Disclosure of Invention
In view of the above analysis, the present application aims to provide a device and a method for detecting a liquid in a metal container, which are used for solving the problems of low recognition rate, poor dust and water resistance or limited service life in the prior art that a heat conduction method is adopted for detecting the liquid.
The aim of the application is mainly realized by the following technical scheme:
in one aspect, the application provides a detection device for liquid in a metal container, which comprises a heating module and a temperature measuring module;
the heating module is used for heating the metal container to enable the liquid in the metal container to form a temperature field with a temperature gradient;
the temperature measuring module comprises a plurality of temperature measuring points, the distance between each temperature measuring point and the heating module is different, and the temperature difference value among the temperature measuring points is obtained by measuring the liquid temperature values at different positions of the heating module.
In one possible design, the temperature measurement module includes a first temperature measurement point and a second temperature measurement point.
In one possible design, the detection device further comprises a metal detection module and a microprocessor module;
the metal detection module is used for detecting whether a metal container exists in the detection area;
after the metal detection module detects the metal container, the state information is sent to the microprocessor module, and the microprocessor module controls the heating module to heat the metal container.
In one possible design, the detection device further comprises an alarm display module.
In one possible design, the warming module includes a plurality of heating resistors and an elastic member;
the heating resistors are arranged on one surface of the elastic piece, the elastic piece is used for supporting the heating resistors, and the shape of the elastic piece can be matched with that of the surface of the metal container;
when in use, the surface of the elastic piece provided with the heating resistor is contacted with the metal container.
In one possible design, the thermometry module includes a temperature sensor and a signal amplifier;
the temperature sensor is a thermistor or a platinum resistor;
the signal amplifier converts the variation of the temperature sensor into a voltage signal which can be detected by the microprocessor module.
In one possible design, the alarm display module includes an indicator light, a buzzer, and a liquid crystal display.
In one possible design, the warming module further includes an electronic switch that is controlled by the microprocessor module.
On the other hand, the application also provides a method for detecting the liquid in the metal container, which comprises the following steps:
placing the metal container in a detection area, and sending a state signal to a microprocessor module after the metal detection module detects the metal container;
the microprocessor module controls the heating module to heat the metal container;
the temperature measuring module detects and measures the temperature values of the liquid at different distances of the heating module and sends temperature signals to the microprocessor module;
the microprocessor module calculates the thermal conductivity coefficients of different environment temperatures or the initial temperature of the measured liquid by calculating the temperature difference values among different measuring positions, and judges the properties of the liquid.
In one possible design, the thermal conductivity is calculated as:
(T2-T1)*t*k*Δs=-(L2-L1)*Q
wherein T1 is the temperature value of the first temperature measuring point, T2 is the temperature value of the second temperature measuring point, T is the heating time, k is the heat conductivity coefficient of the measured liquid, deltas is the material sectional area, L1 is the distance between the first temperature measuring point and the heating module, L2 is the distance between the second temperature measuring point and the heating module, and Q is the heat flowing through deltas.
In one possible design, when the heat conductivity coefficient of the detected liquid is lower than a threshold value, judging the detected liquid as dangerous, and sending out dangerous prompt sound by the buzzer and displaying dangerous prompt by the liquid crystal;
when the heat conductivity coefficient of the detected liquid is above a threshold value, the detected liquid is judged to be safe liquid, the buzzer sends out a safety prompt sound, and meanwhile, the liquid crystal displays a safety prompt.
Compared with the prior art, the application has at least one of the following beneficial effects:
a) The application realizes the detection of the liquid property based on the difference of the heat conductivity coefficients of the liquids with different properties. The heat conduction is usually carried from a high-temperature object to a low-temperature object, and the heat conductivity coefficient of the liquid can be calculated by measuring the temperature values of the liquid at different positions of the heating module and the temperature difference values among the temperature measuring points, so that the liquid with different properties is measured. The influence of the environmental temperature and the liquid temperature on the heat conductivity coefficient and the test result is well solved, the accuracy of the test result is improved, and the anti-interference capability is improved.
b) The heating module provided by the application adopts a hard heating resistor, so that the heating module is not easy to damage, and the service life of the heating module is prolonged.
c) In order to avoid the situation that the hard heating resistor is not attached to the surface of the metal container, a plurality of heating resistors are arranged, and a plurality of smaller heating resistors are spliced into a larger shape. The plurality of heating resistors are arranged on one surface of the elastic piece, the elastic piece is used for supporting the plurality of heating resistors, and the elastic piece can be matched with the surface shape of the metal container.
d) In order to facilitate calculation of the distance between the heating module and the plurality of temperature measuring points, the heating module and the plurality of temperature measuring points are on the same straight line.
Additional features and advantages of the application will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the application. The objectives and other advantages of the application may be realized and attained by the structure particularly pointed out in the written description and drawings.
Detailed Description
The following detailed description of the preferred application is provided in connection with the accompanying drawings, which form a part hereof, and together with the description serve to explain the principles of the application.
Spatially relative terms, such as "under", "below", "beneath", "above", "over" and the like, may be used herein for ease of description to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, when the device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary term "below" may include both an orientation above and below, and the device may be otherwise oriented.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
The device for detecting the liquid in the metal container comprises a heating module and a temperature measuring module as shown in fig. 1 and 2; the heating module is used for heating the metal container to enable the liquid in the metal container to form a temperature field with a temperature gradient; the temperature measuring module comprises a plurality of temperature measuring points, the distance between each temperature measuring point and the heating module is different, and the temperature difference value among the temperature measuring points is obtained by measuring the temperature values of the liquid at different positions away from the heating module.
The application realizes the detection of the liquid property based on the difference of the heat conductivity coefficients of the liquids with different properties. The heat conduction is usually carried from a high-temperature object to a low-temperature object, and the heat conductivity coefficient of the liquid can be calculated by measuring the temperature values of the liquid at different positions of the heating module 1 and the temperature difference values among the temperature measuring points, so that the liquid with different properties is measured. The influence of the environmental temperature and the liquid temperature on the test result is well solved, the accuracy of the test result is improved, and the anti-interference capability is improved.
The temperature measuring module 2 includes a first temperature measuring point 201 and a second temperature measuring point 202, where the distances between the first temperature measuring point 201 and the second temperature measuring point 202 and the heating module 1 are different, and the first temperature measuring point 201 and the second temperature measuring point 202 obtain temperature difference values between the temperature measuring points by measuring the temperature values of the liquid at different positions of the heating module 1.
In order to facilitate calculation of the distance between the heating module 1 and the plurality of temperature measuring points, it is preferable that the heating module 1 and the plurality of temperature measuring points are on a straight line.
The detection device also comprises a metal detection module 4, a microprocessor module 3 and an alarm display module 5. The metal detection module 4 is used for detecting whether a metal container exists in the detection area, and the microprocessor module 3 mainly realizes signal acquisition, operation, data processing and control of an external module. After the metal detection module 4 detects the metal container, the state information is sent to the microprocessor module 3, and the microprocessor module 3 controls the heating module 1 to heat the metal container. Meanwhile, the microprocessor module 3 controls the temperature measuring module 2 to detect the temperature values of a plurality of temperature measuring points near the heating module 1; calculating the heat conductivity coefficient of the liquid according to the temperature of each temperature measuring point, and processing to obtain the property of the liquid; the test result is reported by controlling the alarm display module 5.
Preferably, the warming module 1 includes a heating resistor and an elastic member. In order to solve the problems of limited service life and easy damage of the heating film in the prior art, the heating module 1 in the application adopts a hard heating resistor and is not easy to damage, thereby prolonging the service life of the heating module 1.
In order to avoid that the hard heating resistor is not attached to the surface of the metal container, it is preferable that the heating resistor is provided in a plurality, and a plurality of smaller heating resistors are spliced into a larger shape. The plurality of heating resistors are arranged on one surface of the elastic piece, the elastic piece is used for supporting the plurality of heating resistors, and the shape of the elastic piece can be matched with that of the surface of the metal container; when the elastic piece is used, the surface of the elastic piece provided with the heating resistor is contacted with the metal container, so that the heating resistor is attached to the surface of the metal container.
The heating module 1 also comprises an electronic switch, and the microprocessor module 3 controls whether the electronic switch heats the metal container of the tested liquid or not.
The temperature measuring module 2 comprises temperature sensors and signal amplifiers, and each temperature measuring point is correspondingly provided with 1 temperature sensor and 1 signal amplifier. The temperature sensor is a thermistor or a platinum resistor; the signal amplifier converts the variation of the temperature sensor into a voltage signal which is detectable by the microprocessor module 3.
In the prior art, a thermocouple is generally used for temperature measurement, and is limited by the volume of a detection structure, a protective shell is not manufactured by the thermocouple, and the temperature measurement is directly carried out through a bare electrode with a smaller contact area, so that the waterproof capability is weak; the temperature sensor is a thermistor or a platinum resistor, has very small volume, can wrap a layer of heat conducting glue outside the temperature sensor on the manufactured structure to carry out dustproof and waterproof treatment, and solves the problem of poor dustproof and waterproof performance of the existing equipment.
The heating module 1 and the temperature measuring module 2 are arranged at lower positions so as to ensure that the heating module 1 and the temperature measuring module 2 are positioned below the liquid level 6 when detecting the liquid in the metal container.
The alarm display module 5 comprises an indicator light, a buzzer and a liquid crystal display and is used for displaying various states and whether the liquid property is dangerous in the operation of the detection device.
The detection device includes a detection ready state, a detection in-process state, and a detection result display state, and the indicator light indicates the state of the current detection flow through different colors. The liquid can be displayed as safe or dangerous in the detection result display state, and at the moment, the buzzer can give out a safe or dangerous prompt sound, and meanwhile, the liquid crystal display displays the safe or dangerous prompt.
A method for detecting liquid in a metal container comprises the following steps:
placing the metal container in a detection area, and sending a state signal to the microprocessor module 3 after the metal container is detected by the metal detection module 4;
the microprocessor module 3 controls the heating module 1 to heat the metal container;
the temperature measuring module 2 detects and measures the temperature values of the liquid at different distances of the heating module 1 and sends temperature signals to the microprocessor module 3;
the microprocessor module 3 calculates the thermal conductivity coefficients of different environment temperatures or the initial temperature of the measured liquid by calculating the temperature difference values between different measuring positions, and judges the properties of the liquid.
In order to facilitate calculation of the distance between the heating module 1 and the plurality of temperature measurement points, the heating module 1 and the plurality of temperature measurement points are on a straight line.
The calculation method of the heat conductivity coefficient is as follows:
the heating module 1 is in a straight line with the first temperature measuring point 201 and the second temperature measuring point 202, as shown in fig. 3, the distance between the heating module 1 and the first temperature measuring point 201 is L1, and the distance between the heating module 1 and the second temperature measuring point 202 is L2. After the heating of the time T, the temperature of the heating module 1 is T0, the temperature measured by the first temperature measuring point 201 is T1, the temperature measured by the second temperature measuring point 202 is T2, and T0> T1> T2.
According to fourier's law, the amount of heat per unit time that passes through a given cross-section is proportional to the rate of change of temperature and the cross-sectional area in a direction perpendicular to that cross-section, while the direction of heat transfer is opposite to the direction of temperature rise.
In the case of one-dimensional stable conduction, fourier's law can be expressed as follows:
in the method, in the process of the application,expressed as heat transferred per second through deltas, ">Is a temperature gradient consistent with the direction of heat flow, the negative sign indicates heat transfer in the direction of temperature decrease, and the proportionality coefficient k is the thermal conductivity coefficient of the material. Δs is ideally an approximately spherical surface area from the radius L1 to L2 of the warming module 1, and is a constant because L1 and L2 are fixed distances from the warming module 1.
The same measured liquid is heated for t, the two sides of the formula (1) are integrated, and the two sides are obtained at a first temperature measuring point 201 and a second temperature measuring point 202:
(T1-T0)*t*k*Δs=-L1*Q (2)
(T2-T0) T k deltas= -L2Q (3) equation (2) (3) yields:
(T2-T1)*t*k*Δs=-(L2-L1)*Q (4)
in the test, the heating power and time are constant, and the distance between the temperature measuring points is unchanged, so that the temperature difference between the two temperature measuring points is inversely proportional to the heat conductivity of the liquid for different liquids. The larger the temperature difference, the smaller the thermal conductivity of the liquid, and the smaller the temperature difference, the larger the thermal conductivity of the liquid. As shown in Table 1, the thermal conductivity of water or near water solutions is higher than that of other common hazardous liquids, and the thermal conductivity of water is about 0.6W/mK. Setting a threshold according to the heat conductivity coefficient of water, comparing the heat conductivity coefficient of the detected liquid in the metal container with the threshold, judging the detected liquid as dangerous when the heat conductivity coefficient of the detected liquid is lower than the threshold, and sending out a dangerous prompt sound by the buzzer and displaying a dangerous prompt by the liquid crystal; when the heat conductivity coefficient of the detected liquid is above a threshold value, the detected liquid is judged to be safe liquid, the buzzer sends out a safety prompt sound, and meanwhile, the liquid crystal displays a safety prompt. Illustratively, the threshold is set at 0.5W/mK.
As can be seen from the formula (4), the method is irrelevant to the ambient temperature and is only relevant to the temperature difference between the two temperature measuring points after heating, so that the influence of the ambient temperature on the test result is well solved.
TABLE 1 thermal conductivity of several common liquids
The common metal container is made of aluminum and iron; according to the requirements of the national standard for detecting the maximum wall thickness of the metal container, the iron is more than or equal to 0.2mm, and the aluminum is more than or equal to 0.3mm. Aluminum container cans typically employ 3004 aluminum with a thermal conductivity of about 163W/mK; iron container cans typically use tinplate, which has a thermal conductivity of about 80W/mK; water is the highest heat conductivity in all liquids, about 0.6W/mK. It can be seen that the thermal conductivity of common metal packages is much higher than that of water, and that the metal container walls are thin, with negligible effect of the container walls on the liquid in practical testing.
If the wall thickness of the detected metal container exceeds the national standard more, the wall thickness can influence the conduction of temperature, so that the temperature difference between the temperature measuring points is reduced, the testing precision is influenced, preferably, a third temperature measuring point is added, the distance between the third temperature measuring point and the first temperature measuring point 201 is larger, a larger temperature difference value can be detected, the liquid thermal conductivity can be calculated more accurately at the moment, and the temperature value of the second temperature measuring point 202 is used as an auxiliary reference at the moment.
The foregoing is only a preferred embodiment of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions easily contemplated by those skilled in the art within the technical scope of the present application should be included in the scope of the present application.