Comparison of selective transmitters for solar thermal applications.

Solar thermal collectors are radiative heat exchangers. Their efficacy is dictated predominantly by their absorption of short wavelength solar radiation and, importantly, by their emission of long wavelength thermal radiation. In conventional collector designs, the receiver is coated with a selectively absorbing surface (Black Chrome, TiNO, etc.

Multipetal-Structured and Dumbbell-Structured Gold-Polymer Composite Particles with Self-Modulated Catalytic Activity.

A simple synthesis route for gold-polymer composite particles with controlled structure (multipetal structure and dumbbell structure) is developed. It is intriguing to observe that by controlling the reaction time and size of gold nanoparticles (AuNPs), tetrapetal-, tripetal-, and dumbbell-structured gold-polystyrene composite are obtained via seeded polymerization. The average number of petals on a single AuNP increases with the AuNP diameter.

Thermo-responsiveness and tunable optical properties of asymmetric polystyrene/PNIPAM-gold composite particles.

Environmentally responsive polystyrene/poly (N-isopropylacrylamide)-gold composite particles are successfully synthesized via a Pickering emulsion polymerization method. It is found that the core-shell and asymmetric structured particles are simultaneously formed during the polymerization. Compared with the core-shell structured composite particles, the asymmetric particles have a higher thermo-responsiveness as a result of differences in morphology and formation mechanism.

Core-shell and asymmetric polystyrene-gold composite particles via one-step Pickering emulsion polymerization.

Core-shell structured polystyrene-gold composite particles are synthesized from one-step Pickering emulsion polymerization. The surface coverage of the core-shell composite particles is improved with increasing gold nanoparticle (AuNP) hydrophobicity and concentration. At high surface coverage, the AuNPs exhibit an ordered hexagonal pattern, likely due to electrostatic repulsion during the emulsion polymerization process.

Feasibility of nanofluid-based optical filters.

In this article we report recent modeling and design work indicating that mixtures of nanoparticles in liquids can be used as an alternative to conventional optical filters. The major motivation for creating liquid optical filters is that they can be pumped in and out of a system to meet transient needs in an application. To demonstrate the versatility of this new class of filters, we present the design of nanofluids for use as long-pass, short-pass, and bandpass optical filters using a simple Monte Carlo optimization procedure.

Nanofluid optical property characterization: towards efficient direct absorption solar collectors.

Suspensions of nanoparticles (i.e., particles with diameters < 100 nm) in liquids, termed nanofluids, show remarkable thermal and optical property changes from the base liquid at low particle loadings.

Comparative environmental and economic analysis of conventional and nanofluid solar hot water technologies.

This study compares environmental and economic impacts of using nanofluids to enhance solar collector efficiency as compared to conventional solar collectors for domestic hotwater systems. Results show that for the current cost of nanoparticles the nanofluid based solar collector has a slightly longer payback period but at the end of its useful life has the same economic savings as a conventional solar collector. The nanofluid based collector has a lower embodied energy (approximately 9%) and approximately 3% higher levels of pollution offsets than a conventional collector.