A Dual-Mode Adaptive Control Method for Preventing Liquid Slugging and Enhancing Subcooling in Low-Temperature Heat Pumps

Abstract

This invention proposes a dual-mode adaptive control method for preventing liquid slugging and enhancing subcooling in low-temperature heat pumps. The method includes: monitoring the bottom temperature of the gas-liquid separator and the rate of temperature change; constructing a liquid slugging risk index based on the difference between the temperature and a preset safety critical temperature, and the difference between the rate of temperature change and a preset minimum temperature rise rate; calculating the pulse power excitation intensity based on the liquid slugging risk index, and selecting the number of open injection channels and adjusting the pulse duty cycle of each channel accordingly to control the injection of high-temperature gaseous refrigerant into the bottom of the gas-liquid separator, driving the evaporation of liquid refrigerant; generating a mode switching score; generating a mode switching signal when the mode switching score exceeds the mode switching threshold and the gas-liquid separator temperature reaches the safety lower limit; switching to the subcooling enhancement mode according to the mode switching signal, and adjusting the opening of the electronic expansion valve of the economizer branch according to the deviation between the current subcooling and the target subcooling.

Description

Technical Field

[0001] This invention belongs to the field of heat pump control, and particularly relates to a method for preventing liquid slugging and enhancing subcooling control of low-temperature heat pumps based on dual-mode adaptive regulation. Background Technology

[0002] Air source heat pumps operating in extreme low-temperature environments (-30°C to 5°C) face the dual challenges of liquid refrigerant retention and decreased system energy efficiency. During initial startup, large areas of liquid accumulation easily occur at the bottom of the gas-liquid separator and in the evaporator piping. The sudden reduction in circulating refrigerant causes a surge in the liquid content of the compressor intake, leading to liquid slugging and shortening compressor life. Common solutions include preheating via electric heating or fixed-ratio bypass, but these methods are energy-intensive and cannot accurately assess the degree of liquid accumulation, resulting in insufficient protection or overheating. Once in normal operation, the large fluctuations in condensing pressure and increased throttling flash ratio under low-temperature conditions make traditional subcooling control based on fixed targets and a single PID controller difficult to maintain stability under rapid load changes, often resulting in insufficient subcooling and reduced COP. Further complicating matters, liquid slugging protection and subcooling regulation are typically driven by independent logic. When some actuators (electronic expansion valves, three-way valves, bypass piping, etc.) are used interchangeably, they constrain each other, making it impossible to achieve a balance between startup safety and operational efficiency, severely limiting the application and promotion of air source heat pumps in frigid regions. Summary of the Invention

[0003] The purpose of this invention is to design a low-temperature heat pump anti-liquid slugging and subcooling enhancement control method based on dual-mode adaptive regulation, which can ensure the safe start-up of the compressor and maintain efficient heat exchange in the steady state stage, thereby shortening the preheating time, reducing energy consumption and improving COP of the low-temperature air source heat pump in extremely cold regions.

[0004] To achieve the above objectives, this invention provides a method for preventing liquid slugging and enhancing supercooling in low-temperature heat pumps based on dual-mode adaptive regulation, the method comprising:

[0005] Monitor the bottom temperature of the gas-liquid separator and the rate of temperature change. Based on the difference between the temperature and the preset safety critical temperature, and the difference between the rate of temperature change and the preset minimum temperature rise rate, construct a liquid hammer risk index through a weighted synthesis method.

[0006] Based on the liquid slugging risk index, combined with the nonlinear risk amplification mechanism and heat capacity correction factor, the pulse power excitation intensity is calculated, and the number of injection channels to be opened and the pulse duty cycle of each channel are adjusted accordingly. The high-temperature gaseous refrigerant is injected into the bottom of the gas-liquid separator in a pulse manner to drive the liquid refrigerant to evaporate.

[0007] Calculate the liquid hammer response attenuation factor, and combine it with the temperature difference between the condenser and the gas-liquid separator and the system heat exchange response rate to generate a mode switching score. When the mode switching score exceeds the mode switching threshold and the gas-liquid separator temperature reaches the safe lower limit, a mode switching signal is generated.

[0008] Based on the mode switching signal, the system switches to the subcooling enhancement mode. According to the deviation between the current subcooling and the target subcooling, and combined with the ratio of condensing pressure to critical pressure, the opening of the electronic expansion valve in the economizer branch is adjusted to achieve stable control of subcooling.

[0009] Furthermore, the nonlinear risk amplification mechanism is achieved by introducing a higher-order nonlinear term of the liquid slug risk index, which enhances the system's response strength in the high-risk range.

[0010] Furthermore, the heat capacity correction factor is calculated by back-calculation through monitoring the dynamic relationship between the heating input and the temperature rise response of the gas-liquid separator.

[0011] Furthermore, the pulse power excitation intensity is obtained based on the liquid shock risk index, specifically: when the liquid shock risk index is higher than the first risk threshold, the first frequency value is used; when the liquid shock risk index is between the first risk threshold and the second risk threshold, the second frequency value is used; and when the liquid shock risk index is lower than the second risk threshold, the third frequency value is used, wherein the first frequency value is greater than the second frequency value, and the second frequency value is greater than the third frequency value.

[0012] Furthermore, the system heat exchange response rate is obtained by calculating the rate of change of the difference between the evaporator inlet temperature and the condenser outlet temperature over time.

[0013] Furthermore, the liquid slugging response attenuation factor is calculated by combining the ratio of the number of currently open injection channels to the maximum number of channels, and the ratio of the current duty cycle to the maximum duty cycle.

[0014] Furthermore, the mode switching threshold can be adaptively adjusted based on the system's real-time operating status parameters and historical performance data. This adaptive adjustment is specifically achieved through the following methods: a threshold optimization model is established based on the system's mode switching success rate and energy efficiency performance data during historical operation. This threshold optimization model takes the condensing pressure fluctuation range, the rate of change of ambient temperature, and the trend of system load change as input parameters and outputs the optimal recommended value for the mode switching threshold. The control system selects and applies the corresponding recommended threshold value based on the similarity between the current operating environment and historical data.

[0015] Furthermore, the mode switching score is calculated as follows: the liquid hammer response attenuation factor, the ratio of the temperature difference between the condenser and the gas-liquid separator to the reference temperature difference, and the difference between the system heat exchange response rate and the minimum threshold value are weighted and summed. The difference between the system heat exchange response rate and the minimum threshold value is processed by the ReLU function and is only included in the score when the heat exchange rate increases beyond the preset threshold.

[0016] Furthermore, the ratio of condensing pressure to critical pressure adopts a segmented suppression strategy, specifically including: when the condensing pressure is lower than the first pressure threshold, a first suppression coefficient is used; when the condensing pressure is between the first and second pressure thresholds, a second suppression coefficient is used; when the condensing pressure is higher than the second pressure threshold, a third suppression coefficient is used; wherein the first suppression coefficient is less than the second suppression coefficient, and the second suppression coefficient is less than the third suppression coefficient.

[0017] Furthermore, when the subcooling deviation is detected to be lower than the set threshold for X consecutive sampling periods, the system automatically locks the current economizer opening degree, where X is a preset value.

[0018] The beneficial technical effects of the present invention are at least as follows:

[0019] To address the aforementioned problems, this invention provides a dual-mode adaptive control method for preventing liquid slugging and enhancing subcooling in low-temperature heat pumps. By utilizing the bottom temperature of the gas separator and its heating slope to construct a liquid slugging risk index in real time, pulse bypass heating is triggered before the liquid slugging risk materializes. A liquid heat capacity ratio correction is introduced to dynamically adjust the injection channel and duty cycle according to the risk level, balancing response speed and energy consumption. The process incorporates a composite switching criterion based on the injection attenuation factor, condensation-gas separation temperature difference, and heat exchange enhancement rate. Subcooling enhancement is only switched to when the liquid slugging risk is eliminated and the system's thermal cycle has recovered, avoiding safety hazards caused by erroneous switching. A closed-loop subcooling regulation formula with a condensation pressure suppression term is established to automatically limit refrigerant distribution under high-pressure conditions while ensuring the target subcooling, preventing unstable operating conditions caused by over-adjustment. Through the above three collaborative innovations, this invention realizes a continuous link of liquid slugging prediction, dynamic intervention, mode switching and subcooling optimization, which not only ensures the safety of compressor start-up, but also maintains efficient heat exchange in the steady state stage, thereby shortening the preheating time, reducing energy consumption and improving COP of low temperature air source heat pumps in frigid regions. Attached Figure Description

[0020] The present invention will be further described with reference to the accompanying drawings, but the embodiments in the drawings do not constitute any limitation on the present invention. For those skilled in the art, other drawings can be obtained based on the following drawings without creative effort.

[0021] Figure 1This is a flowchart of the low-temperature heat pump anti-liquid slugging and supercooling enhancement control method based on dual-mode adaptive regulation according to the present invention. Detailed Implementation

[0022] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0023] In one or more embodiments, such as Figure 1 As shown, a method for preventing liquid slugging and enhancing subcooling in low-temperature heat pumps based on dual-mode adaptive regulation is disclosed. The method includes the following:

[0024] S1: Monitor the bottom temperature of the gas-liquid separator and the rate of temperature change. Based on the difference between the temperature and the preset safety critical temperature, and the difference between the rate of temperature change and the preset minimum temperature rise rate, construct a liquid hammer risk index through a weighted synthesis method.

[0025] Specifically, the core objective of this step is to determine the risk of liquid refrigerant retention during the initial startup of a cryogenic heat pump by identifying the thermal state of the refrigerant in the gas-liquid separator, and to quantify the liquid slugging trend. Liquid refrigerant accumulation at the bottom of the gas separator is a common problem during heat pump startup in cryogenic conditions. Its direct consequence is that the compressor operates by drawing liquid, leading to the risk of liquid slugging. Traditional systems typically rely on timed preheating or a fixed-ratio bypass loop to preheat the gas separator, but this makes it difficult to determine in real time whether liquid refrigerant retention actually exists, easily leading to "insufficient preheating" or "overheating" problems, resulting in energy waste or protection failure. Therefore, it is necessary to design a risk criterion that can depict the liquid accumulation trend in real time.

[0026] This step directly uses two types of core sensing parameters as input during the initial system startup. The first type is the temperature at the bottom of the gas-liquid separator. The temperature data is collected by an NTC thermistor sensor located at the bottom of the separator (the sensor typically has an accuracy of ±0.1℃ and a response time of <1s). This location is usually where liquid refrigerant is most likely to accumulate in the gas separator. The control system reads this temperature data every 2 seconds and stores it in the buffer loop queue.

[0027] The second type of input is the rate of change of temperature at the bottom of the gas separator per unit time. Its value is calculated online by the system controller using a first-order difference method during runtime. The difference interval is a fixed period. The difference is calculated as follows:

[0028] ;

[0029] in This represents the current time point. This slope value reflects the response speed of the refrigerant at the bottom to changes in temperature. If heating has been turned on but the temperature slope remains close to zero, it indicates that the thermal energy has failed to effectively drive phase change evaporation, and there is a problem of refrigerant accumulation without evaporation.

[0030] The two original variables mentioned above together form the input basis for liquid slugging risk modeling. To enable the system to use a single control variable to drive subsequent strategies in its control logic, this step introduces a comprehensive liquid slugging risk index. The calculation formula is as follows:

[0031] ;

[0032] The formula consists of two weighted terms: the first term measures whether the current temperature of the gas separator is below a set safety threshold. The temperature is generally set to 5℃. When the temperature of the gas separator is lower than this value, it indicates that the refrigerant is still in a liquid state or has not fully evaporated. This refers to the "liquid slugging risk detection threshold," which determines whether the temperature at the bottom of the gas separator is still in the low-temperature liquid state region. Physically, this triggers protection. When the temperature at the bottom of the gas-liquid separator... Below If the condition is such that the refrigerant is still in the low-temperature liquid state zone or has just entered the evaporation edge zone within the separator, and the liquid has not yet fully vaporized, the risk of the compressor drawing liquid is high, and the controller must immediately enter the anti-liquid slugging mode (activating pulse bypass heating, limiting compressor frequency, etc.). The second item reflects whether the heating rate is lower than the minimum expected rate. , usually set as This rate value comes from experimental calibration and represents the minimum evaporation response rate that the gas separator should achieve under normal bypass injection conditions.

[0033] The two indicators are constructed as a one-sided action function using the max function to avoid misjudging normal operating conditions such as excessively high temperature or rapid temperature rise. Weighting coefficients. , The default factory settings are 0.6 and 0.4, but minor adjustments can be made in extremely low-temperature regions. The significance is that if a particular indicator reflects a significant risk, the overall index can be increased, driving the system into protective mode earlier.

[0034] Specifically, when the temperature at the bottom of the gas separator is only -8.5℃ and the temperature rise slope is 0.05℃ / s, then:

[0035] ;

[0036] The system normalizes this value to interval (e.g., by) (for the maximum threshold), the final control input value is This indicates a serious risk of liquid cooling failure, and the next step should be to immediately activate a high-level bypass response.

[0037] S2: Based on the liquid slugging risk index, combined with the nonlinear risk amplification mechanism and heat capacity correction factor, the pulse power excitation intensity is calculated, and the number of injection channels to be opened and the pulse duty cycle of each channel are adjusted accordingly. The high-temperature gaseous refrigerant is injected into the bottom of the gas-liquid separator in a pulse manner to drive the liquid refrigerant to evaporate.

[0038] Specifically, the goal of this step is to quickly drive local refrigerant vaporization through structured, energy-saving, and high-response-rate intervention after identifying the risk of liquid refrigerant accumulation in the gas-liquid separator, thereby avoiding the risk of the compressor drawing in liquid refrigerant during startup. Unlike traditional methods, this solution not only determines whether to activate bypass injection based on the liquid slugging risk value, but also introduces dynamic adjustment terms and nonlinear correction quantities into the channel cascading strategy, pulse excitation mechanism, and system response terms. This enables the control system to quickly break through the thermal resistance barrier of the liquid refrigerant accumulation point with lower energy consumption, improving overall startup safety and efficiency.

[0039] Unlike traditional injection based on a fixed rhythm, this step designs a dynamic control mechanism that integrates a nonlinear risk amplification term and a "heat capacity resistance correction factor" during the start-up phase, and proposes the following control formula:

[0040] ;

[0041] in: This is the pulse power excitation intensity control factor (used to determine the duty cycle and injection energy of each channel). The liquid impact risk index is derived from step one; The weight is linearly amplified; the default value is 0.8. This is a nonlinear response gain factor used to enhance the response sensitivity of high-risk sections, and is typically set to 0.6. The current estimated heat capacity of the gas separator is calculated by back-calculating the temperature rise rate under unit heating input; This is the reference heat capacity (calibrated value) under standard conditions. This is a heat capacity correction weighting factor, typically set to 1.0–1.5, used to improve pulse intensity under high heat capacity conditions.

[0042] In this formula, As a nonlinear gain mechanism, the term can drastically increase the response strength when the risk value is close to 1, avoiding the mismatch between "slow response and high risk"; secondly, the heat capacity ratio term By assessing the refrigerant thermal resistance level of the system and automatically adjusting the injection intensity, the low energy efficiency problem of traditional solutions, which "inject more but heat up slowly" under different gas separation structures and heat capacity characteristics, is solved.

[0043] In practical implementation, the system controls... Mapped to the following control policies:

[0044] Channel selection: If Enable 1 channel; Two channels will be activated. All three channels are open.

[0045] Pulse duty cycle adjustment: Mapped to the pulse duty cycle of each channel (Range from 0.2 to 0.8), for example, through linear normalization:

[0046] ;

[0047] The controller periodically opens the solenoid valve at a 1Hz pulse frequency (which can be dynamically adjusted), allowing high-temperature gaseous refrigerant to be injected into the bottom of the gas distributor through a directional nozzle.

[0048] Specifically, during a certain low-temperature startup phase, the system monitored the following: ; Then we have:

[0049] ;

[0050] The final duty cycle is Channel 3 is activated. The injection module will enter a high-intensity heating state, rapidly driving localized evaporation of the refrigerant within the gas separator, reducing the risk of liquid slugging.

[0051] S3: Calculate the liquid hammer response attenuation factor, and combine it with the temperature difference between the condenser and the gas-liquid separator and the system heat exchange response rate to generate a mode switching score. When the mode switching score exceeds the mode switching threshold and the gas-liquid separator temperature reaches the safe lower limit, a mode switching signal is generated.

[0052] Specifically, the process involves constructing a criterion model that is highly adapted to the operating conditions of low-temperature heat pumps, integrating three core signals: execution status, thermal status, and energy efficiency trend, to determine whether the system meets the condition that "the risk of liquid slugging has been mitigated and it has the potential to enhance supercooling," thereby triggering subsequent control procedures.

[0053] First, construct the basic state factors:

[0054] ;

[0055] This item represents the "attenuation degree" of the liquid hammer response intensity. A higher value indicates that the current protection is weakening, the system is in the late stage of response, and conditions are being created for switching. Among them: This indicates the number of bypass injection channels that are currently open. The maximum duty cycle that can be set for a single-channel pulse controller represents the longest opening ratio of the solenoid valve per second at a 1 Hz reference frequency;

[0056] Furthermore, the operating condition feedback indicators are incorporated into the primary criteria:

[0057] Temperature difference between condenser outlet and bottom of gas separator ;in, This refers to the temperature at the condenser outlet.

[0058] Rate of change of total system heat exchange response capacity after compressor startup ,in This is the evaporator inlet temperature.

[0059] The final complete switching criterion is as follows:

[0060] ;

[0061] in: To calibrate the temperature difference (e.g., 15°C); The weights are adjusted based on experience, with typical values ​​of 0.4 and 0.3. To improve the minimum threshold for heat exchange (e.g., 1.0℃ / min); This means that the score is only calculated when the heat exchange rate increases significantly, in order to prevent erroneous switching caused by slow heat exchange disturbances.

[0062] The system refreshes all input data every 10 seconds and calculates... If the following conditions are met:

[0063] ;

[0064] This triggers a mode switch; where The switching threshold is set to 0.9 (the standard setting value for general operating scenarios is recommended). This is the safe limit for gas separation temperature (e.g., 30°C). It refers to "switching the safety temperature limit." Only when the gas separator temperature has risen sufficiently to prove that the refrigerant has essentially vaporized and the risk of liquid slugging has been eliminated is the system allowed to enter the supercooling enhancement mode. The physical meaning here is to deactivate the protection; only when... Rise to Only when the refrigerant remains stable can it be considered that it has achieved sufficient superheat, all liquid phase has vaporized, and the oil circuit is unobstructed. At this point, it is permissible to deactivate protection and switch to subcooling enhancement mode to improve system efficiency. Taking R-410A, commonly used in low-temperature air source heat pumps in northern regions, as an example, its saturation temperature is approximately -20°C at 0.4 MPa (absolute pressure, ≈4 barA). When the temperature at the bottom of the gas separator rises to around 5°C, it only indicates that it is approaching the edge of liquid-gas equilibrium, and there may still be residual liquid in some areas, requiring immediate triggering of protection. Conversely, if the temperature at this point can be stabilized above 30°C, the system (under the corresponding operating conditions) has moved far away from the saturation curve. In addition, R-410A has good miscibility and fluidity with commonly used POE oil in the operating range of approximately 1.9–2.0 MPa, which is beneficial for oil return and intake air drying. Therefore, it can be used as a safe lower limit for deactivating protection and entering performance optimization. If using R-32 with a higher saturation curve, the threshold can be shifted upwards by two points using the same logic. However, it is recommended to maintain a safety margin of 20–25 K between the two to ensure early triggering while avoiding premature exit. When the condition is met, the following flags will be output:

[0065] This indicates that the supercooling enhancement mode can be switched;

[0066] Otherwise, maintain The system continues to perform liquid hammer protection operations.

[0067] For example, the system state at a certain moment is as follows:

[0068] , ;

[0069] , ;

[0070] , Then we have:

[0071] ;

[0072] , ;

[0073] ;

[0074] but:

[0075] ;

[0076] If set This refers to the recommended switching threshold under normal operating scenarios. Therefore, the system remains in liquid slugging protection mode and only switches to the performance enhancement path and executes the supercooling control strategy after the conditions are met in the next cycle.

[0077] If set This refers to the recommended switching threshold under ultra-low temperature or rapid load fluctuation conditions. If the switching conditions are met, the system will enter the performance enhancement path and execute the subcooling control strategy.

[0078] S4: Based on the mode switching signal, switch to the subcooling enhancement mode. According to the deviation between the current subcooling and the target subcooling, and combined with the ratio of condensing pressure to critical pressure, adjust the opening of the electronic expansion valve of the economizer branch to achieve stable control of subcooling.

[0079] Specifically, the core task of this step is to confirm in the previous step that it is possible to switch from liquid slugging protection mode to supercooling enhancement mode (i.e. After that, the activation and dynamic control of the subcooling path are specifically executed to ensure that the system achieves efficient heat exchange and rapid subcooling in a low-temperature environment, while ensuring system stability and safety.

[0080] when Subsequently, the system gradually activates the subcooling enhancement loop. In this embodiment, the subcooling loop uses an electronic expansion valve to control the bypass refrigerant flow. The goal is to gradually control the subcooling to the set target. (10℃ is recommended), and maintain system stability.

[0081] First, define the current subcooling difference:

[0082] ;

[0083] in: This is the real-time measured value of subcooling; if This indicates that further cooling is needed, and the system will gradually increase the opening of the economizer branch. .

[0084] To ensure that the regulation response is not affected by large fluctuations in condensing pressure, this scheme introduces a pressure-related compensation and suppression term, and the final control formula is:

[0085] ;

[0086] in: The opening degree of the electronic expansion valve in the updated economizer branch; The current opening degree is saved by the controller's internal state; This is the proportional gain term (e.g., 0.08 / ℃). This is the condensation pressure penalty coefficient (e.g., 0.1). This is the critical pressure (system design value, such as 2.5 MPa). This refers to the pressure in the high-pressure pipeline on the condenser outlet side.

[0087] Specifically, currently (Indicates an opening degree of 40%) ; MPa MPa;

[0088] but:

[0089] ;

[0090] The controller will adjust the valve to 55.2% opening in minimum steps (e.g., 2%) and continue monitoring. Is it close to the target?

[0091] If within three consecutive sampling periods (e.g., 30 seconds) If the subcooling is stable, the controller will lock the current setting. It enters a steady-state mode and awaits the next round of heat load changes.

[0092] This invention also provides a low-temperature heat pump anti-liquid slugging and supercooling enhancement control device based on dual-mode adaptive regulation, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the steps described in the above embodiments of the low-temperature heat pump anti-liquid slugging and supercooling enhancement control method based on dual-mode adaptive regulation, for example... Figure 1 The steps S1 to S6 described above; or, when the processor executes the computer program, it implements the functions of each module in the above system embodiments.

[0093] For example, the computer program may be divided into one or more modules, which are stored in the memory and executed by the processor to complete the present invention. The one or more modules may be a series of computer program instruction segments capable of performing specific functions, which describe the execution process of the computer program in the dual-mode adaptive control-based cryogenic heat pump anti-liquid slugging and supercooling enhancement control device.

[0094] The dual-mode adaptive control system for preventing liquid slugging and enhancing supercooling in low-temperature heat pumps can be a computing device such as a desktop computer, laptop, handheld computer, or cloud server. This system may include, but is not limited to, a processor and memory. Those skilled in the art will understand that the dual-mode adaptive control system may also include input / output devices, network access devices, and buses.

[0095] The processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASACs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor. This processor is the control center of the dual-mode adaptive control-based cryogenic heat pump anti-liquid slugging and supercooling enhancement control device, connecting all parts of the device via various interfaces and lines.

[0096] The memory can be used to store the computer program and / or modules. The processor, by running or executing the computer program and / or modules stored in the memory, and by calling the data stored in the memory, realizes various functions of the low-temperature heat pump anti-liquid slugging and supercooling enhancement control device based on dual-mode adaptive regulation. The memory may mainly include a program storage area and a data storage area. The program storage area may store the operating system, at least one application program required for a function, etc.; the data storage area may store data created based on the operation of the air conditioner controller, etc. In addition, the memory may include high-speed random access memory, and may also include non-volatile memory, such as hard disk, memory, plug-in hard disk, smart media card (SMC), secure digital card (SD card), flash card, at least one disk storage device, flash memory device, or other volatile solid-state storage devices.

[0097] The module integrated with the dual-mode adaptive control-based low-temperature heat pump anti-liquid slugging and supercooling enhancement control equipment, if implemented as a software functional unit and sold or used as an independent product, can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc.

[0098] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc.

[0099] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A low-temperature heat pump anti-liquid-splashing and supercooling degree strengthening control method based on dual-mode adaptive regulation, characterized in that, The method comprises: Monitoring the temperature at the bottom of the gas-liquid separator and the rate of change of the temperature, and constructing a liquid impact risk index by a weighted synthesis method based on the difference between the temperature and a preset safety critical temperature and the difference between the rate of change and a preset minimum temperature rise rate; Based on the liquid impact risk index, the pulse power excitation strength is calculated in combination with a nonlinear risk amplification mechanism and a heat capacity correction factor, and the number of open injection channels and the pulse duty cycle of each channel are dynamically selected accordingly to control the injection of high-temperature gaseous refrigerant into the bottom of the gas-liquid separator in a pulse mode to drive the evaporation of liquid refrigerant; A liquid impact response decay factor is calculated, and a mode switching score is generated in combination with the temperature difference between the condenser and the gas-liquid separator and the system heat exchange response rate. When the mode switching score exceeds a mode switching threshold and the temperature of the gas-liquid separator reaches a lower safety limit, a mode switching signal is generated. The mode switching threshold is adaptively adjusted according to real-time operating state parameters and historical performance data of the system. The adaptive adjustment is specifically realized by the following method: based on the mode switching success rate and energy efficiency performance data of the system in historical operation, a threshold optimization model is established, which takes the condenser pressure fluctuation range, the ambient temperature change rate, and the system load change trend as input parameters and outputs the optimal mode switching threshold recommendation value; the control system selects and applies the corresponding threshold recommendation value according to the similarity between the current operating environment and the historical data; the mode switching score is calculated by weighting the sum of the liquid impact response decay factor, the ratio of the temperature difference between the condenser and the gas-liquid separator to the reference temperature difference, and the difference between the system heat exchange response rate and the minimum threshold value, wherein the difference between the system heat exchange response rate and the minimum threshold value is processed by a ReLU function and only when the heat exchange rate exceeds a preset threshold value is it included in the score; According to the mode switching signal, switch to the supercooling degree enhancement mode, adjust the opening of the economizer branch electronic expansion valve according to the deviation of the current supercooling degree and the target supercooling degree, and realize the stable control of the supercooling degree in combination with the ratio of the condensing pressure to the critical pressure; the ratio of the condensing pressure to the critical pressure adopts a segmented suppression strategy, specifically including: when the condensing pressure is lower than the first pressure threshold, a first suppression coefficient is adopted; when the condensing pressure is between the first pressure threshold and the second pressure threshold, a second suppression coefficient is adopted; when the condensing pressure is higher than the second pressure threshold, a third suppression coefficient is adopted; wherein the first suppression coefficient is less than the second suppression coefficient, and the second suppression coefficient is less than the third suppression coefficient.

2. The low-temperature heat pump anti-liquid-pounding and supercooling enhancement control method based on dual-mode adaptive regulation according to claim 1, characterized in that, The nonlinear risk amplification mechanism is realized by introducing a high-order nonlinear term of the liquid impact risk index, which enhances the response strength of the system in the high-risk interval.

3. The low-temperature heat pump anti-liquid-penetration and supercooling enhancement control method based on dual-mode adaptive regulation according to claim 1, characterized in that, The heat capacity correction factor is calculated by monitoring the dynamic relationship between the heating input and the temperature rise response of the gas-liquid separator in a reverse deduction manner.

4. The low-temperature heat pump anti-liquid-penetration and supercooling enhancement control method based on dual-mode adaptive regulation according to claim 1, characterized in that, The pulse power excitation intensity is obtained based on a liquid strike risk index, specifically: when the liquid strike risk index is higher than a first risk threshold, a first frequency value is adopted; when the liquid strike risk index is between the first risk threshold and a second risk threshold, a second frequency value is adopted; and when the liquid strike risk index is lower than the second risk threshold, a third frequency value is adopted, wherein the first frequency value is greater than the second frequency value, and the second frequency value is greater than the third frequency value.

5. The low-temperature heat pump anti-liquid-penetration and supercooling enhancement control method based on dual-mode adaptive regulation according to claim 1, characterized in that, The system heat exchange response rate is obtained by calculating the rate of change of the difference between the evaporator inlet temperature and the condenser outlet temperature over time.

6. The low-temperature heat pump anti-liquid-spraying and supercooling enhancement control method based on dual-mode adaptive regulation according to claim 1, characterized in that, The liquid strike response decay factor is calculated by the ratio of the number of currently opened spray channels to the maximum number of channels, and the ratio of the current duty cycle to the maximum duty cycle.

7. The low-temperature heat pump anti-liquid-penetration and supercooling enhancement control method based on dual-mode adaptive regulation according to claim 1, characterized in that, When it is detected that the supercooling degree deviation is lower than the set threshold for X consecutive sampling periods, the system automatically locks the current economizer opening, and X is a preset value.

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