A method for testing the thermal energy conversion efficiency of electric heating tubes

Abstract

A method for testing the thermal energy conversion efficiency of an electric heating tube belongs to the technical field of electric heating tube detection. The method is characterized in that it comprises the following steps: measuring the weight of an electric heating tube (3); inputting a voltage at both ends of the electric heating tube (3), and detecting the temperatures of multiple temperature measuring points on the electric heating tube (3) at the same time; adjusting the input voltage so that the temperature of the temperature measuring point with the highest temperature on the electric heating tube (3) is stabilized at the test temperature, and recording the input power at this time; calculating the thermal energy conversion parameter of the electric heating tube, the thermal energy conversion parameter being the ratio of the input power to the weight of the electric heating tube (3); evaluating the electric heating tube (3) by the thermal energy conversion parameter, and if the thermal energy conversion parameter is less than 0.7, the electric heating tube (3) is qualified, and the smaller the thermal energy conversion parameter, the higher the thermal energy conversion efficiency of the electric heating tube (3). The present invention can accurately detect the thermal energy conversion efficiency of the electric heating tube and measure the service life of the electric heating tube, so as to facilitate accurate detection of the electric heating tube and facilitate detection.

Description

Technical Field

[0001] The invention discloses a method for testing the heat energy conversion efficiency of an electric heating tube, belonging to the technical field of electric heating tube detection. Background Art

[0002] The electric hot pot is a modern cooking utensil that can be used for frying, deep-frying, steaming, boiling, rinsing, stewing, simmering, braising and other processing. It can not only cook food, but also keep it warm. It is clean and hygienic to use, has no radiation, saves time and effort, and is one of the indispensable tools for modern housework. The electric hot pot is usually heated by the electric heating tube and the soaking pan at the bottom, so the quality of the electric heating tube directly affects the use of the electric hot pot. The current requirements for the electric heating tube are that the breakdown voltage of the electric heating tube must be higher than 3000V, and the service life of the electric heating tube must be greater than 3000h. Due to the long service life of the electric heating tube, the current detection of the electric heating tube usually only detects the breakdown voltage, but cannot detect the thermal efficiency and life of the electric heating tube. Due to the existence of the above problems, the quality of the electric heating tube is uneven, and the thermal efficiency of the electric heating tube cannot be evaluated. Summary of the invention

[0003] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a method for testing the thermal energy conversion efficiency of an electric heating tube, which can detect the thermal energy conversion efficiency of the electric heating tube and determine the service life of the electric heating tube according to the thermal energy conversion efficiency, and can detect the thermal energy conversion efficiency of the electric heating tube accurately and conveniently.

[0004] The technical solution adopted by the present invention to solve the technical problem is: the electric heating tube heat energy conversion efficiency testing method is characterized by comprising the following steps:

[0005] Measure the weight of the electric heating tube;

[0006] Input voltage at both ends of the electric heating tube, and detect the temperature of multiple temperature measuring points on the electric heating tube at the same time;

[0007] Adjust the input voltage so that the temperature of the highest temperature measuring point on the electric heating tube is stabilized at the test temperature, and record the input power at this time;

[0008] Calculate the heat energy conversion parameter of the electric heating tube, which is the ratio of the input power to the weight of the electric heating tube;

[0009] The electric heating tube is evaluated by the thermal energy conversion parameter. If the thermal energy conversion parameter is less than 0.7, the electric heating tube is qualified, and the smaller the thermal energy conversion parameter, the higher the thermal energy conversion efficiency of the electric heating tube.

[0010] Preferably, an electronic scale is used to measure the weight of the electric heating tube. The electronic scale is used to measure the weight of the electric heating tube, which is convenient and accurate.

[0011] Preferably, the test temperature is 300° C. The test temperature of 300° C. can ensure accurate detection and reduce the influence of ambient temperature on detection, making the detection structure more accurate.

[0012] Preferably, the temperatures of the five temperature measuring points on the electric heating tube are detected, and the five temperature measuring points are evenly spaced along the electric heating tube. By setting five temperature measuring points on the electric heating tube, the temperature of the electric heating tube can be fully detected to accurately determine the highest temperature measuring point on the electric heating tube, and it can be ensured that the temperature of the highest temperature measuring point of the electric heating tube is accurately detected when different electric heating tubes are detected.

[0013] Preferably, the electric heating tube is placed on the insulation board, and the temperature of the temperature measuring point of the electric heating tube is detected by the temperature probe. The electric heating tube is placed on the insulation board, which eliminates the influence of the external environment on the detection of the electric heating tube. The temperature of the temperature measuring point of the electric heating tube is detected by the temperature probe, and the temperature detection of the electric heating tube is accurate.

[0014] Preferably, the insulation board is rock wool, a placement board is provided at the bottom of the insulation board, and the thickness of the insulation board is 10 mm. The thickness of the insulation board is 10 mm, which can prevent the heat generated by the electric heating pipe from being transferred downward.

[0015] Preferably, the method further comprises designing the shape of the electric heating tube according to the heat energy conversion parameters so that the cross section of the electric heating tube gradually narrows from top to bottom. The cross section of the electric heating tube gradually narrows from top to bottom to ensure that the thickness of the magnesium oxide powder is reasonable, which can ensure both the electrical insulation performance of the electric heating tube and the heat energy conversion efficiency of the electric heating tube.

[0016] Preferably, the top of the electric heating tube is arranged horizontally, and the bottom is an arc shape with a convex middle portion, which can ensure a large contact area between the electric heating tube and the soaking pan, so that the heat emitted by the electric heating tube can be quickly transferred to the soaking pan, so that the thermal efficiency of the electric heating pot is high, and the electric heating tube is conveniently welded to the soaking pan, and the working surface of the electric heating tube has the largest contact area with the soaking pan, and the bottom is coaxial with the electric heating wire, which can improve the breakdown resistance of the electric heating tube.

[0017] The parameter value of converting electrical energy into thermal energy during the operation of the electric heating tube is an important parameter that reflects the quality and life of the electric heating tube. Magnesium oxide powder is used to fill and compact the space between the heating wire and the inner wall of the electric heating tube, which plays the role of electrical insulation and heat conduction between the heating wire and the tube wall. Under a certain insulation strength, the smaller the thermal resistance of the magnesium oxide powder, the better the thermal conductivity of the electric heating tube, and the smaller the temperature difference between the heating wire and the tube wall, the longer the life of the electric heating tube, and the higher the thermal energy conversion efficiency of the electric heating tube.

[0018] Under the condition that the diameter and length of the electric heating tube are constant, the greater the thickness of the magnesium oxide powder in the electric heating tube, the better the electrical insulation performance of the electric heating tube, the greater the temperature difference between the electric heating wire and the tube wall of the electric heating tube, the lower the thermal energy conversion efficiency of the electric heating tube, and the shorter the life of the electric heating tube; the smaller the thickness of the magnesium oxide powder in the electric heating tube, the smaller the temperature difference between the electric heating wire and the tube wall of the electric heating tube, the higher the thermal energy conversion efficiency of the electric heating tube, the longer the life of the electric heating tube, but the worse the electrical insulation performance of the electric heating tube. At present, there is no parameter that can balance the above-mentioned contradictions. The inventor defines the thermal energy conversion parameter, which is the ratio of the input power to the weight of the electric heating tube, and uses the magnesium oxide powder and the input power as the detection quantity to test the thermal energy conversion efficiency of the electric heating tube, and detects the service life of the electric heating tube by the temperature difference between the heating wire and the inner wall of the electric heating tube, which can accurately realize the detection of the thermal energy conversion efficiency and life of the electric heating tube.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The electric heating tube heat energy conversion efficiency test method measures the temperature of the electric heating tube, that is, the temperature of the tube wall of the electric heating tube. The temperature of the heating wire in the electric heating tube can be measured by input power, so that the temperature of the tube wall of the electric heating tube reaches the test temperature. By comparing the temperature of the heating wire of the electric heating tube, the heat conversion efficiency of the electric heating tube can be judged, and the service life of the electric heating tube can be measured according to the temperature difference between the heating wire and the tube wall. The heat energy conversion parameter comprehensively evaluates the weight of the electric heating tube with the input power of the heating wire, so as to accurately detect the heat energy conversion efficiency of the electric heating tube and measure the service life of the electric heating tube, which is convenient for accurate detection of the electric heating tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a three-dimensional schematic diagram of the electric heating tube detection equipment.

[0022] Figure 2 It is a three-dimensional schematic diagram of the electric heating tube.

[0023] Figure 3 It is a cross-sectional schematic diagram of the electric heating tube.

[0024] In the figure: 1, placement board 2, insulation board 3, electric heating tube 4, temperature probe 5, magnesium oxide powder 6, electric heating wire. DETAILED DESCRIPTION

[0025] Figures 1 to 3 The best embodiment of the present invention is shown below in conjunction with the attached Figures 1 to 3 The present invention is further described.

[0026] The present invention is further described below in conjunction with specific embodiments. However, people familiar with the art should understand that the detailed description given here in conjunction with the drawings is for better explanation, and the structure of the present invention necessarily exceeds these limited embodiments. For some equivalent replacement schemes or common means, they are no longer described in detail herein, but still belong to the scope of protection of the present application.

[0027] like Figure 1 As shown: the electric heating tube heat energy conversion efficiency test device includes a placement plate 1, a heat insulation plate 2, a temperature probe 4, a power meter, a voltmeter and a voltage regulator. The placement plate 1 is a metal plate, the placement plate 1 is square, the thickness of the placement plate 1 is 2mm, the heat insulation plate 2 is arranged on the upper side of the placement plate 1, the heat insulation plate 2 is rock wool, the heat insulation plate 2 is also square, and the side length of the heat insulation plate 2 is less than the side length of the placement plate 1, and the thickness of the heat insulation plate 2 is 10mm.

[0028] The electric heating tube 3 to be tested is placed on the insulation board 2, and the electric heating tube 3 is located directly above the insulation board 2. The temperature of the temperature measuring point of the electric heating tube 3 is tested by the temperature probe 4. In this embodiment, there are five temperature measuring points evenly spaced along the electric heating tube 3, and a temperature probe 4 is set at each temperature measuring point. The temperature of the five temperature measuring points of the electric heating tube 3 is tested by the temperature probe 4 at the same time.

[0029] The input end of the voltage regulator is connected to the alternating current, and the output end is connected to both ends of the electric heating tube 3. The power meter and the voltmeter are both connected to the electric heating tube 3, and the input voltage and input power of the electric heating tube are detected.

[0030] A method for testing the heat energy conversion efficiency of an electric heating tube comprises the following steps:

[0031] The weight of the electric heating tube 3 is measured.

[0032] The weight of the electric heating tube is measured by an electronic scale.

[0033] A voltage is inputted at both ends of the electric heating tube 3, and the temperatures of multiple temperature measuring points on the electric heating tube 3 are detected simultaneously.

[0034] Voltage is input to both ends of the electric heating tube 3 through the voltage regulator, and the temperatures of five temperature measuring points on the electric heating tube 3 are measured simultaneously through the temperature probe 4 .

[0035] The input voltage is adjusted so that the temperature of the highest temperature measuring point on the electric heating tube 3 is stabilized at the test temperature, and the input power at this time is recorded.

[0036] The input voltage of the electric heating tube 3 is adjusted by the voltage regulator until the temperature of the highest temperature measuring point on the electric heating tube 3 is stabilized at the test temperature. In this embodiment, the test temperature is 300°C. When the temperature of the temperature measuring points of the electric heating tube 3 is detected, five temperature measuring points are set, and the temperature of the electric heating tube 3 can be comprehensively measured to determine the highest temperature point. When the temperature of the highest temperature point is stabilized at 300°C, the test requirements are met. At this time, the power on the power meter is recorded, that is, the input power of the electric heating tube 3.

[0037] The heat energy conversion parameter of the electric heating tube is calculated, where the heat energy conversion parameter is the ratio of the input power to the weight of the electric heating tube 3 .

[0038] The calculation formula of thermal energy conversion parameter K is as follows:

[0039] K = P / G;

[0040] Wherein, P is the input power of the electric heating tube 3, the unit is w; G is the weight of the electric heating tube 3, the unit is g.

[0041] The electric heating tube 3 is evaluated by the heat energy conversion parameter. If the heat energy conversion parameter is less than 0.7, the electric heating tube 3 is qualified, and the smaller the heat energy conversion parameter is, the higher the heat energy conversion efficiency of the electric heating tube 3 is.

[0042] The weight side detection of the electric heating tube 3 can be performed before the temperature detection at the temperature measuring point and the input power detection, or it can be performed after the temperature detection at the temperature measuring point and the power detection.

[0043] like Figure 2~3 As shown: the electric heating tube heat energy conversion efficiency test method also includes designing the shape of the electric heating tube 3 according to the heat energy conversion parameters so that the cross section of the electric heating tube 3 gradually narrows from top to bottom.

[0044] The electric heating tube 3 is enclosed in a circular ring shape, and the end of the electric heating tube 3 is bent downward, which can avoid obstruction to the welding between the electric heating tube 3 and the heat soaking plate, and facilitate the wiring of the electric heating tube 3. The electric heating tube 3 is an aluminum tube. The heating wire 6 is arranged in the electric heating tube 3, and the electric heating tube 3 is filled with magnesium oxide powder 5, which has good thermal conductivity and good insulation performance.

[0045] The top of the electric heating tube 3 is horizontal, and both sides of the top of the electric heating tube 3 are gradually inclined inward from top to bottom, so that the middle part of the electric heating tube 3 is a cone that gradually narrows from top to bottom, and the bottom of the electric heating tube 3 is an arc shape with a convex middle part, and the two sides of the bottom of the electric heating tube 3 are tangent to the corresponding sides of the middle part respectively, and the heating wire 6 is coaxially arranged with the bottom of the electric heating tube 3.

[0046] According to the heat energy conversion parameters, the smaller the temperature difference between the heating wire 6 and the tube wall of the electric heating tube 3, the smaller the heat energy conversion parameters, the longer the life of the heating wire 6, and the higher the heat energy conversion efficiency. Therefore, when designing the electric heating tube 3, the heat transferred from the heating wire 6 to the electric heating tube 3 must be quickly transferred out, while ensuring a reasonable thickness of the magnesium oxide powder 5 to ensure the electrical insulation performance of the electric heating tube 3.

[0047] The following table shows the test data of electric heating tubes of different specifications:

[0048] .

[0049] The inventors respectively passed 220V AC power to the 13 groups of electric heating tubes 3 in the above table and conducted life tests. The electric heating tubes 3 corresponding to groups 1 to 11 still worked stably after being continuously powered on for 3000 hours, while the lifespans of the electric heating tubes 3 corresponding to groups 12 and 13 were much less than 3000 hours. The electric heating tube corresponding to group 11 in the above table is the electric heating tube 3 with the cross-sectional shape determined in this embodiment.

[0050] Through the above experiments, it can be concluded that under the condition that the model of the electric heating tube 3 is certain, when the heat energy conversion parameter is less than 0.7, the input power is small, and the temperature difference between the tube wall of the electric heating tube 3 and the electric heating wire 6 is small. At this time, the heat energy conversion efficiency of the electric heating tube 3 is high, and the service life of the electric heating wire 6 is long, that is, the service life of the electric heating tube 3 is long. Under the condition that the model of the electric heating tube 3 is certain, when the heat energy conversion parameter is greater than 0.7, that is, the amount of magnesium oxide powder in the electric heating tube 3 is large, the speed at which the heat of the electric heating wire 6 is transferred to the electric heating tube 3 is slow, that is, the temperature difference between the electric heating wire 6 and the tube wall of the electric heating tube 3 is large, and the heat energy conversion efficiency of the electric heating tube 3 is low, and the electric heating wire 6 is easily burned out, and the service life of the electric heating wire 6 is short, that is, the service life of the electric heating tube 3 is short.

[0051] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. A method for testing the thermal energy conversion efficiency of an electric heating tube, characterized in that: The steps include: Measuring the weight of the electric heating tube (3); Inputting a voltage at both ends of the electric heating tube (3) and detecting the temperatures of a plurality of temperature measuring points on the electric heating tube (3) at the same time; Adjust the input voltage so that the temperature of the highest temperature measuring point on the electric heating tube (3) is stabilized at the test temperature, and record the input power at this time, wherein the test temperature is 300° C.; Calculating the heat energy conversion parameter of the electric heating tube, the heat energy conversion parameter being the ratio of the input power to the weight of the electric heating tube (3); The electric heating pipe (3) is evaluated by means of a heat energy conversion parameter; if the heat energy conversion parameter is less than 0.7, the electric heating pipe (3) is qualified; and the smaller the heat energy conversion parameter, the higher the heat energy conversion efficiency of the electric heating pipe (3).

2. The method for testing the thermal energy conversion efficiency of an electric heating tube according to claim 1, characterized in that: The weight of the electric heating tube (3) is measured using an electronic scale.

3. The method for testing the thermal energy conversion efficiency of an electric heating tube according to claim 1, characterized in that: The temperatures of five temperature measuring points on the electric heating tube (3) are detected, and the five temperature measuring points are evenly spaced along the electric heating tube (3).

4. The method for testing the thermal energy conversion efficiency of an electric heating tube according to claim 1 or 3, characterized in that: The electric heating tube (3) is placed on the heat insulation board (2), and the temperature of the temperature measuring point of the electric heating tube (3) is detected by a temperature probe (4).

5. The method for testing the heat energy conversion efficiency of an electric heating tube according to claim 4, characterized in that: The thermal insulation board (2) is made of rock wool, a placement board (1) is provided at the bottom of the thermal insulation board (2), and the thickness of the thermal insulation board (2) is 10 mm.

6. The method for testing the heat energy conversion efficiency of an electric heating tube according to claim 1, characterized in that: The method further comprises designing the shape of the electric heating tube (3) according to the heat energy conversion parameter, so that the cross section of the electric heating tube (3) gradually narrows from top to bottom.

7. The method for testing the heat energy conversion efficiency of an electric heating tube according to claim 6, characterized in that: The top of the electric heating tube (3) is arranged horizontally, and the bottom is in the shape of an arc with a convex middle portion.

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