(a) Conceptual design of a nanofluid concentrating collector with glazing. (b) Conceptual design of a nanofluid concentrating collector without glazing. (c) Conceptual drawing of a conventional power tower solid surface absorber.
Thermal resistance network—comparison between a conventional solar thermal plant and a nanofluid solar thermal plant. , , , , and refer to the thermal resistance of solid surface absorption, conduction, convection, fluid-to-fluid heat exchange, and volumetric solar absorption heat transfer steps, respectively.
Extinction coefficient over the visible range for copper, graphite, silver, and gold— , . The “Pure VP-1_ EXP” is an experimental result for the pure base fluid, Therminol VP-1—as found with a Jasco V-670 spectrophotometer.
Reflectivity as a function of the wavelength of copper, graphite, silver, and gold (20 nm) nanofluids with a volume fraction of 0.1% and (w/ and w/o) glazing as compared to that of a conventional selective surface absorber (Ref. 27 ).
Schematic of conditions used in the numerical model with a characteristic temperature field shown.
Modeled system efficiencies of graphite, copper, aluminum, and silver nanofluids with the system efficiency of Abengoa’s PS10 solar power tower for comparison (Ref. 30 ).
Modeled receiver efficiency as a function of concentration ratio, with , : Single points—published values (Ref. 30 ).
(a) Laboratory-scale single-axis tracking, reflective dish. (b) Aluminum machined receiver with instrumentation ports.
Normalized steady-state efficiencies for conventional collectors (lines) compared to our outdoor laboratory-scale dish experiments (data points).
(a) Comparison of yearly electricity generation for a plant rated at . (b) Comparison of the estimated revenues for a commercial scale plant.
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