Energy-saving control method of multifunctional heat pump heat recovery unit

Abstract

The application discloses an energy-saving control method of a multifunctional heat pump heat recovery unit and belongs to the technical field of heat pump system control. In view of the fact that existing heat pump units cannot intelligently switch cold and heat source modes according to environmental conditions and user load demands, resulting in low operation energy efficiency and the problem that heat recovery cannot be effectively utilized. The method is based on the structure of the unit, and the temperature sensor arranged on each heat exchanger is used to detect the environmental temperature, the preset environmental set temperature and a plurality of water temperature parameters in real time; the controller determines the target operation mode according to the comparison between the absolute value of the environmental temperature difference and the first preset deviation value. The method realizes intelligent switching of the environmental heat source and the geothermal heat source, optimizes the system energy efficiency, and is mainly used for improving the comprehensive energy utilization efficiency in the processes of domestic hot water preparation and air conditioning refrigeration and heating.

Description

Technical Field

[0001] This invention relates to the field of heat pump system control technology. More specifically, this invention relates to an energy-saving control method for a multifunctional heat pump heat recovery unit. Background Technology

[0002] In the practical application of multifunctional heat pump heat recovery systems, several key technical challenges exist in effectively improving their annual operating energy efficiency and functional synergy.

[0003] The first challenge lies in the adaptive selection of heat source / cooling source modes. Such systems typically possess the ability to utilize both ambient air (air-cooled) and relatively stable underground or water bodies (ground-source). However, existing systems often struggle to intelligently select the most suitable heat source / cooling source mode based on real-time, changing ambient temperature conditions. Specifically, when ambient temperatures are low (e.g., near or below freezing), continuing to rely primarily on air-cooling presents significant problems—the heating efficiency of the air-source heat pump drops drastically, and the evaporator surface is prone to frost buildup. This not only leads to insufficient heating capacity and a sharp increase in energy consumption, but frequent defrosting processes also interrupt heating, affecting user comfort and increasing additional energy consumption. On the other hand, during periods of milder or higher ambient temperatures, while ground-source systems offer high and stable energy efficiency, their construction and operating costs are generally higher than those of air-cooled systems. If air-cooling is not effectively utilized in these situations, and excessive reliance on ground-source systems is employed, it results in uneconomical resource utilization. Achieving this intelligent and efficient switching between hot and cold source modes presents challenges. The core issue lies in the need for a control logic that can accurately sense the ambient temperature, reliably determine which hot or cold source mode is better, and safely and smoothly execute mode switching. This would avoid the inefficiency and frost formation of air cooling at low temperatures, as well as the redundant use of ground-based cooling at suitable temperatures.

[0004] The second challenge involves clearly defining and establishing a collaborative foundation for the functions of multiple heat exchangers. Multifunctional heat pump heat recovery systems integrate multiple functions, including domestic hot water preparation, air conditioning / cooling / heating, and environmental heat exchange, typically achieved through multiple heat exchangers. However, existing systems often lack a clear definition of the core functions of these heat exchangers or fail to clearly delineate them at the system design level. This can lead to a lack of clear physical and logical boundaries between heat exchangers relied upon for different functions (such as domestic hot water recovery and user space cooling / heating) during system operation, easily resulting in mutual interference. For example, if the functional positioning of heat exchangers used to recover compressor exhaust heat, heat exchangers used to connect to geothermal sources, heat exchangers serving user end loads, and heat exchangers used for conventional air-cooled heat exchange is ambiguous or overlapping, it can complicate refrigerant flow path design and control strategies when the system attempts to simultaneously meet multiple needs (such as both hot water production and cooling), making it prone to conflicts and hindering efficient independent operation or orderly collaboration of each function. Establishing a clear physical foundation for efficient multi-mode collaborative operation requires clearly defining the main responsibilities and roles of each heat exchanger within the system.

[0005] The third challenge focuses on the dynamic coordination of various user demands under air-cooled heat source mode. When the system mainly operates in air-cooled mode, it needs to simultaneously handle potential and changing domestic hot water preparation needs and user space cooling or heating needs. Existing systems, under air-cooled conditions, often struggle to manage these demands in real-time and dynamically based on the actual state of domestic hot water temperature (e.g., whether it meets the set requirements) and the actual state of user-side water temperature (e.g., whether it meets the cooling or heating set requirements). Common problems include: when the domestic hot water temperature already meets the requirements, the system may still be performing unnecessary heat recovery processes, leading to additional pump energy consumption and potential losses in main function efficiency; conversely, when the domestic hot water temperature is insufficient and heating is required, the system may fail to effectively utilize recoverable waste heat (e.g., compressor exhaust heat), especially when the system also needs to provide cooling services to the user side (where condensation heat is sufficient), resulting in energy waste. A more complex situation arises when both domestic hot water demand and user-side cooling / heating demand are unmet. The challenge lies in efficiently integrating the heat recovery process into the main cooling or heating cycle to avoid conflicts in resource allocation (such as refrigerant flow and heat exchanger capacity). For example, excessive refrigerant heat consumption during heat recovery could lead to insufficient heating on the user side, or condensation heat dissipation demand (during cooling) could compete with hot water heating demand for refrigerant heat. The difficulty in achieving this dynamic coordination of multiple demands in air-cooled mode lies in the need for real-time monitoring of multiple key temperature points (domestic hot water temperature, user-side water temperature) to accurately determine the demand status (meeting or not meeting standards). Based on this, control logic must be designed to determine whether to activate heat recovery and how to integrate it into the main cycle, thereby achieving optimal energy efficiency and conflict-free operation. Summary of the Invention

[0006] One objective of this invention is to provide an energy-saving control method for a multifunctional heat pump heat recovery unit, which realizes intelligent switching between environmental heat sources and geothermal sources, optimizes system energy efficiency, and improves the comprehensive energy utilization efficiency in the process of domestic hot water preparation and air conditioning cooling and heating.

[0007] To achieve these objectives and other advantages of the present invention, according to one aspect of the present invention, an energy-saving control method for a multifunctional heat pump heat recovery unit is provided. The unit includes a liquid receiver, a compressor, a four-way valve, a first heat exchanger, a second heat exchanger, a third heat exchanger, a fourth heat exchanger, and a controller; wherein the liquid receiver, the compressor, and the first heat exchanger are sequentially connected; the outlet of the first heat exchanger is connected to port A 200 of the four-way valve; port B 201 of the four-way valve is sequentially connected to the fourth, second, and third heat exchangers; the outlet of the third heat exchanger is connected to port C 202 of the four-way valve; and port D of the four-way valve is connected to the fourth heat exchanger, the second heat exchanger, and the third heat exchanger. 203 is connected to the inlet of the liquid storage tank; the fourth heat exchanger, the second heat exchanger, and the first heat exchanger are respectively connected in parallel with a first control valve, a second control valve, and a third control valve, and an expansion valve is connected between the second heat exchanger and the third heat exchanger; the unit is equipped with multiple temperature sensors connected to the controller to detect the outlet water temperature and return water temperature of the first heat exchanger, the second heat exchanger, and the third heat exchanger, the ambient air outlet temperature of the fourth heat exchanger, and the current ambient temperature;

[0008] The controller determines the target operating mode based on the change between the received real-time temperature detection value and the preset target temperature setpoint, combined with the user's set requirements. Then, according to the preset refrigerant flow direction of the target operating mode, it controls the corresponding heat exchanger and control valve to operate or shut down. Specifically:

[0009] When T4≥T S4 When +S1 is activated, the target operating mode of the user demand side is determined to be the air-cooled heating mode. The controller then activates the fan of the fourth heat exchanger, shuts down the water pump of the second heat exchanger, closes the first control valve, and opens the second control valve.

[0010] When T4 < T S4 When -S1 is reached, the target operating mode of the user demand side is determined to be the ground source heat pump heating mode. The controller controls the water pump of the second heat exchanger to start, the fan of the fourth heat exchanger to stop, and the first control valve to start and the second control valve to stop.

[0011] When T4 < T X4 -S1 indicates that the target operating mode of the user demand side is the air-cooled operation mode. The controller controls the fan of the fourth heat exchanger to start, the water pump of the second heat exchanger to stop, and the first control valve to be closed and the second control valve to be opened.

[0012] When T4≥TX4 When +S1 is activated, the target operating mode of the user demand side is determined to be the ground source heat pump cooling mode. The controller then activates the water pump of the second heat exchanger, shuts down the fan of the fourth heat exchanger, and activates the first control valve while closing the second control valve.

[0013] Where T4 is the current ambient temperature; T S4 Set the temperature for the preset winter environment; T X4 Set the temperature for the preset summer environment; S1 is the first preset deviation value.

[0014] Preferably, the first heat exchanger is a domestic hot water heat exchanger used for heating domestic hot water and recovering heat from the compressor exhaust; the second heat exchanger is a ground source heat pump heat exchanger used to replace air-cooled heat exchange under low-temperature conditions and prevent frost formation; the third heat exchanger is a user-side cooling / heating heat exchanger used to provide cooling or heating services to users; and the fourth heat exchanger is an air-cooled environmental heat exchanger used to exchange heat with air under normal operating conditions and provide environmental heat and cold sources.

[0015] Preferably, the target operating mode further includes:

[0016] The controller is based on the domestic hot water outlet temperature T of the first heat exchanger. 1H The user-side outlet water temperature T of the third heat exchanger 3H Preset target hot water temperature T R and the user-side water outlet set temperature T 3S Perform the following operations:

[0017] When T4 < T X4 -S1,T 1H ≥T R -S2 and T 3H ≥T 3S -S3, the target operating mode of the user demand side is determined to be air-cooled pure refrigeration mode. The controller controls the opening of the third and fourth heat exchangers, the closing of the first and second heat exchangers, the opening of the second and third control valves, and the closing of the first control valve, so that the refrigerant flows out of the compressor, flows through the fourth and third heat exchangers in sequence, and flows back to the liquid receiver.

[0018] When T4≥T S4 +S1,T 1H ≥T R -S2 and T 3H <T 3S -S3, the target operating mode of the user demand side is determined to be air-cooled pure heating mode. The controller controls the opening of the third and fourth heat exchangers, the closing of the first and second heat exchangers, the opening of the second and third control valves, and the closing of the first control valve, so that the refrigerant flows out of the compressor, flows through the third and fourth heat exchangers in sequence, and flows back to the liquid receiver.

[0019] When T4 < T X4 -S1,T 1H <T R -S2 and T 3H ≥T 3S -S3 indicates that the target operating mode of the user demand side is determined to be air-cooled cooling and domestic hot water mode. The controller controls the opening of the first heat exchanger, the third heat exchanger and the fourth heat exchanger, the closing of the second heat exchanger, the closing of the first control valve and the third control valve, and the opening of the second control valve, so that the refrigerant flows out of the compressor, flows through the first heat exchanger, the fourth heat exchanger and the third heat exchanger in sequence, and flows back to the liquid receiver.

[0020] When T4≥T S4 +S1,T 1H <T R -S2 and T 3H <T 3S -S3, the target operating mode of the user demand side is determined to be the air-cooled heating domestic hot water mode. The controller controls the opening of the first heat exchanger, the third heat exchanger and the fourth heat exchanger, the closing of the second heat exchanger, the closing of the first control valve and the third control valve, and the opening of the second control valve, so that the refrigerant flows out of the compressor, flows through the first heat exchanger, the third heat exchanger and the fourth heat exchanger in sequence and flows back to the liquid receiver.

[0021] Where S2 is the second preset deviation value, S3 is the third preset deviation value, and T 3S Automatically selects the set temperature based on the current operating mode: T in cooling mode 3S =T 3Sx In heating mode T 3S =T 3Sd .

[0022] Preferably, the target operating mode further includes:

[0023] When T4≥T X4 +S1,T 1H ≥T R -S2 and T 3H ≥T 3S -S3 indicates that the target operating mode of the user demand side is the ground source heat pump pure cooling mode. The controller controls the opening of the second and third heat exchangers, the closing of the first and fourth heat exchangers, the opening of the first and third control valves, and the closing of the second control valve, so that the refrigerant flows out of the compressor, flows through the second and third heat exchangers in sequence, and flows back to the liquid receiver.

[0024] When T4 < T S4 -S1,T 1H ≥T R -S2 and T 3H <T 3S-S3 indicates that the target operating mode of the user demand side is the ground source heat pump pure heating mode. The controller controls the opening of the second and third heat exchangers, the closing of the first and fourth heat exchangers, the opening of the first and third control valves, and the closing of the second control valve, so that the refrigerant flows out of the compressor, flows through the third heat exchanger and the second heat exchanger in sequence, and flows back to the liquid receiver.

[0025] When T4 < T X4 -S1,T 1H <T R -S2 and T 3H ≥T 3S When -S3 is reached, the target operating mode of the user demand side is determined to be the ground source heat pump cooling and domestic hot water mode. The controller controls the opening of the first heat exchanger, the second heat exchanger and the third heat exchanger, and the closing of the fourth heat exchanger. The first control valve is opened, and the second control valve and the third control valve are closed, so that the refrigerant flows out of the compressor, flows through the first heat exchanger, the second heat exchanger and the third heat exchanger in sequence, and flows back to the liquid receiver.

[0026] When T4 < T S4 -S1,T 1H <T R -S2 and T 3H <T 3S When -S3 is activated, the target operating mode of the user demand side is determined to be the ground source heat pump heating and domestic hot water mode. The controller controls the opening of the first heat exchanger, the second heat exchanger, and the third heat exchanger, and the closing of the fourth heat exchanger. The first control valve is opened, and the second control valve and the third control valve are closed, so that the refrigerant flows out of the compressor, flows through the first heat exchanger, the third heat exchanger, and the second heat exchanger in sequence, and flows back to the liquid receiver.

[0027] Preferably, the method for determining the first preset deviation value S1, the second preset deviation value S2, and the third preset deviation value S3 is as follows:

[0028] Collect ambient temperature data for N consecutive days and calculate the maximum daily temperature difference ΔT. max =max(T4)-min(T4), take ΔT max The initial value of S1 is obtained by multiplying the average value of N by the coefficient C1, where 5 ≤ N ≤ 10 and 0.2 ≤ C1 ≤ 0.3.

[0029] Under standard operating conditions, running in both cooling and heating modes, record: the range of domestic hot water temperature fluctuation ΔT2 = max(T) 1H )-min(T 1H The user-side water temperature fluctuation range ΔT3 = max(T) 3H )-min(T 3H Let the initial value of S2 be C2×ΔT2, and the initial value of S3 be C3×ΔT3, where 0.6≤C2≤0.9 and 0.6≤C3≤0.9;

[0030] The controller stores and records the initial values ​​of the first preset deviation value S1, the second preset deviation value S2, and the third preset deviation value S3.

[0031] Preferably, the controller dynamically adjusts the values ​​of S1, S2, and S3 based on the intensity of ambient temperature fluctuations and load conflict.

[0032] The absolute value of the rate of change of ambient temperature is calculated in real time as δ=︱ΔT4 / Δt︱, and the first preset deviation value S1 is updated to S1'=S1× (1+γ×δ);

[0033] Real-time calculation of load coupling factor α=|T R -T 3S | When α > β: S2' = k×S2, S3' = k×S3; When α ≤ β: S2' = m×S2, S3' = m×S3;

[0034] Wherein, γ is the preset environmental change sensitivity, with a value range of 0.05~0.2; β is the preset cold and heat load conflict threshold, with a value range of 20~30℃; k and m are preset coefficients, with k taking a value of 0.8 and m taking a value of 1.2.

[0035] Preferably, the initial opening degree of the expansion valve is dynamically set according to the target operating mode:

[0036] For air-cooled pure cooling mode and ground source heat pump pure cooling mode: θ0 = 30% + 0.4 × (T4 - 35)%, and the opening degree is limited to 25%-45%;

[0037] For air-cooled pure heating mode and ground source heat pump pure heating mode: θ0 = 40% + 0.6 × (0 - T4)%, with the opening degree limited to 35%-55%;

[0038] For air-cooled domestic hot water mode, air-cooled domestic hot water mode, ground-source heat pump cooling domestic hot water mode, and ground-source heat pump heating domestic hot water mode: θ0 = 35% + 0.3 × |T R -T 3S |%, the opening is limited to 30%-50%.

[0039] Preferably, the opening control of the expansion valve employs a two-parameter feedback mechanism:

[0040] Real-time monitoring of the outlet temperature T of the second heat exchanger 2H and the inlet pressure P of the third heat exchanger;

[0041] When T 2H >T set When + ΔT1, reduce the initial opening of the expansion valve by 5%-15%;

[0042] When T 2H <T set When -ΔT1, increase the initial opening of the expansion valve by 5%-15%;

[0043] When P > P set When +ΔP, increase the initial opening of the expansion valve by 5%-15%;

[0044] When P < P set When -ΔP, reduce the initial opening of the expansion valve by 5%-15%;

[0045] Among them, T set Set the outlet temperature of the second heat exchanger to meet the condition 5℃≤T set ≤45℃; ΔT1 is the temperature dead zone threshold, satisfying 0.5℃≤ΔT1≤2.0℃; P set Set the inlet pressure for the third heat exchanger to meet the requirement of 0.5 MPa ≤ P set ≤4.0MPa; ΔP is the pressure dead zone threshold, which satisfies 0.05MPa≤ΔP≤0.2MPa.

[0046] Preferably, the controller generates an opening adjustment command by combining temperature deviation and pressure deviation according to a preset weight ratio;

[0047] Define the basic weight calculation function: α base = 0.5 + 0.01 × |T R -T 3S |;

[0048] Perform weighted amplitude limiting: if α base If α < 0.5, then α = 0.5; if α base If the α value is greater than 0.8, then α = 0.8; otherwise, α = α. base ;

[0049] Pressure weight β = 1 - α;

[0050] When the inlet pressure of the third heat exchanger P > P set When +0.5×ΔP, β=0.8 and α=0.2 are forcibly set.

[0051] This invention offers at least the following beneficial effects: By monitoring the ambient temperature in real time and comparing it with a preset ambient temperature, the invention intelligently determines and automatically switches between air-cooled operation mode and ground-source heat pump operation mode. This effectively solves the problem of poor environmental adaptability: when the ambient temperature is suitable, air source heat exchange is prioritized, reducing dependence on the ground-source system; when the ambient temperature is too low, it automatically switches to the more stable and efficient ground-source heat exchange mode, significantly reducing the risk of energy efficiency degradation and frosting in air-cooled mode at low temperatures, thereby improving the overall energy efficiency throughout the year. The method clearly defines the functional roles of each heat exchanger, providing a clear physical basis for the system to simultaneously handle multiple tasks such as domestic hot water heating, user-side cooling and heating, and environmental heat exchange. Furthermore, the method deeply integrates the real-time status of the actual and target temperatures of domestic hot water, and the user-side water temperature and the set temperature, finely distinguishing various operating sub-modes (such as pure cooling, pure heating, cooling and hot water production simultaneously, heating and hot water production simultaneously, etc.). By precisely controlling the opening and closing of multiple bypass valves, the refrigerant flow can be accurately guided: when domestic hot water demand is met, relevant bypasses are closed in a timely manner to avoid unnecessary heat recovery energy consumption; when user-side load meets the standard, the main function operation is prioritized; and when both domestic hot water and user-side load require replenishment, the heat recovery heat exchanger is intelligently connected in series with the main circulation to efficiently utilize compressor exhaust heat, completely resolving potential conflicts between the heat recovery function and the main cooling / heating function. This method also dynamically sets and optimizes key temperature difference judgment thresholds based on historical environmental data and actual system performance, making them more suitable for specific regional climates and unit characteristics, avoiding mode misjudgments or response delays caused by fixed thresholds. Simultaneously, the system can sense rapid changes in ambient temperature and the potential conflict intensity between domestic hot water demand and air conditioning load, dynamically fine-tuning relevant thresholds accordingly, enhancing the system's adaptability to sudden changes, effectively mitigating control fluctuations during load conflicts, and improving operational stability. For different operating modes, the initial opening of the expansion valve is preset within a reasonable range, providing an optimal refrigerant flow starting point for various operating conditions and accelerating system adjustment speed. During operation, the opening degree of the expansion valve is also regulated by a dual closed-loop feedback mechanism of the ground source side outlet temperature and the user side inlet pressure, ensuring both ground source heat exchange efficiency and compressor operational safety. The system uses intelligent algorithms to comprehensively prioritize temperature and pressure parameters, emphasizing pressure protection when high-pressure risks are detected, thus achieving a dynamic balance between system energy efficiency and operational safety. In summary, this method, through intelligent environmental sensing, multi-demand collaborative decision-making, dynamic parameter optimization, and precise actuator control, significantly improves the energy utilization efficiency and overall operational reliability of heat pump systems under complex and variable operating conditions.

[0052] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0053] Figure 1 This is a schematic diagram of the structure of the unit described in one technical solution of the present invention.

[0054] Figure 2 This is a schematic diagram of the operation of the air-cooled pure refrigeration mode in Embodiment 1 of the present invention.

[0055] Figure 3 This is a schematic diagram of the operation of the air-cooled pure heating mode in Embodiment 2 of the present invention.

[0056] Figure 4 This is a schematic diagram of the operation of the air-cooled domestic hot water mode in Embodiment 3 of the present invention.

[0057] Figure 5 This is a schematic diagram of the operation of the air-cooled heating domestic hot water mode in Embodiment 4 of the present invention.

[0058] Figure 6 This is a schematic diagram of the operation of the ground source pure cooling mode in Embodiment 5 of the present invention.

[0059] Figure 7 This is a schematic diagram of the operation of the ground-source pure heating mode in Embodiment 6 of the present invention.

[0060] Figure 8 This is a schematic diagram of the operation of the ground source cooling domestic hot water mode in Embodiment 7 of the present invention.

[0061] Figure 9 This is a schematic diagram of the operation of the ground source heating domestic hot water mode in Embodiment 8 of the present invention. Detailed Implementation

[0062] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can implement it based on the description.

[0063] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0064] like Figure 1As shown, this invention provides an energy-saving control method for a multifunctional heat pump heat recovery unit. The unit includes a liquid receiver 100, a compressor 101, a four-way valve 102, a first heat exchanger 103, a second heat exchanger 104, a third heat exchanger 105, a fourth heat exchanger 106, and a controller. The liquid receiver 100, compressor 101, and first heat exchanger 103 are sequentially connected. The outlet of the first heat exchanger 103 is connected to interface A 200 of the four-way valve 102. Interface B 201 of the four-way valve 102 is sequentially connected to the fourth heat exchanger 106, the second heat exchanger 104, and the third heat exchanger 105. The outlet of the third heat exchanger 105 is connected to interface C 202 of the four-way valve 102. Interface D of the four-way valve 102... 203 is connected to the inlet of the liquid storage tank 100; the fourth heat exchanger 106, the second heat exchanger 104, and the first heat exchanger 103 are respectively connected in parallel with a first control valve 300, a second control valve 301, and a third control valve 302; an expansion valve 303 is connected between the second heat exchanger 104 and the third heat exchanger 105; the unit is equipped with multiple temperature sensors connected to the controller to detect the outlet and return water temperatures of the first heat exchanger 103, the second heat exchanger 104, and the third heat exchanger 105, the ambient air outlet temperature of the fourth heat exchanger 106, and the current ambient temperature;

[0065] The controller determines the target operating mode based on the change between the received real-time temperature detection value and the preset target temperature setpoint, combined with the user's set requirements. Then, according to the preset refrigerant flow direction of the target operating mode, it controls the corresponding heat exchanger and control valve to operate or shut down. Specifically:

[0066] When T4≥T S4 When +S1 is activated, the target operating mode of the user demand side is determined to be the air-cooled heating mode. The controller then activates the fan of the fourth heat exchanger, shuts down the water pump of the second heat exchanger, closes the first control valve, and opens the second control valve.

[0067] When T4 < T S4 When -S1 is reached, the target operating mode of the user demand side is determined to be the ground source heat pump heating mode. The controller controls the water pump of the second heat exchanger to start, the fan of the fourth heat exchanger to stop, and the first control valve to start and the second control valve to stop.

[0068] When T4 < T X4 -S1 indicates that the target operating mode of the user demand side is the air-cooled operation mode. The controller controls the fan of the fourth heat exchanger to start, the water pump of the second heat exchanger to stop, and the first control valve to be closed and the second control valve to be opened.

[0069] When T4≥T X4When +S1 is activated, the target operating mode of the user demand side is determined to be the ground source heat pump cooling mode. The controller then activates the water pump of the second heat exchanger, shuts down the fan of the fourth heat exchanger, and activates the first control valve while closing the second control valve.

[0070] Where T4 is the current ambient temperature; T S4 Set the temperature for the preset winter environment; T X4 Set the temperature for the preset summer environment; S1 is the first preset deviation value.

[0071] In this technical solution, the unit includes a liquid receiver 100, a compressor 101, a four-way valve 102, and four heat exchangers. The outlet of the liquid receiver 100 is connected to the inlet of the compressor 101, and the outlet of the compressor 101 is connected to the refrigerant inlet of the first heat exchanger 103. The refrigerant outlet of the first heat exchanger 103 is connected to port A of the four-way valve 102, and port B of the four-way valve 102 is connected in series with the fourth heat exchanger 106, the second heat exchanger 104, and the third heat exchanger 105. The refrigerant outlet of the third heat exchanger 105 is connected to port C of the four-way valve 102, and port D of the four-way valve 102 is connected back to the inlet of the liquid receiver 100. The liquid receiver 100 can be a stainless steel pressure vessel; the compressor 101 can be a scroll compressor; the four-way valve 102 can be a four-way solenoid directional valve; and the heat exchangers can be brazed plate heat exchangers or copper tube aluminum fin heat exchangers. TP2 copper can be used for the copper pipes, and hydrophilic aluminum foil can be used for the aluminum fins. The liquid receiver 100 is installed on the unit chassis support; the compressor 101 is fixed on the shock-absorbing base; the four-way valve 102 is arranged above the outlet pipe of the compressor 101; each heat exchanger is installed in parallel inside the unit casing through the support, and the interfaces are welded together in the above order.

[0072] A first control valve 300 is connected in parallel to both ends of the refrigerant pipeline of the fourth heat exchanger 106; a second control valve 301 is connected in parallel to both ends of the second heat exchanger 104; and a third control valve 302 is connected in parallel to both ends of the first heat exchanger 103. An expansion valve 303 is installed on the pipeline between the second heat exchanger 104 and the third heat exchanger 105. The control valves can be DN20 solenoid valves; the expansion valve 303 can be an electronic expansion valve. The initial opening of the expansion valve 303 is preset according to the operating mode, and the response time of the control valve does not exceed 1 second. The first control valve 300 is connected to the inlet and outlet pipelines of the fourth heat exchanger 106, respectively; the second control valve 301 is installed on the parallel bypass pipe of the second heat exchanger 104; the third control valve 302 is installed on the parallel bypass pipe of the first heat exchanger 103; and the expansion valve 303 is installed on the main pipeline from the outlet of the second heat exchanger 104 to the inlet of the third heat exchanger 105.

[0073] Temperature sensors are located at: the outlet and return ends of the first heat exchanger 103, the outlet and return ends of the second heat exchanger 104, the outlet and return ends of the third heat exchanger 105, the ambient air outlet of the fourth heat exchanger 106, and the ambient space. The controller collects temperature data in real time and executes operations: the first preset deviation value is set to 2℃, and the preset winter ambient temperature T is... S4 The temperature is set to 7℃; the control valve opening or closing logic is as follows: Winter T S4 =7℃, S1=2℃, T4: When T is less than 5℃, the ground source heat pump is turned on; when T is greater than 9℃, the air-cooled heat pump is turned on. Summer T S4 When the temperature is 37℃, S1=2℃, and T4≥35℃+2℃, the ground source heat pump is activated; when T4<35℃-2℃, the air-cooled heat pump is activated. A PT1000 platinum resistance thermometer can be used as the temperature sensor; an industrial PLC can be used as the controller.

[0074] This technical solution achieves automatic switching between hot and cold source modes through structured connections and temperature threshold control. It avoids efficiency losses and frosting issues associated with air-cooled heat exchangers under low-temperature conditions, and reduces unnecessary operation of the ground-source system under suitable temperature conditions. The selection and assembly design of each system component ensures reliable execution of control commands.

[0075] In another technical solution, the first heat exchanger 103 is a domestic hot water heat exchanger used for heating domestic hot water and recovering the exhaust heat of the compressor 101; the second heat exchanger 104 is a ground source heat pump heat exchanger used to replace air-cooled heat exchange under low-temperature conditions and prevent frost formation; the third heat exchanger 105 is a user-side cooling / heating heat exchanger, providing cooling or heating services to the user; and the fourth heat exchanger 106 is an air-cooled environmental heat exchanger used for exchanging heat with air under normal operating conditions and providing environmental heat and cold sources.

[0076] In this technical solution, the first heat exchanger 103 is defined as a domestic hot water heat exchanger, used to recover the heat from the exhaust of the compressor 101 to prepare domestic hot water. Its refrigerant inlet is connected to the outlet pipe of the compressor 101, and the refrigerant outlet is connected to the interface of the four-way valve 102A. The domestic hot water pipeline circulates independently, with the inlet connected to tap water or a water tank, and the outlet supplying hot water to the designated point. This heat exchanger can be a brazed plate heat exchanger, and the plate material can be 316L stainless steel to resist corrosion from domestic water. The assembly position is close to the exhaust port of the compressor 101 to shorten the high-temperature refrigerant transport distance and reduce heat loss. During operation, the high-temperature refrigerant flows through the gaps between the plates, transferring heat to the flowing domestic water on the other side. At a typical inlet water temperature of 15 degrees Celsius, it can heat the hot water to 45-55 degrees Celsius.

[0077] The second heat exchanger 104 serves as a ground source heat pump heat exchanger, operating in heating mode (T4 < T) under heating conditions. S4 -S1) replaces air-cooled heat exchange to prevent frost formation; under cooling conditions, the local source heat pump operates in cooling mode (T4≥T).X4 When +S1), it provides ground source heat dissipation, and its pipeline is connected to buried pipes or underground water system; the fourth heat exchanger 106 serves as an air-cooled environment heat exchanger, and in the heating condition, when the air-cooled operation mode (T4≥T) is used, it provides ground source heat dissipation, and its pipeline is connected to buried pipes or underground water system; S4 When +S1), it acts as an evaporator to absorb heat; under refrigeration conditions, when operating in air-cooled refrigeration mode (T4 < T), it absorbs heat as an evaporator. X4 -S1) acts as a condenser for heat dissipation. The second heat exchanger 104 can be a shell-and-tube heat exchanger, and the tube-side material can be a copper-nickel alloy to resist corrosion from the ground source water; the fourth heat exchanger 106 can be a copper tube aluminum finned heat exchanger, and the fin surface can be coated with a hydrophilic coating. The second heat exchanger 104 is installed at the bottom of the unit and connected to the ground source well through an insulated pipe; the fourth heat exchanger 106 is installed in the ventilation area at the top of the unit and is equipped with an axial flow fan. During operation, when the ambient temperature is lower than the set threshold, the second heat exchanger 104 starts the water pump to circulate the antifreeze on the ground source side; when the ambient temperature is suitable, the fan of the fourth heat exchanger 106 drives air to flow through the finned tubes to achieve heat exchange.

[0078] The third heat exchanger 105 is a user-side cooling and heating heat exchanger, connected to the air conditioning terminal water pipe. Its refrigerant side is connected to the second heat exchanger 104 via expansion valve 303, and its water-side inlet is connected to the air conditioning return water pipe, while its outlet is connected to the air conditioning supply water pipe. This heat exchanger can be a high-efficiency microchannel heat exchanger, and the flat tube material can be aluminum alloy. Its assembly location is close to the unit's control panel side for easy connection to the user's water pipe.

[0079] During operation: The local source heat pump operates in heating mode (T4 < T). S4 -S1) or ground source heat pump operation cooling mode (T4≥T) X4 When +S1 is triggered, the second heat exchanger 104 starts the water pump to circulate the antifreeze. In air-cooled heating mode (T4≥T...),... S4 +S1) or air-cooled operation mode (T4 < T) X4 When -S1 is triggered, the fan in the fourth heat exchanger 106 drives air heat exchange. During the test, when the ambient temperature T4 = 3℃ (T... S4 =5℃, S1=1℃) and when the user's heating demand is activated, the conditions for the ground source heat pump to operate in heating mode are met (T4<T S4 (-S1) The system automatically shuts down the fan of the fourth heat exchanger 106 and starts the water pump of the second heat exchanger 104 to avoid the problem of air-cooled frost.

[0080] This technical solution clearly defines the functional boundaries of the heat exchanger, establishing independent physical channels for domestic hot water recovery, ground-source anti-frost replacement, user energy supply, and conventional air-cooled heat exchange. This configuration eliminates functional overlap and provides a fundamental guarantee for multi-mode collaborative operation.

[0081] In another technical solution, the target operating mode further includes:

[0082] The controller is based on the domestic hot water outlet temperature T of the first heat exchanger 103. 1H The user-side outlet water temperature T of the third heat exchanger 105 3H Preset target hot water temperature T R and the user-side water outlet set temperature T 3S Perform the following operations:

[0083] When T4 < T X4 -S1,T 1H ≥T R -S2 and T 3H ≥T 3S -S3, it is determined that the target operating mode of the user demand side is the air-cooled pure cooling mode. The controller controls the opening of the third heat exchanger 105 and the fourth heat exchanger 106, the closing of the first heat exchanger 103 and the second heat exchanger 104, the opening of the second control valve 301 and the third control valve 302, and the closing of the first control valve 300, so that the refrigerant flows out of the compressor 101, flows through the fourth heat exchanger 106 and the third heat exchanger 105 in sequence, and flows back to the liquid receiver 100.

[0084] When T4≥T S4 +S1,T 1H ≥T R -S2 and T 3H <T 3S When -S3 is reached, the target operating mode of the user demand side is determined to be the air-cooled pure heating mode. The controller controls the opening of the third heat exchanger 105 and the fourth heat exchanger 106, the closing of the first heat exchanger 103 and the second heat exchanger 104, the opening of the second control valve 301 and the third control valve 302, and the closing of the first control valve 300, so that the refrigerant flows out of the compressor 101, flows through the third heat exchanger 105 and the fourth heat exchanger 106 in sequence, and flows back to the liquid receiver 100.

[0085] When T4 < T X4 -S1,T 1H <T R -S2 and T 3H ≥T 3S -S3, when the target operating mode of the user demand side is determined to be air-cooled domestic hot water mode, the controller controls the opening of the first heat exchanger 103, the third heat exchanger 105 and the fourth heat exchanger 106, the closing of the second heat exchanger 104, the closing of the first control valve 300 and the third control valve 302, and the opening of the second control valve 301, so that the refrigerant flows out from the compressor 101, flows through the first heat exchanger 103, the fourth heat exchanger 106 and the third heat exchanger 105 in sequence and flows back to the liquid receiver 100;

[0086] When T4≥T S4 +S1,T 1H <T R-S2 and T 3H <T 3S When -S3 is reached, it is determined that the target operating mode of the user demand side is the air-cooled heating domestic hot water mode. The controller controls the opening of the first heat exchanger 103, the third heat exchanger 105 and the fourth heat exchanger 106, the closing of the second heat exchanger 104, the closing of the first control valve 300 and the third control valve 302, and the opening of the second control valve 301, so that the refrigerant flows out from the compressor 101, flows through the first heat exchanger 103, the third heat exchanger 105 and the fourth heat exchanger 106 in sequence and flows back to the liquid receiver 100.

[0087] Where S2 is the second preset deviation value, S3 is the third preset deviation value, and T 3S Automatically selects the set temperature based on the current operating mode: T in cooling mode 3S =T 3Sx In heating mode T 3S =T 3Sd .

[0088] In this technical solution, when the absolute value of the difference between the ambient temperature and the preset ambient temperature is greater than or equal to the first preset deviation value (typically 2 degrees Celsius), and the actual measured temperature of the domestic hot water is higher than the domestic hot water set temperature minus the second preset deviation value (typically 2 degrees Celsius), and the user-side outlet water temperature is higher than the user-side set temperature minus the third preset deviation value (typically 1 degree Celsius), the controller determines that it is in air-cooled pure cooling mode. At this time, the controller closes the water valve of the first heat exchanger 103 and the third control valve 302, and opens the second control valve 301 and the water pump of the third heat exchanger 105. The refrigerant flow direction is: compressor 101 → fourth heat exchanger 106 (heat dissipation) → third heat exchanger 105 (heat absorption) → liquid receiver 100. If the user-side outlet water temperature is lower than the set value minus the third preset deviation value, it is determined to be in air-cooled pure heating mode, and the refrigerant flows in the reverse direction through the third heat exchanger 105 (heat release) → fourth heat exchanger 106 (heat absorption).

[0089] When the absolute value of the difference between the ambient temperature and the preset ambient temperature is greater than or equal to the first preset deviation value, and the actual measured temperature of the domestic hot water is lower than the set value minus the second preset deviation value, but the outlet water temperature on the user side meets the standard (higher than the set value minus the third preset deviation value), the air-cooled domestic hot water mode is activated. The controller opens the water valve of the first heat exchanger 103 and closes the third control valve 302; the refrigerant flows sequentially through: compressor 101 → first heat exchanger 103 (heating domestic hot water) → fourth heat exchanger 106 (auxiliary heat dissipation) → third heat exchanger 105 (absorbing cold and supplying cooling) → liquid receiver 100.

[0090] When the absolute value of the difference between the ambient temperature and the preset ambient temperature is greater than or equal to the first preset deviation value, and both the domestic hot water temperature and the user-side water temperature fail to meet the standard, the air-cooled heating domestic hot water mode is activated. The controller keeps the third control valve 302 closed, and the refrigerant flow direction is: compressor 101 → first heat exchanger 103 (prioritizes heating domestic hot water) → third heat exchanger 105 (secondary heating of air conditioning water) → fourth heat exchanger 106 (heat absorption balance) → liquid receiver 100.

[0091] By using both domestic hot water temperature and user-side water temperature as dual criteria, the system achieves on-demand coordination between the main cooling / heating functions and domestic hot water recovery in air-cooled mode. When hot water is plentiful, the recovery path is shut off to reduce pump consumption; when demand exists simultaneously, the refrigerant flow path is optimized to improve waste heat utilization, thus avoiding temperature fluctuations caused by functional conflicts.

[0092] In another technical solution, the target operating mode further includes:

[0093] When T4≥T X4 +S1,T 1H ≥T R -S2 and T 3H ≥T 3S -S3, the target operating mode of the user demand side is determined to be the ground source heat pump pure cooling mode. The controller controls the opening of the second heat exchanger 104 and the third heat exchanger 105, the closing of the first heat exchanger 103 and the fourth heat exchanger 106, the opening of the first control valve 300 and the third control valve 302, and the closing of the second control valve 301, so that the refrigerant flows out of the compressor 101, flows through the second heat exchanger 104 and the third heat exchanger 105 in sequence, and flows back to the liquid receiver 100.

[0094] When T4 < T S4 -S1,T 1H ≥T R -S2 and T 3H <T 3S -S3, the target operating mode of the user demand side is determined to be the pure heating mode of the ground source heat pump. The controller controls the opening of the second heat exchanger 104 and the third heat exchanger 105, the closing of the first heat exchanger 103 and the fourth heat exchanger 106, the opening of the first control valve 300 and the third control valve 302, and the closing of the second control valve 301, so that the refrigerant flows out of the compressor 101, flows through the third heat exchanger 105 and the second heat exchanger 104 in sequence, and flows back to the liquid receiver 100.

[0095] When T4 < T X4 -S1,T 1H <T R -S2 and T 3H ≥T 3SWhen -S3 is reached, the target operating mode of the user demand side is determined to be the ground source heat pump cooling and domestic hot water mode. The controller controls the opening of the first heat exchanger 103, the second heat exchanger 104 and the third heat exchanger 105, and the closing of the fourth heat exchanger 106. The first control valve 300 is opened, and the second control valve 301 and the third control valve 302 are closed, so that the refrigerant flows out from the compressor 101, flows through the first heat exchanger 103, the second heat exchanger 104 and the third heat exchanger 105 in sequence and flows back to the liquid receiver 100.

[0096] When T4 < T S4 -S1,T 1H <T R -S2 and T 3H <T 3S When -S3 is reached, the target operating mode on the user demand side is determined to be the ground source heat pump heating and domestic hot water mode. The controller controls the opening of the first heat exchanger 103, the second heat exchanger 104 and the third heat exchanger 105, and the closing of the fourth heat exchanger 106. The first control valve 300 is opened, and the second control valve 301 and the third control valve 302 are closed, so that the refrigerant flows out of the compressor 101, flows through the first heat exchanger 103, the third heat exchanger 105 and the second heat exchanger 104 in sequence and flows back to the liquid receiver 100.

[0097] In this technical solution, when the absolute value of the difference between the ambient temperature and the preset ambient temperature is less than the first preset deviation value (2 degrees Celsius), and the domestic hot water temperature is higher than the set value minus the second preset deviation value (2 degrees Celsius):

[0098] If the user-side outlet water temperature meets the standard (higher than the set value minus the third preset deviation value by 1 degree Celsius), the ground source pure cooling mode is activated. The controller closes the water valve of the first heat exchanger 103 and the third control valve 302, and opens the first control valve 300. The refrigerant flow direction is: compressor 101 → second heat exchanger 104 (ground source heat dissipation) → third heat exchanger 105 (cold absorption for cooling) → receiver 100. If the user-side outlet water temperature does not meet the standard, the ground source pure heating mode is activated. The refrigerant flows in reverse through the third heat exchanger 105 (heat release) → second heat exchanger 104 (ground source heat absorption).

[0099] When the absolute value of the difference between the ambient temperature and the preset ambient temperature is less than the first preset deviation value, and the domestic hot water temperature is lower than the set value minus the second preset deviation value, but the user's cooling demand meets the standard, the ground source cooling domestic hot water mode is activated. The controller opens the water valve of the first heat exchanger 103 and closes the second control valve 301 and the third control valve 302. The refrigerant flows sequentially through: compressor 101 → first heat exchanger 103 (heating domestic hot water) → second heat exchanger 104 (ground source auxiliary heat dissipation) → third heat exchanger 105 (absorbing cold and supplying cooling) → liquid receiver 100.

[0100] When the absolute value of the difference between the ambient temperature and the preset ambient temperature is less than the first preset deviation value, and both the domestic hot water temperature and the user-side water temperature fail to meet the standard, the ground source heating domestic hot water mode is activated. The controller closes the second control valve 301 and the third control valve 302, and the refrigerant flow direction is: compressor 101 → first heat exchanger 103 (heating domestic hot water) → third heat exchanger 105 (heating air conditioning water) → second heat exchanger 104 (ground source heat absorption) → liquid receiver 100.

[0101] By jointly judging the domestic hot water status and user-side water temperature under geothermal conditions, efficient coordination between the geothermal source and waste heat recovery is achieved. In pure mode, redundant heat exchange paths are shut down for energy saving; in hybrid mode, domestic hot water and the main functional heat exchanger are connected in series to ensure that domestic hot water demand is prioritized while maintaining stable user-side temperature, thus avoiding functional conflicts between the geothermal system and heat recovery.

[0102] In another technical solution, the method for determining the first preset deviation value S1, the second preset deviation value S2, and the third preset deviation value S3 is as follows:

[0103] Collect ambient temperature data for N consecutive days and calculate the maximum daily temperature difference ΔT. max =max(T4)-min(T4), take ΔT max The initial value of S1 is obtained by multiplying the average value of N by the coefficient C1, where 5 ≤ N ≤ 10 and 0.2 ≤ C1 ≤ 0.3.

[0104] Under standard operating conditions, running in both cooling and heating modes, record: the range of domestic hot water temperature fluctuation ΔT2 = max(T) 1H )-min(T 1H The user-side water temperature fluctuation range ΔT3 = max(T) 3H )-min(T 3H Let the initial value of S2 be C2×ΔT2, and the initial value of S3 be C3×ΔT3, where 0.6≤C2≤0.9 and 0.6≤C3≤0.9;

[0105] The controller stores and records the initial values ​​of the first preset deviation value S1, the second preset deviation value S2, and the third preset deviation value S3.

[0106] In this technical solution, ambient temperature data is collected for 7 consecutive days (24 sets of records per day), and the daily maximum temperature difference (daily maximum temperature minus daily minimum temperature) is calculated. The arithmetic mean of the 7-day maximum temperature difference (e.g., the average of 8.2℃, 9.5℃, and 7.8℃ is 8.5℃) is multiplied by a coefficient of 0.2 to obtain the initial value of S1, which is 1.7℃. Data acquisition uses an installed ambient temperature sensor, and the controller automatically stores and processes the data. In practice, if the average maximum temperature difference in a region during spring and autumn is 10℃, the initial value of S1 is set to 2℃. This setting method ensures that S1 conforms to local climate characteristics, avoiding erroneous switching caused by a fixed threshold.

[0107] Under standard cooling conditions (ambient dry-bulb temperature 35℃), the system operated in pure cooling mode for 2 hours, recording the fluctuation range of domestic hot water temperature (e.g., 45.3℃ to 46.1℃, ΔT2 = 0.8℃). Multiplying ΔT2 by a coefficient of 0.8 yields the initial value of S2, 0.64℃ (rounded to 1℃). Under standard heating conditions (ambient dry-bulb temperature 7℃), the system operated in pure heating mode, recording the fluctuation of user-side water temperature (e.g., 44.5℃ to 45.2℃, ΔT3 = 0.7℃). Multiplying ΔT3 by a coefficient of 0.8 yields the initial value of S3, 0.56℃ (rounded to 1℃). A PT1000 temperature sensor was used in the test, with a data sampling interval of 10 seconds.

[0108] The controller stores the determined initial values ​​of S1, S2, and S3 (e.g., 2℃, 1℃, 1℃) in non-volatile memory. These thresholds are invoked in real-time during operation to participate in mode determination. The stored data includes the set timestamp and the calculated original values, supporting later calibration traceability. Implementation example: When the system starts up for the first time, it automatically performs 5 days of environmental data acquisition (N=5) and 1 hour of standard operating condition testing, completing threshold initialization and storage.

[0109] Thresholds are set based on historical environmental data and measured temperature fluctuations, making the mode switching criteria more closely aligned with actual system characteristics and regional climate. The dynamic initialization process avoids biases imposed by manual experience settings, improving the accuracy of the coordination between environmental mode switching and heat recovery functions.

[0110] In another technical solution, the controller dynamically adjusts the values ​​of S1, S2, and S3 based on the intensity of ambient temperature fluctuations and load conflicts.

[0111] The absolute value of the rate of change of ambient temperature is calculated in real time as δ=︱ΔT4 / Δt︱, and the first preset deviation value S1 is updated to S1'=S1× (1+γ×δ);

[0112] Real-time calculation of load coupling factor α=|T R -T 3S | When α > β: S2' = k×S2, S3' = k×S3; When α ≤ β: S2' = m×S2, S3' = m×S3;

[0113] Wherein, γ is the preset environmental change sensitivity, with a value range of 0.05~0.2; β is the preset cold and heat load conflict threshold, with a value range of 20~30℃; k and m are preset coefficients, with k taking a value of 0.8 and m taking a value of 1.2.

[0114] In this technical solution, the rate of change of ambient temperature is calculated in real time. Ambient temperature data is collected every minute, and the absolute value of the change compared to the previous minute is calculated (e.g., 5℃ in the first minute, 3℃ in the second minute, rate of change δ=2℃ / min). When δ exceeds 1℃ / min for 2 consecutive minutes, the first preset deviation value S1 is updated from the initial value of 1℃ to S1'=1×(1+0.1×2)=1.2℃. The adjustment coefficient γ is taken as 0.1 (within the range of 0.05-0.2). Implementation example: In spring, when the ambient temperature drops sharply from 8℃ to 2℃ (δ=6℃ / h), the system automatically raises S1 from 1℃ to 1.6℃, triggering the ground source mode switch in advance to prevent the risk of frost.

[0115] Real-time calculation of domestic hot water set temperature (T) R =45℃) and the user-side set temperature (T 3S The absolute difference α = 5℃ (e.g., T = 40℃). The preset conflict threshold β = 25℃. When α > β (e.g., T...), R =50℃, T 3S =20℃, α=30℃), reduce the second and third preset deviation values ​​to 0.8 times the original value (S2 is adjusted from 2℃ to 1.6℃, S3 is adjusted from 1℃ to 0.8℃); when α≤β (e.g., T R =45℃, T 3S =40℃, α=5℃), S2 and S3 are increased to 1.2 times their original values ​​(S2=2.4℃, S3=1.2℃). The coefficients k and m are taken as 0.8 and 1.2 respectively.

[0116] When the inlet pressure of the third heat exchanger 105 exceeds the set value (P) set When the pressure is 3.0 MPa and the temperature is 0.1 MPa (ΔP = 0.2 MPa), a pressure weight of β = 0.8 and a temperature weight of α = 0.2 are forcibly set. Under normal operating conditions, the weights are set as α = 0.5 + 0.01 × |T R -T 3S The calculation (e.g., |45-40|=5℃, α=0.55) uses a pressure weighting β=0.45. During implementation, a sudden cooling water failure in cooling mode causes the pressure to rise to 3.3MPa. The system automatically increases the pressure regulation weighting to 80% and quickly opens expansion valve 303 to release pressure.

[0117] Enhanced sensitivity to environmental changes and adaptive adjustment to load conflicts mitigate control oscillations caused by temperature threshold rigidity; under high-pressure conditions, pressure protection weights are emphasized to balance system efficiency and operational safety. Dynamic adjustment mechanisms improve stability under complex operating conditions.

[0118] In another technical solution, the initial opening degree of the expansion valve 303 is dynamically set according to the target operating mode:

[0119] For air-cooled pure cooling mode and ground source heat pump pure cooling mode: θ0 = 30% + 0.4 × (T4 - 35)%, and the opening degree is limited to 25%-45%;

[0120] For air-cooled pure heating mode and ground source heat pump pure heating mode: θ0 = 40% + 0.6 × (0 - T4)%, with the opening degree limited to 35%-55%;

[0121] For air-cooled domestic hot water mode, air-cooled domestic hot water mode, ground-source heat pump cooling domestic hot water mode, and ground-source heat pump heating domestic hot water mode: θ0 = 35% + 0.3 × |T R -T 3S |%, the opening is limited to 30%-50%.

[0122] In this technical solution, for both air-cooled pure cooling mode and ground-source heat pump pure cooling mode, the initial opening of expansion valve 303 is set to a base value of 30%, and dynamically compensated according to the ambient temperature: when the ambient temperature is above 35 degrees Celsius, the opening increases by 0.4% for every 1 degree Celsius increase; when the ambient temperature is below 35 degrees Celsius, the opening decreases by 0.4% for every 1 degree Celsius decrease. The final opening is limited to between 25% and 45%. For example, when the ambient temperature is 38 degrees Celsius, the calculated opening = 30% + 0.4 × (38-35)% = 31.2%; when the ambient temperature is 30 degrees Celsius, the opening = 30% + 0.4 × (30-35)% = 28%. Expansion valve 303 can be a stepper motor driven electronic expansion valve 303, and the valve body material can be H62 brass. It is installed on the main pipeline from the outlet of the second heat exchanger 104 to the inlet of the third heat exchanger 105.

[0123] For both air-cooled pure heating mode and ground-source heat pump pure heating mode, the initial opening of expansion valve 303 is set to 40% of the base value, and compensated according to the ambient low temperature: for every 1 degree Celsius the ambient temperature is below 0 degrees Celsius, the opening increases by 0.6%; for every 1 degree Celsius the ambient temperature is above 0 degrees Celsius, the opening decreases by 0.6%. The opening range is limited to 35% to 55%. For example, when the ambient temperature is -3 degrees Celsius, the opening = 40% + 0.6 × [0 - (-3)]% = 41.8%; when the ambient temperature is 5 degrees Celsius, the opening = 40% + 0.6 × (0 - 5)% = 37%.

[0124] For operation modes including domestic hot water recovery (air-cooled / ground-source cooling and heating domestic hot water mode), the initial opening degree is set to 35% of the base value, and based on the domestic hot water set temperature (T). R ) and user-side set temperature (T) 3S Absolute difference compensation: Increase opening by 3% for every 10 degrees Celsius difference. Opening is limited to 30% to 50%. For example, T R =45℃, T 3S When the temperature is 40℃, |45-40|=5℃, the opening degree = 35%+0.3×5%=36.5%; if T R =50℃, T 3S =35℃, |50-35|=15℃, opening degree=35%+0.3×15%=39.5%. A filter screen should be installed at the inlet of the 303 expansion valve; the material can be 304 stainless steel wire mesh.

[0125] The initial opening of the expansion valve 303 is preset according to the characteristics of different operating modes, providing a reasonable flow starting point for cooling, heating, and heat recovery operations. Combined with dynamic compensation of the difference between ambient temperature and load, the system stabilization time is shortened, and energy consumption during regulation is reduced. The opening limit design avoids the risk of flow runaway.

[0126] In another technical solution, the opening control of the expansion valve 303 employs a two-parameter feedback mechanism:

[0127] Real-time monitoring of the outlet temperature T of the second heat exchanger 104 2H and the inlet pressure P of the third heat exchanger 105;

[0128] When T 2H >T set When + ΔT1, the initial opening of the expansion valve 303 is reduced by 5%-15%;

[0129] When T 2H <T set When -ΔT1, increase the initial opening of expansion valve 303 by 5%-15%;

[0130] When P > P set When +ΔP, the initial opening of the expansion valve 303 is increased by 5%-15%;

[0131] When P < P set When -ΔP, the initial opening of the expansion valve 303 is reduced by 5%-15%;

[0132] Among them, T set Set the outlet temperature of the second heat exchanger 104 to meet the condition 5℃≤T set ≤45℃; ΔT1 is the temperature dead zone threshold, satisfying 0.5℃≤ΔT1≤2.0℃; P setSet the inlet pressure for the third heat exchanger 105 to meet the condition 0.5MPa≤Pset≤4.0MPa; ΔP is the pressure dead zone threshold, which meets the condition 0.05MPa≤ΔP≤0.2MPa.

[0133] In this technical solution, the outlet temperature (T) of the second heat exchanger 104 is monitored in real time. 2H ), set the reference value T set =15℃ (cooling mode) or 40℃ (heating mode), dead zone threshold ΔT1=1℃. When T 2H For 5 minutes, the temperature remained above T. set When +ΔT1 (e.g., 16℃), reduce the opening of expansion valve 303 by 10%; when T 2H For 5 minutes, the temperature remained below T. set When -ΔT1 (e.g., 14℃) is reached, the opening is increased by 10%. A PT100 platinum resistance thermometer can be used, encapsulated within the insulation layer of the outlet pipe of the second heat exchanger (104), with the probe contacting the outer wall of the refrigerant pipe. Test case: The return water temperature on the ground source side abnormally rises to 18℃ (T... set (At 15℃), the system automatically reduces the opening of expansion valve 303 from 40% to 36%, restoring heat exchange efficiency.

[0134] Real-time monitoring of the inlet pressure (P) of the third heat exchanger 105, and setting a reference value P. set =2.8MPa (cooling mode) or 2.2MPa (heating mode), dead zone threshold ΔP = 0.1MPa. If P remains above P for 2 minutes... set When the pressure is +ΔP (e.g., 2.9 MPa), increase the opening of expansion valve 303 by 12%; when P remains below P for 2 minutes... set When -ΔP (e.g., 2.1MPa) is reached, the opening is reduced by 12%. A piezoresistive transmitter with a range of 0-4.0MPa can be selected as the pressure sensor. The interface is installed in the straight pipe section 0.5 meters before the refrigerant inlet of the third heat exchanger 105. The temperature dead zone threshold ΔT1 is set to 0.8℃, 1.0℃, or 1.5℃ (typical value 1.0℃), and the pressure dead zone threshold ΔP is set to 0.08MPa, 0.10MPa, or 0.15MPa (typical value 0.10MPa). The threshold selection is based on the accuracy of the pipeline sensors: ΔT1 ≥ 0.8℃ when the temperature sensor error is ±0.3℃, and ΔP ≥ 0.08MPa when the pressure sensor error is ±0.02MPa. During assembly, the temperature sensor and pressure sensor are positioned 1.5 meters and 2.0 meters away from the outlet of expansion valve 303, respectively, to avoid valve body disturbance affecting the measurement.

[0135] The opening of expansion valve 303 is dynamically corrected through dual closed-loop feedback of temperature and pressure. Temperature regulation maintains the heat exchange efficiency on the ground source side, pressure regulation ensures the safe operation of compressor 101, and dead-zone threshold design avoids frequent operation. Dual-parameter coordinated control improves system stability.

[0136] In another technical solution, the controller generates an opening adjustment command by combining temperature deviation and pressure deviation according to a preset weight ratio.

[0137] Define the basic weight calculation function: α base = 0.5 + 0.01 × |T R -T 3S |;

[0138] Perform weighted amplitude limiting: if α base If α < 0.5, then α = 0.5; if α base If the α value is greater than 0.8, then α = 0.8; otherwise, α = α base ;

[0139] Pressure weight β = 1 - α;

[0140] When the inlet pressure P of the third heat exchanger 105 is greater than P set When +0.5×ΔP, β=0.8 and α=0.2 are forcibly set.

[0141] In this technical solution, the domestic hot water set temperature (T) is used. R ) and user-side set temperature (T) 3S The absolute difference between α and α is used to calculate the base value for temperature weighting. A limiting process is applied to the base weights: when α... base When α < 0.5, force α = 0.5; when α base When the value is greater than 0.8, α is forced to be 0.8; otherwise, the calculated value is maintained. The controller integrates temperature deviation and pressure deviation according to their weighted proportions: the weight of the temperature adjustment command is α, and the weight of the pressure adjustment command is β. If the temperature deviation requires an increase of 5% in the opening and the pressure deviation requires a decrease of 3% in the opening, then the final command is (5% × 0.65) + (-3% × 0.35) = 2.05%.

[0142] A dynamic weight allocation mechanism balances temperature and pressure regulation needs under normal operating conditions; in high-pressure and high-risk situations, system safety is prioritized to avoid control failures caused by parameter coupling. Weight limiting design maintains regulation stability.

[0143] Example 1: Air-cooled pure cooling mode (e.g.) Figure 2 (As shown)

[0144] Scenario: Ambient temperature 30℃ (T4), preset T X4 =35℃, S1=1.5℃, T 1H =47℃, T R =45℃, S2=2℃, T 3H =26℃, T 3S =T 3Sx =25℃, S3=1℃.

[0145] Satisfy: T4 <T X4 -S1→ 30<35-1.5=33.5,T 1H ≥T R -S2→47≥45-2=43, and T 3H ≥T 3Sx -S3→26≥25-1=24;

[0146] Control: Shut down the first heat exchanger water pump and the third control valve, and open the second control valve;

[0147] Refrigerant flow: Compressor 101 → Fourth heat exchanger 106 (heat dissipation) → Third heat exchanger 105 (cooling absorption) → Receiver 100;

[0148] The initial opening of the expansion valve is θ0 = 30% + 0.4 × (30-35)% = 28%.

[0149] Result: The water temperature at the user's side remained stable at 24.8℃, and the domestic hot water was not activated, thus achieving the goal of energy saving.

[0150] Example 2: Air-cooled pure heating mode (e.g.) Figure 3 (As shown)

[0151] Scenario: Ambient temperature 15℃ (T4), preset T S4 =5℃, S1=1.5℃, T 1H =46℃, T R =45℃, S2=2℃, T 3H =42℃, T 3S =T 3Sd =45℃, S3=1℃.

[0152] Satisfy: T4≥T S4 + S1→ 15≥5+1.5,T 1H ≥T R -S2→46≥45-2=43, and T 3H <T 3Sd -S3→42<45-1=44;

[0153] Control: Turn off the water pump of the first heat exchanger 103 and open the second control valve 301;

[0154] Refrigerant reversal: Compressor 101 → Third heat exchanger 105 (heat release) → Fourth heat exchanger 106 (heat absorption) → Receiver 100;

[0155] The opening degree of expansion valve 303 is θ0 = 40% + 0.6 × (0 - 15) = 31%.

[0156] Result: The water temperature at the user's side rose to 44.5℃, and there was no frost on the air-cooled heat exchanger.

[0157] Example 3: Air-cooled domestic hot water mode (e.g.) Figure 4 (As shown)

[0158] Scenario: Ambient temperature 32℃ (T4), preset T X4 =35℃, S1=1℃, T 1H =42℃, T R =45℃, S2=2℃, T 3H =26℃, T 3S =T 3Sx =25℃, S3=1℃.

[0159] Satisfy: T4 < T X4 - S1→ 32<34,T 1H <T R -S2→42<45-2=43, and T 3H ≥T 3Sx -S3→26≥25-1=24;

[0160] Control: Turn on the water pump of the first heat exchanger 103 and close the third control valve 302;

[0161] Refrigerant flow: Compressor 101 → First heat exchanger 103 (heating hot water) → Fourth heat exchanger 106 (auxiliary heat dissipation) → Third heat exchanger 105 (cooling absorption) → Liquid receiver 100;

[0162] The opening degree of expansion valve 303 is θ0 = 35% + 0.3 × |45 - 25| = 41%.

[0163] Result: The domestic hot water temperature rose to 44℃, and the water temperature at the user's side was 25.1℃.

[0164] Example 4: Air-cooled heating domestic hot water mode (e.g.) Figure 5 (As shown)

[0165] Scenario: Ambient temperature 15℃ (T4), preset T S4 =5℃, S1=1℃, T 1H =42℃, T R =45℃, S2=2℃, T 3H =43℃, T 3S =T 3Sd =45℃, S3=1℃.

[0166] Satisfy: T4≥T S4 + S1→ 15≥6,T 1H <T R -S2→42<43, and T 3H <T 3Sd -S3→43<44;

[0167] Control: Turn on the water pump of the first heat exchanger 103 and close the third control valve 302;

[0168] Refrigerant flow: Compressor 101 → First heat exchanger 103 (heating hot water) → Third heat exchanger 105 (heating air conditioning water) → Fourth heat exchanger 106 (absorbing heat) → Receiver 100;

[0169] The opening degree of expansion valve 303 is θ0 = 35% + 0.3 × |45 - 45| = 35%.

[0170] Results: Domestic hot water temperature was 44.5℃, and the water temperature at the user's side was 44.8℃. The system operated efficiently with no risk of frost formation.

[0171] Example 5: Ground-source pure cooling mode (e.g.) Figure 6 (As shown)

[0172] Scenario: Ambient temperature 38℃ (T4), preset T X4 =30℃, S1=1.5℃, T 1H =46℃, T R =45℃, S2=2℃, T 3H =26℃, T 3S =T 3Sx =25℃, S3=1℃.

[0173] Satisfy: T4≥T X4 + S1→38≥31.5, T 1H ≥T R -S2→46≥43, and T 3H ≥T 3Sx -S3→26≥24;

[0174] Control: Turn off the water pump of the first heat exchanger 103 and open the first control valve 300;

[0175] Refrigerant flow: Compressor 101 → Second heat exchanger 104 (ground source heat dissipation) → Third heat exchanger 105 (cooling absorption) → Receiver 100;

[0176] The opening degree of expansion valve 303 is θ0 = 30% + 0.4 × (38 - 35) = 31.2%.

[0177] Results: The water temperature at the user side was 24.9℃, and the water temperature fluctuation at the ground source side was ≤0.3℃.

[0178] Example 6: Ground-source pure heating mode (e.g.) Figure 7 (As shown)

[0179] Scenario: Ambient temperature -10℃ (T4), preset T S4 =5℃, S1=1.5℃, T1H =47℃, T R =45℃, S2=2℃, T 3H =43℃, T 3S =T 3Sd =45℃, S3=1℃.

[0180] Satisfy: T4 < T S4 - S1→ -10<5-1.5=3.5); T 1H ≥T R -S2→47≥45-2=43, and T 3H <T 3Sd -S3→ 43<45-1=44.

[0181] Control: Open the first control valve 300 and close the third control valve 302;

[0182] Refrigerant reversal: Compressor 101 → Third heat exchanger 105 (heat release) → Second heat exchanger 104 (ground source heat absorption) → Receiver 100;

[0183] The opening degree of expansion valve 303 is θ0 = 40% + 0.6 × (0 - (-10)) = 46%.

[0184] Results: The water temperature at the user side was 45.2℃, and the return water temperature at the ground source side remained stable at 6℃.

[0185] Example 7: Ground-source cooling domestic hot water mode (e.g.) Figure 8 (As shown)

[0186] Scenario: Ambient temperature 33℃ (T4), preset T X4 =35℃, S1=1.5℃, T 1H =42℃, T R =45℃, S2=2℃, T 3H =25.5℃, T 3S =T 3Sx =25℃, S3=1℃.

[0187] Satisfy: T4 <T X4 - S1→ 33<35-1.5=33.5, T 1H <T R -S2→42<45-2=43, and T 3H ≥T 3Sx -S3→25.5≥25-1=24;

[0188] Control: Turn on the water pump of the first heat exchanger 103 and close the second control valve 301;

[0189] Refrigerant flow: Compressor 101 → First heat exchanger 103 (heating hot water) → Second heat exchanger 104 (ground source heat dissipation) → Third heat exchanger 105 (cooling absorption) → Receiver 100;

[0190] The opening degree of expansion valve 303 is θ0 = 35% + 0.3 × |45 - 25| = 41%.

[0191] Results: Domestic hot water temperature was 44℃, while the user-side outlet water temperature dropped to 24.8℃. During operation, the inlet pressure of the third heat exchanger rose to 3.1 MPa (P set =3.0MPa, ΔP=0.2MPa), triggering the high-pressure protection mechanism, forcibly setting the pressure weight β=0.8, and quickly adjusting the opening of the expansion valve.

[0192] Example 8: Geothermal heating domestic hot water mode (e.g.) Figure 9 (As shown)

[0193] Scenario: Ambient temperature -1℃ (T4), preset T S4 =5℃, S1=1℃, T 1H =40℃, T R =45℃, S2=2℃, T 3H =42℃, T 3S =T 3Sd =45℃, S3=1℃.

[0194] Satisfy: T4 < T S4 - S1→ -1<4;T 1H <T R -S2→40<43, and T 3H <T 3Sd -S3→42<44.

[0195] Control: Turn on the water pump of the first heat exchanger 103 and close the second control valve 301;

[0196] Refrigerant flow: Compressor 101 → First heat exchanger 103 (heating hot water) → Third heat exchanger 105 (heating air conditioning water) → Second heat exchanger 104 (ground source heat absorption) → Receiver 100;

[0197] The opening degree of expansion valve 303 is θ0 = 35% + 0.3 × |45 - 45| = 35%.

[0198] Results: Domestic hot water temperature 44.7℃, user-side outlet water temperature 44.9℃, and the inlet pressure of the third heat exchanger rose to 3.3MPa during operation (P set =2.2MPa, ΔP=0.2MPa), triggering the forced opening adjustment mechanism, the expansion valve opening increases by 12% to 47%.

[0199] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. An energy-saving control method for a multi-functional heat pump heat recovery unit, characterized in that, The unit includes a liquid receiver, a compressor, a four-way valve, a first heat exchanger, a second heat exchanger, a third heat exchanger, a fourth heat exchanger, and a controller. The liquid receiver, compressor, and first heat exchanger are connected sequentially. The outlet of the first heat exchanger is connected to port A 200 of the four-way valve. Port B 201 of the four-way valve is connected sequentially to the fourth, second, and third heat exchangers. The outlet of the third heat exchanger is connected to port C 202 of the four-way valve, and port D 203 of the four-way valve is connected to the inlet of the liquid receiver. The fourth, second, and first heat exchangers are each connected in parallel with a first control valve, a second control valve, and a third control valve. An expansion valve connects the second and third heat exchangers. The unit is equipped with multiple temperature sensors connected to the controller to detect the outlet and return water temperatures of the first, second, and third heat exchangers, the ambient air outlet temperature of the fourth heat exchanger, and the current ambient temperature. The controller determines the target operating mode based on the change between the received real-time temperature detection value and the preset target temperature setpoint, combined with the user's set requirements. Then, according to the preset refrigerant flow direction of the target operating mode, it controls the corresponding heat exchanger and control valve to operate or shut down. Specifically: When T4≥T S4 When +S1 is activated, the target operating mode of the user demand side is determined to be the air-cooled heating mode. The controller then activates the fan of the fourth heat exchanger, shuts down the water pump of the second heat exchanger, closes the first control valve, and opens the second control valve. When T4 < T S4 -S1 indicates that the target operating mode of the user demand side is the ground source heat pump heating mode. The controller controls the water pump of the second heat exchanger to start, the fan of the fourth heat exchanger to stop, and the first control valve to start and the second control valve to stop. When T4 < T X4 -S1 indicates that the target operating mode of the user demand side is the air-cooled operation mode. The controller controls the fan of the fourth heat exchanger to start, the water pump of the second heat exchanger to stop, and the first control valve to be closed and the second control valve to be opened. When T4≥T X4 When +S1 is activated, the target operating mode of the user demand side is determined to be the ground source heat pump cooling mode. The controller then activates the water pump of the second heat exchanger, shuts down the fan of the fourth heat exchanger, and activates the first control valve while closing the second control valve. Where T4 is the current ambient temperature; T S4 Set the temperature for the preset winter environment; T X4 Set the temperature for the preset summer environment; S1 is the first preset deviation value.

2. The energy-saving control method for the multifunctional heat pump heat recovery unit as described in claim 1, characterized in that, The first heat exchanger is a domestic hot water heat exchanger, used for heating domestic hot water and recovering heat from the compressor exhaust; the second heat exchanger is a ground source heat pump heat exchanger, used to replace air-cooled heat exchange under low-temperature conditions and prevent frost formation; the third heat exchanger is a user-side cooling / heating heat exchanger, providing cooling or heating services to the user; and the fourth heat exchanger is an air-cooled environmental heat exchanger, used for exchanging heat with the air under normal operating conditions and providing environmental heat and cold sources.

3. The energy-saving control method for the multifunctional heat pump heat recovery unit as described in claim 2, characterized in that, The target operating mode also includes: The controller is based on the domestic hot water outlet temperature T of the first heat exchanger. 1H The user-side outlet water temperature T of the third heat exchanger 3H Preset target hot water temperature T R and the user-side water outlet set temperature T 3S Perform the following operations: When T4 < T X4 -S1,T 1H ≥T R -S2 and T 3H ≥T 3S -S3, the target operating mode of the user demand side is determined to be air-cooled pure refrigeration mode. The controller controls the opening of the third and fourth heat exchangers, the closing of the first and second heat exchangers, the opening of the second and third control valves, and the closing of the first control valve, so that the refrigerant flows out of the compressor, flows through the fourth and third heat exchangers in sequence, and flows back to the liquid receiver. When T4≥T S4 +S1,T 1H ≥T R -S2 and T 3H <T 3S -S3, the target operating mode of the user demand side is determined to be air-cooled pure heating mode. The controller controls the opening of the third and fourth heat exchangers, the closing of the first and second heat exchangers, the opening of the second and third control valves, and the closing of the first control valve, so that the refrigerant flows out of the compressor, flows through the third and fourth heat exchangers in sequence, and flows back to the liquid receiver. When T4 < T X4 -S1,T 1H <T R -S2 and T 3H ≥T 3S -S3 indicates that the target operating mode of the user demand side is determined to be air-cooled cooling and domestic hot water mode. The controller controls the opening of the first heat exchanger, the third heat exchanger and the fourth heat exchanger, the closing of the second heat exchanger, the closing of the first control valve and the third control valve, and the opening of the second control valve, so that the refrigerant flows out of the compressor, flows through the first heat exchanger, the fourth heat exchanger and the third heat exchanger in sequence, and flows back to the liquid receiver. When T4≥T S4 +S1,T 1H <T R -S2 and T 3H <T 3S -S3, the target operating mode of the user demand side is determined to be the air-cooled heating domestic hot water mode. The controller controls the opening of the first heat exchanger, the third heat exchanger and the fourth heat exchanger, the closing of the second heat exchanger, the closing of the first control valve and the third control valve, and the opening of the second control valve, so that the refrigerant flows out of the compressor, flows through the first heat exchanger, the third heat exchanger and the fourth heat exchanger in sequence and flows back to the liquid receiver. Where S2 is the second preset deviation value, S3 is the third preset deviation value, and T 3S Automatically selects the set temperature based on the current operating mode: T in cooling mode 3S =T 3Sx In heating mode T 3S =T 3Sd .

4. The energy-saving control method for the multifunctional heat pump heat recovery unit as described in claim 3, characterized in that, The target operating mode also includes: When T4≥T X4 +S1,T 1H ≥T R -S2 and T 3H ≥T 3S -S3 indicates that the target operating mode of the user demand side is the ground source heat pump pure cooling mode. The controller controls the opening of the second and third heat exchangers, the closing of the first and fourth heat exchangers, the opening of the first and third control valves, and the closing of the second control valve, so that the refrigerant flows out of the compressor, flows through the second and third heat exchangers in sequence, and flows back to the liquid receiver. When T4 < T S4 -S1,T 1H ≥T R -S2 and T 3H <T 3S -S3 indicates that the target operating mode of the user demand side is the ground source heat pump pure heating mode. The controller controls the opening of the second and third heat exchangers, the closing of the first and fourth heat exchangers, the opening of the first and third control valves, and the closing of the second control valve, so that the refrigerant flows out of the compressor, flows through the third heat exchanger and the second heat exchanger in sequence, and flows back to the liquid receiver. When T4 < T X4 -S1,T 1H <T R -S2 and T 3H ≥T 3S When -S3 is reached, the target operating mode of the user demand side is determined to be the ground source heat pump cooling and domestic hot water mode. The controller controls the opening of the first heat exchanger, the second heat exchanger and the third heat exchanger, and the closing of the fourth heat exchanger. The first control valve is opened, and the second control valve and the third control valve are closed, so that the refrigerant flows out of the compressor, flows through the first heat exchanger, the second heat exchanger and the third heat exchanger in sequence, and flows back to the liquid receiver. When T4 < T S4 -S1,T 1H <T R -S2 and T 3H <T 3S When -S3 is activated, the target operating mode of the user demand side is determined to be the ground source heat pump heating and domestic hot water mode. The controller controls the opening of the first heat exchanger, the second heat exchanger, and the third heat exchanger, and the closing of the fourth heat exchanger. The first control valve is opened, and the second control valve and the third control valve are closed, so that the refrigerant flows out of the compressor, flows through the first heat exchanger, the third heat exchanger, and the second heat exchanger in sequence, and flows back to the liquid receiver.

5. The energy-saving control method for the multifunctional heat pump heat recovery unit as described in claim 4, characterized in that, The method for determining the first preset deviation value S1, the second preset deviation value S2, and the third preset deviation value S3 is as follows: Collect ambient temperature data for N consecutive days and calculate the maximum daily temperature difference ΔT. max =max(T4)-min(T4), take ΔT max The initial value of S1 is obtained by multiplying the average value of N by the coefficient C1, where 5 ≤ N ≤ 10 and 0.2 ≤ C1 ≤ 0.

3. Under standard operating conditions, running in both cooling and heating modes, record: the range of domestic hot water temperature fluctuation ΔT2 = max(T) 1H )-min(T 1H The user-side water temperature fluctuation range ΔT3 = max(T) 3H )-min(T 3H Let the initial value of S2 be C2×ΔT2, and the initial value of S3 be C3×ΔT3, where 0.6≤C2≤0.9 and 0.6≤C3≤0.9; The controller stores and records the initial values ​​of the first preset deviation value S1, the second preset deviation value S2, and the third preset deviation value S3.

6. The energy-saving control method for the multifunctional heat pump heat recovery unit as described in claim 5, characterized in that, The controller dynamically adjusts the values ​​of S1, S2, and S3 based on the intensity of ambient temperature fluctuations and load conflicts. The absolute value of the rate of change of ambient temperature is calculated in real time as δ=︱ΔT4 / Δt︱, and the first preset deviation value S1 is updated to S1'=S1×(1+γ×δ); Real-time calculation of load coupling factor α=|T R -T 3S | When α > β: S2' = k × S2, S3' = k × S3; When α ≤ β: S2' = m × S2, S3' = m × S3; Wherein, γ is the preset environmental change sensitivity, with a value range of 0.05~0.2; β is the preset cold and heat load conflict threshold, with a value range of 20~30℃; k and m are preset coefficients, with k taking a value of 0.8 and m taking a value of 1.

2.

7. The energy-saving control method for the multifunctional heat pump heat recovery unit as described in claim 4, characterized in that, The initial opening degree of the expansion valve is dynamically set according to the target operating mode: For air-cooled pure cooling mode and ground source heat pump pure cooling mode: θ0 = 30% + 0.4 × (T4 - 35)%, and the opening degree is limited to 25%-45%; For air-cooled pure heating mode and ground source heat pump pure heating mode: θ0 = 40% + 0.6 × (0 - T4)%, with the opening degree limited to 35%-55%; For air-cooled domestic hot water mode, air-cooled domestic hot water mode, ground-source heat pump cooling domestic hot water mode, and ground-source heat pump heating domestic hot water mode: θ0 = 35% + 0.3 × |T R -T 3S |%, the opening is limited to 30%-50%.

8. The energy-saving control method for the multifunctional heat pump heat recovery unit as described in claim 7, characterized in that, The opening control of the expansion valve employs a two-parameter feedback mechanism: Real-time monitoring of the outlet temperature T of the second heat exchanger 2H and the inlet pressure P of the third heat exchanger; When T 2H >T set When + ΔT1, reduce the initial opening of the expansion valve by 5%-15%; When T 2H <T set When -ΔT1, increase the initial opening of the expansion valve by 5%-15%; When P > P set When +ΔP, increase the initial opening of the expansion valve by 5%-15%; When P < P set When -ΔP, reduce the initial opening of the expansion valve by 5%-15%; Among them, T set Set the outlet temperature of the second heat exchanger to meet the condition 5℃≤T set ≤45℃; ΔT1 is the temperature dead zone threshold, satisfying 0.5℃≤ΔT1≤2.0℃; P set Set the inlet pressure for the third heat exchanger to meet the requirement of 0.5 MPa ≤ P set ≤4.0MPa; ΔP is the pressure dead zone threshold, which satisfies 0.05MPa≤ΔP≤0.2MPa.

9. The energy-saving control method for the multifunctional heat pump heat recovery unit as described in claim 8, characterized in that, The controller generates an opening adjustment command by combining temperature deviation and pressure deviation according to a preset weight ratio. Define the basic weight calculation function: α base = 0.5 + 0.01 × |T R -T 3S |; Perform weighted amplitude limiting: if α base If α < 0.5, then α = 0.5; if α base If the α value is greater than 0.8, then α = 0.8; otherwise, α = α base ; Pressure weight β = 1 - α; When the inlet pressure of the third heat exchanger P > P set When +0.5×ΔP, β=0.8 and α=0.2 are forcibly set.

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