An apparatus for quickly determining the speed of a ventilation fan at an engineering site and a method of using the same

Abstract

The application relates to a device for quickly determining the rotating speed of a ventilator on a construction site and a use method thereof, and relates to the technical field of ventilator engineering application debugging. The device comprises a hardware main body composed of a controller and a touch display screen, and a control software system with five modules of built-in parameter input, curve fitting, system resistance calculation, target working condition solution and result output. The method is based on the similarity theory of the ventilator, accurately quantifies the pipeline system resistance characteristics through on-site measurement, one-key solves the target running rotating speed, and simultaneously completes the motor adaptability determination and the belt pulley transmission ratio recommendation. The application does not need to transform the original control system of the ventilator, can complete the on-site debugging offline, greatly improves the rotating speed calculation precision, realizes the standard reaching after the replacement of the belt pulley once, and significantly shortens the debugging period and reduces the engineering cost.

Description

Technical Field

[0001] This invention relates to the field of ventilation fan engineering application and commissioning technology, specifically to a device and its method for quickly determining the speed of a ventilation fan on-site. Background Technology

[0002] As the core power equipment of HVAC and industrial ventilation systems, the operating conditions of ventilation fans directly determine the ventilation effect of the system. In practical engineering applications, ventilation fans often use fixed-frequency motors with belt pulleys to determine the operating speed. Design institutes complete the selection and operating condition design of ventilation fans based on the design pipeline resistance. However, due to factors such as the routing of pipelines, the number of pipe fittings, and the installation accuracy on site, the actual pipeline system resistance on site often deviates significantly from the design resistance. This results in a serious discrepancy between the actual operating conditions (flow rate, external static pressure) of the ventilation fan and the design conditions, making it impossible to meet the system ventilation requirements.

[0003] Currently, the industry-standard commissioning method for addressing the aforementioned operating condition deviation issue is as follows: technicians estimate the theoretical speed based on the fan's similarity theory, and then repeatedly test and verify the results on-site by changing different pulley combinations with varying transmission ratios until the operating conditions meet the design requirements. This method has significant drawbacks: it cannot accurately quantify the actual resistance characteristics of the on-site pipelines, the estimated speed deviates greatly from actual needs, and often requires multiple pulley replacements to achieve the design operating conditions. This significantly prolongs the engineering commissioning period and increases after-sales maintenance costs, becoming a common challenge in the application of fan engineering in the industry.

[0004] In existing technologies, constant air volume control is achieved by preset a constant air volume curve and closed-loop adjustment based on motor speed and duty cycle. However, this is only applicable to fresh air handling units with brushless DC motors. It relies on the unit's built-in real-time online closed-loop control system and cannot be adapted to offline commissioning scenarios of ventilation fans with fixed frequency motors and belt drives that have already been installed on-site. Summary of the Invention

[0005] The purpose of this invention is to provide a device and its method for quickly determining the speed of a ventilation fan on-site, in order to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a device for quickly determining the speed of a ventilation fan on an engineering site, comprising a hardware main body and a control software system running within the hardware main body;

[0007] The hardware component includes a controller and a display screen, which are bidirectionally connected to the controller. The display screen is used to input parameters to the controller and simultaneously receive and visualize the calculation results output by the controller. The controller is used to host and run the control software system, and execute parameter processing, logical operations, and result output instructions.

[0008] The control software system includes a parameter input module, a curve fitting module, a system resistance calculation module, a target working condition solution module, and a result output module.

[0009] The parameter input module communicates and interacts with the display screen to receive and verify the fan's factory performance test parameters, engineering design parameters, and on-site measured parameters entered through the display screen. The factory performance test parameters include at least the fan's flow rate, static pressure, speed, and power under multiple operating conditions; the engineering design parameters include at least the design flow rate, design external static pressure, and rated power of the matching motor; and the on-site measured parameters include at least the on-site measured flow rate, measured external static pressure, measured operating speed, and measured operating power.

[0010] The curve fitting module is communicatively connected to the parameter input module. It is used to fit and generate a flow-static pressure performance curve at a reference speed based on the factory performance test parameters. It is also used to convert the flow-static pressure performance curve at the reference speed into a flow-static pressure performance curve at the actual measured speed based on the fan similarity theory.

[0011] The system resistance calculation module is communicatively connected to the parameter input module and the curve fitting module, respectively. It is used to obtain the theoretical static pressure of the fan at the measured speed at the measured flow rate through interpolation calculation based on the measured flow rate at the site. Based on the difference between the theoretical static pressure and the measured external static pressure, the system resistance loss is calculated, and then the system resistance coefficient K is solved and the system characteristic curve is generated.

[0012] The target operating condition solution module is communicatively connected to the parameter input module and the system resistance calculation module, respectively. It is used to calculate the system resistance loss under the design operating condition based on the design flow rate and the system resistance coefficient K, and to solve the target static pressure of the fan in combination with the design external static pressure. It is also used to calculate the target operating speed of the fan based on the design flow rate and the target static pressure through the fan similarity theory, and to convert the fan operating power at the target speed.

[0013] The result output module communicates and interacts with the target operating condition solution module and the display screen respectively, and is used to transmit the target operating speed and motor adaptation determination result to the display screen for display. The motor adaptation determination result is generated by comparing the fan operating power at the target speed with the rated power of the matching motor.

[0014] Furthermore, the display screen is a touch screen, which has the functions of parameter touch input, curve visualization display and calculation result output; the controller is an embedded microcontroller, which has a storage unit for storing the input parameters, fitted performance curves, system characteristic curves and calculation result data.

[0015] Furthermore, the curve fitting module is also configured to: when the factory performance test parameters include no less than 7 operating points that can reflect the operating area of ​​the fan, generate the flow-static pressure performance curve at the reference speed using a smooth curve fitting method; the conversion rules of the fan similarity theory are: the flow ratio is equal to the speed ratio, the static pressure ratio is equal to the square of the speed ratio, and the power ratio is equal to the cube of the speed ratio.

[0016] Furthermore, in the system resistance calculation module, the formula for calculating the system resistance coefficient K is as follows: ,in For system resistance loss, The flow rate was measured on-site; the system characteristic curves are based on... Relation generation, where For system resistance, This refers to the fan flow rate.

[0017] Furthermore, in the target operating condition solution module, the calculation formula for the target static pressure of the ventilation fan at the design flow rate is as follows: ,in For designing external static pressure, This refers to the system resistance loss under design conditions. , For the design flow rate; the result output module is also configured to: generate a judgment result that the motor does not need to be replaced when the fan operating power at the target speed is less than or equal to the rated power of the matching motor; and generate a warning result that the motor needs to be replaced and a recommended value for the power of the suitable motor when the fan operating power at the target speed is greater than the rated power of the matching motor.

[0018] A method for using a device for quickly determining the speed of a ventilation fan on-site, based on the aforementioned device, includes the following steps:

[0019] S1. Input the fan's factory performance test parameters, engineering design parameters, and on-site measured parameters through the device's display screen. The parameter input module in the controller receives and verifies the input parameters. The factory performance test parameters include at least the fan's flow rate, static pressure, speed, and power under multiple operating conditions. The engineering design parameters include at least the design flow rate, design external static pressure, and rated power of the matching motor. The on-site measured parameters include at least the on-site measured flow rate, measured external static pressure, measured operating speed, and measured operating power.

[0020] S2. The curve fitting module in the controller fits and generates the flow-static pressure performance curve at the reference speed based on the verified factory performance test parameters, and converts the flow-static pressure performance curve at the reference speed into the flow-static pressure performance curve at the actual measured speed based on the fan similarity theory.

[0021] S3. The system resistance calculation module in the controller obtains the theoretical static pressure of the fan at the corresponding flow rate under the measured speed by interpolation calculation based on the actual flow rate on site. It calculates the difference between the theoretical static pressure and the measured external static pressure to obtain the system resistance loss. Then, based on the system resistance loss and the measured flow rate, it solves the system resistance coefficient K and generates the system characteristic curve simultaneously.

[0022] S4. The target operating condition solution module in the controller calculates the system resistance loss under the design operating condition based on the design flow rate and system resistance coefficient K, and obtains the target static pressure of the fan by combining the design external static pressure solution.

[0023] S5. The target operating condition solution module in the controller calculates the target operating speed of the fan based on the design flow rate and target static pressure through the fan similarity theory, and simultaneously calculates the fan operating power at the target speed. It then compares the fan operating power at the target speed with the rated power of the matching motor to generate the motor compatibility judgment result.

[0024] S6. The result output module in the controller transmits the target operating speed and motor adaptation determination results to the display screen, and completes the visualization output through the display screen.

[0025] Furthermore, in step S2, the factory performance test parameters include no less than 7 operating points that can reflect the operating conditions of the fan's usage area, and the flow-static pressure performance curve at the reference speed is generated by a smooth curve fitting method; the conversion rules of the fan similarity theory are: flow ratio equals speed ratio, static pressure ratio equals the square of speed ratio, and power ratio equals the cube of speed ratio.

[0026] Furthermore, in step S3, before performing the interpolation calculation, it is first verified whether the actual measured flow rate is within the flow coverage range of the flow-static pressure performance curve at the measured rotational speed; if it exceeds the coverage range, a flow rate over-limit prompt is issued through the display screen; if it is within the coverage range, then the linear interpolation calculation is performed; after completing the solution of the system resistance coefficient K, the validity of the K value is also determined. When the K value exceeds the preset engineering experience threshold range, a system resistance abnormality prompt is issued through the display screen.

[0027] Furthermore, in steps S4-S5, before solving for the target static pressure, it is first verified whether the design flow rate is within the flow coverage range of the flow-static pressure performance curve at the reference speed. Based on the similarity theory of the fan, combined with the sweep method and the bisection iteration method, the target operating speed is obtained, and then the flow-static pressure performance curve at the target speed is calculated.

[0028] Furthermore, after step S6 is completed, the following steps are also performed: the target operating speed, system resistance coefficient, flow-static pressure performance curves at each speed, and system characteristic curves are stored in the controller's non-volatile storage unit; at the same time, based on the target operating speed and the rated speed of the motor measured on site, the recommended values ​​of the transmission ratio and diameter matching of the drive wheel and driven wheel are calculated and output through the display screen.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] This invention, through a system resistance calculation module, based on actual on-site measured operating data, enables rapid and accurate quantification of the actual resistance characteristics of pipeline systems in engineering sites. It solves the core technical problems of existing technologies, such as the inability to obtain real on-site resistance and the lack of accurate basis for speed conversion, thus laying the foundation for accurate calculation of target speed.

[0031] Based on the similarity theory of ventilation fans, this invention combines curve fitting, linear interpolation, sweep method and binary iterative solution into a complete algorithm to achieve one-click accurate calculation of the target rotational speed. Compared with existing theoretical estimation methods, it significantly improves the accuracy of rotational speed calculation. Verification by examples shows that repeated trial and error is not required.

[0032] During the process of solving for the target speed, this invention simultaneously completes the conversion of the fan power at the target speed and the determination of the motor compatibility, thus avoiding the engineering risk of motor overload after speed adjustment in advance and filling the industry gap of existing debugging methods lacking safety verification.

[0033] This invention, through the integrated portable device design of "controller + touch screen" and the modular software system, realizes the entire process of parameter input, calculation and result output on-site offline operation. It does not require modification of the original control system of the ventilation fan, nor does it require complicated online debugging equipment. It is suitable for the complex construction environment of various engineering sites, with low operation threshold and strong convenience.

[0034] This invention achieves the design working condition by accurately calculating the target rotational speed, requiring only one pulley replacement on-site. This completely solves the industry pain point of multiple pulley replacements and trial and error in existing technologies, as verified by engineering applications. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the flow-static pressure performance curve of the ventilation fan at the factory speed n1 of the present invention;

[0036] Figure 2 This is a schematic diagram showing the flow-static pressure performance curve of the ventilation fan of the present invention at the on-site operating speed n2 and the measured operating conditions at the engineering site.

[0037] Figure 3 The flow rate at the actual measured rotational speed n2 of this invention is... Schematic diagram of static pressure P1 and external static pressure P0 of the down-draft fan;

[0038] Figure 4 This is a schematic diagram showing the flow-static pressure performance curve of the ventilation fan of the present invention at the on-site operating speed n2 and the system characteristic curve during on-site operation;

[0039] Figure 5 The design flow rate of this invention A schematic diagram illustrating the calculation of the target static pressure (p0+Δp0) required by the downdraft fan;

[0040] Figure 6 This is a schematic diagram showing the flow-static pressure performance curve of the ventilation fan at the target speed n3 and the matching with the design conditions of the present invention.

[0041] Figure 7 This is a schematic diagram comparing the flow-static pressure performance and system resistance characteristics of the ventilator before and after speed adjustment according to the present invention. Detailed Implementation

[0042] Please see Figure 1 —7, a device for quickly determining the speed of a ventilation fan on an engineering site, comprising a hardware main body and a control software system running within the hardware main body;

[0043] The main hardware consists of a controller and a display screen, which are bidirectionally connected to the controller. The display screen is used to input parameters into the controller and simultaneously receive and visualize the calculation results output by the controller. The controller is used to host and run the control software system, and execute parameter processing, logical operations, and result output instructions.

[0044] The control software system includes a parameter input module, a curve fitting module, a system resistance calculation module, a target working condition solution module, and a result output module.

[0045] The parameter input module communicates and interacts with the display screen to receive and verify the fan's factory performance test parameters, engineering design parameters, and on-site measured parameters entered through the display screen. Among them, the factory performance test parameters include at least the fan's flow rate, static pressure, speed, and power under multiple operating conditions; the engineering design parameters include at least the design flow rate, design external static pressure, and rated power of the matching motor; and the on-site measured parameters include at least the on-site measured flow rate, measured external static pressure, measured operating speed, and measured operating power.

[0046] The curve fitting module communicates with the parameter input module and is used to fit and generate the flow-static pressure performance curve at the reference speed based on the factory performance test parameters. It is also used to convert the flow-static pressure performance curve at the reference speed into the flow-static pressure performance curve at the actual measured speed based on the fan similarity theory.

[0047] The system resistance calculation module is connected to the parameter input module and the curve fitting module respectively. It is used to obtain the theoretical static pressure of the fan at the measured speed and corresponding flow rate through interpolation calculation based on the measured flow rate on site. Based on the difference between the theoretical static pressure and the measured external static pressure, the system resistance loss is calculated, and then the system resistance coefficient K is solved and the system characteristic curve is generated.

[0048] The target operating condition solution module is connected to the parameter input module and the system resistance calculation module. It is used to calculate the system resistance loss under the design operating condition based on the design flow rate and the system resistance coefficient K, and to solve the target static pressure of the fan in combination with the design external static pressure. It is also used to calculate the target operating speed of the fan based on the design flow rate and the target static pressure through the fan similarity theory, and to convert it into the fan operating power at the target speed.

[0049] The results output module communicates and interacts with the target operating condition solution module and the display screen to transmit the target operating speed and motor compatibility determination results to the display screen for display. The motor compatibility determination results are generated by comparing the fan operating power at the target speed with the rated power of the matching motor.

[0050] The display screen is a touch screen, which has the functions of parameter touch input, curve visualization and calculation result output; the controller is an embedded microcontroller with a storage unit, which is used to store the input parameters, fitted performance curves, system characteristic curves and calculation result data.

[0051] The curve fitting module is also configured to generate a flow-static pressure performance curve at the reference speed when the factory performance test parameters include no less than 7 operating points that can reflect the operating area of ​​the fan. The conversion rules of the fan similarity theory are: the flow ratio is equal to the speed ratio, the static pressure ratio is equal to the square of the speed ratio, and the power ratio is equal to the cube of the speed ratio.

[0052] In the system resistance calculation module, the formula for solving the system resistance coefficient K is as follows: ,in For system resistance loss, The flow rate was measured on-site; the system characteristic curves are based on... Relation generation, where For system resistance, This refers to the fan flow rate.

[0053] In the target operating condition solution module, the formula for calculating the target static pressure of the ventilation fan at the design flow rate is as follows: ,in For designing external static pressure, This refers to the system resistance loss under design conditions. , For design flow rate; the result output module is also configured to: generate a judgment result that the motor does not need to be replaced when the fan operating power at the target speed is less than or equal to the rated power of the matching motor; and generate a warning result that the motor needs to be replaced and a recommended value for the power of the matching motor when the fan operating power at the target speed is greater than the rated power of the matching motor.

[0054] A method for using a device for quickly determining the speed of a ventilation fan on-site, based on the aforementioned device, includes the following steps:

[0055] S1. Input the fan's factory performance test parameters, engineering design parameters, and on-site measured parameters through the device's display screen. The parameter input module in the controller receives and verifies the input parameters. Among them, the factory performance test parameters include at least the fan's flow rate, static pressure, speed, and power under multiple operating conditions; the engineering design parameters include at least the design flow rate, design external static pressure, and rated power of the matching motor; and the on-site measured parameters include at least the on-site measured flow rate, measured external static pressure, measured operating speed, and measured operating power.

[0056] S2. The curve fitting module in the controller fits and generates the flow-static pressure performance curve at the reference speed based on the verified factory performance test parameters, and converts the flow-static pressure performance curve at the reference speed into the flow-static pressure performance curve at the actual measured speed based on the fan similarity theory.

[0057] S3. The system resistance calculation module in the controller obtains the theoretical static pressure of the fan at the corresponding flow rate under the measured speed by interpolation calculation based on the actual flow rate on site. It calculates the difference between the theoretical static pressure and the measured external static pressure to obtain the system resistance loss. Then, based on the system resistance loss and the measured flow rate, it solves the system resistance coefficient K and generates the system characteristic curve simultaneously.

[0058] S4. The target operating condition solution module in the controller calculates the system resistance loss under the design operating condition based on the design flow rate and system resistance coefficient K, and obtains the target static pressure of the fan by combining the design external static pressure solution.

[0059] S5. The target operating condition solution module in the controller calculates the target operating speed of the fan based on the design flow rate and target static pressure through the fan similarity theory, and simultaneously calculates the fan operating power at the target speed. It then compares the fan operating power at the target speed with the rated power of the matching motor to generate the motor compatibility judgment result.

[0060] S6. The result output module in the controller transmits the target operating speed and motor adaptation determination results to the display screen, and completes the visualization output through the display screen.

[0061] In step S2, the factory performance test parameters include no less than 7 operating points that can reflect the operating area of ​​the fan. The flow-static pressure performance curve at the reference speed is generated by a smooth curve fitting method. The conversion rules of the fan similarity theory are: the flow ratio is equal to the speed ratio, the static pressure ratio is equal to the square of the speed ratio, and the power ratio is equal to the cube of the speed ratio.

[0062] In step S3, before performing the interpolation calculation, it is first verified whether the actual measured flow rate is within the flow coverage range of the flow-static pressure performance curve at the measured rotation speed. If it exceeds the coverage range, a flow rate over-limit warning is issued through the display screen. If it is within the coverage range, the linear interpolation calculation is then performed. After the system resistance coefficient K is solved, the validity of the K value is also determined. When the K value exceeds the preset engineering experience threshold range, a system resistance abnormality warning is issued through the display screen.

[0063] First, check: Is the actual flow rate measured on-site "out of range"? Then check the device: Does the flow rate measured on-site cover the fan performance curve? If it exceeds the range, immediately trigger an alarm: Flow rate exceeds limit. Avoid using curve extrapolation for inaccurate calculations. Next, check: Is the calculated system resistance coefficient K "abnormal"? After the device calculates K, compare it with the normal range based on engineering experience. If K is too large / too small, trigger an alarm: System resistance is too large / too small.

[0064] In steps S4-S5, before solving for the target static pressure, it is first verified whether the design flow rate is within the flow coverage range of the flow-static pressure performance curve at the reference speed. Based on the similarity theory of the fan, combined with the sweep method and the bisection iteration method, the target operating speed is obtained, and then the flow-static pressure performance curve at the target speed is calculated.

[0065] After step S6 is completed, the following steps are also performed: the target operating speed, system resistance coefficient, flow-static pressure performance curves at each speed, and system characteristic curves are stored in the controller's non-volatile storage unit; at the same time, based on the target operating speed and the rated speed of the motor measured on site, the recommended values ​​of the transmission ratio and diameter matching of the drive wheel and driven wheel are calculated and output through the display screen. Example 1:

[0066] The technical solution adopted by the present invention to solve the above problems is as follows:

[0067] When a ventilator is used on a construction site and the operating conditions at the site do not meet the design requirements, the device can quickly determine the required speed by inputting the corresponding test parameters into the ventilator's factory performance test parameter column, design parameter column, and actual test parameter column on the construction site. This is achieved by using the ventilator's similarity theory and the program's algorithm. The device then determines whether the motor needs to be replaced by judging the power. On the construction site, the design parameters can be quickly achieved by replacing the pulley once.

[0068] In the performance test parameter field of this device's ventilation fan, input the flow rate, static pressure, speed n1, and power under multiple operating conditions. Typically, the factory performance test parameters should include at least seven operating points reflecting the operating area of ​​the ventilation fan. This device will automatically fit the input multiple operating points using a smoothing curve to form the flow rate and static pressure curve at speed n1, as shown below. Figure 1 .

[0069] On-site testing typically involves controlling the external static pressure to test the flow rate, and then inputting the flow rate into the actual test field at the engineering site of this unit. External static pressure Rotational speed n2, power Based on the similarity theory of the fan, the parameters are automatically calculated from the factory test data to the performance at speed n2, and the flow rate and static pressure curve at speed n2 are automatically fitted by a smoothing curve, as shown in the figure. Figure 2 .

[0070] The device is designed to determine the external static pressure based on the engineering site. Actual traffic volume By interpolation calculation, the static pressure of the fan at the corresponding flow rate when the fan speed is n2 was found. ,like Figure 3 .

[0071] The static pressure at the factory setting of the device at this flow rate and n2 rotation speed through the fan. External static pressure measured at the engineering site difference The drag coefficient of this system is obtained. ,according to The relationship is used to generate system characteristic curves, such as Figure 4 .

[0072] Then enter the design flow rate in the design parameters column. Design of external static pressure Motor power, based on design flow rate Combining this with the system's drag coefficient K, we get Therefore, under this system, the following needs to be achieved: Traffic, When the external static pressure is reached, the static pressure of the fan needs to reach ( ),like Figure 5 .

[0073] The device uses flow rate ,pressure( Using the similarity theory of ventilation fans and combined with program code calculations, the required rotational speed n3 is quickly located on-site. Based on the performance at n2, the performance parameters at n3 are obtained using similarity theory. The power at n3 is checked to determine whether the motor needs to be replaced. On-site, based on the rotational speed n3, the design parameters (flow rate) are achieved by changing the combination of the driving and driven impellers once. External static pressure ),like Figure 6 . Example 2:

[0074] The on-site design point happens to fall on the factory test point, and the external static pressure of the control design is tested and verified.

[0075] Factory test performance of the ventilation fan:

[0076]

[0077] The design institute designed it. External static pressure It is matched with a motor power of 11kW.

[0078] Adjust the system resistance on-site to the external static pressure. hour, Rotation speed .

[0079] According to the scene External static pressure It can be known that the static pressure of the ventilator at the factory is... Calculate system resistance loss The system drag coefficient is obtained. .

[0080] according to With design flow , thus gain resistance loss .

[0081] Based on the resistance loss and external static pressure, the ventilation fan meets the requirements on site. When the external static pressure is 400Pa, the required static pressure of the fan is... .

[0082] according to static pressure Using the similarity theory of ventilation fans and combined with program code calculations, the following can be obtained: The flow rate at that rotational speed is obtained through interpolation. At that time, the power required is 10.96kW, which meets the on-site requirements; on-site, only the drive-driven wheel ratio needs to be changed to meet the requirements, such as... Figure 7 .

[0083] If the on-site design point does not fall on the factory test point, and the actual on-site measurement conditions cannot be adjusted, how can the speed be adjusted to achieve the desired result? See the example below:

[0084] The factory test performance of the ventilation fan is shown in Table 1:

[0085] Table 1. Test data of the ventilation fan at the factory (n1 is the actual test speed (not necessarily the same speed)).

[0086]

[0087] The design institute designed it. External static pressure Matching motor power .

[0088] Based on the actual system structure, the external static pressure was directly measured on-site without additional adjustments to the system resistance. , Rotation speed .

[0089] according to Based on the similarity theory of ventilation fans, , When the fan operates at speed n2 (a specified speed, a constant speed, equivalent to the fan running at speed n2, the data in Table 2 are obtained by adjusting the resistance of the laboratory test system), the fan data are shown in Table 2.

[0090] Table 2 Factory test data of the ventilation fan during n2 operation

[0091]

[0092] Based on the data in Table 2 and In this case, the system actively analyzes the landing point and finds it to be between operating points 3 and 4 in Table 2, i.e., the flow rate is between 18641 and 15468. Using interpolation, it calculates that when... At that time, pressure ,

[0093] ,have to .

[0094] According to on-site testing External static pressure under flow rate and the ventilation fan The required factory pressure When the project site is in operation When the flow rate is high, the system resistance loss is low. ,according to The system drag coefficient is obtained. .

[0095] Based on the system resistance coefficient K and the design required flow rate Obtain resistance loss .

[0096] Based on resistance loss External static pressure The ventilation fan must meet the requirements. External static pressure At that time, the static pressure of the fan is required. .

[0097] according to static pressure ,

[0098] Using the similarity theory of ventilation fans, the required rotational speed n2 is increased to n3. Combined with the program code calculation, n3 = 1034 r / min is obtained. Based on the rotational speed n3 and the parameters in Table 1, and according to the similarity theory of ventilation fans... , , See Table 3. Based on the n3 rotational speed and the corresponding flow rate, pressure, and power, it is found through interpolation that at this rotational speed, when the flow rate reaches 19000 m3 / h, the power required is 10.63 kW, which meets the on-site requirements (no need to replace the motor). On-site, only the driving-driven wheel ratio needs to be changed to achieve the n3 rotational speed to meet the design requirements.

[0099] Table 3 Factory test data of the ventilation fan during n3 operation

[0100]

[0101] ,have to .

Claims

1. A device for quickly determining the rotational speed of a ventilation fan on-site, characterized in that, It includes a hardware main body and a control software system running within the hardware main body; The hardware component includes a controller and a display screen, which are bidirectionally connected to the controller. The display screen is used to input parameters to the controller and simultaneously receive and visualize the calculation results output by the controller. The controller is used to host and run the control software system, and execute parameter processing, logical operations, and result output instructions. The control software system includes a parameter input module, a curve fitting module, a system resistance calculation module, a target working condition solution module, and a result output module. The parameter input module communicates and interacts with the display screen to receive and verify the fan's factory performance test parameters, engineering design parameters, and on-site measured parameters entered through the display screen. The factory performance test parameters include at least the fan's flow rate, static pressure, speed, and power under multiple operating conditions; the engineering design parameters include at least the design flow rate, design external static pressure, and rated power of the matching motor; and the on-site measured parameters include at least the on-site measured flow rate, measured external static pressure, measured operating speed, and measured operating power. The curve fitting module is communicatively connected to the parameter input module. It is used to fit and generate a flow-static pressure performance curve at a reference speed based on the factory performance test parameters. It is also used to convert the flow-static pressure performance curve at the reference speed into a flow-static pressure performance curve at the actual measured speed based on the fan similarity theory. The system resistance calculation module is communicatively connected to the parameter input module and the curve fitting module, respectively. It is used to obtain the theoretical static pressure of the fan at the measured speed at the measured flow rate through interpolation calculation based on the measured flow rate at the site. Based on the difference between the theoretical static pressure and the measured external static pressure, the system resistance loss is calculated, and then the system resistance coefficient K is solved and the system characteristic curve is generated. The target operating condition solution module is communicatively connected to the parameter input module and the system resistance calculation module, respectively. It is used to calculate the system resistance loss under the design operating condition based on the design flow rate and the system resistance coefficient K, and to solve the target static pressure of the fan in combination with the design external static pressure. It is also used to calculate the target operating speed of the fan based on the design flow rate and the target static pressure through the fan similarity theory, and to convert the fan operating power at the target speed. The result output module communicates and interacts with the target operating condition solution module and the display screen respectively, and is used to transmit the target operating speed and motor adaptation determination result to the display screen for display. The motor adaptation determination result is generated by comparing the fan operating power at the target speed with the rated power of the matching motor.

2. The device for quickly determining the speed of a ventilation fan on-site according to claim 1, characterized in that, The display screen is a touch screen, which has the functions of parameter touch input, curve visualization display and calculation result output; the controller is an embedded microcontroller with a storage unit, which is used to store the input parameters, fitted performance curves, system characteristic curves and calculation result data.

3. The device for quickly determining the speed of a ventilation fan on-site according to claim 1, characterized in that, The curve fitting module is also configured to: when the factory performance test parameters include no less than 7 operating points that can reflect the operating area of ​​the fan, generate a flow-static pressure performance curve at the reference speed using a smooth curve fitting method; the conversion rules of the fan similarity theory are: flow ratio equals speed ratio, static pressure ratio equals the square of speed ratio, and power ratio equals the cube of speed ratio.

4. The device for quickly determining the speed of a ventilation fan on-site according to claim 1, characterized in that, In the system resistance calculation module, the formula for solving the system resistance coefficient K is as follows: ,in For system resistance loss, The flow rate was measured on-site; the system characteristic curves are based on... Relation generation, where For system resistance, This refers to the fan flow rate.

5. The device for quickly determining the speed of a ventilation fan on-site according to claim 1, characterized in that, In the target operating condition solution module, the formula for calculating the target static pressure of the ventilation fan at the design flow rate is as follows: ,in For designing external static pressure, This refers to the system resistance loss under design conditions. , For the design flow rate; the result output module is also configured to: generate a judgment result that the motor does not need to be replaced when the fan operating power at the target speed is less than or equal to the rated power of the matching motor; and generate a warning result that the motor needs to be replaced and a recommended value for the power of the suitable motor when the fan operating power at the target speed is greater than the rated power of the matching motor.

6. A method for using a device for quickly determining the speed of a ventilation fan on-site, characterized in that, Based on the device described in claim 1, the following steps are included: S1. Input the fan's factory performance test parameters, engineering design parameters, and on-site measured parameters through the device's display screen. The parameter input module in the controller receives and verifies the input parameters. The factory performance test parameters include at least the fan's flow rate, static pressure, speed, and power under multiple operating conditions. The engineering design parameters include at least the design flow rate, design external static pressure, and rated power of the matching motor. The on-site measured parameters include at least the on-site measured flow rate, measured external static pressure, measured operating speed, and measured operating power. S2. The curve fitting module in the controller fits and generates the flow-static pressure performance curve at the reference speed based on the verified factory performance test parameters, and converts the flow-static pressure performance curve at the reference speed into the flow-static pressure performance curve at the actual measured speed based on the fan similarity theory. S3. The system resistance calculation module in the controller obtains the theoretical static pressure of the fan at the corresponding flow rate under the measured speed by interpolation calculation based on the actual flow rate on site. It calculates the difference between the theoretical static pressure and the measured external static pressure to obtain the system resistance loss. Then, based on the system resistance loss and the measured flow rate, it solves the system resistance coefficient K and generates the system characteristic curve simultaneously. S4. The target operating condition solution module in the controller calculates the system resistance loss under the design operating condition based on the design flow rate and system resistance coefficient K, and obtains the target static pressure of the fan by combining the design external static pressure solution. S5. The target operating condition solution module in the controller calculates the target operating speed of the fan based on the design flow rate and target static pressure through the fan similarity theory, and simultaneously calculates the fan operating power at the target speed. It then compares the fan operating power at the target speed with the rated power of the matching motor to generate the motor compatibility judgment result. S6. The result output module in the controller transmits the target operating speed and motor adaptation determination results to the display screen, and completes the visualization output through the display screen.

7. The method of using the device for quickly determining the speed of a ventilation fan on-site according to claim 6, characterized in that, In step S2, the factory performance test parameters include no less than 7 operating points that can reflect the operating area of ​​the ventilator. The flow-static pressure performance curve at the reference speed is generated by a smooth curve fitting method. The conversion rules of the ventilator similarity theory are: the flow ratio is equal to the speed ratio, the static pressure ratio is equal to the square of the speed ratio, and the power ratio is equal to the cube of the speed ratio.

8. The method of using the device for quickly determining the speed of a ventilation fan on-site according to claim 6, characterized in that, In step S3, before performing the interpolation calculation, it is first verified whether the actual measured flow rate is within the flow coverage range of the flow-static pressure performance curve at the actual rotational speed. If the data usage exceeds the coverage area, a notification of exceeding the data limit will be displayed on the screen. If the system is within the coverage area, linear interpolation calculation is performed. After the system resistance coefficient K is solved, the validity of the K value is also determined. When the K value exceeds the preset engineering experience threshold range, an abnormal system resistance prompt is issued through the display screen.

9. The method of using the device for quickly determining the speed of a ventilation fan on-site according to claim 6, characterized in that, In steps S4-S5, before solving for the target static pressure, it is first verified whether the design flow rate is within the flow coverage range of the flow-static pressure performance curve at the reference speed. Based on the similarity theory of the fan, combined with the sweep method and the bisection iteration method, the target operating speed is obtained, and then the flow-static pressure performance curve at the target speed is calculated.

10. The method of using the device for quickly determining the speed of a ventilation fan on-site according to claim 6, characterized in that, After step S6 is completed, the following steps are also performed: the target operating speed, system resistance coefficient, flow-static pressure performance curves at each speed, and system characteristic curves are stored in the controller's non-volatile storage unit; at the same time, based on the target operating speed and the rated speed of the motor measured on site, the recommended values ​​of the transmission ratio of the drive pulley and driven pulley and the pulley diameter matching ratio are calculated and output through the display screen.

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