PTC regeneration bypass control method for window-type oxygen-enriched membrane fresh air complete machine

Abstract

This invention discloses a PTC regeneration bypass control method for window-type oxygen-enriched membrane fresh air systems, belonging to the field of air handling equipment control technology. The method includes: real-time monitoring of the oxygen-enriched membrane component performance degradation rate, dew point of the drying unit, indoor carbon dioxide concentration, and indoor-outdoor temperature difference; comprehensively determining the oxygen-enriched membrane performance degradation and the drying unit regeneration needs, and calculating and selecting the optimal time point with the least impact on the indoor environment to initiate regeneration, taking into account indoor air quality and heat load conditions; first switching to bypass ventilation mode to maintain basic air exchange, while simultaneously regenerating the drying unit and independently expelling moisture outdoors; and smoothly switching back to the original operating mode after regeneration is complete. This method solves the problems of improper regeneration timing, impact on indoor ventilation and comfort during regeneration, and high regeneration energy consumption in existing technologies, achieving efficient, energy-saving, and intelligent regeneration and maintenance of core consumables while ensuring continuous indoor air quality.

Description

Technical Field

[0001] This invention relates to the field of air handling equipment control technology, and in particular to a PTC regeneration bypass control method for window-type oxygen-enriched membrane fresh air units. Background Technology

[0002] As people's demands for indoor air quality continue to rise, integrated fresh air systems that combine ventilation, purification, oxygenation, and humidity control are increasingly being used. Among these, fresh air systems employing oxygen-enriched membrane modules can increase the oxygen concentration in the air supplied to the room through physical separation, providing healthier air for enclosed or poorly ventilated indoor environments. To ensure the efficient separation performance of the oxygen-enriched membrane, a pre-drying unit is typically required to deeply dehumidify the air entering the membrane module, as moisture affects the permeation selectivity of the membrane. However, the drying unit gradually absorbs moisture and becomes saturated during operation, leading to a decrease in dehumidification capacity. Therefore, periodic regeneration (i.e., desorption of moisture) is necessary to restore its function.

[0003] Currently, regeneration control is a critical and challenging aspect of fresh air systems integrating oxygen-enriched membranes and drying units. Common regeneration triggering methods are often based on a single condition, such as simply the operating time of the drying unit or a simple dew point threshold. This simple triggering mechanism has significant shortcomings, as it fails to consider the performance degradation of the oxygen-enriched membrane component itself. When the drying unit needs regeneration, the oxygen-enriched membrane may still be in good condition. The misalignment between regeneration requirements based on drying unit operating time and those based on dew point thresholds can lead to excessively frequent regenerations or delayed regeneration timing, which is detrimental to optimizing the overall energy efficiency and lifespan of core components.

[0004] The regeneration process itself typically requires temporary changes to the airflow path of the equipment. To heat and desorb the drying unit, the normal fresh air handling duct often needs to be shut off. Completely stopping ventilation during regeneration leads to an accumulation of indoor pollutants such as carbon dioxide, deteriorating air quality and impacting user experience. Simply introducing untreated (unenriched, undehumidified) outdoor air during regeneration, while maintaining ventilation, directly introduces hot or cold air into the room during extreme summer or winter temperatures, placing additional heating and cooling loads on the air conditioning system and significantly increasing building energy consumption. Existing regeneration control strategies rarely adequately consider the conflict between maintaining ventilation and avoiding additional energy consumption during regeneration, making it difficult to select the optimal regeneration timing. Existing regeneration process control is often rather crude. For example, the power control of the regeneration heater may use a fixed setting, failing to finely adjust according to the actual saturation level of the drying unit, resulting in excessively long regeneration times or high energy consumption. Improperly treated, humid and hot exhaust gases generated during regeneration may again affect the internal environment of the equipment and even indoor humidity. Furthermore, the process of switching from regeneration mode back to normal operation mode, without a smooth transition and rigorous verification, may cause airflow shocks, noise, or temporary operational instability. Existing technologies cannot solve the series of interrelated technical problems that arise during the operation of fresh air systems, such as the selection of regeneration timing, the balance between ventilation continuity and energy efficiency, and the refined control of the regeneration process. Therefore, it is necessary to design a more intelligent, coordinated, and efficient control method to address the challenge of balancing coordinated regeneration and continuous ventilation in the long-term operation of window-type oxygen-enriched membrane fresh air systems. Summary of the Invention

[0005] This invention overcomes the problems of improper timing of regeneration, impact on indoor ventilation and comfort during the regeneration process, and high energy consumption in the prior art. It achieves efficient, energy-saving, and intelligent regeneration and maintenance of core consumables while ensuring the continuity of indoor air quality.

[0006] To achieve the above objectives, the present invention adopts the following solution: A PTC regeneration bypass control method for a window-type oxygen-enriched membrane fresh air system, wherein the window-type oxygen-enriched membrane fresh air system includes an oxygen-enriched membrane module, a drying unit, a PTC heater, an oxygen-enriched membrane inlet solenoid valve, and a bypass ventilation duct, and the control method includes the following steps: S1: In purification mode or oxygenation mode, monitor the rate of change of outlet oxygen concentration of oxygen-enriched membrane module, current dew point of drying unit, indoor carbon dioxide concentration and indoor-outdoor temperature difference in real time. S2: Based on the comparison between the rate of change of the outlet oxygen concentration of the oxygen-enriched membrane module and the first preset threshold, determine whether the oxygen-enriched membrane module has entered the performance degradation stage; at the same time, based on the comparison between the current dew point of the drying unit and the second preset threshold, determine whether the drying unit needs to be regenerated; when the oxygen-enriched membrane module enters the performance degradation stage and the drying unit needs to be regenerated, calculate and determine the optimal time to start the regeneration program by combining whether the indoor carbon dioxide concentration exceeds the third preset threshold and whether the indoor and outdoor temperature difference exceeds the fourth preset threshold. S3: When the optimal time to start the regeneration program is reached, generate and execute the regeneration command: close the solenoid valve of the oxygen-enriched membrane air intake channel to cut off the airflow to the oxygen-enriched membrane module, and open the bypass ventilation duct to maintain indoor and outdoor ventilation. S4: With the bypass ventilation duct open, the PTC heater is turned on to heat and regenerate the drying unit. The heating power of the PTC heater is dynamically adjusted according to the difference between the current dew point of the drying unit and the second preset threshold. The high-temperature humid air generated during the regeneration process is discharged to the outdoor environment through an independent exhaust path. S5: Continuously monitor the current dew point of the drying unit. When the current dew point of the drying unit drops to the fifth preset threshold, the regeneration is determined to be complete. At this time, the PTC heater is turned off, the solenoid valve of the oxygen-enriched membrane air intake channel is opened, and the bypass ventilation duct is closed, so that the window-type oxygen-enriched membrane fresh air unit is restored to the purification mode or oxygenation mode.

[0007] Preferably, step S1 specifically includes: The raw oxygen concentration signal at the outlet of the oxygen-enriched membrane module is obtained by an oxygen concentration sensor installed at the outlet of the oxygen-enriched membrane module. At the same time, the ambient temperature and ambient pressure at the outlet of the oxygen-enriched membrane module are obtained by a temperature sensor and a pressure sensor installed at the same location. The raw oxygen concentration signal at the outlet is compensated in real time based on the ambient temperature and ambient pressure to obtain the oxygen concentration value at the outlet under standard conditions. The oxygen concentration value at the outlet under standard conditions is continuously collected at fixed time intervals, and the difference in oxygen concentration between adjacent time intervals is calculated. The first dew point value is obtained by directly measuring the dew point using a dew point sensor installed in the air outlet channel of the drying unit; the second dew point value is calculated by a temperature sensor and a relative humidity sensor installed in the air inlet channel of the drying unit; the first dew point value and the second dew point value are compared in real time, and if the absolute difference between the two exceeds a preset deviation threshold, calibration is performed, including zero-point calibration of the dew point sensor with dry nitrogen and range calibration of the dew point sensor with a saturated salt solution environment; after calibration, the first dew point value is reacquired as the current dew point of the drying unit; The raw indoor carbon dioxide concentration is continuously detected by a carbon dioxide sensor installed at the indoor return air vent, and the raw carbon dioxide concentration is processed by time-weighted averaging to obtain a stable monitoring value of indoor carbon dioxide concentration. The indoor temperature is obtained by a first temperature sensor installed on the indoor side wall, and the outdoor temperature is obtained by a second temperature sensor installed on the outdoor side wall, and the temperature difference between indoor and outdoor is calculated.

[0008] Preferably, in step S2, the method for determining whether the oxygen-enriched membrane module has entered the performance degradation stage includes: During the initial stable operation phase of the window-type oxygen-enriched membrane fresh air system, the baseline value of the initial outlet oxygen concentration change rate of the oxygen-enriched membrane module under standard operating conditions is recorded and stored. The standard operating conditions are determined based on the predefined range of inlet air temperature, inlet air humidity, and membrane pressure. During continuous operation in purification or oxygenation mode, the current outlet oxygen concentration change rate is acquired in real time, and the offset of the outlet oxygen concentration change rate is calculated based on the current outlet oxygen concentration change rate and the initial outlet oxygen concentration change rate baseline value. The offset is compared with a first preset threshold. If the absolute value of the offset continuously exceeds the dynamically adjusted first preset threshold for a preset number of consecutive judgment cycles, the oxygen-enriched membrane module is determined to have entered the performance degradation stage. The first preset threshold is determined by dynamic adjustment, and its absolute value decreases accordingly as the cumulative operating time of the oxygen-enriched membrane module increases. Before calculating the offset, the current outlet oxygen concentration change rate is first corrected based on the real-time monitored inlet air temperature, inlet air humidity, and membrane pressure to eliminate rate measurement deviations caused by short-term environmental parameter fluctuations.

[0009] Preferably, the method for determining whether the drying unit needs to be regenerated in step S2 includes: The system acquires the current dew point of the drying unit and compares it with a dynamically set second preset threshold. Simultaneously, it performs trend-based prediction logic: continuously collects current dew point data at multiple time points and uses the least squares method to perform linear fitting to obtain the slope of the current dew point change trend. If the current dew point exceeds the second preset threshold, or the slope of the current dew point change trend is continuously positive and greater than the preset slope threshold, the system determines that the drying unit needs to be regenerated. The second preset threshold is dynamically set based on the historical adsorption load status of the drying unit before the current regeneration cycle. The historical adsorption load status is quantified by calculating the product of the total air flow through the drying unit and its average moisture content from the completion of the last regeneration to the current time. If the historical adsorption load is higher than the set level, the second preset threshold is lowered accordingly; if the historical adsorption load is lower than the set level, the second preset threshold is raised accordingly.

[0010] Preferably, in step S2, the method for calculating and determining the optimal time to start the regeneration process specifically includes: When the system determines that the oxygen-enriched membrane module has entered the performance degradation stage and the drying unit needs to be regenerated, it acquires a stable monitoring value of indoor carbon dioxide concentration and a real-time monitoring value of the indoor and outdoor temperature difference. The stable monitoring value of indoor carbon dioxide concentration is compared with a dynamically corrected third preset threshold to obtain a first comparison result. At the same time, the indoor and outdoor temperature difference is compared with a fourth preset threshold selected according to the current seasonal pattern to obtain a second comparison result. Subsequently, the first and second comparison results are quantified into weighting factors and combined with a time-priority coefficient preset according to different times of the day, reflecting the power grid load or user habits, to calculate a comprehensive ventilation efficiency index. The optimal time point is determined based on whether the ventilation efficiency index exceeds a dynamically set start-up threshold. After the two conditions of the oxygen-enriched membrane module entering the performance degradation stage and the drying unit needing to be regenerated are met simultaneously, the ventilation efficiency index is continuously calculated and the first time point when it exceeds the start-up threshold is found. This time point is determined as the optimal time point to start the regeneration program. The third preset threshold is dynamically adjusted based on the real-time indoor activity intensity of people. The real-time indoor activity intensity is obtained by analyzing the signal frequency and distribution of infrared motion sensors deployed indoors. When the activity intensity increases, the third preset threshold is lowered. The fourth preset threshold is selected based on the current seasonal mode. In summer mode, the fourth preset threshold is reduced to reduce the additional cooling energy consumption caused by ventilation. In winter mode, the fourth preset threshold is increased to meet the sensitivity requirements of indoor air quality.

[0011] Preferably, step S3, which involves generating and executing the regeneration command, specifically includes: Once the system determines the optimal time to initiate the regeneration program, the main controller generates a sequence of regeneration instructions containing timing logic. The instruction sequence includes a closing instruction and an opening instruction. The closing instruction is sent to the drive circuit of the solenoid valve in the oxygen-enriched membrane intake channel via a digital signal line. The instruction is encoded with the target valve position being fully closed and the maximum allowable delay time. The opening instruction is sent to the damper actuator in the bypass ventilation duct via another independent digital signal line. The instruction is encoded with the target damper opening being fully open and the maximum allowable delay time. Before issuing the above two commands, the main controller first reduces the speed of the whole unit's ventilation fan to a preset transition speed; the closing command and the opening command are set to be sent simultaneously, and only after the valve position status feedback signal of the oxygen-enriched membrane air intake channel solenoid valve confirms that it has started to move towards the closed position is the bypass ventilation duct damper actuator allowed to start to move towards the open position.

[0012] Preferably, after the shutdown and startup commands are sent, the system executes a command verification and feedback mechanism, specifically including: Within the maximum allowed delay time of the instruction, the main controller continuously receives valve position status feedback signals from the solenoid valve of the oxygen-enriched membrane air intake channel and damper opening feedback signals from the bypass ventilation duct; it compares the received valve position status feedback signals with the target valve position status in the instruction, and simultaneously compares the received damper opening feedback signals with the target damper opening in the instruction; if both comparison results confirm that the actual state is consistent with the target state within the maximum delay time, the regeneration instruction is determined to have been executed successfully, the main controller records a success flag and allows entry into step S4; if either comparison result fails to confirm that the state is consistent within the maximum delay time, the instruction is determined to have failed; in the case of instruction execution failure, a backup switching strategy is initiated: the main controller immediately issues a shutdown command to the ventilation fan, and after the fan has completely stopped, it resends the original shutdown and start command sequences; if the backup switching strategy still fails after repeating the specified number of times, the system determines that there is a hardware failure, generates a fault alarm signal, locks the entire machine in a safe state, and terminates the current regeneration process, while attempting to restore the original operating mode before the instruction was executed.

[0013] Preferably, in step S4, the method of turning on the PTC heater and adjusting the heating power includes: After confirming that the bypass ventilation duct has been opened as instructed, the main controller sends a start command to the power drive module of the PTC heater, and the PTC heater starts working with the initial preheating power. The system continuously acquires the current dew point of the drying unit and calculates the real-time difference between the current dew point value and the second preset threshold. Using the real-time difference as the primary input parameter, a basic target heating power is calculated according to the built-in difference-power mapping table. At the same time, a real-time correction factor is obtained by analyzing the downward trend slope of the current dew point of the drying unit within a preset time window. If the downward trend slope is less than the expected value, the correction factor is increased to increase the target heating power; if the downward trend slope is greater than the expected value, the correction factor is decreased to decrease the target heating power. The basic target heating power is multiplied by the real-time correction factor to obtain the actual heating power command value of the PTC heater applied to the next control cycle.

[0014] Preferably, in step S4, the specific process of venting the high-temperature and humid air generated during the regeneration process to the outdoor environment through an independent exhaust path includes: The independent exhaust path consists of an independent exhaust fan and a dedicated duct isolated from the indoor environment. When the PTC heater starts, the exhaust fan starts simultaneously. The fan speed is linked to the actual heating power command value of the PTC heater and is adjusted proportionally to match the rate of regeneration moisture generation. A humidity sensor is installed at the outlet of the independent exhaust path to monitor the relative humidity of the exhaust gas. The monitored relative humidity of the exhaust gas is compared with an expected humidity range calculated based on the current PTC heater power and the intake humidity. If the monitored humidity is consistently lower than the lower limit of the expected range, a duct leakage suspicion flag is triggered, and the exhaust fan speed is increased to compensate. If the monitored humidity is consistently higher than the upper limit of the expected range and the current dew point of the drying unit decreases slowly, a low regeneration efficiency flag is triggered. If the actual heating power command value of the PTC heater has reached its maximum safe power limit and the duration exceeds the preset time, the main controller performs a regeneration mode switch: records the current state, then shuts down the PTC heater and the exhaust fan, switches the drying unit to a normal temperature purging mode driven by an internal circulation fan for a period of time, and then attempts to restart the PTC heating regeneration mode.

[0015] Preferably, step S5 specifically includes: During the regeneration process, the current dew point of the drying unit is continuously acquired at a fixed sampling period. When the current dew point first falls below the fifth preset threshold, a delay judgment timer is started. The current dew point is monitored during the timer's operation. If the current dew point remains below the fifth preset threshold and does not show a rebound upward trend during the timer's operation, the regeneration is officially determined to be complete. If the current dew point rebounds and exceeds the fifth preset threshold during the timer's operation, the timer is reset and the regeneration process continues. After regeneration is completed, a sequential recovery operation is performed: First, a step-down power reduction command is sent to the power drive module of the PTC heater, causing the heating power to gradually decrease to zero according to a preset curve over multiple control cycles, and then a shutdown command is sent; at the same time as the PTC heater power begins to decrease, a synchronous speed reduction command is sent to the exhaust fan of the independent exhaust path, causing its speed to decrease proportionally with the decrease in heating power; after confirming that the PTC heater has been shut down and the exhaust fan has stopped, a recovery command sequence is generated and sent, including simultaneously sending an opening command to the solenoid valve of the oxygen-enriched membrane air intake channel and a closing command to the damper actuator of the bypass ventilation duct; after the system monitors and confirms that the valve position status feedback signal of the solenoid valve of the oxygen-enriched membrane air intake channel is fully open and the damper opening feedback signal of the bypass ventilation duct is fully closed, the speed of the ventilation fan is gradually increased from the transition speed to the set speed of the corresponding purification mode or oxygenation mode; After the recovery process is completed, record the complete data of this regeneration process, including the regeneration duration, final dew point value and cumulative energy consumption; the fifth preset threshold is calculated and dynamically updated through a linear regression model, specifically set as the cumulative energy consumption of the PTC heater in the current regeneration cycle and the initial dew point value of the drying unit at the start of regeneration.

[0016] The present invention has at least the following beneficial effects: (1) By using multi-parameter fusion judgment and comprehensive decision-making, intelligent selection of the regeneration start-up timing is realized. It can not only accurately identify the real regeneration needs of the core components of the equipment, but also reduce the negative impact of regeneration behavior on indoor air quality comfort and building heat load to a low level. Regeneration is started under the premise of ensuring basic ventilation continuity, which improves user experience and overall system energy efficiency; (2) By using a high-precision, multi-redundant sensor system with self-calibration function to monitor key parameters, and combined with a dynamic performance degradation judgment algorithm based on historical benchmarks and environmental compensation, a highly reliable and accurate data foundation is provided for the entire control decision. This significantly improves the sensitivity and reliability of judging the performance degradation of the oxygen-enriched membrane component and the saturation state of the drying unit, effectively avoiding misjudgment and omission, making regeneration triggering more accurate and necessary; (3) By designing a refined instruction sequence that includes preparatory actions, timing logic, real-time feedback verification and fault handling strategies, the extremely high reliability and stability of the air path switching and recovery process are ensured. The system not only achieves a seamless transition between working mode and regeneration mode, reducing disturbance to the indoor environment, but also significantly improves the robustness and safety of system operation through a rigorous fault diagnosis and safety protection mechanism; (4) By introducing dynamic threshold setting, trend prediction, adaptive adjustment of heating power and exhaust linkage, and an anomaly handling mechanism based on real-time effect monitoring, the regeneration process itself is deeply optimized, enabling the regeneration process to intelligently adapt to different environmental conditions and equipment status. While ensuring the regeneration effect, the regeneration speed and thermal energy utilization efficiency are significantly improved, and the overall energy consumption is effectively reduced; (5) By adopting a delayed trend judgment regeneration completion, sequential smooth recovery operation, and dynamic self-learning update strategy for key judgment thresholds, the system ensures that each regeneration achieves a stable and reliable effect, and enables the system to continuously optimize itself as the running time accumulates, extending the effective life of the core components of the equipment, and making the long-term operation behavior of the system increasingly consistent with the actual use scenario, reflecting a high level of intelligence. Attached Figure Description

[0017] Figure 1 This is a schematic diagram illustrating the principle of the control method provided by the present invention. Detailed Implementation

[0018] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0019] like Figure 1 The diagram shown is a schematic diagram of the PTC regeneration bypass control method for a window-type oxygen-enriched membrane fresh air unit provided by the present invention.

[0020] A window-type oxygen-enriched membrane fresh air unit is a composite air handling device integrated into a window or exterior wall for uninterrupted ventilation, while simultaneously increasing the oxygen concentration and regulating the humidity of the incoming air. It includes an oxygen-enriched membrane module, a drying unit, a PTC heater, an oxygen-enriched membrane inlet solenoid valve, and a bypass ventilation duct. Within a limited space, it integrates air pretreatment, selective gas separation, humidity control, and component self-regeneration functions through a compact modular layout. The unit typically includes a casing, a fan system, a filter unit, a control module, and several core functional components. These components, coordinated by a unified main controller, intelligently switch between at least two main operating modes—"purification / oxygenation" and "regeneration"—based on indoor and outdoor environmental parameters and the equipment's own status, thereby achieving a balance between continuously providing high-quality fresh air and ensuring the equipment's self-maintenance.

[0021] Oxygen-enriched membrane modules are composed of hollow fiber membranes or flat sheet membranes, with different permeation rates for oxygen and nitrogen. When pressurized humid air flows through one side of the membrane, oxygen molecules, due to their smaller molecular size and higher solubility-diffusion coefficient, preferentially permeate through the membrane wall, thus accumulating on the other side (the permeate side) to form an oxygen-enriched airflow. Nitrogen and most water vapor are retained on the other side (the permeate side) and discharged as waste gas or treated separately. The performance of this module directly determines the level of oxygen concentration enhancement in the outlet air. However, its separation efficiency is sensitive to inlet air humidity and inlet membrane pressure, and long-term operation may lead to membrane surface fouling or physical aging, resulting in a decrease in oxygen permeation rate. Therefore, pre-protection and regular condition monitoring are necessary.

[0022] The drying unit is a crucial pre-treatment module ensuring the efficient and stable operation of the oxygen-enriched membrane module. It dehumidifies the air entering the module, lowering the dew point to a very low level. This function is achieved through adsorption dehumidification, with the unit filled with high-performance solid adsorbents such as molecular sieves, silica gel, or composite drying materials. When humid air flows through the adsorbent bed, water molecules are selectively adsorbed, and the dried air is then output to the subsequent oxygen-enriched membrane module. As the adsorption process continues, the adsorbent gradually becomes saturated, its dehumidification capacity decreases, and the outlet air dew point increases. Therefore, the drying unit must be regenerated periodically, i.e., by desorbing the adsorbed moisture through methods such as heating, restoring its drying capacity. The regeneration frequency and effectiveness of the drying unit directly affect the lifespan of the oxygen-enriched membrane and the overall energy consumption of the system.

[0023] The PTC heater is a specialized electric heating element that provides a heat source for the regeneration of the drying unit. PTC (Positive Temperature Coefficient) material has the characteristic that its resistance increases significantly with increasing temperature, giving the PTC heater a self-limiting temperature characteristic: when the temperature reaches near its Curie point, the resistance increases sharply, and the current automatically decreases, thereby limiting the heating temperature, preventing overheating, and ensuring high safety. In the overall system, the PTC heater is integrated around or inside the air duct of the drying unit. It activates in regeneration mode to heat the adsorbent, providing the energy required for moisture desorption. Its heating power can be adjusted according to regeneration needs to achieve energy efficiency optimization.

[0024] The oxygen-enriched membrane inlet solenoid valve is an airflow switching device controlled by the main controller, installed on the main inlet channel leading to the oxygen-enriched membrane module. In normal purification or oxygenation mode, this solenoid valve is open, allowing dried air to smoothly enter the oxygen-enriched membrane module. When the system determines that the drying unit needs to be regenerated, the main controller sends a command to close this solenoid valve. Its valve core actuates (e.g., driven by electromagnetic force) to mechanically cut off the airflow path, isolating the oxygen-enriched membrane module during regeneration and preventing the entry of undried humid air (or hot, humid airflow during regeneration).

[0025] The bypass ventilation duct is a backup airflow path designed to address indoor ventilation interruptions during regeneration. It's an independent duct separate from the main "drying-oxygen enrichment" treatment path, with one end connected to the outdoor fresh air inlet (usually after primary filtration) and the other end directly connected to the indoor air supply vent. This duct is equipped with a controlled damper (driven by a stepper motor or micro servo motor). In normal mode, this damper is closed, and all airflow passes through the main treatment path. When the main path is interrupted due to regeneration (solenoid valve closed), the main controller commands this damper to open, allowing outdoor air to be delivered directly into the room through this bypass ventilation duct without undergoing drying and oxygen enrichment treatment. Although the air delivered at this time is untreated, basic ventilation is maintained, preventing indoor carbon dioxide buildup and ensuring minimum air quality. The opening and closing of the bypass ventilation duct must be precisely coordinated with the operation of the main path solenoid valve to achieve seamless airflow switching.

[0026] The control method includes the following steps: S1: In purification mode or oxygenation mode, monitor in real time the rate of change of oxygen concentration at the outlet of the oxygen-enriched membrane module, the current dew point of the drying unit, the indoor carbon dioxide concentration, and the temperature difference between indoors and outdoors.

[0027] The system monitors at least four key parameters in real time during purification or oxygenation modes: the rate of change of oxygen concentration at the outlet of the oxygen-enriched membrane module, the current dew point of the drying unit, the indoor carbon dioxide concentration, and the indoor-outdoor temperature difference. The rate of change of outlet oxygen concentration reflects the change in the separation performance of the oxygen-enriched membrane over time. It is collected in real time by an oxygen concentration sensor located at the membrane module outlet and compensated for temperature and pressure to obtain an accurate value. This rate can be used to determine whether the membrane module's oxygen permeability has decreased due to contamination or aging. The current dew point of the drying unit directly characterizes its saturation level after adsorbing moisture. A higher dew point indicates a higher moisture content in the desiccant and a weaker dehumidification capacity, requiring regeneration to restore its function. Indoor carbon dioxide concentration, as one of the core indicators for measuring indoor air quality, reflects the intensity of human activity and the urgency of ventilation needs. The indoor-outdoor temperature difference affects the heat load generated by ventilation; for example, directly introducing outdoor air during high summer temperatures or low winter temperatures may lead to additional cooling or heating energy consumption. Simultaneous monitoring of these parameters provides a multi-dimensional data foundation for subsequently determining the timing of regeneration initiation, ensuring that the regeneration process is neither started too early, resulting in energy waste, nor executed too late, affecting overall system performance.

[0028] S2: Based on the comparison between the rate of change of the outlet oxygen concentration of the oxygen-enriched membrane module and the first preset threshold, determine whether the oxygen-enriched membrane module has entered the performance degradation stage; at the same time, based on the comparison between the current dew point of the drying unit and the second preset threshold, determine whether the drying unit needs to be regenerated; when the oxygen-enriched membrane module enters the performance degradation stage and the drying unit needs to be regenerated, calculate and determine the optimal time to start the regeneration program by combining whether the indoor carbon dioxide concentration exceeds the third preset threshold and whether the indoor and outdoor temperature difference exceeds the fourth preset threshold.

[0029] The rate of change of oxygen concentration at the outlet of the oxygen-enriched membrane module is compared with a first preset threshold, which is a value between 5% and 10% per minute that represents the initial stable value of the oxygen concentration. This threshold can be adjusted based on the characteristics of the membrane material and the operating environment. If the rate consistently exceeds this first preset threshold, it indicates that the oxygen-enriched membrane module may be entering a performance degradation phase, and its separation efficiency is insufficient to maintain the expected oxygenation effect. Simultaneously, the current dew point of the drying unit is compared with a second preset threshold, which can be set between -10℃ and 0℃. If the current dew point is higher than this value, it indicates that the drying unit is close to saturation in adsorbing moisture, its dehumidification capacity has significantly decreased, and regeneration is required. Under the premise that both conditions are met, the system further combines whether the indoor carbon dioxide concentration exceeds a third preset threshold (e.g., adjustable within the range of 800ppm to 1200ppm) and whether the indoor and outdoor temperature difference exceeds a fourth preset threshold (e.g., set to 5℃ in summer mode and 10℃ in winter mode) to comprehensively calculate and determine the optimal time to start the regeneration program. The core of this judgment logic is that the regeneration process requires temporarily switching the air path and activating heating. In order to avoid significantly affecting indoor environmental comfort and air quality, the system will choose to regenerate when the indoor air quality is acceptable and the ventilation heat load is low, thereby achieving a balance between energy efficiency and air quality.

[0030] S3: When the optimal time to start the regeneration program is reached, a regeneration command is generated and executed: the solenoid valve of the oxygen-enriched membrane intake channel is closed to cut off the airflow to the oxygen-enriched membrane module, while the bypass ventilation duct is opened to maintain indoor and outdoor ventilation.

[0031] Once the system determines that the optimal regeneration start-up time has been reached, it generates and executes a regeneration command. This command includes closing the solenoid valve of the oxygen-enriched membrane inlet channel to cut off the airflow to the oxygen-enriched membrane module, preventing undried humid air from entering the membrane module and causing damage during regeneration; simultaneously, it opens the bypass ventilation duct, allowing outdoor air to flow directly into the room without passing through the oxygen-enriched membrane and drying unit, thereby maintaining basic ventilation and avoiding indoor stuffiness or increased carbon dioxide concentration due to the regeneration process. In this step, the switching of the airflow path needs to be rapid and coordinated, achieved by the main controller synchronously sending control signals to the solenoid valve drive circuit and damper actuator, ensuring that the bypass ventilation duct opens in a timely manner while the oxygen-enriched membrane path is cut off, achieving a seamless transition in ventilation function.

[0032] S4: With the bypass ventilation duct open, the PTC heater is turned on to heat and regenerate the drying unit. The heating power of the PTC heater is dynamically adjusted according to the difference between the current dew point of the drying unit and the second preset threshold. The high-temperature humid air generated during the regeneration process is discharged to the outdoor environment through an independent exhaust path.

[0033] With the bypass ventilation duct open, the system activates the PTC heater to regenerate the drying unit. Due to its self-limiting temperature characteristics, the PTC heater automatically adjusts its power during heating to avoid overheating risks, making it suitable for desiccant desorption and regeneration. The heating power is dynamically adjusted based on the difference between the current dew point of the drying unit and a second preset threshold; for example, if the current dew point is significantly higher than the threshold, the system can increase the heating power to accelerate desorption, and vice versa to save energy. The high-temperature, humid air generated during regeneration is directly exhausted to the outdoor environment through an independent exhaust path, completely isolated from the indoor air to prevent moisture backflow from affecting indoor humidity or causing secondary pollution. This design ensures both effective regeneration and maintains the independence and stability of the indoor environment.

[0034] S5: Continuously monitor the current dew point of the drying unit. When the current dew point of the drying unit drops to the fifth preset threshold, the regeneration is determined to be complete. At this time, the PTC heater is turned off, the solenoid valve of the oxygen-enriched membrane air intake channel is opened, and the bypass ventilation duct is closed, so that the window-type oxygen-enriched membrane fresh air unit is restored to the purification mode or oxygenation mode.

[0035] During regeneration, the system continuously monitors the current dew point of the drying unit. When it drops to the fifth preset threshold (e.g., a value between -30℃ and -20℃), regeneration is considered complete. At this point, the system shuts off the PTC heater, stopping heating; simultaneously, it opens the solenoid valve of the oxygen-enriched membrane inlet channel, closes the bypass ventilation duct, and switches the airflow back to normal purification or oxygenation mode, restoring the unit to its original function. This step also includes a certain delay or trend judgment logic. For example, after the dew point reaches the threshold, monitoring continues for a period of time to confirm that it no longer rebounds before finally determining that regeneration is complete, thereby improving the reliability of the judgment and avoiding premature termination of regeneration due to measurement fluctuations.

[0036] Compared to existing regeneration control methods that often employ timed regeneration or single-parameter triggering, this method significantly improves the intelligence and overall energy efficiency of the regeneration process through multi-parameter fusion judgment and dynamic timing selection. On one hand, the system can accurately identify the real-time status of the oxygen-enriched membrane and drying unit, avoiding unnecessary regeneration cycles and extending component lifespan. On the other hand, by incorporating indoor air quality and temperature difference parameters for timing optimization, it reduces interference with indoor comfort during regeneration and lowers the additional heat load caused by ventilation. Furthermore, the bypass ventilation duct design ensures uninterrupted indoor ventilation during regeneration, enhancing the user experience, while the dynamic power adjustment and independent dehumidification path of the PTC heater further enhance the safety and efficiency of the regeneration process. Overall, this method achieves efficient, energy-saving, and reliable long-term operation of the equipment while maintaining indoor air quality.

[0037] In another technical solution, step S1 specifically includes: The raw oxygen concentration signal at the outlet of the oxygen-enriched membrane module is obtained by an oxygen concentration sensor installed at the outlet of the oxygen-enriched membrane module. At the same time, the ambient temperature and ambient pressure at the outlet of the oxygen-enriched membrane module are obtained by a temperature sensor and a pressure sensor installed at the same location. The raw oxygen concentration signal at the outlet is compensated in real time based on the ambient temperature and ambient pressure to obtain the oxygen concentration value at the outlet under standard conditions. The oxygen concentration value at the outlet under standard conditions is continuously collected at fixed time intervals, and the difference in oxygen concentration between adjacent time intervals is calculated. The first dew point value is obtained by directly measuring the dew point using a dew point sensor installed in the air outlet channel of the drying unit; the second dew point value is calculated by a temperature sensor and a relative humidity sensor installed in the air inlet channel of the drying unit; the first dew point value and the second dew point value are compared in real time, and if the absolute difference between the two exceeds a preset deviation threshold, calibration is performed, including zero-point calibration of the dew point sensor with dry nitrogen and range calibration of the dew point sensor with a saturated salt solution environment; after calibration, the first dew point value is reacquired as the current dew point of the drying unit; The raw indoor carbon dioxide concentration is continuously detected by a carbon dioxide sensor installed at the indoor return air vent, and the raw carbon dioxide concentration is processed by time-weighted averaging to obtain a stable monitoring value of indoor carbon dioxide concentration. The indoor temperature is obtained by a first temperature sensor installed on the indoor side wall, and the outdoor temperature is obtained by a second temperature sensor installed on the outdoor side wall, and the temperature difference between indoor and outdoor is calculated.

[0038] In the oxygen concentration monitoring section, the system acquires the raw signal through an oxygen concentration sensor located at the outlet of the oxygen-enriched membrane module. This sensor typically operates based on electrochemical or optical principles, responding to changes in oxygen partial pressure and outputting a corresponding electrical signal. Since the sensor output is affected by ambient temperature and pressure, the system also includes temperature and pressure sensors at the same location to capture real-time environmental conditions. Based on these parameters, the system performs real-time compensation calculations on the raw oxygen concentration signal. For example, it uses a built-in compensation algorithm to correct the measured values ​​to those at standard temperatures (e.g., 25°C) and standard pressures (e.g., 101.3 kPa), thereby eliminating measurement deviations caused by environmental fluctuations and obtaining more accurate and comparable standard-state outlet oxygen concentration values. To calculate the rate of change, the system continuously acquires these corrected concentration values ​​at fixed time intervals (e.g., every 1 to 5 seconds) and calculates the concentration difference between adjacent time points to obtain the instantaneous trend of oxygen concentration changes in real time, providing a high-precision data foundation for subsequent assessment of membrane module performance.

[0039] In terms of dew point monitoring in the drying unit, the system employs a combination of redundant measurement and real-time calibration to ensure the reliability of dew point data. First, a first dew point measurement is obtained through a dew point sensor (either a cold mirror or capacitive sensor) directly installed in the drying unit's outlet channel. This value directly reflects the moisture content of the air after drying. Simultaneously, the system indirectly calculates a second dew point value using temperature and relative humidity sensors installed in the drying unit's inlet channel, based on known temperature-humidity-dew point conversion relationships (e.g., approximate calculations using the Magnus formula). Ideally, these two values ​​should be close. The system continuously compares these two values. If the absolute difference exceeds a preset deviation threshold (e.g., 0.5℃ to 2℃), it determines that the directly measured dew point sensor may be drifting or contaminated, triggering a calibration procedure. During calibration, the system first guides dried nitrogen through the sensor for zero-point calibration, then exposes it to a constant humidity environment created by a specific saturated salt solution for range calibration. After completion, the first dew point measurement is re-acquired as the final reliable value for the current dew point. This dual-path verification and automatic calibration mechanism greatly improves the long-term stability and accuracy of key humidity parameter measurements.

[0040] For monitoring indoor carbon dioxide concentration and the indoor-outdoor temperature difference, the system also employs a data stability-focused processing strategy. Indoor carbon dioxide concentration is continuously monitored by an infrared carbon dioxide sensor installed at the indoor return air vent. This sensor calculates the carbon dioxide concentration by measuring the absorption of infrared light at a specific wavelength. To avoid misleading judgments due to momentary fluctuations caused by brief human activity or the opening and closing of doors and windows, the system performs time-weighted averaging on the collected raw concentration values. For example, it uses the average value within a sliding time window (e.g., 5 to 15 minutes) as a stable monitoring value, which better reflects the overall trend of indoor air quality. The indoor-outdoor temperature difference is obtained using two high-precision temperature sensors installed on the indoor and outdoor side walls, respectively. The installation locations are typically designed to avoid direct sunlight and localized heat sources to obtain representative air temperatures. The system calculates the difference between these two temperatures in real time. This parameter is directly related to the heat load brought by the introduction of fresh air and is a key input for assessing ventilation energy consumption costs.

[0041] By employing the aforementioned techniques of multi-sensor fusion, real-time compensation and calibration, and data smoothing, this method effectively overcomes problems such as the cross-influence of environmental parameters, long-term sensor drift, and random fluctuations in measurement signals, compared to traditional methods that rely solely on raw readings from a single sensor. This makes the assessment of the rate of change in oxygen-enriched membrane performance, desiccant status, indoor air quality, and heat load potential more reliable and accurate. It reduces the risk of false triggering, missed triggering, or inappropriate timing selection due to inaccurate data at the source, thereby improving the intelligence and reliability of the entire control system's decision-making.

[0042] In another technical solution, step S2, determining whether the oxygen-enriched membrane module has entered the performance degradation stage includes: During the initial stable operation phase of the window-type oxygen-enriched membrane fresh air system, the baseline value of the initial outlet oxygen concentration change rate of the oxygen-enriched membrane module under standard operating conditions is recorded and stored. The standard operating conditions are determined based on the predefined range of inlet air temperature, inlet air humidity, and membrane pressure. During continuous operation in purification or oxygenation mode, the current outlet oxygen concentration change rate is acquired in real time, and the offset of the outlet oxygen concentration change rate is calculated based on the current outlet oxygen concentration change rate and the initial outlet oxygen concentration change rate baseline value. The offset is compared with a first preset threshold. If the absolute value of the offset continuously exceeds the dynamically adjusted first preset threshold for a preset number of consecutive judgment cycles, the oxygen-enriched membrane module is determined to have entered the performance degradation stage. The first preset threshold is determined by dynamic adjustment, and its absolute value decreases accordingly as the cumulative operating time of the oxygen-enriched membrane module increases. Before calculating the offset, the current outlet oxygen concentration change rate is first corrected based on the real-time monitored inlet air temperature, inlet air humidity, and membrane pressure to eliminate rate measurement deviations caused by short-term environmental parameter fluctuations.

[0043] In the initial stage of establishing the performance degradation judgment benchmark, the system automatically records and stores the initial outlet oxygen concentration change rate benchmark value of the oxygen-enriched membrane module under standard operating conditions during the initial stable operation phase (e.g., continuous stable operation for 24 to 48 hours) after the entire unit is installed and commissioned or after each maintenance. Here, the standard operating condition is not a single condition, but rather a range of one or more stable operating intervals defined by predefined inlet air temperature ranges (e.g., 10°C to 30°C), inlet air humidity ranges (e.g., 30%RH to 70%RH), and membrane inlet pressure ranges (e.g., a specific range close to atmospheric pressure). Only data collected when these environmental parameters are simultaneously met is recognized and used to calculate the initial benchmark. This ensures that the benchmark value is obtained under controlled conditions where the membrane module performance is optimal, and has high representativeness and comparability. During real-time judgment, the system continuously acquires the current outlet oxygen concentration change rate. However, before this, a secondary correction is performed on the current rate based on the real-time monitored inlet air temperature, inlet air humidity, and membrane inlet pressure. For example, an empirical coefficient model reflecting the impact of these environmental parameters on the membrane permeation rate is used to eliminate rate measurement deviations caused by short-term environmental fluctuations (such as a sudden humid air or slight changes in air pressure), thereby extracting a more accurate post-purification rate value that reflects the membrane's own state changes. Subsequently, the system calculates the offset between this corrected current rate and the stored initial baseline value. The first preset threshold is dynamically adjusted, with its absolute value decreasing as the cumulative operating time of the oxygen-enriched membrane module increases. For example, the threshold is set more leniently in the early stages of operation, but gradually tightens after several thousand hours of operation. This design takes into account that the membrane module's performance degradation sensitivity increases with usage time; slight changes may indicate significant aging, thus requiring stricter monitoring. Logically, the system requires that the absolute value of the offset must continuously exceed this dynamically adjusted first preset threshold and reach a preset number of consecutive judgment cycles (e.g., 5 to 10 consecutive calculation cycles) before finally determining that the oxygen-enriched membrane module has entered the performance degradation stage. This continuous requirement effectively filters out occasional, short-term performance fluctuations, avoiding false alarms. The entire judgment process forms a complete closed loop, from benchmark establishment, real-time monitoring, environmental interference elimination to dynamic threshold comparison. It doesn't simply compare a single reading at a particular moment, but makes a comprehensive judgment based on historical benchmarks, the current state after environmental compensation, and judgment criteria that change over time. Compared to simple judgment methods that use fixed thresholds and ignore operational history and environmental interference, the performance degradation judgment method provided by this solution significantly improves the accuracy and adaptability of the judgment.By establishing an initial benchmark based on standard operating conditions, the objectivity and fairness of the judgment starting point are ensured. The introduction of secondary correction using environmental parameters effectively shields the interpretation of core performance indicators from short-term external fluctuations, allowing the system to focus on the true changes in the membrane module's own state. Furthermore, the dynamically adjusted first preset threshold enables the system to intelligently adapt to the aging characteristics of the membrane module at different stages throughout its lifespan. This ensures that the early warning mechanism avoids oversensitivity in the new membrane stage while maintaining sufficient awareness of performance decline in older membranes. This comprehensive judgment strategy significantly reduces the false and false alarm rates of performance degradation, making the triggering of the regeneration process more reasonable and necessary. This facilitates timely maintenance, thereby extending the effective service life of the membrane module and maintaining the long-term stability of the overall system performance.

[0044] In another technical solution, the method for determining whether the drying unit needs regeneration in step S2 includes: The system acquires the current dew point of the drying unit and compares it with a dynamically set second preset threshold. Simultaneously, it performs trend-based prediction logic: continuously collects current dew point data at multiple time points and uses the least squares method to perform linear fitting to obtain the slope of the current dew point change trend. If the current dew point exceeds the second preset threshold, or the slope of the current dew point change trend is continuously positive and greater than the preset slope threshold, the system determines that the drying unit needs to be regenerated. The second preset threshold is dynamically set based on the historical adsorption load status of the drying unit before the current regeneration cycle. The historical adsorption load status is quantified by calculating the product of the total air flow through the drying unit and its average moisture content from the completion of the last regeneration to the current time. If the historical adsorption load is higher than the set level, the second preset threshold is lowered accordingly; if the historical adsorption load is lower than the set level, the second preset threshold is raised accordingly.

[0045] In determining the regeneration requirement of the drying unit, the system employs a dual-criteria logic based on both the current state and the changing trend. The basic criterion is a direct comparison between the current dew point of the drying unit and a second preset threshold. For example, this threshold might be set between -15°C and -5°C. If the current dew point is higher than this threshold, it indicates that the desiccant's adsorbed moisture has approached its capacity, and the dehumidification efficiency has significantly decreased. Based on this, the system initially determines that regeneration needs to be initiated. Simultaneously, the system performs a more forward-looking trend-based prediction. It continuously collects current dew point data at multiple time points over a period of time (e.g., the past 30 minutes to 2 hours) and uses the least squares method to perform linear fitting on these data, thereby calculating the slope of the current dew point's change over time. This slope value directly reflects the rate at which the desiccant becomes saturated with moisture. The system monitors this slope. If it remains positive (meaning the dew point is rising) and exceeds a preset slope threshold (e.g., rising 0.5°C to 2°C per hour), the system will predict that the drying unit is rapidly approaching saturation, even if the current dew point has not yet exceeded a second preset threshold, thus determining in advance that regeneration is needed. This trend prediction mechanism gives the system a certain degree of foresight, helping to plan regeneration before a substantial decline in drying performance and avoiding impacts on subsequent gas supply quality due to response lag.

[0046] The second preset threshold is not a fixed value, but is dynamically set based on the actual workload experienced by the drying unit before the current regeneration cycle. This makes the judgment criteria more personalized and adaptable. The system quantifies the historical adsorption load by calculating the product of the total airflow through the drying unit and its average moisture content during the period from the completion of the last regeneration to the current moment. The total airflow can be obtained by integrating the wind speed sensor in the air duct, while the average moisture content is calculated from the temperature and humidity sensor data at the air inlet. If the calculated historical adsorption load is higher than a certain set level (e.g., corresponding to long-term high humidity operation), it means that the desiccant has adsorbed a large amount of moisture in this cycle, and its performance may degrade faster. Therefore, the system will lower the second preset threshold accordingly, making the regeneration judgment more sensitive and earlier. Conversely, if the historical adsorption load is low (e.g., corresponding to dry seasons or low ventilation operation), the system will raise the second preset threshold accordingly, allowing the drying unit to continue operating at a higher dew point, thereby avoiding unnecessary frequent regeneration and saving energy. This strategy of dynamically adjusting the threshold based on the working history enables the system to intelligently adapt to different climatic conditions and usage intensity.

[0047] In practical implementation, the system operates two decision paths in parallel: threshold comparison and trend analysis. Regeneration is triggered when the conditions of either path are met, or a comprehensive score can be achieved by assigning different weights. Furthermore, the system may introduce a safety margin. For example, after trend prediction triggers, if the current dew point is still far below the threshold, the system enters an "early warning observation" state, increasing monitoring frequency instead of immediately executing regeneration, thus achieving a balance between predictability and stability. This comprehensive decision-making method ensures that the timing of the dryer unit's regeneration is neither too conservative, leading to energy waste and component wear, nor too aggressive, affecting the overall dehumidification and the normal operation of the subsequent oxygen-enriching membrane. By combining real-time threshold comparison and trend analysis, and introducing dynamic threshold settings based on historical loads, a more accurate and intelligent assessment of the desiccant's state is achieved. Compared to traditional methods relying solely on a single fixed dew point threshold, this method significantly enhances the predictability of dryer unit performance degradation, enabling earlier identification of potential saturation trends. This allows the system to plan regeneration in advance, avoiding the risk of excessive air humidity due to sudden insufficient drying capacity. Meanwhile, the dynamic threshold mechanism enables the system to automatically adjust the judgment criteria according to the actual usage environment. Under humid and high-load conditions, it adopts a more conservative strategy to ensure performance, while under dry and low-load conditions, it adopts a more economical strategy to reduce energy consumption. Thus, while ensuring the core functions, it optimizes the overall operating energy efficiency and the service life of the drying unit.

[0048] In another technical solution, step S2, specifically calculating and determining the optimal time to start the regeneration process, includes: When the system determines that the oxygen-enriched membrane module has entered the performance degradation stage and the drying unit needs to be regenerated, it acquires a stable monitoring value of indoor carbon dioxide concentration and a real-time monitoring value of the indoor and outdoor temperature difference. The stable monitoring value of indoor carbon dioxide concentration is compared with a dynamically corrected third preset threshold to obtain a first comparison result. At the same time, the indoor and outdoor temperature difference is compared with a fourth preset threshold selected according to the current seasonal pattern to obtain a second comparison result. Subsequently, the first and second comparison results are quantified into weighting factors and combined with a time-priority coefficient preset according to different times of the day, reflecting the power grid load or user habits, to calculate a comprehensive ventilation efficiency index. The optimal time point is determined based on whether the ventilation efficiency index exceeds a dynamically set start-up threshold. After the two conditions of the oxygen-enriched membrane module entering the performance degradation stage and the drying unit needing to be regenerated are met simultaneously, the ventilation efficiency index is continuously calculated and the first time point when it exceeds the start-up threshold is found. This time point is determined as the optimal time point to start the regeneration program. The third preset threshold is dynamically adjusted based on the real-time indoor activity intensity of people. The real-time indoor activity intensity is obtained by analyzing the signal frequency and distribution of infrared motion sensors deployed indoors. When the activity intensity increases, the third preset threshold is lowered. The fourth preset threshold is selected based on the current seasonal mode. In summer mode, the fourth preset threshold is reduced to reduce the additional cooling energy consumption caused by ventilation. In winter mode, the fourth preset threshold is increased to meet the sensitivity requirements of indoor air quality.

[0049] After determining the two necessary conditions—the degradation of the oxygen-enriched membrane performance and the need for regeneration of the drying unit—the system does not immediately initiate the regeneration process. Instead, it enters a relatively refined timing optimization calculation phase to determine the optimal start-up time that minimizes the impact on the indoor environment and maximizes energy efficiency. First, the system acquires stable monitoring values ​​of the indoor carbon dioxide concentration and calculates the real-time indoor-outdoor temperature difference. Next, the carbon dioxide concentration value is compared with a dynamically corrected third preset threshold. For example, this base threshold might be set around 1000 ppm, but it will be adjusted upwards or downwards based on the real-time intensity of indoor human activity. Simultaneously, the indoor-outdoor temperature difference is compared with a fourth preset threshold selected based on the current seasonal pattern (summer or winter). This threshold might be set at a lower value of 3°C to 8°C in summer and a higher value of 8°C to 15°C in winter. These two comparison results reflect the urgency of indoor air quality at the current moment and the potential heat load from ventilation, respectively. Subsequently, the system quantifies these two comparison results, converting them into calculable weighting factors. For example, the extent to which the carbon dioxide concentration exceeds the threshold and the extent to which the temperature difference exceeds the threshold can be mapped to a score between 0 and 1 or a specific level, respectively. Then, these weighting factors reflecting environmental conditions are combined with a pre-defined time-period priority coefficient. This time-period coefficient reflects factors such as peak and off-peak grid loads (e.g., high priority during off-peak hours at night) or user habits (e.g., high priority during days when no one is home). The system calculates a comprehensive ventilation efficiency index using a built-in algorithm model (e.g., weighted summation or a more complex multi-objective function). The level of this index represents the comprehensive benefit of initiating regeneration (accompanied by bypass ventilation) at the current moment; a higher index means a greater positive effect of ventilation (e.g., improved air quality) and a smaller negative cost (e.g., heat load energy consumption). The system sets a dynamic initiation threshold, which can be fine-tuned based on historical operating data or user settings. After the conditions are met, the system continuously calculates the index and finds the point at which it first exceeds the initiation threshold, officially determining this point as the optimal time to initiate the regeneration procedure.

[0050] Regarding the dynamic adjustment logic of the threshold, the third preset threshold is mainly adjusted based on the real-time indoor activity intensity. Activity intensity is estimated by analyzing the signal frequency and spatial distribution of multiple infrared motion sensors deployed indoors. When active and frequent movement of people is detected, the system determines that the indoor carbon dioxide production rate is high and the system is more sensitive to air quality. Therefore, it lowers the third preset threshold (e.g., from 1000ppm to 800ppm), reducing the system's tolerance for increased carbon dioxide concentration. This makes it more inclined to consider ventilation (bypass during regeneration) more efficient when air quality is slightly poor. The seasonal adjustment of the fourth preset threshold directly serves the energy-saving goal. In summer mode, the indoor environment is usually in a cooling state, with the indoor temperature lower than the outdoor temperature. If outdoor hot air is introduced (through the bypass duct) to initiate regeneration at this time, it will increase the cooling load of the indoor air conditioning. Therefore, the fourth preset threshold for summer mode is set to a relatively small positive value (e.g., 3°C). This means that only when the absolute value of the indoor and outdoor temperature difference is less than this small threshold does the system consider the additional cooling energy consumption from ventilation acceptable, thus allowing regeneration to be initiated at this optimal time. The core principle is to minimize cooling loss caused by regenerative ventilation. In winter mode, indoor temperatures are typically higher than outdoor temperatures due to heating, and introducing cold outdoor air would increase the heating load. However, winter is often more sensitive to indoor air quality (such as carbon dioxide accumulation) and requires a more proactive approach to maintaining the performance of the equipment (oxygen-enriched membrane). Therefore, the fourth preset threshold for winter mode is set to a relatively large positive value (e.g., 8°C). This means the system allows regeneration to be initiated even with a larger temperature difference between indoors and outdoors. This reflects a trade-off between equipment maintenance needs, the necessity of ventilation, and heating energy consumption in winter mode, temporarily relaxing restrictions on energy consumption caused by ventilation.

[0051] This solution achieves intelligent and refined selection of the regeneration program initiation point by quantitatively integrating multiple factors such as indoor air quality requirements, heat load costs, power grid conditions, and user habits. Compared to simple regeneration strategies that trigger at fixed times or only consider the state of a single device, this method considers regeneration behavior within the broader context of the entire indoor environmental system and energy costs. This significantly reduces the disruption to indoor occupants' comfort during regeneration operation and avoids unnecessary ventilation switching when indoor air quality is already good or when outdoor conditions are extreme, thereby reducing additional cooling or heating energy consumption caused by regeneration bypass ventilation. Furthermore, by incorporating time-based priorities, this method also helps achieve off-peak operation, reducing overall equipment operating costs.

[0052] In another technical solution, step S3, the process of generating and executing the regeneration instructions, specifically includes: Once the system determines the optimal time to initiate the regeneration program, the main controller generates a sequence of regeneration instructions containing timing logic. The instruction sequence includes a closing instruction and an opening instruction. The closing instruction is sent to the drive circuit of the solenoid valve in the oxygen-enriched membrane intake channel via a digital signal line. The instruction is encoded with the target valve position being fully closed and the maximum allowable delay time. The opening instruction is sent to the damper actuator in the bypass ventilation duct via another independent digital signal line. The instruction is encoded with the target damper opening being fully open and the maximum allowable delay time. Before issuing the above two commands, the main controller first reduces the speed of the whole unit's ventilation fan to a preset transition speed; the closing command and the opening command are set to be sent simultaneously, and only after the valve position status feedback signal of the oxygen-enriched membrane air intake channel solenoid valve confirms that it has started to move towards the closed position is the bypass ventilation duct damper actuator allowed to start to move towards the open position.

[0053] Once the system calculates the optimal time to initiate the regeneration procedure, the main controller generates and executes a carefully designed sequence of regeneration instructions with strict timing logic. This sequence typically includes at least two core instructions: a closing instruction for the solenoid valve in the oxygen-enriched membrane inlet channel and an opening instruction for the damper actuator in the bypass ventilation duct. The closing instruction is sent to the solenoid valve's drive circuit via a dedicated digital signal line. This instruction not only specifies the target state—requiring the solenoid valve core to move to the fully closed position to completely cut off the airflow to the oxygen-enriched membrane component—but also encodes the maximum allowable delay time for executing this action, such as 2 to 5 seconds. This is to prevent the actuator from waiting indefinitely due to jamming or other reasons. Similarly, the opening instruction is sent to the damper actuator controlling the bypass ventilation duct via another independent digital signal line. This instruction encodes the target damper opening as fully open and the corresponding maximum allowable delay. The main controller can also embed checksums or specific command frame formats when programming these instructions to enhance communication reliability. Before issuing these two crucial state switching commands, the main controller performs a preparatory action: first, it reduces the speed of the unit's ventilation fan. The fan will decrease from the set speed of the current purification or oxygenation mode (e.g., high, medium, or low speed) to a preset transition speed. This transition speed may be set as a percentage of the original speed, such as 30% to 60%, or a fixed lower speed value. The purpose of this operation is to reduce the total system air pressure and airflow velocity before the airflow path switch, thereby reducing the aerodynamic load on the solenoid valves and dampers at the moment of action, making the switching process smoother, and reducing airflow noise or vibration that may be caused by sudden pressure changes.

[0054] Regarding the specific command execution sequence, the system employs a coordination mechanism to ensure an orderly and reliable switching process. Although the shut-off and open commands are logically sent simultaneously—that is, the controller issues these two commands within the same control cycle—a dependency condition is introduced at the physical execution level. After issuing the command, the main controller immediately monitors the initial feedback signal from the solenoid valve of the oxygen-enriched membrane intake channel. Typically, upon receiving the shut-off command, the solenoid valve's drive circuit first returns a "start moving" or "command accepted" feedback signal. The system is designed so that only after confirming the receipt of feedback that the solenoid valve has begun moving to the shut-off position does it release the signal through logic circuitry or software conditions, allowing the damper actuator of the bypass ventilation duct to truly begin moving to the open position. This slight timing delay ensures that the airflow cut-off action takes precedence over the bypass opening action, effectively preventing airflow short-circuiting at the moment of switching—that is, the chaotic state of a small amount of untreated air passing through two paths simultaneously—thus ensuring a stable transition of indoor air quality during the switching process. By employing a refined control sequence that includes preparatory actions, independently coded commands, and timing coordination, this method significantly improves the reliability, smoothness, and safety of the airflow switching process. Compared to the traditional method of directly and simultaneously driving two actuators for abrupt switching, pre-reducing the fan speed minimizes the mechanical impact on the actuators; while the timing logic eliminates the possibility of brief cross-contamination of the airflow path. These measures work together to ensure a virtually seamless transition from normal operating mode to regeneration mode with minimal impact on the indoor environment, avoiding significant airflow disturbances, noise, or temporary air quality degradation caused by switching actions.

[0055] After the shutdown and startup commands are sent, the system executes a command verification and feedback mechanism, which includes: Within the maximum allowed delay time of the instruction, the main controller continuously receives valve position status feedback signals from the solenoid valve of the oxygen-enriched membrane air intake channel and damper opening feedback signals from the bypass ventilation duct; it compares the received valve position status feedback signals with the target valve position status in the instruction, and simultaneously compares the received damper opening feedback signals with the target damper opening in the instruction; if both comparison results confirm that the actual state is consistent with the target state within the maximum delay time, the regeneration instruction is determined to have been executed successfully, the main controller records a success flag and allows entry into step S4; if either comparison result fails to confirm that the state is consistent within the maximum delay time, the instruction is determined to have failed; in the case of instruction execution failure, a backup switching strategy is initiated: the main controller immediately issues a shutdown command to the ventilation fan, and after the fan has completely stopped, it resends the original shutdown and start command sequences; if the backup switching strategy still fails after repeating the specified number of times, the system determines that there is a hardware failure, generates a fault alarm signal, locks the entire machine in a safe state, and terminates the current regeneration process, while attempting to restore the original operating mode before the instruction was executed.

[0056] Upon issuance of the command, the system immediately initiates an active command verification and real-time feedback mechanism. Within the maximum allowed delay window, the main controller continuously and frequently acquires feedback signals from two key actuators. For the oxygen-enriched membrane inlet solenoid valve, the controller receives its valve position status feedback signal, which can be an analog signal (such as 0-10V voltage or 4-20mA current) or a digital signal, representing the actual position of the valve core. For the bypass ventilation duct, it receives the damper opening feedback signal from an angle sensor or potentiometer connected to the damper shaft. The main controller compares the received actual valve position status with the target valve position status (fully closed) set in the command in real time, and also compares the actual damper opening with the target damper opening (fully open). This comparison is precise; for example, determining whether the actual position reaches more than 95% of the target position or is within a preset dead zone range indicates a consistent state. Based on the real-time comparison results, a clear judgment is made within the maximum delay time. If, within the set time, both comparison results confirm that the actual state and the target state are consistent, the system determines that the regeneration command sequence has been successfully executed. The main controller records a success flag, allowing the control system process to smoothly proceed to the next stage, namely the PTC heating and regeneration stage in step S4. Conversely, if, within the maximum delay time, the feedback signal from any actuator fails to indicate that its actual state has reached the target state required by the command (e.g., the solenoid valve is stuck halfway, or the damper is not fully open), the system determines that the command execution has failed.

[0057] In case of command execution failure, the system has a pre-set tiered backup switching strategy to attempt recovery. If failure is detected, the main controller issues a shutdown command to the ventilation fan, completely stopping its operation and eliminating airflow. After the fan stops, the main controller resends the original shutdown and startup command sequence to attempt a second action. This reset and retry strategy has a limited number of repetitions, typically 2 to 3. If the backup switching strategy fails after the specified number of repetitions, the system will stop trying and instead determine it as a hardware failure, such as actuator damage, sensor malfunction, or mechanical jamming. At this point, the main controller generates a clear fault alarm signal, notifying the user via indicator lights, the display screen, or network information. Simultaneously, the system locks the entire unit to a safe state (usually all actuators remain stationary, the heater is off, and the fan is stopped) and completely terminates the current regeneration process. Where possible, the system will attempt to restore the relevant components to their original operating mode before command execution to minimize the impact on the continued operation of the indoor environment. The command verification and feedback mechanism, along with supporting backup switching and fault handling strategies, adds a crucial safety layer and fault tolerance to the entire regeneration control process. This changes the unreliable "command issued is considered executed" mode of traditional open-loop control, confirming the actual effect of each critical action through real-time hardware feedback. This not only promptly detects and reports actuator faults, preventing performance problems or even safety hazards (such as moisture entering inappropriate areas) that might result from heating or ventilation under incorrect airflow conditions, but also automatically attempts to recover from certain transient faults through an intelligent retry mechanism. When recovery is impossible, explicit fault locking and alarms effectively prevent the fault from escalating and guide users or maintenance personnel to intervene promptly, significantly improving the operational reliability, safety, and maintainability of the entire window-type fresh air unit system.

[0058] In another technical solution, step S4, which involves turning on the PTC heater and adjusting the heating power, includes the following methods: After confirming that the bypass ventilation duct has been opened as instructed, the main controller sends a start command to the power drive module of the PTC heater, and the PTC heater starts working with the initial preheating power. The system continuously acquires the current dew point of the drying unit and calculates the real-time difference between the current dew point value and the second preset threshold. Using the real-time difference as the primary input parameter, a basic target heating power is calculated according to the built-in difference-power mapping table. At the same time, a real-time correction factor is obtained by analyzing the downward trend slope of the current dew point of the drying unit within a preset time window. If the downward trend slope is less than the expected value, the correction factor is increased to increase the target heating power; if the downward trend slope is greater than the expected value, the correction factor is decreased to decrease the target heating power. The basic target heating power is multiplied by the real-time correction factor to obtain the actual heating power command value of the PTC heater applied to the next control cycle.

[0059] After confirming that the bypass ventilation duct has been successfully opened and is operating stably, the system enters the core power control stage of PTC heating and regeneration. First, the main controller sends a start command to the power drive module of the PTC heater, and the PTC heater begins operation. To provide a smooth initial heating of the drying unit and avoid thermal shock, the heater starts operating at a set initial preheating power. This initial preheating power can be set to a low percentage of the PTC heater's rated maximum power, such as 20% to 40%, for several minutes, such as 3 to 8 minutes, to ensure a uniform and slow rise in the overall temperature of the drying unit. After heating starts, the system enters a dynamic power regulation closed loop, where the real-time difference between the current dew point value of the drying unit and a second preset threshold directly quantifies the gap between the current state of the drying unit and the ideal regeneration target. The system has a pre-calibrated difference-power mapping table or a calculation formula built-in, which can calculate a basic target heating power based on this real-time difference. For example, when the difference is large (e.g., the dew point is much higher than the threshold), the base target power obtained from the table is higher to quickly remove moisture; when the difference decreases, the base target power also decreases. Simultaneously, to more intelligently respond to the dynamic characteristics of the regeneration process, the system also introduces a real-time correction factor. This correction factor is obtained by analyzing the downward trend slope of the current dew point of the drying unit within a preset time window. The length of the time window can be set as needed, for example, from 10 to 30 minutes in the past. The system calculates the average rate of dew point decrease over time within this window. If the calculated downward trend slope is less than a certain expected value (e.g., lower than the theoretical slope predicted based on the current heating power and desiccant characteristic model), it indicates that the current heating power may not be sufficient for efficient desorption, or the desiccant is severely damp. In this case, the system increases the correction factor (e.g., set to a value greater than 1) to increase the final target heating power. Conversely, if the downward trend slope is greater than the expected value, it indicates that the desorption efficiency is high. To avoid overheating and energy waste, the system decreases the correction factor (e.g., set to a value less than 1) to reduce the target power. The system multiplies the calculated target heating power by a real-time correction factor to obtain the actual heating power command value for the PTC heater applied to the next control cycle. This command value is sent to the PTC's power drive module, which precisely controls the voltage or current applied across the PTC element by adjusting the conduction angle of the thyristor or using PWM (pulse width modulation), thereby achieving continuous or stepped adjustment of its heating power. The entire adjustment process is periodic, with a new sampling, calculation, and command update every 30 seconds or every minute, forming an intelligent power control system that adaptively responds to the real-time desiccant desorption status and efficiency trends, ensuring that the regeneration process is both fast and efficient without unnecessarily consuming excessive electrical energy.

[0060] This solution employs a dual-parameter dynamic power control strategy based on the real-time dew point difference and the desorption trend slope to achieve refined management and energy efficiency optimization of the PTC heating regeneration process. Compared to heating methods using fixed power or simple staged power, this method can more sensitively respond to actual state changes in the drying unit. It intelligently increases power to accelerate the process in the initial stages requiring rapid desorption or when resistance is encountered, and automatically reduces power to avoid overheating and energy waste when desorption is successful or near completion. This not only significantly improves the thermal efficiency of the regeneration process and shortens the overall time required to reach the target dew point, but also effectively prevents the risk of desiccant thermal aging or localized overheating problems that may result from continuous high-power heating. Thus, while ensuring reliable regeneration results, it achieves a significant reduction in energy consumption and better protection of the lifespan of critical components.

[0061] In step S4, the specific process of venting the high-temperature and humid air generated during the regeneration process to the outdoor environment through an independent exhaust path includes: The independent exhaust path consists of an independent exhaust fan and a dedicated duct isolated from the indoor environment. When the PTC heater starts, the exhaust fan starts simultaneously. The fan speed is linked to the actual heating power command value of the PTC heater and is adjusted proportionally to match the rate of regeneration moisture generation. A humidity sensor is installed at the outlet of the independent exhaust path to monitor the relative humidity of the exhaust gas. The monitored relative humidity of the exhaust gas is compared with an expected humidity range calculated based on the current PTC heater power and the intake humidity. If the monitored humidity is consistently lower than the lower limit of the expected range, a duct leakage suspicion flag is triggered, and the exhaust fan speed is increased to compensate. If the monitored humidity is consistently higher than the upper limit of the expected range and the current dew point of the drying unit decreases slowly, a low regeneration efficiency flag is triggered. If the actual heating power command value of the PTC heater has reached its maximum safe power limit and the duration exceeds the preset time, the main controller performs a regeneration mode switch: records the current state, then shuts down the PTC heater and the exhaust fan, switches the drying unit to a normal temperature purging mode driven by an internal circulation fan for a period of time, and then attempts to restart the PTC heating regeneration mode.

[0062] To ensure that the high-temperature and high-humidity exhaust gas generated during the regeneration process is effectively and reliably discharged outdoors without affecting the indoor environment, the system is designed and controlled with an independent exhaust path. This path is physically isolated from the indoor environment and typically consists of a dedicated centrifugal or axial fan for dehumidification and a sealed, dedicated duct (possibly insulated), with its outlet directly leading outdoors. When the PTC heater start command is confirmed, the system synchronously starts this independent exhaust fan, with the two operating in close synchronization. The exhaust fan speed is not constant but is controlled in conjunction with the actual heating power command value of the PTC heater, adjusted according to a preset proportional relationship. For example, the exhaust fan speed can be set to have a linear relationship with the heating power within a certain range; the higher the heating power, the higher the speed. The purpose of this linkage is to ensure that the exhaust volume matches the real-time rate of moisture generation during regeneration, ensuring that moisture is removed promptly, while avoiding energy waste or airflow noise caused by high-speed exhaust at low heating power.

[0063] To monitor dehumidification efficiency and path integrity, humidity sensors are installed at the outlet of independent exhaust paths or in the middle of the duct to continuously monitor the relative humidity of the exhaust gas. Simultaneously, the system calculates a predicted exhaust gas humidity range based on the current PTC heater power, intake air humidity (obtainable from the dryer unit's intake sensor), and the theoretical desorption characteristics of the desiccant, using a built-in model or empirical data table. This range is a dynamic reference; for example, during periods of high heating power and high intake air humidity, the upper limit of the predicted humidity range will be higher. The system compares the real-time monitored exhaust gas humidity with this dynamic predicted range to diagnose the operating status and regeneration efficiency of the exhaust path. This comparison can trigger two main anomaly handling mechanisms. The first is suspected duct leakage. If the monitored exhaust gas relative humidity consistently falls below the lower limit of the predicted range (e.g., abnormally low humidity readings during the main desorption phase), this may indicate a leak in the exhaust path, causing some moisture to escape without passing the sensor, or that dry outdoor air is diluting the moisture. At this point, the system will trigger a "suspected duct leakage" flag and attempt compensatory control, such as actively increasing the exhaust fan speed to try to reduce the possible leakage impact or enhance exhaust capacity by increasing the exhaust negative pressure. The second flag is a low regeneration efficiency flag. If the monitored humidity consistently exceeds the upper limit of the expected range, but the current dew point of the drying unit decreases very slowly, this indicates a large amount of moisture being generated (meaning heating has produced water vapor), but this moisture is not effectively desorbed from the desiccant (manifested as a slow dew point decrease), and thermal energy may be wasted on heating the carrier rather than effective desorption. In this case, the system triggers a "low regeneration efficiency" flag. If, under these circumstances, the actual heating power command value of the PTC heater has reached its maximum safe power limit (set by hardware or software) and the duration exceeds the preset duration (e.g., 10 minutes), the main controller will determine that the current single heating regeneration mode may be encountering a bottleneck. As a countermeasure, the system will perform a regeneration mode switch: first, record all current status parameters, and then safely shut down the PTC heater and exhaust fan. Next, the system switches the drying unit to a room-temperature purging mode driven by another internal circulation fan built into the device for a period of time (e.g., 5 to 15 minutes). In this mode, dry air from the room or inside the device is guided to blow over the desiccant surface, using airflow and room temperature for physical purging to help remove moisture that may have accumulated on the surface or disrupt the desorption equilibrium. After purging, the system will attempt to restart the PTC heating regeneration mode again, aiming for more effective heating desorption from a new starting point.

[0064] This method constructs a highly reliable and adaptive system for ensuring the safe discharge and regeneration of moisture through active linkage control of independent exhaust paths, real-time humidity monitoring, and intelligent anomaly diagnosis and handling. It not only ensures that all humid and hot exhaust gases generated during regeneration are forcibly and directionally discharged outdoors, completely eliminating the risk of secondary humidification pollution to the indoor environment, but also optimizes exhaust energy consumption through the linkage of exhaust fans and heating power. More importantly, the anomaly diagnosis mechanism based on humidity monitoring enables the system to proactively identify two potential problems: "duct leakage" and "low regeneration efficiency," and can take targeted compensatory measures or even switch execution modes to attempt to restore efficiency. This significantly improves the robustness and success rate of the entire regeneration process under complex operating conditions, avoiding regeneration failures, energy waste, or prolonged ineffective equipment operation caused by poor ventilation or desorption bottlenecks, thus ensuring the long-term stability and reliability of the system.

[0065] In another technical solution, step S5 specifically includes: During the regeneration process, the current dew point of the drying unit is continuously acquired at a fixed sampling period. When the current dew point first falls below the fifth preset threshold, a delay judgment timer is started. The current dew point is monitored during the timer's operation. If the current dew point remains below the fifth preset threshold and does not show a rebound upward trend during the timer's operation, the regeneration is officially determined to be complete. If the current dew point rebounds and exceeds the fifth preset threshold during the timer's operation, the timer is reset and the regeneration process continues. After regeneration is completed, a sequential recovery operation is performed: First, a step-down power reduction command is sent to the power drive module of the PTC heater, causing the heating power to gradually decrease to zero according to a preset curve over multiple control cycles, and then a shutdown command is sent; at the same time as the PTC heater power begins to decrease, a synchronous speed reduction command is sent to the exhaust fan of the independent exhaust path, causing its speed to decrease proportionally with the decrease in heating power; after confirming that the PTC heater has been shut down and the exhaust fan has stopped, a recovery command sequence is generated and sent, including simultaneously sending an opening command to the solenoid valve of the oxygen-enriched membrane air intake channel and a closing command to the damper actuator of the bypass ventilation duct; after the system monitors and confirms that the valve position status feedback signal of the solenoid valve of the oxygen-enriched membrane air intake channel is fully open and the damper opening feedback signal of the bypass ventilation duct is fully closed, the speed of the ventilation fan is gradually increased from the transition speed to the set speed of the corresponding purification mode or oxygenation mode; After the recovery process is completed, record the complete data of this regeneration process, including the regeneration duration, final dew point value and cumulative energy consumption; the fifth preset threshold is calculated and dynamically updated through a linear regression model, specifically set as the cumulative energy consumption of the PTC heater in the current regeneration cycle and the initial dew point value of the drying unit at the start of regeneration.

[0066] In the final stage of the regeneration process, the system incorporates a prudent logic combining delayed confirmation and trend judgment to determine regeneration completion. The system continuously acquires the current dew point value of the drying unit at a fixed sampling period, which can be set to a short interval, such as every 30 to 60 seconds, to ensure continuous monitoring. When the current dew point value first falls below a fifth preset threshold, the system does not immediately declare regeneration complete but instead initiates a delayed judgment timer. This delay phase may last, for example, 3 to 10 minutes, during which the system continues to monitor the dew point at the same frequency. If, throughout the timer's operation, the current dew point value remains below the fifth preset threshold and there is no significant upward rebound trend (e.g., by analyzing the data points within the timer and confirming that the slope is generally stable or continuously downward), the system finally officially determines that regeneration is complete. This design effectively filters out false alarms of single-point low readings caused by minor sensor fluctuations, brief airflow unevenness, or temporary equilibrium phenomena during desorption. If the current dew point value rebounds and exceeds the fifth preset threshold again during the timer's operation, the system immediately resets the timer and continues the original regeneration process until a stable low dew point condition is met again. This determination mechanism greatly improves the reliability of the regeneration completion signal, ensuring that the drying unit has fully recovered its adsorption capacity.

[0067] Once regeneration is officially deemed complete, the entire unit needs to be smoothly and safely switched back from regeneration mode to normal purification or oxygenation mode. The recovery operation has a clear timing and coordination. First, for the PTC heater, the main controller sends a step-down power reduction command to its power drive module. This command causes the heating power to gradually decrease to zero over several subsequent control cycles according to a preset smooth decline curve, for example, decreasing evenly from the current power in four to six steps over 30 seconds to 2 minutes, before finally sending a complete shutdown command. This gradual reduction method avoids stress on the heating element due to a sudden temperature drop and also facilitates the even dissipation of residual heat from the drying unit. Simultaneously with the PTC heater power reduction, the system sends a synchronous speed reduction command to the exhaust fan in the independent exhaust path, causing its speed to decrease proportionally with the decrease in heating power according to a preset correspondence, ultimately reaching a stop state when the heater is shut down, thus achieving synchronous shutdown of exhaust and heat generation and avoiding energy waste. After confirming that the PTC heater has shut down and the exhaust fan has stopped, the system generates and sends a recovery command sequence. The system sends an opening command to the solenoid valve of the oxygen-enriched membrane inlet channel and a closing command to the damper actuator of the bypass ventilation duct to reverse the airflow switching action in step S3. The system closely monitors and confirms the feedback signals from these two actuators. Only when the valve position feedback signal of the solenoid valve of the oxygen-enriched membrane inlet channel is confirmed to be fully open, and the damper opening feedback signal of the bypass ventilation duct is confirmed to be fully closed, is the airflow considered to have been correctly restored. Finally, the system gradually increases the speed of the ventilation fan from the transition speed maintained during regeneration, and after a smooth acceleration process, restores it to the set speed corresponding to the current required purification mode or oxygenation mode. At this point, the entire unit has fully resumed normal operation.

[0068] After the entire recovery process is completed, the system archives and learns from the data of this regeneration process, recording key data including the total regeneration duration, the final stable dew point value reached, and the cumulative energy consumption of the PTC heater. Specifically, the fifth preset threshold itself is not a fixed value, but is dynamically calculated and updated through a linear regression model. The input variables of this model include at least the cumulative energy consumption of the PTC heater within the current regeneration cycle and the initial dew point value of the drying unit at the start of regeneration. For example, the model establishes the following relationship: in a regeneration cycle, if the initial dew point is high and the cumulative energy consumption is large, it indicates that the regeneration load is heavy and more energy is invested. Therefore, the final degree of dryness (corresponding to a lower dew point) may be better, and the system may set a lower fifth preset threshold for the next regeneration (i.e., requiring greater dryness) to pursue better regeneration quality; conversely, if the initial dew point is not high and the energy consumption is low, the system may appropriately increase the fifth preset threshold to balance effect and efficiency. Through this learning mechanism based on historical performance data, the criteria for determining regeneration completion can be continuously optimized as the equipment is used and self-awareness improves, making the system behavior more adaptive. This method significantly improves the reliability, safety, and long-term operational intelligence of the entire regeneration cycle's final stage by introducing a delayed confirmation mechanism and a sequential, collaborative recovery operation process, and endowing key thresholds with dynamic self-updating capabilities. Compared to the simple approach of immediately switching upon reaching the threshold, delayed trend determination effectively avoids "false completion" caused by incomplete regeneration or measurement interference, ensuring substantial recovery of the drying unit's performance and laying a solid foundation for stable operation in subsequent modes. Sequential recovery operations, particularly the coordinated gradual reduction of heating power and exhaust fan speed, and rigorous feedback verification of airflow switching, ensure extremely smooth mode transitions, minimizing impact on mechanical components such as fans and valves and disturbance to indoor airflow, thereby improving equipment lifespan and user experience. Furthermore, the dynamic update mechanism of the fifth preset threshold allows the system to learn and adjust itself based on the actual situation of each regeneration. In the long run, this helps the regeneration strategy increasingly align with the specific operating environment and aging state of the equipment, continuously optimizing energy efficiency while ensuring regeneration quality, and achieving an effective leap in the level of intelligent equipment maintenance.

[0069] To further illustrate the technical effectiveness of this method, a specific implementation example is provided: This example illustrates the operation of a window-type oxygen-enriched membrane fresh air system in the living room of a residential building during winter. The initial conditions are: the equipment has been running continuously in oxygen-enriching mode for three days, the outdoor ambient temperature is -2℃ and the relative humidity is 60%, the indoor ambient temperature is 22℃ and the relative humidity is 40%, and there are two people in the room.

[0070] 1) Key parameters are continuously collected through multiple sets of sensors. Oxygen concentration, temperature, and pressure sensors located at the outlet of the oxygen-enriched membrane module work together to acquire the raw oxygen concentration signal (21.5% O2) and perform compensation calculations based on real-time ambient temperature (20.5℃) and pressure (101.2 kPa) to obtain the outlet oxygen concentration value under standard conditions, and calculate its rate of change as -0.5% / min. The drying unit's status monitoring employs a redundant design: its outlet direct dew point sensor measures a first dew point value of -12℃, while a second dew point value of approximately -11.8℃ is calculated based on the temperature and humidity sensor at the inlet (-1℃, 58%RH); the difference between the two is within the allowable range, so -12℃ is used as the current reliable dew point value. Indoor air quality is monitored by a carbon dioxide sensor at the return air vent, and a stable value of 850 ppm is obtained after 5 minutes of moving average processing. In addition, indoor and outdoor wall temperature sensors measure 22℃ and -2℃ respectively, calculating a real-time indoor-outdoor temperature difference of 24℃.

[0071] 2) Diagnose the performance status of the oxygen-enriched membrane module. The equipment retrieves the initial performance baseline (oxygen concentration change rate -0.05% / min) recorded under standard operating conditions during the initial stable operation phase. The measured change rate (-0.5% / min) is then corrected against the current real-time monitored intake parameters. After eliminating environmental fluctuations, the offset relative to the baseline is calculated to be 0.45% / min. The system dynamically lowers the first preset threshold to 0.3% / min based on the equipment's cumulative operating time (3000 hours). Since the offset consistently exceeds this dynamic threshold for five consecutive judgment cycles, the system determines that the oxygen-enriched membrane module has entered the performance degradation stage.

[0072] Simultaneously, the regeneration requirement of the drying unit is assessed. The current dew point (-12℃) is sent to the decision logic. First, based on the historical adsorption load since the last regeneration (quantitative calculation shows a relatively high recent load), the second preset threshold is dynamically lowered to -15℃. Furthermore, the system analyzes the dew point data trend over the past 30 minutes, and through linear fitting, obtains a dew point rise slope of +0.43℃ / min, which consistently exceeds the preset slope threshold (0.3℃ / min). Combining the two conditions of "current dew point exceeding the dynamic threshold" and "trend slope consistently positive and exceeding the limit," the system determines that the drying unit needs immediate regeneration.

[0073] 3) After confirming the two necessary conditions of oxygen-enriched membrane performance degradation and the need for regeneration of the drying unit, the system enters the regeneration start-up timing optimization decision-making stage. The decision model comprehensively considers indoor environmental comfort and energy consumption impact: Indoor air quality factors: The current indoor CO2 concentration is 850 ppm. Based on the infrared motion sensor signal, the system determines that two people are active indoors, and accordingly dynamically lowers the third preset threshold from the base value of 1000 ppm to 900 ppm. The current concentration is below the threshold, indicating good air quality, and the marginal benefit of improving ventilation is low, so it is assigned a low weighting factor (0.3).

[0074] Heat load factor: The current indoor-outdoor temperature difference is 24℃. The system is in winter mode, and the corresponding fourth preset threshold is 10℃. The current temperature difference far exceeds the threshold, which means that if bypass ventilation is started at this time, a large amount of cold air will be introduced, significantly increasing the heating load. Therefore, this factor is given a lower weight factor (0.1).

[0075] Time period factor: It is currently the afternoon, which is not the peak electricity consumption period, so the system time period priority coefficient is set to 0.8.

[0076] The system calculated a weighted overall ventilation efficiency index of only 0.024 at the current moment, lower than the dynamic activation threshold (0.05). Therefore, the system decided not to activate regeneration and instead continue monitoring. Until 10 PM that evening, the scenario changed: human activity decreased, CO2 concentration dropped to 650 ppm, and its weighting factor increased to 0.7; the indoor-outdoor temperature difference decreased to 18°C, and its weighting factor increased to 0.5; and it entered the off-peak electricity period, with the time factor adjusted to 1.2. After recalculation, the ventilation efficiency index jumped to 0.42, far exceeding the activation threshold. Based on this, the system accurately identified this moment as the optimal time to activate the regeneration program with the least impact on the indoor environment and the best overall energy efficiency.

[0077] Upon reaching the optimal timing point, the main controller first performs a preparatory action, reducing the main ventilation fan speed from 1200 rpm to a transitional speed of 600 rpm to decrease the aerodynamic load during airflow switching. Subsequently, it generates and simultaneously issues two core commands: a closing command (target: fully closed, maximum delay 3 seconds) to the solenoid valve of the oxygen-enriched membrane intake channel via digital signals, and an opening command (target: fully open, maximum delay 3 seconds) to the bypass ventilation damper actuator. The system strictly adheres to timing logic: it only releases the signal to allow the damper actuator to operate after receiving feedback that the solenoid valve has begun to close. Within the maximum 3-second delay, the system continuously compares the feedback signals from both actuators with the target status. Once it confirms that the solenoid valve is fully closed and the damper is fully open, it determines that the airflow switching command was successfully executed and records a success flag.

[0078] 5) After successful airflow switching confirmation, the system initiates the PTC heating and regeneration core process. The PTC heater initially operates at an initial preheating power of 300W for 5 minutes. Then, it enters a dynamic power adjustment closed loop: the system uses the real-time difference (+3℃) between the current dew point of the drying unit (-12℃) and the second preset threshold (-15℃) as the main input, and queries the built-in mapping table to obtain the basic target heating power of 600W. Simultaneously, it analyzes the actual dew point drop slope (0.2℃ / min) over the past 10 minutes and finds it to be lower than the expected value (0.5℃ / min), thus generating a real-time correction factor of 1.3. Multiplying the basic power by the correction factor yields the actual heating power command value of 780W for the next control cycle, which is then sent to the PTC power drive module for execution.

[0079] The high-temperature, humid air generated during regeneration is processed through a separate exhaust path. A dedicated exhaust fan, which starts synchronously with the PTC heater, automatically sets its speed to 1500 rpm, linked to the heating power command (780W), to match the estimated moisture generation rate. At the exhaust path outlet, a humidity sensor monitors the relative humidity of the exhaust gas in real time, ensuring it is 85%. The system compares this reading with the expected humidity range (80%~95%) calculated based on the current heating power and intake air humidity to confirm normal exhaust performance. If the humidity is consistently abnormally low, the system triggers a "suspected duct leakage" flag and automatically increases the exhaust fan speed to compensate. If the humidity is consistently high and the dew point decreases slowly, a "low regeneration efficiency" flag is triggered, and an optimization strategy of switching to a normal temperature purging mode is implemented when the power has reached its limit.

[0080] 6) During regeneration, the system continuously monitors the dew point of the drying unit. When the dew point first drops below the dynamic fifth preset threshold (-28℃, calculated by a linear regression model based on the initial dew point and expected energy consumption for this regeneration), the system starts a 5-minute delay timer. During the timer, if the dew point remains stable below -29℃ without any rebound trend, the system officially determines that regeneration is complete. Subsequently, a sequential and smooth recovery operation is executed: first, a step-down power reduction command is sent to the PTC heater, causing its power to smoothly decrease to zero within 90 seconds and then shut down; the exhaust fan speed is also proportionally reduced until it stops. After confirming that heating and dehumidification have stopped, the system sends a recovery command sequence, simultaneously opening the oxygen-enriched membrane intake solenoid valve and closing the bypass ventilation door. After receiving confirmation feedback of "fully open" and "fully closed" from both, the main controller gradually increases the ventilation fan speed from the transition speed, eventually restoring it to the set speed of 1200 rpm for the oxygenation mode. After the recovery is completed, the system automatically records the key data of the entire regeneration process (duration 30 minutes, final dew point -30℃, cumulative energy consumption 0.35 kWh), and uses this data to dynamically update the fifth preset threshold through a linear regression model, providing a more accurate completion judgment standard for the next regeneration based on the actual state of the equipment.

[0081] Note that the above implementation examples are only demonstrations of the implementation process of some solutions in this application and are not intended to limit the adaptability of the methods provided in this application.

[0082] It should be noted that although the steps are described in a specific order above, this does not mean that they must be performed in that order. In fact, some of these steps can be executed concurrently, or even in a different order, as long as the required functionality is achieved. The number of devices and processing scale described herein are for simplification of the invention; applications, modifications, and variations of this invention will be readily apparent to those skilled in the art.

[0083] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A PTC regeneration bypass control method for a window-type oxygen-enriched membrane fresh air system, characterized in that, The window-type oxygen-enriched membrane fresh air unit includes an oxygen-enriched membrane module, a drying unit, a PTC heater, an oxygen-enriched membrane air inlet solenoid valve, and a bypass ventilation duct. The control method includes the following steps: S1: In purification mode or oxygenation mode, monitor the rate of change of outlet oxygen concentration of oxygen-enriched membrane module, current dew point of drying unit, indoor carbon dioxide concentration and indoor-outdoor temperature difference in real time. S2: Based on the comparison between the rate of change of the outlet oxygen concentration of the oxygen-enriched membrane module and the first preset threshold, determine whether the oxygen-enriched membrane module has entered the performance degradation stage; at the same time, based on the comparison between the current dew point of the drying unit and the second preset threshold, determine whether the drying unit needs to be regenerated; when the oxygen-enriched membrane module enters the performance degradation stage and the drying unit needs to be regenerated, calculate and determine the optimal time to start the regeneration program by combining whether the indoor carbon dioxide concentration exceeds the third preset threshold and whether the indoor and outdoor temperature difference exceeds the fourth preset threshold. S3: When the optimal time to start the regeneration program is reached, generate and execute the regeneration command: close the solenoid valve of the oxygen-enriched membrane air intake channel to cut off the airflow to the oxygen-enriched membrane module, and open the bypass ventilation duct to maintain indoor and outdoor ventilation. S4: With the bypass ventilation duct open, the PTC heater is turned on to heat and regenerate the drying unit. The heating power of the PTC heater is dynamically adjusted according to the difference between the current dew point of the drying unit and the second preset threshold. The high-temperature humid air generated during the regeneration process is discharged to the outdoor environment through an independent exhaust path. S5: Continuously monitor the current dew point of the drying unit. When the current dew point of the drying unit drops to the fifth preset threshold, the regeneration is determined to be complete. At this time, the PTC heater is turned off, the solenoid valve of the oxygen-enriched membrane air intake channel is opened, and the bypass ventilation duct is closed, so that the window-type oxygen-enriched membrane fresh air unit is restored to the purification mode or oxygenation mode.

2. The PTC regeneration bypass control method for a window-type oxygen-enriched membrane fresh air unit according to claim 1, characterized in that, Step S1 specifically includes: The raw oxygen concentration signal at the outlet of the oxygen-enriched membrane module is obtained by an oxygen concentration sensor installed at the outlet of the oxygen-enriched membrane module. At the same time, the ambient temperature and ambient pressure at the outlet of the oxygen-enriched membrane module are obtained by a temperature sensor and a pressure sensor installed at the same location. The raw oxygen concentration signal at the outlet is compensated in real time based on the ambient temperature and ambient pressure to obtain the oxygen concentration value at the outlet under standard conditions. The oxygen concentration value at the outlet under standard conditions is continuously collected at fixed time intervals, and the difference in oxygen concentration between adjacent time intervals is calculated. The first dew point value is obtained by directly measuring the dew point using a dew point sensor installed in the air outlet channel of the drying unit; the second dew point value is calculated by a temperature sensor and a relative humidity sensor installed in the air inlet channel of the drying unit; the first dew point value and the second dew point value are compared in real time, and if the absolute difference between the two exceeds a preset deviation threshold, calibration is performed, including zero-point calibration of the dew point sensor with dry nitrogen and range calibration of the dew point sensor with a saturated salt solution environment; after calibration, the first dew point value is reacquired as the current dew point of the drying unit; The raw indoor carbon dioxide concentration is continuously detected by a carbon dioxide sensor installed at the indoor return air vent, and the raw carbon dioxide concentration is processed by time-weighted averaging to obtain a stable monitoring value of indoor carbon dioxide concentration. The indoor temperature is obtained by a first temperature sensor installed on the indoor side wall, and the outdoor temperature is obtained by a second temperature sensor installed on the outdoor side wall, and the temperature difference between indoor and outdoor is calculated.

3. The PTC regeneration bypass control method for a window-type oxygen-enriched membrane fresh air unit according to claim 1, characterized in that, In step S2, the methods for determining whether the oxygen-enriched membrane module has entered the performance degradation stage include: During the initial stable operation phase of the window-type oxygen-enriched membrane fresh air system, the baseline value of the initial outlet oxygen concentration change rate of the oxygen-enriched membrane module under standard operating conditions is recorded and stored. The standard operating conditions are determined based on the predefined range of inlet air temperature, inlet air humidity, and membrane pressure. During continuous operation in purification or oxygenation mode, the current outlet oxygen concentration change rate is acquired in real time, and the offset of the outlet oxygen concentration change rate is calculated based on the current outlet oxygen concentration change rate and the initial outlet oxygen concentration change rate baseline value. The offset is compared with a first preset threshold. If the absolute value of the offset continuously exceeds the dynamically adjusted first preset threshold for a preset number of consecutive judgment cycles, the oxygen-enriched membrane module is determined to have entered the performance degradation stage. The first preset threshold is determined by dynamic adjustment, and its absolute value decreases accordingly as the cumulative operating time of the oxygen-enriched membrane module increases. Before calculating the offset, the current outlet oxygen concentration change rate is first corrected based on the real-time monitored inlet air temperature, inlet air humidity, and membrane pressure to eliminate rate measurement deviations caused by short-term environmental parameter fluctuations.

4. The PTC regeneration bypass control method for a window-type oxygen-enriched membrane fresh air unit according to claim 1, characterized in that, The methods for determining whether the drying unit needs regeneration in step S2 include: The system acquires the current dew point of the drying unit and compares it with a dynamically set second preset threshold. Simultaneously, it performs trend-based prediction logic: continuously collects current dew point data at multiple time points and uses the least squares method to perform linear fitting to obtain the slope of the current dew point change trend. If the current dew point exceeds the second preset threshold, or the slope of the current dew point change trend is continuously positive and greater than the preset slope threshold, the system determines that the drying unit needs to be regenerated. The second preset threshold is dynamically set based on the historical adsorption load status of the drying unit before the current regeneration cycle. The historical adsorption load status is quantified by calculating the product of the total air flow through the drying unit and its average moisture content from the completion of the last regeneration to the current time. If the historical adsorption load is higher than the set level, the second preset threshold is lowered accordingly; if the historical adsorption load is lower than the set level, the second preset threshold is raised accordingly.

5. The PTC regeneration bypass control method for a window-type oxygen-enriched membrane fresh air unit according to claim 1, characterized in that, In step S2, the specific methods for calculating and determining the optimal time to start the regeneration process include: When the system determines that the oxygen-enriched membrane module has entered the performance degradation stage and the drying unit needs to be regenerated, it acquires a stable monitoring value of indoor carbon dioxide concentration and a real-time monitoring value of the indoor and outdoor temperature difference. The stable monitoring value of indoor carbon dioxide concentration is compared with a dynamically corrected third preset threshold to obtain a first comparison result. At the same time, the indoor and outdoor temperature difference is compared with a fourth preset threshold selected according to the current seasonal pattern to obtain a second comparison result. Subsequently, the first and second comparison results are quantified into weighting factors and combined with a time-priority coefficient preset according to different times of the day, reflecting the power grid load or user habits, to calculate a comprehensive ventilation efficiency index. The optimal time point is determined based on whether the ventilation efficiency index exceeds a dynamically set start-up threshold. After the two conditions of the oxygen-enriched membrane module entering the performance degradation stage and the drying unit needing to be regenerated are met simultaneously, the ventilation efficiency index is continuously calculated and the first time point when it exceeds the start-up threshold is found. This time point is determined as the optimal time point to start the regeneration program. The third preset threshold is dynamically adjusted based on the real-time indoor activity intensity of people. The real-time indoor activity intensity is obtained by analyzing the signal frequency and distribution of infrared motion sensors deployed indoors. When the activity intensity increases, the third preset threshold is lowered. The fourth preset threshold is selected based on the current seasonal mode. In summer mode, the fourth preset threshold is reduced to reduce the additional cooling energy consumption caused by ventilation. In winter mode, the fourth preset threshold is increased to meet the sensitivity requirements of indoor air quality.

6. The PTC regeneration bypass control method for a window-type oxygen-enriched membrane fresh air unit according to claim 1, characterized in that, Step S3, the process of generating and executing regeneration instructions specifically includes: Once the system determines the optimal time to initiate the regeneration program, the main controller generates a sequence of regeneration instructions containing timing logic. The instruction sequence includes a closing instruction and an opening instruction. The closing instruction is sent to the drive circuit of the solenoid valve in the oxygen-enriched membrane intake channel via a digital signal line. The instruction is encoded with the target valve position being fully closed and the maximum allowable delay time. The opening instruction is sent to the damper actuator in the bypass ventilation duct via another independent digital signal line. The instruction is encoded with the target damper opening being fully open and the maximum allowable delay time. Before issuing the above two commands, the main controller first reduces the speed of the whole unit's ventilation fan to a preset transition speed; the closing command and the opening command are set to be sent simultaneously, and only after the valve position status feedback signal of the oxygen-enriched membrane air intake channel solenoid valve confirms that it has started to move towards the closed position is the bypass ventilation duct damper actuator allowed to start to move towards the open position.

7. The PTC regeneration bypass control method for a window-type oxygen-enriched membrane fresh air unit according to claim 6, characterized in that, After the shutdown and startup commands are sent, the system executes a command verification and feedback mechanism, which includes: Within the maximum allowed delay time of the instruction, the main controller continuously receives valve position status feedback signals from the solenoid valve of the oxygen-enriched membrane air intake channel and damper opening feedback signals from the bypass ventilation duct; it compares the received valve position status feedback signals with the target valve position status in the instruction, and simultaneously compares the received damper opening feedback signals with the target damper opening in the instruction; if both comparison results confirm that the actual state is consistent with the target state within the maximum delay time, the regeneration instruction is determined to have been executed successfully, the main controller records a success flag and allows entry into step S4; if either comparison result fails to confirm that the state is consistent within the maximum delay time, the instruction is determined to have failed; in the case of instruction execution failure, a backup switching strategy is initiated: the main controller immediately issues a shutdown command to the ventilation fan, and after the fan has completely stopped, it resends the original shutdown and start command sequences; if the backup switching strategy still fails after repeating the specified number of times, the system determines that there is a hardware failure, generates a fault alarm signal, locks the entire machine in a safe state, and terminates the current regeneration process, while attempting to restore the original operating mode before the instruction was executed.

8. The PTC regeneration bypass control method for a window-type oxygen-enriched membrane fresh air unit according to claim 1, characterized in that, In step S4, the methods for turning on the PTC heater and adjusting the heating power include: After confirming that the bypass ventilation duct has been opened as instructed, the main controller sends a start command to the power drive module of the PTC heater, and the PTC heater starts working with the initial preheating power. The system continuously acquires the current dew point of the drying unit and calculates the real-time difference between the current dew point value and the second preset threshold. Using the real-time difference as the primary input parameter, a basic target heating power is calculated according to the built-in difference-power mapping table. At the same time, a real-time correction factor is obtained by analyzing the downward trend slope of the current dew point of the drying unit within a preset time window. If the downward trend slope is less than the expected value, the correction factor is increased to increase the target heating power; if the downward trend slope is greater than the expected value, the correction factor is decreased to decrease the target heating power. The basic target heating power is multiplied by the real-time correction factor to obtain the actual heating power command value of the PTC heater applied to the next control cycle.

9. The PTC regeneration bypass control method for a window-type oxygen-enriched membrane fresh air unit according to claim 8, characterized in that, In step S4, the specific process of venting the high-temperature and humid air generated during the regeneration process to the outdoor environment through an independent exhaust path includes: The independent exhaust path consists of an independent exhaust fan and a dedicated duct isolated from the indoor environment. When the PTC heater starts, the exhaust fan starts simultaneously. The fan speed is linked to the actual heating power command value of the PTC heater and is adjusted proportionally to match the rate of regeneration moisture generation. A humidity sensor is installed at the outlet of the independent exhaust path to monitor the relative humidity of the exhaust gas. The monitored relative humidity of the exhaust gas is compared with an expected humidity range calculated based on the current PTC heater power and the intake humidity. If the monitored humidity is consistently lower than the lower limit of the expected range, a duct leakage suspicion flag is triggered, and the exhaust fan speed is increased to compensate. If the monitored humidity is consistently higher than the upper limit of the expected range and the current dew point of the drying unit decreases slowly, a low regeneration efficiency flag is triggered. If the actual heating power command value of the PTC heater has reached its maximum safe power limit and the duration exceeds the preset time, the main controller performs a regeneration mode switch: records the current state, then shuts down the PTC heater and the exhaust fan, switches the drying unit to a normal temperature purging mode driven by an internal circulation fan for a period of time, and then attempts to restart the PTC heating regeneration mode.

10. The PTC regeneration bypass control method for a window-type oxygen-enriched membrane fresh air unit according to claim 1, characterized in that, Step S5 specifically includes: During the regeneration process, the current dew point of the drying unit is continuously acquired at a fixed sampling period. When the current dew point first falls below the fifth preset threshold, a delay judgment timer is started. The current dew point is monitored during the timer's operation. If the current dew point remains below the fifth preset threshold and does not show a rebound upward trend during the timer's operation, the regeneration is officially determined to be complete. If the current dew point rebounds and exceeds the fifth preset threshold during the timer's operation, the timer is reset and the regeneration process continues. After regeneration is completed, a sequential recovery operation is performed: First, a step-down power reduction command is sent to the power drive module of the PTC heater, causing the heating power to gradually decrease to zero according to a preset curve over multiple control cycles, and then a shutdown command is sent; at the same time as the PTC heater power begins to decrease, a synchronous speed reduction command is sent to the exhaust fan of the independent exhaust path, causing its speed to decrease proportionally with the decrease in heating power; after confirming that the PTC heater has been shut down and the exhaust fan has stopped, a recovery command sequence is generated and sent, including simultaneously sending an opening command to the solenoid valve of the oxygen-enriched membrane air intake channel and a closing command to the damper actuator of the bypass ventilation duct; after the system monitors and confirms that the valve position status feedback signal of the solenoid valve of the oxygen-enriched membrane air intake channel is fully open and the damper opening feedback signal of the bypass ventilation duct is fully closed, the speed of the ventilation fan is gradually increased from the transition speed to the set speed of the corresponding purification mode or oxygenation mode; After the recovery process is completed, record the complete data of this regeneration process, including the regeneration duration, final dew point value and cumulative energy consumption; the fifth preset threshold is calculated and dynamically updated through a linear regression model, specifically set as the cumulative energy consumption of the PTC heater in the current regeneration cycle and the initial dew point value of the drying unit at the start of regeneration.

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