Energy-saving indoor ventilation system capable of storing heat

Abstract

The invention discloses an energy-saving indoor ventilation system capable of storing heat, which relates to the technical field of building ventilation and energy conservation, and comprises a fresh air channel, an exhaust channel and a heat recovery device arranged between the fresh air channel and the exhaust channel. The heat recovery device comprises a first energy exchange module and a second energy exchange module which are arranged in parallel; the first energy exchange module is a sensible heat exchanger. According to the energy-saving type indoor ventilation system capable of storing heat, the phase change heat storage unit and a parallel energy exchange framework are introduced, intelligent mode switching control is combined, and the frosting phenomenon of a traditional heat exchange core body under the low-temperature and high-humidity working condition is completely eradicated. According to the system, the problem of ventilation interruption caused by periodic defrosting is effectively avoided, the continuity and stability of the indoor air environment are guaranteed, energy additionally consumed for defrosting is eliminated, and the overall energy efficiency and operation reliability of the system in severe cold seasons are improved.

Description

Technical Field

[0001] This invention relates to the field of building ventilation and energy-saving technology, specifically to an energy-saving indoor ventilation system capable of heat storage. Background Technology

[0002] In the field of energy-efficient indoor ventilation systems, utilizing heat recovery devices to recover energy from exhaust air is a common practice. However, these systems face a significant practical challenge. During winter operation, when cold outdoor fresh air and indoor exhaust air exchange heat in a traditional heat exchange core, condensation easily forms on the exhaust side as the temperature drops below the dew point. In frigid weather, this condensation quickly frosts and blocks the airflow channels of the core, leading to a sharp increase in air resistance and a significant decrease in ventilation efficiency. Currently, defrosting is typically achieved by intermittently introducing high-temperature exhaust air or activating electric heating elements. However, this periodic defrosting process forces the system to suspend normal ventilation, disrupting the continuity and comfort of the indoor air environment. More importantly, the defrosting process itself consumes additional energy to melt the frost, directly offsetting the energy saved by heat recovery. This results in a significant reduction in overall energy efficiency during the coldest season of the year, when energy conservation is most crucial. Therefore, how to completely avoid frost formation on the heat exchange core in low-temperature environments, thereby ensuring continuous ventilation and eliminating defrosting energy consumption, has become a core technical challenge that urgently needs to be addressed. Summary of the Invention

[0003] The purpose of this invention is to provide an energy-saving indoor ventilation system capable of heat storage, in order to solve the problems mentioned in the background art.

[0004] To solve the above-mentioned technical problems, the present invention provides the following technical solution: an energy-saving indoor ventilation system capable of heat storage, comprising a fresh air duct, an exhaust air duct, and a heat recovery device disposed between the fresh air duct and the exhaust air duct, wherein the heat recovery device comprises a first energy exchange module and a second energy exchange module disposed in parallel. The first energy exchange module is a sensible heat exchanger; The second energy exchange module is a phase change thermal storage unit, which is encapsulated with phase change material for storing and releasing latent heat through a phase change process; The system also includes a fluid circulation loop, a damper assembly, and a system controller; The fluid circulation loop includes a first circulation branch and a second circulation branch. The first circulation branch flows through the exhaust duct and the phase change heat storage unit to form an exhaust energy absorption path. The second circulation branch flows through the fresh air duct and the phase change heat storage unit to form a fresh air energy release path. The air valve assembly is used to control the connection status between the fresh air duct and the exhaust air duct and the sensible heat exchanger or the fluid circulation loop; The system controller is configured as follows: It receives detection signals from outdoor temperature sensors and indoor humidity sensors; The system operating condition is determined based on the detected signals; When the system is judged to be in normal operating condition, the control valve assembly connects the fresh air duct and the exhaust air duct to the sensible heat exchanger and blocks the heat exchange path between the fluid circulation loop and the air duct. The system operates in direct heat recovery mode. When the system is determined to be in a condition prone to frosting, the control valve assembly physically isolates the connection between the fresh air duct and the exhaust air duct and the sensible heat exchanger, and starts the fluid circulation loop, so that the system operates in the heat storage and anti-frost mode.

[0005] Furthermore, the melting point temperature of the phase change material encapsulated within the phase change thermal storage unit is between -5 degrees Celsius and 5 degrees Celsius.

[0006] Furthermore, the logic for the system controller to determine the frosting-prone condition includes: The reading of the outdoor temperature sensor is compared with a first temperature threshold. The reading of the indoor humidity sensor is compared with a first humidity threshold. When the outdoor temperature sensor reading is lower than or equal to the first temperature threshold and the indoor humidity sensor reading is higher than or equal to the first humidity threshold, it is determined to be a frosting-prone condition.

[0007] Furthermore, the system controller is also configured to perform a mode switching verification process: After the fluid circulation loop is started, the temperature change rate of the phase change thermal storage unit and the temperature change of the fresh air outlet are monitored. When the temperature change rate of the phase change thermal storage unit stabilizes within a predetermined range, and the temperature of the fresh air duct outlet reaches and stabilizes within the target temperature range, the system is confirmed to have successfully switched to and stably operated in the thermal storage anti-frost mode.

[0008] Furthermore, the first circulation branch includes a first liquid heat exchanger disposed in the exhaust channel, a first circulation pump connected to the first liquid heat exchanger, and a pipeline connecting the first liquid heat exchanger and the phase change heat storage unit. The second circulation branch includes a second liquid heat exchanger installed in the fresh air duct, a second circulation pump connected to the second liquid heat exchanger, and a pipeline connecting the second liquid heat exchanger and the phase change heat storage unit.

[0009] Furthermore, both the first liquid heat exchanger and the second liquid heat exchanger are plate heat exchangers.

[0010] Furthermore, the air valve assembly includes a fresh air selection air valve disposed in the fresh air duct upstream of the sensible heat exchanger and an exhaust air selection air valve disposed in the exhaust air duct upstream of the sensible heat exchanger; both the fresh air selection air valve and the exhaust air selection air valve have two air outlets, which lead to the sensible heat exchanger and the corresponding second liquid heat exchanger or first liquid heat exchanger, respectively.

[0011] Furthermore, the system also includes a data storage and processing unit, which pre-stores a frost risk prediction model based on historical operating data; when the system controller judges the operating conditions, it also inputs the outdoor temperature, indoor humidity and system operating time parameters into the frost risk prediction model, and makes a condition judgment based on the model output results.

[0012] Furthermore, the outer wall of the phase change thermal storage unit is provided with a thermal insulation layer.

[0013] Furthermore, during the process of switching from the direct heat recovery mode to the heat storage and anti-frost mode, the system controller controls the first circulation branch to start before the second circulation branch.

[0014] This invention provides an energy-saving indoor ventilation system capable of heat storage, which has the following beneficial effects: This energy-efficient indoor ventilation system, capable of heat storage, eliminates the frosting phenomenon of traditional heat exchange cores under low-temperature and high-humidity conditions by introducing phase-change heat storage units and a parallel energy exchange architecture, combined with intelligent mode switching control. This system effectively avoids ventilation interruptions caused by periodic defrosting, ensures a continuous and stable indoor air environment, eliminates the extra energy consumed for defrosting, and improves the overall energy efficiency and operational reliability of the system during severe cold seasons.

[0015] This energy-saving indoor ventilation system, capable of heat storage, utilizes an indirect energy recovery method based on phase change heat storage and optimized control logic. This not only achieves stable heat recovery but also reduces the system's reliance on traditional defrosting components, helping to extend equipment lifespan and reduce maintenance needs. Attached Figure Description

[0016] Figure 1 This is a system architecture and mode switching diagram of an energy-saving indoor ventilation system capable of heat storage according to the present invention; Figure 2 This is a flowchart illustrating the mode switching control of an energy-saving indoor ventilation system capable of heat storage according to the present invention. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Please see Figure 1 and Figure 2 The present invention provides a technical solution: an energy-saving indoor ventilation system capable of heat storage, including a fresh air duct, an exhaust air duct, and a heat recovery device disposed between the fresh air duct and the exhaust air duct, wherein the heat recovery device includes a first energy exchange module and a second energy exchange module disposed in parallel. The first energy exchange module is a sensible heat exchanger; The second energy exchange module is a phase change thermal storage unit, which is encapsulated with phase change material to store and release latent heat through a phase change process. The system also includes a fluid circulation loop, a damper assembly, and a system controller; The fluid circulation loop includes a first circulation branch and a second circulation branch. The first circulation branch flows through the exhaust duct and the phase change heat storage unit, forming an exhaust energy absorption path; the second circulation branch flows through the fresh air duct and the phase change heat storage unit, forming a fresh air energy release path. The damper assembly is used to control the connection status between the fresh air duct and the exhaust air duct and the sensible heat exchanger or fluid circulation loop; The system controller is configured as follows: It receives detection signals from outdoor temperature sensors and indoor humidity sensors; Determine the system's operating status based on the detected signals; When the system is judged to be in normal operating condition, the control air valve assembly connects the fresh air duct and the exhaust air duct to the sensible heat exchanger and blocks the heat exchange path between the fluid circulation loop and the air duct. The system operates in direct heat recovery mode. When the system is identified as being prone to frosting, the control valve assembly physically isolates the connection between the fresh air duct and the exhaust air duct and the sensible heat exchanger, and activates the fluid circulation loop, putting the system into heat storage and anti-frost mode.

[0019] It should be further explained that the system constructs a novel heat recovery architecture comprising a first energy exchange module and a second energy exchange module arranged in parallel. The first energy exchange module uses a conventional sensible heat exchanger, while the second energy exchange module is an independently encapsulated phase change thermal storage unit containing a specific phase change material. This unit achieves large-scale storage and release of latent heat through the solid-liquid phase change process of its internal material. The melting point of the phase change material is specially selected to meet the energy buffering requirements in low-temperature environments. The system also integrates a closed fluid circulation loop, which is physically divided into a first circulation branch and a second circulation branch. The first circulation branch flows sequentially through a liquid heat exchanger and a circulation pump located in the exhaust duct, and finally connects to the phase change thermal storage unit, forming a path for extracting waste heat from the exhaust air. The second circulation branch flows sequentially through another liquid heat exchanger and a circulation pump located in the fresh air duct, and finally connects to the same phase change thermal storage unit, forming a path for releasing the stored heat to the fresh air.

[0020] The system's damping assembly specifically includes switchable dampers installed upstream of the sensible heat exchanger in the fresh air duct and exhaust air duct, used to precisely guide the airflow path. As the control center, the system controller continuously receives signals from the outdoor temperature sensor and the indoor humidity sensor, and executes preset logical judgments: Under normal operating conditions, the controller controls the air valve assembly to ensure that both fresh air and exhaust air flow through the sensible heat exchanger for direct and efficient heat exchange, while keeping the fluid circulation loop in a non-operating state; once the outdoor temperature drops to a set threshold and the indoor humidity rises to a set threshold, which defines a frosting-prone condition, the controller immediately initiates the mode switching program. First, it controls the air valve assembly to physically cut off the flow of fresh air and exhaust air to the sensible heat exchanger, thereby fundamentally eliminating the physical conditions for frosting. Then, it sequentially starts the circulation pump in the fluid circulation loop, driving the antifreeze liquid to absorb heat on the exhaust side and flow into the phase change heat storage unit to store energy. At the same time, it extracts heat from the phase change heat storage unit on the fresh air side to preheat the fresh air. By monitoring key operating parameters, the stability and effectiveness of this mode switching are verified, ensuring that the system can achieve uninterrupted ventilation and energy recovery even in extremely cold conditions, completely avoiding the problems of frosting and defrosting.

[0021] The melting point of the phase change material encapsulated within the phase change thermal storage unit is between -5°C and 5°C. It should be further clarified that the melting point of the phase change material encapsulated within the phase change thermal storage unit is limited to between -5°C and 5°C. This temperature range ensures that when the outdoor temperature drops to near freezing point—a critical condition most likely to cause frost formation in conventional heat exchangers—the phase change material can promptly activate and complete its solid-liquid phase change, thereby efficiently absorbing and storing waste heat recovered from the exhaust air.

[0022] This phase change material, with its specific melting point range, acts as an energy buffer medium. Its latent heat of phase change is far greater than that of conventional sensible heat absorption, enabling the unit to store a large amount of heat even with minimal temperature fluctuations and release it stably to the fresh air side. This characteristic works closely with the system controller's predictive logic for frosting conditions, allowing the phase change heat storage unit to immediately commence operation when needed. This effectively increases the temperature of the air entering the fresh air duct and ensures that the surface temperature of the liquid heat exchanger it flows through remains above the dew point, thus physically eliminating the possibility of frosting.

[0023] The determination of this melting point parameter is not a conventional or obvious choice in the field, but rather based on a deep understanding and repeated verification of the relationship between building ventilation and thermal environment, phase change material properties and anti-frost objectives. It determines the working efficiency and reliability of the entire system after mode switching and is an important guarantee for realizing the core functions of heat storage and anti-frost.

[0024] The logic for the system controller to determine the frosting-prone operating condition includes: Compare the reading from the outdoor temperature sensor with a first temperature threshold. The reading from the indoor humidity sensor is compared with a first humidity threshold. When the outdoor temperature sensor reading is lower than or equal to the first temperature threshold and the indoor humidity sensor reading is higher than or equal to the first humidity threshold, it is determined to be a frosting-prone condition.

[0025] It should be further explained that the logic for the system controller to determine the frost-prone operating condition is as follows: The system controller has a built-in preset first temperature threshold and first humidity threshold. This threshold combination is set based on data analysis and experimental verification of the critical frost conditions of heat exchangers in a large number of actual engineering projects. During system operation, the controller continuously compares the real-time outdoor temperature sensor reading with the first temperature threshold, and simultaneously compares the real-time indoor humidity sensor reading with the first humidity threshold.

[0026] When the logic judgment module simultaneously meets both conditions—"outdoor temperature reading is lower than or equal to the first temperature threshold" and "indoor humidity reading is higher than or equal to the first humidity threshold"—the controller determines that the current environmental parameters have entered a frosting-prone operating zone. This dual-parameter collaborative judgment mechanism surpasses conventional logic that relies solely on temperature, enabling more accurate prediction of frosting risks. Essentially, it proactively identifies and responds to the physical conditions for frosting, namely, low temperature encountering high humidity. This judgment logic directly triggers the system's intelligent switching from direct heat recovery mode to thermal storage anti-frost mode. It is a crucial decision-making step for the entire system to achieve "preventing frosting before it occurs" rather than "passively defrosting," ensuring the timeliness and accuracy of mode switching.

[0027] The system controller is also configured to perform a mode switching verification process: After starting the fluid circulation loop, monitor the temperature change rate of the phase change thermal storage unit and the temperature change of the fresh air outlet. When the temperature change rate of the phase change thermal storage unit stabilizes within the predetermined range, and the temperature of the fresh air duct outlet reaches and stabilizes within the target temperature range, the system is confirmed to have successfully switched to and is operating stably in the thermal storage anti-frost mode.

[0028] It should be further explained that the mode switching verification process is implemented as follows: After the system controller starts the fluid circulation loop and completes the air valve switching action, it enters a dynamic monitoring and verification phase. During this phase, the controller continuously collects data from the temperature sensor inside the phase change thermal storage unit, and obtains the temperature change rate of the unit in real time by calculating the temperature change value per unit time; at the same time, the controller also continuously monitors the reading of the air temperature sensor located at the air outlet of the fresh air duct.

[0029] The controller compares the acquired rate of temperature change with an empirical range of values ​​pre-stored within the controller, representing a stable heat transfer state of the system, and compares the fresh air outlet temperature with a target temperature range preset based on comfort and anti-frost requirements. When the rate of temperature change of the phase change thermal storage unit remains within the predetermined range, it indicates that the heat absorption or release process of the phase change material is stabilizing, and energy input and output are in dynamic equilibrium. Furthermore, when the fresh air outlet temperature reaches and remains stable within the target temperature range, it proves that the preheating effect of the fresh air has met the design requirements.

[0030] Only when both of the above conditions are met simultaneously can the system controller finally confirm that the switch from direct heat recovery mode to thermal storage anti-frost mode is completely successful and effective. At this point, the system is determined to be operating stably in this mode. This verification process ensures the stable establishment of the system's energy flow, fundamentally avoiding functional failures or energy waste that may result from improper switching, and improving the overall system's intelligence level and operational reliability.

[0031] The first circulation branch includes a first liquid heat exchanger installed in the exhaust duct, a first circulation pump connected to the first liquid heat exchanger, and a pipeline connecting the first liquid heat exchanger and the phase change heat storage unit. The second circulation branch includes a second liquid heat exchanger installed in the fresh air duct, a second circulation pump connected to the second liquid heat exchanger, and a pipeline connecting the second liquid heat exchanger and the phase change heat storage unit.

[0032] It should be further explained that the configuration of the fluid circulation loop is as follows: The first circulation branch is connected in sequence to the first liquid heat exchanger, the first circulation pump for driving fluid flow, and the phase change heat storage unit, which are installed in the exhaust channel. This forms a complete and closed exhaust energy absorption and transfer path, so that the fluid flowing through this branch can first absorb the waste heat contained in the exhaust air in the first liquid heat exchanger, and then be driven by the first circulation pump to flow through the phase change heat storage unit, and transfer the heat it carries to the phase change material for storage. The second circulation branch is connected in sequence to the second liquid heat exchanger, the second circulation pump for driving fluid flow, and the phase change heat storage unit, which are installed in the fresh air channel. This forms an independent and closed fresh air energy supply and release path, so that the low temperature fluid flowing through this branch is driven by the second circulation pump to flow through the phase change heat storage unit and absorb its stored latent heat, and then becomes a fluid with a higher temperature and enters the second liquid heat exchanger, thereby preheating the cold fresh air flowing through the fresh air channel.

[0033] These two branches share the same phase change thermal storage unit as the core energy buffer and exchange hub, realizing indirect and non-contact heat exchange between exhaust energy and fresh air. This physically isolated loop design is the fundamental reason why this solution can completely avoid frost formation on the surface of traditional heat exchangers. Its configuration ensures reliable and controllable transfer and utilization of energy between different physical locations.

[0034] Both the first and second liquid heat exchangers are plate heat exchangers. It should be further noted that both the first and second liquid heat exchangers are implemented using plate heat exchangers. These plate heat exchangers are composed of multiple corrugated metal plates stacked together, forming dense parallel flow channels. This structure gives them a large specific surface area, thereby achieving efficient heat transfer between the fluid and air within the limited space of the exhaust or fresh air duct. In the exhaust duct, the first liquid heat exchanger makes full contact with the relatively warm exhaust air through its plate surface, quickly absorbing the residual heat in the exhaust air and transferring it to the circulating liquid flowing through the internal channels.

[0035] In the fresh air duct, the second liquid heat exchanger uses its plate surface to contact the cold outdoor fresh air, efficiently releasing the heat carried by the circulating liquid that has been heated by the phase change heat storage unit inside it to the fresh air.

[0036] The compact and efficient characteristics of plate heat exchangers ensure that when the system switches to the heat storage and anti-frost mode, the heat in the exhaust air can be quickly and effectively captured and transferred to the circulating liquid. At the same time, the preheated circulating liquid can also fully and quickly release the heat stored in it to the fresh air. Thus, while physically isolating the fresh air from direct contact with the exhaust air, the overall energy recovery efficiency of the system is still guaranteed.

[0037] The damper assembly includes a fresh air selection damper located upstream of the sensible heat exchanger in the fresh air duct and an exhaust air selection damper located upstream of the sensible heat exchanger in the exhaust air duct. Both the fresh air selection damper and the exhaust air selection damper have two air outlets, which lead to the sensible heat exchanger and the corresponding second liquid heat exchanger or first liquid heat exchanger, respectively.

[0038] It should be further explained that the air valve assembly achieves its airflow path switching function through the following configuration: A fresh air selection valve is installed upstream of the sensible heat exchanger in the fresh air duct. This valve has one inlet and two outlets. Its inlet connects to the fresh air inlet pipe from the outside, its first outlet connects to the fresh air side interface of the sensible heat exchanger via a duct, and its second outlet connects to the cavity containing the second liquid heat exchanger via a duct. Similarly, an exhaust selection valve is installed symmetrically upstream of the sensible heat exchanger in the exhaust duct. This valve also has one inlet and two outlets. Its inlet connects to the exhaust air inlet pipe from the room, its first outlet connects to the exhaust side interface of the sensible heat exchanger via a duct, and its second outlet connects to the cavity containing the first liquid heat exchanger via a duct. These two selection valves are connected to the system controller via a mechanical linkage or separately controlled drive motors.

[0039] When the system controller issues a mode switching command, the fresh air selection valve and the exhaust air selection valve operate synchronously, their valve plates rotating precisely to a predetermined angle. This ensures that the fresh air and exhaust airflows are either simultaneously directed to the sensible heat exchanger or simultaneously directed to the corresponding liquid heat exchanger. This mechanical structure of dual valves coordinating switching ensures the determinism of the transition between the two operating modes. In particular, when switching to the heat storage and anti-frost mode, it reliably achieves the physical isolation of the direct heat exchange path between the fresh air duct and the exhaust air duct.

[0040] The system also includes a data storage and processing unit, which pre-stores a frost risk prediction model based on historical operating data. When the system controller judges the operating conditions, it also inputs outdoor temperature, indoor humidity and system operating time parameters into the frost risk prediction model, and makes a judgment on the operating conditions by combining the model output results.

[0041] It should be further explained that the data storage and processing unit is implemented in the following way: The system includes a data storage and processing unit integrated within or closely communicating with the system controller. This unit's non-volatile memory pre-stores a frosting risk prediction model trained using machine learning algorithms based on the system's historical operating data. This model considers not only real-time outdoor temperature and indoor humidity, but also time-series parameters such as the specific time of day and the system's continuous operating time as input features. When determining operating conditions, the system controller inputs the collected outdoor temperature, indoor humidity, and current system operating time parameters into the frosting risk prediction model.

[0042] The model outputs a quantified probability value or risk level of frost risk by performing weighted analysis and pattern recognition on these multi-dimensional parameters. The system controller does not rely solely on the model's output but integrates and cross-validates this result with preliminary judgment logic based on fixed thresholds to ultimately make a comprehensive decision on whether to switch to the thermal storage anti-frost mode. This intelligent prediction method based on historical data models improves the foresight and accuracy of judgments on complex, gradual, or near-critical operating conditions, enabling the system to execute mode switching more smoothly and accurately, further optimizing system energy efficiency and anti-frost reliability, and demonstrating data-driven intelligent control.

[0043] The outer wall of the phase change thermal storage unit is equipped with an insulation layer. It should be further explained that the insulation layer is implemented as follows: the entire outer surface of the metal shell of the phase change thermal storage unit is covered with a continuous layer of insulation material with low thermal conductivity. This insulation material layer is selected from materials such as closed-cell rubber-plastic insulation cotton or polyurethane foam. Its thickness is calculated based on the difference between the unit's operating temperature and the ambient temperature, as well as the target heat loss rate, to ensure that unnecessary heat exchange between the interior of the phase change thermal storage unit and the external environment is effectively blocked during system operation. This insulation layer completely covers all outer surfaces of the unit shell, including the interfaces connecting to the circulation pipeline, which are also locally reinforced with insulation, thereby minimizing heat loss during the energy storage and standby phases.

[0044] This measure ensures that the latent heat stored in the phase change material can be efficiently used to preheat fresh air, rather than being ineffectively dissipated into the surrounding environment, directly improving the energy utilization efficiency and operational economy of the entire thermal storage and anti-frost mode. The insulation layer ensures that the thermal storage unit can provide stable and sufficient heat output at critical moments of mode switching, thereby reliably achieving the ultimate goal of raising the fresh air temperature and preventing frost formation on the liquid heat exchanger surface.

[0045] During the switch from direct heat recovery mode to thermal storage anti-frost mode, the system controller initiates the first circulation branch before the second circulation branch. It should be further explained that the timing control of the system controller during mode switching is implemented as follows: When the system controller decides to switch from direct heat recovery mode to thermal storage anti-frost mode based on its judgment logic, it executes a step-by-step sequential startup process. The controller first sends a start command to the first circulation pump of the first circulation branch, driving the fluid in that branch to begin flowing. This allows the waste heat in the exhaust duct to be absorbed by the first liquid heat exchanger and transported to the phase change thermal storage unit for heat storage via circulating fluid. This step aims to prioritize establishing the system's heat source side circulation.

[0046] Following this, the controller introduces a preset delay or waits for the temperature sensor feedback from the phase change thermal storage unit to reach a specific trigger condition before sending a start command to the second circulation pump in the second circulation branch, initiating the heating cycle on the fresh air side. This control strategy of starting the exhaust side circuit first and then the fresh air side circuit ensures that the phase change thermal storage unit has received and stored some of the heat from the exhaust air before the cold fresh air begins to flow through the second liquid heat exchanger. This allows for immediate and effective preheating of the fresh air side, avoiding any risk of excessively low local temperatures that might occur due to cold fresh air entering the system first, further solidifying the reliability of the anti-frost effect. This time-sequential start-up logic is a refined design in the system's control strategy. It optimizes the energy flow matching during the transient process of mode switching, improving the system's stability and energy efficiency.

[0047] This system, by introducing a phase change thermal storage unit and a parallel energy exchange architecture, combined with intelligent mode switching control, eliminates the frosting phenomenon of traditional heat exchange cores under low temperature and high humidity conditions. This system effectively avoids ventilation interruptions caused by periodic defrosting, ensures a continuous and stable indoor air environment, eliminates the extra energy consumed for defrosting, and improves the overall energy efficiency and operational reliability of the system during severe cold seasons.

[0048] Furthermore, the indirect energy recovery method based on phase change thermal storage, combined with optimized control logic, not only achieves stable heat recovery but also reduces the system's reliance on traditional defrosting components, helping to extend equipment lifespan and reduce maintenance needs. This solution provides a new system operation paradigm that achieves high efficiency and energy saving without the risk of frosting while ensuring uninterrupted ventilation.

[0049] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0050] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An energy-saving indoor ventilation system capable of heat storage, comprising a fresh air duct, an exhaust air duct, and a heat recovery device disposed between the fresh air duct and the exhaust air duct, characterized in that, The heat recovery device includes a first energy exchange module and a second energy exchange module arranged in parallel. The first energy exchange module is a sensible heat exchanger; The second energy exchange module is a phase change thermal storage unit, which is encapsulated with phase change material for storing and releasing latent heat through a phase change process; The system also includes a fluid circulation loop, a damper assembly, and a system controller; The fluid circulation loop includes a first circulation branch and a second circulation branch. The first circulation branch flows through the exhaust channel and the phase change thermal storage unit to form an exhaust energy absorption path. The second circulation branch flows through the fresh air duct and the phase change thermal storage unit, forming a fresh air energy release path; The air valve assembly is used to control the connection status between the fresh air duct and the exhaust air duct and the sensible heat exchanger or the fluid circulation loop; The system controller is configured as follows: It receives detection signals from outdoor temperature sensors and indoor humidity sensors; The system operating condition is determined based on the detected signals; When the system is judged to be in normal operating condition, the control valve assembly connects the fresh air duct and the exhaust air duct to the sensible heat exchanger and blocks the heat exchange path between the fluid circulation loop and the air duct. The system operates in direct heat recovery mode. When the system is determined to be in a condition prone to frosting, the control valve assembly physically isolates the connection between the fresh air duct and the exhaust air duct and the sensible heat exchanger, and starts the fluid circulation loop, so that the system operates in the heat storage and anti-frost mode.

2. The energy-saving indoor ventilation system capable of heat storage according to claim 1, characterized in that: The melting point temperature of the phase change material encapsulated in the phase change thermal storage unit is between -5°C and 5°C.

3. The energy-saving indoor ventilation system capable of heat storage according to claim 1, characterized in that: The logic for the system controller to determine the frosting-prone condition includes: The reading of the outdoor temperature sensor is compared with a first temperature threshold. The reading of the indoor humidity sensor is compared with a first humidity threshold. When the outdoor temperature sensor reading is lower than or equal to the first temperature threshold and the indoor humidity sensor reading is higher than or equal to the first humidity threshold, it is determined to be a frosting-prone condition.

4. The energy-saving indoor ventilation system capable of heat storage according to claim 1, characterized in that: The system controller is also configured to perform a mode switching verification process: After the fluid circulation loop is started, the temperature change rate of the phase change thermal storage unit and the temperature change of the fresh air outlet are monitored. When the temperature change rate of the phase change thermal storage unit stabilizes within a predetermined range, and the temperature of the fresh air duct outlet reaches and stabilizes within the target temperature range, the system is confirmed to have successfully switched to and stably operated in the thermal storage anti-frost mode.

5. The energy-saving indoor ventilation system capable of heat storage according to claim 1, characterized in that: The first circulation branch includes a first liquid heat exchanger disposed in the exhaust channel, a first circulation pump connected to the first liquid heat exchanger, and a pipeline connecting the first liquid heat exchanger and the phase change heat storage unit. The second circulation branch includes a second liquid heat exchanger installed in the fresh air duct, a second circulation pump connected to the second liquid heat exchanger, and a pipeline connecting the second liquid heat exchanger and the phase change heat storage unit.

6. The energy-saving indoor ventilation system capable of heat storage according to claim 5, characterized in that: Both the first liquid heat exchanger and the second liquid heat exchanger are plate heat exchangers.

7. The energy-saving indoor ventilation system capable of heat storage according to claim 1, characterized in that: The air valve assembly includes a fresh air selection air valve disposed in the fresh air duct upstream of the sensible heat exchanger and an exhaust air selection air valve disposed in the exhaust air duct upstream of the sensible heat exchanger; both the fresh air selection air valve and the exhaust air selection air valve have two air outlets, which lead to the sensible heat exchanger and the corresponding second liquid heat exchanger or first liquid heat exchanger, respectively.

8. The energy-saving indoor ventilation system capable of heat storage according to claim 1, characterized in that: The system also includes a data storage and processing unit, which pre-stores a frost risk prediction model based on historical operating data. When the system controller judges the operating conditions, it also inputs the outdoor temperature, indoor humidity and system operating time parameters into the frost risk prediction model, and makes a judgment on the operating conditions by combining the model output results.

9. The energy-saving indoor ventilation system capable of heat storage according to claim 1, characterized in that: The outer wall of the phase change thermal storage unit is provided with a heat insulation layer.

10. An energy-saving indoor ventilation system capable of heat storage according to claim 1, characterized in that: During the switching process from the direct heat recovery mode to the heat storage and anti-frost mode, the system controller controls the first circulation branch to start before the second circulation branch.

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