Heat exchanger pressure drop automatic test system and test method

Abstract

The application discloses a heat exchanger pressure drop automatic testing system and testing method. The system includes a double-range parallel gas supply module, a pressure acquisition module, a parameter storage module and a controller. The double-range parallel gas supply module is provided with a main pipeline and parallel first and second branch pipes, and the opening and closing are controlled by a pneumatic ball valve, and the automatic switching of large and small range test modes is realized in combination with two-stage flow meters; the pressure acquisition module includes a gauge pressure sensor and an absolute pressure sensor, and is used for acquiring pipeline pressure and performing real-time compensation of environmental atmospheric pressure; the parameter storage module supports one-key loading of test parameters of multiple models of heat exchangers; the controller controls flow closed-loop regulation, synchronously acquires gas pressure data to calculate compensated pressure drop values, and fits a measured pressure drop curve based on multi-point pressure drop data to perform performance qualification determination in a full flow interval. The application can meet full-range automatic testing requirements on a single platform, eliminates environmental and human errors, and significantly improves testing accuracy.

Description

Technical Field

[0002] This application relates to the field of aircraft heat exchanger testing, and in particular to an automatic testing system and method for heat exchanger pressure drop. Background Technology

[0004] Heat exchangers are critical thermal management components in fields such as aero-engines and aircraft environmental control systems. During the manufacturing and maintenance of heat exchangers, pressure drop performance testing is a core testing step to evaluate whether their internal flow channels meet design requirements. Pressure drop testing typically uses compressed air as the test medium, measuring the pressure difference between the heat exchanger inlet and outlet under different flow conditions to characterize its flow resistance characteristics.

[0005] Existing heat exchanger pressure drop testing devices typically employ a single-pipeline structure, where a flow meter and a proportional control valve are connected in series on a single gas supply line. The flow rate is controlled by the control valve, and the flow meter measures the flow rate. However, different heat exchanger models have significantly different operating flow rates. For example, the test flow rate for some small heat exchangers is only 0.1–0.5 t / h, while the test flow rate for large heat exchangers can reach 5–10 t / h. Single-range flow meters present an inherent accuracy dilemma when facing such wide-range flow rate testing requirements: if a large-range flow meter is selected to cover high-flow-rate conditions, the flow meter will operate at the lower end of its range under low-flow-rate conditions, significantly increasing measurement errors and failing to meet the required testing accuracy; conversely, if a small-range flow meter is selected to ensure accuracy at low flow rates, it cannot meet the testing requirements for high-flow-rate conditions. Current technologies typically address this by configuring multiple testing devices with different flow rates, or by having operators manually change the flow meter before testing. However, the former requires a large footprint and is costly, while the latter is cumbersome to operate and prone to introducing uncertainties such as pipeline leaks during replacement.

[0006] Furthermore, existing heat exchanger pressure drop testing devices typically use gauge pressure sensors to measure the pressure at the inlet of the heat exchanger under test during pressure drop calculations, assuming the outlet pressure is atmospheric pressure and directly using the inlet gauge pressure value in the calculations. However, in actual testing environments, atmospheric pressure is not constant. Influenced by weather changes, altitude differences, and airflow conditions within the plant, ambient atmospheric pressure can fluctuate by hundreds of Pascals within a single day. For high-precision pressure drop testing of aerospace heat exchangers, the systematic deviation caused by such atmospheric pressure fluctuations cannot be ignored. In existing technologies, some testing devices are corrected by manually querying meteorological data and manually inputting atmospheric pressure values. However, this method neither reflects real-time changes in atmospheric pressure during the test nor mitigates the risk of human error.

[0007] On the other hand, there are numerous heat exchanger models in the aviation maintenance field. The coefficients, exponents, inlet cross-sectional areas, and outlet cross-sectional areas involved in the pressure drop calculation formulas differ between models, and the required test flow ranges and compatible flow branches also vary. In existing testing equipment, when the model of the heat exchanger under test changes, operators need to manually complete a series of configuration operations, including but not limited to: reviewing process documents to confirm calculation parameters, manually selecting a suitable flow test pipeline, manually selecting a suitable pressure sensor channel, and manually modifying relevant parameters and upper and lower limit thresholds in the testing software. This is not only time-consuming and labor-intensive, but also highly susceptible to human error in inputting incorrect parameters, leading to directly invalid test results and even posing a significant safety hazard by allowing defective products to enter the installation process.

[0008] In fact, the aforementioned discrepancies in accuracy, fluctuations in ambient air pressure, cumbersome manual configuration, and existing point-by-point judgment methods reflect a deep-seated common deficiency in the field of heat exchanger testing: the lack of a testing architecture that can deeply couple fluid dynamics laws, environmental physical quantity compensation, and control system hardware. Traditional methods treat flow supply, environmental correction, and judgment logic separately, resulting in measured pressure drop data that can only reflect discrete states at specific moments and under specific operating conditions. This fails to comprehensively and systematically map the true flow resistance characteristic curve of the heat exchanger, which easily leads to misjudgments in the full life cycle evaluation of the heat exchanger. Summary of the Invention

[0010] This application provides a system capable of performing fully automated, high-precision pressure drop tests on multiple models of heat exchangers over a wide flow range, in order to solve the aforementioned technical problems.

[0011] Firstly, the automatic pressure drop testing system for heat exchangers provided in this application adopts the following technical solution:

[0012] An automatic pressure drop testing system for heat exchangers includes:

[0013] A dual-range parallel gas supply module includes a main pipeline and a first branch and a second branch connected in parallel downstream of the main pipeline. A first flow meter is installed on the main pipeline. A pneumatic ball valve and a first proportional control valve are sequentially installed on the first branch along the gas flow direction. A second flow meter and a second proportional control valve are sequentially installed on the second branch along the gas flow direction. The range of the second flow meter is smaller than that of the first flow meter. When the pneumatic ball valve is open, gas flows through both the first and second branches simultaneously, and the system uses the reading of the first flow meter as the flow measurement value. When the pneumatic ball valve is closed, gas flows only through the second branch, and the system uses the reading of the second flow meter as the flow measurement value.

[0014] The pressure acquisition module includes a gauge pressure sensor installed on the inlet side of the heat exchanger under test and an absolute pressure sensor installed on the atmospheric side. The absolute pressure sensor is used to acquire the ambient atmospheric pressure in real time.

[0015] The parameter storage module stores multiple test parameter sets corresponding to each heat exchanger model identifier. Each test parameter set includes at least: pressure drop calculation parameters, flow gradient sequence, and range branch identifier.

[0016] The controller is communicatively connected to the dual-range parallel gas supply module, the pressure acquisition module, and the parameter storage module, respectively. The controller is configured as follows:

[0017] In response to the received heat exchanger model identifier, the corresponding test parameter set is loaded from the parameter storage module, and the on / off state of the pneumatic ball valve is controlled according to the range branch identifier in the test parameter set to select the corresponding branch.

[0018] The flow rate is adjusted point by point to each target flow rate value according to the flow rate gradient sequence, and the gauge pressure reading of the gauge pressure sensor and the absolute pressure reading of the absolute pressure sensor are collected synchronously at each target flow rate value.

[0019] Based on the gauge pressure reading, the absolute pressure reading, and the pressure drop calculation parameters, calculate the pressure drop value after ambient atmospheric pressure compensation for each target flow rate.

[0020] By adopting the above technical solution, the system automatically switches between large-range and small-range modes by setting a first flow meter on the main pipeline and setting up a first and second branch in parallel downstream. A pneumatic ball valve controls the on / off state of the first branch. This allows a single test bench to cover the full-range pressure drop testing needs of heat exchangers of different specifications, from small to large flow rates, avoiding the need for multiple dedicated testing devices in traditional solutions and significantly reducing equipment costs and floor space. Simultaneously, the parameter storage module pre-stores test parameter sets for each heat exchanger model, which are automatically loaded by the controller based on the model identifier, enabling one-click retrieval of test parameters. This eliminates the tedious operation and error risk of manually setting parameters item by item, greatly improving testing efficiency and consistency. Furthermore, by introducing an absolute pressure sensor to obtain ambient atmospheric pressure in real time and compensating for it in the pressure drop calculation, the system eliminates the systematic influence of atmospheric pressure fluctuations at different test times, seasons, or altitudes on the pressure drop test results, ensuring the comparability and accuracy of test data under different environmental conditions.

[0021] Optionally, the test parameter set further includes upper limit curve parameters and lower limit curve parameters; the controller is also configured to:

[0022] Curve fitting was performed on multiple target flow values ​​and their corresponding compensated pressure drop values ​​to obtain the measured pressure drop curve equation;

[0023] If the measured pressure drop curve is located between the upper limit curve determined by the upper limit curve parameter and the lower limit curve determined by the lower limit curve parameter within the entire flow range covered by the flow gradient sequence, then the pressure drop of the heat exchanger under test is deemed to be qualified.

[0024] By adopting the above technical solution, this application does not simply superimpose the dual-range parallel pipeline, absolute pressure sensor, parameter storage module, and curve fitting algorithm, but constructs a rigorous "full-envelope standardized flow resistance characteristic joint analysis architecture." Specifically: the dual-range parallel gas supply module provides wide-range, continuous, and high-precision physical measurement points for full-range testing, overcoming the data distortion caused by extreme operating conditions due to a single range, and laying a wide-range data foundation for subsequent curve fitting; on this basis, the real-time compensation mechanism of the absolute pressure sensor uniformly converts discrete collected data under different environments to the standard atmospheric pressure model, eliminating physical noise caused by meteorological fluctuations, and ensuring that the wide-range data strictly obeys the gas state equation and aerodynamic drag laws; while the parameter storage module acts as the central nervous system, simultaneously coordinating the hardware switching timing of the range branches, the algorithm coefficients of atmospheric pressure compensation, and the setting of each target flow gradient according to the heat exchanger model; the hardware coordination and environmental decoupling of the above three dimensions ultimately deliver a highly pure, full-range covered standardized dataset to the controller, thus making curve-level overall judgment possible. Without the support of wide-range hardware measurement and environmental data noise reduction, any mathematical curve fitting will fail due to boundary discrepancies or distortions; conversely, without curve-level overall judgment, the global advantage of wide-range accurate data cannot be realized. These four elements are interdependent and indispensable, together completely solving the industry problem of poor environmental adaptability and inaccurate judgment under all operating conditions for multiple heat exchanger models.

[0025] Optionally, the controller is further configured to: during the point-by-point adjustment of the flow rate, form a flow rate closed-loop control to make the actual flow rate value approach the target flow rate value; wherein, the flow rate closed-loop control specifically includes:

[0026] When in small-range test mode, the real-time reading of the second flow meter on the second branch is used as a feedback signal, and the opening of the second proportional control valve is independently adjusted through a closed-loop algorithm.

[0027] When in the large-range test mode, the real-time reading of the first flow meter on the main pipeline is used as the total flow feedback signal, and the opening of the first proportional regulating valve and the second proportional regulating valve are calculated and adjusted synchronously or sequentially according to the preset dual-valve collaborative control strategy.

[0028] By adopting the above technical solution, the system forms a closed-loop feedback control loop through the flow meter and proportional regulating valve. It compares the real-time flow reading with the target flow value and automatically adjusts the valve opening to ensure that the actual flow at each test gradient point is accurately and stably close to the target value. This provides high-precision basic data for subsequent curve fitting and avoids flow deviation caused by gas supply pressure fluctuations or pipeline resistance changes under open-loop control, thereby ensuring the accuracy and repeatability of pressure drop test results.

[0029] Optionally, the pressure acquisition module includes at least three gauge pressure sensors with different ranges; the test parameter set also includes pressure sensor channel identifiers; the controller automatically selects a gauge pressure sensor whose range matches the expected pressure drop range of the heat exchanger under test based on the pressure sensor channel identifier.

[0030] By adopting the above technical solution, the system is configured with multiple gauge pressure sensors with different ranges and automatically selects the matching sensor channel according to the model identification of the heat exchanger under test. This ensures that the pressure measurement always works within the optimal range of the sensor, making full use of the sensor's resolution and accuracy. It avoids the problem of insufficient accuracy caused by using a large-range sensor for a small-pressure-drop heat exchanger, and also avoids the risk of exceeding the range caused by using a small-range sensor for a large-pressure-drop heat exchanger. This achieves a balance between pressure measurement accuracy and test range.

[0031] Optionally, in the large-range test mode when the pneumatic ball valve is in the on state, the controller simultaneously reads the flow values ​​of the first flow meter and the second flow meter, calculates the difference or ratio between the two, and issues a flow meter deviation alarm when the difference or ratio exceeds a preset threshold range.

[0032] By adopting the above technical solution, the system uses the readings of two flow meters for co-flow verification in the large-range test mode. By comparing the difference or ratio of the two flow meters at the same time, the system monitors the metering consistency of the flow meters in real time. It can promptly detect metering deviations caused by flow meter drift, blockage or malfunction during the test, ensure the reliability of test data, and avoid the quality risk of unqualified products flowing out or qualified products being misjudged due to abnormal flow metering.

[0033] Optionally, when the system starts, the controller reads the calibration validity information of each sensor, as well as the first and second flow meters; if the difference between the calibration validity period of any instrument and the current date is less than a preset warning number of days, a warning prompt is output; if the calibration validity period of any instrument is earlier than the current date, the test process is prohibited.

[0034] By adopting the above technical solution, the system automatically verifies the verification validity period of all measuring instruments during the startup phase. Through a two-level protection mechanism of early warning prompts and mandatory prohibition, it ensures that the system always operates under a legal and valid metrological state, eliminating the risk of invalid test data and failure of quality traceability due to the use of expired and unverified instruments from the source, and meeting the strict requirements of the aviation manufacturing industry for the management of measuring instruments.

[0035] Optionally, the output end of the dual-range parallel gas supply module is provided with at least two output branches, each of which is provided with an independently controlled gas supply valve, which is connected to a fixed fixture and a mobile fixture respectively; both the fixed fixture and the mobile fixture are provided with quick-connect pressure testing connectors of the same specification.

[0036] By adopting the above technical solution, the system is equipped with dual output branches that connect to a fixed fixture and a mobile fixture respectively. This allows the same test bench to be adapted to heat exchangers of different shapes and installation forms. The fixed fixture is used for efficient testing of conventional batch products, while the mobile fixture is used for flexible testing of large or irregularly shaped heat exchangers. At the same time, the standardized quick-connect pressure test connectors enable quick connection and disassembly of the fixtures and gas supply lines, shortening changeover time and improving the versatility and production efficiency of the test bench.

[0037] Secondly, this application provides an automatic method for testing the pressure drop of a heat exchanger, comprising the following steps:

[0038] Based on the model identifier of the heat exchanger under test, the corresponding test parameter set is loaded from the preset parameter storage module. The test parameter set includes at least pressure drop calculation parameters, flow gradient sequence and range branch identifier.

[0039] According to the range branch identifier, the flow measurement mode used in the test is determined: if the range branch identifier indicates a large range mode, the pneumatic ball valve set on the first branch is opened, so that the gas from the main pipeline flows through the first branch and the second branch connected in parallel with it at the same time, and the reading of the first flow meter set on the main pipeline is used as the flow measurement value.

[0040] If the range branch indicator indicates the small range mode, then the pneumatic ball valve is closed, so that the gas flows only through the second branch, and the reading of the second flow meter installed on the second branch is used as the flow measurement value.

[0041] According to the flow gradient sequence, the opening of the proportional control valve in the corresponding range mode is adjusted sequentially so that the real-time reading of the selected flow meter approaches each target flow value; after each target flow value stabilizes, the gauge pressure value and the absolute pressure value corresponding to the ambient atmospheric pressure on the inlet side of the heat exchanger under test are collected synchronously.

[0042] Based on the gauge pressure value, absolute pressure value, and pressure drop calculation parameters collected under each target flow rate, calculate each pressure drop value after compensation by ambient atmospheric pressure.

[0043] By adopting the above technical solution, this method achieves full automation of the heat exchanger pressure drop test from parameter setting to data acquisition and result calculation through the organic connection of four links: automatic parameter loading driven by model identification, automatic configuration of range mode, automatic adjustment of flow rate point by point, and real-time automatic compensation of atmospheric pressure. It shortens the test process, which requires multiple operators and takes tens of minutes in traditional manual operation, into an automated process that can be started with one click. At the same time, it eliminates the fluctuation of test results caused by human operation differences, and significantly improves test efficiency, data consistency and process traceability.

[0044] Optionally, the step of calculating the pressure drop value after compensation by ambient atmospheric pressure includes:

[0045] The absolute pressure value at the inlet side of the heat exchanger under test is obtained by summing the gauge pressure value and the absolute pressure value.

[0046] The standardized pressure drop value is calculated based on the inlet absolute pressure value, the outlet atmospheric pressure value, and the specified formula in the pressure drop calculation parameters.

[0047] By adopting the above technical solution, this method converts gauge pressure readings into absolute pressure values ​​and then substitutes them into standardized formulas to calculate pressure drop, establishing a complete data processing link from gauge pressure to absolute pressure and then to standardized pressure drop. This makes the physical meaning of the pressure drop calculation process clear and the data source traceable, ensuring the horizontal comparability of pressure drop data under different test batches and different environmental conditions.

[0048] Optionally, a curve fitting determination step may also be included:

[0049] Power function curve fitting was performed on the data sets of multiple target flow rates and corresponding compensated pressure drop values ​​to obtain the measured curve equation σΔP. r = K r × Q αr ; where σΔP r To measure the standardized voltage drop value, K r αr is the measured flow resistance coefficient, Q is the test airflow rate, and αr is the measured flow regime index;

[0050] Obtain the upper limit curve equation σΔP from the test parameter set. UL = K UL × Q αUL And the lower limit curve equation σΔP LL = K LL × Q αLL ; where σΔP ULTo standardize the upper limit of pressure drop, K UL αUL is the upper limit target correlation coefficient, σΔP is the upper limit target exponent, and σΔP is the upper limit target correlation coefficient. LL To standardize the lower limit of voltage drop, K LL αLL is the lower limit target correlation coefficient, and αLL is the lower limit target exponent;

[0051] Within the flow interval from the minimum to the maximum value of the flow gradient sequence, determine whether the output value of the measured curve equation is not greater than the output value of the upper limit curve equation and is not less than the output value of the lower limit curve equation.

[0052] If so, the pressure drop performance of the tested heat exchanger is deemed qualified.

[0053] By adopting the above technical solution, this method uses a power function model to fit the flow-pressure drop data to a curve, which is highly consistent with the physical law of the pressure drop of the heat exchanger changing with the flow rate. The fitting accuracy is high and the physical meaning of the parameters is clear. By continuously comparing the measured curve with the upper and lower limit curves in the entire flow range, rather than making discrete judgments only at a limited number of sampling points, it can capture the abnormal deviation trend that may exist between sampling points, realize the global evaluation of the pressure drop performance of the tested heat exchanger, and effectively prevent the judgment blind zone caused by improper selection of sampling points.

[0054] In summary, this application includes at least one of the following beneficial technical effects:

[0055] 1. The system utilizes a dual-range parallel gas supply module to achieve automatic switching between large and small flow rates, a parameter storage module to enable one-click loading of test parameters for multiple models, and an absolute pressure sensor to provide real-time compensation for ambient atmospheric pressure. These three components work together to form an automatic heat exchanger pressure drop testing system covering the entire range, all models, and all environmental conditions. This system replaces the traditional manual operation mode of multiple dedicated devices on a single test bench, significantly reducing equipment and labor costs. At the same time, it eliminates the impact of human operation differences and environmental fluctuations on test results, improving test efficiency, data accuracy, and process consistency.

[0056] 2. By using curve fitting based on power functions and continuous comparison of upper and lower limit curves within the entire flow range, the traditional point-by-point discrete judgment is upgraded to curve-level overall judgment. This not only reflects the pressure drop performance trend of the heat exchanger under all operating conditions, but also captures abnormal deviations between sampling points, effectively preventing misjudgment and missed judgment, and improving the reliability and scientific nature of the qualification judgment.

[0057] 3. Through multiple safeguard mechanisms such as flow closed-loop control, automatic selection of multi-range pressure sensors, dual flow meter co-flow calibration, and automatic verification of the validity period of metering instruments, the reliability and traceability of test data are comprehensively guaranteed from four dimensions: flow accuracy, pressure accuracy, metering consistency, and instrument compliance, thus meeting the stringent requirements for product quality testing in the aerospace manufacturing field. Attached Figure Description

[0059] Figure 1 This is the pneumatic schematic diagram of an automatic pressure drop testing system for heat exchangers.

[0060] Figure 2 This is a test diagram of the pressure drop curve equation of an embodiment of this application;

[0061] Figure 3 This is a plan view of the automatic heat exchanger pressure drop testing system according to an embodiment of this application;

[0062] Figure 4 This is the flowchart of the automatic test method for heat exchanger pressure drop in the embodiments of this application.

[0063] Explanation of reference numerals in the attached figures:

[0064] 100. Dual-range parallel gas supply module; 110. Main pipeline; 111. Manual shut-off valve; 112. First flow meter; 120. First branch; 121. Pneumatic ball valve; 122. First proportional regulating valve; 130. Second branch; 131. Second flow meter; 132. Second proportional regulating valve; 140. Output branch; 141. Gas supply valve; 150. Fixed fixture; 160. Mobile fixture; 200. Pressure acquisition module; 210. Gauge pressure sensor; 220. Absolute pressure sensor; 300. Controller. Detailed Implementation

[0066] The following is in conjunction with the appendix Figure 1-4 This application will be described in further detail.

[0067] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0068] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terminology used herein is for descriptive purposes only and is not intended to limit the scope of this application.

[0069] This application provides an automatic pressure drop testing system for heat exchangers. The overall concept is as follows: an automatic switching between high-flow and low-flow testing conditions is achieved through a dual-range parallel gas supply module; one-click retrieval of test parameters for multiple heat exchanger models is achieved through a parameter storage module; real-time compensation of ambient atmospheric pressure is achieved through the collaborative operation of gauge pressure and absolute pressure sensors in the pressure acquisition module; and the above modules are organically connected in series through a controller, forming a fully automated testing system from parameter loading, range configuration, flow regulation, data acquisition to pressure drop calculation. This system can cover the full-range pressure drop testing needs of heat exchangers of different specifications from low to high flow rates on a single test bench, eliminating the influence of human operation differences and environmental fluctuations on test results, and significantly improving testing efficiency, data accuracy, and process consistency.

[0070] Reference Figure 1 The automatic pressure drop testing system for heat exchangers mainly includes a dual-range parallel gas supply module 100, a pressure acquisition module 200, a parameter storage module, and a controller 300. For ease of explanation, compressed air is used as the test medium in the following example, but this application is not limited to this. Any gas medium that can be used for heat exchanger pressure drop testing can be used as a reference.

[0071] The dual-range parallel gas supply module 100 is used to supply compressed gas with regulated flow and precise metering to the heat exchanger under test. The module includes a main pipeline 110 and a first branch 120 and a second branch 130 connected in parallel downstream of the main pipeline 110.

[0072] The upstream end of the main pipeline 110 is connected to a factory compressed air source. In one embodiment, the supply pressure of the air source ranges from zero to 1.4 MPa. A manual shut-off valve 111 and a first flow meter 112 are sequentially installed on the main pipeline 110 along the gas flow direction. The manual shut-off valve 111 is used to manually cut off the air supply during system maintenance or long-term shutdown. In one embodiment, the manual shut-off valve 111 is a stainless steel flanged shut-off valve with a nominal diameter of DN80, a nominal pressure of PN16, and a valve body made of 304 stainless steel. It is fixedly connected to the main pipeline 110 via a flange and bolt assembly.

[0073] The first flow meter 112 is located downstream of the manual shut-off valve 111 and is used to measure the total flow rate through the main pipeline 110 in the large-range test mode. In one embodiment, the first flow meter 112 is a vortex flow meter with a range of zero to ten tons per hour, outputting a standard four to twenty milliamp current signal, and a nominal pressure of PN16. It is connected to the main pipeline 110 via a flange connection. The first flow meter 112 is installed upstream of a branch point on the main pipeline 110. Therefore, in the large-range mode, all gas flowing through the first branch 120 and the second branch 130 is first measured by the first flow meter 112, and its reading represents the total gas supply flow rate of the system.

[0074] Downstream of the first flow meter 112, the main pipeline 110 splits into a first branch 120 and a second branch 130 that are connected in parallel. Specifically, at the branch point, the main pipeline 110 is divided into two paths by a tee fitting: one is the first branch 120, and the other is the second branch 130. The two paths merge back into a single output pipeline downstream by another tee fitting, which is connected to the inlet end of the heat exchanger under test.

[0075] A pneumatic ball valve 121 and a first proportional regulating valve 122 are sequentially arranged along the gas flow direction on the first branch 120. The pneumatic ball valve 121 is used to control the opening and closing of the first branch 120, thereby realizing the switching between a large range mode and a small range mode. In one embodiment, the pneumatic ball valve 121 is a stainless steel pneumatic flange ball valve with a nominal diameter of DN80, a nominal pressure of PN16, and a valve body material of 304 stainless steel. It is installed on the pipe section of the first branch 120 by means of flange bolts. The pneumatic actuator of the pneumatic ball valve 121 is connected to a solenoid directional valve through an air pipe. The control terminal of the solenoid directional valve is electrically connected to the digital output port of the controller 300. The controller 300 drives the pneumatic ball valve 121 to open or close by sending a switching signal to the solenoid directional valve.

[0076] The first proportional control valve 122 is located downstream of the pneumatic ball valve 121 and is used to continuously proportionally regulate the gas flow rate through the first branch 120 in a large-range mode. In one embodiment, the first proportional control valve 122 is an electric single-seat control valve with a nominal diameter of DN80, a nominal pressure of PN16, and a valve body made of 304 stainless steel. Its electric actuator receives a 4 to 20 mA analog current signal output from the controller 300 and linearly adjusts the valve core opening accordingly, thereby achieving continuous flow adjustment. The first proportional control valve 122 is fixedly connected to the pipe section of the first branch 120 via a flange and bolt assembly.

[0077] A second flow meter 131 and a second proportional control valve 132 are sequentially installed along the gas flow direction on the second branch 130. The second flow meter 131 is used to accurately measure the gas flow rate through the second branch 130 in a small-range mode. In one embodiment, the second flow meter 131 is also a vortex flow meter with a range of zero to two tons per hour, outputting a standard four to twenty milliamp current signal, and a nominal pressure of PN16. The range of the second flow meter 131 is smaller than that of the first flow meter 112, allowing the second flow meter 131 to operate in the middle to high range of its range under low-flow conditions, thereby achieving higher measurement accuracy and resolution. The second flow meter 131 is installed on the pipe section of the second branch 130 via a flange connection.

[0078] The second proportional control valve 132 is located downstream of the second flow meter 131 and is used to continuously proportionally regulate the gas flow rate through the second branch 130 in a small-range mode. In one embodiment, the second proportional control valve 132 is an electrically operated single-seat control valve with a nominal diameter of DN40, a nominal pressure of PN16, and a valve body made of 304 stainless steel. Its diameter is smaller than that of the first proportional control valve 122, thus providing higher regulation accuracy and a smaller dead zone under low-flow conditions. The electric actuator of the second proportional control valve 132 also receives a 4 to 20 mA analog current signal output from the controller 300.

[0079] The working mode of the dual-range parallel gas supply module 100 is as follows: When the pneumatic ball valve 121 is in the open state, the gas flows from the main pipeline 110 through the first flow meter 112, and then simultaneously enters the first branch 120 and the second branch 130 at the branch point. It flows to the heat exchanger under test through the first proportional regulating valve 122 and the second proportional regulating valve 132 respectively. At this time, the system is in the large-range test mode, and the reading of the first flow meter 112 is used as the flow measurement value. It is suitable for pressure drop testing of heat exchanger types with large rated flow. When the pneumatic ball valve 121 is closed, the gas flows from the main pipe 110 through the first flow meter 112. At the branch point, because the first branch 120 is cut off by the pneumatic ball valve 121, the gas can only enter the second branch 130, flow through the second flow meter 131 and the second proportional regulating valve 132, and then enter the heat exchanger under test. At this time, the system is in the small range test mode, and the reading of the second flow meter 131 is used as the flow measurement value. It is suitable for pressure drop testing of heat exchanger types with small rated flow.

[0080] With the above structural configuration, the dual-range parallel gas supply module 100 uses the first flow meter 112 on the main pipeline 110 and the second flow meter 131 on the second branch pipeline 130 to form a dual-precision metering system with complementary large and small ranges. With the on / off control of the pneumatic ball valve 121, automatic switching is achieved, so that a single test bench can cover the full range pressure drop test requirements of heat exchangers of different specifications, avoiding the problem of needing to configure multiple dedicated test equipment in traditional solutions.

[0081] In another embodiment, the front ends of the first proportional control valve 122 and the second proportional control valve 132 can be connected in parallel to enable the switching of different proportional control valves according to the usage scenario, such as switching to use a different proportional control valve after a certain proportional control valve is damaged.

[0082] The pressure acquisition module 200 is used to acquire the pipeline pressure on the inlet side of the heat exchanger under test and the ambient atmospheric pressure, providing raw data for subsequent pressure drop calculations.

[0083] The pressure acquisition module 200 includes a gauge pressure sensor 210 installed on the inlet side of the heat exchanger under test and an absolute pressure sensor 220 installed on the atmospheric side. The gauge pressure sensor 210 is connected to the inlet pipe section of the heat exchanger under test via a pressure measuring pipeline and is used to measure the gauge pressure value of the gas pressure in the inlet pipe relative to the local atmospheric pressure. The pressure sensing end of the absolute pressure sensor 220 is open to the atmosphere and is used to acquire the ambient atmospheric pressure at the test site in real time. In one embodiment, the absolute pressure sensor 220 uses a pressure transmitter with a range of zero to 120 kPa absolute pressure, outputting a standard 4 to 20 mA current signal. The introduction of the absolute pressure sensor 220 enables the system to track changes in ambient atmospheric pressure in real time. During pressure drop calculation, the gauge pressure value is superimposed with the atmospheric pressure value to convert it into an absolute pressure value, thereby eliminating the systematic influence of atmospheric pressure fluctuations at different test periods, seasons, or altitudes on the pressure drop test results, ensuring the comparability and accuracy of test data under different environmental conditions.

[0084] In one embodiment, the pressure acquisition module 200 includes at least three gauge pressure sensors 210 with different ranges. Specifically, in this embodiment, the pressure acquisition module 200 includes a first gauge pressure sensor, a second gauge pressure sensor, and a third gauge pressure sensor, with their ranges set to 0-7 kPa, 0-60 kPa, and 0-300 kPa, respectively. The three gauge pressure sensors 210 can be connected to the pressure measurement interface on the inlet side of the heat exchanger under test through their respective independent pressure measurement lines. The signal output terminal of each gauge pressure sensor 210 is electrically connected to a different analog input channel of the controller 300. The test parameter set also includes pressure sensor channel identifiers, and the controller 300 automatically selects the gauge pressure sensor 210 whose range matches the expected pressure drop range of the heat exchanger under test based on the pressure sensor channel identifiers.

[0085] For example, for heat exchangers with a small pressure drop range of several hundred Pa to several thousand Pa, the controller 300 selects a first gauge pressure sensor with a range of 0 to 7 kPa, ensuring that the pressure measurement operates in the mid-to-high range of the sensor's range, fully utilizing the sensor's resolution and accuracy. For heat exchangers with a large pressure drop range of tens of kPa, the controller 300 selects a second gauge pressure sensor with a range of 0 to 60 kPa. Through the automatic selection of the multi-range gauge pressure sensor 210, the system can obtain optimal pressure measurement accuracy in heat exchanger tests at different pressure drop levels, avoiding the insufficient accuracy caused by using a large-range sensor for a small pressure drop heat exchanger, and also avoiding the risk of over-range measurement caused by using a small-range sensor for a large pressure drop heat exchanger.

[0086] The parameter storage module is used to centrally manage and store the test parameter sets corresponding to various heat exchanger models. This allows the system to retrieve the complete set of test configurations with one click, without the need for manual parameter setting when switching between product models under test.

[0087] The parameter storage module stores multiple test parameter sets corresponding to different heat exchanger model identifiers. Each test parameter set includes at least pressure drop calculation parameters, flow gradient sequences, and range branch identifiers. In one embodiment, the parameter storage module is implemented using a relational database within an industrial control computer, with the heat exchanger model identifier as the primary key to associate and store various test parameters.

[0088] The pressure drop calculation parameters include various coefficients, exponents, and constants involved in the pressure drop calculation formula, such as the effective heat dissipation area of ​​the heat exchanger, the cross-sectional area of ​​the flow channel, and correction factors. These parameters vary depending on the heat exchanger model and are pre-calculated and determined by process engineers based on product design drawings and technical specifications before being entered into the parameter storage module.

[0089] A flow gradient sequence defines the target flow values ​​that need to be sequentially adjusted during the testing process. In one embodiment, the flow gradient sequence is arranged in an ascending order, for example, containing five target flow values: 20%, 40%, 60%, 80%, and 100% of the rated flow. In another embodiment, the flow gradient sequence may include more target flow values ​​to obtain denser sampling data.

[0090] The range branch identifier is used to indicate whether the test for the current model of heat exchanger should use a large range mode or a small range mode. In one embodiment, the range branch identifier is a binary flag bit; when the flag bit is at the first value, it indicates a large range mode, and when the flag bit is at the second value, it indicates a small range mode. After loading the test parameter set, the controller 300 controls the on / off state of the pneumatic ball valve 121 according to the value of the range branch identifier.

[0091] In one embodiment, the test parameter set further includes upper limit curve parameters and lower limit curve parameters, which are used to define the upper and lower boundaries for determining the pass / fail performance of the heat exchanger under test, respectively. The upper limit curve parameters and lower limit curve parameters each include the coefficients and exponents in the power function curve equation; for example, the upper limit curve equation is represented as σΔP. UL = K UL × Q αUL The equation for the lower limit curve is expressed as σΔP LL = K LL × Q αLL , where σΔP UL To standardize the upper limit of pressure drop, K UL αUL is the upper limit target correlation coefficient, σΔP is the upper limit target exponent, and σΔP is the upper limit target correlation coefficient. LL To standardize the lower limit of voltage drop, K LL αLL is the lower limit target relationship coefficient, and αLL is the lower limit target index. The specific value of αLL is determined in advance by the process engineer based on the product technical conditions and entered into the parameter storage module.

[0092] The specific determination and input process of the upper and lower limit curve parameters is as follows: Process engineers pre-select several standard qualified samples of the corresponding model and conduct multiple rounds of large-sample flow-pressure drop curve tests under different ambient temperatures and meteorological conditions. Using the power function fitting method with absolute pressure compensation disclosed in this application, the flow resistance curve equation for this model across environmental benchmarks is obtained. Subsequently, combined with the design redundancy tolerance of the heat exchanger in the aero-engine or environmental control system (e.g., allowing ±5% pressure drop tolerance), the positive and negative tolerance envelope boundaries are calculated based on the coefficients and exponents of the nominal equation, thereby generating the aforementioned independent upper and lower limit curve parameters.

[0093] In one embodiment, the test parameter set also includes a pressure sensor channel identifier, which indicates the channel number of the gauge pressure sensor 210 to be selected for testing the current model of heat exchanger. The pressure sensor channel identifier corresponds one-to-one with the access channel of each gauge pressure sensor 210 in the pressure acquisition module 200, and the controller 300 automatically selects the corresponding gauge pressure sensor 210 for data acquisition based on the identifier.

[0094] By pre-storing test parameter sets for each heat exchanger model through the parameter storage module, operators only need to select the heat exchanger model identifier on the system interface, and the controller 300 can automatically load the complete set of test parameters and complete the system configuration. This eliminates the tedious operation and error risk of manually setting parameters one by one, and greatly improves testing efficiency and consistency.

[0095] The controller 300 is the core control unit of the entire automatic pressure drop testing system for the heat exchanger, and it is communicatively connected to the dual-range parallel gas supply module 100, the pressure acquisition module 200, and the parameter storage module. In one embodiment, the controller 300 is composed of a programmable logic controller (PLC) and an industrial computer. The PLC is responsible for tasks with high real-time requirements, such as real-time signal acquisition and valve control, while the industrial computer is responsible for computationally intensive tasks such as parameter management, human-machine interaction, data storage, and curve fitting calculations. The PLC and the industrial computer are connected via Ethernet communication to achieve real-time data exchange.

[0096] Controller 300 is configured to perform the following functions:

[0097] In response to the received heat exchanger model identifier, the corresponding test parameter set is loaded from the parameter storage module. The on / off state of the pneumatic ball valve 121 is controlled according to the range branch identifier in the test parameter set to select the corresponding branch.

[0098] In one embodiment, the operator selects or inputs the heat exchanger model identifier through the human-machine interface of the industrial control computer. The industrial control computer retrieves and loads the corresponding test parameter set from the database, and then sends the parameters required for real-time control, such as the range branch identifier, flow gradient sequence, and pressure sensor channel identifier, to the programmable logic controller. When the range branch identifier indicates the large range mode, the controller 300 outputs an opening signal to the solenoid directional valve of the pneumatic ball valve 121, the pneumatic ball valve 121 opens, the first branch 120 is connected, and the gas flows through both the first branch 120 and the second branch 130 simultaneously. The system uses the reading of the first flow meter 112 as the flow measurement value. When the range branch identifier indicates the small range mode, the controller 300 outputs a closing signal to the solenoid directional valve of the pneumatic ball valve 121, the pneumatic ball valve 121 closes, the first branch 120 is cut off, and the gas flows only through the second branch 130. The system uses the reading of the second flow meter 131 as the flow measurement value.

[0099] The flow rate is adjusted point by point according to the flow gradient sequence to each target flow rate value, and the gauge pressure reading of gauge pressure sensor 210 and the absolute pressure reading of absolute pressure sensor 220 are collected synchronously at each target flow rate value.

[0100] Specifically, during the point-by-point adjustment of flow rate, a closed-loop flow control is formed to make the actual flow rate value approach the target flow rate value; wherein, the closed-loop flow control specifically includes:

[0101] When in small-range test mode, the real-time reading of the second flow meter 131 on the second branch 130 is used as a feedback signal, and the opening of the second proportional regulating valve 132 is independently adjusted through a closed-loop algorithm.

[0102] When in the large-range test mode, the real-time reading of the first flow meter 112 on the main pipeline 110 is used as the total flow feedback signal, and the opening degree of the first proportional regulating valve 122 and the second proportional regulating valve 132 are calculated and adjusted synchronously or sequentially according to the preset dual-valve collaborative control strategy.

[0103] In high-range mode, the controller 300 uses the real-time reading of the first flow meter 112 as a feedback signal and employs a master-slave allocation strategy to coordinate the opening of the first proportional control valve 122 and the second proportional control valve 132 to achieve precise regulation of the total air supply. Specifically, the controller 300 uses the first proportional control valve 122 as the master control valve and the second proportional control valve 132 as the slave control valve. The controller 300 first calculates the valve opening command value required for total flow regulation based on the deviation between the target flow value and the real-time reading of the first flow meter 112 using a proportional-integral-derivative control algorithm. Then, the controller 300 allocates this opening command value to the first proportional control valve 122 and the second proportional control valve 132 according to a preset opening allocation ratio.

[0104] In one embodiment, the opening allocation ratio is determined based on the ratio of the nominal diameters of the two proportional control valves. For example, when the nominal diameter of the first proportional control valve 122 is DN80 and the nominal diameter of the second proportional control valve 132 is DN40, the flow capacity of the first proportional control valve 122 is approximately four times that of the second proportional control valve 132. Therefore, the controller 300 allocates approximately 80% of the total opening command value to the first proportional control valve 122 and approximately 20% to the second proportional control valve 132. This allocation ratio can be calibrated and fine-tuned during the system commissioning phase according to the actual pipeline flow resistance characteristics, and the calibrated allocation ratio coefficient is stored in the system configuration area of ​​the parameter storage module.

[0105] In another embodiment, the controller 300 employs a sequential, progressive strategy to coordinate the control of two proportional control valves: In the initial stage of flow regulation, the controller 300 prioritizes adjusting the opening of the first proportional control valve 122 to quickly approach the target flow value, while the second proportional control valve 132 remains at a preset fixed opening. Once the real-time reading of the first flow meter 112 enters a preset neighborhood of the target flow value, the controller 300 locks the current opening of the first proportional control valve 122 and then performs fine-tuning by adjusting the opening of the second proportional control valve 132. This utilizes the smaller diameter and higher regulation resolution of the second proportional control valve 132 to achieve precise flow stability. This strategy balances rapid response over a large flow range with high regulation accuracy in the final steady state.

[0106] In the small range mode, the controller 300 uses the real-time reading of the second flow meter 131 as a feedback signal to adjust the air supply flow by adjusting the opening of the second proportional regulating valve 132.

[0107] In one embodiment, the flow closed-loop control employs a proportional-integral-derivative (PID) control algorithm. The controller 300 takes the deviation between the target flow value and the real-time reading of the flow meter as input, performs PID calculations, and outputs the corresponding proportional control valve opening command. When the absolute value of the deviation remains within a preset stable threshold for a certain period of time, the controller 300 determines that the current target flow point has reached a stable state.

[0108] In one test embodiment, for a system with large hysteresis caused by the compressibility of the gas medium, the preset stability threshold is set to ±2% of the target flow rate, and the continuous certain time is set to be no less than 5 seconds. The controller 300 only issues a command signal allowing synchronous acquisition of pressure data when the envelope of the flow meter fluctuation is completely confined within the aforementioned time-deviation tolerance window, thus avoiding dynamic test errors introduced by taking values ​​during the transient gas column oscillation phase.

[0109] After the flow rate stabilizes, the controller 300 synchronously acquires the gauge pressure readings of the gauge pressure sensor 210 and the absolute pressure readings of the absolute pressure sensor 220 through the analog input channel of the programmable logic controller. The acquired data is stored in the data buffer of the controller 300, indexed by the target flow rate value, for subsequent pressure drop calculations. Through closed-loop flow control, the system ensures that the actual flow rate at each test gradient point is accurately and stably stable near the target value, avoiding flow deviations caused by fluctuations in gas supply pressure or changes in pipeline resistance under open-loop control, thereby guaranteeing the accuracy and repeatability of the pressure drop test results.

[0110] The controller 300 calculates the pressure drop value after compensation by ambient atmospheric pressure for each target flow rate based on the gauge pressure reading, absolute pressure reading, and pressure drop calculation parameters.

[0111] The specific calculation process is as follows: First, the gauge pressure and absolute pressure values ​​collected at each target flow rate are summed to obtain the absolute pressure value at the inlet side of the heat exchanger under test. Since gauge pressure sensor 210 measures the gauge pressure of the gas at the inlet side relative to the local atmospheric pressure, while absolute pressure sensor 220 measures the absolute pressure value of the local atmospheric pressure, the sum of the two is the absolute pressure value of the gas at the inlet side. The outlet side of the heat exchanger under test is directly connected to the atmospheric environment, so the absolute pressure value at the outlet side is equal to the ambient atmospheric pressure value measured by absolute pressure sensor 220. Then, based on the inlet absolute pressure value, the outlet atmospheric pressure value, and the specified formula in the pressure drop calculation parameters, the standardized pressure drop value is calculated.

[0112] In one embodiment, the formula for calculating the normalized voltage drop is as follows:

[0113] First, based on the gauge pressure reading Pg of the gauge pressure sensor 210 and the absolute pressure reading Patm of the absolute pressure sensor 220, the absolute pressure value at the inlet side of the heat exchanger under test is calculated:

[0114] P in = P g + P atm

[0115] Among them, P in P represents the absolute pressure value on the inlet side. g P is the inlet-side gauge pressure value measured by gauge pressure sensor 210. atm The ambient atmospheric pressure value is measured by the absolute pressure sensor 220.

[0116] The outlet side of the heat exchanger under test is directly connected to the atmospheric environment; therefore, the absolute pressure value at the outlet side is equal to the ambient atmospheric pressure value.

[0117] P out = P atm ;

[0118] Then, calculate the measured absolute pressure drop between the inlet and outlet sides:

[0119] ΔP abs = P in - P out = P g ;

[0120] Because atmospheric pressure fluctuates during different testing periods, to eliminate the impact of atmospheric pressure fluctuations on pressure drop test results and ensure the comparability of pressure drop data under different environmental conditions, it is necessary to convert the measured pressure drop values ​​to standardized pressure drop values ​​under standard atmospheric pressure conditions. The standardized conversion is based on the following physical principle: under the same mass flow rate conditions, the pressure drop generated when gas flows through the internal channels of a heat exchanger is related to the gas density, and the gas density is proportional to the absolute pressure under isothermal conditions. Therefore, the formula for calculating the standardized pressure drop is:

[0121] σΔP = ΔP abs ×P std / P atm ;

[0122] Where σΔP is the standardized pressure drop, and ΔP abs P is the measured absolute pressure drop value. std P is the standard atmospheric pressure constant (valued at 101.325 kPa). atm This is the ambient atmospheric pressure value measured in real time by the absolute pressure sensor 220.

[0123] In another embodiment, for heat exchangers with high flow rates and large pressure drops, the pressure drop calculation needs to consider the gas compressibility effect. In this case, the formula for calculating the standardized pressure drop is in the form of the square difference of absolute pressure:

[0124] σΔP =( P 2in -P 2 out ) / (2×P std );

[0125] Among them, P in P represents the absolute pressure value on the inlet side. out The absolute pressure value on the outlet side (i.e., P) atm ), P std ρ is the standard atmospheric pressure constant. This formula is derived based on an isothermal compressible flow model and can more accurately reflect the influence of gas density variations along the flow path on pressure drop measurement results under high pressure drop conditions.

[0126] The specified formulas in the pressure drop calculation parameters are predetermined by the process engineer based on the specific technical conditions of the heat exchanger under test and the applicable process specifications, and are stored in the parameter storage module in the form of formula identifiers. When loading the test parameter set, the controller 300 calls the corresponding calculation subroutine to perform the pressure drop calculation according to the formula identifier. Different models of heat exchangers can select different standardized pressure drop calculation formulas according to their flow channel characteristics and pressure drop levels. The system achieves compatibility of multiple calculation formulas through parameterized configuration.

[0127] By converting gauge pressure readings into absolute pressure values ​​and then substituting them into standardized formulas to calculate pressure drop, a complete data processing link from gauge pressure to absolute pressure and then to standardized pressure drop is established. This makes the physical meaning of the pressure drop calculation process clear and the data source traceable, ensuring the horizontal comparability of pressure drop data under different test batches and different environmental conditions.

[0128] In one embodiment, the test parameter set further includes upper limit curve parameters and lower limit curve parameters, and the controller 300 is further configured to:

[0129] The controller 300 performs curve fitting on multiple target flow values ​​and their corresponding compensated pressure drop values ​​to obtain the measured pressure drop curve equation.

[0130] In one embodiment, the controller 300 uses a power function model for curve fitting, that is, the form of the measured curve equation is σΔP. r = K r × Q αr ; where σΔP r To measure the standardized voltage drop value, K r denoted as , where Q is the measured flow resistance coefficient, Q is the test air flow rate, and αr is the measured flow regime index. The power function model closely matches the physical law of pressure drop in the heat exchanger as a function of flow rate; that is, the pressure drop is usually proportional to a certain power of the flow rate. Therefore, using a power function for fitting can achieve high fitting accuracy, and the fitting parameters have clear physical meaning.

[0131] In one embodiment, the controller 300 uses the least squares method to estimate the parameters of the power function model. Specifically, the controller 300 takes the logarithms of the flow rate value and the pressure drop value respectively and performs linear regression, and calculates the exponent αr and the coefficient Kr of the power function by back-calculating the slope and intercept of the regression line.

[0132] After obtaining the measured curve equation, the controller 300 determines whether the measured pressure drop curve is located between the upper curve determined by the upper curve parameters and the lower curve determined by the lower curve parameters within the entire flow rate range covered by the flow rate gradient sequence.

[0133] Specifically, the controller 300 obtains the upper curve equation σΔP UL = K UL × Q αUL and the lower curve equation σΔP LL = K LL × Q αLL . Where, σΔP UL is the upper limit value of the standardized pressure drop, K UL is the upper limit target relationship coefficient, αUL is the upper limit target exponent, σΔP LL is the lower limit value of the standardized pressure drop, K LL is the lower limit target relationship coefficient, αLL is the lower limit target exponent. The controller 300 calculates the output values of the measured curve equation, the upper curve equation and the lower curve equation point by point at a preset flow rate step within the flow rate range from the minimum value to the maximum value of the flow rate gradient sequence, and determines whether the output value of the measured curve equation at each calculation point is not greater than the output value of the upper curve equation and not less than the output value of the lower curve equation. If the above conditions are all satisfied at all calculation points, it is determined that the pressure drop performance of the measured heat exchanger is qualified; if the output value of the measured curve exceeds the upper curve or is lower than the lower curve at any calculation point, it is determined that the pressure drop performance of the measured heat exchanger is unqualified. As Figure 2 shown.

[0134] By replacing the traditional point-by-point determination method with the curve-level overall determination method, the system can comprehensively reflect the pressure drop performance trend of the measured heat exchanger within the full operating condition range, capture the abnormal deviation trends that may exist between sampling points, effectively prevent the determination blind area caused by improper selection of sampling points, and improve the reliability and scientificity of the qualification determination.

[0135] In one embodiment, in the large-range test mode when the pneumatic ball valve 121 is in the conducting state, the controller 300 is further configured to simultaneously read the flow rate values of the first flowmeter 112 and the second flowmeter 131, calculate the difference or ratio between the two, and issue a flowmeter deviation alarm when the difference or ratio exceeds the preset threshold range.

[0136] Specifically, in the large-range test mode, gas flows simultaneously through the first branch 120 and the second branch 130. The first flowmeter 112 measures the total flow rate through the main pipeline 110, and the second flowmeter 131 measures the flow rate through the second branch 130. The controller 300 periodically collects the real-time readings of the two flowmeters and calculates the ratio between the total flow rate and the flow rate. Due to the fixed pipeline structure, this ratio should remain within a relatively stable range under normal operating conditions. When this ratio exceeds a preset threshold range, it indicates that at least one of the first flowmeter 112 or the second flowmeter 131 may have a measurement deviation. The controller 300 then outputs a flowmeter deviation alarm message on the human-machine interface, prompting the operator to check the working status of the flowmeters.

[0137] In one embodiment, the preset threshold range is determined by the following calibration method: During the system installation and commissioning phase or after the periodic verification of the metering instruments, the operator, in a large-range test mode, sequentially adjusts the gas supply flow rate to several calibrated flow rates within the large-range range, such as 20%, 50%, and 80% of the full-scale range. After each calibrated flow rate value stabilizes, the total flow rate reading Q1 of the first flowmeter 112 and the partial flow rate reading Q2 of the second flowmeter 131 are simultaneously recorded. The ratio R0 = Q1 / Q2 is calculated, and the ratios under multiple calibrated flow rates are averaged to obtain the reference split ratio R0. This reference split ratio R0 is determined by the inherent flow resistance distribution characteristics of the pipeline and remains essentially constant under the condition that the pipeline structure and valve status remain unchanged. After calibration, the reference split ratio R0 and the allowable deviation percentage are stored in the system configuration area of ​​the parameter storage module.

[0138] During formal testing, the controller 300 periodically calculates the real-time ratio R = Q1 / Q2 between the first flowmeter 112 and the second flowmeter 131, and compares it with the reference flow split ratio R0. When the real-time ratio R deviates from the reference flow split ratio R0 by more than the allowable deviation percentage, i.e., when |R - R0| / R0 > δ, the controller 300 determines that the flowmeter has a measurement deviation and issues an alarm. In one embodiment, the allowable deviation percentage δ is set to five percent, i.e., when the deviation of the real-time flow split ratio from the reference flow split ratio exceeds plus or minus five percent, an alarm is triggered. In another embodiment, for testing scenarios of critical aerospace components with higher measurement accuracy requirements, the allowable deviation percentage δ can be set to three percent. The specific value of the allowable deviation percentage δ is determined by the metrology management personnel based on the accuracy class and test accuracy requirements of the two flow meters. For example, when the accuracy class of the first flow meter 112 is 1.0 and the accuracy class of the second flow meter 131 is 1.0, the sum of the maximum allowable errors of the two flow meters is two percent. After considering additional factors such as pipeline flow fluctuations, the allowable deviation percentage δ is set to two to three times the sum of the maximum allowable errors, that is, four to six percent.

[0139] By using dual flowmeter co-flow calibration, the system monitors the metering consistency of the flowmeters in real time during the test, and can promptly detect metering deviations caused by flowmeter drift, blockage or malfunction, ensuring the reliability of the test data.

[0140] In one embodiment, the controller 300 is further configured to read the calibration validity information of each sensor in the pressure acquisition module 200, as well as the first flow meter 112 and the second flow meter 131, when the system starts up. In one embodiment, the calibration validity information of each metering instrument is stored in the system configuration area of ​​the parameter storage module in date format, and is updated and entered by the metrology management personnel after each instrument is sent for calibration.

[0141] During the system power-on initialization phase, the controller 300 reads the verification validity period information of each measuring instrument one by one and compares it with the current system date. If the difference between the verification validity period of any instrument and the current date is less than a preset warning period (e.g., thirty days), a warning message is output on the human-machine interface to remind the metrology management personnel to arrange the verification or calibration of that instrument as soon as possible. If the verification validity period of any instrument is earlier than the current date, meaning that the verification certificate of that instrument has expired, the controller 300 prohibits the execution of the testing process and displays a warning message prohibiting testing and the expired instrument's identification information on the human-machine interface. The lock is lifted only after the metrology management personnel complete the instrument's submission for verification and update the verification validity period information.

[0142] By automatically verifying the validity period of the calibration, the system eliminates the risk of invalid test data and failure of quality traceability caused by the use of expired and uncalibrated instruments, thus meeting the strict requirements of the aerospace manufacturing industry for the management of measuring instruments.

[0143] Reference Figure 1 In one embodiment, the output end of the dual-range parallel gas supply module 100 is provided with at least two output branches 140, each of which is provided with an independently controlled gas supply valve 141, which is connected to a fixed tooling frame 150 and a movable tooling frame 160 respectively.

[0144] Specifically, the output pipeline of the dual-range parallel gas supply module 100, after the first branch 120 and the second branch 130 merge downstream, is divided into at least two output branches 140 by pipe fittings. In one embodiment, each output branch 140 is equipped with a pneumatic ball valve 121 as a gas supply valve 141, and the pneumatic actuator of each gas supply valve 141 is electrically connected to the digital output port of the controller 300, so that the controller 300 independently controls the on / off state of each output branch 140.

[0145] Reference Figure 1 and Figure 3 In one embodiment, one output branch 140 is connected to a fixed fixture 150 via a stainless steel rigid pipe. The fixed fixture 150 has a frame structure, welded from structural steel, and is fixedly mounted on the test bench base. The fixed fixture 150 is equipped with a positioning and clamping mechanism for quickly positioning and clamping heat exchangers of standard dimensions. The other output branch 140 is connected to a movable fixture 160 via a flexible connecting pipe. The movable fixture 160 is equipped with omnidirectional casters with locking function at its bottom, allowing it to be flexibly moved to the desired position within the test workshop. The movable fixture 160 is used to support products such as large or irregularly shaped heat exchangers that cannot be clamped on the fixed fixture 150.

[0146] Both the fixed fixture 150 and the mobile fixture 160 are equipped with quick-connect pressure testing connectors of a uniform specification. These connectors are used to quickly connect the pressure testing pipeline on the inlet side of the heat exchanger under test to the gauge pressure sensor 210 in the pressure acquisition module 200. In one embodiment, the quick-connect pressure testing connector uses a standard quick-plug gas connector. The operator simply inserts the plug of the pressure testing hose into the socket of the quick-connect connector to establish a sealed pressure testing path; no tools are needed to tighten the threaded connector. The connection is disconnected by pressing the release button when unplugging. The uniform quick-connect pressure testing connectors allow the same pressure testing pipeline to be used interchangeably between the fixed fixture 150 and the mobile fixture 160, shortening changeover time.

[0147] By setting up dual output branches 140 to connect the fixed fixture 150 and the mobile fixture 160 respectively, the system can adapt to heat exchangers of different shapes and sizes and installation forms, improving the versatility and production efficiency of the test bench.

[0148] The implementation principle of this application embodiment is as follows: the dual-range parallel gas supply module 100 realizes automatic switching between large and small flow rates, the parameter storage module realizes one-click loading of test parameters for multiple models, and the absolute pressure sensor 220 realizes real-time compensation of ambient atmospheric pressure. The three work together to form an automatic heat exchanger pressure drop test system covering the entire range, all models, and all environmental conditions. It replaces the traditional manual operation mode of multiple dedicated devices on a single test bench, significantly reducing equipment and labor costs. At the same time, it eliminates the impact of human operation differences and environmental fluctuations on test results, and improves test efficiency, data accuracy, and process consistency.

[0149] This application also provides an automatic testing method for heat exchanger pressure drop, which is implemented based on the aforementioned automatic heat exchanger pressure drop testing system. (Refer to...) Figure 4 The following provides a detailed explanation of each step of the method.

[0150] S100. Based on the model identifier of the heat exchanger under test, load the corresponding test parameter set from the preset parameter storage module. The test parameter set includes at least the pressure drop calculation parameters, the flow gradient sequence, and the range branch identifier.

[0151] Specifically, the operator mounts the heat exchanger under test on a fixed or mobile fixture and connects the inlet and pressure testing lines. The operator selects or scans a code to enter the model identifier of the heat exchanger under test on the industrial computer's human-machine interface. The controller retrieves the corresponding complete set of test parameters from the parameter storage module's database based on the model identifier. After loading, the controller displays a summary of the test parameters for the current model on the human-machine interface for operator confirmation. This automatic parameter loading driven by the model identifier eliminates the tedious and error-prone manual setting of parameters item by item.

[0152] S200. Determine the flow measurement mode to be used in the test based on the range branch identification.

[0153] If the range branch indicator shows the large range mode, the controller outputs an open signal to the solenoid directional valve of the pneumatic ball valve, opening the pneumatic ball valve located on the first branch. This allows gas from the main pipeline to flow simultaneously through the first branch and the second branch connected in parallel, with the flow rate measured by the reading of the first flow meter located on the main pipeline. Simultaneously, the controller incorporates both the first and second proportional control valves into the flow regulation loop to achieve precise control over a large flow range.

[0154] If the range branch indicator shows the small range mode, the controller outputs a shut-off signal to the solenoid directional valve of the pneumatic ball valve, closing the pneumatic ball valve and allowing gas to flow only through the second branch. The reading of the second flowmeter installed on the second branch is used as the flow measurement value. In this case, the controller regulates the flow only through the second proportional control valve. Because the second proportional control valve has a smaller diameter and the second flowmeter has a smaller range, the system's regulation and measurement accuracy are better than in the large range mode under small flow conditions.

[0155] In one embodiment, the range mode is determined automatically: when the maximum flow value in the flow gradient sequence is greater than the upper limit of the second flow meter's range, the range branch identifier indicates a large range mode; when the maximum flow value in the flow gradient sequence is not greater than the upper limit of the second flow meter's range, the range branch identifier indicates a small range mode. This automatic determination method allows the system to automatically generate the range branch identifier value during the test parameter set input stage, reducing the workload of manual configuration.

[0156] S300: Following the flow gradient sequence, sequentially adjust the opening of the proportional control valve in the corresponding range mode to make the real-time reading of the selected flow meter approach each target flow value. After each target flow value stabilizes, simultaneously collect the gauge pressure value and the absolute pressure value corresponding to the ambient atmospheric pressure at the inlet side of the heat exchanger under test.

[0157] Specifically, the controller reads the first target flow value from the flow gradient sequence, outputs an opening command to the corresponding proportional control valve, and uses the real-time reading of the selected flow meter as a feedback signal. Through a closed-loop control algorithm, it continuously adjusts the opening of the proportional control valve until the deviation between the real-time flow meter reading and the target flow value enters a stable threshold range and remains stable for a preset time. After the flow stabilizes, the controller synchronously acquires the gauge pressure value from the gauge pressure sensor and the absolute pressure value from the absolute pressure sensor via a programmable logic controller. The acquired gauge pressure value, absolute pressure value, and the corresponding target flow value are combined into a data record and stored in the data buffer.

[0158] Subsequently, the controller reads the next target flow value in the flow gradient sequence and repeats the above process of flow adjustment, stability determination and data acquisition until all target flow values ​​in the flow gradient sequence have been acquired.

[0159] S400: Calculate the pressure drop values ​​after compensation by ambient atmospheric pressure based on the gauge pressure, absolute pressure, and pressure drop calculation parameters collected under each target flow rate.

[0160] Specifically, for each set of data records, the controller first sums the gauge pressure value and the absolute pressure value to obtain the absolute pressure value at the inlet side of the heat exchanger under test. Then, the outlet atmospheric pressure value is set to the ambient atmospheric pressure value measured by the absolute pressure sensor. Finally, based on the inlet absolute pressure value, the outlet atmospheric pressure value, and the specified formula in the pressure drop calculation parameters, the standardized pressure drop value is calculated. Referring to the aforementioned formula for calculating the standardized pressure drop, the controller performs the above calculation on the data records corresponding to each target flow rate value in the flow gradient sequence to obtain the pressure drop value after ambient atmospheric pressure compensation for each target flow rate value.

[0161] The testing method also includes a curve fitting determination step:

[0162] S510. Perform power function curve fitting on the obtained sets of target flow values ​​and corresponding compensated pressure drop values ​​to obtain the measured curve equation σΔP. r = K r × Q αr Wherein, σΔP r To measure the standardized voltage drop value, K r Here, Q is the measured flow resistance coefficient, Q is the test airflow rate, and αr is the measured flow regime index. In one embodiment, the controller uses the least squares method to perform linear regression on the logarithmic data, and the coefficient K of the power function is calculated from the regression result. r And the exponent αr.

[0163] S520. Obtain the upper limit curve equation σΔP from the test parameter set. UL = K UL × Q αUL And the lower limit curve equation σΔP LL = K LL × Q αLL Wherein, σΔP UL To standardize the upper limit of pressure drop, K UL αUL is the upper limit target correlation coefficient, σΔP is the upper limit target exponent, and σΔP is the upper limit target correlation coefficient. LL To standardize the lower limit of voltage drop, K UL αLL is the lower limit target correlation coefficient, and αLL is the lower limit target exponent;

[0164] S530. Within the flow interval from the minimum to the maximum value of the flow gradient sequence, substitute the measured curve equation, the upper limit curve equation, and the lower limit curve equation point by point with the preset flow calculation step size, and determine whether the output value of the measured curve equation at each calculation point is not greater than the output value of the upper limit curve equation and not less than the output value of the lower limit curve equation.

[0165] If all the above conditions are met at all calculation points, the pressure drop performance of the heat exchanger under test is deemed qualified, and the controller displays the qualified result on the human-machine interface and generates a test report for archiving. If the output value of the measured curve at any calculation point exceeds the upper limit curve or falls below the lower limit curve, the pressure drop performance of the heat exchanger under test is deemed unqualified, and the controller displays the unqualified result and deviation range information on the human-machine interface.

[0166] In the above implementation process, the dual-range parallel pipeline structure, the absolute pressure compensation step, the dynamic parameter loading, and the curve-level overall judgment step constitute a closed-loop data chain with strong feedback and strong dependence. Specifically, the high reliability of multi-point curve fitting judgment depends on the self-consistency of the power function model, which is only valid when the flow measurement points span a sufficiently wide flow range and each measurement point is not affected by the external environment. In this embodiment, the controller, based on the range branch identifier automatically loaded by the parameter storage module, precisely controls the pneumatic ball valve to switch between the large-range branch and the small-range branch at the optimal critical point, ensuring that the acquisition accuracy of flow Q in both the low-flow range (determining the intercept and sensitivity) and the high-flow range (determining the upper limit of the exponent) is in the optimal state, avoiding fitting distortion at both ends of the curve; at the same time, the absolute pressure sensor captures the ambient atmospheric pressure at each point in real time, dynamically standardizing the gauge pressure value fluctuating due to the influence of external air pressure, ensuring that the pressure drop value participating in the curve fitting completely eliminates the environmental drift error caused by the passage of time within the same test process. It is precisely because of the precise guidance of the parameter storage module, the wide-range high-precision air supply of the dual-branch system, and the forced purification of environmental noise by absolute pressure compensation that the final measured curve equation can accurately reproduce the true aerodynamic damping characteristics of the internal flow channel of the heat exchanger under test. This collaborative architecture completely overcomes the problem of system error accumulation caused by isolated hardware assembly in existing technologies.

[0167] By using the curve fitting method described above, the system can continuously evaluate the pressure drop performance of the heat exchanger under test within the entire flow range, avoiding the blind spots caused by the limited sampling points in the traditional point-by-point judgment method, and improving the comprehensiveness and reliability of the judgment.

[0168] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. An automatic pressure drop testing system for heat exchangers, characterized in that, include: A dual-range parallel gas supply module (100) includes a main pipeline (110) and a first branch (120) and a second branch (130) connected in parallel downstream of the main pipeline (110); a first flow meter (112) is provided on the main pipeline (110); a pneumatic ball valve (121) and a first proportional regulating valve (122) are sequentially provided on the first branch (120) along the gas flow direction; a second flow meter (131) and a second proportional regulating valve (122) are sequentially provided on the second branch (130) along the gas flow direction. The proportional control valve (132) has a range of the second flow meter (131) that is smaller than that of the first flow meter (112). When the pneumatic ball valve (121) is open, the gas flows through both the first branch (120) and the second branch (130) simultaneously, and the system uses the reading of the first flow meter (112) as the flow measurement value. When the pneumatic ball valve (121) is closed, the gas flows through only the second branch (130), and the system uses the reading of the second flow meter (131) as the flow measurement value. The pressure acquisition module (200) includes a gauge pressure sensor (210) installed on the inlet side of the heat exchanger under test and an absolute pressure sensor (220) installed on the atmospheric side. The absolute pressure sensor (220) is used to acquire the ambient atmospheric pressure in real time. The parameter storage module stores multiple test parameter sets corresponding to each heat exchanger model identifier. Each test parameter set includes at least: pressure drop calculation parameters, flow gradient sequence, and range branch identifier. The controller (300) is communicatively connected to the dual-range parallel gas supply module (100), the pressure acquisition module (200), and the parameter storage module, respectively. The controller (300) is configured as follows: In response to the received heat exchanger model identifier, the corresponding test parameter set is loaded from the parameter storage module, and the on / off state of the pneumatic ball valve (121) is controlled according to the range branch identifier in the test parameter set to select the corresponding branch. The flow rate is adjusted point by point to each target flow rate value according to the flow rate gradient sequence, and the gauge pressure reading of the gauge pressure sensor (210) and the absolute pressure reading of the absolute pressure sensor (220) are collected synchronously at each target flow rate value. Based on the gauge pressure reading, the absolute pressure reading, and the pressure drop calculation parameters, calculate the pressure drop value after ambient atmospheric pressure compensation for each target flow rate.

2. The system according to claim 1, characterized in that, The test parameter set also includes upper limit curve parameters and lower limit curve parameters; the controller (300) is further configured to: Curve fitting was performed on multiple target flow values ​​and their corresponding compensated pressure drop values ​​to obtain the measured pressure drop curve equation; If the measured pressure drop curve is located between the upper limit curve determined by the upper limit curve parameter and the lower limit curve determined by the lower limit curve parameter within the entire flow range covered by the flow gradient sequence, then the pressure drop of the heat exchanger under test is deemed to be qualified.

3. The system according to claim 1, characterized in that, The controller (300) is further configured to: during point-by-point flow adjustment, form a flow closed-loop control to make the actual flow value approach the target flow value; wherein, the flow closed-loop control specifically includes: When in small-range test mode, the real-time reading of the second flow meter (131) on the second branch (130) is used as the feedback signal, and the opening of the second proportional regulating valve (132) is independently adjusted through closed-loop algorithm; When in the large-range test mode, the real-time reading of the first flow meter (112) on the main pipeline (110) is used as the total flow feedback signal, and the opening degree of the first proportional regulating valve (122) and the second proportional regulating valve (132) are calculated and adjusted synchronously or sequentially according to the preset dual-valve collaborative control strategy.

4. The system according to claim 1, characterized in that, The pressure acquisition module (200) includes at least three gauge pressure sensors (210) with different ranges; the test parameter set also includes pressure sensor channel identifiers; the controller (300) automatically selects the gauge pressure sensor (210) whose range matches the expected pressure drop range of the heat exchanger under test according to the pressure sensor channel identifiers.

5. The system according to claim 1, characterized in that, In the large-range test mode when the pneumatic ball valve (121) is in the conducting state, the controller (300) is also configured to: simultaneously read the flow values ​​of the first flow meter (112) and the second flow meter (131), calculate the difference or ratio between the two, and issue a flow meter deviation alarm when the difference or ratio exceeds a preset threshold range.

6. The system according to claim 1, characterized in that, The controller (300) is also configured to: when the system starts, read the calibration validity information of each sensor in the pressure acquisition module (200) and the first flow meter (112) and the second flow meter (131); if the difference between the calibration validity period of any instrument and the current date is less than the preset warning number of days, then output a warning prompt; If the verification validity period of any instrument is earlier than the current date, the test procedure is prohibited.

7. The system according to claim 1, characterized in that, The output end of the dual-range parallel gas supply module (100) is provided with at least two output branches (140), each of which is provided with an independently controlled gas supply valve (141), which is connected to a fixed fixture (150) and a movable fixture (160) respectively; both the fixed fixture (150) and the movable fixture (160) are provided with quick-connect pressure testing connectors of the same specification.

8. An automatic method for testing the pressure drop of a heat exchanger, characterized in that, Includes the following steps: Based on the model identifier of the heat exchanger under test, the corresponding test parameter set is loaded from the preset parameter storage module. The test parameter set includes at least pressure drop calculation parameters, flow gradient sequence and range branch identifier. According to the range branch marking, the flow measurement mode used in the test is determined: if the range branch marking indicates a large range mode, the pneumatic ball valve (121) set on the first branch (120) is opened, so that the gas from the main pipeline (110) flows through the first branch (120) and the second branch (130) connected in parallel with it at the same time, and the reading of the first flow meter (112) set on the main pipeline (110) is used as the flow measurement value; If the range branch indicator indicates the small range mode, the pneumatic ball valve (121) is closed, so that the gas flows only through the second branch (130), and the reading of the second flow meter (131) set on the second branch (130) is used as the flow measurement value. According to the flow gradient sequence, the opening of the proportional control valve in the corresponding range mode is adjusted sequentially so that the real-time reading of the selected flow meter approaches each target flow value; after each target flow value stabilizes, the gauge pressure value and the absolute pressure value corresponding to the ambient atmospheric pressure on the inlet side of the heat exchanger under test are collected synchronously. Based on the gauge pressure value, absolute pressure value, and pressure drop calculation parameters collected under each target flow rate, calculate each pressure drop value after compensation by ambient atmospheric pressure.

9. The method according to claim 8, characterized in that, The steps for calculating the pressure drop value after compensation by ambient atmospheric pressure include: The absolute pressure value at the inlet side of the heat exchanger under test is obtained by summing the gauge pressure value and the absolute pressure value. The standardized pressure drop value is calculated based on the inlet absolute pressure value, the outlet atmospheric pressure value, and the specified formula in the pressure drop calculation parameters.

10. The method according to claim 8, characterized in that, It also includes the curve fitting determination step: The obtained data groups of target flow values and corresponding compensated pressure drop values are subjected to power function curve fitting to obtain a measured curve equation σΔP r = K r × Q αr ; wherein σΔP r is a measured normalized pressure drop value, K r is a measured flow resistance coefficient, Q is a test air flow, and αr is a measured flow state index. Obtain the upper limit curve equation σΔP from the test parameter set. UL = K UL × Q αUL And the lower limit curve equation σΔP LL =K LL × Q αLL ; where σΔP UL To standardize the upper limit of pressure drop, K UL αUL is the upper limit target correlation coefficient, σΔP is the upper limit target exponent, and σΔP is the upper limit target correlation coefficient. LL To standardize the lower limit of voltage drop, K LL αLL is the lower limit target correlation coefficient, and αLL is the lower limit target exponent; Within the flow interval from the minimum to the maximum value of the flow gradient sequence, determine whether the output value of the measured curve equation is not greater than the output value of the upper limit curve equation and is not less than the output value of the lower limit curve equation. If so, the pressure drop performance of the tested heat exchanger is deemed qualified.

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