Experimental setup, instrumentation and start-up of the L-STAR small loop (S-Loop) facility

A closed gas loop facility with six side channel blowers is planned for assessing the thermohydraulic and safety conditions of gas cooled systems for power reactors and validating heat transfer and pressure drop correlations of fuel rod assemblies. The main purpose of the experimental setup is to measure temperature and gas velocity profiles close to the electrical heated rod with different artificial surface roughness. As the first part of the investigation, a small air loop (S-Loop) with only one side channel blower operating at a pressure up to 3 bar (a) has been erected, instrumented, and qualified for operation. To identify the functional behaviour of the S-Loop facility, pressure and temperature distributions over the whole gas loop as well as the mass flow rate have been measured for different primary pressures and for different rotational speeds of the side channel blower, with and without the influence of the bypass-2. Furthermore, gas velocity in the test section has also been measured by means of LDA. Repeatability of the functional behaviour and the influence of the bypasses have been checked. Experimental results revealed that the test section operates at a reduced pressure situation. In the case of particle seeding for LDA measurement, periodical pressure variation in the S-Loop was detected. Results from altogether three test series are compared, analysed and discussed in this paper, together with a detailed description of the S-Loop P and ID. (author)