Thermal performance of ventilated solar collector with energy storage containing phase change material

This paper presents a ventilated solar collector with energy storage of fins containing Phase Change Material (PCM) in the air cavity and investigates its thermal performance. The idea is to use PCM in combination with ventilation as a thermal controller of indoor environment and to consequently decrease the building energy consumption both in summer and winter time. The main parts of the solar collector are plate fins with small thickness containing PCM fitted into the ventilation cavity, which is a good way to compensate the low thermal conductivity of PCM. The solar collector can absorb large amount of solar energy because of the high latent capacity of PCM. The energy is supplied into the indoor environment by means of ventilation. The system can be integrated into the building envelopes such as windows for low-energy building.

This study starts with examining the discharge process of PCM fins by numerically investigating 9 cases of PCM fins in different fin thickness and air gap thickness in a transient 2D model. Then the charge process of PCM fins in consideration of solar radiation is studied in a time-dependent 3D model. The results show that for discharge process, a larger fin thickness and a smaller air gap thickness are good for the increase of total heat exchange amount of PCM fins during discharge process. However, when continuing to increase the fin thickness and keeping the air gap thickness fixed at 5 mm, the total heat exchange amount does not continue the increase trend. The fin thickness of 20 mm has the largest heat exchange amount and the largest utilization percentage. Mechanical ventilation is needed only in cases with air gap thickness as 5mm. The system has the potential to completely or partly substitute the air-conditioning and heating system and a big energy saving potential.