Enhancing the Performance of Split Unit Air-Conditioning System by Integrating Air–PCM Heat Transfer Unit: Numerical and Experimental Assessment

The growing need for energy-efficient cooling solutions has driven the exploration of cutting-edge technologies in air-conditioning (AC) systems. Therefore, this research aims to improve the energy efficiency of a split AC system by incorporating a phase change material (PCM) heat transfer element into the AC system. PCM can release and store thermal energy, assisting in decreasing the load on the AC system during peak cooling periods. The PCM utilized in the study is Rubitherm RT18HC. The study includes numerical and experimental evaluations to assess the impact of the air–PCM unit on the split unit's performance. The numerical simulations were conducted using computational fluid dynamics models based on ANSYS-Fluent to choose the best design and conditions for the air–PCM unit. The experimental study was conducted in the hot environment of Iraq, where outdoor temperatures exceed 43°C. The numerical results showed that the best design and conditions concluded to be a 1-cm PCM height in the panels, 3 cm air channel height, 0.9 m/s air velocity for charging, 0.45 m/s air velocity for discharging, 7°C inlet air temperature for charging, and 25°C inlet air temperature for discharging. In the experimental part, after validating the theoretical results, two practical cases were conducted to evaluate the split unit performance with and without PCM. The results showed an average of 5% lower room temperature, 9.5% lower air entering the evaporator temperature, 10% lower energy consumption, and a 12.5% increase in the AC unit's coefficient of performance when using the air–PCM heat transfer unit.