Refrigerating system based on multi-parameter intelligent regulation and control and control method thereof

Abstract

The invention discloses a refrigerating system based on multi-parameter intelligent regulation and control and a control method thereof, and belongs to the technical field of refrigeration. The system comprises a refrigeration circulation loop composed of a compressor, a condenser, an electronic expansion valve and an evaporator, and a condensation fan. The innovation is that a multi-parameter sensing module is formed by integrating a high-pressure pressure sensor, a low-pressure pressure sensor, a plurality of temperature sensors and a frost thickness sensor and is connected to an intelligent controller. According to the controller, a fuzzy PID algorithm is adopted as a core, and the opening degree of an electronic expansion valve, the rotating speed of a condensate fan and the running state of a compressor are dynamically and cooperatively regulated and controlled by collecting multi-source parameters of a system in real time. Accurate and self-adaptive tracking of the target superheat degree and the target condensing pressure is achieved, the intelligent defrosting and system protection functions are achieved, the problems that a traditional refrigerating system is lagged in regulation and control, poor in collaboration and low in energy efficiency are effectively solved, and the system operation efficiency, stability and reliability are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of refrigeration technology, specifically to a refrigeration system and its control method based on multi-parameter intelligent regulation. Background Technology

[0002] Traditional refrigeration systems, such as refrigerators, air conditioners, and chillers, typically consist of basic components such as a compressor, condenser, throttling device (e.g., capillary tube, thermostatic expansion valve, or electronic expansion valve), and evaporator. Their working principle involves the refrigerant circulating within the system, absorbing and releasing heat through phase change to achieve cooling or heating.

[0003] The existing refrigeration systems have the following main problems: 1. Lag and insufficient precision in regulation: Commonly used throttling devices (such as thermostatic expansion valves) have slow response speeds and limited regulation precision, making them unable to quickly adapt to drastic changes in operating conditions (such as ambient temperature and heat load within the storage facility). This can easily lead to frequent system start-ups and shutdowns or operation at suboptimal operating points, resulting in a low coefficient of performance (COP).

[0004] 2. Poor component coordination: Major energy-consuming components such as compressors, fans, and valves are usually controlled independently, lacking a coordinated strategy based on optimal overall system performance. For example, the condenser fan speed and the electronic expansion valve opening are not linked, making it impossible to maximize energy efficiency under partial load.

[0005] 3. Weak anti-interference ability: For common problems such as evaporator frosting and condenser blockage, traditional systems often rely on simple timing or temperature difference methods to make judgments, which are inaccurate and can easily lead to unnecessary defrosting energy consumption or affect the cooling effect due to untimely defrosting.

[0006] 4. Reliability issues: Liquid slugging (liquid refrigerant entering the compressor) and uncontrolled suction superheat are the main causes of shortened compressor lifespan. Most existing systems rely on a single temperature or pressure sensor for protection, resulting in inadequate protection mechanisms and potential safety hazards.

[0007] Therefore, there is an urgent need for a refrigeration system and control method that can achieve intelligent collaboration and precise control of multiple components, and possess high reliability and high energy efficiency. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a refrigeration system and its control method based on multi-parameter intelligent regulation. This system integrates multiple sensors and intelligent controllers to perform coordinated and optimized control of key components such as the electronic expansion valve, condenser fan, and compressor, thereby achieving efficient, stable, and reliable operation of the system.

[0009] To achieve the above objectives, the technical solution adopted by this invention is: a refrigeration system based on multi-parameter intelligent control, comprising a compressor, a condenser, a throttling device, and an evaporator connected by pipelines, wherein the throttling device is an electronic expansion valve, and a condensing fan is provided on the condenser side; its innovation lies in that the system further includes: Multi-parameter sensing module: including a high-pressure sensor for detecting condenser outlet pressure, a low-pressure sensor for detecting evaporator outlet pressure, a first temperature sensor for detecting compressor suction port temperature, a second temperature sensor for detecting condenser outlet temperature, a third temperature sensor for detecting ambient temperature, and a humidity sensor or image sensor for detecting frost thickness on evaporator surface.

[0010] Intelligent controller: electrically connected to the multi-parameter sensing module, electronic expansion valve, condenser fan, and compressor; the controller has a built-in algorithm program for receiving detection signals from the multi-parameter sensing module, calculating and outputting control signals to the electronic expansion valve, condenser fan, and compressor, executing the following control logic: Electronic expansion valve (EXV) adaptive control: Using the target superheat as the control core, the actual superheat is calculated by combining the evaporator outlet pressure (corresponding to saturation temperature) and compressor suction temperature. Employing a fuzzy PID algorithm, the opening step of the electronic expansion valve is dynamically adjusted based on the deviation between the actual and target superheat and its rate of change, achieving rapid, stable, and precise control with minimal overshoot.

[0011] Condenser fan coordinated speed control: The target condensing pressure is the core control factor. The controller dynamically optimizes the target condensing pressure value based on the system operating load (estimated through compressor operating frequency) and ambient temperature. By comparing the actual condensing pressure detected by the high-pressure sensor with the target value, a PID control algorithm is used to adjust the condenser fan speed, ensuring the system always operates at the optimal condensing pressure.

[0012] Intelligent defrosting judgment and triggering: A combined judgment is made using the "running time method," the "evaporator inlet and outlet air pressure difference method," and the "frost thickness sensor detection method." When any condition reaches a preset threshold, the defrosting program is triggered. During defrosting, the controller shuts down the compressor, electronic expansion valve, and condenser fan, turns on the evaporator-side heater or four-way reversing valve (for heat pump systems), and intelligently determines the defrosting end point based on the evaporator coil temperature or defrosting time.

[0013] System protection and fault-tolerant control: Real-time monitoring of suction superheat. When the suction superheat falls below the safety threshold, a risk of liquid slugging is identified, and the controller immediately reduces the opening of the electronic expansion valve and increases the compressor frequency (if inverter functionality is available). Simultaneously, the system continuously monitors data from various sensors. If a sensor fails, it automatically switches to a redundant control mode based on historical data and other valid sensors to ensure continued safe system operation.

[0014] The innovation of the control method for a refrigeration system based on multi-parameter intelligent regulation described in this invention lies in the following steps: S1: The system powers on, the controller initializes, and reads all sensor data; S2: Calculate the initial target superheat and target condensing pressure based on the ambient temperature and the user-set temperature; S3: Enter the main control loop: a. Acquire real-time data from the multi-parameter sensing module; b. Execute the adaptive control algorithm of the electronic expansion valve and output the EXV opening control signal; c. Execute the condenser fan coordinated speed control algorithm and output the fan PWM speed control signal; d. Execute the intelligent defrosting judgment logic. If the condition is met, interrupt the main loop and jump to the defrosting subroutine; e. Execute system protection logic; if an anomaly occurs, enter security protection mode. S4: Repeat step S3 until the system shuts down.

[0015] With the above structure, the beneficial effects of the present invention are as follows: This invention, through precise control of the electronic expansion valve and coordinated speed regulation of the condenser fan, ensures that the evaporator and condenser always operate under optimal heat exchange conditions, significantly improving the system's annual energy efficiency ratio (APF or SEER).

[0016] This invention employs advanced algorithms such as fuzzy PID, resulting in a fast system response, small overshoot, strong anti-interference capability, good adaptability to operating conditions, and very stable operation.

[0017] This invention employs a multi-parameter fusion intelligent defrosting mechanism to avoid problems such as accidental defrosting and untimely defrosting, thereby reducing energy consumption; the improved liquid hammer protection and sensor fault-tolerant design greatly enhance the system's operational safety and service life.

[0018] This invention enables the refrigeration system to move from "single-point control" to "system collaborative optimization," providing core technical support for smart homes and IoT refrigeration equipment. Attached Figure Description

[0019] Figure 1This is a schematic diagram of the structure of the present invention.

[0020] Explanation of reference numerals in the attached figures: 1. Compressor, 2. Condenser, 3. Electronic expansion valve, 4. Evaporator, 5. Sensor, 6. Condenser fan, 7. Intelligent controller. Detailed Implementation

[0021] The invention will now be further described with reference to the accompanying drawings.

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0023] See Figure 1 The refrigeration system of this invention includes a compressor 1, a condenser 2, an electronic expansion valve 3, and an evaporator 4, forming a refrigeration cycle loop. A high-pressure sensor P_h and a second temperature sensor T2 are installed at the outlet of the condenser 2. A low-pressure sensor P_l and a first temperature sensor T1 are installed at the suction port of the compressor 1. A third temperature sensor T3 (ambient temperature) and a sensor 5 (such as an infrared ranging sensor) for detecting frost thickness are installed near the evaporator 4. A condenser fan 6 is aligned with the condenser 2. The input terminal of the intelligent controller 7 is connected to all sensors, and the output terminal is connected to the control terminals of the electronic expansion valve 3, the condenser fan 6, and the compressor 1. Specifically: I. The main body of the refrigeration system of the present invention is a closed loop following a vapor compression refrigeration cycle, in which the refrigerant circulates. The loop comprises, in order of refrigerant flow direction: Compressor 1: Its exhaust port is connected to the inlet of condenser 2 through an exhaust pipe. Compressor 1 is the power core of the system, used to compress low-temperature, low-pressure refrigerant gas into high-temperature, high-pressure superheated gas.

[0024] Condenser 2: Its inlet receives high-pressure refrigerant gas from compressor 1, and its outlet is connected to a liquid receiver (optional) or electronic expansion valve 3 via a liquid pipe. Condenser 2 is usually a finned tube heat exchanger, and its function is to release heat from the high-temperature, high-pressure refrigerant gas to the ambient air, condensing it into a medium-temperature, high-pressure liquid.

[0025] Electronic expansion valve 3: As a throttling device for the system, its inlet is connected to the outlet of condenser 2, and its outlet is connected to the inlet of evaporator 4 through a pipeline. Electronic expansion valve 3 is a throttling element whose opening can be precisely controlled by an electrical pulse signal. Its core function is to throttle and reduce the pressure of high-pressure liquid refrigerant, making it a low-temperature, low-pressure gas-liquid two-phase mixture.

[0026] Evaporator 4: Its inlet receives the gas-liquid two-phase mixture from the electronic expansion valve 3, and its outlet is connected to the suction port of compressor 1 through a suction pipe. Evaporator 4 is also usually a finned tube heat exchanger, and its function is to allow the low-temperature, low-pressure refrigerant liquid to absorb heat from the space being cooled and evaporate, thereby achieving the purpose of refrigeration.

[0027] Other auxiliary components: Depending on the actual system requirements, the circuit may also include conventional components such as a liquid receiver (for storing excess refrigerant), a gas-liquid separator (installed before the compressor suction port to prevent liquid slugging), a dryer filter (for adsorbing moisture and impurities), and a sight glass (for observing the refrigerant status), which are not shown in the figure.

[0028] The condenser fan 6 is physically aligned with the finned portion of the condenser 2. Its function is to force airflow through the gaps between the fins of the condenser 2, thereby enhancing heat exchange efficiency. Its speed is adjustable.

[0029] II. Arrangement and Connection of Sensing and Detection System The multi-parameter sensing modules are strategically deployed at key nodes of the system to collect multi-source information that determines the system state in real time. High-pressure sensor (P_h): Installed on the outlet pipe of the condenser (2), it is used to detect the pressure on the high-pressure side, i.e., the condensing pressure. This signal is the core parameter for calculating the condensing temperature and controlling the condensing fan (6).

[0030] Low-pressure sensor (P_l): Installed on the pipeline before the suction port of the compressor (1), it is used to detect the pressure on the low-pressure side, i.e., the evaporation pressure. This signal is the core parameter for calculating the evaporation temperature.

[0031] First temperature sensor (T1): Installed at the suction port of compressor (1), used to detect the suction temperature of compressor. This signal is combined with the saturation temperature corresponding to the evaporation pressure detected by P_l to calculate the suction superheat, which is a key parameter for controlling the electronic expansion valve (3) and protecting the compressor.

[0032] The second temperature sensor (T2) is installed on the outlet pipe of the condenser (2), adjacent to the high-pressure sensor (P_h), and is used to detect the temperature of the liquid refrigerant at the condenser outlet. This signal can be combined with the P_h signal to determine the heat exchange performance of the condenser and whether the system is short of refrigerant.

[0033] The third temperature sensor (T3): Installed externally (e.g., at the air inlet of an air conditioner outdoor unit), it is used to detect the ambient temperature. This signal is an important reference input for the system to optimize setpoints such as target condensing pressure.

[0034] Frost thickness sensor 5: Installed between the fins of evaporator 4 or at the air inlet. It can be a non-contact infrared distance sensor that indirectly calculates the frost thickness by measuring changes in distance from the frost-covered fin surface; or it can be a capacitive or resistive humidity sensor that determines the frost condition by detecting changes in air humidity caused by frost. This signal is used for intelligent defrosting detection.

[0035] The signal output terminals of all the above sensors are connected to the corresponding input interfaces (AI - analog input, DI - digital input, or communication interface) of the intelligent controller 7 via wires (analog signal lines or digital buses).

[0036] III. Actuator Connections in the Control System The system's actuators, i.e., the controlled objects, all receive commands from the intelligent controller 7 via wires at their control terminals. Electronic expansion valve 3: Its drive coil is connected to the pulse output port of intelligent controller 7 via a wire. The controller controls the stepper motor of the valve core to rotate by emitting pulse signals of a specific number and frequency, thereby precisely adjusting its opening degree.

[0037] Condenser fan 6: If it is a brushless DC fan (BLDC), its speed control line is connected to the PWM (Pulse Width Modulation) output port or communication interface (such as RS485) of the intelligent controller 7 via a wire. The controller steplessly adjusts its speed by adjusting the duty cycle of the PWM signal or sending speed control commands.

[0038] Compressor 1: If it is a variable frequency compressor, the speed control terminal of its variable frequency drive module is connected to the analog output port (AO) or communication interface of the intelligent controller 7 via a wire. The controller adjusts its operating frequency by outputting analog signals (such as 0-10V) or digital commands. If it is a fixed frequency compressor, it is started and stopped by controlling whether its contactor coil is energized (digital output DO control).

[0039] IV. The Core Role of Intelligent Controllers The intelligent controller 7 is the "brain" of this system. It is typically a microprocessor module (such as a PLC, dedicated PCB board, or microcontroller system) with embedded control algorithms. It continuously executes the following processes: Data acquisition: It reads real-time measurement values ​​from all sensors in a loop through its input interface.

[0040] Data processing and calculation: Based on built-in algorithms (such as fuzzy PID algorithm) and preset logic, the read data is calculated (such as calculating superheat, comparing with target value, and judging defrosting conditions).

[0041] Decision and output: Based on the calculation results, corresponding control commands are generated and sent to each actuator (EXV, fan, compressor) through its output interface.

[0042] Closed-loop feedback: The actions of the actuators change the operating state of the system (such as pressure and temperature). These changes are detected by sensors and fed back to the controller, thus forming one or more closed-loop control systems to achieve continuous optimization and precise control. Example

[0043] Take an inverter air conditioner as an example.

[0044] The controller 7 is set to a target superheat of 5K and a target condensing pressure of 2.5MPa based on the current outdoor ambient temperature of 35℃ and the compressor operating frequency of 50Hz.

[0045] EXV control: T1 detects an intake temperature of 15℃, and P_l detects a low pressure corresponding to a saturation temperature of 10℃. Therefore, the actual superheat is 5K, which is consistent with the target value. The controller maintains the current EXV opening.

[0046] Sudden Loading: The indoor temperature suddenly rises, increasing the heat load. The refrigerant in the evaporator evaporates too quickly, causing the actual superheat to rise instantaneously to 8K. The controller detects the deviation (+3K) and the deviation is increasing. Using a fuzzy PID algorithm, it calculates that the EXV opening needs to be significantly increased to quickly supply more refrigerant, causing the superheat to drop rapidly back to around 5K, thus avoiding efficiency loss due to insufficient refrigerant supply.

[0047] Coordinated control: Simultaneously, due to the increased system load, the condensing heat load also increases, and the actual condensing pressure tends to rise. While increasing the EXV opening, the controller also increases the speed of the condensing fan 6 according to a predetermined algorithm to enhance heat dissipation and stabilize the condensing pressure near the target value of 2.5MPa.

[0048] Defrosting: In heating mode, when the humidity sensor detects that the frost thickness reaches 3mm, or the running time exceeds 45 minutes, and the air pressure difference on both sides of the evaporator increases to a certain threshold, the controller immediately starts the defrosting program.

[0049] The above description is only used to illustrate the technical solution of the present invention and is not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention, as long as they do not depart from the spirit and scope of the technical solution of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A refrigeration system based on multi-parameter intelligent control, comprising a compressor, a condenser, a throttling device, and an evaporator connected by pipelines, wherein a condenser fan is provided on the condenser side, characterized in that: The throttling device is an electronic expansion valve; the system also includes a multi-parameter sensing module and an intelligent controller. The multi-parameter sensing module is used to detect multi-source parameters of the system operation, including at least pressure, temperature and humidity / frost thickness information; The intelligent controller is electrically connected to the multi-parameter sensing module, the electronic expansion valve, the condenser fan, and the compressor. It is configured to receive the detection signal from the multi-parameter sensing module and output control signals to the electronic expansion valve, the condenser fan, and the compressor based on the built-in algorithm program, so as to realize the coordinated intelligent control of the opening degree of the electronic expansion valve, the speed of the condenser fan, and the operating status of the compressor.

2. The refrigeration system based on multi-parameter intelligent control according to claim 1, characterized in that, The multi-parameter sensing module includes: High-pressure sensor used to detect condenser outlet pressure; A low-pressure sensor used to detect the outlet pressure of an evaporator; The first temperature sensor used to detect the compressor's suction temperature; A second temperature sensor used to detect the condenser outlet temperature; A third temperature sensor used to detect ambient temperature; A humidity sensor or image sensor used to detect the thickness of frost on the evaporator surface.

3. The refrigeration system based on multi-parameter intelligent control according to claim 1 or 2, characterized in that: The intelligent controller performs controls including adaptive control of the electronic expansion valve, coordinated speed control of the condenser fan, intelligent defrosting judgment and triggering, and system protection and fault tolerance control.

4. The refrigeration system based on multi-parameter intelligent control according to claim 3, characterized in that: The adaptive control of the electronic expansion valve is based on the target superheat and uses a fuzzy PID algorithm to dynamically adjust the opening of the electronic expansion valve according to the deviation between the actual superheat and the target superheat and its rate of change.

5. The refrigeration system based on multi-parameter intelligent control according to claim 3, characterized in that: The condenser fan coordinated speed control is based on the target condensing pressure. It dynamically optimizes the target condensing pressure value according to the system operating load and ambient temperature, and adjusts the condenser fan speed to make the actual condensing pressure approach the target value.

6. The refrigeration system based on multi-parameter intelligent control according to claim 3, characterized in that: The intelligent defrosting judgment and triggering is based on a combined judgment of the running time, evaporator air pressure difference and frost thickness sensor information to trigger the defrosting program.

7. A control method for a refrigeration system as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Acquire real-time data from the multi-parameter sensing module: S2. Based on the real-time data, execute the electronic expansion valve adaptive control algorithm and output the electronic expansion valve opening control signal; S3. Based on the real-time data, execute the condenser fan coordinated speed control algorithm and output the condenser fan speed control signal; S4. Based on the real-time data, execute the intelligent defrosting judgment logic. If the conditions are met, trigger the defrosting program. S5. Based on the real-time data, execute the system protection logic; if an anomaly occurs, enter the security protection mode. The control method according to claim 7 is characterized in that: the adaptive control algorithm of the electronic expansion valve is a fuzzy PID control algorithm.

8. The control method according to claim 7, characterized in that: The conditions for triggering the defrosting program are that any one of the three parameters, namely "running time", "evaporator air pressure difference" and "detected frost thickness", reaches its preset threshold.

9. The control method according to claim 7, characterized in that: The system protection logic includes real-time monitoring of suction superheat, and when it falls below a safe threshold, it performs operations such as reducing the opening of the electronic expansion valve and increasing the operating frequency of the compressor.

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