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

Abstract

The invention 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. The problems that an existing heat pump unit cannot intelligently switch cold and heat source modes according to environmental conditions and user load requirements, so that the operation energy efficiency is low, and heat cannot be effectively utilized and recycled are solved. The method is based on a unit structure, the environment temperature, the preset environment set temperature and multiple water temperature parameters are detected in real time through temperature sensors arranged on all heat exchangers; and the controller judges a target operation mode according to comparison between the environment temperature difference absolute value and a first preset deviation value. According to the method, intelligent switching between the environment heat source and the geothermal source is achieved, the system energy efficiency is optimized, and the method is mainly used for improving the energy comprehensive utilization efficiency in the domestic hot water preparation and air conditioner refrigeration and heating processes.

Description

Technical Field

[0001] The present invention relates to the technical field of heat pump system control, and more particularly to an energy-saving control method for a multifunctional heat pump heat recovery unit. Background Art

[0002] In the practical application of multifunctional heat pump heat recovery systems, there are several key technical challenges in effectively improving their year-round energy efficiency and functional synergy.

[0003] The first challenge lies in adapting the heat and cooling source modes. Such systems typically utilize both ambient air (air cooling) and relatively stable underground or water bodies (ground source). However, existing systems often struggle to intelligently select the most appropriate heat and cooling source mode based on real-time, changing ambient temperature conditions. Specifically, when ambient temperatures are low (e.g., near or below freezing), relying primarily on air cooling presents significant challenges: the heating efficiency of air-source heat pumps decreases significantly, and frost easily forms on the evaporator surface. This not only leads to insufficient heating capacity and a sharp increase in energy consumption, but frequent defrosting interrupts heating, impacting user comfort and increasing energy consumption. On the other hand, during periods of relatively mild or high ambient temperatures, ground source systems, while highly efficient and stable, typically have higher construction and operating costs than air cooling systems. Failure to effectively utilize air cooling in these situations and over-reliance on ground source heat pumps can result in uneconomical resource utilization. There are difficulties in achieving this intelligent and efficient switching of cold and heat source modes. The core lies in the need for a control logic that can accurately sense the ambient temperature status, reliably determine which cold and heat source mode is more optimal, and safely and smoothly execute mode switching to avoid the inefficiency and frosting of air cooling at low temperatures, and the redundant use of ground sources at suitable temperatures.

[0004] The second challenge involves clearly defining the functions of multiple heat exchangers and establishing a foundation for coordination. Multifunctional heat pump heat recovery systems integrate multiple functions, such as domestic hot water production, air conditioning cooling / heating, and ambient heat exchange, typically through multiple heat exchangers. However, existing systems often lack a clear understanding 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 the heat exchangers underlying different functions (such as domestic hot water heat recovery and user space cooling / heating) during system operation, leading to potential interference. For example, if the functional definitions of heat exchangers for compressor exhaust heat recovery, heat exchangers for connecting to geothermal sources, heat exchangers serving user end loads, and heat exchangers for conventional air-cooled heat exchange are ambiguous or overlapping, the refrigerant flow design and control strategies become complex and prone to conflicts when the system attempts to simultaneously meet multiple requirements (such as hot water production and cooling), making it difficult to achieve efficient independent operation or coordinated operation of each function. To establish a clear physical foundation for efficient multi-mode coordination, it is necessary to clearly define the primary responsibilities and roles of each heat exchanger in the system.

[0005] The third challenge focuses on dynamically coordinating the needs of multiple users in the air-cooled heat source mode. When the system operates primarily in air-cooled mode, it needs to simultaneously handle the potential and changing demands for domestic hot water production and user space cooling or heating. Existing systems, operating under air-cooled conditions, often struggle to dynamically and collaboratively manage these demands in real time based on the actual status of the domestic hot water temperature (e.g., whether it meets the set requirements) and the actual status of the user-side water temperature (e.g., whether it meets the cooling or heating set requirements). Common issues include: when the domestic hot water temperature already meets the requirements, the system may still perform unnecessary heat recovery processes, resulting in additional pump energy consumption and possible loss of primary function efficiency; conversely, when the domestic hot water temperature is insufficient and needs to be heated, 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 (when sufficient condensation heat is available), resulting in energy waste. A more complex situation arises when both domestic hot water demand and user-side cooling / heating demands are unmet. The question arises of how to efficiently integrate heat recovery into the main cooling or heating cycle to avoid conflicts in resource allocation (e.g., refrigerant flow and heat exchanger capacity). For example, excessive refrigerant heat consumption during heat recovery could lead to insufficient heating at the user end, or condensing heat dissipation (during cooling) could compete with hot water heating demand for refrigerant heat. The challenge of managing this dynamic coordination of multiple demands in air-cooled mode lies in the real-time monitoring of multiple key temperature points (domestic hot water temperature, user-side water temperature), accurately determining the respective demand status (on or off target), and designing control logic accordingly to determine whether to initiate 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 object of the present invention is to provide an energy-saving control method for a multifunctional heat pump heat recovery unit, which realizes the intelligent switching of ambient heat source and geothermal source, optimizes the 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] In order to achieve these objects and other advantages of the present invention, according to one aspect of the present invention, the present invention provides an energy-saving control method for a multifunctional heat pump heat recovery unit, the unit comprising a liquid reservoir, 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 reservoir, the compressor, and the first heat exchanger are sequentially connected, the outlet of the first heat exchanger is connected to the interface A 200 of the four-way valve, the interface B 201 of the four-way valve is sequentially connected to the fourth heat exchanger, the second heat exchanger, and the third heat exchanger, the outlet of the third heat exchanger is connected to the interface C 202 of the four-way valve, and the interface D 203 of the four-way valve is connected to the interface C 204 of the four-way valve. 203 is connected to the inlet of the liquid reservoir; 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 provided with a plurality of temperature sensors connected to the controller for detecting 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; The controller determines the target operating mode on the user demand side based on the change between the received real-time temperature detection value and the preset target temperature setting value, combined with the user's set requirements, and controls the corresponding heat exchanger and control valve to operate or close according to the refrigerant flow direction preset in the target operating mode, specifically: When T4≥T S4 At +S1, it is determined that the target operation mode on the user demand side is the air cooling and heating mode. The controller turns on the fan of the fourth heat exchanger, turns off the water pump of the second heat exchanger, closes the first control valve, and opens the second control valve. When T4<T S4 -S1, it is determined that the target operation mode on the user demand side is the ground source heat pump heating mode, the controller controls to turn on the water pump of the second heat exchanger, turn off the fan of the fourth heat exchanger, open the first control valve, and close the second control valve; When T4<T X4 -S1, it is determined that the target operation mode on the user demand side is the air-cooling operation mode, and 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 close and the second control valve to open; When T4≥T X4At +S1, it is determined that the target operation mode on the user demand side is the ground source heat pump cooling 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 open and the second control valve to close. Among them, 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.

[0008] Preferably, the first heat exchanger is a domestic hot water heat exchanger, which is used for heating domestic hot water and recovering compressor exhaust heat; the second heat exchanger is a ground source heat pump heat exchanger, which is used to replace air-cooled heat exchange under low temperature conditions to prevent frost; the third heat exchanger is a user-side cooling / heating heat exchanger, which provides cooling or heating services for the user end; the fourth heat exchanger is an air-cooled ambient heat exchanger, which is used for heat exchange with air under normal conditions to provide an ambient cold and heat source.

[0009] Preferably, the target operating mode further includes: The controller is based on the outlet water temperature T of the domestic hot water side of the first heat exchanger. 1H , user side outlet water temperature of the third heat exchanger T 3H , preset target hot water temperature T R And the user side water outlet set temperature T 3S Do the following: When T4<T X4 -S1, T 1H ≥T R -S2 and T 3H ≥T 3S -S3, it is determined that the target operation mode on the user demand side is the air-cooled pure cooling 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, passes through the fourth and third heat exchangers in sequence, and flows back to the liquid reservoir; When T4≥T S4 +S1,T 1H ≥T R -S2 and T 3H <T 3S -S3, it is determined that the target operation mode on the user demand side is the air-cooling and heating-only 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, passes through the third and fourth heat exchangers in sequence, and flows back to the liquid reservoir; When T4<T X4 -S1, T 1H <T R -S2 and T3H ≥T 3S -S3, it is determined that the target operation mode on the user demand side is the air-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, closes the second heat exchanger, closes the first control valve and the third control valve, and opens 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 reservoir; When T4≥T S4 +S1,T 1H <T R -S2 and T 3H <T 3S -S3, it is determined that the target operation mode on the user demand side is the air-cooling and heating domestic hot water mode. The controller controls the opening of the first heat exchanger, the third heat exchanger, and the fourth heat exchanger, closes the second heat exchanger, closes the first control valve and the third control valve, and opens 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 reservoir; Wherein, S2 is the second preset deviation value, S3 is the third preset deviation value, T 3S Automatically select the set temperature according to the current operating mode: T 3S =T 3Sx , in heating mode, T 3S =T 3Sd .

[0010] Preferably, the target operating mode further includes: When T4≥T X4 +S1,T 1H ≥T R -S2 and T 3H ≥T 3S -S3, it is determined that the target operation mode on the user demand side is the pure cooling mode of the ground source heat pump. 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, passes through the second and third heat exchangers in sequence, and flows back to the liquid reservoir; When T4<T S4 -S1, T 1H ≥T R -S2 and T 3H <T 3S -S3, it is determined that the target operation mode on the user demand side is the ground source heat pump pure heating mode. The controller controls the second and third heat exchangers to open, the first and fourth heat exchangers to close, the first control valve and the third control valve to open, and the second control valve to close, so that the refrigerant flows out of the compressor, flows through the third heat exchanger, the second heat exchanger in sequence, and flows back to the liquid reservoir; When T4<TX4 -S1, T 1H <T R -S2 and T 3H ≥T 3S -S3, it is determined that the target operation mode on the user demand side is 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, closes the fourth heat exchanger, opens the first control valve, and closes the second control valve and the third control valve, so that the refrigerant flows out of the compressor, flows through the first heat exchanger, the second heat exchanger, the third heat exchanger in sequence, and flows back to the liquid reservoir; When T4<T S4 -S1, T 1H <T R -S2 and T 3H <T 3S -S3, it is determined that the target operating mode on the user demand side is the ground source heat pump heating domestic hot water mode. The controller controls the opening of the first heat exchanger, the second heat exchanger and the third heat exchanger, closes the fourth heat exchanger, opens the first control valve, closes the second control valve and the third control valve, so that the refrigerant flows out of the compressor and flows through the first heat exchanger, the third heat exchanger, the second heat exchanger in sequence and flows back to the liquid reservoir.

[0011] Preferably, the first preset deviation value S1, the second preset deviation value S2, and the third preset deviation value S3 are determined 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 by the coefficient C1, where 5≤N≤10, 0.2≤C1≤0.3; Run the cooling and heating modes under standard working conditions and record the following: Domestic hot water temperature fluctuation range ΔT2 = max (T 1H )-min(T 1H ), user side water temperature fluctuation range ΔT3=max(T 3H )-min(T 3H ), take the initial value of S2 = C2×ΔT2, the initial value of S3 = C3×ΔT3, where 0.6≤C2≤0.9, 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 .

[0012] Preferably, the controller dynamically adjusts the values ​​of S1, S2, and S3 according to the intensity of ambient temperature fluctuation and load conflict intensity: Calculate the absolute value of the ambient temperature change rate δ=|ΔT4 / Δt| in real time, and update the first preset deviation value S1 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; Among them, γ is the preset environmental mutation sensitivity, ranging from 0.05 to 0.2; β is the preset cooling and heating load conflict threshold, ranging from 20 to 30°C; k and m are preset coefficients, k is 0.8, and m is 1.2.

[0013] Preferably, the initial opening of the expansion valve is dynamically set according to the target operation mode: For air-cooled pure cooling mode and ground-source heat pump pure cooling mode: θ0=30%+0.4×(T4-35)%, 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)%, the opening degree is 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%.

[0014] Preferably, the expansion valve opening control implements a dual-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 + ΔT1, reduce the initial opening of the expansion valve by 5%-15%; When T 2H <T set -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 temperature at the outlet of the second heat exchanger to meet the requirement of 5℃≤T set ≤45℃; ΔT1 is the temperature dead zone threshold, which satisfies 0.5℃≤ΔT1≤2.0℃; P set Set the pressure at the inlet of the third heat exchanger to meet the requirement of 0.5MPa≤Pset ≤4.0MPa; ΔP is the pressure dead zone threshold, satisfying 0.05MPa≤ΔP≤0.2MPa.

[0015] Preferably, the controller generates an opening adjustment instruction by integrating the temperature deviation and the pressure deviation according to a preset weight ratio; Define the basic weight calculation function: α base = 0.5+0.01×︱T R -T 3S ︱; Execute weight clipping: If α base <0.5, then α=0.5; if α base >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 forced to be set.

[0016] The present invention has at least the following beneficial effects: By monitoring the ambient temperature in real time and comparing it with a preset ambient setpoint, the system intelligently determines and automatically switches between air-cooling mode and ground-source heat pump mode. This effectively addresses the issue of poor environmental adaptability: when the ambient temperature is suitable, air-source heat exchange is prioritized, reducing reliance on the ground-source system. When the ambient temperature is too low, the system automatically switches to the more stable and efficient ground-source heat exchange mode, significantly reducing the risk of energy loss and frost formation in air-cooling mode at low temperatures, thereby improving overall energy efficiency year-round. The method clearly defines the functional roles of each heat exchanger, providing a clear physical foundation for the system to simultaneously handle multiple tasks, including domestic hot water heating, user-side cooling and heating, and ambient heat exchange. Furthermore, the method integrates the real-time status of the actual domestic hot water temperature and target temperature, as well as the user-side water temperature and setpoint temperature, to finely distinguish between multiple operating sub-modes (such as pure cooling, pure heating, simultaneous cooling and hot water production, and simultaneous heating and hot water production). By precisely controlling the opening and closing states of multiple bypass valves, refrigerant flow can be precisely directed. When domestic hot water demand is met, the relevant bypass valves are promptly closed to avoid unnecessary heat recovery energy consumption. When user-side loads meet standards, primary operation is prioritized. When both domestic hot water and user-side loads require replenishment, a heat recovery heat exchanger is intelligently integrated in series with the main circulation, efficiently utilizing compressor exhaust heat. This effectively resolves potential conflicts between heat recovery and primary cooling / heating functions. This method also dynamically sets and optimizes key temperature difference thresholds based on historical environmental data and actual system performance, tailoring them to specific regional climates and unit characteristics, avoiding mode misjudgments or response delays caused by fixed thresholds. Furthermore, the system can detect rapid changes in ambient temperature and the potential conflict between domestic hot water demand and air conditioning loads, dynamically fine-tuning relevant thresholds accordingly. This enhances the system's adaptability to sudden changes, effectively mitigates control fluctuations during load conflicts, and improves operational stability. The initial opening of the expansion valve is pre-set within a reasonable range for different operating modes, providing an optimal refrigerant flow starting point for each operating condition and accelerating system regulation. During operation, the opening of the expansion valve is also subject to dual closed-loop feedback regulation of the ground source side outlet temperature and the user side inlet pressure, which not only ensures the ground source heat exchange efficiency, but also maintains the safety of the compressor operation. The system comprehensively weighs the priority of temperature and pressure parameters through intelligent algorithms, and focuses on pressure protection when high-pressure risks are detected, thus achieving a dynamic balance between system energy efficiency and operational safety. In summary, this method significantly improves the energy utilization efficiency and overall operational reliability of the heat pump system under complex and changeable working conditions through intelligent environmental perception, multi-demand collaborative decision-making, dynamic parameter optimization and precise control of actuators.

[0017] Other advantages, objectives and features of the present invention will be reflected in part from the following description and will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a structural schematic diagram of the unit described in one technical solution of the present invention.

[0019] Figure 2 This is a schematic diagram of the operation of the air-cooled pure refrigeration mode in Example 1 of the present invention.

[0020] Figure 3 This is a schematic diagram of the operation of the air-cooled pure heating mode in Example 2 of the present invention.

[0021] Figure 4 This is a schematic diagram of the operation of the air-cooled domestic hot water mode in Example 3 of the present invention.

[0022] Figure 5 This is a schematic diagram of the operation of the air-cooling and heating domestic hot water mode in Example 4 of the present invention.

[0023] Figure 6 This is a schematic diagram of the operation of the ground source pure cooling mode in Example 5 of the present invention.

[0024] Figure 7 This is a schematic diagram of the operation of the ground source pure heating mode in Example 6 of the present invention.

[0025] Figure 8 This is a schematic diagram of the operation of the ground source cooling and domestic hot water mode in Example 7 of the present invention.

[0026] Figure 9 This is a schematic diagram of the operation of the ground source heating domestic hot water mode in Example 8 of the present invention. DETAILED DESCRIPTION

[0027] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can implement the invention with reference to the description.

[0028] It should be understood that terms such as “having”, “including” and “comprising” used herein do not preclude the existence or addition of one or more other elements or combinations thereof.

[0029] like Figure 1As shown, the present invention provides an energy-saving control method for a multifunctional heat pump heat recovery unit, the unit comprising a liquid reservoir 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; wherein the liquid reservoir 100, the compressor 101 and the first heat exchanger 103 are sequentially connected, the outlet of the first heat exchanger 103 is connected to the interface A 200 of the four-way valve 102, the 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 the interface C 202 of the four-way valve 102, and the interface D 201 of the four-way valve 102 is connected to the fourth heat exchanger 106, the second heat exchanger 104 and the third heat exchanger 105. 203 is connected to the inlet of the liquid reservoir 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 provided with a plurality of temperature sensors connected to the controller for detecting the outlet water temperature and return water temperature 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; The controller determines the target operating mode on the user demand side based on the change between the received real-time temperature detection value and the preset target temperature setting value, combined with the user's set requirements, and controls the corresponding heat exchanger and control valve to operate or close according to the refrigerant flow direction preset in the target operating mode, specifically: When T4≥T S4 At +S1, it is determined that the target operation mode on the user demand side is the air cooling and heating mode. The controller turns on the fan of the fourth heat exchanger, turns off the water pump of the second heat exchanger, closes the first control valve, and opens the second control valve. When T4<T S4 -S1, it is determined that the target operation mode on the user demand side is the ground source heat pump heating mode, the controller controls to turn on the water pump of the second heat exchanger, turn off the fan of the fourth heat exchanger, open the first control valve, and close the second control valve; When T4<T X4 At -S1, it is determined that the target operation mode on the user demand side is the air-cooling operation mode. The controller controls the fan of the fourth heat exchanger to be turned on, the water pump of the second heat exchanger to be turned off, the first control valve to be closed, and the second control valve to be opened. When T4≥T X4 At +S1, it is determined that the target operation mode on the user demand side is the ground source heat pump cooling 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 open and the second control valve to close. Among them, T4 is the current ambient temperature; TS4 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.

[0030] In this technical solution, the unit includes a liquid reservoir 100, a compressor 101, a four-way valve 102, and four heat exchangers. The outlet of the liquid reservoir 100 is connected to the inlet of the compressor 101, which in turn 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 reservoir 100. The liquid reservoir 100 can be a stainless steel pressure vessel; the compressor 101 can be a scroll refrigeration compressor 101; the four-way valve 102 can be a four-way electromagnetic reversing valve; and the heat exchanger can be a brazed plate heat exchanger or a copper tube and aluminum fin heat exchanger. The copper tubes can be made of TP2 copper, and the aluminum fins can be made of hydrophilic aluminum foil. The liquid accumulator 100 is mounted on the unit chassis bracket; the compressor 101 is fixed to the shock-absorbing base; the four-way valve 102 is placed above the outlet pipe of compressor 101; the heat exchangers are mounted side by side inside the unit casing via brackets, and the interfaces are welded in the above order.

[0031] A first control valve 300 is connected in parallel at both ends of the refrigerant pipeline for the fourth heat exchanger 106. A second control valve 301 is connected in parallel at both ends of the second heat exchanger 104. A third control valve 302 is connected in parallel at both ends of the first heat exchanger 103. An expansion valve 303 is installed in the pipeline between the second heat exchanger 104 and the third heat exchanger 105. A DN20 solenoid on-off valve can be used as the control valve, and an electronic expansion valve can be used as the expansion valve 303. The initial opening of the expansion valve 303 is preset according to the operating mode, and the control valve response time does not exceed 1 second. The first control valve 300 is connected to the inlet and outlet pipes of the fourth heat exchanger 106, respectively. The second control valve 301 is installed in the parallel bypass pipe of the second heat exchanger 104. The third control valve 302 is installed in the parallel bypass pipe of the first heat exchanger 103. The expansion valve 303 is installed in the main pipeline from the outlet of the second heat exchanger 104 to the inlet of the third heat exchanger 105.

[0032] Temperature sensors are placed 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 position of the fourth heat exchanger 106, and the ambient space. The controller collects temperature data in real time and performs operations: the first preset deviation value is set to 2°C, and the preset winter ambient setting temperature T S4 Set to 7℃; the control valve opening or closing logic is: Winter T S4=7℃, S1=2℃, turn on the ground source heat pump when T4 is less than 5℃, turn on the air cooling heat pump when it is greater than 9℃. S4 =37°C, S1=2°C, the ground source heat pump is turned on when T4≥35°C+2°C, and the air-cooled heat pump is turned on when T4<35°C-2°C. A PT1000 platinum resistance thermometer can be used as the temperature sensor, and an industrial PLC can be used as the controller.

[0033] This technical solution achieves automatic switching between cooling and heating source modes through structured connections and temperature threshold control. This prevents efficiency loss and frost formation in 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 the system's components ensures reliable execution of control commands.

[0034] In another technical solution, the first heat exchanger 103 is a domestic hot water heat exchanger, which is used to heat domestic hot water and recover the exhaust heat of the compressor 101; the second heat exchanger 104 is a ground source heat pump heat exchanger, which is used to replace air-cooled heat exchange under low-temperature conditions to prevent frost; the third heat exchanger 105 is a user-side cooling / heating heat exchanger, which provides cooling or heating services for the user end; the fourth heat exchanger 106 is an air-cooled ambient heat exchanger, which is used to exchange heat with the air under normal conditions to provide an ambient cold and heat source.

[0035] In this technical solution, the first heat exchanger 103 is defined as a domestic hot water heat exchanger, which is used to recover the exhaust heat 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, the inlet is connected to tap water or a water tank, and the outlet supplies a hot water point. The heat exchanger can use a brazed plate heat exchanger, and the plate material can be 316L stainless steel to resist domestic water corrosion. The assembly position is close to the exhaust port of the compressor 101, shortening the high-temperature refrigerant transportation distance to reduce heat loss. During operation, the high-temperature refrigerant flows through the gap between the plates and transfers heat to the domestic water flowing on the other side. When the typical inlet water temperature is 15 degrees Celsius, the hot water can be heated to 45-55 degrees Celsius.

[0036] The second heat exchanger 104 is used as a ground source heat pump heat exchanger. Under the heating condition, the ground source heat pump operates in the heating mode (T4<T S4 -S1) to replace air cooling heat exchange to prevent frost; in cooling conditions, the local source heat pump operates in cooling mode (T4≥T X4 + S1) provides ground source heat dissipation, and its pipeline is connected to the buried pipe or groundwater system; the fourth heat exchanger 106 is used as an air-cooled environment heat exchanger, and in the heating condition, when the air-cooled operation heating mode (T4 ≥ T S4 +S1) as an evaporator to absorb heat; in cooling conditions, when the air cooling mode is running (T4<T X4-S1) acts as a condenser to dissipate heat. The second heat exchanger 104 can be a shell-and-tube heat exchanger, and the tube material can be copper-nickel alloy to resist groundwater corrosion. The fourth heat exchanger 106 can be a copper-tube aluminum-fin 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 groundwater well via 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 below the set threshold, the second heat exchanger 104 starts the water pump to circulate the antifreeze on the groundwater side. When the ambient temperature is suitable, the fan in the fourth heat exchanger 106 drives air through the fin tubes to achieve heat exchange.

[0037] The third heat exchanger 105 is a user-side cooling and heating heat exchanger connected to the air conditioner's terminal water line. Its refrigerant side is connected to the second heat exchanger 104 via an expansion valve 303. Its water inlet is connected to the air conditioner's return pipe, and its outlet is connected to the air conditioner's supply pipe. This heat exchanger can be a high-efficiency microchannel heat exchanger, and its flat tubes can be made of aluminum alloy. It is installed near the unit's control panel for easy access to the user's water pipe.

[0038] During operation: the local heat pump operates in heating mode (T4<T S4 -S1) or ground source heat pump operation cooling mode (T4 ≥ T X4 + S1) is triggered, the second heat exchanger 104 starts the water pump to circulate the antifreeze liquid. When the air cooling operation is in heating mode (T4 ≥ T S4 +S1) or air cooling mode (T4<T X4 -S1) is triggered, the fan of the fourth heat exchanger 106 drives the air to exchange heat. In the test, when the ambient temperature T4 = 3℃ (T S4 =5℃, S1=1℃) and the user's heating demand starts, the ground source heat pump operation heating mode conditions are met (T4<T S4 -S1), the system automatically turns off the fan of the fourth heat exchanger 106 and turns on the water pump of the second heat exchanger 104 to avoid air cooling and frosting problems.

[0039] This technical solution clearly demarcates the functional boundaries of the heat exchanger, creating independent physical channels for domestic hot water recovery, ground-source frost protection, user energy supply, and conventional air-cooled heat exchange. This configuration eliminates cross-functional interference and provides a foundation for multi-mode collaborative operation.

[0040] In another technical solution, the target operating mode further includes: The controller is based on the outlet water temperature T of the domestic hot water side of the first heat exchanger 103. 1H , 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 Do the following: When T4<T X4 -S1, T 1H ≥T R -S2 and T 3H ≥T 3S At -S3, it is determined that the target operation mode on the user demand side is the air-cooled pure cooling mode. The controller controls the third heat exchanger 105 and the fourth heat exchanger 106 to be opened, the first heat exchanger 103 and the second heat exchanger 104 to be closed, the second control valve 301 and the third control valve 302 to be opened, and the first control valve 300 to be closed, 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 reservoir 100; When T4≥T S4 +S1,T 1H ≥T R -S2 and T 3H <T 3S At -S3, it is determined that the target operation mode on the user demand side is the air-cooling-only heating mode. The controller controls the third heat exchanger 105 and the fourth heat exchanger 106 to be opened, the first heat exchanger 103 and the second heat exchanger 104 to be closed, the second control valve 301 and the third control valve 302 to be opened, and the first control valve 300 to be closed, so that the refrigerant flows out of the compressor 101, passes through the third heat exchanger 105 and the fourth heat exchanger 106 in sequence, and flows back to the liquid reservoir 100; When T4<T X4 -S1, T 1H <T R -S2 and T 3H ≥T 3S At -S3, it is determined that the target operation mode on the user demand side is the air-cooling and domestic hot water mode. The controller controls the first heat exchanger 103, the third heat exchanger 105, and the fourth heat exchanger 106 to be opened, the second heat exchanger 104 to be closed, the first control valve 300 and the third control valve 302 to be closed, and the second control valve 301 to be opened, so that the refrigerant flows out of the compressor 101, passes 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 reservoir 100; When T4≥T S4 +S1,T 1H <T R -S2 and T 3H <T 3S At -S3, it is determined that the target operation mode on the user demand side is the air-cooling and heating domestic hot water mode. The controller controls the first heat exchanger 103, the third heat exchanger 105, and the fourth heat exchanger 106 to be opened, the second heat exchanger 104 to be closed, the first control valve 300 and the third control valve 302 to be closed, and the second control valve 301 to be opened, so that the refrigerant flows out of 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 reservoir 100; Wherein, S2 is the second preset deviation value, S3 is the third preset deviation value, T 3S Automatically select the set temperature according to the current operating mode: T 3S =T 3Sx , in heating mode, T 3S =T 3Sd .

[0041] In this technical solution, when the absolute value of the difference between the ambient temperature and the preset ambient setpoint temperature is greater than or equal to a first preset deviation value (typically 2 degrees Celsius), the measured domestic hot water temperature is higher than the domestic hot water setpoint temperature minus a second preset deviation value (typically 2 degrees Celsius), and the user-side outlet water temperature is higher than the user-side setpoint temperature minus a third preset deviation value (typically 1 degree Celsius), the controller determines that the system is in air-cooled, pure cooling mode. At this point, the controller closes the water valve on the first heat exchanger 103 and the third control valve 302, and opens the second control valve 301 and the water pump on the third heat exchanger 105. The refrigerant flows in the following direction: compressor 101 → fourth heat exchanger 106 (heat dissipation) → third heat exchanger 105 (heat absorption) → liquid reservoir 100. If the user-side outlet water temperature is lower than the setpoint minus the third preset deviation value, the system is 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).

[0042] When the absolute difference between the ambient temperature and the preset ambient setpoint temperature is greater than or equal to the first preset deviation value, the measured domestic hot water temperature is lower than the setpoint minus the second preset deviation value, but the user-side outlet water temperature meets the standard (higher than the setpoint 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 the following: compressor 101 → first heat exchanger 103 (heating domestic hot water) → fourth heat exchanger 106 (auxiliary heat dissipation) → third heat exchanger 105 (absorbing cold water for cooling) → liquid reservoir 100.

[0043] When the absolute difference between the ambient temperature and the preset ambient setpoint temperature is greater than or equal to a first preset deviation value, and both the domestic hot water and user-side water temperatures fall below the specified range, the air-cooled heating domestic hot water mode is activated. The controller maintains the third control valve 302 closed, and the refrigerant flows as follows: compressor 101 → first heat exchanger 103 (preferential heating of domestic hot water) → third heat exchanger 105 (secondary heating of air-conditioning water) → fourth heat exchanger 106 (heat absorption balance) → liquid reservoir 100.

[0044] Using dual criteria, both domestic hot water temperature and user-side water temperature, the system achieves on-demand coordination between the cooling / heating primary function and domestic hot water recovery in air-cooled mode. When sufficient hot water is available, the recovery path is closed to reduce pump consumption. When both hot water and domestic hot water are in demand, the refrigerant flow path is optimized to improve waste heat utilization and avoid temperature fluctuations caused by functional conflicts.

[0045] In another technical solution, the target operating mode further includes: When T4≥T X4 +S1,T 1H ≥T R -S2 and T 3H ≥T 3S -S3, it is determined that the target operation mode on the user demand side is the ground source heat pump pure cooling mode. The controller controls the second heat exchanger 104 and the third heat exchanger 105 to be opened, the first heat exchanger 103 and the fourth heat exchanger 106 to be closed, the first control valve 300 and the third control valve 302 to be opened, and the second control valve 301 to be closed, 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 reservoir 100; When T4<T S4 -S1, T 1H ≥T R -S2 and T 3H <T 3S -S3, it is determined that the target operation mode on the user demand side is the ground source heat pump pure heating mode. The controller controls the second heat exchanger 104 and the third heat exchanger 105 to be opened, the first heat exchanger 103 and the fourth heat exchanger 106 to be closed, the first control valve 300 and the third control valve 302 to be opened, and the second control valve 301 to be closed, 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 reservoir 100; When T4<T X4 -S1, T 1H <T R -S2 and T 3H ≥T 3S At -S3, it is determined that the target operation mode on the user demand side is the ground source heat pump cooling and domestic hot water mode. The controller controls the first heat exchanger 103, the second heat exchanger 104, and the third heat exchanger 105 to be opened, the fourth heat exchanger 106 to be closed, the first control valve 300 to be opened, and the second control valve 301 and the third control valve 302 to be closed. The refrigerant flows out of the compressor 101, passes through the first heat exchanger 103, the second heat exchanger 104, the third heat exchanger 105 in sequence, and flows back to the liquid reservoir 100; When T4<T S4 -S1, T 1H <T R -S2 and T 3H <T 3S-S3, it is determined that the target operating mode on the user demand side is the ground source heat pump heating domestic hot water mode, and the controller controls the opening of the first heat exchanger 103, the second heat exchanger 104 and the third heat exchanger 105, closing the fourth heat exchanger 106, opening the first control valve 300, closing the second control valve 301 and the third control valve 302, so that the refrigerant flows out of the compressor 101 and flows through the first heat exchanger 103, the third heat exchanger 105, the second heat exchanger 104 in sequence and flows back to the liquid reservoir 100.

[0046] In this technical solution, when the absolute value of the difference between the ambient temperature and the preset ambient set 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): If the user-side outlet water temperature meets the standard (above the set value minus a third preset deviation value of 1°C), the ground-source pure cooling mode is activated. The controller closes the water valve on the first heat exchanger 103 and the third control valve 302, then opens the first control valve 300. The refrigerant flows in the following direction: compressor 101 → second heat exchanger 104 (ground-source heat dissipation) → third heat exchanger 105 (cooling absorption for cooling) → liquid reservoir 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 the reverse direction through the third heat exchanger 105 (heat release) → second heat exchanger 104 (ground-source heat absorption).

[0047] When the absolute difference between the ambient temperature and the preset ambient setpoint temperature is less than the first preset deviation value, the domestic hot water temperature is lower than the setpoint 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 through the following sequence: 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 for cooling) → liquid reservoir 100.

[0048] When the absolute difference between the ambient temperature and the preset ambient setpoint temperature is less than a first preset deviation value, and both the domestic hot water and user-side water temperatures do not meet the standards, the ground-source heating domestic hot water mode is activated. The controller closes the second and third control valves 301 and 302, and the refrigerant flows as follows: 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) → reservoir 100. By combining the status of domestic hot water (DHW) and user-side water temperature under ground source conditions, efficient synergy between geothermal heat generation and waste heat recovery is achieved. In pure mode, redundant heat exchange paths are shut down for energy savings. In hybrid mode, DHW and primary heat exchangers are connected in series, ensuring that DHW demand is prioritized while maintaining stable user-side temperatures, avoiding functional conflicts between the ground source system and heat recovery.

[0049] In another technical solution, the first preset deviation value S1, the second preset deviation value S2, and the third preset deviation value S3 are determined 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 by the coefficient C1, where 5≤N≤10, 0.2≤C1≤0.3; Run the cooling and heating modes under standard working conditions and record the following: Domestic hot water temperature fluctuation range ΔT2 = max (T 1H )-min(T 1H ), user side water temperature fluctuation range ΔT3=max(T 3H )-min(T 3H ), take the initial value of S2 = C2×ΔT2, the initial value of S3 = C3×ΔT3, where 0.6≤C2≤0.9, 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 .

[0050] In this technical solution, ambient temperature data is collected for seven consecutive days (24 sets of data are recorded daily) and the maximum daily temperature difference is calculated (maximum temperature minus minimum temperature). The arithmetic mean of the seven-day maximum temperature difference is taken (for example, the average of 8.2°C, 9.5°C, and 7.8°C is 8.5°C), multiplied by a coefficient of 0.2, to obtain an initial S1 value of 1.7°C. Data is collected using an installed ambient temperature sensor, and the controller automatically stores and calculates the data. In practice, if the average maximum temperature difference between spring and autumn in a certain region is 10°C, the initial S1 value is set to 2°C. This setting method ensures that S1 is consistent with local climate characteristics and avoids erroneous switching caused by fixed thresholds.

[0051] Run the system in cooling-only mode for 2 hours under standard cooling conditions (ambient dry-bulb temperature 35°C) and record the domestic hot water temperature fluctuation (e.g., 45.3°C to 46.1°C, ΔT2 = 0.8°C). Multiply ΔT2 by a factor of 0.8 to obtain an initial S2 value of 0.64°C (rounded to 1°C). Run the system in heating-only mode under standard heating conditions (ambient dry-bulb temperature 7°C) and record the user-side water temperature fluctuation (e.g., 44.5°C to 45.2°C, ΔT3 = 0.7°C). Multiply ΔT3 by a factor of 0.8 to obtain an initial S3 value of 0.56°C (rounded to 1°C). A PT1000 temperature sensor was used for this test, with a data sampling interval of 10 seconds.

[0052] The controller stores the determined initial values ​​for S1, S2, and S3 (for example, 2°C, 1°C, and 1°C) in non-volatile memory. These thresholds are then used in real-time during operation to determine the mode. The stored data includes the set timestamp and calculated original values, supporting traceability for later calibration. Implementation example: When the system is first started, it automatically performs five days of environmental data collection (N=5) and a one-hour standard operating condition test to initialize and store the thresholds.

[0053] Thresholds are set based on historical environmental data and measured temperature fluctuations, ensuring that mode switching criteria are more closely aligned with actual system characteristics and regional climate. This dynamic initialization process mitigates biases inherent in manual settings and improves the accuracy of the synergy between environmental mode switching and heat recovery.

[0054] In another technical solution, the controller dynamically adjusts the values ​​of S1, S2, and S3 according to the intensity of ambient temperature fluctuation and load conflict intensity: Calculate the absolute value of the ambient temperature change rate δ=|ΔT4 / Δt| in real time, and update the first preset deviation value S1 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; Among them, γ is the preset environmental mutation sensitivity, ranging from 0.05 to 0.2; β is the preset cooling and heating load conflict threshold, ranging from 20 to 30°C; k and m are preset coefficients, k is 0.8, and m is 1.2.

[0055] This technical solution calculates the ambient temperature change rate in real time. Ambient temperature data is collected every minute and the absolute change compared to the previous minute is calculated (for example: 5°C in the first minute, 3°C in the second minute, rate of change δ = 2°C / min). If δ exceeds 1°C / min for two consecutive minutes, the first preset deviation value S1 is updated from the initial value of 1°C to S1' = 1 × (1 + 0.1 × 2) = 1.2°C. The adjustment coefficient γ is set to 0.1 (within the range of 0.05-0.2). Implementation example: In spring, when the ambient temperature suddenly drops from 8°C to 2°C (δ = 6°C / h), the system automatically increases S1 from 1°C to 1.6°C, triggering a switch to ground-source mode in advance to prevent frost risk.

[0056] Real-time calculation of domestic hot water set temperature (T R =45℃) and the user-side set temperature (T 3S =40℃) with an absolute difference of α=5℃. The default 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 of the original value (S2 is adjusted from 2℃ to 1.6℃, S3 is adjusted from 1℃ to 0.8℃); when α≤β (for example, T R =45℃, T 3S =40℃, α=5℃), increase S2 and S3 to 1.2 times their original values ​​(S2=2.4℃, S3=1.2℃). The coefficient k is 0.8 and m is 1.2.

[0057] When the inlet pressure of the third heat exchanger 105 exceeds the set value (P set =3.0MPa) 0.1MPa (ΔP=0.2MPa), the pressure weight β=0.8 and the temperature weight α=0.2 are set compulsorily. Under normal working conditions, the weight is α=0.5+0.01×|T R -T 3S |Calculation (for example, |45-40| = 5°C, α = 0.55), pressure weight β = 0.45. During implementation, a cooling water failure suddenly occurred in the cooling mode, causing the pressure to rise to 3.3 MPa. The system automatically increased the pressure regulation weight to 80% and rapidly opened expansion valve 303 to relieve pressure.

[0058] Enhanced sensitivity to environmental changes and adaptive adjustment of load conflicts mitigate control oscillations caused by rigid temperature thresholds. High-pressure operating conditions prioritize pressure protection, balancing system efficiency and operational safety. Dynamic adjustment mechanisms enhance stability under complex operating conditions.

[0059] In another technical solution, the initial opening of the expansion valve 303 is dynamically set according to the target operation mode: For air-cooled pure cooling mode and ground-source heat pump pure cooling mode: θ0=30%+0.4×(T4-35)%, 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)%, the opening degree is 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%.

[0060] 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%, with dynamic compensation based on ambient temperature: when the ambient temperature is above 35°C, the opening increases by 0.4% for every 1°C increase; when the ambient temperature is below 35°C, the opening decreases by 0.4% for every 1°C decrease. The final opening is limited to between 25% and 45%. For example, at an ambient temperature of 38°C, the calculated opening is 30% + 0.4 × (38-35)% = 31.2%; at an ambient temperature of 30°C, the calculated opening is 30% + 0.4 × (30-35)% = 28%. Expansion valve 303 can be an electronic expansion valve driven by a stepper motor, and the valve body can be made of H62 brass. It is installed in the main line from the outlet of the second heat exchanger 104 to the inlet of the third heat exchanger 105.

[0061] For air-cooled heating-only mode and ground-source heat pump heating-only mode, the initial opening of expansion valve 303 is set to a base value of 40%. This is compensated for the ambient temperature drop: for every degree Celsius below 0°C, the opening increases by 0.6%. For every degree Celsius increase in ambient temperature above 0°C, the opening decreases by 0.6%. The opening range is limited to 35% to 55%. For example, at an ambient temperature of -3°C, the opening is 40% + 0.6 × [0 - (-3)]% = 41.8%; at an ambient temperature of 5°C, the opening is 40% + 0.6 × (0 - 5)% = 37%.

[0062] For the operation mode with domestic hot water recovery (air cooling / ground source cooling and heating domestic hot water mode), the initial opening is set to 35% of the basic value, and the domestic hot water set temperature (T R ) and the user-side set temperature (T 3S ) absolute difference compensation: increase the opening by 3% for every 10 degrees Celsius difference. The opening is limited to 30% to 50%. For example, T R =45℃、T 3S =40℃, |45-40|=5℃, 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%. Install a filter screen at the inlet of expansion valve 303. The material can be 304 stainless steel wire mesh.

[0063] The initial opening of the expansion valve 303 is preset based on the specific operating mode, providing an optimal flow starting point for cooling, heating, and heat recovery. Dynamic compensation for ambient temperature and load differences shortens system stabilization time and reduces energy consumption during regulation. An opening limiter design mitigates the risk of flow loss.

[0064] In another technical solution, the opening control of the expansion valve 303 implements a dual-parameter feedback mechanism: 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; When T 2H >T set + ΔT1, the initial opening of the expansion valve 303 is reduced by 5%-15%; When T 2H <T set -ΔT1, the initial opening of the expansion valve 303 is increased by 5%-15%; When P>P set When +ΔP, the initial opening of the expansion valve 303 is increased by 5%-15%; When P<P set When -ΔP, the initial opening of the expansion valve 303 is reduced by 5%-15%; Among them, T set Set the outlet temperature of the second heat exchanger 104 to meet the requirement of 5℃≤T set ≤45℃; ΔT1 is the temperature dead zone threshold, which satisfies 0.5℃≤ΔT1≤2.0℃; P set Set the pressure at the inlet of the third heat exchanger 105 to meet the requirement of 0.5MPa≤P set ≤4.0MPa; ΔP is the pressure dead zone threshold, satisfying 0.05MPa≤ΔP≤0.2MPa.

[0065] In this technical solution, the outlet temperature of the second heat exchanger 104 (T 2H ), set the reference value T set =15℃ (cooling mode) or 40℃ (heating mode), dead zone threshold ΔT1 = 1℃. 2H Stay above T for 5 minutes set +ΔT1 (e.g. 16°C), reduce the opening of the expansion valve 303 by 10%; when T 2H Stay below T for 5 minutes set When the temperature is -ΔT1 (e.g. 14°C), increase the opening by 10%. The temperature sensor can be a PT100 platinum resistor, encapsulated in the insulation layer of the outlet pipe of the second heat exchanger 104, and the probe contacts the outer wall of the refrigerant pipe. Test case: The return water temperature on the ground source side rises abnormally to 18°C ​​(T set =15℃), the system automatically reduces the opening of the expansion valve 303 from 40% to 36% to restore the heat exchange efficiency.

[0066] Real-time monitoring of the inlet pressure (P) of the third heat exchanger 105, setting the reference value P set=2.8MPa (cooling mode) or 2.2MPa (heating mode), dead zone threshold ΔP=0.1MPa. When P is higher than P for 2 minutes set +ΔP (e.g. 2.9MPa), increase the opening of the expansion valve 303 by 12%; when P is lower than P for 2 minutes set When the pressure drops below -ΔP (e.g., 2.1 MPa), reduce the opening by 12%. A piezoresistive pressure transmitter with a range of 0-4.0 MPa can be used as the pressure sensor. The interface should be installed in the 0.5-meter straight pipe section before the refrigerant inlet of the third heat exchanger 105. The temperature deadband threshold ΔT1 is set to 0.8°C, 1.0°C, or 1.5°C (typical value 1.0°C), and the pressure deadband threshold ΔP is set to 0.08 MPa, 0.10 MPa, or 0.15 MPa (typical value 0.10 MPa). The threshold selection is based on the accuracy of the pipeline sensor: for a temperature sensor error of ±0.3°C, ΔT1 ≥ 0.8°C; for a pressure sensor error of ±0.02 MPa, ΔP ≥ 0.08 MPa. During assembly, the temperature sensor and pressure sensor should be 1.5 meters and 2.0 meters away from the outlet of the expansion valve 303, respectively, to prevent valve body disturbances from affecting the measurement.

[0067] The opening of expansion valve 303 is dynamically adjusted through dual closed-loop feedback of temperature and pressure. Temperature regulation maintains heat exchange efficiency on the ground source side, while pressure regulation ensures safe operation of compressor 101. A dead zone threshold design prevents frequent operation. This dual-parameter coordinated control improves system stability.

[0068] In another technical solution, the controller generates an opening adjustment instruction by integrating the temperature deviation and the pressure deviation according to a preset weight ratio; Define the basic weight calculation function: α base = 0.5+0.01×︱T R -T 3S ︱; Execute weight clipping: If α base <0.5, then α=0.5; if α base >0.8, then α=0.8; otherwise α =α base ; Pressure weight β=1-α; When the inlet pressure of the third heat exchanger 105 is P>P set When +0.5×ΔP, β=0.8 and α=0.2 are forced to be set.

[0069] In this technical solution, according to the domestic hot water setting temperature (T R ) and the user-side set temperature (T 3S ) calculates the temperature weight base value. Implement clipping on the base weight: when α base <0.5, force α=0.5; when α baseIf the value is greater than 0.8, α is forced to 0.8; otherwise, the calculated value is maintained. The controller weights the temperature and pressure deviations accordingly: α is the weight for the temperature control command, and β is the weight for the pressure control command. If a temperature deviation requires a 5% increase in the opening, and a pressure deviation requires a 3% decrease in the opening, the final command is (5% × 0.65) + (-3% × 0.35) = 2.05%.

[0070] A dynamic weight allocation mechanism balances temperature and pressure regulation requirements under normal operating conditions. During high-pressure conditions, system safety is prioritized to avoid control failures caused by parameter coupling. A weighted limiter design maintains regulation stability.

[0071] Example 1: Air-cooled pure cooling mode (such as Figure 2 shown) Scenario: Ambient temperature 30°C (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℃. Satisfied: 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; Control: Close the first heat exchanger water pump and the third control valve, and open the second control valve; Refrigerant flow: compressor 101 → fourth heat exchanger 106 (heat dissipation) → third heat exchanger 105 (cold absorption) → liquid receiver 100; The initial opening of the expansion valve θ0 = 30% + 0.4 × (30-35)% = 28%.

[0072] Result: The outlet water temperature on the user side was stable at 24.8℃, and domestic hot water was not started, thus achieving the energy saving purpose.

[0073] Example 2: Air cooling and pure heating mode (such as Figure 3 shown) Scenario: Ambient temperature 15°C (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℃.

[0074] 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; Control: turn off the water pump of the first heat exchanger 103 and open the second control valve 301; Refrigerant reverse direction: compressor 101 → third heat exchanger 105 (heat release) → fourth heat exchanger 106 (heat absorption) → liquid receiver 100; The opening degree of the expansion valve 303 θ0 = 40% + 0.6 × (0-15) = 31%.

[0075] Result: The outlet water temperature on the user side rose to 44.5°C, and there was no frost on the air-cooled heat exchanger.

[0076] Example 3: Air-cooled domestic hot water mode (such as Figure 4 shown) Scenario: Ambient temperature 32°C (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℃.

[0077] Satisfaction: 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; Control: Start the water pump of the first heat exchanger 103 and close the third control valve 302; Refrigerant flow: compressor 101 → first heat exchanger 103 (heating hot water) → fourth heat exchanger 106 (auxiliary heat dissipation) → third heat exchanger 105 (cold absorption) → liquid receiver 100; The opening degree of the expansion valve 303 θ0 = 35% + 0.3 × |45-25| = 41%.

[0078] Result: The domestic hot water temperature rose to 44°C, and the outlet water temperature on the user side was 25.1°C.

[0079] Example 4: Air-cooled heating domestic hot water mode (such as Figure 5 shown) Scenario: Ambient temperature 15°C (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℃.

[0080] Satisfy: T4 ≥ T S4 + S1→ 15≥6, T 1H <T R -S2→42<43, and T 3H <T 3Sd -S3→43<44; Control: Start the water pump of the first heat exchanger 103 and close the third control valve 302; Refrigerant flow: compressor 101 → first heat exchanger 103 (heating hot water) → third heat exchanger 105 (heating air-conditioning water) → fourth heat exchanger 106 (heat absorption) → liquid receiver 100; The opening degree of the expansion valve 303 θ0 = 35% + 0.3 × |45-45| = 35%.

[0081] Results: Domestic hot water temperature was 44.5°C, user-side outlet water temperature was 44.8°C, and the system operated efficiently without any risk of frost.

[0082] Example 5: Ground source pure cooling mode (such as Figure 6 shown) Scenario: Ambient temperature 38°C (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℃.

[0083] Satisfy: T4 ≥ T X4 + S1→38≥31.5, T 1H ≥T R -S2→46≥43, and T 3H ≥T 3Sx -S3→26≥24; Control: turn off the water pump of the first heat exchanger 103 and open the first control valve 300; Refrigerant flow: compressor 101 → second heat exchanger 104 (ground source heat dissipation) → third heat exchanger 105 (cold absorption) → liquid receiver 100; The opening degree of the expansion valve 303 θ0 = 30% + 0.4 × (38-35) = 31.2%.

[0084] Results: The outlet water temperature on the user side was 24.9℃, and the water temperature fluctuation on the ground source side was ≤0.3℃.

[0085] Example 6: Ground source pure heating mode (such as Figure 7 shown) Scenario: Ambient temperature -10°C (T4), preset T S4 =5℃,S1=1.5℃,T 1H =47℃, T R =45℃,S2=2℃,T 3H =43℃, T 3S =T 3Sd =45℃, S3=1℃.

[0086] Satisfaction: 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.

[0087] Control: open the first control valve 300 and close the third control valve 302; Refrigerant reverse direction: compressor 101 → third heat exchanger 105 (heat release) → second heat exchanger 104 (ground source heat absorption) → liquid reservoir 100; The opening degree of the expansion valve 303 θ0 = 40% + 0.6 × (0 - (-10)) = 46%.

[0088] Results: The outlet water temperature on the user side was 45.2℃, and the return water temperature on the ground source side was stable at 6℃.

[0089] Example 7: Ground source cooling domestic hot water mode (such as Figure 8 shown) Scenario: Ambient temperature 33°C (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℃.

[0090] Satisfied: 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; Control: Start the water pump of the first heat exchanger 103 and close the second control valve 301; Refrigerant flow: compressor 101 → first heat exchanger 103 (heating hot water) → second heat exchanger 104 (ground source heat dissipation) → third heat exchanger 105 (cold absorption) → liquid reservoir 100; The opening degree of the expansion valve 303 θ0 = 35% + 0.3 × |45-25| = 41%.

[0091] Results: The domestic hot water temperature was 44℃, the outlet water temperature on the user side dropped to 24.8℃, and the inlet pressure of the third heat exchanger rose to 3.1MPa (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 expansion valve opening.

[0092] Example 8: Ground source heating domestic hot water mode (such as Figure 9 shown) Scenario: Ambient temperature -1°C (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℃.

[0093] Satisfaction: T4<T S4 - S1→ -1<4;T 1H <T R -S2→40<43, and T 3H <T 3Sd -S3→42<44.

[0094] Control: Start the water pump of the first heat exchanger 103 and close the second control valve 301; 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) → liquid reservoir 100; The opening degree of the expansion valve 303 θ0 = 35% + 0.3 × |45-45| = 35%.

[0095] Results: Domestic hot water is 44.7℃, user-side outlet water is 44.9℃, and the inlet pressure of the third heat exchanger rises to 3.3MPa (P set=2.2MPa, ΔP=0.2MPa), triggering the forced adjustment mechanism of the opening, and the expansion valve opening increased by 12% to 47%.

[0096] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of 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 multifunctional heat pump heat recovery unit, characterized in that: The unit includes a liquid accumulator, 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 accumulator, the compressor, and the first heat exchanger are connected in sequence, the outlet of the first heat exchanger is connected to the interface A 200 of the four-way valve, the interface B 201 of the four-way valve is connected to the fourth heat exchanger, the second heat exchanger, and the third heat exchanger in sequence, the outlet of the third heat exchanger is connected to the interface C 202 of the four-way valve, and the interface D 203 of the four-way valve is connected to the inlet of the liquid accumulator; 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 provided with a plurality of temperature sensors connected to the controller for detecting 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 on the user demand side based on the change between the received real-time temperature detection value and the preset target temperature setting value, combined with the user's set requirements, and controls the corresponding heat exchanger and control valve to operate or close according to the refrigerant flow direction preset in the target operating mode, specifically: When T4≥T S4 At +S1, it is determined that the target operation mode on the user demand side is the air cooling and heating mode. The controller turns on the fan of the fourth heat exchanger, turns off the water pump of the second heat exchanger, closes the first control valve, and opens the second control valve. When T4<T S4 -S1, it is determined that the target operation mode on the user demand side is the ground source heat pump heating mode, the controller controls to turn on the water pump of the second heat exchanger, turn off the fan of the fourth heat exchanger, open the first control valve, and close the second control valve; When T4<T X4 At -S1, it is determined that the target operation mode on the user demand side is the air-cooling operation mode. The controller controls the fan of the fourth heat exchanger to be turned on, the water pump of the second heat exchanger to be turned off, the first control valve to be closed, and the second control valve to be opened. When T4≥T X4 At +S1, it is determined that the target operation mode on the user demand side is the ground source heat pump cooling 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 open and the second control valve to close. Among them, 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 of the multifunctional heat pump heat recovery unit according to claim 1, characterized in that: The first heat exchanger is a domestic hot water heat exchanger, which is used to heat domestic hot water and recover the heat from the compressor exhaust; the second heat exchanger is a ground source heat pump heat exchanger, which is used to replace air-cooled heat exchange under low-temperature conditions to prevent frost; the third heat exchanger is a user-side cooling / heating heat exchanger, which provides cooling or heating services for the user end; the fourth heat exchanger is an air-cooled ambient heat exchanger, which is used to exchange heat with the air under normal working conditions to provide an ambient cold and heat source.

3. The energy-saving control method of the multifunctional heat pump heat recovery unit according to claim 2, characterized in that: The target operating mode also includes: The controller is based on the outlet water temperature T of the domestic hot water side of the first heat exchanger. 1H , user side outlet water temperature of the third heat exchanger T 3H , preset target hot water temperature T R And the user side water outlet set temperature T 3S Do the following: When T4<T X4 -S1, T 1H ≥T R -S2 and T 3H ≥T 3S -S3, it is determined that the target operation mode on the user demand side is the air-cooled pure cooling 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, passes through the fourth and third heat exchangers in sequence, and flows back to the liquid reservoir; When T4≥T S4 +S1,T 1H ≥T R -S2 and T 3H <T 3S -S3, it is determined that the target operation mode on the user demand side is the air-cooling and heating-only 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, passes through the third and fourth heat exchangers in sequence, and flows back to the liquid reservoir; When T4<T X4 -S1, T 1H <T R -S2 and T 3H ≥T 3S -S3, it is determined that the target operation mode on the user demand side is the air-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, closes the second heat exchanger, closes the first control valve and the third control valve, and opens 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 reservoir; When T4≥T S4 +S1,T 1H <T R -S2 and T 3H <T 3S -S3, it is determined that the target operation mode on the user demand side is the air-cooling and heating domestic hot water mode. The controller controls the opening of the first heat exchanger, the third heat exchanger, and the fourth heat exchanger, closes the second heat exchanger, closes the first control valve and the third control valve, and opens 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 reservoir; Wherein, S2 is the second preset deviation value, S3 is the third preset deviation value, T 3S Automatically select the set temperature according to the current operating mode: T 3S =T 3Sx , in heating mode, T 3S =T 3Sd .

4. The energy-saving control method of the multifunctional heat pump heat recovery unit according to 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, it is determined that the target operation mode on the user demand side is the pure cooling mode of the ground source heat pump. 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, passes through the second and third heat exchangers in sequence, and flows back to the liquid reservoir; When T4<T S4 -S1, T 1H ≥T R -S2 and T 3H <T 3S -S3, it is determined that the target operation mode on the user demand side is the ground source heat pump pure heating mode. The controller controls the second and third heat exchangers to open, the first and fourth heat exchangers to close, the first control valve and the third control valve to open, and the second control valve to close, so that the refrigerant flows out of the compressor, flows through the third heat exchanger, the second heat exchanger in sequence, and flows back to the liquid reservoir; When T4<T X4 -S1, T 1H <T R -S2 and T 3H ≥T 3S -S3, it is determined that the target operation mode on the user demand side is 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, closes the fourth heat exchanger, opens the first control valve, and closes the second control valve and the third control valve, so that the refrigerant flows out of the compressor, flows through the first heat exchanger, the second heat exchanger, the third heat exchanger in sequence, and flows back to the liquid reservoir; When T4<T S4 -S1, T 1H <T R -S2 and T 3H <T 3S -S3, it is determined that the target operating mode on the user demand side is the ground source heat pump heating domestic hot water mode. The controller controls the opening of the first heat exchanger, the second heat exchanger and the third heat exchanger, closes the fourth heat exchanger, opens the first control valve, closes the second control valve and the third control valve, so that the refrigerant flows out of the compressor and flows through the first heat exchanger, the third heat exchanger, the second heat exchanger in sequence and flows back to the liquid reservoir.

5. The energy-saving control method of the multifunctional heat pump heat recovery unit according to claim 4, characterized in that: The first preset deviation value S1, the second preset deviation value S2, and the third preset deviation value S3 are determined 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 by the coefficient C1, where 5≤N≤10, 0.2≤C1≤0.3; Run the cooling and heating modes under standard working conditions and record the following: Domestic hot water temperature fluctuation range ΔT2 = max (T 1H )-min(T 1H ), user side water temperature fluctuation range ΔT3=max(T 3H )-min(T 3H ), take the initial value of S2 = C2×ΔT2, the initial value of S3 = C3×ΔT3, where 0.6≤C2≤0.9, 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 of the multifunctional heat pump heat recovery unit according to claim 5, characterized in that: The controller dynamically adjusts the values ​​of S1, S2, and S3 according to the intensity of ambient temperature fluctuation and load conflict intensity: Calculate the absolute value of the ambient temperature change rate δ=︱ΔT4 / Δt︱ in real time, and update the first preset deviation value S1 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; Among them, γ is the preset environmental mutation sensitivity, ranging from 0.05 to 0.2; β is the preset cooling and heating load conflict threshold, ranging from 20 to 30°C; k and m are preset coefficients, k is 0.8, and m is 1.

2.

7. The energy-saving control method for a multifunctional heat pump heat recovery unit according to claim 4, characterized in that: The initial opening 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)%, 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)%, the opening degree is 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 a multifunctional heat pump heat recovery unit according to claim 7, characterized in that: The expansion valve opening control implements a dual-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 + ΔT1, reduce the initial opening of the expansion valve by 5%-15%; When T 2H <T set -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 temperature at the outlet of the second heat exchanger to meet the requirement of 5℃≤T set ≤45℃; ΔT1 is the temperature dead zone threshold, which satisfies 0.5℃≤ΔT1≤2.0℃; P set Set the pressure at the inlet of the third heat exchanger to meet the requirement of 0.5MPa≤P set ≤4.0MPa; ΔP is the pressure dead zone threshold, satisfying 0.05MPa≤ΔP≤0.2MPa.

9. The energy-saving control method for a multifunctional heat pump heat recovery unit according to claim 8, characterized in that: The controller generates an opening adjustment instruction by integrating the temperature deviation and the pressure deviation according to a preset weight ratio; Define the basic weight calculation function: α base = 0.5+0.01×︱T R -T 3S ︱; Execute weight clipping: If α base <0.5, then α=0.5; if α base >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 forced to be set.

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