Transparent Photonic Crystal Heat Mirrors for Solar Thermal Applications

Rostami, Mohsen; Talebzadeh, Nima; O’Brien, Paul G.

doi:10.3390/en13061464

Cited by 13 publications

(7 citation statements)

References 48 publications

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“…2(c) to transmit solar radiation while reflecting a portion of the radiation from the emitter to reduce the amount of emission losses through the top port (F esc ) while increasing photon recycling (F BB ). 63,64 The best-case results for the STPV systems comprising a prolate spheroid [Fig. 1(b)], a prolate spheroid with an annular reflector [Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Furthermore, it should be noted that selective optical filters can be positioned at the top opening of the oblate cavity shown in Fig. 2(c) to transmit solar radiation while reflecting a portion of the radiation from the emitter to reduce the amount of emission losses through the top port (Fesc) while increasing photon recycling (FBB) 63 , 64 …”

Section: Resultsmentioning

confidence: 99%

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Spheroid-based optical cavities for tunable photon recycling and emitter temperature control in robust solar thermophotovoltaic systems

Talebzadeh

O’Brien

2023

J. Photon. Energy

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.The theoretical efficiency of solar thermophotovoltaic (STPV) systems is much greater than their efficiencies achieved in practice. Optical cavities can improve the performance of STPV systems by increasing the emitter-to-PV cell view factor and by facilitating photon recycling, whereby photons are reflected back to the emitter. Photon recycling reduces losses and increases the temperature of the emitter, thereby increasing efficiency. Our study presents STPV systems comprising optical cavities in the form of oblate and prolate spheroids. The geometry of the optical cavity can be tuned to control the degree of photon recycling, emitter temperature, emission losses, and the emitter-to-PV cell effective view factor and separation distance without using complex nano- or microstructured materials or optical filters. Numerical analysis shows an optical cavity in the form of a prolate spheroid, prolate spheroid with a middle annular aperture specular reflector, and integrated oblate- and prolate-spheroid can be used to achieve efficiencies of 17.7%, 18.9%, and 22%, respectively, under solar irradiation at a concentration factor of 1500X. These robust spheroid-based optical cavities can be used to design improved STPV systems with increased durability and higher performance.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Spheroid-based optical cavities for tunable photon recycling and emitter temperature control in robust solar thermophotovoltaic systems

Talebzadeh

O’Brien

2023

J. Photon. Energy

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“…After the electrochemical sy were immersed in a saturated CuCl2/HCl solution for a given time. T The optical properties of the PAA-based DBRs studied in this work could be attractive for application in transparent photonic crystal heat mirror (TPCHM) [39,40]. In principle, TPCHM works as infrared mirrors that decrease heat losses in the receiver of solar concentrators [36].…”

Section: Discussionmentioning

confidence: 99%

Charge Density-Versus Time-Controlled Pulse Anodization in the Production of PAA-Based DBRs for MIR Spectral Region

et al. 2021

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A robust and reliable method for fabricating porous anodic alumina (PAA)-based distributed Bragg reflectors (DBRs), operating in mid-infrared (MIR) spectral region, is presented. The method relies on application of high (UH) and low (UL) voltage pulse sequence repeated in cycles. PAA-based DBR consists of alternating high-(dH) and low-porosity (dL) layers translated directly into periodically varied refractive index. Two anodization modes were used: time- and charge density-controlled mode. The former generated dH + dL pairs with non-uniform thickness (∆d) and effective refractive index (∆neff). It is supposed, that owing to a compensation effect between the ∆d and ∆neff, the photonic stopbands (PSBs) were symmetrical and intensive (transmittance close to zero). Under the charge density-controlled mode dH + dL pairs of uniform thickness were formed. However, the remaining ∆neff provided an asymmetrical broadening of PSBs. Furthermore, it is demonstrated that the spectral position of the PSBs can be precisely tuned in the 3500–5500 nm range by changing duration of voltage pulses, the amount of charge passing under subsequent UH and UL pulses, and by pore broadening after the electrochemical synthesis. The material can be considered to be used as one-dimensional transparent photonic crystal heat mirrors for solar thermal applications.

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“…For example, filters that selectively reflect out-of-band photons while transmitting in-band photons can be integrated at the midplane of the ellipsoidal optical cavity or at the upper surface of the PV cell. Further, selective filters that transmit solar radiation while reflecting thermal radiation from the emitter can be placed at the opening at the top of the ellipsoidal optical cavity to further decrease the emission losses through the top opening (Fesc) [51]- [53]. As mentioned previously, the performance of selective emitters and filters can degrade due to extended exposure to high temperatures.…”

Section: Heat Load and Cooling Powermentioning

confidence: 99%

Ellipsoidal Optical Cavities for Enhanced Thermophotovoltaics

Talebzadeh

Pirvaram

O’Brien

2022

IEEE J. Photovoltaics

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Herein we present an optical cavity in the form of a prolate ellipsoid that can greatly enhance the performance of solar thermophotovoltaic (STPV) systems. The geometrical parameters of the cavity can be designed to control the degree of photon recycling, the temperature of the emitter within the STPV system, gap distance and effective view factor between the PV cell and the emitter, and to minimize the emission losses. Numerical analysis shows the ellipsoidal optical cavity can be designed to achieve an effective view factor of 88.7% between the emitter and PV cell within a STPV system. Results show an efficiency of 5.62% in a STPV system with a GaSb PV cell and a black-body emitter under solar radiation at a concentration factor of 350X. Further, assuming the surface of the ellipsoidal optical cavity is capable of reflecting 99% of the radiation incident onto its surface, efficiencies of 15.54% can be attained when the solar concentration factor is 1400X. These results are attained for STPV systems without using selective absorbers, emitters or filters. The ellipsoidal optical cavity can be integrated into the design of advanced TPV systems and bring them closer to the high theoretical efficiencies TPV systems are capable of.

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Transparent Photonic Crystal Heat Mirrors for Solar Thermal Applications

Cited by 13 publications

References 48 publications

Spheroid-based optical cavities for tunable photon recycling and emitter temperature control in robust solar thermophotovoltaic systems

Spheroid-based optical cavities for tunable photon recycling and emitter temperature control in robust solar thermophotovoltaic systems

Charge Density-Versus Time-Controlled Pulse Anodization in the Production of PAA-Based DBRs for MIR Spectral Region

Ellipsoidal Optical Cavities for Enhanced Thermophotovoltaics

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