The Experts below are selected from a list of 8493 Experts worldwide ranked by ideXlab platform
Kui Liu - One of the best experts on this subject based on the ideXlab platform.
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Ultra-precision machining of radial Fresnel Lens on roller moulds
CIRP Annals - Manufacturing Technology, 2015Co-Authors: Rui Huang, Xinquan Zhang, A. Senthil Kumar, Mustafizur Rahman, Kui LiuAbstract:In Roll-to-Roll manufacturing of optical films, direct diamond turning of radial Fresnel Lens structures on a roller mould was considered infeasible, due to the incapability to cut steep circular grooves on the outer cylindrical surface using conventional approach. This paper presents a novel solution to this problem. A four-axis interactive tool-workpiece motion is designed to precisely fabricate the complex microstructures. The tool path is generated from geometrical calculations considering the Lens design, tool geometries and roller parameters. This process is experimentally verified with qualified profile quality and surface finish, thus making direct machining of radial Fresnel Lens possible.
Takao Kashiwagi - One of the best experts on this subject based on the ideXlab platform.
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Flux densities in optimum nonimaging Fresnel Lens solar concentrators for space
Conference Record of the Twenty-Eighth IEEE Photovoltaic Specialists Conference - 2000 (Cat. No.00CH37036), 2000Co-Authors: Ralf Leutz, Atsushi Akisawa, Akio Suzuki, Takao KashiwagiAbstract:This paper aims at the clarification of flux density issues in solar Fresnel Lens concentrators for use in space photovoltaics. Using the novel nonimaging Fresnel Lens designed and prototyped by the authors as an example, flux densities are described as dependent on optical concentration ratio of the Lens, solar disk size and related brightness distribution, and spectral dispersion of incident sunlight. Discussing the results of a simulation, the optimum linear nonimaging Fresnel Lens concentrator is proposed in terms of concentration ratio, i.e. acceptance half angle pairs.
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design of a nonimaging Fresnel Lens for solar concentrators
Solar Energy, 1999Co-Authors: Ralf Leutz, Atsushi Akisawa, Akio Suzuki, Takao KashiwagiAbstract:An optimum convex shaped nonimaging Fresnel Lens is designed following the edge ray principle. The Lens is evaluated by tracing rays and calculating a projective optical concentration ratio. This Fresnel Lens is intended for use in evacuated tube type solar concentrators, generating mid-temperature heat to drive sorption cycles, or provide industrial process heat. It can also be used along with a secondary concentrator in photovoltaic applications.
Yanjun Dai - One of the best experts on this subject based on the ideXlab platform.
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performance investigation on a linear Fresnel Lens solar collector using cavity receiver
Solar Energy, 2014Co-Authors: Yanjun Dai, Meng Lin, K Sumathy, X K ZhaoAbstract:Abstract The optical and thermal performance of a linear Fresnel Lens solar collector using different types of cavity receiver is presented in this paper. The optical properties of the proposed Fresnel Lens solar collector was predicted by employing Monte Carlo ray trace method and thereby radiation distribution as well as the impact of incidence angle on optical performance was obtained. Triangular cavity receiver was found to have highest optical efficiency of 81.2%. Thermal performance was investigated by employing both numerical and experimental method. 2D mathematical model was developed considering conductive, convective and radiative heat losses. The CFD model was then validated by comparing simulation results with experimental results. For Fresnel Lens solar collector with triangular cavity receiver, the thermal efficiency was found to be around 30% at 120 °C. The analysis confirms that the Fresnel Lens solar collector with triangular cavity receiver boasts best performance in terms of both optical and thermal characteristics.
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experimental investigation and analysis on a concentrating solar collector using linear Fresnel Lens
Energy Conversion and Management, 2010Co-Authors: Hui Zhai, Yanjun Dai, R Z Wang, Liang ZhangAbstract:Abstract A concentrating solar collector based on linear Fresnel Lens is investigated experimentally in this paper. This solar collector is expected to acquire a higher thermal efficiency at a relatively high temperature level than the commonly used flat-plate or evacuated tube solar collectors. Experimental results show that the thermal efficiency is about 50% when the conversion temperature (water) is 90 °C. The test shows that the indication of lost energy is 0.578 W/m2 K, which is much smaller than that of commonly used evacuated tube solar collector without concentrating. In order to make analysis, a mathematical model for evacuated tube absorber heated by linear Fresnel Lens has been built. The validation shows that the model agrees with the experimental data well. The analysis indicates that Fresnel Lens collector with evacuated tube absorber has good efficiency (50%) in clear day even when the conversion temperature approaches 200 °C. The influence of ambient conditions and the percent of different types of energy loss, etc., are also analyzed.
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Experimental Studies on Highly Concentrated Solar Radiation by Using Fresnel Lens Group
Proceedings of ISES World Congress 2007 (Vol. I – Vol. V), 2008Co-Authors: Y. M. Han, Ruzhu Wang, Yanjun Dai, A. H. XiongAbstract:With advantages of lower volume, lower weight, smaller focal length and lower cost, Fresnel Lenses are suitable for solar radiation concentration, energy control, and system modularization. In this study, a modular device composed of two-stage Fresnel Lens is present and its performance is experimentally investigated for different conditions. Facular point image quality of Fresnel Lens is investigated by simulation for Lens battery design. As for the Fresnel Lens with 100mm in diameter, 220mm in focal length, when incident angle is kept within 1°, the focal point will not move out of the receiver domain with the dimension of 10mm* 10mm. when coupling with another Fresnel Lens of 30mm in diameter, it has found that 50~60% of the collected solar radiation can transmit through the Fresnel Lens group under condition of 1000 suns.
Ralf Leutz - One of the best experts on this subject based on the ideXlab platform.
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secondary optics for Fresnel Lens solar concentrators
Proceedings of SPIE, 2010Co-Authors: Ling Fu, Ralf Leutz, Hans Philipp AnnenAbstract:Secondary optics are used in concentrating photovoltaic (CPV) systems with Fresnel Lens primaries to increase the optical system efficiency by catching refracted light that otherwise would miss the receiver, better the tracking tolerance (acceptance half-angle) and enhance the flux uniformity on the cell. Several refractive secondary optics under the same Fresnel Lens primary are designed, analyzed and compared based on their optical performances, materials, manufacturability, manufacturing tolerancing and cost. The goal of this work is to show the basic two different design approaches statistical mixing as opposed to deterministic mixing. Caustics are elementary in the deterministic tailoring approach. We find that statistical mixing offers higher flexibility for the solar application. It is also shown that there are conventional, i.e. designs based on conic section ("half-egg") that work well as solar secondaries. It is also made clear that primary and secondary must be designed as optical train.
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Nonimaging Fresnel Lens Design
Springer Series in OPTICAL SCIENCES, 2001Co-Authors: Ralf Leutz, Akio SuzukiAbstract:A Fresnel Lens is essentially a chain of prisms. Each prism represents the slope of the Lens surface, but without the material of the full body of the conventional singlet. The imaging Fresnel Lens refracts light from an object and forms an image in the focal plane. Aberrations have an impact on the quality of the image; the imaging Lens should be free from such distortions. Due to the inaccurate manufacturing of the prism tips and grooves the image quality of Fresnel Lenses is inferior to the images produced by aspherical full Lenses.
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Flux densities in optimum nonimaging Fresnel Lens solar concentrators for space
Conference Record of the Twenty-Eighth IEEE Photovoltaic Specialists Conference - 2000 (Cat. No.00CH37036), 2000Co-Authors: Ralf Leutz, Atsushi Akisawa, Akio Suzuki, Takao KashiwagiAbstract:This paper aims at the clarification of flux density issues in solar Fresnel Lens concentrators for use in space photovoltaics. Using the novel nonimaging Fresnel Lens designed and prototyped by the authors as an example, flux densities are described as dependent on optical concentration ratio of the Lens, solar disk size and related brightness distribution, and spectral dispersion of incident sunlight. Discussing the results of a simulation, the optimum linear nonimaging Fresnel Lens concentrator is proposed in terms of concentration ratio, i.e. acceptance half angle pairs.
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design of a nonimaging Fresnel Lens for solar concentrators
Solar Energy, 1999Co-Authors: Ralf Leutz, Atsushi Akisawa, Akio Suzuki, Takao KashiwagiAbstract:An optimum convex shaped nonimaging Fresnel Lens is designed following the edge ray principle. The Lens is evaluated by tracing rays and calculating a projective optical concentration ratio. This Fresnel Lens is intended for use in evacuated tube type solar concentrators, generating mid-temperature heat to drive sorption cycles, or provide industrial process heat. It can also be used along with a secondary concentrator in photovoltaic applications.
Meng Lin - One of the best experts on this subject based on the ideXlab platform.
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performance investigation on a linear Fresnel Lens solar collector using cavity receiver
Solar Energy, 2014Co-Authors: Yanjun Dai, Meng Lin, K Sumathy, X K ZhaoAbstract:Abstract The optical and thermal performance of a linear Fresnel Lens solar collector using different types of cavity receiver is presented in this paper. The optical properties of the proposed Fresnel Lens solar collector was predicted by employing Monte Carlo ray trace method and thereby radiation distribution as well as the impact of incidence angle on optical performance was obtained. Triangular cavity receiver was found to have highest optical efficiency of 81.2%. Thermal performance was investigated by employing both numerical and experimental method. 2D mathematical model was developed considering conductive, convective and radiative heat losses. The CFD model was then validated by comparing simulation results with experimental results. For Fresnel Lens solar collector with triangular cavity receiver, the thermal efficiency was found to be around 30% at 120 °C. The analysis confirms that the Fresnel Lens solar collector with triangular cavity receiver boasts best performance in terms of both optical and thermal characteristics.
