Cascade refrigeration system flow control method, device, refrigeration equipment and medium

Abstract

The application discloses a cascade refrigeration system flow control method and device, a refrigeration equipment and a medium. The cascade refrigeration system comprises a low-temperature stage compressor, a high-temperature stage compressor, an intermediate heat exchanger, a temperature sensor, a condensing fan and a temperature drop rate sensor. The temperature sensor is arranged on the intermediate heat exchanger. The method comprises the following steps: when the low-temperature stage compressor is started, the real-time temperature monitored by the temperature sensor is synchronously acquired, and the running time length of the low-temperature stage compressor is recorded; the running state of the low-temperature stage compressor is determined according to the real-time temperature and the running time length; and if the low-temperature stage compressor is in a low-flow running state, a low-flow response mode is started. The temperature detected by the temperature sensor and the calculated instantaneous temperature drop rate are utilized to determine the flow condition when the low-temperature stage compressor is started, and the flow control is performed according to the instantaneous temperature drop rate, so that the problem that the refrigerant flow is low and the temperature drop rate is slow due to the liquid accumulation in the intermediate heat exchanger when the low-temperature stage compressor is started is solved.

Description

Technical Field

[0001] This invention relates to the field of refrigeration technology, and more specifically to a flow control method, apparatus, refrigeration equipment, and medium for cascade refrigeration systems. Background Technology

[0002] With advancements in technology, cascade refrigeration systems, due to their significant effectiveness in achieving low temperatures, have been applied to products operating at -40℃ to -60℃, ultra-low temperatures of -86℃, and deep low temperatures of -150℃. While cascade refrigeration systems excel in achieving low-temperature environments, they are prone to causing excessively high compressor start-up discharge pressure. To prevent excessively high compressor discharge pressure, exceeding the compressor's operating conditions and causing it to trip, current technology involves adjusting the inverter compressor's frequency ramp-up rate after startup to control the system pressure within a reasonable range. However, under high heat loads, even when the inverter compressor operates at its lowest speed, the discharge pressure can still be too high, even exceeding the pressure limit. This can be addressed by increasing the size of the intermediate heat exchanger to enhance heat exchange between the high and low temperature stages, thereby reducing the compressor's start-up discharge pressure. However, this can easily lead to liquid accumulation of the low-temperature stage refrigerant in the intermediate heat exchanger, resulting in low refrigerant flow and slow cooling rate during compressor startup. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a flow control method, device, refrigeration equipment and medium for a cascade refrigeration system, aiming to solve the problem of low refrigerant flow and slow cooling rate caused by liquid accumulation in the intermediate heat exchanger when the low-temperature compressor starts up.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] In a first aspect, the present invention provides a flow control method for a cascade refrigeration system, wherein the cascade refrigeration system includes a low-temperature stage compressor, a high-temperature stage compressor, an intermediate heat exchanger, a temperature sensor, a condenser fan, and a cooling rate sensor, wherein the temperature sensor is disposed in the intermediate heat exchanger, and the method includes:

[0006] When the cryogenic stage compressor starts, the real-time temperature monitored by the temperature sensor at the intermediate heat exchanger is acquired synchronously, and the running time experienced by the cryogenic stage compressor from the start-up moment is recorded.

[0007] The operating status of the cryogenic compressor is determined based on real-time temperature and runtime.

[0008] If the cryogenic compressor is operating at low flow, then the low flow response mode will be activated.

[0009] Furthermore, determining the operating status of the cryogenic stage compressor based on real-time temperature and runtime includes:

[0010] The real-time temperature is compared with the preset critical temperature for the intermediate heat exchanger to start and float, and the running time is compared with the preset transition time.

[0011] If the real-time temperature is not lower than the critical temperature for starting the upward flow, or if the real-time temperature is lower than the critical temperature for starting the upward flow but the running time does not exceed the transition time, then the cryogenic stage compressor is determined to be in normal operating condition.

[0012] If the real-time temperature is lower than the critical temperature for starting the upward flow and the running time exceeds the transition time, the cryogenic stage compressor is determined to be in a low-flow operation state.

[0013] Furthermore, if the cryogenic compressor is operating at low flow rate, the low flow rate response mode is activated, including:

[0014] The instantaneous cooling rate is calculated from the temperature measured by the cooling rate sensor.

[0015] According to the instantaneous cooling rate, the operating speed of the condenser fan is reduced, the operating frequency of the high-temperature stage compressor is reduced, and the operating frequency of the low-temperature stage compressor is increased.

[0016] Furthermore, the instantaneous cooling rate is functionally related to the operating speed of the condenser fan, the operating frequency of the high-temperature compressor, and the operating frequency of the low-temperature compressor.

[0017] Furthermore, the operating speed of the condenser fan changes linearly with the instantaneous cooling rate in a linear fashion, the operating frequency of the high-temperature stage compressor changes linearly with the instantaneous cooling rate in a quadratic fashion, and the operating frequency of the low-temperature stage compressor changes linearly with the instantaneous cooling rate in an inverse linear fashion.

[0018] Furthermore, if the cryogenic compressor is operating at low flow rates, then after activating the low flow response mode, the following additional steps are included:

[0019] After activating the low flow response mode, the low flow response mode will be deactivated when the current real-time temperature is detected to be no lower than the critical temperature for activating the upward flow.

[0020] Furthermore, if the cryogenic compressor is operating at low flow rates, then after activating the low flow response mode, the following additional steps are included:

[0021] After activating the low-traffic response mode, the time of entering the low-traffic response mode is recorded synchronously.

[0022] If the time to enter the low flow response mode is not less than the preset alarm time, and the current real-time temperature is still lower than the critical temperature for activating the upward flow, a fault alarm will be triggered.

[0023] Secondly, the present invention also provides a flow control device for a cascade refrigeration system, wherein the cascade refrigeration system includes a low-temperature stage compressor, a high-temperature stage compressor, an intermediate heat exchanger, a temperature sensor, a condenser fan, and a cooling rate sensor, wherein the temperature sensor is disposed in the intermediate heat exchanger, and the device includes:

[0024] The recording unit is used to synchronously acquire the real-time temperature monitored by the temperature sensor at the intermediate heat exchanger when the cryogenic stage compressor starts, and to record the running time experienced by the cryogenic stage compressor from the start-up time.

[0025] The determination unit is used to determine the operating status of the cryogenic stage compressor based on real-time temperature and running time.

[0026] The starting unit is used to activate the low-flow response mode if the cryogenic stage compressor is operating at a low flow rate.

[0027] Thirdly, the present invention also provides a refrigeration device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the cascade refrigeration system flow control method as described above.

[0028] Fourthly, the present invention also provides a computer-readable storage medium storing a computer program, the computer program including program instructions, which, when executed by a processor, cause the processor to perform the cascade refrigeration system flow control method as described above.

[0029] The beneficial effects of this invention compared to existing technologies are as follows: A flow control method for a cascade refrigeration system, comprising a low-temperature stage compressor, a high-temperature stage compressor, an intermediate heat exchanger, a temperature sensor, a condenser fan, and a cooling rate sensor, with the temperature sensor located in the intermediate heat exchanger, includes: simultaneously acquiring the real-time temperature monitored by the temperature sensor at the intermediate heat exchanger when the low-temperature stage compressor starts, and recording the operating time of the low-temperature stage compressor from the start-up moment; determining the operating status of the low-temperature stage compressor based on the real-time temperature and operating time; and activating a low-flow response mode if the low-temperature stage compressor is in a low-flow operating state. This invention utilizes the temperature detected by the temperature sensor at the intermediate heat exchanger and calculates the instantaneous cooling rate to determine the flow situation when the low-temperature stage compressor starts, and adjusts the operation of the low-temperature stage compressor, high-temperature stage compressor, and condenser fan according to the instantaneous cooling rate. This solves the problem of low refrigerant flow and slow cooling rate caused by liquid accumulation in the intermediate heat exchanger when the low-temperature stage compressor starts. Furthermore, temperature-based control, compared to time-based control in existing technologies, allows for more precise adjustment based on actual conditions, thus better ensuring the cooling rate.

[0030] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other objectives, features and advantages of the present invention more obvious and understandable, preferred embodiments are described in detail below. Attached Figure Description

[0031] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 A schematic diagram of a cascade refrigeration system provided in a specific embodiment of the present invention;

[0033] Figure 2 Signal diagram of a cascade refrigeration system provided in a specific embodiment of the present invention;

[0034] Figure 3 A flowchart of a flow control method for a cascade refrigeration system provided in a specific embodiment of the present invention;

[0035] Figure 4 A schematic block diagram of a flow control device for a cascade refrigeration system provided in a specific embodiment of the present invention;

[0036] Figure 5 This is a schematic block diagram of a refrigeration device provided for a specific embodiment of the present invention. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0039] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0040] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0041] Figure 1 A schematic diagram of a cascade refrigeration system provided in a specific embodiment of the present invention; Figure 2 This is a signal diagram of a cascade refrigeration system provided in a specific embodiment of the present invention. For example... Figure 1 and Figure 2 As shown, the cascade refrigeration system includes a low-temperature stage compressor (i.e., Figure 1 B1), high-temperature compressor (i.e. Figure 1 A1 in the text), high-temperature throttling device (i.e. Figure 1 A3 in the middle), low temperature stage throttling device (i.e. Figure 1 B2), intermediate heat exchanger (i.e. Figure 1 (AB), temperature sensor, condenser (i.e.) Figure 1 A2 in the middle), condenser fan (i.e. Figure 1 A21 in the middle), evaporator (i.e. Figure 1 The B3 sensor and the cooling rate sensor are used in cascade refrigeration systems, which can be applied in refrigerators, cold storage facilities, and other products. When used in direct-cooling refrigerators, the cooling rate sensor is placed at the top inside the refrigerator body to better reflect the cooling rate. Both the high-temperature stage compressor and the low-temperature stage compressor use variable frequency compressors to better control the pressure during startup. To avoid excessively high discharge pressure in the low-temperature stage during startup, the high-temperature stage compressor is turned on first to cool the low-temperature stage system. Once the high-temperature stage compressor reaches full frequency operation and the intermediate heat exchanger temperature reaches a specific value, the low-temperature stage compressor is then turned on for cooling.

[0042] like Figure 1As shown, the outlet of the high-temperature stage compressor is connected to the inlet of the condenser. The high-temperature stage compressor compresses the refrigerant, making it a high-temperature, high-pressure gas, which is then delivered to the condenser. The outlet of the condenser is connected to the inlet of the high-temperature stage throttling device. In the condenser, the high-temperature, high-pressure refrigerant gas exchanges heat with the external environment (e.g., through heat dissipation by the condenser fan), changing the refrigerant from a gaseous state to a liquid state. The liquid refrigerant then enters the high-temperature stage throttling device. The outlet of the high-temperature stage throttling device is connected to one side (high-temperature side) of the intermediate heat exchanger. After throttling and pressure reduction, the refrigerant exchanges heat with the low-temperature stage refrigerant in the intermediate heat exchanger. The outlet of the low-temperature stage compressor is connected to the other side (low-temperature side) of the intermediate heat exchanger. After condensation, the refrigerant gas is throttled and pressure reduced by the low-temperature stage throttling device, and then returns to the compressor via the evaporator. Figure 2 As shown, the cascade refrigeration system is equipped with a main board, which is connected to components such as a temperature sensor, a cooling rate sensor, a high-temperature stage compressor, a low-temperature stage compressor, and a condenser fan via control circuits. The temperature signal collected by the temperature sensor on the intermediate heat exchanger is transmitted to the main board for processing. The main board is equipped with the cascade refrigeration system flow control method of this application. According to the method, the frequency of the high-temperature stage compressor, the frequency of the low-temperature stage compressor, and the speed of the condenser fan are controlled to achieve normal operation and flow control of the entire cascade refrigeration system.

[0043] like Figure 3 As shown, this embodiment of the invention provides a flow control method for a cascade refrigeration system, which includes the following steps: S10-S30.

[0044] S10. When the cryogenic stage compressor starts, simultaneously acquire the real-time temperature monitored by the temperature sensor at the intermediate heat exchanger, and record the running time experienced by the cryogenic stage compressor from the start-up moment.

[0045] In this embodiment, a high-precision thermistor temperature sensor can be selected, which has the advantages of fast response and measurement accuracy of ±0.1℃, ensuring that the temperature changes of the refrigerant inside the intermediate heat exchanger can be captured in real time and accurately. When the cryogenic compressor starts, the real-time temperature T1 monitored by the temperature sensor is acquired simultaneously. At the same time, the system's timer immediately starts recording time, accurately calculating the running time t1 of the cryogenic compressor from the moment of start-up.

[0046] For example, after the cryogenic compressor starts, the temperature sensor quickly transmits the initial temperature of the intermediate heat exchanger, which is around -30 to -40°C, to the main board. The timer starts simultaneously and records this moment as the start of operation. As the system runs, the temperature data and runtime information are continuously updated. For example, after running for 10 seconds, the temperature drops to 23°C. All of this data is continuously recorded.

[0047] S20. Determine the operating status of the cryogenic compressor based on real-time temperature and runtime.

[0048] In one embodiment, step S20 specifically includes the following steps: S201-S203.

[0049] S201. Compare the real-time temperature with the preset critical temperature for the intermediate heat exchanger to start and float, and compare the running time with the preset transition time.

[0050] S202. If the real-time temperature is not lower than the critical temperature for starting the upward flow, or if the real-time temperature is lower than the critical temperature for starting the upward flow but the running time does not exceed the transition time, then the cryogenic stage compressor is determined to be in normal operating condition.

[0051] S203. If the real-time temperature is lower than the critical temperature for starting the upward flow and the running time exceeds the transition time, the low-temperature stage compressor is determined to be in a low-flow operation state.

[0052] For steps S201-S203, in this embodiment, the real-time temperature T1 is compared with the preset critical temperature T0 for the intermediate heat exchanger to start floating (this value is set based on the system design cooling capacity, refrigerant physical parameters, and past experimental data, for example, T0 is set to -20℃). At the same time, the running time t1 is compared with the preset transition time t0 (generally 60 seconds).

[0053] If T1≥T0, it means that the low-temperature stage circulating cooling capacity is sufficient and the refrigerant flow is normal, and it is judged to be in normal operating condition; if T1<T0 and t1≤t0, it means that the system is in a transitional debugging period, similar to the "break-in" stage of a new device when it is first started, and various parameters are approaching stability; if T1<T0 and t1>t0, it means that the low-temperature stage circulating cooling capacity is small and the flow rate is small, and the liquid refrigerant accumulates at the intermediate heat exchanger, that is, the low-temperature stage compressor is in a low-flow operating state.

[0054] For example, if T0 is set to -18℃ and t0 is 60 seconds, after the cryogenic compressor is started, the temperature T1 drops from approximately -30 to -40℃ to 17℃ within the first 30 seconds (T1 < T0 and t1 < t0), indicating that it is in a transitional state; if the temperature drops to -22℃ after 80 seconds of operation (T1 < T0 and t1 > t0), then the cryogenic compressor is considered to have entered a low-flow operation state.

[0055] S30. If the cryogenic compressor is operating at low flow, then activate the low flow response mode.

[0056] In one embodiment, step S30 specifically includes the following steps: S301-S302.

[0057] S301. Obtain the instantaneous cooling rate calculated from the temperature measured by the cooling rate sensor.

[0058] S302. Based on the instantaneous cooling rate, reduce the operating speed of the condenser fan and the operating frequency of the high-temperature stage compressor, while increasing the operating frequency of the low-temperature stage compressor.

[0059] For steps S301-S302, in this embodiment, when it is determined that the system is in a low-flow operation state, the cooling rate sensor data is immediately retrieved, and the instantaneous cooling rate dv is calculated according to dv = dT / dt (dT is the temperature change within a small time interval, and dt is the corresponding time interval). Based on the instantaneous cooling rate dv, the system operating parameters are adjusted, namely, reducing the condenser fan speed v1, reducing the high-temperature stage compressor frequency F1, and increasing the low-temperature stage compressor frequency F2, in order to reduce the liquid refrigerant and increase the flow rate.

[0060] By dynamically adjusting system parameters based on the cooling rate, the limitations of traditional fixed-parameter operation are broken, and the problems of liquid refrigerant accumulation and low flow rate are solved at the root.

[0061] To quickly resolve the low flow rate issue, specifically, the instantaneous cooling rate is functionally related to the operating speed of the condenser fan, the operating frequency of the high-temperature stage compressor, and the operating frequency of the low-temperature stage compressor. More specifically, the operating speed of the condenser fan changes linearly proportionally to the instantaneous cooling rate (a linear function), the operating frequency of the high-temperature stage compressor changes linearly quadratically to the instantaneous cooling rate, and the operating frequency of the low-temperature stage compressor changes linearly inversely to the instantaneous cooling rate.

[0062] In this embodiment, the operating speed v1 of the condenser fan is adjusted according to the function v1 = f1(dv). For example, f1(dv) is set as a linear function v1 = k1dv + b1 (k1 and b1 are coefficients determined based on system debugging; assuming k1 = -2 and b1 = 1000, a decrease in dv results in a proportional linear decrease in v1). That is, the condenser fan speed changes linearly with the instantaneous cooling rate; a decrease in the instantaneous cooling rate results in a proportional decrease in the condenser fan speed. The high-temperature stage compressor frequency F1 is adjusted according to F1 = f2(dv) (a quadratic function F1 = k2dv² + b²; assuming k2 = -0.5 and b2 = 800). That is, the high-temperature stage compressor frequency changes linearly with the instantaneous cooling rate; a decrease in the instantaneous cooling rate results in a decrease in the high-temperature stage compressor frequency. The frequency F2 of the cryogenic stage compressor increases according to F2=f3(dv) (inverse proportional function F2=k3 / dv+b3, assuming k3=500, b3=30), that is, the frequency of the cryogenic stage compressor changes inversely proportionally and linearly with the instantaneous cooling rate. When the instantaneous cooling rate decreases, the frequency of the cryogenic stage compressor increases.

[0063] For example, when entering low flow mode, dv = -0.5℃ / second is calculated. After adjusting according to the function, the condenser fan speed drops from 1500 rpm to 1200 rpm, the high-temperature compressor frequency drops from 60Hz to 40Hz, and the low-temperature compressor frequency increases from 30Hz to 40Hz.

[0064] In one embodiment, after step S30, the following step is further included: S40.

[0065] S40. After activating the low flow response mode, when the current real-time temperature is detected to be no lower than the critical temperature for activating the upward flow, the low flow response mode is deactivated.

[0066] In this embodiment, after the low flow response mode is activated, the system continuously monitors the real-time temperature T1 of the intermediate heat exchanger. Once T1 rises to ≥T0, the special parameter adjustment under the low flow response mode is immediately terminated, and the high-temperature compressor, low-temperature compressor and condenser fan resume operation according to the preset conventional frequency increase curve or stable operating frequency, returning to the normal cooling rhythm.

[0067] For example, if the temperature rises from -25℃ to -18℃ (≥T0) after adjustment, the system will automatically switch back to normal operating mode.

[0068] In one embodiment, after step S30, the following steps are also included: S60-S70.

[0069] S60. After activating the low-traffic response mode, the time of entering the low-traffic response mode is recorded synchronously.

[0070] S70. If the time to enter the low flow response mode is not less than the preset alarm time, and the current real-time temperature is still lower than the critical temperature for starting the upward flow, a fault alarm will be triggered.

[0071] For steps S60-S70, in this embodiment, the time t2 for entering the low-traffic response mode is recorded synchronously, and the preset alarm time t3 (set to 300 seconds according to actual conditions) is recorded. If t2≥t3 and T1 is still <T0, the system triggers an audible and visual alarm and sends fault information to the remote monitoring terminal (data is transmitted remotely via an IoT module) to facilitate timely maintenance by operation and maintenance personnel.

[0072] This invention utilizes the temperature detected by a temperature sensor at the intermediate heat exchanger and calculates the instantaneous cooling rate to determine the flow rate during the startup of the low-temperature stage compressor. Based on the instantaneous cooling rate, the operation of the low-temperature stage compressor, the high-temperature stage compressor, and the condenser fan are adjusted. This solves the problem of low refrigerant flow and slow cooling rate caused by liquid accumulation in the intermediate heat exchanger during the startup of the low-temperature stage compressor. Furthermore, temperature-based control, compared to the existing technology that uses time-based control, allows for more precise adjustment based on actual conditions, thus better ensuring the cooling rate.

[0073] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0074] This invention also provides a flow control device for a cascade refrigeration system, which is used to perform the steps in any of the aforementioned embodiments of the flow control method for a cascade refrigeration system. Specifically, please refer to... Figure 4 , Figure 4 A schematic block diagram of a cascade refrigeration system flow control device 100 provided in an embodiment of this application is shown. The cascade refrigeration system flow control device 100 specifically includes a recording unit 110, used to simultaneously acquire the real-time temperature monitored by the temperature sensor at the intermediate heat exchanger when the low-temperature stage compressor starts, and to record the running time experienced by the low-temperature stage compressor from the start-up time; a determination unit 120, used to determine the operating state of the low-temperature stage compressor based on the real-time temperature and the running time; and a start unit 130, used to start a low-flow response mode if the low-temperature stage compressor is in a low-flow operating state.

[0075] In one embodiment, the determination unit 120 is specifically used to: compare the real-time temperature with the preset start-up critical temperature of the intermediate heat exchanger, and compare the running time with the preset transition time; if the real-time temperature is not lower than the start-up critical temperature, or the real-time temperature is lower than the start-up critical temperature but the running time does not exceed the transition time, then the cryogenic compressor is determined to be in normal operation; if the real-time temperature is lower than the start-up critical temperature and the running time exceeds the transition time, then the cryogenic compressor is determined to be in low-flow operation.

[0076] In one embodiment, the starting unit 130 is specifically used to: obtain the instantaneous cooling rate calculated from the temperature measured by the cooling rate sensor; and reduce the operating speed of the condenser fan and the operating frequency of the high-temperature stage compressor according to the instantaneous cooling rate, while increasing the operating frequency of the low-temperature stage compressor.

[0077] Specifically, the instantaneous cooling rate is functionally related to the operating speed of the condenser fan, the operating frequency of the high-temperature compressor, and the operating frequency of the low-temperature compressor.

[0078] More specifically, the operating speed of the condenser fan changes linearly with the instantaneous cooling rate in a linear fashion, the operating frequency of the high-temperature stage compressor changes linearly with the instantaneous cooling rate in a quadratic fashion, and the operating frequency of the low-temperature stage compressor changes linearly with the instantaneous cooling rate in an inverse linear fashion.

[0079] In one embodiment, the cascade refrigeration system flow control device 100 further includes a release unit, which is used to release the low flow response mode when the current real-time temperature is detected to be not lower than the activation floating critical temperature after the low flow response mode is activated.

[0080] In one embodiment, the cascade refrigeration system flow control device 100 further includes a time recording unit for synchronously recording the time of entering the low flow response mode after the low flow response mode is activated; and an alarm unit for issuing a fault alarm reminder if the time of entering the low flow response mode is not less than a preset alarm time and the current real-time temperature is still lower than the activation floating critical temperature.

[0081] It should be noted that those skilled in the art can clearly understand that the specific implementation process of the above-mentioned cascade refrigeration system flow control device 100 and each unit can be referred to the corresponding description in the foregoing method embodiments. For the sake of convenience and brevity, it will not be repeated here.

[0082] The aforementioned flow control device for the cascade refrigeration system can be implemented as a computer program, which can, for example... Figure 5 The refrigeration equipment shown is running.

[0083] Please see Figure 5 , Figure 5 This is a schematic block diagram of a refrigeration device provided in an embodiment of this application. The refrigeration device 700 can be a refrigerator, a cold chain transport vehicle, or other equipment with a cascade refrigeration system.

[0084] like Figure 5 As shown, the refrigeration device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the flow control method steps of the cascade refrigeration system as described above.

[0085] The cooling device 700 includes a processor 720, a memory, and a network interface 750 connected via a system bus 710. The memory may include a non-volatile storage medium 730 and internal memory 740.

[0086] The non-volatile storage medium 730 can store an operating system 731 and a computer program 732. When the computer program 732 is executed, it causes the processor 720 to perform a cascade cooling system flow control method.

[0087] The processor 720 provides computing and control capabilities to support the operation of the entire refrigeration unit 700.

[0088] The internal memory 740 provides an environment for the operation of the computer program 732 in the non-volatile storage medium 730. When the computer program 732 is executed by the processor 720, the processor 720 can execute the cascade cooling system flow control method.

[0089] This network interface 750 is used for network communication, such as sending assigned tasks. Those skilled in the art will understand that... Figure 5 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the refrigeration device 700 to which the present application is applied. A specific refrigeration device 700 may include more or fewer components than shown in the figure, or combine certain components, or have different component arrangements. The processor 720 is used to run program code stored in memory to implement the cascade refrigeration system flow control method.

[0090] Those skilled in the art will understand that Figure 5 The embodiments of the refrigeration device shown do not constitute a limitation on the specific configuration of the refrigeration device. In other embodiments, the refrigeration device may include more or fewer components than shown, or combine certain components, or have different component arrangements. For example, in some embodiments, the refrigeration device may include only a memory and a processor. In such embodiments, the structure and function of the memory and processor are different from those shown. Figure 5 The embodiments shown are consistent and will not be repeated here.

[0091] It should be understood that, in the embodiments of this application, the processor 720 may be a central processing unit (CPU), or it may be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor.

[0092] In another embodiment of the present invention, a computer-readable storage medium is provided. This computer-readable storage medium may be a non-volatile computer-readable storage medium. The computer-readable storage medium stores a computer program, wherein when executed by a processor, the computer program implements the cascade refrigeration system flow control method disclosed in the embodiments of the present invention.

[0093] Those skilled in the art will readily understand that, for the sake of convenience and brevity, the specific working processes of the devices, apparatuses, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in terms of function in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this invention.

[0094] In the embodiments provided by this invention, it should be understood that the disclosed devices, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative. For instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. Units with the same function may be grouped into one unit. For example, multiple units or components may be combined or integrated into another device, or some features may be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, devices, or units, or may be electrical, mechanical, or other forms of connection.

[0095] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of the embodiments of the present invention, depending on actual needs.

[0096] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0097] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), magnetic disks, or optical disks.

[0098] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A flow control method for a cascade refrigeration system, characterized in that, The cascade refrigeration system includes a low-temperature stage compressor, a high-temperature stage compressor, an intermediate heat exchanger, a temperature sensor, a condenser fan, and a cooling rate sensor. The temperature sensor is located in the intermediate heat exchanger. The method includes: When the cryogenic stage compressor starts, the real-time temperature monitored by the temperature sensor at the intermediate heat exchanger is acquired synchronously, and the running time experienced by the cryogenic stage compressor from the start-up moment is recorded. The operating status of the cryogenic compressor is determined based on real-time temperature and runtime. If the cryogenic stage compressor is operating at low flow, then the low flow response mode will be activated. If the cryogenic compressor is operating at low flow, a low flow response mode will be activated, including: The instantaneous cooling rate is calculated from the temperature measured by the cooling rate sensor. According to the instantaneous cooling rate, the operating speed of the condenser fan is reduced, the operating frequency of the high-temperature stage compressor is reduced, and the operating frequency of the low-temperature stage compressor is increased.

2. The flow control method for a cascade refrigeration system according to claim 1, characterized in that, The method of determining the operating status of the cryogenic compressor based on real-time temperature and runtime includes: The real-time temperature is compared with the preset critical temperature for the intermediate heat exchanger to start and float, and the running time is compared with the preset transition time. If the real-time temperature is not lower than the critical temperature for starting the upward flow, or if the real-time temperature is lower than the critical temperature for starting the upward flow but the running time does not exceed the transition time, then the cryogenic stage compressor is determined to be in normal operating condition. If the real-time temperature is lower than the critical temperature for starting the upward flow and the running time exceeds the transition time, the cryogenic stage compressor is determined to be in a low-flow operation state.

3. The flow control method for a cascade refrigeration system according to claim 1, characterized in that, The instantaneous cooling rate is functionally related to the operating speed of the condenser fan, the operating frequency of the high-temperature compressor, and the operating frequency of the low-temperature compressor.

4. The flow control method for a cascade refrigeration system according to claim 3, characterized in that, The operating speed of the condenser fan changes linearly with the instantaneous cooling rate in a linear fashion, the operating frequency of the high-temperature stage compressor changes linearly with the instantaneous cooling rate in a quadratic fashion, and the operating frequency of the low-temperature stage compressor changes linearly with the instantaneous cooling rate in an inverse linear fashion.

5. The flow control method for a cascade refrigeration system according to claim 1, characterized in that, If the cryogenic compressor is operating at low flow, the low flow response mode, after being activated, also includes: After activating the low flow response mode, the low flow response mode will be deactivated when the current real-time temperature is detected to be no lower than the critical temperature for activating the upward flow.

6. The flow control method for a cascade refrigeration system according to claim 1, characterized in that, If the cryogenic compressor is operating at low flow, the low flow response mode, after being activated, also includes: After activating the low-traffic response mode, the time of entering the low-traffic response mode is recorded synchronously. If the time to enter the low flow response mode is not less than the preset alarm time, and the current real-time temperature is still lower than the critical temperature for activating the upward flow, a fault alarm will be triggered.

7. A flow control device for a cascade refrigeration system, wherein, during operation, it executes the flow control method for a cascade refrigeration system as described in any one of claims 1-6, characterized in that, The cascade refrigeration system includes a low-temperature stage compressor, a high-temperature stage compressor, an intermediate heat exchanger, a temperature sensor, a condenser fan, and a cooling rate sensor. The temperature sensor is located in the intermediate heat exchanger. The device includes: The recording unit is used to synchronously acquire the real-time temperature monitored by the temperature sensor at the intermediate heat exchanger when the cryogenic stage compressor starts, and to record the running time experienced by the cryogenic stage compressor from the start-up time. The determination unit is used to determine the operating status of the cryogenic stage compressor based on real-time temperature and running time. The starting unit is used to activate the low-flow response mode if the cryogenic stage compressor is operating at a low flow rate.

8. A refrigeration device, characterized in that, The system includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements the flow control method for a cascade refrigeration system as described in any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that, The storage medium stores a computer program, which includes program instructions. When the program instructions are executed by a processor, the processor performs the flow control method for a cascade refrigeration system as described in any one of claims 1 to 6.

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