Preliminary assessment of the nuclear thermal-hydraulic system code MARS for the application to a refrigeration cycle

MARS is a nuclear thermal-hydraulic system code. It has been developed for the design and safety analysis of a water-cooled nuclear power plant and has been validated using various experimental data. It can realistically predict two-phase flow behaviors in both a steady-state and a transient of a complicated thermal-hydraulic system with robustness and versatility. This study is an attempt to fully utilize the advantages of MARS for the simulation of a refrigeration cycle, such as a multi-split system air conditioner. However, since most models and correlations in the MARS code have been developed for water-cooled nuclear systems, some code modification and assessment were required. First, we have implemented the thermodynamic properties of a refrigerant R-410A and a compressor model into the code. Then we assessed the heat transfer and pressure drop models of MARS using a set of R-410A boiling and condensation experiments. To assess the applicability of the MARS code to a refrigeration cycle, we have simulated a multi-split system air conditioner experiment. The results showed that the nuclear thermal-hydraulic system code can predict the transient behavior of a refrigeration cycle reasonably well. The limitations and further improvements are also identified from the results.