Flow control method and device for cascade refrigeration system, refrigeration equipment and medium

Abstract

The invention discloses a cascade refrigeration system flow control method and device, refrigeration equipment and a medium, a cascade refrigeration system comprises a low-temperature-stage compressor, a high-temperature-stage compressor, an intermediate heat exchanger, a temperature sensor, a condensation fan and a cooling rate sensor, and the temperature sensor is arranged in the intermediate heat exchanger. The real-time temperature monitored by the temperature sensor is synchronously obtained, and the operation duration of the low-temperature-stage compressor is recorded; the operation state of the low-temperature-stage compressor is judged according to the real-time temperature and the operation duration; and if the low-temperature compressor is in the low-flow operation state, a low-flow response mode is started. The flow condition of the low-temperature compressor during starting is judged according to the temperature detected by the temperature sensor and the calculated instantaneous cooling rate, and flow control is performed according to the instantaneous cooling rate, so that the problems of low refrigerant flow and slow cooling rate caused by liquid accumulation in the intermediate heat exchanger during starting of the low-temperature compressor are solved.

Description

Technical Field

[0001] The present invention relates to the field of refrigeration technology, and more specifically to a flow control method, device, refrigeration equipment and medium for a cascade refrigeration system. Background Art

[0002] With the advancement of science and technology, the cascade refrigeration system has been used in products with low temperatures of -40℃ to -60℃, ultra-low temperatures of -86℃, and deep low temperatures of -150℃ due to its remarkable effect in obtaining low temperatures. The cascade refrigeration system has a remarkable effect in obtaining low-temperature environments, but it is easy to cause the problem of too high exhaust pressure when the compressor starts. In order to avoid the compressor exhaust pressure being too high and exceeding the compressor operating conditions, thereby causing the compressor to trip. The prior art is to reasonably adjust the frequency increase rate of the variable frequency compressor after the compressor is turned on, so as to control the system pressure within a reasonable range. However, when the heat load is large and the variable frequency compressor maintains operation at the lowest speed, the exhaust pressure will also be too high, even exceeding the pressure limit. For this reason, the intermediate heat exchanger can be increased to enhance the heat exchange of the refrigerant between the high and low temperature stages, thereby reducing the exhaust pressure when the compressor starts. However, this is easy to cause the low-temperature refrigerant to accumulate in the intermediate heat exchanger in a liquid state, and the refrigerant flow rate is low when the low-temperature compressor starts, and the cooling rate is slow. Summary of the invention

[0003] The purpose of the present 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 is started.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

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

[0006] When the low-temperature compressor is started, the real-time temperature monitored by the temperature sensor at the intermediate heat exchanger is simultaneously obtained, and the running time of the low-temperature compressor from the start-up time is recorded;

[0007] Determine the operating status of the low-temperature compressor based on the real-time temperature and operating time;

[0008] If the low temperature stage compressor is in low flow operation, the low flow response mode is activated.

[0009] Further, the step of determining the operating state of the low temperature compressor according to the real-time temperature and the operating time includes:

[0010] Compare the real-time temperature with the preset critical temperature of the intermediate heat exchanger for opening and floating, and compare the operation time with the preset transition time;

[0011] If the real-time temperature is not lower than the critical temperature for starting the floating operation, or if the real-time temperature is lower than the critical temperature for starting the floating operation but the operation time does not exceed the transition time, it is determined that the low-temperature compressor is in normal operation;

[0012] If the real-time temperature is lower than the critical temperature for starting the floating operation and the operation time exceeds the transition time, it is determined that the low-temperature compressor is in a low-flow operation state.

[0013] Furthermore, if the low temperature compressor is in a low flow operation state, the low flow response mode is started, including:

[0014] Obtaining an instantaneous cooling rate calculated from the temperature measured by a cooling rate sensor;

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

[0017] Furthermore, the operating speed of the condensing fan changes linearly in proportion to the instantaneous cooling rate as a linear function, the operating frequency of the high-temperature stage compressor changes linearly in proportion to the instantaneous cooling rate as a quadratic function, and the operating frequency of the low-temperature stage compressor changes linearly in proportion to the instantaneous cooling rate as an inverse function.

[0018] Furthermore, if the low-temperature compressor is in a low-flow operation state, after starting the low-flow response mode, the method further includes:

[0019] After the low flow response mode is started, when it is detected that the current real-time temperature is not lower than the critical temperature for starting the floating, the low flow response mode is released.

[0020] Furthermore, if the low-temperature compressor is in a low-flow operation state, after starting the low-flow response mode, the method further includes:

[0021] After the low flow response mode is started, the time of entering the low flow response mode is simultaneously recorded;

[0022] If the time to enter the low flow response mode is not less than the preset alarm time, and it is detected that the current real-time temperature is still lower than the critical temperature for starting the float, a fault alarm reminder will be issued.

[0023] In a second aspect, the present invention further provides a flow control device for a cascade refrigeration system, wherein the cascade refrigeration system comprises a low-temperature compressor, a high-temperature compressor, an intermediate heat exchanger, a temperature sensor, a condensing fan, and a cooling rate sensor, wherein the temperature sensor is disposed in the intermediate heat exchanger, and the device comprises:

[0024] A recording unit, used to synchronously obtain the real-time temperature monitored by the temperature sensor at the intermediate heat exchanger when the low-temperature compressor is started, and to record the running time experienced by the low-temperature compressor from the start-up time;

[0025] A determination unit, used for determining the operating state of the low temperature compressor according to the real-time temperature and the operating time;

[0026] The starting unit is used to start the low flow response mode if the low temperature stage compressor is in a low flow operation state.

[0027] In a third aspect, the present invention further provides a refrigeration device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the flow control method of the cascade refrigeration system as described above when executing the computer program.

[0028] In a fourth aspect, the present invention further provides a computer-readable storage medium, wherein the storage medium stores a computer program, wherein the computer program includes program instructions, and when the program instructions are executed by a processor, the processor executes the flow control method for a cascade refrigeration system as described above.

[0029] Compared with the prior art, the present invention has the following beneficial effects: a flow control method for a cascade refrigeration system, wherein the cascade refrigeration system comprises a low-temperature compressor, a high-temperature compressor, an intermediate heat exchanger, a temperature sensor, a condensing fan and a cooling rate sensor, wherein the temperature sensor is arranged at the intermediate heat exchanger, and the method comprises: when the low-temperature compressor is started, synchronously obtaining the real-time temperature monitored by the temperature sensor at the intermediate heat exchanger, and recording the running time experienced by the low-temperature compressor from the start-up time; judging the running state of the low-temperature compressor according to the real-time temperature and the running time; and starting the low-flow response mode if the low-temperature compressor is in a low-flow running state. The present invention uses the temperature detected by the temperature sensor at the intermediate heat exchanger and the calculated instantaneous cooling rate to judge the flow condition when the low-temperature compressor is started, and adjusts the running conditions of the low-temperature compressor, the high-temperature compressor and the condensing fan according to the instantaneous cooling rate, thereby solving the problem of low refrigerant flow and slow cooling rate caused by liquid accumulation in the intermediate heat exchanger when the low-temperature compressor is started. At the same time, the control is carried out according to the temperature, which can be more accurately regulated according to the actual situation than the prior art using time control, thereby better ensuring the cooling rate.

[0030] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the following preferred embodiments are specifically cited and described in detail as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

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

[0033] Figure 2 A signal diagram of a cascade refrigeration system provided by a specific embodiment of the present invention;

[0034] Figure 3 A flow chart of a cascade refrigeration system flow control method provided by 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 A schematic block diagram of a refrigeration device provided in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work 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 "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

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

[0040] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0041] Figure 1 A schematic diagram of a cascade refrigeration system provided in a specific embodiment of the present invention; Figure 2 The signal diagram of the cascade refrigeration system provided by the specific embodiment of the present invention. Figure 1 and Figure 2 As shown, the cascade refrigeration system includes a low temperature compressor (i.e. Figure 1 B1 in), high temperature compressor (i.e. Figure 1 A1 in), high temperature throttling device (i.e. Figure 1 A3 in), low temperature throttling device (i.e. Figure 1 B2 in), intermediate heat exchanger (i.e. Figure 1 AB in), temperature sensor, condenser (i.e. Figure 1 A2 in), condensing fan (i.e. Figure 1 A21 in), evaporator (i.e. Figure 1 B3) and the cooling rate sensor. The cascade refrigeration system can be used in refrigerators, cold storage and other products. When used in direct-cooling refrigerators, the cooling rate sensor is arranged on the top of the refrigerator body, so as to better reflect the cooling rate. Both the high-temperature compressor and the low-temperature compressor use variable frequency compressors to better control the pressure at startup. When the cascade refrigeration system is started, in order to avoid excessive low-temperature exhaust pressure, the high-temperature compressor will be turned on to cool the low-temperature system first. After the high-temperature compressor is increased to full frequency operation and the temperature of the intermediate heat exchanger reaches a specific value, the low-temperature compressor will be turned on for refrigeration.

[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 to make it a high-temperature and high-pressure gas, and then transports this high-temperature and high-pressure refrigerant gas 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 and high-pressure refrigerant gas exchanges heat with the external environment (for example, heat is dissipated by the condensing fan), and the refrigerant changes from gas to liquid, and then the liquid refrigerant enters the high-temperature stage throttling device. The outlet of the high-temperature stage throttling device is connected to one side of the intermediate heat exchanger (high-temperature side), and the refrigerant after throttling and reducing the pressure 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 of the intermediate heat exchanger (low-temperature side). After the refrigerant gas is condensed, it is throttled and reduced in pressure through the low-temperature stage throttling device, and then returns to the compressor through the evaporator. As shown Figure 2 As shown, the cascade refrigeration system is configured with a main board, which is connected to components such as temperature sensors, cooling rate sensors, high-temperature compressors, low-temperature compressors and condensing fans through control lines. 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 configured with the cascade refrigeration system flow control method of the present application, and the high-temperature compressor frequency, low-temperature compressor frequency and condensing fan speed are controlled according to the method to achieve normal operation and flow control of the entire cascade refrigeration system.

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

[0044] S10. When the low-temperature compressor is started, the real-time temperature monitored by the temperature sensor at the intermediate heat exchanger is synchronously obtained, and the running time of the low-temperature compressor from the start-up time is recorded.

[0045] In this embodiment, the temperature sensor can be a high-precision thermistor temperature sensor, which has the advantages of fast response and measurement accuracy of up to ±0.1°C, ensuring that the temperature change of the refrigerant inside the intermediate heat exchanger can be captured accurately in real time. When the low-temperature compressor is started, the real-time temperature T1 monitored by the temperature sensor is obtained synchronously. At the same time, the system timer immediately starts recording the time, and accurately counts the running time t1 experienced by the low-temperature compressor from the moment it is started.

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

[0047] S20: Determine the operating state of the low-temperature compressor according to the real-time temperature and the operating time.

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

[0049] S201, comparing the real-time temperature with the preset critical temperature of the intermediate heat exchanger for starting and floating, and comparing the operation time with the preset transition time;

[0050] S202: If the real-time temperature is not lower than the critical temperature for starting the floating operation, or if the real-time temperature is lower than the critical temperature for starting the floating operation but the operation time does not exceed the transition time, it is determined that the low-temperature compressor is in a normal operation state;

[0051] S203: If the real-time temperature is lower than the critical temperature for starting the floating operation and the operation time exceeds the transition time, it is determined that the low-temperature compressor is in a low-flow operation state.

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

[0053] If T1≥T0, it means that the low-temperature stage circulation cooling capacity is sufficient and the refrigerant flow is normal, and it is judged to be in normal operating state; if T1<T0 and t1≤t0, it means that the system is in a transition debugging period, similar to the "running-in" stage when a new equipment is just started, and various parameters are approaching stability; if T1<T0 and t1>t0, it means that the low-temperature stage circulation cooling capacity is small, the flow is small, and the liquid refrigerant accumulates in the intermediate heat exchanger, that is, the low-temperature stage compressor is in a low-flow operation state.

[0054] For example, setting T0 to -18°C and t0 to 60 seconds, after starting the low-temperature compressor for a certain time, the temperature T1 drops from the initial -30 to -40°C to 17°C (T1<T0 and t1<t0) within the first 30 seconds, and it is judged to be in a transitional state; if the temperature drops to -22°C (T1<T0 and t1>t0) after running for 80 seconds, it is determined that the low-temperature compressor has entered a low-flow operation state.

[0055] S30: If the low temperature compressor is in a low flow operation state, the low flow response mode is started.

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

[0057] S301, obtaining an instantaneous cooling rate calculated from the temperature measured by a cooling rate sensor.

[0058] S302, according to the instantaneous temperature drop rate, the operating speed of the condensing fan is reduced accordingly, the operating frequency of the high-temperature compressor is reduced, and the operating frequency of the low-temperature compressor is increased.

[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 in a small time interval, and dt is the corresponding time interval). The system operating parameters are adjusted according to the instantaneous cooling rate dv, that is, the condensing fan speed v1 is reduced, the high temperature compressor frequency F1 is reduced, and the low temperature compressor frequency F2 is increased to reduce the liquid refrigerant and increase the flow rate.

[0060] Dynamically adjusting system parameters based on the cooling rate breaks the limitations of traditional fixed parameter operation and solves the problems of liquid refrigerant accumulation and low flow rate from the root.

[0061] In order to solve the low flow problem as soon as possible, specifically, the instantaneous cooling rate is functionally associated with the operating speed of the condensing fan, the operating frequency of the high-temperature compressor, and the operating frequency of the low-temperature compressor. More specifically, the operating speed of the condensing fan changes linearly with the instantaneous cooling rate in a linear function, the operating frequency of the high-temperature compressor changes linearly with the instantaneous cooling rate in a quadratic function, and the operating frequency of the low-temperature compressor changes linearly with the instantaneous cooling rate in an inversely proportional function.

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

[0063] For example, when entering the low flow mode, dv=-0.5℃ / sec is calculated. After adjustment according to the function, the speed of the condensing fan is reduced from 1500 rpm to 1200 rpm, the frequency of the high-temperature compressor is reduced from 60Hz to 40Hz, and the frequency of the low-temperature compressor is increased from 30Hz to 40Hz.

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

[0065] S40: After the low flow response mode is started, when it is detected that the current real-time temperature is not lower than the critical temperature for starting the floating, the low flow response mode is released.

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

[0067] For example, if the temperature rises from -25°C to -18°C (≥T0) after adjustment, the system automatically switches back to normal operation mode.

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

[0069] S60: After the low flow response mode is started, the time of entering the low flow response mode is synchronously recorded.

[0070] S70: If the time of entering the low flow response mode is not less than the preset alarm time, and if it is detected that the current real-time temperature is still lower than the critical temperature for starting the floating, a fault alarm reminder is issued.

[0071] For steps S60-S70, in this embodiment, the time t2 of entering the low flow response mode is synchronously recorded, and the alarm time t3 is preset (set to 300 seconds according to the actual situation). 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 through the Internet of Things module) to facilitate timely maintenance by operation and maintenance personnel.

[0072] The present invention utilizes the temperature detected by the temperature sensor at the intermediate heat exchanger and calculates the instantaneous cooling rate to judge the flow condition when the low-temperature compressor is started, and adjusts the operation conditions of the low-temperature compressor, the high-temperature compressor and the condensing fan according to the instantaneous cooling rate, thereby solving the problems of low refrigerant flow and slow cooling rate caused by liquid accumulation in the intermediate heat exchanger when the low-temperature compressor is started. At the same time, control based on temperature can be more accurately regulated according to actual conditions than the prior art that uses time to control, thereby better ensuring the cooling rate.

[0073] It should be understood that the order of execution of the steps in the above embodiment does not necessarily mean 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 embodiment of the present invention.

[0074] The embodiment of the present invention further provides a cascade refrigeration system flow control device, which is used to perform the steps in any embodiment of the cascade refrigeration system flow control method described above. Figure 4 , Figure 4 A schematic block diagram of a cascade refrigeration system flow control device 100 provided in an embodiment of the present application is shown. The cascade refrigeration system flow control device 100 specifically includes a recording unit 110, which is used to synchronously obtain the real-time temperature monitored by the temperature sensor at the intermediate heat exchanger when the low-temperature compressor is started, and record the operating time experienced by the low-temperature compressor from the start-up time; a determination unit 120, which is used to determine the operating state of the low-temperature compressor according to the real-time temperature and the operating time; and a starting unit 130, which is used to start a low-flow response mode if the low-temperature 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 critical temperature for starting and floating of the intermediate heat exchanger, and compare the operating time with the preset transition time; if the real-time temperature is not lower than the critical temperature for starting and floating, or the real-time temperature is lower than the critical temperature for starting and floating but the operating time does not exceed the transition time, it is determined that the low-temperature stage compressor is in a normal operating state; if the real-time temperature is lower than the critical temperature for starting and floating and the operating time exceeds the transition time, it is determined that the low-temperature stage compressor is in a low-flow operating state.

[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; reduce the operating speed of the condensing fan and the operating frequency of the high-temperature stage compressor according to the instantaneous cooling rate, and increase the operating frequency of the low-temperature stage compressor.

[0077] Specifically, the instantaneous cooling rate is functionally correlated with the operating speed of the condensing fan, the operating frequency of the high-temperature stage compressor, and the operating frequency of the low-temperature stage compressor.

[0078] More specifically, the operating speed of the condensing fan changes linearly in proportion to the instantaneous cooling rate as a linear function, the operating frequency of the high-temperature stage compressor changes linearly in proportion to the instantaneous cooling rate as a quadratic function, and the operating frequency of the low-temperature stage compressor changes linearly in proportion to the instantaneous cooling rate as an inverse function.

[0079] In one embodiment, the cascade refrigeration system flow control device 100 further includes a release unit for releasing the low flow response mode after the low flow response mode is started, when it is detected that the current real-time temperature is not lower than the floating start critical temperature.

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

[0081] It should be noted that technicians in the relevant field can clearly understand that the specific implementation process of the above-mentioned cascade refrigeration system flow control device 100 and each unit can refer to the corresponding description in the aforementioned method embodiment, and for the convenience and brevity of description, it will not be repeated here.

[0082] The above-mentioned cascade refrigeration system flow control device can be implemented in the form of a computer program. The computer program can be used in Figure 5 Operation on the refrigeration unit shown.

[0083] See also Figure 5 , Figure 5 Refrigeration equipment 700 may be a refrigerator, a cold chain transport vehicle or other equipment having 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, the steps of the flow control method of the cascade refrigeration system described above are implemented.

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

[0086] The non-volatile storage medium 730 may store an operating system 731 and a computer program 732. When the computer program 732 is executed, the processor 720 may execute a flow control method for a cascade refrigeration system.

[0087] The processor 720 is used to provide computing and control capabilities to support the operation of the entire refrigeration device 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 flow control method of the cascade refrigeration system.

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

[0090] Those skilled in the art will understand that Figure 5 The embodiments of the refrigeration device shown in the figure do not constitute a limitation on the specific structure of the refrigeration device. In other embodiments, the refrigeration device may include more or fewer components than shown in the figure, or combine certain components, or arrange the components differently. For example, in some embodiments, the refrigeration device may only include a memory and a processor. In such embodiments, the structure and function of the memory and the processor are the same as those in the figure. Figure 5 The embodiments shown are consistent and will not be described again here.

[0091] It should be understood that in the embodiment of the present application, the processor 720 may be a central processing unit (CPU), and the processor 720 may also be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. Among them, the general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

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

[0093] Those skilled in the art can clearly understand that, for the convenience and simplicity of description, the specific working process of the above-described equipment, devices and units can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here. Those of ordinary skill in the art can appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented with electronic hardware, computer software or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to the function. Whether these functions are executed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present invention.

[0094] In the several embodiments provided by the present invention, it should be understood that the disclosed equipment, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. Units with the same function may also be combined 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 an 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 separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the embodiments of the present invention.

[0096] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0097] If the integrated unit is implemented in the form of 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 is essentially 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. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), disk or optical disk and other media that can store program codes.

[0098] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection 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 compressor, a high-temperature compressor, an intermediate heat exchanger, a temperature sensor, a condensing fan, and a cooling rate sensor, wherein the temperature sensor is disposed at the intermediate heat exchanger, and the method includes: When the low-temperature compressor is started, the real-time temperature monitored by the temperature sensor at the intermediate heat exchanger is simultaneously obtained, and the running time of the low-temperature compressor from the start-up time is recorded; Determine the operating status of the low-temperature compressor based on the real-time temperature and operating time; If the low temperature stage compressor is in low flow operation, the low flow response mode is activated.

2. The flow control method of the cascade refrigeration system according to claim 1, characterized in that: Determining the operating state of the low-temperature compressor according to the real-time temperature and the operating time includes: Compare the real-time temperature with the preset critical temperature of the intermediate heat exchanger for opening and floating, and compare the operation time with the preset transition time; If the real-time temperature is not lower than the critical temperature for starting the floating operation, or if the real-time temperature is lower than the critical temperature for starting the floating operation but the operation time does not exceed the transition time, it is determined that the low-temperature compressor is in a normal operation state; If the real-time temperature is lower than the critical temperature for starting the floating operation and the operation time exceeds the transition time, it is determined that the low-temperature compressor is in a low-flow operation state.

3. The flow control method of a cascade refrigeration system according to claim 1, characterized in that: If the low temperature compressor is in a low flow operation state, the low flow response mode is started, including: Obtaining an instantaneous cooling rate calculated from the temperature measured by a cooling rate sensor; According to the instantaneous cooling rate, the operating speed of the condensing fan is reduced accordingly, the operating frequency of the high-temperature stage compressor is reduced, and the operating frequency of the low-temperature stage compressor is increased.

4. The flow control method of the cascade refrigeration system according to claim 3, characterized in that: The instantaneous cooling rate is functionally correlated with the operating speed of the condensing fan, the operating frequency of the high-temperature stage compressor, and the operating frequency of the low-temperature stage compressor.

5. The flow control method of a cascade refrigeration system according to claim 4, characterized in that: The operating speed of the condensing fan changes linearly and proportionally with the instantaneous cooling rate as a linear function, the operating frequency of the high-temperature compressor changes linearly and proportionally with the instantaneous cooling rate as a quadratic function, and the operating frequency of the low-temperature compressor changes linearly and inversely with the instantaneous cooling rate as a reverse function.

6. The flow control method of a cascade refrigeration system according to claim 1, characterized in that: If the low temperature compressor is in a low flow operation state, after starting the low flow response mode, the method further includes: After the low flow response mode is started, when it is detected that the current real-time temperature is not lower than the critical temperature for starting the floating, the low flow response mode is released.

7. The flow control method of a cascade refrigeration system according to claim 1, characterized in that: If the low temperature compressor is in a low flow operation state, after starting the low flow response mode, the method further includes: After the low flow response mode is started, the time of entering the low flow response mode is simultaneously recorded; If the time to enter the low flow response mode is not less than the preset alarm time, and it is detected that the current real-time temperature is still lower than the critical temperature for starting the float, a fault alarm reminder will be issued.

8. A flow control device for a cascade refrigeration system, characterized in that: The cascade refrigeration system includes a low-temperature compressor, a high-temperature compressor, an intermediate heat exchanger, a temperature sensor, a condensing fan, and a cooling rate sensor. The temperature sensor is arranged on the intermediate heat exchanger. The device includes: A recording unit, used to synchronously obtain the real-time temperature monitored by the temperature sensor at the intermediate heat exchanger when the low-temperature compressor is started, and to record the running time experienced by the low-temperature compressor from the start-up time; A determination unit, used for determining the operating state of the low temperature compressor according to the real-time temperature and the operating time; The starting unit is used to start the low flow response mode if the low temperature stage compressor is in a low flow operation state.

9. A refrigeration device, characterized in that: The method comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the flow control method of the cascade refrigeration system as claimed in any one of claims 1 to 7 when executing the computer program.

10. A computer-readable storage medium, characterized in that: The storage medium stores a computer program, and the computer program includes program instructions. When the program instructions are executed by a processor, the processor executes the cascade refrigeration system flow control method according to any one of claims 1 to 7.

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