CN218096665U - Cascade compression refrigeration system and refrigeration device with same - Google Patents

Abstract

The utility model provides a cascade compression refrigerating system and have its refrigerating plant, refrigerating system includes high-temperature level and low-temperature level refrigeration cycle return circuit, high-temperature level refrigeration cycle return circuit includes high-temperature level compressor, parallelly connected branch road, connect the high-temperature level muffler of the two and locate the diverter valve of parallelly connected branch road entrance, parallelly connected branch road is including parallelly connected first cooling branch road and the second cooling branch road that sets up, first cooling branch road is including the first throttling arrangement and the high-temperature level evaporimeter of establishing ties, the second cooling branch road is including the second throttling arrangement and the evaporation department of establishing ties, parallelly connected branch road still includes the third throttling arrangement that connects in parallel with the second throttling arrangement, it is first to flow through, the first refrigerant in the second throttling arrangement exchanges heat with the first refrigerant that flows through in the high-temperature level muffler respectively; the second refrigerant flowing through the condensing part of the low-temperature stage refrigeration cycle loop exchanges heat with the first refrigerant flowing through the evaporating part, so that the problems of low refrigeration efficiency and high starting pressure when the low-temperature stage compressor is started are solved.

Description

Cascade compression refrigeration system and refrigeration device with same

Technical Field

The utility model relates to a refrigeration plant technical field especially relates to a refrigerating system and have its refrigerating plant.

Background

Along with the improvement of economic level and technical level and the convenience of transportation, the variety of food materials and food is more and more diversified, in order to carry out suitable storage to different kinds of food materials and food to play best storage and fresh-keeping effect, refrigerating plant that has different warm areas is produced in the meantime.

However, the existing refrigeration device usually adopts a cascade compression refrigeration system to respectively refrigerate different storage compartments, so that temperature areas of the storage compartments of the refrigeration device have differences, and classified storage of different kinds of food materials and food is realized. However, the conventional refrigeration device has problems that the refrigeration efficiency of the refrigeration system is low and the starting pressure is large when the low-temperature stage compressor is started.

Disclosure of Invention

In order to solve the technical problem, an object of the present invention is to provide a refrigerating apparatus with a cascade compression refrigerating system, which solves the problems of low refrigerating efficiency of the refrigerating system and large starting pressure when the low-temperature stage compressor is started in the existing refrigerating apparatus.

In order to achieve one of the above objects, one embodiment of the present invention provides a cascade type compression refrigeration system, which comprises,

the high-temperature stage refrigeration cycle loop comprises a high-temperature stage compressor, a parallel branch and a high-temperature stage air return pipe for connecting the high-temperature stage compressor and the parallel branch, wherein a first refrigerant flows through the high-temperature stage refrigeration cycle loop, the parallel branch comprises a first cooling branch and a second cooling branch which are arranged in parallel, the first cooling branch comprises a first throttling device and a high-temperature stage evaporator which are arranged in series, the second cooling branch comprises a second throttling device and an evaporation part which are arranged in series, the parallel branch further comprises a third throttling device which is arranged in parallel with the second throttling device, 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 air return pipe respectively, the high-temperature stage refrigeration cycle loop further comprises a switching valve arranged at an inlet of the parallel branch, and the switching valve is selectively communicated with at least one of the first cooling branch, the second throttling device and the third throttling device;

and the low-temperature stage refrigeration cycle loop comprises a low-temperature stage compressor and a condensing part, wherein a second refrigerant flows in the low-temperature stage refrigeration cycle loop, and the second refrigerant flowing through the condensing part exchanges heat with the first refrigerant flowing through the evaporating part.

As a further improvement of an embodiment of the present invention, the low-temperature stage refrigeration cycle circuit further includes a low-temperature stage throttling device, a low-temperature stage evaporator and a first air return pipe section, which are arranged in series, and the condensation portion is located between the low-temperature stage compressor and the low-temperature stage throttling device.

As a further improvement of an embodiment of the present invention, the second refrigerant flowing through the first return-air pipe section exchanges heat with the second refrigerant flowing through the low-temperature stage throttling device.

As a further improvement of an embodiment of the present invention, the low-temperature stage refrigeration cycle loop further includes a second air return pipe section and a heat release pipe section, the second air return pipe section is located the low-temperature stage evaporator with between the low-temperature stage compressor, the heat release pipe section is located the low-temperature stage compressor with between the condensation portion, flow through the second refrigerant in the second air return pipe section and flow through the second refrigerant heat exchange in the heat release pipe section.

As a further improvement of an embodiment of the present invention, the second return air pipe section is located between the first return air pipe section and the low-temperature stage compressor.

As a further improvement of an embodiment of the present invention, the second return air pipe section and the heat release pipe section are sleeved or attached to each other.

As a further improvement of an embodiment of the present invention, the low-temperature throttling device is a capillary tube, and the first return air pipe section is sleeved with or attached to the low-temperature throttling device.

As a further improvement of an embodiment of the present invention, the first throttling device and the second throttling device are respectively sleeved or attached to the high-temperature-level muffler.

In order to realize one of the above-mentioned utility model purpose, the utility model discloses an embodiment still provides a refrigerating plant, including the box, still include as above overlapping formula compression refrigerating system, first storing compartment and second storing compartment have in the box, high temperature level refrigeration cycle return circuit does room cooling between first storing, low temperature level refrigeration cycle return circuit does room cooling between the second storing.

As a further improvement of an embodiment of the present invention, the refrigeration apparatus further includes a controller, the controller is connected to the switching valve, and is configured to: according to the temperature of the first storage chamber and the second storage chamberControlAnd controlling the communication state of the switching valve, the first cooling branch, the second cooling branch and the third throttling device.

Compared with the prior art, the utility model discloses following beneficial effect has: the utility model discloses a cascade compression refrigerating system and have its refrigerating plant, diverter valve 17 can control the flow direction of first refrigerant selectively as required to realize different functions and refrigeration effect; when the first refrigerant circulates in the first cooling branch, the high-temperature-stage evaporator supplies cooling for the first storage compartment; when the first refrigerant circulates in the second cold supply branch, the first refrigerant flows out of the second throttling device to the evaporation part in the high-temperature-stage refrigeration cycle loop, and the first refrigerant in the evaporation part can absorb the heat of the second refrigerant flowing through the condensation part through the heat exchange between the second refrigerant flowing through the condensation part and the first refrigerant flowing through the evaporation part, so that the temperature of the second refrigerant in the condensation part can be further reduced, and the second refrigerant is precooled for the low-temperature-stage refrigeration cycle loop, and the low-temperature-stage refrigeration cycle loop can realize lower temperature; meanwhile, 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 gas return pipe respectively, so that the first refrigerant in the high-temperature-stage gas return pipe can be utilized to cool the first refrigerant in the first throttling device and the first refrigerant in the second throttling device, the refrigerating capacity is increased, the suction temperature of the high-temperature-stage compressor is increased to about the ambient temperature, the refrigerating efficiency of the high-temperature-stage compressor is improved, and the working efficiency of the high-temperature-stage refrigerating circulation loop is improved; when the low-temperature stage compressor is started, the first refrigerant can circulate in the third throttling device, so that the problem of high starting pressure at the moment of starting the low-temperature stage compressor can be solved.

Drawings

Fig. 1 is a schematic structural diagram of a cascade compression refrigeration system according to an embodiment of the present invention.

Detailed Description

The present invention will be described in detail below with reference to specific embodiments shown in the drawings.

In the various figures of the present invention, certain dimensions of structures or portions are exaggerated relative to other structures or portions for ease of illustration, and thus, are used only to illustrate the basic structure of the subject matter of the present invention.

It will be understood that, although the terms first, second, etc. may be used herein to describe various elements or structures, these described elements should not be limited by these terms. These terms are only used to distinguish these descriptive objects from one another.

An embodiment of the utility model provides a refrigerating plant, including the box and the door body, have the storing room in the box, the door body is used for opening or closes the storing room, and refrigerating plant still includes refrigerating system, and refrigerating system locates in the box and to the storing room cooling. Specifically, the refrigerating device can be set as a refrigerator, a freezer, or the like, so as to meet the requirements of different users and different application scenarios.

In this embodiment, the box body has a first storage chamber and a second storage chamber, the first storage chamber may be a refrigerating chamber or a freezing chamber, and the second storage chamber may be a temperature-changing chamber or a deep-cooling chamber. The refrigerating system adopts a cascade compression refrigerating system 100, and specifically comprises a high-temperature-level refrigerating circulation loop 1 and a low-temperature-level refrigerating circulation loop 2.

For convenience of description, in the present embodiment, the high-temperature-stage refrigeration cycle 1 supplies cold to the first storage compartment, and the low-temperature-stage refrigeration cycle 2 supplies cold to the second storage compartment. Of course, the two may be interchanged.

Of course, in other embodiments, other storage compartments besides the first storage compartment and the second storage compartment may be provided according to actual needs.

Referring to fig. 1, the high-temperature stage refrigeration cycle circuit 1 includes a high-temperature stage compressor 11, a parallel branch and a high-temperature stage return pipe 13 connecting the high-temperature stage compressor and the high-temperature stage return pipe, a first refrigerant flows through the high-temperature stage refrigeration cycle circuit 1, the parallel branch includes a first cooling branch and a second cooling branch which are arranged in parallel, the first cooling branch includes a first throttling device 161 and a high-temperature stage evaporator 15 which are arranged in series, the second cooling branch includes a second throttling device 162 and an evaporation part 12 which are arranged in series, the parallel branch further includes a third throttling device 163 which is arranged in series with the second throttling device 162, and 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 respectively.

The high temperature stage refrigeration cycle 1 further includes a switching valve 17 disposed at an inlet of the parallel branch, and the switching valve 17 is selectively communicated with at least one of the first cooling branch, the second throttling device 162 and the third throttling device 163, so as to selectively control a flow direction of the first refrigerant as required, thereby implementing different functions and refrigeration effects. Therefore, the temperature range of-30-10 ℃ can be realized in the first storage chamber, and the temperature can be adjusted in the temperature range.

The low-temperature-stage refrigeration cycle circuit 2 includes a condensation unit 21, and a second refrigerant flows through the low-temperature-stage refrigeration cycle circuit 2, and the second refrigerant flowing through the condensation unit 21 exchanges heat with the first refrigerant flowing through the evaporation unit 12.

Thus, when the first refrigerant circulates in the first cooling branch, the high-temperature-stage evaporator 15 supplies cooling to the first storage compartment; when the first refrigerant circulates in the second cooling branch, the first refrigerant flows out of the second cooling branch to the evaporation part 12 in the high-temperature-stage refrigeration cycle loop 1, and through heat exchange between the second refrigerant flowing through the condensation part 21 and the first refrigerant flowing through the evaporation part 12, the first refrigerant in the evaporation part 12 can absorb heat of the second refrigerant flowing through the condensation part 21, so that the temperature of the second refrigerant in the condensation part 21 can be further reduced, and the second refrigerant is precooled for the low-temperature-stage refrigeration cycle loop 2, so that the low-temperature-stage refrigeration cycle loop 2 can realize lower temperature; meanwhile, as 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 for cooling the first refrigerant in the first throttling device 161 and the second throttling device 162, so as to increase the cooling capacity, and simultaneously improve the suction temperature of the high-temperature stage compressor 11, so that the suction temperature is raised to about the ambient temperature, so as to improve the cooling efficiency of the high-temperature stage compressor 11 and the working efficiency of the high-temperature stage refrigeration cycle loop 1; when the low-temperature stage compressor 22 is started, the first refrigerant can be circulated in the third throttling device 163, so that the problem of large starting pressure at the starting moment of the low-temperature stage compressor 22 can be solved, and as a result, the temperature of the first refrigerant in the evaporation part 12 is too high or even reaches dozens of degrees due to the large heat dissipation capacity of the condensation part 21 at the starting moment of the low-temperature stage compressor 22, when the first refrigerant flows into the high-temperature stage return pipe 13 to exchange heat with the second throttling device 162, the temperature of the first refrigerant in the second throttling device 162 is increased to reduce the flow rate of the first refrigerant, so that the evaporation part 12 cannot provide enough cold for the condensation part 21, and further the starting pressure of the low-temperature stage compressor 22 is large.

Preferably, the first throttling means 161, the second throttling means 162 and the third throttling means 163 are capillary tubes.

The first throttling device 161 and the second throttling device 162 are respectively in thermal connection with the high-temperature-stage return air pipe 13 in a manner of being sleeved or attached to each other, so that the improvement of the heat exchange efficiency of the first refrigerant circulating in the first throttling device and the second throttling device is facilitated, and the energy utilization rate is improved.

Further, the high-temperature-stage refrigeration cycle loop 1 further includes a high-temperature-stage drying filter 18 disposed between the high-temperature-stage condenser 14 and the parallel branch, and a liquid storage bag 19 disposed between the parallel branch and the high-temperature-stage return air pipe 13.

The low-temperature stage refrigeration cycle loop 2 further comprises a low-temperature stage compressor 22, a low-temperature stage throttling device 23, a low-temperature stage evaporator 24 and a first air return pipe section 25 which are arranged in series, and the condensing part 21 is arranged between the low-temperature stage compressor 22 and the low-temperature stage throttling device 23.

Further, the second refrigerant flowing through the first air return pipe section 25 exchanges heat with the second refrigerant flowing through the low-temperature-stage throttling device 23, so that the second refrigerant flowing through the first air return pipe section 25 absorbs heat of the second refrigerant flowing through the low-temperature-stage throttling device 23, the temperature of the second refrigerant flowing through the suction inlet of the low-temperature-stage compressor 22 is increased, the suction temperature of the low-temperature-stage compressor 22 is increased, the energy utilization rate of the low-temperature-stage refrigeration cycle loop 2 is increased, and the energy efficiency of the whole refrigeration device is improved.

Preferably, the low-temperature-stage throttling device 23 is a capillary tube, and the first return air pipe section 25 and the low-temperature-stage throttling device 23 are sleeved or attached to each other, so that heat exchange of a second refrigerant circulating in the first return air pipe section and the second return air pipe section is facilitated, and the energy utilization rate is improved.

Further, the low-temperature-stage refrigeration cycle circuit 2 further includes a second air return pipe section 26 and a heat release pipe section 27, the second air return pipe section 26 is disposed between the low-temperature-stage evaporator 24 and the low-temperature-stage compressor 22, the heat release pipe section 27 is disposed between the low-temperature-stage compressor 22 and the condensation portion 21, and the second refrigerant flowing through the second air return pipe section 26 exchanges heat with the second refrigerant flowing through the heat release pipe section 27, so that the second refrigerant flowing through the second air return pipe section 26 can absorb heat of the second refrigerant flowing through the heat release pipe section 27, the suction temperature of the low-temperature-stage compressor 22 is increased, the cold quantity of the second refrigerant flowing from the heat release pipe section 27 to the condensation portion 21 is reduced, the low-temperature-stage refrigeration cycle circuit 2 can achieve a lower temperature, the temperature of the second storage chamber can be adjusted within a temperature range of-60 ℃ to-20 ℃, the energy utilization rate of the low-temperature-stage refrigeration cycle circuit 2 is increased, and the energy efficiency of the whole refrigeration device is improved.

Preferably, the second gas return pipe section 26 is located between the first gas return pipe section 25 and the low temperature stage compressor 22, so that the energy utilization rate of the low temperature stage refrigeration cycle circuit 2 can be maximally improved.

The second air return pipe section 26 and the heat release pipe section 27 are sleeved or attached to each other, so that heat exchange of the second refrigerant circulating in the second air return pipe section and the heat release pipe section is facilitated, and the energy utilization rate is improved.

Further, the low-temperature-stage refrigeration cycle circuit 2 further includes a low-temperature-stage radiating pipe 28 provided between the low-temperature-stage compressor 22 and the heat releasing pipe section 27, and a low-temperature-stage dry filter 29 provided between the condensing portion 21 and the low-temperature-stage throttling device 23. The second refrigerant flowing out of the low-temperature-stage compressor 22 can be radiated by the low-temperature-stage radiating pipe 28, so that the low-temperature-stage refrigeration cycle circuit 2 can achieve a lower temperature; the second refrigerant flowing out of the condensing portion 21 may be dried and filtered by the low-temperature stage filter-drier 29.

The first refrigerant and the second refrigerant may be the same refrigerant or different refrigerants.

In addition, "high temperature" and "low temperature" in the "high temperature stage refrigeration cycle circuit 1" and the "low temperature stage refrigeration cycle circuit 2" are relative terms, and the evaporation temperature of the first refrigerant flowing through the high temperature stage refrigeration cycle circuit 1 is relatively higher than the evaporation temperature of the second refrigerant flowing through the low temperature stage refrigeration cycle circuit 2.

Further, the refrigeration apparatus further includes a controller connected to the switching valve 17 and configured to control a communication state between the switching valve 17 and the first cooling branch, the second throttling device 162, and the third throttling device 163 according to the temperatures of the first storage compartment and the second storage compartment.

In particular, the controller is configured to,

if the switching valve 17 is only communicated with the second throttling device 162 and the high-temperature stage compressor 11 and the low-temperature stage compressor 22 are both in the running state, the duration of the switching valve 17 in the state of being only communicated with the second throttling device 162 is measured, and after a preset time T1, if the temperature T in the second storage compartment is up to T1 ₂ Has not yet fallen to the preset shutdown temperature T _{2 off} Or below, judging the temperature T in the first storage room ₁ Whether it is less than the preset starting temperature T _{1 on} ；

If so, timing the duration that the switching valve 17 is in the state of being only communicated with the second throttling device 162 again, so that the temperature of the second storage compartment can be reduced to the preset temperature as soon as possible;

if not, judging T ₁ And T ₂ Whether a first preset condition is met or not, wherein the first preset condition is as follows: t is ₁ <The preset temperature T of the first storage chamber ₁₀ And T is ₂ <The preset temperature T of the first storage chamber ₂₀ ；

If T ₁ And T ₂ If the first preset condition is satisfied, the switching valve 17 is controlled to be switched to be simultaneously communicated with the first cooling branch and the second throttling device 162.

Therefore, the first storage chamber can be prevented from being kept at a high temperature all the time due to the fact that the first storage chamber cannot be supplied with cold for a long time; while avoiding excessive system pressure caused by the simultaneous operation of the high temperature stage compressor 11 and the low temperature stage compressor 22.

Preferably, t1= 5-40 min, not only can provide enough cold for the second storage chamber to effectively reduce the temperature thereof, but also can prevent the first storage chamber from being unable to supply cold for a long time.

Preferably, T ₁₀ And the temperature is-30-20 ℃, so that the actual temperature of the first storage chamber can be prevented from being too high, and the system pressure caused by the simultaneous operation of the high-temperature-stage compressor 11 and the low-temperature-stage compressor 22 can be prevented from being too high.

Preferably, T ₂₀ And the temperature is-30-20 ℃, so that the actual temperature of the second storage chamber can be prevented from being too high, and the system pressure caused by the simultaneous operation of the high-temperature-stage compressor 11 and the low-temperature-stage compressor 22 can be prevented from being too high.

Further, the controller is also configured to,

if T is ₁ And T ₂ If the first preset condition is not met, the low-temperature stage compressor 22 is controlled to stop, and the switching valve 17 is controlled to be switched to be communicated with the first cooling branch circuit only, so that the flow of the refrigerant in the first cooling branch circuit can be increased, and the speed of the refrigerant in the first cooling branch circuit is increasedThe refrigeration efficiency of first storing compartment.

Further, the controller is also configured to,

if the switching valve 17 is in communication with only the second throttling device 162 and both the high-temperature stage compressor 11 and the low-temperature stage compressor 22 are in the operating state, the duration of the switching valve 17 in communication with only the second throttling device 162 is measured, and if T is T1 within the preset time T1 ₂ Down to T _{2 off} Then the low-temperature stage compressor 22 is controlled to stop and T is judged ₁ Whether a second preset condition is met or not;

if T is ₁ If the second preset condition is met, the switching valve 17 is controlled to be switched to be communicated with the first cooling branch only;

if T ₁ If the second preset condition is not met, the high-temperature stage compressor 11 is controlled to stop;

wherein the second preset condition is: at this time T ₁ Not less than the preset starting temperature T of the first storage chamber _{1 on} Or the preset shutdown temperature T of the first storage chamber _{1 off} <T ₁ <T _{1 on} And T before the moment ₁ Is always greater than T _{1 off} 。

That is, within a preset time t1, if the temperature of the second storage compartment is reduced to the preset shutdown temperature, the low-temperature stage compressor 22 may be stopped, at this time, the temperature condition of the first storage compartment is determined, if the second preset condition is met, it is indicated that the first storage compartment still needs cooling, at this time, the switching valve 17 may be switched to be only communicated with the first cooling branch, so as to supply cooling to the first storage compartment; if the temperature of the first storage chamber does not meet the second preset condition, it is indicated that the first storage chamber does not need to be cooled, and at the moment, the high-temperature stage compressor 11 can be controlled to stop, so that energy consumption is saved.

Further, the controller is also configured to,

if the switching valve 17 is in communication with only the first cooling branch and the high-temperature stage compressor 11 is in an operating state, the switching valve 17 is kept in communication with only the first cooling branchTiming the duration, within a preset time T2, if T ₁ Down to T _{1 off} Then, determine T ₂ Whether a third preset condition is met or not, wherein the third preset condition is as follows: at this time T ₂ More than or equal to the preset starting temperature T of the second storage chamber _2-opening Or at the moment, the preset shutdown temperature T of the second storage chamber _{2 off} <T ₂ <T _2-opening And T before the moment ₂ Is always greater than T _{2 off} ；

If T ₂ If the third preset condition is met, T is judged ₂ Whether or not less than T ₂₀ ；

If T is ₂ ≥T ₂₀ Then the switching valve 17 is controlled to switch to communication with only the third throttling means 163;

after a preset time t3, controlling the low-temperature stage compressor 22 to start;

after the preset time t4, the control switch valve 17 is switched to be communicated with only the second throttling device 162.

Like this, at refrigerating plant operation in-process, begin to give from high temperature level refrigeration cycle return circuit 1 room refrigeration begins in the time of predetermineeing t2 between the first storing, if indoor temperature drops to its when predetermineeing shutdown temperature and need not refrigerate between the first storing, then is right the temperature of room is judged between the second storing, in order to avoid the room is not refrigerated for a long time between the second storing and leads to its interior high temperature, is unfavorable for storing the fresh-keeping of article wherein. If the temperature of the second storage chamber meets the third preset condition within the preset time T2, namely the second storage chamber needs to be refrigerated, and the temperature of the second storage chamber is higher than the preset temperature T ₂₀ During the process, the switching valve 17 is controlled to be communicated with the third throttling device 163 only, and the high-temperature stage compressor 11 is controlled to be started, so that the problem of large starting pressure at the moment of starting the low-temperature stage compressor 22 can be solved, and because the first refrigerant in the third throttling device 163 does not exchange heat with the first refrigerant in the high-temperature stage return air pipe 13, the reduction of the flow rate of the first refrigerant in the third throttling device 163 is avoided, the evaporation part 12 is ensured to provide sufficient cold for the condensation part 21, and the overlarge pressure at the moment of starting the low-temperature stage compressor 22 is avoided. Further, the method can be used for preparing a novel materialAfter a preset time t3, the evaporation part 12 provides enough cooling capacity for the condensation part 21, at this time, the low-temperature stage compressor 22 is started, and the low-temperature stage refrigeration cycle loop 2 supplies cooling capacity for the second storage compartment. After a preset time t4, the low-temperature stage compressor 22 operates stably, at this time, the switching valve 17 is controlled to be switched to be only communicated with the second throttling device 162, the first refrigerant flowing through the second throttling device 162 exchanges heat with the first refrigerant flowing through the high-temperature stage return pipe 13, so that the first refrigerant in the high-temperature stage return pipe 13 can be used for cooling the first refrigerant in the second throttling device 162, the cooling capacity is increased, the suction temperature of the high-temperature stage compressor 11 is increased to about the ambient temperature, the cooling efficiency of the high-temperature stage compressor 11 is improved, the cooling capacity of the evaporation part 12 to the condensation part 21 is further improved, the cooling efficiency of the low-temperature stage refrigeration cycle loop 2 is improved, and the energy utilization rate of the cooling device is improved.

Preferably, t2= 5-20 min, not only can the high-temperature refrigeration cycle loop 1 provide enough cold energy for the first storage chamber, but also the second storage chamber is prevented from being unable to supply cold for a long time.

Preferably, t3 is 5min or less to ensure that the evaporator 12 provides enough cold to the condenser 21 to avoid excessive start-up pressure at the low temperature stage compressor 22.

Preferably, t4= 0.5-10 min, and by this time, the pressure of the low-temperature-stage compressor 22 tends to be stable, and the improvement of the refrigeration efficiency of the low-temperature-stage refrigeration cycle loop 2 is facilitated, so that the temperature in the first storage compartment reaches the preset temperature as soon as possible, and the starting efficiency is improved.

Further, the controller is also configured to,

if T ₂ ≤T ₂₀ Then the control switch valve 17 is switched to communicate with only the second throttling device 162;

and after the preset time t2, controlling the low-temperature stage compressor 22 to start.

When the second storage chamber needs to refrigerate and the temperature T of the second storage chamber is in the running state of the refrigerating device ₂ Not higher than a preset temperature T ₂₀ At this time, the second throttling device can be directly connected162, the evaporation part 12 supplies cold to the condensation part 21, so that the first refrigerant flowing through the second throttling device 162 exchanges heat with the first refrigerant flowing through the high-temperature-stage air return pipe 13, thereby increasing the cold supply quantity of the evaporation part 12 to the condensation part 21, accelerating the precooling efficiency and further increasing the refrigeration efficiency of the second storage compartment.

Further, the controller is also configured to,

within a preset time T2, if T ₁ Down to T _{1 off} And T is ₂ And if the second preset condition is not met, the high-temperature stage compressor 11 is controlled to stop.

That is, within the preset time T2, if the temperature of the first storage chamber is reduced to the preset shutdown temperature T _{1 off} And the temperature of the second storage chamber also reaches the preset shutdown temperature T _{2 off} Or the shutdown condition of the second storage compartment is met, the high-temperature stage compressor 11 can be stopped, so that energy consumption is saved.

Further, the controller is also configured to,

if the switching valve 17 is only communicated with the first cooling branch and the high-temperature stage compressor 11 is in the running state, timing the duration of the switching valve 17 in the state of being only communicated with the first cooling branch, and after a preset time T2, determining if the temperature T in the first storage compartment is high ₁ Has not yet fallen to the preset shutdown temperature T _{1 guan} Or below, judging the temperature T in the second storage room ₂ Whether a fourth preset condition is met or not, wherein the fourth preset condition is as follows: at the moment T ₂ ≥T _2-opening Or, alternatively, T _{2 off} <T ₂ <T _2-opening And T2 is within T ₂ Is always greater than T _{2 off} ；

If yes, judging T ₂ Whether it is higher than the preset temperature T ₂₀ ；

If so, the switching valve 17 is controlled to switch to only communicate with the third throttling means 163;

after a preset time t3, controlling the low-temperature stage compressor 22 to start;

after the preset time t4, the control switch valve 17 is switched to be communicated with only the second throttling device 162.

Therefore, in the operation process of the refrigerating device, the high-temperature refrigeration circulation loop starts to refrigerate the first storage chamber, and after the preset time t1, if the temperature in the first storage chamber is not reduced to the preset shutdown temperature, whether the second storage chamber needs to refrigerate is judged firstly, so that the situation that the temperature in the second storage chamber is too high due to the fact that the second storage chamber cannot refrigerate for a long time and the articles stored in the second storage chamber are not favorable for keeping fresh is avoided. If the preset time T2 is passed, the second storage chamber needs to be refrigerated, and the temperature T of the second storage chamber is ₂ Greater than a predetermined temperature T ₂₀ The switching valve 17 is controlled to be communicated with the third throttling device 163 only, and the high-temperature stage compressor 11 is controlled to be started, so that the problem of large starting pressure at the moment of starting the low-temperature stage compressor 22 can be solved, and because the first refrigerant in the third throttling device 163 does not exchange heat with the first refrigerant in the high-temperature stage air return pipe 13, the reduction of the flow rate of the first refrigerant in the third throttling device 163 is avoided, the evaporation part 12 is ensured to provide enough cold for the condensation part 21, and the overlarge pressure at the moment of starting the low-temperature stage compressor 22 is avoided. Further, after the preset time t3, the evaporation part 12 provides enough cooling capacity for the condensation part 21, at this time, the low-temperature stage compressor 22 is started, and the low-temperature stage refrigeration cycle loop 2 supplies cooling capacity for the second storage compartment. After a preset time t4, the low-temperature stage compressor 22 operates stably, at this time, the switching valve 17 is controlled to be switched to be only communicated with the second throttling device 162, the first refrigerant flowing through the second throttling device 162 exchanges heat with the first refrigerant flowing through the high-temperature stage return pipe 13, so that the first refrigerant in the high-temperature stage return pipe 13 can be used for cooling the first refrigerant in the second throttling device 162, the cooling capacity is increased, the suction temperature of the high-temperature stage compressor 11 is increased to about the ambient temperature, the cooling efficiency of the high-temperature stage compressor 11 is improved, the cooling capacity of the evaporation part 12 to the condensation part 21 is further improved, the cooling efficiency of the low-temperature stage refrigeration cycle loop 2 is improved, and the energy utilization rate of the cooling device is improved.

Further, the controller is further configured to:

if T ₂ ≤T ₀ Then the control switch valve 17 is switched to communicate with only the second throttling device 162;

and after the preset time t3, controlling the low-temperature stage compressor 22 to start.

When the second storage chamber needs to refrigerate and the temperature T of the second storage chamber is in the running state of the refrigerating device ₂ Not higher than a predetermined temperature T ₂₀ When the cooling system is used, the second throttling device 162 can be directly used at the moment, so that the evaporation part 12 supplies cold to the condensation part 21, and therefore, the first refrigerant flowing through the second throttling device 162 exchanges heat with the first refrigerant flowing through the high-temperature-level air return pipe 13, the cold supply amount of the evaporation part 12 to the condensation part 21 can be improved, the precooling efficiency is accelerated, and the refrigerating efficiency of the second storage compartment is improved.

Further, the controller is further configured to:

if T ₂ If the fourth preset condition is not met, the duration of the switching valve 17 in the state of communication with only the first cooling branch is counted again.

That is, after the preset time T2, if the temperature of the first storage chamber has not decreased to the preset shutdown temperature T thereof yet _{1 off} And the temperature of the second storage chamber is reduced to the preset shutdown temperature T _{2 off} Or the shutdown condition of the second storage compartment is met, the high-temperature-stage compressor 11 needs to continue to operate at the moment, and for cooling the first storage compartment, a new round of temperature monitoring and compressor operation state control are performed by timing the duration of the switching valve 17 in the state of being only communicated with the first cooling branch again.

The utility model also provides a control method of the refrigerating device, which comprises the following steps,

if the switching valve 17 is only communicated with the second throttling device 162 and the high-temperature stage compressor 11 and the low-temperature stage compressor 22 are both in the running state, the duration of the switching valve 17 in the state of being only communicated with the second throttling device 162 is measured, and after a preset time T1, if the temperature T in the second storage compartment is up to T1 ₂ Has not yet fallen to the preset shutdown temperature T _{2 off} Or below, judging the temperature in the first storage roomDegree T ₁ Whether it is less than the preset starting temperature T _{1 on} ；

If so, timing the duration that the switching valve 17 is only communicated with the second throttling device 162 again, so that the temperature of the second storage compartment can be reduced to the preset temperature as soon as possible;

if not, judging T ₁ And T ₂ Whether a first preset condition is met or not, wherein the first preset condition is as follows: t is ₁ <The preset temperature T of the first storage chamber ₁₀ And T is ₂ <The preset temperature T of the first storage chamber ₂₀ ；

If T is ₁ And T ₂ If the first preset condition is satisfied, the switching valve 17 is controlled to be switched to be simultaneously communicated with the first cooling branch and the second throttling device 162.

Therefore, the first storage chamber can be prevented from being cooled for a long time, so that the internal temperature of the first storage chamber is always high; while avoiding excessive system pressure caused by the simultaneous operation of the high temperature stage compressor 11 and the low temperature stage compressor 22.

Preferably, t1= 5-40 min, not only enough cold energy can be provided for the second storage chamber to effectively reduce the temperature of the second storage chamber, but also the first storage chamber can be prevented from not being supplied with cold for a long time.

Preferably, T ₀ And the temperature is-30-20 ℃, so that the problem that the system pressure is too high due to the simultaneous operation of the high-temperature stage compressor 11 and the low-temperature stage compressor 22 when the difference between the actual temperature of the first storage chamber and the preset starting temperature is too large can be avoided.

Further, the control method may further include,

if T ₁ And T ₂ If the first preset condition is not met, the low-temperature stage compressor 22 is controlled to stop, and the switching valve 17 is controlled to be switched to be communicated with the first cooling branch only, so that the flow of the refrigerant in the first cooling branch can be increased, and the refrigeration efficiency of the first storage compartment is improved.

Further, the control method may further include,

if the switching valve 17 is in communication with only the second throttling device 162 and both the high-temperature stage compressor 11 and the low-temperature stage compressor 22 are in the operating state, the duration of the switching valve 17 in communication with only the second throttling device 162 is measured, and if T is T1 within the preset time T1 ₂ Down to T _{2 off} Then the low-temperature stage compressor 22 is controlled to stop and T is judged ₁ Whether a second preset condition is met or not;

if T is ₁ If the second preset condition is met, the switching valve 17 is controlled to be switched to be communicated with the first cooling branch only;

if T ₁ If the second preset condition is not met, the high-temperature stage compressor 11 is controlled to stop;

wherein the second preset condition is: at the moment T ₁ ≥T _{1 on} Or, the preset shutdown temperature T of the first storage compartment _{1 off} <T ₁ <T _{1 opener} And before the time T ₁ Is always greater than T _{1 off} 。

That is to say, within a preset time t1, if the temperature of the second storage compartment is reduced to the preset shutdown temperature, the low-temperature stage compressor 22 may be stopped, at this time, the temperature condition of the first storage compartment is determined, and if the second preset condition is met, it is indicated that the first storage compartment still needs to be cooled, at this time, the switching valve 17 may be switched to be only communicated with the first cooling branch, so as to cool the first storage compartment; if the temperature of the first storage chamber does not meet the second preset condition, it is indicated that the first storage chamber does not need to be cooled, and at the moment, the high-temperature stage compressor 11 can be controlled to stop, so that energy consumption is saved.

Further, the control method may further include,

if the switching valve 17 is only communicated with the first cooling branch and the high-temperature stage compressor 11 is in the running state, the duration of the switching valve 17 in the state of being only communicated with the first cooling branch is timed, within a preset time T2, if T is ₁ Down to T _{1 off} Then, determine T ₂ Whether a third preset condition is met or not, wherein the third preset condition is as follows: at the moment T ₂ Not less thanThe preset starting temperature T of the second storage chamber _2-opening Or at this moment, the preset shutdown temperature T of the second storage compartment _{2 guan (a)} <T ₂ <T _2-opening And T before the moment ₂ Is always greater than T _{2 guan (a)} ；

If T ₂ If the third preset condition is met, judging T ₂ Whether or not less than T ₂₀ ；

If T ₂ ≥T ₂₀ Then the switching valve 17 is controlled to switch to only communicate with the third throttling means 163;

after the preset time t3, controlling the low-temperature stage compressor 22 to start;

after the preset time t4, the switching valve 17 is controlled to be switched to be communicated with only the second throttling device 162.

Like this, in refrigerating plant operation in-process, begin to give from high temperature level refrigeration cycle return circuit 1 first storing room refrigeration begins, in preset time t2, if indoor temperature in first storing room falls to its and predetermines shutdown temperature and when not needing the refrigeration, then right the temperature of second storing room is judged, in order to avoid the second storing room can not get the refrigeration for a long time and lead to its interior high temperature, is unfavorable for the fresh-keeping of the article of storing wherein. If the temperature of the second storage chamber meets the third preset condition within the preset time T2, namely the second storage chamber needs to be refrigerated, and the temperature of the second storage chamber is higher than the preset temperature T ₂₀ During the operation, the switching valve 17 is controlled to be communicated with the third throttling device 163 only, and the high-temperature stage compressor 11 is controlled to start, so that the problem of large starting pressure of the low-temperature stage compressor 22 at the moment of starting can be solved, because the first refrigerant in the third throttling device 163 does not exchange heat with the first refrigerant in the high-temperature stage return pipe 13, the reduction of the flow rate of the first refrigerant in the third throttling device 163 is avoided, the evaporation part 12 is ensured to provide sufficient cold for the condensation part 21, and the overlarge pressure of the low-temperature stage compressor 22 at the moment of starting is avoided. Further, after the preset time t3, the evaporation part 12 provides enough cold energy for the condensation part 21, at this time, the low-temperature stage compressor 22 is started, and the low-temperature stage refrigeration cycle loop 2 supplies cold for the second storage compartment. Further, the method can be used for preparing a novel materialAfter the preset time t4, the low-temperature stage compressor 22 operates stably, at this time, the switching valve 17 is controlled to be switched to be only communicated with the second throttling device 162, the first refrigerant flowing through the second throttling device 162 exchanges heat with the first refrigerant flowing through the high-temperature stage return pipe 13, so that the first refrigerant in the high-temperature stage return pipe 13 can be used for cooling the first refrigerant in the second throttling device 162, the cooling capacity is increased, the suction temperature of the high-temperature stage compressor 11 is increased to about the ambient temperature, the refrigeration efficiency of the high-temperature stage compressor 11 is improved, the cooling capacity of the evaporation part 12 to the condensation part 21 is further improved, the refrigeration efficiency of the low-temperature stage refrigeration cycle loop 2 is improved, and the energy utilization rate of the refrigeration device is improved.

Preferably, t2= 5-20 min, not only the high-temperature-stage refrigeration cycle loop 1 can provide enough cold for the first storage compartment, but also the second storage compartment is prevented from being unable to supply cold for a long time.

Preferably, t3 is less than or equal to 5min to ensure that the evaporator 12 provides enough cold for the condenser 21 to avoid excessive starting pressure at the low temperature stage compressor 22.

Preferably, t4= 0.5-10 min, and by this time, the pressure of the low-temperature-stage compressor 22 tends to be stable, and the improvement of the refrigeration efficiency of the low-temperature-stage refrigeration cycle loop 2 is facilitated, so that the temperature in the first storage compartment reaches the preset temperature as soon as possible, and the starting efficiency is improved.

Further, the control method may further include,

if T ₂ ≤T ₂₀ Then the control switch valve 17 is switched to communicate with only the second throttling device 162;

and after the preset time t2, controlling the low-temperature stage compressor 22 to start.

When the second storage chamber needs to refrigerate and the temperature T of the second storage chamber is in the running state of the refrigerating device ₂ Not higher than a predetermined temperature T ₂₀ At this time, the second throttling device 162 may be directly used to cool the evaporation part 12 to the condensation part 21, so that the first refrigerant flowing through the second throttling device 162 exchanges heat with the first refrigerant flowing through the high-temperature stage return pipe 13, thereby increasing the evaporation part12 to the cold supply amount of the condensation part 21, the precooling efficiency is accelerated, and the refrigerating efficiency of the second storage chamber is further improved.

Further, the control method may further include,

within a preset time T2, if T ₁ Down to T _{1 off} And T is ₂ And if the second preset condition is not met, the high-temperature stage compressor 11 is controlled to stop.

That is to say, within the preset time T2, if the temperature of the first storage chamber is reduced to the preset shutdown temperature T _{1 guan} And the temperature of the second storage chamber also reaches the preset shutdown temperature T _{2 guan (a)} Or the shutdown condition of the second storage compartment is met, the high-temperature stage compressor 11 can be stopped, so that energy consumption is saved.

Further, the control method may further include,

if the switching valve 17 is only communicated with the first cooling branch and the high-temperature stage compressor 11 is in the running state, timing the duration of the switching valve 17 in the state of being only communicated with the first cooling branch, and after a preset time T2, if the temperature T in the first storage compartment is up to the preset temperature T ₁ Has not yet fallen to the preset shutdown temperature T _{1 guan} Or below, determining the temperature T in the second storage room ₂ Whether a fourth preset condition is met or not, wherein the fourth preset condition is as follows: at this time T ₂ ≥T _{2 open} Or, alternatively, T _{2 off} <T ₂ <T _{2 open} And T2 is within T ₂ Is always greater than T _{2 off} ；

If yes, judging T ₂ Whether it is higher than the preset temperature T ₂₀ ；

If so, the switching valve 17 is controlled to switch to only communicate with the third throttling means 163;

after the preset time t3, controlling the low-temperature stage compressor 22 to start;

after the preset time t4, the switching valve 17 is controlled to be switched to be communicated with only the second throttling device 162.

Therefore, in the running process of the refrigerating device, the refrigeration of the first storage compartment is started from the high-temperature-level refrigeration circulation loop and is presetAfter the time t1, if the temperature in the first storage room is not reduced to the preset shutdown temperature, whether the second storage room needs to be refrigerated or not is judged firstly, so that the phenomenon that the temperature in the second storage room is too high due to the fact that the second storage room cannot be refrigerated for a long time and the articles stored in the second storage room are not favorable for keeping fresh is avoided. If the preset time T2 passes, the second storage chamber needs to be refrigerated, and the temperature T of the second storage chamber is ₂ Greater than a predetermined temperature T ₂₀ The switching valve 17 is controlled to be communicated with the third throttling device 163 only, and the high-temperature stage compressor 11 is controlled to be started, so that the problem of large starting pressure at the moment of starting the low-temperature stage compressor 22 can be solved, and because the first refrigerant in the third throttling device 163 does not exchange heat with the first refrigerant in the high-temperature stage air return pipe 13, the reduction of the flow rate of the first refrigerant in the third throttling device 163 is avoided, the evaporation part 12 is ensured to provide enough cold for the condensation part 21, and the overlarge pressure at the moment of starting the low-temperature stage compressor 22 is avoided. Further, after the preset time t3, the evaporation part 12 provides enough cooling capacity for the condensation part 21, at this time, the low-temperature stage compressor 22 is started, and the low-temperature stage refrigeration cycle loop 2 supplies cooling capacity for the second storage compartment. After a preset time t4, the low-temperature stage compressor 22 operates stably, at this time, the switching valve 17 is controlled to be switched to be only communicated with the second throttling device 162, the first refrigerant flowing through the second throttling device 162 exchanges heat with the first refrigerant flowing through the high-temperature stage return pipe 13, so that the first refrigerant in the high-temperature stage return pipe 13 can be used for cooling the first refrigerant in the second throttling device 162, the cooling capacity is increased, the suction temperature of the high-temperature stage compressor 11 is increased to about the ambient temperature, the cooling efficiency of the high-temperature stage compressor 11 is improved, the cooling capacity of the evaporation part 12 to the condensation part 21 is further improved, the cooling efficiency of the low-temperature stage refrigeration cycle loop 2 is improved, and the energy utilization rate of the cooling device is improved.

Further, the control method further comprises:

if T is ₂ ≤T ₀ Then the control switch valve 17 is switched to communicate with only the second throttling device 162;

and after the preset time t3, controlling the low-temperature stage compressor 22 to start.

When the second storage chamber needs to be refrigerated and the temperature T of the second storage chamber is in the running state of the refrigerating device ₂ Not higher than a predetermined temperature T ₂₀ When the cooling system is used, the second throttling device 162 can be directly used at the moment, so that the evaporation part 12 supplies cold to the condensation part 21, and therefore, the first refrigerant flowing through the second throttling device 162 exchanges heat with the first refrigerant flowing through the high-temperature-level air return pipe 13, the cold supply amount of the evaporation part 12 to the condensation part 21 can be improved, the precooling efficiency is accelerated, and the refrigerating efficiency of the second storage compartment is improved.

Further, the control method further comprises:

if T is ₂ If the fourth preset condition is not met, the duration of the switching valve 17 in the state of communication with only the first cooling branch is counted again.

That is, after the preset time T2, if the temperature of the first storage chamber has not decreased to the preset shutdown temperature T thereof yet _{1 off} And the temperature of the second storage chamber is reduced to the preset shutdown temperature T _{2 off} Or the shutdown condition of the second storage compartment is met, the high-temperature-stage compressor 11 needs to continue to operate at the moment, and for cooling the first storage compartment, a new round of temperature monitoring and compressor operation state control are performed by timing the duration of the switching valve 17 in the state of being only communicated with the first cooling branch again.

Compared with the prior art, the utility model provides a cascade compression refrigerating system 100, refrigerating plant who has it and refrigerating plant's control method, its beneficial effect lies in: the switching valve 17 selectively controls the flow direction of the first refrigerant as required to realize different functions and refrigeration effects; when the first refrigerant circulates in the first cooling branch, the high-temperature-stage evaporator 15 cools the first storage compartment; when the first refrigerant flows through the second cooling branch, the first refrigerant flows out of the second throttling device 162 to the evaporation part 12 in the high-temperature-stage refrigeration cycle circuit 1, and the first refrigerant in the evaporation part 12 can absorb heat of the second refrigerant flowing through the condensation part 21 by heat exchange between the second refrigerant flowing through the condensation part 21 and the first refrigerant flowing through the evaporation part 12, so that the temperature of the second refrigerant in the condensation part 21 can be further reduced, and the second refrigerant is precooled for the low-temperature-stage refrigeration cycle circuit 2, so that the low-temperature-stage refrigeration cycle circuit 2 can achieve a lower temperature; meanwhile, as 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 for cooling the first refrigerant in the first throttling device 161 and the second throttling device 162, so as to increase the cooling capacity, and simultaneously improve the suction temperature of the high-temperature stage compressor 11, so that the suction temperature is raised to about the ambient temperature, so as to improve the cooling efficiency of the high-temperature stage compressor 11 and the working efficiency of the high-temperature stage refrigeration cycle loop 1; when the low-temperature-stage compressor 22 is started, the first refrigerant can be circulated through the third throttling device 163, and the problem of a large starting pressure at the moment of starting the low-temperature-stage compressor 22 can be solved.

It should be understood that although the specification describes embodiments, not every embodiment includes only a single embodiment, and such description is for clarity purposes only, and it will be appreciated by those skilled in the art that the specification as a whole may be appropriately combined to form other embodiments as will be apparent to those skilled in the art.

The above list of details is only for the practical implementation of the present invention, and they are not intended to limit the scope of the present invention, and all equivalent implementations or modifications that do not depart from the technical spirit of the present invention should be included in the scope of the present invention.

Claims (10)

1. A cascade compression refrigeration system is characterized by comprising,

the high-temperature stage refrigeration cycle loop comprises a high-temperature stage compressor, a parallel branch and a high-temperature stage air return pipe for connecting the high-temperature stage compressor and the parallel branch, wherein a first refrigerant flows through the high-temperature stage refrigeration cycle loop, the parallel branch comprises a first cooling branch and a second cooling branch which are arranged in parallel, the first cooling branch comprises a first throttling device and a high-temperature stage evaporator which are arranged in series, the second cooling branch comprises a second throttling device and an evaporation part which are arranged in series, the parallel branch further comprises a third throttling device which is arranged in parallel with the second throttling device, 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 air return pipe respectively, the high-temperature stage refrigeration cycle loop further comprises a switching valve arranged at an inlet of the parallel branch, and the switching valve is selectively communicated with at least one of the first cooling branch, the second throttling device and the third throttling device;

and the low-temperature stage refrigeration circulation loop comprises a low-temperature stage compressor and a condensation part, wherein a second refrigerant flows in the low-temperature stage refrigeration circulation loop, and the second refrigerant flowing through the condensation part exchanges heat with the first refrigerant flowing through the evaporation part.

2. The cascade compression refrigeration system according to claim 1, wherein the low temperature stage refrigeration cycle further comprises a low temperature stage throttling device, a low temperature stage evaporator and a first return air pipe section arranged in series, and the condensing portion is arranged between the low temperature stage compressor and the low temperature stage throttling device.

3. The cascade compression refrigeration system of claim 2, wherein the second refrigerant flowing through the first return gas tube segment exchanges heat with the second refrigerant flowing through the low temperature stage throttling device.

4. The cascade compression refrigeration system according to claim 2, wherein the low-temperature stage refrigeration cycle further comprises a second gas return pipe section and a heat release pipe section, the second gas return pipe section is disposed between the low-temperature stage evaporator and the low-temperature stage compressor, the heat release pipe section is disposed between the low-temperature stage compressor and the condensation portion, and a second refrigerant flowing through the second gas return pipe section exchanges heat with a second refrigerant flowing through the heat release pipe section.

5. The cascade compression refrigeration system of claim 4, wherein the second return gas leg is located between the first return gas leg and the low temperature stage compressor.

6. The cascade compression refrigeration system according to claim 4, wherein the second return air duct segment is nested or abutted against the heat release duct segment.

7. The cascade compression refrigeration system according to claim 4, wherein the low temperature stage throttling device is a capillary tube, and the first return air tube section and the low temperature stage throttling device are sleeved or attached to each other.

8. The cascade compression refrigeration system according to claim 1, wherein said first throttling device and said second throttling device are respectively sleeved with or attached to said high temperature stage muffler.

9. A refrigerating device, comprising a box body, and further comprising the cascade compression refrigerating system according to any one of claims 1 to 8, wherein the box body has a first storage compartment and a second storage compartment therein, the high-temperature stage refrigerating cycle circuit supplies cold to the first storage compartment, and the low-temperature stage refrigerating cycle circuit supplies cold to the second storage compartment.

10. The refrigeration apparatus of claim 9, further comprising a controller coupled to the switching valve and configured to: according to the temperature of the first storage chamber and the second storage chamberControlAnd controlling the communication state of the switching valve, the first cooling branch, the second cooling branch and the third throttling device.

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