Papers by Keyword: Hydrophobic Coatings

Abstract: Dust deposition may reduce the yield of the PV panels from 10-50% depending upon the amount of dust deposited, particle size and nature. To prevent loss of efficiency of power plant, cleaning of PV panels is generally required in one-two weeks and in summers during dust storms cleaning frequency needs to be increased. Generally, for cleaning de-ionised water is recommended which adds to the cost and even availability of ordinary water for cleaning is a problem with water scarce regions. In the world, most of the high solar potential sites which are ideal for solar PV power plant installation lie in water scarce regions. The attractive locations for solar energy in Asia and Sub-Saharan Africa are water stressed. Therefore, it becomes important to devise methods to reduce the water consumption in cleaning of solar PV panels in solar power plants. There are studies going on several methods, one such option is use of transparent hydrophobic coatings on the solar panel surface to reduce dust deposition and water used in cleaning. The present work is a step in the direction of estimation of reduction of water consumption with the use of transparent hydrophobic coatings. The present paper discusses the characteristics of dust particles deposited on the solar power plant at University of Kota, Kota, India location and compares the water use amount in cleaning dust on five glass samples. The five samples consist of four different transparent hydrophobic coatings available in market and one is the reference uncoated glass sample. Tests have been done and reported for transparency, dust deposition and water use amount in cleaning for the five samples. On the basis of the comparative study, the amount of water saving potential is estimated for solar power plants. The challenges in use of hydrophobic coatings have been discussed and scope for future work in this field has been examined.

Abstract: In this work, nanomaterials were used as consolidants and protective layers for artistic stones. Synthetized nanocomposites were applied on marble and their performances as protective and water repellent coating were characterized. For the preparation of the novel nanocomposites, SiO₂ and TiO₂ nanoparticles were synthesized by laser pyrolysis and were dispersed in acrylic polymer and silicon-based resin. To evaluate the retreatability of water repellent treatments, the capability of laser to remove protective layers was explored. Laser cleaning tests with different working parameters have been carried out to optimize the effectiveness of the process. The effects of laser treatments on stone surfaces and on the applied nanocomposites were estimated by using confocal optical microscopy and Laser-Induced Fluorescence (LIF).

Abstract: Experimental investigation and numerical simulation on the effect of surface wettability on the performance of a polydimethylsiloxane (PDMS) based diffuser micropump are presented. A valveless micro membrane pump with piezoelectric actuation has been examined. Using a replica molding technique, the valveless micropump was made of PDMS on a Pyrex glass substrate. A thin piezoelectric (PZT) disc was used as an actuator. Poly vinyl alcohol (PVA) and octadecyltrichlorosilane (OTS) coatings, which make the coated surface hydrophilic and hydrophobic, respectively, were used to modify the surface wettability inside the pump. In our experiments, the contact angle of the PDMS surface changed from 96.6 o to 29.1 o and 99.6 o by PVA and OTS coatings, respectively, and the contact angle of glass changed from 33.2 o to 17.5 o and 141.8 o. A self-priming process was numerically simulated in a diffuser element using a computational fluid dynamics program (CFD-ACE+). The results show that fewer gas bubbles were created in the hydrophilic coated pump than in the hydrophobic coated one as time progressed. This agrees well with experimental observations. Steady-state flow rates of the micropump were measured. Compared to the non-coated pump, the flow rate increased slightly with the hydrophobic coating but decreased with the hydrophilic coating. We determine that surface wettability significantly affects the performance of a PDMS-based micropump.