Feed-forward cooling control method and system for centrifugal compressor and centrifugal compressor

Abstract

The invention discloses a feed-forward cooling control method and system for a centrifugal compressor and the centrifugal compressor. According to the method, the flow of a cooling medium can be accurately and adaptively adjusted in advance based on the on-way temperature rise characteristic of airflow in the running process of the centrifugal compressor; the wall temperature change in the operation process of the centrifugal compressor is predicted in advance through a dynamic feedforward mechanism, advanced adjustment and active temperature control are achieved, the defect of lag adjustment of traditional feedback control is overcome, model errors and disturbance are eliminated in combination with feedback correction, the wall temperature of a diffuser and a volute can be stably controlled within a target range, the control precision is improved, and the control efficiency is improved. Local overheating or supercooling is effectively avoided; and meanwhile, the wall surfaces of the diffuser and the volute are cooled, the temperature of the wall surfaces is controlled, thermal stress and thermal fatigue damage to the wall surfaces of the diffuser and the volute are reduced, and the service life of equipment is prolonged.

Description

Technical Field

[0001] This invention relates to the field of gas cooling technology for centrifugal compressors, specifically to a feedforward cooling control method, system, and centrifugal compressor for centrifugal compressors. Background Technology

[0002] In centrifugal air compressors operating under high-pressure, multi-stage compression conditions, gas is compressed by the impeller and then enters the diffuser and volute to complete diffusion and collection. During this process, the gas's internal energy and temperature increase significantly. This not only increases the compression work of subsequent stages and reduces the overall isothermal compression efficiency, but also causes thermal deformation of components due to the increased temperature of the flow channel walls, affecting flow field matching and pressure stability. Furthermore, for high-power magnetic levitation compressors, due to their large rotor length, the increased elongation of the rotor after heating leads to significant changes in axial bearing clearance, making control difficult. The transfer of aerodynamic heat to the rotor exacerbates this situation.

[0003] Meanwhile, existing cooling control methods mostly employ passive cooling, constant flow cooling, or simple feedback control based solely on measured temperature. Their cooling logic relies on conventional sensor temperature control, which has significant drawbacks: Firstly, simple feedback control is a delayed control that adjusts only after the temperature exceeds the limit, failing to anticipate dynamic changes in airflow temperature rise along the flow path and easily leading to localized overheating or overcooling. Secondly, existing control methods do not incorporate the temperature rise characteristics of the gas from the impeller outlet through the diffuser to the volute, resulting in low cooling accuracy, high energy consumption, and an inability to adapt to temperature rise fluctuations under varying compressor operating conditions (changes in speed, flow rate, and pressure ratio). Summary of the Invention

[0004] Technical objective: To address the shortcomings of existing centrifugal compressors in gas cooling, this invention discloses a feedforward cooling control method, system, and centrifugal compressor for centrifugal compressors.

[0005] Technical solution: To achieve the above technical objectives, the present invention adopts the following technical solution: A method for feedforward cooling control of a centrifugal compressor, comprising the following steps: S01. Establish a gas temperature rise mechanism model and a shell wall thermal dynamics model based on the gas flow path of the centrifugal compressor. Obtain the temperature change data of the gas in each flow stage through the gas temperature rise mechanism model, and obtain the heat exchange data between the gas and the shell wall corresponding to the flow path through the shell wall thermal dynamics model. S02. Based on the temperature change data and heat transfer data during the gas flow process of the centrifugal compressor, the corresponding shell wall temperature is predicted, and the predicted wall temperature is obtained. S03. Using the predicted wall temperature as the benchmark for feedforward cooling control, calculate the feedforward cooling control quantity to cool the shell wall.

[0006] Preferably, when cooling the shell wall, the present invention corrects the feedforward cooling control quantity based on the deviation between the real-time collected shell wall temperature and the target wall temperature, and determines the cooling medium flow rate required for the final cooling of the shell wall.

[0007] Preferably, when establishing the gas temperature rise mechanism model and the shell wall thermal dynamics model, the present invention uses the real-time operating conditions of the centrifugal compressor as input, and establishes the model in segments according to the gas flow path of the impeller outlet, diffuser, and volute, based on the changes in gas flow state; and performs feedforward cooling control separately in the segmented regions.

[0008] Preferably, the temperature rise mechanism model of the present invention includes an impeller outlet total temperature mechanism model, a diffuser aerodynamic temperature rise mechanism model, and a volute heat dissipation temperature rise mechanism model. The impeller outlet total temperature mechanism model is used to calculate the total outlet temperature of the airflow after the impeller has done work. ,in, Total temperature at the compressor inlet; Impeller isentropic efficiency; Gas adiabatic index; Impeller pressure ratio; A diffuser aerodynamic temperature rise mechanism model is used to calculate the total temperature of the diffuser outlet gas flow. , ,in, Diffuser efficiency; : Diffuser inlet airflow velocity; : Diffuser outlet airflow velocity; Specific heat capacity of a gas at constant pressure; The volute heat dissipation and temperature rise mechanism model is used to calculate the airflow temperature inside the volute. : , : Volute loss coefficient.

[0009] Preferably, the housing of the present invention is predicted by a thermal dynamic model of the housing wall. The corresponding shell wall temperature after a certain time. , This represents the amount of heat generated by the airflow on the wall. This represents the heat dissipation from the casing wall to the cooling medium; where, : Diffuser / volute wall temperature at the current time (time t); Predicted duration; Heat capacity of diffuser / volute wall; The heat transfer coefficient between the airflow and the wall; : The heat exchange area between the airflow and the wall; Temperature of the mainstream airflow inside the volute; The heat transfer coefficient between the wall and the cooling medium; The heat exchange area between the wall surface and the cooling medium; : Cooling medium inlet temperature.

[0010] Preferably, the present invention is based on predicted wall temperature With target wall temperature The deviation is used to calculate the feedforward cooling control quantity. ,in, : Feedforward control proportional coefficient; : Feedforward control integral coefficient; Target wall temperature of diffuser / volute.

[0011] Preferably, the present invention is based on real-time collected wall temperature. With target wall temperature The deviation is used to calculate the feedback cooling correction amount. , : Feedback control proportional coefficient; : Integral coefficient for feedback control; Real-time measured wall temperature; Total control of cooling capacity .

[0012] The present invention discloses a feedforward cooling control system for a centrifugal compressor. Using the above-mentioned method, the system includes a cooling module for providing cooling medium to the centrifugal compressor according to cooling requirements, a temperature sensing module for detecting temperature data of the centrifugal compressor, and a control module for controlling the flow rate of the cooling medium according to the operating conditions of the centrifugal compressor. The control module pre-calculates the feedforward cooling control quantity required for the cooling of the centrifugal compressor based on the operating conditions of the centrifugal compressor, and the cooling module performs the cooling operation.

[0013] Preferably, after calculating the feedforward cooling control quantity, the present invention calculates the feedback cooling correction quantity based on the difference between the current centrifugal compressor casing wall temperature and the corresponding target temperature, and calculates the total control transmission cooling quantity by superimposing the feedforward cooling control quantity and the feedback cooling correction quantity, which is used as the final cooling medium flow rate.

[0014] This invention discloses a centrifugal compressor using the aforementioned system, comprising an integrally formed diffuser and a volute body. The inlet end of the diffuser is connected to the compressed gas outlet of the compressor. A first cooling channel is uniformly formed inside the wall of the diffuser, and a second cooling channel with an annular design is formed inside the inner wall of the volute body. The first and second cooling channels are connected to a cooling module to form a closed-loop cooling circuit. Temperature sensors for real-time detection of wall temperature are provided on the inner walls of both the diffuser and the volute body.

[0015] Beneficial Effects: The centrifugal compressor feedforward cooling control method, system, and centrifugal compressor disclosed in this invention have the following beneficial effects: 1. This invention predicts the wall temperature changes during the operation of a centrifugal compressor in advance through a dynamic feedforward mechanism, achieving "advance adjustment and active temperature control". It overcomes the shortcomings of "lagging adjustment" in traditional feedback control. Combined with feedback correction to eliminate model errors and disturbances, it enables the diffuser and volute wall temperatures to be stably controlled within the target range, improving control accuracy and effectively avoiding local overheating or overcooling.

[0016] 2. This invention performs airflow cooling within the diffuser and volute body. Compared to interstage cooling alone, this method can reduce the transfer of aerodynamic heat to the rotor by lowering the gas temperature, thereby reducing the thermal elongation of the centrifugal compressor rotor and improving compressor stability.

[0017] 3. The feedforward cooling control method of the present invention can respond in real time to changes in the operating conditions of the centrifugal compressor, dynamically adjust the prediction accuracy and cooling adjustment amount, and adapt to temperature rise fluctuations under varying operating conditions; at the same time, it can adjust the cooling medium flow rate as needed, avoid energy waste caused by constant flow cooling, reduce the energy consumption of the cooling system, reduce losses, and improve flow field stability.

[0018] 4. The centrifugal compressor of the present invention designs the diffuser and the volute body into an integral structure, eliminating the connection gap of the split structure, reducing airflow leakage and impact loss, and ensuring the continuity of airflow by smooth transition of the flow channel, improving the diffusion and collection efficiency, while avoiding flow field distortion caused by wall thermal deformation and improving pressure uniformity.

[0019] 5. This invention uses flow channels opened in the wall to cool the corresponding shell wall, which can simplify the cooling structure design of the centrifugal compressor, effectively reduce the volume of the interstage heat exchanger, simplify the overall installation layout, reduce the size and weight of the equipment, and reduce the cost of the cabinet.

[0020] 6. This invention reduces thermal stress and thermal fatigue damage to the diffuser and volute main body wall through precise temperature control, thus extending the service life of the structure. At the same time, the limiting constraint of the safety protection module avoids frequent actuator operation and cooling system abnormalities, thereby improving the overall operational stability and reliability of the compressor. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0022] Figure 1 This is a schematic diagram of the centrifugal compressor structure of the present invention; Among them, 1-diffuser, 2-volute body, 3-first cooling channel, 4-second cooling channel. Detailed Implementation

[0023] Reference will now be made in detail to embodiments of the present disclosure, one or more of which are set forth herein. Each embodiment and example is provided by way of explanation of the apparatus, composition, and materials of the present disclosure, and not by way of limitation. Rather, the following description provides convenient illustrations for implementing exemplary embodiments of the present disclosure. Indeed, it will be apparent to those skilled in the art that various modifications and variations can be made to the teachings of the present disclosure without departing from the scope or spirit of the present disclosure.

[0024] This invention discloses a feedforward cooling control method for a centrifugal compressor, characterized by comprising the following steps: S01. Establish a gas temperature rise mechanism model and a shell wall thermal dynamics model based on the gas flow path of the centrifugal compressor. Obtain the temperature change data of the gas in each flow stage through the gas temperature rise mechanism model, and obtain the heat exchange data between the gas and the shell wall corresponding to the flow path through the shell wall thermal dynamics model.

[0025] Inside a centrifugal compressor, gas is compressed by the impeller and then enters the diffuser. The diffuser slows down and diffuses the gas, converting the kinetic energy of the airflow into pressure energy. At the same time, flow losses are converted into heat energy, causing the airflow temperature to rise. The gas then enters the volute. Inside the volute, due to the collecting effect of the volute, eddies, tongue impacts, secondary flows, and friction losses are generated. These losses are converted into heat energy, causing the airflow temperature to rise further.

[0026] To enable targeted and controllable cooling control at different stages of airflow temperature change, this invention establishes a gas temperature rise mechanism model and a shell wall thermal dynamics model. The real-time operating conditions of the centrifugal compressor are used as input, and the airflow paths of the impeller outlet, diffuser, and volute are used to establish the model segmented according to changes in gas flow state. Feedforward cooling control is performed separately in each segmented region. The airflow process is divided into three parts: the gas temperature rise mechanism model includes the impeller outlet total temperature mechanism model, the diffuser aerodynamic temperature rise mechanism model, and the volute heat dissipation temperature rise mechanism model. The impeller outlet total temperature mechanism model is used to calculate the total outlet temperature of the airflow after the impeller has done work. ,in, The compressor inlet total temperature (°C) can be collected in real time by a temperature sensor; The isentropic efficiency (dimensionless) of the impeller is obtained through experiments or CFD calibration. The gas adiabatic index (dimensionless) is determined based on the characteristics of the compressed medium. Impeller pressure ratio (dimensionless) is equal to the ratio of the total pressure at the impeller outlet to the total pressure at the impeller inlet. It is calculated or estimated by collecting data in real time.

[0027] A diffuser aerodynamic temperature rise mechanism model is used to calculate the total temperature of the diffuser outlet gas flow. , A temperature rise model within the diffuser is established based on the conservation of gas energy, wherein... Diffuser efficiency (dimensionless), obtained through testing or CFD calibration; The diffuser inlet airflow velocity (m / s) is calculated based on the inlet cross-sectional area and mass flow rate. The diffuser outlet airflow velocity (m / s) is calculated based on the outlet cross-sectional area and mass flow rate. Specific heat capacity of gas at constant pressure (J / (kg·℃)) is determined based on the characteristics of the compression medium.

[0028] The volute heat dissipation and temperature rise mechanism model is used to calculate the airflow temperature inside the volute: ； To establish the temperature rise caused by gas flow loss inside the volute using the loss factor method; : Volute loss coefficient (dimensionless), obtained through design experience or CFD calibration. Diffuser outlet airflow velocity (m / s).

[0029] S02. Based on the temperature change data and heat exchange data during the gas flow process of the centrifugal compressor, the corresponding shell wall temperature is predicted, and the predicted wall temperature is obtained.

[0030] The thermal dynamic model prediction of the shell wall of this invention The corresponding shell wall temperature after a certain time. , This represents the amount of heat generated by the airflow on the wall. This refers to the amount of heat dissipated from the casing wall to the cooling medium.

[0031] in: The diffuser / volute wall temperature (°C) at the current time (time t) is acquired in real time. Prediction duration (s) is also the time interval for compressor cooling control. It is generally set according to the compressor response characteristics, preferably 0.1~1s. Heat capacity of diffuser / volute wall (J / ℃), calculated based on structural dimensions and material properties; The heat transfer coefficient between the airflow and the wall (W / (m²·℃)) is obtained through offline testing or CFD calibration. The heat exchange area (m²) between the airflow and the wall is calculated based on the dimensions of the diffuser and volute structure. Temperature of the main airflow inside the volute (°C); The heat transfer coefficient between the wall and the cooling medium (W / (m²·℃)) is determined based on the cooling channel structure and the characteristics of the cooling medium, and can be obtained through simulation experiments. The heat exchange area (m²) between the wall and the cooling medium is calculated based on the cooling channel layout dimensions. : Cooling medium inlet temperature (°C), acquired in real time by a temperature sensor.

[0032] The final output of the shell wall thermal dynamics model is the predicted wall temperature at time Δt. Its expression can be simplified to:

[0033] Gas mass flow rate (kg / s) Compressor speed (r / min) The total pressure ratio of the compressor is denoted as , and all parameters are real-time collected operating conditions. The predicted wall temperature can be directly correlated with the compressor's operating conditions.

[0034] S03. Using the predicted wall temperature as the benchmark for feedforward cooling control, calculate the feedforward cooling control quantity to cool the shell wall.

[0035] This invention is based on predicted wall temperature With target wall temperature The deviation is used to calculate the feedforward cooling control quantity. ,in, The feedforward control proportional coefficient (dimensionless) is obtained through offline tuning. The feedforward control integral coefficient (1 / s) is obtained through offline tuning. Target wall temperature of diffuser / volute (°C), set according to compressor design requirements.

[0036] To avoid the inability to accurately control cooling by relying solely on predicted wall temperature for pre-cooling due to model errors or external disturbances (such as fluctuations in cooling medium temperature or sudden changes in airflow conditions), this invention, when cooling the shell wall, uses the deviation between the real-time collected shell wall temperature and the target wall temperature to correct the feedforward cooling control quantity, thereby determining the cooling medium flow rate required for the final cooling of the shell wall.

[0037] Specifically, this invention is based on real-time collected wall temperature data. With target wall temperature The deviation is used to calculate the feedback cooling correction amount. , The feedback control proportional coefficient (dimensionless) is obtained through offline tuning. The integral coefficient of the feedback control (1 / s) is obtained through offline tuning. Real-time measured wall temperature (°C) is collected by a temperature sensor located at a corresponding position inside the casing.

[0038] The total controlled transmission cooling capacity is obtained by combining the two. .

[0039] Finally, the cooling medium is controlled to cool the corresponding wall surface by transmitting the cooling capacity through the cooler according to the overall control.

[0040] To ensure the safe operation of the compressor and the stability of the cooling system, this invention imposes a safety limit constraint on the total controlled cooling capacity: Minimum flow constraint: To prevent insufficient cooling flow from causing overheating of the diffuser and volute, which can exacerbate thermal fatigue and material failure. Maximum flow constraint: This is to prevent excessive cooling flow from causing the wall surface to become too cold, the cooling medium to condense, and the aerodynamic efficiency to decrease and energy consumption to increase. Rate of change limit constraint: This avoids frequent actuator operation and extends the service life of the equipment.

[0041] in, , , All parameters are preset based on the compressor design parameters and the performance of the cooling system.

[0042] This invention also discloses a feedforward cooling control system for a centrifugal compressor. The system uses the aforementioned method to control the cooling of the centrifugal compressor. It includes a cooling module for providing cooling medium to the centrifugal compressor according to cooling requirements, a temperature sensing module for detecting temperature data of the centrifugal compressor, and a control module for controlling the flow rate of the cooling medium according to the operating conditions of the centrifugal compressor. The control module pre-calculates the feedforward cooling control quantity required for the cooling of the centrifugal compressor based on its operating conditions, and the cooling module executes the cooling operation. Preferably, the cooling module is a device capable of accurately controlling the delivery flow rate, such as a cooling pump or an electromagnetic flow regulating valve.

[0043] After calculating the feedforward cooling control quantity, this invention calculates the feedback cooling correction quantity based on the difference between the current centrifugal compressor casing wall temperature and the corresponding target temperature. The total control transmission cooling quantity is calculated by superimposing the feedforward cooling control quantity and the feedback cooling correction quantity, which is used as the final cooling medium flow rate to ensure the accuracy of cooling control.

[0044] like Figure 1 As shown, this invention discloses a centrifugal compressor using the above-described system, comprising an integrally formed diffuser 1 and a volute body 2. The inlet end of the diffuser 1 is connected to the compressed gas outlet of the compressor. A first cooling channel 3 is uniformly formed inside the wall of the diffuser 1, and a second cooling channel 4 with an annular design is formed inside the inner wall of the volute body 2. The first cooling channel 3 and the second cooling channel 4 are connected to a cooling module to form a closed-loop cooling circuit. Temperature sensors for real-time detection of wall temperature are provided on the inner walls of both the diffuser 1 and the volute body 2.

[0045] The diffuser 1 and the volute body 2 are integrally cast. The flow channel outlet of the diffuser 1 and the spiral flow channel inlet of the volute body 2 are smoothly and tangentially transitioned, eliminating the connection gap of the split structure, reducing airflow leakage and impact loss, and ensuring the continuity of the flow field. The cooling channels are all made of stainless steel and are inlaid and cast, with a wall thickness of not less than 5mm to ensure structural strength.

[0046] The first cooling channel 3 adopts a comb-shaped layout that matches the shape of the diffuser 1, covering the entire channel area from the diffuser section inlet to the connection with the volute body, and the end of the channel extends to the outside to connect with the cooling medium flow pipeline of the cooling module to form a loop.

[0047] The second cooling channel 4 is an annular channel, and the inlet and outlet of the annular channel can be connected to the inlet and outlet of the first cooling channel 3, respectively.

[0048] The cooling module can be a conventional interstage cooler, connected to the corresponding cooling channel through pipelines. A cooling pump provides power to drive the cooling medium to circulate. An electromagnetic flow regulating valve is installed at the inlet of the corresponding cooling channel to regulate the incoming cooling cutoff flow rate. A pressure regulating valve is installed at the outlet of the channel to ensure the smooth flow of the cooling medium in the corresponding cooling channel and avoid problems such as air blockage and uneven flow in the cooling channel.

[0049] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for controlling feedforward cooling of a centrifugal compressor, characterized in that, Including the following steps: S01. Establish a gas temperature rise mechanism model and a shell wall thermal dynamics model based on the gas flow path of the centrifugal compressor. Obtain the temperature change data of the gas in each flow stage through the gas temperature rise mechanism model, and obtain the heat exchange data between the gas and the shell wall corresponding to the flow path through the shell wall thermal dynamics model. S02. Based on the temperature change data and heat transfer data during the gas flow process of the centrifugal compressor, the corresponding shell wall temperature is predicted, and the predicted wall temperature is obtained. S03. Using the predicted wall temperature as the benchmark for feedforward cooling control, calculate the feedforward cooling control quantity to cool the shell wall.

2. The centrifugal compressor feedforward cooling control method according to claim 1, characterized in that, When cooling the shell wall, the feedforward cooling control quantity is corrected based on the deviation between the real-time collected shell wall temperature and the target wall temperature to determine the cooling medium flow rate required for the final cooling of the shell wall.

3. The centrifugal compressor feedforward cooling control method according to claim 2, characterized in that, When establishing the gas temperature rise mechanism model and the shell wall thermal dynamics model, the real-time operating conditions of the centrifugal compressor are used as input, and the airflow paths of the impeller outlet, diffuser, and volute are used to establish the model in segments according to the changes in gas flow state; feedforward cooling control is performed separately in each segmented region.

4. The centrifugal compressor feedforward cooling control method according to claim 3, characterized in that, The temperature rise mechanism model includes the impeller outlet total temperature mechanism model, the diffuser aerodynamic temperature rise mechanism model, and the volute heat dissipation temperature rise mechanism model. The impeller outlet total temperature mechanism model is used to calculate the total outlet temperature of the airflow after the impeller has done work. ,in, Total temperature at the compressor inlet; Impeller isentropic efficiency; Gas adiabatic index; Impeller pressure ratio; A diffuser aerodynamic temperature rise mechanism model is used to calculate the total temperature of the diffuser outlet gas flow. , ,in, Diffuser efficiency; : Diffuser inlet airflow velocity; : Diffuser outlet airflow velocity; Specific heat capacity of a gas at constant pressure; The volute heat dissipation and temperature rise mechanism model is used to calculate the airflow temperature inside the volute. : , : Volute loss coefficient.

5. The centrifugal compressor feedforward cooling control method according to claim 3, characterized in that, Predicting based on shell wall thermal dynamics model The corresponding shell wall temperature after a certain time. , This represents the amount of heat generated by the airflow on the wall. This represents the heat dissipation from the casing wall to the cooling medium; where, : The current diffuser / volute wall temperature at time t; Predicted duration; Heat capacity of diffuser / volute wall; : The heat transfer coefficient between the airflow and the wall; : The heat exchange area between the airflow and the wall; Temperature of the mainstream airflow inside the volute; The heat transfer coefficient between the wall and the cooling medium; : Heat exchange area between the wall and the cooling medium; : Inlet temperature of the cooling medium.

6. The centrifugal compressor feedforward cooling control method according to claim 5, characterized in that, Based on predicted wall temperature With target wall temperature The deviation is used to calculate the feedforward cooling control quantity. ,in, : Feedforward control proportional coefficient; : Feedforward control integral coefficient; Target wall temperature of diffuser / volute.

7. The centrifugal compressor feedforward cooling control method according to claim 6, characterized in that, Based on real-time wall temperature With target wall temperature The deviation is used to calculate the feedback cooling correction amount. , : Feedback control proportional coefficient; : Integral coefficient for feedback control; Real-time measured wall temperature; Total control of cooling capacity .

8. A centrifugal compressor feedforward cooling control system, using the method described in any one of claims 1-7, characterized in that, It includes a cooling module for providing cooling medium to the centrifugal compressor according to cooling requirements, a temperature sensing module for detecting temperature data of the centrifugal compressor, and a control module for controlling the flow rate of cooling medium according to the operating conditions of the centrifugal compressor. The control module pre-calculates the feedforward cooling control quantity required for cooling the centrifugal compressor based on the operating conditions of the centrifugal compressor, and the cooling module performs the cooling operation.

9. A centrifugal compressor feedforward cooling control system according to claim 8, characterized in that, After calculating the feedforward cooling control quantity, the feedback cooling correction quantity is calculated based on the difference between the current centrifugal compressor casing wall temperature and the corresponding target temperature. The total control transmission cooling quantity is calculated by superimposing the feedforward cooling control quantity and the feedback cooling correction quantity, which is used as the final cooling medium flow rate.

10. A centrifugal compressor using the system of claim 8 or 9, characterized in that, The diffuser (1) and the volute body (2) are integrally molded. The inlet end of the diffuser (1) is connected to the compressed gas outlet of the compressor. A first cooling channel (3) is uniformly opened inside the wall of the diffuser (1). A second cooling channel (4) with an annular design is opened inside the inner wall of the volute body (2). The first cooling channel (3) and the second cooling channel (4) are connected to the cooling module to form a closed-loop cooling circuit. Temperature sensors for real-time detection of wall temperature are provided on the inner walls of both the diffuser (1) and the volute body (2).

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