Low-temperature central heating heat source adaptive variable frequency water source heat pump unit and heating control method thereof

Abstract

This invention relates to the field of water source heat pump units and compression heat pump cycle control technology, and particularly to a low-temperature centralized heating heat source adaptive variable frequency water source heat pump unit and its heating control method. The unit includes a heat source-side heat exchanger, a variable frequency compressor, a throttling device, a user-side heat exchanger, a built-in circulating water pump, and a controller. The heat source-side heat exchanger is connected to the centralized heating water circuit, and the user-side heat exchanger is connected to underfloor heating terminals, radiator terminals, or a combination of both. The controller determines the heat source-side heat extraction margin parameters based on the heat source-side temperature parameters, determines the user-side load demand parameters based on the user-side temperature parameters, and, in conjunction with the suction superheat, refrigerant subcooling, and exhaust safety status, adjusts the operating frequency of the variable frequency compressor, the opening degree of the throttling device, and the speed of the built-in circulating water pump. This system is used for secondary heating using low-temperature centralized heating water as a low-temperature heat source, and can simultaneously address heat source-side protection, refrigerant circulation stability, and adaptability to different heating terminals.

Description

Technical Field

[0001] This invention relates to the field of water source heat pump units and compression heat pump cycle control technology, and particularly to a low-temperature centralized heating heat source adaptive variable frequency water source heat pump unit and its heating control method. Background Technology

[0002] A water source heat pump unit typically includes a variable frequency compressor, a throttling device, a heat source-side heat exchanger, and a user-side heat exchanger. These components are sequentially connected to form the refrigerant circulation loop of a compression heat pump. The refrigerant absorbs heat from a low-temperature heat source and evaporates in the heat source-side heat exchanger (which acts as the evaporator). After being compressed by the variable frequency compressor, it becomes a high-temperature, high-pressure refrigerant, which then releases heat to the user-side heating circulating water in the user-side heat exchanger (which acts as the condenser) to provide heating.

[0003] In some centralized heating scenarios, the temperature of the centralized heating water is low, or factors such as pipeline distance, building load, and terminal heat dissipation conditions cause slow heating and insufficient heating temperatures at the user-side heating terminals such as underfloor heating and radiators. Therefore, there is a need to use the centralized heating water as a low-temperature heat source for a water source heat pump, and to use a compression heat pump to circulate and reheat the user-side heating circulating water.

[0004] However, existing water source heat pump units still have the following problems when using low-temperature district heating water as a heat source:

[0005] (1) Existing systems usually adjust the compressor operating frequency based only on the actual supply water temperature or return water temperature on the user side, without fully combining the inlet water temperature, outlet water temperature and inlet / outlet water temperature difference on the heat source side to determine the heat extraction status on the evaporator side, which can easily lead to excessive heat extraction on the evaporator side and abnormally lower return water temperature in the central heating system.

[0006] (2) When the temperature of the central heating water fluctuates or the heat available on the heat source side is insufficient, the existing system is unable to limit the compressor frequency increase or adjust the opening of the throttling device in time, which can easily cause abnormalities in evaporation pressure, suction superheat, condensation pressure or exhaust temperature, affecting the stability of the heat pump cycle and the safety of compressor operation.

[0007] (3) Existing throttling control is based on a single superheat, without fully combining refrigerant subcooling, exhaust safety status and user-side load changes for comprehensive adjustment, which can easily lead to problems such as unstable refrigerant supply, insufficient subcooling or decreased condensation heat exchange efficiency.

[0008] (4) In the existing system, the compressor, throttling device and built-in circulating water pump are mostly controlled independently. There is a lack of linkage control strategy based on the heat source side heat extraction status, user side load demand and refrigerant circulation status. This can easily lead to slow user side heating speed, large fluctuations in water supply temperature or frequent compressor start-stop when running at low load.

[0009] (5) Existing condenser heat exchangers usually only perform ordinary condensation heat exchange, which does not make sufficient use of the waste heat of the liquid refrigerant after condensation. The refrigerant subcooling is unstable, which is not conducive to improving the efficiency of the heat pump cycle and the stability of the actual water supply temperature on the user side.

[0010] (6) The required water supply temperature and circulation flow rate of underfloor heating, radiators and mixed underfloor heating and radiators are different. The existing system has difficulty in identifying the type of heating terminal on the user side based on the temperature difference between the supply and return water on the user side, the rate of change of the supply water temperature and the speed of the built-in circulating water pump, resulting in poor adaptability of the same water source heat pump unit to different heating terminals. Summary of the Invention

[0011] To address at least one of the technical problems in the prior art, the present invention aims to provide a low-temperature centralized heating heat source adaptive variable frequency water source heat pump unit.

[0012] To address at least one of the technical problems in the prior art, the present invention aims to provide a heating control method for a low-temperature centralized heating heat source adaptive variable frequency water source heat pump unit.

[0013] The first objective of this invention is achieved as follows:

[0014] A low-temperature centralized heating heat source adaptive variable frequency water source heat pump unit includes a heat source side heat exchanger, a variable frequency compressor, a throttling device, a user side heat exchanger, a built-in circulating water pump, a user side water supply pipeline, a user side water return pipeline, and a controller. The heat source side heat exchanger includes a heat source water channel and a refrigerant evaporation channel. The heat source water channel is used to connect to the centralized heating water circuit.

[0015] The heat source-side heat exchanger serves as an evaporation-side heat exchanger, used to allow the refrigerant to evaporate and absorb heat within the refrigerant evaporation channel; the user-side heat exchanger serves as a condensation-side heat exchanger, used to allow the refrigerant to condense and release heat.

[0016] The user-side heat exchanger includes a refrigerant condensation channel and a user water channel. The user water channel is connected to the user-side water supply pipeline and the user-side water return pipeline, respectively. The user-side water supply pipeline is used to connect at least one of the underfloor heating manifold and radiators.

[0017] The discharge port of the variable frequency compressor, the refrigerant condensation channel, the throttling device, the refrigerant evaporation channel, and the suction port of the variable frequency compressor are connected in sequence to form a refrigerant circulation loop of a compression heat pump.

[0018] The built-in circulating water pump is used to drive the user-side heating circulating water to circulate between the user-side heat exchanger and at least one of the underfloor heating manifold and radiator.

[0019] The controller is electrically connected to the variable frequency compressor, the throttling device, and the built-in circulating water pump, respectively. The controller is used to adjust the operating frequency of the variable frequency compressor, the opening degree of the throttling device, and the speed of the built-in circulating water pump in conjunction with the temperature parameters on the heat source side and the temperature parameters on the user side.

[0020] By configuring a heat exchanger on the heat source side, a variable frequency compressor, a throttling device, and a heat exchanger on the user side, and sequentially connecting the discharge port of the variable frequency compressor, the refrigerant condensing channel, the throttling device, the refrigerant evaporating channel, and the suction port of the variable frequency compressor to form a refrigerant circulation loop for a compression heat pump, the central heating water can participate in the heat pump circulation as a low-temperature heat source on the evaporating side. The user-side heating circulating water can absorb the heat released by the refrigerant as a load on the condensing side and then supply it to the underfloor heating manifold and / or radiators. Simultaneously, the controller adjusts the operating frequency of the variable frequency compressor, the opening degree of the throttling device, and the speed of the built-in circulating water pump based on the temperature parameters on the heat source side and the user side. This solves the problem that existing units, relying solely on user-side water temperature control, struggle to simultaneously address the heat extraction status on the evaporating side, the heat release load on the user side, and the throttling refrigerant supply status. This improves the stability of the refrigerant circulation and the heating effect on the user side.

[0021] The above control is based on the refrigerant circulation loop of the compression heat pump, and coordinates the heat extraction boundary on the evaporator side, the heat release load on the user side, the liquid supply status of the electronic expansion valve, and the safety status of the variable frequency compressor. The underfloor heating manifold or radiator on the user side is connected as the condensing side load terminal.

[0022] The primary objective of this invention can also be achieved using the following technical measures:

[0023] Furthermore, the water source heat pump unit also includes a heat source side inlet water temperature detection device, a heat source side outlet water temperature detection device, a user side actual water supply temperature detection device, and a user side return water temperature detection device;

[0024] The heat source side temperature parameters include at least the heat source side outlet water temperature and the heat source side inlet and outlet water temperature difference, and include at least one of the heat source side inlet water temperature and the heat source side outlet water temperature change rate.

[0025] The user-side temperature parameters include at least the user-side target water supply temperature and the user-side actual water supply temperature, and include at least one of the following: user-side return water temperature, user-side supply and return water temperature difference, and user-side actual water supply temperature change rate.

[0026] By setting up inlet water temperature sensors on the heat source side, outlet water temperature sensors on the heat source side, actual supply water temperature sensors on the user side, and return water temperature sensors on the user side, the controller can obtain parameters such as inlet water temperature, outlet water temperature, temperature difference between inlet and outlet water on the heat source side, rate of change of outlet water temperature on the heat source side, target supply water temperature, actual supply water temperature, and return water temperature on the user side. This provides a basis for subsequent judgment of the heat extraction status on the evaporator side and changes in user load. This solves the problem of existing water source heat pump units having only single detection parameters and difficulty in timely reflecting the operating status of the heat source and user sides, providing more comprehensive data for adjusting the compressor, throttling device, and built-in circulating water pump.

[0027] Furthermore, the controller generates heat source side heat extraction margin parameters based on the heat source side temperature parameters, and generates user side load demand parameters based on the user side temperature parameters;

[0028] When the temperature difference between the inlet and outlet water on the heat source side is greater than the preset upper limit of the temperature difference between the inlet and outlet water on the heat source side, or when the outlet water temperature on the heat source side is lower than the preset lower limit of the outlet water temperature on the heat source side, the controller determines that the heat extraction margin parameter on the heat source side does not meet the preset heat extraction margin condition, and restricts the operation frequency of the variable frequency compressor from increasing or decreasing.

[0029] By enabling the controller to generate heat source margin parameters based on heat source side temperature parameters and user side load demand parameters based on user side temperature parameters, the operating frequency of the variable frequency compressor can be limited or reduced when the temperature difference between the inlet and outlet water on the heat source side is too large or the outlet water temperature on the heat source side is too low. This prevents the heat exchanger on the heat source side from continuing to absorb excessive heat from the central heating water. This solution addresses the problem of abnormally low central heating return water temperature and unstable evaporator-side heat exchange caused by continuous frequency increases in the compressor when the central heating water temperature is low or fluctuating. It helps protect the water circuit on the heat source side and maintains the stable operation of the compression heat pump cycle.

[0030] Furthermore, the controller is also used to perform self-learning control of the heat source side's heat extraction capacity within a preset identification time after the water source heat pump unit is started; the controller controls the variable frequency compressor to operate at a preset trial frequency, controls the throttling device to maintain a preset trial opening, and controls the built-in circulating water pump to operate at a preset trial speed. The controller determines the heat source side's heat extraction capacity level based on the rate of decrease of the heat source side's outlet water temperature, the temperature difference between the heat source side's inlet and outlet water, and the rate of increase of the actual supply water temperature on the user side. Based on the heat source side's heat extraction capacity level, the controller selects the corresponding variable frequency compressor frequency increase curve, throttling device opening curve, built-in circulating water pump speed curve, and / or heat source side bypass regulating valve opening curve.

[0031] During the startup phase of the water source heat pump unit, self-learning control of the heat source side's heat extraction capacity is implemented. This involves short-term identification using preset test frequencies, preset test opening degrees, and preset test speeds. Based on the rate of temperature decrease of the outlet water on the heat source side, the temperature difference between the inlet and outlet water on the heat source side, and the rate of temperature increase of the actual supply water temperature on the user side, the heat extraction capacity level of the centralized heating water circuit is determined. Consequently, the controller can select the appropriate variable frequency compressor frequency increase curve, throttling device opening degree curve, and built-in circulating water pump speed curve for differences in the temperature, flow rate, and heat exchange capacity of different community pipe networks. This avoids excessive heat extraction under low-temperature or low-flow pipe network conditions while improving the temperature rise response speed under conditions of sufficient heat source capacity.

[0032] Furthermore, the heat source water channel has a heat source water inlet and a heat source water outlet, the heat source water inlet is used to connect with the central heating water inlet pipe, and the heat source water outlet is used to connect with the central heating water return pipe;

[0033] The heat source water channel includes an inlet flow equalization chamber, an outlet flow convergence chamber, and multiple parallel heat source water heat exchange branches;

[0034] The inlet flow equalization chamber is connected to the heat source water inlet, the outlet flow collection chamber is connected to the heat source water outlet, and multiple heat source water heat exchange branches are connected in parallel between the inlet flow equalization chamber and the outlet flow collection chamber;

[0035] The refrigerant evaporation channel includes a refrigerant inlet manifold, a refrigerant outlet manifold, and multiple refrigerant evaporation branches corresponding to the heat exchange branches of the heat source water.

[0036] The refrigerant inlet manifold is connected to the outlet of the throttling device, the refrigerant outlet manifold is connected to the suction port of the variable frequency compressor, and multiple refrigerant evaporation branches are connected in parallel between the refrigerant inlet manifold and the refrigerant outlet manifold.

[0037] The refrigerant inlet manifold is used to distribute the refrigerant after it has been throttled by the throttling device to multiple refrigerant evaporation branches, and the refrigerant outlet manifold is used to collect the refrigerant flowing out of multiple refrigerant evaporation branches and transport the refrigerant to the suction port.

[0038] By incorporating an inlet water equalization chamber, an outlet water collection chamber, and multiple parallel heat source water heat exchange branches in the heat source water channel, and by including multiple refrigerant evaporation branches in the refrigerant evaporation channel corresponding to the heat exchange of the heat source water branches, the centralized heating water can be evenly distributed after entering the heat source-side heat exchanger and fully exchange heat with the refrigerant evaporation branches. This structure can improve the problems of uneven heat exchange on the evaporation side, excessive local heat extraction, or insufficient local heat exchange, which is beneficial to improving the uniformity of refrigerant heat absorption on the evaporation side and reducing the temperature fluctuation of the outlet water on the heat source side.

[0039] Furthermore, the user-side heat exchanger includes a main condensation heat exchange zone, a liquid equalization transition zone, and a subcooling heat exchange zone arranged sequentially along the refrigerant flow direction;

[0040] The main condensing heat exchange zone is used to allow the refrigerant discharged from the variable frequency compressor to exchange heat with the heating circulating water on the user side.

[0041] The liquid equalization transition zone is used to equalize the pressure and distribute the flow of liquid refrigerant entering the subcooled heat exchange zone.

[0042] The subcooled heat exchange zone is located upstream of the throttling device and is used to allow the condensed liquid refrigerant to continue releasing heat back to the user side of the water.

[0043] The user water channel is configured such that the user-side return water first passes through the subcooling heat exchange zone and then through the main condensing heat exchange zone, forming a segmented countercurrent heat exchange path in which the user-side water flow and the refrigerant flow direction are opposite.

[0044] By configuring the user-side heat exchanger as a main condensing heat exchange zone, a liquid equalization transition zone, and a subcooling heat exchange zone, and by having the user-side return water first pass through the subcooling heat exchange zone and then through the main condensing heat exchange zone, the condensed liquid refrigerant can continue to release waste heat to the lower-temperature user-side return water, increasing the refrigerant subcooling. The main condensing heat release process is then completed through the main condensing heat exchange zone. This solution addresses the problems of insufficient utilization of liquid refrigerant waste heat and unstable refrigerant subcooling in existing user-side heat exchangers, thus improving condensing-side heat exchange efficiency and the stability of the actual user-side supply water temperature.

[0045] Furthermore, the throttling device is an electronic expansion valve;

[0046] The water source heat pump unit also includes an intake temperature detection device, an intake pressure detection device, an exhaust temperature detection device, an exhaust pressure detection device, and an inlet temperature detection device for the throttling device;

[0047] The controller determines the suction superheat based on the suction temperature and suction pressure, determines the refrigerant subcooling based on the discharge pressure and the inlet temperature of the throttling device, and determines the discharge safety status based on the discharge temperature and discharge pressure.

[0048] The controller adjusts the opening of the electronic expansion valve according to the intake superheat, the refrigerant subcooling, and the exhaust safety status.

[0049] By setting the throttling device as an electronic expansion valve and incorporating suction temperature, suction pressure, discharge temperature, discharge pressure, and throttling device inlet temperature sensors, the controller can determine the suction superheat based on suction temperature and suction pressure, the refrigerant subcooling based on discharge pressure and throttling device inlet temperature, and the discharge safety state based on discharge temperature and discharge pressure. This allows the controller to adjust the opening of the electronic expansion valve according to the actual refrigerant cycle state, resolving issues such as unstable refrigerant supply, insufficient subcooling, or abnormal discharge temperature that can easily occur when adjusting the throttling device solely based on superheat. This improves compressor operating safety and heat pump cycle stability.

[0050] Furthermore, the water source heat pump unit also includes a heat source side bypass pipeline and a heat source side bypass regulating valve;

[0051] The heat exchanger on the heat source side has a heat source water inlet and a heat source water outlet. The heat source side bypass pipeline is connected between the heat source water inlet and the heat source water outlet. The heat source side bypass regulating valve is installed on the heat source side bypass pipeline and is electrically connected to the controller.

[0052] When the heat extraction margin parameter on the heat source side does not meet the preset heat extraction margin condition, the controller increases the opening of the bypass regulating valve on the heat source side, so that some of the central heating water bypasses the heat exchanger on the heat source side and mixes with the water outlet at the heat source water outlet, thereby limiting the heat extraction of the central heating water by the heat exchanger on the heat source side.

[0053] By installing a bypass pipeline and a bypass regulating valve on the heat source side connected between the heat source water inlet and outlet, the controller can increase the opening of the bypass regulating valve when the heat source side heat extraction margin parameter does not meet the preset heat extraction margin condition. This allows some of the central heating water to bypass the heat source side heat exchanger and mix with the water effluent at the heat source water outlet. This solution can reduce the effective heat extraction intensity when the heat source side outlet water temperature is too low or the temperature difference between the inlet and outlet water on the heat source side is too large. It solves the problem of abnormally low return water temperature caused by excessive heat extraction of the central heating water by the heat source side heat exchanger, and helps maintain the evaporator side heat exchange boundary and the operational stability of the central heating water circuit.

[0054] Furthermore, the controller includes a heating terminal identification unit;

[0055] The heating terminal identification unit identifies the current user-side heating terminal as a floor heating terminal, a radiator terminal, or a hybrid terminal of floor heating and radiators based on the actual water supply temperature on the user side, the return water temperature on the user side, the speed of the built-in circulating water pump, the temperature difference between the supply and return water on the user side, and the change rate of the actual water supply temperature on the user side.

[0056] When a device is identified as a floor heating terminal, the controller executes the first heating control mode;

[0057] When a radiator terminal is identified, the controller executes the second heating control mode;

[0058] When the system is identified as a hybrid terminal for both underfloor heating and radiators, the controller executes the third heating control mode.

[0059] In this heating control mode, the target water supply temperature range on the user side corresponding to the first heating control mode is lower than the target water supply temperature range on the user side corresponding to the second heating control mode. The third heating control mode adjusts the speed of the built-in circulating water pump according to the rate of change of the user side return water temperature and limits the rate of increase of the actual water supply temperature on the user side.

[0060] By incorporating a heating terminal identification unit in the controller, and based on the actual supply water temperature, return water temperature, built-in circulating water pump speed, supply and return water temperature difference, and the rate of change of the actual supply water temperature, the controller can identify underfloor heating terminals, radiator terminals, or a combination of underfloor heating and radiator terminals. This allows the controller to execute corresponding heating control modes according to different terminal types. This solution addresses the problem of existing systems struggling to automatically adapt to the significant differences in required supply water temperature and circulation flow rates for different heating terminals, and helps avoid situations where underfloor heating terminals heat up too quickly, radiator terminals provide insufficient heat, or combined underfloor heating and radiator terminals experience large temperature fluctuations.

[0061] The second objective of this invention is achieved as follows:

[0062] A heating control method for a low-temperature centralized heating heat source adaptive variable frequency water source heat pump unit, applied to the aforementioned low-temperature centralized heating heat source adaptive variable frequency water source heat pump unit, includes the following steps:

[0063] S1, acquire the temperature parameters on the heat source side and the temperature parameters on the user side. The temperature parameters on the heat source side include at least the outlet water temperature on the heat source side and the temperature difference between the inlet and outlet water on the heat source side, and include at least one of the inlet water temperature on the heat source side and the rate of change of the outlet water temperature on the heat source side. The temperature parameters on the user side include at least the target water supply temperature on the user side and the actual water supply temperature on the user side, and include at least one of the return water temperature on the user side, the temperature difference between the supply and return water on the user side, and the rate of change of the actual water supply temperature on the user side.

[0064] S2, determine the heat source side heat extraction margin parameter based on the heat source side temperature parameter, and determine the user side load demand parameter based on the user side temperature parameter;

[0065] S3, based on the heat source side heat margin parameters and the user side load demand parameters, determine the target operating frequency of the variable frequency compressor, the target opening degree of the throttling device, and the target speed of the built-in circulating water pump;

[0066] S4, control the operation of the variable frequency compressor according to the target operating frequency, control the operation of the throttling device according to the target opening degree, and control the operation of the built-in circulating water pump according to the target speed;

[0067] S5 compares the actual water supply temperature on the user side with the target water supply temperature range on the user side during operation.

[0068] When the actual water supply temperature on the user side is lower than the lower limit of the target water supply temperature range on the user side, and the heat source side heat extraction margin parameter meets the preset heat extraction margin condition, the operating frequency of the variable frequency compressor is increased.

[0069] When the actual water supply temperature on the user side is lower than the lower limit of the target water supply temperature range on the user side, but the heat extraction margin parameter on the heat source side does not meet the preset heat extraction margin condition, the operating frequency of the variable frequency compressor is restricted from increasing, and the target operating frequency is restricted to the upper limit of the frequency corresponding to the current heat extraction margin parameter on the heat source side.

[0070] When the actual water supply temperature on the user side enters the target water supply temperature range on the user side, the operating frequency of the variable frequency compressor is maintained or reduced, and the built-in circulating water pump is maintained at a preset heat preservation circulation speed.

[0071] When the actual water supply temperature on the user side is higher than the upper limit of the target water supply temperature range on the user side, the operating frequency of the variable frequency compressor is reduced, and the built-in circulating water pump is maintained at the preset heat preservation circulation speed.

[0072] By acquiring the temperature parameters on the heat source side and the user side in the heating control method, and determining the heat source side heat extraction margin parameters and the user side load demand parameters accordingly, and then determining the target operating frequency of the variable frequency compressor, the target opening degree of the throttling device, and the target speed of the built-in circulating water pump, the operating status of the compressor, throttling device, and circulating water pump can be adjusted according to changes in the heat extraction status on the heat source side and the load demand on the user side. This method can solve the problems of single response, slow temperature rise, large fluctuations in supply water temperature, and frequent start-stop of the compressor during low-load operation in existing control methods, and is beneficial to improving the heating stability when low-temperature centralized heating water is used as the evaporative heat source.

[0073] The second objective of this invention can also be achieved by the following technical measures:

[0074] Furthermore, the heating control method also includes the following control functions:

[0075] The water source heat pump unit includes a user-side actual water supply temperature detection device, a user-side return water temperature detection device, a suction temperature detection device, a suction pressure detection device, a discharge temperature detection device, a discharge pressure detection device, a throttling device inlet temperature detection device, a heat source-side inlet water temperature detection device, and a heat source-side outlet water temperature detection device.

[0076] In step S1, the actual water supply temperature on the user side is obtained through the actual water supply temperature detector on the user side, the return water temperature on the user side is obtained through the return water temperature detector on the user side, and the suction temperature, suction pressure, discharge temperature, discharge pressure, and throttling device inlet temperature are also obtained. The user side supply and return water temperature difference is determined based on the actual water supply temperature and the return water temperature on the user side. The change rate of the actual water supply temperature on the user side is determined based on the continuously collected actual water supply temperature on the user side. The change rate of the return water temperature on the user side is determined based on the continuously collected return water temperature on the user side. The suction superheat is determined based on the suction temperature and the suction pressure. The refrigerant subcooling is determined based on the discharge pressure and the throttling device inlet temperature. The discharge safety status is determined based on the discharge temperature and the discharge pressure.

[0077] The inlet water temperature on the heat source side is obtained through the inlet water temperature detection device on the heat source side, and the outlet water temperature on the heat source side is obtained through the outlet water temperature detection device on the heat source side; the temperature difference between the inlet and outlet water on the heat source side is determined based on the inlet water temperature and the outlet water temperature on the heat source side, and the rate of change of the outlet water temperature on the heat source side is determined based on the continuously collected outlet water temperature on the heat source side.

[0078] In step S3, the controller determines the target operating frequency of the variable frequency compressor, the target opening degree of the throttling device, and the target speed of the built-in circulating water pump according to the priority control rules.

[0079] The priority control rules include:

[0080] When the exhaust pressure is higher than the preset exhaust pressure limit or the exhaust temperature is higher than the preset exhaust temperature limit, the operating frequency of the variable frequency compressor is reduced first, and the opening degree of the throttling device is limited.

[0081] When the intake superheat is lower than the preset lower limit of superheat, the opening of the throttling device is reduced first.

[0082] When the heat source side heat extraction margin parameter does not meet the preset heat extraction margin condition, the operating frequency of the variable frequency compressor is restricted from increasing or decreasing, and the opening of the throttling device is adjusted according to the deviation of the suction superheat from the preset superheat range. The speed of the built-in circulating water pump is adjusted according to the temperature difference between the supply and return water on the user side and the actual supply water temperature change rate on the user side.

[0083] When the refrigerant subcooling is lower than the preset subcooling lower limit, and the suction superheat is within the preset superheat range and the exhaust safety status meets the preset exhaust safety conditions, the maximum allowable opening of the throttling device is preferentially limited and / or the speed of the built-in circulating water pump is increased within the preset allowable speed range.

[0084] When the exhaust safety status meets the preset exhaust safety conditions, the intake superheat is within the preset superheat range, the refrigerant subcooling is within the preset subcooling range, the heat source side heat margin parameter meets the preset heat margin conditions, and the user side load demand parameter increases, the operating frequency of the variable frequency compressor is increased.

[0085] When the actual water supply temperature on the user side enters the target water supply temperature range on the user side, the operating frequency of the variable frequency compressor is maintained or reduced, and the speed of the built-in circulating water pump is maintained or reduced according to the rate of change of the return water temperature on the user side. When two or more priority control rules are satisfied simultaneously, they are executed according to the order of their arrangement, with the priority control rule that appears earlier overriding the one that appears later.

[0086] By further acquiring suction temperature, suction pressure, discharge temperature, discharge pressure, and throttling device inlet temperature in the method, and executing priority control rules based on suction superheat, refrigerant subcooling, discharge safety status, and heat source margin parameters, the method can prioritize reducing the compressor operating frequency when the discharge temperature or discharge pressure is abnormal, prioritize reducing the throttling device opening when the suction superheat is too low, and limit the compressor frequency increase when heat source is insufficient. This scheme can solve the problem of unclear response sequence among compressor safety protection, throttling device liquid supply regulation, and evaporator-side heat extraction protection in compression heat pump cycles, and helps reduce the risks of liquid slugging, excessively high discharge temperature, unstable throttling, and excessive heat extraction from the heat source.

[0087] The beneficial effects of this invention are as follows:

[0088] This invention connects to the centralized heating water circuit via a heat exchanger on the heat source side, using the centralized heating water as a low-temperature heat source for the refrigerant evaporation side. The heat extraction status on the heat source side is determined by the inlet water temperature, outlet water temperature, temperature difference between the inlet and outlet water, and the rate of change of the outlet water temperature. When the outlet water temperature is too low or the temperature difference between the inlet and outlet water is too large, the controller can limit the increase in the operating frequency of the variable frequency compressor and, in conjunction with a throttling device and a built-in circulating water pump, adjust the system to prevent excessive heat extraction on the evaporation side and reduce the risk of abnormally low return water temperature in the centralized heating system.

[0089] This invention acquires refrigerant cycle-related parameters through suction temperature detection, suction pressure detection, discharge temperature detection, discharge pressure detection, and throttling device inlet temperature detection. This enables the controller to determine suction superheat, refrigerant subcooling, and discharge safety status, and adjust the opening of the electronic expansion valve and the operating frequency of the variable frequency compressor accordingly. This reduces problems such as abnormal suction superheat, unstable refrigerant supply, excessively high discharge temperature, or excessively high discharge pressure, thus helping to lower the risks of compressor liquid slugging and high-temperature, high-pressure operation.

[0090] This invention determines the user-side load demand based on the target supply water temperature, actual supply water temperature, return water temperature, supply and return water temperature difference, and the rate of change of the actual supply water temperature. Based on this, it determines the target operating frequency of the variable frequency compressor, the target opening degree of the throttling device, and the target speed of the built-in circulating water pump. Simultaneously, the user-side heat exchanger is equipped with a main condensing heat exchange zone, a liquid equalization transition zone, and a subcooling heat exchange zone. This allows the user-side return water to first absorb the residual heat of the liquid refrigerant before undergoing main condensing heat exchange, which helps improve the refrigerant subcooling and condensing-side heat exchange efficiency. This enables the actual supply water temperature on the user side to reach the target supply water temperature range more quickly and remain stable.

[0091] This invention uses a heating terminal identification unit to identify underfloor heating terminals, radiator terminals, or a combination of underfloor heating and radiator terminals based on the actual supply water temperature, return water temperature, supply and return water temperature difference, built-in circulating water pump speed, and the rate of change of the actual supply water temperature on the user side, and then executes the corresponding heating control mode. This allows for adjustment based on the required supply water temperature and circulation flow rate of different heating terminals, avoiding problems such as excessively rapid heating of underfloor heating terminals, insufficient heating of radiator terminals, and large temperature fluctuations in the combination of underfloor heating and radiator terminals. Simultaneously, once the actual supply water temperature on the user side enters the target supply water temperature range, the operating frequency of the variable frequency compressor is maintained or reduced to maintain heat preservation circulation, which helps reduce frequent start-stop cycles during low-load operation.

[0092] This invention can also perform self-learning control of the heat source side's heat extraction capacity during the start-up phase of the water source heat pump unit. It performs short-term identification through preset test frequencies, preset test opening degrees, and preset test speeds, and determines the heat extraction capacity level of the centralized heating water circuit based on the rate of temperature drop of the outlet water on the heat source side, the temperature difference between the inlet and outlet water on the heat source side, and the rate of temperature rise of the actual supply water on the user side. Therefore, the controller can select the corresponding variable frequency compressor frequency increase curve, throttling device opening degree curve, and built-in circulating water pump speed curve for differences in the temperature, flow rate, and heat exchange capacity of different community pipe networks, avoiding excessive heat extraction under low temperature or low flow conditions, while improving the temperature rise response speed under conditions of sufficient heat source capacity.

[0093] By separately defining the operating conditions corresponding to the parameters of exhaust safety status, suction superheat, refrigerant subcooling, and heat source side heat extraction margin, and executing control according to the priority order of exhaust safety protection, suction liquid slugging protection, heat source side heat extraction protection, refrigerant subcooling adjustment, and user side load adjustment, high-priority protection actions can cover low-priority frequency increase actions. This avoids conflicting control commands when multiple adjustment targets are triggered simultaneously, reducing the risks of exhaust exceeding limits, suction liquid carryover, insufficient subcooling, and excessive heat extraction from the heat source side.

[0094] By limiting the calculation cycle of the temperature change rate, the number of consecutive confirmations, the recovery hysteresis, the preset trial conditions, and the update conditions of the heat source side's heat extraction capacity level, the impact of instantaneous fluctuations of the sensor and short-term disturbances of the pipeline network on the judgment results can be reduced, and frequent switching of the heat source side's heat extraction capacity level can be avoided, making the linkage control of the variable frequency compressor, throttling device, built-in circulating water pump, and heat source side bypass regulating valve more stable. Attached Figure Description

[0095] Figure 1 This is a schematic diagram of the overall structure of the low-temperature centralized heating heat source adaptive variable frequency water source heat pump unit of the present invention.

[0096] Figure 2 This is a schematic diagram of the internal flow channel structure of the heat source side heat exchanger of the present invention.

[0097] Figure 3 This is a schematic diagram of the segmented countercurrent heat exchange structure of the user-side heat exchanger of the present invention.

[0098] Figure 4 This is a schematic diagram of the electrical connections between the controller and each detection element and execution component of the present invention.

[0099] Figure 5 This is a schematic diagram illustrating the working principle of the low-temperature centralized heating heat source adaptive variable frequency water source heat pump unit of the present invention.

[0100] Figure 6 This is a schematic diagram of the external structure of the water source heat pump unit of the present invention.

[0101] Figure 7 This is a schematic diagram of the internal assembly structure of the water source heat pump unit of the present invention.

[0102] Figure 1 , Figure 2 , Figure 3 and Figure 5 The solid arrows in the diagram indicate the flow direction of the corresponding working medium. Among them, Figure 1 and Figure 5 The arrows in the diagram indicate the flow directions of the central heating water, refrigerant, and user-side heating circulating water, respectively. Figure 2The downward arrow indicates the flow direction of the central heating water, and the upward arrow indicates the flow direction of the refrigerant. Figure 3 The downward arrow indicates the direction of refrigerant flow, and the upward arrow indicates the direction of heating circulating water flow on the user side. Figure 3 The horizontal dashed lines in the diagram represent the partition lines between the main condensation heat exchange zone 411, the liquid equalization transition zone 412, and the subcooling heat exchange zone 413. These horizontal dashed lines do not represent solid components.

[0103] Figure 1 and Figure 4 The dashed lines in the diagram represent electrical connections or signal transmission relationships. Detailed Implementation

[0104] The present invention will be further described below with reference to the accompanying drawings. It should be understood that the following embodiments are only for illustrating the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Where there is no conflict, the technical features in the following embodiments can be combined with each other.

[0105] Example 1, such as Figures 1 to 7 As shown, this embodiment provides a low-temperature centralized heating heat source adaptive variable frequency water source heat pump unit. The water source heat pump unit is used to connect to the centralized heating water circuit and use the centralized heating water as a low-temperature heat source. The heat pump circulation is used to raise the temperature of the user-side heating circulating water a second time to supply heat to the underfloor heating manifold 91 and / or radiator 92.

[0106] The water source heat pump unit includes a heat source-side heat exchanger 10, a variable frequency compressor 20, a throttling device 30, a user-side heat exchanger 40, a built-in circulating water pump 50, a user-side water supply pipeline 61, a user-side water return pipeline 62, and a controller 70. In this embodiment, the throttling device 30 is preferably an electronic expansion valve.

[0107] The water source heat pump unit is preferably designed as an integrated unit. The heat source-side heat exchanger 10, the variable frequency compressor 20, the throttling device 30, the user-side heat exchanger 40, the built-in circulating water pump 50, and the controller 70 are all integrated within the water source heat pump unit. The external surface of the water source heat pump unit has interfaces for connecting to the central heating water circuit and the user-side heating circulating water circuit. Therefore, the water source heat pump unit can form an integrated structure that facilitates on-site installation, pipeline connection, inspection and maintenance, and overall layout.

[0108] In this embodiment, the heat source-side heat exchanger 10 serves as an evaporator-side heat exchanger in the refrigerant cycle, and the user-side heat exchanger 40 serves as a condenser-side heat exchanger in the refrigerant cycle; the variable frequency compressor 20, the throttling device 30, the refrigerant evaporation channel 12, and the refrigerant condensation channel 41 together define the refrigerant cycle control object of the water source heat pump unit.

[0109] like Figure 1 and Figure 2 As shown, the heat source-side heat exchanger 10 includes a heat source water channel 11 and a refrigerant evaporation channel 12. The heat source water channel 11 is used to connect to the central heating water circuit, so that the central heating water serves as the low-temperature heat source for the water source heat pump unit. Specifically, the heat source water channel 11 has a heat source water inlet 111 and a heat source water outlet 112. The heat source water inlet 111 is used to connect to the central heating water inlet pipe, and the heat source water outlet 112 is used to connect to the central heating water return pipe. The central heating water enters the heat source-side heat exchanger 10 through the heat source water inlet 111, exchanges heat with the refrigerant in the refrigerant evaporation channel 12 in the heat source-side heat exchanger 10, and then flows out through the heat source water outlet 112 and returns to the central heating water return pipe.

[0110] Furthermore, the heat source water channel 11 includes an inlet flow equalization chamber 113, an outlet flow collection chamber 114, and multiple parallel heat source water heat exchange branches 115. The inlet flow equalization chamber 113 is connected to the heat source water inlet 111, the outlet flow collection chamber 114 is connected to the heat source water outlet 112, and the multiple heat source water heat exchange branches 115 are connected between the inlet flow equalization chamber 113 and the outlet flow collection chamber 114. After entering the inlet flow equalization chamber 113, the central heating water is distributed to the multiple heat source water heat exchange branches 115, and then collected through the outlet flow collection chamber 114 before flowing out from the heat source water outlet 112.

[0111] The refrigerant evaporation channel 12 includes multiple refrigerant evaporation branches 121 corresponding to the heat exchange branches 115 of the heat source water, so as to improve the heat exchange uniformity between the central heating water and the refrigerant.

[0112] Furthermore, the refrigerant evaporation channel 12 also includes a refrigerant inlet manifold 122 and a refrigerant outlet manifold 123. The refrigerant inlet manifold 122 is connected to the outlet of the throttling device 30, and the refrigerant outlet manifold 123 is connected to the suction port 22 of the variable frequency compressor 20. Multiple refrigerant evaporation branches 121 are connected in parallel between the refrigerant inlet manifold 122 and the refrigerant outlet manifold 123. The low-temperature, low-pressure refrigerant, after being throttled by the throttling device 30, is distributed by the refrigerant inlet manifold 122 to the multiple refrigerant evaporation branches 121. After absorbing heat and evaporating in each refrigerant evaporation branch 121, the refrigerant is collected through the refrigerant outlet manifold 123 and flows to the suction port 22.

[0113] like Figure 1 and Figure 3As shown, the user-side heat exchanger 40 includes a refrigerant condensation channel 41 and a user water channel 42. The user water channel 42 has a user water inlet 421 and a user water outlet 422. The user water inlet 421 is connected to the user-side return water pipe 62, and the user water outlet 422 is connected to the user-side supply water pipe 61. The user-side supply water pipe 61 is used to connect at least one of the underfloor heating manifold 91 and the radiator 92. The built-in circulating water pump 50 is disposed in the user-side return water pipe 62 and is used to drive the user-side heating circulating water to circulate between the user-side heat exchanger 40 and the underfloor heating manifold 91 and / or the radiator 92.

[0114] The user-side heat exchanger 40 includes a main condensing heat exchange zone 411, a liquid equalization transition zone 412, and a subcooling heat exchange zone 413 arranged sequentially along the refrigerant flow direction. The main condensing heat exchange zone 411 is used to allow the high-temperature, high-pressure refrigerant discharged from the variable frequency compressor 20 to condense and exchange heat with the user-side heating circulating water. The liquid equalization transition zone 412 is used to equalize the pressure and distribute the flow of the liquid refrigerant entering the subcooling heat exchange zone 413. The subcooling heat exchange zone 413 is located upstream of the throttling device 30 and is used to allow the condensed liquid refrigerant to continue releasing heat to the user-side return water. The user water channel 42 is configured so that the user-side return water first passes through the subcooling heat exchange zone 413 and then through the main condensing heat exchange zone 411, forming a segmented counter-current heat exchange path where the user-side water flow is opposite to the refrigerant flow direction.

[0115] Furthermore, the liquid equalization transition zone 412 includes a liquid equalization chamber connected to the outlet of the main condensing heat exchange zone 411. The liquid equalization chamber is provided with a flow guide baffle, a liquid equalization orifice plate, or a plurality of liquid equalization through holes arranged at intervals along the width direction of the heat exchanger. The liquid equalization through holes are used to distribute the liquid refrigerant flowing out of the main condensing heat exchange zone 411 to the subcooling heat exchange zone 413.

[0116] Therefore, the lower-temperature user-side return water first absorbs the residual heat of the liquid refrigerant, making the refrigerant obtain a more stable subcooling, and then enters the main condensing heat exchange zone 411 to be further heated, thereby improving the actual water supply temperature on the user side and the heat pump cycle efficiency.

[0117] The variable frequency compressor 20 has an exhaust port 21 and an intake port 22. The exhaust port 21, the refrigerant condensation channel 41, the throttling device 30, the refrigerant evaporation channel 12, and the intake port 22 of the variable frequency compressor 20 are sequentially connected to form a refrigerant circulation loop for a compression heat pump. During operation, the low-temperature, low-pressure refrigerant absorbs heat from the central heating water and evaporates in the refrigerant evaporation channel 12, and then enters the variable frequency compressor 20 through the intake port 22. The variable frequency compressor 20 compresses the refrigerant to a high-temperature, high-pressure state and discharges it from the exhaust port 21. The high-temperature, high-pressure refrigerant enters the refrigerant condensation channel 41 and releases heat to the heating circulation water on the user side. After condensation, the refrigerant is throttled and depressurized by the throttling device 30 and then re-enters the refrigerant evaporation channel 12.

[0118] like Figure 1 and Figure 4 As shown, the water source heat pump unit also includes a heat source side inlet water temperature detector 71, a heat source side outlet water temperature detector 72, a user side actual supply water temperature detector 73, a user side return water temperature detector 74, a suction temperature detector 75, a suction pressure detector 76, an exhaust temperature detector 77, an exhaust pressure detector 78, and a throttling device inlet temperature detector 79. The heat source side inlet water temperature detector 71 is located near the heat source water inlet 111 and is used to detect the heat source side inlet water temperature; the heat source side outlet water temperature detector 72 is located near the heat source water outlet 112 and is used to detect the heat source side outlet water temperature; the user side actual supply water temperature detector 73 is located in the user side supply water pipeline 61 and is used to detect the user side actual supply water temperature; the user side return water temperature detector 74 is located in the user side return water pipeline 62 and is used to detect the user side return water temperature. The suction temperature detector 75 and the suction pressure detector 76 are disposed on the suction side of the variable frequency compressor 20, the discharge temperature detector 77 and the discharge pressure detector 78 are disposed on the discharge side of the variable frequency compressor 20, and the throttling device inlet temperature detector 79 is disposed on the inlet side of the throttling device 30.

[0119] The controller 70 is electrically connected to the variable frequency compressor 20, the throttling device 30, the built-in circulating water pump 50, the heat source side inlet water temperature detector 71, the heat source side outlet water temperature detector 72, the user side actual water supply temperature detector 73, the user side return water temperature detector 74, the suction temperature detector 75, the suction pressure detector 76, the exhaust temperature detector 77, the exhaust pressure detector 78, and the throttling device inlet temperature detector 79.

[0120] The controller 70 adjusts the operating frequency of the variable frequency compressor 20, the opening degree of the throttling device 30, and the rotational speed of the built-in circulating water pump 50 in conjunction with the heat source side temperature parameters and the user side temperature parameters. The heat source side temperature parameters include at least the heat source side outlet water temperature and the heat source side inlet and outlet water temperature difference, and include at least one of the heat source side inlet water temperature and the heat source side outlet water temperature change rate. The user side temperature parameters include at least the user side target water supply temperature and the user side actual water supply temperature, and include at least one of the user side return water temperature, the user side supply and return water temperature difference, and the user side actual water supply temperature change rate.

[0121] Specifically, the controller 70 generates a heat source side heat extraction margin parameter based on the heat source side temperature parameter and a user side load demand parameter based on the user side temperature parameter. When the inlet and outlet water temperature difference on the heat source side is greater than the preset upper limit of the inlet and outlet water temperature difference on the heat source side, or when the outlet water temperature on the heat source side is lower than the preset lower limit of the outlet water temperature on the heat source side, the controller 70 determines that the heat source side heat extraction margin parameter does not meet the preset heat extraction margin condition, and restricts the increase or decrease of the operating frequency of the variable frequency compressor 20. In this way, the heat exchanger 10 on the heat source side can avoid excessive heat extraction from the central heating water, reducing the risk of abnormally low central heating return water temperature.

[0122] Further, the heat source side heat extraction margin parameter is determined based on the inlet and outlet water temperature difference, the outlet water temperature, and the outlet water temperature change rate. When the inlet and outlet water temperature difference is not greater than a preset upper limit, the outlet water temperature is not lower than a preset lower limit, and the outlet water temperature decrease rate is not greater than a preset lower limit, the controller 70 determines that the heat source side heat extraction margin parameter meets the preset heat extraction margin condition. When the inlet and outlet water temperature difference is greater than the preset upper limit, the outlet water temperature is lower than the preset lower limit, or the outlet water temperature decrease rate is greater than the preset lower limit, the controller 70 determines that the heat source side heat extraction margin parameter does not meet the preset heat extraction margin condition.

[0123] To standardize the calculation of various temperature parameters, the target water supply temperature on the user side is a set value within the target water supply temperature range on the user side. The upper and lower limits of the target water supply temperature range on the user side are determined according to the type of heating terminal on the user side. The temperature difference between the inlet and outlet water on the heat source side is the inlet water temperature on the heat source side minus the outlet water temperature on the heat source side. The temperature difference between the supply and return water on the user side is the actual supply water temperature on the user side minus the return water temperature on the user side. The rate of change of the outlet water temperature on the heat source side is the difference between the outlet water temperature on the heat source side in the current sampling period and the outlet water temperature on the heat source side in the previous sampling period divided by the preset sampling period. When the rate of change of the outlet water temperature on the heat source side is negative, its absolute value is the rate of decrease of the outlet water temperature on the heat source side. The rate of change of the actual water supply temperature on the user side is calculated in the same way. When the rate of change of the actual water supply temperature on the user side is positive, its value is the rate of increase of the actual water supply temperature on the user side. The rate of change of user-side return water temperature is the difference between the user-side return water temperature in the current sampling period and the user-side return water temperature in the previous sampling period, divided by the preset sampling period. When the rate of change of user-side return water temperature is positive, its value represents the rate of increase of user-side return water temperature. When the rate of change of user-side return water temperature is negative, its absolute value represents the rate of decrease of user-side return water temperature.

[0124] The controller 70 performs moving average filtering or median filtering on multiple consecutive sampled values, and changes the control state after the corresponding judgment condition is met a preset number of times. The corresponding recovery condition is provided with a preset hysteresis to avoid frequent switching of the control state caused by detection fluctuations.

[0125] The heat margin parameter taken from the heat source side can be determined by threshold judgment, table lookup judgment, or weighted scoring method.

[0126] Furthermore, the controller 70 pre-stores the correspondence between the heat source side heat extraction margin parameter and the upper frequency limit of the variable frequency compressor 20. This correspondence is calibrated through operational tests under different heat source side temperature and flow conditions and stored in the controller 70. The upper frequency limit does not increase as the heat source side heat extraction margin parameter decreases. The controller 70 queries the corresponding upper frequency limit based on the current heat source side heat extraction margin parameter; when the target operating frequency is higher than the upper frequency limit, the target operating frequency is limited to the upper frequency limit; when the current operating frequency of the variable frequency compressor 20 is higher than the upper frequency limit, the operating frequency of the variable frequency compressor 20 is reduced until it is no higher than the upper frequency limit.

[0127] Furthermore, the controller 70 is also used to perform self-learning control of the heat extraction capacity on the heat source side. Specifically, within a preset identification time after the water source heat pump unit starts, the controller 70 controls the variable frequency compressor 20 to operate at a preset trial frequency, controls the throttling device 30 to maintain a preset trial opening, and controls the built-in circulating water pump 50 to operate at a preset trial speed; within the preset identification time, the controller 70 acquires the heat source side inlet water temperature, heat source side outlet water temperature, heat source side inlet and outlet water temperature difference, heat source side outlet water temperature decrease rate, and user side actual water supply temperature increase rate, and determines the heat extraction capacity level on the heat source side based on the heat source side outlet water temperature decrease rate, heat source side inlet and outlet water temperature difference, and user side actual water supply temperature increase rate.

[0128] The heat source side heat extraction margin parameter is used to characterize the real-time heat extraction safety margin under the current operating conditions, and the heat source side heat extraction capacity level is used to characterize the comprehensive heat extraction capacity of the centralized heating water circuit obtained after a preset identification time. The two are used for real-time limiting and operating curve selection, respectively.

[0129] Furthermore, the preset identification time can be 1 min to 10 min, and the preset testing frequency can be 30% to 60% of the rated frequency of the variable frequency compressor 20. During the preset identification time, the controller 70 does not directly control the variable frequency compressor 20 to rapidly increase its frequency according to the target water supply temperature on the user side, but instead uses the preset testing frequency, the preset testing opening degree, and the preset testing speed to perform a short-term identification of the heat extraction capacity of the current central heating water circuit.

[0130] The preset test opening degree is the initial opening degree of the electronic expansion valve that corresponds to the preset test frequency and can maintain the intake superheat within the preset superheat range; the preset test speed is the speed of the built-in circulating water pump that ensures the circulating water flow rate in the user water channel 42 is not lower than the preset minimum allowable flow rate. During the self-learning process, when the exhaust safety status does not meet the preset exhaust safety conditions, the intake superheat is lower than the preset superheat lower limit, or the heat source side heat extraction margin parameter does not meet the preset heat extraction margin conditions, the controller 70 terminates the current self-learning process and enters the protection operation state. The threshold values ​​for the rate of decrease of the outlet water temperature on the first heat source side, the threshold values ​​for the rate of decrease of the outlet water temperature on the second heat source side, the threshold values ​​for the temperature difference between the inlet and outlet water on the first heat source side, the threshold values ​​for the temperature difference between the inlet and outlet water on the second heat source side, and the preset heat extraction capacity identification supply water temperature rise rate threshold are pre-calibrated and stored in the controller 70 through high heat extraction capacity, medium heat extraction capacity, and low heat extraction capacity test conditions. During calibration, the average values ​​of parameters during the stable operation phase of each test condition were collected, and the median value between the average values ​​of parameters corresponding to adjacent heat extraction capacity levels was determined as the boundary threshold of the corresponding level.

[0131] The heat extraction capacity level of the heat source side includes high heat extraction capacity level, medium heat extraction capacity level and low heat extraction capacity level. Among them, the threshold for the rate of decrease of the outlet water temperature of the second heat source side is greater than the threshold for the rate of decrease of the outlet water temperature of the first heat source side, and the threshold for the temperature difference between the inlet and outlet water of the second heat source side is greater than the threshold for the temperature difference between the inlet and outlet water of the first heat source side. When the rate of temperature drop of the outlet water on the heat source side is less than the threshold for the rate of temperature drop of the outlet water on the first heat source side, the temperature difference between the inlet and outlet water on the heat source side is less than the threshold for the temperature difference between the inlet and outlet water on the first heat source side, and the rate of temperature rise of the actual water supply on the user side is greater than the preset threshold for the rate of temperature rise of the water supply for identifying heat extraction capacity, the controller 70 determines that the current centralized heating water circuit is at a high heat extraction capacity level; when the rate of temperature drop of the outlet water on the heat source side is greater than the threshold for the rate of temperature drop of the outlet water on the second heat source side, or the temperature difference between the inlet and outlet water on the heat source side is greater than the threshold for the temperature difference between the inlet and outlet water on the second heat source side, or the rate of temperature rise of the actual water supply on the user side is lower than the preset threshold for the rate of temperature rise of the water supply for identifying heat extraction capacity, the controller 70 determines that the current centralized heating water circuit is at a low heat extraction capacity level; all other cases are determined to be at a medium heat extraction capacity level.

[0132] The controller 70 selects the corresponding frequency increase curve of the variable frequency compressor, the opening curve of the throttling device, the speed curve of the built-in circulating water pump, and the opening curve of the bypass regulating valve on the heat source side according to the heat source side's heat extraction capacity level. When the heat source side's heat extraction capacity level is high, the controller 70 allows the variable frequency compressor 20 to increase its frequency at a first frequency increase rate and allows the throttling device 30 to adjust at a first opening change rate. When the heat source side's heat extraction capacity level is medium, the controller 70 controls the variable frequency compressor 20 to increase its frequency at a second frequency increase rate lower than the first frequency increase rate. When the heat source side's heat extraction capacity level is low, the controller 70 restricts the increase of the operating frequency of the variable frequency compressor 20, reduces the opening change range of the throttling device 30, restricts the increase or decrease of the speed of the built-in circulating water pump 50, and / or increases the opening of the heat source side bypass regulating valve 81.

[0133] Furthermore, the controller 70 updates the heat extraction capacity level of the heat source side according to a preset update cycle during the operation of the water source heat pump unit. When the rate of decrease in the outlet water temperature of the heat source side decreases, the temperature difference between the inlet and outlet water of the heat source side decreases, and the rate of increase in the actual supply water temperature of the user side increases within several consecutive preset update cycles, the controller 70 increases the heat extraction capacity level of the heat source side; when the rate of decrease in the outlet water temperature of the heat source side increases, the temperature difference between the inlet and outlet water of the heat source side increases, or the rate of increase in the actual supply water temperature of the user side decreases within several consecutive preset update cycles, the controller 70 decreases the heat extraction capacity level of the heat source side. Thus, the water source heat pump unit can automatically select the operating curve according to the actual heating capacity of different centralized heating networks, avoiding excessive heat extraction by the heat source side due to excessively rapid compressor frequency increase during the start-up phase, and also avoiding excessively slow temperature rise response when the heat extraction capacity of the heat source side is sufficient.

[0134] The self-learning control of the heat source side's heat extraction capacity includes: S61, starting the water source heat pump unit; S62, controlling the variable frequency compressor 20 to operate at a preset test frequency, controlling the throttling device 30 to maintain a preset test opening, and controlling the built-in circulating water pump 50 to operate at a preset test speed; S63, acquiring the rate of decrease in outlet water temperature on the heat source side, the temperature difference between inlet and outlet water on the heat source side, and the rate of increase in actual supply water temperature on the user side; S64, determining the heat source side's heat extraction capacity level based on the rate of decrease in outlet water temperature on the heat source side, the temperature difference between inlet and outlet water on the heat source side, and the rate of increase in actual supply water temperature on the user side; S65a, when determined to be a high heat extraction capacity level, selecting the first set of operating curves corresponding to the high heat extraction capacity level; S65b, when determined to be a medium heat extraction capacity level, selecting the second set of operating curves corresponding to the medium heat extraction capacity level; S65c, when determined to be a low heat extraction capacity level, limiting the... The operating frequency of the variable frequency compressor 20 increases, and the opening range of the throttling device 30 is reduced, the speed of the built-in circulating water pump 50 is limited or reduced, and / or the opening of the heat source side bypass regulating valve 81 is increased; S66, the heat source side heat extraction capacity level is re-evaluated according to the preset update cycle; S67, when the heat source side heat extraction capacity level changes, or the actual operating parameters deviate from the preset allowable range corresponding to the current operating curve for multiple consecutive preset update cycles, it is determined that the control parameters need to be corrected; otherwise, it is determined that the control parameters do not need to be corrected; S68, when the control parameters need to be corrected, the frequency increase curve of the variable frequency compressor 20, the opening curve of the throttling device 30, the speed curve of the built-in circulating water pump 50, and / or the opening curve of the heat source side bypass regulating valve 81 are updated; when the control parameters do not need to be corrected, the current operating curve is maintained.

[0135] The user-side load demand parameters are determined based on the temperature deviation between the target supply water temperature and the actual supply water temperature, the supply and return water temperature difference, and the rate of change of the actual supply water temperature. When the temperature deviation increases, the supply and return water temperature difference increases, or the rate of change of the actual supply water temperature is lower than a preset load judgment supply water temperature rise rate threshold, the controller 70 determines that the user-side load demand parameters increase. When the actual supply water temperature enters the target supply water temperature range or exceeds the upper limit of the target supply water temperature range, and the return water temperature change rate is not less than zero and is lower than a preset load reduction judgment return water temperature rise rate threshold, the controller 70 determines that the user-side load demand parameters decrease. When the return water temperature change rate is negative, the user-side load demand parameters are not determined to decrease based on the return water temperature change rate. The preset load judgment supply water temperature rise rate threshold and the preset load reduction judgment return water temperature rise rate threshold are pre-calibrated through temperature rise tests under different user-side heating load conditions and stored in the controller 70.

[0136] The preset threshold for the rate of increase of water supply temperature for identifying heat extraction capacity and the preset threshold for the rate of increase of water supply temperature for judging load are calibrated according to the requirements for identifying the heat extraction capacity level on the heat source side and the requirements for judging load on the user side, respectively. The values ​​of the two can be the same or different.

[0137] Furthermore, the water source heat pump unit also includes a heat source side bypass pipe 80 and a heat source side bypass regulating valve 81. The heat source side bypass pipe 80 is connected between the heat source water inlet 111 and the heat source water outlet 112, and the heat source side bypass regulating valve 81 is disposed in the heat source side bypass pipe 80 and electrically connected to the controller 70. When the heat source side heat extraction margin parameter does not meet the preset heat extraction margin condition, the controller 70 increases the opening of the heat source side bypass regulating valve 81, so that some of the central heating water bypasses the heat source side heat exchanger 10 and mixes with the water outlet at the heat source water outlet 112, thereby limiting the heat extraction of the central heating water by the heat source side heat exchanger 10.

[0138] In this embodiment, the controller 70 determines the corresponding evaporation saturation temperature based on the suction pressure, and determines the suction superheat based on the difference between the suction temperature and the evaporation saturation temperature; the controller 70 determines the corresponding condensation saturation temperature based on the discharge pressure, and determines the refrigerant subcooling based on the difference between the condensation saturation temperature and the inlet temperature of the throttling device; the controller 70 determines the discharge safety status based on the discharge temperature and discharge pressure.

[0139] When the exhaust temperature is not higher than the preset exhaust temperature limit and the exhaust pressure is not higher than the preset exhaust pressure limit, the controller 70 determines that the exhaust safety status meets the preset exhaust safety conditions; when the exhaust temperature is higher than the preset exhaust temperature limit or the exhaust pressure is higher than the preset exhaust pressure limit, the controller 70 determines that the exhaust safety status does not meet the preset exhaust safety conditions, and prioritizes reducing the operating frequency of the variable frequency compressor 20.

[0140] In this embodiment, the preset operating conditions that allow for increasing the operating frequency of the variable frequency compressor 20 include: the exhaust safety state meets preset exhaust safety conditions, the suction superheat is within a preset superheat range, the refrigerant subcooling is within a preset subcooling range, and the heat source side heat margin parameters meet preset heat margin conditions. The preset exhaust safety conditions are that the exhaust temperature is not higher than a preset upper limit for exhaust temperature and the exhaust pressure is not higher than a preset upper limit for exhaust pressure; the preset superheat range is defined by a preset lower limit for superheat and a preset upper limit for superheat; the preset subcooling range is defined by a preset lower limit for subcooling and a preset upper limit for subcooling. The preset upper limit for exhaust pressure is determined based on the correspondence between the pressure and saturation temperature of the refrigerant used, the allowable exhaust pressure of the variable frequency compressor 20, and a preset maximum condensing saturation temperature, and the lower of these pressure limits is selected.

[0141] Specifically, when the suction superheat is lower than the preset lower limit of superheat, the controller 70 reduces the opening of the throttling device 30 to reduce the refrigerant flow into the refrigerant evaporation channel 12, thereby reducing the risk of liquid slugging in the variable frequency compressor 20; when the suction superheat is higher than the preset upper limit of superheat, and the heat source side heat margin parameter meets the preset heat margin condition, the controller 70 increases the opening of the throttling device 30 to increase the refrigerant supply on the evaporation side; when the refrigerant subcooling is lower than the preset lower limit of subcooling, and the suction superheat is within the preset superheat range and the exhaust... When the safety conditions meet the preset exhaust safety requirements, the controller 70 limits the maximum allowable opening of the throttling device 30 and / or increases the speed of the built-in circulating water pump 50 to increase the condensation and subcooling heat exchange of the user-side heat exchanger 40; when the actual water supply temperature on the user side enters the target water supply temperature range on the user side, the controller 70 maintains or reduces the operating frequency of the variable frequency compressor 20; when the actual water supply temperature on the user side is higher than the upper limit of the target water supply temperature range on the user side, the controller 70 preferentially reduces the operating frequency of the variable frequency compressor 20.

[0142] In one implementation, when the temperature difference between the supply and return water on the user side is greater than a preset upper limit for the user side supply and return water temperature difference, and the actual water supply temperature change rate on the user side is lower than a preset lower limit for the actual water supply temperature change rate on the user side, the controller 70 increases the speed of the built-in circulating water pump 50 within a preset allowable speed range; when the temperature difference between the supply and return water on the user side is less than the preset lower limit for the user side supply and return water temperature difference, and the actual water supply temperature on the user side enters the target water supply temperature range on the user side or exceeds the upper limit of the range, or the actual water supply temperature change rate on the user side exceeds the preset upper limit for the actual water supply temperature change rate on the user side, the controller 70 decreases the speed of the built-in circulating water pump 50. The speed of the built-in circulating water pump 50 is adjusted step by step according to a preset speed step size, and the speed adjustment is performed after the corresponding conditions are continuously met a preset number of times. The preset upper and lower limits of the user-side supply and return water temperature difference, the preset upper and lower limits of the user-side actual supply water temperature change rate, and the preset allowable speed range are calibrated through heating tests of each heating terminal under different loads. During calibration, the speed of the built-in circulating water pump 50 is gradually changed within the allowable speed range, and the user-side supply and return water temperature difference, user-side actual supply water temperature change rate, and pump speed range that enable the user-side actual supply water temperature to enter the user-side target supply water temperature range and not exceed the sum of the upper limit of the range and the preset hysteresis are determined as the corresponding preset ranges. The difference between adjacent available speed levels is determined as the preset speed step size. The preset confirmation number is 2 to 5 times. The preset heat preservation circulation speed is the built-in circulating water pump speed that enables the user-side heating circulating water flow rate to be no less than the preset minimum allowable flow rate and maintains the user-side actual supply water temperature within the user-side target supply water temperature range. The preset heat preservation circulation speed is calibrated through steady-state heat preservation tests of different user-side heating terminals and stored in the controller 70. This allows the pump adjustment parameters to match the thermal inertia and flow demand of the heating terminal, and reduces the risk of frequent pump speed adjustments caused by single sampling fluctuations.

[0143] The controller 70 further includes a heating terminal identification unit 701. The heating terminal identification unit 701 identifies the current user-side heating terminal as a floor heating terminal, a radiator terminal, or a hybrid terminal (floor heating and radiator) based on the actual user-side supply water temperature, user-side return water temperature, the rotation speed of the built-in circulating water pump 50, the user-side supply and return water temperature difference, and the user-side actual supply water temperature change rate. When identified as a floor heating terminal, the controller 70 executes a first heating control mode; when identified as a radiator terminal, the controller 70 executes a second heating control mode; and when identified as a hybrid terminal (floor heating and radiator), the controller 70 executes a third heating control mode. The target user-side supply water temperature range corresponding to the first heating control mode is lower than the target user-side supply water temperature range corresponding to the second heating control mode. The third heating control mode adjusts the rotation speed of the built-in circulating water pump 50 based on the user-side return water temperature change rate and limits the rate of increase of the user-side actual supply water temperature to avoid the floor heating terminal heating up too quickly or the radiator terminal providing insufficient heat.

[0144] The underfloor heating terminal of this invention includes an underfloor heating manifold 91 and underfloor heating pipes connected to the underfloor heating manifold 91, and the radiator terminal includes a radiator 92 and its connecting pipes.

[0145] In one embodiment, the heating terminal identification unit 701 identifies the user-side heating terminal type according to a preset terminal identification table. The preset terminal identification table corresponds to underfloor heating terminals, radiator terminals, and mixed underfloor heating and radiator terminals, and sets preset scores for each type of heating terminal, including the user-side actual supply water temperature range, user-side return water temperature range, built-in circulating water pump speed range, user-side supply and return water temperature difference range, user-side actual supply water temperature change rate range, and corresponding scores for each actual operating parameter. The preset terminal identification table is pre-stored in the controller 70 and can be updated based on user settings, historical operating data, or debugging parameters.

[0146] The heating terminal identification unit 701 performs heating terminal type identification within a preset stable identification time. During this time, the operating frequency of the variable frequency compressor 20 and the speed of the built-in circulating water pump 50 remain within their respective preset identification ranges. The heating terminal identification unit 701 compares the collected actual operating parameters with the preset parameter ranges corresponding to the heating terminals in the preset terminal identification table. When an actual operating parameter falls within the preset parameter range of the corresponding heating terminal, the feature score of that heating terminal is increased by the preset score corresponding to that actual operating parameter. The preset scores corresponding to all actual operating parameters are then summed to obtain the underfloor heating terminal feature score, the radiator terminal feature score, and the mixed underfloor heating and radiator terminal feature score. The heating terminal identification unit 701 determines the heating terminal type with the highest feature score as the current user-side heating terminal type. When the difference between the highest and second-highest feature scores is less than a preset score difference, if a previous identification result exists, the previous identification result is maintained; otherwise, the current user-side heating terminal type is determined to be a mixed underfloor heating and radiator terminal. This reduces the impact of overlapping temperature ranges at different heating terminals on the identification results, improving the accuracy and stability of heating terminal identification.

[0147] The preset terminal identification table is generated through a terminal calibration process. During calibration, under stable heating conditions at the underfloor heating terminal, radiator terminal, and a combined underfloor heating and radiator terminal, various actual operating parameters are collected according to a preset calibration sampling cycle. After removing data from the startup phase, the corresponding preset parameter ranges are determined based on the statistical range of each actual operating parameter during the stable operation phase and the preset calibration margin. The preset calibration margin is not less than the measurement error of the corresponding detection component and is determined based on the fluctuation amplitude of the corresponding actual operating parameters during the stable operation phase. The preset identification range is determined based on the parameter range that the corresponding execution component can stably operate during the terminal calibration process, and the preset stable identification time is determined based on the longest stable time required for each actual operating parameter to enter the corresponding preset parameter range. One point is added when each actual operating parameter falls into the preset parameter range of the corresponding heating terminal. The maximum feature score for each heating terminal is 5 points, and the preset score difference is 1 point. After calibration, each preset parameter range and corresponding score is stored in the controller 70. This allows the identification table to cover detection errors and stable operation fluctuations, and reduces misidentification caused by differences in terminal thermal inertia.

[0148] In this embodiment, the first heating control mode corresponds to underfloor heating, and the target water supply temperature range on the user side can be set to 35℃~45℃; the second heating control mode corresponds to radiator heating, and the target water supply temperature range on the user side can be set to 45℃~60℃; the third heating control mode corresponds to a mixed underfloor heating and radiator heating system, and the target water supply temperature range on the user side can be set to 40℃~55℃. In other embodiments, the above temperature ranges can be adjusted according to the building load, the type of heating terminal on the user side, and the user settings.

[0149] In the third heating control mode, when the rate of change of the user-side return water temperature is not less than zero, the controller 70 adjusts the speed of the built-in circulating water pump 50 based on the comparison between the user-side return water temperature rise rate and the preset lower limit of the rise rate of the mixed terminal return water temperature. When the user-side return water temperature rise rate is lower than the preset lower limit of the rise rate ... The lower limit of the preset rate of increase of return water temperature at the mixing terminal and the upper limit of the preset rate of increase of supply water temperature at the mixing terminal are pre-calibrated through the heating test of the mixing terminal of underfloor heating and radiator heating and stored in the controller 70.

[0150] The heating control method in this embodiment includes the following steps:

[0151] S1, acquire the temperature parameters on the heat source side and the temperature parameters on the user side. The temperature parameters on the heat source side include at least the outlet water temperature on the heat source side and the temperature difference between the inlet and outlet water on the heat source side, and include at least one of the inlet water temperature on the heat source side and the rate of change of the outlet water temperature on the heat source side; the temperature parameters on the user side include at least the target supply water temperature on the user side and the actual supply water temperature on the user side, and include at least one of the return water temperature on the user side, the temperature difference between the supply and return water on the user side, and the rate of change of the actual supply water temperature on the user side. Simultaneously, the controller 70 also acquires the suction temperature, suction pressure, exhaust temperature, exhaust pressure, and the inlet temperature of the throttling device.

[0152] The controller 70 determines the user-side supply and return water temperature difference based on the user-side actual water supply temperature and the user-side return water temperature, determines the user-side actual water supply temperature change rate based on the continuously collected user-side actual water supply temperature, and determines the user-side return water temperature change rate based on the continuously collected user-side return water temperature.

[0153] S2, determine the heat source side heat extraction margin parameter based on the heat source side temperature parameter, determine the user side load demand parameter based on the user side temperature parameter, determine the suction superheat based on the suction temperature and suction pressure, determine the refrigerant subcooling based on the discharge pressure and throttling device inlet temperature, and determine the discharge safety status based on the discharge temperature and discharge pressure.

[0154] S3, based on the heat source side heat margin parameters, the user side load demand parameters, the suction superheat, the refrigerant subcooling, and the exhaust safety status, determine the target operating frequency of the variable frequency compressor 20, the target opening degree of the throttling device 30, and the target speed of the built-in circulating water pump 50.

[0155] S4, control the operation of the variable frequency compressor 20 according to the target operating frequency, control the operation of the throttling device 30 according to the target opening degree, and control the operation of the built-in circulating water pump 50 according to the target speed.

[0156] S5 compares the actual water supply temperature on the user side with the target water supply temperature range on the user side during operation.

[0157] When the actual water supply temperature on the user side is lower than the lower limit of the target water supply temperature range on the user side, and the heat extraction margin parameter on the heat source side meets the preset heat extraction margin condition, the operating frequency of the variable frequency compressor 20 is increased.

[0158] When the actual water supply temperature on the user side is lower than the lower limit of the target water supply temperature range on the user side, but the heat extraction margin parameter on the heat source side does not meet the preset heat extraction margin condition, the operating frequency of the variable frequency compressor 20 is restricted from increasing, and the target operating frequency is restricted to the upper limit of the frequency corresponding to the current heat extraction margin parameter on the heat source side.

[0159] When the actual water supply temperature on the user side enters the target water supply temperature range on the user side, the operating frequency of the variable frequency compressor is maintained or reduced, and the built-in circulating water pump 50 is maintained at a preset heat preservation circulation speed.

[0160] When the actual water supply temperature on the user side is higher than the upper limit of the target water supply temperature range on the user side, the operating frequency of the variable frequency compressor is reduced, and the built-in circulating water pump 50 is maintained at the preset heat preservation circulation speed.

[0161] In step S3, the controller 70 determines the target operating frequency of the variable frequency compressor 20, the target opening degree of the throttling device 30, and the target speed of the built-in circulating water pump 50 according to priority control rules. The priority control rules include: when the exhaust pressure is higher than a preset upper limit for exhaust pressure or the exhaust temperature is higher than a preset upper limit for exhaust temperature, the controller 70 prioritizes reducing the operating frequency of the variable frequency compressor 20 and restricts the increase in the opening degree of the throttling device 30; when the suction superheat is lower than a preset lower limit for superheat, the controller 70 prioritizes decreasing the opening degree of the throttling device 30; when the heat source side heat extraction margin parameter does not meet the preset heat extraction margin condition, the controller 70 prioritizes restricting the increase or decrease in the operating frequency of the variable frequency compressor 20, adjusts the opening degree of the throttling device 30 according to the deviation of the suction superheat from the preset superheat range, and adjusts the speed of the built-in circulating water pump 50 according to the temperature difference between the user-side supply and return water and the rate of change of the actual supply water temperature on the user side.

[0162] When the refrigerant subcooling is lower than the preset subcooling lower limit, and the suction superheat is within the preset superheat range and the exhaust safety condition meets the preset exhaust safety condition, the maximum allowable opening of the throttling device 30 is preferentially limited and / or the speed of the built-in circulating water pump 50 is increased within the preset allowable speed range.

[0163] When the exhaust safety status meets the preset exhaust safety conditions, the intake superheat is within the preset superheat range, the refrigerant subcooling is within the preset subcooling range, the heat source side heat margin parameter meets the preset heat margin conditions, and the user side load demand parameter increases, the controller 70 increases the operating frequency of the variable frequency compressor 20.

[0164] When the actual water supply temperature on the user side enters the target water supply temperature range on the user side, the operating frequency of the variable frequency compressor 20 is maintained or reduced, and the speed of the built-in circulating water pump 50 is maintained or reduced according to the change rate of the return water temperature on the user side.

[0165] When two or more priority control rules are satisfied simultaneously, they are executed according to the order in which they are arranged, and the priority control rule that is arranged earlier overrides the priority control rule that is arranged later.

[0166] The working principle of this embodiment is as follows:

[0167] Central heating water enters the heat source-side heat exchanger 10 through the heat source water inlet 111. Within the heat source water channel 11, it exchanges heat with the low-temperature, low-pressure refrigerant in the refrigerant evaporation channel 12, causing the refrigerant to absorb low-grade heat from the central heating water and evaporate. The evaporated refrigerant then enters the variable frequency compressor 20 through the suction port 22, where it is compressed into a high-temperature, high-pressure refrigerant. After compression, the refrigerant enters the user-side heat exchanger 40 through the discharge port 21, and then flows into the user's water channel 42 within the refrigerant condensation channel 41. The side heating circulating water releases heat, and the condensed refrigerant re-enters the heat source side heat exchanger 10 after being throttled and depressurized by the throttling device 30. The user side heating circulating water, driven by the built-in circulating water pump 50, enters the user side heat exchanger 40 through the user side return water pipe 62. It first flows through the cold heat exchange zone 413 to absorb the residual heat of the liquid refrigerant, and then flows through the main condensing heat exchange zone 411 to be further heated. Subsequently, it is transported to the underfloor heating manifold 91 and / or radiator 92 through the user side supply water pipe 61.

[0168] Through the above process, this embodiment can control the heat extraction from the central heating water when the temperature is low or the heating capacity fluctuates. By coordinating the variable frequency compressor 20, the throttling device 30, and the built-in circulating water pump 50, the temperature of the heating circulating water on the user side is increased. At the same time, excessive heat extraction is limited by the heat source side heat extraction margin parameter, and the refrigerant circulation is kept stable by the suction superheat, refrigerant subcooling, and exhaust safety status. The heating terminal identification unit 701 is adapted to the underfloor heating terminal, radiator terminal, or a combination of underfloor heating and radiator terminals. Thus, it has the effects of stable temperature rise, the heat source side return water temperature is not prone to abnormal drop, the compressor operation safety is high, the terminal adaptability is strong, and it is not easy to frequently start and stop when operating at low load.

[0169] In one specific embodiment, the inlet water temperature on the heat source side of the centralized heating system is 28℃~35℃, the lower limit of the outlet water temperature on the heat source side is set to 24℃~26℃, the upper limit of the preset temperature difference between the inlet and outlet water on the heat source side is set to 6℃~8℃, and the preset sampling period is 10 s~60 s. The target water supply temperature on the user side is set according to the type of heating terminal on the user side. Specifically, the target water supply temperature range for the user side corresponding to the underfloor heating terminal is 35℃~45℃, the target water supply temperature range for the user side corresponding to the radiator terminal is 45℃~60℃, and the target water supply temperature range for the user side corresponding to the combined underfloor heating and radiator terminal is 40℃~55℃. The variable frequency compressor 20 has an operating frequency adjustment range of 20 Hz to 90 Hz, the built-in circulating water pump 50 has a speed adjustment range of 1200 r / min to 3200 r / min, the throttling device 30 is an electronic expansion valve with an opening adjustment range of 80 steps to 480 steps, the preset control range of suction superheat is 4 ℃ to 8 ℃, the preset control range of refrigerant subcooling is 3 ℃ to 7 ℃, and the upper limit of exhaust temperature is set to 90 ℃ to 105 ℃. When the actual water supply temperature on the user side is lower than the lower limit of the target water supply temperature range on the user side, and the temperature difference between the inlet and outlet water on the heat source side is no greater than 6 ℃ and the outlet water temperature on the heat source side is no lower than 25 ℃, the controller 70 increases the operating frequency of the variable frequency compressor 20, for example, gradually increasing it from 35 Hz to 60 Hz~75 Hz, and increases the speed of the built-in circulating water pump 50 to 2200 r / min~2800 r / min to accelerate the heating of the circulating water on the user side; when the outlet water temperature on the heat source side is lower than 25 ℃ or the temperature difference between the inlet and outlet water on the heat source side is greater than 6 ℃, the controller 70 increases the operating frequency of the variable frequency compressor 20, for example, gradually increasing it from 35 Hz to 60 Hz~75 Hz, and increases the speed of the built-in circulating water pump 50 to 2200 r / min~2800 r / min, in order to accelerate the heating of the circulating water on the user side; when the outlet water temperature on the heat source side is lower than 25 ℃ or the temperature difference between the inlet and outlet water on the heat source side is greater than 6 ℃, the controller 70 increases the operating frequency of the variable frequency compressor 20, for example, gradually increasing it from 35 Hz to 60 Hz~75 Hz, and increases the operating frequency of the built-in circulating water pump 50 to 2200 r / min~2800 r / min, in order to accelerate the heating of the circulating water on the user side. At ℃, the controller 70 determines that the heat extraction margin parameter on the heat source side does not meet the preset heat extraction margin condition, restricts the variable frequency compressor 20 from continuing to increase the frequency, and limits the target operating frequency to below the corresponding upper frequency limit; the throttling device 30 adjusts the opening degree according to the deviation of the suction superheat degree from the preset superheat degree range, and the built-in circulating water pump 50 adjusts the speed according to the temperature difference between the supply and return water on the user side and the rate of change of the actual supply water temperature on the user side, while increasing the opening degree of the bypass regulating valve 81 on the heat source side, so that some of the centralized heating water bypasses the heat exchanger 10 on the heat source side and mixes with the water at the outlet 112 of the heat source water, thereby restoring the outlet water temperature on the heat source side to the allowable range.

[0170] Under the design and operating conditions corresponding to this embodiment, when the inlet water temperature on the heat source side and the initial return water temperature on the user side are both approximately 30°C, the actual water supply temperature on the user side rises to 42°C to 48°C within 25 to 35 minutes after the unit starts up. After entering a stable operating state, the actual water supply temperature on the user side remains within the target water supply temperature range, with a fluctuation range not exceeding ±2°C, preferably not exceeding ±1.5°C; the outlet water temperature on the heat source side remains above 25°C to reduce the impact of the heat extraction process on the return water temperature of the centralized heating system. During operation, the suction superheat is maintained at 4°C to 8°C, and the refrigerant subcooling is maintained at 3°C ​​to 7°C, thereby reducing the risk of liquid slugging in the variable frequency compressor 20, excessively high exhaust temperature, and unstable adjustment of the throttling device 30. The above operating results show that this embodiment can take into account the user-side heating rate, the stability of the actual water supply temperature on the user side, the temperature protection on the heat source side, and the stability of the refrigerant circulation under the condition of using low-temperature centralized heating water as a low-temperature heat source, and can be adapted to underfloor heating terminals, radiator terminals, and mixed terminals of underfloor heating and radiator heating.

[0171] It should be noted that the terms "first," "second," etc., used in this invention are only used to distinguish identical or similar components and do not indicate order, quantity, or importance; the directional terms such as "upper," "lower," "inner," "outer," "front," and "rear" refer to the installation state of the water source heat pump unit shown in the accompanying drawings and do not constitute a limitation on the actual installation direction. The above embodiments are only preferred embodiments of this invention, and equivalent substitutions or modifications made by those skilled in the art without departing from the concept of this invention should all fall within the protection scope of this invention.

Claims

1. A low-temperature centralized heating heat source adaptive variable frequency water source heat pump unit, comprising a heat source-side heat exchanger, a variable frequency compressor, a throttling device, a user-side heat exchanger, a built-in circulating water pump, a user-side water supply pipeline, a user-side return water pipeline, and a controller, characterized in that: The heat source side heat exchanger includes a heat source water channel and a refrigerant evaporation channel, and the heat source water channel is used to connect to the centralized heating water circuit. The heat source-side heat exchanger serves as an evaporation-side heat exchanger, used to allow the refrigerant to evaporate and absorb heat within the refrigerant evaporation channel; the user-side heat exchanger serves as a condensation-side heat exchanger, used to allow the refrigerant to condense and release heat. The user-side heat exchanger includes a refrigerant condensation channel and a user water channel. The user water channel is connected to the user-side water supply pipeline and the user-side water return pipeline, respectively. The user-side water supply pipeline is used to connect at least one of the underfloor heating manifold and radiators. The discharge port of the variable frequency compressor, the refrigerant condensation channel, the throttling device, the refrigerant evaporation channel, and the suction port of the variable frequency compressor are connected in sequence to form a refrigerant circulation loop of a compression heat pump. The built-in circulating water pump is used to drive the user-side heating circulating water to circulate between the user-side heat exchanger and at least one of the underfloor heating manifold and radiator. The controller is electrically connected to the variable frequency compressor, the throttling device, and the built-in circulating water pump, respectively. The controller is used to adjust the operating frequency of the variable frequency compressor, the opening degree of the throttling device, and the speed of the built-in circulating water pump in conjunction with the temperature parameters on the heat source side and the temperature parameters on the user side.

2. The low-temperature centralized heating heat source adaptive variable frequency water source heat pump unit according to claim 1, characterized in that: The water source heat pump unit also includes a heat source side inlet water temperature detection device, a heat source side outlet water temperature detection device, a user side actual water supply temperature detection device, and a user side return water temperature detection device. The heat source side temperature parameters include at least the heat source side outlet water temperature and the heat source side inlet and outlet water temperature difference, and include at least one of the heat source side inlet water temperature and the heat source side outlet water temperature change rate. The user-side temperature parameters include at least the user-side target water supply temperature and the user-side actual water supply temperature, and include at least one of the following: user-side return water temperature, user-side supply and return water temperature difference, and user-side actual water supply temperature change rate.

3. The low-temperature centralized heating heat source adaptive variable frequency water source heat pump unit according to claim 2, characterized in that: The controller generates heat source side heat extraction margin parameters based on the heat source side temperature parameters, and generates user side load demand parameters based on the user side temperature parameters. When the temperature difference between the inlet and outlet water on the heat source side is greater than the preset upper limit of the temperature difference between the inlet and outlet water on the heat source side, or when the outlet water temperature on the heat source side is lower than the preset lower limit of the outlet water temperature on the heat source side, the controller determines that the heat extraction margin parameter on the heat source side does not meet the preset heat extraction margin condition, and restricts the operation frequency of the variable frequency compressor from increasing or decreasing.

4. The low-temperature centralized heating heat source adaptive variable frequency water source heat pump unit according to claim 1, characterized in that: The heat source water channel has a heat source water inlet and a heat source water outlet. The heat source water inlet is used to connect with the central heating water inlet pipe, and the heat source water outlet is used to connect with the central heating water return pipe. The heat source water channel includes an inlet flow equalization chamber, an outlet flow convergence chamber, and multiple parallel heat source water heat exchange branches; The inlet flow equalization chamber is connected to the heat source water inlet, the outlet flow collection chamber is connected to the heat source water outlet, and multiple heat source water heat exchange branches are connected in parallel between the inlet flow equalization chamber and the outlet flow collection chamber; The refrigerant evaporation channel includes a refrigerant inlet manifold, a refrigerant outlet manifold, and multiple refrigerant evaporation branches corresponding to the heat exchange branches of the heat source water. The refrigerant inlet manifold is connected to the outlet of the throttling device, the refrigerant outlet manifold is connected to the suction port of the variable frequency compressor, and multiple refrigerant evaporation branches are connected in parallel between the refrigerant inlet manifold and the refrigerant outlet manifold. The refrigerant inlet manifold is used to distribute the refrigerant after it has been throttled by the throttling device to multiple refrigerant evaporation branches, and the refrigerant outlet manifold is used to collect the refrigerant flowing out of multiple refrigerant evaporation branches and transport the refrigerant to the suction port.

5. The low-temperature centralized heating heat source adaptive variable frequency water source heat pump unit according to claim 1, characterized in that: The user-side heat exchanger includes a main condensing heat exchange zone, a liquid equalization transition zone, and a subcooling heat exchange zone arranged sequentially along the refrigerant flow direction. The main condensing heat exchange zone is used to allow the refrigerant discharged from the variable frequency compressor to exchange heat with the heating circulating water on the user side. The liquid equalization transition zone is used to equalize the pressure and distribute the flow of liquid refrigerant entering the subcooled heat exchange zone. The subcooled heat exchange zone is located upstream of the throttling device and is used to allow the condensed liquid refrigerant to continue releasing heat back to the user side of the water. The user water channel is configured such that the user-side return water first passes through the subcooling heat exchange zone and then through the main condensing heat exchange zone, forming a segmented countercurrent heat exchange path in which the user-side water flow and the refrigerant flow direction are opposite.

6. The low-temperature centralized heating heat source adaptive variable frequency water source heat pump unit according to claim 1, characterized in that: The throttling device is an electronic expansion valve; The water source heat pump unit also includes an intake temperature detection device, an intake pressure detection device, an exhaust temperature detection device, an exhaust pressure detection device, and an inlet temperature detection device for the throttling device; The controller determines the suction superheat based on the suction temperature and suction pressure, determines the refrigerant subcooling based on the discharge pressure and the inlet temperature of the throttling device, and determines the discharge safety status based on the discharge temperature and discharge pressure. The controller adjusts the opening of the electronic expansion valve according to the intake superheat, the refrigerant subcooling, and the exhaust safety status.

7. The low-temperature centralized heating heat source adaptive variable frequency water source heat pump unit according to claim 3, characterized in that: The water source heat pump unit also includes a heat source side bypass pipeline and a heat source side bypass regulating valve; The heat exchanger on the heat source side has a heat source water inlet and a heat source water outlet. The heat source side bypass pipeline is connected between the heat source water inlet and the heat source water outlet. The heat source side bypass regulating valve is installed on the heat source side bypass pipeline and is electrically connected to the controller. When the heat extraction margin parameter on the heat source side does not meet the preset heat extraction margin condition, the controller increases the opening of the bypass regulating valve on the heat source side, so that some of the central heating water bypasses the heat exchanger on the heat source side and mixes with the water outlet at the heat source water outlet, thereby limiting the heat extraction of the central heating water by the heat exchanger on the heat source side.

8. The low-temperature centralized heating heat source adaptive variable frequency water source heat pump unit according to claim 2, characterized in that: The controller includes a heating terminal identification unit; The heating terminal identification unit identifies the current user-side heating terminal as a floor heating terminal, a radiator terminal, or a hybrid terminal of floor heating and radiators based on the actual water supply temperature on the user side, the return water temperature on the user side, the speed of the built-in circulating water pump, the temperature difference between the supply and return water on the user side, and the change rate of the actual water supply temperature on the user side. When a device is identified as a floor heating terminal, the controller executes the first heating control mode; When a radiator terminal is identified, the controller executes the second heating control mode; When the system is identified as a hybrid terminal for both underfloor heating and radiators, the controller executes the third heating control mode. In this heating control mode, the target water supply temperature range on the user side corresponding to the first heating control mode is lower than the target water supply temperature range on the user side corresponding to the second heating control mode. The third heating control mode adjusts the speed of the built-in circulating water pump according to the rate of change of the user side return water temperature and limits the rate of increase of the actual water supply temperature on the user side.

9. A heating control method for a low-temperature centralized heating heat source adaptive variable frequency water source heat pump unit, applied to the low-temperature centralized heating heat source adaptive variable frequency water source heat pump unit according to any one of claims 1 to 8, characterized in that, Includes the following steps: S1, acquire the temperature parameters on the heat source side and the temperature parameters on the user side. The temperature parameters on the heat source side include at least the outlet water temperature on the heat source side and the temperature difference between the inlet and outlet water on the heat source side, and include at least one of the inlet water temperature on the heat source side and the rate of change of the outlet water temperature on the heat source side. The temperature parameters on the user side include at least the target water supply temperature on the user side and the actual water supply temperature on the user side, and include at least one of the return water temperature on the user side, the temperature difference between the supply and return water on the user side, and the rate of change of the actual water supply temperature on the user side. The target water supply temperature range on the user side is determined according to the type of heating terminal on the user side, and the target water supply temperature on the user side is a set value within the target water supply temperature range on the user side. S2, determine the heat source side heat extraction margin parameter based on the heat source side temperature parameter, and determine the user side load demand parameter based on the user side temperature parameter; S3, based on the heat source side heat margin parameters and the user side load demand parameters, determine the target operating frequency of the variable frequency compressor, the target opening degree of the throttling device, and the target speed of the built-in circulating water pump; S4, control the operation of the variable frequency compressor according to the target operating frequency, control the operation of the throttling device according to the target opening degree, and control the operation of the built-in circulating water pump according to the target speed; S5 compares the actual water supply temperature on the user side with the target water supply temperature range on the user side during operation. When the actual water supply temperature on the user side is lower than the lower limit of the target water supply temperature range on the user side, and the heat source side heat extraction margin parameter meets the preset heat extraction margin condition, the operating frequency of the variable frequency compressor is increased. When the actual water supply temperature on the user side is lower than the lower limit of the target water supply temperature range on the user side, but the heat extraction margin parameter on the heat source side does not meet the preset heat extraction margin condition, the operating frequency of the variable frequency compressor is restricted from increasing, and the target operating frequency is restricted to the upper limit of the frequency corresponding to the current heat extraction margin parameter on the heat source side. When the actual water supply temperature on the user side enters the target water supply temperature range on the user side, the operating frequency of the variable frequency compressor is maintained or reduced, and the built-in circulating water pump is maintained at a preset heat preservation circulation speed. When the actual water supply temperature on the user side is higher than the upper limit of the target water supply temperature range on the user side, the operating frequency of the variable frequency compressor is reduced, and the built-in circulating water pump is maintained at the preset heat preservation circulation speed.

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