A method and apparatus for testing the performance of a filler

Abstract

The present application relates to heat mass exchange equipment detection technical field, disclose a kind of method and device for testing packing performance, method includes the following steps: adjusting system to run to dynamic heat balance state;Utilize air state detection mechanism to carry out physical mixing sampling to cross section air to obtain average dry-wet bulb temperature, and simultaneously collect inlet and outlet water temperature;Air is shaped after passing through flow equalizer, average dynamic pressure is collected through physically connected wind pressure detector and actual air mass flow is calculated;Based on the acquisition parameter, according to heat transfer mass transfer theory, the numerical integral is carried out to calculate packing performance test constant;Finally, through multi-working condition test and curve fitting, general performance characteristic equation is established.The present application effectively solves the measurement error problem caused by airflow distribution uneven by air physical mixing sampling and airflow homogenization pressure measurement, improves the accuracy of thermodynamic parameters and flow calculation, and the characteristic equation generated has higher engineering application value.

Description

Technical Field

[0001] This invention relates to the field of heat and mass exchange equipment testing technology, and in particular to a method and apparatus for testing the performance of packing materials. Background Technology

[0002] Cooling tower packing is a core component of industrial circulating water cooling systems. Its main function is to increase the contact area and contact time between water and air, thereby reducing the temperature of the circulating water through heat and mass exchange. The thermodynamic properties of the packing directly determine the cooling efficiency and operating energy consumption of the cooling tower. Therefore, establishing an accurate testing platform to obtain the heat and mass transfer coefficients and resistance characteristics of the packing is of great significance for the optimized design of cooling towers and the selection of packing materials.

[0003] Accurate acquisition of key air-side parameters remains a challenge in existing packing performance testing technologies. Due to the complex heat and mass exchange that occurs as air flows through the packing layer, the temperature and humidity distribution at the packing outlet cross-section is often uneven, exhibiting significant stratification or localized differences. Traditional testing methods often employ single-point measurements or simple multi-point independent sensor measurements followed by arithmetic averaging. This approach ignores the nonlinear characteristics of the thermodynamic properties of humid air and the non-uniformity of the flow field, making it difficult to accurately reflect the average enthalpy of the air at that cross-section, thus leading to significant deviations in heat balance calculations.

[0004] Furthermore, airflow over the packing material is typically accompanied by intense turbulence and vortices, resulting in poor flow field stability. Without effective flow equalization, directly reading dynamic or static pressure data using traditional pressure measuring devices often leads to large fluctuations and poor repeatability, thus affecting the accuracy of air mass flow rate calculations. If the input flow rate and temperature / humidity parameters contain errors, subsequent calculations based on heat and mass transfer theories such as the Michael equation will deviate from the true values, making it difficult to construct a universal characteristic equation that accurately characterizes the performance of the packing material under different water-to-air ratio conditions, thus limiting the engineering application value of the test data. Summary of the Invention

[0005] The purpose of this invention is to provide a method for testing the performance of packing materials, which solves the problem that in existing packing performance testing, the uneven distribution of air temperature and humidity and fluctuations in the flow field lead to poor representativeness of thermodynamic parameter acquisition and inaccurate flow rate calculation, thus making it impossible to accurately establish the general performance characteristic equation of the packing material.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for testing the performance of packing materials, comprising the following steps:

[0007] S1. By adjusting the water pump flow rate and the frequency converter frequency of the fan, the system operates under the preset target water flow rate and target air flow rate conditions until the system reaches a stable state of dynamic thermal equilibrium.

[0008] S2. Under the stable state of dynamic thermal equilibrium, the following parameters are collected simultaneously: using the air state detection mechanism arranged at the front and rear ends of the packing frame, the dry bulb temperature and wet bulb temperature of the air at the packing inlet and the dry bulb temperature and wet bulb temperature of the air at the packing outlet are measured; using the temperature sensor one installed in the water inlet of the water distribution tray and the temperature sensor two installed in the water collection tank, the inlet water temperature and outlet water temperature are measured.

[0009] S3. After the air is cooled by the water, it is guided into the duct by the fan and discharged through the flow equalizer. The average dynamic pressure after passing through the flow equalizer is collected by the interconnected air pressure detectors. Based on the average dynamic pressure, the cross-sectional characteristics of the duct, and the physical properties of the air determined by the dry-bulb temperature and wet-bulb temperature, the actual air mass flow rate corresponding to the target air flow rate is calculated.

[0010] S4. Based on the collected inlet water temperature, outlet water temperature, dry bulb temperature, wet bulb temperature, and air mass flow rate calculated in step S3, a packing performance test constant representing the current working condition is obtained by numerical integration calculation according to the heat and mass transfer theory.

[0011] S5. Repeat steps S1 to S4. By changing the ratio of the target water flow rate and the target air flow rate, obtain the test constants of the packing performance under different water-air ratio conditions, and perform curve fitting on the test constants to establish a general performance characteristic equation characterizing the packing performance.

[0012] Preferably, the criteria for determining whether the system has reached a dynamic thermal equilibrium stable state in step S1 include:

[0013] Within a preset continuous monitoring period, the outlet water temperature measured by the second temperature sensor is continuously monitored. If the difference between the maximum and minimum outlet water temperature within the monitoring period does not exceed the preset temperature threshold, it is determined that the water temperature field and airflow field in the system have reached stability.

[0014] Preferably, the process of measuring the air temperature using an air state detection mechanism in step S2 includes:

[0015] Using the main pipe of the air condition detection mechanism and multiple branch pipes fixedly connected to the outer wall of the main pipe, air is simultaneously drawn in from different spatial positions of the cross section to be tested through air inlets evenly distributed on one side of the multiple branch pipes.

[0016] The inhaled air is physically mixed during its flow into the main pipe to form an air sample representing the average state of the cross section.

[0017] The air sample is guided to a ventilated hygrometer via a connecting tube, and the dry-bulb temperature and wet-bulb temperature are read.

[0018] Preferably, the process of collecting the average dynamic pressure in step S3 includes:

[0019] The air driven by the fan is controlled to enter the duct after flowing out of the packing frame;

[0020] The flow equalizer located upstream of the wind pressure detector shapes the airflow into a stable flow state with uniform velocity distribution.

[0021] By using multiple wind pressure detectors located on a cross section downstream of the flow equalizer, which are physically interconnected to form a shared pressure output channel, the pressure at multiple detection points is physically averaged and then output to a micromanometer to obtain the average dynamic pressure.

[0022] Preferably, the actual air mass flow rate in step S3 is calculated by multiplying the flow coefficient of the duct and the pressure measuring device, the cross-sectional area of ​​the duct at the pressure measuring section, and the square root of the product of twice the average dynamic pressure and the air density.

[0023] Preferably, the numerical integration calculation in step S4 is based on the balance between the heat loss on the water side and the driving force of the gas-water enthalpy difference, and is achieved by definite integration of the ratio of the specific heat capacity of water to the enthalpy difference;

[0024] The enthalpy difference is the difference between the enthalpy of saturated humid air at the water temperature and the enthalpy of air at the corresponding position of the water temperature, and the integration interval is from the outlet water temperature to the inlet water temperature.

[0025] The air enthalpy value is calculated based on the law of conservation of energy, using the enthalpy value of the air at the packing inlet and the correction amount for water temperature changes based on the ratio of water flow rate to air mass flow rate.

[0026] Preferably, the general performance characteristic equation established in step S5 adopts a power function model, and the model characterizes the packing performance test constant as equal to the first empirical constant multiplied by the negative second empirical constant power of the water-air mass flow rate ratio.

[0027] An apparatus for testing the performance of fillers, comprising:

[0028] A frame, wherein a packing frame is fixedly connected to the inner wall of the frame, a water distribution tray is fixedly connected to the inside of the frame, and a water collection tank is fixedly connected to the inside of the frame;

[0029] An air condition detection mechanism, symmetrically installed inside the frame, is used to detect changes in dry and wet bulb temperatures;

[0030] The air condition detection mechanism includes a main pipe, with multiple branch pipes fixedly connected to the outer wall of the main pipe. Each branch pipe has an air inlet on one side, and one end of each branch pipe is fixedly connected to the inner wall of the frame. A connecting pipe is fixedly connected to the outer wall of the main pipe, and a ventilated wet / dry meter is fixedly connected to the outer wall of the connecting pipe.

[0031] Preferably, the upper surface of the water distribution tray is provided with a water inlet, a temperature sensor is fixedly connected inside the water distribution tray, and a temperature sensor is fixedly connected inside the water collection tank.

[0032] Preferably, a duct is fixedly connected to the outer wall of the frame, multiple fans are fixedly connected to the frame at the location of the duct, a flow equalizer is fixedly connected to the inside of the duct, and multiple air pressure detectors are fixedly connected to the end of the duct away from the frame.

[0033] In summary, the present invention has at least one of the following beneficial technical effects:

[0034] 1. This invention allows air to enter through multiple branch pipes via inlet holes, then converge into the main pipe, and finally be transported to a ventilated wet-bulb thermometer via a connecting pipe. This enables the detection of both dry-bulb and wet-bulb temperatures of the air, achieving simultaneous sampling and physical mixing of air at different spatial locations within the test cross-section. Before the air comes into contact with the wet-bulb and dry-bulb thermometers, it undergoes homogenization within the pipe system, directly obtaining an air sample representing the average thermodynamic state of the entire cross-section. This avoids deviations caused by single-point measurements or multi-point mathematical averaging.

[0035] 2. This invention employs a flow rate calculation method combining airflow homogenization and physical average pressure measurement. By installing a flow equalizer within the duct, the turbulent airflow exiting the packing material is shaped into a stable flow field with uniform velocity distribution. Multiple physically connected air pressure detectors are then used to directly collect the cross-sectional average dynamic pressure. This method avoids flow rate calculation errors caused by airflow pulsation or uneven distribution. By obtaining high-precision average dynamic pressure and combining it with real-time air density correction, accurate calculation of the actual air mass flow rate is achieved, ensuring the reliability of subsequent energy conservation derivations.

[0036] 3. This invention uses the heat and mass transfer theory to numerically integrate test data under multiple operating conditions and fits the discrete packing performance test constants into a general characteristic equation in the form of a power function. This not only quantifies the thermodynamic performance of the packing under different water-to-air ratios, but also eliminates the limitations of single-condition testing. The generated characteristic equation can be directly applied to the engineering design and selection of cooling towers and thermal calculations. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the method flow of the present invention;

[0038] Figure 2 This is a perspective view of the present invention;

[0039] Figure 3 This is a cross-sectional view of the frame of the present invention;

[0040] Figure 4 This is a schematic diagram of the main body of the present invention;

[0041] Figure 5 This is a schematic diagram of the connecting pipe of the present invention;

[0042] Figure 6 This is a schematic diagram of the water collection tank of the present invention;

[0043] Figure 7 This is a cross-sectional view of the ductwork of the present invention.

[0044] The components are as follows: 1. Frame; 2. Water tray; 3. Water inlet; 4. Temperature sensor one; 5. Water collection tank; 6. Air duct; 7. Air pressure detector; 8. Temperature sensor two; 9. Air condition detection mechanism; 901. Main pipe; 902. Branch pipe; 903. Ventilation wet / dry meter; 904. Air inlet; 905. Connecting pipe; 10. Packing frame; 11. Flow equalizer; 12. Fan. Detailed Implementation

[0045] The following is in conjunction with the appendix Figure 1 The present invention will be further described in detail below.

[0046] This invention provides a method for testing the performance of packing materials, comprising the following steps:

[0047] S1. By adjusting the water pump flow rate and the frequency converter frequency of the fan 12, the system operates under the preset target water flow rate and target air flow rate conditions until the system reaches a stable state of dynamic thermal equilibrium.

[0048] Specifically, in step S1 of this embodiment, the test conditions are set and the system is stabilized to provide a reliable prerequisite for subsequent accurate data acquisition.

[0049] S101, Set the flow rate. Start the test system, and the operator sets the circulating water flow rate to the preset target flow rate by adjusting the pump speed or the control valve on the pipeline. At the same time, by precisely adjusting the output frequency of the inverter connected to the fan 12, the air flow rate through the packing frame 10 is initially set to the preset target air flow rate.

[0050] S102, determine whether the system has reached a stable dynamic thermal equilibrium state. Under the flow rate conditions set in S101, the test system runs continuously. During this period, the outlet water temperature measured by temperature sensor 8 is continuously monitored and recorded by the data acquisition system. And the wet-bulb temperature of the packing inlet air measured by air condition monitoring unit 9. .

[0051] The judgment criterion is: within a preset continuous monitoring period. (For example, It can be set to within 10 minutes, while simultaneously meeting the following two conditions:

[0052] The collected water temperature The fluctuation range does not exceed the preset outlet water temperature threshold. (e.g., 0.1°C);

[0053] The collected inlet air wet-bulb temperature The fluctuation range does not exceed the preset wet-bulb temperature threshold. (e.g., 0.1°C).

[0054] The judgment criteria can be quantified using the following mathematical relationship:

[0055] ;

[0056] In the formula, This indicates any time within the monitoring time interval. Indicates the system at time 10:00 The measured outlet water temperature, Indicates the start time of the monitoring window. Indicates the duration of continuous monitoring. This represents the entire monitoring time interval used to determine stability. This indicates the maximum value of the outlet water temperature within the monitoring time interval. This represents the minimum effluent temperature within the monitoring time interval. This indicates the maximum acceptable fluctuation threshold for the outlet water temperature.

[0057] Only when the above conditions are met is it considered that the water temperature field and airflow field in the entire test system have reached stability, and the subsequent key thermodynamic parameter acquisition steps can be carried out.

[0058] The judgment criteria can be quantified using the following mathematical relationship:

[0059] ;

[0060] In the formula, This indicates any time within the monitoring time interval. Indicates the start time of the monitoring time interval. Indicates the length of the monitoring time window. Indicates time The outlet water temperature, Indicates time The inlet air wet-bulb temperature, This indicates the maximum value of the outlet water temperature within the monitoring time interval. This represents the minimum outlet water temperature within the monitoring time interval. This indicates the maximum wet-bulb temperature of the inlet air within the monitoring time interval. This represents the minimum wet-bulb temperature of the inlet air during the monitoring time interval. This indicates the maximum allowable fluctuation threshold for the outlet water temperature. This indicates the maximum permissible fluctuation threshold for the wet-bulb temperature of the inlet air.

[0061] The system is considered to be in true thermodynamic equilibrium only when both of the above conditions are met simultaneously. Only then can the collected temperature and humidity data truly reflect the performance of the packing material under steady-state conditions, thus avoiding enthalpy calculation errors caused by environmental fluctuations.

[0062] S2. Under the stable state of dynamic thermal equilibrium, the following parameters are collected simultaneously: using the air state detection mechanism 9 arranged at the front and rear ends of the packing frame 10, the dry bulb temperature and wet bulb temperature of the air at the packing inlet and the dry bulb temperature and wet bulb temperature of the air at the packing outlet are measured; using the temperature sensor 4 at the water inlet of the water distribution plate 2 and the temperature sensor 8 in the water collection tank 5, the inlet water temperature and outlet water temperature are measured.

[0063] Specifically, in this embodiment, after the test system reaches the aforementioned dynamic thermal equilibrium stable state, it proceeds to step S2, which aims to accurately obtain all the raw data required for subsequent performance calculations.

[0064] S201, collect air condition parameters. This collection is performed by two sets of air condition detection mechanisms 9 symmetrically arranged at the front and rear ends of the packing frame 10. The structure of the air condition detection mechanism 9 is as follows: it includes a main pipe 901, and multiple branch pipes 902 are fixedly connected to the outer wall of the main pipe 901. Air inlets 904 are evenly distributed on one side of the multiple branch pipes 902.

[0065] During the data collection process, air intake holes 904 facing the airflow direction simultaneously draw in air from different spatial locations on the cross-section under test. This air undergoes physical and uniform mixing as it converges into the main pipe 901. This structural design obtains an air sample that represents the average state of the entire cross-section, thus overcoming errors that may arise from uneven local airflow in single-point measurements. The mixed average air sample is guided to the ventilation hygrometer 903 via the connecting pipe 905. The dry-bulb temperature of the air at the packing inlet is measured and recorded using the ventilation hygrometer 903. and wet-bulb temperature and the dry bulb temperature of the air at the packing outlet. and wet-bulb temperature .

[0066] S202, water temperature parameters are acquired. This acquisition is performed using high-precision temperature sensor 4 and temperature sensor 8 (e.g., PT1000 model). Temperature sensor 4 is located at the front end of the water inlet of the water distribution tray 2 and is used to measure the inlet temperature of the water about to enter the packing material. Temperature sensor 28 is installed inside water collection tank 5 to measure the outlet temperature of water that has undergone a complete heat and mass exchange process and is collected there. This arrangement ensures that the measured inlet and outlet water temperatures accurately reflect the temperature changes of the water before and after flowing through the entire packing section.

[0067] S3. After the air is cooled by the water, it is guided by the fan 12 into the duct 6 and discharged through the flow equalizer 11. The average dynamic pressure after passing through the flow equalizer 11 is collected by the interconnected air pressure detector 7. Based on the average dynamic pressure, the cross-sectional characteristics of the duct, and the physical properties of the air determined by the dry-bulb temperature and wet-bulb temperature, the actual air mass flow rate corresponding to the target air flow rate is calculated.

[0068] Specifically, in this embodiment, while or after the simultaneous acquisition of thermodynamic state parameters, step S3 is performed to optimize the airflow and perform multi-point averaging measurements to obtain an accurate actual air mass flow rate for subsequent performance calculations.

[0069] S301, the airflow is homogenized. The air driven by the fan 12 flows out of the packing frame 10 and enters the air duct 6. Inside the air duct 6, the air first flows through the flow equalizer 11 located upstream of the wind pressure detector 7. The function of the flow equalizer 11 is to shape the possible airflow turbulence or uneven velocity distribution into a more uniform and stable flow state, providing a basis for subsequent accurate wind pressure measurement.

[0070] S302, average dynamic pressure is collected. Average dynamic pressure is collected by multiple air pressure detectors 7 arranged inside the duct 6 and located at a cross-section downstream of the flow equalizer 11. The wind pressure detector 7 employs a Pitot tube principle or an averaging velocitube structure, and has both a total pressure sensing port and a static pressure sensing port. It can simultaneously acquire the total pressure and static pressure of the airflow and output the difference between them as dynamic pressure. Multiple wind pressure detectors 7 are physically interconnected, forming a shared pressure output channel, which is connected to a compensated micromanometer. This structure enables the physical averaging of dynamic pressure at multiple points on the duct cross-section, thereby obtaining a highly representative average dynamic pressure. .

[0071] S303 calculates the actual air mass flow rate. This is based on the average dynamic pressure collected in step S302. Actual air mass flow rate The calculation is based on Bernoulli's equations in fluid mechanics and incorporates system calibration coefficients to correct for practical engineering errors. This is achieved through the following relationship:

[0072] ;

[0073] In the formula, This represents the actual air mass flow rate to be calculated. This indicates the flow coefficient of the duct and the pressure measuring device. This represents the cross-sectional area of ​​duct 6 at the pressure measuring section. This represents the average dynamic pressure measured in step S302. This indicates air density.

[0074] This represents the system calibration coefficient, used to correct the deviation of the Pitot tube coefficient of the wind pressure detector 7 and the non-uniformity of the velocity distribution in the duct cross section. Its value is obtained through calibration using a standard flow meter.

[0075] S4. Based on the collected inlet water temperature, outlet water temperature, dry bulb temperature, wet bulb temperature, and air mass flow rate calculated in step S3, a numerical integration calculation is performed according to the heat and mass transfer theory to obtain a test constant for the packing performance that represents the current working condition.

[0076] Specifically, in this embodiment, after obtaining all the required thermodynamic state parameters and actual air mass flow rate, the method proceeds to the packing performance test constant (i.e., cooling number). The calculation steps are as follows. This step is the core technology of the method of this invention. Through numerical integration calculation, the collected physical parameters are transformed into quantitative indicators characterizing the performance of the packing material under the current working conditions.

[0077] S401 defines the integral model for determining the cooling number, which is based on the balance between heat loss on the water side and the driving force of the air-water enthalpy difference. This is achieved by definite integral of the ratio of water's specific heat capacity to the enthalpy difference. Its cooling number... Calculated by the following formula:

[0078] ;

[0079] In the formula, Indicates the cooling number. This represents the enthalpy of saturated moist air corresponding to water temperature. Indicates the enthalpy of air. Indicates the specific heat of water. , These represent the inlet and outlet water temperatures, respectively.

[0080] In addition, the volumetric diffusion coefficient of the packing can be calculated simultaneously. The volumetric diffusion coefficient relationship is as follows:

[0081] ;

[0082] In the formula, The volumetric diffusion coefficient represents the heat dissipation performance per unit volume of the packing material. This is the height of the packing material. This refers to the actual air mass flow rate;

[0083] Other symbols and cooling numbers The meaning is the same in the integral. Therefore, the cooling number It is equal to the ratio of the product of the volumetric diffusion coefficient and the packing height to the actual air mass flow rate:

[0084] ;

[0085] In the formula, The volumetric diffusion coefficient is... This is the height of the packing material. This refers to the actual air mass flow rate. This indicates the cooling number.

[0086] S402, Determine the enthalpy values ​​in the integrand function. Before performing numerical integration, it is necessary to determine the methods for calculating two key enthalpy values ​​in the integrand function:

[0087] Enthalpy of saturated moist air Calculation of enthalpy of saturated moist air The integral variable is water temperature. The function. For the integration interval Any water temperature within Its corresponding It can be calculated using standard wet air thermodynamic formulas or by consulting a wet air enthalpy-humidity diagram.

[0088] air enthalpy Calculation of air enthalpy The heat released during integration is a variable. Its value can be derived from the law of conservation of energy within the packing material. At any cross-section within the packing material, the heat released from the inlet to the water side of that cross-section is equal to the heat absorbed from the inlet to the air side of that cross-section. Therefore, it is related to water temperature. Corresponding air enthalpy value It can be calculated using the following formula:

[0089] ;

[0090] In the formula, This indicates the enthalpy of air at that cross-section. This indicates the dry-bulb temperature of the input air measured according to step S201. and wet-bulb temperature The calculated enthalpy of the inlet air, This indicates the water mass flow rate corresponding to the target water flow rate set in step S101. This indicates the specific heat capacity of water. This represents the actual air mass flow rate calculated in step S303. Indicates the inlet temperature of the water. This indicates the temperature of the water.

[0091] S403, Perform numerical integration calculation. Since the integral equations in S401 typically have no analytical solutions, numerical integration methods are used to solve them. Taking the trapezoidal rule as an example, the specific execution process is as follows:

[0092] Integration interval Divided into equal parts A tiny temperature difference step .

[0093] For the water temperature at each dividing point (in The corresponding calculation is performed using the S402 method. and Then the value of the integrand can be calculated. .

[0094] By summing the function values ​​at all step lengths using the trapezoidal rule formula, the final test constant (cooling number) for the packing performance is calculated. Numerical solution:

[0095] ;

[0096] In the formula, Indicates the cooling number. Indicates the change in water temperature. This indicates the total number of data collection points or the number of discrete points in the temperature data. Indicates the first Water temperature at each data point , .

[0097] After completing the cooling number In addition to the calculation, this method can also be based on the average dynamic pressure collected in step S3. and airflow speed (Depend on (Conversion) to calculate the resistance characteristics of the packing. The resistance relationship of the packing is:

[0098] ;

[0099] In the formula, This represents the static pressure resistance of the packing layer, which is the difference between the average static pressure at the inlet section and the average static pressure at the outlet section of the packing frame. Indicates wind speed. This indicates air density.

[0100] coefficient Sum of Indices It is a function of the water-to-air ratio and the spray density. The relationship between them can be represented as:

[0101] ;

[0102] ;

[0103] in, Indicates the density of the sprayed water. All of these are experimental constants obtained by fitting after multi-condition testing.

[0104] S5. Repeat steps S1 to S4. By changing the ratio of target water flow rate and target air flow rate, obtain the test constants of packing performance under different water-air ratio conditions, and perform curve fitting on the test constants to establish a general performance characteristic equation characterizing the performance of the packing.

[0105] Specifically, in step S5 of this embodiment, the single-point test results are extended into a general mathematical model that can characterize the performance of the filler under different working conditions.

[0106] S501, perform multi-condition testing to obtain performance data points, which is accomplished by repeatedly executing steps S1 to S4. Specifically, the target water flow rate is systematically changed. and target airflow The ratio was set to a series of different water-to-air ratios. Under each operating condition, the system stability test, parameter acquisition, flow calculation, and packing performance test constant (cooling coefficient) were performed in their entirety. The entire calculation process is used to obtain a series of test constants for packing performance under different water-air ratio conditions.

[0107] Data can be represented as a set of multiple data points. Each data point contains a water-to-air ratio. and its corresponding packing performance test constant .

[0108] S502, perform curve fitting to establish a general performance characteristic equation. Using the series of data points obtained in step S501, a test constant (cooling number) describing the packing performance is established through mathematical fitting methods (such as the least squares method). A mathematical model of the relationship between water vapor ratio and air vapor ratio.

[0109] This model is the general characteristic equation for the thermodynamic performance of packing (the relationship between cooling number and water-to-air ratio):

[0110] ;

[0111] In the formula, Indicates the cooling number. Indicates the water-to-air ratio , The experimental constant is obtained through curve fitting. This represents the experimental constant.

[0112] Furthermore, the volumetric diffusion coefficient was obtained through further processing. And its related experimental constants, the expression of which is:

[0113] ;

[0114] In the formula, The volumetric diffusion coefficient represents the heat dissipation performance per unit volume of the packing material. This represents the actual air mass flow rate. Indicates water mass flow rate, , , This represents the experimental constant.

[0115] Among them, the index and The value is obtained by applying it to all operating conditions. , and The value is obtained using the least squares method. Because Value and and The two parameters are related and can be fixed separately. or By changing another parameter, the exponent can be obtained. and and for each working condition and already obtained and Substitute the values ​​into the above formula to find the result for each working condition. The value can be obtained by averaging. value.

[0116] The general performance characteristic equation establishes a quantitative relationship between packing performance and operating conditions, which can be directly used for the engineering design and performance verification of cooling towers, thereby guiding the design and selection of cooling towers.

[0117] The apparatus for testing packing performance described below corresponds to the method for testing packing performance described above.

[0118] Please see the appendix Figure 2 -Appendix Figure 7 The present invention also provides an apparatus for testing the performance of fillers, comprising:

[0119] A frame 1 is fixedly connected to the inner wall of the frame 1. A water distribution tray 2 is fixedly connected to the inside of the frame 1. A water collection tank 5 is fixedly connected to the inside of the frame 1. A water inlet 3 is opened on the upper surface of the water distribution tray 2. A temperature sensor 1 4 is fixedly connected to the inside of the water distribution tray 2. A temperature sensor 2 8 is fixedly connected to the inside of the water collection tank 5.

[0120] Specifically, water is pumped from the inlet 3 into the water distribution tray 2 by a water pump. The temperature of the incoming water is detected and recorded by a temperature sensor 4. The water is then evenly distributed onto the packing frame 10 by the water distribution tray 2 and flows within the packing frame 10, causing the water to fall into the water collection tank 5. The temperature of the water is detected by a temperature sensor 8.

[0121] Air condition detection mechanism 9, which is symmetrically installed inside frame 1, is used to detect changes in dry and wet bulb temperature;

[0122] The air condition detection mechanism 9 includes a main pipe 901, a plurality of branch pipes 902 are fixedly connected to the outer wall of the main pipe 901, an air inlet 904 is opened on one side of the plurality of branch pipes 902, one end of the branch pipes 902 is fixedly connected to the inner wall of the frame 1, a connecting pipe 905 is fixedly connected to the outer wall of the main pipe 901, and a ventilation wet / dry meter 903 is fixedly connected to the outer wall of the connecting pipe 905.

[0123] Specifically, the air condition detection mechanism 9 is fixed on the inner wall of the frame 1 on both sides of the packing frame 10 to detect the dry bulb and wet bulb temperatures of the inlet air and the dry bulb and wet bulb temperatures of the packing outlet air. Air enters the branch pipe 902 through the air inlet holes 904 on the multiple branch pipes 902 and flows into the main pipe 901. Then it is transported to the ventilation dry and wet bulb meter 903 through the connecting pipe 905, thereby detecting the dry bulb and wet bulb temperatures of the air.

[0124] A duct 6 is fixedly connected to the outer wall of the frame 1. Multiple fans 12 are fixedly connected to the frame 1 at the position of the duct 6. A flow equalizer 11 is fixedly connected inside the duct 6. Multiple air pressure detectors 7 are fixedly connected to the end of the duct 6 away from the frame 1.

[0125] Specifically, by starting the fan 12, air enters the air state detection mechanism 9 and the packing frame 10 from one end of the frame 1. The air flow cools the water in the packing frame 10, then enters the air duct 6, then is blown into the flow equalizer 11 and flows to the outlet of the air duct 6. The average dynamic pressure after passing through the flow equalizer 11 is collected by the interconnected air pressure detector 7.

[0126] Working principle: First, water is pumped through inlet 3 to the inside of water distribution tray 2. Temperature sensor 4 measures the temperature of the water entering the water distribution tray 2. The water is then evenly distributed onto the packing frame 10 through the water distribution tray 2, allowing the water to flow on the packing material inside the packing frame 10 and then fall into the inside of the water collection tank 5. Temperature sensor 8 detects the water passing through the packing frame 10 and then discharges it through the drain outlet of the water collection tank 5.

[0127] The fan 12 is started to allow air to flow in from one end of the frame 1, then through the packing frame 10 and come into contact with water for cooling, and then flow into the air duct 6. The air flows in the frame 1 and passes through the air condition detection mechanisms 9 installed on both sides of the packing frame 10, so that the air enters the interior of the branch pipe 902 through the air inlet 904 and flows into the main pipe 901. The air is then delivered to the ventilation dry and wet bulb meter 903 through the connecting pipe 905, so as to detect the dry bulb temperature and wet bulb temperature of the air.

[0128] Air enters the duct 6, is then blown into the flow equalizer 11 and flows to the outlet of the duct 6. The average dynamic pressure after passing through the flow equalizer 11 is then collected by the interconnected air pressure detector 7.

Claims

1. A method for testing the performance of packing materials, characterized in that, Includes the following steps: S1. By adjusting the water pump flow rate and the frequency converter frequency of the fan (12), the system operates under the preset target water flow rate and target air flow rate conditions until the system reaches a dynamic thermal equilibrium stable state. S2. Under the stable state of dynamic thermal equilibrium, the following parameters are collected simultaneously: using the air state detection mechanism (9) arranged at the front and rear of the packing frame (10), the dry bulb temperature and wet bulb temperature of the air at the packing inlet and the dry bulb temperature and wet bulb temperature of the air at the packing outlet are measured; using the temperature sensor 1 (4) installed in the water inlet of the water distribution tray (2) and the temperature sensor 2 (8) installed in the water collection tank (5), the inlet water temperature and outlet water temperature are measured. S3. After the air cools down by water, it is guided by the fan (12) into the air duct (6) and discharged through the flow equalizer (11). The average dynamic pressure after passing through the flow equalizer (11) is collected by the interconnected air pressure detector (7). Based on the average dynamic pressure, the cross-sectional characteristics of the air duct (6) and the air physical properties determined by the dry bulb temperature and wet bulb temperature, the actual air mass flow rate corresponding to the target air flow rate is calculated. S4. Based on the collected inlet water temperature, outlet water temperature, dry bulb temperature, wet bulb temperature, and air mass flow rate calculated in step S3, a packing performance test constant representing the current working condition is obtained by numerical integration calculation according to the heat and mass transfer theory. S5. Repeat steps S1 to S4. By changing the ratio of the target water flow rate and the target air flow rate, obtain the test constants of the packing performance under different water-air ratio conditions, and perform curve fitting on the test constants to establish a general performance characteristic equation characterizing the packing performance.

2. The method for testing the performance of fillers according to claim 1, characterized in that, The criteria for determining whether the system has reached a dynamic thermal equilibrium stable state in step S1 include: During a preset continuous monitoring period, the outlet water temperature measured by the second temperature sensor (8) and the wet-bulb temperature of the packing inlet air measured by the air state detection mechanism (9) are continuously monitored. If the following two conditions are met during the monitoring period, the water temperature field and airflow field within the system are considered to have reached stability: The difference between the maximum and minimum values ​​of the outlet water temperature does not exceed the preset outlet water temperature threshold. The difference between the maximum and minimum wet-bulb temperature of the air at the packing inlet did not exceed the preset wet-bulb temperature threshold.

3. The method for testing the performance of fillers according to claim 1, characterized in that, The process of measuring the air temperature using the air state detection mechanism (9) in step S2 includes: Using the main pipe (901) of the air condition detection mechanism (9) and multiple branch pipes (902) fixedly connected to the outer wall of the main pipe (901), air is simultaneously drawn in from different spatial positions of the cross section to be tested through air inlets (904) evenly distributed on one side of the multiple branch pipes (902); The inhaled air is physically mixed as it flows into the main pipe (901) to form an air sample representing the average state of the cross section; The air sample is guided to the ventilated wet and dry bulb meter (903) via the connecting tube (905), and the dry bulb temperature and wet bulb temperature are read.

4. The method for testing the performance of fillers according to claim 1, characterized in that, The process of collecting average dynamic pressure in step S3 includes: The air driven by the fan (12) is controlled to enter the air duct (6) after flowing out of the packing frame (10); The flow equalizer (11) located upstream of the wind pressure detector (7) is used to shape the airflow into a stable flow state with uniform velocity distribution. The wind pressure detector (7) is used to simultaneously obtain the total pressure and static pressure of the airflow, and the difference between the total pressure and the static pressure is output as the dynamic pressure. By using multiple wind pressure detectors (7) located on a cross section downstream of the flow equalizer (11), a shared pressure output channel is formed through physical interconnection. The dynamic pressure at multiple detection points is physically averaged and then output to a micro pressure gauge to obtain the average dynamic pressure.

5. The method for testing the performance of fillers according to claim 1, characterized in that, In step S3, the actual air mass flow rate is calculated by multiplying the system calibration coefficient, the cross-sectional area of ​​the duct (6) at the pressure measurement section, and the square root of twice the product of the average dynamic pressure and the air density.

6. The method for testing the performance of fillers according to claim 1, characterized in that, The numerical integration calculation in step S4 is based on the balance between the heat loss on the water side and the driving force of the gas-water enthalpy difference. It calculates the cooling number or volumetric diffusion coefficient, which serves as a test constant for the packing performance. The specific calculation process includes: The cooling number is calculated by definite integral of the ratio of water's specific heat capacity to its enthalpy difference over the interval from the outlet water temperature to the inlet water temperature. The volumetric diffusion coefficient is obtained by multiplying the cooling number by the actual air mass flow rate and then dividing by the packing height; The enthalpy difference is the difference between the enthalpy of saturated humid air at the water temperature (the integral variable) and the enthalpy of air at the corresponding location at that water temperature. The air enthalpy value is calculated based on the law of conservation of energy, using the enthalpy value of the air at the packing inlet and the correction amount for water temperature changes based on the ratio of water flow rate to air mass flow rate.

7. The method for testing the performance of fillers according to claim 6, characterized in that, The process of establishing the general performance characteristic equation in step S5 includes: establishing a general thermal performance characteristic equation using a power function model based on the cooling number under different water-to-air ratio conditions, wherein the model represents that the cooling number is equal to the first empirical constant multiplied by the second empirical constant raised to the power of the water-to-air mass flow rate ratio; establishing a packing resistance characteristic equation based on the average dynamic pressure collected in step S3 and the airflow velocity converted from the actual air mass flow rate; wherein the packing resistance characteristic equation represents that the packing resistance divided by the air density is equal to the resistance coefficient multiplied by the exponent of the airflow velocity, wherein the resistance coefficient and the exponent are both quadratic functions of the water density.

8. An apparatus for testing the performance of packing materials, applied to the method for testing the performance of packing materials according to any one of claims 1-7, characterized in that, include: The frame (1) has a packing frame (10) fixedly connected to its inner wall, a water distribution tray (2) fixedly connected to the inside of the frame (1), and a water collection tank (5) fixedly connected to the inside of the frame (1). An air condition detection mechanism (9) is symmetrically installed inside the frame (1) to detect changes in dry and wet bulb temperatures; The air condition detection mechanism (9) includes a main pipe (901), a plurality of branch pipes (902) are fixedly connected to the outer wall of the main pipe (901), an air inlet (904) is opened on one side of the plurality of branch pipes (902), one end of the branch pipe (902) is fixedly connected to the inner wall of the frame (1), a connecting pipe (905) is fixedly connected to the outer wall of the main pipe (901), and a ventilation dry and wet meter (903) is fixedly connected to the outer wall of the connecting pipe (905).

9. The apparatus for testing the performance of packing materials according to claim 8, characterized in that, The water distribution tray (2) has a water inlet (3) on its upper surface. A temperature sensor (4) is fixedly connected inside the water distribution tray (2). A temperature sensor (8) is fixedly connected inside the water collection tank (5).

10. The apparatus for testing the performance of fillers according to claim 8, characterized in that, The outer wall of the frame (1) is fixedly connected to a duct (6), and multiple fans (12) are fixedly connected to the frame (1) at the position of the duct (6). A flow equalizer (11) is fixedly connected inside the duct (6), and multiple wind pressure detectors (7) are fixedly connected to the end of the duct (6) away from the frame (1).

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