Air handling unit with carbon dioxide refrigerant circuit, electronic control unit, HVAC system, and method

Abstract

A method and an air handling unit (50, 100, ... 650) having an ECU (800). The ECU includes heat exchange functional components, a first coil (703) air cooler, a carbon dioxide (R744) refrigerant circuit, and an integrated cooling and heating module with or without carbon dioxide pressure optimization (750). The first coil (703) is placed in the exhaust duct to receive non-hot air from the building. The integrated cooling and heating module is used for heat exchange with the first coil (703) air cooler and a second coil (702), which is placed in the air supply duct of the AHU leading to the building (900). When the first coil (703) is placed after the heat exchange function component in the exhaust airflow / channel (23), the ECU (800) can control or regulate the air temperature (801) at the first coil (703) by adjusting the efficiency (53, 103, 303, 503) of the heat exchange function component (52). Specific adjustments include: adjusting the bypass valves (53, 103) of the bypass channel for the cross-flow / counter-flow plate heat exchanger, adjusting the rotational speed (303) of the rotary heat exchanger, and / or adjusting the liquid flow rate (503) in the coiled tube heat exchanger (RAC). Through these adjustments, the efficiency of the carbon dioxide refrigerant cycle is maximized.

Description

(19) State Intellectual Property Office (12) Invention Patent Application (10) Application Publication Number (43) Application Publication Date (21) Application Number 202480065711.9 (22) Application Date 2024.10.03 (30) Priority Data 2330459-5 2023.10.15 SE (85) PCT International Application Entering National Phase Date 2026.04.13 (86) PCT International Application Application Data PCT / SE2024 / 050843 2024.10.03 (87) PCT International Application Publication Data WO2025 / 084972 EN 2025.04.24 (71) Applicant: Fleck Group Sweden AG Address: Jönköping County, Sweden (72) Inventor: Dušan Stamenković, Urban Kronstrom (74) Patent Agency: Beijing Sanju Sunshine Intellectual Property Agency Co., Ltd. 11250 Patent Attorney Cheng Gang (51) Int.Cl. F24F 12 / 00 (2006.01) F24F 11 / 30 (2006.01) F25B 9 / 00 (2006.01) (54) Invention Title Air Handling Unit with Carbon Dioxide Refrigerant Circuit, Electronic Control Unit, HVAC System and Method (57) Abstract A method and an air handling unit (50, 100, ... 650) having an ECU (800). The ECU includes heat exchange functional components, a first coil (703) air cooler, a carbon dioxide (R744) refrigerant circuit, and an integrated cooling and heating module with or without (700) carbon dioxide pressure optimization (750). The first coil (703) is placed in an exhaust duct to receive non-heated air from the building. The integrated cooling and heating module is used for heat exchange with the first coil (703) air cooler and the second coil (702), which is placed in the air supply duct from the AHU to the building (900). When the first coil (703) is placed after the heat exchange function component in the exhaust airflow / channel (23), the ECU (800) can control or regulate the air temperature (801) at the first coil (703) by adjusting the efficiency (53, 103, 303, 503) of the heat exchange function component (52). Specific adjustment methods include: adjusting the bypass valves (53, 103) of the bypass channel for the cross-flow / counterflow plate heat exchanger, adjusting the rotational speed (303) of the rotary heat exchanger, and / or adjusting the liquid flow rate (503) in the coiled tube heat exchanger (RAC). Through the above adjustments, the efficiency of the carbon dioxide refrigerant cycle is maximized.Claims 4 pages, Description 27 pages, Drawings 16 pages, CN 122029386 A 2026.05.12 CN 1 22 02 93 86 A 1. An air handling unit (50; 100, 150, 200, 250; 300, 350, 400, 450; 500, 550, 600, 650), comprising: an outdoor airflow channel (21); an air supply channel (22); an exhaust channel (23); an exhaust channel (24); and a heat exchange functional component (52), wherein the heat exchange functional component (52) is one of the following: a cross-flow / counter-flow plate heat exchanger PHE (102). A rotary heat exchanger RHE (302) or a coiled tube heat exchange system RAC (502); and a carbon dioxide (R744) refrigerant circuit (760, 700, 750), the carbon dioxide (R744) refrigerant circuit (760, 700, 750) comprising: a first coil (703) placed between the exhaust duct (23) and the exhaust channel (24); a second coil (702) placed between the heat exchange functional component (52) and the air supply duct (22); and a first coil air inlet temperature sensor T (801); wherein the carbon dioxide (R744) refrigerant circuit (760, 700, 750) is configured for heat transfer between the first coil (703) and the second coil (702), characterized in that, The first coil (703) is configured to exchange heat with an airflow originating from the exhaust duct (23), which may be air received from inside the building (900). 2. The air handling unit (100, 200, 300, 400, 500, 600) according to claim 1, characterized in that the carbon dioxide (R744) refrigerant circuit (760) is an integrated carbon dioxide cooling and heating module (700). 3. The air handling unit (150, 250; 350, 450; 550, 650) according to claim 1, characterized in that the carbon dioxide (R744) refrigerant circuit (760) is an advanced integrated cooling and heating module (750) with carbon dioxide pressure optimization. 4. The air handling unit (100, 150; 300, 350; 500, 550) according to any one of claims 1-3, characterized in that the first coil (703) is placed between the exhaust duct (23) and the heat exchange functional component (52).5. An air handling unit (100, 150, 300, 350, 500, 550) according to any one of claims 1-4, characterized in that it is configured to: receive exhaust air through the exhaust duct (23) and via the first coil air inlet temperature sensor T (801), send it to the first coil (703), and then send it to the heat exchange functional component (52); the heat exchange functional component (52) is: a cross-flow / counterflow plate heat exchanger PHE (102), a rotary heat exchanger RHE (302), or a coiled tube heat exchange system RAC (502). 6. An air handling unit (200, 250, 400, 450, 600, 650) according to any one of claims 1-3, characterized in that: the first coil (703) is placed between the heat exchange functional component (52) and the exhaust duct (24). 7. An air handling unit (200, 250; 400, 450; 600, 650) for cold energy recovery according to any one of claims 1-3, 6, characterized in that it is configured to: receive exhaust air via exhaust duct (23), send it to exhaust room / building temperature sensor Ti 803, and then send it to the heat exchange functional component (52), which is: a cross-flow / counter-flow plate heat exchanger PHE (102), a rotary heat exchanger RHE (302), or a coiled tube heat exchange system RAC (502); then send it to the first coil air inlet temperature sensor T (801); and then send it to the first coil (703). 8. An air handling unit (100, 150, 200, 250) according to any one of claims 1-7, characterized in that: the heat exchange functional component (52) is a cross-flow / counter-flow plate heat exchanger (PHE) (102). 9. The air handling unit (300, 350, 400, 450) according to any one of claims 1-7, characterized in that: the heat exchange functional component (52) is a rotary heat exchanger (RHE) (302). 10. The air handling unit (500, 550, 600, 650) according to any one of claims 1-7, characterized in that: the heat exchange functional component (52) is a coiled tube heat exchange system (RAC) (502). 11. The air handling unit (100, 150, 200, 250) according to any one of claims 8-10, characterized in that it further includes a bypass valve (53), which is configured such that: when the bypass valve (52) is opened, at least a portion of the airflow can bypass the heat exchange functional component (52).12. The air handling unit (300, 350, 400, 450) according to claim 9, characterized in that it further comprises a rotary heat exchanger (RHE) controlled at rotational speed per minute (RPM), which can be used to adjust the efficiency of the RHE heat exchange. 13. The air handling unit (500, 550, 600, 650) according to claim 10, characterized in that it further comprises a system fluid flow control actuator for a retractable heat exchanger (RAC), which is used to adjust the efficiency of the RAC heat exchange. 14. The air handling unit (200; 250; 400, 450; 600, 650) according to any one of claims 1-13, characterized in that it further comprises: the exhaust room / building temperature sensor (803), configured to receive the value of the exhaust room / building temperature sensor (803). 15. An electronic control unit (ECU) (800) configured to control an air handling unit (AHU) (50; 100, 150, 200, 250; 300, 350, 400, 450; 500, 550, 600, 650) according to any one of claims 1-14, characterized in that it comprises: electronic control unit hardware (ECUHW) (810) for sensor data processing and optimization of AHU operation; an interface connected to a first coil air inlet temperature sensor T (801), the first coil air inlet temperature sensor T (801) being configured to sense the temperature at the air inlet of the first coil (703); and an interface to an exhaust airflow temperature sensor Ti (803), the exhaust airflow temperature sensor Ti (803) being configured to sense the temperature at the exhaust duct (23) or the temperature inside a building or room (900); The determination function module (804) is configured to: determine a heat exchange efficiency control signal (806) based on the data of the first coil air inlet temperature sensor T (801) and the data of the exhaust airflow temperature sensor Ti (803) collected on demand; control the efficiency of the AHU heat exchanger based on the heat exchange efficiency control signal (806) so that the air inlet temperature of the first coil (703) is maintained within the optimal target range (802) of the first coil air inlet temperature sensor T (801); and adjust the efficiency of the heat exchange function component (52) based on the heat exchange efficiency control signal (806) to regulate: the actuator (821) for the PHE bypass valve, the regulator (822) for the RHE speed, or the regulator (823) for the RAC fluid flow rate.16. The ECU (800) according to claim 15, further comprising: a learning function module (805) for providing feedback adjustment to the control function in the determination function module (804) based on the control history. 17. The ECU (800) according to any one of claims 15 to 16, further comprising: a sensor T optimal target range setting module (802), and / or a system configuration file (812), the system configuration file (812) defining at least one optimal temperature target range (802). 18. The ECU (800) according to any one of claims 15-17, wherein the ECU is configured as a software-based cloud service for interfacing with and controlling at least one air handling unit (AHU) (50; 100, 150, 200, 250; 300, 350, 400, 450; 500, 550, 600, 650) according to claims 1-13. 19. An air handling unit (50, 100, 150, 200, 250; 300, 350, 400, 450; 500, 550, 600, 650) according to any one of claims 1-14, characterized in that it further comprises: an ECU (800) according to any one of claims 14-18, configured to: control the air handling unit (50, 100, 150, 200, 250; 300, 350, 400, 450; 500, 550, 600, 650), and / or control an AHU (50, 200, 250; 400, 450; 600, 650) with cold energy recovery, such that the detected temperature of the first coil air inlet temperature sensor T (801) is maintained within an optimal range.20. A method for improving the cooling capacity recovery efficiency and system efficiency of an air handling unit (AHU) according to any one of claims 1-14 and 19, the method being performed by an electronic control unit (ECU) (800) according to any one of claims 15-18, characterized by comprising the following steps: (S1000) receiving the first coil air inlet temperature collected by a sensor T (801); (S1200) receiving the temperature collected by an exhaust room / building temperature sensor Ti (803); (S2000) determining the adjustment requirement (804) to generate a heat exchange efficiency control signal (806); bringing the transcritical or subcritical refrigerant cycle to and maintaining its optimal state, and maintaining the first coil (703) air inlet temperature at sensor T (801) within the optimal temperature range (802) for a carbon dioxide transcritical or subcritical cycle air cooler; (S3000) using the heat exchange efficiency control signal (806) to adjust the heat exchange efficiency control parameters in the following manner: (S3100) Regulate the rotational speed (303) of the rotary heat exchanger (302); Claims 3 / 4, page 4, CN 122029386 A (S3200) Regulate the bypass valve for the cross-flow / counter-flow heat exchanger (102); or (S3300) Regulate the fluid flow rate of the coiled tube heat exchange system (RAC) (502) to achieve efficient cold recovery and maximum system efficiency. 21. The method according to claim 20, further comprising: performing step (S1100) before step (S2000), wherein step (S1100) comprises: (S1100) setting an optimal target temperature range (OTTR) (802) for the temperature sensor T, such that the optimal target temperature range is used in step (S2000) to determine the adjustment requirements for the heat exchanger efficiency. 22. The method according to any one of claims 20-21, characterized in that it further comprises: performing step (S1200) before step (S2000), wherein step (S1200) comprises: (S1200) obtaining the exhaust air temperature from the room / building (TTR) (801), such that in step (S2000) the exhaust air temperature determination (804) from the room / building is used to adjust the demand, i.e., generating a heat exchange efficiency control signal (806) to adjust the heat exchanger efficiency. 23. The method according to any one of claims 20-22, characterized in that it further comprises: the optimal temperature target range (802) of the temperature sensor T is set between 15 degrees Celsius and 40 degrees Celsius, preferably between 20 and 32 degrees Celsius.24. The method according to any one of claims 20-23, characterized in that it further comprises: performing step (S4000) after step (S3000), wherein step (S4000) comprises: (S4000) learning, or feedback adjusting the adjustment loop to optimize control parameters for: determining the adjustment requirements for heat exchanger efficiency in step (S2000). 25. A heating, ventilation, and air conditioning (HVAC) system (20) comprising at least one air handling unit (AHU) (50; 100, 150, 200, 250; 300, 350, 400, 450; 500, 550, 600, 650) according to any one of claims 1-14 or 19, characterized in that the exhaust duct (23) is connected to the interior of a building (900), vehicle, train, or ship. 26. A building or vehicle, characterized in that it includes an HVAC system (20) according to claim 25, or an air handling unit (50, 100...650) according to any one of claims 1-14 or 19. Claims 4 / 4 pages 5 CN 122029386 A Air handling unit with carbon dioxide refrigerant circuit, electronic control unit, HVAC system and method Technical Field

[0001] The present invention relates to an air handling unit (AHU) for a heating, ventilation and air conditioning (HVAC) system. More specifically, the present invention relates to an air handling unit that uses carbon dioxide as a refrigerant and has integrated cooling / heating functions, particularly applicable to HVAC systems in buildings and vehicles. Background Art

[0002] Prior invention WO2018199835A1 discloses an air handling system with a partial indirect heat pump and a method for reducing the drop in supply air temperature in defrost mode. The prior invention provides a cooling system for recyclable cold air for buildings.

[0003] Propane and butyl refrigerants are highly flammable. Therefore, the use of carbon dioxide, also known as R744, is a safer option.

[0004] Compared to HFC and HFO refrigerants, carbon dioxide, also known as R744, offers greater environmental advantages for AHU and HVAC systems. An HVAC system may include one or more AHU modules, each including one or more carbon dioxide refrigerant loops for circulating carbon dioxide for cooling and heating purposes. Similar to outdoor-installed air conditioning systems, an AHU or HVAC system may include one or more heat exchangers / air coolers located outside the building to be cooled.

[0005] It has been found that HVAC systems and air handling units (AHUs) using carbon dioxide perform poorly and face challenges in hot environments, especially during hot summers. Using carbon dioxide as a refrigerant makes the control of the cooling process more sensitive than with previously less sustainable refrigerants.Systems using carbon dioxide have more demanding requirements compared to systems using HFC, HFO, butane, or propane as refrigerants because their air cooler coils require lower maximum temperatures to achieve optimal cooling operation.

[0006] Therefore, there is a need to provide a better method and configuration for carbon dioxide-based air handling units suitable for buildings in hot environments. Summary of the Invention

[0007] In order to improve the efficiency of air handling units (AHUs) using carbon dioxide (R744) refrigerant circuits, which are integrated cooling and heating modules with or without (700) carbon dioxide pressure optimization (750), the inventors recognized that using outdoor airflow to cool the air cooler of the heating module reduces the likelihood of obtaining optimal transcritical and subcritical carbon dioxide refrigeration processes, especially when outdoor temperatures are high, or when the outdoor air inlets leading to the air cooler coils are placed outdoors. Temperature fluctuations and high temperatures of outdoor air, as well as solar radiation and microclimates, make the control process challenging and difficult to achieve optimal cooling.

[0008] The inventors recognized the need for better and more stable cooling airflow temperature control. Experiments and studies have shown that in warm or sunny weather, the indoor temperature of most air-conditioned buildings and rooms rarely reaches the same high temperature as the outdoor air received by the AHU.

[0009] Therefore, an AHU configuration can be optimized in which AHU50, 100, 150...650 are commissioned and put into operation as a complete HVAC system 20 in building 900; the indoor exhaust airflow is used as the air intake of the air cooler, which is the coil 703 on page 1 / 27 of the first specification 6 CN 122029386 A. The first coil 703 belongs to an integrated cooling and heating module, which is an integrated cooling and heating module without carbon dioxide 700 or an integrated cooling and heating module with carbon dioxide pressure optimization 750.

[0010] When the AHU is installed in the building 900 or at least partially installed on the exterior 900', the first coil 703 is adjusted / installed in the airflow / channel passing through the interior of the building or room to receive room temperature air, which enters the exhaust airflow 23 in the exhaust duct 23, flows through the exhaust temperature sensor 803 (if present), and then through the heat exchange functional components 102, 302, 502; finally through the first coil 703, which acts as an air cooler; thereby further exchanging heat with the second coil 702, which is configured to cool the supply air 22 entering the building 900 or room.

[0011] In the system configurations mentioned for AHU50, 200, 250, 400, 450, 600, 650, HVAC system 20, and building 900, the AHU may be further equipped with functions to control the efficiency of heat exchange functional components 102, 302, and 502 to further control and regulate the air temperature at the first coil inlet air temperature sensor T801. Furthermore, an optimization method for maintaining the optimal first coil inlet air temperature at sensor T801 is provided. This method may be implemented in the form of electronic devices, hardware, mechanical components, and / or ECU software.

[0012] The present invention includes an air handling unit (AHU), an HVAC system comprising the AHU, and an electronic control unit (ECU) 800 with methods for controlling and optimizing the operation of the AHU. AHU50 may be provided according to three embodiments, or as a variation of the first embodiment: AHU100, 150, 200, 250 with cross-flow / counter-flow plate heat exchangers (PHE); AHU300, 350, 400, 450 with rotary heat exchangers (RHE); and AHU500, 550, 600, 650 with coiled tube heat exchanger (RAC) heat exchange functionality.

[0013] According to FIG8, a preferred embodiment is a rotary heat exchanger (RHE) AHU (450) with a pressure-optimized cooling system, which is expected to be very efficient. The optimization of the cooling system can be applied to AHUs with all heat recovery functions located between the first coil 703 and the second coil 702, namely 200, 250, 400, 450, 600, 650. These alternatives optimize the carbon dioxide (R744) refrigerant loop by using controlled cooling recovery from airflow from inside the building or room.

[0014] The AHU may include an ECU 800 or a similar control system for sensor, control logic functions and actuator control, implemented as electronic ECU hardware (ECUHW) 810 or as ECU software (ECUSW) 811, and optionally equipped with a system configuration file (812) or interface for setting the optimal target range (802) of sensor T, the first coil inlet temperature sensor T (801) and the exhaust room / building temperature sensor (803).

[0015] The AHU also includes the ECU 800; heat exchange functional components; a first coil (703) air cooler placed in the exhaust duct to receive air from the building; a carbon dioxide (R744) refrigerant circuit; an integrated cooling and heating module with or without carbon dioxide pressure optimization (750); the module for heat exchange with the first coil (703) air cooler; and a second coil (702) placed in the air supply duct of the AHU leading to the building (900).After placing the first coil (703) in the heat exchange function component in the exhaust airflow / channel (23), the ECU (800) is able to control / regulate the air temperature at the first coil by adjusting the heat exchange efficiency, said adjustment being achieved by adjusting the bypass vent valve of the bypass channel for the cross-flow / counter-flow plate heat exchanger, adjusting the rotational speed of the rotary heat exchanger, and / or adjusting the liquid flow rate in the coiled tube heat exchanger (RAC), thereby maximizing the carbon dioxide refrigerant cycle efficiency.

[0016] The present invention relates to heating, ventilation and air conditioning (HVAC) systems. More specifically, the present invention relates to HVAC systems that utilize carbon dioxide as a refrigerant in integrated cooling / heating air handling unit (AHU) modules 50; 100, 150, ... 650.

[0017] The HVAC system includes one or more AHU modules, each module including one or more carbon dioxide refrigerant loops for circulating carbon dioxide for cooling and heating purposes. The system also includes one or more heat exchangers / air coolers placed in the exhaust airflow of the AHU for heat exchange, thereby maximizing cycle efficiency.

[0018] The carbon dioxide refrigerant loop can operate with a simple loop design, i.e., using carbon dioxide as the refrigerant and including the main components (see page 2 / 27 of the specification, CN 122029386 A); or with an advanced loop design, i.e., using carbon dioxide as the refrigerant and including the main components and pressure optimization.

[0019] The HVAC system may also include a heat recovery system, such as a rotary heat exchanger (RHE), a cross-flow / counterflow plate heat exchanger (PHE), or a coiled tube heat exchanger (RAC), which is controlled by an electronic control unit (ECU) to maintain the air temperature before the air cooler between 15 degrees Celsius and 40 degrees Celsius. The system may also use a transcritical or subcritical carbon dioxide refrigeration process, referred to herein as CO2 or R744, where the refrigerant loop utilizes exhaust air from the building or room at the air cooler inlet.

[0020] The HVAC system may also include temperature sensors T801, 803 for measuring the air temperature entering the air cooler, i.e., before the first coil 703, and for measuring the temperature in the exhaust airflow 23 located within an exhaust duct configured to receive room temperature air from the building or room.

[0021] The ECU may be configured to control its PHE, RHE, or RAC heat exchange efficiency because maximizing the utilization of the heat exchange functional components is more energy-efficient than using a carbon dioxide (R744) refrigerant circuit without (700) or with an integrated cooling and heating module with carbon dioxide pressure optimization (750).However, if maximum heat exchange is used in a PHE, RHE, or RAC, there is a risk that the air temperature at the first coil 703, indicated by the first coil inlet air temperature of sensor T801, may reach a suboptimal temperature for the carbon dioxide refrigeration process.

[0022] Therefore, an optimization method is needed that maintains the first coil inlet air temperature at sensor T801 within the desired optimal temperature target range 802 of sensor T while controlling heat exchange efficiency by adjusting at least one of the following: a bypass valve for any cross-flow / counter-flow plate heat exchanger (PHE); the rotational speed of any rotary heat exchanger (RHE); or the liquid flow rate in any coiled heat exchanger (RAC).

[0023] Since ECU800 can control one AHU (50, 100, 150, ... 650), it can also control and optimize multiple AHUs located in different buildings, even via the Internet as a cloud service and / or with the aid of central control software for monitoring, control, and optimization. Therefore, a single ECU can serve multiple AHUs, buildings with HVAC systems, and other HVAC systems, not limited to devices in buildings and vehicles. The ECU can perform its functions in a cloud computing environment, or in local ECU hardware, or implemented in a circuit design.

[0024] An HVAC20 system and its AHU may include a heat exchanger / evaporator in cooling mode located in an air supply duct that supplies air to the interior of a building or room. The air supply duct supplies air to the interior of a building or room. The HVAC system may also include an expansion valve for controlling the evaporator suction superheat. The HVAC system may also include expansion valves for pressure optimization in the air cooler / condenser and pressure optimization in the flash receiver.

[0025] To maintain efficient cooling and heat transfer processes when using carbon dioxide, control of pressure, temperature, and fluid flow rate is crucial. This invention provides a technical solution for HVAC / AHU applications that uses carbon dioxide R744 refrigerant to maintain or optimize the cooling process. During the cooling season, by configuring the AHU to utilize the exhaust airflow, i.e., the exhaust duct, to air-cool the first coil 703, the system can achieve higher efficiency during the cooling season, which is typically hot weather. During cold weather, this function will operate normally, achieving maximum heat recovery through the heat exchange processes of PHE, RHE, and RAC.

[0026] In the cold winter, a conventionally configured AHU is used, in which the carbon dioxide (R744) refrigerant circuit, i.e., the integrated cooling and heating module without (700) or with CO2 pressure optimization (750), is configured to reverse the heat transfer process; that is, the first coil 703 and the second coil 702 operate in opposite modes, transferring heat from the first coil to the second coil to heat the supply air entering the building or room.

[0027] During the hot summer months, the inventors recognized that placing the air cooler / condenser in the exhaust duct of the HVAC system and AHU can maintain the temperature range required for the optimal carbon dioxide cooling system. This configuration is particularly preferred in hot climate zones, at midday, and during the peak of summer, because indoor temperatures are much lower than outdoor temperatures in hot environments, summer, and on sunny days. The new AHU configuration makes it possible to control the conditions required for optimal carbon dioxide-based HVAC cooling in buildings, while also saving energy.

[0028] Technical Problem The main technical problem solved by this invention is how to provide a sustainable, carbon dioxide-based optimized HVAC system with efficient cooling in hot environments. This is a challenge because the carbon dioxide refrigeration process may operate in transcritical mode, while previous technologies using less environmentally friendly greenhouse gases operate in subcritical mode. Compared to earlier, less sustainable refrigerants, high-pressure carbon dioxide refrigeration processes are considered to be more sensitive to high temperatures on the air cooler side.

[0029] Since the heat exchangers included in AHU and corresponding HVAC systems provide a more energy-efficient way to transfer and recover heat and cold in heat exchange functional components such as PHE, RHE, and RAC systems, energy-saving systems should maximize the use of this heat exchange capacity. However, this heat exchange may interfere with integrated cooling and heating modules without 700 or with CO2 pressure optimization 750, because efficient PHE, RHE, or RAC heat exchange may cause the first coil 703 to reach a non-optimal high temperature range, thereby preheating the airflow at the inlet of the first coil 703, which is intended to be used as an air cooler.

[0030] Driven by environmental and sustainability regulations, harmful refrigerants such as HFC and HFO must be rapidly phased out in favor of natural refrigerants such as CO2. However, CO2 refrigerants require significantly higher pressures and have more stringent control requirements for the cooling process, especially when using transcritical processes.

[0031] The solution to the technical problem is a known prior art HVAC system that uses a reversible heat pump to maximize energy recovery and simultaneously provide heating and cooling by efficiently transferring energy between supply and exhaust airflows. Such devices primarily use HFC or HFO mixtures as refrigerants / heat transfer media. From an environmental perspective, HFC / HFO refrigerants need to be replaced due to their high temperature effect potential (GWP) and the long lifespan and unknown risks of the chemicals they release into the atmosphere. Therefore, carbon dioxide (R744) has been identified as a preferred alternative.

[0032] Other types of refrigerants, such as A2L (weakly flammable) and A3 (highly flammable) refrigerants, have been found unsuitable.For these refrigerants, fire prevention has always been a challenge, as described in prior art patent application WO2018199835A1.

[0033] The technical problem caused by the use of carbon dioxide is that R744 refrigerant operates at higher pressures and enters transcritical mode. This can lead to reduced energy efficiency in the cooling process, which is sensitive to the high temperature air at the inlet of the air cooler. In prior art air conditioning systems, the air cooler is placed outdoors and is directly affected by the outdoor air temperature. Therefore, such systems typically operate in transcritical mode, resulting in decreased efficiency and control stability.

[0034] The inventors recognized that, in order to achieve an efficient cooling process, the inlet temperature of the air cooler in the exhaust airflow channel should be maintained between 15°C and 40°C, preferably between 20°C and 32°C.

[0035] A more efficient technical solution is needed to improve the efficiency of such HVAC systems and reduce their energy consumption, especially in hot summers, warm climates, and high-temperature seasons.

[0036] The inventors solved this technical challenge by placing the air cooler in the indoor air exhaust channel. In summer and sunny weather, indoor temperatures are typically lower than outdoor temperatures, thus providing a lower and more stable temperature range in the exhaust duct.

[0037] Therefore, compared to outdoor air coolers, HVAC systems using carbon dioxide refrigeration processes are more controllable and have lower air temperatures at the air cooler inlet, resulting in higher energy efficiency.

[0038] The inventors have proposed several alternatives for combining carbon dioxide refrigerant circuits with PHE, RHE, and RAC (cross-flow / counter-flow plate heat exchangers, rotary heat exchangers, and coiled tube heat exchange systems).

[0039] The inventors have identified a preferred configuration for combining heat exchangers with carbon dioxide-based refrigeration processes by introducing a new way of configuring AHUs in HVAC systems to combine heat recovery systems with refrigerant circuits.

[0040] The inventors also recognize the need for a solution that can control the exhaust temperature to the optimal temperature for the carbon dioxide refrigeration process.This regulation can be achieved by: a) employing different heat recovery systems / heat exchangers, i.e., PHE, RHE, or RAC; b) configuring the heat exchanger in series with a carbon dioxide-based refrigeration process to maintain the air cooler at its optimal temperature, or at least within the optimal temperature range for continued operation; c) opening a bypass channel for outdoor air and supply airflow to control the air temperature at the air cooler inlet; d) for rotary heat exchangers, adjusting and optimizing their rotational speed (RPM); e) for coiled heat exchange systems used for heat recovery, the efficiency of the heat recovery process can be controlled using: i. a variable frequency drive mounted on the pump and / or (if any) fan; ii. a circuit for controlling the speed of the motor driving the pump or (if any) fan; iii. an actuable damper or adjustable bypass duct for adjusting the airflow bypassing the RAC coil.

[0041] The aforementioned regulation techniques enable the air temperature at the air cooler inlet to be controlled and optimized within a preferred range.

[0042] Beneficial Effects of the Invention The present invention provides an air handling unit with or without an ECU 50, embodiments of which include PHE, RHE, and RAC; and an HVAC system 20. The HVAC system 20 employs an environmentally friendly carbon dioxide (R744)-based solution and has optimized features for cooling the building’s indoor climate using exhaust air from the building at the air cooler inlet. Thus, stable and favorable operating conditions are achieved even when outdoor climate and solar radiation vary over a day, an hour, or longer, especially during hot summers when outdoor air temperatures are so high that outdoor air coolers cannot function properly.

[0043] The efficiency with which the first coil 703, which serves as a condenser (subcritical) or air cooler (transcritical), dissipates heat to the airflow depends on the exhaust air temperature entering the first coil, i.e., the exhaust-side reversible heat exchanger 703, as sensed by the first coil inlet temperature sensor T801. Compared to conventional cooling systems using HFC / HFO refrigerants, the set temperature range 802 of the high-pressure carbon dioxide condenser (subcritical) or gas cooler (transcritical) is much more sensitive. Therefore, using the exhaust airflow 23 to cool the first coil, i.e., the exhaust-side reversible heat exchanger 703, and adjusting the heat exchange characteristics of PHE102, RHE302, and RAC502, can ensure temperature stability, thereby improving the stability, accuracy, energy efficiency, and cooling performance of the cooling process.

[0044] Another advantage of the present invention is that the same ECU 800 control function does not need to be implemented as a single hardware ECU 810, computing unit, PID regulator, or even convolutional neural network (CNN) or field programmable gate array (FPGA), but can also be configured as a hardware-connected technical solution, thereby eliminating the need for ECU hardware 810.

[0045] Since the ECU 800 is configured to receive an optional system profile 812, which defines and represents configuration data of different mechanical and electrical embodiments represented by heat exchanger mechanisms, namely PHE, RHE and RAC; the first aspect of the configuration is equipped with: a) an integrated cooling and heating module with carbon dioxide 700, or b) an advanced integrated cooling and heating module with carbon dioxide pressure optimization 750.

[0046] The second aspect of the configuration relates to the position of the first coil inlet temperature sensor T801 relative to the exhaust airflow 23 and the heat exchange functional components (PHE, RHE, or RAC), the sensor T801 sensing the temperature of the exhaust airflow 23 and co-located with the first coil 703, i.e., the exhaust-side reversible heat exchanger on page 5 / 27 of the specification, CN 122029386 A: c) the AHU is configured to connect the exhaust airflow 23 channel, the first coil inlet temperature sensor T801 and the first coil 703, and then connect the heat exchange functional components PHE100, 150; RHE300, 350; or RAC500, 550; or d) the AHU is configured to connect the exhaust airflow 23 channel, the heat exchange functional components PHE200, 250; RHE400, 450; or RAC600, 650, and then connect the first coil inlet temperature sensor T801 and the first coil 703.

[0047] This configuration enables optimization of the temperature of the exhaust airflow 23 passing through the efficiency-controlled heat exchange functional components, and heating or cooling of the airflow to maintain the preferred or set optimal target range of the sensor T. The efficiency control of the heat exchange functional components can be adjusted by: using a bypass valve and bypass channel for PHE200, 250; using speed control (RPM) for RHE400, 450; and using fluid flow control for RAC600, 650.

[0048] A third aspect of the invention is: if a separate exhaust room / building temperature sensor 803 is present and used in the configuration, typically, this configuration is AHU200, 250, 400, 450, 600, 650, which can be optimized using an adjustable heat exchanger as described above. When both the exhaust room / building temperature sensor 803 and the first coil inlet temperature sensor T801 are present, the ECU and corresponding methods determine the temperature difference obtained during the process of adjusting the efficiency of the heat exchange functional components. This temperature difference is used for system optimization and for temperature control of the air flowing to the first coil inlet temperature sensor T801 before the air reaches the first coil 703.

[0049] In a fourth aspect, the optimal target range 802 of the sensor T is set in the configuration.If the optimal target range 802 setting of sensor T is available, it can cover the set air temperature range at the first coil 703 previously sensed by the first coil inlet temperature sensor T801.

[0050] The fifth aspect is whether the learning function module 805 should be activated. When the learning function is activated through method step S4000, it (typically ECU 800) will use collected historical sensor data and actuator outputs to determine and optimize an improved regulation control loop in step S2000.

[0051] Optimization can be achieved using extended Kalman filtering (EKF), Kalman filtering, control equations, lookup tables, PID regulator adjustments, or even convolutional neural networks (CNN).

[0052] A typical learning situation occurs when the previous regulation of the efficiency of the heat exchange function components of PHF, RHE, or RAC fails to maintain the set temperature range at the first coil inlet temperature sensor T801. In this case, the learning function module 805 can adjust the control algorithm or mechanism to avoid similar failures in the future. Similarly, optimization can also be performed to achieve optimal energy efficiency.

[0053] As shown in FIG17, since the system configuration file 812 provides configuration data, the same ECU can be used to control all embodiments of the "air handling unit with or without ECU 50" and all aspects of the present invention. The system configuration file can define how the AHU with PHE is regulated as embodiments 100, 150, 200, 250; wherein the first aspect defines the position of the first coil 703 with temperature sensor 801 relative to the heat exchange functional components and the exhaust airflow 23 channel. The second aspect relates to the use of: an integrated cooling and heating module with carbon dioxide 700, or an advanced integrated cooling and heating module with carbon dioxide pressure optimization 750.

[0054] Furthermore, changes in the hardware and configuration of the AHU may require fine-tuning of the decision function module, and may also require fine-tuning when adjusting the heat exchanger control parameters to adapt to the actual mechanical configuration and the efficiency of the circulating fluid in the RAC.

[0055] As previously stated, excessively high air cooler temperatures may interfere with the integrated cooling and heating module with carbon dioxide 700, or the advanced integrated cooling and heating module with carbon dioxide pressure optimization 750. Specification 6 / 27 pages 11 CN 122029386 A Brief Description of the Drawings

[0056] The present invention is described with the aid of examples in the accompanying drawings, as follows.

[0057] Air Handling Unit (AHU) with Crossflow / Counterflow Plate Heat Exchanger (PHE) Figure 1: Shows an air handling unit (AHU) 100 controlled by ECU 800, which has a temperature sensor 801.The mechanical part 101 of the air handling unit (AHU) is designed to receive exhaust air 23, which is then sent to the first coil, i.e., the exhaust-side reversible heat exchanger 703, via the first coil inlet temperature sensor T801. The first coil 703 is an integrated cooling and heating module with carbon dioxide 700, and then to the cross-flow / counterflow plate heat exchanger PHE102.

[0058] Figure 2 shows an air handling unit (AHU) 150 controlled by ECU 800, which has a temperature sensor 801. The air handling unit (AHU) 151 is designed to receive exhaust air 23, which is then sent to the first coil, i.e., the exhaust-side reversible heat exchanger 703, via the first coil inlet temperature sensor T801. The first coil 703 is an advanced integrated cooling and heating module with carbon dioxide pressure optimization 750, and then to the cross-flow / counterflow plate heat exchanger PHE102.

[0059] Figure 3: Shows an air handling unit (AHU) 200 controlled by ECU 800, which has a temperature sensor 801. The air handling unit (AHU) 201 is designed to receive exhaust air 23 to the exhaust room / building temperature sensor Ti 803, further to the cross-flow / counterflow plate heat exchanger PHE 102, then to the first coil inlet temperature sensor T 801, and then to the first coil, i.e., the exhaust-side reversible heat exchanger 703, which is part of an integrated cooling and heating module with carbon dioxide 700.

[0060] Figure 4: Shows an air handling unit (AHU) 250 controlled by ECU 800, which has a temperature sensor 801. The air handling unit (AHU) 251 is designed to receive exhaust air 23 to the exhaust room / building temperature sensor Ti803, further to the cross-flow / counter-flow plate heat exchanger PHE102, then to the first coil inlet temperature sensor T801, and then to the first coil, i.e., the exhaust-side reversible heat exchanger 703, which belongs to an advanced integrated cooling and heating module with carbon dioxide pressure optimization 750.

[0061] HVAC and AHU with Rotary Heat Exchanger (RHE) Figure 5: shows an air handling unit (AHU) 300 controlled by ECU 800 with temperature sensor 801. The air handling unit (AHU) 301 is designed to receive exhaust air 23, which is then sent to the first coil, i.e., the exhaust-side reversible heat exchanger 703, via the first coil inlet temperature sensor T801, which is an integrated cooling and heating module with carbon dioxide 700, and then to the rotary heat exchanger (RHE) 302.

[0062] Figure 6 shows an air handling unit (AHU) 350 controlled by ECU 800, which has a temperature sensor 801.The air handling unit (AHU) 351 is designed to receive exhaust air 23, which is then sent to the first coil, i.e., the exhaust-side reversible heat exchanger 703, via the first coil inlet temperature sensor T801, which is part of an advanced integrated cooling and heating module with carbon dioxide pressure optimization 750, and then to the rotary heat exchanger (RHE) 302.

[0063] Figure 7 shows an air handling unit (AHU) 400 controlled by an ECU 800, which has a temperature sensor 801, and its air handling unit (AHU) 401 is designed to receive exhaust air 23 to the exhaust room / building temperature sensor Ti803, further to the rotary heat exchanger (RHE) 302, then to the first coil inlet temperature sensor T801, and then to the first coil, i.e., the exhaust-side reversible heat exchanger 703, which is part of an integrated cooling and heating module with carbon dioxide 700.

[0064] Figure 8: shows an air handling unit (AHU) 450 controlled by ECU 800, which has a temperature sensor 801, and the air handling system (AHU) 451 is designed to receive exhaust air 23 to exhaust room / building temperature sensor Ti 803, further to rotary heat exchanger (RHE) 302, then to first coil inlet temperature sensor T 801, and then to the first coil, i.e., exhaust side reversible heat exchanger 703, which belongs to the advanced integrated cooling and heating module with carbon dioxide pressure optimization 750, page 7 / 27 of specification 12 CN 122029386 A.

[0065] HVAC and AHU with Revolved Tube Heat Exchanger (RAC) Heat Exchange Function Figure 9: shows an air handling unit (AHU) 500 controlled by ECU 800, which has a temperature sensor 801. The air handling unit (AHU) 501 is designed to receive exhaust air 23, which is sent to the first coil, i.e., the exhaust-side reversible heat exchanger 703, via the first coil inlet temperature sensor T801, which is part of an integrated cooling and heating module with carbon dioxide 700, and then sent to the revolved tube heat exchanger (RAC) 502.

[0066] Figure 10 shows an air handling unit (AHU) 550 controlled by ECU 800, which has a temperature sensor 801. The air handling system (AHU) 551 is designed to receive exhaust air 23, which is sent to the first coil, i.e., the exhaust-side reversible heat exchanger 703, via the first coil inlet temperature sensor T801, which belongs to an advanced integrated cooling and heating module with carbon dioxide pressure optimization 750, and then sent to the coiled tube heat exchanger system (RAC) 502.

[0067] Figure 11 shows an air handling unit (AHU) 600 controlled by ECU 800, which has a temperature sensor 801, and its air handling system (AHU) 601 is designed to receive exhaust air 23 to exhaust room / building temperature sensor Ti 803, further to a coiled heat exchange system (RAC) 502, then to the first coil inlet temperature sensor T 801, and then to the first coil, i.e., the exhaust side reversible heat exchanger 703, which is an integrated cooling and heating module with carbon dioxide 700.

[0068] Figure 12: Shows an air handling unit (AHU) 650 controlled by ECU 800, which has a temperature sensor 801, and its air handling system (AHU) 651 is designed to: receive exhaust air 23 to exhaust room / building temperature sensor Ti 803, further to a coiled heat exchanger system (RAC) 502, then to a first coil inlet temperature sensor T 801, and then to the first coil, i.e., exhaust-side reversible heat exchanger 703, which belongs to an advanced integrated cooling and heating module with carbon dioxide pressure optimization 750.

[0069] Heating and cooling module with carbon dioxide Figure 13a: Shows an integrated cooling and heating module with carbon dioxide 700.

[0070] Figure 13b: Shows an advanced integrated cooling and heating module with carbon dioxide pressure optimization 750.

[0071] Building with HVAC system including air handling unit Figure 14a: Shows a building 900 with an air handling unit installed inside.

[0072] Figure 14b: Shows an air handling unit at least partially installed on the exterior 900' of a building.

[0073] Electronic Control Unit (ECU) and Method for AHU Control: Figure 15: Shows the components of an electronic control unit (ECU) 800 that performs the required exhaust airflow temperature regulation optimization, calculates the regulation requirements for plate heat exchanger, rotary heat exchanger, or RAC performance using a decision function module 804, and uses the calculation results as a heat exchange efficiency control signal 806.

[0074] Figure 16: Shows the steps of a method for optimizing exhaust airflow temperature regulation.

[0075] System Hierarchy and AHU Embodiment with AHU Configuration Figure 17: Shows the hierarchy of systems and subsystems, starting with a building 900 with an HVAC system, which includes at least one HVAC system 20. The HVAC system 20 includes at least one air handling unit (AHU) 50 with or without any ECU 800.Detailed Description

[0076] System hierarchy Figure 17 visualizes the system hierarchy, which includes: - A building with an HVAC system; - An HVAC system including an AHU; - An air handling unit (AHU) including a carbon dioxide refrigerant circuit and an ECU; and - A carbon dioxide refrigerant circuit, and - An electronic control unit (ECU) configured to control one or more AHUs.

[0077] As previously described, Figure 17 shows the hierarchy of systems and subsystems, starting with a building 900 with an HVAC system, which includes at least one HVAC system 20. The HVAC system 20 includes at least one air handling unit (AHU) 50 with or without any ECU 800. The AHUs are divided into three different embodiments based on their heat exchange functional components: PHE100, 150, 200, 250; RHE300, 350, 400, 450; and RAC500, 550, 600, 650.

[0078] A first aspect of the AHU relates to the selection of a configuration that defines how the exhaust airflow 23 and its passages flow and connect the first coil 703 and the heat exchange functional components. According to the first aspect, the first coil 703 may be placed between the exhaust airflow 23 and the heat exchange functional components, such as PHE in 100 and 150, RHE in 300 and 350, or RAC in 500 and 550. Alternatively, the heat exchange functional components may be placed between the exhaust airflow 23 and its passages and the first coil 703, such as PHE in 200 and 250, RHE in 400 and 450, or RAC in 600 and 650.

[0079] The latter typically utilizes the ECU to optimize the heat recovery function in PHE 200, 250 by opening, closing, and regulating the bypass passage, or regulating the speed of RHE 400, 450, or regulating the fluid circulation of RAC 600, 650.

[0080] According to a second aspect, the AHU is provided with an integrated cooling and heating module with carbon dioxide 700, or with an advanced integrated cooling and heating module with carbon dioxide pressure optimization 750.

[0081] In the three AHU embodiments distinguished by the type of heat exchange functional components, all HVAC systems use exhaust airflow 23 to cool the first coil, i.e., the exhaust-side reversible heat exchanger 703, regardless of whether the airflow passes before or after the heat exchanger mechanism PHE, RHE, and RAC. The HVAC system ECU 800 is equipped with at least an exhaust temperature sensor T801 and optionally an exhaust room / building temperature sensor Ti803, as well as an input or definition for a set temperature range 802, if provided. The ECU 800 controls the efficiency of the heat exchanger mechanism to ensure that the temperature at the exhaust temperature sensor T801 reaches the set temperature range 802, thereby optimizing the efficiency of the carbon dioxide refrigeration circuit in use.The heat exchange efficiency control signal 806 can be implemented without an ECU, but some control logic is still required. This control logic can be implemented electrically, mechanically, and / or hydromechanically to induce optimized control of the actuator.

[0082] As shown in Figure 17, 12 different HVAC system configurations can be summarized into the following variations and embodiments: PHE 100, 150, 200, 250; RHE 300, 350, 400, 450; RAC 500, 550, 600, 650.

[0083] In another aspect, each of the above-described AHU embodiments PHE, RHE, and RAC is provided with the following two main alternative mechanical configurations: a) exhaust air 23 first flows through exhaust air temperature sensor T801, then through first coil 703, and then through heat exchange functional components 102, 302, and 502; b) exhaust air 23 first flows through heat exchange functional components 102, 302, and 502, then through first coil 703, which is equipped with exhaust air temperature sensor T801.

[0084] In another aspect, each of the above-described AHU embodiments PHE, RHE, and RAC may further be equipped with: x) an integrated cooling and heating module with carbon dioxide (reference numeral 700), or y) an advanced integrated cooling and heating module with carbon dioxide pressure optimization (reference numeral 750). Specification 9 / 27 pages 14 CN 122029386 A

[0085] Figure 17 presents a table of all three air handling unit embodiments: PHE, RHE, and RAC; wherein reference numeral 51 indicates various aspects of the invention.

[0086] Certain aspects of the invention are visualized, such as: i) the location selection of the first coil 703 relative to the heat exchange functional components and the exhaust airflow passage 23; ii) the selection of the carbon dioxide refrigeration circuit, for example, with or without pressure optimization.

[0087]

[0088] AHU with cross-flow / counter-flow plate heat exchanger (PHE) Figure 1 shows an air handling unit (AHU) 50, more specifically AHU 100, which can be used as an element in HVAC system 20. The air handling unit includes an integrated cooling / heating air handling unit (AHU) (101). Each AHU includes a carbon dioxide (R744) refrigerant circuit 700 for circulating carbon dioxide (R744) for cooling and heating purposes, and each AHU has a heat exchanger / air cooler, namely a first coil 703 and a second coil 702. ECU 800 defines the control functions and logic of an optimization method to ensure that the exhaust temperature sensor T801 is within the optimal temperature range at the air inlet of the first coil 703 of the carbon dioxide (R744) refrigerant circuit 700. As shown in Figures 14a and 14b, the HVAC system 20 is typically located inside building 900, or at least partially outside building 900'.

[0089] An air handling unit (50; 100, 150, 200, 250; 300, 350, 400, 450; 500, 550, 600, 650) can be described as including a mechanical design comprising: an outdoor airflow passage 21; an air supply passage 22; an exhaust passage 23; an exhaust passage 24; and a heat exchange functional component 52 of the type of: a cross-flow / counter-flow plate heat exchanger PHE102, a rotary heat exchanger RHE302, or a coiled tube heat exchange system RAC502; a carbon dioxide (R744) refrigerant circuit 760, without 700 or with pressure optimization 750.

[0090] The carbon dioxide (R744) refrigerant circuit includes: a first coil 703, which is placed between the exhaust duct 23 and the exhaust duct 24; and a second coil 702, which is placed between the second side of the heat exchange functional component 52 and the supply air duct 22.

[0091] The carbon dioxide (R744) refrigerant circuits 760, 700, and 750 are configured for heat transfer between the first coil 703 and the second coil 702 and can operate in both directions. For the challenging problem of cooling buildings, the second coil 702 located in the supply air duct 22 transfers heat to the first coil 703 located in the exhaust duct 23 or the downstream exhaust duct 24. Therefore, the first coil 703 is configured to exchange heat with an airflow from the exhaust duct 23, which may be air received from inside the building 900 via the exhaust airflow 23.

[0092] An air handling unit (AHU) 100 controlled by an ECU 800 includes a temperature sensor 801 and is designed to receive exhaust air 23, which is then delivered via a first coil inlet temperature sensor T801 to a first coil, i.e., an exhaust-side reversible heat exchanger 703, which is part of an integrated cooling and heating module with carbon dioxide 700, and then to a cross-flow / counterflow plate heat exchanger PHE 102.

[0093] An air handling unit (AHU) designed to receive exhaust air 23 is typically equipped with a first coil inlet temperature sensor T801, which is actually part of the ECU 800 subsystem. The first coil 703 is a reversible heat exchanger for exhaust air from the exhaust duct 23. The first coil 703 is also part of an integrated cooling and heating module with carbon dioxide 700 or a pressure-optimized version 750 thereof.

[0094] Furthermore, in Figure 1, the AHU is equipped with a cross-flow / counter-flow plate heat exchanger PHE102. The AHU is preferably provided with a first fan 112 for propelling the supply airflow 22 and a second fan 114 for propelling the exhaust airflow 23; the propulsion mechanism may have different forms, but the functions are similar.

[0095] In order to adjust the heat transfer efficiency of PHE, AHU100-250 may be provided with an actuable bypass valve 53, which can be at least partially opened to allow air to bypass PHE through a separate channel; or a cross-flow / counterflow plate heat exchanger damper control 103 may be provided, which can be used to adjust the efficiency of PHE heat exchange function.

[0096] An air handling unit (AHU) 150 controlled by ECU800, which has a temperature sensor 801, is designed to receive exhaust air 23, which is sent to the first coil, i.e., the exhaust-side reversible heat exchanger 703, via the first coil inlet temperature sensor T801, which is an advanced integrated cooling and heating module with carbon dioxide pressure optimization 750, and then sent to the cross-flow / counterflow plate heat exchanger PHE102.

[0097] The air handling unit (AHU) 200 controlled by the ECU 800 has a temperature sensor 801, and its air handling unit (AHU) 201 is designed to: receive exhaust air 23 to the exhaust room / building temperature sensor Ti 803, further send it to the cross-flow / counterflow plate heat exchanger PHE 102, then send it to the first coil inlet temperature sensor T 801, and then send it to the first coil, i.e., the exhaust side reversible heat exchanger 703, which is an integrated cooling and heating module with carbon dioxide 700.

[0098] The aforementioned AHU 200 and the following AHU 250 both include cold energy recovery, temperature optimization and control for the first coil 703, and use actuators to control the bypass valve and channel of PHE 102.

[0099] The air handling unit (AHU) 250 controlled by the ECU 800 has a temperature sensor 801 and is designed to receive exhaust air via exhaust duct 23 to exhaust room / building temperature sensor Ti803, further to cross-flow / counterflow plate heat exchanger PHE102, then to first coil inlet temperature sensor T801, and then to the first coil, i.e. exhaust side reversible heat exchanger 703, which is an advanced integrated cooling and heating module with carbon dioxide pressure optimization 750.

[0100] An air handling unit (AHU) 300 with a rotary heat exchanger (RHE) is controlled by an ECU 800. It has a temperature sensor 801 and is designed to receive exhaust air via exhaust duct 23, send it to the first coil, i.e., the exhaust-side reversible heat exchanger 703, via the first coil inlet temperature sensor T801, which is an integrated cooling and heating module with carbon dioxide 700, and then send it to the rotary heat exchanger (RHE) 302.

[0101] In order to adjust the heat transfer efficiency of AHU300-450, RHE may be equipped with a rotary heat exchanger speed control 303. AHU300-450 may also be combined with a damper actuator 53 to control the airflow through or around RHE, and further adjust the efficiency of the heat exchange function from page 11 / 27 of the specification 16 CN 122029386 A.

[0102] The air handling unit (AHU) 350 controlled by ECU800 has a temperature sensor 801 and is designed to receive exhaust air 23, which is sent to the first coil 703, i.e., the exhaust-side reversible heat exchanger, via the first coil inlet temperature sensor T801, which is an advanced integrated cooling and heating module with carbon dioxide pressure optimization 750, and then sent to the rotary heat exchanger (RHE) 302.

[0103] The air handling unit (AHU) 400 controlled by the ECU 800 has a temperature sensor 801, and the air handling unit (AHU) 401 is designed to: receive exhaust air 23 to the exhaust room / building temperature sensor Ti 803, further send it to the rotary heat exchanger (RHE) 302, then send it to the first coil inlet temperature sensor T 801, and then send it to the first coil, i.e., the exhaust side reversible heat exchanger 703, which is an integrated cooling and heating module with carbon dioxide 700.

[0104] The aforementioned AHU 400 and the following AHU 450 both include cold energy recovery, temperature optimization and control for the first coil 703, and employ adjustment of the RHE speed.

[0105] The air handling unit (AHU) 450 controlled by the ECU 800 has a temperature sensor 801 and is designed to receive exhaust air 23 to the exhaust room / building temperature sensor Ti 803, further to the rotary heat exchanger (RHE) 302, then to the first coil inlet temperature sensor T 801, and then to the first coil, i.e., the exhaust-side reversible heat exchanger 703, which is an advanced integrated cooling and heating module with carbon dioxide pressure optimization 750.

[0106] An air handling unit (AHU) 500 with a coiled heat exchanger (RAC) function is controlled by an ECU 800. It has a temperature sensor 801 and is designed to receive exhaust air 23, which is sent to the first coil 703, i.e., the exhaust-side reversible heat exchanger, via the first coil inlet temperature sensor T801. The first coil 703 is an integrated cooling and heating module with carbon dioxide 700, and then sent to the coiled heat exchanger (RAC) 502.

[0107] In order to adjust the heat transfer efficiency of the RAC heat transfer function in AHU500-650, the fluid flow control actuator 503 of the coiled heat exchange system (RAC) can adjust the efficiency of the RAC heat transfer function by changing the fluid circulation speed of its circulation pump or by using a circulation control valve. In addition, the bypass valve 53 can also be used to control the airflow bypassing or passing through the RAC coil.

[0108] The air handling unit (AHU) 550 controlled by ECU 800 has a temperature sensor 801 and is designed to receive exhaust air 23, which is sent to the first coil, i.e., the exhaust-side reversible heat exchanger 703, via the first coil inlet temperature sensor T801, which belongs to the advanced integrated cooling and heating module with carbon dioxide pressure optimization 750, and then sent to the coiled heat exchange system (RAC) 502.

[0109] An air handling unit (AHU) 600 controlled by an ECU 800 has a temperature sensor 801 and is designed to receive exhaust air 23 to an exhaust room / building temperature sensor Ti 803, further to a retractable heat exchanger (RAC) 502, then to a first coil inlet temperature sensor T 801, and then to the first coil, i.e., the exhaust-side reversible heat exchanger 703, which is an integrated cooling and heating module with carbon dioxide 700.

[0110] Both the aforementioned AHU 600 and the following AHU 650 include cold energy recovery, temperature optimization and control for the first coil 703, and employ regulation of the circulation flow rate of the RAC system 502.

[0111] An air handling unit (AHU) 650 controlled by an ECU 800 has a temperature sensor 801 and is designed to receive exhaust air 23 to an exhaust room / building temperature sensor Ti 803, further to a coiled heat exchanger (RAC) 502, then to a first coil inlet temperature sensor T 801, and then to the first coil, i.e., the exhaust-side reversible heat exchanger 703, which is an advanced integrated cooling and heating module with carbon dioxide pressure optimization 750. (Page 12 / 27, CN 122029386 A)

[0112] All air handling units (50; 100, 150, 200, 250; 300, 350, 400, 450; 500, 550, 600, 650) with new features are provided with the following features: a first coil 703 is placed in the airflow from the exhaust duct 23 to connect the interior of a building, room or similar space, thereby providing air with less fluctuation and lower temperature than outdoor air in hot weather.In some configurations, exhaust air first passes through heat exchange components, PHE, RHE, or RAC systems, then reaches the first coil 703, and then further enters the exhaust passage 24.

[0113] The heating mode (HM) is not described here, as its operation should be well known to HVAC system engineers. Similarly, the electronic control unit (ECU) described later can implement a method for switching between the cooling mode (CM) and the heating mode (HM) according to the invention.

[0114] When the AHU includes cold energy recovery and the system is in cooling mode, the optimization and control methods provided by the present invention can be used to optimize how the carbon dioxide (R744) refrigerant circuits 760, 700, 750 of the air handling unit coordinate with the adjustable heat exchange components 52. Examples of adjustable heat exchange function components 52 are as follows: - PHE102, a cross-flow / counterflow plate heat exchanger with an adjustable actuated bypass valve; - RHE302, a rotary heat exchanger with speed control; - a coiled tube heat exchange system (RAC) 502 with coolant flow control.

[0115] A typical trigger condition for entering the optimized cooling mode is that the temperature of the airflow entering the first coil 703 is higher than the optimal value, which can be detected by the exhaust duct temperature sensor 803 or the first coil inlet temperature sensor T801.

[0116] Typically, an air handling unit (AHU) 50; 100, 150, 200, 250; 300, 350, 400, 450; 500, 550, 600, 650 includes: an outdoor airflow passage 21 as an air inlet from outside the building; an air supply passage 22 for supplying airflow to the interior of the building or room; an exhaust passage 23 for exhausting used air from inside the building or room; an exhaust passage 24 for exhausting air from the AHU to the exterior of the building; and a heat exchange component 52 for heat transfer between the airflow entering the building via passages 21, 22 and the airflow exiting the building via passages 23, 34.

[0117] Air handling units (AHUs) are typically equipped with fans to propel airflow from the outside through passages 21, 22 into the room, and with another fan or similar mechanism to propel airflow from the room through passages 23, 24 to the outside, and with heat exchange components 52. Since an AHU can also be propelled by an external airflow generating mechanism, it may not need to include its own fan or fan system. Nevertheless, air handling units (AHUs) 50; 100, 150, 200, 250; 300, 350, 400, 450; 500, 550, 600, 650 may be equipped with fans or multiple fans to propel air through their airflow passages 21, 22, 23, 24. Similarly, motors for the circulation pump, actuators, and drive motors for any RHE are considered to be provided if necessary.

[0118] The heat exchange functional component 52 includes at least one of the following: a cross-flow / counter-flow plate heat exchanger PHE102, a rotary heat exchanger RHE302, or a coiled tube heat exchange system RAC502; the above configurations can be considered as different embodiments, namely PHE, RHE, and RAC.

[0119] Therefore, the heat exchange functional component 52 provides a low-energy heat transfer mechanism. Instruction manual 13 / 27 pages 18 CN 122029386 A

[0120] AHU also provides a carbon dioxide (R744) refrigerant circuit 760, 700, 750, which includes: a first coil 703 placed between an exhaust duct 23 and an exhaust duct 24; a second coil 702 placed between a heat exchange functional component 52 and an air supply duct 22; and a first coil inlet temperature sensor T801; wherein the carbon dioxide (R744) refrigerant circuit 760, 700, 750 is configured for heat transfer between the first coil 703 and the second coil 702.

[0121] The carbon dioxide (R744) refrigerant circuit consumes energy, and like a conventional carbon dioxide (R744) refrigeration system, it follows thermodynamic principles to transfer heat between its first coil 703 and second coil 702. The first coil 703 and the second coil 702 can operate in reverse mode, thereby providing heating and cooling in different system modes.

[0122] Air handling units (AHUs) 50; 100, 150, 200, 250; 300, 350, 400, 450; 500, 550, 600, 650 are specifically designed such that the first coil 703 is configured to exchange heat with an airflow originating from the exhaust duct 23, such as air received from inside the building 900; the purpose is to use indoor air as the airflow for the first coil 703. This configuration has proven superior to placing the first coil in an airflow that provides air from outside the building, and is also superior to conventional air conditioning system configurations in which the first coil 703, as an air cooler, is placed outside the building, with or without a fan, to act as a radiator.

[0123] A first aspect of the invention is that the AHU may be provided with two alternative configurations of an integrated cooling and heating module with carbon dioxide, wherein: a) the air handling units 100, 200, 300, 400, 500, 600 as defined in claim 2 may include a carbon dioxide (R744) refrigerant circuit 760, which is an integrated cooling and heating module with carbon dioxide 700; or b) the air handling units 150, 250, 350, 450, 550, 650 as defined in claim 3, wherein the carbon dioxide (R744) refrigerant circuit 760 is an advanced integrated cooling and heating module with carbon dioxide pressure optimization 750.

[0124] A second aspect of the invention is the placement of the first coil 703 relative to the heat exchange functional component 52 in the AHU. Alternatives exist: a) the air handling units 100, 150, 300, 350, 500, and 550 as claimed in claim 4, wherein the first coil 703 is placed between the exhaust duct 23 and the heat exchange functional component 52.

[0125] This can also be expressed as the air handling units 100, 150, 300, 350, 500, and 550 as defined in claim 5, which are designed to receive exhaust air via the exhaust duct 23, pass it through the first coil inlet temperature sensor T801, deliver it to the first coil 703, and then to the heat exchange functional component 52, which may be: a cross-flow / counter-flow plate heat exchanger PHE102, a rotary heat exchanger RHE302, or a coiled tube heat exchange system RAC502.

[0126] Or b) the air handling unit 200, 250, 400, 450, 600, 650 as claimed in claim 6, wherein the first coil 703 is placed between the heat exchange functional component 52 and the exhaust passage 24.

[0127] This can also be expressed as the air handling unit 200, 250, 400, 450, 600, 650 for cold energy recovery as defined in claim 7, which is designed to: receive exhaust air via exhaust passage 23, send it to exhaust room / building temperature sensor Ti803, and further send it to heat exchange functional component 52, which may be: cross-flow / counter-flow plate heat exchanger PHE102, rotary heat exchanger RHE302 or coiled tube heat exchange system RAC502; then send it to the first coil inlet temperature sensor T801; and further send it to the first coil 703. Specification page 14 / 27 19 CN 122029386 A

[0128] As previously stated, the air handling unit can be embodied in three different embodiments, which can also be considered as supported variations or configurations. For example, the ECU800 and the method according to claims 18-22 can support all types of air handling unit configurations, which have been mentioned in AHU50; 100, 150, 200, 250; 300, 350, 400, 450; 500, 550, 600, 650.

[0129] According to a first embodiment, the air handling unit 100, 150, 200, 250 as claimed in claim 8 includes a heat exchange functional component 52, which is: a cross-flow / counter-flow plate heat exchanger (PHE) 102.

[0130] The air handling units 100, 150, 200, and 250 of the embodiments of claim 11 may further include an actuable bypass valve 53, which is designed to: when open, allow at least a portion or all of the airflow to bypass the heat exchange functional component 52; and when closed, allow the airflow to pass through the heat exchange functional component, i.e., PHE 102, thereby providing adjustable heat transfer efficiency.

[0131] According to a second embodiment, the air handling units 300, 350, 400, and 450 of claim 9 include a heat exchange functional component 52, which is a rotary heat exchanger (RHE) 302. The RHE may be configured with a rotational speed (RPM) control to provide adjustable rotational speed and heat transfer efficiency.

[0132] According to a third embodiment, the air handling units (500, 550, 600, and 650) of claim 10 include a heat exchange functional component (52), which is a coiled tube heat exchange system (RAC) 502. In addition, the RAC system may be equipped with a flow regulator for its fluids, typically a valve or circulating motor control, thereby providing adjustable heat transfer efficiency.

[0133] In the configuration of the air handling unit 200; 250; 400, 450; 600, 650 as defined in claim 12, the AHU further includes: an exhaust room / building temperature sensor 803 configured to receive the value of the exhaust room / building temperature sensor 803.

[0134] The configuration enables the method and ECU to estimate the difference between the exhaust temperature and the temperature at the first coil 703, which is sensed by the first coil inlet temperature sensor 801. This information is then used by the decision function module 804 to determine adjustments to the control signal 806 to regulate the heat transfer efficiency at PHE102, RHE302, and the RAC system 502.

[0135] As previously stated, the heat transfer efficiency at the heat exchanger can be controlled or adjusted by the following devices or methods: a) an actuator for the bypass vent valve of PHE102; b) speed control for RHE302; and / or c) circulation flow control, actuable circulation valve, or circulation motor control for RAC system 502.

[0136] Electronic control unit (ECU) and method for AHU control: Figure 15 shows the components of electronic control unit (ECU) 800, which performs the required exhaust airflow temperature regulation optimization using a decision function module 804 that calculates the regulation requirements of the heat exchanger or RAC performance as a heat exchange efficiency control signal 806. The heat exchange efficiency control signal 806 controls the heat exchanger performance using one of the following devices according to the system configuration: a) an actuator for controlling the PHE bypass vent valve; b) a regulator for controlling the RHE speed; and c) a regulator for controlling the RAC liquid flow rate.

[0137] Figure 16 illustrates the steps of a method for optimizing exhaust airflow temperature regulation. First, the adjustment requirement for the AHU heat exchanger efficiency is determined in S2000 to achieve the optimal air temperature before the air cooler / condenser. Then, the heat exchanger efficiency control parameters are adjusted in S3000, for example, through the following sub-steps: a) S3100 adjusts the RHE rotation speed, b) S3200 adjusts the air valve for the bypass channel of the PHE, or c) S3300 adjusts the RAC liquid flow rate. Specification 15 / 27 pages 20 CN 122029386 A

[0138] The learning in step S4000 and the adjustment of the control loop in step S2000 based on the control history can optimize the regulation and control function of step S2000. This allows the system to adjust its control function to improve accuracy, regulation speed, robustness to deviations from the set temperature range, and to adjust and calibrate the regulation method in step S3000.

[0139] The electronic control unit (ECU) 800 is designed to control air handling units (AHUs) 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650 as defined in claims 1-12 and 17, wherein the ECU is integrated with the AHU. As a physical entity, the electronic control unit 800 includes: electronic control unit hardware (ECUHW) 810 for sensor data processing and AHU operation optimization; an interface connected to a first coil inlet temperature sensor T801, which is designed to sense the temperature at the air inlet of the first coil 703; and an interface connected to an exhaust airflow temperature sensor Ti803, which is designed to sense the temperature at the exhaust duct 23 or the temperature inside the building 900 or room 900 or alternative building / room 900'.

[0140] The ECU 800 also includes a determination function module 804, which implements regulation and control functions and is designed to: determine the heat exchange efficiency control signal 806 based at least on the input signals of the first coil inlet temperature sensor T801 and the exhaust airflow temperature sensor Ti803, wherein the presence or absence of the exhaust airflow temperature sensor Ti803 depends on the configuration of the AHU and the ECU.

[0141] The determination function module 804 is used to control and adjust the efficiency of the heat exchange function components of the AHU so that the air temperature at the first coil 703 reaches and is maintained at an optimal air temperature, which is within the optimal target range 802 of the first coil inlet temperature sensor T801.

[0142] The determination function module 804 determines the heat exchange efficiency control signal 806.The control signal 806 is then used as an input signal to adjust the efficiency of the heat exchange function component 52, which is controlled or adjusted according to the heat exchange efficiency control signal 806 to regulate the following devices: an actuator 821 for the PHE bypass channel damper, a regulator 822 for the RHE speed, or a regulator 823 for the RAC liquid flow rate.

[0143] As further claimed in claim 14, the ECU (800) also includes: a learning function module (805) for feedback adjustment of the regulation function based on the regulation history in the decision function module (804). The learning function module can optimize the control and optimization functions of the ECU to optimize the air temperature reaching the first coil 703 inside the AHU, the heat exchange efficiency signal (806) of which is adjustable and can regulate the following devices: an actuator (821) for the PHE bypass channel damper, a regulator (822) for the RHE speed, or a regulator (823) for the RAC liquid flow rate.

[0144] To optimize the operation of the first coil 703 in the AHU, the AHU needs to be configured as follows: the heat exchange function components are PHE102, RHE302 and / or 502, which separate the first coil 703 and are placed between the heat exchange function components and the exhaust channels 24 (AHU200, 250, 400, 450, 600, 650). By adjusting the efficiency of the heat exchange function, the actual temperature at the first coil inlet temperature sensor T801 can be controlled.

[0145] As shown in Figures 14a and 14b, by using the temperature sensor 803 of the indoor exhaust channel 23 and the first coil inlet temperature sensor T801, the determination function module 804 can determine the actual temperature difference on the heat exchanger and use this temperature difference as input to optimize and regulate the heat exchanger efficiency signal (806), and to regulate the regulators 821, 822 and 823.

[0146] As further described in claim 15, the ECU 800 may include: setting an optimal target range (802) for the sensor T, and / or a system profile (812) that defines at least one optimal temperature target range (802); This optimal temperature target range (802) is used to set a default value and to adjust the target temperature range at the first coil 703.

[0147] The first coil 703 is connected to the second coil 702 for heat exchange. An integrated cooling and heating module with carbon dioxide 700, or an advanced integrated cooling and heating module with carbon dioxide pressure optimization 750, transfers heat from the second coil 702 to the first coil 703 during building cooling and inversely transfers heat when heating the building and rooms.

[0148] Depending on weather conditions, readings from temperature sensors 801 and 803, the setting of temperature range 802, and other sensor data such as pressure data, as well as cloud information from weather data and weather forecasts, the behavior of the determination function module 804 can be adjusted and its performance optimized, and this adjustment process is implemented through method step S3000.

[0149] Integrated heating and cooling module with carbon dioxide Figure 13a: shows an integrated cooling and heating module with carbon dioxide 700, which is a self-contained autonomous adjustment process, typically provided by the manufacturer in an integrated form.

[0150] Figure 13b: shows an advanced integrated cooling and heating module with carbon dioxide pressure optimization 750. Carbon dioxide pressure optimization is a self-contained autonomous adjustment process, typically provided by the manufacturer in an integrated form. Due to the presence of pressure optimization, the determination method used to regulate the efficiency of the heat exchange function components may have slightly different characteristics than the variant 700 in Figure 13a without pressure optimization. If the system has a system configuration file, that file may specify that the system's ECU 800 and / or AHU 50, 100...650 should be optimized for use with an advanced integrated cooling and heating module with CO2 pressure optimization 750, or optimized for use with a more basic integrated cooling and heating module with CO2 700.

[0151] The air handling unit including the ECU is further defined as claimed in claim 17, wherein the air handling unit (AHU) 50, 100, 150, 200, 250; 300, 350, 400, 450; 500, 550, 600, 650 is an AHU integrated with an electronic control unit (ECU) 800. The AHU includes an ECU, which may be local or remote, such as Software as a Service (SaaS) as claimed in claim 16. The AHU including the ECU integrates an electronic control unit (ECU) 800 as described in claims 12 to 16, which is configured to control air handling units 50, 100, 150, 200, 250; 300, 350, 400, 450; 500, 550, 600, 650. The ECU is subsequently configured to sense temperatures 801, 803 and set a temperature range 802 to determine a control signal 806, thereby regulating and controlling the AHUs equipped with cooling recovery, namely AHUs 50, 200, 250; 400, 450; 600, 650. Specifically, this is achieved by actuating the bypass valves for AHUs 200 and 250 with PHE, regulating the rotational speed for AHUs 400 and 450 with RHE, and / or regulating the circulation flow rate for AHUs 600 and 650 with RAC. Therefore, the ECU senses the temperature, determines the control signal 806, and adjusts / controls the efficiency of the heat exchange function to maintain and ensure the optimal temperature at the first coil inlet temperature sensor T801.

[0152] Both temperature sensors 801 and 803 can be used by the determination function module 804 according to the adjustment requirements, i.e., the control signal 806.

[0153] The HVAC system integrated with the building includes an HVAC system 20 with or without an AHU 50 of ECU 800, which can be integrated with the building 900, i.e., installed inside the building or at least partially installed outside the building 900'. The air conditioning system is typically equipped with a function similar to the first coil 703, i.e., the air cooler is located outside the building. In this invention, it has been found that the preferred location of the air cooler is connected to the exhaust duct 23 of the building or room.

[0154] The HVAC system 20 according to claim 23 includes at least one air handling unit (AHU) (50; 100, 150, 200, 250; 300, 350, 400, 450; 500, 550, 600, 650) according to claims 1 to 12 or 17, wherein the exhaust duct 23 is connected to the interior of a building 900, a vehicle, a train, or a ship.

[0155] Figure 14a shows an AHU placed entirely inside the building 900, while Figure 14b shows an AHU placed at least partially outside the building 900, which is a common placement for air conditioning (AC) systems. The present invention abandons the conventional practice of using outdoor air for air coolers, i.e., the first coil 703, which is configured to be in direct communication with indoor air flowing through the exhaust duct 23.

[0156] The radiation 905 from the sun 904 and the high temperature of the outdoor air 902 pose challenges when using any cooling and heating module 760 with carbon dioxide aspects 700 and 750 for air cooling, because the first coil 703 is sensitive to the temperature required for optimal operation when cooling the building. Therefore, appropriate methods are needed for the ECU, AHU, and HVAC systems to ensure that the temperature 801 is maintained within the set temperature range 802.

[0157] In one aspect of the AHU, the cooling and heating module with carbon dioxide is: a) an integrated cooling and heating module with carbon dioxide 700; b) an advanced integrated cooling and heating module with carbon dioxide pressure optimization 750.

[0158] Figure 13a: shows an integrated cooling and heating module with carbon dioxide 700.

[0159] Figure 13b: shows an advanced integrated cooling and heating module with carbon dioxide pressure optimization 750.

[0160] Figure 14a: shows a building 900 with an internally installed air handling unit.

[0161] Figure 14b: shows building 900' with the air handling unit at least partially installed on the exterior of the building.

[0162] Figure 15 illustrates the components of an electronic control unit (ECU) 800 that uses a decision function module 804 to perform optimization of the required exhaust airflow temperature regulation. This decision function module calculates the regulation requirements for the heat exchanger or RAC performance and uses it as a heat exchange efficiency control signal 806. The heat exchange efficiency control signal 806, depending on the system configuration, controls the heat exchanger performance using one of the following devices: a) an actuator for the PHE bypass channel damper; b) a regulator for the RHE speed; and c) a regulator for the RAC liquid flow rate, which employs a speed control or flow regulation valve for the RAC circulating pump.

[0163] The ECU may be a computer with memory, electronic circuitry, adaptive electronic circuitry, a PID controller, a Kalman filter, or any other optional adaptable control function that can be placed in a feedback learning loop.

[0164] Figure 16 illustrates the steps of a method for optimizing exhaust airflow temperature regulation. First, step S2000 determines the regulation requirements of the AHU heat exchanger efficiency to achieve the optimal air temperature before the air cooler / condenser. Then, step S3000 regulates the heat exchanger efficiency control parameters, for example, through the following different sub-steps: a) S3100 adjusts the RHE speed, b) S3200 adjusts the air valve for the bypass channel of the PHE, and c) S3300 adjusts the liquid flow rate of the RAC.

[0165] With the accumulation of historical data, the learning in step S4000 and the adjustment of the control loop in step S2000 based on the regulation history will update the optimization parameters used in step S2000.

[0166] In another embodiment, step S4000 can be implemented in a cloud computing environment where statistical analysis is performed on multiple installed AHUs, and then the optimization parameters for each AHU are determined in step S2000. Such cloud services can utilize external parameters such as changes and forecasts in weather conditions. The centralized execution of step S4000 allows for coordinated or uncoordinated pre-conditioning of multiple AHU and HVAC systems. Step S4000, as a processing function of the central cloud or server, can take into account changes in weather and environment during calculation, such as dealing with conditions such as humidity, cold, high temperature, air pollution, and air pressure changes. In addition, method steps S2000, S3000 and their sub-steps S3100, S3200, S3300 and step S1100 can all be executed and processed in a server-side or cloud computing environment. Specification 18 / 27 pages 23 CN 122029386 A

[0167] When determining the adjustment requirement, step S2000 receives information about temperature sensor data T from step S1000, receives optional information about the optimal target range setting of sensor T from step S1100, and receives optional information about the exhaust temperature of the room / building from step S1200.

[0168] The improvement in the cooling method improves the control process by introducing the following features.

[0169] To maximize cycle efficiency, the heat exchanger / air cooler is placed in the exhaust airflow of the AHU. Placing the heat exchanger / air cooler outdoors can cause problems when the outdoor temperature is too high. This design has a significant advantage in efficiency compared to the past practice of placing the heat exchanger / air cooler outdoors.

[0170] As a first design step, as shown in Figure 1, the carbon dioxide cycle can be used as a simple refrigerant loop without pressure optimization.

[0171] The inventors recognized that in summer, the indoor temperature of a building is always lower than the outdoor temperature because the outdoor temperature is at least higher.

[0172] When the outdoor temperature varies from 20°C to 40°C, the exhaust air temperature from the building can vary from 15°C to 30°C.

[0173] In heating mode, the low inlet temperature on the air cooler / condenser is very beneficial to system efficiency.

[0174] An exhaust temperature sensor Ti (803) and an air temperature sensor T (801) are placed at the air cooler inlet to provide the exhaust air temperature and the air temperature at the air cooler inlet. The air temperature T (801) is then used to optimize the maximum air temperature at the air cooler inlet, making partial or complete heat recovery possible under warm and hot summer conditions via a PHE, RHE, or RAC system.

[0175] When the temperature reaches the maximum temperature setpoint, the air valve in the PHE can be controlled to maintain the air temperature entering the air cooler inlet at the optimal value to achieve high circulation efficiency.

[0176] When the temperature reaches the maximum temperature setpoint, the RHE, i.e., the rotary heat exchanger, is controlled to slow down, i.e., reduce its rotation speed, to maintain the air temperature at the air cooler inlet at the optimal value for high circulation efficiency.

[0177] When the temperature reaches the maximum temperature setpoint, in order to regulate the optimal cooling process, the liquid flow rate in the RAC system is then controlled to maintain the air temperature at the air cooler inlet at an optimal value for high cycle efficiency.

[0178] If an AHU module with an advanced carbon dioxide refrigerant loop is used in this invention, the optimization process can be controlled and regulated by additional expansion valves and flash receivers. It is generally accepted that this embodiment can provide higher loop efficiency compared to a simple carbon dioxide refrigerant loop.

[0179] System Efficiency and Circulation Optimization Method The following method describes how to optimize and improve the cooling process and indirectly improve the system efficiency of the AHU, which, when configured for use in a building, is able to acquire indoor air as cooled air discharged through exhaust duct 23.

[0180] These methods can be implemented in AHU50, 100, ... via hard-wired electronics, or preferably executed by ECU800, or possibly in the form of ECU software 811, for executing control electronics, computers, field-programmable gate arrays (FPGAs), microcontrollers, or electronic control unit hardware ECUHW810.

[0181] Furthermore, the ECU can be implemented as Software as a Service (SaaS) in a cloud server computer model or a central server computer model. Such an EXCU can be executed in a central computer or as a SaaS method, simultaneously controlling one or more AHUs from a remote location. This software execution is equivalent to local execution but provides more coordination opportunities. For example, changes in weather conditions, temperature, pressure, rain, snow, cloud cover, etc., can be used to improve the learning functions further described later in this document, and can also provide input for the improved collaborative decision function module (804).

[0182] The specific method described in further detail in claim 18 is responsible for optimizing the cooling efficiency of air handling units (AHUs) 200, 250; 400, 450; 600, 650. This first method performs the following steps (S1000 to S3300): (S1000) receiving the first coil air inlet temperature from sensor T801.

[0183] (S1100) receiving data from exhaust room / building temperature sensor Ti803.

[0184] (S2000) determining the adjustment requirements for heat exchanger efficiency control parameters to achieve and maintain optimal transcritical or subcritical refrigerant cycling, and ensuring that the first coil inlet temperature sensor T801 is tuned to an optimal temperature range 802 for temperature sensor T, which is suitable for air coolers with transcritical or subcritical carbon dioxide cycles.

[0185] (S3000) Adjusting the heat exchanger efficiency control parameters, using a heat exchange efficiency control signal (806) to regulate the performance of at least one heat exchange function, by: (S3100) adjusting the rotational speed (303) of the rotary heat exchanger (302); (S3200) adjusting the damper of the bypass channel for the cross-flow / counterflow plate heat exchanger (102); or (S3300) adjusting the liquid flow rate of the coiled heat exchange system (RAC) (502) to achieve efficient cold recovery and maximum system efficiency.

[0186] Maximum system efficiency is achieved when the first coil inlet temperature sensor T801 is maintained within the optimal temperature range 802.

[0187] The second method as further described in claim 19, with step (S1100) added before step (S2000). Step (S1100) is described below.

[0188] (S1100) An optimal target temperature range (OTTR) (802) is set for the temperature sensor T, such that step (S2000) uses this optimal target temperature range when determining the adjustment requirement for the heat exchanger efficiency.

[0189] In a third method further as claimed in claim 20, a sub-step (S1200) is specified prior to step (S2000), wherein step (S1200) includes: (S1200) receiving exhaust air temperature from room or building Ti803, such that step (S2000) uses the exhaust air temperature from room or building when determining adjustment requirement 804, which is the heat exchange efficiency control signal 806 for adjusting the heat exchanger efficiency.

[0190] In a fourth method further as defined in claim 21, an optimal temperature target range (802) of the temperature sensor T is used, which is set between 15 degrees Celsius and 40 degrees Celsius, preferably between 20 and 32 degrees Celsius. It has been found that this temperature range is optimal for cooling the first coil 703, and for the AHU50, 100, ... 650 actually used, it can optimally utilize heat exchange components such as PHE102, RHE302, or RAC502.

[0191] The fifth method as further defined in claim 22 describes how the learning step is processed to optimize the decision step. In the learning step S4000 following step S3000, the parameters used in the decision step S3000 are analyzed and optimized, for example, a more preferred range is identified for the optimal temperature target range 802 of the temperature sensor T. For example, if it is found by analyzing the input and output history of the control process that the decision function module cannot adequately maintain the first coil inlet temperature sensor T801 within the optimal temperature range, the responsiveness of the decision control function can be recalibrated and adjusted to ensure future control stability, thereby maintaining the set temperature. Those skilled in the art of control systems will be aware of various techniques used for such optimization or learning functions. More complex methods can also be used, including convolutional neural network (CNN) technology, Kalman filtering with learning parameters, and adjustable PID controllers.

[0192] Step (S4000), learning also includes: (S4000) learning, or feedback regulation control loop, to optimize the control parameters in the following step: Step (S2000) determining the adjustment requirements for heat exchanger efficiency.

[0193] List of reference numerals The reference numerals used in the figures are explained below. First, the reference numerals of the items are specified, followed by the abbreviations of the items, arrows, information flows or method steps, and a brief description is provided where necessary.

[0194] The system described herein is generally referred to as a “carbon dioxide refrigeration HVAC system,” that is, “an integrated cooling / heating air handling unit with an optimized carbon dioxide refrigerant circuit that uses return air from the building,” and its reference numeral is 20.

[0195] To avoid confusion between the figure numbers and reference numerals, numbers 1 to 19 are omitted. Method steps are numbered S1000, S2000, etc.

[0196] 20 = An HVAC system. The HVAC system is typically installed in building 900. This HVAC system is an integrated cooling / heating air handling unit that uses return air from building 900 and has a carbon dioxide refrigerant circuit. The system optimizes the cooling efficiency of its refrigeration circuit by first utilizing indoor air as the cooling medium for the refrigerant circuit. Especially in hot seasons, the temperature of indoor air rarely reaches the high temperature reached by outdoor air under solar radiation 904. HVAC system 20 also employs a control mechanism that sets a feasible temperature range for the refrigerant circuit to operate at optimal efficiency. Furthermore, HVAC system 20 can be equipped with an AHU featuring a plate heat exchanger (PHE), a rotary heat exchanger (RHE), or a coiled tube heat exchanger system (RAC), combined with a simple refrigerant circuit 700 or an advanced refrigerant circuit with pressure optimization 750. Alternatively, the refrigerant circuit can be configured such that its first coil, i.e., the exhaust-side reversible heat exchanger 703, directly receives the building's exhaust air 23, as shown in air handling units (AHUs) and system variants 100, 150, 300, 350, 500, and 550; or alternatively, the exhaust air passes through a PHE, RHE, or RAC heat exchanger before entering the first coil of the refrigerant circuit (i.e., the reversible heat exchanger 703 for exhaust air), as shown in 200, 250, 400, 450, 600, and 650.

[0197] 20' = Same as 20, but the AHU is at least partially installed outside the building at 900'.

[0198] 21 = Outdoor airflow duct, located at the AHU. "Outdoor" can also refer to the exterior of the AHU, for example, when the AHU is installed on a ship, other vessel or structure with internal and external spaces, it usually refers to outdoor air that provides fresh air to the building.

[0199] 22 = Supply air duct, used to supply air to the building or room.

[0200] 23 = Exhaust air duct, connected to a room or building, used to draw air from inside the building.

[0201] 24 = Exhaust duct, connected to the exterior of the building, used to exhaust used air.

[0202] 50 = Air handling unit, covering the following three types of embodiments and configurations: PHE type: 100, 150, 200, 250; RHE type: 300, 350, 400, 450; RAC type: 500, 550, 600, 650.

[0203] 50' = any air handling unit 50 installed inside a building, as an example of any air handling unit installation: PHE: 100, 150, 200, 250; RHE: 300, 350, 400, 450; and RAC: 500, 550, 600, 650.

[0204] 50" = Any air handling unit 50 at least partially installed outside the building, which may serve as an example of the installation of other air handling units.

[0205] 51 = A table showing all air handling unit embodiments PHE, RHE, and RAC; wherein: First aspect: The mechanical configuration of the AHU is: a) Exhaust flow first to the first coil, then to the heat exchange functional component; or, as per specification page 21 / 27, 26 CN 122029386 A b) Exhaust flow first to the heat exchange functional component, then to the first coil.

[0206] Second aspect: The type of carbon dioxide refrigeration circuit of the AHU is: c) An integrated cooling and heating module with carbon dioxide 700; d) An advanced integrated cooling and heating module with carbon dioxide pressure optimization 750.

[0207] 52 = Heat exchange functional component, for example: a cross-flow / counter-flow plate heat exchanger PHE102, a rotary heat exchanger RHE302, or a coiled tube heat exchange system RAC502.

[0208] 53 = Bypass valve. When open, air bypasses the heat exchange function component (52), typically PHE102; when closed, air passes through the heat exchange function component (52).

[0209] 100 = Air handling unit (AHU) controlled by ECU800, with a first coil inlet temperature sensor T801. The air handling unit (AHU) includes an air handling unit mechanical part 101, as detailed below. The air handling unit (AHU) 100 is designed to receive exhaust air 23 via the first coil inlet temperature sensor T801, deliver it to the first coil 703 with an integrated cooling and heating module containing carbon dioxide 700, and then to the cross-flow / counter-flow plate heat exchanger PHE102.

[0210] 101 = Air Handling Unit (AHU) mechanical part, including the following components and designed to: receive exhaust air 23, send it via a first coil inlet temperature sensor T801 to a first coil 703, which belongs to an advanced integrated cooling and heating module with carbon dioxide pressure optimization 750, and then send it to a cross-flow / counter-flow plate heat exchanger PHE 102.

[0211] 102 = Cross-flow / counter-flow plate heat exchanger (PHE) 103 = Cross-flow / counter-flow plate heat exchanger damper control, which can be used to adjust the efficiency of the PHE heat exchange function. Same as 53.

[0212] 112 = First fan, for supply airflow.

[0213] 114 = Second fan, for exhaust airflow.

[0214] 150 = Air handling unit (AHU) controlled by ECU 800, which has a first coil inlet temperature sensor T801. The air handling unit (AHU) includes air handling unit mechanical parts 151, as detailed below. The air handling unit (AHU) 150 is designed to receive exhaust air 23, which, via the first coil inlet temperature sensor T801, is delivered to a first coil 703, which belongs to an advanced integrated cooling and heating module with carbon dioxide pressure optimization 750, and then to a cross-flow / counterflow plate heat exchanger PHE 102.

[0215] 151 = Air handling unit (AHU) mechanical part, including the following components and designed to receive exhaust air 23, which is sent to the first coil 703 via the first coil inlet temperature sensor T801, the first coil 703 being an advanced integrated cooling and heating module with carbon dioxide pressure optimization 750, and then to the cross-flow / counterflow plate heat exchanger PHE102.

[0216] 200 = Air handling unit (AHU) controlled by ECU 800, with the first coil inlet temperature sensor T801. The air handling unit (AHU) includes air handling unit mechanical part 201, as detailed below. Air handling unit (AHU) 200 is designed to receive exhaust air 23 to exhaust room / building temperature sensor Ti803, then to cross-flow / counter-flow plate heat exchanger PHE102, then to first coil inlet temperature sensor T801, and then to first coil 703, which belongs to an integrated cooling and heating module with carbon dioxide 700.

[0217] 201= The mechanical part of the air handling unit (AHU) includes the following components and is designed to receive exhaust air 23 to exhaust room / building temperature sensor Ti803, then to cross-flow / counter-flow plate heat exchanger PHE102, then to first coil inlet temperature sensor T801, and then to first coil 703, which belongs to an integrated cooling and heating module with carbon dioxide 700. Instruction manual, pages 22 / 27, CN 122029386 A

[0218] 250 = Air handling unit (AHU) controlled by ECU 800, with first coil inlet temperature sensor T 801. The air handling unit (AHU) includes air handling unit mechanical part 251, as detailed below. The air handling unit (AHU) 250 is designed to: receive exhaust air 23 to exhaust room / building temperature sensor Ti 803, then to cross-flow / counterflow plate heat exchanger PHE 102, then to first coil inlet temperature sensor T 801, and then to first coil 703, which belongs to an advanced integrated cooling and heating module with carbon dioxide pressure optimization 750.

[0219] 251 = The air handling unit (AHU) mechanical part includes the following components and is designed to: receive exhaust air 23 to exhaust room / building temperature sensor Ti803, then to cross-flow / counterflow plate heat exchanger PHE 102, then to first coil inlet temperature sensor T801, and then to first coil 703, which belongs to an advanced integrated cooling and heating module with CO2 pressure optimization 750.

[0220] 300 = An air handling unit (AHU) controlled by ECU 800, with first coil inlet temperature sensor T801. The air handling unit (AHU) includes air handling unit mechanical part 301, as detailed below. Air handling unit (AHU) 300 is designed to receive exhaust air 23, which is sent to first coil 703 via first coil inlet temperature sensor T 801. This first coil belongs to an integrated cooling and heating module with carbon dioxide 700, and then to rotary heat exchanger (RHE) 302.

[0221] 301 = The mechanical part of the air handling unit (AHU) includes the following components and is designed to receive exhaust air 23, which is sent to first coil 703 via first coil inlet temperature sensor T 801. This first coil belongs to an integrated cooling and heating module with carbon dioxide 700, and then to rotary heat exchanger (RHE) 302.

[0222] 302 = Rotary heat exchanger (RHE).

[0223] 303 = Rotary heat exchanger (RHE) rotation speed per minute (RPM) control, which can be used to adjust the efficiency of the RHE heat exchange function.

[0224] 350 = Air handling unit (AHU) controlled by ECU 800, with a first coil inlet temperature sensor T 801. The air handling unit (AHU) includes an air handling unit mechanical part 351, as detailed below. The air handling system (AHU) 351 is designed to receive exhaust air 23, which, via the first coil inlet temperature sensor T 801, is delivered to a first coil 703, which belongs to an advanced integrated cooling and heating module with carbon dioxide pressure optimization 750, and then to a rotary heat exchanger (RHE) 302.

[0225] 351 = Air handling unit (AHU) mechanical part, including the following components, and designed to receive exhaust air 23, which, via the first coil inlet temperature sensor T 801, is delivered to a first coil 703, which belongs to an advanced integrated cooling and heating module with carbon dioxide pressure optimization 750, and then to a rotary heat exchanger (RHE) 302.

[0226] 400 = An air handling unit (AHU) controlled by ECU 800, with a first coil inlet temperature sensor T 801. The air handling unit (AHU) includes an air handling unit mechanical part 401, as detailed below.Air handling unit (AHU) 400 is designed to receive exhaust air 23, pass it to exhaust room / building temperature sensor Ti 803, then to rotary heat exchanger (RHE) 302, then to first coil inlet temperature sensor T 801, and then to first coil 703, which belongs to an integrated cooling and heating module with carbon dioxide 700.

[0227] 401 = Air handling unit (AHU) mechanical part, including the following components and designed to receive exhaust air 23, pass it to exhaust room / building temperature sensor Ti 803, then to rotary heat exchanger (RHE) 302, then to first coil inlet temperature sensor T 801, and then to first coil 703, which belongs to an integrated cooling and heating module with carbon dioxide 700.

[0228] 450 = Air handling unit (AHU) controlled by ECU 800, with first coil inlet temperature sensor T 801. The air handling unit (AHU) includes an air handling unit mechanical section 451, as detailed below. Air Handling Unit Instruction Manual 23 / 27 28 CN 122029386 A The (AHU) 450 is designed to: receive exhaust air 23, pass it through the exhaust room / building temperature sensor Ti 803, then to a rotary heat exchanger (RHE) 302, then to a first coil inlet temperature sensor T 801, and subsequently to a first coil 703, which belongs to an advanced integrated cooling and heating module with CO2 pressure optimization 750.

[0229] 451 = The air handling unit (AHU) mechanical part includes the following components and is designed to: receive exhaust air 23, pass it through exhaust room / building temperature sensor Ti 803, then to rotary heat exchanger (RHE) 302, then to first coil inlet temperature sensor T 801, and then to first coil 703, which belongs to an advanced integrated cooling and heating module with CO2 pressure optimization 750.

[0230] 500 = An air handling unit (AHU) controlled by ECU 800, with first coil inlet temperature sensor T 801. The air handling unit (AHU) includes air handling unit mechanical part 501, as detailed below. The air handling unit (AHU) 500 is designed to receive exhaust air 23, which is sent to the first coil 703 via the first coil inlet temperature sensor T 801. The first coil belongs to an integrated cooling and heating module with carbon dioxide 700, and then to the coiled tube heat exchanger system (RAC) 502.

[0231] 501 = The air handling unit (AHU) mechanical part includes the following components and is designed to: receive exhaust air 23, send it via a first coil inlet temperature sensor T 801 to a first coil 703, which belongs to an integrated cooling and heating module with carbon dioxide 700, and then send it to a coiled heat exchanger (RAC) 502.

[0232] 502 = Coiled heat exchanger (RAC).

[0233] 503 = Coiled heat exchanger (RAC) fluid flow control actuator, which can be used to adjust the efficiency of the RAC heat exchange function.

[0234] 550 = An air handling unit (AHU) controlled by an ECU 800, with a first coil inlet temperature sensor T 801. The air handling unit (AHU) includes an air handling unit mechanical part 551, as detailed below. Air handling unit (AHU) 550 is designed to receive exhaust air 23, which is delivered to a first coil 703 via a first coil inlet temperature sensor T 801. This first coil belongs to an advanced integrated cooling and heating module with carbon dioxide pressure optimization 750, and then to a coiled heat exchanger system (RAC) 502.

[0235] 551 = The air handling unit (AHU) mechanical part includes the following components and is designed to receive exhaust air 23, which is delivered to a first coil 703 via a first coil inlet temperature sensor T 801. This first coil belongs to an advanced integrated cooling and heating module with carbon dioxide pressure optimization 750, and then to a coiled heat exchanger system (RAC) 502.

[0236] 600 = An air handling unit (AHU) controlled by ECU 800, with a first coil inlet temperature sensor T 801. The air handling unit (AHU) includes an air handling unit mechanical part 601, as detailed below. Air handling unit (AHU) 600 is designed to receive exhaust air 23 to exhaust room / building temperature sensor Ti 803, then to a coiled heat exchanger system (RAC) 502, then to a first coil inlet temperature sensor T 801, and then to a first coil 703, which is part of an integrated cooling and heating module with carbon dioxide 700.

[0237] 601 = The mechanical part of the air handling unit (AHU) includes the following components and is designed to receive exhaust air 23 to exhaust room / building temperature sensor Ti 803, then to a coiled heat exchanger system (RAC) 502, then to a first coil inlet temperature sensor T 801, and then to a first coil 703, which is part of an integrated cooling and heating module with carbon dioxide 700.

[0238] 650 = An air handling unit (AHU) controlled by ECU 800, with a first coil inlet temperature sensor T 801. The air handling unit (AHU) includes an air handling unit mechanical part 651, as detailed below.The air handling unit (AHU) 650 is designed to receive exhaust air 23 to the exhaust room / building temperature sensor Ti 803, then to the retractable heat exchanger (RAC) 502, then to the first coil inlet temperature sensor T 801, and then to the first coil 703, which belongs to the advanced integrated cooling and heating module with carbon dioxide pressure optimization 750.

[0239] 651= The mechanical part of the air handling unit (AHU) includes the following components and is designed to receive exhaust air 23 to the exhaust room / building temperature sensor Ti 803, then to the retractable heat exchanger (RAC) 502, then to the first coil inlet temperature sensor T 801, and then to the first coil 703, which belongs to the advanced integrated cooling and heating module with carbon dioxide pressure optimization 750.

[0240] 700 = Integrated cooling and heating module with carbon dioxide 700.

[0241] 701 = AHU module with simple integrated cooling and heating module 700 carbon dioxide.

[0242] 702 = Second coil. Reversible heat exchanger on the supply air side. "Reversible" means that when operating in cooling mode, the coil acts as an evaporator; when operating in heating mode, the coil acts as a condenser (subcritical) or a gas cooler (transcritical).

[0243] 703 = First coil. Reversible heat exchanger on the exhaust air side. See the second coil 702 above.

[0244] 704 = Variable frequency or switching compressor.

[0245] 705 = Expansion valve.

[0246] 707 = Expansion valve (flash receiver pressure control).

[0247] 708 = Expansion valve (gas cooler pressure control).

[0248] 709 = Flash receiver tank.

[0249] 710 = Expansion valve (suction superheat control) 720 = R744 type carbon dioxide refrigerant 721 = R744 type carbon dioxide refrigerant for advanced carbon dioxide refrigerant circuit 750 = Advanced carbon dioxide refrigerant circuit with pressure optimization 751 = AHU module with advanced carbon dioxide refrigerant circuit 760 = Carbon dioxide (R744) refrigerant circuit, for example: integrated cooling and heating module (700) with carbon dioxide; or advanced integrated cooling and heating module (750) with carbon dioxide pressure optimization.

[0250] 800 = Electronic control unit (ECU) for controlling and optimizing the refrigeration process in a transcritical or subcritical carbon dioxide refrigerant circuit. The ECU receives the exhaust air temperature T before the airflow passes through the first coil, i.e., the exhaust-side reversible heat exchanger. The ECU determines the optimal control required for the heat exchanger efficiency parameters to ensure that the transcritical or subcritical carbon dioxide refrigerant circuit process is optimized.Then, the ECU can control the bypass valve of the cross-flow / counterflow plate heat exchanger (if any), or control the rotational speed of the rotary heat exchanger, or control the liquid flow rate in the RAC system.

[0251] 801 = First coil inlet temperature sensor T. Located at the inlet of the first coil 703, it is used to sense the temperature of the airflow entering the first coil 703.

[0252] 802 = Optimal target range of temperature sensor T; i.e., first coil inlet temperature sensor T (801). This range can be pre-configured, or provided through an interface that defines the actual optimal target range of temperature sensor T, or provided by manually setting the optimal target range of first coil inlet temperature sensor T 801.

[0253] 803 = Exhaust room / building temperature sensor Ti. The sensor measures the room temperature and / or the temperature of the exhaust airflow entering the mechanical part of the AHU, which typically flows through an exhaust duct to the sensor 803 and then to the heat exchange functional unit (PHE, RHE, or RAC) before reaching the first coil inlet temperature sensor T 801. The temperature difference between the two sensors will indicate the temperature difference on the controlled heat exchange functional unit, which is controlled by the PHE bypass valve, the RHE speed, or the circulation flow regulation on the RAC subsystem.

[0254] 804 = Determination function module for regulating demand, used to control the efficiency of the AHU heat exchange functional unit to maintain the optimal air temperature at the first coil 703. This control function is implemented as a method for optimizing the exhaust air temperature flowing into the first coil 703, i.e., the exhaust side reversible heat exchanger.

[0255] 805 = Learning function module for feedback adjustment of the regulation function based on regulation history and deviation.

[0256] 806 = Heat exchange efficiency control signal. This control signal 806 is used to adjust the heat exchange performance of PHE, RHE, or RAC in an AHU with a carbon dioxide refrigerant circuit, wherein the signal is adapted according to the type of AHU to be controlled, specifically depending on the presence of PHE (102), RHE (302), or RAC (502), if a system configuration file 812 is available, as indicated by the system configuration file 812.

[0257] 810 = Electronic control unit (ECU) hardware (HW) includes electronics, control functions, and computing functions, such as a microcontroller, CPU, MPU, and is equipped with memory for storing and executing software 811. Alternatively, the hardware may also be a hardware configuration method that at least executes a decision function module 804 and preferably a learning function module 805.

[0258] 811 = ECU software or control logic implementation for optimizing an integrated cooling and heating module with carbon dioxide 700, or an advanced integrated cooling and heating module 750 with pressure control.

[0259] 812 = System configuration file providing information about the air handling unit or AHU type, enabling the electronic control unit (ECU) 800 to determine 804 and control: an actuator 821 for regulating the bypass channel of PHE 100, 150, 200 or 250; a regulator 822 for regulating the RHE speed of RHE 300, 350, 400 or 450; or a regulator 823 for regulating the RAC liquid flow rate of RAC 500, 550, 600 or 650.

[0260] 820 = AHU with carbon dioxide refrigerant loop control, using heat exchange efficiency control signal 806 to optimize the temperature of the following modules: a) an integrated cooling and heating module with carbon dioxide 700, or b) an advanced integrated cooling and heating module with carbon dioxide pressure optimization 750.

[0261] 821 = Actuator for the PHE bypass channel damper, regulating PHE 100, 150, 200, or 250.

[0262] 822 = Regulator for RHE speed, regulating RHE 300, 350, 400, or 450.

[0263] 823 = Regulator for RAC liquid flow rate, regulating RAC 500, 550, 600, or 650.

[0264] 900 = Building, with the air handling unit installed inside.

[0265] 900' = Building, with the air handling unit at least partially installed outside.

[0266] 901 = Building walls and roof.

[0267] 902 = External air temperature of the building, temperature T0.

[0268] 903 = Internal air temperature of the building, temperature Ti.

[0269] 904 = Sun and environment with thermal radiation 905.

[0270] 905 = Thermal radiation from the sun 904 and the environment.

[0271] S1000–S4000 represent method steps. In Figure 16, dashed lines represent optional method steps.

[0272] S1000 = Receive temperature sensor data T.

[0273] S1100 = Set the optimal target range for sensor T.

[0274] S1200 = Receive the exhaust air temperature of the room / building.

[0275] S2000 = Determine the adjustment requirements for the AHU heat exchanger efficiency to achieve the optimal air temperature before the air cooler / condenser.

[0276] S3000 = Adjust the heat exchanger efficiency control parameters.

[0277] S3100 = Adjust the rotational speed of the rotary heat exchanger.

[0278] S3200 = Adjust the damper for the bypass passage of the cross-flow / counter-flow plate heat exchanger (PHE) 102. This bypass channel allows a portion of the fluid in the system to bypass the heat exchanger via a path that bypasses it.Instruction manual, pages 26 / 27, 31 CN 122029386 A

[0279] S3300 = Regulate the liquid flow rate in the RAC system to control the heat recovery process in the coiled tube heat exchanger (RAC), thereby regulating the temperature at sensor T, which is located at the position where air enters the first coil (703) in the AHU equipped with RAC500, 550, 600 and 650, i.e., the exhaust-side reversible heat exchanger.

[0280] S4000 = In step S4000, based on the regulation history, a learning and regulation control loop is used to adjust the various parameters of the regulation step determined in step S2000. In step S4000, the historical deviation between the set temperature range defined by the optimal target range setting of sensor T 802 is analyzed; thereby adjusting the regulation parameters of the regulation demand determination function module 804 in step S2000. Instruction manual page 27 / 27, 32 CN 122029386 A, Figure 1; Instruction manual figure 1 / 16 page, 33 CN 122029386 A, Figure 2; Instruction manual figure 2 / 16 page, 34 CN 122029386 A, Figure 3; Instruction manual figure 3 / 16 page, 35 CN 122029386 A, Figure 4; Instruction manual figure 4 / 16 page, 36 CN 122029386 A, Figure 5; Instruction manual figure 5 / 16 page, 37 CN 122029386 A, Figure 6; Instruction manual figure 6 / 16 page, 38 CN 122029386 A, Figure 7; Figure 8; Instruction manual figure 7 / 16 page, 39 CN 122029386 A, Figure 9; Instruction manual figure 8 / 16 page, 40 CN 122029386 A, Figure 10; Instruction manual figure 9 / 16 page, 41 CN 122029386 A, Figure 11 Figure 12, Figure 13a, Figure 13b, Figure 14a, Figure 14b, Figure 15, Figure 16, Figure 17, Figure 18, Figure 19, Figure 10 / 16, Page 42, CN 122029386 A, Figure 12, Figure 13a, Figure 14b, Figure 15, Figure 16, Figure 17, Figure 19, Figure 19, Figure 10 / 16, Page 43, CN 122029386 A, Figure 13b, Figure 19, Figure 10 / 16, Page 44, CN 122029386 A, Figure 19, Figure 10 / 16, Page 48, CN 122029386 A ... Page 48, CN 122029386 A, Figure 10 / 16, Page 48, Page 48, CN 122029386 A, Figure 10 / 16, Page 48, Page 48, CN 122029386 A, Figure 10 / 16, Page 48, Page 48, Page

Claims

1. An air handling unit (50; 100, 150, 200, 250; 300, 350, 400, 450; 500, 550, 600, 650), comprising: Outdoor airflow channel (21); Air supply duct (22); Exhaust duct (23); Exhaust passage (24); The heat exchange functional component (52) is one of the following: Cross-flow / counter-flow plate heat exchanger PHE (102) Rotary heat exchanger RHE (302) or RAC (502) coiled tube heat exchange system; and A carbon dioxide (R744) refrigerant circuit (760, 700, 750), wherein the carbon dioxide (R744) refrigerant circuit (760, 700, 750) comprises: The first coil (703) is placed in: Between the exhaust duct (23) and the exhaust duct (24); The second coil (702) is placed between the heat exchange functional component (52) and the air supply duct (22); and First coil air inlet temperature sensor T(801); The carbon dioxide (R744) refrigerant circuits (760, 700, 750) are configured to transfer heat between the first coil (703) and the second coil (702). Its features are, The first coil (703) is configured to exchange heat with an airflow originating from the exhaust duct (23), which may be air received from inside the building (900).

2. The air handling unit (100, 200, 300, 400, 500, 600) according to claim 1, characterized in that, The carbon dioxide (R744) refrigerant circuit (760) is an integrated carbon dioxide cooling and heating module (700).

3. The air handling unit (150, 250; 350, 450; 550, 650) according to claim 1, characterized in that, The carbon dioxide (R744) refrigerant circuit (760) is an advanced integrated cooling and heating module (750) with carbon dioxide pressure optimization.

4. The air handling unit (100, 150; 300, 350; 500, 550) according to any one of claims 1-3, characterized in that, The first coil (703) is placed in: Between the exhaust duct (23) and the heat exchange functional component (52).

5. The air handling unit (100, 150, 300, 350, 500, 550) according to any one of claims 1-4, characterized in that, It is configured as follows: Exhaust air is received through the exhaust duct (23) and via the first coil air inlet temperature sensor T (801). It is sent to the first coil (703), and then sent to The heat exchange functional component (52); the heat exchange functional component (52) is: Cross-flow / counter-flow plate heat exchanger PHE (102), rotary heat exchanger RHE (302) or coiled tube heat exchanger RAC (502).

6. The air handling unit (200, 250, 400, 450, 600, 650) according to any one of claims 1-3, characterized in that: The first coil (703) is placed in: Between the heat exchange functional component (52) and the exhaust channel (24).

7. The air handling unit (200, 250; 400, 450; 600, 650) for cold energy recovery according to any one of claims 1-3, 6, characterized in that, It is configured as follows: Exhaust air is received via exhaust duct (23) and sent to The exhaust room / building temperature sensor Ti 803 is then sent to the heat exchange functional component (52), which is: Cross-flow / counter-flow plate heat exchanger PHE (102), rotary heat exchanger RHE (302), or coiled tube heat exchanger RAC (502); then sent to The first coil air inlet temperature sensor T(801); and It is then sent to the first coil (703).

8. The air handling unit (100, 150, 200, 250) according to any one of claims 1-7, characterized in that: The heat exchange functional component (52) is a cross-flow / counter-flow plate heat exchanger (PHE) (102).

9. The air handling unit (300, 350, 400, 450) according to any one of claims 1-7, characterized in that: The heat exchange functional component (52) is a rotary heat exchanger (RHE) (302).

10. The air handling unit (500, 550, 600, 650) according to any one of claims 1-7, characterized in that: The heat exchange functional component (52) is a coiled tube heat exchange system (RAC) (502).

11. The air handling unit (100, 150, 200, 250) according to any one of claims 8-10, characterized in that, It also includes a bypass ventilator (53), which is configured as follows: When the bypass valve (52) is opened, at least part of the airflow can bypass the heat exchange component (52).

12. The air handling unit (300, 350, 400, 450) according to claim 9, characterized in that, It also includes a rotary heat exchanger (RHE) controlled by rotational speed per minute (RPM), which can be used to adjust the efficiency of the RHE heat exchange.

13. The air handling unit (500, 550, 600, 650) according to claim 10, characterized in that, It also includes a fluid flow control actuator for a coiled tube heat exchanger (RAC) system, which is used to regulate the efficiency of the heat exchange in the RAC.

14. The air handling unit (200; 250; 400, 450; 600, 650) according to any one of claims 1-13, characterized in that, Also includes: The exhaust room / building temperature sensor (803) is configured to receive the value of the exhaust room / building temperature sensor (803).

15. An electronic control unit (ECU) (800) configured to control an air handling unit (AHU) (50; 100, 150, 200, 250; 300, 350, 400, 450; 500, 550, 600, 650) according to any one of claims 1-14, characterized in that, include: Electronic control unit hardware (ECUHW) (810) for sensor data processing and AHU operation optimization; An interface connected to the first coil air inlet temperature sensor T (801), wherein the first coil air inlet temperature sensor T (801) is configured to sense the temperature at the air inlet of the first coil (703); The interface with the exhaust airflow temperature sensor Ti (803) is configured to sense the temperature at the exhaust duct (23) or the temperature inside the building or room (900); The determination function module (804) is configured to determine the heat exchange efficiency control signal (806) based on the data from the first coil air inlet temperature sensor T (801) and the data from the exhaust airflow temperature sensor Ti (803) collected as needed. The efficiency of the AHU heat exchanger is controlled according to the heat exchange efficiency control signal (806) to maintain the air inlet temperature of the first coil (703) within the optimal target range (802) of the first coil air inlet temperature sensor T (801); and The efficiency of the heat exchange functional component (52) is adjusted according to the heat exchange efficiency control signal (806) to regulate: Actuator (821) for PHE bypass valve, regulator (822) for RHE speed or Regulator (823) for RAC fluid flow rate.

16. The ECU (800) according to claim 15, characterized in that, Also includes: The learning function module (805) is used to provide feedback adjustment to the control function in the judgment function module (804) based on the control history.

17. The ECU (800) according to any one of claims 15 to 16, further comprising: Sensor T optimal target range setting module (802), and / or The system configuration file (812) defines at least one optimal temperature target range (802).

18. The ECU (800) according to any one of claims 15-17, characterized in that, The ECU is configured as a software-based cloud service for interfacing with and controlling at least one air handling unit (AHU) according to claims 1-13 (50; 100, 150, 200, 250; 300, 350, 400, 450; 500, 550, 600, 650).

19. The air handling unit (50, 100, 150, 200, 250; 300, 350, 400, 450; 500, 550, 600, 650) according to any one of claims 1-14, characterized in that, Also includes: The ECU (800) according to any one of claims 14-18 is configured as follows: Control the air handling units (50, 100, 150, 200, 250; 300, 350, 400, 450; 500, 550, 600, 650), and / or Control the AHU (50, 200, 250; 400, 450; 600, 650) with cold energy recovery to maintain the detection temperature of the first coil air inlet temperature sensor T (801) within the optimal range.

20. A method for improving the cold energy recovery efficiency and system efficiency of an air handling unit, wherein the air handling unit is an air handling unit (AHU) according to any one of claims 1-14 and 19, the method being performed by an electronic control unit (ECU) (800) according to any one of claims 15-18, characterized in that, Includes the following steps: （S1000） Receive the first coil air inlet temperature collected by sensor T (801); （S1200） Receive the temperature collected by the exhaust room / building temperature sensor Ti (803); （S2000） Determine the adjustment requirement (804) to generate a heat exchange efficiency control signal (806); To enable transcritical or subcritical refrigerant cycles to reach and maintain optimal conditions, and Maintain the air inlet temperature of the first coil (703) at sensor T (801) within the optimal temperature range (802) for a transcritical or subcritical cycle air cooler for carbon dioxide. （S3000） The heat exchange efficiency control parameters are adjusted using the heat exchange efficiency control signal (806) in the following manner: (S3100) Adjust the rotation speed (303) of the rotary heat exchanger (302); (S3200) Regulates the bypass valve used for the cross-flow / counter-flow heat exchanger (102); or (S3300) Regulates the fluid flow rate of the coiled tube heat exchanger system (RAC) (502). To achieve efficient cold energy recovery and maximum system efficiency.

21. The method according to claim 20, characterized in that, Also includes: Step (S1100) is performed before step (S2000), wherein step (S1100) includes: （S1100） Set the optimal target temperature range (OTTR) for temperature sensor T (802). This allows the optimal target temperature range to be used in step (S2000) to determine the adjustment requirements for the heat exchanger efficiency.

22. The method according to any one of claims 20-21, characterized in that, Also includes: Step (S1200) is performed before step (S2000), wherein step (S1200) includes: （S1200） The exhaust temperature is obtained from the room / building (TTR) (801), so that the exhaust temperature determination from the room / building (804) is used in step (S2000) to adjust the demand, that is, to generate a heat exchange efficiency control signal (806) to adjust the heat exchanger efficiency.

23. The method according to any one of claims 20-22, characterized in that, Also includes: The optimal temperature target range (802) of the temperature sensor T is set between 15 degrees Celsius and 40 degrees Celsius, preferably between 20 and 32 degrees Celsius.

24. The method according to any one of claims 20-23, characterized in that, Also includes: Step (S4000) is performed after step (S3000), wherein step (S4000) includes: （S4000） Learning, or feedback adjustment of the control loop, to optimize control parameters for: In step (S2000), the adjustment requirement for the heat exchanger efficiency is determined.

25. A heating, ventilation, and air conditioning (HVAC) system (20) comprising at least one air handling unit (AHU) (50; 100, 150, 200, 250; 300, 350, 400, 450; 500, 550, 600, 650) according to any one of claims 1-14 or 19, characterized in that, The exhaust duct (23) is connected to the interior of a building (900), vehicle, train or ship.

26. A building or vehicle, characterized in that, Includes the HVAC system (20) according to claim 25, or the air handling unit (50, 100...650) according to any one of claims 1-14 or 19.

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