Extending thermal-hydraulic modelling capabilities of Apros into coiled geometries

In this work we extend modelling capabilities of the Apros two-fluid thermal hydraulic model into coiled geometries by re-defining the existing closure laws with new correlations valid in coiled tubes. The purpose is to be able to accurately model helically coiled steam generators, often adoped by small modular reactors (SMRs). For that, we identify suitable correlations and implement them into Apros. We also seek to identify areas which can already be accurately described with the existing models and, on the other hand, areas in which further experimental efforts are required for development of more accurate methods. Further, based on open literature, we compile a data base of experimental data for validation and verification purposes. We use the compiled data base for improving the accuracy of some of our calculation models. Specifically, we propose a modified version of an existing correlation for predicting the first dryout quality in helically coiled tubes. The proposed correlation is capable of estimating the first dryout quality with a reasonable accuracy in a range of state parameters and curvature ratios in which helically coiled steam generators generally operate.