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

Abstract

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

Description

Technical Field

[0001] The present application relates to the field of refrigeration and heating, and in particular to a multi-stage cascade refrigeration and heating method, device, storage medium and electronic equipment. Background Art

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

[0003] However, in the prior art, the startup of the two-stage cascade refrigeration system is generally to preset a startup interval, then start the first stage compressor first, and then start the second stage compressor after reaching the startup interval. This startup method has a fixed startup interval between the two compressors, which is not accurate. After the second stage compressor is started, it is easy to cause the compressor to trip due to high pressure. Summary of the invention

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

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

[0006] In a second aspect, the present application provides a multi-stage cascade refrigeration and heating device, comprising: a first determination module, 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; a second determination module, used to determine the start-up timing of the second-stage compressor based on the pressure change rate; a start-up module, used to start the second-stage compressor when the start-up timing of the second-stage compressor is met.

[0007] As an optional example, the second determination module includes: a determination unit for obtaining the first start time and the default start interval of the first-stage compressor; when the pressure change rate exceeds the preset pressure threshold, increasing the duration of the default start interval, and determining the second start time of the second-stage compressor according to the increased default start interval; when the pressure change rate is less than the preset pressure threshold, reducing the duration of the default start interval, and determining the second start time of the second-stage compressor according to the reduced default start interval.

[0008] As an optional example, the above-mentioned device also includes: an adjustment module, which is used to obtain the temperature change rate of the target space of the above-mentioned multi-stage cascade refrigeration and heating device after starting the above-mentioned second-stage compressor; when the above-mentioned temperature change rate is less than the preset temperature threshold, increasing the frequency of the above-mentioned second-stage compressor.

[0009] As an optional example, the above-mentioned device also includes: a processing module, which is used to maintain the current frequency of the above-mentioned second-stage compressor when the frequency of the above-mentioned second-stage compressor reaches a preset maximum value during the process of increasing the frequency of the above-mentioned second-stage compressor when the temperature change rate is less than the temperature preset threshold value; or, when the temperature change rate reaches the temperature preset threshold value, maintain the current frequency of the above-mentioned second-stage compressor.

[0010] As an optional example, the above-mentioned device also includes: a control module, which is used to maintain the current frequency of the above-mentioned second-stage compressor or reduce the current frequency of the above-mentioned second-stage compressor when the above-mentioned temperature change rate is less than the above-mentioned temperature preset threshold value during the process of increasing the frequency of the above-mentioned second-stage compressor when the above-mentioned temperature change rate is greater than the above-mentioned temperature preset threshold value.

[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 used to refrigerate the second-stage compressor, the second-stage compressor is a refrigeration compressor used to cool 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.

[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, 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.

[0013] In a third aspect, the present application provides a multi-stage cascade refrigeration and heating system, comprising: a first determination module, 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; a second determination module, used to determine the start-up timing of the second-stage compressor according to the pressure change rate; a start-up module, used to start the second-stage compressor when the start-up timing 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 to the at least one communication interface; at least one processor connected to the at least one bus; and at least one memory connected to the at least one bus, wherein the memory stores a computer program, and the processor is configured to implement any one of the multi-stage cascade cooling and heating methods mentioned above when executing the computer program.

[0015] In a fifth aspect, the present application further provides a computer storage medium storing computer executable instructions, wherein the computer executable instructions are used to execute any of the multi-stage cascade cooling and heating methods described above in the present application.

[0016] The above-mentioned technical scheme provided by the embodiment of the present application has the following advantages over the prior art: the scheme provided by the embodiment of the present application, after starting the first-stage compressor of the multi-stage cascade refrigeration and heating device, determines the pressure change rate of the above-mentioned first-stage compressor, wherein the above-mentioned multi-stage cascade refrigeration and heating device at least includes the above-mentioned first-stage compressor and the second-stage compressor; according to the above-mentioned pressure change rate, determines the starting timing of the above-mentioned second-stage compressor; when the starting timing of the above-mentioned second-stage compressor is met, starts the above-mentioned second-stage compressor, so that the starting timing of the second-stage compressor can be determined according to the pressure change rate of the first-stage compressor, thereby improving the accuracy of the starting timing of the second-stage compressor, ensuring that the second-stage compressor will not jump after starting, and improving the stability of the multi-stage cascade refrigeration and heating device. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0019] One or more embodiments are exemplarily described by pictures in the corresponding drawings, and these exemplified descriptions do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0020] Figure 1 A flow chart of a multi-stage cascade cooling and heating method provided in an embodiment of the present application;

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

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

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

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

[0025] Figure 6 A flow chart of a two-stage cascade cooling and heating method provided in an embodiment of the present application;

[0026] Figure 7 A schematic diagram of the structure of a multi-stage cascade cooling and heating device provided in an embodiment of the present application;

[0027] Figure 8 A schematic diagram of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0029] The disclosure below provides many different embodiments or examples to implement different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or letters in different examples. This repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed.

[0030] In order to solve the technical problem of compressor tripping in a two-stage cascade system in the prior art, the present application provides a multi-stage cascade refrigeration and heating method, which can achieve the effect of improving the stability of the multi-stage cascade refrigeration and heating device.

[0031] Figure 1 A flow chart of a multi-stage cascade cooling and heating method provided in an embodiment of the present application. Figure 1 As shown, the multi-stage cascade refrigeration and heating method comprises:

[0032] S102, 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 includes at least the first-stage compressor and a second-stage compressor;

[0033] S104, determining a start time of the second stage compressor according to the pressure change rate;

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

[0035] Optionally, the multi-stage cascade refrigeration and heating device in this embodiment may be a two-stage cascade refrigeration and heating device, or may be a three-stage or even more-stage cascade refrigeration and heating device with two or more stages. The multi-stage cascade refrigeration and heating device may be a device for refrigeration, the first-stage compressor is a refrigeration compressor for refrigerating the second-stage compressor, the second-stage compressor is a refrigeration compressor for refrigerating 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. Or the multi-stage cascade refrigeration and heating device may be a device for heating, the first-stage compressor is a heating compressor for heating the second-stage compressor, the second-stage compressor is a heating compressor for heating 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.

[0036] For example, a bipolar cascade refrigeration device includes two compressors. One compressor starts first. The compressor that starts first is responsible for generating a certain amount of cold air. The hot air generated in the process of generating cold air is discharged to the outside. The second compressor starts when the starting conditions are met. The compressor that starts later uses the cold air of the compressor that starts first to cool the room and discharges the cold air indoors. The hot air generated in the cooling process is given to the first compressor, allowing the first compressor to cool the hot air. Figure 2 shown. Figure 2 In the process, when the first-stage compressor is cooling, it transmits cold air to the second-stage compressor, and transmits the hot air generated in the cooling process to the outside. The cold air transmitted to the second-stage compressor is used for further cooling by the second-stage compressor, thereby reducing the indoor temperature, and the hot air generated in the cooling process of the second-stage compressor is transmitted 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 device, taking a three-stage cascade refrigeration and heating device as an example, then Figure 3 As shown. The first stage compressor provides cold air to the second stage compressor, and the hot air generated during the refrigeration process is discharged to the outside. The second stage compressor uses the cold air provided by the first stage compressor for refrigeration, and the refrigerated cold air is given to the third stage compressor, and the hot air generated during the refrigeration process is given to the first stage compressor. The third stage compressor uses the cold air of the second stage compressor to cool the room, and the generated hot air is given to the second stage compressor.

[0038] If it is a multi-stage cascade refrigeration equipment, more stages of compressors will be added. The core idea is that the upper stage compressor provides cold air to the lower stage compressor, and the lower stage compressor continues to cool and provide hot air to the upper stage compressor.

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

[0040] In this embodiment, the air exchange between the multiple compressors in the above-mentioned multi-stage cascade cooling and heating device can be air exchange, that is, the air moves between different compressors, or heat exchange, that is, the air does not move between different compressors, but the cold air and the hot air are separated and exchange heat with each other. For example, taking a two-stage compressor as an example, Figure 4 The diagram shows the heat exchange between cold air and hot air via a heat exchangeable medium. Figure 4In the embodiment, the heat exchangeable medium 402 can separate the air of the first stage compressor from the air of the second stage compressor, and although the two can exchange heat, they are not intercommunication with each other. In this way, the refrigerant between the first stage compressor and the second stage compressor can be prevented from leaking to each other.

[0041] Figure 5 It is a schematic diagram of the heat exchange of hot and cold gas mixture between two-stage compressors, such as Figure 5 As shown. 1 is a low-temperature compressor (second-stage compressor), 2 is a filter, 3 is an oil separator, 4 is a condensing fan, 5 is a condenser, 6 is an anti-condensation tube, 7 is a high-temperature compressor (first-stage compressor), 8 is a filter, 9 is a high-temperature side pressure sensor, 10 is a gas-liquid separator, 11 is a high-temperature side capillary, 12 is an intermediate heat exchanger, 13 is a low-temperature side capillary, 14 is an evaporator, and 15 is a low-temperature side pressure sensor. The high-temperature and high-pressure gas discharged from the high-temperature compressor 7 flows through the condenser 5 to exchange heat with the ambient air and is condensed, then enters the high-temperature side capillary 11 through the anti-condensation tube 6 for throttling, and enters the intermediate heat exchanger 12. The high-temperature and high-pressure gas discharged from the low-temperature 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. At the same time, the high-temperature side refrigerant uses its own low temperature to exchange heat with the low-temperature side refrigerant in the intermediate heat exchanger 12, further reducing the refrigerant temperature. The refrigerant in the high-temperature side loop continues to flow through the gas-liquid separator 10 and returns to the high-temperature compressor, completing the high-temperature side loop cycle. The refrigerant in the low-temperature side loop continues to run after flowing through the intermediate heat exchanger 12, throttling through the capillary 13, and then cooling the compartment through the evaporator 14, and then the refrigerant returns to the low-temperature compressor, and the low-temperature side loop completes the cycle. At this time, the system completes a refrigeration cycle.

[0042] Continuing with the example of a two-stage cascade device, in this embodiment, when a cooling / heating task is received, the first-stage compressor must first be started, and the first-stage compressor works to cool or heat. Then, during the operation of the first-stage compressor, the pressure will change, and the pressure change rate indicates the pressure rise rate of the compressor. The greater the pressure change rate, the faster the pressure rise rate of the compressor. The start time of the second-stage compressor is determined according to the size of the pressure change rate. For example, if the pressure change rate is relatively fast, it means that the pressure of the first-stage compressor is relatively large. If the second-stage compressor is turned on at this time, the pressure of the first-stage compressor is larger and it is easy to trip. Therefore, the start time of the second-stage compressor should be delayed. If the pressure change rate of the first-stage compressor is relatively slow, it means that the pressure of the first-stage compressor is relatively small. At this time, the start time of the second-stage compressor can be advanced.

[0043] In this embodiment, when the start timing of the second-stage compressor is met, the second-stage compressor can be started. There can be many situations for the start timing of the second-stage compressor. For example, the pressure of the first-stage compressor is not high, or the temperature drop rate in the space where the two-stage cascade device is located is fast, or the first-stage compressor is in a stable state, etc. As an example, a default start interval can be set between the first-stage compressor and the second-stage compressor, and then the default start interval can be increased or decreased according to the pressure change rate of the first-stage compressor, and the adjusted default start interval is used as the start condition. After the first-stage compressor is started, it is considered that the start condition of the second-stage compressor has been reached after the adjusted default start interval.

[0044] For example, after the first-stage compressor is started, the second-stage compressor is originally scheduled to be started after 1 minute. In this embodiment, the 1 minute is adjusted according to the pressure change rate of the first-stage compressor to extend or shorten the interval. For example, it is changed to 1 minute and 20 seconds. In this case, the second-stage compressor is started 1 minute and 20 seconds after the first-stage compressor is started.

[0045] The solution provided in the embodiment of the present application determines the pressure change rate of the first-stage compressor of the multi-stage cascade refrigeration and heating device after the first-stage compressor is started, wherein the multi-stage cascade refrigeration and heating device at least includes the first-stage compressor and the second-stage compressor; determines the start-up timing of the second-stage compressor according to the pressure change rate; starts the second-stage compressor when the start-up timing of the second-stage compressor is met, so that the start-up timing of the second-stage compressor can be determined according to the pressure change rate of the first-stage compressor, thereby improving the accuracy of the start-up timing of the second-stage compressor, ensuring that the second-stage compressor will not trip after starting, and improving the stability of the multi-stage cascade refrigeration and heating device.

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

[0047] In this embodiment, a preset pressure threshold value can be preset, and the preset pressure threshold value indicates the size of an acceptable pressure change rate. If the pressure change rate of the first-stage compressor is greater than the preset pressure threshold value after the first-stage compressor is started, it is considered that the pressure change of the first-stage compressor is too fast. At this time, the start-up of the second-stage compressor can be extended, thereby leaving room for the first-stage compressor to reduce the pressure. If the pressure change rate of the first-stage compressor is less than the preset pressure threshold value after the first-stage compressor is started, it is considered that the pressure change of the first-stage compressor is slow. At this time, the start-up of the second-stage compressor can be shortened, thereby appropriately speeding up the start-up speed of the second-stage compressor, and the pressure change of the first-stage compressor will not be too high.

[0048] It should be noted that the above-mentioned pressure preset threshold can also be an interval, and the interval includes a left interval value and a right interval value. If the pressure change rate of the first-stage compressor is less than the left interval value, the default start-up interval can be shortened. If the pressure change rate of the first-stage compressor is greater than the right-left interval value, the default start-up interval can be extended. If the pressure change rate of the first-stage compressor is in the interval, the default start-up 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; when the temperature change rate is less than a preset temperature threshold, increasing the frequency of the second-stage compressor.

[0050] In this embodiment, after the first-stage compressor is started, the pressure change rate of the first-stage compressor is obtained, and the start timing of the second-stage compressor is determined according to the pressure change rate of the first-stage compressor. After the second-stage compressor is started, the temperature change rate of the target space can also be obtained. If the refrigeration and heating equipment is an air conditioner or other equipment, the target space is the space where the refrigeration and heating device is located, such as indoors, in a factory area, or in a room. If the refrigeration and heating device is a refrigerator, the target space is the inside of the refrigerator. The temperature change in the target space is the temperature change rate. The temperature change in the target space changes because the second-stage compressor is working.

[0051] In this embodiment, a temperature preset threshold value may be preset, and the temperature preset threshold value may be used to specify that the temperature in the target space should change at a speed according to the temperature preset threshold value. For example, if the temperature preset threshold value is 30, it means that the temperature in the target space should be increased or decreased by 30 degrees Celsius within a unit time (e.g., 1 minute, 10 minutes, or 1 hour, etc.). If it is not increased or decreased by 30 degrees Celsius, it indicates that the temperature change rate in the target space is not enough. At this time, it is necessary to increase the frequency of the second-stage compressor to speed up the temperature change rate in the target space.

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

[0053] In this embodiment, after the second-stage compressor is started, the temperature change rate of the target space is obtained. If the temperature change rate is less than the preset temperature threshold, the frequency of the second-stage compressor is increased to improve the operating efficiency of the second-stage compressor. If the frequency of the second-stage compressor is increased, it is also necessary to check whether the frequency of the second-stage compressor has reached the preset maximum value. If the frequency of the second-stage compressor has reached the preset maximum value, it is necessary to stop increasing the frequency of the second-stage compressor. Avoid the frequency of the second-stage compressor being too high and the pressure being too high, causing the second-stage compressor to trip. The above-mentioned preset maximum value can be a frequency value that keeps the second-stage compressor working normally without tripping. If this value is exceeded, the second-stage compressor may trip.

[0054] In addition, in order to ensure that the pressure of the second-stage compressor is not too high, when the temperature change rate is less than the preset temperature threshold, the frequency of the second-stage compressor is increased. If the temperature change rate reaches the preset temperature threshold, the frequency of the second-stage compressor is stopped from being increased. At this time, the second-stage compressor can be regarded as being in a stable state, and the temperature change rate meets the requirement.

[0055] As an optional example, when the temperature change rate is less than the preset temperature threshold, in 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 above-mentioned temperature change rate is less than the temperature preset threshold value, in the process of increasing the frequency of the above-mentioned second-stage compressor, if the temperature change rate is greater than the temperature preset threshold value, the frequency of the second-stage compressor can be stopped from being increased, and the frequency can be kept unchanged or reduced until the temperature change rate is equal to the temperature preset threshold value.

[0057] In addition, the temperature preset 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 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 unchanged. When the temperature change rate is greater than the right temperature range, the frequency of the second-stage compressor is reduced.

[0058] Continuing with the example of a two-stage cascade refrigeration device, the high-temperature compressor (first-stage compressor) is started first, and after the high-temperature compressor has been running for a period of time, the low-temperature compressor (second-stage compressor) is started. The purpose is to enable the high-temperature side circuit in the condenser to provide a certain amount of cooling capacity in advance, so as to avoid the low-temperature side compressor tripping after starting due to the excessive condensation pressure of the refrigerant in the low-temperature side circuit due to the high temperature on the condensing side after the low-temperature compressor is turned on. Therefore, the start-stop interval between the high-temperature and low-temperature compressors is crucial. When the interval is too short, the high-temperature side circuit in the condenser will provide insufficient cooling capacity, and the low-temperature side refrigerant condensation pressure will be too high, causing the low-temperature compressor to trip. When the interval is too long, the high-temperature side circuit in the condenser will provide too much cooling capacity, so that a large amount of low-temperature side refrigerant will form liquid accumulation in the condenser, and the refrigerant in the low-temperature side system will decrease, resulting in a slow cooling rate. The compressor start-stop optimization and control process provided in this embodiment can determine the start timing of the second-stage compressor based on the pressure change rate of the first-stage compressor after the first-stage compressor is started, thereby ensuring that the second-stage compressor is started at the appropriate time and avoiding the phenomenon of the first-stage compressor and the second-stage compressor tripping.

[0059] Figure 6 is a flow chart of this embodiment. Taking refrigeration as an example, Figure 6As shown, in this embodiment, the system simultaneously monitors the temperature T of the target area and the pressure P in the two-circuit compressor, thereby calculating the cooling rate Vt per unit time and the pressure increase rate VP per unit time. The system can be adjusted automatically according to the actual ambient temperature, or the operator can manually adjust the temperature preset threshold V0 and the frequency preset threshold H0 according to actual needs. During the system startup operation phase, the system monitors the internal pressure Pg of the high-temperature side circuit in real time according to the pressure sensor 8, and calculates the pressure increase rate Vg1 in the high-temperature side circuit. When Vg1 is greater than the set threshold Vg0 of the high-temperature side circuit, the system increases the startup interval of the low-temperature compressor by t1, and increases the refrigeration time of the high-temperature compressor to relieve the pressure of the high-temperature side circuit. During the stable operation phase, when it is detected that the actual cooling rate Vt of the compartment is less than the temperature preset threshold V0, and the compressor frequency has not reached the highest frequency, the system controls the compressor to increase the frequency to pull the temperature (it can be the second-stage compressor, or the first-stage compressor and the second-stage compressor can be increased at the same time) until Vt≧V0 or the compressor has reached the highest frequency, the compressor stops increasing the frequency and runs at the current frequency. If the pressure rise rate Vp in the circuit is greater than the set threshold Vp0 during the operation phase, or the pressure rise rate Vp in the circuit does not reach the set threshold Vp0 in a short period of time, but the pressure in the system may be relatively high, the machine tripping and other phenomena may occur. At this time, the system will judge that the pressure P in the pipeline of the first-stage compressor or the second-stage compressor will reach the pressure threshold P0 before stopping according to the cooling rate Vt. At this time, the system will temporarily lower the frequency of the corresponding compressor to reduce the pressure in the pipeline, give priority to ensuring the normal operation of the system, and avoid abnormal phenomena such as tripping. When it is detected that the ambient temperature is low or the load is small, the system lowers the temperature preset threshold V0 and controls the compressor to run at a lower frequency to avoid excessive cooling due to excessive cooling capacity per unit time, short compressor startup time, frequent compressor start-up and stop, increased operating power consumption, and shortened compressor service life. When the ambient temperature is high or the load is heavy, the system controls to increase the temperature preset threshold V0 and increase the frequency of the compressor to meet the cooling demand.

[0060] Figure 7 This is a schematic diagram of the structure of a multi-stage cascade refrigeration and heating device provided in an embodiment of the present application. Figure 7 As shown, the multi-stage cascade refrigeration and heating device comprises:

[0061] A first determination 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 the first-stage compressor and the second-stage compressor;

[0062] A second determination module 704 is used to determine the start timing of the second stage compressor according to 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 may be a two-stage cascade refrigeration and heating device, or may be a three-stage or even more-stage cascade refrigeration and heating device with two or more stages. The multi-stage cascade refrigeration and heating device may be a device for refrigeration, the first-stage compressor is a refrigeration compressor for refrigerating the second-stage compressor, the second-stage compressor is a refrigeration compressor for refrigerating 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. Or the multi-stage cascade refrigeration and heating device may be a device for heating, the first-stage compressor is a heating compressor for heating the second-stage compressor, the second-stage compressor is a heating compressor for heating 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.

[0065] For example, a bipolar cascade refrigeration device includes two compressors. One compressor starts first. The compressor that starts first is responsible for generating a certain amount of cold air. The hot air generated in the process of generating cold air is discharged to the outside. The second compressor starts when the starting conditions are met. The compressor that starts later uses the cold air of the compressor that starts first to cool the room and discharges the cold air indoors. The hot air generated in the cooling process is given to the first compressor, allowing the first compressor to cool the hot air. Figure 2 shown. Figure 2 In the process, when the first-stage compressor is cooling, it transmits cold air to the second-stage compressor, and transmits the hot air generated in the cooling process to the outside. The cold air transmitted to the second-stage compressor is used for further cooling by the second-stage compressor, thereby reducing the indoor temperature, and the hot air generated in the cooling process of the second-stage compressor is transmitted 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 device, taking a three-stage cascade refrigeration and heating device as an example, then Figure 3 As shown. The first stage compressor provides cold air to the second stage compressor, and the hot air generated during the refrigeration process is discharged to the outside. The second stage compressor uses the cold air provided by the first stage compressor for refrigeration, and the refrigerated cold air is given to the third stage compressor, and the hot air generated during the refrigeration process is given to the first stage compressor. The third stage compressor uses the cold air of the second stage compressor to cool the room, and the generated hot air is given to the second stage compressor.

[0067] If it is a multi-stage cascade refrigeration equipment, more stages of compressors will be added. The core idea is that the upper stage compressor provides cold air to the lower stage compressor, and the lower stage compressor continues to cool and provide hot air to the upper stage compressor.

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

[0069] In this embodiment, the air exchange between the multiple compressors in the above-mentioned multi-stage cascade cooling and heating device can be air exchange, that is, the air moves between different compressors, or heat exchange, that is, the air does not move between different compressors, but the cold air and the hot air are separated and exchange heat with each other. For example, taking a two-stage compressor as an example, Figure 4 The diagram shows the heat exchange between cold air and hot air via a heat exchangeable medium. Figure 4 In the embodiment, the heat exchangeable medium 402 can separate the air of the first stage compressor from the air of the second stage compressor, and although the two can exchange heat, they are not intercommunication with each other. In this way, the refrigerant between the first stage compressor and the second stage compressor can be prevented from leaking to each other.

[0070] Figure 5 It is a schematic diagram of the heat exchange of hot and cold gas mixture between two-stage compressors, such as Figure 5As shown. 1 is a low-temperature compressor (second-stage compressor), 2 is a filter, 3 is an oil separator, 4 is a condensing fan, 5 is a condenser, 6 is an anti-condensation tube, 7 is a high-temperature compressor (first-stage compressor), 8 is a filter, 9 is a high-temperature side pressure sensor, 10 is a gas-liquid separator, 11 is a high-temperature side capillary, 12 is an intermediate heat exchanger, 13 is a low-temperature side capillary, 14 is an evaporator, and 15 is a low-temperature side pressure sensor. The high-temperature and high-pressure gas discharged from the high-temperature compressor 7 flows through the condenser 5 to exchange heat with the ambient air and is condensed, then enters the high-temperature side capillary 11 through the anti-condensation tube 6 for throttling, and enters the intermediate heat exchanger 12. The high-temperature and high-pressure gas discharged from the low-temperature 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. At the same time, the high-temperature side refrigerant uses its own low temperature to exchange heat with the low-temperature side refrigerant in the intermediate heat exchanger 12, further reducing the refrigerant temperature. The refrigerant in the high-temperature side loop continues to flow through the gas-liquid separator 10 and returns to the high-temperature compressor, completing the high-temperature side loop cycle. The refrigerant in the low-temperature side loop continues to run after flowing through the intermediate heat exchanger 12, throttling through the capillary 13, and then cooling the compartment through the evaporator 14, and then the refrigerant returns to the low-temperature compressor, and the low-temperature side loop completes the cycle. At this time, the system completes a refrigeration cycle.

[0071] Continuing with the example of a two-stage cascade device, in this embodiment, when a cooling / heating task is received, the first-stage compressor must first be started, and the first-stage compressor works to cool or heat. Then, during the operation of the first-stage compressor, the pressure will change, and the pressure change rate indicates the pressure rise rate of the compressor. The greater the pressure change rate, the faster the pressure rise rate of the compressor. The start time of the second-stage compressor is determined according to the size of the pressure change rate. For example, if the pressure change rate is relatively fast, it means that the pressure of the first-stage compressor is relatively large. If the second-stage compressor is turned on at this time, the pressure of the first-stage compressor is larger and it is easy to trip. Therefore, the start time of the second-stage compressor should be delayed. If the pressure change rate of the first-stage compressor is relatively slow, it means that the pressure of the first-stage compressor is relatively small. At this time, the start time of the second-stage compressor can be advanced.

[0072] In this embodiment, when the start timing of the second-stage compressor is met, the second-stage compressor can be started. There can be many situations for the start timing of the second-stage compressor. For example, the pressure of the first-stage compressor is not high, or the temperature drop rate in the space where the two-stage cascade device is located is fast, or the first-stage compressor is in a stable state, etc. As an example, a default start interval can be set between the first-stage compressor and the second-stage compressor, and then the default start interval can be increased or decreased according to the pressure change rate of the first-stage compressor, and the adjusted default start interval is used as the start condition. After the first-stage compressor is started, it is considered that the start condition of the second-stage compressor has been reached after the adjusted default start interval.

[0073] For example, after the first-stage compressor is started, the second-stage compressor is originally scheduled to be started after 1 minute. In this embodiment, the 1 minute is adjusted according to the pressure change rate of the first-stage compressor to extend or shorten the interval. For example, it is changed to 1 minute and 20 seconds. In this case, the second-stage compressor is started 1 minute and 20 seconds after the first-stage compressor is started.

[0074] The solution provided in the embodiment of the present application determines the pressure change rate of the first-stage compressor of the multi-stage cascade refrigeration and heating device after the first-stage compressor is started, wherein the multi-stage cascade refrigeration and heating device at least includes the first-stage compressor and the second-stage compressor; determines the start-up timing of the second-stage compressor according to the pressure change rate; starts the second-stage compressor when the start-up timing of the second-stage compressor is met, so that the start-up timing of the second-stage compressor can be determined according to the pressure change rate of the first-stage compressor, thereby improving the accuracy of the start-up timing of the second-stage compressor, ensuring that the second-stage compressor will not trip after starting, and improving the stability of the multi-stage cascade refrigeration and heating device.

[0075] For other examples of this embodiment, please refer to the above examples and will not be described in detail here.

[0076] The present application also provides a multi-stage cascade refrigeration and heating system, comprising:

[0077] A first determination module is used to determine the pressure change rate of the first-stage compressor of the multi-stage cascade refrigeration and heating device 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 at least includes the first-stage compressor and the second-stage compressor;

[0078] A second determination module, used to determine the start timing of the second-stage compressor according to the pressure change rate;

[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 above examples and will not be described in detail here.

[0081] like Figure 8 As shown, an embodiment of the present 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, used for storing computer programs;

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

[0084] An embodiment of the present application further provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the multi-stage cascade cooling and heating method provided by any of the aforementioned method embodiments is implemented.

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

[0086] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a general hardware platform, and of course, by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the relevant technology can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0087] It should be understood that the terms used herein are only for the purpose of describing specific example embodiments and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "one", "an" and "said" as used herein may also be meant to include plural forms. The terms "include", "comprise", "contain", and "have" are inclusive, and therefore specify the existence of stated features, steps, operations, elements and / or parts, but do not exclude the existence or addition of one or more other features, steps, operations, elements, parts, and / or combinations thereof. The method steps, processes, and operations described herein are not interpreted as necessarily requiring them to be performed in the specific order described or illustrated, unless the execution order is clearly indicated. It should also be understood that additional or alternative steps may be used.

[0088] The foregoing is merely a specific embodiment of the present invention, which enables those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be 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 present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to 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 a first-stage compressor of a multi-stage cascade refrigeration and heating device is started, determining a pressure change rate of 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 time of the second stage compressor according to the pressure change rate; When the start timing of the second-stage compressor is met, the second-stage compressor is started.

2. The method according to claim 1, characterized in that Determining the start timing of the second-stage compressor according to the pressure change rate includes: Obtaining a first start time and a default start interval of the first stage compressor; When the pressure change rate exceeds a preset pressure threshold, increasing the duration of the default start interval, and determining a second start timing of the second stage compressor according to the increased default start interval; When the pressure change rate is less than the preset pressure threshold, the duration of the default start interval is reduced, and the second start timing of the second stage compressor is determined according to the reduced default start interval.

3. The method according to claim 2, characterized in that After starting the second stage compressor, the method further includes: Obtaining 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, the frequency of the second stage compressor is increased.

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

5. The method according to claim 3, characterized in that: When the temperature change rate is less than a preset temperature threshold, in 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, the current frequency of the second-stage compressor is maintained or the current frequency of the second-stage compressor is reduced.

6. The method according to claim 1, characterized in that 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. The method according to claim 1, characterized in that 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.

8. A multi-stage cascade refrigeration and heating device, characterized in that: include: A first determination module is used to determine the pressure change rate of the first-stage compressor of the multi-stage cascade refrigeration and heating device 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; A second determination module, configured to determine a start time of the second stage compressor according to the pressure change rate; A starting module is used to start the second-stage compressor when the starting timing of the second-stage compressor is met.

9. A multi-stage cascade refrigeration and heating system, characterized in that: include: A first determination module is used to determine the pressure change rate of the first-stage compressor of the multi-stage cascade refrigeration and heating device 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; A second determination module, configured to determine a start time of the second stage compressor according to the pressure change rate; A starting module is used to start the second-stage compressor when the starting timing of the second-stage compressor is met.

10. 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 coupled 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 when the processor executes the computer program, the multi-stage cascade cooling and heating method described in any one of claims 1 to 7 is implemented.

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