Dust Deposition Mechanism and Cleaning Strategy for Open Volumetric Air Receiver Based Solar Tower Sub-systems

Abstract

Desert regions like Rajasthan and Gujarat in India receives abundant solar energy. At the same time these regions are blessed with dust or sand. Solar thermal systems are one of the ways to harness this available energy. Open Volumetric Air Receiver based concentrated solar tower systems are being investigated for applications, like, metal processing. The dust deposition on sub-systems like, heliostat, porous receiver will hinder smooth operation of such a system. Considering this fact, aspects of dust deposition in porous absorber of the receiver and in heliostat are presented. In this direction, experiments and analyses are performed. This revealed that dust deposition on heliostat will be affected by its location among other parameters. The presented analysis shows the required free-stream air velocity for cleaning of such a mirror depending on particle size and location. Experiments on dust deposition in a single pore of an absorber, simulated by a thin and long glass tube of 1.3mm diameter is presented. Furthermore, experiments on dust deposition in one porous absorber reveal its severe consequence. Finally, a strategy for collection of the removed dust particles from these pores is presented to avoid their passage to internals.

Dust impact on concentrated solar power: A review

“…Bouaddi et al [102] modeled the cleanliness of CSP reflectors with Dynamic Linear Models, then compared it with that of exposed 45° tilted mirrors; the dust distribution was homogenous (as noted also by [96,103]); the lowest measured cleanliness was around 20% after 3 months. The local linear trend was the best to describe the cleanliness factor.…”

“…To evaluate the impact of dust on solar tower plants, Singh et al [96] investigated the soiling of heliostats and Open Volumetric Air Receivers (OVAR), the tests were done with single and double heliostat set-ups. Dust blocked 20% of the OVAR's pores, which caused reduction of the convective heat transfer and the overall efficiency.…”

On the design and evaluation of open volumetric air receiver for process heat applications

“…Therefore, dust will deposit on the pores and cleaning is required for smooth operation of OVAR, especially, in arid regions, like, Rajasthan. A strategy for cleaning and collection of dust from pores are presented in Singh et al (2015). A comparison between existing and the presented absorber design is given in Table 5.…”

Self-cleaning of a hydrophobic surface by a rolling water droplet

“…Water condensation on the dust particles can cause dissolution of some dust compounds in water and forms a chemically active liquid on the surface 30 . In some cases, this gives rise permanent damage on the texture and alters the surface properties 31 . Moreover, investigation of the mechanism of the dust particles deposition on surfaces becomes important towards minimization of particle accumulation, which becomes critical for sustaining the high performance of solar energy harvesting devices 32,33 .…”