Fresnel Lens Research Articles

A combined thermal and electrical performance evaluation of low concentration photovoltaic systems

Due to the expectations of improving the overall efficiency of photovoltaic installation, the increase solar irradiation that could be converted into electricity should be considered as an alternative solution for existing PV technologies. Low-concentration photovoltaic systems such as reflective surfaces or Fresnel micro lens plates were chosen for this study because they were economically justified and easy to install and maintain. The low concentration systems were studied theoretically and experimentally under sunny and cloudy weather conditions. After the initial optimization of the system geometry and construction, both electrical and thermal performances were evaluated and compared with a reference PV panel. In addition, the effect of additional irradiation as well as panel temperature was studied for a specific period using thermography and digital image techniques. It was revealed that the highest improvement in energy performance was achieved by the panel with reflective surfaces, while the Fresnel plate considered here slightly decreased this performance in comparison with the reference case. The consideration ends with an economic analysis of both systems in the case of free-standing PV installation and a list of recommendations are presented, based on the empirical results. The highest improvement of energy performance can be achieved by the implementation of reflective surfaces, about 20% of the average daily global efficiency, and 15% on electrical production. In the case of the Fresnel micro lens, a decrease in both global efficiency and electricity production is observed, 8% and 21%, respectively. Regarding the temperature of PV panels, significant overheating was not registered; about 45–55 °C for the entire experimental test.

Thermal analysis of a box type solar cooker coupled with Fresnel lens

The thermal analysis of a Box-type solar cooker (BTSC) coupled with two Fresnel lens magnifiers (FLMG) is presented in this paper. A time dependent numerical model based on heat balances occurring at different parts of the cooker was prepared and executed in a MATLAB program. To check the robustness of the model, the temperature variation of the cooker elements obtained by the mathematic modeling was compared with the experimental results. The comparison showed the average estimated error between the experimental and numerical values fell between 0.73–3.49 percentage. In order to check the effectiveness of the FLMG, First Figure of merit (F1) and Second figure of merit (F2) tests were performed as per international testing procedures. The first figure of merit value increased from 0.11 to 0.12 m2 °C/W, converting the BTSC from B grade category to A grade. The Second figure of merit rose from 0.43 to 0.45 by utilizing the FLMG, indicating the improvement in heat exchange to the load in the cooking vessel. The temperature of all the components of the BTSC was increased by incorporating the FLMG. The paper also discusses the variation of different heat transfer coefficients coming to play in the cooker. Basmati rice was successfully cooked by the solar cooker in an interval of 58 min.

Dual projectile beams.

Accelerating beams, of which the Airy beam is an important representative, are characterized by intensity maxima that propagate along curved trajectories. In this work we present a simple approach to directly generate accelerating beams with controllable trajectories by means of binary phase structures that consist of only a π phase step modulation in comparison to previous studies where two-dimensional cubic phase modulations for example are required, and which have practical limitations due to their challenging fabrication with phase plates or diffractive optical elements (DOEs), or the spatially extended system needed for their generation at the Fourier plane. In our approach, two intensity maxima are formed that propagate along root parabolic trajectories in contrast to Airy and higher order caustic beams that propagate along a parabolic curve, hence we call these beams Dual Projectile Beams (DPBs). By tailoring a step or slit phase patterns with additional Fresnel lenses, we either generate hollow-core or abruptly focusing beams and control their curvatures. Moreover, using DPBs as a simpler complement to complex structured light fields, we demonstrate their versatility at the example of their interaction with nonlinear matter, namely the formation of a spatial soliton in a photorefractive material. We show that the formed solitary state propagates almost unchanged for a distance of several Rayleigh lengths. This light matter interaction can be regarded as a light beam deceleration. The simplicity of this approach makes these beams suitable for integrated optics and high-power laser applications using DOEs or meta-surfaces.

Solar collector tube as secondary concentrator for significantly enhanced optical performance of LCPV/T system

Improving efficiency, controlling cost and reducing the temperature of solar cells are great challenges for linear concentrated photovoltaic/thermal systems (LCPV/T). In this work, we report a new design with a linear Fresnel lens as the primary optical element and an additional multi-functioned solar collector tube as the secondary optical element. With such design, the low-cost solar collector tube acts multiple roles simultaneously, i.e., lens, spectral beam-splitting filter and heat collector. It was demonstrated that the addition of such multi-functional solar collector tube in LCPV/T system can significantly increase the irradiation uniformity and decrease the average temperature of photovoltaic (PV) module under the same thermal condition, which results in the improved electricity output performance of PV module. Under the solar irradiance and ambient temperature for a typical daytime, the average electrical, thermal and total energy efficiencies of the proposed system are 11.39%, 64.72% and 76.11%, respectively. Our work should be of guidance for the design of LCPV/T system with high efficiency, long-life and low cost.

Femtosecond Laser Direct Writing of Gradient Index Fresnel Lens in GeS2-Based Chalcogenide Glass for Imaging Applications

Chalcogenide glasses have attracted growing interest for their potential to meet the demands of photonic applications in the Mid-Wavelength InfraRed (MWIR) and Long-Wavelength InfraRed (LWIR) transmission windows. In this work, we investigated the photosensitivity to femtosecond laser irradiation of a dedicated chalcogenide glass, along with its possible applications in micro-optics. In order to address the SWaP problem (Size, Weight and Power), this work took advantage of recent techniques in femtosecond laser direct writing to imprint flat and integrated optical systems. Here, we wanted to simplify an infrared multispectral imaging system which combines a lens array and a filter array. Each channel has a focal length of 7 mm and an f-number of 4. We show in this paper that the chosen GeS2-based chalcogenide glass is very promising for the fabrication of graded index optics by fs-laser writing, and particularly for the fabrication of Fresnel lenses. We note a very important phase variation capacity in this infrared material corresponding to refractive index variations up to +0.055. A prototype of Fresnel GRIN lens with a refractive index gradient was fabricated and optically characterized in the Vis range.

Harnessing and cloaking optical boundary in lens-array based display

Optical boundaries are basic structures for optical system and they become visible where reflection and refraction occur. The visible boundary is very often presented as a nuisance to optical systems in imaging recording or in display. Harnessing the optical boundaries up to a complete carpeting is scientifically interesting and technologically important. This work describes the concept, design, fabrication and testing of novel Fresnel lens array with tailored microstructures to carpet the optical boundaries while the functionality such as focusing and deflection can be retained. A gradually interleaved and periodically arranged micro-structured Fresnel lens sheet acting as low band pass filter lens array is proposed, fabricated and tested. The novel Fresnel lens array is demonstrated to remain the optical features for perfect planar display. When it is applied to a backlight illuminated display system, tailored illumination with local dimming further helps improving the visual homogeneity. The combined use of these new techniques allows the boundary cloaked completely over a large viewing directional range for broad visible spectra. The cloaking technique is applied as an immediate example to an autostereoscopic display system and is shown to be practical and valid for imaging and display optics.

The Experimental Investigation of a New Panel Design for Thermoelectric Power Generation to Maximize Output Power Using Solar Radiation

It is well established that renewable energy resources for electricity generation are free. In hot areas, solar energy has become one of the major interests of researchers and specialists. This paper aims to experimentally investigate the maximum voltage generation of a thermoelectric generator (TEG) panel. This panel was built from many TEG modules that are connected in series and in parallel. The panel was exposed to high heat due to solar radiation during summer, either directly or through a Fresnel lens. The other side of the TEG panel was cooled using tap water that was passed through aluminum heat exchangers in an active cooling method. It was found that the maximum open-circuit voltage of this TEG panel using a Fresnel lens was 9.35 V. With no lens, it was 11.75 V at 14:00 h local time. The experiments were done during a sunny July period in Iraq.

Fabrication of polygonal Fresnel lenses with a rotating cutting tool on three-axis ultraprecision lathes

Fresnel lenses are gaining wider applications due to their advantages of being lighter, thinner and suitable for increasingly complex and miniaturized optical systems. To increase the fill factor when combining multiple Fresnel lenses to form an array, polygonal Fresnel lenses have been designed and machined with the ultra-precision machine tools in industry. However, for the three-axis machine tool equipped with the X-, Z-, and C-axes, it is difficult to machine the straight edges of the polygonal Fresnel lens due to the lack of a Y-axis. Although the synchronized servo motions of the linear axis and the spindle can be utilized to fit the relative motion trajectory of the tool to a straight line, the cutting tool rotates relative to the workpiece and thus the tool rake face is not always perpendicular to the direction of the relative motion during machining. In this paper, a high-precision rotating platform is integrated into the three-axis ultra-precision machine tool to make the cutting tool track the rotation of the spindle and keep the tool rake face perpendicular to the direction of the relative motion at all times. Then the tool trajectory is generated and the influence of the tool nose radius is compensated. Finally, an experiment of cutting the hexagonal Fresnel lens is performed on a three-axis ultra-precision lathe, and the machined workpiece is inspected with a white light interferometer. The experimental results show that the profile accuracy of the machined polygonal Fresnel lens satisfies the requirements in industrial applications.

Analysis, evaluation and integration of modular natural illumination system using a rectangular Fresnel lens for high performance

Daylighting using natural illumination system (NILS) is gaining popularity due to transition to the renewable and non-conventional energy resources. In the proposed work, optomechanical design, numerical analysis, experimentation and integration of a modular Fresnel lens for NILS to effectively harness the sunlight is discussed. The modular and integrated design delivers uniform light at the receiving area of the daylight transportation system. This modular Fresnel lens is a combination of linear Fresnel lenses designed to offer a moderate concentration ratio to avoid hot spots. The distribution of solar radiation on the focal plane/entry section of the plastic optical fibre bundle (daylight transportation system) is simulated using the ray-trace technique for a lens system with a concentration ratio of 81. The irradiance distributions at the focal plane were found uniform with a radiometric and photometric transmission efficiency of 72.45% and 85.96%, respectively, for the lens element. The overall photometric transmission efficiency of the system with 10 m long plastic/acrylic optical fibre cable was found as 40.97%.

Impacts of seasonal dust accumulation on a point-focused Fresnel high-concentration photovoltaic/thermal system

Dust accumulation on the concentrator of a high concentration photovoltaic/thermal (HCPVT) system can cause significant performance loss. In our work, the effect of seasonal dust deposition on the output performance of an HCPVT system with a point-focused Fresnel lens was studied in natural dust-deposition experiments. The changes of thermoelectric performance and exergy performance of the system under different dust accumulation levels were analyzed, and the influence of dust accumulation density on the total efficiency was determined. The results show that when the average dust density increases by 1 g/m2, the transmittance of the Fresnel lens decreases by 2.73%, thermal efficiency by 7.58%, and electrical efficiency by 1.74%. The temperature rise of the all-day operation system decreased by 2.31%, and the exergy efficiency loss reached 17.32%. Model fitting and calculation show that when the dust concentration is 8.81 g/m2, the all-day total/thermoelectric power output is 5.27 kW less than that with a clean lens.

A Polyimide-Based Photocatalyst for Continuous Hydrogen Peroxide Production Using Air and Water under Solar Light

A Polyimide-Based Photocatalyst for Continuous Hydrogen Peroxide Production Using Air and Water under Solar Light

Solar spectral beam splitting for photochemical conversion and polygeneration

Conversion efficiency from sunlight to electricity is relatively low for both solar thermal and photovoltaic converters, where more than three quarters of the solar energy is dissipated back to the environment. Division of the solar spectrum (spectral splitting) enables better use of photon energy in each spectral band. Here we present a polygeneration approach to solar energy conversion where the main contribution is a photochemical process, while co-producing power and medium grade heat. A collector design is introduced with a linear Fresnel lens, a ‘cold mirror’ spectral filter, and photochemical, photovoltaic, and thermal converters. To illustrate a wide scope of applications, three photochemical options are investigated: photonitrozation of cyclohexane, photooxigenation of citronellol, and catalytic disinfection of wastewater. The analysis of conversion efficiency uses detailed optical modeling based on realistic (commercially available) component properties and on experimental characterization of participating compounds. Overall system efficiency is up to 50%. The amount of electricity displaced or saved vs. current lamp-driven photochemical processes can reach as high as 97% of the incident solar energy, for several combinations of photochemical and photovoltaic converters. The polygeneration approach can be implemented using low-cost components and may lead to cost-effective, highly efficient solutions with a significant contribution to displacement of conventional energy sources.

Exergy and SCAPS 1-D Analysis on Modified Thermophotovoltaic Cell with Fresnel Lens Concentrator and Absorber–Emitter Materials

Exergy and SCAPS 1-D Analysis on Modified Thermophotovoltaic Cell with Fresnel Lens Concentrator and Absorber–Emitter Materials

Design and implementation of an active optimized optical green energy generation system using ultraviolet solar irradiance

This paper proposes a methodology of optimum power point tracking for tandem solar cell technology to generate green energy. It utilizes an active optical solar tracking and concentrating system, employing ultraviolet (UV) parts: UVA and UVB (280–400 nm), from the solar irradiations. Hence, devises a methodology to avoid complex maximum power point tracking hardware and presents a use of UV solar irradiation. It can be used as an alternative to the conventional concentrated photovoltaic system as well. The performance of the proposed system is also optimized for its output power fixed at a required value of the interest with fewer fluctuations and heating effects. Working of the proposed system is based on a solar irradiance, intensity-dependent axial movement of the light funnel with its variable aperture, and the W/m2 created by a Fresnel lens. The proposed system finds its utility for places where the UV index is recorded at its highest ≥ +11 allowing UV radiations to reach the earth at high levels. The proposed approach is validated, to fulfill fixed energy demand of a thermolysis process against its constant output power claim. For the purpose, firstly absorption response of a quadruple junction solar cell is investigated and made sure that it is capable of operating on UVA and UVB. Secondly, to achieve a constant irradiance level on solar panel surface, control systems along three-axes are designed based on the least-squares optimization criterion to minimize the tracking error and keep the irradiation fixed to a reference value of 1000 W/m2.

Performance analysis of a concentrated system with series photovoltaic/thermal module and solar thermal collector integrated with PCM and TEG

This study presents a detailed performance analysis of a novel concentrated system which consists of a photovoltaic/thermal (PV/T) module with phase change material (PCM) and a solar thermal (ST) collector with thermoelectric generators (TEG) connected in series. While considerable electrical energy is acquisitive, enhanced high-temperature thermal energy is also achieved. In this system, the PV/T module generates both photoelectric power generation and low-temperature thermal energy, and the secondary heated water and the secondary thermoelectric output are obtained through the ST module and TEG on ST. Theoretical investigations find that, the system of the PV/T module and the ST module in series (PV/T-ST) performs well in terms of thermal performance and comprehensive performance. During the all-day operation, compared with the PV/T-PV/T system, the final temperature of the water tank in the PV/T-ST system is about 5 °C higher. Also, the electrical efficiency and the thermal efficiency are 10.65% and 65.22% respectively at 12:30 when using the 1.1-m2 Fresnel lens. Where, TEG converts some thermal energy into electrical energy, increasing the amount of high-grade energy of the system by about 321.53 kJ in the daytime. Additionally, the discussion from different perspectives on the impact of different parameters is also carried out.

\u03bb/30 inorganic features achieved by multi-photon 3D lithography

It’s critically important to construct arbitrary inorganic features with high resolution. As an inorganic photoresist, hydrogen silsesquioxane (HSQ) has been patterned by irradiation sources with short wavelength, such as EUV and electron beam. However, the fabrication of three- dimensional nanoscale HSQ features utilizing infrared light sources is still challenging. Here, we demonstrate femtosecond laser direct writing (FsLDW) of HSQ through multi-photon absorption process. 26 nm feature size is achieved by using 780 nm fs laser, indicating super-diffraction limit photolithography of λ/30 for HSQ. HSQ microstructures by FsLDW possess nanoscale resolution, smooth surface, and thermal stability up to 600 °C. Furthermore, we perform FsLDW of HSQ to construct structural colour and Fresnel lens with desirable optical properties, thermal and chemical resistance. This study demonstrates that inorganic features can be flexibly achieved by FsLDW of HSQ, which would be prospective for fabricating micro-nano devices requiring nanoscale resolution, thermal and chemical resistance.

Design and experimental study of a Fresnel lens-based concentrated photovoltaic thermal system integrated with nanofluid spectral splitter

Minimizing optical losses during light focusing and preparing an appropriate nanofluid for spectral splitting is crucial for the performance of a concentrated photovoltaic thermal system. A Fresnel lens-based solar concentrator integrated with a nanofluid spectral splitting photovoltaic thermal system was designed and validated in this study. The design posited solar irradiation being appropriately concentrated by a linear Fresnel lens on a series of tubes through which the nanofluid flowed, allowing a large beam of limited spectra to be transmitted to the PV below, with the rest absorbed and converted to thermal energy is introduced. The optical loss was minimized by increasing the surface area and decreasing the optical path length. The synthesized nanofluid's spectral transmittance was measured experimentally. Dynamic modeling energy balance equation for the concentrated solar energy conversion system was developed and computed by MATLAB programming. Since the photovoltaic module was decoupled from the filtering channel and integrated with the water cooling, its surface temperature was much lower than the nanofluid and output water temperature. The combined efficiency of the system was 50.35%, 65.2%, 72.70%, 74.7%, and 85% for ZnO nanofluids with volume concentration ratios of 0.00036%, 0.00089%, 0.0017%, 0.0036%, and 0.0089%, respectively. A nanofluid with a concentration ratio of 0.00089 vol% provides the closest spectral match with a silicon solar cell, as verified by a reasonable electrical and thermal efficiency. We used this as a representative concentration ratio of ZnO nanoparticles to validate the prototype. The maximum deviation between simulated and experimentally determined overall performance was less than 3.7% which shows the two results are in good agreement. The findings highlight the potentials of employing a low-cost ZnO nanofluid in a concentrated photovoltaic thermal system for full spectrum utilization.

Energy and exergy based study on a box type solar cooker coupled with a Fresnel lens magnifier

ABSTRACT The variation of energy and exergy efficiency of a Box-type solar cooker (BTSC) incorporated with a Fresnel lens magnifier (FLMG) is evaluated in this study. The comparison in energy and exergy efficiency was investigated in the absence and presence of the FLMG to determine the efficiency variation of the BTSC by addition of the FLMG. With the implementation of FLMG, the average values of energy and exergy efficiencies had increased by 10% and 8.52%, respectively. The magnitude of energy efficiency with and without FLMG decreased with time, whereas the exergy efficiency enhanced with time for both cases. The manuscript discusses the effect of different thermodynamic parameters like temperature difference, energy and exergy output, absorber mean plate temperature, and heat losses in the modified cooker. The total heat loss coefficient ranged from 5.48 to 8.44 W/m2K and depended on the variation of wind velocity. The maximum heat loss and mean plate temperature were found to be 120 kJ and 128.3°C, respectively. The time for sensible heating was reduced by 16 mins by the implementation of the FLMG. The addition of the lens showed an increase in the Area concentration ratio (AR) of the BTSC by 48.7%. By comparing the cost and energy usage of LPG (Liquefied Petroleum Gas), the payback period and the quantity of carbon dioxide reduced per month were calculated as 3.19 years and 8.265 kg, respectively.

Thermal performance assessment of the world’s first solar thermal Fresnel lens collector field

Fresnel lenses are used in a wide range of solar energy applications, primarily due to their reduced material usage, low cost, and high optical efficiency. This study presents an investigation of the world’s first full-scale Fresnel lens solar collector field. The collector field consists of 144 two-axis tracking solar collectors manufactured by the Danish company Heliac and supplies heat to the local district heating network in Lendemarke, Denmark. The thermal performance of the solar collector field was determined using the quasi-dynamic test method. It was found that the peak efficiency was 11% lower compared to a brand-new collector and that heat losses from the collectors made up half of the total heat losses of the solar field. The reduction in the peak efficiency was primarily caused by soiling as the collectors were exposed to outdoor conditions for one year without cleaning. Furthermore, the system’s annual performance was determined using a simulation model developed in TRNSYS and validated by comparison to measurement data. For 2020, the heat generation was 373 kWh/m2 (relative to aperture area) when operating with an outlet temperature of 90 °C and inlet temperature of 50 °C. Additionally, a sensitivity analysis of the annual heat generation was performed, varying the ground cover ratio, mean collector temperature, and soiling level. The sensitivity analysis showed that the heat generation was relatively insensitive to changes in the mean collector temperature, demonstrating that the collectors are suitable for generating heat above 100 °C, unlike flat-plate collectors.

Highly Efficient Solar Laser Pumping Using a Solar Concentrator Combining a Fresnel Lens and Modified Parabolic Mirror

Solar-pumped lasers (SPLs) allow direct solar-to-laser power conversion, and hence, provide an opportunity to harness a renewable energy source. Herein, we report significant improvements in end-side-pumped solar laser collection efficiency and beam brightness using a novel 1.5-m-diameter compound solar concentrator combining a Fresnel lens and modified parabolic mirror. A key component of this scheme is the off-axis-focused parabolic mirror. An original dual-parabolic pump cavity is another feature. To determine the dependence of the SPL performance on the distance between the focus and central axis of the modified parabolic mirror, several systems with different distances were optimized using TracePro and ASLD software. It was numerically calculated that end-side pumping a 5-mm-diameter, 22-mm-long Nd:YAG crystal rod would generate 74.6 W of continuous-wave solar laser power at a collection efficiency of 42.2 W/m2, i.e., 1.1 times greater than the previous record value. Considering the laser beam quality, a brightness figure of 0.063 W was obtained, which is higher than that of other multimode SPL designs with end-side pumping. Thus, our SPL concentrator offers the possibility of achieving a beam quality as high as that obtainable via side pumping, alongside highly efficient energy conversion, which is characteristic to end-side pumping.