Three-stage heat pump fresh air dehumidification unit

Abstract

The application provides a three-stage heat pump fresh air dehumidification unit, which comprises a detachably connected refrigerant circulation mechanism and an air treatment mechanism, the refrigerant circulation mechanism forms a closed loop through a compressor, a condenser, a filter, an electronic expansion valve, a deep cooling fin heat exchanger, a pre-cooling fin heat exchanger and a gas-liquid separator; in the air duct of the air treatment mechanism, fresh air flows through a heat exchanger primary side, the pre-cooling fin heat exchanger, the deep cooling fin heat exchanger in sequence, and then returns to flow through a heat exchanger secondary side and is sent out, forming a three-stage air treatment process of pre-cooling, deep cooling and heat recovery, and relates to the technical field of heating, ventilation and air conditioning, wherein, by integrating a small heat pump system and a three-stage heat exchange air duct, efficient and independent treatment of fresh air is realized, the refrigerating capacity of the main unit does not need to be increased, and the application has the remarkable advantages of low initial investment, high operation energy efficiency, precise and stable temperature and humidity control.

Description

Technical Field

[0001] This invention relates to the field of heating, ventilation and air conditioning technology, and in particular to a three-stage heat pump fresh air dehumidifier unit. Background Technology

[0002] In modern building environments, introducing and treating fresh outdoor air has become a fundamental requirement for HVAC systems to maintain indoor air quality and the health and comfort of occupants. Currently, the main methods for treating fresh air include the following:

[0003] Unorganized fresh air systems: Some buildings or systems, in order to save on initial investment, do not have dedicated fresh air introduction and treatment channels, relying solely on air penetration through doors and windows or occasional window opening for ventilation. This method results in ineffective indoor air exchange, making it easy for carbon dioxide and pollutant concentrations to exceed standards, leading to poor air quality and seriously affecting indoor comfort and health.

[0004] Directly introduced fresh air: Outdoor fresh air is mixed directly with indoor return air before the return air section of the air conditioning unit. While simple, this method has significant drawbacks: the outdoor fresh air load is entirely superimposed on the main unit, forcing the selection of a larger unit capacity, resulting in a significant increase in initial investment costs. Simultaneously, due to the drastic fluctuations in the temperature and humidity of the fresh air, mixing it with the relatively stable return air will severely disrupt the operating conditions of the main unit, leading to poor indoor temperature and humidity control accuracy, frequent start-ups and shutdowns or load adjustments of the main unit, low operating efficiency, and shortened equipment lifespan.

[0005] Independent fresh air handling unit pretreatment: This method uses a separate fresh air handling unit to pre-treat the fresh air before it is delivered to the return air vent of the main unit. This method provides good air handling effect and stability. However, it requires an additional complete air handling equipment and corresponding duct and water pipe systems, resulting in the highest initial investment cost. Furthermore, the capacity of the main unit still needs to consider the remaining cooling and heating load of the pre-treated fresh air, and its capacity and operating energy consumption are still higher than those of the case where only return air is treated. In summary, existing technologies face a dilemma in fresh air treatment: a difficult balance between air quality, system stability, initial investment cost, and operating efficiency.

[0006] Therefore, there is an urgent need in this field for a highly integrated, energy-efficient, and independently and precisely designed solution that can completely free up the load on the main unit. Summary of the Invention

[0007] To overcome existing problems, this application provides a three-stage heat pump fresh air dehumidifier unit, which integrates the air conditioning unit for processing fresh air with a small refrigeration system into a single design. Through an innovative three-stage heat exchange mode, it achieves efficient energy consumption processing of fresh air, effectively reducing initial investment and operating costs while ensuring comfort.

[0008] The technical solution adopted by the embodiments of this application to solve its technical problem is:

[0009] A three-stage heat pump fresh air dehumidifier unit includes a refrigerant circulation mechanism and an air handling mechanism, wherein the refrigerant circulation mechanism and the air handling mechanism are detachable and installable.

[0010] The refrigerant circulation mechanism includes a compressor, a condenser, a filter, at least one electronic expansion valve, and a gas-liquid separator connected sequentially by pipelines.

[0011] The compressor's exhaust port is connected to the refrigerant inlet of the condenser via a pipeline;

[0012] The refrigerant outlet of the condenser is connected to the inlet of the filter via a pipeline;

[0013] The filter's outlet is connected via a pipeline to the inlet of at least one electronic expansion valve;

[0014] The gas outlet of the gas-liquid separator is connected back to the suction port of the compressor through a pipeline, thereby forming a closed refrigerant circulation loop.

[0015] The gas-liquid separator is an optional component and can be removed when the unit is used in a stable external environment with stable temperature and humidity. In this case, the refrigerant pipeline is short-circuited accordingly.

[0016] The air handling unit includes an air duct with an air inlet and an air outlet, and the following components arranged sequentially within the air duct along the direction of fresh air flow:

[0017] A heat exchanger having a primary air duct and a secondary air duct that are isolated from each other but can exchange heat. The inlet of the primary air duct constitutes the air inlet of the unit for introducing fresh air from the outside. The heat exchanger is a stationary plate-fin sensible heat exchanger.

[0018] A centrifugal fan is located downstream of the primary air duct of the heat exchanger to drive the airflow;

[0019] A pre-cooled finned heat exchanger, the finned portion of which is arranged in the air duct downstream of the centrifugal fan;

[0020] A cryogenic finned heat exchanger, wherein the finned portion is arranged in the air duct downstream of the precooled finned heat exchanger;

[0021] The air duct is configured such that air flowing out of the cryogenic finned heat exchanger is redirected into the secondary air duct of the heat exchanger and then discharged through the air outlet.

[0022] In the air handling process, the precooled finned heat exchanger and the cryogenic finned heat exchanger are arranged in series in the air duct to form a stepped cooling and dehumidification of the air. A water collection tray is connected below the precooled finned heat exchanger and the cryogenic finned heat exchanger to collect and discharge the condensate generated during the entire cooling and dehumidification process. In the refrigerant process, the refrigerant flowing through the cryogenic finned heat exchanger then flows through the precooled finned heat exchanger to provide superheat for the refrigerant.

[0023] Preferably, there are two electronic expansion valves, which independently control the refrigerant flow into the two cryogenic finned heat exchangers; in the refrigerant path, the precooled finned heat exchanger is connected in series downstream of the cryogenic finned heat exchanger to provide superheat for the refrigerant flowing out of the cryogenic finned heat exchanger.

[0024] The electronic expansion valve has its outlet connected to the refrigerant inlet of a cryogenic finned heat exchanger via a pipeline. The refrigerant outlet of the cryogenic finned heat exchanger is connected to the refrigerant inlet of a precooled finned heat exchanger via a pipeline. The refrigerant outlet of the precooled finned heat exchanger is connected to the inlet of a gas-liquid separator via a pipeline.

[0025] Preferably, the refrigerant circulation mechanism further includes a bypass solenoid valve, the inlet end of which is connected to the pipeline between the compressor's exhaust port and the condenser, and the outlet end of which is connected to the pipeline between the electronic expansion valve outlet and the cryogenic finned heat exchanger inlet, for bypassing and injecting a portion of the high-temperature gaseous refrigerant for defrosting when the cryogenic finned heat exchanger is frosted.

[0026] The bypass solenoid valve is a normally closed solenoid valve; for each cryogenic finned heat exchanger, an independent bypass solenoid valve and corresponding control logic are configured to realize independent defrosting control of a single cryogenic finned heat exchanger.

[0027] It also includes a temperature and humidity sensor installed at the air outlet of the unit, and a control system electrically connected to the temperature and humidity sensor, the compressor and the centrifugal fan. The control system is configured to automatically adjust the operating frequency of the compressor and the speed of the centrifugal fan based on the deviation between the air outlet temperature and humidity measured by the temperature and humidity sensor and the set value.

[0028] The control system is further configured to control the outlet superheat of the refrigerant flowing through the precooled finned heat exchanger, so as to maintain it within a preset range.

[0029] The advantages of the embodiments of this application are:

[0030] Integrating a small heat pump refrigeration system with air handling functions into a single unit eliminates the need for separate chiller units, boilers, complex water systems, and separate fresh air unit enclosures, greatly simplifying system design, installation, and floor space requirements, and significantly reducing initial investment and installation costs.

[0031] Through a three-stage energy processing mode of pre-cooling, deep cooling, and reheating, the system achieves tiered and efficient utilization of energy between refrigerant and air, and between air and air. The overall energy efficiency ratio of the system is far higher than that of traditional methods. By using a heat exchanger, the energy of the exhaust air is used to reheat the low-temperature supply air after deep dehumidification free of charge, completely eliminating the high-energy-consuming electric reheating or steam reheating methods in traditional dehumidification, thus significantly reducing operating costs. The system adopts full frequency conversion control and direct feedback closed-loop regulation of the supply air parameters, which has a rapid response, strong anti-interference ability, and can effectively resist changes in outdoor weather conditions. The supply air temperature and humidity control accuracy is high, providing unprecedented stability for the indoor environment.

[0032] The design of controllable superheat and gas-liquid separator ensures the safety and reliability of the compressor under various loads, especially under low load or variable operating conditions. The intelligent hot gas bypass defrosting function ensures that the unit can operate continuously and stably in low temperature and high humidity environments, avoiding the problem of frequent start-stop or efficiency reduction caused by frost in conventional equipment, and expanding the application area and seasonal range of the unit. Attached Figure Description

[0033] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0034] Figure 1 This is a schematic diagram of the main structure of the three-stage heat pump fresh air dehumidifier unit of the present invention;

[0035] Figure 2 This is a side view of the three-stage heat pump fresh air dehumidifier unit of the present invention;

[0036] Figure 3 This is a top view schematic diagram of the three-stage heat pump fresh air dehumidifier unit of the present invention;

[0037] Figure 4 This is a schematic diagram of the three-stage heat pump fresh air dehumidifier system of the present invention.

[0038] Explanation of key figure labels:

[0039] 100. Refrigerant circulation mechanism;

[0040] 1. Compressor; 2. Condenser; 3. Bypass solenoid valve; 4. Filter; 5. Electronic expansion valve; 8. Gas-liquid separator;

[0041] 200. Air handling unit;

[0042] 6. Cryogenic finned heat exchanger; 7. Pre-cooled finned heat exchanger; 9. Temperature and humidity sensor; 10. Heat exchanger; 11. Centrifugal fan. Detailed Implementation

[0043] 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 a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention. In addition, for the sake of convenience, the terms "upper," "lower," "left," and "right" are equivalent to the upper, lower, left, and right directions of the accompanying drawings themselves, and the terms "first," "second," etc., are used for descriptive purposes and have no other special meaning.

[0044] This application provides a three-stage heat pump fresh air dehumidification unit, which solves the problems in the prior art. It integrates a small heat pump refrigeration system and air handling function into an integrated unit, eliminating the need for a separate chiller, boiler and complex water system, as well as a separate fresh air unit enclosure. This greatly simplifies system design, installation and floor space, and significantly reduces the initial investment and installation costs of the equipment.

[0045] Through a three-stage energy processing mode of pre-cooling, deep cooling, and reheating, the system achieves tiered and efficient utilization of energy between refrigerant and air, and between air and air. The overall energy efficiency ratio of the system is far higher than that of traditional methods. By using a heat exchanger, the energy of the exhaust air is used to reheat the low-temperature supply air after deep dehumidification free of charge, completely eliminating the high-energy-consuming electric reheating or steam reheating methods in traditional dehumidification, thus significantly reducing operating costs. The system adopts full frequency conversion control and direct feedback closed-loop regulation of the supply air parameters, which has a rapid response, strong anti-interference ability, and can effectively resist changes in outdoor weather conditions. The supply air temperature and humidity control accuracy is high, providing unprecedented stability for the indoor environment.

[0046] The design of controllable superheat and gas-liquid separator ensures the safety and reliability of the compressor under various loads, especially under low load or variable operating conditions. The intelligent hot gas bypass defrosting function ensures that the unit can operate continuously and stably in low temperature and high humidity environments, avoiding the problem of frequent start-stop or efficiency reduction caused by frost in conventional equipment, and expanding the application area and seasonal range of the unit.

[0047] The technical solution in this application is to solve the above problems, and the overall approach is as follows:

[0048] Example

[0049] This embodiment provides the specific structure of a three-stage heat pump fresh air dehumidifier unit, such as... Figure 1-4As shown, it includes a refrigerant circulation mechanism 100 and an air handling mechanism 200, which are detachable.

[0050] The refrigerant circulation mechanism 100 includes a compressor 1, a condenser 2, a filter 4, at least one electronic expansion valve 5, and a gas-liquid separator 8 connected in sequence by pipelines;

[0051] The discharge port of compressor 1 is connected to the refrigerant inlet of condenser 2 via a pipeline;

[0052] The refrigerant outlet of condenser 2 is connected to the inlet of filter 4 via a pipeline;

[0053] The outlet of filter 4 is connected to the inlet of at least one electronic expansion valve 5 via a pipeline;

[0054] The gas outlet of the gas-liquid separator 8 is connected back to the suction port of the compressor 1 through a pipeline, thereby forming a closed refrigerant circulation loop.

[0055] Among them, the gas-liquid separator 8 is an optional component and can be removed when the unit is used in a stable external environment with stable temperature and humidity. In this case, the refrigerant pipeline is short-circuited accordingly.

[0056] There are two electronic expansion valves 5, which independently control the refrigerant flow into the two cryogenic finned heat exchangers 6; in the refrigerant passage, the precooled finned heat exchanger 7 is connected in series downstream of the cryogenic finned heat exchanger 6 to provide superheat for the refrigerant flowing out of the cryogenic finned heat exchanger 6.

[0057] Among them, the outlet of the electronic expansion valve 5 is connected to the refrigerant inlet of a cryogenic finned heat exchanger 6 through a pipeline, the refrigerant outlet of the cryogenic finned heat exchanger 6 is connected to the refrigerant inlet of a precooled finned heat exchanger 7 through a pipeline, and the refrigerant outlet of the precooled finned heat exchanger 7 is connected to the inlet of a gas-liquid separator 8 through a pipeline.

[0058] The refrigerant circulation mechanism 100 also includes a bypass solenoid valve 3, whose inlet end is connected to the pipeline between the exhaust port of the compressor 1 and the condenser 2, and whose outlet end is connected to the pipeline between the outlet of the electronic expansion valve 5 and the inlet of the cryogenic finned heat exchanger 6, for bypassing and injecting part of the high-temperature gaseous refrigerant to defrost when the cryogenic finned heat exchanger 6 is frosted.

[0059] Among them, the bypass solenoid valve 3 is a normally closed solenoid valve; for each cryogenic finned heat exchanger 6, a bypass solenoid valve 3 and corresponding control logic are independently configured to realize independent defrosting control of a single cryogenic finned heat exchanger 6.

[0060] Furthermore, the exhaust port of the variable frequency compressor 1 is connected to the refrigerant inlet of the condenser 2 through a copper pipe. The condenser 2 can be an air-cooled finned heat exchanger. Its refrigerant outlet is connected in sequence to the filter 4 and two parallel electronic expansion valves 5 through a copper pipe. The filter 4 is used to adsorb moisture and filter impurities in the system to ensure system cleanliness.

[0061] The outlets of the two electronic expansion valves 5 are connected to the refrigerant inlets of the two parallel cryogenic finned heat exchangers 6 through independent pipelines. This dual-valve, dual-path independent control design allows for precise allocation of refrigerant flow according to the load conditions of the two cryogenic heat exchangers, improving energy efficiency and the precision of control.

[0062] After the refrigerant outlets of the two cryogenic finned heat exchangers 6 merge, they are connected to the refrigerant inlet of the precooled finned heat exchanger 7 through the same pipeline. The refrigerant outlet of the precooled finned heat exchanger 7 is then connected to the inlet of the gas-liquid separator 8 through a pipeline. The gas outlet of the gas-liquid separator 8 is finally connected back to the suction port of the variable frequency compressor 1 through a return gas pipeline, forming a closed refrigeration cycle.

[0063] The gas-liquid separator 8 is designed as an optional component. In areas where the temperature and humidity of the fresh air are relatively stable year-round, the gas-liquid separator 8 can be removed and the original piping can be short-circuited accordingly to reduce costs and simplify the system. In areas with large fluctuations in the external environment, it is recommended to install it to improve the reliability of compressor operation.

[0064] Defrosting Function Implementation: Two branches are connected to the pipeline between the discharge port of compressor 1 and the inlet of condenser 2, with a normally closed bypass solenoid valve 3 installed on each branch. The outlets of these two bypass solenoid valves 3 are connected to the pipelines after the outlets of the two electronic expansion valves 5 and before the inlet of the corresponding cryogenic finned heat exchanger 6. When the control system determines that a cryogenic finned heat exchanger 6 is frosted through temperature or pressure sensors, it will open the corresponding bypass solenoid valve 3, directly injecting some high-temperature, high-pressure gaseous refrigerant into the heat exchanger, achieving rapid, independent defrosting without affecting the normal operation of the other branch.

[0065] The air handling unit 200 includes an air duct with an air inlet and an air outlet, and the following components arranged sequentially within the air duct along the direction of fresh air flow:

[0066] A heat exchanger 10 has a primary air duct and a secondary air duct that are isolated from each other but can exchange heat. The inlet of the primary air duct constitutes the air inlet of the unit and is used to introduce fresh air from the outside. The heat exchanger 10 is a stationary plate-fin sensible heat exchanger.

[0067] A centrifugal fan 11 is located downstream of the primary air duct of the heat exchanger 10 and is used to drive the airflow.

[0068] The pre-cooled finned heat exchanger 7 has its finned portion arranged in the air duct downstream of the centrifugal fan 11;

[0069] The cryogenic finned heat exchanger 6 has its finned portion arranged in the air duct downstream of the precooled finned heat exchanger 7.

[0070] The air duct is configured such that the air flowing out of the cryogenic finned heat exchanger 6 is redirected into the secondary air duct of the heat exchanger 10 and then discharged through the air outlet.

[0071] In the air handling process, the precooled finned heat exchanger 7 and the cryogenic finned heat exchanger 6 are arranged in series in the air duct to form a stepped cooling and dehumidification of the air. A water collection tray is connected below the precooled finned heat exchanger 7 and the cryogenic finned heat exchanger 6 to collect and discharge the condensate generated during the entire cooling and dehumidification process. In the refrigerant process, the refrigerant flowing through the cryogenic finned heat exchanger 6 then flows through the precooled finned heat exchanger 7 to provide superheat for the refrigerant.

[0072] Furthermore, fresh air from outside first enters the primary air duct of the heat exchanger 10 through the air inlet. The heat exchanger 10 is preferably a stationary plate-fin sensible heat exchanger, whose primary air duct is physically isolated from the secondary air duct but can efficiently transfer sensible heat through metal partitions.

[0073] After being pre-cooled by the heat exchanger 10, the fresh air is drawn in and pressurized by the centrifugal fan 11. The centrifugal fan 11 is located downstream of the heat exchanger 10, which helps to create negative pressure in the entire front air duct and ensures uniform air intake.

[0074] The pressurized air flows sequentially through a pre-cooling finned heat exchanger 7 and two parallel-connected cryogenic finned heat exchangers 6. The finned sections of these three heat exchangers are arranged in series in the air duct, forming a stepped cooling and dehumidification section for the air. The pre-cooling finned heat exchanger 7 first cools the fresh air to near its dew point temperature and condenses some water; the cryogenic finned heat exchangers 6 then deeply cool the air, making its temperature far below the dew point, thus completing deep dehumidification. All condensate generated during this process is collected and discharged through a shared condensate tray installed directly below the pre-cooling and cryogenic heat exchangers.

[0075] After deep dehumidification, the low-temperature dry air is guided by the air duct and flows into the secondary air duct of the heat exchanger 10. Here, the low-temperature dry supply air undergoes non-contact heat exchange with the newly entered hot and humid fresh air. After absorbing its sensible heat, the temperature rises significantly, and the relative humidity decreases to a comfortable range. Finally, it is sent out from the air outlet at the top, completing the three-stage air handling process of pre-cooling, deep cooling, and reheating.

[0076] It also includes a temperature and humidity sensor 9 installed at the air outlet of the unit, and a control system electrically connected to the temperature and humidity sensor 9, the compressor 1 and the centrifugal fan 11. The control system is configured to automatically adjust the operating frequency of the compressor 1 and the speed of the centrifugal fan 11 based on the deviation between the air outlet temperature and humidity measured by the temperature and humidity sensor 9 and the set value.

[0077] The control system is further configured to control the outlet superheat of the refrigerant flowing through the precooled finned heat exchanger 7, so as to maintain it within a preset range.

[0078] Furthermore, a high-precision temperature and humidity sensor 9 is installed at the air outlet of the unit to monitor the final air supply status in real time.

[0079] The temperature and humidity sensor 9 is electrically connected to the core controller of the unit, and the controller is also electrically connected to the variable frequency compressor 1 and the variable frequency centrifugal fan 11.

[0080] Based on the deviation between the supply air temperature and humidity values ​​fed back by the temperature and humidity sensor 9 and the user-set values, the operating frequency of the variable frequency compressor 1 and the speed of the variable frequency centrifugal fan 11 are adjusted synchronously or independently through the PID algorithm to achieve precise matching and control of cooling capacity and fresh air volume, ensuring stable supply air parameters.

[0081] The temperature and pressure sensors installed at the refrigerant outlet of the precooling finned heat exchanger 7 calculate the outlet superheat. The controller then adjusts the opening of the electronic expansion valve 5 to stabilize the superheat within a preset reasonable range, thereby ensuring the safe operation of the compressor 1 and optimizing system energy efficiency.

[0082] Working principle:

[0083] Refrigerant cycle working principle:

[0084] When the variable frequency compressor 1 starts, it compresses the low-temperature, low-pressure refrigerant gas into high-temperature, high-pressure superheated vapor, which is then discharged into the condenser 2. In the condenser 2, the refrigerant releases a large amount of heat to the ambient medium, usually air or water, and condenses into a room-temperature, high-pressure liquid refrigerant.

[0085] The liquid refrigerant flows through filter 4 to remove any impurities and moisture, and then enters electronic expansion valve 5. Electronic expansion valve 5 acts as a precise throttling mechanism to reduce the pressure of the high-pressure liquid refrigerant, turning it into a low-temperature, low-pressure gas-liquid two-phase mixture of saturated refrigerant.

[0086] The throttled, low-temperature refrigerant first enters two parallel cryogenic finned heat exchangers 6. At this point, the refrigerant temperature is much lower than the dew point temperature of the fresh air. When the fresh air flows over the finned surface of the cryogenic finned heat exchanger 6, the water vapor in it is rapidly cooled and condenses into water, thus achieving deep dehumidification. At the same time, the refrigerant absorbs heat from the fresh air and completely evaporates into low-temperature, low-pressure saturated vapor.

[0087] The low-temperature saturated vapor flowing out from the cryogenic finned heat exchanger 6 then enters the pre-cooling finned heat exchanger 7. Here, the fresh air, which has not yet been dehumidified and has a relatively high temperature, is pre-cooled and its temperature is reduced to close to the dew point. This not only completes the initial cooling and pre-cooling stage of the fresh air and prepares it for subsequent cryogenic dehumidification, but more importantly, the heat released by the fresh air is used to heat the refrigerant vapor, making it superheated vapor with controllable superheat.

[0088] The refrigerant vapor with a certain degree of superheat then enters the gas-liquid separator 8 to ensure that any remaining liquid refrigerant is separated, preventing liquid slugging into the compressor. Finally, the pure superheated vapor is drawn into the compressor 1, completing the entire cycle.

[0089] When the ambient temperature and humidity are low, and the surface temperature of the cryogenic finned heat exchanger 6 is below 0°C and it is in contact with humid air, frost will form, affecting heat exchange. At this time, the unit controller detects the frost signal and opens the bypass solenoid valve 3 on the corresponding cryogenic finned heat exchanger 6 pipeline. High-temperature and high-pressure refrigerant vapor bypasses directly from the compressor 1 discharge port to the inlet of the corresponding cryogenic finned heat exchanger 6. After the high-temperature vapor enters, it releases heat, causing the frost layer to melt and fall off quickly, achieving rapid, efficient defrosting without interrupting the main cycle.

[0090] Air handling working principle:

[0091] Driven by centrifugal fan 11, outdoor fresh air first enters horizontally into the primary side of heat exchanger 10. Simultaneously, low-temperature, dry air, after deep dehumidification, enters vertically into the secondary side of the same heat exchanger 10 before being supplied to the mains. The two air streams exchange energy non-contactly within the heat exchanger 10. In summer, the outdoor fresh air is pre-cooled and pre-dried by the exhaust air, recovering its cooling capacity and dryness; the exhaust air, in turn, is pre-heated and humidified.

[0092] The pre-cooled fresh air flows sequentially through the pre-cooling finned heat exchanger 7 and the cryogenic finned heat exchanger 6. In the pre-cooling section, the fresh air is further cooled to saturation and begins to condense and dehumidify. In the subsequent cryogenic section, the fresh air is further cooled to an even lower temperature for deep dehumidification, ensuring its moisture content meets the supply air requirements. The pre-cooling finned heat exchanger 7 and the cryogenic finned heat exchanger 6 are connected in series in the air duct, with the cryogenic section preceding the pre-cooling section in the refrigerant path, forming a highly efficient stepped heat exchange mode that maximizes the utilization of the refrigerant's cooling capacity. All condensate generated during this process is collected and discharged uniformly from a shared bottom condensate tray.

[0093] After deep dehumidification, the air returns to the secondary side of heat exchanger 10, where it exchanges heat with the incoming hot and humid fresh air, absorbing its sensible heat and increasing its own temperature while reducing the relative humidity to a comfortable range. This process does not require additional electrical energy for electric reheating, achieving internal energy recovery and resulting in significant energy savings.

[0094] Working principle of intelligent control:

[0095] Temperature and humidity sensor 9, installed at the air outlet, monitors the air supply status parameters in real time and transmits the signals to the unit controller. The controller compares the measured values ​​with the user-set values ​​and dynamically adjusts the operating frequency of the variable frequency compressor 1 using algorithms such as PID to change the total cooling capacity of the system; at the same time, it adjusts the speed of the variable frequency centrifugal fan 11 to change the fresh air volume.

[0096] The control system monitors the refrigerant temperature and pressure at the outlet of the precooled finned heat exchanger 7, calculates its superheat, and stabilizes the superheat within a preset optimal range by adjusting the opening of the electronic expansion valve 5, thereby ensuring the safe operation of the compressor and optimizing system energy efficiency.

[0097] Finally, it should be noted that the above embodiments are merely examples for clearly illustrating the present invention and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A three-stage heat pump fresh air dehumidifier unit, characterized in that, include: A refrigerant circulation mechanism (100) and an air handling mechanism (200) are provided, wherein the refrigerant circulation mechanism (100) and the air handling mechanism (200) are detachably installed; The refrigerant circulation mechanism (100) includes a compressor (1), a condenser (2), a filter (4), an electronic expansion valve (5), and a gas-liquid separator (8) connected in sequence by pipelines. The compressor (1) has its exhaust port connected to the refrigerant inlet of the condenser (2) via a pipeline; The refrigerant outlet of the condenser (2) is connected to the inlet of the filter (4) via a pipeline; The outlet of the filter (4) is connected to the inlet of the electronic expansion valve (5) via a pipeline; The gas outlet of the gas-liquid separator (8) is connected back to the suction port of the compressor (1) through a pipeline, thereby forming a closed refrigerant circulation loop. The air handling unit (200) includes a duct with an air inlet and an air outlet, and a heat exchanger (10) arranged sequentially in the duct along the direction of fresh air flow. The heat exchanger has a primary duct and a secondary duct that are isolated from each other but can exchange heat. The inlet of the primary duct constitutes the air inlet of the unit for introducing fresh air from the outside. A centrifugal fan (11), which is located downstream of the primary air duct of the heat exchanger (10), is used to drive the airflow; A pre-cooled finned heat exchanger (7) has its finned portion arranged in the duct downstream of the centrifugal fan (11); The cryogenic finned heat exchanger (6) has its finned portion arranged in the air duct downstream of the precooled finned heat exchanger (7); The air duct is configured such that the air flowing out from the cryogenic finned heat exchanger (6) is redirected into the secondary air duct of the heat exchanger (10) and then discharged through the air outlet. In the air handling process, the precooled finned heat exchanger (7) and the cryogenic finned heat exchanger (6) are arranged in series in the air duct to form a stepped cooling and dehumidification of the air. In the refrigerant process, the refrigerant flowing through the cryogenic finned heat exchanger (6) then flows through the precooled finned heat exchanger (7) to provide superheat for the refrigerant. There are two electronic expansion valves (5), which independently control the refrigerant flow into the two cryogenic finned heat exchangers (6); in the refrigerant passage, the precooled finned heat exchanger (7) is connected in series downstream of the cryogenic finned heat exchanger (6) to provide superheat for the refrigerant flowing out of the cryogenic finned heat exchanger (6). The outlet of the electronic expansion valve (5) is connected to the refrigerant inlet of a cryogenic finned heat exchanger (6) via a pipeline. The refrigerant outlet of the cryogenic finned heat exchanger (6) is connected to the refrigerant inlet of a precooled finned heat exchanger (7) via a pipeline. The refrigerant outlet of the precooled finned heat exchanger (7) is connected to the inlet of a gas-liquid separator (8) via a pipeline.

2. The three-stage heat pump fresh air dehumidifier unit according to claim 1, characterized in that, The refrigerant circulation mechanism (100) also includes a bypass solenoid valve (3). The inlet end of the bypass solenoid valve (3) is connected to the pipeline between the exhaust port of the compressor (1) and the condenser (2). The outlet end of the bypass solenoid valve (3) is connected to the pipeline between the outlet of the electronic expansion valve (5) and the inlet of the cryogenic finned heat exchanger (6). It is used to bypass and inject part of the high-temperature gaseous refrigerant to defrost when the cryogenic finned heat exchanger (6) is frosted.

3. The three-stage heat pump fresh air dehumidifier unit according to claim 1, characterized in that, The heat exchanger (10) is a stationary plate-fin sensible heat exchanger.

4. The three-stage heat pump fresh air dehumidifier unit according to claim 1, characterized in that, It also includes a temperature and humidity sensor (9) installed at the air outlet of the unit, and a control system electrically connected to the temperature and humidity sensor (9), the compressor (1) and the centrifugal fan (11).

5. The three-stage heat pump fresh air dehumidifier unit according to claim 4, characterized in that, The control system is configured to automatically adjust the operating frequency of the compressor (1) and the speed of the centrifugal fan (11) based on the deviation between the outlet air temperature and humidity measured by the temperature and humidity sensor (9) and the set value.

6. The three-stage heat pump fresh air dehumidifier unit according to claim 5, characterized in that, The control system is further configured to control the outlet superheat of the refrigerant flowing through the precooled finned heat exchanger (7) to maintain it within a preset range.

7. The three-stage heat pump fresh air dehumidifier unit according to claim 1, characterized in that, The precooled finned heat exchanger (7) and the cryogenic finned heat exchanger (6) are connected together by a water collection tray below, which is used to collect and discharge the condensate generated during the entire cooling and dehumidification process.

8. The three-stage heat pump fresh air dehumidifier unit according to claim 1, characterized in that, The gas-liquid separator (8) is an optional component and can be removed when the unit is used in a stable external environment with stable temperature and humidity. In this case, the refrigerant pipeline is short-circuited accordingly.

9. The three-stage heat pump fresh air dehumidifier unit according to claim 2, characterized in that, The bypass solenoid valve (3) is a normally closed solenoid valve; for each of the cryogenic finned heat exchangers (6), a bypass solenoid valve (3) and corresponding control logic are independently configured to realize independent defrosting control of a single cryogenic finned heat exchanger (6).

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