Experimental validation of a self-calibrating cryogenic mass flowmeter

[摘要] 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.

[发布机构] Institute of Technical Thermodynamics and Refrigeration, Karlsruhe Institute of Technology, Karlsruhe; 76131, Germany^1;WEKA AG, Baeretswil; 8344, Switzerland^2;Institute of Data Processing and Electronics, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen; 76344, Germany^3;Institute of Technical Physics, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen; 76344, Germany^4

[效力级别] 物理学 [学科分类] 材料科学（综合）

[关键词] Experimental validations;Flow rate fluctuations;Helium refrigerators;Real operating conditions;Reference measurements;Self-calibrating;Systematic uncertainties;Thermal measurements