A method for measuring the air temperature field at the air outlet of a braking resistor device

Abstract

This invention relates to an air outlet temperature field measuring device, specifically a method for measuring the air temperature field at the outlet of a braking resistor device. A temperature measuring plate with ventilation openings, made of 304 stainless steel, is installed at the air outlet of the forced-air-cooled braking resistor device. During operation, the plate is heated by the cooling air, resulting in an oxide film on its surface. Since the oxide film thickness is related to the cooling air temperature and affects the interference colors, the color distribution of the oxide film produced after the temperature measuring plate is oxidized by the high temperature of the cooling air can be used to deduce the temperature distribution of the cooling air at the outlet, i.e., the air outlet temperature field. The materials are inexpensive and readily available; the densely spaced openings on the temperature measuring plate minimize the impact on the cooling airflow, ensuring that the operating conditions during temperature measurement closely approximate the normal operating state of the braking resistor device.

Description

Technical Field

[0001] This invention relates to an apparatus for measuring temperature fields, and more particularly to a method for measuring the temperature field of the air outlet of a braking resistor device. Background Technology

[0002] As the power of locomotive braking resistors increases, the problem of resistor burnout is receiving more and more attention. A significant proportion of burnouts are caused by uneven heating of the resistor strip due to uneven cooling airflow distribution within the flow channel. The distribution of cooling airflow within the flow channel and its heat dissipation effect on the resistor strip can be represented by the cooling air temperature field at the air outlet.

[0003] Currently, there is no direct means to measure the temperature field of the cooling air at the air outlet under operating conditions. Summary of the Invention

[0004] To address the above problems, this invention provides a method for creating an air temperature field at the outlet of a braking resistor device that uses inexpensive and readily available materials, has densely packed openings in the temperature measuring plate that minimize the impact on the flow of cooling air, and allows the operating conditions during temperature measurement to closely approximate the normal working state of the braking resistor device.

[0005] The 304 stainless steel temperature measuring plate is made of 304 stainless steel, with a smooth and flat surface. It is degreased and cleaned, and the naturally formed oxide scale is removed. It is not treated with coloring, electroplating, coating or other processes.

[0006] The technical solution of this invention relates to a method for measuring the air temperature field at the outlet of a braking resistor device, characterized by comprising a 304 stainless steel temperature measuring plate, an air outlet of the braking resistor device, a spectrophotometer, and the following steps:

[0007] 1) Select 304 stainless steel temperature measuring plate material that has not undergone coloring, electroplating, or coating treatment;

[0008] 2) The 304 stainless steel temperature measuring plate is made of 304 stainless steel. The surface of the 304 stainless steel temperature measuring plate is mechanically ground and polished, and the surface is flat and smooth.

[0009] 3) Degrease the surface of the 304 stainless steel temperature measuring plate to remove surface oil, dust and other contaminants;

[0010] 4) The naturally formed oxide scale on the 304 stainless steel temperature measuring plate is removed by pickling;

[0011] 5) Open evenly distributed ventilation openings on the 304 stainless steel temperature measuring plate;

[0012] 6) A non-heat-generating punching process is used to process ventilation openings on 304 stainless steel temperature measuring plates;

[0013] 7) The evenly distributed ventilation openings occupy more than 70% of the total area of ​​the 304 stainless steel temperature measuring plate, which minimizes the obstruction of airflow and does not affect the airflow state.

[0014] 8) Install the 304 stainless steel temperature measuring plate at the air outlet of the braking resistor device. After installation, the 304 stainless steel temperature measuring plate should be perpendicular to the cooling airflow direction of the air outlet.

[0015] 9) Turn on the braking resistor device in the working condition that requires temperature measurement, and after the working condition stabilizes, continue for 20 minutes or more to allow the 304 stainless steel temperature measuring plate to be heated and oxidized in the cooling air.

[0016] 10) After the operating conditions stabilize for 20 minutes or more, turn off the braking resistor device and remove it after the 304 stainless steel temperature measuring plate has cooled down naturally.

[0017] 11) Use a spectrophotometer to measure the L* and a* values ​​of the wind-receiving surface of the 304 stainless steel temperature measuring plate, and record the measurement point locations; take multiple measurement points to obtain multiple data points;

[0018] 12) The air temperature field of the air outlet (1) of the braking resistor device is obtained from the coordinates of the measurement point and the calculated temperature value of the point.

[0019] Step 12) includes:

[0020] Substitute the measured L* value into the following formula (1) to obtain the temperature value at that location;

[0021] T = k1(L*)³ + k2(L*) 2 +k3L*+k4 ……(1)

[0022] In the formula,

[0023] T represents the highest temperature experienced at that location;

[0024] L* is the L* value measured at this location by the spectrophotometer;

[0025] k1, k2, k3, and k4 are coefficients, and the preferred value for the coefficients is: k1 = -1.6585 × 10 -2 , k2=2.3855, k3= -117.6304, k4= 2619.8094;

[0026] The air temperature field at the air outlet 1 of the braking resistor device is obtained from the coordinates of the measurement point and the calculated temperature value at that point.

[0027] Substitute the measured a* value into the following equation (2) to obtain the temperature value at that location.

[0028] T = j1(a*) 3 +j2(a*)2 +j3(a*)+j4……(2)

[0029] In the formula,

[0030] T represents the highest temperature experienced at that location;

[0031] a* is the a* value measured at this location by the spectrophotometer;

[0032] j1, j2, j3, and j4 are coefficients, and the preferred value for the coefficients is: j1 = 6.1406 × 10 -2 , j2= -2.7541, j3=55.0889, j4=267.4303;

[0033] The air temperature field at the outlet of the braking resistor device can be obtained from the coordinates of the measurement point and the calculated temperature value at that point.

[0034] The advantages of this invention are: the temperature measuring plate is made of 304 stainless steel, which is inexpensive and readily available; the temperature measuring plate has relatively dense openings, which have little impact on the flow of cooling air, making the operating conditions during temperature measurement close to the normal working conditions of the braking resistor device. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention.

[0036] In the diagram, 1 is the air outlet of the braking resistor device; 2 is the 304 stainless steel temperature measuring plate; 3 is the spectrophotometer; and 4 is the ventilation opening. Detailed Implementation

[0037] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings and examples, thereby providing a full understanding of how the present invention uses technical means to solve technical problems and achieve technical effects, and enabling its implementation. It should be noted that, as long as there is no conflict, the various embodiments and features in each embodiment of the present invention can be combined with each other, and the resulting technical solutions are all within the protection scope of the present invention.

[0038] Furthermore, numerous specific details are set forth in the following description for purposes of explanation, in order to provide a thorough understanding of the embodiments of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without the specific details herein or the particular methods described.

[0039] When 304 stainless steel and its components are exposed to high temperatures in air, a very thin and dense oxide film forms on their surface due to high-temperature oxidation. This oxide film is colorless and transparent, but due to the principle of light interference, it displays interference colors. The color of the interference colors is related to the thickness of the oxide film. After a certain period of high-temperature oxidation in air, the thickness of the oxide film formed on 304 stainless steel and its components is related to the highest temperature experienced.

[0040] Based on the above principles, this invention provides a device for measuring the air temperature field at the outlet of a braking resistor device. The analytical method of this invention will now be described through the following embodiments. Example 1

[0041] like Figure 1 As shown, this invention relates to a method for measuring the air temperature field at the outlet of a braking resistor device, characterized by comprising a 304 stainless steel temperature measuring plate 2, an air outlet 1 of the braking resistor device, a spectrophotometer 3, and the following steps:

[0042] 1) Select 304 stainless steel temperature measuring plate material that has not undergone coloring, electroplating, or coating treatment;

[0043] 2) The 304 stainless steel temperature measuring plate 2 is made of 304 stainless steel. The surface of the 304 stainless steel temperature measuring plate 2 is mechanically ground and polished, and the surface is flat and smooth.

[0044] 3) Degrease the surface of the 304 stainless steel temperature measuring plate 2 to remove surface oil, dust and other contaminants;

[0045] 4) The naturally formed oxide scale on the 304 stainless steel temperature measuring plate 2 is removed by pickling;

[0046] 5) Make evenly distributed ventilation openings 4 on the 304 stainless steel temperature measuring plate 2;

[0047] 6) A non-heat-generating punching process is used to process ventilation openings 4 on the 304 stainless steel temperature measuring plate 2;

[0048] 7) The evenly distributed ventilation openings 4 occupy more than 70% of the area of ​​the 304 stainless steel temperature measuring plate 2, which makes the airflow obstruction area small and does not affect the airflow state.

[0049] 8) Install the 304 stainless steel temperature measuring plate 2 on the air outlet 1 of the braking resistor device. After installation, the 304 stainless steel temperature measuring plate 2 is perpendicular to the cooling airflow direction of the air outlet.

[0050] 9) Turn on the braking resistor device in the working condition that requires temperature measurement, and after the working condition stabilizes, continue for 20 minutes or more to allow the 304 stainless steel temperature measuring plate 2 to be heated and oxidized in the cooling air.

[0051] 10) After the operating conditions stabilize for 20 minutes or more, turn off the braking resistor device and remove the 304 stainless steel temperature measuring plate 2 after it cools down naturally.

[0052] 11) Use a spectrophotometer 3 to measure the L* value of the wind-receiving surface of the 304 stainless steel temperature measuring plate 2, and record the measurement point location; take multiple measurement points to obtain multiple data points;

[0053] 12) Substitute the measured L* value into the following formula (1) to obtain the temperature value at that location;

[0054] T = k1(L*)³ + k2(L*) 2 +k3L*+k4 ……(1)

[0055] In the formula,

[0056] T represents the highest temperature experienced at that location;

[0057] L* is the L* value measured at this location by the spectrophotometer;

[0058] k1, k2, k3, and k4 are coefficients, and the preferred value for the coefficients is: k1 = -1.6585 × 10 -2 , k2=2.3855, k3= -117.6304, k4= 2619.8094;

[0059] The air temperature field at the air outlet 1 of the braking resistor device is obtained from the coordinates of the measurement point and the calculated temperature value at that point. Example 2

[0060] like Figure 1 As shown, this invention relates to a device for measuring the air temperature field at the outlet of a braking resistor device, characterized by comprising a 304 stainless steel temperature measuring plate 2, an air outlet 1 of the braking resistor device, a spectrophotometer 3, and the following steps:

[0061] 1) Select 304 stainless steel temperature measuring plate material that has not undergone coloring, electroplating, or coating treatment;

[0062] 2) The 304 stainless steel temperature measuring plate 2 is made of 304 stainless steel. The surface of the 304 stainless steel temperature measuring plate 2 is mechanically ground and polished, and the surface is flat and smooth.

[0063] 3) Degrease the surface of the 304 stainless steel temperature measuring plate 2 to remove surface oil, dust and other contaminants;

[0064] 4) The naturally formed oxide scale on the 304 stainless steel temperature measuring plate 2 is removed by pickling;

[0065] 5) Make evenly distributed ventilation openings 4 on the 304 stainless steel temperature measuring plate 2;

[0066] 6) A non-heat-generating punching process is used to process ventilation openings 4 on the 304 stainless steel temperature measuring plate 2;

[0067] 7) The evenly distributed ventilation openings 4 occupy more than 70% of the area of ​​the 304 stainless steel temperature measuring plate 2, which makes the airflow obstruction area small and does not affect the airflow state.

[0068] 8) Install the 304 stainless steel temperature measuring plate 2 at the air outlet 1 of the braking resistor device. After installation, the 304 stainless steel temperature measuring plate 2 is perpendicular to the cooling airflow direction of the air outlet.

[0069] 9) Turn on the braking resistor device in the working condition that requires temperature measurement, and after the working condition stabilizes, continue for 20 minutes or more to allow the 304 stainless steel temperature measuring plate 2 to be heated and oxidized in the cooling air.

[0070] 10) After the operating conditions stabilize for 20 minutes or more, turn off the braking resistor device and remove the 304 stainless steel temperature measuring plate 2 after it cools down naturally.

[0071] 11) Use a spectrophotometer 4 to measure the a* value of the wind-receiving surface of the 304 stainless steel temperature measuring plate 2, and record the measurement point location. Take multiple measurements to obtain multiple data points.

[0072] 12) Substitute the measured a* value into the following formula (2) to obtain the temperature value at that location.

[0073] T = j1(a*) 3 +j2(a*) 2 +j3(a*)+j4……(2)

[0074] In the formula,

[0075] T represents the highest temperature experienced at that location;

[0076] a* is the a* value measured at this location by the spectrophotometer;

[0077] j1, j2, j3, and j4 are coefficients, and the preferred value for the coefficients is: j1 = 6.1406 × 10 -2 , j2= -2.7541, j3=55.0889, j4=267.4303;

[0078] The air temperature field at the outlet of the braking resistor device can be obtained from the coordinates of the measurement point and the calculated temperature value at that point.

[0079] The principle of the measurement method of this invention is as follows: When 304 stainless steel and its components are exposed to air and operate in a high-temperature environment, a very thin and dense oxide film will form on their surface due to high-temperature oxidation. This oxide film is colorless and transparent, but due to the principle of light interference, it will display interference colors. The color of the interference colors is related to the thickness of the oxide film. After 304 stainless steel and its components undergo high-temperature oxidation in air for a certain period of time, the thickness of the oxide film produced is related to the highest temperature experienced. A temperature measuring plate with ventilation openings is made of 304 stainless steel and installed at the air outlet of a forced-air-cooled braking resistor device. When the braking resistor device is working, it is heated by the cooling air, and an oxide film is formed on its surface. Because the thickness of the oxide film is related to the temperature of the cooling air, and the thickness of the oxide film affects the interference colors, the temperature distribution of the cooling air at the air outlet, i.e., the air temperature field at the air outlet, can be deduced from the color distribution of the oxide film produced after the temperature measuring plate is oxidized by the cooling air at high temperature.

[0080] Those skilled in the art should understand that this invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to this invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for measuring the air temperature field at the outlet of a braking resistor device, characterized in that: Includes a 304 stainless steel temperature measuring plate (2), a braking resistor device air outlet (1), a spectrophotometer (3), and the following steps: 1) Select 304 stainless steel temperature measuring plate (2) without coloring, electroplating, or coating treatment; 2) The 304 stainless steel temperature measuring plate (2) is made of 304 stainless steel. The surface of the 304 stainless steel temperature measuring plate (2) is mechanically ground and polished, and the surface is flat and smooth. 3) Degrease the surface of the 304 stainless steel temperature measuring plate (2) to remove surface oil and dust contaminants; 4) The naturally formed oxide scale on the 304 stainless steel temperature measuring plate (2) is removed by pickling; 5) Make evenly distributed ventilation openings (4) on the 304 stainless steel temperature measuring plate (2); 6) A non-heat-generating punching process is used to process ventilation openings (4) on a 304 stainless steel temperature measuring plate (2); 7) The evenly distributed ventilation openings (4) occupy more than 70% of the area of ​​the 304 stainless steel temperature measuring plate (2), which makes the airflow obstruction area small and does not affect the airflow state. 8) Install the 304 stainless steel temperature measuring plate (2) at the air outlet (1) of the braking resistor device. After installation, the 304 stainless steel temperature measuring plate (2) is perpendicular to the cooling airflow direction of the air outlet. 9) Turn on the braking resistor device in the working condition that requires temperature measurement, and after the working condition stabilizes, continue for 20 minutes or more to allow the 304 stainless steel temperature measuring plate (2) to be heated and oxidized in the cooling air. 10) After the working condition is stable and lasts for 20 minutes or more, turn off the braking resistor device and remove the 304 stainless steel temperature measuring plate (2) after it cools down naturally. 11) Use a spectrophotometer (3) to measure the L* and a* values ​​on the windward surface of the 304 stainless steel temperature measuring plate (2) and record the measurement point positions; take multiple measurement points to obtain multiple data points; 12) Obtain the air temperature field of the air outlet (1) of the braking resistor device from the coordinates of the measurement point and the calculated temperature value of the point.

2. The method for measuring the air temperature field at the outlet of a braking resistor device according to claim 1, characterized in that: Step 12) includes: Substitute the measured L* value into the following formula (1) to obtain the temperature value at that location; T = k1(L*)³ + k2(L*) 2 +k3L*+k4 ……(1) Where, T represents the highest temperature experienced at that location; L* is the L* value measured at this location by the spectrophotometer; k1, k2, k3, and k4 are coefficients, and the coefficient values ​​are: k1 = -1.6585 × 10 -2 , k2=2.3855, k3= -117.6304, k4=2619.8094; The air temperature field at the air outlet (1) of the braking resistor device is obtained by measuring the coordinates of the measurement point and calculating the temperature value at that point.

3. The method for measuring the air temperature field at the outlet of a braking resistor device according to claim 1, characterized in that: This also includes substituting the measured a* value into the following equation (2) to obtain the temperature value at that location. T = j1(a*) 3 +j2(a*) 2 +j3(a*)+j4……(2) Where, T represents the highest temperature experienced at that location; a* is the a* value measured at this location by the spectrophotometer; j1, j2, j3, and j4 are coefficients, and the coefficient values ​​are: j1 = 6.1406 × 10 -2 , j2= -2.7541, j3= 55.0889, j4=267.4303; The air temperature field at the outlet of the braking resistor device can be obtained from the coordinates of the measurement point and the calculated temperature value at that point.

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