Thermal Storage Capacity and Night Ventilation Performance of a Solar Chimney Combined with Different PCMs

Thermal storage capacity and airflow rate of a solar chimney combined with different PCMs are numerically studied during nighttime. PCMs with phase change temperatures of 38 degrees C, 44 degrees C, 50 degrees C, and 63 degrees C are selected in this numerical study. Results show that the maximum average ventilation rate of 610 kg/m(2) and maximum thermal storage of 4750 kJ/m(2) are achieved at the phase change temperature of 38 degrees C. However, for phase change temperature of 63 degrees C, night ventilation does not occur under the identical conditions. The findings reveal that a lower phase change temperature can increase the chargeability (and therefore the dischargeability) of a solar chimney, since a higher phase change temperature demands higher solar radiation intensity and longer charging time for a solar chimney. For PCM with a phase change temperature of 44 degrees C, most of the heat stored in PCM is lost to ambient through glass cover by radiation and only a small portion is used for heating the air within air channel.