Low-temperature thermocouple calibration device for 77-90K temperature area

Abstract

The invention discloses a low-temperature thermocouple calibration device for a 77-90K temperature area. The calibration device comprises a vacuum pump, a liquid nitrogen tank, a tapered container, acalibration platform, a heat sink, a constant-temperature block, a thermocouple to be calibrated, a standard thermometer, a vacuum tank, a vacuum pump and a data collection instrument. By use of the method, a stable temperature point between 77 and 90K can be conveniently obtained, and in addition, a plurality of thermocouple thermometers can be simultaneously calibrated. The set of device has theadvantages of being convenient in operation, high in accuracy, high in a calibration amount and the like.

Description

technical field [0001] The invention relates to the technical field of low-temperature refrigeration engineering, in particular to a calibration device for a low-temperature thermocouple thermometer in a temperature range of 77-90K. Background technique [0002] In low-temperature cavitation and liquid flooding experiments, the temperature range of the experimental section is between 77 and 90K, the frequency of temperature changes is very fast, and more temperature measuring points need to be arranged. Therefore, low-temperature thermocouples are widely used in the temperature measurement of the experimental section of low-temperature cavitation and liquid flooding experiments due to their excellent dynamic response characteristics and low cost. [0003] The traditional low-temperature thermocouple calibration method uses the boiling point of liquid nitrogen under standard atmospheric pressure, the temperature point of ice-water mixture, and the boiling water point as three...

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Problems solved by technology

[0005] Chinese patent CN 104458059 A discloses a calibration device for thermocouple strings. The device takes the naturally changing room temperature as the calibration point, and can easily and quickly calibrate multiple thermocouples, but it is not suitable for low-temperature thermoelectric devices requiring high precision. Even calibration

Chinese patent CN105865658A discloses a ground calibration method for miniature armored thermocouples. This invention uses a small infrared lamp array to achieve uniform heating on the plane of the constant temperature copper plate, and can simultaneously calibrate multiple thermocouple thermometers, but it cannot be applied to 77-90K Area

[0006] The article [1] describes a calibration device for low-temperature thermocouples, which utilizes the radiant cooling of liquid nitrogen to resist the heat provided by the heater in the constant temperature box, so as to realize the calibration of low-temperature thermocouples in the temperature range of 77-273K ;A medical cryogenic thermometer calibration device is described in the article [2]. Its principle is similar to that of the article [1]. It uses the different heating power of the heating wire in the constant temperature block and the cold radiation of liquid nitrogen to balance to achieve 77 ~ 300K Different stable temperature points; this type of device is widely used, but the incubator needs to be completely immersed in liquid nitrogen, and the inside of the incubator needs to maintain a high vacuum state. When calibrating a large number of thermocouples in groups, the vacuum must be repeatedly broken state, rearrange the thermocouples to be calibrated, and the operation is complicated

The article [3] describes a simple low-temperature thermocouple calibration system and method. Its invention is to mix different proportions of liquid nitrogen and liquid oxygen in a low-temperature open container to obtain multiple calibration points between 77 and 90K, and A detailed uncertainty analysis is given for the calibration results, but the design of the device is simple, and multiple low-temperature thermocouples cannot be calibrated at the same time, and liquid nitrogen and liquid oxygen cannot be reused after mixing

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