Effect of phase-change materials in the performance of a solar air heater

This work presents an experimental analysis of a double-channel solar air heater (SAH) with and without phase-change material (PCM) as thermal energy storage system (TES). Two identical prototypes were designed and constructed, and one of them was modified to house macro- encapsulated PCM in the absorber plate. Both collectors were evaluated in an experimental setup instrumented for hot air temperature and velocity, solar radiation, temperature probes in the glass cover, absorber plate, PCM storage system, and a weather station to record the environmental conditions. To evaluate the performance of the SAH under sudden variations of solar radiation, three different case studies were considered with varying conditions of weather: clear sky and high radiation, partially cloudy, and clear sky with a substantial drop in solar radiation at noon. The maximum outlet temperatures reached by the SAH with PCM were 82 °C, 62 °C, and 79.5 °C for the three cases, respectively. The outlet temperature of the SAH without PCM was consistently 10 °C lower compared to the collector with PCM. The PCM maintained the heating during day irradiation transients and extended it after dusk, without any decrease in the thermal efficiency. Further studies of modeling and design optimization appear very pertinent.