Bestimmung der Messunsicherheit dynamischer Kennwerte von Berührungsthermometern in strömender Luft

Augustin, Silke; Fröhlich, Thomas; Heydrich, Marius

doi:10.1515/teme-2016-0055

Cited by 2 publications

(2 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These individual contributions in [9] are presented as examples. With these uncertainties, the time-percent values can be specified for the individual measurements.…”

Section: Test Equipmentmentioning

confidence: 99%

Temperature Dependence of the Dynamic Parameters of Contact Thermometers

Augustin¹,

Fröhlich²

2019

Sensors

Self Cite

View full text Add to dashboard Cite

Contact thermometers are used in a wide temperature range as well as under various media and environmental conditions. The temperature can range from −200 °C to about 1500 °C. In this case, the dynamic parameters (time percentage values tx and time constants τ) depend on temperature. Several effects are superimposed. Constructional and material properties of the thermometer and the installation location affect the dynamic behavior as well as the type and material properties of the object to be measured. Thermal conductivity λ, specific heat capacity c, and density ρ depend on temperature. This temperature dependence can be mutually compensated for (see Section 3). At the same time, the dynamic behavior is also influenced by the temperature-dependent parameters of the medium. When the thermometers are installed in air, for example, the heat transfer coefficient α decreases with increasing temperature, owing to the temperature-dependent material data of the air, at constant speed v. At the same time, heat radiation effects are so strong that the heat transfer improves despite the decreasing convective heat transfer coefficient. In this paper, a number of examples are used to establish a model for the temperature dependence of the dynamic parameters for various thermometer designs. Both numerically and experimentally determined results for the determination of the dynamic characteristic values are included in the consideration.

show abstract

“…These individual contributions in [9] are presented as examples. With these uncertainties, the time-percent values can be specified for the individual measurements.…”

Section: Test Equipmentmentioning

confidence: 99%

Temperature Dependence of the Dynamic Parameters of Contact Thermometers

Augustin¹,

Fröhlich²

2019

Sensors

Self Cite

View full text Add to dashboard Cite

show abstract

“…In and Bernhard (2014), the measurement by means of contact thermometers is described as a measuring chain. Here, the thermal influences resulting from the coupling of the thermometer with the medium, the mounting conditions and the environment are characterized, and the measurement deviations which are due to the conversion of the temperature of the sensing element T S to the variable X A and, depending on some further processing steps, to disturbance variables acting on the secondary converter (e.g., Figure 1.…”

Section: The Contact Thermometer As a Measuring Chainmentioning

confidence: 99%

Bilateral comparison for determining the dynamic characteristic values of contact thermometers in fluids

Augustin

Fröhlich

Schalles

et al. 2018

J. Sens. Sens. Syst.

Self Cite

View full text Add to dashboard Cite

Abstract. In applicable standards and sets of rules (VDI/VDE, 2014; DIN, 2010, 2017), recommendations are made concerning the types of experiments for determining the dynamic parameters in fluids (flowing water and flowing air) under well-defined conditions. In the data sheets of the thermometer manufacturers, quite different specifications can be found, such as time percentage values or time constants. Only a few thermometer manufacturers specify the medium and flow conditions under which these parameters have been determined. Above all, it is not common practice to indicate a measurement uncertainty for the dynamic parameters found. In Augustin et al. (2017), a first model for the indication of the measurement uncertainty of dynamic parameters in flowing air was presented. The present paper describes the results of a bilateral comparison made for the first time for determining dynamic parameters in the laboratories of the JUMO GmbH & Co. KG Fulda company and at the Institute of Process Measurement and Sensor Technology of the TU Ilmenau. In doing so, two type-N thermocouples with different diameters were investigated in experimental facilities with flowing water and flowing air. Subsequently, the dynamic parameters found were compared with each other. The differences revealed mainly resulted from plant-specific parameters.

show abstract

Bestimmung der Messunsicherheit dynamischer Kennwerte von Berührungsthermometern in strömender Luft

Cited by 2 publications

References 0 publications

Temperature Dependence of the Dynamic Parameters of Contact Thermometers

Temperature Dependence of the Dynamic Parameters of Contact Thermometers

Bilateral comparison for determining the dynamic characteristic values of contact thermometers in fluids

Contact Info

Product

Resources

About