Abstract
Present environmental issues force the research to explore radically new concepts in sustainable and renewable energy production. In the present work, a functional fluid consisting of a stable colloidal suspension of maghemite magnetic nanoparticles in water was characterized from the points of view of thermoelectrical and optical properties, to evaluate its potential for direct electricity generation from thermoelectric effect enabled by the absorption of sunlight. These nanoparticles were found to be an excellent solar radiation absorber and simultaneously a thermoelectric power-output enhancer with only a very small volume fraction when the fluid was heated from the top. These findings demonstrate the investigated nanofluid’s high promise as a heat transfer fluid for co-generating heat and power in brand new hybrid flat-plate solar thermal collectors where top-heating geometry is imposed.
Highlights
In the current pursuit to improve energy conversion, production, and storage efficiency of renewable technologies, hybridization is considered a promising approach
In the case of solar energy, such hybridization efforts are often made by combining photovoltaics (PV), solar thermal collectors (STC), photochemical synthesis, and other renewable energy technologies
We investigated the thermoelectric and the optical absorption of dilute aqueous ferrofluids made with γ-Fe2 O3 magnetic nanoparticles coated by PAAMA
Summary
In the current pursuit to improve energy conversion, production, and storage efficiency of renewable technologies, hybridization (i.e., combining different energy production technologies in a single system) is considered a promising approach. In the case of STC, hybridization with a TEG module is advantageous as it enables the co-generation of ‘heat’ and ‘electricity.’ Conventional, low-mid temperature, solar thermal collectors consist of a dark surface devoted to sunlight absorption and to heat exchange with a thermal fluid These systems are known to suffer from efficiency limitations due to the thermal resistance at the absorber–fluid interface. A flat-plate, solar-thermal collector with a very large, heated surface offers an ideal application opportunity for these multifunctional ferrofluids to co-generate heat (through an efficient sunlight absorption) and electricity (through thermoelectric conversion) To assess such co-generation feasibility, here we report the first experimental investigation on the thermoelectric and the optical properties of stable aqueous ferrofluids containing maghemite nanoparticles
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