Author:
Khanyile B. S.,Numan N.,Simo A.,Nkosi M.,Mtshali C. B.,Khumalo Z.,Madiba I. G.,Mabakachaba B.,Swart H.,Coetsee-Hugo E.,Duvenhage Mart-Mari,Lee E.,Henini M.,Gibaud A.,Chaker M.,Rezaee P.,Lethole N.,Akbari M.,Morad R.,Maaza M.
Abstract
AbstractSolar heat management & green air-conditioning are among the major technologies that could mitigate heat islands phenomenon while minimizing significantly the CO2 global foot-print within the building & automotive sectors. Chromogenic materials in general, and thermochromic smart coatings especially are promising candidates that consent a noteworthy dynamic solar radiation Infrared (NIR-IR) regulation and hence an efficient solar heat management especially with the expected increase of the global seasonal temperature. Within this contribution, two major challenging bottlenecks in vanadium oxide based smart coatings were addressed. It is validated for the first time that the NIR-IR modulation of the optical transmission (∆TTRANS = T(T〈TMIT) − T(T〉TMIT) of Vanadium oxide based smart coatings can be controlled & tuned. This upmost challenging bottle-neck controllability/tunability is confirmed via a genuine approach alongside to a simultaneous drastic reduction of the phase transition temperature TMIT from 68.8 °C to nearly room temperature. More precisely, a substantial thermochromism in multilayered V2O5/V/V2O5 stacks equivalent to that of standard pure VO2 thin films but with a far lower transition temperature, is reported. Such a multilayered V2O5/V/V2O5 thermochromic system exhibited a net control & tunability of the optical transmission modulation in the NIR-IR (∆TTRANS) via the nano-scaled thickness’ control of the intermediate Vanadium layer. In addition, the control of ∆TTRANS is accompanied by a tremendous diminution of the thermochromic transition temperature from the elevated bulk value of 68.8 °C to the range of 27.5–37.5 ºC. The observed remarkable and reversible thermochromism in such multilayered nano-scaled system of V2O5/V/V2O5 is likely to be ascribed to a noteworthy interfacial diffusion, and an indirect doping by alkaline ions diffusing from the borosilicate substrate. It is hoped that the current findings would contribute in advancing thermochromic smart window technology and their applications for solar heat management in glass windows in general, skyscraper especially & in the automotive industry. If so, this would open a path to a sustainable green air-conditioning with zero-energy input.
Publisher
Springer Science and Business Media LLC
Reference130 articles.
1. Oke, T. R., Johnson, D. G., Steyn, D. G. & Watson, I. D. Simulation of surface urban heat island under ‘ideal’ conditions at night—Part 2: Diagnosis and causation. Bound.-Layer Meteorol. 56, 339–358 (1991).
2. Santamouris, M. (ed.) Energy and Climate in the Urban Built Environment (James and James Science Publishers, 2001).
3. Santamouris, M. Heat island research in Europe—The State of the art. J. Adv. Build. Energy Res. 1, 123–150 (2007).
4. Santamouris, A. & Synnefa, T. K. Using advanced cool materials in the urban built environment to mitigate heat islands and improve thermal comfort conditions. Solar Energy 85(12), 3085–3102 (2011).
5. Papanikolaou, N. et al. On the impact of urban climate to the energy consumption of buildings. Solar Energy 70(3), 01–216 (2001).