Efficient Volumetric Absorption Solar Thermal Platforms Employing Thermally Stable - Solar Selective Nanofluids Engineered from Used Engine Oil

Abstract

We report a low cost and scalable method to synthesize solar selective nanofluids from ‘used engine oil’. The as-prepared nanofluids exhibit excellent long-term stability (presently tested up to 6 months under undisturbed stagnant conditions at room temperature) and photo-thermal conversion efficiency. Moreover, these were found to retain their stability and functional characteristics even after extended periods (72 hours) of high temperature (300°C) heating, ultra violet light exposure and thermal cyclic loading. Building upon it, we have been able to successfully engineer an efficient volumetric absorption solar thermal platform that employs the as-prepared nanofluids and achieves higher steady state temperatures (approximately 5% higher) relative to the conventional surface absorption based solar thermal system under the sun. The developed volumetric absorption solar thermal platform could prove to be significant step in the evolution of efficient solar thermal systems which could potentially be deployed for host of applications ranging from solar driven heating, air-conditioning, and desalination units to solar energy electricity generation systems.

Recent advances on the fundamental physical phenomena behind stability, dynamic motion, thermophysical properties, heat transport, applications, and challenges of nanofluids

“…Because nanomaterials are more prone to chemical destabilization like oxidation [178], oxidation is a common chemical destability that arises in the nanofluids. This always occurs when the working temperature is high or when a small number of air J o u r n a l P r e -p r o o f leaks into the fluid system (promote oxidation of nanofluid) [179,180]. pH variations, chemical species, and electrolytes can induce oxidation of nanoparticles [31,181] and corrosion in the container walls [182].…”

Non-linear finite element modelling of light-to-heat energy conversion applied to solar nanofluids

“…Another inconvenience of incrementing concentration is that the colloidal stability of the nanofluid is not guaranteed [67,68], thus it is more likely to precipitate and then lose the working principle of the nanofluid. Moreover, continuously increasing the NPs concentration in the base fluid does not guarantee better light absorption as light-to-heat conversion is limited to top layers in solar nanofluids with high NPs concentrations [69].…”

Nanofluid Filled Enclosures: Potential Photo-Thermal Energy Conversion and Sensible Heat Storage Devices

“…Herein, the nanoparticles dispersed in the liquid absorb the incident solar energy and subsequently transfers it to the surrounding liquid. Particle size being very small; negligibly small temperature difference exists between the nanoparticle and the surrounding liquid -hence resulting in efficient photo-thermal energy conversion [7][8][9][10][11][12][13]. In order to realize efficient solar thermal energy conversion platforms based on volumetric absorption principle, a detailed investigation into transport mechanisms involved in such systems is warranted.…”