Two-pipe control system and method based on direct expansion type air conditioning unit

Abstract

The invention relates to a two-pipe control system and method based on a direct expansion type air conditioning unit, and relates to the field of direct expansion type air conditioning units. According to the technical scheme, the operation demand instruction of the direct expansion type air conditioning unit is received through the control unit; regulating and controlling the working state of each component of the environment side unit and the use side unit according to the operation demand instruction; and based on the regulation and control states of all parts of the environment side unit and the use side unit, the refrigerant is guided to flow in a two-pipe circulation loop formed by the environment side unit and the use side unit, and refrigeration circulation, heating circulation, dehumidification circulation or defrosting circulation corresponding to the operation demand instruction is executed, so that the corresponding air treatment function is achieved. Under the condition, the direct expansion type air conditioning unit can meet the requirement for normal-temperature dehumidification, system circulation can be achieved only through the two connecting pipes, and the direct expansion type air conditioning unit can efficiently operate in the dehumidification operation mode, dehumidifies without cooling and is good in economical efficiency.

Description

Technical Field

[0001] This invention relates to the field of direct expansion air conditioning unit technology, and in particular to a two-pipe control system and method based on direct expansion air conditioning units. Background Technology

[0002] With the increasing emphasis placed on environmental protection by the nation, the promotion of clean energy has become an industry consensus and development trend. Direct expansion air conditioning units, due to their direct refrigerant evaporation cooling and direct air treatment mode, eliminate the need for intermediate heat exchange media, effectively reducing energy losses during energy transfer and thus exhibiting higher heat exchange efficiency, demonstrating significant advantages in clean energy applications. However, under certain special operating conditions (such as requiring dehumidification of incoming air and maintaining a consistent or minimally different return air temperature to avoid air cooling), existing technologies still have significant shortcomings. Currently, the commonly used approach is to compensate for the temperature of the air cooled by the user-side heat exchanger using an electric auxiliary heating device along the airflow direction. This solution significantly increases the unit's operating energy consumption, leading to decreased system economy.

[0003] To replace electric auxiliary heating, the industry has proposed a hot-fluorine heating solution. The core of this solution is to add a reheat heat exchanger after the evaporator-side heat exchanger. The high-temperature, high-pressure gas discharged from the compressor is introduced into the reheat heat exchanger through connecting pipes, utilizing the refrigerant's own condensation heat to reheat the air. However, this solution requires the refrigerant, after condensation in the reheat heat exchanger, to be further introduced into the ambient environment. Currently, the mainstream implementation methods include three-pipe systems (the evaporator and condenser sides are connected by three pipes to form a complete fluorine system) and four-pipe systems (the evaporator and reheat heat exchanger are each equipped with independent inlet and outlet pipes). Both of these piping designs have significant drawbacks. The increased number of pipes not only increases the complexity of on-site construction and extends the installation period but also directly leads to higher material and system maintenance costs.

[0004] Therefore, developing a direct expansion air conditioning unit that can meet the dehumidification requirements at normal temperature and achieve system circulation only through two connecting pipes (connecting the environmental side and the user side) has become the key to solving current technical pain points and improving the cost-effectiveness of the system, and has important practical significance. Summary of the Invention

[0005] The purpose of this invention is to provide a two-pipe control system and method based on a direct expansion air conditioning unit to solve the problems existing in the prior art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a two-pipe control system based on a direct expansion air conditioning unit, the system comprising: The environmental side unit includes an interconnected compressor, a vapor-liquid separator, a four-way reversing valve, an environmental side heat exchanger, an environmental side condenser fan, a first throttling element, a first filter, and a first check valve; The use-side unit includes a three-way valve, a second throttling element, a second check valve, a third check valve, a second filter, a use-side heat exchanger, a reheat heat exchanger, and a use-side blower; and The control unit is electrically connected to each component of the environmental side unit and the user side unit respectively, so as to regulate the coordinated operation of each component; The environmental side unit and the user side unit are connected by an inlet pipe and a return pipe.

[0007] In some embodiments, the compressor's exhaust port is connected to the first port of the four-way reversing valve, the compressor's intake port is connected to the outlet of the vapor-liquid separator, and the vapor-liquid separator's inlet is connected to the second port of the four-way reversing valve. The third port of the four-way reversing valve is connected to the first port of the ambient heat exchanger, the fourth port of the four-way reversing valve is connected to one end of the return gas pipe, and the second port of the ambient heat exchanger is connected to one end of the first filter. The other end of the first filter is connected to one end of the first one-way valve and one end of the first throttling element, and the other end of the first one-way valve and the other end of the first throttling element are connected to one end of the inlet pipe.

[0008] In some embodiments, the other end of the inlet pipe is connected to port C of the three-way valve, port B of the three-way valve is connected to the first port of the reheat heat exchanger, and the second port of the reheat heat exchanger is connected to one end of the third check valve. The first port of the heat exchanger on the use side is connected to one end of the second filter, the second port of the heat exchanger on the use side is connected to the other end of the return gas pipe, and the other end of the second filter is connected to one end of the second one-way valve and one end of the second throttling element, respectively. The other end of the third check valve, the other end of the second check valve, and the other end of the second throttling element are all connected to port A of the three-way valve.

[0009] In some embodiments, the compressor is a variable frequency compressor; Both the ambient heat exchanger and the user heat exchanger are finned tube heat exchangers. Both the first throttling element and the second throttling element are electronic expansion valves; The environmental side condenser fan is a three-speed AC fan, a stepless speed-regulating EC fan, or a stepless speed-regulating DC fan. The side-blowing fan used is either a continuously variable EC fan or a continuously variable DC fan.

[0010] Secondly, the present invention provides a two-pipe control method based on a direct expansion air conditioning unit. The method is applied to the two-pipe control system based on the direct expansion air conditioning unit as described above. The method is executed and regulated by the control unit, and includes: Receives operation demand instructions from direct expansion air conditioning units, wherein the operation demand instructions include at least one of cooling instructions, heating instructions, dehumidification instructions, and defrosting instructions; According to the operational requirements, the working status of each component of the environmental side unit and the user side unit is adjusted. Based on the control status of each component of the environmental side unit and the user side unit, the refrigerant is guided to flow in the two-pipe circulation loop formed by the environmental side unit and the user side unit, and the refrigeration cycle, heating cycle, dehumidification cycle or defrosting cycle corresponding to the operation demand command are executed to achieve the corresponding air handling function.

[0011] In some embodiments, the execution of the refrigeration cycle includes: The four-way reversing valve is de-energized and remains in its initial state, the first throttling element is fully closed, the three-way valve is de-energized and remains in its initial reversing state, and the compressor, ambient side condenser fan and user side blower are started. The high-temperature, high-pressure gaseous refrigerant discharged from the compressor flows through the ambient heat exchanger and is condensed into high-pressure liquid refrigerant under the action of the ambient condenser fan. It then enters the user-side unit through the first filter, the first one-way valve, and the liquid inlet pipe. High-pressure liquid refrigerant flows in through port C and out through port A of the three-way valve. After being throttled and depressurized by the second throttling element, it flows through the second filter and the heat exchanger on the user side, where it absorbs heat from the air and becomes gaseous refrigerant. Finally, it flows back to the suction port of the compressor through the return pipe, the four-way reversing valve, and the vapor-liquid separator, completing the refrigeration cycle.

[0012] In some embodiments, the execution of the heating cycle includes: The four-way reversing valve is energized and reversed, the second throttling element is fully closed, the three-way valve is de-energized and maintains the initial reversing state, and the compressor, the ambient side condenser fan and the user side blower are started. The high-temperature and high-pressure gaseous refrigerant discharged from the compressor enters the user-side unit through the four-way reversing valve and the return gas pipe, flows through the user-side heat exchanger, and releases heat into high-pressure liquid refrigerant under the action of the user-side blower. After flowing in through the second filter, the second one-way valve and the A port and out through the C port of the three-way valve, it enters the environmental-side unit through the liquid inlet pipe. The high-pressure liquid refrigerant is throttled and depressurized by the first throttling element, and then flows through the ambient side heat exchanger. Under the action of the ambient side condenser fan, it absorbs heat and becomes gaseous refrigerant. It then flows back to the suction port of the compressor through the vapor-liquid separator, completing the heating cycle.

[0013] In some embodiments, the dehumidification cycle execution process includes: The four-way reversing valve is de-energized and remains in its initial state. The first throttling element is fully closed. The three-way valve is energized and reversed, starting the compressor, the ambient side condenser fan, and the user side blower. The high-temperature, high-pressure gaseous refrigerant discharged from the compressor flows through the ambient heat exchanger and is condensed into high-pressure liquid refrigerant under the action of the ambient condenser fan. It then enters the user-side unit through the first filter, the first one-way valve, and the liquid inlet pipe. High-pressure liquid refrigerant flows in through port C and out through port B of the three-way valve, then flows through the reheat heat exchanger to release heat, and then through the third one-way valve and the second throttling element to reduce pressure. It then flows through the second filter and the user-side heat exchanger to complete cooling and dehumidification. After becoming gaseous refrigerant, it flows back to the suction port of the compressor through the return pipe, the four-way reversing valve and the vapor-liquid separator to complete the dehumidification cycle.

[0014] In some implementations, the defrosting cycle includes the following steps: The four-way reversing valve is de-energized and remains in its initial state. The first throttling element is fully closed, the second throttling element is fully open, the three-way valve is de-energized and remains in its initial reversing state, the compressor is started and the side blower is used, and the environmental side condenser is turned off and shut down. The high-temperature, high-pressure gaseous refrigerant discharged from the compressor flows through the ambient heat exchanger, where it defrosts and releases heat, becoming a high-pressure liquid refrigerant. It then passes through the first filter, the first check valve, and the liquid inlet pipe before entering the user-side unit. High-pressure liquid refrigerant flows in through port C and out through port A of the three-way valve. After absorbing heat from the air via the second throttling element, the second filter, and the heat exchanger on the user side, it becomes gaseous refrigerant and flows back to the compressor's suction port via the return pipe, the four-way reversing valve, and the vapor-liquid separator, completing the defrosting cycle. After the defrosting cycle is completed, it automatically switches back to the heating cycle.

[0015] In some embodiments, the execution of the dehumidification cycle further includes a dynamic adjustment step based on temperature parameters of the environmental side unit and the user side unit: Real-time temperature T of the environmental side unit is collected. wj and the real-time temperature T of the side unit nj Preset environmental side unit determination temperature T w and use of side unit to determine temperature T n ; When T wj ≥T w And Tnj ≥T n At that time, the compressor is controlled to operate at the rated frequency, and the ambient side condenser fan and the user side supply fan operate at the preset wind speed; When T wj ≥T w And T nj <T n At the same time, the compressor is controlled to maintain the rated frequency, the ambient side condenser fan is reduced to the preset low speed, and the side supply fan is maintained at the preset speed. When T wj <T w And T nj ≥T n When the compressor is in operation, the compressor is reduced to the preset frequency, the ambient side condenser fan is reduced to the preset low speed, and the side fan is used to maintain the preset speed. When T wj <T w And T nj <T n When the compressor is in operation, the compressor frequency is reduced to the preset frequency, and both the ambient condenser fan and the user-side blower are reduced to the preset low speed.

[0016] The beneficial effects of the technical solution provided by this invention include at least the following: This technical solution receives operating demand commands from the direct expansion air conditioning unit via a control unit. These commands include at least one of cooling, heating, dehumidification, and defrosting commands. Based on these commands, the operating states of various components in the environmental and user-side units are regulated. Based on the regulated states of these components, the refrigerant is guided to flow in the two-pipe circulation loop formed by the environmental and user-side units, executing the corresponding cooling, heating, dehumidification, or defrosting cycle to achieve the corresponding air handling function. In this case, a direct expansion air conditioning unit is provided that can meet the dehumidification requirements at normal temperature while requiring only two connecting pipes for system circulation. It can operate efficiently in dehumidification mode without lowering the temperature, resulting in good economic performance. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0018] Figure 1 The diagram shows a schematic of a two-pipe control system based on a direct expansion air conditioning unit, provided by an exemplary embodiment of the present invention.

[0019] Figure 2The diagram shows a flow chart of a two-pipe control method based on a direct expansion air conditioning unit provided by an exemplary embodiment of the present invention.

[0020] Figure 3 A flow diagram of a refrigeration cycle provided by an exemplary embodiment of the present invention is shown.

[0021] Figure 4 A flow diagram of a heating cycle provided by an exemplary embodiment of the present invention is shown.

[0022] Figure 5 A flow diagram of a dehumidification cycle provided by an exemplary embodiment of the present invention is shown.

[0023] Figure 6 A flow diagram of the defrosting cycle provided by an exemplary embodiment of the present invention is shown.

[0024] In the diagram: 1. Compressor; 2. Vapor-liquid separator; 3. Four-way reversing valve; 4. Ambient side heat exchanger; 5. Ambient side condenser fan; 6. First throttling element; 7. First filter; 8. First check valve; 9. Three-way valve; 10. Second throttling element; 11. Second check valve; 12. Third check valve; 13. Second filter; 14. Use side heat exchanger; 15. Reheat heat exchanger; 16. Use side blower; 17. Control unit. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0027] Figure 1This diagram illustrates a two-pipe control system based on a direct expansion air conditioning unit according to an exemplary embodiment of the present invention. The two-pipe control system includes: an environmental side unit comprising a compressor 1, a vapor-liquid separator 2, a four-way reversing valve 3, an environmental side heat exchanger 4, an environmental side condenser fan 5, a first throttling element 6, a first filter 7, and a first one-way valve 8, all interconnected; a user side unit comprising a three-way valve 9, a second throttling element 10, a second one-way valve 11, a third one-way valve 12, a second filter 13, a user side heat exchanger 14, a reheat heat exchanger 15, and a user side supply fan 16; and a control unit 17 electrically connected to each component of both the environmental side unit and the user side unit to regulate the coordinated operation of the components; wherein the environmental side unit and the user side unit are connected via an inlet pipe and a return pipe.

[0028] In this embodiment, the compressor powers the refrigerant circulation, the vapor-liquid separator prevents liquid slugging in the compressor, and the four-way reversing valve switches between cooling and heating cycles. An ambient-side heat exchanger and an ambient-side condenser fan work together to complete ambient-side heat exchange. A first throttling element regulates the refrigerant flow, a first filter removes impurities, and a first check valve prevents refrigerant backflow. A three-way valve switches the refrigerant path to adapt to different operating modes, a second throttling element precisely controls the temperature, and a second and third check valves prevent backflow. A second filter removes impurities. A side heat exchanger is used for cooling and dehumidification, a reheat heat exchanger replenishes the temperature to meet ambient temperature dehumidification requirements, and a side fan accelerates air handling.

[0029] For details, please refer to Figure 1 The exhaust port of compressor 1 is connected to the first port of four-way reversing valve 3, the suction port of compressor 1 is connected to the outlet of vapor-liquid separator 2, and the inlet of vapor-liquid separator 2 is connected to the second port of four-way reversing valve 3. The third port of four-way reversing valve 3 is connected to the first port of ambient heat exchanger 4, the fourth port of four-way reversing valve is connected to one end of return pipe, and the second port of ambient heat exchanger 4 is connected to one end of first filter 7. The other end of first filter 7 is connected to one end of first check valve 8 and one end of first throttling element 6, and the other end of first check valve 8 and the other end of first throttling element 6 are connected to one end of inlet pipe.

[0030] For more details, please refer to Figure 1The other end of the inlet pipe is connected to port C of the three-way valve 9, port B of the three-way valve 9 is connected to the first port of the reheat heat exchanger 15, and the second port of the reheat heat exchanger 15 is connected to one end of the third check valve 12; the first port of the use-side heat exchanger 14 is connected to one end of the second filter 13, and the second port of the use-side heat exchanger 14 is connected to the other end of the return gas pipe; the other end of the second filter 13 is connected to one end of the second check valve 11 and one end of the second throttling element 10 respectively; the other end of the third check valve 12, the other end of the second check valve 11, and the other end of the second throttling element 10 are all connected to port A of the three-way valve 9.

[0031] In some embodiments, compressor 1 is a variable frequency compressor, which can adjust the operating frequency as needed to flexibly match different load conditions, reduce ineffective energy consumption while ensuring temperature stability; ambient side heat exchanger 4 and user side heat exchanger 14 are both finned tube heat exchangers, which enhance heat exchange efficiency with increased heat exchange area and adapt to heat exchange needs in multiple modes; the first throttling element 6 and the second throttling element 10 are both electronic expansion valves, which can accurately control the refrigerant flow rate and ensure that the system is in a high-efficiency operating state in cooling, heating and other modes; ambient side condenser fan 5 is a three-speed AC fan or a stepless speed-regulating EC fan or a stepless speed-regulating DC fan; user side supply fan 16 is a stepless speed-regulating EC fan or a stepless speed-regulating DC fan, which can adjust the wind speed according to the actual working conditions, which not only matches the heat exchange needs but also further reduces energy consumption.

[0032] Figure 2 The diagram illustrates a flowchart of a two-pipe control method for a direct expansion air conditioning unit according to an exemplary embodiment of the present invention. This method is applied to the aforementioned two-pipe control system for a direct expansion air conditioning unit. The method is executed and regulated by the control unit and includes: Step 201: Receive the operation demand command of the direct expansion air conditioning unit. The operation demand command includes at least one of the following: cooling command, heating command, dehumidification command, and defrosting command. Step 202: Adjust the working status of each component of the environmental side unit and the user side unit according to the operation requirement instructions; Step 203: Based on the control status of each component in the environmental side unit and the user side unit, guide the refrigerant to flow in the two-pipe circulation loop formed by the environmental side unit and the user side unit, and execute the refrigeration cycle, heating cycle, dehumidification cycle or defrosting cycle corresponding to the operation demand command to achieve the corresponding air handling function.

[0033] In some embodiments, Figure 3 The diagram illustrates the flow path of a refrigeration cycle provided by an exemplary embodiment of the present invention. The execution process of the refrigeration cycle includes: The four-way reversing valve is de-energized and remains in its initial state, the first throttling element is fully closed, the three-way valve is de-energized and remains in its initial reversing state, and the compressor, ambient side condenser fan and user side blower are started. The high-temperature, high-pressure gaseous refrigerant discharged from the compressor flows through the ambient heat exchanger and is condensed into high-pressure liquid refrigerant by the ambient condenser fan. It then enters the user-side unit through the first filter, the first one-way valve, and the liquid inlet pipe. High-pressure liquid refrigerant flows in through port C and out through port A of the three-way valve. After being throttled and depressurized by the second throttling element, it flows through the second filter and the heat exchanger on the user side, where it absorbs heat from the air and becomes gaseous refrigerant. Finally, it flows back to the compressor's suction port through the return pipe, the four-way reversing valve, and the vapor-liquid separator, completing the refrigeration cycle.

[0034] In this embodiment, the four-way reversing valve is de-energized and remains in its initial state, which fixes the refrigerant flow in the cooling direction and prevents chaotic flow. The first throttling element is fully closed to prevent refrigerant diversion and ensure that all refrigerant participates in the main cooling cycle. The three-way valve remains in its initial reversing state to prepare for subsequent refrigerant diversion. Simultaneously, the compressor, ambient-side condenser fan, and user-side blower are started. The compressor provides refrigerant circulation power, the ambient-side condenser fan enhances ambient-side heat release efficiency, and the user-side blower fan accelerates air circulation on the user side. The high-temperature, high-pressure gaseous refrigerant condenses into a high-pressure liquid under the cooperation of the ambient-side heat exchanger and the ambient-side condenser fan. Impurities are filtered out by the first filter, and backflow is prevented by the first one-way valve. Then, it enters the user side stably through the inlet pipe. Subsequently, the refrigerant flows in through port C and out through port A of the three-way valve, and the second throttling element reduces the pressure, allowing the refrigerant to absorb heat from the air in the user-side heat exchanger to achieve cooling. Finally, it returns through the return pipe, the four-way reversing valve, and the vapor-liquid separator.

[0035] In some embodiments, Figure 4 The diagram illustrates the flow path of a heating cycle provided by an exemplary embodiment of the present invention. The execution process of the heating cycle includes: The four-way reversing valve is energized and reversed, the second throttling element is fully closed, the three-way valve is de-energized and maintains the initial reversing state, and the compressor, ambient side condenser fan and user side blower are started. The high-temperature and high-pressure gaseous refrigerant discharged from the compressor enters the user-side unit through the four-way reversing valve and return gas pipe, flows through the user-side heat exchanger, and releases heat into high-pressure liquid refrigerant under the action of the user-side blower. After flowing in through the second filter, the second one-way valve and the A port of the three-way valve and flowing out through the C port, it enters the environmental-side unit through the liquid inlet pipe. The high-pressure liquid refrigerant is throttled and depressurized by the first throttling element, and then flows through the ambient heat exchanger. Under the action of the ambient condenser fan, it absorbs heat and becomes gaseous refrigerant. It then flows back to the compressor suction port through the vapor-liquid separator, completing the heating cycle.

[0036] In this embodiment, controlling the four-way reversing valve to switch the refrigerant flow direction in reverse allows the high-temperature refrigerant to flow preferentially to the user side. The second throttling element, when fully closed, prevents refrigerant diversion, ensuring all refrigerant participates in the main heating cycle. The three-way valve maintains its initial reversing state, stabilizing the subsequent flow path. Simultaneously, the compressor and side fans are started. The compressor provides refrigerant circulation power, the user-side fan enhances heat diffusion into the room, and the ambient-side condenser fan assists in absorbing external heat. The high-temperature, high-pressure gaseous refrigerant reaches the user side directly via the reversing valve and return pipe, releases heat in the user-side heat exchanger, removes impurities via the second filter, prevents backflow via the second one-way valve, and then enters the ambient side via the three-way valve (A in, C out) and the liquid inlet pipe. Subsequently, the first throttling element reduces pressure, the ambient-side heat exchanger absorbs external heat, and finally, the vapor-liquid separator prevents liquid refrigerant from entering the compressor.

[0037] In some embodiments, Figure 5 The diagram illustrates the flow direction of a dehumidification cycle provided by an exemplary embodiment of the present invention. The dehumidification cycle execution process includes: The four-way reversing valve is de-energized and remains in its initial state. The first throttling element is fully closed. The three-way valve is energized and reversed, starting the compressor, the ambient side condenser fan, and the user side blower. The high-temperature, high-pressure gaseous refrigerant discharged from the compressor flows through the ambient heat exchanger and is condensed into high-pressure liquid refrigerant by the ambient condenser fan. It then enters the user-side unit through the first filter, the first one-way valve, and the liquid inlet pipe. High-pressure liquid refrigerant flows in through port C and out through port B of the three-way valve, then flows through the reheat heat exchanger to release heat, and then through the third one-way valve and the second throttling element to reduce pressure. It then flows through the second filter and the user-side heat exchanger to complete the cooling and dehumidification process. After becoming gaseous refrigerant, it flows back to the compressor's suction port through the return pipe, the four-way reversing valve and the vapor-liquid separator to complete the dehumidification cycle.

[0038] In this embodiment, the four-way reversing valve is de-energized and remains in its initial state, ensuring that the refrigerant's basic flow direction is adapted to the dehumidification and heat exchange process; the first throttling element is fully closed to prevent flow diversion, ensuring that the refrigerant participates in the dehumidification cycle in a concentrated manner; the three-way valve is energized and reversed to directly guide the refrigerant to the reheat heat exchanger; simultaneously, the compressor, the ambient-side condenser fan, and the user-side blower are started, with the compressor providing the refrigerant circulation power, the ambient-side condenser fan enhancing refrigerant condensation, and the user-side blower fan driving air to complete the cooling, dehumidification, and reheating process. The high-temperature, high-pressure gaseous refrigerant first condenses into a high-pressure liquid on the ambient side, and after passing through the first filter to filter impurities and the first one-way valve to prevent backflow, it enters the user side; the flow guidance of the three-way valve (C in, B out) allows the refrigerant to first flow through the reheat heat exchanger to release heat, then pass through the second throttling element to reduce pressure, and the second filter to filter impurities before entering the user-side heat exchanger to complete cooling and dehumidification; finally, when the gaseous refrigerant flows back, the vapor-liquid separator prevents liquid slugging in the compressor.

[0039] In some embodiments, the dehumidification cycle execution process further includes a dynamic adjustment step based on the temperature parameters of the environmental side unit and the user side unit: Real-time temperature T of the environmental side unit is collected. wj and the real-time temperature T of the side unit nj Preset environmental side unit determination temperature T w and use of side unit to determine temperature T n ; When T wj ≥T w And T nj ≥T n At that time, the compressor is controlled to operate at the rated frequency, and the ambient side condenser fan and the user side supply fan operate at the preset wind speed; When T wj ≥T w And T nj <T n At the same time, the compressor is controlled to maintain the rated frequency, the ambient side condenser fan is reduced to the preset low speed, and the side supply fan is maintained at the preset speed. When T wj <T w And T nj ≥T n When the compressor is in operation, the compressor is reduced to the preset frequency, the ambient side condenser fan is reduced to the preset low speed, and the side fan is used to maintain the preset speed. When T wj <T w And T nj <T n When the compressor is in operation, the compressor frequency is reduced to the preset frequency, and both the ambient condenser fan and the user-side blower are reduced to the preset low speed.

[0040] In the embodiments of this application, the control logic under different temperature combinations has different focuses. When T wj ≥T w And T nj ≥T n When the operating conditions are suitable, the compressor operates at its rated state to ensure efficient dehumidification; when T wj ≥T w And T nj <T n When the operating temperature is low, only the ambient temperature condenser fan speed is reduced. This maintains compressor power to ensure dehumidification while preventing the operating temperature from dropping further, thus maintaining a minimum ambient temperature. wj <T w And T nj ≥T nWhen the ambient temperature is low, the compressor frequency is reduced and the ambient condenser fan speed is reduced to reduce ineffective energy consumption without affecting the temperature on the user side; when both are low, parameters are reduced in all dimensions to balance dehumidification demand and energy consumption costs.

[0041] In some embodiments, Figure 6 The diagram illustrates the flow of a defrosting cycle provided by an exemplary embodiment of the present invention. The execution process of the defrosting cycle includes: The four-way reversing valve is de-energized and remains in its initial state. The first throttling element is fully closed, the second throttling element is fully open, the three-way valve is de-energized and remains in its initial reversing state, the compressor is started and the side blower is used, and the environmental side condenser is turned off and shut down. The high-temperature, high-pressure gaseous refrigerant discharged from the compressor flows through the ambient heat exchanger, where it defrosts and releases heat, becoming a high-pressure liquid refrigerant. It then passes through the first filter, the first check valve, and the liquid inlet pipe before entering the user-side unit. High-pressure liquid refrigerant flows in through port C and out through port A of the three-way valve. After passing through the second throttling element, the second filter, and the heat exchanger on the user side, it absorbs heat from the air and becomes gaseous refrigerant. Then, it flows back to the compressor's suction port through the return pipe, the four-way reversing valve, and the vapor-liquid separator, completing the defrosting cycle. After the defrosting cycle is completed, it automatically switches back to the heating cycle.

[0042] In this embodiment, the four-way reversing valve is de-energized to maintain its initial state, fixing the refrigerant flow direction for defrosting; the first throttling element is fully closed to prevent flow diversion, ensuring that the high-temperature refrigerant flows concentratedly to the ambient side; the second throttling element is fully open to provide a smooth path for the refrigerant, contributing to defrosting efficiency; the ambient side condenser fan is shut down to prevent heat loss, allowing the high-temperature refrigerant heat to be concentrated for melting the frost on the fins; starting the side fan ensures indoor air circulation during defrosting, reducing room temperature fluctuations. When the high-temperature, high-pressure gaseous refrigerant flows through the ambient side heat exchanger, it releases heat to complete defrosting. After passing through the first filter to filter impurities and the first one-way valve to prevent backflow, it enters the user side, absorbing heat from the air to prevent over-cooling of the refrigerant. Finally, after passing through the vapor-liquid separator to prevent liquid slugging, it flows back to the compressor. The automatic switchback to the heating cycle after defrosting requires no manual intervention, quickly restoring heating and maximizing the user experience.

[0043] In summary, this technical solution receives operating demand commands from the direct expansion air conditioning unit via a control unit. These commands include at least one of cooling, heating, dehumidification, and defrosting commands. Based on these commands, the operating states of various components in the environmental and user-side units are regulated. Based on the regulated states of these components, the refrigerant is guided to flow in the two-pipe circulation loop formed by the environmental and user-side units, executing the corresponding cooling, heating, dehumidification, or defrosting cycle to achieve the corresponding air handling function. This provides a direct expansion air conditioning unit that can meet the dehumidification requirements at normal temperature while requiring only two connecting pipes for system circulation. It can operate efficiently in dehumidification mode without cooling, offering good economic performance.

[0044] It is understood that the specific examples in this document are only intended to help those skilled in the art better understand this disclosure, and are not intended to limit the scope of the invention.

[0045] It is understood that in the various embodiments of this specification, the sequence number of each process does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of this disclosure.

[0046] It is understood that the various implementation methods described in this specification can be implemented individually or in combination, and this disclosure does not limit them.

[0047] Unless otherwise stated, all technical and scientific terms used in this disclosure have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of this specification. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items. The singular forms "a," "the," and "the" as used in this disclosure and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0048] The above description is merely a specific embodiment of this specification, but the scope of protection of this invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this specification should be included within the scope of protection of this specification. Therefore, the scope of protection of this invention should be determined by the scope of the claims.

Claims

1. A two-pipe control system based on a direct expansion air handling unit, characterized by, The system comprises: an environment-side unit comprising a compressor, a vapor-liquid separator, a four-way reversing valve, an environment-side heat exchanger, an environment-side condenser fan, a first throttling element, a first filter, and a first check valve; a use-side unit comprising a three-way valve, a second throttling element, a second check valve, a third check valve, a second filter, a use-side heat exchanger, a reheat heat exchanger, and a use-side supply fan; and a control unit electrically connected to each component of the environment-side unit and the use-side unit to regulate the cooperative operation of each component. The environment-side unit and the use-side unit are connected by a liquid inlet pipe and a gas return pipe.

2. The two-pipe control system based on the direct expansion air conditioning unit according to claim 1, wherein: an exhaust port of the compressor is connected to a first port of the four-way reversing valve, a suction port of the compressor is connected to an outlet of the vapor-liquid separator, and an inlet of the vapor-liquid separator is connected to a second port of the four-way reversing valve; a third port of the four-way reversing valve is connected to a first port of the environment-side heat exchanger, a fourth port of the four-way reversing valve is connected to one end of the gas return pipe, and a second port of the environment-side heat exchanger is connected to one end of the first filter; the other end of the first filter is connected to one end of the first check valve and one end of the first throttling element, and the other end of the first check valve and the other end of the first throttling element are jointly connected to one end of the liquid inlet pipe.

3. The two-pipe control system based on the direct expansion air conditioning unit according to claim 2, wherein: the other end of the liquid inlet pipe is connected to a C port of the three-way valve, a B port of the three-way valve is connected to a first port of the reheat heat exchanger, and a second port of the reheat heat exchanger is connected to one end of the third check valve; a first port of the use-side heat exchanger is connected to one end of the second filter, a second port of the use-side heat exchanger is connected to the other end of the gas return pipe, and the other end of the second filter is connected to one end of the second check valve and one end of the second throttling element; the other end of the third check valve, the other end of the second check valve, and the other end of the second throttling element are jointly connected to an A port of the three-way valve.

4. A two-pipe control method for a direct expansion air conditioning unit, characterized by, The method is applied to the two-pipe control system based on the direct expansion air conditioning unit according to any one of claims 1 to 3, is executed and regulated by the control unit, and comprises: receiving an operation demand instruction of the direct expansion air conditioning unit, the operation demand instruction comprising at least one of a refrigeration instruction, a heating instruction, a dehumidification instruction, and a defrosting instruction; regulating the working states of each component of the environment-side unit and the use-side unit according to the operation demand instruction; based on the regulated states of each component of the environment-side unit and the use-side unit, guiding the flow of refrigerant in the two-pipe circulation loop formed by the environment-side unit and the use-side unit, and executing a refrigeration cycle, a heating cycle, a dehumidification cycle, or a defrosting cycle corresponding to the operation demand instruction to realize a corresponding air handling function.

5. The two-pipe control method of the direct expansion type air conditioning unit according to claim 4, wherein The execution process of the refrigeration cycle comprises: The four-way reversing valve is controlled to keep the initial state, the first throttling element is fully closed, the three-way valve is controlled to keep the initial reversing state, the compressor, the ambient side condensing fan and the use side air supply fan are started; The high-temperature and high-pressure gaseous refrigerant discharged by the compressor flows through the ambient side heat exchanger and is condensed into high-pressure liquid refrigerant under the action of the ambient side condensing fan, enters the use side unit through the first filter, the first check valve and the liquid inlet pipe; The high-pressure liquid refrigerant flows into the three-way valve through the C port and flows out through the A port, is throttled and pressure-reduced by the second throttling element, then flows through the second filter and the use side heat exchanger, becomes gaseous refrigerant after absorbing heat from air, and finally flows back to the suction port of the compressor through the gas return pipe, the four-way reversing valve and the vapor-liquid separator, thus completing the refrigeration cycle.

6. The two-pipe control method based on the direct expansion type air conditioning unit according to claim 4, wherein The execution process of the heating cycle comprises: The four-way reversing valve is controlled to reverse, the second throttling element is fully closed, the three-way valve is controlled to keep the initial reversing state, the compressor, the ambient side condensing fan and the use side air supply fan are started; The high-temperature and high-pressure gaseous refrigerant discharged by the compressor enters the use side unit through the four-way reversing valve and the gas return pipe, flows through the use side heat exchanger, is heat-released into high-pressure liquid refrigerant under the action of the use side air supply fan, then flows into the ambient side unit through the second filter, the second check valve and the A port of the three-way valve and flows out through the C port; The high-pressure liquid refrigerant is throttled and pressure-reduced by the first throttling element, then flows through the ambient side heat exchanger, is heated into gaseous refrigerant under the action of the ambient side condensing fan, flows back to the suction port of the compressor through the vapor-liquid separator, thus completing the heating cycle.

7. The two-pipe control method of the direct expansion type air conditioning unit according to claim 4, wherein The execution process of the dehumidification cycle comprises: The four-way reversing valve is controlled to keep the initial state, the first throttling element is fully closed, the three-way valve is controlled to reverse, the compressor, the ambient side condensing fan and the use side air supply fan are started; The high-temperature and high-pressure gaseous refrigerant discharged by the compressor flows through the ambient side heat exchanger and is condensed into high-pressure liquid refrigerant under the action of the ambient side condensing fan, enters the use side unit through the first filter, the first check valve and the liquid inlet pipe; The high-pressure liquid refrigerant flows into the three-way valve through the C port and flows out through the B port, flows through the reheating heat exchanger to release heat, is throttled and pressure-reduced by the third check valve and the second throttling element, then flows through the second filter and the use side heat exchanger to complete cooling and dehumidification, becomes gaseous refrigerant, and finally flows back to the suction port of the compressor through the gas return pipe, the four-way reversing valve and the vapor-liquid separator, thus completing the dehumidification cycle.

8. The two-pipe control method based on the direct expansion type air conditioning unit according to claim 4, characterized by, The execution process of the defrosting cycle comprises: The four-way reversing valve is controlled to keep the initial state, the first throttling element is fully closed, the second throttling element is fully opened, the three-way valve is controlled to keep the initial reversing state, the compressor and the use side air supply fan are started, and the ambient side condensing fan is controlled to stop; The high-temperature and high-pressure gaseous refrigerant discharged by the compressor flows through the ambient side heat exchanger, is heat-released to become high-pressure liquid refrigerant after defrosting, enters the use side unit through the first filter, the first check valve and the liquid inlet pipe; The high-temperature and high-pressure gaseous refrigerant discharged by the compressor flows through the ambient side heat exchanger, is heat-released to become high-pressure liquid refrigerant after defrosting, enters the use side unit through the first filter, the first check valve and the liquid inlet pipe; After the high-pressure liquid refrigerant flows into the C port of the three-way valve and flows out of the A port, it absorbs air heat through the second throtting element, the second filter and the use-side heat exchanger, becomes gaseous refrigerant, and then flows back to the suction port of the compressor through the gas return pipe, the four-way reversing valve and the gas-liquid separator, completing the defrosting cycle, After the defrosting cycle is completed, the system automatically switches back to the heating cycle.

9. The two-pipe control method of the direct expansion type air conditioning unit according to claim 7, wherein During the execution of the dehumidifying cycle, a dynamic regulation step based on the temperature parameters of the environment-side unit and the use-side unit is further included: Real-time acquisition of environment-side unit real-time temperature T wj and use-side unit real-time temperature T nj , preset environment-side unit determination temperature T w and use-side unit determination temperature T n ; When T wj ≥ T w and T nj ≥ T n , the compressor is controlled to operate at a rated frequency, and the ambient side condensing fan and the use side supply fan are controlled to operate at a preset air speed. When T wj ≥ T w , and T nj < T n , the compressor is controlled to keep running at rated frequency, the ambient side condensing fan is reduced to run at a preset low speed, and the use side supply fan keeps running at a preset speed. When T wj <T w and T nj ≥T n , the compressor is controlled to run at a preset frequency, the environment side condensing fan is controlled to run at a preset low wind speed, and the use side supply fan is controlled to keep running at a preset wind speed. When T wj <T w and T nj <T n , the compressor is controlled to run at a preset frequency, and the environment-side condensing fan and the use-side supply fan are both reduced to run at a preset low wind speed.

10. The two-pipe system control system based on the direct expansion air conditioning unit according to claims 1-3, characterized in that: the compressor is a variable frequency compressor; the environment-side heat exchanger and the use-side heat exchanger are both finned tube heat exchangers; the first throtting element and the second throtting element are both electronic expansion valves; the environment-side condensing fan is a three-speed AC fan or a stepless speed EC fan or a stepless speed DC fan; the use-side supply fan is a stepless speed EC fan or a stepless speed DC fan.

Images