Improving Solar Air Heater Collector Performance With Coil Tube Filled by Phase Change Material Under Opposing Flow Forced Convection

ABSTRACT This work experimentally explores the improving solar air heater collector with a coil tube filled by Phase Change Material under opposing flow forced convection. To demonstrate the performance enhancement, two SAH models are used, where the first model is equipped with a coil tube filled by Lauric acid as phase change material (PCM) whereas the second model is a normal SAH collector. The experiments are done under typical conditions in Mosul city, Iraq for around 11 h per day in winter from January to March 2025. The performances of the two models are presented together for the purpose of comparison. Both models have identical structural dimensions, insulation, and glazing, enabling a direct assessment of PCM effects on the outlet temperature, useful energy gain, and thermal efficiency. Results demonstrated that the thermal performance increases with increasing mass flowrate of air, where the thermal efficiency of the modified model is greater than the conventional model by a ratio of 21%, 16%, and 8.5% for air mass flowrates 0.02223 kg/s (14th March), 0.04769 kg/s (15th March), and 0.08462 kg/s (16th March), respectively. For constant air mass flowrate, the findings displayed that the modified model outperforms the conventional model by a ratio of 31% (on 18th January), 28% (on 12th February), and 21% (on 14th March). For all air mass flowrates, the results indicated that the modified model exists at a higher outlet temperature than the conventional model. Finally, the findings confirm that the use of a coil tube filled by PCM along with opposing flow forced convection has a major impact on the model performance without need for complex modifications, making the modified model the optimal design among the tested configurations.