Peter Schütz
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The two-phase flow test rig MTLoop

Foto der Hauptumwälzpumpe
Circulation pump of MTLoop

The test rig MTLoop (Measurement Test Loop) was erected in 1995 to test innovative measurement methods for two-phase flows. For this purpose the sensors, mostly wire-mesh sensors, were mounted in different levels in a vertical test section of 3.5 m length, so that the phase status was measured on various inlet length. The wire-mesh sensors deliver data with high spatial and temporal resolution, so that on the MTLoop test rig was carried out generic investigation with steady-state and transient two-phase flows in the frame of a research project. MTLoop was operated until 2003 and was dismantled after the successful commissioning of the high-pressure thermal hydraulic test facility TOPFLOW. Similarly like the TOPFLOW data, the results of MTLoop was used for model development and validation of Computational Fluid Dynamics (CFD) codes.

Design and operation

A schematic view of MTLoop is presented in the following picture. Water circulated in the test loop that was drawn from a separation tank and pumped into a rising pipe. The gas phase was injected to the bottom part of this pipe, either air controlled by flow meters or steam generated by an electrical heater. Then the two-phase mixture flowed trough the vertical test section, where the measurements took place. Subsequent to the rising pipe a horizontal channel was installed to investigate horizontal flow phenomena. The last pipe ended in a cyclon-separator that separated the mixture. The water returned to the rising pipe and the air or steam was blowed-off. The cooler at the suction side of the circulation pump was applied to control the temperature in the test section during air water tests or to set a defined subcooling for the pump (avoid cavitation) during steam water experiments. The test loop was designed for operation up to a pressure of 2.5 MPa and the corresponding saturation temperature of 224°C and have had an approval of operation by the authorities. All pipes with exception of the downpipe had a nominal diameter of DN50. The last one was designed with DN65 that is the same diameter as the suction side flange of the pump.

Schematische Dartellung der Anlage

Schematische Darstellung der Zweiphasentestschleife MTLoop



This work is based on a research project funded by the German Federal Ministry of Economics and Energy, support code: 150 1215. The authors assume the responsibility for the content.