scholarly journals Ellipsoidal Optical Cavities for Enhanced Thermophotovoltaics

2021 ◽  
Author(s):  
Paul O'Brien ◽  
Nima Talebzadeh ◽  
Atousa Pirvaram
Keyword(s):  
Numerical Analysis ◽  
Solar Radiation ◽  
Concentration Factor ◽  
Optical Cavity ◽  
Black Body ◽  
Geometrical Parameters ◽  
View Factor ◽  
Optical Cavities ◽  
Pv Cell ◽  
Photon Recycling

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.

scholarly journals Ellipsoidal Optical Cavities for Enhanced Thermophotovoltaics

2021 ◽  
Author(s):  
Paul O'Brien ◽  
Nima Talebzadeh ◽  
Atousa Pirvaram
Keyword(s):  
Numerical Analysis ◽  
Solar Radiation ◽  
Concentration Factor ◽  
Optical Cavity ◽  
Black Body ◽  
Geometrical Parameters ◽  
View Factor ◽  
Optical Cavities ◽  
Pv Cell ◽  
Photon Recycling

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.

Geometrical shapes effects of optical cavity on entanglement dynamics of optomechanical systems: A numerical analysis

2021 ◽  
pp. 1-11
Author(s):  
Mehrad Gavahi ◽  
Hong Rong Li
Keyword(s):  
Steady State ◽  
Numerical Analysis ◽  
Optical Cavity ◽  
Entanglement Dynamics ◽  
Optomechanical System ◽  
Optomechanical Systems ◽  
Optical Cavities ◽  
Mechanical Coupling ◽  
Geometrical Shapes ◽  
Mechanical Oscillators

In this work, a model of optomechanical system was investigated by analyzing the entanglement dynamics of two related mechanical oscillators in a modified system. Geometrical shapes effects of optical cavities on entanglement of a representative optomechanical system were investigated by means of performing numerical analysis. It was signified that the steady-state or the dynamic behavior of optomechanical engagement could be created owing to the strength of mechanical pairs, which are strong towards the oscillating temperature. In addition, the mentioned entanglement dynamics were seen to be entirely related to the natural state’s stability. Furthermore, rendering the mechanical damping effects, the critical mechanical coupling strength-related analytical expression, where the transition from a steady state to a dynamic clamp occurs, was reported. In the studied system, two identical mechanical oscillators were formed in different conditions of the optical cavities shapes.

scholarly journals Calculation of the irradiance of solar radiation in a greenhouse with a complex structure using a diagram for sky view factor

2020 ◽  
Vol 76 (1) ◽  
pp. 44-52
Author(s):  
Shuh MATSUDA ◽  
Hisashi YOSHIKOSHI ◽  
Tomoyo SUZUKI ◽  
Yuuki OHTA ◽  
Ayaka CHIBA ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Complex Structure ◽  
View Factor ◽  
Sky View Factor

Engineering the sensitivity of macroscopic physical systems to variations in the fine-structure constant

2021 ◽  
Author(s):  
Beata Zjawin ◽  
Marcin Bober ◽  
Roman Ciuryło ◽  
Daniel Lisak ◽  
Michał Zawada ◽  
...  
Keyword(s):  
Fine Structure ◽  
Optical Cavity ◽  
Structure Constant ◽  
Relativistic Effects ◽  
Fine Structure Constant ◽  
Sensitivity Factor ◽  
Optical Cavities ◽  
Physical Systems ◽  
Heavy Atoms ◽  
Nuclear Transitions

Abstract Experiments aimed at searching for variations in the fine-structure constant α are based on spectroscopy of transitions in microscopic bound systems, such as atoms and ions, or resonances in optical cavities. The sensitivities of these systems to variations in α are typically on the order of unity and are fixed for a given system. For heavy atoms, highly charged ions and nuclear transitions, the sensitivity can be increased by benefiting from the relativistic effects and favorable arrangement of quantum states. This article proposes a new method for controlling the sensitivity factor of macroscopic physical systems. Specific concepts of optical cavities with tunable sensitivity to α are described. These systems show qualitatively different properties from those of previous studies of the sensitivity of macroscopic systems to variations in α, in which the sensitivity was found to be fixed and fundamentally limited to an order of unity. Although possible experimental constraints attainable with the specific optical cavity arrangements proposed in this article do not yet exceed the present best constraints on α variations, this work paves the way for developing new approaches to searching for variations in the fundamental constants of physics.

scholarly journals Design and simulation of bio fluidic sensor based on photonic crystal

2014 ◽  
Vol 3 (2) ◽  
pp. 106
Author(s):  
Rajini Gaddam Kesava Reddy ◽  
Sharmila Ashok kumar ◽  
Sankardoss Varadhan
Keyword(s):  
Photonic Crystals ◽  
Photonic Band Gap ◽  
Optical Cavity ◽  
Fdtd Method ◽  
High Sensitivity ◽  
Three Dimensions ◽  
Fluidic Channel ◽  
Optical Cavities ◽  
Fluid Sensor ◽  
On Chip

Photonic crystals are materials patterned with a periodicity in dielectric constant in one, two and three dimensions and associated with Bragg scattering which can create range of forbidden frequencies called Photonic Band Gap (PBG). By optimizing various parameters and creating defects, we will review the design and characterization of waveguides, optical cavities and multi-fluidic channel devices. We have used such waveguides and laser nanocavities as Biosensor, in which field intensity is strongly dependent on the type of biofliud and its refractive index. This design and simulation technique leads to development of a nanophotonic sensor for detection of biofluids. In this paper, we have simulated sensing of biofliud in various photonic defect structures with the help of a numerical algorithm called Finite Difference Time Domain (FDTD) method. The simulation result shows the high sensitivity for the change in the bio-molecular structure. For developing the complete sensor system, we have to use the MEMS technologies to integrate on-chip fluidic transport components with sensing systems. The resulting biofluidic system will have the capability to continuously monitor the concentration of a large number of relevant biological molecules continuously from ambulatory patients. Keywords: FDTD, Photonic Crystals, Bio fluid Sensor, Optical Cavity.

Solar Radiation at 1200 MC/S., 600 MC/S., and 200 MC/S

1949 ◽  
Vol 2 (1) ◽  
pp. 48 ◽  
Author(s):  
FJ Lehany ◽  
DE Yabsley
Keyword(s):  
Magnetic Field ◽  
Body Temperature ◽  
Solar Radiation ◽  
Thermal Emission ◽  
Black Body ◽  
Sunspot Area ◽  
The Sun ◽  
Long Period ◽  
Period Variations ◽  
The Magnetic Field

Daily observations of solar radiation at frequencies of 1200 Mc/s., 600 Mc/s., and 200 Mc/s. taken between August 18 and November 30, 1947, are described. The characteristics of the radiation at 200 Mc/s. were in general agreement with those observed by earlier workers. At 600 Mc/s. and 1200 Mc/s., the received intensity was normally steady on any one day but underwent long-period variations over a range of about two to one. The radiation received when the sun was almost free of sunspots corresponded to an effective black-body temperature of 0.5 million �K. at 600 Mc/s. and 0.1 million �K. at 1200 Mc/s. As sunspots appeared, the temperature rose and showed marked oar- relation with sunspot area. It is considered that radiation at these frequencies is entirely thermal in origin and that the long-period variations are at least partly due to the influence of the magnetic field of sunspots on the mechanism of thermal emission from a magneto-ionic medium. On a few occasions, isolated disturbances were observed on 600 Mc/s. and 1200 Mc/s. some of which were associated with chromospheric flares and radio fade-outs. The difficulties arising in the calibration of the apparatus and the steps taken to overcome them are discussed in detail.

The Modeling of Solar Cells

2014 ◽  
Vol 716-717 ◽  
pp. 1438-1441
Author(s):  
Chun Li ◽  
Shi Qiong Zhou
Keyword(s):  
Solar Cell ◽  
Solar Radiation ◽  
Solar Energy ◽  
Research And Development ◽  
Mathematic Model ◽  
Load Impedance ◽  
Power Resources ◽  
The World ◽  
Pv Cell ◽  
Practical Engineering

The world is increasingly experiencing a great need for additional power resources so as to reduce dependency on conventional sources, and solar energy could be an answer to that need. However, the performance of solar energy depends on solar radiation, ambient temperature, and load impedance. A practical engineering mathematic model of solar cell is developed and a general simulation model of PV cell is created based on Simulink system, which is convenient to be applied to the research and development of solar cell.

scholarly journals Aspect controls the survival of ice cliffs on debris-covered glaciers

2018 ◽  
Vol 115 (17) ◽  
pp. 4369-4374 ◽  
Author(s):  
Pascal Buri ◽  
Francesca Pellicciotti
Keyword(s):  
Solar Radiation ◽  
Mass Balance ◽  
Hot Spots ◽  
3D Model ◽  
Vertical Gradient ◽  
High Mass ◽  
View Factor ◽  
High Mountain ◽  
Mass Losses ◽  
Very High

Supraglacial ice cliffs exist on debris-covered glaciers worldwide, but despite their importance as melt hot spots, their life cycle is little understood. Early field observations had advanced a hypothesis of survival of north-facing and disappearance of south-facing cliffs, which is central for predicting the contribution of cliffs to total glacier mass losses. Their role as windows of energy transfer suggests they may explain the anomalously high mass losses of debris-covered glaciers in High Mountain Asia (HMA) despite the insulating debris, currently at the center of a debated controversy. We use a 3D model of cliff evolution coupled to very high-resolution topographic data to demonstrate that ice cliffs facing south (in the Northern Hemisphere) disappear within a few months due to enhanced solar radiation receipts and that aspect is the key control on cliffs evolution. We reproduce continuous flattening of south-facing cliffs, a result of their vertical gradient of incoming solar radiation and sky view factor. Our results establish that only north-facing cliffs are recurrent features and thus stable contributors to the melting of debris-covered glaciers. Satellite observations and mass balance modeling confirms that few south-facing cliffs of small size exist on the glaciers of Langtang, and their contribution to the glacier volume losses is very small (∼1%). This has major implications for the mass balance of HMA debris-covered glaciers as it provides the basis for new parameterizations of cliff evolution and distribution to constrain volume losses in a region where glaciers are highly relevant as water sources for millions of people.

scholarly journals A Study of the Thermal Environment and Air Quality in Hot–Humid Regions during Running Events in Southern Taiwan

Atmosphere ◽  
2020 ◽  
Vol 11 (10) ◽  
pp. 1101
Author(s):  
Si-Yu Yu ◽  
Andreas Matzarakis ◽  
Tzu-Ping Lin
Keyword(s):  
Air Quality ◽  
Solar Radiation ◽  
Thermal Comfort ◽  
Real Time ◽  
Thermal Environment ◽  
Monitoring Data ◽  
Integrated Analysis ◽  
View Factor ◽  
Thermal Discomfort ◽  
Southern Taiwan

It is quite difficult to investigate thermal comfort in hot–humid regions, and there have not been many real case studies or research related to this issue. In this article, four running events held in nearby popular travel spots in Kaohsiung, the largest city in southern Taiwan, were selected to analyze the influence of thermal environment and air quality on thermal comfort. Mostly real time environmental monitoring data were applied for estimating thermal indicators, along with Sky View Factor (SVF) data taken at the sites of the running scheduled routes, to analyze the thermal performance of participants at running events. Compared with runners, walkers (local residents, fans, and staff of the events) would be exposed to a greater risk of thermal discomfort with increasing time spent on the routes. With the integrated analysis, mPET (modified physiologically equivalent temperature) can be viewed as a relatively comprehensive indicator in considering both environmental thermal conditions and the biometrical differences of activities and clothing types. From the results, a good correlation between mPET and solar radiation/SVF was obtained, which indicated that mPET could be sufficiently sensible in revealing the thermal condition variation from one site to another during the route with time. Based on the discomfort risk assessment, for runners, the event held in autumn with lower SVF at the route sites would be less risky of thermal discomfort, while the event held in spring with lower solar radiation would be more comfortable for walkers. As for air quality condition, the inappropriateness of holding winter outdoor activities in Kaohsiung was obviously shown in both real time monitoring data and long term analysis.

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