摘要

Single phase natural circulation is of interest in various energy systems, including solar heaters, nuclear reactors, geothermal power production, engine and computer cooling. The present paper deals with an experimental study on the influence of pressure drops on the behavior of a single-phase natural circulation loop. At DITEC two rectangular loops have been constructed and operated, differing for the inner diameter of the tubes and for other geometric dimensions but maintaining quite the same length/diameter ratio.
In this paper the experimental results using the bigger loop are reported. Several series of tests have been carried out, varying the input power from 500 W to 3400 W. The loops showed, sometime, unstable behavior in the case of smooth pipes, hence to stabilize the behavior two localized pressure drops (orifices of different diameter) were located in the vertical legs. The experimental data are analyzed and compared with previous results obtained with smooth pipes, demonstrating the stabilizing effect of the pressure drops on the overall behavior of the loop.