Refrigerant loop control method, controller and system of Tianshi water system

Abstract

The invention discloses a refrigerant loop control method, a controller and a system of a Tianshu water system, and the method comprises the steps: at the initial stage of starting the system from a shutdown state, opening electronic expansion valves of all branches in all refrigerant loops at a large opening degree at the starting moment, and maintaining the electronic expansion valves for a short balance time; according to the invention, a smooth channel for refrigerant circulation between all branches and the main loop is established, so that the refrigerant detained in the non-target branch can quickly flow back to the main loop, and the problems of insufficient effective circulating refrigerant amount of the refrigerant loop, unstable system starting and performance delay caused by the fact that the refrigerant is detained in the non-target branch are solved; according to the invention, quick balanced distribution of the refrigerant when the system is started is realized, the time for the system to reach peak performance is shortened, abnormal protection is prevented from being triggered, the reliability of the system is improved, and the user experience is improved.

Description

Technical Field

[0001] This application relates to the field of refrigerant circuit control technology for natural refrigerant-ground water systems, and in particular to a refrigerant circuit control method, controller and system for natural refrigerant-ground water systems. Background Technology

[0002] A refrigerant-based water-based system is an air-source heat pump system that can simultaneously provide air conditioning and domestic hot water. It typically includes an outdoor unit connected via refrigerant piping, multiple indoor units, and a water-side heat exchange module.

[0003] In practical applications, a sufficient amount of refrigerant needs to be charged into the system to ensure its various cooling or heating performance requirements. However, since the total refrigerant charge of the system is usually determined based on the maximum load condition, during system shutdown, the refrigerant will naturally settle and remain in all branch pipes and heat exchangers of the system under the influence of gravity, temperature, and other factors, resulting in a random and uneven distribution. This leads to insufficient effective refrigerant in the refrigerant circulation loop when the system starts up, a decrease in evaporator heat exchange, and the system's output capacity failing to reach the set target, resulting in poor user comfort. It may also cause the system's suction pressure to be too low or the discharge pressure to be too high during startup, triggering the system's high and low pressure protection or alarm shutdown, resulting in unstable operation and thus impairing the system's reliability and service life. Summary of the Invention

[0004] The purpose of this application is to overcome the defects of the prior art and provide a refrigerant loop control method, controller and system for a refrigerant-based water system. This system can achieve rapid and balanced distribution of refrigerant during system startup, shorten the time for the system to reach peak performance, avoid triggering abnormal protection, improve system reliability and enhance user experience.

[0005] A first aspect of this application provides a refrigerant circuit control method for a natural gas-fired water system, characterized in that the refrigerant circuit of the natural gas-fired water system includes a main refrigerant circuit, a plate heat exchanger branch circuit, several indoor unit branches, a main circuit electronic expansion valve, a plate heat exchanger electronic expansion valve, and an indoor unit electronic expansion valve; the plate heat exchanger branch circuit and the several indoor unit branches are connected to the main refrigerant circuit; wherein the main circuit electronic expansion valve is disposed on the main refrigerant circuit, the plate heat exchanger expansion valve is disposed on the plate heat exchanger branch circuit, and the indoor unit expansion valve is disposed on the indoor unit branch circuit; The method includes: In the shutdown state, the first target operating mode of the fluorinated water system is obtained, and the target branch that needs to be activated in the first target operating mode is determined; wherein, the operating mode includes at least one of hot water mode, hot air mode and cold air mode; The main road electronic expansion valve is opened at a preset opening degree corresponding to the first target operating mode, the electronic expansion valve corresponding to the target branch is opened at a first preset opening degree, and the electronic expansion valve corresponding to the non-target branch is opened at a second preset opening degree, and the operation continues for a first set time; wherein, the first preset opening degree is the opening degree of the electronic expansion valve corresponding to the target branch in the target operating mode; the second preset opening degree is less than the first preset opening degree; After running for the first set time, the opening of the electronic expansion valve corresponding to the non-target branch is adjusted by a third preset opening degree; wherein, the third preset opening degree is less than or equal to the second preset opening degree; An opening control strategy corresponding to the first target operating mode is executed on the main electronic expansion valve and the electronic expansion valve corresponding to the target branch.

[0006] Compared to existing technologies, this application establishes a smooth refrigerant flow channel between all branches and the main circuit by opening the electronic expansion valves of all branches in the refrigerant circuit to a large opening at the moment of startup and maintaining a short period of equilibrium during the initial startup of the system from a shutdown state. This allows refrigerant that is stuck in non-target branches to quickly flow back to the main circulation, solving the problems of insufficient effective circulating refrigerant in the refrigerant circuit, unstable system startup, and performance delay caused by refrigerant stuck in non-target branches. It achieves rapid refrigerant balance distribution during system startup, shortens the time for the system to reach peak performance, avoids triggering abnormal protection, improves system reliability, and enhances the user experience.

[0007] In one embodiment, the refrigerant circuit of the hot-air refrigerant system includes at least two indoor unit branches; When the target operating mode is the hot water mode, the target branch is the plate heat exchanger branch, and the non-target branch is all the indoor unit branches; When the target operating mode is the hot air mode or the cold air mode, the target branch is the indoor unit branch where the indoor unit that needs to be started is located, and the non-target branch is the plate heat exchanger branch and the indoor unit branch where the indoor unit that does not need to be started is located. When the target operating mode is simultaneous hot water mode and hot air mode, the target branch is the plate heat exchanger branch and the indoor unit branch where the indoor unit that needs to be started is located, and the non-target branch is the indoor unit branch where the indoor unit that does not need to be started is located.

[0008] In one embodiment, the refrigerant circuit main circuit of the fluorinated water system includes a compressor, the plate heat exchanger branch circuit further includes a plate heat exchanger, and the indoor unit branch circuit further includes an indoor unit heat exchanger; the execution of an opening control strategy corresponding to the first target operating mode on the main circuit electronic expansion valve and the electronic expansion valve corresponding to the target branch circuit includes: When the target operating mode is at least one of hot water mode and hot air mode, the main circuit electronic expansion valve performs PID control based on the return gas temperature and / or return gas superheat of the compressor, and controls the opening of the electronic expansion valve of the target branch to the maximum value. When the target operating mode is the cooling mode, the opening of the main circuit electronic expansion valve is controlled to its maximum value. The electronic expansion valve of the indoor unit branch where the indoor unit to be started is located is controlled by PID according to the return air temperature and / or return air superheat of the indoor unit heat exchanger.

[0009] In one embodiment, during the operation of the fluoride-water system in its current operating mode, a second target operating mode is obtained; wherein, the second target operating mode includes a hot water mode, a hot air mode, or a combination of both. The main road electronic expansion valve is opened at the preset opening degree corresponding to the second target operating mode; If the current operating mode is hot water mode and the second target operating mode is hot air mode, the plate heat exchanger electronic expansion valve is adjusted to the fourth preset opening, and the indoor unit electronic expansion valve of the indoor unit branch where the indoor unit to be started is located is adjusted to the first preset opening; if the second target operating mode is hot water mode and hot air mode simultaneously, the indoor unit electronic expansion valve of the indoor unit branch where the indoor unit to be started is located is adjusted to the first preset opening; the refrigerant-water system operates at the adjusted opening for a second set time; wherein, the fourth preset opening is less than the first preset opening and greater than the third preset opening; If the current operating mode is hot air mode and the second target operating mode is hot water mode, the plate heat exchanger electronic expansion valve is adjusted to the first preset opening, and the electronic expansion valves of all indoor unit branches are adjusted to the fourth preset opening; if the second target operating mode is hot water mode and hot air mode simultaneously, the plate heat exchanger electronic expansion valve is adjusted to the first preset opening; the refrigerant-water system operates at the adjusted opening for a second set time; If the current operating mode is both hot water mode and hot air mode, and the second target operating mode is hot water mode, adjust the electronic expansion valves of all indoor unit branches to the fourth preset opening; if the second target operating mode is hot air mode, adjust the electronic expansion valves of the heat exchanger to the fourth preset opening; the refrigerant-water system operates at the adjusted opening for a second set time. The opening degree of the electronic expansion valve corresponding to the non-target branch is adjusted by the third preset opening degree; An opening control strategy corresponding to the second target operating mode is executed on the main electronic expansion valve and the electronic expansion valve corresponding to the target branch.

[0010] Based on the technical solution of this embodiment, when the operating mode of the air-fluorine ground-water system is switched, the refrigerant has enough time to be redistributed in an orderly manner between different branches, eliminating the sudden changes in flow and pressure caused by the switching of operating modes, and ensuring a smooth and shock-free transition from one steady-state operation to another.

[0011] In one embodiment, the second target operating mode further includes a cooling mode; If the current operating mode is hot water mode, hot air mode, or both hot water mode and hot air mode, and the second target operating mode is cold air mode, the fluorine-water system will be shut down and then restarted. If the current operating mode is cold air mode, and the second target operating mode is hot water mode, hot air mode, or both hot water mode and hot air mode, the Tianfudi water system will be shut down and then restarted.

[0012] The technical solution based on this embodiment can fundamentally eliminate hardware damage and system crashes that may be caused by direct switching between hot and cold modes, thus ensuring the operational safety and service life of the system.

[0013] In one embodiment, the fluorine-water system further includes an outdoor heat exchanger and a compressor, and the operating mode further includes a defrosting mode; During the operation of the fluorinated water system, the operating parameters of the current operating mode of the fluorinated water system are monitored; the operating parameters include the refrigerant evaporation temperature of the outdoor heat exchanger, the operating time of the compressor, and the evaporation pressure of the refrigerant; When the refrigerant evaporation temperature, the compressor operating time, and the refrigerant evaporation pressure simultaneously meet the preset conditions of the defrost mode, the refrigerant-water system enters the defrost mode; wherein, the preset conditions for meeting the defrost mode include the refrigerant evaporation temperature of the outdoor heat exchanger meeting the preset defrost temperature, the compressor operating time meeting the preset defrost operating time, and the refrigerant evaporation pressure meeting the preset defrost pressure.

[0014] In one embodiment, when the evaporation temperature of the refrigerant and the operating time of the compressor meet the preset conditions of the defrosting mode, but the evaporation pressure of the refrigerant does not meet the preset conditions of the defrosting mode, the preset opening adjustment amount is increased based on the current opening of the main electronic expansion valve. The electronic expansion valve of the non-target branch is adjusted to a fifth preset opening degree and continuously operated for a third preset time; wherein the fifth preset opening degree is less than the first preset opening degree and greater than the third preset opening degree; After the third set time has elapsed, the opening of the main electronic expansion valve is reduced by the preset opening adjustment amount, and the opening of the electronic expansion valve of the non-target branch is adjusted to the third preset opening. The fluoride-free water system continues to operate in the current operating mode.

[0015] Based on the technical solution of this embodiment, it is possible to accurately identify and automatically repair false defrosting caused by insufficient refrigerant, avoid the interruption of heating due to ineffective defrosting of the hot-air refrigerant and water-cooled system, significantly improve the stability of system operation, and enhance the user experience.

[0016] In one embodiment, when the target operating mode is the cooling mode, the second preset opening degree and the third preset opening degree are equal and are 0 PLS.

[0017] A second aspect of this application provides a controller, characterized in that it includes a processor and a memory; the memory stores instructions executable by the processor, the instructions being executed by the processor to enable the processor to perform any of the above-described refrigerant loop control methods for a refrigerant-water system.

[0018] A third aspect of this application provides a refrigerant-based water system, characterized in that the refrigerant-based water system includes a refrigerant circuit and a controller as described in claim 9; the refrigerant circuit includes a main refrigerant circuit, a plate heat exchanger branch circuit, a plurality of indoor unit branches, a main circuit electronic expansion valve, a plate heat exchanger electronic expansion valve, and an indoor unit electronic expansion valve, wherein the plate heat exchanger branch circuit and the plurality of indoor unit branches are connected to the main refrigerant circuit; wherein the main circuit electronic expansion valve is disposed on the main refrigerant circuit, the plate heat exchanger expansion valve is disposed on the plate heat exchanger branch circuit, and the indoor unit expansion valve is disposed on the indoor unit branch circuit.

[0019] Compared to existing technologies, this application establishes a smooth refrigerant flow channel between all branches and the main circuit by opening the electronic expansion valves of all branches in the refrigerant circuit to a large opening at the moment of startup and maintaining a short period of equilibrium during the initial startup of the system from a shutdown state. This allows refrigerant that is stuck in non-target branches to quickly flow back to the main circulation, solving the problems of insufficient effective circulating refrigerant in the refrigerant circuit, unstable system startup, and performance delay caused by refrigerant stuck in non-target branches. It achieves rapid refrigerant balance distribution during system startup, shortens the time for the system to reach peak performance, avoids triggering abnormal protection, improves system reliability, and enhances the user experience.

[0020] To better understand and implement this application, the following detailed description is provided in conjunction with the accompanying drawings. Attached Figure Description

[0021] Figure 1 A schematic diagram of the refrigerant circuit structure of the refrigerant-water system provided in this application embodiment, including four indoor unit branches; Figure 2 A detailed flowchart of the refrigerant loop control method for the fluorine-water system provided in this application embodiment; Figure 3 A detailed flowchart of the refrigerant circuit control method for the fluorinated water system provided in this application embodiment before it is operated in the second target operating mode; Figure 4 The following is a flowchart illustrating a refrigerant circuit control method provided in this application embodiment when the refrigerant evaporation temperature and compressor operating time meet the preset conditions of the defrost mode, but the refrigerant evaporation pressure does not meet the preset conditions of the defrost mode. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of the embodiments of this application.

[0023] In the following description, when referring to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. In the description of this application, it should be understood that the terms "first," "second," "third," etc., are used only to distinguish similar objects and are not necessarily used to describe a specific order or sequence, nor should they be construed as indicating or implying relative importance. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances. The singular forms "a," "the," and "the" used in this application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. The word "if" as used herein can be interpreted as "when," "when," or "in response to determination."

[0024] Furthermore, in the description of this application, unless otherwise stated, "multiple" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. Additionally, "fluoride-free water system" or "system" in the embodiments described in this application refer to the fluoride-free water system.

[0025] In a refrigerant-based water-cooled system, the refrigerant acts as a heat carrier, circulating directionally within a closed system. Through evaporation and heat absorption or condensation and heat release in different components, heat is transferred directionally from a low-temperature heat source to a high-temperature heat source, meeting various cooling or heating needs. The system utilizes plate heat exchangers on the water-side module to transfer heat from the refrigerant into the water, providing hot water to users. This hot water can then power indoor water-based heating systems such as underfloor heating or radiators. Furthermore, the refrigerant's evaporation and heat absorption or condensation and heat release in the indoor unit's heat exchanger allows the indoor unit (e.g., an air conditioner) to blow cold or hot air.

[0026] Please see Figure 1 , Figure 1The diagram illustrates the refrigerant circuit structure of the refrigerant-based water system provided in this embodiment, which includes four indoor unit branches. The refrigerant circuit of the refrigerant-based water system provided in this embodiment includes a main refrigerant circuit, a plate heat exchanger branch, four indoor unit branches, a main circuit electronic expansion valve 100, a plate heat exchanger electronic expansion valve 200, and indoor unit electronic expansion valves 300, 400, 500, and 600. The plate heat exchanger branch and several indoor unit branches are connected to the main refrigerant circuit. Specifically, the main circuit electronic expansion valve 100 is located on the main refrigerant circuit, the plate heat exchanger expansion valve 200 is located on the plate heat exchanger branch, and the indoor unit expansion valves 300, 400, 500, and 600 are located on the indoor unit branches.

[0027] The refrigerant's circulation in the closed pipeline is powered by the system's compressor. The compressor draws in low-pressure, low-temperature refrigerant vapor at its suction port, performs work on it, and outputs high-temperature, high-pressure superheated refrigerant vapor at its discharge port. Thus, during stable compressor operation, a stable pressure difference is generated between its discharge and suction ports, and this pressure difference is the fundamental driving force for the refrigerant flow throughout the entire cycle.

[0028] The path through which refrigerant circulates in a closed system is called the refrigerant circuit. The main refrigerant circuit refers to the common flow path from the compressor discharge port to each branch distribution point, and from the branch junction point to the compressor suction port. The plate heat exchanger branch refers to the refrigerant branch that originates from each branch distribution point on the main circuit, passes through the plate heat exchanger and the plate heat exchanger electronic expansion valve 200, and then merges back into the main circuit at the branch junction point. The indoor unit branch refers to the refrigerant branch that originates from each branch distribution point on the main circuit, passes through the indoor unit heat exchanger and the indoor unit electronic expansion valves 300, 400, 500, and 600, and then merges back into the main circuit at the branch junction point.

[0029] By controlling the opening of the electronic expansion valve, the refrigerant can be precisely distributed, thus achieving accurate heat delivery.

[0030] The refrigerant-based water system provided in this application realizes the distribution and regulation of refrigerant flow and heat at multiple system terminals through the connection between the main refrigerant circuit and each branch circuit and the control of the electronic expansion valves on the main circuit and branches circuit.

[0031] Please see Figure 2 , Figure 2 A detailed flowchart of the refrigerant loop control method for a naturally fluorinated water system provided in this application embodiment. The refrigerant loop control method for a naturally fluorinated water system provided in this application embodiment is characterized by comprising: S1: In the shutdown state, obtain the first target operating mode of the fluorine-water system and determine the target branch that needs to be started in the first target operating mode; wherein, the operating mode includes at least one of hot water mode, hot air mode and cold air mode.

[0032] When the air-to-water refrigerant system is shut down, the refrigerant will gradually deposit in the lower-temperature parts of the system due to gravity, such as the underground water-side modules or some pipes, while the indoor units located higher up will lack sufficient refrigerant.

[0033] The target operating mode refers to the operating mode of the fluoride-free water system selected by the user based on their needs. The first target operating mode refers to the operating mode in which the fluoride-free water system is started by the user from its self-shutdown state.

[0034] In one embodiment, the refrigerant circuit of the fluorine-water system includes at least two indoor unit branches.

[0035] In a preferred embodiment, the refrigerant circuit of the fluorine-water system includes four indoor unit branches.

[0036] When the target operating mode is hot water mode, the target branch is the plate heat exchanger branch, and the non-target branch is all indoor unit branches.

[0037] The hot water mode of the Tianfu Dishui system obtains hot water through a plate heat exchanger. The plate heat exchanger branch is the target branch, and the refrigerant is preferentially and centrally directed to this branch. Since all indoor units do not need to operate in this mode, all indoor unit branches are non-target branches.

[0038] When the target operating mode is hot air mode or cold air mode, the target branch is the indoor unit branch where the indoor unit that needs to be started is located, and the non-target branches are the plate heat exchanger branch and the indoor unit branch where the indoor unit that does not need to be started is located.

[0039] The hot air mode and cold air mode of the Tianfudi water system obtain hot air or cold air through the indoor unit heat exchanger. At this time, the branch containing at least one specific indoor unit that the user requests to start is designated as the target branch, and the plate heat exchanger and other indoor units that are not working are designated as non-target branches.

[0040] When the target operating mode is both hot water mode and hot air mode, the target branch is the plate heat exchanger branch and the indoor unit branch where the indoor unit that needs to be started is located, and the non-target branch is the indoor unit branch where the indoor unit that does not need to be started is located.

[0041] When the Tianfudi water system operates in both hot water and hot air modes simultaneously, the branch containing the plate heat exchanger and at least one specific indoor unit that the user requires to be activated is the target branch, while other indoor units that do not need to be activated are non-target branches.

[0042] S2: Open the main road electronic expansion valve with the main road preset opening degree corresponding to the first target operation mode, open the electronic expansion valve corresponding to the target branch with the first preset opening degree, open the electronic expansion valve corresponding to the non-target branch with the second preset opening degree, and continue to run for a first set time; wherein, the first preset opening degree is the opening degree of the electronic expansion valve corresponding to the target branch in the target operation mode; the second preset opening degree is less than the first preset opening degree.

[0043] During the factory design phase of the Tianfendi Water System, the system is tested in hot water mode, hot air / cold air mode, and a composite mode that combines hot water and hot air modes. Based on a large amount of experimental data, the pressure difference required for the system to quickly establish the refrigerant circulation that matches the corresponding operating mode can be obtained. Furthermore, the opening degree of the main circuit electronic expansion valve that matches the effective refrigerant charge required for the refrigerant circulation in the corresponding operating mode can be adjusted, and this opening degree is used as the preset opening degree of the main circuit for the corresponding operating mode.

[0044] Similarly, when the system is tested in hot water mode, hot air / cold air mode, and a composite mode in which hot water mode and hot air mode are run simultaneously, the amount of refrigerant required to achieve the best energy efficiency or the fastest temperature response is tested for each plate heat exchanger branch and each indoor unit branch in each operating mode. The opening degree of the electronic expansion valve corresponding to the obtained refrigerant amount is calibrated as the first preset opening degree of the branch in the corresponding operating mode.

[0045] The second preset opening degree was also obtained through experimental calibration. It is used to establish a temporary, larger flow channel for non-target branches in the early stage of system startup, so as to achieve rapid refrigerant recovery and system pressure balance.

[0046] The second preset opening degree is smaller than the first preset opening degree. The electronic expansion valve corresponding to the non-target branch is opened at the second preset opening degree, establishing a flow resistance difference for the refrigerant between the target and non-target branches. At this time, the target branch, due to the large opening degree of the electronic expansion valve and low resistance, becomes the main flow path for the refrigerant. After the compressor establishes the system pressure difference, the refrigerant retained in the non-target branch is extracted from the small-opening valve port, achieving refrigerant recovery and avoiding insufficient refrigerant circulation caused by refrigerant remaining in non-operating components.

[0047] S3: After running for a first set time, adjust the opening of the electronic expansion valve corresponding to the non-target branch by a third preset opening degree; wherein the third preset opening degree is less than or equal to the second preset opening degree.

[0048] The first set time, obtained through experimental testing, is used to allow sufficient time for the liquid refrigerant remaining in the non-target branch to flow back to the main circulation under the pressure difference established in the system, thereby eliminating the shortage of effective refrigerant circulation caused by uneven initial refrigerant distribution.

[0049] The third preset opening degree was obtained through experimental testing. It allows the refrigerant to flow continuously through the non-target branch at an extremely low flow rate, preventing the refrigerant from condensing and stagnating again due to complete stagnation in the non-target branch. It also ensures that the pressure in the non-target branch is basically the same as that in the main refrigerant circuit, so that the branch can be activated when the system needs to switch modes, thus achieving a rapid response to the switching of operating modes.

[0050] In one embodiment, when the target operating mode of the fluoride-water system is the cold air mode, the second preset opening degree and the third preset opening degree are equal and 0 PLS.

[0051] In cooling mode, the system operates on a standard refrigeration cycle. At this time, the indoor unit heat exchanger acts as an evaporator to absorb indoor heat, and the system no longer needs to start the plate heat exchanger. In order to prevent the high-temperature and high-pressure refrigerant in the main refrigerant circuit from being ineffectively and uncontrollably diverted to the plate heat exchanger branch and remaining in the plate heat exchanger as liquid refrigerant, and to prevent this liquid refrigerant from flowing back to the compressor directly or indirectly and causing liquid slugging in the compressor, the electronic expansion valve at its inlet must be completely closed (0 PLS) to ensure that all refrigerant flows to the outdoor unit according to the design path and achieves the highest cooling efficiency.

[0052] S4: Execute the opening control strategy corresponding to the first target operating mode on the main electronic expansion valve and the electronic expansion valve corresponding to the target branch.

[0053] In one embodiment, the refrigerant circuit main circuit of the refrigerant-cooled ground-water system includes a compressor, the plate heat exchanger branch circuit also includes a plate heat exchanger, and the indoor unit branch circuit also includes an indoor unit heat exchanger; the opening degree control strategy corresponding to the first target operating mode is executed on the main circuit electronic expansion valve and the electronic expansion valve corresponding to the target branch circuit, including: When the target operating mode is at least one of hot water mode and hot air mode, the main circuit electronic expansion valve is controlled by PID based on the compressor return gas temperature and / or return gas superheat, and the opening degree of the electronic expansion valve of the target branch is controlled to the maximum value.

[0054] The main circuit electronic expansion valve performs PID control based on the compressor's return gas temperature and / or return gas superheat, which can maintain the stability of the system's evaporation pressure and superheat, ensure that the compressor's return gas condition is appropriate, and avoid liquid slugging or overheating operation.

[0055] The electronic expansion valve corresponding to the target branch (such as the plate heat exchanger electronic expansion valve in hot water mode, or the electronic expansion valve of the indoor unit branch corresponding to the indoor unit that needs to be started in hot air mode) is controlled to have its opening at the maximum value, which can minimize the flow resistance of the branch and ensure that the refrigerant can flow fully through the corresponding heat exchanger.

[0056] When the target operating mode is cooling mode, the opening of the main circuit electronic expansion valve is at its maximum value. The electronic expansion valve of the indoor unit branch where the indoor unit to be started is located is controlled by PID based on the return air temperature and / or return air superheat of the indoor unit heat exchanger.

[0057] The main circuit electronic expansion valve controls its opening to the maximum value, which can minimize the throttling resistance of the main circuit and ensure that the refrigerant can flow smoothly to each indoor unit branch.

[0058] The opening degree of the electronic expansion valve of the indoor unit branch where the indoor unit to be started is located is controlled by a PID algorithm based on the return air temperature and / or return air superheat of the corresponding indoor unit heat exchanger, so as to maintain the evaporation pressure and superheat of the indoor unit within a suitable range and ensure the stability and energy efficiency of the output cold air.

[0059] Compared to existing technologies, this application establishes a smooth refrigerant flow channel between all branches and the main circuit by opening the electronic expansion valves of all branches in the refrigerant circuit to a large opening at the moment of startup and maintaining a short period of equilibrium during the initial startup of the system from a shutdown state. This allows refrigerant that is stuck in non-target branches to quickly flow back to the main circulation, solving the problems of insufficient effective circulating refrigerant in the refrigerant circuit, unstable system startup, and performance delay caused by refrigerant stuck in non-target branches. It achieves rapid refrigerant balance distribution during system startup, shortens the time for the system to reach peak performance, avoids triggering abnormal protection, improves system reliability, and enhances the user experience.

[0060] In one embodiment, see Figure 3 , Figure 3 A detailed flowchart of the refrigerant loop control method for the refrigerant-water system provided in this application embodiment before it operates in the second target operating mode.

[0061] The second target operating mode refers to the target operating mode that the fluoride-water system will switch to when it is already in a certain operating mode and is about to switch to based on a new user operation command.

[0062] S41: During the operation of the fluoride-water system in the current operating mode, obtain the second target operating mode; wherein, the second target operating mode includes hot water mode, hot air mode, or hot water mode and hot air mode simultaneously.

[0063] S42: Open the main road electronic expansion valve at the main road preset opening degree corresponding to the second target operation mode.

[0064] S43: If the current operating mode is hot water mode and the second target operating mode is hot air mode, adjust the plate heat exchanger electronic expansion valve to the fourth preset opening degree, and adjust the indoor unit electronic expansion valve of the indoor unit branch where the indoor unit to be started is located to the first preset opening degree; if the second target operating mode is hot water mode and hot air mode simultaneously, adjust the indoor unit electronic expansion valve of the indoor unit branch where the indoor unit to be started is located to the first preset opening degree; the refrigerant-water system runs at the adjusted opening degree for the second set time; wherein, the fourth preset opening degree is less than the first preset opening degree and greater than the third preset opening degree.

[0065] If the current operating mode is hot air mode and the second target operating mode is hot water mode, adjust the plate heat exchanger electronic expansion valve to the first preset opening degree and adjust the indoor unit electronic expansion valves of all indoor unit branches to the fourth preset opening degree; if the second target operating mode is hot water mode and hot air mode running simultaneously, adjust the plate heat exchanger electronic expansion valve to the first preset opening degree; the refrigerant-water system runs at the adjusted opening degree for the second set time.

[0066] If the current operating mode is both hot water mode and hot air mode, and the second target operating mode is hot water mode, adjust the electronic expansion valves of all indoor unit branches to the fourth preset opening degree; if the second target operating mode is hot air mode, adjust the electronic expansion valves of the heat exchanger to the fourth preset opening degree; the refrigerant-water system will run at the adjusted opening degree for the second set time.

[0067] The fourth preset opening degree was determined through dynamic mode switching experiments on the refrigerant-water system. In the simulated dynamic mode switching experiment, by monitoring key system parameters (such as compressor discharge pressure fluctuation amplitude, low-pressure change rate, and time to reach a new steady state), the intermediate opening degree value that minimizes fluctuations in these parameters and ensures the smoothest mode switching process was selected and calibrated as the fourth preset opening degree. Typically, the fourth preset opening degree can be set to 30% to 60% of the first preset opening degree to allow for refrigerant redistribution through flow resistance differences; the specific value depends on the system capacity and piping design.

[0068] For branches that need to be closed due to switching operating modes, the opening degree of the electronic expansion valve of the corresponding branch is adjusted to the fourth preset opening degree, which provides a buffer stage for pressure changes. This can avoid sudden changes in system pressure caused by the drastic change in valve closure when the system switches operating modes, thus protecting the compressor and pipeline components.

[0069] The second set time, obtained through experimental testing, allows the refrigerant sufficient time for orderly redistribution between different branches, eliminating sudden changes in flow and pressure caused by switching operating modes, and ensuring a smooth, shock-free transition from one steady-state operation to another.

[0070] S44: Adjust the opening degree of the electronic expansion valve corresponding to the non-target branch at the third preset opening degree.

[0071] S45: Execute the opening control strategy corresponding to the second target operating mode for the main electronic expansion valve and the electronic expansion valve corresponding to the target branch.

[0072] Based on the technical solution of this embodiment, when the operating mode of the air-fluorine ground-water system is switched, the refrigerant has enough time to be redistributed in an orderly manner between different branches, eliminating the sudden changes in flow and pressure caused by the switching of operating modes, and ensuring a smooth and shock-free transition from one steady-state operation to another.

[0073] In one embodiment, the second target operating mode also includes a cooling mode.

[0074] If the current operating mode is hot water mode, hot air mode, or both hot water mode and hot air mode, and the second target operating mode is cold air mode, the Tianfudi water system will be shut down and then restarted.

[0075] If the current operating mode is cold air mode, and the second target operating mode is hot water mode, hot air mode, or both hot water mode and hot air mode, the Tianfudi water system will be shut down and then restarted.

[0076] When the system is currently running any heating-related mode and the user requests to switch to cooling mode, the Tianfudi water system will completely shut down. After the pressure inside the system is fully balanced, it will be restarted following the steps required for the system to run in cooling mode while in shutdown mode.

[0077] Conversely, when the system is currently running in cooling mode and needs to be switched to any heating-related mode, it is also necessary to first perform a shutdown operation, and then restart the system according to the steps required for the system to run in heating-related mode while in shutdown state.

[0078] The core difference between the cooling mode and heating-related modes (hot water mode, hot air mode, or both simultaneously) lies in the energization state of the four-way reversing valve. The refrigerant flows in completely opposite directions within the refrigerant circuit. Therefore, switching from heating-related mode to cooling mode, or vice versa, requires reversing the four-way valve. However, directly energizing the four-way valve during system operation—that is, when a high pressure differential exists—poses an extremely high risk of compressor liquid slugging.

[0079] Therefore, the system is first shut down during the switching process to equalize the internal pressure, providing a no-load or low-load switching environment for the four-way valve and ensuring its normal switching capability. The technical solution based on this embodiment fundamentally eliminates the hardware damage and system crashes that may be caused by direct switching between hot and cold modes, ensuring the system's operational safety and lifespan.

[0080] In one embodiment, the fluorine-water system also includes an outdoor heat exchanger and a compressor, and the operating mode also includes a defrosting mode.

[0081] During the operation of the fluorinated water system, monitor the operating parameters of the current operating mode of the fluorinated water system; the operating parameters include the refrigerant evaporation temperature of the outdoor heat exchanger, the compressor operating time, and the refrigerant evaporation pressure.

[0082] When the refrigerant-based water system is operating in heating mode, the outdoor heat exchanger, acting as an evaporator, exchanges heat with the outside air. Water vapor in the air condenses on the surface of the heat exchanger, greatly increasing the thermal resistance between the air and the refrigerant, resulting in a deterioration in heat exchange efficiency and a decrease in system performance. At this time, the evaporation pressure inside the evaporator and the corresponding refrigerant evaporation temperature decrease. The refrigerant evaporation temperature and evaporation pressure follow the saturation pressure-temperature curve and have a one-to-one correspondence.

[0083] Optionally, the refrigerant evaporation temperature can be monitored by a temperature sensor installed at the outlet of the outdoor heat exchanger as one of the conditions for determining whether frost has formed, and the refrigerant evaporation pressure inside the evaporator can be monitored by a pressure sensor as one of the conditions for determining whether frost has formed.

[0084] Since frosting is a cumulative process over time, monitoring the operating time of the system, i.e., whether the compressor's operating time meets the preset conditions, can prevent false defrosting caused by brief temperature sensor monitoring failures and ensure that the system has enough stable operating time to form an impactful frost layer.

[0085] When the refrigerant evaporation temperature, compressor running time, and refrigerant evaporation pressure simultaneously meet the preset conditions for defrosting mode, the Tianfei Dishui system enters defrosting mode. Among them, meeting the preset conditions for defrosting mode includes the outdoor heat exchanger's refrigerant evaporation temperature meeting the preset defrosting temperature, the compressor running time meeting the preset defrosting running time, and the refrigerant evaporation pressure meeting the preset defrosting pressure.

[0086] In one embodiment, see Figure 4 , Figure 4 The following is a flowchart illustrating a refrigerant circuit control method provided in this application embodiment when the refrigerant evaporation temperature and compressor operating time meet the preset conditions of the defrost mode, but the refrigerant evaporation pressure does not meet the preset conditions of the defrost mode.

[0087] When the amount of refrigerant participating in the heat exchange is sufficient, the refrigerant evaporation process continues. Near the evaporator outlet, the outlet contains saturated vapor or slightly superheated vapor that has just completed evaporation. At this point, both temperature and pressure represent the same saturated state, thus showing a strict correspondence. However, when the amount of refrigerant participating in the heat exchange is insufficient, the limited liquid refrigerant has already completely evaporated in the first half of the evaporator. Only gaseous refrigerant is continued to be heated in the remaining tube side. In this case, the value measured by the pressure sensor is still determined by the final evaporation point of the refrigerant, reflecting the saturation pressure. The temperature sensor measures the temperature of the superheated gas, which is necessarily higher than the saturation temperature corresponding to the measured saturation pressure. In this case, the measured evaporation temperature and evaporation pressure deviate from the saturation pressure-temperature curve, showing a non-corresponding relationship.

[0088] Optionally, the preset conditions for the defrost mode can be set to a preset defrost temperature of -3℃ to -6℃, a preset defrost running time of 5 hours, and a preset defrost pressure of the saturation pressure corresponding to -3℃ to -6℃. If the evaporation temperature drops to -5℃ and the system has run for 5 hours, but the evaporation pressure is still higher than the saturation pressure corresponding to -3℃, then it can be confirmed that the amount of refrigerant participating in heat exchange in the system is insufficient and the defrost mode will not be entered.

[0089] When the refrigerant evaporation temperature and compressor operating time meet the preset conditions for defrosting mode, but the refrigerant evaporation pressure does not meet the preset conditions for defrosting mode, the following steps are executed: S51: Based on the current opening degree of the main circuit electronic expansion valve, increase the preset opening degree adjustment amount.

[0090] By appropriately increasing the opening of the main circuit electronic expansion valve, the refrigerant charge in the entire refrigerant circuit is increased, thereby increasing the driving force of the refrigerant circulation. This helps to promote the return of stagnant refrigerant and restore the evaporation pressure.

[0091] S52: Adjust the electronic expansion valve of the non-target branch to the fifth preset opening degree and continue to run for a third preset time; wherein the fifth preset opening degree is less than the first preset opening degree and greater than the third preset opening degree.

[0092] Adjusting the opening of the electronic expansion valve corresponding to the non-target branch from the third preset opening to a larger fifth preset opening allows the refrigerant remaining in the non-target branch that is not in operation to flow back to the main refrigerant circuit to participate in circulation within a third set time, thereby increasing the amount of refrigerant evaporating in the evaporator.

[0093] The third set time is determined based on the refrigerant's evaporation pressure and evaporation temperature. The system operates for the third set time, which allows the refrigerant sufficient time to redistribute and respond to pressure. The monitoring shows that the refrigerant's evaporation pressure and evaporation temperature have recovered to meet the corresponding relationship of the saturation pressure-temperature curve.

[0094] S53: After the third set time, the opening of the main electronic expansion valve will be reduced by the preset opening adjustment amount, and the opening of the electronic expansion valve of the non-target branch will be adjusted to the third preset opening. The fluoride-free water system will continue to run in the current operating mode.

[0095] Because the refrigerant that was not on the target path flows back to the main refrigerant circuit for circulation, the amount of refrigerant evaporating in the evaporator is sufficient, and the evaporation pressure and evaporation temperature of the refrigerant recover to the corresponding relationship of the saturation pressure-temperature curve. At this time, the evaporation temperature and evaporation pressure do not meet the preset defrosting conditions, so the refrigerant-water system returns to normal operation and continues to operate in the current operating mode.

[0096] Based on the technical solution of this embodiment, it is possible to accurately identify and automatically repair false defrosting caused by insufficient refrigerant, avoid the interruption of heating due to ineffective defrosting of the hot-air refrigerant and water-cooled system, significantly improve the stability of system operation, and enhance the user experience.

[0097] A second aspect of this application provides a controller, characterized in that it includes a processor and a memory; the memory stores instructions that can be executed by the processor, and the instructions are executed by the processor to enable the processor to perform the steps of any of the above-described refrigerant loop control methods for a refrigerant-water system.

[0098] A third aspect of this application provides a refrigerant-based water system, characterized in that the system includes a refrigerant circuit and a controller as described in the second aspect; the refrigerant circuit includes a main refrigerant circuit, a plate heat exchanger branch circuit, several indoor unit branches, a main circuit electronic expansion valve, a plate heat exchanger electronic expansion valve, and an indoor unit electronic expansion valve, wherein the plate heat exchanger branch circuit and the several indoor unit branches are connected to the main refrigerant circuit; wherein the main circuit electronic expansion valve is disposed on the main refrigerant circuit, the plate heat exchanger expansion valve is disposed on the plate heat exchanger branch circuit, and the indoor unit expansion valve is disposed on the indoor unit branch circuit.

[0099] The specific examples described above further illustrate the purpose, technical solution, and beneficial effects of this application. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0100] The above-described embodiments are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications, equivalent substitutions, and improvements without departing from the concept of the present invention, all of which fall within the protection scope of the present invention.

Claims

1. A refrigerant loop control method for a natural-to-ground water refrigerant system, characterized in that, The refrigerant circuit of the refrigerant-water system includes a main refrigerant circuit, plate heat exchanger branches, several indoor unit branches, a main circuit electronic expansion valve, a plate heat exchanger electronic expansion valve, and an indoor unit electronic expansion valve. The plate heat exchanger branches and the several indoor unit branches are all connected to the main refrigerant circuit. The main circuit electronic expansion valve is located on the main refrigerant circuit, the plate heat exchanger expansion valve is located on the plate heat exchanger branch, and the indoor unit expansion valve is located on the indoor unit branch. The method includes: In the shutdown state, the first target operating mode of the fluorinated water system is obtained, and the target branch that needs to be activated in the first target operating mode is determined; wherein, the operating mode includes at least one of hot water mode, hot air mode and cold air mode; The main road electronic expansion valve is opened at a preset opening degree corresponding to the first target operating mode, the electronic expansion valve corresponding to the target branch is opened at a first preset opening degree, and the electronic expansion valve corresponding to the non-target branch is opened at a second preset opening degree, and the operation continues for a first set time; wherein, the first preset opening degree is the opening degree of the electronic expansion valve corresponding to the target branch in the first target operating mode; the second preset opening degree is less than the first preset opening degree; After running for the first set time, the opening of the electronic expansion valve corresponding to the non-target branch is adjusted by a third preset opening degree; wherein, the third preset opening degree is less than or equal to the second preset opening degree; An opening control strategy corresponding to the first target operating mode is executed on the main electronic expansion valve and the electronic expansion valve corresponding to the target branch.

2. The refrigerant loop control method for a natural gas-fired water system according to claim 1, characterized in that, The refrigerant circuit of the fluorine-water system includes at least two indoor unit branches; When the target operating mode is the hot water mode, the target branch is the plate heat exchanger branch, and the non-target branch is all the indoor unit branches; When the target operating mode is the hot air mode or the cold air mode, the target branch is the indoor unit branch where the indoor unit that needs to be started is located, and the non-target branch is the plate heat exchanger branch and the indoor unit branch where the indoor unit that does not need to be started is located. When the target operating mode is simultaneous hot water mode and hot air mode, the target branch is the plate heat exchanger branch and the indoor unit branch where the indoor unit that needs to be started is located, and the non-target branch is the indoor unit branch where the indoor unit that does not need to be started is located.

3. The refrigerant loop control method for a natural gas-fired water system according to claim 2, characterized in that, The refrigerant circuit main circuit of the fluorinated water system includes a compressor, the plate heat exchanger branch circuit also includes a plate heat exchanger, and the indoor unit branch circuit also includes an indoor unit heat exchanger; the execution of an opening control strategy corresponding to the first target operating mode on the main circuit electronic expansion valve and the electronic expansion valve corresponding to the target branch circuit includes: When the target operating mode is at least one of hot water mode and hot air mode, the main circuit electronic expansion valve performs PID control based on the return gas temperature and / or return gas superheat of the compressor, and controls the opening of the electronic expansion valve of the target branch to the maximum value. When the target operating mode is the cooling mode, the opening of the main circuit electronic expansion valve is controlled to its maximum value. The electronic expansion valve of the indoor unit branch where the indoor unit to be started is located is controlled by PID according to the return air temperature and / or return air superheat of the indoor unit heat exchanger.

4. The refrigerant loop control method for a natural gas-fired water system according to claim 2, characterized in that, During the operation of the fluoride-water system in its current operating mode, a second target operating mode is acquired; wherein, the second target operating mode includes hot water mode, hot air mode, or hot water mode and hot air mode operating simultaneously; The main road electronic expansion valve is opened at the preset opening degree corresponding to the second target operating mode; If the current operating mode is hot water mode and the second target operating mode is hot air mode, the plate heat exchanger electronic expansion valve is adjusted to the fourth preset opening, and the indoor unit electronic expansion valve of the indoor unit branch where the indoor unit to be started is located is adjusted to the first preset opening; if the second target operating mode is hot water mode and hot air mode simultaneously, the indoor unit electronic expansion valve of the indoor unit branch where the indoor unit to be started is located is adjusted to the first preset opening; the refrigerant-water system operates at the adjusted opening for a second set time; wherein, the fourth preset opening is less than the first preset opening and greater than the third preset opening; If the current operating mode is hot air mode and the second target operating mode is hot water mode, the plate heat exchanger electronic expansion valve is adjusted to the first preset opening, and the electronic expansion valves of all indoor unit branches are adjusted to the fourth preset opening; if the second target operating mode is hot water mode and hot air mode simultaneously, the plate heat exchanger electronic expansion valve is adjusted to the first preset opening; the refrigerant-water system operates at the adjusted opening for a second set time; If the current operating mode is both hot water mode and hot air mode, and the second target operating mode is hot water mode, adjust the electronic expansion valves of all indoor unit branches to the fourth preset opening; if the second target operating mode is hot air mode, adjust the electronic expansion valves of the heat exchanger to the fourth preset opening; the refrigerant-water system operates at the adjusted opening for a second set time. The opening degree of the electronic expansion valve corresponding to the non-target branch is adjusted by the third preset opening degree; An opening control strategy corresponding to the second target operating mode is executed on the main electronic expansion valve and the electronic expansion valve corresponding to the target branch.

5. The refrigerant loop control method for a natural gas-fired water system according to claim 4, characterized in that, The second target operating mode also includes a cooling mode; If the current operating mode is hot water mode, hot air mode, or both hot water mode and hot air mode, and the second target operating mode is cold air mode, the fluorine-water system will be shut down and then restarted. If the current operating mode is cold air mode, and the second target operating mode is hot water mode, hot air mode, or both hot water mode and hot air mode, the Tianfudi water system will be shut down and then restarted.

6. The refrigerant loop control method for a natural gas-fired water system according to claim 1, characterized in that, The fluorine-water system also includes an outdoor heat exchanger and a compressor, and the operating mode also includes a defrosting mode. During the operation of the fluorinated water system, the operating parameters of the current operating mode of the fluorinated water system are monitored; the operating parameters include the refrigerant evaporation temperature of the outdoor heat exchanger, the operating time of the compressor, and the evaporation pressure of the refrigerant; When the refrigerant evaporation temperature, the compressor operating time, and the refrigerant evaporation pressure simultaneously meet the preset conditions of the defrost mode, the refrigerant-water system enters the defrost mode; wherein, the preset conditions for meeting the defrost mode include the refrigerant evaporation temperature of the outdoor heat exchanger meeting the preset defrost temperature, the compressor operating time meeting the preset defrost operating time, and the refrigerant evaporation pressure meeting the preset defrost pressure.

7. The refrigerant loop control method for a natural gas-fired water system according to claim 6, characterized in that, When the evaporation temperature of the refrigerant and the running time of the compressor meet the preset conditions of the defrosting mode, but the evaporation pressure of the refrigerant does not meet the preset conditions of the defrosting mode, the preset opening adjustment amount is increased based on the current opening of the main electronic expansion valve. The electronic expansion valve of the non-target branch is adjusted to a fifth preset opening degree and continuously operated for a third preset time; wherein the fifth preset opening degree is less than the first preset opening degree and greater than the third preset opening degree; After the third set time has elapsed, the opening of the main electronic expansion valve is reduced by the preset opening adjustment amount, and the opening of the electronic expansion valve of the non-target branch is adjusted to the third preset opening. The fluoride-free water system continues to operate in the current operating mode.

8. A refrigerant loop control method for a natural gas-fired water system according to claim 1, characterized in that, When the target operating mode is the cold air mode, the second preset opening degree and the third preset opening degree are equal and 0 PLS.

9. A controller, characterized in that, It includes a processor and a memory; the memory stores instructions that can be executed by the processor, which, when executed by the processor, enables the processor to perform the refrigerant loop control method for a refrigerant-water system as described in any one of claims 1 to 8.

10. A fluoride-free groundwater system, characterized in that, The refrigerant-based water system includes a refrigerant circuit and a controller as described in claim 9; the refrigerant circuit includes a main refrigerant circuit, a plate heat exchanger branch circuit, several indoor unit branches, a main circuit electronic expansion valve, a plate heat exchanger electronic expansion valve, and an indoor unit electronic expansion valve, wherein the plate heat exchanger branch circuit and the several indoor unit branches are connected to the main refrigerant circuit; wherein the main circuit electronic expansion valve is located on the main refrigerant circuit, the plate heat exchanger expansion valve is located on the plate heat exchanger branch circuit, and the indoor unit expansion valve is located on the indoor unit branch circuit.

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