Heat Transfer Characteristics of a Volumetric Absorption Solar Collector using Nano-Encapsulated Phase Change Slurry

ABSTRACT

The conventional solar collectors which absorb solar energy through surface of the receiver have much energy waste during energy conversion process due to heat loss from the pipe surface. Volumetric absorption solar collectors (VASC) can overcome this problem through directly absorbing solar energy by nanofliud with excellent optical absorption property. Nano-encapsulated phase change material (NPCM) is a kind of novel composite PCMs widely adopted in thermal energy storage system. The NPCM slurry (NPCS) has great potential to be used in VASC since it can be used as both the heat transfer fluid and energy storage medium. In the present study, a numerical model based on the Eulerian-Eulerian approach is built to investigate the heat transfer characteristics of NPCS in a parallel plate channel for volumetric absorption of solar energy. Influences of different parameters such as the extinction coefficient, flow velocity, radiative intensity on the performance of collector are studied through the numerical simulation. The results indicate that the NPCS shows better performance in the VASC compared with the conventional nanofluids without phase change. The information provided is helpful in the further study of solar energy volumetric absorption.