An experimental investigation of heat losses during charging the thermal storage tank in a particle-based CSP system

Abstract

This paper presents results of an exploratory study aimed to investigate heat loss during charging the thermal energy storage (TES) bin with hot solid particles. Tests were performed at the pilot particle-based power tower plant in King Saud University in Riyadh, Saudi Arabia. In this plant, a small TES bin is installed between the particle heating receiver and the particle-to-working-fluid heat exchanger. Two types of experiments, the on-sun test and the steady-state test, were conducted; in each experiment, two cases were considered, namely the empty bin and full bin. Results show that in the case of empty TES bin, the air, entrained as a result of particles falling, can cause a significant temperature drop in the particle side. Moreover, the use of several particle-feeding lines can promote the so-called chimney effect. In the case of full bin, the amount of entrained air was reduced significantly, thus the temperature drop in the particle side was shrunk greatly. However, results also show that the air occupying the empty region (due to the particle’s angle of repose) inside the full bin recorded lower temperature than that of particles which implies that the chimney effect is still present.