Multi-split air conditioning system

Abstract

The invention discloses a multi-split air conditioning system, and belongs to the technical field of air conditioners. The system comprises an outdoor unit, an indoor unit, an indoor water tail end and an air handling unit. A controller is configured to determine whether the air handling unit is a refrigeration main body or a heating main body; if the air handling unit is a refrigeration main body, a second four-way valve is controlled based on refrigeration heat exchange control logic, so that the second four-way valve communicates with the outdoor heat exchanger and the reheating heat exchanger, and an expansion valve of the outdoor heat exchanger is controlled to be in a non-cut-off state; and if the air handling unit is the heating main body, an expansion valve of the outdoor heat exchanger is controlled to be in a non-cut-off state based on the heating and heat exchange control logic, and an outdoor fan is controlled to operate based on the preset rotating speed. According to the air conditioning system, different strategies of four-way valve switching and outdoor heat exchanger expansion valve control are carried out only through recognition of a refrigerating main body and a heating main body, heat transfer of the reheating heat exchanger and the dehumidification heat exchanger can be achieved, and basic temperature and humidity regulation and control are achieved.

Description

Technical Field

[0001] This application relates to the field of air conditioning technology, and in particular to a multi-split air conditioning system. Background Technology

[0002] In a multi-split air conditioning system, one or more outdoor units are typically connected to multiple indoor terminal units via piping to form a complete refrigerant circulation system, enabling temperature and humidity regulation in multiple areas. Unlike traditional single-function air conditioning systems, multi-split air conditioning systems offer greater flexibility and integration, allowing simultaneous connection to various types of terminal units, such as water system terminals, air handling units (AHUs) for dehumidification and reheating, fresh air system terminals, and conventional cooling / heating indoor units. The system can simultaneously support multiple operating modes, including hot water production, cooling and dehumidification, and conventional air conditioning, and is widely used in large buildings, commercial spaces, or high-precision process environments requiring zoned control or complex climate conditions.

[0003] As a key air handling unit in the system, the AHU (Air Handling Unit) typically includes a condenser and evaporator to perform dehumidification and reheating functions, thereby regulating the temperature and humidity of the air. In a multi-split air conditioning system equipped with an AHU, when the AHU is connected to the outdoor unit, the system calculates the required cooling and heating demand based on the real-time parameters of the inlet air and the target air parameters, and adjusts the compressor's operating frequency accordingly to achieve the appropriate air conditioning.

[0004] However, in practical applications, when systems require precise temperature and humidity control, a significant difference in load demands between the reheat heat exchanger and the dehumidification heat exchanger often arises. Because the compressor, dehumidification heat exchanger, and reheat heat exchanger are connected in series in the system structure, the system can only be regulated with a single, unified compressor control target. This leads to a difficulty in synchronously matching the compressor's output capacity with the actual demands of each heat exchanger. This capacity mismatch directly affects the temperature and humidity control performance of the terminal air handling unit, especially in scenarios requiring high precision in temperature and humidity control.

[0005] Therefore, under the existing air conditioning system architecture with heat recovery function, in order to improve the response capability and control accuracy of temperature and humidity regulation, there is an urgent need for a control method that can coordinate the operating status of the compressor and related heat exchange units according to the actual needs of the terminal, so as to achieve a more refined temperature and humidity regulation target. Summary of the Invention

[0006] This application provides a multi-split air conditioning system, including: The outdoor unit has a compressor, an outdoor heat exchanger, a first four-way valve, and a second four-way valve. The first end D1 of the first four-way valve is connected to the exhaust side of the compressor. The fifth end D2 of the second four-way valve is connected to the first end D1 of the first four-way valve and to the seventh end E2 of the second four-way valve. The sixth end C2 of the second four-way valve is connected to the outdoor heat exchanger and to the eighth end S2 of the second four-way valve. Indoor unit, which has an indoor heat exchanger; The indoor water terminal is connected to the compressor via a high-pressure pipeline and to the outdoor heat exchanger via a liquid pipeline. The expansion valve of the outdoor heat exchanger is in the closed state. An air handling unit includes a dehumidifying heat exchanger and a reheat heat exchanger, wherein the first end of the dehumidifying heat exchanger and the first end of the reheat heat exchanger are connected to the liquid pipes of the indoor water terminal. The second end of the dehumidifying heat exchanger is connected to the suction side of the compressor, the fourth end S1 of the first four-way valve, and the eighth end S2 of the second four-way valve through a low-pressure pipeline. The third end E1 of the first four-way valve is connected to the fourth end S1. The second end of the reheat heat exchanger is connected to the second end C1 of the first four-way valve through a high-low pressure switching pipeline, and the second end C1 of the first four-way valve is connected to the first end D1. The controller is configured as follows: Determine whether the air handling unit is the main cooling or heating unit; If the air handling unit is the main cooling unit, the second four-way valve is controlled based on the cooling heat exchange control logic to connect the outdoor heat exchanger and the reheat heat exchanger, and the expansion valve of the outdoor heat exchanger is controlled to be in a non-stop state. At this time, the refrigerant can flow to the outdoor heat exchanger and the outdoor heat exchanger is used as a condenser for heat exchange. If the air handling unit is the main heating unit, the expansion valve of the outdoor heat exchanger is controlled to be in a non-stop state based on the heating and heat exchange control logic, and the outdoor fan is controlled to run based on the preset speed, so that the outdoor heat exchanger participates in heat exchange as an evaporator and transfers the heat exchange of the dehumidifying heat exchanger.

[0007] Based on the above embodiments, the multi-split air conditioning system of this application can simultaneously connect cooling terminals and heating terminals. By adjusting the first four-way valve and the second four-way valve, controlling the outdoor fan, and / or controlling the opening of the outdoor heat exchanger expansion valve, heat recovery can be achieved, thereby improving the energy efficiency of existing equipment.

[0008] By coordinating the operation of the four-way valve, expansion valve, and fan, the refrigerant path can be dynamically adjusted to meet the precise heat exchange control requirements under different operating modes. When the air handling unit is the main heating component, a dual evaporation mechanism using a dehumidifying heat exchanger and an outdoor heat exchanger is employed. The outdoor heat exchanger reduces the heat exchange load of the dehumidifying heat exchanger, ensuring that the indoor air is not excessively dry. When the air handling unit is the main cooling component, the outdoor heat exchanger acts as a condenser connected to the reheat heat exchange process, effectively reducing the heat exchange load of the reheat heat exchanger and preventing the air temperature after reheat heat exchanger treatment from becoming too high. This achieves precise air temperature control and improves indoor comfort.

[0009] In some embodiments, the fifth terminal D2 and the sixth terminal C2 of the second four-way valve are connected based on the refrigeration heat exchange control logic, and the seventh terminal E2 and the eighth terminal S2 of the second four-way valve are connected. At this time, the high-temperature and high-pressure refrigerant discharged by the compressor flows to the indoor water terminal, the reheat heat exchanger of the air handling unit and the outdoor heat exchanger for condensation heat exchange, transferring the heat exchange of the reheat module to the outdoor heat exchanger. The heat exchange burden of the reheat heat exchanger is partially borne by the outdoor heat exchanger, which can significantly reduce its output load, avoid temperature control deviation caused by excessive reheat capacity of the air handling unit, improve the stability and accuracy of system operation, and use the outdoor heat exchanger to restore the output capacity of the reheat module to the process parameter deviation range.

[0010] In some embodiments, the controller is further configured to: If the air handling unit is the main heating component, the opening degree of the expansion valve is controlled to adjust the normalized real-time superheat. Approximate to or equal to the normalized target superheat .

[0011] Based on the above configuration, the controller of this application adjusts the opening of the expansion valve in real time through closed-loop control logic to accurately control the refrigerant flow, ensure that the refrigerant heat exchange meets the target heat exchange, and guarantee the stability of the air handling unit when it is in heating mode.

[0012] In some embodiments, the controller is further configured to: Obtain the gas pipe temperature of the outdoor heat exchanger and liquid tube temperature Based on tracheal temperature and liquid tube temperature Determine the real-time superheat; According to the outdoor side return temperature of the outdoor heat exchanger and evaporation temperature The real-time superheat is normalized to obtain the normalized real-time superheat. .

[0013] Specifically, the normalized real-time superheat can be calculated based on the following calculation model: ,in, This is the air volume correction factor. The correction coefficients are obtained from product test results. Since the design of heat exchangers and fans at different terminals varies, which will affect the heat exchange capacity of the heat exchanger, the correction coefficients are different. By adding correction parameters, the applicability and robustness of the model are improved, so that it can cover different equipment types and operating conditions.

[0014] In some embodiments, the controller is further configured to: The outdoor heat exchanger is determined as the normalized heat transfer capacity of the evaporator. The normalized heat transfer Substituting into the normalized target superheat model, the normalized target superheat is calculated. .

[0015] In the above embodiments, the normalized target superheat model can be expressed as the following calculation model: ,in, To calculate the correlation coefficient, it is obtained through regression of historical data or product trial fitting and dynamically adjusted according to different product versions.

[0016] The above calculation model adopts a rational function structure, which can fit the dynamic trend of target subcooling with load change well. It has high versatility and adjustability and is suitable for various environments and operating conditions.

[0017] Based on the above configuration, this application embodiment estimates the current heat exchange demand as the operating intensity of the current system under actual load. The controller uses this value as the target control input to further drive the expansion valve to adjust the opening, thereby controlling the actual superheat to approach the target value and realizing the fine adjustment of the refrigerant supply on the evaporator side.

[0018] In some embodiments, the controller is further configured to: Obtain the maximum heat exchange capacity of the outdoor heat exchanger as the evaporator. and minimum heat exchange The specific value is obtained in advance through product testing; Based on the maximum heat exchange and minimum heat exchange The difference determines the maximum evaporative heat transfer difference; Based on the required heat exchange capacity of the outdoor heat exchanger as an evaporator With the minimum heat exchange The difference determines the difference in heat exchange required for evaporation; The normalized heat transfer is determined based on the quotient of the difference between the evaporation demand heat transfer value and the difference between the maximum evaporation heat transfer value. .

[0019] In the above embodiments, normalized heat transfer This can be represented by the following computational model: ; Based on the above control logic, the controller uses the calculated normalized heat transfer rate... The normalized target superheat was calculated. The opening of the expansion valve is dynamically adjusted through a closed-loop control algorithm to achieve normalized real-time superheat. Approximate to or equal to the normalized target superheat This allows for precise control of evaporation pressure and refrigerant flow, enabling accurate adjustment of the outdoor heat exchanger expansion valve, preventing superheat deviation, and effectively improving temperature control accuracy. By introducing airflow correction, model correction parameters, and polynomial fitting expression, the above model possesses good versatility and scalability, and can be widely applied to heat exchange systems of different models and configurations.

[0020] In some embodiments, the controller is further configured to: If the air handling unit is the main refrigeration unit, the opening degree of the expansion valve is controlled to ensure the normalized real-time subcooling degree. Approximate to or equal to the normalized target supercooling .

[0021] Based on the above configuration, the opening of the expansion valve is adjusted in real time through closed-loop control logic, thereby regulating the refrigerant flow into the outdoor heat exchanger and optimizing the subcooling control accuracy and system operating efficiency. This control strategy ensures that the refrigerant at the condenser outlet (in this case, the outdoor heat exchanger) is maintained within the ideal subcooling range, improving heat exchange performance and system stability.

[0022] In some embodiments, the controller is further configured to: Obtain the saturation temperature corresponding to the high pressure of the outdoor heat exchanger. and liquid tube temperature Based on saturation temperature and liquid tube temperature The real-time subcooling degree is determined, and the high pressure is obtained based on the detection of a pressure sensor. According to the outdoor side return temperature of the outdoor heat exchanger The real-time superheat is normalized to obtain the normalized real-time undercooling. .

[0023] Specifically, the normalized real-time subcooling can be calculated based on the following calculation model: ,in, This is the air volume correction factor. This is the model correction factor.

[0024] In the above embodiment, the outdoor side temperature recovery It can be the return water temperature or the return air temperature, and the outdoor side return temperature. Liquid tube temperature The temperature is detected by the temperature sensor of the air conditioning system.

[0025] Based on the above configuration, the controller in this application accurately assesses the subcooling level of the refrigerant by monitoring the operating status of the high-pressure side in real time. The controller obtains the corresponding refrigerant saturation temperature by looking up a table or calling the built-in thermodynamic model based on the pressure value. Simultaneously, the system also obtains the actual temperature of the refrigerant at the liquid line location via a temperature sensor. The temperature difference between these two values ​​represents the current real-time subcooling.

[0026] In some embodiments, the controller is further configured to: The outdoor heat exchanger is determined to have normalized heat transfer capacity as a condenser. The normalized heat transfer Substituting into the normalized target supercooling model, the normalized target supercooling is calculated. .

[0027] In the above embodiments, the normalized target supercooling model can be expressed as the following calculation model: ,in, To calculate the correlation coefficient.

[0028] Based on the above configuration, this embodiment estimates the current heat exchange demand as the operating intensity of the current system under actual load. The controller uses this value as the target control input to further drive the expansion valve to adjust the opening, thereby controlling the actual subcooling to approach the target value and realizing fine adjustment of the refrigerant supply on the condenser side.

[0029] In some embodiments, the controller is further configured to: Obtain the maximum heat transfer capacity of the outdoor heat exchanger as the condenser. and minimum heat exchange The specific value is obtained in advance through product testing; Based on the maximum heat exchange and minimum heat exchange The difference determines the maximum condensation heat transfer difference; Based on the required heat exchange capacity of the outdoor heat exchanger as a condenser With the minimum heat exchange The difference determines the difference in heat exchange required for condensation; The normalized heat transfer is determined based on the quotient of the difference between the required heat transfer and the maximum difference in condensation heat transfer. .

[0030] In the above embodiments, normalized heat transfer This can be represented by the following computational model: .

[0031] In some embodiments, during the product design or commissioning phase, the system obtains the maximum heat transfer capacity of the outdoor heat exchanger when operating as a condenser using test data under standard operating conditions. and minimum heat exchange And it is stored in the controller.

[0032] Based on the above configuration, this application adopts the maximum heat exchange obtained from preliminary experiments. and minimum heat exchange As a benchmark, by calculating the normalized heat transfer using the difference ratio method, the system can accurately reflect the heat transfer capacity requirement of the current operating state relative to the design limit state, thereby improving the accuracy of the target subcooling calculation and the rationality of the control response. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the circulating piping principle of an air conditioning system provided in an embodiment of this application; Figure 2 This is a schematic diagram of the circulation path principle of an air conditioning system provided in an embodiment of this application; Figure 3 This is a schematic diagram of another circulation path of the air conditioning system provided in an embodiment of this application; Figure 4 This is a schematic diagram of another circulation path of the air conditioning system provided in an embodiment of this application; Figure 5 This is a flowchart illustrating the control logic of an air conditioning system provided in an embodiment of this application. Figure 6 Another control logic flowchart of the air conditioning system provided in this application embodiment; Figure 7 Another control logic flowchart of the air conditioning system provided in this application embodiment; Figure 8 Another control logic flowchart of the air conditioning system provided in this application embodiment; Figure 9 Another control logic flowchart of the air conditioning system provided in this application embodiment; Figure 10 This is a schematic diagram of the hardware structure of the controller provided in an embodiment of this application.

[0034] In the above figures: 1. Outdoor unit; 101. Compressor; 102. Outdoor heat exchanger; 103. First four-way valve; 104. Second four-way valve; 2. Indoor unit; 3. Indoor water terminal; 4. Air handling unit; 401. Dehumidifying heat exchanger; 402. Reheat heat exchanger; 501. Processor; 502. Memory. Detailed Implementation

[0035] To make the objectives and implementation methods of this application clearer, the exemplary implementation methods of this application will be clearly and completely described below with reference to the accompanying drawings of the exemplary embodiments of this application. Obviously, the exemplary embodiments described are only some embodiments of this application, and not all embodiments.

[0036] Unless otherwise defined, the technical or scientific terms used in this application shall have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms “a,” “an,” “an,” “the,” and similar words used in this application do not indicate quantity limitation and may indicate singular or plural. The terms “comprising,” “including,” “having,” and any variations thereof used in this application are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or device that includes a series of steps or modules (units) is not limited to the listed steps or units, but may also include steps or units not listed, or may include other steps or units inherent to these processes, methods, products, or devices. The terms “connected,” “linked,” “coupled,” and similar words used in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. “Multiple” used in this application refers to two or more. “And / or” describes the relationship between related objects, indicating that three relationships may exist; for example, “A and / or B” can represent: A alone, A and B simultaneously, and B alone. The character " / " generally indicates that the preceding and following objects are in an "or" relationship. The terms "first," "second," and "third" used in this application are merely to distinguish similar objects and do not represent a specific ordering of the objects.

[0037] Air conditioners execute refrigeration and heating cycles using a compressor, condenser, expansion valve, and evaporator. These cycles are controlled by a controller, which manages refrigerant flow and the opening of the expansion valve. The refrigeration and heating cycles involve a series of processes including compression, condensation, expansion, and evaporation, ultimately supplying refrigerant to the conditioned and heat-exchanged air.

[0038] The compressor compresses refrigerant gas under high temperature and pressure and discharges the compressed refrigerant gas. The discharged refrigerant gas flows into the outdoor heat exchanger. The outdoor heat exchanger condenses the compressed refrigerant into a liquid phase, and the heat is released to the surrounding environment through the condensation process.

[0039] The expansion valve expands the high-temperature, high-pressure liquid refrigerant condensed in the condenser into a low-pressure liquid refrigerant. The evaporator evaporates the expanded refrigerant in the expansion valve, returning the low-temperature, low-pressure refrigerant gas to the compressor. The evaporator achieves its cooling effect by utilizing the latent heat of refrigerant evaporation to exchange heat with the material being cooled. Throughout the cycle, the air conditioner regulates the temperature of the indoor space.

[0040] The outdoor unit of an air conditioner refers to the part of the refrigeration cycle that includes the compressor and the outdoor heat exchanger. The indoor unit of an air conditioner includes the indoor heat exchanger, and an expansion valve can be provided in either the indoor or outdoor unit.

[0041] The indoor and outdoor heat exchangers function as either condensers or evaporators. When the indoor heat exchanger is used as a condenser, the air conditioner functions as a heater in heating mode; when the indoor heat exchanger is used as an evaporator, the air conditioner functions as a cooler in cooling mode.

[0042] like Figure 1 As shown, this application provides a multi-split air conditioning system, including: Outdoor unit 1 includes compressor 101, outdoor heat exchanger 102, first four-way valve 103, and second four-way valve 104. The first end D1 of the first four-way valve 103 is connected to the exhaust side of compressor 101. The fifth end D2 of the second four-way valve 104 is connected to the first end D1 of the first four-way valve 103 and to the seventh end E2 of the second four-way valve 104. The sixth end C2 of the second four-way valve 104 is connected to outdoor heat exchanger 102 and to the eighth end S2 of the second four-way valve 104. Indoor unit 2, which has an indoor heat exchanger; The indoor water terminal 3 is connected to the compressor 101 through a high-pressure pipeline and to the outdoor heat exchanger 102 through a liquid pipeline. The expansion valve of the outdoor heat exchanger 102 is in the closed state. Air handling unit 4 includes a dehumidifying heat exchanger 401 and a reheat heat exchanger 402, with the first end of the dehumidifying heat exchanger 401 and the first end of the reheat heat exchanger 402 connected to the liquid pipes of the indoor water terminal 3. The second end of the dehumidifying heat exchanger 401 is connected to the suction side of the compressor 101, the fourth end S1 of the first four-way valve 103 and the eighth end S2 of the second four-way valve 104 through a low-pressure pipeline. The third end E1 of the first four-way valve 103 is connected to the fourth end S1. The second end of the reheat heat exchanger 402 is connected to the second end C1 of the first four-way valve 103 through a high-low pressure switching pipeline, and the second end C1 of the first four-way valve 103 is connected to the first end D1.

[0043] In the above embodiments, the indoor water terminal 3 includes either a water terminal or a single-heat terminal. A single-heat terminal is an indoor terminal device in a multi-split system that only has a heating function. It is typically used in scenarios where centralized heating is required in winter but cooling is not needed (such as supplemental heating in northern regions, single-heat mode in hotel rooms at night, etc.). Common types of water terminals include fan coil units, radiant panels, and radiators, among which fan coil units are the most mainstream water terminals.

[0044] Under normal circumstances, the outdoor heat exchanger 102 is used as a complete heat recovery device to recover waste heat (such as condensation heat) generated in the refrigeration cycle and transfer it to the stage where heating is required. Figure 2 This is a schematic diagram of the flow path principle of a multi-split air conditioning system, for reference. Figure 2 As shown (the indoor unit, fresh air unit, and other structures are omitted in the figure), the expansion valve of the outdoor heat exchanger 102 is in the closed state to prevent refrigerant backflow, and no high-temperature and high-pressure refrigerant flows through the second four-way valve 104. There is basically no refrigerant flowing in the outdoor heat exchanger 102. The dehumidifying heat exchanger 401 of the air handling unit 4 (AHU) acts as an evaporator. The refrigerant enters the dehumidifying heat exchanger 401 to absorb heat from the air and evaporate, changing from liquid to gas phase. The temperature and humidity in the air decrease, thus achieving the dehumidification function. Subsequently, the evaporated low-temperature and low-pressure gaseous refrigerant is drawn into the suction side of the compressor 101. The compressor 101 compresses the drawn-in low-temperature and low-pressure gaseous refrigerant to obtain a high-temperature and high-pressure gaseous refrigerant.

[0045] The reheat heat exchanger 402 and indoor water terminal 3 of the air handling unit 4 serve as condensers, specifically: The high-temperature and high-pressure gaseous refrigerant connected to the high-pressure pipeline enters the indoor water terminal 3, where it releases energy and transfers heat to the water to provide hot water for heating. The refrigerant itself condenses into a liquid phase. Another part of the high-temperature and high-pressure gaseous refrigerant connected to the high-pressure pipeline enters the reheat heat exchanger 402 through the high-low pressure switching pipeline, releases heat and condenses into liquid phase, which is used to reheat the dehumidified air. Subsequently, the liquid refrigerant from the indoor water terminal 3 and the reheat heat exchanger 402 circulates to the dehumidification heat exchanger 401 through the low-pressure pipeline, forming a dynamic balance and achieving the purpose of hot water production and temperature control and dehumidification.

[0046] When the air handling unit 4 controls the temperature and humidity according to the required air parameters, the change in required sensible heat and the change in required latent heat are calculated based on the inlet air parameters and the required air parameters of the air handling unit 4.

[0047] The change in latent heat demand (also known as dehumidification heat exchange) can be expressed as: ,in, To dehumidify the air volume, This refers to the enthalpy value at the inlet of the dehumidification module of air handling unit 4. The enthalpy value at the outlet of the dehumidification module of air handling unit 4; The change in sensible heat demand (also known as reheat heat exchange) can be expressed as: ,in, For reheat air volume, This is the enthalpy value at the inlet of the reheat module of air handling unit 4. The enthalpy value at the outlet of the dehumidification module of air handling unit 4; The refrigerant heat exchange capacity consists of both latent heat change and sensible heat change. The refrigerant heat exchange capacity during dehumidification / heat exchange can be expressed as: , This refers to the refrigerant flow rate, which is the required amount of refrigerant circulating. The enthalpy value of the imported refrigerant. This refers to the enthalpy value of the refrigerant at the outlet. Based on the compressor frequency calculation model The required compressor frequency for the target heat exchange can be calculated. ,in, For the volumetric efficiency of the compressor, Because the specific volume of the gas is rarefied. The refrigerant circulation volume is directly determined by the compressor frequency. Substituting the refrigerant circulation volume into the compressor frequency calculation model can calculate the required compressor frequency.

[0048] Based on the above model, the required refrigerant heat exchange rate can be calculated based on the sensible heat change rate and the latent heat change rate, and the compressor frequency used for control can be calculated based on the refrigerant circulation volume required for the refrigerant heat exchange rate.

[0049] However, since multi-split air conditioning systems only have one outdoor unit, in order to meet the cooling / heating capacity requirements, they generally need to operate at the maximum demand compressor frequency, which leads to over-output of the actual capacity of other terminals.

[0050] Table 1 shows an example of sensible heat and latent heat imbalance. As shown in Table 1, when judging the circulation system based on the dehumidification module and reheat module of air handling unit 4, the required evaporation capacity of the dehumidification module is 38.1 kW, and the required condensation capacity of the reheat module is 25.2 kW. The required evaporation capacity is greater than the required condensation capacity. When the compressor 101 is controlled at the required frequency of 84 Hz of the dehumidification module of air handling unit 4, the output capacity of the dehumidification module is 38.1 kW, and the output capacity of the reheat module is 46.6 kW. This will cause the output capacity of the reheat module to far exceed its required capacity, resulting in excessive deviation of process parameters.

[0051]

[0052] To address the issue of excessive output capacity of the reheat heat exchanger 402 (acting as a condenser) in the reheat module due to excessively high compressor output frequency, and to optimize the temperature control and dehumidification effect of the air handling unit 4, this application provides the following refrigeration heat exchange control logic. Similarly, considering the potential issue of excessively high output capacity of the dehumidification heat exchanger 401 (acting as an evaporator) when operating in heating mode, this application provides the following heating heat exchange control logic to resolve this problem. Specifically: refer to Figure 5 As shown, the controller is configured as follows: Determine whether the air handling unit 4 is a cooling unit or a heating unit (step S100). If the air handling unit 4 is the main cooling unit, the second four-way valve 104 is controlled based on the cooling heat exchange control logic to connect the outdoor heat exchanger 102 and the reheat heat exchanger 402, and the expansion valve of the outdoor heat exchanger 102 is controlled to be in a non-stop state. At this time, refrigerant can flow to the outdoor heat exchanger 102, and the outdoor heat exchanger 102 is used as a condenser for heat exchange; (step S200) If the air handling unit 4 is the main heating unit, the expansion valve of the outdoor heat exchanger 102 is controlled to be in a non-closed state based on the heating and heat exchange control logic, and the outdoor fan is controlled to run based on the preset speed, so that the outdoor heat exchanger 102 participates in heat exchange as an evaporator, transferring the heat exchange of the dehumidifying heat exchanger 401. The preset speed is a value greater than 0. (Step S300) Under the above heating and heat exchange control logic, the ports of the first four-way valve 103 and the second four-way valve 104 are kept connected. The second end C1 of the first four-way valve 103 is connected to the first end D1, and the third end E1 of the first four-way valve 103 is connected to the fourth end S1. The indoor water terminal 3 and the reheat heat exchanger 402 act as condensers, exchanging heat with the water medium and the dehumidified air medium respectively, thereby increasing the water temperature and air temperature. At this time, the refrigerant changes from a high-temperature and high-pressure gaseous refrigerant to a medium-temperature and medium-pressure liquid refrigerant through condensation and heat exchange.

[0053] Because under the heating and heat exchange control logic, the controller controls the expansion valve of the outdoor heat exchanger 102 to no longer be shut off. At this time, the dehumidifying heat exchanger 401 and the outdoor heat exchanger 102 act as evaporators. The medium-temperature and medium-pressure liquid refrigerant flows into the dehumidifying module through the low-pressure pipe and into the outdoor heat exchanger 102 through the liquid pipe.

[0054] The dehumidification heat exchanger 401 of the dehumidification module is used to absorb heat from the air through evaporation, and the outdoor heat exchanger 102 is used to absorb heat from the refrigerant through evaporation. The outdoor heat exchanger 102 is used to fully absorb heat as an evaporator by increasing the speed of the outdoor fan.

[0055] The heat exchange capacity of the outdoor heat exchanger 102 is controlled by adjusting the opening of the expansion valve and the speed of the outdoor fan, thereby effectively regulating its heat exchange capacity and achieving dynamic load adaptation.

[0056] Based on the above embodiments, the multi-split air conditioning system of this application can simultaneously connect cooling terminals and heating terminals. By adjusting the first four-way valve 103 and the second four-way valve 104, controlling the outdoor fan, and / or controlling the opening of the expansion valve of the outdoor heat exchanger 102, heat recovery can be achieved, thereby improving the energy efficiency of existing equipment.

[0057] By coordinating the operation of the four-way valve, expansion valve, and fan, the refrigerant path can be dynamically adjusted, meeting the needs for fine heat exchange control under different operating modes. When the air handling unit 4 is the main heating unit, the dual evaporation mechanism of the dehumidifying heat exchanger 401 and the outdoor heat exchanger 102 is used to reduce the heat exchange load of the dehumidifying heat exchanger 401, ensuring that the indoor air is not excessively dry. When the air handling unit 4 is the main cooling unit, the outdoor heat exchanger 102 is connected to the reheat heat exchange process as a condenser, effectively reducing the heat exchange load of the reheat heat exchanger 402, avoiding excessively high air temperature after being treated by the reheat heat exchanger 402, achieving fine air temperature control, and improving indoor comfort.

[0058] refer to Figure 3 As shown, in this embodiment of the application, the fifth terminal D2 and the sixth terminal C2 of the second four-way valve 104 are connected based on the refrigeration and heat exchange control logic, and the seventh terminal E2 and the eighth terminal S2 of the second four-way valve 104 are connected.

[0059] At this time, the high-temperature and high-pressure refrigerant discharged by the compressor 101 flows to the indoor water terminal 3, the reheat heat exchanger 402 of the air handling unit 4, and the outdoor heat exchanger 102 for condensation and heat exchange, transferring the heat exchange of the reheat module to the outdoor heat exchanger 102. The heat exchange burden of the reheat heat exchanger 402 is partially borne by the outdoor heat exchanger 102, which can significantly reduce its output load, avoid temperature control deviation caused by excessive reheat capacity of the air handling unit 4, improve the stability and accuracy of system operation, and use the outdoor heat exchanger 102 to restore the output capacity of the reheat module to the range of process parameter deviation.

[0060] The above-mentioned refrigeration and heat exchange control logic improves the stability and adjustment sensitivity of the reheat process, which helps the system maintain high comfort output under low load or fluctuating load conditions and improves the overall energy efficiency level.

[0061] To meet the evaporative heat exchange requirements, a portion of the condensation heat exchange is achieved through heat exchange with the atmosphere via the outdoor heat exchanger 102 and fan speed, thus enabling controllable reheating at the terminal. In this case, the heat exchange capacity of the outdoor heat exchanger 102 can be adjusted by regulating the expansion valve opening and fan speed.

[0062] Considering that the temperature and humidity of the air handling unit 4 can be controlled in a coordinated manner by controlling only the first four-way valve 103, the second four-way valve 104, the expansion valve of the outdoor heat exchanger 102 and the outdoor fan, the control accuracy is limited.

[0063] In the above embodiments, when the outdoor heat exchanger 102 acts as a condenser, it condenses the high-temperature, high-pressure gaseous refrigerant into a subcooled liquid; when the outdoor heat exchanger 102 acts as an evaporator, it absorbs heat from the environment. Subcooling refers to the difference between the refrigerant liquid temperature and its saturation temperature, which is usually formed at the condenser outlet; superheat refers to the difference between the refrigerant temperature at the compressor 101 suction port and its saturation temperature, which is usually formed at the evaporator outlet.

[0064] In existing technologies, there are solutions for controlling the outdoor heat exchanger 102 based on superheat and subcooling. However, this often leads to under- or over-adjustment of the outdoor heat exchanger 102's heat exchange capacity, resulting in inaccurate control of its heat exchange capacity and consequently, inaccurate control of the temperature and humidity of the air handling unit 4. Specifically, Research and experiments revealed that when the airflow configuration of air handling unit 4 is set to high fan speed, the capacity decreases by 11% and 84% respectively at a return air temperature of 27℃ and 19℃, respectively, at a superheat of 10K. At a return air temperature of 27℃, the capacity decreases by 11% and 32% respectively at high fan speed and silent mode, respectively, at a superheat of 10K. The experimental results show that the effect of superheat on sensible heat capacity is related to the fan speed and indoor temperature, and the normalized superheat is consistent with the trend of sensible heat change.

[0065] Conventional superheat control involves calculating the superheat SH= Obtaining real-time superheat and controlling it to the target superheat value does not quantify the actual output capacity of the heat exchanger, nor can it achieve precise control of the heat exchange. However, this embodiment of the application establishes a normalized superheat control instead of conventional superheat control, thereby achieving precise control of the heat exchange of the outdoor heat exchanger 102.

[0066] In some embodiments, reference Figure 6 As shown, the controller is also configured as follows: If air handling unit 4 is the main heating unit, the opening degree of the expansion valve is controlled to ensure the normalized real-time superheat. Approximate to or equal to the normalized target superheat (Step S301) Based on the above configuration, the controller of this application adjusts the opening of the expansion valve in real time through closed-loop control logic to accurately control the refrigerant flow, ensure that the refrigerant heat exchange meets the target heat exchange, and guarantee the stability of the air handling unit 4 when it is in heating mode.

[0067] In some embodiments, the controller is also configured to: Obtain the gas pipe temperature of outdoor heat exchanger 102 and liquid tube temperature Based on tracheal temperature and liquid tube temperature Determine the real-time superheat; According to the outdoor side return temperature of outdoor heat exchanger 102 and evaporation temperature The real-time superheat is normalized to obtain the normalized real-time superheat. .

[0068] Specifically, the normalized real-time superheat can be calculated based on the following calculation model: ,in, This is the air volume correction factor. The correction coefficients are obtained from product test results. Since the design of heat exchangers and fans at different terminals varies, which will affect the heat exchange capacity of the heat exchanger, the correction coefficients are different. By adding correction parameters, the applicability and robustness of the model are improved, so that it can cover different equipment types and operating conditions.

[0069] In the above embodiment, outdoor side temperature recovery It can be the return water temperature or return air temperature, or the air pipe temperature. Liquid tube temperature outdoor temperature recovery The temperature is detected by the temperature sensor of the air conditioning system.

[0070] In actual system operation, direct use of temperature difference control may result in nonlinear distortion. Based on the above-mentioned normalized real-time superheat calculation model, the normalized real-time superheat is used to accurately reflect the current operating status of the outdoor heat exchanger 102 as an evaporative heat exchanger; this can reduce the impact of environmental disturbances on control variables, making the controller output more stable and reliable.

[0071] In another embodiment, the gas and liquid temperature sensors can be selected from thermocouples, thermistors, or infrared sensors according to accuracy requirements, and are placed near the heat exchanger inlets to improve measurement accuracy.

[0072] In some embodiments, the controller is also configured to: The outdoor heat exchanger 102 is determined as the normalized heat transfer capacity of the evaporator. Normalized heat exchange Substituting into the normalized target superheat model, the normalized target superheat is calculated. .

[0073] In the above embodiments, the normalized target superheat model can be expressed as the following calculation model: ,in, To calculate the correlation coefficient, it is obtained through regression of historical data or product trial fitting and dynamically adjusted according to different product versions.

[0074] The above calculation model adopts a rational function structure, which can fit the dynamic trend of target subcooling with load change well. It has high versatility and adjustability and is suitable for various environments and operating conditions.

[0075] Based on the above configuration, this application embodiment estimates the current heat exchange demand as the operating intensity of the current system under actual load. The controller uses this value as the target control input to further drive the expansion valve to adjust the opening, thereby controlling the actual superheat to approach the target value and realizing the fine adjustment of the refrigerant supply on the evaporator side.

[0076] In the above configuration, the target superheat is automatically adjusted according to the actual operating load, avoiding performance fluctuations caused by fixed target values ​​in traditional control.

[0077] In some of these embodiments, the evaporation temperature The saturation temperature of the refrigerant is approximately obtained from the low-pressure saturation temperature obtained by the suction pressure sensor. The suction pressure sensor is set on the suction side of the compressor 101, and its suction pressure is used to approximate the evaporation pressure. The refrigerant saturation temperature corresponding to the evaporation pressure is used as the evaporation temperature.

[0078] In some embodiments, reference Figure 7 As shown, the controller is also configured as follows: Obtain the outdoor heat exchanger 102 as the maximum heat exchange capacity of the evaporator. and minimum heat exchange (Step S311), the specific value of which is obtained in advance through product testing; Based on maximum heat exchange and minimum heat exchange The difference determines the maximum evaporative heat transfer difference (step S312). Based on the required heat exchange capacity of outdoor heat exchanger 102 as an evaporator With minimum heat exchange The difference determines the difference in heat exchange demand for evaporation (step S313). The normalized heat transfer rate is determined by the quotient of the difference between the evaporation demand heat transfer rate and the difference between the maximum evaporation heat transfer rate. (Step S314).

[0079] In the above embodiments, normalized heat transfer This can be represented by the following computational model: ; The aforementioned required heat exchange can be calculated based on the inlet temperature, the required temperature, and the amount of refrigerant (such as air volume or water flow). Specifically, the required heat exchange is calculated based on the product of the difference between the required temperature and the inlet temperature and the amount of refrigerant.

[0080] The above normalized heat transfer The solution utilizes demand heat exchange. and maximum heat exchange Minimum heat exchange These parameters can effectively reflect the actual heat exchange ratio of the outdoor heat exchanger 102. By presetting the maximum / minimum heat exchange capacity, the model automatically reflects the capacity boundaries of different heat exchangers or models, using the difference between the maximum evaporative heat exchange capacity and the maximum evaporative heat exchange capacity as the upper and lower limits for normalized calculations. This model can adaptively adjust the control intensity according to the equipment characteristics, avoiding control deviations caused by uniform target settings.

[0081] The above normalized heat transfer Used to obtain the normalized target superheat It effectively connects the quantitative channel between heat load regulation requirements and expansion valve control objectives, improving the response consistency and logical clarity of the control closed loop.

[0082] Based on the above control logic, the controller uses the calculated normalized heat transfer rate... The normalized target superheat was calculated. The opening of the expansion valve is dynamically adjusted through a closed-loop control algorithm to achieve normalized real-time superheat. Approximate to or equal to the normalized target superheat This allows for precise control of evaporation pressure and refrigerant flow, enabling accurate adjustment of the expansion valve of the outdoor heat exchanger 102, preventing overheating deviations, and effectively improving temperature control accuracy. By introducing airflow correction, model correction parameters, and polynomial fitting expression, the above model possesses good versatility and scalability, and can be widely applied to heat exchange systems of different models and configurations.

[0083] Similar to the above embodiments, when the outdoor heat exchanger 102 acts as a condenser, conventional single subcooling control is insufficient to characterize the heat exchange capacity between terminals. Due to differences in heat exchange temperature difference and heat transfer efficiency at different terminals, the heat exchange capacity varies greatly under a single subcooling target control. Therefore, this embodiment of the application establishes normalized subcooling control instead of conventional subcooling control to achieve precise control of the heat exchange capacity of the outdoor heat exchanger 102.

[0084] In some embodiments, reference Figure 8 As shown, the controller is also configured as follows: If air handling unit 4 is the main refrigeration unit, the opening of the expansion valve is controlled to ensure the normalized real-time subcooling degree. Approximate to or equal to the normalized target supercooling (Step S201) Based on the above configuration, the opening of the expansion valve is adjusted in real time through closed-loop control logic, thereby regulating the refrigerant flow into the outdoor heat exchanger 102 and optimizing the subcooling control accuracy and system operating efficiency. This control strategy ensures that the refrigerant at the outlet of the condenser (here, the outdoor heat exchanger 102) is maintained within the ideal subcooling range, improving heat exchange efficiency and system stability.

[0085] In some embodiments, the controller is also configured to: Obtain the saturation temperature corresponding to the high pressure of the outdoor heat exchanger 102. and liquid tube temperature Based on saturation temperature and liquid tube temperature The real-time subcooling degree is determined, and the high-pressure is obtained based on the detection of a pressure sensor. According to the outdoor side return temperature of outdoor heat exchanger 102 Normalize the real-time superheat to obtain the normalized real-time subcooling. .

[0086] Specifically, the normalized real-time subcooling can be calculated based on the following calculation model: ,in, This is the air volume correction factor. These are model correction factors, obtained from product testing results. Due to differences in the design of heat exchangers and fans at different terminals, the heat exchange capacity of the heat exchanger will be affected, hence the different correction factors.

[0087] In the above embodiment, outdoor side temperature recovery It can be the return water temperature or the return air temperature, and the outdoor side return temperature. Liquid tube temperature The temperature is detected by the temperature sensor of the air conditioning system.

[0088] Based on the above configuration, the controller in this application accurately assesses the subcooling level of the refrigerant by monitoring the operating status of the high-pressure side in real time. The controller obtains the corresponding refrigerant saturation temperature by looking up a table or calling the built-in thermodynamic model based on the pressure value. Simultaneously, the system also obtains the actual temperature of the refrigerant at the liquid line location via a temperature sensor. The temperature difference between these two values ​​represents the current real-time subcooling.

[0089] To eliminate interference from different external environments, the outdoor return air temperature parameter is further introduced to normalize the real-time subcooling value, generating a standardized normalized real-time subcooling value. This is used for control judgments and system performance evaluation under various environmental conditions. This mechanism provides a data foundation for subsequent precise control of the expansion valve and system energy-saving strategies.

[0090] In some embodiments, the controller is also configured to: The outdoor heat exchanger 102 is determined as the normalized heat transfer capacity of the condenser. Normalized heat exchange Substituting into the normalized target supercooling model, the normalized target supercooling is calculated. .

[0091] In the above embodiments, the normalized target supercooling model can be expressed as the following calculation model: ,in, The correlation coefficient is obtained by regression of historical data or product test fitting, and is used to reflect the nonlinear relationship between heat exchange load and target subcooling.

[0092] The above calculation model adopts a rational function structure, which can fit the dynamic trend of target subcooling with load change well. It has high versatility and adjustability and is suitable for various environments and operating conditions.

[0093] Based on the above configuration, this embodiment estimates the current heat exchange demand as the operating intensity of the current system under actual load. The controller uses this value as the target control input to further drive the expansion valve to adjust the opening, thereby controlling the actual subcooling to approach the target value and realizing fine adjustment of the refrigerant supply on the condenser side.

[0094] Based on the above embodiments, experiments have shown that under normalized subcooling control, the heating capacity deviation in different scenarios is small, and the correlation with the ability to operate in multi-temperature difference scenarios is stronger. The normalized subcooling of this application can better characterize the change law of the capacity.

[0095] In some embodiments, reference Figure 9 As shown, the controller is also configured as follows: Obtain the outdoor heat exchanger 102 as the maximum heat exchange capacity of the condenser. and minimum heat exchange The specific value is obtained in advance through product testing; Based on maximum heat exchange and minimum heat exchange The difference determines the maximum condensation heat transfer difference; Based on the required heat exchange capacity of outdoor heat exchanger 102 as a condenser With minimum heat exchange The difference determines the difference in heat exchange required for condensation; The normalized heat transfer rate is determined by the quotient of the difference between the condensation demand heat transfer rate and the maximum condensation heat transfer rate. .

[0096] In the above embodiments, normalized heat transfer This can be represented by the following computational model: .

[0097] In some embodiments, during the product design or commissioning phase, the system obtains the maximum heat transfer capacity of the outdoor heat exchanger 102 when operating as a condenser using test data under standard operating conditions. and minimum heat exchange And it is stored in the controller.

[0098] Based on the above configuration, this application adopts the maximum heat exchange obtained from preliminary experiments. and minimum heat exchange As a benchmark, by calculating the normalized heat transfer using the difference ratio method, the system can accurately reflect the heat transfer capacity requirement of the current operating state relative to the design limit state, thereby improving the accuracy of the target subcooling calculation and the rationality of the control response.

[0099] In summary, the air conditioning system of this application embodiment can achieve heat recovery when high-precision temperature and humidity control is not required; when higher-precision temperature and humidity control is required, heat transfer can be achieved simply by identifying the main cooling and heating components and switching different four-way valves and controlling the expansion valve of the outdoor heat exchanger 102, thus achieving basic temperature and humidity control. By calculating the actual required cooling and heating capacity, the normalized target subcooling and superheating are obtained, and the expansion valve is adjusted so that the heat exchanger output capacity is approximately equal to the target demand capacity, thereby achieving precise temperature and humidity control through the regulation of heat exchange.

[0100] It should be noted that the above modules can be functional modules or program modules, and can be implemented through software or hardware. For modules implemented through hardware, the above modules can reside in the same processor; or the above modules can be located in different processors in any combination.

[0101] in addition, Figure 10 This is a schematic diagram of the hardware structure of the controller according to an embodiment of this application.

[0102] The controller may include a processor 501 and a memory 502 storing computer program instructions.

[0103] Specifically, the processor 501 may include a central processing unit (CPU), an application specific integrated circuit (ASIC), or one or more integrated circuits that can be configured to implement the embodiments of this application.

[0104] Memory 502 may include a large-capacity memory for data or instructions. For example, and not limitingly, memory 502 may include a hard disk drive (HDD), a floppy disk drive, a solid-state drive (SSD), flash memory, an optical disk drive, a magneto-optical disk drive, magnetic tape, or a Universal Serial Bus (USB) drive, or a combination of two or more of these. Where appropriate, memory 502 may include removable or non-removable (or fixed) media. Where appropriate, memory 502 may be internal or external to a data processing device. In a particular embodiment, memory 502 is non-volatile memory. In a particular embodiment, memory 502 includes read-only memory (ROM) and random access memory (RAM). Where appropriate, the ROM may be a mask-programmed ROM, a programmable read-only memory (PROM), an erasable read-only memory (EPROM), an electrically erasable read-only memory (EEPROM), an electrically alterable read-only memory (EAROM), or flash memory, or a combination of two or more of these. Where appropriate, the RAM can be Static Random-Access Memory (SRAM) or Dynamic Random-Access Memory (DRAM). DRAM can be Fast Page Mode Dynamic Random Access Memory (FPMDRAM), Extended Data Out Dynamic Random Access Memory (EDODRAM), Synchronous Dynamic Random-Access Memory (SDRAM), etc.

[0105] The memory 502 can be used to store or cache various data files that need to be processed and / or communicated, as well as possible computer program instructions executed by the processor 501.

[0106] The processor 501 reads and executes computer program instructions stored in the memory 502 to implement the built-in arithmetic operations of the controller in the above embodiment.

[0107] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0108] For ease of explanation, the above description has been provided in conjunction with specific embodiments. However, the above exemplary discussion is not intended to be exhaustive or to limit the embodiments to the specific forms disclosed above. Various modifications and variations can be obtained based on the above teachings. The selection and description of the above embodiments are for the purpose of better explaining the principles and practical applications, thereby enabling those skilled in the art to better utilize the embodiments and various different variations of the embodiments suitable for specific application considerations.

Claims

1. A multi-split air conditioning system, characterized in that, include: The outdoor unit has a compressor, an outdoor heat exchanger, a first four-way valve, and a second four-way valve. The first end of the first four-way valve is connected to the exhaust side of the compressor. The fifth end of the second four-way valve is connected to the first end of the first four-way valve and to the seventh end of the second four-way valve. The sixth end of the second four-way valve is connected to the outdoor heat exchanger and to the eighth end of the second four-way valve. Indoor unit, which has an indoor heat exchanger; The indoor water terminal is connected to the compressor via a high-pressure pipeline and to the outdoor heat exchanger via a liquid pipeline. The expansion valve of the outdoor heat exchanger is in the closed state. An air handling unit includes a dehumidifying heat exchanger and a reheat heat exchanger, wherein the first end of the dehumidifying heat exchanger and the first end of the reheat heat exchanger are connected to the liquid pipes of the indoor water terminal. The second end of the dehumidifying heat exchanger is connected to the suction side of the compressor, the fourth end of the first four-way valve, and the eighth end of the second four-way valve via a low-pressure pipeline. The third end of the first four-way valve is connected to the fourth end. The second end of the reheat heat exchanger is connected to the second end of the first four-way valve through a high-low pressure switching pipeline, and the second end of the first four-way valve is connected to the first end. The controller is configured as follows: Determine whether the air handling unit is the main cooling or heating unit; If the air handling unit is the main cooling unit, the second four-way valve is controlled based on the cooling heat exchange control logic to connect the outdoor heat exchanger and the reheat heat exchanger, and the expansion valve of the outdoor heat exchanger is controlled to be in a non-stop state. If the air handling unit is the main heating unit, the expansion valve of the outdoor heat exchanger is controlled to be in a non-stop state based on the heating and heat exchange control logic, and the outdoor fan is controlled to operate based on the preset speed.

2. The multi-split air conditioning system according to claim 1, characterized in that, Based on the refrigeration and heat exchange control logic, the fifth and sixth terminals of the second four-way valve are connected, and the seventh and eighth terminals of the second four-way valve are connected.

3. The multi-split air conditioning system according to claim 2, characterized in that, The controller is also configured to: If the air handling unit is the main heating component, the opening degree of the expansion valve is controlled to adjust the normalized real-time superheat. Approximate to or equal to the normalized target superheat .

4. The multi-split air conditioning system according to claim 3, characterized in that, The controller is also configured to: Obtain the gas pipe temperature of the outdoor heat exchanger and liquid tube temperature Based on tracheal temperature and liquid tube temperature Determine the real-time superheat; According to the outdoor side return temperature of the outdoor heat exchanger and evaporation temperature The real-time superheat is normalized to obtain the normalized real-time superheat. .

5. The multi-split air conditioning system according to claim 3, characterized in that, The controller is also configured to: The outdoor heat exchanger is determined as the normalized heat transfer capacity of the evaporator. The normalized heat transfer Substituting into the normalized target superheat model, the normalized target superheat is calculated. .

6. The multi-split air conditioning system according to claim 5, characterized in that, The controller is also configured to: Obtain the maximum heat exchange capacity of the outdoor heat exchanger as the evaporator. and minimum heat exchange ; Based on the maximum heat exchange and minimum heat exchange The difference determines the maximum evaporative heat transfer difference; Based on the required heat exchange capacity of the outdoor heat exchanger as an evaporator With the minimum heat exchange The difference determines the difference in heat exchange required for evaporation; The normalized heat transfer is determined based on the quotient of the difference between the evaporation demand heat transfer value and the difference between the maximum evaporation heat transfer value. .

7. The multi-split air conditioning system according to any one of claims 1 to 6, characterized in that, The controller is also configured to: If the air handling unit is the main refrigeration unit, the opening degree of the expansion valve is controlled to ensure the normalized real-time subcooling degree. Approximate to or equal to the normalized target supercooling .

8. The multi-split air conditioning system according to claim 6, characterized in that, The controller is also configured to: Obtain the saturation temperature corresponding to the high pressure of the outdoor heat exchanger. and liquid tube temperature Based on saturation temperature and liquid tube temperature Determine the real-time subcooling; According to the outdoor side return temperature of the outdoor heat exchanger The real-time superheat is normalized to obtain the normalized real-time undercooling. .

9. The multi-split air conditioning system according to claim 6, characterized in that, The controller is also configured to: The outdoor heat exchanger is determined to have normalized heat transfer capacity as a condenser. The normalized heat transfer Substituting into the normalized target supercooling model, the normalized target supercooling is calculated. .

10. The multi-split air conditioning system according to claim 9, characterized in that, The controller is also configured to: Obtain the maximum heat transfer capacity of the outdoor heat exchanger as the condenser. and minimum heat exchange ; Based on the maximum heat exchange and minimum heat exchange The difference determines the maximum condensation heat transfer difference; Based on the required heat exchange capacity of the outdoor heat exchanger as a condenser With the minimum heat exchange The difference determines the difference in heat exchange required for condensation; The normalized heat transfer is determined based on the quotient of the difference between the required heat transfer and the maximum difference in condensation heat transfer. .

Images