Refrigeration equipment, control method and control device

Abstract

The invention provides refrigeration equipment, a control method and a control device, and relates to the technical field of refrigeration control, and the control method is suitable for a refrigeration system with double refrigeration circuits and a cooling water heat exchange circuit. The refrigeration equipment comprises a first refrigeration loop, a second refrigeration loop and a first heat exchange loop. Based on the environment load signal, the start and stop states of the first compressor and the second compressor are dynamically controlled, and energy efficiency scheduling under different loads is achieved; the air suction and exhaust parameters and the liquid outlet temperature of each refrigerating circuit are collected, the superheat degree is calculated, the opening degree of an electronic expansion valve is adjusted, and stable liquid supply of an evaporator is ensured; meanwhile, the opening degree of an electric adjusting valve of each plate heat exchanger is controlled according to the exhaust temperature or pressure, and the condensate water flow is adjusted; and condensation control is further optimized in combination with liquid outlet temperature feedback. According to the method, efficient operation and condensation decoupling of the system under different load working conditions can be achieved, and the overall refrigeration performance and stability are improved.

Description

Technical Field

[0001] This application relates to the field of refrigeration control technology, and in particular to a refrigeration equipment, control method and control device. Background Technology

[0002] Currently, data centers, communication equipment rooms, and high-precision equipment environments place higher demands on the stability, energy efficiency, and operational strategies of air conditioning systems. In such applications, cooling equipment not only needs to meet the continuous cooling requirements throughout the year and around the clock, but also should have the ability to flexibly adjust under different load conditions to avoid energy waste and operational overload.

[0003] In existing technologies, although some dual-loop air conditioning systems are equipped with multiple compressor refrigeration loops and multiple condensers, most systems still have the following shortcomings in terms of structural layout or control strategy: Firstly, the lack of awareness of environmental load and coordinated control of compressor operating status makes it impossible to effectively schedule different compressor refrigeration circuits under high and low load conditions, resulting in redundant operation of compressors in some scenarios and energy waste.

[0004] Secondly, the condenser section typically operates with a fixed water flow, without dynamic adjustment based on condensing pressure or exhaust temperature, resulting in low condensing efficiency. Furthermore, hydraulic interference exists between multiple condenser loops, affecting system stability.

[0005] Third, the lack of a superheat feedback adjustment mechanism in the refrigerant supply control can easily lead to unstable refrigerant supply to the evaporator, affecting heat exchange efficiency and even causing the risk of evaporator freezing.

[0006] Fourth, some systems lack an integrated structure for dehumidification control and supply air temperature compensation, resulting in low supply air temperature during dehumidification operation, which affects the temperature and humidity stability of the controlled environment.

[0007] Fifth, existing equipment lacks effective protection and automatic fault recovery mechanisms for abnormal conditions such as high pressure and low pressure, resulting in poor compressor safety and system fault tolerance.

[0008] Therefore, there is an urgent need to provide a refrigeration system control method and device structure that can achieve automatic adjustment under multiple load conditions, has redundant operation capability, high condensation efficiency, stable liquid supply, precise humidity and heat control, and complete fault protection and recovery mechanism. Summary of the Invention

[0009] The main objective of this invention is to provide a control method for refrigeration equipment, aiming to meet the year-round, all-weather refrigeration needs while achieving multi-dimensional linkage regulation of compressor start / stop status, liquid supply, and condensate flow, thereby realizing: The system dynamically responds to changes in environmental load and activates the refrigeration circuit as needed, achieving an optimal compressor scheduling strategy. Based on superheat feedback control of the electronic expansion valve, it improves the stability of evaporator liquid supply and avoids liquid return and frosting. By combining exhaust parameters and outlet liquid temperature to adjust the electric water valve, it optimizes the condensing efficiency of the plate heat exchanger and achieves hydraulic decoupling. Under high humidity conditions, it automatically triggers the dehumidification mode and links it with the PTC heater to ensure comfortable supply air temperature. It introduces a compressor high and low pressure fault detection and automatic reset mechanism to improve system fault tolerance and operational reliability.

[0010] This method can effectively solve problems in existing technologies such as compressor redundancy, rough condensation regulation, unstable liquid supply, lack of dehumidification compensation, and reliance on manual intervention for fault recovery, thereby improving the intelligence level and energy utilization efficiency of refrigeration systems in data centers, communication equipment rooms, and high-precision environments.

[0011] To achieve the above objectives, the present invention provides a control method for a refrigeration device, applicable to a refrigeration device including a first refrigeration circuit, a second refrigeration circuit, and a first heat exchange circuit. The first and second refrigeration circuits respectively include a compressor, an evaporator, an electronic expansion valve, and a plate heat exchanger. The first heat exchange circuit includes a liquid outlet pipe, a liquid return pipe, and multiple electrically operated regulating valves connected to the plate heat exchanger. The control method includes: Acquire environmental load signals; When the environmental load signal is lower than the first load threshold, only the first compressor is controlled to start, so that the first refrigeration circuit can operate; When the environmental load signal is higher than the second load threshold, control the first compressor and the second compressor to start simultaneously, so that the first refrigeration circuit and the second refrigeration circuit operate simultaneously. Multiple sensor signals from the first refrigeration circuit and the second refrigeration circuit are acquired respectively. The sensor signals include at least the suction temperature, suction pressure, exhaust temperature, exhaust pressure and liquid outlet temperature. Based on the suction temperature and suction pressure, the superheat of each loop is calculated, and the opening of the electronic expansion valve corresponding to each evaporator is controlled to maintain the superheat within the target range. Based on the exhaust temperature or exhaust pressure, the opening of the electric regulating valve corresponding to each plate heat exchanger is controlled to regulate the condensate flow rate. Based on the outlet temperature, control the opening degree of the electric regulating valve; When the environmental load is detected to drop below the third load threshold, the second compressor is shut down, and only the first compressor is kept running.

[0012] In one embodiment, the control method further includes: Obtain the discharge pressure and suction pressure of the first compressor and the second compressor; When the pressure protection fault condition is met, the corresponding compressor is controlled to stop running and a fault alarm signal is output. The pressure protection fault conditions include determining whether the exhaust pressure is higher than the set high pressure protection threshold, or whether the intake pressure is lower than the set low pressure protection threshold.

[0013] In one embodiment, when the exhaust pressure and intake pressure return to the set safe operating range and continue to meet the preset time condition, the fault state is automatically lifted and the compressor is controlled to resume operation.

[0014] In one embodiment, calculating the superheat of each loop based on the intake temperature and intake pressure, and controlling the opening of the electronic expansion valve corresponding to each evaporator to maintain the superheat within a target range includes: Obtain the suction temperature and suction pressure at the evaporator outlet; The superheat of the evaporator is calculated based on the suction temperature and suction pressure. The superheat is compared with the target superheat, and the deviation value is calculated; Adjust the opening of the electronic expansion valve according to the deviation value so that the superheat tends to be within the target superheat range.

[0015] In one embodiment, the control method further includes: Obtain the freezing temperature from the freezing temperature sensor located on the evaporator; If the freezing temperature is lower than the freezing protection temperature threshold, the electronic expansion valve is controlled to reduce its opening to decrease the liquid supply to the evaporator, or the corresponding compressor is controlled to stop running to interrupt the refrigeration process.

[0016] In one embodiment, the control method further includes: Obtain ambient humidity; When the ambient humidity is higher than the dehumidification threshold, the evaporator is controlled to perform a refrigeration and dehumidification operation. In addition, the PTC heater is turned on to heat and compensate the supply air after it has been treated by the evaporator, so that the supply air temperature is maintained within the target range.

[0017] In one embodiment, controlling the opening of the electrically operated regulating valve corresponding to each plate heat exchanger based on the exhaust temperature or exhaust pressure to regulate the condensate flow rate includes: Obtain exhaust temperature and exhaust pressure; Determine whether the exhaust temperature or exhaust pressure deviates from the target condensation parameter range; When the exhaust temperature is higher than the exhaust temperature threshold or the exhaust pressure is higher than the exhaust pressure threshold, the electric regulating valve connected to the corresponding plate heat exchanger is controlled to increase the opening degree to increase the cooling water flow rate. When the exhaust temperature is lower than the exhaust temperature threshold or the exhaust pressure is lower than the exhaust pressure threshold, the electric regulating valve is controlled to reduce its opening to reduce the cooling water flow. The outlet liquid temperature signal of the plate heat exchanger is acquired, and the opening degree of the electric regulating valve is adjusted according to the outlet liquid temperature.

[0018] The present invention also provides a control device, the control device comprising: a memory, a processor, and a control program for a refrigeration device stored in the memory and executable on the processor, the control program for the refrigeration device being configured to implement the control method described above.

[0019] The present invention also provides a refrigeration device, the refrigeration device comprising: The first refrigeration circuit and the second refrigeration circuit each include a compressor, an evaporator, an electronic expansion valve, and a plate heat exchanger. The first refrigeration circuit and the second refrigeration circuit are set up independently for parallel or alternating operation. The first heat exchange circuit includes an outlet pipe, a return pipe, and multiple cooling water branches connected to the plate heat exchanger. Each of the multiple cooling water branches is equipped with an electric regulating valve for regulating the flow rate of cooling water through the plate heat exchanger. Multiple sensors, including at least a suction temperature sensor, a suction pressure sensor, an exhaust temperature sensor, and an exhaust pressure sensor respectively disposed in the first refrigeration circuit and the second refrigeration circuit, and a temperature sensor disposed in the first heat exchange circuit for monitoring the liquid outlet temperature of the plate heat exchanger. The control device.

[0020] In one embodiment, the plurality of electrically controlled valves include a first electrically controlled valve and a second electrically controlled valve corresponding to each of the two plate heat exchangers, and a third electrically controlled valve disposed on the liquid outlet main pipeline of the first heat exchange circuit. The control device is configured to control the opening degree of the first and second electric regulating valves according to the exhaust pressure or exhaust temperature, and to correct the regulation result of the electric regulating valves based on the liquid outlet temperature, so as to achieve independent condensation control and hydraulic decoupling for different plate heat exchangers. Attached Figure Description

[0021] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic flowchart of a control method according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the system architecture of a refrigeration device according to another embodiment of the present invention.

[0024] Attached image captions: 10. First heat exchange circuit; 20. First refrigeration circuit; 30. Second refrigeration circuit.

[0025] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0026] 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. Well-known modules, units, and their connections, links, communications, or operations are not shown or described in detail. Furthermore, the described features, architectures, or functions can be combined in any way in one or more embodiments. Those skilled in the art should understand that the various embodiments described below are only for illustrative purposes and are not intended to limit the scope of protection of the present invention.

[0027] While most existing dual-loop refrigeration systems are equipped with two or more compressor refrigeration loops, the start-stop control between these loops often relies on coarse-grained logic such as timing or temperature difference, lacking real-time sensing and judgment of environmental heat load. This results in the inability to promptly initiate multi-loop operation under high load, while multiple compressors often operate redundantly under low load, increasing energy consumption and lacking strategic optimization space.

[0028] In most systems, the cooling water flow rate used by the condenser (such as a water-cooled plate heat exchanger) is a constant flow rate or a manually adjustable valve setting, failing to be linked to condensing load parameters such as exhaust temperature and condensing pressure. This "static" condensation method, on the one hand, cannot adjust the heat exchange capacity according to load changes, resulting in energy waste; on the other hand, when two loops are running simultaneously, hydraulic interference exists between the cooling water branches, causing one heat exchanger to be overcooled and the other to be undercooled, reducing the overall stability and efficiency of the system.

[0029] Evaporator liquid supply control still mainly relies on fixed opening degree or simplified temperature control logic, lacking a dynamic adjustment mechanism based on "superheat" feedback, making it difficult to achieve a balance between sufficient heat exchange in the evaporator and compressor suction protection. Under high load fluctuations or low air volume conditions, it is very easy to cause excessive or insufficient liquid supply to the evaporator, resulting in freezing, liquid return, or efficiency loss.

[0030] Although some systems have dehumidification capabilities, during deep dehumidification (low-temperature evaporation), the supply air temperature drops significantly. The lack of a matching reheating device (such as a PTC module) to replenish the temperature results in excessively low supply air temperature, which can easily lead to condensation accumulation or affect the comfort of personnel, especially in the high humidity and low temperature conditions of spring and autumn.

[0031] Most systems only have high-pressure / low-pressure switches for compressor protective shutdown, but lack subsequent automatic detection and restart logic, requiring manual reset and causing a decrease in system availability. In unattended scenarios (such as at night or in remote server rooms), once a fault is triggered, it will lead to a prolonged cooling interruption, affecting equipment safety.

[0032] The main solution in this application embodiment is: A control method and device structure for a refrigeration system that is oriented towards multi-load conditions, supports redundant operation, features independent condensation regulation, stable liquid supply, controllable dehumidification, and complete fault self-recovery capability are proposed. The main improvement directions are as follows: The control method introduces environmental load signals as scheduling judgment benchmarks, and divides the start-stop logic into multiple segments through the first threshold, the second threshold, and the third threshold to ensure that a single compressor runs under low load and a dual-loop system is automatically started under high load, so as to realize on-demand allocation of compressor resources and reduce unnecessary energy consumption.

[0033] The water flow rate of the plate heat exchanger is no longer fixed, but dynamically adjusted by an electric regulating valve based on the exhaust temperature and exhaust pressure. At the same time, the outlet liquid temperature is superimposed as feedback correction to achieve true "load-matching condensation control". In addition, a balancing branch valve is set up to achieve hydraulic decoupling between multiple plate heat exchangers.

[0034] The electronic expansion valve before each evaporator is dynamically adjusted by the controller based on the real-time calculated "superheat" value, ensuring that the heat exchange zone of the evaporator is fully vaporized and that there is no risk of liquid return at the compressor suction end, thereby improving evaporation efficiency and system stability.

[0035] When humidity exceeds the standard, the dehumidification mode is automatically activated, and the PTC heater is activated to compensate for the air supply, so that the dehumidification efficiency and the air supply temperature are balanced and unified, solving the problem of "excessive dehumidification and cooling" in traditional systems and improving the stability of both temperature and humidity.

[0036] The control system continuously monitors the intake and exhaust pressures. When a high-pressure or low-pressure abnormality is triggered, it automatically shuts down and outputs a fault signal. When the system pressure returns to a safe range and remains there for a certain period of time, it automatically determines that the condition has been resolved and resumes operation of the corresponding compressor without manual intervention, greatly improving system reliability and unattended operation capability.

[0037] Reference Figure 1 In one embodiment of the present invention, the control method of the refrigeration equipment includes steps S100-S400, wherein: S100, acquire environmental load signal; S200: When the environmental load signal is lower than the first load threshold, only the first compressor is controlled to start, so that the first refrigeration circuit can operate; when the environmental load signal is higher than the second load threshold, both the first and second compressors are controlled to start, so that both the first and second refrigeration circuits can operate simultaneously; when the environmental load is detected to drop below the third load threshold, the second compressor is controlled to shut down, so that only the first compressor can operate. S300, acquire multiple sensor signals from the first refrigeration circuit and the second refrigeration circuit respectively, wherein the sensor signals include at least the intake temperature, intake pressure, exhaust temperature, exhaust pressure and liquid outlet temperature; S400: Based on the suction temperature and suction pressure, calculate the superheat of each loop and control the opening of the electronic expansion valve corresponding to each evaporator to maintain the superheat within the target range; based on the exhaust temperature or exhaust pressure, control the opening of the electric regulating valve corresponding to each plate heat exchanger to regulate the condensate flow rate; based on the liquid outlet temperature, control the opening of the electric regulating valve.

[0038] This method dynamically controls the start-up and shutdown status of two refrigeration circuits based on environmental load conditions, and adjusts the refrigerant supply and condensate heat exchanger flow in a coordinated manner to achieve efficient and stable operation.

[0039] During system operation, the control device first obtains the environmental load signal. If the environmental load is lower than the first load threshold, the control system only starts the first compressor to drive the first refrigeration circuit to operate independently.

[0040] At this point, in the first refrigeration circuit, the compressor compresses the low-pressure refrigerant into a high-pressure, high-temperature gaseous refrigerant and discharges it. It should be noted that the compressor is the core component of the refrigeration system, used to drive refrigerant circulation and increase refrigerant pressure, thereby driving the subsequent condensation and throttling processes.

[0041] The discharged high-temperature, high-pressure refrigerant then enters a plate heat exchanger for condensation. It should be noted that a plate heat exchanger is a device that exchanges heat between refrigerant and water. Inside, the refrigerant exchanges heat with the cooling water through channels between several metal plates, transferring heat to the water flow and thus condensing the refrigerant into a liquid.

[0042] The liquid refrigerant from the plate heat exchanger is throttled and depressurized by an electronic expansion valve before entering the evaporator. It should be noted that the electronic expansion valve is a precision, electrically controlled valve whose opening degree can be adjusted according to controller commands, thereby dynamically controlling the refrigerant flow into the evaporator and achieving precise liquid supply to the evaporator load.

[0043] After absorbing heat from the air side and vaporizing in the evaporator, the refrigerant flows through the suction pipe back to the compressor in a closed loop. During this process, the control device acquires the temperature and pressure signals on the suction side in real time. It should be noted that the suction temperature refers to the actual temperature of the refrigerant at the evaporator outlet, and the suction pressure is the refrigerant pressure at that location; both of these factors together determine the superheat of the refrigerant.

[0044] The controller calculates the superheat using the suction temperature and pressure, compares it with the target superheat, and if a deviation exists, corrects the liquid supply by adjusting the opening of the electronic expansion valve to ensure the evaporator maintains a stable and sufficient heat exchange state. It should be noted that superheat refers to the portion of the gaseous refrigerant temperature above the saturation temperature after evaporation, reflecting whether evaporation is complete and whether there is a risk of liquid return.

[0045] When the environmental load increases and exceeds the second load threshold, the control device simultaneously starts the second compressor, causing the second refrigeration circuit to operate in conjunction with the first circuit to meet the greater cooling load demand. At this time, both refrigeration circuits are running, and the refrigerant on the condenser side enters the corresponding plate heat exchanger and is simultaneously connected to the cooling water branch in the first heat exchange circuit.

[0046] Cooling water enters through the main inlet pipe and flows through three branch pipes to two plate heat exchangers and a balancing branch. Each branch is equipped with an electrically controlled regulating valve. It should be noted that the electrically controlled regulating valve is an electronically controlled actuator that adjusts the valve opening according to the controller signal to control the speed at which cooling water flows through the plate heat exchanger, thus affecting the condensation effect.

[0047] The control device determines the current condensing load based on changes in temperature or pressure on the compressor's exhaust side, and adjusts the opening of the electrically controlled regulating valve connected to the plate heat exchanger accordingly to automatically regulate the condensing capacity. For example, if the exhaust temperature rises, indicating insufficient condensation, the controller will increase the water valve opening to increase the cooling water flow rate and improve condensing efficiency; if the exhaust temperature is too low, it will reduce the water flow to avoid energy waste.

[0048] It should be noted that the exhaust temperature is the temperature of the refrigerant before it leaves the compressor and enters the plate heat exchanger, and the exhaust pressure is the refrigerant pressure at that point. These values ​​reflect the heat load and flow state before the condenser and are important bases for adjusting the condensate flow rate.

[0049] In addition, the control system also collects the outlet temperature of each plate heat exchanger as adjustment feedback. It should be noted that the outlet temperature refers to the temperature change when the refrigerant condenses into a liquid state after passing through the plate heat exchanger. It not only reflects the condensation effect, but can also be used to further correct the water valve regulation behavior, forming a complete closed-loop control path.

[0050] If the system detects that the environmental load has dropped below the third load threshold again, it will shut down the second compressor, keeping only the first refrigeration circuit running. Through this dynamic compressor combination control, combined with refrigerant supply and condensate flow regulation, this method can achieve dual optimization of the refrigeration system's operating capacity and energy efficiency.

[0051] The entire control process uses sensors as inputs and actuators as control targets, forming a multi-loop collaborative control strategy based on load sensing. It has the advantages of fast response speed, high adjustment accuracy, and high system energy efficiency, and is suitable for refrigeration scenarios with high load fluctuations and high energy efficiency requirements.

[0052] Optionally, in one embodiment, to ensure that the system has reliable self-protection capability under abnormal pressure conditions and can automatically reset and restart after pressure recovery, the control method further introduces compressor pressure protection logic and automatic fault recovery mechanism.

[0053] During system operation, the control device continuously monitors the suction and discharge pressures of the first and second compressors. When the discharge pressure of either compressor exceeds the set high-pressure protection threshold, or the suction pressure falls below the set low-pressure protection threshold, the system will immediately trigger a protection action, stop the corresponding compressor from operating, and output a fault alarm signal.

[0054] It should be noted that discharge pressure refers to the pressure of the high-temperature and high-pressure refrigerant at the compressor outlet. If the discharge pressure is too high, it indicates insufficient condensation or insufficient condensate flow, which may lead to compressor overload or even damage. Suction pressure, on the other hand, is the low-pressure state of the refrigerant at the compressor inlet. If the suction pressure is too low, it may indicate insufficient liquid supply or evaporator freezing, or abnormal refrigerant return, which can also damage the compressor.

[0055] Once the system enters protection mode, it will no longer automatically restart but will continue to monitor the two parameters mentioned above. When it is detected that the compressor's discharge pressure and suction pressure have both returned to the set safe operating range and have remained within this range for more than a preset time threshold (e.g., 30 seconds), the system is determined to be stable, and the control device will automatically clear the fault state, restart the compressor, and restore the refrigeration operation of its corresponding circuit.

[0056] It should be noted that the introduction of preset time conditions can effectively prevent pressure fluctuations from repeatedly triggering faults and resets within a short period of time, thereby improving the stability and safety of system operation. This automatic reset mechanism is particularly suitable for unattended computer room air conditioning or long-term industrial environments, and can significantly improve system availability and fault tolerance.

[0057] Optionally, in one embodiment, to ensure that the evaporator operates in a stable and efficient heat exchange state, the system employs a dynamic adjustment strategy based on superheat feedback to control the opening of the electronic expansion valve. This strategy calculates the actual superheat by real-time acquisition of the suction temperature and suction pressure at the evaporator outlet and compares it with the target superheat, thereby precisely controlling the refrigerant supply.

[0058] Specifically, the control device continuously collects the suction temperature and suction pressure at the evaporator outlet in the first and second refrigeration circuits.

[0059] The controller calculates the saturation temperature corresponding to the suction pressure based on a preset saturation pressure-temperature lookup table or refrigerant property formula, and subtracts this saturation temperature from the actual suction temperature to obtain the current superheat value. It should be noted that superheat is the temperature difference between the actual refrigerant temperature and its saturation temperature, reflecting whether the refrigerant in the evaporator has fully vaporized, and is a key criterion for preventing liquid refrigerant from flowing back into the compressor.

[0060] The calculated superheat is compared with the target superheat set in the controller (e.g., 5℃~8℃) to obtain the superheat deviation value. If the current superheat is higher than the target range, it indicates that the evaporator is supplying too little liquid, and the control device will appropriately increase the opening of the electronic expansion valve to increase the refrigerant flow into the evaporator; conversely, if the superheat is too low, the opening of the expansion valve will be reduced to decrease the liquid supply.

[0061] It should be noted that the electronic expansion valve is an electronically controlled throttling device with fast response and high adjustment accuracy. Its opening degree can be continuously adjusted by PWM signal or stepper motor command, making it very suitable for superheat closed-loop control applications.

[0062] Optionally, in one embodiment, to prevent coil icing during low-temperature operation of the evaporator, the system incorporates protective control logic based on freezing temperature detection. When the evaporator surface temperature is detected to be below a safe threshold, the control device will automatically adjust the liquid supply of the electronic expansion valve or suspend the compressor operation to interrupt the refrigeration process and ensure stable system operation.

[0063] During system operation, each evaporator is equipped with a freezing temperature sensor, which is installed at the evaporator outlet or on the surface of the heat exchange coil to monitor the evaporator's minimum operating temperature in real time. It should be noted that the freezing temperature sensor is a high-sensitivity negative temperature coefficient (NTC) thermistor specifically designed to determine whether the evaporator is in a near-freezing temperature state.

[0064] After acquiring the freezing temperature signal, the controller compares its real-time value with a preset freezing protection temperature threshold, typically set to 2°C or 0°C. If the freezing temperature falls below this threshold, the system immediately enters protection mode. Based on the current system operating conditions, the controller may prioritize reducing the opening of the electronic expansion valve, thereby reducing the amount of refrigerant supplied to the evaporator and slowing down the evaporator's cooling trend.

[0065] It should be noted that reducing the opening of the electronic expansion valve can quickly suppress the evaporator load, preventing excessive refrigerant from accumulating in the evaporation zone under low load, thereby avoiding further cooling to the freezing point.

[0066] If the system continuously detects a sustained drop in freezing temperature and the liquid supply regulation cannot effectively curb the accumulation of cold energy, the control device will trigger the second-level protection, directly shutting down the corresponding compressor and forcibly interrupting the operation of that refrigeration circuit to allow the evaporator to recover naturally. After the compressor stops, the system can still keep the fan running, using airflow to accelerate the defrosting process on the evaporator surface.

[0067] Optional, refer to Figure 2 This embodiment provides an air conditioning refrigeration equipment based on a dual refrigeration circuit and a chilled water plate heat exchanger system. The system mainly consists of a first refrigeration circuit, a second refrigeration circuit, and a cooling water circuit coupled thereto. The system as a whole achieves adjustable refrigeration capacity and condensing heat regulation function through a parallel structure.

[0068] The first refrigeration circuit centers on compressor-1# (inverter). After condensation in plate heat exchanger-1, the refrigerant enters the dryer filter and sight glass. The liquid refrigerant then enters evaporator-1 via electronic expansion valve EEV-1, where it absorbs heat and vaporizes. Downstream of the evaporator is a freezing temperature sensor and a fan. The fan drives airflow through the evaporator and delivers it to the target area. The refrigerant gas, after passing through suction temperature and pressure sensors, enters the compressor's suction end, forming a closed loop. Its discharge end is connected to discharge temperature and pressure sensors. The gas from the compressor is then sent back to plate heat exchanger-1, resulting in liquid output.

[0069] The second refrigeration circuit is similar in structure to the first circuit, driven by compressor-2# (fixed frequency). Its suction end is connected to evaporator-2. Plate heat exchanger-2 sends the gas through the dryer filter and sight glass. The refrigerant gas condensed in the evaporator passes through suction temperature and pressure sensors and then enters the suction end of compressor-2# (fixed frequency) to form a closed loop. The exhaust gas from this compressor passes through exhaust temperature and pressure sensors and then enters plate heat exchanger-2, forming liquid outlet. Unlike the first evaporator, a PTC heater assembly is added downstream of evaporator-2 to reheat and compensate for the low-temperature air supply during dehumidification operation, improving air supply comfort.

[0070] The condensers of the two refrigeration circuits (plate heat exchangers-1 and-2) share a single cooling water system. This system has a main outlet manifold and a main inlet manifold, and is connected to the two plate heat exchangers and one heat exchange circuit via three cooling water branches. The heat exchange circuit is connected to an electrically controlled regulating valve V-1#, plate heat exchanger-1 is connected to an electrically controlled regulating valve V-2#, and plate heat exchanger-2 is connected to an electrically controlled regulating valve V-3# with on / off control function. Cooling water enters through the main inlet, is distributed to the two plate heat exchangers for heat exchange according to control logic, and is then discharged through the outlet manifold.

[0071] It should be noted that on / off control refers to a control method that regulates the opening and closing of liquid or gas flow paths. In this invention, on / off control specifically refers to the electric regulating valve, under the command of the control system, adjusting the valve opening to achieve the opening, closing, or continuous proportional regulation of cooling water flow. Although the term contains the word "on / off," it is not limited to simple switching operations but possesses a certain linear regulation capability. It can be used as a flow controller in refrigeration systems to match the cooling water demand under different condensing load conditions, playing a role in stabilizing system operation and dynamic regulation.

[0072] All sensor signals are ultimately fed into the control unit, which controls the compressor's start / stop status based on environmental load information. Under low load, only the first refrigeration circuit operates, while under high load, both circuits operate in parallel. Simultaneously, the electronic expansion valve adjusts the liquid supply in real time based on suction pressure and temperature to maintain stable superheat. Furthermore, the opening of the electric water valve is adjusted based on discharge pressure or temperature to control the condensate flow of each plate heat exchanger, with further feedback correction based on the outlet liquid temperature. Structurally, this system possesses high-efficiency heat exchange and heat load decoupling capabilities, while simultaneously achieving multi-condition, dynamic energy efficiency optimization through sensor network and controller collaboration.

[0073] Optionally, in one embodiment, to meet the dehumidification needs in high-humidity environments while avoiding discomfort or condensation risks caused by excessively low supply air temperature during dehumidification, a "dehumidification + PTC reheat" linkage control mechanism is introduced. This mechanism determines whether to enter dehumidification mode based on ambient humidity and compensates for supply air temperature by controlling the PTC heater, ensuring that the system maintains a stable supply air temperature within the target comfort range while performing dehumidification.

[0074] During system operation, the control device acquires ambient humidity parameters in real time. It should be noted that the ambient humidity is a relative humidity value, expressed as a percentage, obtained from humidity sensors installed at the return air vent or supply air duct, and is used to assess the current water vapor content in the air.

[0075] When the ambient humidity is detected to be higher than the preset dehumidification threshold (e.g., set to 70%RH), the system enters the dehumidification control logic. The control device instructs the evaporator to start performing refrigeration and dehumidification operations, that is, by lowering the surface temperature of the evaporator, water vapor in the air is condensed and precipitated, thereby achieving the purpose of air drying.

[0076] However, since dehumidification is essentially a deep cooling process, it can easily result in low supply air temperature. Therefore, while performing dehumidification, the controller will also activate the PTC heater. It should be noted that the PTC heater is a positive temperature coefficient thermistor heating element. Its characteristic is that its resistance increases as the temperature rises, thereby automatically adjusting its heating capacity. It also has an overheat self-limiting current function, making it suitable for safe heating at the air supply terminal.

[0077] The PTC heater is located in the air supply duct downstream of the evaporator to compensate for the temperature rise of the dehumidified cold air. The controller compares the current supply air temperature with the target supply air temperature and adjusts the output power of the PTC heater until the supply air temperature is maintained within the set comfortable range, such as 18℃~22℃.

[0078] Optionally, in one embodiment, to improve condensation efficiency, optimize energy consumption, and avoid overcooling or insufficient condensation, the system introduces a control method based on the combined adjustment of compressor discharge parameters and outlet liquid temperature to regulate the cooling water flow rate of the plate heat exchanger. This method dynamically controls the opening of the electric regulating valve by real-time sensing of the refrigerant discharge status and the refrigerant temperature at the heat exchanger outlet, thereby precisely regulating the amount of cooling water entering the plate heat exchanger and constructing a closed-loop regulation logic for the condensation section.

[0079] During system operation, the controller acquires the temperature and pressure at the compressor discharge end of each refrigeration circuit in real time. It should be noted that the discharge temperature is the temperature at which the refrigerant is discharged from the compressor after compression, reflecting the system's refrigeration load and compression ratio; the discharge pressure is the corresponding high-pressure side refrigerant pressure, which reflects changes in the heat exchange load on the condenser side.

[0080] The controller compares the acquired exhaust temperature and pressure with their respective set target thresholds. When the exhaust temperature or pressure exceeds the corresponding threshold (e.g., exhaust temperature threshold of 90℃, exhaust pressure threshold of 2.3MPa), it indicates that the current condensation effect is insufficient. The system will then control the electric regulating valve connected to the plate heat exchanger of this loop to increase its opening, thereby increasing the cooling water flow, enhancing the condensation capacity, and reducing the high-pressure load on the system.

[0081] Conversely, if the exhaust temperature or exhaust pressure is lower than the set lower limit, it indicates that there may be excessive cooling water, which may lead to over-cooling of the refrigerant, reduced energy efficiency, or even affect the subsequent throttling effect. In this case, the controller will reduce the opening of the electric regulating valve, reduce the water flow, and increase the refrigerant condensation temperature to bring the system back to the normal range.

[0082] To further improve regulation accuracy and system response speed, the controller will also acquire the refrigerant outlet temperature at the plate heat exchanger outlet in real time as additional feedback. It should be noted that the outlet temperature is the temperature at which the refrigerant flows out after completing phase change in the plate heat exchanger. If it deviates from the target range (such as being undercooled or insufficiently condensed), it will also trigger a correction to the opening of the electric regulating valve.

[0083] For example, if the exhaust temperature is within the threshold range but the liquid temperature is significantly lower (overcooled), the system can still reduce the valve opening; while if the liquid temperature is higher (insufficient condensation), even if the exhaust parameters have not exceeded the limits, the water volume can be increased in advance for early intervention.

[0084] By employing this "main control of exhaust parameters combined with feedback correction of outlet liquid temperature" adjustment strategy, the system achieves precise control of the cooling water flow in the plate heat exchanger. This not only ensures consistently high efficiency and stability in the condensing section but also avoids energy waste, making it suitable for condensing loops with large fluctuations in operating conditions. This strategy can be applied independently to each refrigeration loop, ensuring that the hydraulics in the dual-loop structure do not interfere with each other, achieving hydraulic decoupling and zoned condensation optimization.

[0085] Optionally, the present invention provides a refrigeration device with a dual refrigeration circuit structure and cooling water branch adjustment function. The device can flexibly configure the refrigeration capacity according to the environmental load and improve the condensation efficiency by adjusting the water flow through multiple valves, thereby achieving dynamic balance and high energy efficiency output of the system operation.

[0086] The refrigeration equipment comprises two independent refrigeration circuits: a first refrigeration circuit and a second refrigeration circuit. Each circuit is independently equipped with a compressor, evaporator, electronic expansion valve, and plate heat exchanger. The two refrigeration circuits are structurally independent and can be started in parallel or switched alternately as needed. They can provide coordinated cooling under high loads or operate independently to save energy in low-load scenarios.

[0087] It should be noted that the compressor is the core driving component used to compress the refrigerant, the evaporator is responsible for absorbing heat from the air side, the electronic expansion valve precisely controls the amount of refrigerant supplied to the evaporator, and the plate heat exchanger undertakes the condensation task, converting the gaseous refrigerant into a liquid state through heat exchange with cooling water, thus completing the high-pressure section heat exchange function of the refrigeration circuit.

[0088] Corresponding to the two refrigeration loops mentioned above, the system is equipped with a first heat exchange loop, namely the cooling water circulation system, which includes a main liquid outlet pipe, a main liquid return pipe, and multiple cooling water branches connected to the plate heat exchanger. Each branch is equipped with an independent electric regulating valve to adjust the flow capacity of the water side of the plate heat exchanger, thereby dynamically adapting to changes in the condensation load of each loop.

[0089] To achieve precise control, the equipment is equipped with temperature and pressure sensors on both the suction and exhaust sides of each refrigeration circuit to collect suction temperature, suction pressure, exhaust temperature, and exhaust pressure information, respectively. At the same time, in the water heat exchange system, an outlet liquid temperature sensor is installed on the outlet side of each plate heat exchanger to collect real-time information on the liquid temperature of the refrigerant after condensation in the heat exchanger.

[0090] It should be noted that the exhaust-side sensor reflects the load status of the compressor's high-pressure section, while the liquid outlet temperature is used to assess whether condensation is sufficient and is an important feedback parameter for adjusting the water valve opening.

[0091] To achieve independent control of condensation capacity and hydraulic decoupling, multiple electrically operated regulating valves are strategically configured. Specifically, the first electrically operated regulating valve controls the water circuit connected to control switch-1, and the second electrically operated regulating valve controls the water circuit to control switch-2; both are used to regulate the condensate flow rate corresponding to the two refrigeration circuits, respectively. In addition, the system is equipped with a third electrically operated regulating valve, installed in the first heat exchange circuit, to control the liquid output rate of the first heat exchange circuit.

[0092] The control device determines the current condenser load based on exhaust temperature or pressure and independently controls the opening of the first and second electric regulating valves. When an increase in exhaust temperature or pressure is detected in a certain refrigeration circuit, it is determined that the condensing load has increased, and the corresponding water valve connected to the heat exchanger will increase its opening to increase the cooling water flow and enhance the condensing capacity. Conversely, the opening will be appropriately reduced to maintain stable operation in the condensing zone.

[0093] Meanwhile, the controller also references the outlet temperature of the plate heat exchanger in real time to fine-tune the water valve adjustment, avoiding overshoot or lag issues. A lower outlet temperature indicates more complete condensation; if the temperature is too low, the controller can appropriately tighten the valve to prevent excessive cooling water and energy waste.

[0094] The third electric regulating valve automatically opens when there is a significant difference in condensation load between the two main branches, forming a bypass flow path, reducing the hydraulic burden on individual heat exchangers, and improving the stability of the system's water-side circulation.

[0095] Through its structure and control logic, this refrigeration equipment can not only flexibly adapt to varying loads but also possesses highly controllable condensation regulation capabilities and system redundancy. It is suitable for scenarios requiring high system continuity and stability, such as data centers, precision air conditioning, and industrial temperature control. The entire operation is autonomously completed by the controller, ensuring a balance between system efficiency and reliability.

[0096] The present invention also proposes a control device, the control device comprising: a memory, a processor, and a control program stored in the memory and executable on the processor, the control program being configured to implement the control method as described above.

[0097] It is worth noting that since the control device of the present invention is based on the control method described above, the embodiments of the control device of the present invention include all the technical solutions of all the embodiments of the control method described above, and the technical effects achieved are exactly the same, so they will not be repeated here.

[0098] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A control method of a refrigeration apparatus, characterized by, The control method is applied to a refrigeration device, and a refrigeration device comprising a first refrigeration circuit, a second refrigeration circuit, and a first heat exchange circuit, wherein the first refrigeration circuit and the second refrigeration circuit each comprise a compressor, an evaporator, an electronic expansion valve, and a plate heat exchanger, and the first heat exchange circuit comprises a liquid outlet pipeline, a liquid return pipeline, and a plurality of electric regulating valves connected to the plate heat exchangers, and the control method comprises: obtaining an environmental load signal; in the case that the environmental load signal is lower than a first load threshold, only controlling the first compressor to start to make the first refrigeration circuit operate; in the case that the environmental load signal is higher than a second load threshold, controlling the first compressor and the second compressor to start simultaneously to make the first refrigeration circuit and the second refrigeration circuit operate simultaneously; in the case that the environmental load is detected to be reduced to below a third load threshold, controlling the second compressor to stop and only maintaining the first compressor to operate; obtaining a plurality of sensor signals of the first refrigeration circuit and the second refrigeration circuit respectively, wherein the sensor signals at least comprise suction temperature, suction pressure, discharge temperature, discharge pressure, and liquid outlet temperature; based on the suction temperature and the suction pressure, calculating the superheat degree of each circuit, and controlling the opening degree of the electronic expansion valve corresponding to each evaporator to make the superheat degree maintain in a target range; based on the discharge temperature or the discharge pressure, controlling the opening degree of the electric regulating valve corresponding to each plate heat exchanger to adjust the condensate water flow; based on the liquid outlet temperature, controlling the opening degree of the electric regulating valve.

2. The control method according to claim 1, characterized by, The control method further comprises: obtaining the discharge pressure and the suction pressure of the first compressor and the second compressor; when a pressure protection fault condition is met, controlling the corresponding compressor to stop operating and outputting a fault alarm signal; the pressure protection fault condition comprises judging whether the discharge pressure is higher than a set high-pressure protection threshold or whether the suction pressure is lower than a set low-pressure protection threshold.

3. The control method according to claim 2, characterized by, when the discharge pressure and the suction pressure recover to a set safe operating range and continuously meet a preset time condition, automatically removing the fault state and controlling the compressor to resume operating.

4. The control method according to claim 1, characterized by, based on the suction temperature and the suction pressure, calculating the superheat degree of each circuit, and controlling the opening degree of the electronic expansion valve corresponding to each evaporator to make the superheat degree maintain in a target range comprises: obtaining the suction temperature and the suction pressure at the outlet of the evaporator; calculating the superheat degree of the evaporator based on the suction temperature and the suction pressure; comparing the superheat degree with a target superheat degree to calculate a deviation value; adjusting the opening degree of the electronic expansion valve according to the deviation value to make the superheat degree tend to be within the target superheat degree range.

5. The control method according to claim 1, characterized by, The control method further comprises: obtaining the freezing temperature of a freezing temperature sensor arranged on the evaporator; in the case that the freezing temperature is lower than a freezing protection temperature threshold, controlling the electronic expansion valve to reduce the opening degree to reduce the liquid supply amount of the evaporator, or controlling the corresponding compressor to suspend operation to interrupt the refrigeration process.

6. The control method according to claim 1, characterized by, The control method further comprises: obtaining the environmental humidity; in the case that the environmental humidity is higher than a dehumidification threshold, controlling the evaporator to perform a refrigeration dehumidification operation; and the PTC heater is turned on to heat and compensate the air supply after the evaporator, so that the air supply temperature is maintained in the target range.

7. The control method according to claim 1, characterized by, The opening degree of the electric regulating valve corresponding to each plate heat exchanger is controlled based on the exhaust temperature or exhaust pressure to adjust the condensate flow. An exhaust temperature and an exhaust pressure are obtained. It is determined whether the exhaust temperature or the exhaust pressure deviates from a target condensing parameter range. When the exhaust temperature is higher than an exhaust temperature threshold or the exhaust pressure is higher than an exhaust pressure threshold, the opening degree of the electric regulating valve connected to the corresponding plate heat exchanger is controlled to increase to increase the cooling water flow. When the exhaust temperature is lower than the exhaust temperature threshold or the exhaust pressure is lower than the exhaust pressure threshold, the opening degree of the electric regulating valve is controlled to decrease to decrease the cooling water flow. An outlet liquid temperature signal of the plate heat exchanger is obtained, and the opening degree of the electric regulating valve is feedback adjusted according to the outlet liquid temperature.

8. A control device characterized by comprising: The control device comprises a memory, a processor, and a control program of the refrigeration equipment stored on the memory and executable on the processor, and the control program of the refrigeration equipment is configured to implement the control method of any one of claims 1 to 7.

9. A refrigeration appliance characterized in that, The refrigeration equipment comprises: The first refrigeration circuit and the second refrigeration circuit each comprise a compressor, an evaporator, an electronic expansion valve, and a plate heat exchanger, and the first refrigeration circuit and the second refrigeration circuit are independently arranged for parallel or alternating operation; The first heat exchange circuit comprises an outlet liquid pipeline, a return liquid pipeline, and a plurality of cooling water branches connected to the plate heat exchanger, and the plurality of cooling water branches are provided with electric regulating valves for adjusting the cooling water flow through the plate heat exchanger; A plurality of sensors, at least comprising suction temperature sensors, suction pressure sensors, exhaust temperature sensors, exhaust pressure sensors arranged in the first refrigeration circuit and the second refrigeration circuit respectively, and temperature sensors arranged in the first heat exchange circuit for monitoring the outlet liquid temperature of the plate heat exchanger; The control device of claim 8.

10. The refrigeration appliance of claim 9, wherein, The plurality of electric regulating valves comprise a first electric regulating valve and a second electric regulating valve respectively corresponding to the two plate heat exchangers, and a third electric regulating valve arranged on the outlet liquid main pipeline of the first heat exchange circuit; The control device is configured to control the opening degrees of the first electric regulating valve and the second electric regulating valve according to the exhaust pressure or the exhaust temperature, and correct the adjustment results of the electric regulating valves based on the outlet liquid temperature, to realize independent condensing control and hydraulic decoupling of different plate heat exchangers.

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