A5088835155- Thermal Radiation and Cooling Technologies
- solar cell performance optimization
- Solar Thermal and Photovoltaic Systems
- Advanced Thermodynamics and Statistical Mechanics
- Photovoltaic System Optimization Techniques
- Aerogels and thermal insulation
- Quantum Electrodynamics and Casimir Effect
- Catalytic Processes in Materials Science
- Atmospheric Ozone and Climate
- Metamaterials and Metasurfaces Applications
- Transition Metal Oxide Nanomaterials
- Solar-Powered Water Purification Methods
- Phase Change Materials Research
- Nanomaterials for catalytic reactions
- Catalysis and Oxidation Reactions
- Electrocatalysts for Energy Conversion
- Nanofluid Flow and Heat Transfer
- Photonic Crystals and Applications
- Optical properties and cooling technologies in crystalline materials
- Heat Transfer and Optimization
- Thermal properties of materials
- Radiative Heat Transfer Studies
- Heat Transfer and Boiling Studies
- Advanced Photocatalysis Techniques
- Urban Heat Island Mitigation
University of Michigan
2015-2024
Michigan United
2019-2021
Massachusetts Institute of Technology
2010-2016
Institute of Chemical Engineering
2015
A high‐temperature stable solar absorber based on a metallic 2D photonic crystal (PhC) with high and tunable spectral selectivity is demonstrated optimized for range of operating temperatures irradiances. In particular, PhC absorptance 0.86 thermal emittance = 0.26 at 1000 K, using material properties, achieved resulting in transfer efficiency more than 50% higher that blackbody absorber. Furthermore, an integrated double‐sided absorber/emitter pair high‐performance thermophotovoltaic (STPV)...
A metallic dielectric photonic crystal with solar broadband, omni-directional, and tunable selective absorption high temperature stable (1000 °C, 24 hrs) properties is fabricated on a 6" silicon wafer. The broadband due to density of optical cavity modes overlapped an anti-reflection coating. Results allow for large-scale, low cost, efficient solar-thermal energy conversion.
Radiative cooling can alleviate urban heat island effects and passively improve personal thermal comfort. Among many emerging approaches, infrared (IR) transparent films fabrics are promising because they allow objects to directly radiate through bands of atmospheric transparency while blocking solar heating. However, achieving high reflectance maintaining IR transmittance using scalable nanostructured materials requires control over the shape size distribution nanoscale building blocks....
Rooftop solar thermal collectors have the potential to meet residential heating demands if deployed efficiently at low irradiance (i.e., 1 sun). The efficiency of depends on their ability absorb incoming energy and minimize losses. Most techniques utilize a vacuum gap between absorber surroundings eliminate conduction convection losses, in combination with surface coatings reradiation Here, we present an alternative approach that operates atmospheric pressure simple, black, absorbing...
The design and simulation of a wide angle, spectrally selective absorber/emitter metallic photonic crystal (MPhC) is presented. By using dielectric filled cavities, the angular, absorption/emission MPhC dramatically enhanced over an air by minimizing diffraction losses. Theoretical analysis performed verified via rigorous coupled wave (RCWA) based simulations. An efficiency comparison designs for solar thermophotovoltaic applications absorber emitter which yields 7% 15.7% improvement,...
Thermophotovoltaic (TPV) systems are a promising technology for distributed conversion of high-temperature heat to electricity. To achieve high efficiency, the transport sub-bandgap radiation between thermal emitter and PV cell should be suppressed. This can achieved by recycling back using spectrally selective cell. However, conventional TPV cells exhibit limited reflectance. Here we demonstrate thin-film In0.53Ga0.47As-based structures with spectral selectivity, including record-high...
Retaining high catalytic activity after exposure to elevated temperatures remains a crucial challenge for applications such as automotive emissions control. While catalysts generally sinter and lose aging at temperature, here we illustrate that palladium in core@shell morphology responds very differently. After 800 °C oxygen, redisperses into the encapsulating shell. The redispersion is more pronounced, nearly complete, when encapsulated by reducible ceria, opposed nonreducible silica. This...
Thermophotovoltaic (TPV) cells convert photons emitted from hot surfaces into electrical power. Unlike solar cells, TPV can be placed in close proximity to the heat source, allowing below-bandgap (i.e., out-of-band, OOB) reflected and reabsorbed by emitter. As reflectance of OOB approaches unity, spectral efficiency becomes increasingly insensitive bandgap cell source temperature. Here, we employ air-bridge structures with a lateral junction Si as means increasing reflectivity, which allows...
Mechanically stacked, tandem thermophotovoltaic (TPV) cells featuring integrated air-bridge InGaAs and InGaAsP subcells achieve high spectral efficiency emission temperature versatility. Thermocompression bonding of electrodes on opposing single increases out-of-band reflectance (ROUT) compared to lacking air bridges. We report a 0.74/0.74 eV homotandem exhibiting ROUT = 96.4%. When operated in multiterminal arrangement, the achieves 38% efficiency, marking 20% absolute improvement over...
The choice of heat transfer fluids has significant effects on the performance, cost, and reliability solar thermal systems. In this chapter, we evaluate existing such as oils molten salts based a new figure merit capturing combined storage capacity, convective characteristics, hydraulic performance fluids. Thermal stability, freezing point, safety issues are also discussed. Through comparative analysis, examine alternative options for including water−steam mixtures (direct steam), ionic...
The greenhouse effect arises when thermal radiation is forced to undergo absorption and re-emission many times before escaping, while sunlight transmits largely unimpeded. Although this responsible for global warming, it generally weak in solid-state materials because can be easily overpowered by other modes of heat transfer. Here, we report on the use infrared plasmonic nanoparticles enhance transparent mesoporous materials. Local surface plasmon resonances conducting oxide (TCO NPs)...
Utilizing the full solar spectrum is desirable to enhance conversion efficiency of a power generator. In practice, this can be achieved through spectral splitting between multiple converters in parallel. However, it unclear which wavelength bands should directed each converter order maximize efficiency. We developed model an ideal hybrid utilizes both single-junction photovoltaic cell and thermal engine. determined limiting efficiencies strategy corresponding optimum bandwidth cell. This...
Atomic layer deposition (ALD) modification of ultra-high-aspect-ratio structures (>10000:1) is a powerful platform with applications in catalysis, filtration, and energy conversion. However, the conformal tunable ALD coatings at these aspect ratios remains challenging, resulting empirical trade-offs between precursor utilization reaction time. Here, we demonstrate control infiltration depth into an aerogel monolith (AM) develop reaction-diffusion model to accurately describe coating process....