Absorber and self-cleaning surfaces on modified polymer plates for solar harvesting in the humid (sub)tropics

摘要

Mild winters in (sub)tropical climates generally do not require water heating to temperatures above 100 degrees C for residential consumption. This allowed development of a cost-effective polymeric thermo-solar collector concept for all-year and low temperature operation. High absorptance in the solar spectrum (90%) was achieved with a carbon black coating on a transparent PMMA (polymethyl methacrylate) plate, and low emissivity in the black body radiation range at 50 degrees C (6-14 mu m) was provided by a polyester cover. Using the highest average absorber roughness attained (0.369 mu m) and a UV-filtered 300 W Xe/Hg lamp, a 30 degrees C water temperature increase in 80 min was produced. In addition, superhydrophobicity was attained (contact angle of 158 +/- 1 degrees and hysteresis of 2 +/- 1 degrees) by deposition of SiO2 nanoparticles on the polymeric surface to allow self-cleaning in rainy conditions without significant transmittance loss in the solar spectrum. (C) 2015 Elsevier Ltd. All rights reserved.