Design and Simulation of VRF AC system in cinema hall using ammonia refrigerants

Abstract

This study presents the modeling, simulation, and validation of a dual-zone Variable Refrigerant Flow (VRF) air-conditioning system using ammonia (R-717) as the working fluid in MATLAB/Simulink. The system comprises detailed subsystem models i.e compressor, condenser, expansion valves, evaporators, and a building thermal network integrated with dynamic control for compressor and fan operation. Indoor loads for two cinema zones were simulated with combined sensible and latent heat effects. System performance was assessed through temperature response, cooling capacity, power consumption, and coefficient of performance (COP). Simulated COPs ranged from 3.8 to 4.4, while analytical validation gave 3.749 – 5.41, with percentage errors between 0.58% and 21.92%, indicating strong correlation under moderate loads and deviations under part-load conditions. Compared to a reference R-410A VRF system (COP = 3.2), the R-717 model demonstrated superior performance across most operating state. The study also incorporates a leak detection mechanism based on refrigerant mass imbalance and indoor concentration monitoring, enhancing system safety. The study highlights the critical role of ventilation in mitigating refrigerant leakage.