A numerical study of a PCM-based passive solar chimney with a finned absorber

Abstract

Passive solar systems like solar chimney do require to be exposed to the sunlight. Hence, when the sunlight vanishes due to either sunset or cloudy weather, the system cannot provide the required heating load of a room. Therefore, without an axillary system, a part of solar energy must be stored at the same time which can happen by introducing Phase Change Material (PCM), enabling the system to benefit from the solar energy during night-time. In the present work, a PCM-enhanced solar chimney is investigated with and without considering fins connected to the absorber plate based on the temperature and velocity distributions as well as airflow rate inside a room in comparison with the non-PCM chimney. The simulation is performed for a whole wintery day with the aid of CFD simulation. The results indicate that the use of PCM as a storage medium enhances the temperature uniformity inside the room; however, the achieved room's mean temperature is 14.68 °C which is quite less than the thermal comfort condition. Therefore, the presence of fins added to the absorber is investigated to gain a higher temperature inside the room. According to the results, it is revealed that the presence of fins is significantly efficient in making up the stored energy inside the PCM. More to the point, for the PCM based solar chimney system, the use of fines results in a 20% enhancement in the room's mean temperature compared with the non-finned case. Besides, more non-uniform airflow is gained for the case of finned absorber with PCM compared with the non-finned case.