Transient analysis of a two-phase flow natural circulation loop using a separated two-phase flow model

Abstract

In this paper the transient and dynamic behaviour of a natural circulation heat transfer loop of 32 mm inside diameter, 7 m height and 8 m width, using water as working fluid is theoretically simulated and experimentally validated. The theoretically simulation requires that the loop is discretised into a number of cylindrical symmetrical control volume and the conservation of mass, momentum and energy are applied to the control volume. The separated two-phase flow model uses frictional multiplier and vapour-liquid void fraction correlations similar to those originally suggested by Martinelli. An orifice plate is used to measure the mass flow rate and which is then compared with the calculated mass flow rate. It is concluded that the theoretical model using the separated two-phase model adequately captures the actual transient and dynamic flow and heat transfer behaviour of the loop. It is further concluded that for future studies of natural two-phase circulation systems the mathematical model using the separated two-phase flow as presented theoretical simulation may be confidently used.