Multi-stage cascade refrigeration heating method and device, storage medium and electronic equipment

Abstract

The application relates to a multi-stage cascade refrigeration and heating method, device, storage medium and electronic equipment. The method comprises the following steps: after starting a first-stage compressor of a multi-stage cascade refrigeration and heating device, determining a pressure change rate of the first-stage compressor, wherein the multi-stage cascade refrigeration and heating device at least comprises the first-stage compressor and a second-stage compressor; determining a starting time of the second-stage compressor according to the pressure change rate; and starting the second-stage compressor when the starting time of the second-stage compressor is met. The application solves the technical problem of compressor tripping in a two-stage cascade system.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of refrigeration and heating, and particularly relates to a multi-stage cascade refrigeration and heating method and device, a storage medium and an electronic device. BACKGROUND

[0002] In the prior art, in some scenarios, a two-stage cascade system can be used for refrigeration. The two-stage cascade system has two compressors, the first compressor is responsible for the first wave of refrigeration, and the cold air of the refrigeration is used for the second compressor, and the second compressor is responsible for the second wave of refrigeration. Compared with single-compressor refrigeration, the two-stage refrigeration can reduce the refrigeration pressure of a single compressor.

[0003] However, in the prior art, the start of the two-stage cascade refrigeration system is generally preset with a start interval, and then the first-stage compressor is started, and after the start interval is reached, the second-stage compressor is started. The start interval between the two compressors is fixed and not accurate, and the compressor pressure jump fault is prone to occur after the second-stage compressor is started. SUMMARY

[0004] The present application provides a multi-stage cascade refrigeration and heating method, device, storage medium and electronic device to solve the technical problem of compressor jump in a two-stage cascade system.

[0005] In a first aspect, the present application provides a multi-stage cascade refrigeration and heating method, comprising: determining a pressure change rate of a first-stage compressor of a multi-stage cascade refrigeration and heating device after starting the first-stage compressor, wherein the multi-stage cascade refrigeration and heating device comprises at least the first-stage compressor and a second-stage compressor; determining a start timing of the second-stage compressor according to the pressure change rate; and starting the second-stage compressor when the start timing of the second-stage compressor is met.

[0006] In a second aspect, the present application provides a multi-stage cascade refrigeration and heating device, comprising: a first determining module configured to determine a pressure change rate of a first-stage compressor of a multi-stage cascade refrigeration and heating device after starting the first-stage compressor, wherein the multi-stage cascade refrigeration and heating device comprises at least the first-stage compressor and a second-stage compressor; a second determining module configured to determine a start timing of the second-stage compressor according to the pressure change rate; and a starting module configured to start the second-stage compressor when the start timing of the second-stage compressor is met.

[0007] As an optional example, the second determining module comprises a determining unit configured to acquire a first starting time of the first-stage compressor and a default starting interval; when the pressure change rate exceeds a preset pressure threshold, increase a length of the default starting interval, and determine a second starting time of the second-stage compressor according to the increased default starting interval; when the pressure change rate is less than the preset pressure threshold, decrease the length of the default starting interval, and determine the second starting time of the second-stage compressor according to the decreased default starting interval.

[0008] As an optional example, the device further comprises an adjusting module configured to, after starting the second-stage compressor, acquire a temperature change rate of a target space of the multi-stage cascade refrigeration and heating device; when the temperature change rate is less than a preset temperature threshold, increase a frequency of the second-stage compressor.

[0009] As an optional example, the device further comprises a processing module configured to, when the temperature change rate is less than the preset temperature threshold, in the process of increasing the frequency of the second-stage compressor, maintain a current frequency of the second-stage compressor when the frequency of the second-stage compressor reaches a preset maximum value, or maintain the current frequency of the second-stage compressor when the temperature change rate reaches the preset temperature threshold.

[0010] As an optional example, the device further comprises a control module configured to, when the temperature change rate is less than the preset temperature threshold, in the process of increasing the frequency of the second-stage compressor, maintain a current frequency of the second-stage compressor when the temperature change rate is greater than the preset temperature threshold, or decrease the current frequency of the second-stage compressor.

[0011] As an optional example, the multi-stage cascade refrigeration and heating device is a device for refrigeration, the first-stage compressor is a refrigeration compressor configured to refrigerate the second-stage compressor, the second-stage compressor is a refrigeration compressor configured to refrigerate a target space of the multi-stage cascade refrigeration and heating device, the compressor frequency of the second-stage compressor is greater than the compressor frequency of the first-stage compressor, or the refrigeration efficiency of the second-stage compressor is greater than the refrigeration efficiency of the first-stage compressor.

[0012] As an optional example, the multi-stage cascade refrigeration and heating device is a device for heating, the first-stage compressor is a heating compressor configured to heat the second-stage compressor, the second-stage compressor is a heating compressor configured to heat a target space of the multi-stage cascade refrigeration and heating device, the compressor frequency of the second-stage compressor is greater than the compressor frequency of the first-stage compressor, or the heating efficiency of the second-stage compressor is greater than the heating efficiency of the first-stage compressor.

[0013] In a third aspect, the present application provides a multi-stage cascade refrigeration and heating system, comprising: a first determining module, configured to determine a pressure change rate of a first-stage compressor after the first-stage compressor of a multi-stage cascade refrigeration and heating device is started, wherein the multi-stage cascade refrigeration and heating device comprises at least the first-stage compressor and a second-stage compressor; a second determining module, configured to determine a starting time of the second-stage compressor according to the pressure change rate; and a starting module, configured to start the second-stage compressor when the starting time of the second-stage compressor is met.

[0014] In a fourth aspect, the present application provides an electronic device, comprising: at least one communication interface; at least one bus connected with the at least one communication interface; at least one processor connected with the at least one bus; and at least one memory connected with the at least one bus, wherein the memory stores a computer program, and the processor is configured to execute the computer program to implement the multi-stage cascade refrigeration and heating method.

[0015] In a fifth aspect, the present application further provides a computer storage medium, which stores computer executable instructions, and the computer executable instructions are used to execute the multi-stage cascade refrigeration and heating method.

[0016] Compared with the prior art, the technical solution provided by the embodiments of the present application has the following advantages: the scheme provided by the embodiments of the present application determines the pressure change rate of the first-stage compressor after the first-stage compressor of the multi-stage cascade refrigeration and heating device is started, wherein the multi-stage cascade refrigeration and heating device comprises at least the first-stage compressor and the second-stage compressor; determines the starting time of the second-stage compressor according to the pressure change rate; and starts the second-stage compressor when the starting time of the second-stage compressor is met, so that the starting time of the second-stage compressor can be determined according to the pressure change rate of the first-stage compressor, the accuracy of the starting time of the second-stage compressor is improved, the problem that the second-stage compressor is not started after the second-stage compressor is started is solved, and the stability of the multi-stage cascade refrigeration and heating device is improved. BRIEF DESCRIPTION OF DRAWINGS

[0017] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate embodiments consistent with the present application and, together with the description, further serve to explain the principles of the application.

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0020] Figure 1 A flowchart of a multi-stage cascade refrigeration and heating method provided in this application embodiment;

[0021] Figure 2 A refrigeration diagram of a two-stage cascade refrigeration and heating device provided in an embodiment of this application;

[0022] Figure 3 A refrigeration diagram of a three-stage cascade refrigeration and heating device provided in this application embodiment;

[0023] Figure 4 A cooling air heat exchange diagram of a two-stage cascade refrigeration and heating device provided in this application embodiment;

[0024] Figure 5 A diagram illustrating the cooling air heat exchange of another two-stage cascade refrigeration and heating device provided in this application embodiment;

[0025] Figure 6 A flowchart of a two-stage cascade refrigeration and heating method provided in this application embodiment;

[0026] Figure 7 This is a schematic diagram of the structure of a multi-stage cascade refrigeration and heating device provided in an embodiment of this application;

[0027] Figure 8 This is a schematic diagram of an electronic device provided in an embodiment of this application. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0029] The following disclosure provides numerous different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of the invention. Furthermore, reference numerals and / or letters may be repeated in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed.

[0030] To address the technical problem of compressor tripping in existing two-stage cascade systems, this application provides a multi-stage cascade refrigeration and heating method that can improve the stability of multi-stage cascade refrigeration and heating devices.

[0031] Figure 1 A flowchart illustrating a multi-stage cascade cooling and heating method provided in an embodiment of this application. Figure 1 As shown, the above-mentioned multi-stage cascade refrigeration and heating method includes:

[0032] S102, after the first stage compressor of the multi-stage cascade refrigeration and heating device is started, the pressure change rate of the first stage compressor is determined, wherein the multi-stage cascade refrigeration and heating device includes at least the first stage compressor and the second stage compressor.

[0033] S104. Based on the aforementioned pressure change rate, determine the start-up timing of the second-stage compressor.

[0034] S106, when the starting timing of the second-stage compressor is met, the second-stage compressor is started.

[0035] Optionally, the multi-stage cascade refrigeration and heating device in this embodiment can be a two-stage cascade refrigeration and heating device, or a three-stage or more-stage cascade refrigeration and heating device. The multi-stage cascade refrigeration and heating device can be a device for refrigeration, where the first-stage compressor is a refrigeration compressor used to refrigerate the second-stage compressor, and the second-stage compressor is a refrigeration compressor used to refrigerate the target space of the multi-stage cascade refrigeration and heating device. The compressor frequency of the second-stage compressor is greater than that of the first-stage compressor, or the refrigeration efficiency of the second-stage compressor is greater than that of the first-stage compressor. Alternatively, the multi-stage cascade refrigeration and heating device can be a device for heating, where the first-stage compressor is a heating compressor used to heat the second-stage compressor, and the second-stage compressor is a heating compressor used to heat the target space of the multi-stage cascade refrigeration and heating device. The compressor frequency of the second-stage compressor is greater than that of the first-stage compressor, or the heating efficiency of the second-stage compressor is greater than that of the first-stage compressor.

[0036] For example, taking a bipolar cascade refrigeration system as an example, a bipolar cascade refrigeration system includes two compressors. One compressor starts first, responsible for generating a certain amount of cold air. The heat generated during the cold air generation process is discharged outdoors. The second compressor starts when the starting conditions are met. The second compressor uses the cold air from the first compressor to refrigerate the air, discharging the cooled air into the room. The heat generated during the refrigeration process is given to the first compressor to cool the hot air. Figure 2 As shown. Figure 2 In this system, the first-stage compressor delivers cold air to the second-stage compressor during the cooling process, while delivering the hot air generated during the cooling process to the outside. The cold air delivered to the second-stage compressor is used for further cooling, thereby lowering the indoor temperature. The hot air generated during the cooling process of the second-stage compressor is then delivered to the first-stage compressor, allowing the first-stage compressor to cool the hot air and produce cold air.

[0037] If it is a multi-stage cascade refrigeration and heating system, taking a three-stage cascade refrigeration and heating system as an example, then as follows: Figure 3 As shown. The first-stage compressor provides cold air to the second-stage compressor, and the heat generated during the refrigeration process is discharged outdoors. The second-stage compressor uses the cold air provided by the first-stage compressor to refrigerate the room, and the refrigerated air is then supplied to the third-stage compressor. The heat generated during the refrigeration process is then supplied to the first-stage compressor. The third-stage compressor uses the cold air from the second-stage compressor to refrigerate the room, and the heat generated during the refrigeration process is then supplied to the second-stage compressor.

[0038] For multi-stage cascade refrigeration equipment, more compressor stages are added. The core idea is that the compressor in the previous stage provides cold air to the compressor in the next stage, and the compressor in the next stage continues to refrigerate while providing hot air to the compressor in the previous stage.

[0039] If it is a multi-stage cascade heating device, then the structural hierarchy of the device is also as follows: Figure 2 , 3 As shown. The difference is that the heating unit exhausts cold air to the outside, the next stage compressor provides cold air to the previous stage compressor, the previous stage compressor provides hot air to the next stage compressor, and the last stage compressor provides hot air to the room.

[0040] In this embodiment, the air exchange between the multiple compressors in the aforementioned multi-stage cascade refrigeration and heating device can be either air exchange (i.e., air moving between different compressors) or heat exchange (i.e., air not moving between different compressors, but rather cold air and hot air being separated and exchanging heat with each other). For example, taking a two-stage compressor as an example... Figure 4 The diagram shows the exchange of heat between cold air and hot air through a heat-exchangeable medium. Figure 4In this design, the heat-exchangeable medium 402 separates the air in the first-stage compressor from that in the second-stage compressor. Although they can exchange heat, they are not interconnected. This prevents refrigerant leakage between the first-stage and second-stage compressors.

[0041] Figure 5 This is a schematic diagram of heat exchange during the mixing and heat exchange of hot and cold gases between two stages of compressors, as shown below. Figure 5 As shown. 1 is the low-temperature stage compressor (second-stage compressor), 2 is the filter, 3 is the oil separator, 4 is the condenser fan, 5 is the condenser, 6 is the anti-condensation tube, 7 is the high-temperature stage compressor (first-stage compressor), 8 is the filter, 9 is the high-temperature side pressure sensor, 10 is the gas-liquid separator, 11 is the high-temperature side capillary tube, 12 is the intermediate heat exchanger, 13 is the low-temperature side capillary tube, 14 is the evaporator, and 15 is the low-temperature side pressure sensor. The high-temperature, high-pressure gas discharged from the high-temperature stage compressor 7 flows through the condenser 5 to exchange heat with the ambient air and is condensed. Then, it passes through the anti-condensation tube 6 and enters the high-temperature side capillary tube 11 for throttling before entering the intermediate heat exchanger 12. The high-temperature, high-pressure gas discharged from the low-temperature stage compressor 1 flows through the condenser 5 to exchange heat with the refrigerant from the high-temperature side circuit and is condensed. Next, the refrigerant passes through the oil separator 3 to separate most of the oil, passes through the filter 2, and enters the intermediate heat exchanger 12. Simultaneously, the high-temperature refrigerant utilizes its low temperature within the intermediate heat exchanger 12 to exchange heat with the low-temperature refrigerant, further reducing its temperature. The refrigerant in the high-temperature side loop continues to flow through the gas-liquid separator 10 before returning to the high-temperature stage compressor, completing the high-temperature side loop cycle. In the low-temperature side loop, the refrigerant continues to operate after passing through the intermediate heat exchanger 12, undergoes throttling through the capillary tube 13, and then passes through the evaporator 14 to cool the compartment. Afterward, the refrigerant returns to the low-temperature stage compressor, completing the low-temperature side loop cycle. At this point, the system completes one refrigeration cycle.

[0042] Continuing with the example of a two-stage cascade device, in this embodiment, upon receiving a cooling / heating task, the first-stage compressor is first started, operating to perform cooling or heating. During operation, the pressure of the first-stage compressor changes; the rate of pressure change indicates the speed at which the compressor's pressure rises. A higher rate of pressure change indicates a faster pressure rise. The starting timing of the second-stage compressor is determined based on the magnitude of the pressure change rate. For example, if the pressure change rate is relatively fast, it indicates that the pressure in the first-stage compressor is relatively high. If the second-stage compressor is started at this time, the pressure in the first-stage compressor will be even higher, potentially causing it to trip. Therefore, the starting time of the second-stage compressor should be delayed. If the pressure change rate of the first-stage compressor is relatively slow, it indicates that the pressure in the first-stage compressor is relatively low, and the starting time of the second-stage compressor can be advanced.

[0043] In this embodiment, the second-stage compressor can be started when the start-up timing for the second-stage compressor is met. There are several possible start-up timings for the second-stage compressor. For example, the pressure of the first-stage compressor may be low, the temperature in the space containing the two-stage cascade device may be decreasing rapidly, or the first-stage compressor may be in a stable state. As an example, a default start-up interval can be set between the first-stage and second-stage compressors. Then, this default start-up interval can be adjusted according to the pressure change rate of the first-stage compressor. The adjusted default start-up interval is used as the start-up condition. After the first-stage compressor is started, the start-up condition for the second-stage compressor is considered to have been met after the adjusted default start-up interval.

[0044] For example, after the first-stage compressor starts, the second-stage compressor is originally scheduled to start after 1 minute. However, in this embodiment, the 1 minute interval is adjusted according to the pressure change rate of the first-stage compressor, either by extending or shortening the interval. For example, if it is changed to 1 minute and 20 seconds, then the second-stage compressor starts at 1 minute and 20 seconds after the first-stage compressor starts.

[0045] The solution provided in this application, after starting the first-stage compressor of the multi-stage cascade refrigeration and heating device, determines the pressure change rate of the first-stage compressor, wherein the multi-stage cascade refrigeration and heating device includes at least the first-stage compressor and a second-stage compressor; based on the pressure change rate, the starting time of the second-stage compressor is determined; when the starting time of the second-stage compressor is met, the second-stage compressor is started. This improves the accuracy of the starting time of the second-stage compressor by determining the pressure change rate of the first-stage compressor, ensuring that the second-stage compressor does not trip after starting, and thus improving the stability of the multi-stage cascade refrigeration and heating device.

[0046] As an optional example, determining the start-up timing of the second-stage compressor based on the pressure change rate includes: obtaining the first start-up time and default start-up interval of the first-stage compressor; increasing the duration of the default start-up interval when the pressure change rate exceeds a preset pressure threshold, and determining the second start-up timing of the second-stage compressor according to the increased default start-up interval; and decreasing the duration of the default start-up interval when the pressure change rate is less than the preset pressure threshold, and determining the second start-up timing of the second-stage compressor according to the decreased default start-up interval.

[0047] In this embodiment, a preset pressure threshold can be set, representing an acceptable rate of pressure change. If the rate of pressure change in the first-stage compressor exceeds this preset threshold after startup, the pressure change in the first-stage compressor is considered too rapid. In this case, the startup time of the second-stage compressor can be extended, allowing the first-stage compressor room to reduce pressure. Conversely, if the rate of pressure change in the first-stage compressor is less than this preset threshold after startup, the pressure change in the first-stage compressor is considered slow. In this case, the startup time of the second-stage compressor can be shortened, appropriately accelerating the startup speed of the second-stage compressor without causing excessive pressure change in the first-stage compressor.

[0048] It should be noted that the aforementioned pressure preset threshold can also be a range, which includes a left range value and a right range value. If the pressure change rate of the first-stage compressor is less than the left range value, the default start interval can be shortened. If the pressure change rate of the first-stage compressor is greater than the right and left range values, the default start interval can be extended. If the pressure change rate of the first-stage compressor is within the range, the default start interval can be kept unchanged.

[0049] As an optional example, after starting the second-stage compressor, the method further includes: obtaining the temperature change rate of the target space of the multi-stage cascade refrigeration and heating device; and increasing the frequency of the second-stage compressor when the temperature change rate is less than a preset temperature threshold.

[0050] In this embodiment, after the first-stage compressor starts, the pressure change rate of the first-stage compressor is obtained. The starting time of the second-stage compressor is determined based on this pressure change rate. After the second-stage compressor starts, the temperature change rate of the target space can also be obtained. If the refrigeration / heating equipment is an air conditioner or similar device, the target space is the space where the refrigeration / heating device is located, such as indoors, in a factory area, or in a room. If the refrigeration / heating device is a refrigerator, the target space is the interior of the refrigerator. The temperature change within the target space is measured by the rate of temperature change. The temperature change within the target space is caused by the operation of the second-stage compressor.

[0051] This embodiment allows for the preset temperature threshold, which specifies the rate at which the temperature within the target space should change. For example, a preset temperature threshold of 30 indicates that the temperature within the target space should increase or decrease by 30 degrees Celsius per unit time (e.g., 1 minute, 10 minutes, or 1 hour). If the temperature does not increase or decrease by 30 degrees Celsius, it indicates that the rate of temperature change within the target space is insufficient. In this case, it is necessary to increase the frequency of the second-stage compressor to accelerate the rate of temperature change within the target space.

[0052] As an optional example, when the temperature change rate is less than the preset temperature threshold, during the process of increasing the frequency of the second-stage compressor, the method further includes: maintaining the current frequency of the second-stage compressor when the frequency of the second-stage compressor reaches the preset maximum value; or, maintaining the current frequency of the second-stage compressor when the temperature change rate reaches the preset temperature threshold.

[0053] In this embodiment, after the second-stage compressor starts, the temperature change rate of the target space is acquired. If the temperature change rate is less than a preset temperature threshold, the frequency of the second-stage compressor is increased to improve its operating efficiency. However, if the frequency of the second-stage compressor is increased, it is also checked whether the frequency has reached a preset maximum value. If the frequency of the second-stage compressor has reached the preset maximum value, the frequency increase is stopped. This is to prevent the second-stage compressor from tripping due to excessively high frequency and pressure. The aforementioned preset maximum value is the frequency value that keeps the second-stage compressor operating normally without tripping; if this value is exceeded, the second-stage compressor may trip.

[0054] Furthermore, in this embodiment, to ensure that the pressure of the second-stage compressor is not too high, when the temperature change rate is less than a preset temperature threshold, if the temperature change rate reaches the preset temperature threshold when the frequency of the second-stage compressor is increased, the frequency increase of the second-stage compressor must be stopped. At this point, the second-stage compressor can be considered to be in a stable state, and the temperature change rate meets the requirements.

[0055] As an optional example, when the temperature change rate is less than a preset temperature threshold, during the process of increasing the frequency of the second-stage compressor, the method further includes: when the temperature change rate is greater than the preset temperature threshold, maintaining the current frequency of the second-stage compressor or reducing the current frequency of the second-stage compressor.

[0056] In this embodiment, when the temperature change rate is less than the preset temperature threshold, if the temperature change rate exceeds the preset temperature threshold during the process of increasing the frequency of the second-stage compressor, the increase in the frequency of the second-stage compressor can be stopped, the frequency can be kept constant, or the frequency can be decreased until the temperature change rate equals the preset temperature threshold.

[0057] In addition, the preset temperature threshold in this embodiment can also be a temperature range, which includes a left temperature range and a right temperature range. When the temperature change rate is less than that of the left temperature range, the frequency of the second-stage compressor is increased. When the temperature change rate is within the temperature range, the frequency of the second-stage compressor is kept constant. When the temperature change rate is greater than that of the right temperature range, the frequency of the second-stage compressor is decreased.

[0058] Continuing with the example of a two-stage cascade refrigeration system, the high-temperature stage compressor (first-stage compressor) starts first. After the high-temperature stage compressor has been running for a period of time, the low-temperature stage compressor (second-stage compressor) starts. The purpose is to ensure that the high-temperature side circuit in the condenser can provide a certain amount of cooling capacity beforehand. This prevents the low-temperature stage compressor from tripping due to excessively high condensing pressure caused by the refrigerant in the low-temperature side circuit after startup. Therefore, the start-stop interval between the high-temperature and low-temperature stage compressors is crucial. If the interval is too short, the cooling capacity provided by the high-temperature side circuit in the condenser will be insufficient, resulting in excessively high condensing pressure of the refrigerant on the low-temperature side, causing the low-temperature stage compressor to trip. If the interval is too long, the cooling capacity provided by the high-temperature side circuit in the condenser will be excessive, causing a large amount of refrigerant to accumulate in the condenser, reducing the refrigerant in the low-temperature system and resulting in a slow cooling rate. The compressor start-stop optimization and control process provided in this embodiment allows the starting timing of the second-stage compressor to be determined based on the pressure change rate of the first-stage compressor after the first-stage compressor starts. This ensures that the second-stage compressor starts at the appropriate time and avoids the tripping phenomenon between the first-stage and second-stage compressors.

[0059] Figure 6 This is a flowchart of this embodiment. Taking refrigeration as an example, as follows... Figure 6As shown, in this embodiment, the system simultaneously monitors the temperature T of the target area and the pressure P within both compressor loops, thereby calculating the cooling rate Vt and the pressure increase rate VP per unit time. The system can automatically adjust according to the actual ambient temperature, or the operator can manually adjust the predetermined temperature threshold V0 and the predetermined frequency threshold H0 according to actual needs. During the system startup phase, the system monitors the internal pressure Pg of the high-temperature side loop in real time based on the pressure sensor 8, and calculates the pressure increase rate Vg1 within the high-temperature side loop. When Vg1 is greater than the set threshold Vg0 of the high-temperature side loop, the system increases the startup interval of the low-temperature stage compressor by t1, increasing the cooling time of the high-temperature stage compressor to alleviate the pressure on the high-temperature side loop. During the stable operation phase, when the actual cooling rate Vt of the compartment is detected to be less than the predetermined temperature threshold V0, and the compressor frequency has not reached the highest frequency, the system controls the compressor to increase its frequency to pull up the temperature (this can be the second-stage compressor increasing its frequency, or the first-stage compressor and the second-stage compressor increasing their frequencies simultaneously), until Vt ≥ V0 or the compressor has reached the highest frequency, at which point the compressor stops increasing its frequency and operates at the current frequency. If, during operation, the system detects that the pressure rise rate Vp in the circuit exceeds the set threshold Vp0, or even if the pressure rise rate Vp does not reach the set threshold Vp0 within a short period but the system pressure itself may be high, a shutdown may occur. In this case, the system will determine, based on the cooling rate Vt, that the pressure P in the pipeline of the first-stage or second-stage compressor will reach the pressure threshold P0 before shutdown. The system will then temporarily reduce the frequency of the corresponding compressor to decrease the pipeline pressure, prioritizing normal system operation and preventing shutdowns. When the ambient temperature is low or the load is light, the system lowers the predetermined temperature threshold V0 and controls the compressor to operate at a lower frequency to prevent excessive cooling due to excessive cooling capacity per unit time, resulting in short compressor start-up times, frequent compressor starts and stops, increased power consumption, and reduced compressor lifespan. When the ambient temperature is high or the load is heavy, the system raises the predetermined temperature threshold V0 and increases the compressor frequency to meet cooling requirements.

[0060] Figure 7 This is a schematic diagram of a multi-stage cascade cooling and heating device provided in an embodiment of this application. Figure 7 As shown, the above-mentioned multi-stage cascade refrigeration and heating device includes:

[0061] The first determining module 702 is used to determine the pressure change rate of the first-stage compressor after the first-stage compressor of the multi-stage cascade refrigeration and heating device is started, wherein the multi-stage cascade refrigeration and heating device includes at least a first-stage compressor and a second-stage compressor.

[0062] The second determining module 704 is used to determine the start-up timing of the second-stage compressor based on the pressure change rate.

[0063] The starting module 706 is used to start the second-stage compressor when the starting timing of the second-stage compressor is met.

[0064] Optionally, the multi-stage cascade refrigeration and heating device in this embodiment can be a two-stage cascade refrigeration and heating device, or a three-stage or more-stage cascade refrigeration and heating device. The multi-stage cascade refrigeration and heating device can be a device for refrigeration, where the first-stage compressor is a refrigeration compressor used to refrigerate the second-stage compressor, and the second-stage compressor is a refrigeration compressor used to refrigerate the target space of the multi-stage cascade refrigeration and heating device. The compressor frequency of the second-stage compressor is greater than that of the first-stage compressor, or the refrigeration efficiency of the second-stage compressor is greater than that of the first-stage compressor. Alternatively, the multi-stage cascade refrigeration and heating device can be a device for heating, where the first-stage compressor is a heating compressor used to heat the second-stage compressor, and the second-stage compressor is a heating compressor used to heat the target space of the multi-stage cascade refrigeration and heating device. The compressor frequency of the second-stage compressor is greater than that of the first-stage compressor, or the heating efficiency of the second-stage compressor is greater than that of the first-stage compressor.

[0065] For example, taking a bipolar cascade refrigeration system as an example, a bipolar cascade refrigeration system includes two compressors. One compressor starts first, responsible for generating a certain amount of cold air. The heat generated during the cold air generation process is discharged outdoors. The second compressor starts when the starting conditions are met. The second compressor uses the cold air from the first compressor to refrigerate the air, discharging the cooled air into the room. The heat generated during the refrigeration process is given to the first compressor to cool the hot air. Figure 2 As shown. Figure 2 In this system, the first-stage compressor delivers cold air to the second-stage compressor during the cooling process, while delivering the hot air generated during the cooling process to the outside. The cold air delivered to the second-stage compressor is used for further cooling, thereby lowering the indoor temperature. The hot air generated during the cooling process of the second-stage compressor is then delivered to the first-stage compressor, allowing the first-stage compressor to cool the hot air and produce cold air.

[0066] If it is a multi-stage cascade refrigeration and heating system, taking a three-stage cascade refrigeration and heating system as an example, then as follows: Figure 3 As shown. The first-stage compressor provides cold air to the second-stage compressor, and the heat generated during the refrigeration process is discharged outdoors. The second-stage compressor uses the cold air provided by the first-stage compressor to refrigerate the room, and the refrigerated air is then supplied to the third-stage compressor. The heat generated during the refrigeration process is then supplied to the first-stage compressor. The third-stage compressor uses the cold air from the second-stage compressor to refrigerate the room, and the heat generated during the refrigeration process is then supplied to the second-stage compressor.

[0067] For multi-stage cascade refrigeration equipment, more compressor stages are added. The core idea is that the compressor in the previous stage provides cold air to the compressor in the next stage, and the compressor in the next stage continues to refrigerate while providing hot air to the compressor in the previous stage.

[0068] If it is a multi-stage cascade heating device, then the structural hierarchy of the device is also as follows: Figure 2 , 3 As shown. The difference is that the heating unit exhausts cold air to the outside, the next stage compressor provides cold air to the previous stage compressor, the previous stage compressor provides hot air to the next stage compressor, and the last stage compressor provides hot air to the room.

[0069] In this embodiment, the air exchange between the multiple compressors in the aforementioned multi-stage cascade refrigeration and heating device can be either air exchange (i.e., air moving between different compressors) or heat exchange (i.e., air not moving between different compressors, but rather cold air and hot air being separated and exchanging heat with each other). For example, taking a two-stage compressor as an example... Figure 4 The diagram shows the exchange of heat between cold air and hot air through a heat-exchangeable medium. Figure 4 In this design, the heat-exchangeable medium 402 separates the air in the first-stage compressor from that in the second-stage compressor. Although they can exchange heat, they are not interconnected. This prevents refrigerant leakage between the first-stage and second-stage compressors.

[0070] Figure 5 This is a schematic diagram of heat exchange during the mixing and heat exchange of hot and cold gases between two stages of compressors, as shown below. Figure 5As shown. 1 is the low-temperature stage compressor (second-stage compressor), 2 is the filter, 3 is the oil separator, 4 is the condenser fan, 5 is the condenser, 6 is the anti-condensation tube, 7 is the high-temperature stage compressor (first-stage compressor), 8 is the filter, 9 is the high-temperature side pressure sensor, 10 is the gas-liquid separator, 11 is the high-temperature side capillary tube, 12 is the intermediate heat exchanger, 13 is the low-temperature side capillary tube, 14 is the evaporator, and 15 is the low-temperature side pressure sensor. The high-temperature, high-pressure gas discharged from the high-temperature stage compressor 7 flows through the condenser 5 to exchange heat with the ambient air and is condensed. Then, it passes through the anti-condensation tube 6 and enters the high-temperature side capillary tube 11 for throttling before entering the intermediate heat exchanger 12. The high-temperature, high-pressure gas discharged from the low-temperature stage compressor 1 flows through the condenser 5 to exchange heat with the refrigerant from the high-temperature side circuit and is condensed. Next, the refrigerant passes through the oil separator 3 to separate most of the oil, passes through the filter 2, and enters the intermediate heat exchanger 12. Simultaneously, the high-temperature refrigerant utilizes its low temperature within the intermediate heat exchanger 12 to exchange heat with the low-temperature refrigerant, further reducing its temperature. The refrigerant in the high-temperature side loop continues to flow through the gas-liquid separator 10 before returning to the high-temperature stage compressor, completing the high-temperature side loop cycle. In the low-temperature side loop, the refrigerant continues to operate after passing through the intermediate heat exchanger 12, undergoes throttling through the capillary tube 13, and then passes through the evaporator 14 to cool the compartment. Afterward, the refrigerant returns to the low-temperature stage compressor, completing the low-temperature side loop cycle. At this point, the system completes one refrigeration cycle.

[0071] Continuing with the example of a two-stage cascade device, in this embodiment, upon receiving a cooling / heating task, the first-stage compressor is first started, operating to perform cooling or heating. During operation, the pressure of the first-stage compressor changes; the rate of pressure change indicates the speed at which the compressor's pressure rises. A higher rate of pressure change indicates a faster pressure rise. The starting timing of the second-stage compressor is determined based on the magnitude of the pressure change rate. For example, if the pressure change rate is relatively fast, it indicates that the pressure in the first-stage compressor is relatively high. If the second-stage compressor is started at this time, the pressure in the first-stage compressor will be even higher, potentially causing it to trip. Therefore, the starting time of the second-stage compressor should be delayed. If the pressure change rate of the first-stage compressor is relatively slow, it indicates that the pressure in the first-stage compressor is relatively low, and the starting time of the second-stage compressor can be advanced.

[0072] In this embodiment, the second-stage compressor can be started when the start-up timing for the second-stage compressor is met. There are several possible start-up timings for the second-stage compressor. For example, the pressure of the first-stage compressor may be low, the temperature in the space containing the two-stage cascade device may be decreasing rapidly, or the first-stage compressor may be in a stable state. As an example, a default start-up interval can be set between the first-stage and second-stage compressors. Then, this default start-up interval can be adjusted according to the pressure change rate of the first-stage compressor. The adjusted default start-up interval is used as the start-up condition. After the first-stage compressor is started, the start-up condition for the second-stage compressor is considered to have been met after the adjusted default start-up interval.

[0073] For example, after the first-stage compressor starts, the second-stage compressor is originally scheduled to start after 1 minute. However, in this embodiment, the 1 minute interval is adjusted according to the pressure change rate of the first-stage compressor, either by extending or shortening the interval. For example, if it is changed to 1 minute and 20 seconds, then the second-stage compressor starts at 1 minute and 20 seconds after the first-stage compressor starts.

[0074] The solution provided in this application, after starting the first-stage compressor of the multi-stage cascade refrigeration and heating device, determines the pressure change rate of the first-stage compressor, wherein the multi-stage cascade refrigeration and heating device includes at least the first-stage compressor and a second-stage compressor; based on the pressure change rate, the starting time of the second-stage compressor is determined; when the starting time of the second-stage compressor is met, the second-stage compressor is started. This improves the accuracy of the starting time of the second-stage compressor by determining the pressure change rate of the first-stage compressor, ensuring that the second-stage compressor does not trip after starting, and thus improving the stability of the multi-stage cascade refrigeration and heating device.

[0075] For other examples of this embodiment, please refer to the examples above, which will not be repeated here.

[0076] This application also provides a multi-stage cascade cooling and heating system, including:

[0077] The first determining module is used to determine the pressure change rate of the first-stage compressor after the first-stage compressor of the multi-stage cascade refrigeration and heating device is started, wherein the multi-stage cascade refrigeration and heating device includes at least the first-stage compressor and the second-stage compressor.

[0078] The second determining module is used to determine the start-up timing of the second-stage compressor based on the pressure change rate mentioned above.

[0079] The starting module is used to start the second-stage compressor when the starting timing of the second-stage compressor is met.

[0080] For other examples of this embodiment, please refer to the examples above, which will not be repeated here.

[0081] like Figure 8 As shown in the figure, this application provides an electronic device, including a processor 111, a communication interface 112, a memory 113, and a communication bus 114, wherein the processor 111, the communication interface 112, and the memory 113 communicate with each other through the communication bus 114.

[0082] Memory 113 is used to store computer programs;

[0083] In one embodiment of this application, the processor 111, when executing the program stored in the memory 113, implements the multi-stage cascade cooling and heating method provided in any of the aforementioned method embodiments.

[0084] This application also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the multi-stage cascade cooling and heating method provided in any of the foregoing method embodiments.

[0085] The device embodiments described above are merely illustrative. 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 modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0086] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented using software plus a general-purpose hardware platform, or of course, using hardware. Based on this understanding, the above technical solutions, in essence or the parts that contribute to the related technology, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0087] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also include the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a particular order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0088] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A multi-stage cascade refrigeration and heating method, characterized in that, include: After the first-stage compressor of the multi-stage cascade refrigeration and heating device is started, the pressure change rate of the first-stage compressor is determined, wherein the multi-stage cascade refrigeration and heating device includes at least the first-stage compressor and the second-stage compressor; The start-up timing of the second-stage compressor is determined based on the pressure change rate. When the start-up timing of the second-stage compressor is met, the second-stage compressor is started; The step of determining the start-up timing of the second-stage compressor based on the pressure change rate includes: obtaining the first start-up time and default start-up interval of the first-stage compressor; increasing the duration of the default start-up interval when the pressure change rate exceeds a preset pressure threshold, and determining the second start-up timing of the second-stage compressor according to the increased default start-up interval; and decreasing the duration of the default start-up interval when the pressure change rate is less than the preset pressure threshold, and determining the second start-up timing of the second-stage compressor according to the decreased default start-up interval. Wherein, when the multi-stage cascade refrigeration and heating device is a device for refrigeration, the first stage compressor is a refrigeration compressor used to refrigerate the second stage compressor, the second stage compressor is a refrigeration compressor used to refrigerate the target space of the multi-stage cascade refrigeration and heating device, the compressor frequency of the second stage compressor is greater than the compressor frequency of the first stage compressor, or the refrigeration efficiency of the second stage compressor is greater than the refrigeration efficiency of the first stage compressor.

2. The method according to claim 1, characterized in that, After starting the second-stage compressor, the method further includes: Obtain the temperature change rate of the target space in the multi-stage cascaded cooling and heating device; When the rate of temperature change is less than a preset temperature threshold, the frequency of the second-stage compressor is increased.

3. The method according to claim 2, characterized in that, When the rate of temperature change is less than a preset temperature threshold, the method further includes increasing the frequency of the second-stage compressor during the process of increasing the frequency of the second-stage compressor: When the frequency of the second-stage compressor reaches the preset maximum value, maintain the current frequency of the second-stage compressor; or, When the rate of temperature change reaches the preset temperature threshold, the second-stage compressor continues to operate at its current frequency.

4. The method according to claim 2, characterized in that, When the rate of temperature change is less than a preset temperature threshold, the method further includes increasing the frequency of the second-stage compressor during the process of increasing the frequency of the second-stage compressor: When the rate of temperature change exceeds the preset temperature threshold, the second-stage compressor is maintained at its current frequency or its current frequency is reduced.

5. The method according to claim 1, characterized in that, When the multi-stage cascade refrigeration and heating device is a device for heating, the first stage compressor is a heating compressor used to heat the second stage compressor, the second stage compressor is a heating compressor used to heat the target space of the multi-stage cascade refrigeration and heating device, the compressor frequency of the second stage compressor is greater than the compressor frequency of the first stage compressor, or the heating efficiency of the second stage compressor is greater than the heating efficiency of the first stage compressor.

6. A multi-stage cascade refrigeration and heating device, characterized in that, include: The first determining module is used to determine the pressure change rate of the first-stage compressor after the first-stage compressor of the multi-stage cascade refrigeration and heating device is started, wherein the multi-stage cascade refrigeration and heating device includes at least the first-stage compressor and the second-stage compressor. The second determining module is used to determine the start-up timing of the second-stage compressor based on the pressure change rate. The starting module is used to start the second-stage compressor when the starting timing of the second-stage compressor is met; The step of determining the start-up timing of the second-stage compressor based on the pressure change rate includes: obtaining the first start-up time and default start-up interval of the first-stage compressor; increasing the duration of the default start-up interval when the pressure change rate exceeds a preset pressure threshold, and determining the second start-up timing of the second-stage compressor according to the increased default start-up interval; and decreasing the duration of the default start-up interval when the pressure change rate is less than the preset pressure threshold, and determining the second start-up timing of the second-stage compressor according to the decreased default start-up interval. Wherein, when the multi-stage cascade refrigeration and heating device is a device for refrigeration, the first stage compressor is a refrigeration compressor used to refrigerate the second stage compressor, the second stage compressor is a refrigeration compressor used to refrigerate the target space of the multi-stage cascade refrigeration and heating device, the compressor frequency of the second stage compressor is greater than the compressor frequency of the first stage compressor, or the refrigeration efficiency of the second stage compressor is greater than the refrigeration efficiency of the first stage compressor.

7. A multi-stage cascade refrigeration and heating system, characterized in that, include: The first determining module is used to determine the pressure change rate of the first-stage compressor after the first-stage compressor of the multi-stage cascade refrigeration and heating device is started, wherein the multi-stage cascade refrigeration and heating device includes at least the first-stage compressor and the second-stage compressor. The second determining module is used to determine the start-up timing of the second-stage compressor based on the pressure change rate. The starting module is used to start the second-stage compressor when the starting timing of the second-stage compressor is met; The step of determining the start-up timing of the second-stage compressor based on the pressure change rate includes: obtaining the first start-up time and default start-up interval of the first-stage compressor; increasing the duration of the default start-up interval when the pressure change rate exceeds a preset pressure threshold, and determining the second start-up timing of the second-stage compressor according to the increased default start-up interval; and decreasing the duration of the default start-up interval when the pressure change rate is less than the preset pressure threshold, and determining the second start-up timing of the second-stage compressor according to the decreased default start-up interval. Wherein, when the multi-stage cascade refrigeration and heating device is a device for refrigeration, the first stage compressor is a refrigeration compressor used to refrigerate the second stage compressor, the second stage compressor is a refrigeration compressor used to refrigerate the target space of the multi-stage cascade refrigeration and heating device, the compressor frequency of the second stage compressor is greater than the compressor frequency of the first stage compressor, or the refrigeration efficiency of the second stage compressor is greater than the refrigeration efficiency of the first stage compressor.

8. An electronic device, characterized in that, include: At least one communication interface; At least one bus connected to the at least one communication interface; At least one processor connected to the at least one bus; At least one memory connected to the at least one bus, wherein the memory stores a computer program, and the processor executes the computer program to implement the multi-stage cascade cooling and heating method according to any one of claims 1 to 5.

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