Abstract
The Karlsruhe Institute of Technology (KIT) and the WEKA AG jointly develop a commercial flowmeter for application in helium cryostats. The flowmeter functions according to a new thermal measurement principle that eliminates all systematic uncertainties and enables self-calibration during real operation. Ideally, the resulting uncertainty of the measured flow rate is only dependent on signal noises, which are typically very small with regard to the measured value. Under real operating conditions, cryoplant-dependent flow rate fluctuations induce an additional uncertainty, which follows from the sensitivity of the method. This paper presents experimental results with helium at temperatures between 30 and 70 K and flow rates in the range of 4 to 12 g/s. The experiments were carried out in a control cryostat of the 2 kW helium refrigerator of the TOSKA test facility at KIT. Inside the cryostat, the new flowmeter was installed in series with a Venturi tube that was used for reference measurements. The measurement results demonstrate the self-calibration capability during real cryoplant operation. The influences of temperature and flow rate fluctuations on the self-calibration uncertainty are discussed.
Highlights
Flowmeters represent a vital element of process monitoring and control in almost every process engineering application
The new flowmeter was installed in series with a Venturi tube that was used for reference measurements
A new thermal flow measurement principle, developed at Karlsruhe Institute of Technology (KIT) [2, 3] overcomes this problem by its ability of self-calibration at any time and under
Summary
Flowmeters represent a vital element of process monitoring and control in almost every process engineering application. For temperatures close to ambient, numerous flowmeters based on various measurement principles are available. No standard flowmeter apart from a specially designed Coriolis [1] exists [2]. The reason is that all measurement principles use empirical correlations to relate the measured quantity to the flow rate. A factory calibration, typically performed at room temperature with air or nitrogen, is indispensable. Its validity is restricted close to the calibration conditions and the use at cryogenic temperatures results in an additional measurement uncertainty. A new thermal flow measurement principle, developed at KIT [2, 3] overcomes this problem by its ability of self-calibration at any time and under
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
