Supercooled water identification and elimination device and method for chilled mirror type precise dew-point instrument

Abstract

The invention discloses a supercooled water identification and elimination device and method for a chilled mirror type precise dew-point meter, and the device comprises a light-emitting tube, a photoelectric receiver, a voltage collector, a temperature collector, a maximum refrigeration switch, and a controller. The voltage collector collects the voltage of the photoelectric signal from the photoelectric receiver, and the temperature collector collects the temperature of the mirror surface; the controller judges whether the possibility of supercooled water exists or not according to whether the temperature of the mirror surface at the dew formation moment is smaller than or equal to 0 DEG C, if yes, the maximum refrigeration switch is turned on, the mirror surface temperature is rapidly reduced until the mirror surface temperature is lower than the dew point temperature by-20 DEG C, the supercooled water is eliminated, and then the voltage value of the photoelectric signal is controlled to be a voltage target value. And an accurate frost point temperature is measured by a dew-point meter. The cold mirror surface supercooled water below 0 DEG C can be identified and eliminated, the measurement accuracy of the frost point temperature is effectively improved, and the measurement accuracy of the cold mirror type precise dew-point instrument is improved.

Description

Technical Field

[0001] The invention belongs to the field of thermal metrology, and in particular relates to a supercooled water identification and elimination device and method for a cold mirror type precision dew point meter. Background Art

[0002] Dew point temperature refers to the temperature when the gas is cooled under certain pressure and the water vapor in the gas begins to condense into water droplets (or condense into ice crystals). When this temperature is below 0°C, it is also called frost point temperature. Dew point / frost point temperature is a parameter that characterizes the moisture content in the gas. Its accurate measurement is of great significance in the fields of aviation, aerospace, petrochemicals, etc. The chilled mirror precision dew point meter is an instrument used to measure the dew point / frost point temperature of the gas. It plays an important role in my country's humidity measurement and transmission system. It can be used as a primary / secondary standard instrument, and can also be used for high-precision dew point / frost point measurement of the gas.

[0003] When the chilled mirror precision dew point meter measures the frost point temperature of the gas (below 0℃), due to the lack of condensation nuclei on the condensation mirror surface, water molecules can exist in the form of liquid water without forming ice crystals. This phenomenon is called the supercooled water phenomenon. The temperature range of supercooled water is between -40℃ and 0℃. In nature, supercooled water is extremely unstable and will spontaneously turn into ice crystals, but in the chilled mirror precision dew point meter, this phenomenon can last for several hours. Since at the same temperature, the saturated water vapor partial pressure of the cold mirror surface covered by ice crystals and the cold mirror surface covered by supercooled water is different, it will cause a large error in measurement. If the chilled mirror precision dew point meter does not have the ability to identify and eliminate supercooled water, the frost point temperature measurement error will be as high as 2℃, which significantly affects the measurement accuracy of the chilled mirror precision dew point meter. Summary of the invention

[0004] The purpose of the present invention is to address the problem that a chilled mirror type precision dew point meter cannot identify and eliminate supercooled water, thereby causing large measurement errors. The present invention provides a supercooled water identification and elimination device and method for a chilled mirror type precision dew point meter, which can realize the identification and elimination of supercooled water on the cold mirror surface below 0°C, effectively improve the measurement accuracy of the frost point temperature, and improve the measurement accuracy of the chilled mirror type precision dew point meter.

[0005] In order to achieve the above-mentioned object, one aspect of the present invention provides a supercooled water identification and elimination device for a cold mirror type precision dew point meter, comprising a light emitting tube, a photoelectric receiver, a voltage collector, a temperature collector, a maximum cooling switch and a controller, wherein the light emitting tube is used to emit light to the mirror surface of the cold mirror type precision dew point meter, the photoelectric receiver is used to receive the mirror surface reflected light to generate a photoelectric signal, the voltage collector is used to collect the voltage of the photoelectric signal from the photoelectric receiver, the temperature collector is used to collect the mirror surface temperature, and the maximum cooling switch is used to quickly cool the mirror surface;

[0006] The controller is used to set the voltage target value of the photoelectric signal, and judge whether there is a possibility of supercooled water according to whether the temperature of the mirror is less than or equal to 0°C at the time of dew condensation. If so, the maximum cooling switch is turned on to quickly reduce the mirror temperature until the mirror temperature is lower than the dew point temperature of -20°C to eliminate supercooled water. Then, the voltage value of the photoelectric signal is controlled at the voltage target value, and the accurate frost point temperature is measured by the cold mirror type precision dew point meter.

[0007] Another aspect of the present invention provides a method for identifying and eliminating supercooled water for a chilled mirror precision dew point meter, using the above-mentioned device to identify and eliminate supercooled water, comprising:

[0008] Collect the initial voltage value U0 of the photoelectric signal. At this time, the voltage is at the maximum value U 0max and the minimum value U 0min Fluctuate between

[0009] Set voltage target value U target =U aver -ΔU, where ΔU is the voltage fluctuation value, U aver is the average voltage, ΔU=U 0max -U 0min , U aver =(U 0max +U 0min ) / 2;

[0010] Input the sample gas into the cold mirror precision dew point meter, collect the current voltage value U, and judge whether the mirror surface is condensed by the change of the current voltage value U. If the voltage value U does not exceed U 0max ~U 0min If the mirror is within the range, it is judged that there is no condensation on the mirror, and the refrigerator is turned on to cool until the voltage value U is lower than the minimum value U 0min , judge that the mirror surface has condensation;

[0011] Determine whether the current mirror temperature T0 is less than or equal to 0°C. If the current mirror temperature is less than or equal to 0°C, it is determined that there is supercooled water on the mirror, and the maximum cooling switch is turned on to quickly reduce the mirror temperature until the mirror temperature T≤T0-20°C to eliminate the supercooled water;

[0012] The voltage value of the photoelectric receiver is controlled at the target value U target At this time, the temperature measured by the cold mirror precision dew point meter is the frost point temperature.

[0013] The supercooled water identification and elimination device and method for a chilled mirror type precision dew point meter according to the above aspects of the present invention can realize the identification and elimination of supercooled water on the chilled mirror surface below 0°C, effectively improve the measurement accuracy of the frost point temperature, and improve the measurement accuracy of the chilled mirror type precision dew point meter. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings used in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work:

[0015] Figure 1 It is a structural schematic diagram of a supercooled water identification and elimination device for a chilled mirror type precision dew point meter according to an embodiment of the present invention;

[0016] Figure 2 The present invention is a flowchart of a method for identifying and eliminating supercooled water in a chilled mirror precision dew point meter according to an embodiment of the present invention. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0018] The embodiment of the present invention provides a supercooled water identification device for a chilled mirror type precision dew point meter, such as Figure 1 As shown, the supercooled water identification device of the embodiment of the present invention includes a light emitting tube, a photoelectric receiver, a voltage collector, a temperature collector, a maximum cooling switch and a controller. The light emitting tube is used to emit light to the mirror surface of the cold mirror precision dew point meter, the photoelectric receiver is used to receive the mirror reflection light to generate a photoelectric signal, the voltage collector is used to collect the photoelectric signal from the photoelectric receiver, the temperature collector is used to collect the mirror surface temperature, the refrigerator is used to cool the mirror surface, and the maximum cooling switch is used to control the cooling power to quickly cool the mirror surface.

[0019] The controller is used to set the target voltage value of the photoelectric signal, and judge whether there is a possibility of supercooled water according to whether the temperature of the mirror surface is less than or equal to 0°C at the time of dew condensation. If so, the maximum cooling switch is turned on to quickly reduce the mirror surface temperature until the mirror surface temperature is lower than the dew point temperature of -20°C to eliminate supercooled water, and then the voltage value of the photoelectric signal is controlled at the target voltage value by controlling the heating and cooling power of the mirror surface, and the accurate frost point temperature is measured by the cold mirror precision dew point meter.

[0020] The embodiment of the present invention also provides a method for identifying and eliminating supercooled water for a chilled mirror precision dew point meter, and the device of the embodiment of the present invention is used to identify and eliminate supercooled water, such as Figure 2 As shown, the process is as follows:

[0021] First, start the machine and collect the initial voltage value U0 of the photoelectric signal of the photoelectric receiver. Then collect the voltage value for a period of time. 0max and U 0min The voltage fluctuation is caused by the circuit base noise. Before the mirror condenses, the light emitted by the light-emitting tube is reflected on the mirror and received by the photoelectric receiver. Ideally, the voltage value is constant, but due to the influence of the circuit base noise and the slight change of the ambient temperature, the voltage signal will have a slight fluctuation, and the fluctuation amount ΔU = U 0max -U 0min The value of ΔU depends on the selection of the light-emitting tube and the photoelectric receiver, the design level of the circuit, and the control stability of the ambient temperature. In one embodiment of the present invention, the ΔU value is 0.5 mV.

[0022] Secondly, set the voltage target value U target =U aver -ΔU,U aver (U 0max +U 0min ) / 2. In one embodiment of the present invention, after experimental testing, it is obtained that ΔU is 0.5mV, U aver is 3.3467V, U target =3.3462V, U target It can be determined according to actual conditions that the smaller the base noise, the higher the sensitivity of the photoelectric receiver, and the more accurate the dew point temperature is finally measured.

[0023] Input the sample gas into the cold mirror precision dew point meter. When the sample gas is input, the change of voltage value U is used to judge whether the mirror surface is condensed. If the voltage value U does not exceed U 0max ~U 0min If the mirror is within the range, it means that there is no condensation on the mirror, that is, the dew point temperature of the incoming sample gas is lower than the mirror temperature. Turn on the refrigerator to cool until the voltage signal U is lower than U 0min , indicating that condensation has formed on the mirror surface.

[0024] At the moment of condensation, it is determined whether the current mirror temperature T0 is less than or equal to 0℃. If the current mirror temperature is less than or equal to 0℃, it means that there may be supercooled water on the mirror. Turn on the maximum cooling switch, cool with the maximum cooling capacity, and quickly reduce the mirror temperature until the mirror temperature T is lower than T0. Usually T≤T0-20℃, the mirror temperature can also be lower, depending on the specific situation. At this time, the supercooled water has been eliminated, and then the dew point control stage is entered, and the voltage output value of the photoelectric receiver is re-controlled at U target At this time, the temperature output by the dew point meter is the frost point temperature.

[0025] In one embodiment, the identification and elimination of supercooled water at a frost point temperature of -20°C is taken as an example. The air inlet of the cold mirror precision dew point meter is connected to the sample gas, the meter is turned on, the voltage value U0 and the mirror temperature T0 of the photoelectric receiver are collected, and the voltage target value U0 is set. target , at this time the voltage fluctuation range is U 0max ~U 0min When the sample gas input is detected, observe whether the voltage signal is at U 0max ~U 0min If the voltage value U does not exceed U 0max ~U 0min If the mirror is within the range, it means that there is no condensation on the mirror, that is, the dew point temperature of the incoming sample gas is lower than the mirror temperature. Turn on the refrigerator to cool until the voltage signal is lower than U 0min , enter the dew point control stage, by adjusting the heating and cooling power, the voltage value output by the photoelectric receiver is controlled at U target At this time, the collected mirror temperature T is around -20℃, indicating that there is supercooled water on the mirror. Start the heating function, raise the mirror to 5℃, and then automatically start the maximum cooling function to quickly reduce the mirror temperature to -40℃. After eliminating the supercooled water on the mirror, the output value of the photoelectric receiver is controlled at U target At this time, the temperature output by the dew point meter is the frost point temperature.

[0026] In summary, the present invention first determines whether there is a possibility of supercooled water by whether the temperature of the mirror surface is less than or equal to 0°C at the time of condensation. If so, a large cooling method is adopted to make the mirror surface temperature much lower than the dew point temperature (lower than the dew point temperature by less than -20°C), eliminate supercooled water, and then re-control the voltage value to the target voltage value, so as to obtain an accurate frost point temperature.

[0027] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A supercooled water identification and elimination device for a chilled mirror precision dew point meter, characterized in that: It includes a light-emitting tube, a photoelectric receiver, a voltage collector, a temperature collector, a maximum cooling switch and a controller. The light-emitting tube is used to emit light to the mirror surface of the cold mirror type precision dew point meter. The photoelectric receiver is used to receive the mirror reflected light to generate a photoelectric signal. The voltage collector is used to collect the voltage of the photoelectric signal from the photoelectric receiver. The temperature collector is used to collect the mirror temperature. The maximum cooling switch is used to quickly cool the mirror surface. The controller is used to set the voltage target value of the photoelectric signal, and judge whether there is a possibility of supercooled water according to whether the temperature of the mirror is less than or equal to 0°C at the time of dew condensation. If so, the maximum cooling switch is turned on to quickly reduce the mirror temperature until the mirror temperature is lower than the dew point temperature of -20°C to eliminate supercooled water. Then, the voltage value of the photoelectric signal is controlled at the voltage target value, and the accurate frost point temperature is measured by the cold mirror type precision dew point meter.

2. A method for identifying and eliminating supercooled water for a chilled mirror precision dew point meter, characterized in that: Using the device of claim 1 to identify and eliminate supercooled water comprises: Collect the initial voltage value U0 of the photoelectric signal. At this time, the voltage is at the maximum value U 0max and the minimum value U 0min Fluctuate between Set voltage target value U target =U aver -ΔU, where ΔU is the voltage fluctuation value, U aver is the average voltage, ΔU=U 0max -U 0min , U aver =(U 0max +U 0min ) / 2; Input the sample gas into the cold mirror precision dew point meter, collect the current voltage value U, and judge whether the mirror surface is condensed by the change of the current voltage value U. If the voltage value U does not exceed U 0max ~U 0min If the mirror is within the range, it is judged that there is no condensation on the mirror, and the refrigerator is turned on to cool until the voltage value U is lower than the minimum value U 0mm , judge that the mirror surface has condensation; Determine whether the current mirror temperature T0 is less than or equal to 0°C. If the current mirror temperature is less than or equal to 0°C, it is determined that there is supercooled water on the mirror, and the maximum cooling switch is turned on to quickly reduce the mirror temperature until the mirror temperature T≤T0-20°C to eliminate the supercooled water; Control the voltage value of the photoelectric signal to the target value U target At this time, the temperature measured by the cold mirror precision dew point meter is the frost point temperature.

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