Design and global optimization of high-efficiency thermophotovoltaic systems

Massachusetts Institute of Technology, Cambridge, 02139, USA.
Optics Express (Impact Factor: 3.49). 09/2010; 18 Suppl 3(19):A314-34. DOI: 10.1364/OE.18.00A314
Source: PubMed


Despite their great promise, small experimental thermophotovoltaic (TPV) systems at 1000 K generally exhibit extremely low power conversion efficiencies (approximately 1%), due to heat losses such as thermal emission of undesirable mid-wavelength infrared radiation. Photonic crystals (PhC) have the potential to strongly suppress such losses. However, PhC-based designs present a set of non-convex optimization problems requiring efficient objective function evaluation and global optimization algorithms. Both are applied to two example systems: improved micro-TPV generators and solar thermal TPV systems. Micro-TPV reactors experience up to a 27-fold increase in their efficiency and power output; solar thermal TPV systems see an even greater 45-fold increase in their efficiency (exceeding the Shockley-Quiesser limit for a single-junction photovoltaic cell).

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Available from: Ivan Celanovic, Jan 03, 2014
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    • "Micro/nanostructured materials have drawn great attention due to their potential applications [1] [2] [3], such as thermophotovoltaic emitters [4] [5], selective solar absorbers [6] [7], and biological sensors [8]. Most electromagnetic metamaterials consist of periodic nano/microstructures that exhibit exotic characteristics by excitation of resonances [9]. "
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    ABSTRACT: Metamaterial thermal emitters and absorbers have been widely studied for different geometric patterns by exciting a variety of electromagnetic resonances. A resistor–inductor–capacitor (RLC) circuit model is developed to describe the magnetic resonances (i.e. magnetic polaritons) inside the structures. The RLC circuit model allows the prediction of not only the resonance frequency, but also the full width at half maximum and quality factor for various geometric patterns. The parameters predicted by the RLC model are compared with the finite-difference time-domain simulation. The magnetic field distribution and the power dissipation density profile are also used to justify the RLC circuit model. The geometric effects on the resonance characteristics are elucidated in the wire (or strip), cross, and square patterned metamaterial in the infrared region. This study will facilitate the design of metamaterial absorbers and emitters based on magnetic polaritons.
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    • "While band-pass filters may be used to improve the overall efficiency, this method is cumbersome and overheating of the filter may become problematic [7– 9]. Therefore, wavelength-selective emitter is crucial to improve the conversion efficiency and power generation of TPV systems [10] [11]. "
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    ABSTRACT: Thermophotovoltaic (TPV) devices can convert thermal radiation directly into electricity. To improve the efficiency of TPV systems, wavelength-selective emitters are designed to take thermal energy from various heat sources and then emit photons to the TPV cells. A two-dimensional grating/thin-film nano-structure is proposed as an efficient emitter, whose performance is enhanced by the excitations of both surface plasmon polaritons (SPPs) and magnetic polaritons (MPs). Rigorous coupled-wave analysis is used to predict the emittance as well as the electromagnetic field and current density distributions. The normal emittance of the proposed nanostructure is shown to be wavelength-selective and polariza-tion-insensitive. The mechanisms of SPP and MP excitations in the nanostructure are elucidated for different polarizations. The current–density loop further confirms the existence of magnetic resonances. Furthermore, the effect of azimuthal and polar angles on the emittance spectra is also investigated, suggesting that the proposed structure has high emittance not only in the normal direction but also at large oblique angles.
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    • "The efficiency of each subsystem can be further decomposed into its component parts. In particular, the selective solar absorber efficiency can be represented by [5,11]: "
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    ABSTRACT: Selective solar absorbers generally have limited effectiveness in unconcentrated sunlight, because of reradiation losses over a broad range of wavelengths and angles. However, metamaterials offer the potential to limit radiation exchange to a proscribed range of angles and wavelengths, which has the potential to dramatically boost performance. After globally optimizing one particular class of such designs, we find thermal transfer efficiencies of 78% at temperatures over 1,000°C, with overall system energy conversion efficiencies of 37%, exceeding the Shockley-Quiesser efficiency limit of 31% for photovoltaic conversion under unconcentrated sunlight. This represents a 250% increase in efficiency and 94% decrease in selective emitter area compared to a standard, angular-insensitive selective absorber. PACS: 42.70.Qs; 81.05.Xj; 78.67.Pt; 42.79.Ek
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