branch simultaneously, and control the speed of the high-temperature compressor 11 to increase, or control the speed of the low-temperature compressor 22 to decrease, or control the speed of the high-temperature compressor 11 to increase and control the speed of the low-temperature compressor 22 to decrease.

[0078] In other words, when the switching valve 17 is only connected to the second cooling branch, the evaporator 12 and the condenser 21 exchange heat, and the low-temperature evaporator 24 cools the second storage room. Additionally, the first refrigerant flowing from the evaporator 12 flows into the high-temperature evaporator 15, thus the high-temperature evaporator 15 cools the first storage room. Within a preset time t1, the temperature of the first storage room also decreases. However, because the evaporator 12 and the condenser 21 exchange heat, the high-temperature evaporator 15 provides less cooling to the first storage room. Therefore, if, after the preset time t1, T2 has not yet dropped to T... 2关 Or below, and T1 is less than T 1开 Then, the timer for the duration during which the switching valve 17 is in a state of being connected only to the second cooling branch is restarted, and the above steps are repeated; if, after a preset time t1, T2 has not yet dropped to T... 2关 Or below, and the temperature T1 of the first storage compartment has not dropped to its preset shutdown temperature T. 1关 And T1 <T 10 T2 <T 20 Then, the control switching valve 17 is connected to the first cooling branch and the second cooling branch at the same time, and the speed of the high-temperature compressor 11 and the low-temperature compressor 22 is adjusted to accelerate the cooling of the first storage room, so as to avoid the temperature of the first storage room from failing to drop to the preset temperature for a long time, which is not conducive to the preservation of food. At the same time, it also avoids the excessive system pressure caused by the simultaneous operation of the high-temperature compressor 11 and the low-temperature compressor 22.

[0079] Preferably, t1 = 5 to 40 minutes. On the one hand, during this time period, the low-temperature refrigeration cycle loop 2 can have a higher refrigeration efficiency, which can accelerate the cooling of the second storage room. On the other hand, it can prevent the first storage room from not receiving sufficient cooling for a long time, which would cause the temperature inside to remain at a high level for a long time.

[0080] Preferably, T 10 = -30~20℃, thus avoiding excessively high actual temperature in the first storage compartment and avoiding excessive system pressure caused by the simultaneous operation of high-temperature compressor 11 and low-temperature compressor 22.

[0081] Preferably, T 20 = -30~20℃, which can avoid the actual temperature of the second storage room being too high, and avoid the system pressure being too high due to the simultaneous operation of the high-temperature compressor 11 and the low-temperature compressor 22.

[0082] Furthermore, the controller is also used to,

[0083] If T1 and T2 do not meet the first preset conditions, the low-temperature stage compressor 22 is controlled to stop, and the switching valve 17 is controlled to switch to only connect with the first cooling branch, so as to accelerate the cooling efficiency of the high-temperature stage evaporator 15 to the first storage room.

[0084] Furthermore, the controller is also used to,

[0085] If the switching valve 17 is only connected to the second cooling branch, and both the high-temperature compressor 11 and the low-temperature compressor 22 are running, then the duration of the switching valve 17 being in the state of only being connected to the second cooling branch is timed. Within a preset time t1, if T2 drops to T... 2关 If so, control the low-temperature stage compressor 22 to stop, and determine whether T1 meets the second preset condition;

[0086] If so, control the switching valve 17 to switch to only connect to the first cooling branch;

[0087] If not, then control the high-temperature stage compressor 11 to stop;

[0088] The second preset condition is: at this moment T1 ≥ the preset start-up temperature T of the first storage room. 1开 Alternatively, the preset shutdown temperature T of the first storage compartment. 1关 <T1<T 1开 And before that moment, T1 is always greater than T. 1关 .

[0089] In other words, if the temperature of the second storage room drops to its preset shutdown temperature within a preset time t1, the low-temperature compressor 22 can be shut down to save energy and reduce system operating pressure. At this time, the temperature of the first storage room is judged. If it meets the second preset condition, it indicates that the first storage room still needs to be cooled. At this time, the switching valve 17 can be switched to only connect to the first cooling branch to cool the first storage room. If the temperature of the first storage room does not meet the second preset condition, it indicates that the first storage room does not need to be cooled. At this time, the high-temperature compressor 11 can be shut down to save energy and reduce system operating pressure.

[0090] One embodiment of the present invention also provides a control method for the refrigeration device as described above, comprising,

[0091] When the switching valve 17 is only connected to the second cooling branch, and both the high-temperature compressor 11 and the low-temperature compressor 22 are running, determine whether the temperature T1 inside the first storage room is greater than its preset start-up temperature T. 1开 ;

[0092] If so, the speed of the high-temperature stage compressor 11 is increased, or the speed of the low-temperature stage compressor 22 is decreased, or the speed of the high-temperature stage compressor 11 is increased and the speed of the low-temperature stage compressor 22 is decreased.

[0093] If not, then the speed of the high-temperature stage compressor 11 is reduced, or the speed of the low-temperature stage compressor 22 is increased, or the speed of the high-temperature stage compressor 11 is reduced and the speed of the low-temperature stage compressor 22 is increased.

[0094] In this way, by adjusting the speed of the high-temperature stage compressor 11 and the low-temperature stage compressor 22, the cooling capacity and refrigeration efficiency of the high-temperature stage evaporator 15 and the low-temperature stage evaporator 24 can be adjusted, thereby simultaneously cooling the first storage compartment and the second storage compartment, while avoiding excessive operating pressure of the refrigeration system.

[0095] Specifically, the control method further includes,

[0096] If the switching valve 17 is only connected to the second cooling branch, and both the high-temperature compressor 11 and the low-temperature compressor 22 are running, then the duration of the switching valve 17 being in the state of only being connected to the second cooling branch is timed. After a preset time t1, if the temperature T2 in the second storage room has not dropped to its preset shutdown temperature T, then... 2关 If the temperature T1 inside the first storage room is lower than its preset start-up temperature T, then determine whether the temperature T1 inside the first storage room is lower than its preset start-up temperature T. 1开 ;

[0097] If so, the duration of the switching valve 17 being in a state of being connected only to the second cooling branch is restarted;

[0098] If not, then determine whether T1 and T2 meet the first preset condition, which is: T1 < the preset temperature T of the first storage room. 10 And T2 < the preset temperature T of the first storage room 20 ;

[0099] If T1 and T2 meet the first preset condition, then control the switching valve 17 to switch to be connected to both the first cooling branch and the second cooling branch simultaneously, and control the speed of the high-temperature compressor 11 to increase, or control the speed of the low-temperature compressor 22 to decrease, or control the speed of the high-temperature compressor 11 to increase and control the speed of the low-temperature compressor 22 to decrease.

[0100] In other words, when the switching valve 17 is only connected to the second cooling branch, the evaporator 12 and the condenser 21 exchange heat, and the low-temperature evaporator 24 cools the second storage room. Additionally, the first refrigerant flowing from the evaporator 12 flows into the high-temperature evaporator 15, thus the high-temperature evaporator 15 cools the first storage room. Within a preset time t1, the temperature of the first storage room also decreases. However, because the evaporator 12 and the condenser 21 exchange heat, the high-temperature evaporator 15 provides less cooling to the first storage room. Therefore, if, after the preset time t1, T2 has not yet dropped to T... 2关 Or below, and T1 is less than T 1开 Then, the timer for the duration during which the switching valve 17 is in a state of being connected only to the second cooling branch is restarted, and the above steps are repeated; if, after a preset time t1, T2 has not yet dropped to T... 2关 Or below, and the temperature T1 of the first storage compartment has not dropped to its preset shutdown temperature T. 1关 And T1 <T 10 T2 <T 20 Then, the control switching valve 17 is connected to the first cooling branch and the second cooling branch at the same time, and the speed of the high-temperature compressor 11 and the low-temperature compressor 22 is adjusted to accelerate the cooling of the first storage room, so as to avoid the temperature of the first storage room from failing to drop to the preset temperature for a long time, which is not conducive to the preservation of food. At the same time, it also avoids the excessive system pressure caused by the simultaneous operation of the high-temperature compressor 11 and the low-temperature compressor 22.

[0101] Preferably, t1 = 5 to 40 minutes. On the one hand, during this time period, the low-temperature refrigeration cycle loop 2 can have a higher refrigeration efficiency, which can accelerate the cooling of the second storage room. On the other hand, it can prevent the first storage room from not receiving sufficient cooling for a long time, which would cause the temperature inside to remain at a high level for a long time.

[0102] Preferably, T 10 = -30~20℃, thus avoiding excessively high actual temperature in the first storage compartment and avoiding excessive system pressure caused by the simultaneous operation of high-temperature compressor 11 and low-temperature compressor 22.

[0103] Preferably, T 20 = -30~20℃, which can avoid the actual temperature of the second storage room being too high, and avoid the system pressure being too high due to the simultaneous operation of the high-temperature compressor 11 and the low-temperature compressor 22.

[0104] Furthermore, the control method also includes,

[0105] If T1 and T2 do not meet the first preset conditions, the low-temperature stage compressor 22 is controlled to stop, and the switching valve 17 is controlled to switch to only connect with the first cooling branch, so as to accelerate the cooling efficiency of the high-temperature stage evaporator 15 to the first storage room.

[0106] Furthermore, the control method also includes,

[0107] If the switching valve 17 is only connected to the second cooling branch, and both the high-temperature compressor 11 and the low-temperature compressor 22 are running, then the duration of the switching valve 17 being in the state of only being connected to the second cooling branch is timed. Within a preset time t1, if T2 drops to T... 2关 If so, control the low-temperature stage compressor 22 to stop, and determine whether T1 meets the second preset condition;

[0108] If so, control the switching valve 17 to switch to only connect to the first cooling branch;

[0109] If not, then control the high-temperature stage compressor 11 to stop;

[0110] The second preset condition is: at this moment T1 ≥ the preset start-up temperature T of the first storage room. 1开 Alternatively, the preset shutdown temperature T of the first storage compartment. 1关 <T1<T 1开 And before that moment, T1 is always greater than T. 1关 .

[0111] In other words, if the temperature of the second storage room drops to its preset shutdown temperature within a preset time t1, the low-temperature compressor 22 can be shut down to save energy and reduce system operating pressure. At this time, the temperature of the first storage room is judged. If it meets the second preset condition, it indicates that the first storage room still needs to be cooled. At this time, the switching valve 17 can be switched to only connect to the first cooling branch to cool the first storage room. If the temperature of the first storage room does not meet the second preset condition, it indicates that the first storage room does not need to be cooled. At this time, the high-temperature compressor 11 can be shut down to save energy and reduce system operating pressure.

[0112] Compared with the prior art, the cascade compression refrigeration system 100, the refrigeration device therein, and the control method of the refrigeration device provided by the present invention have the following advantages: When the first refrigerant flows in the first cooling branch, the high-temperature evaporator 15 provides cooling for the first storage room; when the first refrigerant flows in the second cooling branch, the first refrigerant flows out from the second throttling device 162 to the evaporation section 12 in the high-temperature refrigeration cycle 1. Through heat exchange between the second refrigerant flowing through the condensation section 21 and the first refrigerant flowing through the evaporation section 12, the first refrigerant in the evaporation section 12 can absorb the heat of the second refrigerant flowing through the condensation section 21, thereby further reducing the temperature of the second refrigerant in the condensation section 21, pre-cooling the low-temperature refrigeration cycle 2, thereby enabling the low-temperature refrigeration cycle 2 to achieve a lower temperature. In addition, the first refrigerant flowing out of the evaporation section 12 flows into the high-temperature evaporator 15, which can also... The system provides cooling to the first storage compartment. Simultaneously, the first refrigerant flowing through the first throttling device 161 and the second throttling device 162 exchange heat with the first refrigerant flowing through the high-temperature stage return pipe 13. This allows the first refrigerant in the high-temperature stage return pipe 13 to cool the first refrigerant in the first throttling device 161 and the second throttling device 162, increasing the cooling capacity. It also raises the suction temperature of the high-temperature stage compressor 11 to approximately the ambient temperature, improving the cooling efficiency of the high-temperature stage compressor 11 and the working efficiency of the high-temperature stage refrigeration cycle loop 1. Furthermore, the operating frequency of the high-temperature stage compressor 11 and the low-temperature stage compressor 22 can be adjusted according to the different temperatures of the storage compartments, so that the high-temperature stage refrigeration cycle loop 1 and the low-temperature stage refrigeration cycle loop 2 generate the cooling capacity required by their respective storage compartments, preventing excessive operating pressure in the refrigeration system.

[0113] It should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0114] The detailed descriptions listed above are merely specific descriptions of feasible embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. All equivalent embodiments or modifications made without departing from the spirit of the present invention should be included within the scope of protection of the present invention.

Claims

1. A refrigeration device, comprising a cascade compression refrigeration system and a housing, characterized in that, The cascade compression refrigeration system includes: A high-temperature refrigeration cycle includes a high-temperature compressor, a switching valve, parallel branches, a high-temperature evaporator, and a high-temperature return pipe connected in series. A first refrigerant flows through the high-temperature refrigeration cycle. The parallel branches include a first cooling supply branch and a second cooling supply branch connected in parallel. The first cooling supply branch includes a first throttling device, and the second cooling supply branch includes a second throttling device and an evaporator connected in series. The switching valve is selectively connected to at least one of the first cooling supply branch and the second cooling supply branch. The first refrigerant flowing through the first throttling device and the first refrigerant flowing through the second throttling device exchange heat with the first refrigerant flowing through the high-temperature return pipe. A low-temperature stage refrigeration cycle circuit includes a low-temperature stage compressor and a condenser section. A second refrigerant flows through the low-temperature stage refrigeration cycle circuit, and the second refrigerant flowing through the condenser section exchanges heat with the first refrigerant flowing through the evaporator section. Both the high-temperature stage compressor and the low-temperature stage compressor are variable frequency compressors; The enclosure has a first storage compartment and a second storage compartment. The high-temperature refrigeration cycle circuit supplies cooling to the first storage compartment, and the low-temperature refrigeration cycle circuit supplies cooling to the second storage compartment. The refrigeration device further includes a controller, which is connected to the switching valve and is used for, If the switching valve only communicates with the second cooling branch, and both the high-temperature stage compressor and the low-temperature stage compressor are in the running state, the duration of the state of the switching valve only communicating with the second cooling branch is timed, and after a preset time t1, if the temperature T2 in the second storage chamber has not decreased to its preset shutdown temperature T 2关 or the following, it is determined whether the temperature T1 in the first storage chamber is less than its preset start temperature T 1开 ; If so, the duration of the switching valve being in a state of being connected only to the second cooling branch is re-timed; If not, then determine whether T1 and T2 meet the first preset condition, which is: T1 < the preset temperature T of the first storage room. 10 And T2 < the preset temperature T of the first storage room 20 ; If T1 and T2 meet the first preset condition, the switching valve is controlled to switch to be connected to both the first cooling branch and the second cooling branch simultaneously, and the speed of the high-temperature stage compressor is increased while the speed of the low-temperature stage compressor is decreased. If T1 and T2 do not meet the first preset conditions, the cryogenic compressor is controlled to stop, and the switching valve is controlled to switch to only connect with the first cooling branch.

2. The refrigeration device according to claim 1, characterized in that, It also includes a controller, which is connected to the switching valve and is used for, When the switching valve is only connected to the second cooling branch, and both the high-temperature compressor and the low-temperature compressor are running, determine whether the temperature T1 inside the first storage room is greater than its preset start-up temperature T. 1开 ; If so, then the speed of the high-temperature stage compressor is increased, or the speed of the low-temperature stage compressor is decreased, or the speed of the high-temperature stage compressor is increased and the speed of the low-temperature stage compressor is decreased. If not, then control the speed of the high-temperature stage compressor to decrease, or control the speed of the low-temperature stage compressor to increase, or control the speed of the high-temperature stage compressor to decrease and control the speed of the low-temperature stage compressor to increase.

3. The refrigeration device according to claim 1, characterized in that, The controller is also used for, If the switching valve is only connected to the second cooling branch, and both the high-temperature compressor and the low-temperature compressor are running, then the duration of the switching valve being in the state of only being connected to the second cooling branch is timed. Within a preset time t1, if the temperature T2 in the second storage room drops to its preset shutdown temperature T... 2关 If so, the low-temperature stage compressor is stopped, and it is determined whether the temperature T1 inside the first storage room meets the second preset condition; If so, control the switching valve to switch to only connect to the first cooling branch; If not, then control the high-temperature stage compressor to shut down; The second preset condition is: at this moment T1 ≥ the preset start-up temperature T of the first storage room. 1开 Alternatively, the preset shutdown temperature T of the first storage compartment. 1关 <T1<T 1开 And before that moment, T1 is always greater than T. 1关 .

4. A control method for a refrigeration device as described in claim 1, characterized in that, The control method includes, When the switching valve is only connected to the second cooling branch, and both the high-temperature compressor and the low-temperature compressor are running, determine whether the temperature T1 inside the first storage room is greater than its preset start-up temperature T. 1开 ; If so, then the speed of the high-temperature stage compressor is increased, or the speed of the low-temperature stage compressor is decreased, or the speed of the high-temperature stage compressor is increased and the speed of the low-temperature stage compressor is decreased. If not, then the speed of the high-temperature stage compressor is reduced and the speed of the low-temperature stage compressor is increased.

5. The control method for the refrigeration device according to claim 4, characterized in that, The control method also includes, If the switching valve is only connected to the second cooling branch, and both the high-temperature compressor and the low-temperature compressor are running, then the duration of the switching valve being in the state of only being connected to the second cooling branch is timed. After a preset time t1, if the temperature T2 in the second storage room has not dropped to its preset shutdown temperature T, then... 2关 If the temperature T1 inside the first storage room is lower than its preset start-up temperature T, then determine whether the temperature T1 inside the first storage room is lower than its preset start-up temperature T. 1开 ; If so, the duration of the switching valve being in a state of being connected only to the second cooling branch is re-timed; If not, then determine whether T1 and T2 meet the first preset condition, which is: T1 < the preset temperature T of the first storage room. 10 And T2 < the preset temperature T of the first storage room 20 ; If T1 and T2 meet the first preset condition, then the switching valve is controlled to switch to be connected to both the first cooling branch and the second cooling branch simultaneously, and the speed of the high-temperature stage compressor is controlled to increase, or the speed of the low-temperature stage compressor is controlled to decrease, or the speed of the high-temperature stage compressor is controlled to increase and the speed of the low-temperature stage compressor is controlled to decrease.

6. The control method for the refrigeration device according to claim 5, characterized in that, The control method also includes, If T1 and T2 do not meet the first preset conditions, the cryogenic compressor is controlled to stop, and the switching valve is controlled to switch to only connect with the first cooling branch.

7. The control method for the refrigeration device according to claim 5, characterized in that, The control method also includes, If the switching valve is only connected to the second cooling branch, and both the high-temperature compressor and the low-temperature compressor are running, then the duration of the switching valve being in the state of only being connected to the second cooling branch is timed. Within a preset time t1, if the temperature T2 in the second storage room drops to its preset shutdown temperature T... 2关 If so, the low-temperature stage compressor is stopped, and it is determined whether the temperature T1 inside the first storage room meets the second preset condition; If so, control the switching valve to switch to only connect to the first cooling branch; If not, then control the high-temperature stage compressor to shut down; The second preset condition is: at this moment T1 ≥ the preset start-up temperature T of the first storage room. 1开 Alternatively, the preset shutdown temperature T of the first storage compartment. 1关 <T1<T 1开 And before that moment, T1 is always greater than T. 1关 .

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