SI-Traceable Water Content Measurements in Solids, Bulks, and Powders

Østergaard, Peter Friis; Nielsen, Jan Alexis

doi:10.1007/s10765-017-2325-4

Cited by 19 publications

(4 citation statements)

References 10 publications

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“…Since the dewpoint hygrometer measures the condensation temperature of the gas leaving the system, and water is expected to be present in the highest content and with the highest condensation temperature, any other compound evaporating from the sample will not be measured in this setup, making the measurement water-content-specific. A detailed description of the setup has been given by Østergaard and Nielsen [13].…”

Section: Dti Reference Methodsmentioning

confidence: 99%

Calibration Techniques for Water Content Measurements in Solid Biofuels

Kjeldsen,

Østergaard,

Strauss

et al. 2024

Energies

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This paper presents methodologies and equipment for SI-traceable inline measurements of water content (a critical quality parameter) in solid biofuels. Inline measurement systems for water content are commonly used at CHP plants, providing continuous real-time data. However, the accuracy of these systems is in most cases unsatisfactory, mainly because the systems are not calibrated representatively for the relevant material, and until now, calibrations traceable to the SI system have not been available. To provide reliable and accurate inline water content data, new procedures and equipment for calibrating measurement systems were developed. Two reference methods for the determination of water content were developed; one measures the airflow and dewpoint of desorbed water in the air passing a test sample, while the other uses a P2O₅-sensor. Additionally, a transfer standard based on a cavity resonance sensor was developed for fast onsite calibration of the inline sensor at the power plant. This new instrument allows for quick and accurate measurements. The transfer standard is made metrologically traceable to the primary measurement standards. The entire system was demonstrated by calibrating an inline microwave-based (MW) sensor at the CHP plant of VERDO in Randers, Denmark. Thus, a complete metrological traceability chain was established from an industrial to a primary standard.

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Section: Dti Reference Methodsmentioning

confidence: 99%

Calibration Techniques for Water Content Measurements in Solid Biofuels

Kjeldsen,

Østergaard,

Strauss

et al. 2024

Energies

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“…The wood blocks are then placed in chambers with forced air circulation and a constant humidity for at least two months before they are used for calibrations. The humidity in the chambers are controlled with saturated salt solutions [1] and continuously monitored by means of calibrated capacitive humidity sensors. The relative humidity is held constant with a requirement of maximum fluctuations of ±1.5 %rh during the preparation period.…”

Section: Preparation Of the Wood Samplesmentioning

confidence: 99%

“…This set-up is based on humidification of wood in an atmosphere with constant humidity, generated by saturated salt solutions. The measurements of the reference values are made by means of the loss-on-drying method and measurements are made traceable to a primary standard for moisture mass fraction developed by DTI in the EMRP METefnet-project [1]. The calibration and measurement capabilities (CMC) were accredited by the national accreditation body in Denmark, DANAK, in 2018.…”

Section: Introductionmentioning

confidence: 99%

A new set-up for the calibration of wood moisture meters

Fester

Kjeldsen

Østergaard

et al. 2019

19th International Congress of Metrology (CIM2019)

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A set-up has been established to calibrate wood-moisture meters at Danish Technological Institute. The set-up is based on humidification of wood in an atmosphere with constant humidity, generated by saturated salt solutions. The measurements of the reference value are made by means of the loss-on-drying method and made traceable to a primary standard for moisture mass fraction established under the EMRP project METefnet in 2015. The facility was accredited by the Danish Accreditation Fund, DANAK, in 2018. In this paper, we report on the design of the calibration set-up, the uncertainty analysis and the validation by comparison to the primary facility.

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“…In this system, the relative expanded uncertainty (95 % confidence level) can be as low as 1.5 %. The DTI standard (Figures 1b) is described in detail in [5]. In both the VTT and the DTI primary standards the measurement chambers are much larger than what is common in commercially moisture analysers, allowing representative measurement on most industrial products without having to pretreat the sample with a risk of contaminating it.…”

Section: Introductionmentioning

confidence: 99%

New Primary Standards for Establishing SI Traceability for Moisture Measurements in Solid Materials

et al. 2017

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A European research project METefnet addresses a fundamental obstacle to improving energy intensive drying process control: due to ambiguous reference analysis methods and insufficient methods for estimating uncertainty in moisture measurements, the achievable accuracy in the past was limited and measurement uncertainties were largely unknown. This paper reports the developments in METefnet that provide a sound basis for the SI traceability: four new primary standards for realising the water mass fraction were set up, analysed and compared to each other. The operation of these standards is based on combining sample weighing with different water vapour detection techniques; cold trap, chilled mirror, electrolytic and coulometric Karl Fischer titration. The results show that an equivalence of 0.2 % has been achieved between the water mass fraction realisations and that the developed methods are applicable to wide range of materials.

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SI-Traceable Water Content Measurements in Solids, Bulks, and Powders

Cited by 19 publications

References 10 publications

Calibration Techniques for Water Content Measurements in Solid Biofuels

Calibration Techniques for Water Content Measurements in Solid Biofuels

A new set-up for the calibration of wood moisture meters

New Primary Standards for Establishing SI Traceability for Moisture Measurements in Solid Materials

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