Characterization of the Humidity Calibration Chamber by Numerical Simulations

Salminen, Juho; Sairanen, Hannu; Grahn, P.; Högström, Richard; Lakka, Antti; Heinonen, Martti

doi:10.1007/s10765-017-2221-y

Cited by 4 publications

(4 citation statements)

References 20 publications

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“…Interestingly, the adsorption/desorption of water molecules reached an equilibrium state faster at lower pressures. This was previously predicted based on a study using a numerical simulation [15]. The humidity measurement by the sensor at P t = 5 kPa shows a difference compared to the case of P t = 101 kPa by about 0.9%rh.…”

Section: Calibration Of Radiosonde Humidity Sensor At Varied Temperat...supporting

confidence: 61%

Calibration of a radiosonde humidity sensor at low temperature and low pressure

et al. 2019

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Relative humidity in upper air is frequently measured using radiosondes at an altitude of up to roughly 35 km. In this study, the calibration of a radiosonde humidity sensor was demonstrated using a humidity generator that can mimic the humidity, temperature, and pressure conditions in upper air. The calibration of the radiosonde humidity sensor was conducted in terms of relative humidity at a temperature range of −70 °C to 20 °C, and at a pressure range of 5 kPa to 101 kPa. Consequently, it was revealed that the radiosonde humidity sensor presents a significant temperature dependency in such a way that indicates lower humidity values than the reference values measured by the generator as temperature is lowered. The deviation from the reference humidity was measured at about 30%rh at −70 °C. However, the effect of low pressure (5 kPa) on the sensor measurement was less than 1%rh. The uncertainty budget on the calibration of the radiosonde humidity sensor, including factors due to humidity generation, correction of temperature effect, pressure effect, and sensor reproducibility, are presented. Consequently, the calibration uncertainty of the humidity sensor was 3.8%rh at the coverage factor k = 2. The calibration capability of the radiosonde humidity sensor demonstrated in this study will provide traceability to the International System of Units (SI) in the humidity measurement in upper air.

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Section: Calibration Of Radiosonde Humidity Sensor At Varied Temperat...supporting

confidence: 61%

Calibration of a radiosonde humidity sensor at low temperature and low pressure

et al. 2019

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“…Interestingly, the adsorption/desorption difference of frostpoint temperature at 4.6 kPa is smaller than that at 20 kPa at low frost-point temperatures. This is possibly because the adsorption/desorption of water molecules on surfaces reaches an equilibrium state faster at lower pressures as previously studied using numerical simulations [18].…”

Section: Uncertainty Budgetmentioning

confidence: 70%

Development of a low-temperature low-pressure humidity chamber for calibration of radiosonde humidity sensors

Lee¹,

Choi²,

Woo³

et al. 2019

Metrologia

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A low-temperature low-pressure humidity chamber has been developed at the Korea Research Institute of Standards and Science for the calibration of radiosonde humidity sensors. The humidity generator operates in a two-temperature and two-pressure mode in which a saturator and a test chamber are separately immersed in two baths. The saturation performance of the saturator is first evaluated at a low temperature (−75 °C) and at atmospheric pressure. In this condition, the uncertainty of the frost-point temperature by the saturator is 53 mK with the coverage factor k = 2. Then, a chilled mirror hygrometer is calibrated for the compensation of low-pressure effects such as a pressure drop along the tubing line inside the hygrometer. Significant differences between the frost-point temperature at the hygrometer inlet and that measured by the hygrometer are observed at a pressure lower than 20 kPa. An empirical formula for compensating the low-pressure effects on the hygrometer is obtained and, subsequently, is used for the validation of the frost-point temperature generated at a low temperature and low pressure in the test chamber. The corresponding uncertainty due to the calibration of the hygrometer including the compensation of low-pressure effects is 306 mK at k = 2. A representative humidity generation and its validation by the hygrometer is demonstrated at a temperature (−70 °C) and two pressures (4.6 kPa and 20 kPa) in the test chamber. Uncertainty budgets on relative humidity in the test chamber are presented from 10 %rh to 40 %rh with a 10 %rh interval at both pressures. Consequently, the combined uncertainty is less than 2%rh (k = 2) which includes uncertainty factors such as the saturation efficiency, the adsorption/desorption hysteresis, the validation by the hygrometer measurement at low pressures, and so on. The newly developed humidity chamber enables the calibration of radiosonde humidity sensors at low temperature and low pressure conditions that mimic upper air environments in a traceable manner to the International System of Units (SI).

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“…Then the structure, heating mode and heat transfer mode are analyzed. The heating condition is the heating of the heating film at the bottom of the metallic module and the temperature change is taken as the boundary condition, which is measured by the internal sensor of the thermostatic metal bath [13], [14]. The cloud of the 60 ℃ temperature field in a thermostatic metal bath is shown in Fig.…”

Section: Finite Element Analysis Of Temperature Field In a Thermostat...mentioning

confidence: 99%

Design of Calibration System for Multi-Channel Thermostatic Metal Bath

Zhuo,

Xu,

Zhou

et al. 2024

Measurement Science Review

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The use of the thermostatic metal bath is becoming more and more extensive and the requirements for its precision and reliability are also increasing. To meet the needs of the metal bath calibration, a 12-channel thermostatic metal bath temperature field calibration system based on a four-wire PT100 has been designed. The system design includes a front-end temperature measurement component, which consists of a four-wire PT100 and a thermostatic block, and a signal processing component, which consists of a bidirectional constant current source excitation unit, a signal conditioning unit and a high-precision acquisition unit. The STM32f407 is used as the main control chip, and the analog channel selector is used for 12-channel selection. The constant current source is used for signal excitation, the proportional method is used to measure the PT100 resistance, and an acquisition circuit with a high-precision 32-bit ADS1263 analog-to-digital converter is used to amplify, filter and convert the analog signal. After piecewise linear fitting and system calibration, the temperature measurement accuracy can reach 0.4 mK, which meets the calibration requirements of the thermostatic metal bath.

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Characterization of the Humidity Calibration Chamber by Numerical Simulations

Cited by 4 publications

References 20 publications

Calibration of a radiosonde humidity sensor at low temperature and low pressure

Calibration of a radiosonde humidity sensor at low temperature and low pressure

Development of a low-temperature low-pressure humidity chamber for calibration of radiosonde humidity sensors

Design of Calibration System for Multi-Channel Thermostatic Metal Bath

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