Fresh air integrated machine of integrated co2 heat pump system

Abstract

This utility model discloses an integrated CO2 heat pump system for fresh air supply, comprising a housing with a fresh air inlet and a fresh air outlet; a primary and secondary efficiency filter, a first heat exchanger, and a second heat exchanger are sequentially installed inside the housing along the fresh air flow direction; the heat pump system using carbon dioxide as refrigerant includes a compressor, a four-way valve, an expansion valve, and a closed refrigerant circuit, the circuit being connected through the four-way valve port so that the compressor exhaust passes sequentially through the first heat exchanger, the expansion valve, and the second heat exchanger before returning to the compressor; a variable frequency fan is installed between the second heat exchanger and the fresh air outlet; temperature and humidity sensors are respectively installed on the outdoor and indoor sides; the controller connects the sensors, the four-way valve, the compressor, and the fan, and has the advantages of dynamically switching between cooling / heating / dehumidification modes and adjusting the fan speed according to environmental parameters.

Description

Technical Field

[0001] This utility model relates to the field of air handling equipment. More specifically, this utility model relates to an integrated fresh air unit with a CO2 heat pump system. Background Technology

[0002] Existing fresh air systems suffer from insufficient heating capacity when operating in low-temperature winter environments. When the outdoor temperature drops below -10°C, traditional Freon refrigerant heat pump systems experience a decrease in compressor suction pressure and refrigerant circulation volume due to the reduced temperature difference between the evaporation temperature and the outdoor temperature. This can result in a reduction in heating capacity of over 40%. Especially when the ambient temperature falls below -20°C, the coefficient of performance (COP) of refrigerants such as R410A is typically below 1.5, making it difficult to meet the heating requirements of fresh air systems.

[0003] Meanwhile, heat pump systems require periodic defrosting in heating mode. Current technologies mostly employ reverse defrosting, which involves switching the system to a cooling cycle via a four-way valve, using the indoor heat exchanger to melt the frost. This process requires stopping the supply of hot air into the room, resulting in an interruption of fresh air supply. Defrosting cycles typically last 5-10 minutes, and in cold regions with high humidity, the defrosting frequency can reach 2-3 times per hour, causing indoor temperature fluctuations and airflow interruptions. While hot air bypass defrosting can maintain airflow, it exacerbates compressor exhaust temperature fluctuations, affecting system reliability.

[0004] Furthermore, energy consumption is a significant issue with fresh air handling. In frigid regions, fresh air heating load accounts for 30%-50% of the building's total load during winter, and conventional electric heating or gas-assisted heating methods are inefficient. For example, electric heating devices have a COP of only 1.0, while gas heating generates emissions. Although heat pump systems are more energy efficient, the compression ratio of traditional refrigerants increases dramatically at low temperatures, leading to a significant increase in compressor power consumption. Experiments show that when the outdoor temperature drops from 0℃ to -15℃, the power of a conventional heat pump compressor increases by about 25%, and the exhaust temperature may exceed safety limits, triggering a protective shutdown.

[0005] These problems result in existing fresh air systems generally suffering from poor heating stability, excessive energy consumption, and insufficient comfort when used in extremely cold regions. Utility Model Content

[0006] One objective of this invention is to provide an integrated fresh air unit with a CO2 heat pump system, in order to at least solve the aforementioned problems.

[0007] To achieve the objectives and other advantages of this utility model, an integrated CO2 heat pump system fresh air unit is provided, comprising a housing, a fresh air inlet and a fresh air outlet disposed on the housing; wherein, a primary and secondary efficiency filter is installed inside the housing, and the primary and secondary efficiency filter is connected downstream of the fresh air inlet; a heat exchanger module is installed inside the housing, the heat exchanger module including a first heat exchanger and a second heat exchanger, the first heat exchanger being located downstream of the primary and secondary efficiency filter, and the second heat exchanger being located downstream of the first heat exchanger; a CO2 heat pump system is installed inside the housing, the CO2 heat pump system including a compressor, a four-way valve, an expansion valve, and a refrigerant charge of CO2. A closed refrigerant circuit is provided, wherein the closed refrigerant circuit is connected in series with the second port of a four-way valve, a first heat exchanger, an expansion valve, a second heat exchanger, and the third port of a four-way valve. The first port of the four-way valve is connected to the output end of the compressor, and the fourth port of the four-way valve is connected to the input end of the compressor. A variable frequency air supply fan is installed inside the housing and is located between the second heat exchanger and the fresh air outlet. A first temperature and humidity sensor is provided on the outdoor side of the housing, and a second temperature and humidity sensor is provided on the indoor side. A controller is also installed inside the housing and is connected to the first temperature and humidity sensor, the second temperature and humidity sensor, the four-way valve, the compressor, and the variable frequency air supply fan.

[0008] Preferably, it further includes a return air inlet and a return air outlet disposed on the casing; wherein, the second heat exchanger has a dual-duct structure, including a fresh air duct and a return air duct that are isolated from each other, the fresh air duct connecting the first heat exchanger and the variable frequency air supply fan, the return air duct connecting the return air inlet and the return air outlet, a return air fan being provided on the return air duct, and the return air fan being connected to the controller; the fresh air duct and the return air duct exchange heat within the second heat exchanger through refrigerant piping.

[0009] Preferably, a high-pressure sensor, a low-pressure sensor, a receiver, and a bypass circuit are added to the closed refrigerant circuit; the high-pressure sensor is installed on the pipeline between the compressor output and the first port of the four-way valve, the low-pressure sensor is installed on the pipeline between the fourth port of the four-way valve and the compressor input, the receiver is located between the third port of the four-way valve and the compressor input, and is downstream of the low-pressure sensor, the bypass circuit connects the receiver outlet and the compressor input, and an electronic expansion valve is provided on the bypass circuit; the high-pressure sensor, the low-pressure sensor, and the electronic expansion valve are all connected to the controller.

[0010] Preferably, a condensate collection tank is provided at the bottom of the housing, located below the first and second heat exchangers. A high-level sensor is installed in the condensate collection tank. The condensate collection tank is connected to the outside of the housing via a drain pipe. A U-shaped water seal bend, an electric heating belt, and an electric three-way valve are connected in series on the drain pipe. The electric heating belt is wrapped around the outer wall of the drain pipe. The first port of the electric three-way valve is connected to the drain pipe, the second port is connected to the external drain pipe, and the third port is connected to the spray branch pipe. The spray branch pipe extends to the fresh air outlet and is equipped with an ultrasonic atomizing nozzle at its end. The high-level sensor, the electric heating belt, the electric three-way valve, and the ultrasonic atomizing nozzle are all connected to the controller.

[0011] Preferably, the primary and secondary filtration device comprises a metal filter screen, an electrostatic electret filter cotton, and an activated carbon adsorption layer arranged sequentially along the fresh air flow direction. The pore size of the metal filter screen is 5 mm, the filtration efficiency of the electrostatic electret filter cotton is ≥90%, and the activated carbon adsorption layer has a basis weight ≥800 g / m³. 2 A honeycomb activated carbon matrix with an iodine value ≥1000 mg / g and silicone sealing strips embedded around it.

[0012] Preferably, the side wall of the housing is provided with a pull-out guide rail, the metal filter and the electrostatic electret filter cotton are detachably installed on the pull-out guide rail, and a differential pressure sensor is integrated at the bottom of the pull-out guide rail. The differential pressure sensor is connected to the controller, and when the differential pressure is greater than a preset threshold, it triggers an alarm to replace the metal filter and the electrostatic electret filter cotton.

[0013] Preferably, the inner wall of the shell is lined with gradient density sound-absorbing cotton, the density of which is 30 kg / m³ from the inside to the outside. 3 60kg / m 3 90kg / m 3 Three floors

[0014] This utility model has at least the following beneficial effects:

[0015] First, by adopting a CO2 refrigerant heat pump system with a dual-heat exchanger series structure, the heating stability in low-temperature environments is significantly improved. The low critical temperature (31.1℃) and high evaporation pressure of CO2 refrigerant allow the system to maintain high cycle efficiency even below -25℃, overcoming the low-temperature heating degradation defects of traditional refrigerants. The closed-loop control by a four-way valve allows for rapid switching between cooling / heating / dehumidification modes. During defrosting, the four-way valve reverses the flow, turning the second heat exchanger into a condenser to melt the frost layer, while the first heat exchanger continuously heats the fresh air, achieving zero air supply interruption during defrosting. The variable frequency fan and temperature / humidity sensor work in conjunction with the controller to dynamically adjust and match the airflow and heat exchange under different loads, avoiding energy waste in conventional equipment under partial load conditions. Overall, the fresh air handling process achieves efficient and continuous operation.

[0016] Secondly, the dual-duct structure's second heat exchanger achieves highly efficient heat recovery from both fresh and exhaust air. Physical isolation between the fresh and return air ducts ensures zero cross-contamination, and the return air fan independently controls the exhaust air flow. The two ducts exchange heat indirectly through refrigerant piping, utilizing exhaust waste heat to preheat or pre-cool the fresh air, significantly reducing the heat pump load under extreme temperatures. Experiments have shown that this structure improves energy recovery by 15%-30% compared to traditional sensible heat recovery devices. The controller automatically adjusts the return air volume based on the indoor and outdoor temperature difference, maximizing energy savings while maintaining fresh air quality, making it particularly suitable for buildings in extremely cold and humid regions.

[0017] Third, high-pressure / low-pressure sensors monitor the transcritical cycle pressure in real time to avoid the risk of overpressure in the CO2 system; the receiver buffers refrigerant flow fluctuations to ensure stable compressor oil return. The bypass circuit, in conjunction with the electronic expansion valve, achieves three core functions: first, during low-temperature startup, the bypass portion discharges to the compressor inlet to prevent excessive pressure differential from causing motor overload; second, it precisely controls the hot gas distribution during the defrost cycle, shortening defrost time; and third, it maintains system pressure balance during sudden load changes. The controller dynamically adjusts the opening of the electronic expansion valve based on sensor data, stabilizing the discharge temperature within a safe range, extending compressor life, and improving system reliability.

[0018] Fourth, the integrated design of the condensate collection tank and the spray system enables water resource recycling. A U-shaped water seal bend blocks internal and external air exchange, while an electric heating element prevents the drain pipe from freezing and clogging. A high-level sensor triggers the controller to activate the spray mode, and an electric three-way valve switches the water flow to the ultrasonic atomizing nozzle, converting the condensate into micron-sized particles that are sprayed into the fresh air outlet. This process produces dual benefits: in the high temperatures of summer, the spray evaporates and absorbs heat, helping to lower the supply air temperature; in the dry winter, it increases the supply air humidity, reducing humidification energy consumption. Overall, it eliminates the energy waste and environmental pollution caused by the external discharge of condensate from traditional equipment.

[0019] The fifth and third-stage composite filtration structure significantly improves pollutant interception efficiency. A 5mm metal mesh blocks large particles such as willow catkins, reducing the load on subsequent filter media; electrostatic electret filter cotton captures PM2.5 particles using charge adsorption, offering superior filtration efficiency compared to ordinary meltblown cotton; high-iodine-value honeycomb activated carbon removes formaldehyde / VOCs through a dual mechanism of physical adsorption and chemical bonding. A silicone sealing strip eliminates leakage at the filter media edges, with a basis weight ≥800g / m³. 2 The matrix ensures sufficient pollutant capacity. This combination achieves longer filtration cycles with the same air resistance, making it particularly suitable for highly polluted environments such as industrial areas.

[0020] Sixth, the integration of the pull-out guide rail and differential pressure sensor simplifies the maintenance process. The guide rail structure allows for tool-free filter replacement, reducing single-person operation time by more than 70%. The differential pressure sensor continuously monitors the pressure drop before and after the filter, automatically triggering an alarm on the controller to prompt replacement when contaminants accumulate and increase system resistance. Compared to traditional timed replacement methods, this design avoids resource waste caused by premature disposal of filter media before it is saturated, and also prevents the risk of secondary pollution caused by using the filter beyond its service life, achieving an optimal balance between maintenance costs and filtration effectiveness.

[0021] Seventh, gradient density sound-absorbing cotton effectively suppresses broadband noise propagation. 30kg / m 3 The low-density layer absorbs the high-frequency fan airflow noise, 90kg / m². 3 High-density layers isolate low-frequency mechanical vibrations of the compressor, with a middle layer of 60 kg / m². 3 The transition layer attenuates mid-frequency noise. The three-layer structure forms a gradually changing acoustic impedance interface, significantly improving noise reduction compared to a single layer of sound-absorbing cotton. This design controls the overall operating noise below 40dB(A), eliminating the interference of heat pump start-up and shutdown on the indoor acoustic environment and meeting the quiet requirements of residential and office spaces.

[0022] Other advantages, objectives and features of this invention will be partly apparent from the following description, and partly understood by those skilled in the art through study and practice of this invention. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the integrated CO2 heat pump system fresh air unit according to an embodiment of the present invention.

[0024] In the diagram, 1. Housing, 2. Fresh air inlet, 3. Fresh air outlet, 4. Primary and secondary filters, 5. First heat exchanger, 6. Second heat exchanger, 7. Compressor, 8. Four-way valve, 9. Expansion valve, 10. Closed refrigerant circuit, 11. Variable frequency air supply fan, 12. First temperature and humidity sensor, 13. Second temperature and humidity sensor, 14. Return air inlet, 15. Return air outlet, 16. Fresh air duct, 17. Return air duct, 18. Return air fan. Detailed Implementation

[0025] The present invention will now be described in further detail with reference to the embodiments and accompanying drawings, so that those skilled in the art can implement it based on the description.

[0026] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0027] It should be noted that, unless otherwise specified, the experimental methods described in the following embodiments are all conventional methods, and the reagents and materials described are all commercially available unless otherwise specified. In the description of this utility model, the terms "lateral", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0028] like Figure 1 As shown, an embodiment of this utility model provides an integrated fresh air unit with a CO2 heat pump system, including a housing 1, a fresh air inlet 2 and a fresh air outlet 3 disposed on the housing 1; wherein, a primary and secondary efficiency filter 4 is installed inside the housing 1, and the primary and secondary efficiency filter 4 is connected downstream of the fresh air inlet 2; a heat exchanger module is installed inside the housing 1, the heat exchanger module including a first heat exchanger 5 and a second heat exchanger 6, the first heat exchanger 5 being located downstream of the primary and secondary efficiency filter 4, and the second heat exchanger 6 being located downstream of the first heat exchanger 5; a CO2 heat pump system is installed inside the housing 1, the CO2 heat pump system including a compressor 7, a four-way valve 8, an expansion valve 9, and a closed refrigerant circuit 10 charged with CO2 refrigerant. The closed refrigerant circuit 10 is connected in series with the second port of the four-way valve 8, the first heat exchanger 5, the expansion valve 9, the second heat exchanger 6, and the third port of the four-way valve 8. The first port of the four-way valve 8 is connected to the output end of the compressor 7, and the fourth port of the four-way valve 8 is connected to the input end of the compressor 7. A variable frequency air supply fan 11 is installed inside the housing 1, and the variable frequency air supply fan 11 is located between the second heat exchanger 6 and the fresh air outlet 3. A first temperature and humidity sensor 12 is provided on the outdoor side of the housing 1, and a second temperature and humidity sensor 13 is provided on the indoor side. A controller is also installed inside the housing 1, and the controller is connected to the first temperature and humidity sensor 12, the second temperature and humidity sensor 13, the four-way valve 8, the compressor 7, and the variable frequency air supply fan 11.

[0029] In the above embodiments, the housing 1 is made of galvanized steel sheet or flame-retardant polypropylene material with a thickness of 1.2mm to 2.0mm. The fresh air inlet 2 and fresh air outlet 3 are located on opposite sides of the housing. The diameter of the fresh air inlet 2 ranges from 200mm to 300mm, and the diameter of the fresh air outlet 3 ranges from 180mm to 280mm, with a center distance of 600mm to 800mm between them. The primary and secondary efficiency filter 4 is bolted to a position 100mm behind the fresh air inlet 2, and its frame dimensions match the duct cross-section. The first heat exchanger 5 is vertically installed 150mm downstream of the primary and secondary efficiency filter 4, and the second heat exchanger 6 is horizontally arranged 300mm behind the first heat exchanger 5. The internal duct cross-section of the housing 1 is 450mm wide and 350mm high, with rounded transitions at duct bends.

[0030] Compressor 7 is a scroll compressor, fixed to the bottom of housing 1 by shock-absorbing pads. A four-way valve 8 is installed 200mm from the discharge port of compressor 7, with its first port connected to the discharge port of compressor 7 via a φ9.52mm copper pipe. The connection sequence of the closed refrigerant circuit 10 is as follows: the second port of four-way valve 8 is connected to the inlet of the first heat exchanger 5; the outlet of the first heat exchanger 5 is connected to the inlet of the second heat exchanger 6 via expansion valve 9; the outlet of the second heat exchanger 6 is connected to the third port of four-way valve 8; and the fourth port of four-way valve 8 returns to the suction port of compressor 7 via a φ12.7mm copper pipe. Expansion valve 9 is a thermostatic expansion valve, with its body installed on a pipe 300mm from the outlet of the first heat exchanger 5.

[0031] The variable frequency air supply fan 11 is a centrifugal fan, installed between the second heat exchanger 6 and the fresh air outlet 3, with the impeller center 180mm from the air outlet surface of the second heat exchanger 6. The first temperature and humidity sensor 12 is fixed to the outer wall of the housing 1, with its probe exposed to the outdoor air. The second temperature and humidity sensor 13 is fixed to the inner wall of the housing 1, with its probe facing indoors. The controller is an industrial-grade PLC, with its input ports connected to the first temperature and humidity sensor 12 and the second temperature and humidity sensor 13, and its output ports connected to the coil of the four-way valve 8, the power module of the compressor 7, and the speed controller of the variable frequency air supply fan 11.

[0032] Work process:

[0033] During the cooling mode operation, when the first temperature and humidity sensor 12 detects that the outdoor temperature exceeds 28°C, the controller switches the four-way valve 8 to the power-off state. The high-temperature CO2 refrigerant discharged from the compressor 7 flows through the first port of the four-way valve 8 to the second port, entering the first heat exchanger 5 to release heat. The outdoor fresh air is cooled at the first heat exchanger 5 after being filtered by the primary and secondary efficiency filters 4. The refrigerant then flows through the expansion valve 9 for throttling and pressure reduction, entering the second heat exchanger 6 to absorb heat from the fresh air and evaporate. The low-temperature gaseous refrigerant flows through the third port of the four-way valve 8 to the fourth port, returning to the compressor 7. The variable frequency fan 11 delivers the cooled fresh air to the room through the fresh air outlet 3 at a speed of 1800-2500 rpm.

[0034] In heating mode, when the first temperature and humidity sensor 12 detects that the outdoor temperature is below 5℃, the controller energizes the four-way valve 8 to reverse the direction. The high-temperature refrigerant discharged from the compressor 7 flows through the first port of the four-way valve 8 to the fourth port, entering the second heat exchanger 6 to release heat. The fresh air flowing through this heat exchanger is heated to 35-45℃. The refrigerant then enters the first heat exchanger 5 after being throttled by the expansion valve 9, absorbing heat from the outdoor fresh air and evaporating. The low-temperature refrigerant flows through the second port of the four-way valve 8 to the third port, returning to the compressor 7. The variable frequency fan 11 automatically adjusts its speed according to the indoor temperature requirement, maintaining the temperature of the fresh air outlet 3 within the set value ±2℃.

[0035] During dehumidification mode operation, when the second temperature and humidity sensor 13 detects that the indoor humidity exceeds 70%, the controller maintains the cooling mode passage of the four-way valve 8 but reduces the speed of the inverter fan 11 to 1000 rpm. Fresh air flows through the primary and secondary filters 4 and then enters the first heat exchanger 5. Due to the heat absorbed by the refrigerant evaporation, the surface temperature of the fins drops below the dew point, causing moisture in the air to condense. The dehumidified, dry air flows through the second heat exchanger 6 and is warmed back to 20-25℃ by the condensation heat of the refrigerant. The controller dynamically adjusts the opening of the expansion valve 9 according to the dehumidification requirements, ensuring that the relative humidity at the fresh air outlet 3 remains stable at 50% ± 5%.

[0036] The mode switching control compares the data from the first temperature and humidity sensor 12 and the second temperature and humidity sensor 13 in real time: when the outdoor temperature is >28℃, the cooling mode is activated first; when the outdoor temperature is <5℃, the heating mode is switched; and when the indoor humidity is >70%, the dehumidification mode is activated. During the mode switching process, the four-way valve 8 has a response time of <3 seconds, and the speed of the variable frequency fan 11 is adjusted by 50 rpm for every 1℃ temperature difference to ensure that the supply air temperature fluctuation does not exceed ±2℃.

[0037] In another embodiment, a return air inlet 14 and a return air outlet 15 are also provided on the housing 1; wherein, the second heat exchanger 6 has a dual-duct structure, including a fresh air duct 16 and a return air duct 17 that are isolated from each other. The fresh air duct 16 is connected between the first heat exchanger 5 and the variable frequency air supply fan 11, and the return air duct 17 is connected between the return air inlet 14 and the return air outlet 15. A return air fan 18 is provided on the return air duct 17, and the return air fan 18 is connected to the controller; the fresh air duct 16 and the return air duct 17 exchange heat in the second heat exchanger 6 through refrigerant pipelines.

[0038] In the above embodiment, a return air inlet 14 with an opening diameter of 220 mm is provided on the side wall of the shell 1; a return air outlet 15 with a diameter of 200 mm is provided on the top of the shell 1. The second heat exchanger 6 adopts a split heat exchange core, and its interior is divided by a 1.0 mm thick galvanized steel plate to form independent fresh air duct 16 and return air duct 17. The fresh air duct 16 has a rectangular cross-section of 300 mm × 150 mm and is directly connected to the outlet of the first heat exchanger 5; the return air duct 17 has a cross-section of 280 mm × 140 mm, and its inlet end is connected to the flange of the return air inlet 14. The edges of the duct partition are fitted with EPDM rubber sealing strips, and the compression is controlled to 30% of the original thickness.

[0039] The return air fan 18 is an axial flow fan with an impeller diameter of 180mm. It is fixed to the middle of the return air duct 17 by a bracket, 400mm from the inlet. The refrigerant piping uses φ7mm copper pipes. Ten rows of pipes are arranged in the fresh air duct 16, and eight rows of pipes are arranged in the return air duct 17. The two sets of pipes are connected in series by a U-shaped bend to form a continuous flow path. Working process: Indoor return air enters the return air duct 17 through the return air inlet 14. When flowing through the refrigerant piping, it releases heat to the refrigerant in winter and absorbs the cold energy of the refrigerant in summer. Fresh air flows in the opposite direction in the adjacent fresh air duct 16 for heat exchange. The controller adjusts the speed of the return air fan 18 according to the temperature difference between the first temperature and humidity sensor 12 and the second temperature and humidity sensor 13: when the temperature difference is ≥8℃, the base speed of 800rpm is started, and the speed is increased by 60rpm for every 1℃ increase in temperature difference.

[0040] This implementation method enables physical isolation heat exchange between fresh air and exhaust air, utilizes exhaust air energy to pre-treat fresh air, and reduces the load on the heat pump system; the sealed isolation structure prevents cross-contamination of air; and the dynamic adjustment function of return air volume adapts to different temperature difference conditions, improving the operational stability in cold and humid regions.

[0041] In another embodiment, a high-pressure sensor, a low-pressure sensor, a liquid receiver, and a bypass circuit are added to the closed refrigerant circuit 10. The high-pressure sensor is installed on the pipeline between the output end of the compressor 7 and the first port of the four-way valve 8. The low-pressure sensor is installed on the pipeline between the fourth port of the four-way valve 8 and the input end of the compressor 7. The liquid receiver is located between the third port of the four-way valve 8 and the input end of the compressor 7, and is downstream of the low-pressure sensor. The bypass circuit connects the outlet of the liquid receiver to the input end of the compressor 7, and an electronic expansion valve is provided on the bypass circuit. The high-pressure sensor, the low-pressure sensor, and the electronic expansion valve are all connected to the controller.

[0042] In the above embodiment, a high-pressure sensor is installed on the refrigerant line between the compressor discharge port and the first port of the four-way valve. The detection point is no more than 300 mm from the compressor discharge port. The high-pressure sensor's range is set to 0 to 15 MPa, with a measurement accuracy of ±0.2 MPa. A low-pressure sensor is installed on the line between the fourth port of the four-way valve and the compressor suction port. The detection point is located 200 mm from the compressor suction port, and the range is 0 to 5 MPa. A 1.2-liter 304 stainless steel receiver is used, installed 400 mm downstream of the low-pressure sensor, and connected to a φ12.7 mm copper pipe via a flange. A φ2 mm oil return hole is provided at the bottom of the receiver.

[0043] The bypass circuit uses a φ4 mm copper pipe to connect the liquid receiver outlet and the compressor suction port, with the total pipe length controlled within 550 mm. The electronic expansion valve is a stepper motor driven type, with the valve body installed in the middle section of the bypass pipe, and the valve port flow diameter is 2.5 mm. During assembly, ensure a 25 mm distance between the bypass pipe and the main pipe, and wrap the pipe wall with 10 mm thick rubber-plastic insulation material. The electronic expansion valve opening adjustment range is 0 to 500 pulses, with a response time ≤0.5 seconds.

[0044] The controller monitors high and low pressure sensor data in real time: when the high pressure exceeds 12.0 MPa, the electronic expansion valve opens to 30% to release pressure; when the low pressure is below 2.0 MPa, the electronic expansion valve closes and the compressor operating frequency is increased. During the -15℃ low-temperature start-up phase, the controller keeps the electronic expansion valve open at 35% for 3 minutes, allowing some high-temperature refrigerant to bypass to the compressor suction end. During the defrost cycle, based on the temperature data of the second heat exchanger fins, the opening of the electronic expansion valve is adjusted by 4 percentage points for every 1℃ temperature difference to control the hot gas distribution.

[0045] This implementation method enables safe monitoring and dynamic adjustment of refrigerant system pressure, avoiding the risk of CO2 transcritical cycle overpressure; the liquid receiver effectively buffers refrigerant flow fluctuations, ensuring compressor oil return stability; and the bypass circuit maintains system pressure balance under extreme operating conditions, improving equipment operational reliability.

[0046] In another embodiment, a condensate collection tank is provided at the bottom of the housing 1, located below the first heat exchanger 5 and the second heat exchanger 6. A high liquid level sensor is provided in the condensate collection tank. The condensate collection tank is connected to the outside of the housing 1 through a drain pipe. A U-shaped water seal bend, an electric heating belt, and an electric three-way valve are connected in series on the drain pipe. The electric heating belt is wrapped around the outer wall of the drain pipe. The first port of the electric three-way valve is connected to the drain pipe, the second port is connected to the external drain pipe, and the third port is connected to the spray branch pipe. The spray branch pipe extends to the fresh air outlet 3 and is equipped with an ultrasonic atomizing nozzle at its end. The high liquid level sensor, the electric heating belt, the electric three-way valve, and the ultrasonic atomizing nozzle are all connected to the controller.

[0047] In the above embodiment, a stainless steel condensate collection tank, 300mm long, 200mm wide, and 80mm deep, is provided at the bottom of the shell 1, located directly below the first heat exchanger 5 and the second heat exchanger 6. The bottom of the tank slopes at 5° towards the drain outlet, and a float-type high-level sensor is installed inside the tank, with a trigger height set to 60mm. The drain pipe is a φ20mm PVC pipe, connected sequentially from the drain outlet of the collection tank to: a U-shaped water seal bend (100mm high), a straight pipe section (200mm long) wrapped with electric heating tape, and an electric three-way valve. The electric heating tape can be a 15W / m self-regulating temperature tracing tape, and the electric three-way valve can be a 24VDC driven brass valve body.

[0048] The spray branch pipe is made of φ8mm 304 stainless steel and extends from the third port of the electric three-way valve to 50mm above the inner wall of the fresh air outlet 3. An ultrasonic atomizing nozzle is installed at the end of the branch pipe; a ceramic atomizing plate assembly with a working frequency of 1.7MHz and an atomization rate of 100mL / h can be selected. The controller is connected to the high liquid level sensor, the electric heating belt temperature controller, the electric three-way valve drive module, and the power supply for the atomizing nozzle. The electric heating belt temperature is set to 35℃±2℃, and the water filling depth of the U-shaped water seal bend is ≥80mm.

[0049] When the high liquid level sensor is triggered, the controller performs the following actions: activating the electric heating belt for 30 seconds of preheating; switching the electric three-way valve to the third port; and connecting the power supply to the ultrasonic atomizing nozzle. Condensate is then transported through the spray branch pipe to the fresh air outlet 3, where it is atomized into 5-10μm particles and sprayed into the airflow. In summer mode (outdoor temperature > 30℃), spraying continues until the liquid level drops to 20mm; in winter mode (outdoor temperature < 5℃), spraying for 2 minutes at 10% humidity deviations. The second port of the electric three-way valve is connected to an external drain pipe, switching to drain mode in case of a spray system malfunction. The high liquid level sensor reset threshold is when the liquid level drops to 30mm.

[0050] This implementation method enables the utilization of condensate resources. In summer, it uses spray evaporation cooling to help reduce the supply air temperature and in winter, it increases the supply air humidity to reduce humidification energy consumption. The U-shaped water seal bend effectively blocks air exchange, and the electric heating belt prevents the pipes from freezing. It intelligently switches between drainage and spray modes to avoid energy waste and environmental pollution caused by direct discharge from traditional equipment.

[0051] In another embodiment, the primary and secondary filtration device includes a metal filter screen, an electrostatic electret filter cotton, and an activated carbon adsorption layer arranged sequentially along the fresh air flow direction. The pore size of the metal filter screen is 5 mm, the filtration efficiency of the electrostatic electret filter cotton is ≥90%, and the activated carbon adsorption layer has a basis weight ≥800 g / m³. 2 A honeycomb activated carbon matrix with an iodine value ≥1000 mg / g and silicone sealing strips embedded around it.

[0052] In the above embodiment, the pore size of the metal filter can be 5mm, with an allowable tolerance range of ±0.1mm. The metal filter can be made of 304 stainless steel perforated plate with a perforation rate of 45%. The filter frame can be made of 1.2mm thick aluminum alloy profile with an anodized surface treatment. The metal filter is installed at the very front of the primary and secondary efficiency filter device, 100mm downstream of the fresh air inlet, and is fixed to the slot in the filter device frame with bolts. When the fresh air flow passes vertically through the metal filter, foreign objects with a particle size ≥5mm, such as willow catkins and flying insects, are intercepted. A 3mm thick rubber sealing strip is pressed around the filter to prevent airflow bypass.

[0053] Electrostatic electret filter cotton can be made of melt-blown polypropylene material, with a thickness of 10mm and a filtration efficiency of not less than 90% (test conditions: 0.3μm NaCl aerosol, flow rate 32L / min). The filter cotton surface is electret treated, with a charge density ≥50μC / m². 2 The filter cotton frame can be made of ABS plastic injection molding with internal reinforcing ribs. This filter cotton layer is installed 50mm downstream of the metal filter screen and is embedded into the filter device frame through a slot-type structure. When airflow passes through, PM2.5 particles are captured due to electrostatic adsorption. The capture efficiency decreases over time and the filter cotton can be replaced.

[0054] The activated carbon adsorption layer can be made of a honeycomb matrix with a single pore diameter of 3 mm and a pore density of ≥100 pores / m³. 2 The matrix basis weight can be selected as 800 g / m³. 2The coal-based activated carbon has an iodine adsorption value ≥1000mg / g (tested according to GB / T 12496.8 standard). A 2mm thick silicone sealing strip is embedded around the honeycomb structure; after compression installation, the deformation of the sealing strip reaches 30% of its original height. This adsorption layer is installed 80mm downstream of the electrostatic electret filter cotton and pushed into the end of the filter device via a sliding rail structure. When fresh air passes through, formaldehyde molecules are captured through physical adsorption, and VOCs pollutants form chemical bonds with the functional groups on the activated carbon surface.

[0055] In this implementation, outdoor fresh air enters through the inlet and first passes through a metal filter to intercept large particles. It then flows through an electrostatic electret filter to remove fine particles, and finally passes through an activated carbon layer to adsorb gaseous pollutants. Silicone sealing strips ensure the edges of each layer are sealed, preventing unfiltered air leakage. This three-stage filtration structure achieves multi-stage pollutant interception under a wind resistance of 150Pa. The metal filter reduces the load on subsequent filter media, the electrostatic electret filter extends the high-efficiency filtration cycle, and the honeycomb activated carbon provides ample adsorption capacity. This design ensures filtration efficiency while reducing maintenance frequency and minimizing the risk of secondary pollution.

[0056] In another embodiment, the side wall of the housing 1 is provided with a pull-out guide rail. The metal filter and the electrostatic electret filter cotton are detachably installed on the pull-out guide rail. A differential pressure sensor is integrated at the bottom of the pull-out guide rail. The differential pressure sensor is connected to the controller. When the differential pressure is greater than a preset threshold, an alarm is triggered to replace the metal filter and the electrostatic electret filter cotton.

[0057] In the above embodiments, the slide rail travel can be 300mm or 450mm, and the rail width can be 30mm or 50mm. The rail body can be made of 6063 aluminum alloy profile with anodized surface treatment, and the slide rail assembly can be a three-section ball bearing slide rail. The rail is installed longitudinally along the side wall of the housing, with the center line 80mm from the edge of the housing, and symmetrically arranged on both sides in the installation area of ​​the primary and secondary efficiency filter devices. A limiting buckle is provided at the end of the rail to prevent the filter assembly from completely falling out. M6 threaded mounting holes with a hole spacing of 150mm are reserved at the bottom of the rail for fixing the differential pressure sensor.

[0058] The metal filter frame can be made of 1.5mm thick 5052 aluminum alloy, bent and formed, with an internally welded φ5mm perforated stainless steel plate. The electrostatic electret filter cotton frame can be made of 2.0mm thick ABS plastic injection molded parts, with 2mm deep grooves around the perimeter. When the filter assembly is inserted along the guide rail, 5mm thick polyurethane sealing strips are embedded on both sides of the frame, with a compression amount reaching 40% of the original thickness. After installation, the front end of the filter should be 20mm away from the inlet surface of the primary and secondary efficiency filter, and the rear end should have a gap of no more than 1mm from the duct wall. When disassembling, hold the frame handle and pull it outward; the resistance of the slide rail should be controlled within the range of 3-5N.

[0059] The differential pressure sensor can be a capacitive differential pressure transmitter with a range of 0-500Pa, installed at the bottom center of the guide rail, and connected to the front and rear chambers of the filter via φ4mm pressure sensing tubes. The sensor trigger threshold can be set to 200Pa or 250Pa. When the measured differential pressure exceeds the threshold for 10 seconds, the controller will issue an audible and visual alarm signal. The sensor housing can be made of flame-retardant ABS material, and the signal cable uses RVVP 2×0.75mm. 2 The shielded cable is connected to the controller input port. Alarm reset requires manual clearing; the alarm will automatically stop when the differential pressure drops below 150 Pa after filter replacement.

[0060] In this implementation, as fresh air flows through the metal filter and electrostatic electret filter cotton, particulate matter gradually accumulates, causing the pressure difference across the filter to increase. A differential pressure sensor monitors resistance changes in real time. When pollutant accumulation causes the pressure difference to exceed the 200Pa threshold, the controller triggers an alarm to prompt maintenance. The operator removes the filter assembly along the pull-out guide rail for replacement. After the new filter is inserted, the sealing strip compresses to form an airtight interface. This structure simplifies maintenance, avoiding the time-consuming disassembly of traditional bolt-fixing methods. The threshold alarm mechanism accurately determines the filter's saturation state, preventing premature replacement that leads to waste or premature use that causes a decrease in airflow. The standardized design of the guide rail and filter assembly ensures airtightness after replacement, reducing the risk of secondary pollution.

[0061] In another embodiment, the inner wall of the housing 1 is lined with gradient density sound-absorbing cotton, the density of which is 30 kg / m³ from the inside to the outside. 3 60kg / m 3 90kg / m 3 Three floors.

[0062] In the above embodiment, the three-layer density of the gradient density sound-absorbing cotton can be selected as 30 kg / m³. 3 60kg / m 3 90kg / m 3 The polyester fiber material can be configured with thicknesses of 10mm, 15mm, and 20mm. The innermost layer weighs 30kg / m². 3 Low-density sound-absorbing cotton can be made of flexible fiber felt with an open area ratio of ≥95%, and a core density of 60kg / m². 3 The outermost layer can be made of a mixture of glass wool and polyester fiber pressed board, with a weight of 90 kg / m². 3 The high-density layer can be made of phenolic resin composite fiberglass board. The layers are bonded together with hot melt adhesive, and the total thickness is controlled within 45mm. The gap between the edge of the sound-absorbing cotton and the inner wall of shell 1 does not exceed 0.5mm, and it is directly attached to the inner surface of the metal wall of the shell using a high-temperature resistant adhesive.

[0063] 30kg / m 3The low-density layer faces the internal airflow channel of the equipment, maintaining a 5mm cavity between it and the inner wall of the casing 1, to absorb high-frequency fan airflow noise above 3000Hz. A 60kg / m³ transition layer is directly bonded to the back of the low-density layer, attenuating 800-3000Hz mid-frequency noise through its interwoven fiber structure. The 90kg / m³ high-density layer is tightly attached to the metal wall of the casing 1, secured with self-tapping screws at 200mm intervals, suppressing low-frequency compressor mechanical vibration sound waves below 200Hz. During installation, layers are laid sequentially from the bottom of the casing 1 upwards, with 45° beveled overlaps at the joints, and an overlap width ≥30mm. A 5mm expansion joint is reserved at the edges of each layer, filled with silicone sealant to buffer thermal expansion and contraction.

[0064] When the equipment is running, the high-frequency noise from the fan airflow penetrates to 30 kg / m³. 3 Low-density layers are absorbed by porous structures; low-frequency vibrations of the compressor are transmitted up to 90 kg / m³. 3 In high-density layers, the acoustic impedance is abruptly reduced by reflection; mid-frequency noise is at 60 kg / m². 3 The transition layer converts heat energy through fiber friction. The three-layer density gradient structure creates broadband sound absorption characteristics, avoiding sound wave reflection in certain frequency bands caused by single-density materials. This design achieves full-frequency noise reduction within a limited space, eliminating the failure problem of traditional single-layer sound-absorbing cotton in the mid-low frequency band, while avoiding the volume expansion caused by using heavy sound insulation materials.

[0065] The number of devices and processing capacity described herein are for simplification. Applications, modifications, and variations of this integrated CO2 heat pump system for fresh air systems will be readily apparent to those skilled in the art.

[0066] Although the embodiments of this utility model 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 this utility model. 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, this utility model is not limited to the specific details and the illustrations shown and described herein.

Claims

1. Integrated CO2 heat pump system's fresh air all-in-one machine, characterized in that, Includes a housing, a fresh air inlet and a fresh air outlet mounted on the housing; wherein, A primary and secondary efficiency filter is installed inside the housing, and the primary and secondary efficiency filter is connected downstream of the fresh air inlet. A heat exchanger module is installed inside the housing. The heat exchanger module includes a first heat exchanger and a second heat exchanger. The first heat exchanger is located downstream of the primary and secondary efficiency filter device, and the second heat exchanger is located downstream of the first heat exchanger. A CO2 heat pump system is installed inside the housing. The CO2 heat pump system includes a compressor, a four-way valve, an expansion valve, and a closed refrigerant circuit charged with CO2 refrigerant. The closed refrigerant circuit is connected in series with the second port of the four-way valve, the first heat exchanger, the expansion valve, the second heat exchanger, and the third port of the four-way valve. The first port of the four-way valve is connected to the output end of the compressor, and the fourth port of the four-way valve is connected to the input end of the compressor. A variable frequency air supply fan is installed inside the housing, and the variable frequency air supply fan is located between the second heat exchanger and the fresh air outlet; The housing has a first temperature and humidity sensor on the outdoor side and a second temperature and humidity sensor on the indoor side. The housing also contains a controller, which is connected to the first temperature and humidity sensor, the second temperature and humidity sensor, the four-way valve, the compressor, and the variable frequency air supply fan.

2. The integrated CO2 heat pump system of claim 1, wherein, It also includes a return air inlet and a return air outlet disposed on the shell; wherein, the second heat exchanger has a dual-duct structure, including a fresh air duct and a return air duct that are isolated from each other, the fresh air duct being connected between the first heat exchanger and the variable frequency air supply fan, the return air duct being connected between the return air inlet and the return air outlet, the return air duct being provided with a return air fan, and the return air fan being connected to the controller; the fresh air duct and the return air duct exchange heat in the second heat exchanger through refrigerant pipelines.

3. The integrated CO2 heat pump system of claim 1, wherein, A high-pressure sensor, a low-pressure sensor, a liquid receiver, and a bypass circuit are added to the closed refrigerant circuit. The high-pressure sensor is installed on the pipeline between the compressor output and the first port of the four-way valve. The low-pressure sensor is installed on the pipeline between the fourth port of the four-way valve and the compressor input. The liquid receiver is located between the third port of the four-way valve and the compressor input, and is downstream of the low-pressure sensor. The bypass circuit connects the liquid receiver outlet and the compressor input. An electronic expansion valve is provided on the bypass circuit. The high-pressure sensor, the low-pressure sensor, and the electronic expansion valve are all connected to the controller.

4. The integrated CO2 heat pump system of claim 1, wherein, A condensate collection tank is located at the bottom of the housing, below the first and second heat exchangers. A high-level sensor is installed in the condensate collection tank. The condensate collection tank is connected to the outside of the housing via a drain pipe. A U-shaped water seal bend, an electric heating element, and an electric three-way valve are connected in series on the drain pipe. The electric heating element is wrapped around the outer wall of the drain pipe. The first port of the electric three-way valve is connected to the drain pipe, the second port is connected to the external drain pipe, and the third port is connected to the spray branch pipe. The spray branch pipe extends to the fresh air outlet and has an ultrasonic atomizing nozzle at its end. The high-level sensor, the electric heating element, the electric three-way valve, and the ultrasonic atomizing nozzle are all connected to the controller.

5. The integrated CO2 heat pump system of claim 1, wherein, The primary and secondary filtration device includes a metal filter screen, an electrostatic electret filter cotton, and an activated carbon adsorption layer arranged sequentially along the fresh air flow direction. The pore size of the metal filter screen is 5mm, the filtration efficiency of the electrostatic electret filter cotton is ≥90%, and the activated carbon adsorption layer has a basis weight ≥800g / m³. 2 A honeycomb activated carbon matrix with an iodine value ≥1000 mg / g and silicone sealing strips embedded around it.

6. The integrated CO2 heat pump system of claim 5, wherein, The side wall of the housing is provided with a pull-out guide rail. The metal filter and the electrostatic electret filter cotton are detachably installed on the pull-out guide rail. A differential pressure sensor is integrated at the bottom of the pull-out guide rail. The differential pressure sensor is connected to the controller. When the differential pressure is greater than a preset threshold, an alarm is triggered to replace the metal filter and the electrostatic electret filter cotton.

7. The integrated CO2 heat pump system of claim 1, wherein, The inner wall of the shell is attached with gradient density sound absorption cotton, and the density of the gradient density sound absorption cotton is 30kg / m 3 , 60kg / m 3 , 90kg / m 3 from inside to outside in turn.

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