Free Cooling Potential HVAC System Integrated with PCM Materials: Experimental and Numerical Investigation

This research explores the use of energy storage systems in combination with PCM to enhance air conditioner (AC) efficiency by lowering inlet air temperature. The study examines various PCM configurations and materials, including paraffin and salt-based PCM, and evaluates the impact of airflow speed on cooling performance. Both experimental and simulation methods were employed, replicating hot-season conditions in Iran. Simulations conducted with ANSYS/Fluent modeled four duct designs, containing one to four PCM enclosure series, subjected to air velocities between 2 m/s and 6 m/s. Results showed that using four PCM series (Design 4) achieved a significant temperature reduction, lowering temperature to 34.5 °C—a drop of 12.8 °C. Salt PCM outperformed paraffin in cooling efficiency. The experimental setup, incorporating PCM enclosures, was tested over three days, with paraffin (RT-31) achieving a maximum temperature drop of 3 °C and a net heat reduction of approximately 16%. These findings demonstrate the potential of PCMs, particularly salt hydrate, to improve AC pre-cooling efficiency.