Corrosion detection method for condensing tube bundle and heat exchange system of air conditioner

Abstract

According to the invention, the electrochemical complex impedance of the corrosion sensor at different frequencies is adopted to construct an electrochemical disturbance spectrum, so that the overall corrosion condition of the air conditioning system is analyzed. A vector voltammetry is adopted for acquisition and excitation of electric signals, the vector voltammetry is the most common electrochemical complex impedance measurement method at the present stage, impedance value measurement is carried out by utilizing the relation between excitation voltage and response current, the impedance value of a measured object is calculated according to the ratio of voltage to current vectors, the circuit design is simple, and the measurement precision is high. The corrosion sensor electrochemical complex impedance measurement system is composed of a main control chip, an impedance spectrum measurement circuit, an excitation signal generation circuit, a data acquisition circuit and a data storage part.

Description

Technical Field

[0001] The invention relates to the field of corrosion detection, and in particular to a corrosion detection method for an air-conditioning condensing tube bundle and a heat exchange system. Background Art

[0002] Corrosion and leakage of the heat exchange system is one of the problems of air conditioning system operation failure. The air conditioning heat exchange system includes heat exchange pipelines, fins and evaporators, which are in a high-low temperature conversion environment for a long time. It is easy to form thin liquid films and condensation on the surface. Chloride ions, sulfides, etc. in the atmospheric environment are easily dissolved in the surface condensation, accelerating corrosion. At the same time, the cabinet and internal electronic components of the air conditioner external unit are in an atmospheric corrosion environment for a long time. The key parts and materials of the air conditioner are prone to corrosion and aging to varying degrees, which will cause the key parts and materials to fail due to corrosion, seriously affecting the appearance, weather resistance and service life of the air conditioner. Foreign countries attach great importance to the weather resistance of air conditioning products, and as users have increasingly stringent requirements on the corrosion resistance of air conditioners, air conditioning companies are prompted to conduct research on monitoring and detection of air conditioning corrosion processes and corrosion behaviors.

[0003] At present, there are few monitoring and detection technologies for air conditioning corrosion behavior. Most of them use conventional detection methods, such as "CN 112543865B Corrosion environment monitoring method and corrosion environment monitoring system evaluation", which is aimed at the narrow space inside the equipment frame of electrical and electronic devices, and does not require commercial power supply, battery and other power sources, and can identify the type of corrosive gas from short-term to long-term. The corrosion environment monitoring method uses a corrosion sensor to observe the discoloration degree of the metal film through a transparent substrate, and identifies the type of corrosive gas based on the relationship between the discoloration degree of the metal film observed in advance and the type of corrosive gas. The detection precision and accuracy cannot be guaranteed. "CN 11514388 A An electrochemical corrosion sensor and its preparation method" relates to an electrochemical corrosion sensor and its preparation method, the electrochemical corrosion sensor includes a metal substrate, an insulating layer superimposed on the substrate, and an electrode layer superimposed on the insulating layer; the thickness of the insulating layer and the electrode layer is micron-level; the preparation method is to spray UV glue on the surface of the metal substrate by ultrasonic spraying to form an insulating layer, and then spray a nano carbon layer or a nano gold layer on the surface of the insulating layer by ultrasonic spraying to form an electrode layer. Electrochemical corrosion sensors have a simple structure and advanced processing technology, making them suitable for mass production. However, the patent cost is relatively high, and the principle used is galvanic corrosion, which cannot monitor accurate electrochemical signals. Summary of the invention

[0004] The purpose of the present invention is to design a simple and efficient modular sensor, use vector voltammetry to detect the corrosion of the measurement test piece, and then characterize the corrosion condition of the test piece installation part, thereby realizing efficient and accurate corrosion detection of the air conditioning system.

[0005] The present invention adopts vector voltammetry to monitor the corrosion behavior in the air-conditioning condensation and heat exchange environment, uses the relationship between the excitation voltage and the response current to measure the impedance value, and calculates the impedance value of the object under test by the ratio of the voltage and current vectors. The circuit design is simple, suitable for the detection of corrosion behavior in various environments, and has high measurement accuracy.

[0006] A corrosion detection method for air conditioning condenser tube bundle and heat exchange system, using a corrosion sensor electrochemical complex impedance measurement system, the electrochemical complex impedance of the corrosion sensor at different frequencies, to construct an electrochemical perturbation spectrum, so as to analyze the overall corrosion of the air conditioning system; complex impedance is a physical quantity that describes the relationship between the input and output of the system, and it includes a real part and an imaginary part; the real part represents the resistance part of the system, and the imaginary part represents the reactance part of the system;

[0007] The acquisition and excitation of electrical signals are both done by vector voltammetry, which is the most commonly used electrochemical complex impedance measurement method at this stage. It uses the relationship between the excitation voltage and the response current to measure the impedance value, and calculates the impedance value of the measured object by the ratio of the voltage and current vectors. Its circuit design is simple and the measurement accuracy is high. Therefore, this system uses the above method to carry out the overall design of the electrochemical complex impedance measurement system of the corrosion sensor;

[0008] The corrosion sensor electrochemical complex impedance measurement system includes a main control chip, an impedance spectrum measurement circuit, an excitation signal generation circuit, a data acquisition circuit and a data storage part; the specific structure is as shown in the attached Figure 1 As shown;

[0009] The main control chip uses an embedded microcontroller integrated circuit (IC) based on the ARM Cortex-M4 architecture core. It is a 32-bit RISC processor with high code efficiency. It can give full play to the high performance characteristics of the ARM core in the storage space of the usual 8 and 16-bit systems, and adopts a multi-clock source method to solve the problem that the faster the MCU clock, the greater the power consumption and the weaker the anti-electromagnetic interference ability;

[0010] The chip has four 16-bit general-purpose timers, three UART communication ports, two I2C interfaces, two SPI interfaces, one CAN interface and other resources, which provide guarantee for realizing various data communications;

[0011] Each IO can be configured into 8 modes and can be used as an interrupt input port for external interrupts. The interrupt controller supports 19 external interrupt / event requests and has independent trigger and mask settings.

[0012] Direct memory access (DMA) can skip the CPU and directly control the transmission, eliminating the complicated process of preserving and restoring the scene in the interrupt processing mode, effectively improving the efficiency of the CPU;

[0013] The digital-to-analog converter (DAC) can be used in conjunction with the DMA controller and can be configured in 8-bit or 12-bit digital input mode, with separate converters for both channels. In dual DAC mode, both channels can convert the output simultaneously and update synchronously.

[0014] The impedance spectrum measurement circuit includes an impedance matching circuit, an excitation signal generator, a differential amplifier and other signal processing circuits; the main control chip controls the entire corrosion sensor; when working, the main control chip controls the impedance measurement circuit to generate voltage signals of different frequencies, and the generating circuit generates a sinusoidal voltage signal with a frequency of f as the input signal Ui of the system, and the voltage at both ends of the measured object Zx is differentially amplified by a fast operational amplifier, and then a DC bias is added to the differentially amplified signal, and finally the sinusoidal output signal Uo with a DC bias is AD sampled, and the input signal is synchronously sampled at the same time, and the input signal and the output signal are vector-ratioed to obtain the complex impedance of the measured object at a frequency of f;

[0015] The generated signal is applied to the measuring test piece, which uses a comb-tooth electrode. During on-site testing, the packaged comb-tooth electrode is installed on the air-conditioning external unit or other easily corroded parts. At the same time, the present invention has a built-in reference resistor in the sensor, and the generated signal is applied to the reference resistor at the same frequency, so that a preliminary evaluation of the temperature, humidity, etc. of the installation environment can be achieved. The signals generated by the measuring test piece and the reference resistor after disturbance are collected and processed by the data acquisition unit. Before signal acquisition, the low-frequency signal is amplified by the differential amplifier to facilitate acquisition.

[0016] The data acquisition unit is responsible for collecting the analog voltage signal output by the impedance spectrum measurement circuit and converting it into a digital signal for transmission, and recording the measurement results in the data storage unit; the data acquisition unit and the data storage unit are both controlled by the main control chip to convert, store and record data.

[0017] The beneficial effects of the present invention are as follows: the corrosion of the measuring test piece is detected by the vector voltammetry method. The main control chip has high performance characteristics, and the method of multiple clock sources solves the problem that the faster the complex MCU clock is, the greater the power consumption and the weaker the anti-electromagnetic interference ability. The reference resistor is set inside the sensor, and the temperature, humidity, etc. of the environment can be preliminarily evaluated according to the basic parameters of the excitation signal applied to the reference resistor. The stability and accuracy of the signal finally applied to the measuring test piece are guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a complex impedance measurement system for corrosion sensors;

[0019] Figure 2 It is an impedance generation and signal amplification unit;

[0020] Figure 3 This is the schematic diagram of the excitation signal generating circuit;

[0021] Figure 4 This is the schematic diagram of the data acquisition circuit;

[0022] Figure 5 Corrosion monitoring sensor for air conditioning environment. DETAILED DESCRIPTION

[0023] The present invention will be further described below with reference to the embodiments, but is not limited thereto.

[0024] Example

[0025] The impedance spectrum measurement circuit structure of this sensor is as follows: Figure 2 As shown in the figure, it consists of a differential amplifier and an impedance generating unit. Figure 3 As shown, the schematic diagram of the data acquisition circuit is as follows Figure 4 As shown, the air conditioning environment corrosion sensor after installation is as follows Figure 5 shown.

[0026] A corrosion detection method for air conditioning condenser tube bundle and heat exchange system, using a corrosion sensor electrochemical complex impedance measurement system, the electrochemical complex impedance of the corrosion sensor at different frequencies, to construct an electrochemical perturbation spectrum, so as to analyze the overall corrosion of the air conditioning system; complex impedance is a physical quantity that describes the relationship between the input and output of the system, and it includes a real part and an imaginary part; the real part represents the resistance part of the system, and the imaginary part represents the reactance part of the system;

[0027] The acquisition and excitation of electrical signals are both done by vector voltammetry, which is the most commonly used electrochemical complex impedance measurement method at this stage. It uses the relationship between the excitation voltage and the response current to measure the impedance value, and calculates the impedance value of the measured object by the ratio of the voltage and current vectors. Its circuit design is simple and the measurement accuracy is high. Therefore, this system uses the above method to carry out the overall design of the electrochemical complex impedance measurement system of the corrosion sensor;

[0028] The corrosion sensor electrochemical complex impedance measurement system includes a main control chip, an impedance spectrum measurement circuit, an excitation signal generation circuit, a data acquisition circuit and a data storage part; the specific structure is as shown in the attached Figure 1 As shown;

[0029] The main control chip uses an embedded microcontroller integrated circuit (IC) based on the ARM Cortex-M4 architecture core. It is a 32-bit RISC processor with high code efficiency. It can give full play to the high performance characteristics of the ARM core in the storage space of the usual 8 and 16-bit systems, and adopts a multi-clock source method to solve the problem that the faster the MCU clock, the greater the power consumption and the weaker the anti-electromagnetic interference ability;

[0030] The chip has four 16-bit general-purpose timers, three UART communication ports, two I2C interfaces, two SPI interfaces, one CAN interface and other resources, which provide guarantee for realizing various data communications;

[0031] Each IO can be configured into 8 modes and can be used as an interrupt input port for external interrupts. The interrupt controller supports 19 external interrupt / event requests and has independent trigger and mask settings.

[0032] Direct memory access (DMA) can skip the CPU and directly control the transmission, eliminating the complicated process of preserving and restoring the scene in the interrupt processing mode, effectively improving the efficiency of the CPU;

[0033] The digital-to-analog converter (DAC) can be used in conjunction with the DMA controller and can be configured in 8-bit or 12-bit digital input mode, with separate converters for both channels. In dual DAC mode, both channels can convert the output simultaneously and update synchronously.

[0034] The impedance spectrum measurement circuit includes an impedance matching circuit, an excitation signal generator, a differential amplifier and other signal processing circuits; the main control chip controls the entire corrosion sensor; when working, the main control chip controls the impedance measurement circuit to generate voltage signals of different frequencies, and the generating circuit generates a sinusoidal voltage signal with a frequency of f as the input signal Ui of the system, and the voltage at both ends of the measured object Zx is differentially amplified by a fast operational amplifier, and then a DC bias is added to the differentially amplified signal, and finally the sinusoidal output signal Uo with a DC bias is AD sampled, and the input signal is synchronously sampled at the same time, and the input signal and the output signal are vector-ratioed to obtain the complex impedance of the measured object at a frequency of f;

[0035] The generated signal is applied to the measuring test piece, which uses a comb-tooth electrode. During on-site testing, the packaged comb-tooth electrode is installed on the air-conditioning external unit or other easily corroded parts. At the same time, the present invention has a built-in reference resistor in the sensor, and the generated signal is applied to the reference resistor at the same frequency, so that a preliminary evaluation of the temperature, humidity, etc. of the installation environment can be achieved. The signals generated by the measuring test piece and the reference resistor after disturbance are collected and processed by the data acquisition unit. Before signal acquisition, the low-frequency signal is amplified by the differential amplifier to facilitate acquisition.

[0036] The data acquisition unit is responsible for collecting the analog voltage signal output by the impedance spectrum measurement circuit and converting it into a digital signal for transmission, and recording the measurement results in the data storage unit; the data acquisition unit and the data storage unit are both controlled by the main control chip to convert, store and record data.

Claims

1. A method for detecting corrosion of air conditioning condenser tube bundles and heat exchange systems, characterized in that: The corrosion sensor electrochemical complex impedance measurement system is used. The electrochemical complex impedance of the corrosion sensor at different frequencies is used to construct an electrochemical perturbation spectrum to analyze the overall corrosion of the air-conditioning system. Complex impedance is a physical quantity that describes the relationship between the input and output of the system. It includes a real part and an imaginary part. The real part represents the resistance part of the system, and the imaginary part represents the reactance part of the system. The acquisition and excitation of electrical signals both use vector voltammetry, which is currently the most commonly used electrochemical complex impedance measurement method. It uses the relationship between excitation voltage and response current to measure impedance value, and calculates the impedance value of the object being measured by the ratio of voltage and current vectors.

2. The method for detecting corrosion of air conditioning condenser tube bundle and heat exchange system according to claim 1, characterized in that: The corrosion sensor electrochemical complex impedance measurement system comprises a main control chip, an impedance spectrum measurement circuit, an excitation signal generation circuit, a data acquisition circuit and a data storage part; The main control chip uses an embedded microcontroller integrated circuit (IC) based on the ARM Cortex-M4 architecture core. It is a 32-bit RISC processor with high code efficiency. It can give full play to the high performance characteristics of the ARM core in the storage space of the usual 8 and 16-bit systems, and adopts a multi-clock source method to solve the problem that the faster the MCU clock, the greater the power consumption and the weaker the anti-electromagnetic interference ability; The chip has four 16-bit general-purpose timers, three UART communication ports, two I2C interfaces, two SPI interfaces, one CAN interface and other resources, which provide guarantee for realizing various data communications; Each IO can be configured into 8 modes and can be used as an interrupt input port for external interrupts. The interrupt controller supports 19 external interrupt / event requests and has independent trigger and mask settings. Direct memory access (DMA) can skip the CPU and directly control the transmission, eliminating the complicated process of preserving and restoring the scene in the interrupt processing mode, effectively improving the efficiency of the CPU; The digital-to-analog converter (DAC) can be used in conjunction with the DMA controller and can be configured in 8-bit or 12-bit digital input mode with separate converters for both channels; in dual DAC mode, both channels can convert the outputs simultaneously and update synchronously.

3. The corrosion detection method for air conditioning condenser tube bundle and heat exchange system according to claim 1 is characterized in that: The impedance spectrum measurement circuit includes an impedance matching circuit, an excitation signal generator, a differential amplifier and other signal processing circuits; the main control chip controls the entire corrosion sensor; when working, the main control chip controls the impedance measurement circuit to generate voltage signals of different frequencies, and the generating circuit generates a sinusoidal voltage signal with a frequency of f as the input signal Uo of the system, and the voltage at both ends of the measured object Zx is differentially amplified by a fast operational amplifier, and then a DC bias is added to the differentially amplified signal, and finally the sinusoidal output signal Uo with a DC bias is AD sampled, and the input signal is synchronously sampled at the same time, and the input signal and the output signal are vector-ratioed to obtain the complex impedance of the measured object at a frequency of f; The generated signal is applied to the measuring test piece, which uses a comb-tooth electrode. During on-site testing, the packaged comb-tooth electrode is installed on the air-conditioning external unit or other easily corroded parts. At the same time, the present invention has a built-in reference resistor in the sensor, and the generated signal is applied to the reference resistor at the same frequency, so that a preliminary evaluation of the temperature, humidity, etc. of the installation environment can be achieved. The signals generated by the measuring test piece and the reference resistor after disturbance are collected and processed by the data acquisition unit. Before signal acquisition, the low-frequency signal is amplified by the differential amplifier to facilitate acquisition. The data acquisition unit is responsible for collecting the analog voltage signal output by the impedance spectrum measurement circuit and converting it into a digital signal for transmission, and recording the measurement results in the data storage unit; the data acquisition unit and the data storage unit are both controlled by the main control chip to convert, store and record data.

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