Short-circuit molten bead energy measuring device and method based on calorimetric method

Abstract

The invention discloses a calorimetric method-based short-circuit molten bead energy measurement method, which comprises the following steps of S1, adding a liquid heat exchange working medium with a preset mass into a measurement container, and measuring the initial temperature of the heat exchange working medium; s2, placing the short-circuit molten beads in a measuring container, ensuring that the molten beads are completely immersed by the heat exchange working medium, and measuring the final temperature and the final mass of the heat exchange working medium; s3, the molten beads are taken out, the heat exchange working medium on the surfaces of the molten beads is cleaned, and the mass of the molten beads is measured; and S4, the energy of the molten beads is calculated by calculating the gasification heat absorption capacity and the temperature rise heat absorption capacity of the heat exchange working medium. Meanwhile, the invention provides a measuring device adopted by the short-circuit molten bead energy measuring method, and the measuring device comprises a heat insulation measuring container, a liquid heat exchange working medium, a stirring device, a temperature sensor, a mass sensor and a measuring device support. According to the invention, the energy of the high-temperature short-circuit molten bead can be directly and accurately measured.

Description

Technical Field

[0001] The present invention relates to the field of fire safety technology, and in particular to a short-circuit molten bead energy measurement device and method based on calorimetry. Background Art

[0002] According to data from the Ministry of Emergency Management, electrical fires in my country account for about 30% of the total number of fires each year, and the number of fires is increasing year by year. Therefore, the number of electrical fires in my country is increasing year by year. In electrical fires, high-temperature molten beads that splash out due to short circuits are an important source of ignition. The temperature of the molten beads is usually as high as 2000-3000 ℃, and splashing onto surrounding combustibles may ignite the combustibles and cause a fire.

[0003] Studies have shown that the energy of the molten bead is an important parameter that affects whether the combustible material can be ignited. The energy of the molten bead is determined by the size and temperature of the molten bead. The size of the molten bead can usually be obtained by directly measuring the cooled molten bead, but there is no simple and effective method to measure the temperature of the molten bead. On the one hand, the temperature of the molten bead is extremely high, exceeding the range of direct measurement sensors such as thermocouples and thermocouples. On the other hand, the surface emissivity of the molten bead is not easy to obtain, and it is difficult to measure its temperature with an infrared thermal imager. Therefore, there is currently a lack of a simple and effective method to accurately measure the energy of a short-circuit molten bead. Summary of the invention

[0004] In order to make up for the deficiencies of the prior art, the embodiments of the present application propose a short-circuit molten bead energy measurement method and device based on calorimetry to solve the problems existing in the prior art.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] A short-circuit molten bead energy measuring device comprises an insulated measuring container, a liquid heat exchange medium, a stirring device, a temperature sensor, a mass sensor and a measuring device bracket; the heat exchange medium is a liquid with known specific heat capacity, latent heat of vaporization and boiling point; the heat exchange medium is installed in the insulated measuring container; the stirring rotor of the stirring device is installed in the bottom of the cavity of the insulated measuring container; a flat plate with mesh is installed on the upper part of the stirring rotor, which divides the heat exchange medium in the insulated measuring container into a molten bead heat test area on the upper part of the flat plate and a stirring area on the lower part; the temperature sensor is installed on the measuring device bracket, and its probe is placed in the molten bead heat test area of ​​the heat exchange medium; the test end of the mass sensor is connected to the insulated measuring container, and the fixed end is connected to the measuring device bracket.

[0007] A method for measuring the energy of a short-circuit molten bead based on calorimetry, using the above-mentioned device, comprises the following steps:

[0008] Step S1: Add a preset mass into the measuring container Liquid heat exchange medium, determine the initial temperature of the heat exchange medium ;

[0009] Step S2: Place the short-circuit molten bead in a measuring container to ensure that the molten bead is completely immersed in the heat exchange medium, and measure the final temperature of the heat exchange medium. and final quality ;

[0010] Step S3: Take out the molten bead and clean the heat exchange medium on its surface, and measure the quality of the molten bead. ;

[0011] Step S4: Calculate the heat absorbed by the heat exchange medium during gasification and heat absorption , and then calculate the energy of the molten bead .

[0012] As a further technical solution of the present invention: the initial temperature of the heat exchange medium in the steps S1 and S2 is determined and final temperature When the heat exchange medium is heated, it is necessary to perform thermal balance treatment on the heat exchange medium. During the thermal balance treatment, the heat exchange medium is fully stirred by a stirring device with a preset speed, and the temperature of the heat exchange medium is measured in real time. When the temperature error of the heat exchange medium does not exceed 0.5℃ within 3s, the heat exchange medium is regarded as being in thermal balance, and the measured temperature value is regarded as a valid measurement value.

[0013] As a further technical solution of the present invention: the predetermined mass of the heat exchange medium measured in steps S1 and S2 is and final quality When the mass error of the internal heat exchange medium does not exceed 0.5 g, it is regarded as a valid measurement value of the mass.

[0014] As a further technical solution of the present invention: the heat absorption of the heat exchange medium by gasification in step S4 is: ,in are the specific heat capacity, boiling point and latent heat of vaporization of the heat exchange medium respectively; the heat absorbed by the heat exchange medium during heating is .

[0015] One or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages:

[0016] The short-circuit molten bead energy measurement method and device of the present invention can utilize liquid heat exchange medium to directly contact the molten bead, absorb the energy of the molten bead, and calculate the energy of the short-circuit molten bead by measuring the heat absorption of gasification and temperature rise of the heat exchange medium. The invention can directly measure the energy of the molten bead in the short-circuit test, the device used is easy to operate, the measurement method is simple and accurate, and can provide measurement technical support for studying the characteristics of the short-circuit molten bead and its ability to ignite combustibles. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a flow chart of the method of the present invention;

[0018] Figure 2 It is a schematic diagram of the device of the present invention;

[0019] In the figure: 1-heat exchange medium; 2-insulated measuring container; 3-temperature sensor; 4-insulating layer of measuring container; 5-molten bead; 6-plate with mesh; 7-stirring rotor; 8-magnetic stirrer; 9-mass sensor; 10-bracket; 11-temperature sensor recorder. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] In the description of the present invention, it should be noted that specific physical quantity values ​​such as "inner diameter 30 mm", "insulation cotton 5 mm thick", "distance 10 mm", etc. are preferred parameters based on the present embodiment, which are only for the purpose of clearly describing the present invention, rather than indicating or implying that the physical quantities involved can only be these values, and therefore cannot be understood as limitations on the present invention.

[0022] In the description of the present invention, it should be noted that the terms "horizontal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicating directions or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings of this example, and are only for the purpose of clearly describing the present invention, rather than indicating or implying that the referred device or element must have a specific orientation, be installed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0023] In the description of the present invention, unless otherwise specified, it should be noted that the terms "inserted", "fixed", "supported", "equipped with", "placed", "connected", etc. should be understood in a broad sense. For example, in some situations, it can be understood that multiple components are directly connected or connected through an intermediate medium, which can be fixedly connected or non-fixedly placed. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances, and they should not be understood as limitations on the present invention.

[0024] A method for measuring the energy of a short-circuit molten bead, such as Figure 1 As shown, the following steps are included:

[0025] Step S1: Add a preset mass into the measuring container Liquid heat exchange medium, determine the initial temperature of the heat exchange medium ;

[0026] Step S2: Place the short-circuit molten bead in a measuring container to ensure that the molten bead is completely immersed in the heat exchange medium, and measure the final temperature of the heat exchange medium. and final quality ;

[0027] Step S3: Take out the molten bead and clean the heat exchange medium on its surface, and measure the quality of the molten bead. ;

[0028] Step S4: Calculate the heat absorbed by the heat exchange medium during gasification and heat absorption , and then calculate the energy of the molten bead .

[0029] When determining the initial temperature and final temperature of the heat exchange working fluid as described in steps S1 and S2, the heat exchange working fluid needs to be subjected to thermal equilibrium treatment. During the thermal equilibrium treatment, the heat exchange working fluid is fully stirred by a stirring device at a preset speed, and the temperature of the heat exchange working fluid is measured in real time. When the temperature error of the heat exchange working fluid does not exceed 0.5°C within 3 seconds, the heat exchange working fluid is deemed to be in thermal equilibrium, and the measured temperature value at this time is deemed to be a valid measurement value.

[0030] When determining the preset mass and final mass of the heat exchange medium in steps S1 and S2, it is necessary to turn off the stirring device and let the heat exchange medium stand for a period of time. When the mass error of the internal heat exchange medium does not exceed 0.5 g, it is regarded as a valid measurement value of the mass.

[0031] The heat absorption amount of the heat exchange medium during gasification determined in step S4 is: ,in are the specific heat capacity, boiling point and latent heat of vaporization of the heat exchange medium respectively; the heat absorbed by the heat exchange medium during heating is .

[0032] The present invention also provides a short-circuit molten bead energy measuring device, which is a measuring device used in the short-circuit molten bead energy measuring method. Figure 2 As shown, it includes a thermal insulation measuring container 2, a liquid heat exchange medium 1, stirring devices 7 and 8, a temperature sensor 3, a mass sensor 9, and a measuring device bracket 10.

[0033] The heat exchange medium 1 is a liquid with known specific heat capacity, latent heat of vaporization and boiling point; the heat exchange medium 1 is installed in the heat-insulating measuring container 2; the stirring rotor 7 of the stirring device 7 and 8 is installed at the bottom of the cavity of the heat-insulating measuring container 2; the stirring rotor 7 is provided with a plate 6 with mesh on the upper part of the stirring rotor 7, which divides the heat exchange medium 1 in the heat-insulating measuring container 2 into a molten bead heat test area 12 on the upper part of the plate and a stirring area 13 on the lower part;

[0034] The temperature sensor 3 is installed on the measuring device bracket 10, and its probe is placed in the molten bead heat test area 12 of the heat exchange medium 1; the test end 14 of the mass sensor 9 is connected to the insulated measuring container 2, and the fixed end 15 is connected to the measuring device bracket 10.

[0035] The insulated measuring container 2 is a circular open cup container, and the cup wall and cup bottom are insulated structures; the stirring devices 7 and 8 are magnetic stirring devices; the stirring rotor 7 is a shuttle magnet; the temperature sensor 3 is a thermocouple, and the measurement accuracy is not less than 0.1 ° C; the measurement accuracy of the mass sensor 9 is not less than 0.1 g.

[0036] Example:

[0037] As attached Figure 1 In this embodiment, preferably, the inner cavity of the thermal insulation measuring container 2 adopts a flat bottom glass test tube with an inner diameter of 30 mm and a height of 100 mm, and the side wall and the bottom of the test tube are wrapped with a layer of thermal insulation cotton with a thickness of 5 mm as the thermal insulation layer 4 of the thermal insulation measuring container. The heat exchange medium 1 adopts distilled water, and its specific heat capacity, boiling point and latent heat of vaporization are 4182 J / kg respectively. K, 100 ℃ and, the heat exchange medium 1 is placed in the thermal insulation measuring container 2, and the distance between the upper surface of the heat exchange medium 1 and the upper surface of the thermal insulation measuring container 2 is 10 mm.

[0038] The stirring devices 7 and 8 adopt the model of Shanghai Shangyi magnetic stirrer: SN-MST-2, which has a net weight of only 200 g and a rotation speed of 60-1500 rpm. The rotation speed of this embodiment is 800 rpm; the thermal insulation measurement container 2 is horizontally placed on the power device 8 of the magnetic stirrer 7 and 8, and the stirring rotor 7 is a shuttle rotor with a length of 20 mm, which is placed at the bottom of the cavity of the thermal insulation measurement container 2. A flat plate 6 with mesh is installed on the upper part of the stirring rotor 7. The flat plate 6 is made of acrylic material and has small holes with a diameter of 1 mm. The lower part of the flat plate 6 is supported by an acrylic ring with an outer diameter of 30 mm and an inner diameter of 25 mm; the flat plate 6 divides the heat exchange medium 1 in the thermal insulation measurement container 2 into a molten bead heat test area 12 on the upper part of the flat plate and a stirring area 13 on the lower part. The heights of the molten bead heat test area 12 and the stirring area 13 on the lower part are 7 mm and 2 mm respectively.

[0039] The temperature sensor 3 uses a K-type thermocouple with an outer diameter of 1 mm and a node diameter of 0.5 mm. It is matched with an NI data collector to realize real-time temperature collection and storage, and the temperature measurement accuracy is 0.04%~0.07%. The thermocouple is fixed on the test bracket 10, inserted into the heat exchange medium 1, and perpendicular to the liquid surface of the heat exchange medium 1; a total of 3 thermocouples are selected, 2 of which are arranged on one side of a certain diameter of the circular horizontal section of the inner cavity of the thermal insulation measurement container 2, 5 mm away from the center of the horizontal section of the thermal insulation measurement container 2, and the vertical distances between their nodes and the flat plate 6 with mesh holes are 10 mm and 60 mm respectively, and another thermocouple is arranged on the other side of the same diameter of the circular horizontal section of the inner cavity of the thermal insulation measurement container 2, 5 mm away from the center of the horizontal section of the thermal insulation measurement container 2, and the vertical distance between its nodes and the flat plate 6 with mesh holes is 10 mm; during the measurement process, the average value of the 3 thermocouples is used as the temperature measurement value.

[0040] Preferably, the mass sensor 9 adopts a Sertolius electronic balance with a measuring range of 6 kg and a measuring accuracy of 0.01 g. It can be connected to a computer to collect and save real-time mass measurement values ​​through special software; the insulated measuring container 2, magnetic stirring devices 7 and 8 are placed horizontally on the electronic balance, and the lower part of the measuring bracket 10 is fixed on the housing of the electronic balance.

[0041] As attached Figure 2 In this embodiment, the specific steps of measuring the energy of the molten bead are as follows:

[0042] 1. Add mass to the measuring container = 10 g of distilled water as the heat exchange medium and let it stand for about 5 minutes;

[0043] 2. Turn on the temperature acquisition device, record the distilled water temperature, and compare the temperature change within 3 consecutive seconds. If it is greater than 0.5℃, continue to stand and repeat this step. If it is less than 0.5℃, record the temperature as the initial temperature of the heat exchange medium. And proceed to the next step;

[0044] 3. Turn on the magnetic stirrer and set the speed to 800 rpm;

[0045] 4. Place the short-circuit molten bead into distilled water and ensure that it is completely immersed in it. Continue to stir the distilled water for about 1 minute;

[0046] 5. Turn on the temperature acquisition device, record the distilled water temperature, and compare the temperature change within 3 consecutive seconds. If it is greater than 0.5℃, continue stirring and repeat this step. If it is less than 0.5℃, record the temperature as the final temperature of the heat exchange medium. And proceed to the next step;

[0047] 6. Turn off the magnetic stirrer, let the measuring system stand still, turn on the electronic balance, record the mass of the measuring system, and compare the mass change within 3 consecutive seconds. If it is greater than 0.1 g, continue to stand still and repeat this step. If it is less than 0.1 g, record the mass as the final mass of the heat exchange medium. And proceed to the next step;

[0048] 7. Take out the molten beads and use a hot air blower to dry the surface water stains. Use an analytical balance to measure the mass of the molten beads and record it as ;

[0049] 8. Calculate the heat absorption of the heat exchange medium by the following formula and heat absorption , and then calculate the energy of the molten bead :

[0050]

[0051]

[0052]

[0053] in, They are the specific heat capacity, boiling point and latent heat of vaporization of the heat exchange medium respectively.

[0054] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0055] In addition, it should be understood that although this specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment have also been appropriately combined to form other implementation modes that are easy for those skilled in the art to understand.

Claims

1. A short-circuit molten bead energy measuring device, comprising a heat-insulating measuring container, a liquid heat exchange medium, a stirring device, a temperature sensor, a mass sensor, and a measuring device bracket, characterized in that: The heat exchange working fluid is a liquid with known specific heat capacity, latent heat of vaporization and boiling point; the heat exchange working fluid is installed inside an insulated measuring container; the stirring rotor of the stirring device is installed at the bottom of the insulated measuring container cavity; a flat plate with mesh is installed on the top of the stirring rotor, which divides the heat exchange working fluid in the insulated measuring container into a molten bead heat test area on the top of the flat plate and a stirring area on the bottom; the temperature sensor is installed on the measuring device bracket, and its probe is placed in the molten bead heat test area of ​​the heat exchange working fluid; the test end of the mass sensor is connected to the insulated measuring container, and the fixed end is connected to the measuring device bracket.

2. A method for measuring the energy of a short-circuit melt bead based on calorimetry, using the device described in claim 1, comprising the following steps: Step S1: Add a preset mass into the measuring container Liquid heat exchange medium, determine the initial temperature of the heat exchange medium ; Step S2: Place the short-circuit molten bead in a measuring container to ensure that the molten bead is completely immersed in the heat exchange medium, and measure the final temperature of the heat exchange medium. and final quality ; Step S3: Take out the molten bead and clean the heat exchange medium on its surface, and measure the quality of the molten bead. ; Step S4: Calculate the heat absorbed by the heat exchange medium during gasification and heat absorption , and then calculate the energy of the molten bead .

3. A method for measuring short-circuit molten bead energy based on calorimetry according to claim 2, characterized in that: The initial temperature of the heat exchange medium in steps S1 and S2 is determined and final temperature When the heat exchange medium is heated, it is necessary to perform thermal balance treatment on the heat exchange medium. During the thermal balance treatment, the heat exchange medium is fully stirred by a stirring device with a preset speed, and the temperature of the heat exchange medium is measured in real time. When the temperature error of the heat exchange medium does not exceed 0.5℃ within 3s, the heat exchange medium is regarded as being in thermal balance, and the measured temperature value is regarded as a valid measurement value.

4. The method for measuring the energy of a short-circuit molten bead based on calorimetry according to claim 2, characterized in that: Determining the preset mass of the heat exchange medium in steps S1 and S2 and final quality When the mass error of the internal heat exchange medium does not exceed 0.5 g, it is regarded as a valid measurement value of the mass.

5. The method for measuring the energy of a short-circuit molten bead based on calorimetry according to claim 2, characterized in that: The heat absorption of the heat exchange medium during gasification as measured in step S4 is: ,in are the specific heat capacity, boiling point and latent heat of vaporization of the heat exchange medium respectively; the heat absorbed by the heat exchange medium during heating is .

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